Biomass pyrolysis

This paper mainly discusses the principle, pyrolysis reaction process, pyrolysis process types and influencing factors of biomass pyrolysis technology. Based on the analysis of the development status at home and abroad, the main shortcomings of biomass pyrolysis technology are put forward, and the development prospect of biomass pyrolysis technology is prospected.

Key words: biomass pyrolysis; Research progress; Development status; prospect

0 quotation

Through biomass energy conversion technology, biomass energy can be efficiently used to produce various clean energy and chemical products, thus reducing human dependence on fossil energy and reducing environmental pollution caused by fossil energy consumption. At present, all countries in the world, especially developed countries, are committed to developing efficient and pollution-free biomass energy utilization technologies to protect their mineral energy resources and provide fundamental guarantee for the sustainable development of the national economy.

Biomass pyrolysis refers to a thermochemical conversion technology in which biomass is heated above 500℃ without oxidant (air, oxygen, steam, etc.). ) or only provide limited oxygen, biomass macromolecules (lignin, cellulose, hemicellulose) are decomposed into smaller molecular fuel substances (solid carbon, combustible gas, bio-oil) through thermochemical reactions. The fuel energy conversion rate of biomass pyrolysis can reach 95.5%, which can maximize the conversion of biomass energy into energy products and make the best use of everything, and pyrolysis is also an essential initial stage of combustion gasification [1].

1 principle of pyrolysis technology

Pyrolysis principle of 1. 1

From the point of view of chemical reaction, it is found that complex thermochemical reactions occur during biomass pyrolysis, including molecular bond breaking, isomerization and small molecular polymerization. The main components of wood, forestry waste and crop waste are cellulose, hemicellulose and lignin. Thermogravimetric analysis showed that cellulose began to pyrolyze at 52℃, and the pyrolysis reaction rate accelerated with the increase of temperature. At 350 ~ 370℃, it is decomposed into low molecular products, and its pyrolysis process is as follows:

(C6H 10O5)n→nC6H 10O5

C6H 10O5→H2O+2CH3-CO-CHO

CH3-CO-CHO+H2→CH3-CO-CH2OH

CH3-CO-CH2OH+H2→CH3-CHOH-CH2+H2O

Hemicellulose is the most unstable component in wood because of its branched structure. It decomposes at 225 ~ 325℃, which is easier to decompose than cellulose, and its pyrolysis mechanism is similar to cellulose [2].

From the point of view of material migration and energy transfer, it is found that in the process of biomass pyrolysis, heat is first transferred to the surface of particles, and then from the surface to the inside of particles. The pyrolysis process is carried out layer by layer from outside to inside, and the heated components of biomass particles are rapidly decomposed into charcoal and volatiles. The volatile components are composed of condensable gas and non-condensable gas, and the condensable gas can be quickly condensed to obtain bio-oil. The primary pyrolysis reaction produces biomass charcoal, primary bio-oil and non-condensable gas. Volatiles in porous biomass particles will be further cracked to form non-condensable gas and thermally stable secondary bio-oil. At the same time, when the volatile gas leaves the biological particles, it will also pass through the surrounding gas components, where it will be further cracked and decomposed, which is called secondary cracking reaction. Biomass pyrolysis process eventually forms bio-oil, non-condensable gas and biomass [3,4].

Basic process of 1.2 pyrolysis reaction

According to the temperature change of pyrolysis process and the product situation, it can be divided into drying stage, preheating stage, solid decomposition stage and calcination stage.

In the drying stage of 1.2. 1 (the temperature is 120 ~ 150℃), the water in the biomass is evaporated, and the chemical composition of the material is almost unchanged.

In the pre-decomposition stage of 1.2.2 (the temperature is 150 ~ 275℃), the thermal reaction of the material is obvious, and the chemical composition begins to change, and unstable components such as hemicellulose in biomass are decomposed into carbon dioxide, carbon monoxide and a small amount of acetic acid. The above two stages are endothermic reaction stages.

1.2.3 solid decomposition stage (temperature 275 ~ 475℃), the main stage of pyrolysis, substances have undergone various complex physical and chemical reactions, resulting in a large number of decomposition products. The generated liquid product contains acetic acid, wood tar and methanol (precipitated when cooling); There are CO2, CO, CH4, H2, etc. In gas products, the content of combustible components increases. This stage will release a lot of heat.

