Process simulation of the fusion decoupling combustion for biomass.

ABSTRACT

Based on the idea of the decoupling combustion technology and considering the effect of the high temperature on the coking and slagging, a fusion decoupling combustion technical scheme is proposed. The technical scheme divides the continuous combustion process into the fusion gasification stage and gasified gas combustion stage. During the fusion gasification stage, the air required for the gasification reaction is preheated to keep the temperature in the gasification zone above the ash fusion temperature. Then, the high-temperature gas flows into the combustion zone. Meanwhile, the flue gas and the air required for the combustion are introduced, thereby ensuring the burnout of combustible components and decreasing the NOx emission. Corresponding process model is established on the Aspen Plus platform. Through comparison with experimental data, the rationality of the modelling method is verified. And the simulation results show that in the scheme, the mass fraction of carbon in raw biomass could be converted completely. With the increase of ER from 0.33 to 0.47, LHV of product gas decreases from 5.5 MJ/Nm3 to 1.5 MJ/Nm3. The rising preheating temperature could decrease the content of H2 and increase the content of CO, which leads to that the LHV keeps the same, thereby that the effect of preheating temperature on the combustion zone could be ignored. The relationship between preheating temperature and the ratio of Air1 plays a decisive role in the implementation of the scheme. When the ratio of Air1 is equal to 0.47, the NOx emission is lower than 70 mg/m3.