Co-pyrolysis of petroleum based waste HDPE,poly-lactic-acid biopolymer and organic waste

Waste pyrolysis is widely investigated, but less information is available about their co-pyrolysis. The present paper discloses the waste pyrolysis and co-pyrolysis in batch reactor at 400 °C, 450 °C and 500 °C. The effect of the raw materials and temperature to the product was investigated. Product yield was increased and the quality (composition, contaminants, etc.) improved by co-pyrolysis. Gas and pyrolysis oil yields increased as function of temperature. Higher ratio of organic waste/petroleum based plastic waste resulted in lower yields of volatile hydrocarbons. Concentrations of oxygen containing products and contaminants are significantly changed with temperature or adding of HDPE into raw materials.     

Thermal and catalytic pyrolysis of a synthetic mixture representative of packaging plastics residue

A synthetic mixture of real waste packaging plastics representative of the residue from a material recovery facility (plasmix) was submitted to thermal and catalytic pyrolysis. Preliminary thermogravimetry experiments coupled with Fourier transform infrared spectroscopy were performed to evaluate the effects of the catalysts on the polymers’ degradation temperatures and to determine the main compounds produced during pyrolysis. The thermal and catalytic experiments were conducted at 370°C, 450°C and 650°C using a bench scale reactor. The oil, gas, and char yields were analyzed and the compositions of the reaction products were compared. The primary aim of this study was to understand the effects of zeolitic hydrogen ultra stable zeolite Y (HUSY) and hydrogen zeolite socony mobil-5 (HZSM5) catalysts with high silica content on the pyrolysis process and the products’ quality. Thermogravimetry showed that HUSY significantly reduces the degradation temperature of all the polymers—particularly the polyolefines. HZSM5 had a significant effect on the degradation of polyethylene due to its smaller pore size. Mass balance showed that oil is always the main product of pyrolysis, regardless of the process conditions. However, all pyrolysis runs performed at 370°C were incomplete. The use of either zeolites resulted in a decrease in the heavy oil fraction and the prevention of wax formation. HUSY has the best performance in terms of the total monoaromatic yield (29 wt-% at 450°C), while HZSM5 promoted the production of gases (41 wt-% at 650°C). Plasmix is a potential input material for pyrolysis that is positively affected by the presence of the two tested zeolites. A more effective separation of polyethylene terephthalate during the selection process could lead to higher quality pyrolysis products.     

Evaporation of pyrolysis oil: Product distribution and residue char analysis

The evaporation of pyrolysis oil was studied at varying heating rates (～1–10⁶°C/min) with surrounding temperatures up to 850°C. A total product distribution (gas, vapor, and char) was measured using two atomizers with different droplet sizes. It was shown that with very high heating rates (～10⁶°C/min) the amount of char was significantly lowered (～8%, carbon basis) compared to the maximum amount, which was produced at low heating rates using a TGA (～30%, carbon basis; heating rate 1°C/min). The char formation takes place in the 100–350°C liquid temperature range due to polymerization reactions of compounds in the pyrolysis oil. All pyrolysis oil fractions (whole oil, pyrolytic lignin, glucose and aqueous rich/lean phase) showed charring behavior. The pyrolysis oil chars age when subjected to elevated temperatures (≥700°C), show similar reactivity toward combustion and steam gasification compared with chars produced during fast pyrolysis of solid biomass. However, the structure is totally different where the pyrolysis oil char is very light and fluffy. To use the produced char in conversion processes (energy or syngas production), it will have to be anchored to a carrier. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Characterisation of products from pyrolysis of waste sludges

The pyrolysis of waste sludges was investigated using thermogravimetry/mass spectrometry (TG/MS) and a fixed-bed reactor. Two types of sludge were used, namely mixed sludge and oil sludge. In TGA/MS measurements, two degradation steps were observed. Degradation of organic structures, in sludge took place in the first step, while inorganic materials in sludge were mainly decomposed in a second step (above 500 °C). In a fixed-bed reactor, the catalytic effect of inorganic matter in addition to organic matter was monitored the quality and yield of products from pyrolysis. Pyrolysis of oil sludge produced a larger amount of oil containing more aliphatic compounds and a high calorific value. On the other hand, pyrolysis of mixed sludge gave a smaller amount of oil being rich in polar compounds. The gaseous products from pyrolysis consist of high amount of combustable gases. Landfilling was found to be the best alternative to dispose off the pyrolytic char obtained from pyrolysis.     