1.2.4 Calcination stage (temperature is 450 ~ 500℃), biomass burns charcoal with heat supplied from outside, which reduces volatile substances in charcoal and increases fixed carbon content. This is an exothermic stage. In fact, it is difficult to clearly define the boundaries of the above four stages, and the reaction process of each stage will cross each other [5, 6].

2 pyrolysis process and influencing factors

2. 1 pyrolysis process type

Judging from the heating rate of biomass and the time required to complete the reaction, the pyrolysis process of biomass can be basically divided into two types: one is slow pyrolysis, and the other is fast pyrolysis. In rapid pyrolysis, when the reaction time is very short (< < 0.5s), it is also called rapid pyrolysis. According to the process conditions, biomass pyrolysis can be divided into three types: slow pyrolysis, rapid pyrolysis and reactive pyrolysis. In the slow pyrolysis process, it can be divided into carbonization and conventional pyrolysis [5].

Slow pyrolysis (also known as dry distillation process and traditional pyrolysis) has a history of thousands of years, and it is a carbonization process aimed at producing charcoal. The heating temperature of low-temperature carbonization is 500 ~ 580℃, the middle-temperature carbonization temperature is 660 ~ 750℃, and the high-temperature carbonization temperature is 900 ~ 1 100℃. Putting the wood into a kiln and heating it under the condition of being isolated from the air can obtain the charcoal output accounting for 30% ~ 35% of the raw material quality.

Rapid pyrolysis is to put crushed biomass raw materials into a rapid pyrolysis device, and strictly control the heating rate (generally about 10 ~ 200℃/s) and the reaction temperature (about 500℃). Under anaerobic conditions, biomass raw materials are rapidly heated to a higher temperature, which leads to the decomposition of macromolecules, producing small molecular gases, condensable volatiles and a small amount of coke products. Condensable volatiles are rapidly cooled into flowable liquid and become bio-oil or tar, the proportion of which can generally reach 40% ~ 60% of the mass of raw materials.

Compared with slow pyrolysis, the heat transfer reaction process of fast pyrolysis occurs in a very short time, and the strong thermal effect directly produces pyrolysis products, which are then rapidly quenched, usually falling below 350℃ within 0.5s, so as to obtain liquid products (oil) to the maximum extent.

Conventional pyrolysis is that biomass raw materials are placed in a conventional pyrolysis device, and under the conditions of moderate temperature below 600℃ and moderate reaction rate (0. 1 ~ 1℃/s), after several hours of pyrolysis, 20% ~ 25% of biomass charcoal and 10% ~ 20% of bio-oil are obtained.

2.2 pyrolysis influencing factors

Generally speaking, the main factors affecting pyrolysis include chemical and physical aspects. Chemical factors include a series of complex primary reactions and secondary reactions; Physical factors are mainly heat and mass transfer in the reaction process and physical characteristics of raw materials. The specific operating conditions are: temperature, material characteristics, catalyst, residence time, pressure and heating rate [10].

Temperature +0

In the process of biomass pyrolysis, temperature is a very important factor, which has a great influence on the distribution, composition, yield and calorific value of pyrolysis gas. The proportion of gas, oil and carbon in the final product of biomass pyrolysis varies greatly with the reaction temperature and heating speed. Generally speaking, slow pyrolysis at low temperature and long residence is mainly used to maximize the yield of carbon, and its mass yield and energy yield reach 30% and 50% (mass fraction) respectively [1~13].

When the temperature is lower than 600℃, the yields of bio-oil, non-condensable gas and carbon are basically the same at a moderate reaction rate. The rapid pyrolysis temperature is in the range of 500 ~ 650℃, which is mainly used to improve the yield of bio-oil, and the yield of bio-oil can reach 80% (mass fraction). The same flash pyrolysis, if the temperature is higher than 700℃, is mainly used to produce gas products with a yield of 80% (mass fraction) at a very high reaction rate and a very short gas phase residence time. When the heating rate is extremely fast, hemicellulose and cellulose hardly produce carbon [5].

2.2.2 The influence of biomass materials

The species, molecular structure, particle size and shape of biomass have an important influence on the pyrolysis behavior and product composition of biomass [3]. This kind of influence is quite complicated, which interacts with external characteristics such as pyrolysis temperature, pressure and heating rate, and affects the pyrolysis process at different levels and degrees. Because lignin is more difficult to decompose than cellulose and hemicellulose, coke with more lignin usually produces more coke. However, if there is more hemicellulose, the coke output is smaller. In the composition of biomass, the liquid product obtained by lignin pyrolysis has the largest calorific value; Among the gas products, the gas calorific value obtained by xylan pyrolysis is the largest [5].

