To achieve energy transformation and reduce carbon emissions, renewable energy must be developed vigorously. As an important part, biomass energy can be used in a variety of ways and has good prospect for development. Biomass gasification-coal coupling for power generation is an important technology and development direction of biomass energy utilization, which has a small impact on the coal-fired boiler, high power generation efficiency and is easy to monitor electricity. In order to investigate the system characteristics of biomass gasification-coal coupling for power generation, it is first necessary to understand the biomass gasification process and obtain the components of biomass gasification gas and related gasification indexes. This paper establishes a biomass gasification model based on thermochemical equilibrium, and obtains the relationship curves between gas components, gasification index and gasifying agent equivalent ratio, water content through Visual Basic programming. The results show that with the increase of water content, the calorific value of gas and the gasification efficiency decrease, whereas the gas production rate increases. And as the gasifying agent equivalent ratio increases, the gas production rate and gasification efficiency increase, while the gas calorific value decreases. These relationship curves can provide reference for the gasification process control, and can also lay the foundation for the design and optimization of the biomass gasification-coal coupling for power generation system.

The 20 MW/10 MW combined electricity generate system is studied which contents the biomass gasifier with the thermal power 60 MW/30 MW and the 660 MW coal fired boilers. In the negative-positive pressure single circulating fluidized bed gasification system, the circulating fluidized bed and fixed, bed system which tandem the two functions gasification and pyrogenic decomposition, the dual circulating fluidized bed combustion, gasification tandem bed system, specific analysis, argumentation and comparison are carried out from the engineering application and project demonstration perspective for the system's layout scheme. For variety of biomass fuel, ‘the positive pressure circulating fluidized bed gasifier and heat exchanger system’，and ‘the positive pressure circulating fluidized bed＋positive pressure fixed bed＋semi-coke back bed/straight row system’ are considered as alternative optimize scheme. After the implementation of the project, it will make important demonstration effect on the coupling of biomass gasification and coal combustion boilers.

This paper studies two reburning power generation projects with 10 MW/20 MW gas power in a company based on 660 MW supercritical coal-fired unit boilers with biomass gas induced in. The optimized burner modification scheme is selected combined with the specific features of ‘four corners cutting circular’ and ‘front and back wall hedging’ boilers. According to the specific gas intake method, we comprehensively analyze the NO_x emission, main parameters change, low load stable combustion, heating surface corrosion and furnace slag, etc. Also, the performance accounting and computational fluid dynamics (CFD) numerical simulation calculation are carried out in the commissioned boiler factory before and after mixed burning. The NO_x decreases obviously, the exhaust temperature increases, and the calculation efficiency of the boiler decreases after burning gas intake in various working conditions.