Production of levoglucosan and glucose from pyrolysis of cellulosic materials

Vacuum pyrolysis of cellulose within the temperature range of 300–500°C provides a tar fraction containing mainly levoglucosan and glucose condensation products. It was found that pyrolysis proceeds at a much faster rate at the higher temperatures without detrimental effect on the yields. At 400°C the reaction was essentially complete within 3 min yielding a tar that contained 39% levoglucosan and, upon mild acid hydrolysis, gave 49% D-glucose. The yields could be further improved by washing or treatment of cellulosic substrates with acids. Cotton hydrocellulose provided up to 58% levoglucosan or 77% D-glucose. This is the highest yield determined by unequivocal methods. Commonly available cellulosic materials such as wood and newsprint give very poor yields of levoglucosan. However, the yields could be improved substantially by acid washing or prehydrolysis to the extent that pyrolysis of these substrates may become an attractive industrial process. The data in this report provide the technical basis for such a process and resolve the existing controversies on the reported yields.     

The pyrolysis of scrap automotive tyres: The influence of temperature and heating rate on product composition

Shredded automotive tyre waste was pyrolysed in a 200 cm³ static batch reactor in a N₂ atmosphere. The compositions and properties of the derived gases, pyrolytic oils and solid char were determined in relation to pyrolysis temperatures up to 720 °C and at heating rates between 5 and 80 °C min⁻¹. As the pyrolysis temperature was increased the percentage mass of solid char decreased, while gas and oil products increased until 600 °C after which there was a minimal change to product yield, the scrap tyres producing approximately 55% oil, 10% gas and 35% char. There was a small effect of heating rate on the product yield. The gases were identified as H₂, CO, CO₂, C₄H₆, CH₄ and C₂H₆, with lower concentrations of other hydrocarbon gases. Chemical class composition analysis by liquid chromatography showed that an increase in temperature produced a decrease in the proportion of aliphatic fractions and an increase in aromatic fractions for each heating rate. The molecular mass range of the oils, as determined by size exclusion chromatography, was up to 1600 mass units with a peak in the 300–400 range. There was an increase in molecular mass range as the pyrolysis temperature was increased. FT-i.r. analysis of the oils indicated the presence of alkanes, alkenes, ketones or aldehydes, aromatic, polyaromatic and substituted aromatic groups. Surface area determination of the solid chars showed a significant increase with increasing pyrolysis temperature and heating rate.     

The pyrolysis of waste mandarin residue using thermogravimetric analysis and a batch reactor

A study on the pyrolysis of waste mandarin residue, with the aim of producing bio-oil, is reported. To elucidate the thermodynamics and temperature-dependency of the pyrolysis reaction of waste mandarin residue, the activation energy was obtained by thermogravimetric analysis. Mass loss occurred within the temperature range 200–750 °C, and the average activation energy was calculated to be 205.5 kJ/mol. Pyrolysis experiments were performed using a batch reactor, under different conditions, by varying the carrier gas flow rate and temperature. When the carrier gas flow rate was increased from 15 to 30 and finally to 50ml/min, the oil yield slightly increased. Experiments performed within the temperature range 400–800 °C showed the highest oil yield (38.16 wt%) at 500 °C. The moisture content in the bio-oil increased from 35 to 45% as the temperature increased from 400 to 800 °C, which also resulted in reduction of the oxygenates content and increase in the phenolics and aromatics content, indicating that temperature is an important operating parameter influencing the yield and composition of bio-oil.     

Low-temperature pyrolysis of Texas lignite,basic extracts and some related model compounds

Low-temperature (400 °C) pyrolysis of Texas lignite produced volatile products typical of coal tars, with tar evolution beginning at about 300 °C. n-Alkanes up to about C₃₀ were observed among the products and these were accompanied by smaller but significant amounts of 1 -alkenes. Similar pyrolyses were performed on pyridine extracts and sodium hydroxide extracts of lignite. The alkanes and alkenes were seen among the pyrolysis products from the pyridine extracts and from the residual lignite from both types of extractions, but they were not seen among the pyrolysis products from the sodium hydroxide extracts. Pyrolyses of some model compounds suggested that dealkylation of alkyl-substituted arenes can be significant at 400 °C and can account for the production of the alkanes and alkenes from the lignite.     