The particle size of biomass is the decisive factor affecting the pyrolysis rate. When the particle size is less than 1mm, the pyrolysis process is controlled by the reaction kinetic rate, while when the particle size is greater than 1mm, the pyrolysis process is also controlled by the heat and mass transfer phenomenon. The heat transfer ability of large particles is worse than that of small particles, and the temperature rise inside particles is slow, that is, the large particles stay in the low temperature zone for a long time, which affects the distribution of pyrolysis products. With the increase of particle size, the yield of solid carbon in pyrolysis products increases. From the point of view of obtaining more bio-oil, the size of biomass particles should be small, but this will undoubtedly lead to difficulties in crushing and screening. In fact, it is only necessary to select biomass particles smaller than1mm.

Effect of catalyst

Researchers use different catalysts to mix in biomass pyrolysis experiments, and different catalysts have different effects. For example, alkali carbonate can increase the output of gas and carbon, reduce the output of bio-oil and promote the release of hydrogen in raw materials, thus increasing the H2/ CO ratio in air products; K+ can promote the production of CO and CO2, but hardly affect the production of H2O. NaCl can promote the formation of H2O, CO and CO2 in cellulose reaction. Hydrocracking can improve the yield of bio-oil and make the molecular weight of oil smaller.

In addition, the residence time of the product obtained by the reaction of raw materials in the reactor, the cooling rate of the gas generated by the reaction, the particle size of raw materials, etc. , it also has a certain influence on the output ratio of carbon, combustible gas and bio-oil (gas is precipitated after cooling) [5].

Retention time

The residence time in biomass pyrolysis reaction can be divided into solid residence time and gas residence time. The shorter the solid phase residence time, the smaller the proportion of pyrolysis solid products, the larger the total product, and the more complete the pyrolysis. At a given temperature and heating rate, the shorter the solid phase residence time, the less the solid phase products and the more the gas phase products in the conversion products. Generally speaking, the gas phase residence time does not affect the primary pyrolysis reaction of biomass, but only affects the secondary pyrolysis reaction of bio-oil in liquid products. When the primary products of biomass pyrolysis products enter the gas phase around biomass particles, bio-oil will undergo further cracking reaction. In the thermal reactor, the longer the gas phase residence time, the more serious the secondary cracking of bio-oil is, and the secondary cracking reaction is intensified, releasing H2, CH4, CO and so on. , resulting in a rapid decrease in liquid products and an increase in gas products. Therefore, in order to obtain the maximum bio-oil output, it is necessary to shorten the gas phase residence time, make volatile products leave the reactor quickly, and reduce the time of tar secondary cracking [3 ~ 5].

pressure

Pressure will affect the gas phase residence time, thus affecting the secondary cracking and finally affecting the distribution of pyrolysis products. With the increase of pressure, the activation energy of biomass decreases, and the decreasing trend gradually slows down. At higher pressure, the pyrolysis rate of biomass is obviously increased, the reaction is more intense, and the residence time of volatile products is increased, resulting in greater secondary pyrolysis; However, under low pressure, volatiles can quickly leave the particle surface, thus limiting the occurrence of secondary cracking and increasing bio-oil production [14, 15].

heating rate

The heating rate has great influence on pyrolysis. Generally speaking, it has both positive and negative effects on pyrolysis. With the increase of heating rate, the corresponding time for material particles to reach the required temperature for pyrolysis becomes shorter, which is beneficial to pyrolysis. But at the same time, the temperature difference between inside and outside the particles becomes larger, which will affect the internal pyrolysis due to the heat transfer lag effect. With the increase of heating rate, the temperature lag will be more serious, the resolution of thermogravimetric curve and differential thermal curve will decrease, and the material weight loss and weight loss rate curve will move to high temperature area. Pyrolysis rate and pyrolysis characteristic temperature (pyrolysis start temperature, pyrolysis fastest temperature and pyrolysis end temperature) all increase linearly with the increase of heating rate. In a certain pyrolysis time, the slow heating rate will prolong the residence time of pyrolysis materials in the low temperature zone, promote the dehydration and carbonization of cellulose and lignin, and lead to an increase in carbon yield. The yield of gas and bio-oil depends largely on the competition between the primary reaction of volatile matter generation and the secondary cracking reaction of bio-oil. The faster heating mode increases the residence time of volatile matter in high temperature environment, promotes the secondary cracking, reduces the bio-oil yield and increases the gas yield [16 ~ 18].

