The Experimental Study on Sectional High―pressure Liquefaction of Corn Straw

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Abstract. Biomass can be converted into liquid fuel by high-pressure liquefaction， which is one of the active methods in the treatment of agricultural wastes. This paper chose the corn straw as a raw material， used the sectional high-pressure liquefaction reaction， and transformed the corn straw to the liquid production. Then Investigated the effects of reaction production influenced by the temperature and solvent ratio， induced the key influencing factor was temperature， got the higher liquid yield when the temperature during in 320 ℃ ～ 360 ℃.

Key words： Corn Stalk， High-Pressure， Liquefaction， Temperature， Influencing Factors

1. Introduction

China's agricultural abundant biomass resources have accounted for 14% of total world energy consumption， equivalent to 1260 trillion tons of oil， and ranked No. 4 after oil， coal and natural gas [1，2]. Crop straw resources and stability， overall about 6 to 7.5 billion tons， of which， about 230 million tons of straw， corn stove is about 220 million tons， wheat， beans， straw and other autumn about 150 million tons. Utilization of agricultural waste is the effective way to control agricultural pollution， to improve the rural environment and the development cycle of agriculture， and to achieve sustainable agricultural development.

2. Segmented biomass liquefaction experimental program

Liquefaction of biomass is the pressure at a higher pressure， a reaction temperature， the corresponding solvent， catalyst and gas atmosphere， such as the presence of liquefaction of biomass from the reaction liquid of a thermal conversion process the proportion of the solvent biomass feedstock and catalyst into a high pressure reactor， and a hydrogen gas or an inert gas， at a suitable temperature and pressure the raw material by a thermal chemical reaction liquefied. High pressure is liquefied biggest advantage compared to other methods in that. It is dried without pretreatment of raw materials， to a certain extent， reducing the energy consumption.

2.1 The overall program experiment

In laboratory supercritical reactor CJF-2 as the main experimental research equipment， preparation of wet biomass fuel quality optimal supercritical process conditions and control parameters. Then， it becomes the level of small-scale laboratory scale supercritical liquefaction new device design， manufacturing and experiments， and to achieve non-stem biomass supercritical preparing high-quality biofuels new technology research goals.

Fig.1. The process route of biomass high pressure

The line segments shown in Figure 1 is the high-pressure liquefaction process， pulverized corn wet biomass into packets of about 1 cm， soluble in water， in the first pressure vessel 15 ～ 30 min after softening， softening reactor conditions the temperature is at 200 ℃， a pressure of 30 MPa softens， the raw material a paste， and then out into the second reactor liquefaction reaction， the reaction catalytic liquefaction and direct liquefaction of two methods， the temperature is ranging from 280 ℃ ～ 400 ℃. After the reaction， the separation and purification of crude oil through the biomass obtained biomass liquid fuels （Bio-oil）.

2.2 An experimental process

Experimental materials： corn Stover （Origin： Anhui Fuyang City Yingshang County， particle size d = 10 ～ 15 mm. Solvent： distilled water， ethanol， Na2CO3 and a catalyst such as ZnCl2）

Main instruments： supercritical high-pressure reactor （CJF-2， Dalian Tongda reactor） 2 and so on. Biomass pyrolysis experiment flow chart is shown in Figure 2.

2.3 Leaching process biomass particles

Corn stalks in the segmented liquefaction process； the first stage of softening accelerated Next biomass is liquefaction. Because the pulverized biomass particles after pretreatment， the smaller particles， and in a 2 L batch reactor under stirring device， so it has two characteristics of both the solid - liquid leaching operation in the solid - liquid permeability leaching （Percolation） and the solid - liquid suspension.

Biomass particle diameter range from 0.05 ～ 0.5 cm ranging softening in the reactor is non-leaching heterogeneous catalytic reactions， including liquid， solid， and sometimes gas. The process is consists of a series of mass， heat transfer and chemical reaction step， which is shown in Figure 3.

In Figure 3， it shows the biomass particle leaching process can be summarized as the following steps：

（1） A fluid reactant particles from the fluid within the body through the outer layer of the fluid film to solid - liquid interface diffusion；

（2） The reactant fluid from the surface of the biomass particles to pass through the particle pores or pores inside the particle diffusion；

（3） Fluid reactants and reaction components of biomass particles for chemical reactions；

（4） To generate particles of the fluid product through the pores spread out；

（5） The fluid produced from biomass particles to the surface of the fluid through the fluid film body spread.

In the above step 5， the slowest steps will constitute the entire leaching rate control step of the process， what is the rate controlling step depends on the extraction conditions.

2.4 Segmented pressure liquefied corn Stover experiment

Ratio experiment started， adding biomass feedstock 1/10 Quality of catalyst on the catalytic liquefaction experimental products were analyzed， the results of the biomass yield calculated uses the following formula：

Catalytic liquefaction experiments and data analysis are as follows.

Different concentrations of the reaction catalyst and organic water content of bio-oil yield shown in Table 1， Table 2. As can be seen from the table， when the pyrolysis catalyst is added to significantly improve the production of bio-fuels， and Na2CO3 and ZnCl2 in dosage 8 g， the yield of biofuels maximum is 32.25 % and 32.90% respectively.

Comparison of these two catalysts found ZnCl 2 as a catalyst， the yield of bio-oil and a calorific value higher than the Na 2 CO 3. This is because during the recession the catalyst can promote hydrolysis and cleavage reaction. Since the decomposition products of straw material composition are relatively complex， it contains a variety of chemical substances； different catalysts have different components of different catalytic effect.

