Combustion behavior and pollutant emission characteristics of polymers and biomass in a bubbling fluidized bed reactor

To measure the combustion and emission characteristics of the boiler using the pelletized biomass fuel,a boiler combustion simulation test-bed was built Experiments were performed with the test bed about the effects of different ratios between the primary and secondary air flow rates,and their supply positions,as well as the fuel layer thickness on the combustion performance and emission behavior,providing credible informations for the design of pellet biomass boiler The test operation and practical trial of the prototype show that this kind of boiler is characterized by high efficiency,fuel saving,clean combustion and low air pollution, opening up broad prospects for its pratical application

Combustion and emission characteristics of boiler using pelletized biomass fuel

Aiming at the influence factors in the biomass layer combustion process,this paper introduces the relative research progress on the biomass fuels physical properties,air supply and form of grate movement.Meanwhile,this paper summarizes the combustion process changes about the particle size,density,total moisture,wind distribution,wind speed,air preheating and grate movements in detail.However,the influence factors of layer combustion process are still in the initial stage of research.

Analysis of the influence factors of biomass layer combustion process

Experiment on fuel flexibility of biomass pellet burner.

The arch is an important component of a biomass boiler. Initial arch design of most boilers is generally gained through manual computation, thus resulting in uncertain reasonability of flue gas flow. Moreover, biomass fuels in the market have instable characteristics, which influence the utilization of biomass energies considerably. To address the problems concerning reasonable flue gas flow caused by the collaborative design of arch and air staging and the combustion adaptability of fuels, a cold modeling experiment of a 1 t/h biomass boiler under different staged air distribution ratios when the rear arch coverage varies was conducted using Fluent software in this study after thermal performance computation and initial structural design of grate and furnace. Furthermore, a boiler performance test based on main fuels and a combustion adaptation test of auxiliary fuels were also performed. The experiments show that the best flue gas flow in the furnace is achieved when the rear arch coverage is 60% and the primary–secondary air distribution ratio is 4:6. The mean boiler efficiency and the mean boiler heat output are 81.26% and 715.76 kW/h by using Pinus koraiensis pellets, wood–straw mixed pellets, and cotton straw briquettes as main fuels; and the tested pollutant emissions are in compliance with the limits of the national standard. The results of the combustion adaptation test reveal that the excessive particle size, the high ash content and the relatively low calorific value of biomass molded fuels are all against the combustion of biomass boilers. Fuel upgrading based on washing process and other methods is suggested. This study can provide references to the performance optimization of traditional small-scale biomass chain heating boilers.

/pdf/design-of-a-1-t-h-biomass-chain-boiler-and-its-fuel-1o7orjr4sw.pdf

Zhang Zhengchuan

Papers

Design of a 1 t/h Biomass Chain Boiler and ιts Fuel Adaptability Analysis