3 research status of pyrolysis technology

3. 1 Domestic research status

Compared with some countries in Europe and America, the research on biomass pyrolysis in Asia and China started late. In recent ten years, the Biomass Energy Research Center of Guangzhou Energy Research Institute, Zhejiang University, Northeast Forestry University and other units have done some work in this regard.

The Biomass Energy Research Center of Guangzhou Energy Research Institute mainly studies the mechanism of thermochemical transformation process of substances and thermochemical utilization technology. The research contents are as follows: (1) Study on pyrolysis mechanism in high-energy environment: plasma pyrolysis gasification, supercritical pyrolysis, etc. (2) Study on new gasification processes: high temperature gasification, oxygen-enriched gasification, steam gasification, etc. (3) Integration and application of gasification technology system: new gasification device, gasification power generation system, etc. (4) Biomass gasification combustion and direct combustion: gasification combustion technology, pyrolysis combustion technology, direct combustion, etc.

Focusing on the huge potential advantages of fluidized bed technology in large-scale utilization of biomass clean energy, Zhejiang University successfully developed a biomass pyrolysis and liquefaction reactor based on fluidized bed technology at the end of last century. Based on the previous successful experiments, aiming at the shortcomings of the existing biomass pyrolysis and liquefaction process, such as low energy utilization rate and non-classification of liquid products, a unique design scheme was adopted to develop an integrated biomass pyrolysis and classification device to prepare liquid fuel, and the effects of various operating parameters on the yield and composition of biomass pyrolysis products were obtained, which was suitable for large-scale production and substitution of liquid fuel. At present, in-depth technology and extended application research are under way.

Research direction of Biomass Energy Research Center of Northeast Forestry University: rotating cone biomass rapid pyrolysis and liquefaction device. After a series of debugging, experiments and improvements, some basic design rules and experiences have been explored. At present, the equipment manufacturing has been completed and will soon enter the experimental stage, laying a solid foundation for future equipment improvement and technology promotion.

In addition, in the research of rapid pyrolysis, with the assistance of the Food and Agriculture Organization of the United Nations (FTO), Shenyang Agricultural University introduced a 50 kg/h rotating cone rapid pyrolysis device from BTG Group in the Netherlands, and carried out related experimental research. University of Shanghai for Science and Technology, East China University of Science and Technology, Zhejiang University, Guangzhou Institute of Energy, China Academy of Sciences, Tsinghua University, Harbin Institute of Technology and Shandong University of Technology have also carried out relevant experimental research, and are currently conducting in-depth technology and extended application research. With the support of existing technology, commercial operation only adopts conveying bed and circulating fluidized bed system [19,20].

The Key Open Laboratory of Renewable Energy of Henan Agricultural University and the Ministry of Agriculture have also conducted long-term research on biomass pyrolysis. The birth of YNO4-4 biomass gas decoking machine has solved the problems of complex purification device, low decoking efficiency and difficult tar collection in the existing biomass pyrolysis gasification device, with simple structure, convenient operation, reliable system operation, low maintenance cost and remarkable economic benefits. It is suitable for various biomass pyrolysis and gasification devices and their commercial application, and has been used in 200 1 1.

At the same time, the laboratory and Henan Shangqiu Lisan New Energy Co., Ltd. studied the comprehensive utilization of biomass pyrolysis products and formed supporting equipment. According to the seasonal and dispersive characteristics of crop straw resources and the contradiction between transportation and storage difficulties, the mode of combining dispersion and concentration is adopted, that is, a small biomass pyrolysis device is built within the range where crop straw is easy to collect, and biomass gas is used locally, and then biomass charcoal, tar and wood vinegar which are convenient for transportation are collected, and several centralized processing plants are built to produce multi-purpose products, which is more suitable for China's national conditions.