Active carbon from scrap tyres

The possibility of producing active carbon by activation at 850 °C of the char obtained from the pyrolysis (at 450 and 600 °C) of scrap tyres has been studied. The activated char showed good adsorbing characteristics, similar to those of typical commercial grades. The yield and the desired adsorbing capacity depend on the activation time. However, the ash content and friability are quite high; therefore the activated char is suitable for applications in powder form in which the ash does not cause problems.     

生活垃圾热解半焦-热解油重整过程中水分的消耗与转移

热解炭原位重整城市固体废物的挥发分是改善热解产物的良好方法。在这个过程中,水蒸气在产品转化中起着重要作用。为了了解水分在重整过程中的作用,本研究中将热解液中的油相和水相分离,然后用D₂O代替重整过程中的水相,以跟踪液体、气体和固体之间的氢转移。热解油/焦炭重整过程在600、700和800℃下进行。用GC-MS（气相色谱质谱法）分析重整后液体中的油相;IR-MS（同位素比质谱法）分析重整后液体和固体中的氘浓度。研究发现,在实验温度范围内,水蒸气对焦炭的气化作用非常弱,当D₂O/焦炭的比例为2/1时,D₂O中2％（质量）的氘在反应后残留在炭中;但水蒸气与热解油的气化反应很强烈,在800℃时,78.68％（质量）的热解液（水油混合物）被气化,且热解油中脂肪烃被大量分解,重整液的油相组分中芳香烃占到96.17%;同时,当D₂O/油的比例为2/3时,D₂O中59％的氘转移到合成气中。研究结果将为生活垃圾热解处理控制最终产物提供理论指导。     

Pyrolysis of municipal solid waste

A state-of-the-art review describing the characteristics of municipal solid waste (MSW) and assessing the chemistry and technology of pyrolysis of municipal solid waste is presented. The economics of the pyrolysis process are outlined. Combustibles constitute on average about 60% of the weight of MSW and result in an average heating value (“as received” basis) of about 3,000 to 6,000 Btu/Ib. This makes MSW attractive for thermal treatment. Municipal solid waste can be converted to gas, liquid and solid products by pyrolysis. Due to the complexity in composition of MSW the exact mechanism of pyrolysis is not known. Both homogeneous and heterogeneous reactions occur at the same time and both heat and mass transfer take place during the process. The relative yields of different products depends on the temperature of pyrolysis and the rate of heating. High pyrolysis temperatures and high heating rates favour the production of gases indicating high energies of activation for gasification reactions. At low temperatures, below 800°C, the pyrolysis process is reaction-rate controlled, while at high temperatures, above 1,200°C, the process is diffusion-rate controlled. Conditions of good heat and mass transfer are required for gasification of MSW. The residual char after pyrolysis can be gasified by further treatment with steam, hydrogen or carbon monoxide and water. The heat available from the products of pyrolysis is sufficient to sustain the process and yield some excess energy. Three types of reactor design have been generally used in the investigation of pyrolysis of MSW; fixed bed reactor, fluidized bed reactor and rotary kiln reactor. The advantages and weak points of each of these are briefly discussed. The costs of disposal of MSW by pyrolysis appear to be competitive with incineration.     

Modeling char surface area during coal pyrolysis: Validation of relationship between pore structure and polymer network

The relationship between pore structure and polymer network during coal pyrolysis was studied by analyzing the evolution of microcrystal, pore structure, and functional groups of char prepared from Naomaohu subbituminous coal by a drop-tube furnace reactor at 600–1000°C. The char specific surface area changes little with aliphatic bridge cleaving at temperatures lower than 700°C; starts to increase at 800°C with the beginning of side chain cleaving; then reaches the maximum with the methyl and methylene content together at 900°C; finally decreases with the further cleaving of aliphatic structures at higher temperatures. Moreover, the lattice stacking height is minimum at 900°C, indicating aliphatic structure can reduce the lattice order degree. These phenomena support the assumption in the CPD-PS model that the side chain cleaving generates open pores and meanwhile reduces the adsorption sites in them, making the char specific surface area first increase and then decrease.     

