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The nature of set- This is the first iron-processing site to be excavated in tlement associated with these pit sites requires further the tropical forest of Cameroon. The dates recovered research. In the former case, occupation in rela- ess by which iron technology replaced stone tools in tively large villages would be indicated, while the lat- southern Cameroon.
There is evidence than kilometers along the pipeline transect indi- for a considerable range of dates from different pits on cates that significant sedentary communities, probably some of the pit sites previously discovered, while the exploiting domesticated crops and also manipulating results from sites discovered during the course of wild resources including oil palm, were not confined to fieldwork along the pipeline right-of-way are complex.
These settlements were in fact a general Journal of African Archaeology Vol. The very low especially given the correspondence between the dis- density of material distributions in these sites renders tribution of pit feature sites and the modern distribu- only recent examples relatively detectable through sur- tion of Bantu languages in Cameroon.
Occupation of wooded savanna Older, large settlement sites with much higher ar- Primarily dry-season survey work in the wooded tifact densities are present in Chad, but are generally savanna and forest-savanna mosaic zones of encountered in sub-surface contexts. These sites, with abundant ceramics frequent detection of small surface sites than was the but no real stone industry, show evidence of signifi- case further to the south. Site densities during the cant settlement before the expansion of iron-working monitoring phase of pipeline construction were much ca bp see below.
A different settlement pattern more comparable. Relatively few top features along the edge of the escarpment. This substantial sites were found on poor lateritic soils and area occupies an intervening position between two swampland southwest of Doba in Chad, for example, rather different ecozones, with relatively open plains while habitation sites were more common within two — below and wooded plateau above, and also has a con- three kilometres of the permanent rivers in the re- siderable defensive potential.
Both of these sites have gion. The and other artefacts, sometimes extending over areas of only charcoal samples found on that site dated more more than a kilometer along the pipeline right-of-way. Settlement Iron-working sites in this region was quite mobile during the pre-colonial and colonial periods E. Brown, personal communica- If pit sites are perhaps the most striking archaeo- tion, , with villages being relocated periodically logical occurrences along the southern part of the to take advantage of fresh soils and during more re- pipeline route, iron-working sites are their equivalents cent periods to avoid attack by slave-raiding groups.
A total of 40 iron-working sites Such behaviour can still be seen in the study area to- were found in the course of CEP archaeological field- Journal of African Archaeology Vol. Nkonkonda Fig. Iron-working sites along the pipeline. Sites with small amounts of slag located in the comparatively well-watered area near such sea- on the surface or in excavation units are much more sonal water sources.
There is little evidence for do- common. There is substantial clustering of these iron- mestic architecture or habitation on these iron-working working sites in a number of areas along the pipeline sites, which supports limited ethnohistorical accounts right-of-way, in the Kouloulou — Kagopal and gathered among Sara communities in These areas offer ample supplies of lateritic ore necessary resources. The internal patterning of these and charcoal for iron processing, but it is unclear that sites, in both Chad and Cameroon, is also in agree- such resources are more prevalent around these site ment with the memories of informants, with furnace re- clusters than they are elsewhere along the right-of- mains paired with large slag heaps where waste from way.
It is likely that this clustering of sites indicates smelts was discarded. The same pattern exists in community-based specialization for iron working dur- Cameroon, both close to the Chad border and in the ing the past in this region, with iron being exchanged south. Small amounts of slag are found on habitation with neighbouring communities in the larger area.
Alternatively, teresting to note that this construction closely paral- slag may also have had entirely different ritual or me- lels the descriptions of pre-colonial furnaces given by dicinal uses, as is the case elsewhere in Africa Sara informants in Chad in At that site, a 12 m2 excavation yielded cul- processing sites in southern Chad.
The furnace tural deposits to a depth of 1. Two in situ smelting furnaces were discovered, been generally similar to that at Djaoro Mbama. This is the first time that well-preserved riod — bp. If these results are representa- smelting facilities of this kind and of this period have tive of the larger sample of iron-processing sites lo- been discovered in Cameroon, allowing insights into cated in southwestern Chad, they indicate an ex- the state of iron production technology early in the traordinary concentration of effort in iron working Iron Age.
They appear to be quite substantial struc- about years ago, in spatially demarcated areas. It is in- working in the periods between and after these peaks Journal of African Archaeology Vol.
Named sites along the pipeline route. ETA Beto and ETA are settlement sites dated to between and bp, contempo- As noted above, stone tool sites were most com- rary with the furnace sites around bp. Most of this material is made on local quartz- record. Expedient tool delimited areas in the OFDA and along the pipeline production techniques predominate.
The stone tools lo- route in Chad were heavily populated by iron-using cated are for the most part very casually made and are communities, with a significant increase in iron pro- not extensively shaped; most of these artefacts are un- duction again at — bp.
Population densities retouched or minimally retouched flakes and shatter, with may have diminished after that. The formed tools include both unifacial and coal to be used in the smelting process see also DIEU bifacial examples, although the latter are more common. It will require a great deal more field- work to test such hypotheses in eastern Cameroon and Such cultural material can probably be found southwestern Chad. Certainly many of remain preliminary.
At the same time, work to this point the mixed scatters of artefacts and naturally occurring has yielded very valuable data on Central African pre- quartz and quartzite shatter that we located extended history. There appears to be a much wider distribution dozens of metres beyond the limits of the pipeline of pit sites of the third and second millennia bp in the right-of-way. The fre- from different industries and dating from different time quency with which such sites were encountered along periods.
Formal tools located during fieldwork appear the pipeline transect suggests that substantial to be generally Middle Stone Age in technological af- populations lived in this area. Further analysis of the filiation, with the bifaces and cores especially the organic material from these pit sites may yield more pieces showing some evidence of use of Levallois information on the economic basis of the associated technique most characteristic of MSA archaeological settlements, and it remains to be seen whether the re- occurrences.
A number of MSA points were found, one gional differences in dates for these sites is supported at ECA, for instance, probably associated with an by further fieldwork. The late occurrences of macrolithic assemblages late-Holocene sequence that seems generally similar to at Ndtoua ECA , on basalt at Shum Laka in the that found on more northerly sites like Shum Laka.
The spatial A small number of surface sites with microlithic distribution of these iron-working sites may indicate components from southern Cameroon may date to the some regional specialization in iron working, while their Late Stone Age, but their resemblance to LSA occur- temporal concentration remains to be further studied.
Such materials have been recognized in a Archaeological heritage management programmes number of stratified sites, and these levels have been in sub-Saharan Africa face a number of challenges, dated at ECA Ndtoua Rock Shelter. These sites indicate the port Project can play an important part in addressing persistence of technologies associated with the LSA these challenges, but this requires support and coop- in the area until approximately bp, but unfortu- eration from many different quarters: national govern- nately we still know little about the chronology of ments, international financial organisations, multina- stone tool use in the forest.
A significant amount of analy- and infrastructure resources — and the very rich human sis on recovered archaeological materials remains to resources — available for research on the continent.
Nkonkonda Acknowledgements Dieu, M. Situation linguistique en Afrique centrale, inventaire preliminaire: le Cameroun. The authors would like to acknowledge the valuable assist- Eggert, M. Southern Cameroon and the settlement of equatorial rainforest: Early ceramics from fieldwork in ance provided by personnel associated with the and In: Lenssen-Erz, T.
Bantu expansions: Re-envisioning a central ExxonMobil Corporation. We want particularly ac- problem of early African history. International Journal of knowledge the help and interest of a number of African Historical Studies 34, Joey Tucker. We also wish to thank the editors of the In: Essomba, J. Journal of African Archaeology for their valuable as- Karthala, Paris, pp. The Management of Cultural very useful comments.
World Bank, Clist also provided comments and suggestions on this Washington. Herbert, E. Indiana University Press, Bloomington. References Holl, A.