3.2 Foreign research status

The initial research of biomass pyrolysis technology is mainly concentrated in Europe and North America. Since 1990s, it has been developing vigorously. With the gradual improvement of experimental scale reaction devices, demonstration and commercial pyrolysis devices have been continuously developed and built. Some famous laboratories and research institutes in Europe have developed many important pyrolysis technologies. In the 1990s, the launch of several projects in European Joule Plan for Biomass Production and Energy indicated that the EU attached importance to biomass pyrolysis technology.

However, the most influential achievements occurred in North America. For example, Castle Capital Company in Canada enlarged the rubber thermal ablation reactor developed by BBC Company to build a solid waste thermal ablation cracking reactor with a scale of1500 kg/h ~ 2,000 kg/h, and later Aston University in Britain, Renewable Energy Laboratory in the United States, Nancy in France,

The rotating cone pyrolysis reactor was developed by the reactor engineering group and BTG biomass technology group of Twente University in the Netherlands. Because of its advanced technology, small equipment size and compact structure, it has been widely studied and applied. Hamberger Institute of Wood Chemistry improved and developed the bubbling bed technology of the mixing reactor, and successfully separated condensable smoke from gas by electrostatic trapping and condenser. ENSYN developed and built a rapid pyrolysis device (RTP) in Italy based on the principle of circulating fluidized bed, and some small experimental devices have been installed and debugged in various research institutes.

Traditional pyrolysis technology is not suitable for thermal conversion of wet biomass. In order to solve this problem, many European countries have begun to study a new pyrolysis technology, namely hydrothermal upgrading (HTU). Dissolve wet sawdust or biomass in water, soften it in a high-pressure container for 65438 05 minutes (200℃, 300 bar), and then enter another reactor (330℃, 200 bar) for liquefaction for 5 ~ 65438 05 minutes. After decarboxylation, oxygen is removed to produce 30% CO2 and 50% bio-oil, only containing 10% ~ 15% oxygen. Dutch Shell Company has proved that high-quality gasoline and crude gasoline can be obtained by catalysis. This technology can produce high-quality oil (oxygen content is lower than pyrolysis oil), and biomass can be used directly without drying [2 1, 22].

4 Prospects and prospects

Facing the exhaustion of fossil energy and the aggravation of environmental pollution, it is urgent to find clean new energy. Now the whole world is paying attention to the development and utilization of biomass energy. The utilization prospect of biomass energy is very broad, but the real practical application depends on whether various conversion and utilization technologies of biomass can make breakthroughs.

With the continuous progress of technology, the research direction and focus are also expanding. In the past, it paid attention to the types and reaction parameters of pyrolysis reactors in order to maximize the products. At present, the process of combining the comprehensive utilization of biomass resources with the optimization of the overall efficiency of the system is considered as the development direction of maximizing the economic benefits of pyrolysis, which has considerable potential. In addition, improving product quality and developing new application fields are also urgent requirements for current research.

The research progress of biomass pyrolysis technology in China is slow, mainly because the research is based on a single technology and lacks systematicness, and there is still a big gap compared with countries such as Europe and America. Especially, there are obvious gaps in the research and development of high-efficiency reactors, the optimization of process parameters, the refining of liquefied products and the influence of biofuels on engine performance. At the same time, there are still some problems in pyrolysis technology: the cost of bio-oil is usually higher than that of mineral oil, bio-oil is incompatible with traditional liquid fuel and needs special fuel treatment equipment; Biooil is a kind of hydrocarbon with high oxygen content, and its physical and chemical properties are unstable. Phase separation and precipitation will occur after long-term storage, which is corrosive. Due to the instability of physical and chemical properties, bio-oil can not be directly used in existing power equipment, and can only be used after modification and refining; The quality of different bio-oils varies greatly, and there is no uniform standard for the use and sale of bio-oils, which affects its wide application. The above problems are also the bottleneck that hinders the efficient and large-scale utilization of biomass [6].

In view of the above gaps and problems, the future research should focus on how to improve the yield of liquefied products, seek efficient refining technology, improve the quality of bio-oil, reduce operating costs, and realize comprehensive utilization and industrial production of products. At the same time, we should strengthen the research on the mechanism of biomass liquefaction reaction, especially the effects of the types of raw materials and various components in raw materials on the thermochemical reaction process and products. On the basis of theoretical research, enlarge the existing equipment, reduce the production cost of bio-oil, and gradually transition to large-scale production, improve the determination method of bio-oil composition and physical characteristics, formulate unified norms and standards, develop new technologies for refining and upgrading bio-oil, and develop low-pollution and efficient catalysts for thermochemical catalytic reactions, thus participating in the competition in the fossil fuel market [23]. ?

refer to

[1] Yang Haiping, Chen hanping, Wang Xianhua, et al. research progress of biomass pyrolysis [J]. gas and thermal power, 2006,26 (5):18.

