Biogas is a kind of clean energy, which not only helps to reduce the greenhouse effect and promote the virtuous cycle of ecological environment, but also can replace fossil fuels such as oil and coal. It has become an important way to solve the energy and environmental problems. The use of biogas power generation can not only alleviate the current situation of power supply shortage, but also has high utilization value in the process of power generation.

沼气发电机在发电的同时，烟气温度一般在550℃左右，通过余热回收技术，将燃气内燃机中的润滑油、中冷器、缸套水和烟气排放中的热量充分回收利用，用于冬季采暖以及生活热水。夏季可与溴化锂吸收式制冷剂连接，作为空调制冷。一般从内燃机余热回收系统中吸收的热量以90℃的热水供给热交换部分使用。内燃机正常回水温度为70℃。

Biogas generator generates electricity at the same time, the flue gas temperature is generally about 550 ℃. Through the waste heat recovery technology, the lubricating oil, intercooler, cylinder liner water and heat from flue gas emission in gas-fired internal combustion engine are fully recovered and utilized for heating and domestic hot water in winter. In summer, it can be connected with lithium bromide absorption refrigerant as air conditioning refrigeration. Generally, the heat absorbed from the internal combustion engine waste heat recovery system is supplied to the heat exchange part with 90 ℃ hot water. The normal return water temperature of internal combustion engine is 70 ℃.

沼气发电机组余热的利用方式，大体分为两种，一种是排烟的余热利用，另一种是发电机组冷却热量的利用，常见的余热利用方式一般有热水型、烟气型、蒸汽型、发电型四种。其中热水型是利用发电机余热产生90度或更高温度的热水，这种方式一般用于需要供暖的北方地区，烟气型是利用烟气的余热配合吸收式制冷机组,提供冷源负荷;蒸汽型是利用烟气余热产生饱和蒸汽或者过热蒸汽，=一种发电型则是利用发电机余热，配合螺杆膨胀动力机发电。

There are two ways to use the waste heat of biogas generator set, one is the use of exhaust heat, the other is the use of cooling heat of generator set. There are four common ways to use the waste heat: hot water type, flue gas type, steam type and power generation type. The hot water type uses the waste heat of the generator to generate hot water of 90 degrees or higher, which is generally used in northern areas where heating is needed. The flue gas type uses the waste heat of the flue gas to cooperate with the absorption refrigeration unit to provide the cold source load; The steam type uses the waste heat of flue gas to generate saturated steam or superheated steam, while the power generation type uses the waste heat of generator to generate power with screw expansion power machine.

目前，大多数发电设备将余热利用设备与发电机组集成一体化，即换热装置在机组内部，不用单独配置。设备只需要三个接口：进、回水接口和沼气接口，设备可与热水锅炉并联连接，既简化了系统，减少了设备及占地面积，利于运行维护，同时也减少了系统工程总投资，据统计，沼气发电余热综合种用率可达80%，在发电并网的同时，减少了能源消耗，方便了电站的给管理，也提高了沼气发电工程的自我供应能力。

At present, most of the power generation equipment integrates the waste heat utilization equipment with the generator set, that is, the heat exchange device is inside the unit, and there is no need to configure it separately. The equipment only needs three interfaces: inlet and return water interface and biogas interface. The equipment can be connected in parallel with the hot water boiler, which not only simplifies the system, reduces the equipment and floor area, is conducive to operation and maintenance, but also reduces the total investment of system engineering. According to statistics, the comprehensive utilization rate of waste heat from biogas power generation can reach 80%, and reduces energy consumption while connecting the power generation to the grid, It not only facilitates the management of power station, but also improves the self supply capacity of biogas power generation project.