In: Lanfranchi, R. Centres CCDP. The Project. Clist, B. Natural and Man-Induced Environmental Nsi 1, Changes in Tropical Africa. Archaeology in Gabon African Ar- University, Sapporo. Klieman, K. Bantu Clist, B.
To enhance the ability of isothermal analysis, the improvement of measurement apparatus to overcome the drawbacks of isothermal method need to be considered.
Hence, substituting equation 3. They can be classified roughly into the differential method and the integral method. The differential method requires the derivative of the measured mass-temperature curve with high signal to noise ratio. Smoothing can bias the calculation of kinetic parameters for a poor signal to noise ratio data. Integral methods overcome this disadvantage using the measured thermogravimetric data without differentiation.
Nevertheless, these methods are not applicable at very low or very high degrees of conversion . Although thermal analytical methods provide valuable information on pyrolytic kinetics, they cannot provide the nature and amount of volatile products formed during the thermal degradation of materials. For this reason, Evolved Gas Analysis EGA has been combined with the thermal analysis techniques to get more information on thermal degradation.
Obtained evolutions of volatile products lead to the prediction on product formation and product yield. Apart from pyrolytic reactors in thermal analytic apparatus, several reactor designs have been developed for kinetic study at high heating rate and for eliminating the effects from operating condition and heat and mass transport phenomena. In principle, TG curve from one heating rates is sufficient for these calculations but in practice, the experiment should include three or more different heating rates measurements for an accurate statistical manipulation and solving the compensation effect .
The feature of thermobalance should have the optimum position of a thermocouple to provide the actual temperature of the sample. Thus, its position should be located closed to sample. Also the temperature calibration is necessary to ensure that the equipment gives the actual temperature of the sample. The feature of a horizontal thermogravimetric analyser is shown in figure 3. Conesa, et al. This could result in the apparent shift in biomass pyrolysis kinetics.
Due to the low heat transfer, kinetic has been measured at relatively low operation temperature instead of the heating time of a particle. If the heat transfer effects cannot be neglected, the chemical kinetic model should be considered together with the heat transfer equations .
The heat flow to or from the sample depend on whether the process is exothermic or endothermic. The integral or area of the DSC peak indicates the proportion of the transition heat for a particular reaction and the change in heat capacity involves the enthalpy change of the reaction .
The apparent activation energy can obtain from the DSC data at different heating rates . In the simultaneous analysis approach, two methods are employed to examine the materials at the same time. One of these methods can identify the volatile compound produced during the analysis simultaneously.
For combined analysis technique, more than one method is applied to analyse the sample and real time analysis is not possible. Radmanesh, et al.
It was observed that the final total yield of gases increase but tar decrease by increasing the heating rate. Then they proposed a kinetic model which can predict the change of the gases yield at different heating rates.
Kinetic parameters were calculated based on parallel independent first-order reactions with a Gaussian distribution of activation energies. Each evolution peak was assumed to involve the respective precursor in the original biomass sample. Thus, each volatile species could evolve as one or more peaks independently. However, the model still needs further improvement by addressing the appropriate reaction mechanism, the mass influence, and the cross-linking competitive reactions.
Moreover, Banyasz, J. The kinetic analysis was based on the peak areas and the peak temperatures of calculated evolution profiles of main produced volatiles formaldehyde, hydroxyacetaldehyde, CO and CO2.
Due to the difficulty to separate lignin from wood, they applied specific ion fragment range — u. Bockhorn and co-workers [28, 30, ] researched the thermal decomposition of polymers under isothermal condition by similar technique applied in this work.
The evolved gas analysis by means of on-line mass spectrometry provided the evolution data for calculating the formal kinetic parameters. A good agreement between the formal kinetic parameters from isothermal measurement and the ones from non-isothermal measurement by TG was reported .
In addition, an advantage from isothermal method is that the change in mechanism can be determined. The Distributed Activation Energy Model DAEM has been used to model the evolution of individual pyrolysis product from different precursors in a set of simultaneous first- order reactions.
Rostami, et al. Thermogravimetry is appropriate for thermal decomposition of biomass at low heating rate but under flash pyrolysis at high temperature, drop tube, tubular reactors, screen heater, radiant heating techniques, and fluidized bed reactors are more suitable than TG. Heated-grid reactor has been used for studying pyrolysis kinetics of solid fuel materials at high heating rate . The samples are placed on the wire mesh, which is electrically heated and is connected to a thermocouple for measuring its temperature.
The mass loss can be recorded by gas analysis  or two measurements on a balance before and after the experiment . Due to their operation at high heating rate, the weight loss during heating period can be minimized.
Thus, the reactivity of sample is not changed before reaching a final temperature. The volatile products will be quenched at a cold gas phase to minimize secondary reactions. However this reactor needs to be used with some concerns. A fine powder is typically suitable as the particle size of sample should be small enough to avoid the temperature gradient and the amount of sample for each run is limited because of the restriction of the thermal load on the grid.
Also sample particles should be applied over the grid with the same small thickness layer evenly. Very small biomass particle about a few hundred micrometres are added together with inert gas stream or air to furnace at high temperatures.
Hence these small particles are heated up rapidly and this causes a short heat-up time compared to the reaction times which it can be determined as the isothermal during the degradation process. Downstream of the drop tube reactor is quenched with N2 and is collected and measured the weight [, , ].
This experiment is a time consuming procedure and introduces some errors from taking quenched products to the determination for the kinetic data.
The large particle size of sample may cause a discontinuous feeding of the solid samples; while the small particle size may create a problematic pneumatic transport. The thermal profile from this reactor is very narrow of isothermal conditions at only the centre of the reactor and lower temperature than the oven value due to the thermal dispersion from extremities effects.
Also the gas flow rate may influences to the thermal profile. The residence time can be measured only with a rough precision and at room temperature . Over the last five decades, the shock tubes have been applied to the study of aerodynamic and high temperature kinetic studies in both homogeneous and heterogeneous systems . The benefit on the kinetic study of the shock tube is the rate coefficient obtaining under diffusion free conditions because this reactor provides a nearly one-dimensional flow with instantaneous heating of reactants .
A shock tube consists of a uniform cross-section tube divided into a driver and driven sections. The driver section is high pressure with a low molecular weight gas and the driven section is filled with test gas at low pressure. The particle is heated using the energy contained in pressurized gas.
The mass loss is recorded using gas analysis . A tubular reactor is a simple flow reactor operating at constant pressure. This reactor is a cylindrical pipe of constant cross-section where the feed enters at one end and the product stream leaves at the other end. The lack of providing of stirring prevents complete mixing of the fluid in the tube which is the opposite assumption from that of the ideal stirred tank reactor. Composition is the same at all point in a given cross-section but changes along the axial coordinate of the tube.
The literatures on using tubular or closed-tubular reactor  for thermal degradation and kinetic studies have been published in bioenergy research . The progress of reactions can be measured from the withdrawn sample from the bed at different times. The feature of this reactor that biomass particles are mixing with bed material restricts the determination of decomposition rate at short residence times .
The produced gas flow can be analysed by evolved gas analysis connection, i. In addition, there are other types of reactor which have been facilitated in the thermal degradation researches, such as laminar entrained flow reactor , plasma pyrolysis [, ], closed loop-type reactor .
These factors on the thermal degradation kinetics are linked. At first in vaporization step, the flow of water vapour is controlled by diffusion and convective and diffusive transport. Then the chemical reactions of pyrolysis process occur. The heat changes from pyrolysis reactions and phase changes cause the temperature profile inside the particle. Volatile and gaseous products migrate from the solid across the heat-exposed surface and involve the heat transfer phenomena.
Three combined mechanisms of heat transmission inside the pyrolyzing solid are the conduction through the solid particle, the radiation from the pore walls, and the transmission through the gas phase inside the particle pores.