[2]? Li Tradition. New energy and renewable energy technology [M]. Jiangsu: Southeast University Press, 2005:116 ~117.

Ma, Yang Jiakuan. Analysis of influencing factors of biomass pyrolysis [J]. Environmental Technology, 2005,5:10 ~12.

Chen, Luo Yonghao, Research progress of biomass pyrolysis mechanism [J]. Industrial heating, 2006,35 (5): 4 ~ 7.

Yuan, Wu Chuangzhi, Ma Longlong, et al. Principle and technology of biomass energy utilization [M]. Beijing: Chemical Industry Press, 2005: 289 ~ 293.

Zhai, Liu Kuiren,. New energy technology [M]. Beijing: Chemical Industry Press, 2005: 266 ~ 27 1.

[7] photo by Jiang, He Guang. Comparative study on biomass pyrolysis technology [J]. Renewable Energy, 2006, 4: 58 ~ 62.

Chen Jun, Tao Zhanliang. Energy chemistry [M]. Beijing: Chemical Industry Press, 2004: 206 ~ 207.

Su Yaxin, Mao Yuru, Zhao Jingde. Introduction to New Energy and Renewable Energy [M]. Beijing: Chemical Industry Press, 2006: 90 ~ 94.

[10] Pan Lina. Rapid pyrolysis process of biomass and its influencing factors [J]. applied energy technology, 2004,2: 7 ~ 8.

[10] Li, Li. Study on rapid pyrolysis process of biomass [J]. Review on sustainable and renewable energy. 2000, 4( 1): 1~73.

Liu Hanqiao, Cai Jiuju, Bao. Comparative Study on Two Reaction Models of Waste Biomass Pyrolysis [J]. Journal of Materials and Metallurgy, 2003,2 (2):153 ~156.

[13] Li Shuiqing, Li Aimin, Yan Jianhua, et al. Study on pyrolysis of biomass waste in rotary kiln ⅰ. Influence of pyrolysis conditions on distribution of pyrolysis products [J]. Acta Solar Energy, 2000,21(4): 333 ~ 340.

Cui Yabing, Gu. Thermogravimetric study on pyrolysis characteristics of biomass under atmospheric pressure and atmospheric pressure [J]. Boiler Technology, 2004,35 (4):12 ~14.

Echetin, Gupta. B. Mohtadri. Effects of pyrolysis pressure and heating rate on structure and apparent gasification reactivity of Pinus radiata semi-coke [J]. Fuel, 2005, (84): 1 328~ 1 334.

[16] Lai Yanhua, Lv Mingxin, Ma Chunyuan, et al. Pyrolysis law of straw biomass fuel at programmed temperature [J]. Combustion science and technology. 200 1,7(3):245~246

[17] Song Chuncai, Hu Haoquan. Study on catalytic pyrolysis and kinetics of straw and its main components [J]. Coal conversion 2003,26 (3): 91-94

[18] Li, Yi Weiming, Bai Xueyuan, et al. Determination of residence time of corn stalk particles in rapid pyrolysis and volatilization experiment [J]. Journal of East Engineering (Natural Science Edition), 2004,18 (1):10 ~ 60.

Cao Youwei, Wang Shuyang. Research progress of biomass pyrolysis technology in China [J]. Forestry Labor Safety, 2005, 18 (2): 24 ~ 26.

Miao Zhenyong, Li Wei, Gu. Research progress of biomass rapid pyrolysis technology [J]. Energy conservation and environmental protection, 2005, (2): 13 ~ 15.

[2 1]bridgewater A V, Peacock g v. Rapid pyrolysis process of biomass. Renewable & Sustainable Energy Review, 2000, (4): 1~73.

[22]bridgewater A V, Cottam M L. Opportunities for production and upgrading of biomass pyrolysis liquid. Energy and fuel,1992,6 (2):113 ~120.

[23] Bridgwater A V. Rapid pyrolysis of bio-refinery-biomass [J]. Renewable energy world. 200 1, ( 1): 66~83.9