半焦基催化剂裂解煤热解产物提高油气品质

利用上段热解下段催化的两段固定床反应器,针对府谷煤研究了半焦和半焦负载Co催化剂对煤热解产物的催化裂解效果。结果表明,半焦和半焦负载钴对热解产物催化裂解后,热解气收率增加,焦油收率降低,但焦油中沸点低于360℃的轻质组分含量提高,轻质焦油收率基本保持不变或略有增加。与煤在600℃直接热解相比,在热解和催化温度均为600℃,采用煤样质量20%的半焦为催化剂时焦油中轻质组分质量含量提高了约25%,轻质组分收率基本不变,热解气体积收率增加了31.2%;在热解温度600℃,催化温度500℃时,采用煤样质量5%的半焦负载钴催化剂,焦油中轻质组分质量收率和含量分别提高了约8.8%和28.8%,热解气体积收率增加了21.5%。煤热解产物的二次催化裂解的总体效果是将焦油中重质组分转化为轻质焦油和热解气。     

Surface temperature of decomposing construction materials studied by laser‐induced phosphorescence

Measurements of surface temperature and mass loss of decomposing construction materials during rapid pyrolysis are presented. Experiments have been performed with samples of low‐density fiberboard, medium‐density fiberboard, particleboard and poly(methyl methacrylate) in a single particle reactor at temperatures between 300° and 600°C. Ultraviolet laser light was used to excite micrometer‐sized thermographic phosphor particles that were deposited on the investigated materials, and the temperature was obtained from temporally resolved measurements of the laser‐induced emission. The wood‐based materials show a similar behavior, with small differences being attributed to differences in material properties. The surface temperature rapidly increases to about 400°C when a particle is introduced to the hot reactor. The initial phase is followed by rapid decomposition during which the surface temperature is 380°–540°C. The heating rate is slowed down during the rapid pyrolysis, and again increases as the remaining char is heated to the reactor temperature. The poly (methyl methacrylate), however, melts and at high temperatures can be characterized as a liquid with a boiling point of about 400°C. Thermographic phosphors are concluded to be suitable for high precision remote measurements of the surface temperature of decomposing construction materials, and possibilities for further studies and developments of the technique are discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

不同类型分子筛催化热解陈腐垃圾性能研究

选用3种不同类型的分子筛催化剂HZSM-5、HY和HBeta,以垃圾填埋场陈腐垃圾为原料,进行绝氧热解和催化热解对比研究。结果表明,分子筛催化剂的加入不仅对陈腐垃圾热解产物产率有明显影响,而且对热解气和热解油的品质有明显的提高。对比3种催化剂发现,HZSM-5更有利于热解气的产生,而且所得热解气的热值最高,为67.45 MJ·m^-3,所得热解油中汽油组分最多,为质量分数65.4%,而重馏分油组分仅为6.9%。HY和HBeta则得到相对更高的热解油产量,尤其是轻质柴油,质量分数分别为38.1%和41.4%。3种催化剂截然不同的催化热解产物产率和产品性质与其孔道结构、织构性质和酸性质均密切相关。     

废旧轮胎热解及热解产物研究展望

热解作为废旧轮胎处置的重要技术手段,可以有效实现其减量化、无害化和资源化利用。本文综述了废旧轮胎热解的影响因素以及热解产物的研究进展,对废旧轮胎热解的经济、环境和社会效益进行了说明,指出当前工业化热解废旧轮胎存在的问题,并展望了未来节能环保式热解工艺的应用前景。结合现有的工业化热解设备,优化工艺条件和反应器结构型式,进一步分析了热解产物即热解气、热解油及热解炭的成分结构与应用,通过对热解产物改性活化与提质处理,创造更大的经济效益。提出应基于环境法规要求和绿色发展理念,糅合多种处理技术,研制适合废旧轮胎热解的工艺装备,开发集收集/预处理/热解/产物回收与提质于一体的废旧轮胎处置技术,实现废旧轮胎高效清洁转化和高值利用。     