After volatiles leave the solid phase, char is formed by the change of physical structure of the reacting solid to develop a network of cracks, particle volume shrinkage, surface regression, and swelling [20, 23, ]. Biagini, et al.
For all materials and using all methods, the activation energy at low heating rate was found higher than that at high heating rate with respect to overall values. Haykiri-Acma, et al. Obviously, the higher heating rate shifted the main peak of DTG profile to the higher temperatures. It could be explained by the heat transfer inside the biomass particles. At low heating rate, a number of peaks can appear individually in small peaks.
When heating rate go higher, some of them overlap and form a unique large peak. The induction period at the initial stage of the weight change data from isothermal measurements shows the low velocity of decomposition which is attributed to the heating of the particle. The large particle size prolongs the induction period due to the longer time of heat transfer from outside to particles and within particles.
For small sample size, the large surface area improves heat and mass transfer. Thus, its fast heating rate causes more light gases and less char and condensate formation . The uniform radial product distribution would result from the neglected temperature gradient between the surfaces and centres of the small biomass particle .
On the other hand, the large particle size prolong the resident time of volatile molecules from primary reactions inside the solid particles that enhances the secondary reaction . These inorganic elements are available as oxides, silicates, carbonates, sulphates, chlorides and phosphates . Some of these inorganic elements act as a catalyst affecting the rate of degradation .
Results from studies on the effect of catalyst informed the enhanced formation of char and gaseous products and inhibited formation of the volatile products. Also, inorganic contents promote secondary reactions which break down higher molecular compounds to smaller ones.
Several inorganic matter have been studied their catalytic effect on degradation. Potassium K was found to shift the pyrolysis to a lower temperature and lower activation energies . In addition, sodium Na is another inorganic matter which was reported for its catalytic influence . Blasi, et al. The potential role of varied systematic errors in temperature measurement among the various thermobalances and the compensation effect are the reported explanations of these disagreements.
It has been recognized that different sets of kinetic parameters can describe similar conversion degree curves once a kinetic model has been selected but it is not necessarily that all of them have the same grade of accuracy . Flynn  reviewed that either the result of scatter of the experimental data, misapplication of kinetic equations, or errors in the experimental procedures can be the reasons for the presence of kinetic compensation effect when studying identical specimens under the same conditions.
Agrawal  also concluded that the inaccurate temperature measurement and large temperature gradients within the sample cause the compensation behaviour in the pyrolysis of cellulosic materials.
Recently, Wang, et al. Moreover, ,  and  reported evidence of compensation effect on their studies. There is the competition between the reaction heat demand and the heat demand for the limited heat supply. The factors affect to the thermal lag problem are heating rate, the placement of the thermocouple, the size of the sample, the composition of the carrier gas, and the endothermicity of the reaction [, ].
As external heating rate increases or low heat-transfer coefficients, the measured temperature may slightly higher than actual temperature and the effect on thermal lag increases . Thermogravimetric analysis is the most widely used technique for the study of cellulose pyrolysis. The understanding of total mass loss for global pyrolytic kinetics is generally intended to predict the overall rate of volatiles release from the solid and it can be applied to mechanism study.
The isothermal kinetic studies and high heating rate experiments showed the lower activation energy than the experiments with slow heating rates. Serious heat transfer limitations and associated temperature measurement problems were identified as the cause of this variation of kinetic parameters.
The decrease of Ea and log A values at higher heating rate was attributed to the higher impact on thermal lag. Table 3. More recently, Carpart, et al. From isothermal measurements, it showed the kinetics of nuclei-growth which was represented by the models of Avrami-Erofeev A-E and of Prout-Tompkins P-T type. From non-isothermal measurement, they simulated a model with two parallel reactions, one was related to the bulk decomposition of cellulose and another was related to the slower residual decomposition.
Approximately the activation energy for the decomposition of hemicelluloses is lower than that of cellulose but it is higher than the activation energy of lignin . Most of kinetic studies on hemicellulose pyrolysis carried on the non-isothermal condition by thermogravimetric analyser.
The two-step process from TGA curves has been observed [, ]. Hemicellulose presented two steps of decomposition. The difference in kinetic parameter values from different wood influences from the compositions of wood.
The reported kinetic parameters of hemicelluloses as a main component in wood have been published from several researchers. Some published kinetic parameters of hemicellulose are presented in table 3.
Cozzani, et al. A simple first-order kinetic model was applied to calculate its activation energy The majority of the available kinetic studies point to a poor fit of simple reaction models in the whole range of conversion and the change in mechanism cannot be detected. The discrepancy in the reported activation energies of hemicelluloses can be explained by the difference in sample composition, experimental setting, the mathematical method to analyse data, and the possible interference of the lignin decomposition .
The kinetic parameters obtained from simple model tend to be lower than those from the complex models.
In the review of Ferdous, et al. Recently, Murugan, et al. The causes of this wide range of reported activation energy are operating conditions temperature, heating rate, and the nature of carrier gas and the nature of lignin composition, functional groups, and separation method [49, ]. In addition, Jiang, et al.
They found activation energies of lignins were in the range of Ferdous, et al. The complex process of lignin pyrolysis was analysed by the distributed activation energy model DAEM. The small activation energy obtained from the fixed- bed reactor indicated the presence of mass and heat transfers effect.
The proper understanding of their thermal properties and reaction kinetics are crucial for the efficient design, operation, and modelling of the pyrolysis, and related thermochemical conversion systems for algae. Like the kinetic studies of lignocellulosic materials, most of kinetic studies in algae are based on the non-isothermal condition assessed by thermogravimetric analysers. Peng, et al. They observed that the devolatilization consists of two main temperature zones, lipid decomposition and other main components i.
The microalgae were devolatilized at lower temperature range than those of lignocellulosic materials, which was economically feasible. Also, Peng, et al  compared the kinetics of Spirulina platensis and Chlorella protothecoides microalgae. As the heating rate increased, the reaction rate in the devolatilization stage increased but the activation energy decreased. The reported activation energy for Chlorella protothecoides was Shuping, et al.
The iso-conversional method and the master-plots method were used for kinetic analysis. The master-plots method gave an Fn model nth-order as the most probable reaction mechanism.
While Li, et al. In both of these articles, researchers suggested that the thermal behaviour was influenced by compositions of biomass. The relationship between the apparent activation energy and pre-exponential factor could be explained by the kinetic compensation effect. It is often expected to describe a solid state decomposition by a single set of kinetic parameters and the isothermal and non-isothermal values are expected to be equal.
However, the nature of solid state processes is the multi-step reactions which contribute to the overall reaction rate that can be measured in thermal analysis. The complexity of thermal decomposition in solid samples is a cause of the variation in reported data. Moreover, there are several approaches to evaluate kinetic data. The model-fitting approach from a single heating rate is considered to give highly uncertain values due to its dependence on both the temperature and the reaction model.
Apart from the difference in computational methods, the kinetic parameter depends strongly on the experimental conditions, such as the inert flow rate, temperatures, atmosphere, and sample size.
The difficulty to measure a real sample temperatures and heating rates also cause the discrepancy in kinetic values. Thus, the kinetic study should be carried out at kinetically controlled conditions to minimize the uncertainty from experimental conditions and also the evaluation should be taken into account the multi-step mechanisms of the solid state decomposition. Proximate and ultimate analysis together with the thermal behaviour analysed by thermogravimetric technique of these three materials are given and discussed based on their application in thermo-chemical conversion process.
Whatman No. It is difficult to obtain a commercial hemicelluloses sample, thus xylan has been widely used as a representative of hemicelluloses of hardwood in pyrolysis study [, , , ]; although different physical and chemical properties have been found depending on the source material and production method. An alkali lignin powder Sigma Chemical Co. All samples without further treatments were stored in desiccators until use. Ten milligrams of sample were used for each measurement.
