Development prospect of domestic biomass power generation technology and equipment

The basic principle of biomass gasification power generation technology is to convert biomass into combustible gases (carbon monoxide, hydrogen, etc.), and then use the heat generated by the combustion of combustible gas to convert into electricity through power generation equipment. To some extent, it makes up for the shortcomings of biomass which is difficult to burn due to its own characteristics. The process flow of biomass gasification power generation mainly includes the following steps: The biomass raw materials after raw processing are sent to the gasifier through the feeding equipment or conveyor belt. Due to the oxygen content is limited by the volume of the furnace body, incomplete reaction occurs in the biomass combustion. At this time, the commonly used process is to recover and preheat the gasification gas, that is, heat exchange between the high-temperature gas and the material to heat the biomass raw materials, and then filter the gas through the cooling system and purification device. The purified gas goes into steam turbines and internal combustion engines to generate electricity. Compared with traditional direct combustion power generation technology, gasification power generation is cleaner and more reliable. In addition, it is the flexibility of gasification technology, which can combine the waste steam generated in the process with the thermal boiler power generation system, and the addition of steam turbine ensures efficiency, small scale, small investment, low cost and high economic efficiency.

3.3 Biomass coupled power generation technology

In 1970, many developed countries in the world began to put forward the theory of biomass power generation technology. It was precisely because of the emergence of the global fossil energy crisis that Denmark [7] took the lead in vigorously promoting the power generation technology based on straw and other biomass in order to ensure energy security and alleviate energy pressure. After the 1990s, biomass power generation technology and theory began to spread and develop rapidly in many developed countries [8]. In the traditional technology of biomass power generation, in fact, it also includes the combined power generation technology of biomass and coal, oil and natural gas, but in the industrialization and application, it is often dominated by small equipment, which is also directly related to the development and national conditions of the power industry in Western countries.

In fact, in developed countries more than 300MW of power generation equipment and technology is actually rare. In China 300 ~ 600MW equipment will be the main application equipment, the development of small biomass generator set can adapt to the international leading biomass power generation technology trend, but also to adapt to the actual national conditions of domestic power development. This will not only solve the problem of burning more coal, but actually solve the technical scope of the transition from coal to clean energy.

4 Biomass power generation process

After the processing of biomass raw materials such as agricultural and forestry wastes and forestry wastes, they are transported to the gasifier, where they begin thermal cracking and carbonization under the dual action of high pressure and high temperature, and a large amount of mixture gas is produced in this process. The main components of these gases are high concentrations of carbon monoxide, hydrogen and methane. When these mixtures with calorific value come out of the furnace, the gas temperature is basically in a high temperature state (800~900 ° C), in order to make full use of this part of the gas, easy to calculate the calorific value and scientific measurement, so that it can be reduced to a low temperature below 400 ° C, after cooling the biomass mixture is transmitted through the transport system, part of it is sent into the boiler for combustion. Another part of the waste gas with the calorific value is returned to the pretreatment stage for heat reuse. According to this step, the biomass power generation process is divided into the pre-treatment of biomass raw materials, the heating of circulating fluidized bed gasifier, the cooling and pressure reduction of mixed gas, the pressure of combustible gas, the detection and accounting and measurement of biomass mixed gas combustion. In the above links also need to purge and circuit protection and security system. The core factor in these links is the equipment and technology of biomass hot gas coupling.

5 Main process equipment of biomass power generation technology

5.1 Circulating Fluidized Bed (CFB) gasifier

The circulating fluidized bed (CFB) [9] gasifier is mainly composed of an upper part, a lower part and a tail part. Each link and each part of this has high temperature and high pressure resistance protection treatment. The two-stage suspension is the key part to ensure the adequate reaction of biomass gasification. The lower part of the gasifier is mainly composed of the main air chamber, the wind baffle, the cap body and the sealing phase. In fact, the first suspension part is the reaction zone of the main chemical reaction process, and the second suspension part only ensures the smooth progress of the gasification process. The tail of the furnace body is equipped with cyclone and electrostatic dust removal equipment. In order to make the exhaust gas does not cause secondary pollution at the same time can simply remove the gas and solid impurity particles.