Biological drying of municipal solid waste from landfill

Abstract

The aim of this work was to investigate the process of biodrying of municipal solid waste from the old landfill to preparing it for pyrolysis or gasification. New aspect of this research is biodrying of waste from old landfill. Biodrying of wastes was carried out at different aeration rates (7, 35, and 175?dm³/kg dry matter/d) at two temperatures (23 and 50?°C). The research was carried out in the laboratory bioreactors of special design (lysimeters), which simulated the conditions prevailing in the landfill. The optimal conditions for reduction of moisture in waste (63.2%) has been attained for the highest aeration rate (175?dm³/kg dry matter/d) and temperature equal to 50?°C. The final moisture content of the obtained biodried product was 23% w/w. In the bioreactor, in which the greatest reduction of moisture was obtained, the total amount of produced CO₂ was 44.9 gC/kg dry matter, and the biodrying efficiency was equal to 0.89. During biodrying of wastes in optimal conditions, higher heating value of waste increased from 4.3 to 11.0?MJ/kg. As a result of the performed pyrolysis of biodried waste at 900?°C, char, oil, and gas were obtained the respective yields of 47, 32, and 21% w/w. The gas emerging in the gasification process was characterized by higher heating value equal to 11.3?MJ/m³.     

Characteristics of oil shale pyrolysis in a two-stage fluidized bed

Rapid pyrolysis of oil shale coupled with in-situ upgrading of pyrolysis volatiles over oil shale char was studied in a laboratory two-stage fluidized bed(TSFB) to clarify the shale oil yield and quality and their variations with operating conditions. Rapid pyrolysis of oil shale in fluidized bed(FB) obtained shale oil yield higher than the Fischer Assay oil yield at temperatures of 500-600 ℃. The highest yield was 12.7 wt% at 500 ℃ and was about1.3 times of the Fischer Assay oil yield. The heavy fraction(boiling point 350 ℃) in shale oil at all temperatures from rapid pyrolysis was above 50%. Adding an upper FB of secondary cracking over oil shale char caused the loss of shale oil but improved its quality. Heavy fraction yield decreased significantly and almost disappeared at temperatures above 550 ℃, while the corresponding light fraction(boiling point 350 ℃) yield dramatically increased. In terms of achieving high light fraction yield, the optimal pyrolysis and also secondary cracking temperatures in TSFB were 600 ℃, at which the shale oil yield decreased by 17.74% but its light fraction yield of 7.07 wt% increased by 86.11% in comparison with FB pyrolysis. The light fraction yield was higher than that of Fischer Assay at all cases in TSFB. Thus, a rapid pyrolysis of oil shale combined with volatile upgrading was important for producing high-quality shale oil with high yield as well.     

Thermo-catalytic decomposition of waste lubricating oil over carbon catalyst

The thermo-catalytic decomposition of waste lubricating oil over a carbon catalyst was investigated in an I.D. of 14.5mm and length of 640mm quartz tube reactor. The carbon catalysts were activated carbon and rubber grade carbon blacks. The decomposition products of waste lubricating oil were hydrogen, methane, and ethylene in a gas phase, carbon in a solid phase and naphthalene in a liquid phase occurring within the temperature ranges of 700 °C-850 °C. The thermo-catalytic decomposition showed higher hydrogen yield and lower methane yield than that of a non-catalytic decomposition. The carbon black catalyst showed higher hydrogen yield than the activated carbon catalyst and maintained constant catalytic activity for hydrogen production, while activated carbon catalyst showed a deactivation in catalytic activity for hydrogen production. As the operating temperature increased from 700 °C to 800 °C, the hydrogen yield increased and was particularly higher with carbon black catalyst than activated carbon. As a result, carbon black catalyst was found to be an effective catalyst for the decomposition of waste lubricating oil into valuable chemicals such as hydrogen and methane.     

Mathematical modelling of lignin pyrolysis

Seven lignins from different sources were pyrolysed (i) isothermally in vacuum over the temperature range 300–1300 °C and (ii) at a constant heating rate of 30 °C min^?1 and a pressure of 0.1 MPa over the temperature range 150–900 °C. The mass fraction of each product—char, tar and gas species—and the elemental composition of the char and the tar were determined for the flash pyrolysis experiments. The evolution rates of the gas species and the tar versus the dynamic temperature of pyrolysis were determined for the constant heating rate pyrolysis experiments. Although the amount of each product species varied from lignin to lignin, the evolution rates were insensitive to the lignin source and the extraction process. To model the data, modifications were made to a recently developed model of coal pyrolysis. The model proved to be successful in simulating both the data from vacuum flash pyrolysis and constant heating rate pyrolysis of Iotech lignin.