Each measurement was repeated three times to check the reproducibility. The results of proximate and ultimate analyses of three lignocellulose derived materials are given in table 4. This lignin sample was identified as alkali lignin which was isolated with alkali and precipitated by mean of mineral acids.
Thus, ash content in this kind of lignin is at high level. From elemental analysis, the lignin structure consists of a high level of carbon and low oxygen content compared to those of cellulose and hemicelluloses.
All samples contain very low nitrogen content which leads to low nitrogen oxide gases produced. Lignin was the only material showing the sulphur content which was considered from the production process. Sample and furnace temperature detectors of TG were calibrated by three standard metals Indium, Zinc and Aluminium before starting experiment to minimize the error from thermal lag.
The measurements of each sample were checked for the reproducibility by repeating three times. The thermogravimetric data of cellulose, hemicelluloses and lignin obtained by recording the history of weight loss of the samples as well as their derivative curves at different heating rates are presented in Fig.
Moreover, Fig. This effect is mostly related to the difference in heat and mass transfer of the sample particles externally and internally. At lower heating rates, sample particles were heated slowly, leading to a better and more effective heat transfer to the inside of the particles.
As a result of the more effective heat transfer, the sample decomposes promptly, enhancing the weight loss. Hence, at lower heating rates, more volatiles were produced than at higher heating rates. On the other hand, at higher heating rates, the temperature difference inside a sample particle is enhanced and then the residue at the end of the pyrolysis increased.
The shift of thermograms toward high temperature as the heating rate increases can be observed clearly in every sample. Table 4. The increase of reaction rates were at the same ratio with the increase of heating rates. The reason for this shift is also from heat transfer effect at high heating rate, the minimum heat required for depolymerisation is reached at higher temperature because of the less effective heat transfer than the low heating rate does.
Hemicellulose started decomposing at a lower temperature but the temperature range on decomposition was wider than did cellulose. Hemicellulose has the highest reactivity for thermal decomposition because its structure is random and amorphous with less strength.
In contrast, cellulose is a crystalline, long chain polymer of glucose units without any branches supporting the hydrogen bonding. Thus, more energy is required for depolymerisation of cellulose polymer as the main mass loss stage of cellulose comes later than that of hemicellulose. Lignin has heavily cross-linked structure of three basic kinds of benzene-propane units. Hence, the structure of lignin results in high thermal stability and is difficult to decompose. Volatiles produced from lignin occurred from the breaking down of different functional groups with different thermal stabilities.
This difference leaded to a broad range of decomposition in lignin . Alkali lignin had a high ash content which influences its pyrolytic behaviour. This difference is influenced from their different chemical structures. The thermal decomposition characters of each sample can explain the multi-step decomposition in biomass. Characteristics of these basic materials influence the mechanisms and kinetics of biomass decomposition. To understand the very complex pyrolytic behaviour of biomass, those of cellulose, hemicellulose and lignin are fundamental and important.
Further in this present study, these promising representatives of lignocellulosic main components will be used to analyse their formal kinetic parameter of pyrolysis process in Chapter 7. It is well-established that the main components lignocellulosic biomass are cellulose, hemicelluloses and lignin, while those of algae can be classified simply as protein, carbohydrate and lipid which present at various proportion depending on species, cultivation condition and harvesting process.
For effective utilization of algae in energy industry, more researches on the pyrolytic behaviour and kinetics are required. In this work, Chlorella vulgaris, freshwater green algae, are selected due to its fast growth rate, high environmental tolerance and easy to cultivate. This chapter will give the methods and results on characteristics of Chlorella vulgaris. Proximate, ultimate and mineral analyses, together with main components analysis are presented here.
The latter was done using a dual drum dryer GMF Gouda. Moisture content was calculated from the weight loss and represented water that may be physically present or chemically bound in the biomass.
The ash content was determined by burning 1. The existing commercial utilisation of thermochemical process on biomass has been developed and several new sites are on the investment plan in many countries .
Pyrolysis is an initial step of the thermal decomposition and it is carried out in the absence of oxygen at moderate temperature . Three forms of product from pyrolysis are permanent gases CH4, CO, CO2, and H2 , condensable volatiles light hydrocarbon gases and tars and solid residue, called bio-char.
The challenge of bioenergy production growth against the attempt to secure a safe and inexpensive food supply is the keystone of this alternative energy development. Recently, there are some articles reporting the influence of biofuel production development on the food price . To avoid a conflict with food production, aquatic biomass, both marine and freshwater algae become the potential biomass source. Also, they have high production yield and no demand on available arable soils.
Moreover, the alternative application of microalgae to reduce the CO2 emission for industrial processes or gas power plant offers more attractive opportunities. Interestingly, there are some reports which show that the bio- oils produced from microalgae have competitive potential as the fuels compared to bio-oil from lignocellulosic pyrolysis .
As a new biomass, algae are currently of research interest in many organizations. To develop algal biomass for commercial energy production, the understanding of their thermal behaviour and kinetics are necessary for the effective design and operation of the conversion units.
Several pyrolysis kinetic models have been reported and they can be classified into three categories: global reaction models, multi-component models, and multi-step reactions models. The global reaction model describes the overall rate of devolatilization in a single step. Their kinetic parameters are the average values for the whole complex scheme.
This single-step model fixes the mass ratio between pyrolysis products; therefore, the prediction of product yields based on process conditions is not feasible. Moreover, the pyrolysis process is too complicated to be described by a global apparent activation energy . Some proposed models suggest that the thermal behaviour of the main components and their relative contribution in the initial biomass can present the primary decomposition rates of biomass [11, 21, 22]. For lignocellulosic material, their thermal degradation is contributed to hemicellulose, cellulose and lignin; although, in a few cases, the decomposition of components is involved more than one reaction step, especially hemicellulose and lignin .
The total devolatilization rate is calculated by linear summation of the individual volatilization rate for each component and the released volatiles from these concurrent reactions are lumped into several groups . Most multi-component model can predict only the rate of weight loss. Thus, the additional measurements of the three product yields need to be taken into account in order to evaluate the related formation rates.
Furthermore, some studies reported the multi-step reaction models which the formation rates of individual product species are measured . Not only the different mathematic model evaluation, but also the nature of biomass and the experimental variables i.
Thermogravimetry TG is the most common technique to determine the kinetic of thermal degradation. The measured weight loss of samples with time or temperature provides the global thermal behaviour [24, 26, 27].
Due to the complexity of pyrolysis, the reaction mechanism may change during the process. Hence, other analytical techniques must be employed to detect and analyse the changes that occur in the chemical composition. These combined techniques provide more information on pyrolysis process which will lead to more understanding on the mechanism and kinetics.
Kinetic study can be carried out at two experimental methods, non-isothermal and isothermal method. In the former, the sample are heated up to a desired temperature at constant heating rate and in the later, the influence of temperature on the rate of weight loss is examined at several measurements at constant temperatures.
The advantage of isothermal measurements over non-isothermal measurement is that isothermal measurement gives the homogeneous sample temperature, while under non-isothermal measurements; the presence of the temperature gradient is due to the non-stationary heating condition causes from the heat conductivity and sample size.
Furthermore, the real sample temperature is very difficult to determine in non-isothermal measurements and also the rate equation from isothermal measurement is independent of temperature, as it gives opportunity to detect the change in reaction order or reaction mechanism .
However isothermal measurement requires several experiments at different temperatures which cause a longer experiment time and larger amount of sample. Another drawback is a certain extent degradation of samples before the system reaches a desired isothermal temperature . In last few decades, dynamic or non-isothermal kinetic study has gained more interest.
