Waste heat power generation
Technology that uses excess thermal energy in the production process to convert it into electrical energy. Waste heat power generation not only saves energy, but also benefits the environment. The important equipment for waste heat power generation is the waste heat boiler. It uses heat or combustible substances in working fluids such as waste gas and waste liquid as a heat source to produce steam for power generation. Because the temperature of the working medium is not high, the boiler is large and consumes a lot of metal. The waste heat used for power generation mainly includes: high-temperature flue gas waste heat, chemical reaction waste heat, waste gas, waste liquid waste heat, low-temperature waste heat (less than 200 ° C) and so on. In addition, there are also those that use excess pressure differential to generate electricity; for example, the blast furnace gas has a higher pressure on the top of the furnace, which can be used by the gas turbine generator to generate electricity before it is sent to the gas user.
There are many ways to recycle waste heat. Generally speaking, the comprehensive utilization of waste heat is the best; the second is the direct use; the third is the indirect use (producing steam for power generation). Such as the steel industry: coke ovens in steel plants. At present, China's large and medium-sized iron and steel enterprises have more than 50 coke ovens of various sizes. In addition to Shanghai Baosteel's industrialization level has reached the international level, the remaining manufacturers have high energy consumption levels and have great potential to be tapped. The converter flue gas power generation in the steelmaking plant currently has 240 converters with a capacity of more than 25 tons across the country. It is equipped with a set of power generation systems based on 3 and can be configured with 80 power stations with a capacity of 3000Kw. There are currently more than 20 electric melting furnaces in steelmaking plants in the country, of which 65 tons can generate more than 5000Kw / seat.
2. Equipment introduction
Single-stage steam turbine: It is widely used in various process industries, and is generally used as a stable and economical driving device for water pumps, oil pumps, fans, compressors and generators.
Multi-stage steam turbine: High reliability and stability have made multi-stage turbines occupy an important position in the process industry. Multi-stage turbines have the characteristics of focusing on reliability and ensuring high efficiency, which can meet the needs of different industrial energy sectors.
Steam Turbine Generator Set: Provide customers with tailor-made steam turbine generator set solutions. Saturated steam turbine generator sets a perfect way for the utilization of saturated steam due to its stable and efficient characteristics.
Residual pressure power generation
During ironmaking, coke and iron ore are put into the blast furnace, and a large amount of hot air is blown by a blower. Once the oxygen in the hot air contacts the carbon in the coke, it will immediately burn and produce a large amount of gas. Most of the gas and iron ore undergo a chemical reaction to separate iron. The rest of the gas is like a pressure cooker that boiled the meal and was freed from the pressure reducing valve. Using this part of the residual voltage to generate electricity is called residual pressure power generation. Also called blast furnace pressure power generation.
After the residual pressure power generation blast furnace gas is removed by a bag filter, the high-pressure, high-temperature, dry and clean gas enters the turboexpander through multiple valves; the first stage of the turboexpander is adjustable. Use it to adjust the flow rate and Pressure; and then the gas is turned into the cascade by the deflector. The gas expands and works in the flow path composed of the stationary cascade and the moving cascade. The pressure and temperature are reduced and converted into kinetic energy to make the working wheel (rotor and The moving blade) rotates, and the working wheel drives the coupled generator to generate electricity.
1. Process flow
The blast furnace waste gas enters the intake manifold of the bag filter through the semi-clean gas pipe behind the gravity precipitator. A bypass is provided between the air inlet of the bag filter and the bag filter, and a cold heat exchanger is provided on the bypass for heating and cooling the gas. The bag of the bag filter is a flumex chemical fiber product. Its working temperature is 80 ℃ ～ 250 ℃, and it is not allowed to exceed 500 ℃ for an instant. Gas temperature below 80 ° C is prone to dew condensation. Dew in the bag will swell with dust, which will reduce the dust removal effect of the bag. In severe cases, the gas flow will not flow smoothly. Gas temperature above 250 ° C will cause the bag to change. Crispy or even burned. Therefore, the setting of a bypass cold heat exchanger to cope with the change of the gas temperature is a condition for the dry bag filter to work normally.
In the next step, the clean gas from the dry bag filter will enter the turbine. At this time, the net gas temperature is between 120 ° C and 180 ° C, and the dust content is 1.2 to 4.6 mg / m3. The net gas from the turbine enters the company's net gas network. The blast furnace gas of some iron-smelting enterprises adopts wet dust removal method, that is, a duct type dust removal device is used after the gravity dust collector, and the net gas produced can still enter the turbine to generate electricity.
From the working principle, the TRT device replaces the high-pressure valve group of the original gas system. The difference is that the high-pressure valve group of the original gas system leaks out the pressure energy of the gas, while the TRT device can recover 30% of the blast furnace blast energy. %about.
After the blast furnace gas is removed by a bag filter, the high pressure, high temperature, dry and clean gas enters the turboexpander through multiple valves; the first stage of the turboexpander is adjustable, and it is used to adjust the flow and pressure; Through the deflector, the gas is turned into the axial direction into the cascade, and the gas continuously expands and works in the flow path composed of the stationary cascade and the moving cascade, and the pressure and temperature are reduced, and converted into kinetic energy to make the working wheel (rotor and moving blade) Rotating, the working wheel drives the coupled generator to generate electricity.
Coal mines, chemical plants, metallurgy, brick making plants, cement plants, paper mills, thermal power and other industrial and mining industries will generate a large amount of waste heat and pressure during the production process. The waste heat and pressure reuse project recovers a large amount of waste heat residual pressure of the exhaust gas that causes environmental thermal pollution. At the same time, the entire thermal system does not burn any primary energy and will not cause any pollution to the environment. This is effective for saving energy and reducing Dust and carbon dioxide emissions, reducing the greenhouse effect, and protecting the ecological environment play a positive role.