| There are abundant cotton straw resources in China.If these cotton straw resources can be fully utilized,huge economic and social benefits will be produced.At present,most cotton straws in China are not fully utilized.The effects of different test parameters on the carbon yield of cotton straw biochar is studied to improve the utilization rate of cotton straws.According to the technical requirements of the cotton straw carbonization equipment,the use of microwave heating has obvious advantages such as fast,efficient,high resource recovery utilization rate,and no secondary pollution.This article has designed a microwave cracking carbonization equipment for cotton straw,which is mainly composed of gas-liquid treatment system,cracking chamber,PLC control panel,nitrogen canister,etc.The main work of this paper is as follows:(1)According to the technical requirements of microwave cracking biochar processing equipment,the technical requirements of microwave cracking biochar processing equipment were established.In this paper,a microwave equipment for biomass energy carbonization is designed.The maximum power of microwave cracking equipment is 2.99kW,and two types of cracking cavity vessels are designed.Simulation results show that when the frequency is 2～2.5GHz,the excitation of magnetron band port is more stable than other frequencies,the frequency of microwave cracking and carbonization equipment is 2.45GHz.(2)Because the structure and shape of microwave cracking chamber have great influence on Microwave utilization efficiency,the electric field simulation of two kinds of cracking chamber vessels in microwave cracking equipment is carried out.According to the electric field simulation results,the electric field strength of the microwave cracking vessel with smooth curved wall is mainly 9.4789 ×102v/m～1.8958×103v/m.and the electric field distribution in the microwave cracking vessel is relatively uniform at this time;the electric field strength of the vessel with non smooth curved wall is mainly 7.2843 × 102v/m～2.0396×103v/m,but the electric field intensity distribution is not uniform.It can be concluded that the curved smooth inner cylinder is better than the curved non smooth inner cylinder as cracking container,so the curved smooth inner cylinder is selected as cracking container(3)Choose carbonization temperature,moisture content of cotton straw and carbonization time as experimental factors.test the microwave carbonization equipment,take the carbon yield of cotton straw as response value,carry out three factors and three levels of quadratic regression test,use box benhnken combination test method to optimize and analyze the optimal combination of microwave carbonization of cotton straw carbon production equipment test factors:moisture content 11%,carbonization time 6.23min,carbonization When the temperature is 300℃,the software analysis predicts that the carbon production rate of cotton straw is 37.84%.When the moisture content was 11%.the carbonization time was 6 minutes and the carbonization temperature was 300℃,the carbon yield of cotton straw was 34.15%.If the relative error between the predicted value and the software is less than 4%,the microwave carbonization equipment can achieve the basic goal.(4)Through the study on the characteristics of cotton straw biochar,it is found that the percentage of carbon elements in the cotton straw charcoal increases gradually with the increase of temperature.With the increase of temperature,the surface of cotton straw is damaged,and the surface of cotton straw gradually appears pore structure.After the study on the adsorption of cotton straw biochar,it was found that the adsorption rate of cotton straw biochar increased with the increase of pH,and also increased with the increase of input of cotton straw biochar. |