This measurement does not require a sudden rise in temperature as the isothermal measurement does. The advantage of non-isothermal analysis is that only a single measurement can provide a sufficient data for the formal kinetic evaluation over an entire temperature range. However, the non-isothermal techniques have received pointed criticism and its increased sensitivity to experimental noise as compared to isothermal methods [20, 32].
Reaching to this point, the important of kinetics on the application of biomass for biofuel production was highlighted. Unlike woody biomass, the published kinetic parameters of microalgae samples are limited and different from species to species.
It has been recognized that the thermal behaviour of microalgae is different from that of lignocellulosic materials because of the difference in basic compositions. Thus, more work on the kinetics of microalgae needs to be studied in both isothermal and non-isothermal measurement. The pyrolytic behaviour of Chlorella vulgaris has been evaluated in order to assess their potential for bioenergy and as a supply of chemicals by a wide range of analytical instrument.
A preliminary pyrolysis in a pilot-scale reactor is carried out to investigate the process performance and qualities of products. New developed pyrolysis micro-reactor coupled with Mass Spectrometer Py-MS will be employed and assessed its potential as a technique for isothermal kinetic analysis.
Isothermal analysis will be starting with the kinetic evaluation of polyethylene and lignocellulosic materials cellulose, hemicellulose and lignin to assess the equipment and procedure before applying them to Chlorella vulgaris sample. By assuming the overlapping of independent, pararell, nth-order reactions of several pseudo-components in the raw microalgae, a reaction model will be presented in a multi-component model.
The model will take into account the different main components in microalgae sample, their thermal behaviour and individual evolved gases produced during pyrolysis process.
Also, the developed procedure to utilize raw data from TG-MS data for kinetic evaluation is well demonstrated in this thesis. Controversy from other authors who only report the kinetic data from non-isothermal conditions for the thermal decomposition of algae, this work might be the first report to present the isothermal kinetic results of microalgae.
Moreover, there are no any accessible articles presenting the non-isothermal kinetic analysis of microalgae by multi-component approach before. The objectives of this work can be summarized as: 1. To study pyrolytic behaviour of Chlorella vulgaris and to investigate the formal kinetic parameters in term of apparent activation energy, pre-exponential factor and apparent reaction order of Chlorella vulgaris under isothermal and non-isothermal conditions. To assess the potential of Chlorella vulgaris as a biofuel and chemicals source by various analytical instrument and by a pilot—scale intermediate pyrolysis reactor in terms of applicability and qualities of products.
To evaluate the potential of a new developed Pyrolysis-Mass Spectrometry Py- MS technique for isothermal kinetic analysis. To examine the formal kinetic parameters of polyethylene, cellulose, hemicellulose and lignin from isothermal measurements.
To demonstrate the developed procedure to employ raw TG-MS data for non- isothermal kinetic analysis. The following topics and contents are contained within the Chapters as set out below: Chapter 1 This current chapter presents an overview and motivation for the work. The objectives and the outline of this thesis are also given in detail.
Chapter 2 The general information on biomass resource both lignocellulosic materials and microalgae biomass is presented in this chapter.
Moreover, the chapter reviews the pyrolysis reactor which is available at European Bioenergy Research Institute EBRI , together with the pyrolysis process and its products.
Chapter 3 The critical review on chemical kinetics, thermal degradation kinetics, isothermal and non-isothermal kinetic measurements, influences on kinetic measurement is detailed in this chapter. Also, the literature reviews on published kinetic parameters of lignocellulosic component cellulose, hemicellulose and lignin and algae are well presented. Chapter 4 The description of lignocellulosic materials cellulose, hemicellulose, and lignin and the characterisation methods, together with their results and discussion are given in this chapter.
Chapter 5 The characteristics of Chlorella vulgaris as the selected microalgae sample for this work are described in term of basic components, proximate analysis, elemental analysis, functional groups and volatile products from lab-scale pyrolysis. Chapter 6 The results and discussion of a preliminary experiment by a pilot-scale intermediate pyrolysis Pyroformer with Chlorella vulgaris pellets is presented here. Chapter 7 This chapter presents the results and discussion of isothermal kinetic study of polyethylene, cellulose, hemicellulose, lignin, and Chlorella vulgaris.
Also, there is the discussion on the potential of the experimental set-up for the isothermal kinetic measurements. The results and discussion on non-isothermal kinetic study of Chlorella vulgaris are also well detailed.
Furthermore, the discussion on the comparison of isothermal and non-isothermal kinetic parameters on Chlorella vulgaris pyrolysis is revealed.
Chapter 9 The final chapter of the thesis discusses the conclusions derived from this research and highlights the key achievements on kinetic analysis. Also, some recommendations for future works are given at this chapter.
As one of these conversions, pyrolysis is simply defined as the chemical changes occurring when heat is applied to biomass in the absence of oxygen. Also, pyrolysis is viewed as the fundamental chemical reaction for gasification and combustion processes. With varied end-uses, the pyrolysis process can be carried out as slow, intermediate or fast pyrolysis. The products of biomass pyrolysis are a mixture of gaseous, liquid, and solid products depending on the operating conditions and the biomass feedstock.
The combustion of fossil resources such as mineral oil and coal has contributed to the increase in the proportion of carbon dioxide in the atmosphere which outweighs carbon dioxide uptake through the carbon cycle. The carbon is trapped in the carbon chain via photosynthesis in plants and released to the atmosphere when vegetable or animal biomasses decompose.
The concept of utilising biomass as solid fuel is similar to the carbon cycle but the period of carbon dioxide release in the combustion of biomass is much shorter than that of the long geological periods required for gas, coal and oil formation. Biomass generally refers to the organic materials from plants or animals based on carbon, hydrogen, and oxygen, often nitrogen, sulphur and also small amount of other atoms, including alkali and heavy metals.
Biomass is generated through photosynthesis in plants. These processes take place in the chloroplast see Fig. Traditionally, biomass can be used directly by burning for heating and cooking or indirectly by converting through conversion technologies into gaseous and liquid fuels. Due to the various forms of fuel from biomass, they can be utilized for variety of needs, such as generating electricity, upgrading to fuel vehicles, and providing process heat for industrial facilities.
Biomass fuels are becoming a more common alternative fuel source to fossil fuels as the conventional energy prices rise. Sources of biomass can be forest biomass, energy crops i. The proportion of these components depends on the biomass species and there are differences between hardwoods and softwoods.
For example, different types of wood have different constituent proportions as shown in table 2. Table 2. Purity, the degree of polymerization DP , and the moisture content influence the properties of cellulose samples . The common chemical formula of cellulose is represented by C6H10O5 x.
A compound of two glucose molecules called cellobiose is the basic building block see Fig. The intra- and inter- molecular hydrogen bonds from the substituent -OH and -CH2OH give cellulose high strength [33, 35, 40]. Hemicellulose is another component in the cell wall together with cellulose and lignin. Unlike cellulose, hemicellulose is a short chain about monomeric units with branched structures.
The low degree of polymerization and amorphous structure make hemicellulose have less strength than the crystalline structure of cellulose. The general formula of hemicellulose is C5H8O4 x . Hemicellulose is soluble in weak alkaline solutions and it is decomposed during heating more readily than cellulose . Hemicellulose consists of sugar units and the most abundant hemicelluloses are xylans and glucomannans.
In hardwoods and grasses, the major hemicelluloses are xylan, while in softwood the major hemicelluloses are galactoglucomannans . The chemical structure of xylan is shown in figure 2. Lignin interspersed with hemicellulose is located surrounding cellulose microfibrils, conferring mechanical strength to the secondary cell wall of plants and some algae . Different proportion of three monolignol monomers  and the distribution of different linkages  depend on the source of original biomass and the isolation methods.
There are two procedures to obtain lignin which are given the conventional name after the method of separation. Another procedure is based on the solubilisation of lignin by specific solvents or reagents.
