At present, the design and manufacturing technology of boilers are mainly based on imported technology and domestic manufacturing. Several projects in Shanxian, Gaotang, Shandong Province introduced the straw bio-power generation technology of Danish BWE company. This kind of boiler technology is mature and recognized outside the satellite, but the price is relatively high. At present, China is still in the stage of digesting and absorbing foreign advanced technology, so it is necessary to develop domestic biomass boilers with independent intellectual property rights from the aspects of biomass energy utilization and environmental protection.
The existing biomass boilers in China are mainly crop straws, and the combustion technologies that have been preliminarily possessed are: straw bundling and feeding combined with water-cooled vibrating grate technology, straw and coal mixed combustion technology, and straw cutting and slit combustion technology.
Before burning the baled straw, it is necessary to measure the load-bearing wall of each baled straw with infrared shuttle, and the moisture content is
The technology of co-combustion of straw and coal is also applied in China. Broken straw was mixed into the original pulverized coal boiler in East China Shiliquan Power Plant, but the ash produced was difficult to be comprehensively utilized. The ash produced by single straw combustion has high potassium content and can be used as fertilizer; Fly ash is mainly used as raw material for cement industry. However, experiments have proved that the potassium in the ash from the co-burning of straw and coal has a negative impact on its recycling.
Due to the low calorific value of straw fuel, straw compression molding combustion technology has attracted more and more attention. According to China's national conditions and the needs of the transformation of old power plants with units below 50lW, Shanghai Sifang Boiler Factory independently developed SF-75/3.82t straw boiler, as shown in Figure 3. The main design parameters are as follows.
The volume of straw is compressed to the original110-115 by using compressed fuel. The combustion equipment adopts the scaly chain grate patented by Sifang Factory, which is based on the enzyme-based magnetism of the corner tube boiler grate and combined with the characteristics of biomass fuel leopard. High casting precision, good sealing performance and even ventilation gap. The air chamber adopts a pressure equalizing chamber, and the air pressure in the air chamber is 100-200Pa higher than that in the ordinary furnace, which has strong penetration to fuel and is beneficial to the intensified combustion of the boiler. At the same time, the combustion mode of "combustion chamber combustion+layer combustion" is adopted, and the fuel is sent into the furnace through the adjustable secondary air in front of the furnace. With the cooperation of primary air, the crushed straw is suspended and semi-suspended in the furnace, and the unburned straw falls on the grate to continue burning; Design a high furnace structure, prolong the residence time of flue gas in the furnace, and ensure the smooth operation of suspended combustion and stratified combustion through reasonable primary and secondary air ratio. The boiler structure is compact, the pretreatment area of straw fuel is small, the original coal-fired boiler equipment can be used for fuel crushing and feeding, and the original boiler room and the original fuel storage site can be used without adding too many advanced equipment, which is more suitable for the transformation of the original small thermal power plant. The boiler was installed in Changge Power Plant, put into operation in April 2007 and passed the performance test in September 2007.