3. Results and discussion

Liquefied in a different ratio of raw materials in the choice of a good temperature， use of different materials ratio liquefaction experiments， respectively， for 5g， 7.5 g 12.5g， and 15g/100ml water ratio of liquefaction experiments. Experimental data are shown in Table 3.

3.1 Liquefaction effect of temperature of the product

The temperature at a fixed ratio of raw materials the change of product yields of Figure 4 is shown in Figure 4.

Analysis of several figures above， the following conclusions can be drawn.

（1） With the temperature rising， direct liquefaction of biomass tar yield decreased productivity. 400 ℃ the tar Heat stable at close to over 400 ℃ significantly increased.

（2） With the temperature rising， the product ash direct liquefaction of biomass production declined.

（3） With the temperature rising， the organic biomass direct liquefaction product hydrate volume gradually decreased. Hydrate pH value decreases with increasing temperature increments.

3.2 Different solvent ratio on the impact of the product

Primarily investigated by experiments when the temperature is constant， the solute / solvent ratio of the product of the case.

Test temperature was maintained at a fixed temperature of 360 ℃， the ratio of the change of the product， mainly on the ratio of solvent to yield of tar， tar than the heat influence on the impact of ash， the ash of heat， the volume of gas hydrate influence on the pH of hydration， and the volume of fuel of biological effects， the effect relationship is shown in Figure 10 to Figure 16.

Comparing each response curve， the following effects can be obtained.

With the temperature rising， direct liquefaction of biomass yield of their products gradually increased. The heat is gradually increased with temperature.

With the temperature rising， direct liquefaction of biomass ash product yield gradually increased. Heat decreases with increasing temperature.

With the temperature rising， biomass direct liquefaction product hydrate volume gradually decreased. PH value gradually increased with increasing temperature.

With the temperature rising， decreased the volume of biofuels.

4. Conclusion

Based on the analysis of biomass liquefaction supercritical reaction mechanism and the basic theory of the model， the liquefaction of biomass of a partial pressure was investigated， and the ratio of temperature and pressure and other factors， the results are analyzed for a more in-depth research. It can obtain the following preliminary conclusions.

High biomass liquefaction conditions were optimized compared directly without the high pressure leaching liquefaction case reaches the preset temperature， the reaction time is generally about 100 ～ 120 min， and after leaching softened， then reaction， the temperature reaches the preset time is generally 50 ～ 60 min minutes and can significantly shorten the reaction time， increase the reaction rate.

Found by experiment， the catalyst added can significantly accelerate the reaction by adding ZnCl 2 can increase the yield of bio-oil 5% to 6%， which is because the catalyst during liquefaction and hydrolysis from the cleavage reaction can to different degrees of enhancement.

Biomass liquefaction many factors， the temperature is a critical impact factor. The reaction is added to the catalyst， the direct liquefaction of biomass yield of the product was significantly affected by temperature， and the reaction temperature is between 320 ℃ ～ 360 ℃. However， due to high pressure liquefied reaction involves a large number of influencing factors， the need for further research content.

Compared with the fast pyrolysis， pressurized liquefied currently still in the laboratory stage， but because of its relatively mild reaction conditions， the equipment requirements are not very demanding， the most important is that it has more traditional paralysis is a key advantage of drying of biomass， biomass pretreatment process can save the extra energy costs， which has good prospects for development and application. As high pressure liquefaction of biomass into a variety of factors involving the need for further research， including biomass liquefaction reaction mechanism and reaction equipment continuity， work， etc.， are the follow-up research institute to solve the problem.

5. Acknowledgement

This article was financially supported by the Education Department of Anhui Natural Science Foundation （2010） ---"Agricultural Waste direct liquefaction key technologies"， and the introduction of talent issues Anhui Science and Technology （2012） ---"jet-liquefaction temperature Predictive Control System".

References

[1] JIANG Jian-Chun. Biomass Research Status and Development Prospect [J]. Forestry Chemistry and Industry， 2002，22 （2）： 75-80

[2] Zhang invincible， Song Hongchuan etc. Conversion of biomass energy development and utilization of technology [J]. Energy Research & Utilization， 2000， （02） ： 1-6

[3] Ren Zhongjie， Gu Ong. Comprehensive utilization of crop straw and Circular Economy [J]. Agricultural Sciences， 2005，33 （11）： 105-106

[4] Money can blog. Status quo of China's forestry resources and potential of biomass energy [J]. Chemical Industry， 2007， （07）： 1-5

[5] Minowa T.， Kondo T.， Sudirjo S T. Thermochemical liquefaction of Indonesian biomass residues [J]. Biomass and Bioenergy， 1998 （14）： 517-524

[6] Yamada T.， Ono H. Rapid liquefaction of lingo cellulosic waste by using ethylene carbonate. Bioresourece Technology 1999 （70） ： 61-67

[7] T， Yokoyama S. Liquid’s fuel production from woody biomass by direct liquefaction [J]. Sekiyu Gakkaishi， 1993，36 （20） ： 73-84

[8] Demirbas A. The effect of learning content on aqueous liquefaction products of biomass [J]. Energy Conversion & Management， 2000， （41）： 1 601 - 1 607

[9] Fatma K.， Bolat E. Coprocessing of Turkish lignite with a cellulosic waste material II. The effect of co-processing on liquefaction yields at different reaction pressures and sawdust / lignite ratios [J]. Fuel Processing Technology， 2002 （75）： 109 -116