For example, sodium hydroxide or a mixture of sodium hydroxide and sodium sulphide is used for the treatment of wood and produces the alkali lignin which is then precipitated with sulphuric acid.
This lignin is known as Kraft lignin. Organosolve lignin is obtained from the organosolve process in which the lignin is dissolved in the organic solvent such as methanol or ethanol which hydrochloric acid as a catalyst [38, 45, 49].
Algae can be grown in diverse habitats from permanent snow to deserts, such as snow banks, rock and soil, tree trunks  but commonly they are found in fresh water i. As algae have photosynthetic pigments, they are the producer of organic matter and oxygen in the sea as do land plants on land. Algae can be microscopic or macroscopic, motile or immotile, unicellular or multicellular plants which show a range in size from the very small about a micrometre to form of seaweeds which have size more than a metre .
Algae are classified into many divisions by means of their pigmentation, life cycle and basic cellular structure . The examples of algae classes and their cytological characteristics are presented in table 2. The compositions are often reported in terms of proteins, lipids, and carbohydrates as the major groups of compounds which are abundant in algal cells. Roughly the cell wall carbohydrates can be divided into water-soluble materials and water-insoluble materials.
The former group have a less complicated molecular structure and the latter group is suitable as skeletal materials. The carbohydrates of algal cell walls include cellulose, mannan, xylan, alginic acid, fucinic acid and chitin . Siddhanta, et al. Mannan and xylan have been found in red and green algae . Alginic acid together with fucinic acid has been found as the major constituents of the cell walls of brown algae . The amorphous or continuous matrix in the ultrastructure of cell wall is dissolved partly as the water- soluble fraction and partly in KOH solution as the hemicellulose fraction.
Mucilages D- glucose, D-mannose, D- and L-galactose, L-rhamnose, D-xylose, L-arabinose, D- glucuronic acid, D-galacturonic acid, L-fucose, D- and L-3, 6-anhydrogalactose, and 6-O- methyl-D- and L-galactose, sulphuric acid and pyruvic acid are the mainly constituents of the continuous matrix of cell walls [62, 67].
Glucose is the principal sugar, while varying proportions of rhamnose, fucose, ribose, arabionose, xylose, mannose and galactose are detected . OH Fig. While brown algae have laminarin and manitol  and red algae have floridean starch as their main storage products .
Lipids Lipid is another important component in algae cell. Non-polar lipid monoglycerides, diglycerides, triglycerides, and free fatty acids are available as storage products. The polar lipid phospholipids and galactolipids , like those of chloroplast of higher plants, are largely surfactant molecules which function both as structural elements and as metabolites in the photosynthetic organelles.
The fatty acids of algal storage occur in range from C12 to C24, thus the common saturated straight chain fatty acids of vegetable oils such as lauric C12 , myristic C14 , palmitic C16 and stearic C18 are found in algae. It is rare reported the appearance of branched-chain fatty acid. For Chlorella vulgaris, the lipid compounds were found as Monogalactosyldiglyceride, Digalactosyldiglyceride, Phosphatidylethanolamine, Sulphoquinovosyldiglyceride, Phosphatidylglycerol, Phosphatidylcholine, and Phosphatidylinositol.
Yoo, Chan et al. The structure of some lipids and fatty acids available in Chlorella vulgaris are shown in Fig. The crude protein figure is obtained by hydrolysis of the algal biomass and estimation of the total nitrogen which results in an overestimation of the true protein content because proteins are not the only source of nitrogen.
However, normally protein is the main component of nitrogen fraction. Other protein estimation procedures are the method after Lowry and Biuret method which based on colour reactions with defined protein content without reacting with other nitrogen-containing compounds .
Therefore, the mass cultivation of microalgae requires carefully controlled conditions to produce optimal yield. The large-scale cultures are practically maintained outdoor because they have the advantage of available sunlight.
These conditions are more appropriate for countries or regions with high solar radiation . As the light source is the limiting factor, the artificial light sources like fluorescent lamps can be used in the pilot scale of microalgal cultivation .
For an efficient and economical photo-bioreactor, the selection of a light source as a key design challenge needs to consider both its spectral quality and intensity. The ability to absorb the solar energy of microalgae in mass cultivation is governed by several factors, including cell density, the length of the optical path of the system, the optical properties of the microalgal cells and rate of culture mixing . Carbon dioxide fixation of microalgae is one of important factors for algae cultivation.
Besides microalgae absorb free carbon dioxide from the atmosphere as a carbon source for photosynthesis from atmosphere, they can gain benefit from the fixation of CO2 in discharge gases from industries and power plants .
Normally the ability of diffusion rate of CO2 from the air into the water is too slow to replace the CO2 assimilated by rapidly growing algae. Thus, the additional CO2 must be applied to cultivation medium to ensure satisfactory growth . Nutrients are another factor for natural growth of microalgae. The main nutrients are nitrogen, phosphorus, and also minor nutrients as silicon, potassium, sodium, iron, magnesium, calcium and some trace elements such as copper, manganese, zinc .
After carbon, nitrogen is the most important nutrient contributing to the biomass production. Some algae can fix nitrogen from the air in the form of nitrogen oxides . Under nitrogen limitation or starvation, there is the discolouration of the cells because the decrease in chlorophylls and the increase in carotenoids, also there is the accumulation of organic carbon compounds such as lipids and carbohydrates depending on the algae species [83, 84].
Although phosphorus in algal biomass is in small amount, it plays an important role as a growth limiting factor. Three main designs of mass cultivation of algae can be classified as the open system, the closed system and co-process system utilising the carbon source from industrial waste. The carbon dioxide fixation is mainly from the atmosphere but an external CO2 supply can be installed to enhance the productivity. The advantages of open ponds over closed system are that they are easily to construct and are low cost.
Also, they need less energy supply by using natural light energy from the sun . However, open ponds have some limitations which influence the production. The low CO2 diffusion, poor light utilization, and inefficient mixing cause lower productivity compared to the closed system.
Moreover, due to the possibility of contamination or pollution from other algae and heterotrophs in open pond, suitable algal species should able to grow under highly selective environments . The photo-bioreactor Fig.
For indoor closed system, the artificial light sources are chosen at a suitable intensity. Co-process with waste treatment This system is to combine the algal cultivation with the carbon dioxide emission mitigation and wastewater treatments. The major driving forces of these designs are the removal of CO2 from the atmosphere, capturing or utilizing the CO2 from fossil fuel combustion, and reducing the cost of nutrients.
This algal biomass can be converted efficiently into biofuels with high productivity and low-cost cultivation . While the CO2 fixation from the atmosphere is limited by low CO2 concentration in air, the mitigation of CO2 emissions from power plants achieves higher yield because of the higher CO2 concentration .
The benefits from utilizing waste water treatment process to algae production are the saving of nutrients cost and the minimizing of the freshwater use for algae cultivation.
Some preliminary growth studies indicated both fresh water and marine algae have a potential in waste waters treatment [92, 93]. Microalgae have potential to remove nitrogen, phosphorus, and metal ions from wastewater  and CO2 from industrial exhaust gases; however these applications can only be achieved with a limited range of algae which are tolerant of the extreme conditions.
It is difficult to directly compare the performance characteristics of each mass cultivation system because they have different advantages and disadvantages. The choice of system depends on the production costs, value of the desired products, location and production quantity. Hence, the production yield of microalgae is higher in comparison to terrestrial plants . Thus, they can be produced all year round . Figure 2.
Biodiesel from algae oil has main characteristics quite similar to petroleum diesel . Therefore, they do not compete with food production .
This process demonstrates an improved method for thermal conversion of ash-rich biomass as microalgal biomass and this process also presents the combination of microalgae into the bioenergy area effectively. It is the integration of different processes such as algal biomass production, biogas units, pyrolysis processes, gasification processes and heat and power generation plants.
Pyrolysis vapours are high quality and highly energetic, dust and tar free which are suitable to combine with heat and power CHP use after a gasification step. Char produced from intermediate pyrolysis in BtVB process is suitable for further applications such as combustion, carbon sequestration and soil re-fertilisation. The varied sized feedstock can be applied into intermediate pyrolysis; char can be separated from vapour easily. Moreover, various types of biomass may be introduced to this process.
Ash- rich biomass, like microalgae, is also possible for use in the intermediate reactor. Exhaust gases from biogas plants and from gas engines are transferred to algae plantation as a fertilizer. Apart from the raw microalgae biomass, algae with high oil content can be extracted by mechanical or solvent extraction for biodiesel production.
Although microalgae biomass is main feed, other regional feedstocks can be used together with algae during the winter time, when algae production slows down. The BtVB process offers closed loops of fertiliser recycling. Residues from the biogas units may be used as a fertilizer in algae plantation. The high ash content microalgae are processed through thermal conversion techniques and yielded a by-product with high ash content solid phase.
The mineral matter in pyrolysis char is used for the energy crops as fertilizer and at least part of char may be extracted with water to recover mineral elements such as potassium, phosphates, nitrates and silica and then feed this mineral solution into microalgae cultivation system as a growth fertilizer. Moreover, the aqueous phase of two-phase liquid products which is rich in inorganic matter may be added as a fertilizer to algae plantation and it can be considered as the closed water loop as well.
In addition, the exhausts gases from engines are taken to algae medium as another source of fertilizer. Chlorella vulgaris have a simple life cycle with high reproductively rate. Their cells are divided into two or four non-motile daughter cells and enclosed for a little while within the parent cell wall . When the parent cell wall breaks, daughter cells are released into the medium. For decades, Chlorella vulgaris has been widely available in the food industry.
They also show great potential for bioenergy applications due to their high growth rate and high oil content. They can be cultured under autotrophic and heterotrophic conditions . The carbon dioxide concentration, nitrogen depletion, harvesting time, and also the method of extraction are the influences to the lipid content and the lipid compositions. The lipid content in Chlorella vulgaris increases when the nitrogen concentration decreases and the CO2 concentration increases [73, ].
These proposed bio-sorption potentials of Chlorella vulgaris lead to their biomass production for biofuels combined with wastewater treatment as well as their solvent tolerance, acid tolerance and high CO2 concentration tolerance  support their application to water treatments and CO2 fixation. It mainly consists of combustion, gasification, and pyrolysis process. Each gives a different range of products and uses different equipment configurations operating in different conditions.
Combustion process is well-defined technology and generates environmental concerns. Pyrolysis becomes an interesting conversion technology because its efficient energy production, easily stored and transported products in the forms of liquid fuels and solid char, and the wide range of produced chemicals .
Pyrolysis is thermal degradation in the absence of oxygen and it is a fundamental step in combustion and gasification followed by total or partial oxidation of the primary products. High temperatures and long residence times are suitable for gas formation. The carbonisation process at low temperature and long residence times are the preferred conditions for char formation, whereas pyrolysis promoting the liquid production occurs at medium temperature with short residence times .
Based on the operating conditions, the pyrolysis can practically be divided roughly into three groups as conventional pyrolysis or slow pyrolysis, intermediate pyrolysis, and fast pyrolysis. The key parameter classifying them is the residence time of solid phase within the reactor.
Gas phase residence time for fast and intermediate pyrolysis is kept below two seconds. Also increase units for grounding installed other than in trench, i. Per Approx. Of 1, O. For wire and terminations, see applicable section. Installation units include hauling up to two 2 miles. Above units include necessary brackets and fasteners to mount transformers to existing pole.
N-Haz unit — Cable with Jacket only. Div-2 1 unit — Cable with Jacket and Shield. Div-2 2 unit — Cable with Jacket, Shield and Jacket. ANODE 8 55 2. ANODE 8 90 2. ANODE 8 3. ANODE 8 4.
All Anode work hours are based on typical installation at or near the surface. For deep groundbed installation add work hours as required by depth. See Means, Richardson or other recognized estimating publications. For Cadweld Connections: Cable-to-Cable, use 3. Cable-to-Pipe, use 3. MM SQ. Transducer 4. Indicating Switch 4. Safety Element Rupt. Disc 2. Gauge 3. Or Pneu. All work hour units in the Install column include unload, storage, specification verification, handling to erection site and installation of device, unless otherwise indicated by note 6.
All other activities for the Install column see note 1 are included in the Control Systems account section These installation hours are for individually shipped components. Typically these devices are furnished pre-mounted to an associated Control Valve, therefore no installation labor is required.
To verify installation requirements, consult Control Systems lead engineer. For any activities that are not included in this section, see Means, Richardson or other recognized estimating publications. Panel mounted devices are typically pre-installed by the panel vendor, therefore no installation labor is required.
If installation is required, see note 2. All work hour units in the Install column include unload, storage, handling to erection site, panel cutout and installation of device. Threaded fittings for Air Supply Bulks include handling, cutting, threading and joint make-up.
Work hour units per LF for Tubing are for wall thickness up to and including 0. For heavier wall tubing, increase work hour units proportionally. Tubing fittings for Process Bulks include handling, cutting, deburring and joint make-up. Any additional supports required are not included. For Non-Fireproofed column, use 4. SP Near White Blast Cleaning Blast cleaning nearly to white metal cleanliness until at least 95 percent of each element of surface area is free of all visible residues for high humidity chemical atmosphere where high cost of cleaning is warranted.
SP-5 White Metal Blast Cleaning Removal of all visible rust, mill scale, paint, and foreign matter by blast cleaning by wheel or mozzle dry or wet using sand, grit, or shot for very corrosive atmosphere where high cost of cleaning is warranted. There are no averages that apply. For a comprehensive listing of square feet per lineal foot for various structural shapes and sizes, see Richardson. The LIGHT structural steel category includes flange, channel, tee and angle shapes; ladders; cages; plate; grating; and other miscellaneous steel items.
Pipe diameter to square feet conversion based on pipe O. Vessel square footage calculation: Shell: greatest circumference times straight length or height Elliptical heads noncircular — most common is a ratio : greatest diameter squared squaring provides coverage for the elliptical shape Hemispherical heads circular : diameter squared times pi 3.
For removal of paint coatings, multiply the appropriate work hour unit above times 3. Disposal of material generated during the removal process is not included. Field painting is typically a subcontract item. Applications below minus degrees F are termed cryogenic; those above degrees F are termed refractory; these categories are not included in these work hour units.
The use of insulation materials to absorb noise emitted from piping and equipment is classified as noise abatement; this application is not included in these work hour units. The use of whole sizes for HOT and half sizes for COLD was done intentionally to emphasize the differences between their respective applications. For any thickness required that is not listed, simply use the midpoint between the lower and higher thickness columns.
For all types of HOT Pipe insulation Glass Fiber, Mineral Wool and Calcium Silicate , the work hour units are based on the following erection method: Pipe cover is secured with gage wire on 9-inch centers. For all types of COLD Pipe insulation Cellular Glass and Polyurethane , the work hour units are based on the following erection method: Joints are buttered with joint sealer.
Pipe cover is secured with fiberglass tape on piping 4 inches OD Outside Diameter and smaller spaced on 9-inch centers. For all types of HOT Equipment insulation Glass Fiber, Mineral Wool and Calcium Silicate , the work hour units are based on the following erection method: Shell cover blanket or block is applied with staggered joint arrangement. Top and bottom edges are securely tied over support rings with wire on inch centers.
Vertical and horizontal seams are laced together by interlocking the wire mesh and with wire ties where necessary. The insulation is secured in place with bands spaced on inch centers. Head cover is shaped so that all sections closely fit the contour of the head and are laced together with wire, or are secured with bands on inch centers at tangent line. Unexposed head cover is secured with wire to insulation supports provided by the vessel manufacturer.
Weatherproof jacket on vertical equipment is supported on S-clips spaced on 4-foot centers. The jacketing for vertical and horizontal equipment is secured with bands spaced on inch centers with one band at each circumferential lap. On vertical equipment, band loops are included on each band to prevent vertical movement. For all types of COLD Equipment insulation Cellular Glass and Polyurethane , the work hour units are based on the following erection method: Shell cover block is applied with staggered joint arrangement.
Joints are buttered with joint sealer. In double layer applications, the inner layer is applied without joint sealer. Each layer is secured with bands on inch centers. Outer layer joints are offset from inner layer joints.
Vapor barrier is outer layer only. Joints are sealed with a foil-to-mylar 3-inch wide strip applied over the vapor barrier. Head cover is shaped so that all sections closely fit the contour of the head. Each band is equipped with one breather spring. Vessel square footage calculation: Shell: greatest circumference including insulation thickness on both sides times straight length or height, plus one foot at each end.
Elliptical heads noncircular — most common is a ratio : greatest diameter including insulation thickness on both sides squared squaring provides coverage for the elliptical shape Hemispherical heads circular : diameter including insulation thickness on both sides squared times pi 3.
For removal of insulation, multiply the appropriate work hour unit above times 0. Field insulation is typically a subcontract item. Typically, it is more accurate to develop demolition hours from a crew basis methodology, due to the potential volume fluctuations in any given category. Thus, the use of the units below could over- or under-exaggerate the true effort required. Also, the categories below represent only those areas in which there has been sufficient Fluor Daniel history to support their inclusion in this manual.
For any activities not listed below, consult the appropriate erection work hour section for use as a guideline as well as consulting the appropriate construction department personnel. Poly, 2 X 4 Frame 0. Erect and dismantle Masonry minimum reinforcing 0. Steel Frame Light Wood Framing, Joists total ceiling area 0. Roofing — built up with gravel 0. Roofing — built up without gravel 0. Roofing — Metal 0. Metal Decking 0. Metal Siding 0. Metal Siding — New Penetrations 0. Drywall one side only 0.
Work hour units include flame cutting of pipe only. If required, see Means, Richardson or other recognized estimating publications. It covers mechanical completion, turnover, commissioning, startup, performance testing and final acceptance. This section does not contain all items required to perform field checkout, and is not intended for such use. Where Fluor is the Managing Contractor, a further breakdown may be needed.
Requirements in these final phases vary widely from contract to contract and specific contractual provisions have precedence over material herein. The Project Manager and the Construction Manager must be familiar with the requirements in their particular contract related to these final phases and plan and prepare for their execution well in advance of the completion of construction. The Proposal Manager must see that the scope of work and the estimate both cover these final phases of the work, when applicable, and are consistent with one another.
Turnover is the process of transferring principal responsibility of the plant, unit, or any part thereof, from Fluor to the Client. This activity generally involves formal transfer of care, custody and control to the Client. Commissioning consists of activities associated with the operation of items of equipment or facilities in preparation for plant startup and introduction of feed stock. It means all work necessary to energize the equipment, normally performed by Fluor or subcontractor prior to turnover to the Client.
Final Acceptance is the documentation that the work under the contract has been completed and is accepted by the Client. Incomplete work and deficiencies, if any, will be identified with the declaration of mechanical completion. Any completed unit or definable entity may be agreed to be mechanically complete independently of the status of the remainder of the work. It is a requisite to mechanical completion that all equipment, piping, instrumentation and electrical systems be installed.
It is desirable that all specification required adjustments and tests for which the construction crew is responsible be completed prior to declaring mechanical completion. For electrical systems, all tests, relay setting and checkouts must be completed prior to energization.
However, some activities require that equipment be hot, energized, or actually running, so it is usual to retain a small crew of millwrights, electricians and others to accomplish that work after mechanical completion under the supervision of the Client during the commissioning or startup phase. Usually, mechanical completion is agreed upon while there is still some insulation and painting to be done, the area must still undergo final cleanup, scaffolding and temporary structures must be removed, and the construction crew and equipment must be demobilized.
The mechanical checkout is conducted by the construction group and usually verified by members of the Client team. It should include a review of reports of tests conducted by the construction group and subcontractors such as pressure tests, electrical measurements, loop checks, and rotational direction checks to assure that all items have been covered.
Detailed inspection tours should be made to determine that: features affected by flow direction such as meters are properly oriented; facilities for by-passing, blocking and blinding are properly located; temporary blinds and other provisions required only for testing have been removed; and any other mechanical condition which may delay or complicate the startup has been properly accommodated.
For some contracts, a licensor may be involved in checkout. It is a line-by-line, feature-by-feature check of the installation against the mechanical flow sheets and thoroughness is essential to minimize commissioning and startup difficulties and delays. It must be conducted prior to mechanical completion so the construction crew may correct any discrepancies uncovered.
It is generally advantageous that mechanical completion be agreed upon as early as practical, but it is a definite disadvantage to have any appreciable construction personnel finishing up construction work during commissioning or startup operations.
The Project and Construction Managers must consider both factors before requesting or agreeing to a declaration of mechanical completion. Notice of mechanical completion is usually formal notice to the Client that commissioning operations can commence.
TURNOVER Turnover is the sequence of events leading to transfer of principal responsibility for a unit or system from the construction crew to a Client commissioning or startup crew. Under many contracts, this is the point at which transfer of care, custody and control is made to the Client. Transfer of care, custody and control of work done by subcontractors must be done as specified in the subcontract terms.
Insurance coverage may be altered at this point and certain payments may also be dependent thereon. The Project Manager must see that any such matters related to this point of progress are properly administered. It may include final checkout and cleanup, run-ins, charging of catalysts, flushing, purging, and energizing systems.
General responsibility for this phase of the work will be established by the contract, but it is most important that the make-up of the crews for each activity be established early and that responsibilities for specific functions be agreed upon and established.
Flushing of the process equipment and piping with oil water or other liquids in Chemical plants , and blowing out of air and steam lines to remove dirt, welding slag and other construction debris will reduce startup difficulties.
The run-in of mechanical equipment, whether conducted by Fluor or Client crews, is an important prelude to startup. These operations are the responsibility of and accomplished under the direction of the Client. Thorough planning and preparation are essential to a successful startup. Preparations should include a review of prior documentation to insure that mechanical and flowsheet checkout occurred prior to mechanical completion, that the equipment and piping has been thoroughly flushed, and that the commissioning phase is complete.
With thorough preparations having been made, the introduction of feed stocks, lighting-off of fires, and initiation of circulation can proceed. The Operating Manuals of the process designer and of vendors afford detailed instructions for each step of the startup, and the startup crew must become intimately familiar with them well in advance and during dry-runs and run-ins.
The startup should proceed in orderly steps and with deliberate speed, with all feasible checking between each step. Performance tests may not be required under all contracts. Performance tests, when required, are prerequisites to final acceptance, and often to final payments to Fluor. Frequently, there is little or no incentive for the Client to expedite performance test runs and the Project Manager must be diligent in his efforts to get them successfully completed.
It is necessary to take confirming data during the tests. Critical instruments should be calibrated immediately prior to the test run. There should be prior agreement on what data will be determined and reported, as well as the condition under which the test will be conducted.
The methods of taking and analyzing samples often prove critical to the success of a test run. The means of calculating and evaluating results should also be agreed upon in advance. Portions of the work may be subject to individual letters of acceptance if the Client wishes to take control of them in advance of overall completion.
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