First, the preamble The steel industry is a major energy consumer in the industrial sector and one of the industries with the greatest potential for energy saving and emission reduction in China. During the "11th Five-Year Plan" period, the steel industry was frequently named on the one hand and became the focus and difficulty area of ​​energy conservation and emission reduction in the whole society. On the other hand, the achievements made in energy conservation and emission reduction in the steel industry also contributed to promoting energy conservation and emission reduction for the whole society Made a great contribution. In September last year, the state has promulgated the "Regulations for the Production and Operation of the Iron and Steel Industry" and made specific requirements on the environmental protection, energy consumption and resource recovery and utilization, and technological equipment of the iron and steel enterprises. "Conditions" made it clear that for enterprises that do not have standardized conditions need rectification in accordance with the requirements of the regulatory conditions, rectification and reform still can not meet the requirements of the enterprise should gradually withdraw from the steel production. For those enterprises that do not meet the standard requirements, relevant departments shall not approve or file new projects, shall not allocate new mines resources and land, shall not issue new product production licenses, and will not provide credit support. The country's environmental laws and regulations will be more stringent, energy-saving emission reduction task more difficult, the steel industry is also more pressure. In the "Twelfth Five-Year Plan" outline of the steel industry development priorities, energy-saving emission reduction-related content accounted for the majority: to support non-blast furnace iron and steel, clean steel production, comprehensive utilization of resources and other technology development; focus on the promotion of energy management and control System technology and high temperature and pressure CDQ, comprehensive utilization of waste heat, sintering flue gas desulfurization and other energy-saving emission reduction technology. Second, the blast furnace slag residue waste heat utilization At present, the recycling rate of waste heat energy in the steel industry is quite low. Among them, high temperature waste heat is relatively easy to recycle, and most of the technical revamp in energy saving has been recovered at present. However, the recovery of low temperature waste heat is almost zero, Slag heat, mostly wasted. It should be pointed out that the low-temperature waste heat accounts for about 35% of the total waste heat, so the low-temperature waste heat in the steel industry has huge potential for recovery. Iron and steel plant in blast furnace ironmaking process, the resulting slag temperature is about 1000 ℃. At present, most iron-smelting companies work out by rapidly quenching high-velocity water from a slag pump in a slag tank into slag and pelletizing it for the production of cement. Generally about 0.3t slag discharged per ton of iron, each ton of slag can produce 80 ~ 95 ℃, 5 ~ 10t of slag water. In order to ensure the recycling effect of slag water, this part of slag water needs to be introduced into the air cooling tower after sedimentation and filtration, and the slag is recycled again after cooling to below 50 ° C. In this way, a large part of the heat is lost in the air-cooled tower, which not only causes waste of energy but also causes thermal pollution to the environment. If we can make rational use of these waste heat, we can save energy, reduce operating costs, but also protect the environment and reduce thermal pollution. The use of heat pumps is an effective way to solve this problem. As an effective energy-saving technology, heat pump is becoming an effective tool to utilize low-grade energy. According to the different driving energy, the heat pump can be divided into electric driven vapor compression heat pump, steam or waste heat-driven absorption heat pump and heat-driven steam jet heat pump three categories. The use of high-temperature heat source, the low-temperature heat source (such as waste heat) to some intermediate temperature and use it as a heat pump is called the first type of heat pump, such as domestic heat pump air conditioners; use a large number of intermediate temperature waste heat and the waste heat source and low temperature heat source Heat potential difference, to make less heat but the temperature is higher than the temperature waste heat hot water or steam heat pump for the second type of heat pump, such as heat pump dryer. Therefore, the absorption heat pump, especially the second heat pump, has great potential in metallurgical enterprises. 1. Preparation of high temperature water or low pressure steam The blast furnace slag water sedimentation filtration, water-water heat exchange, and then through the absorption heat pump unit, the use of a large number of slag in the water temperature heat source for heat driven by a large number of medium temperature and low temperature heat source heat potential difference, Preparation of high-temperature water or low-pressure steam, part of the low-heat transfer to higher temperatures, thereby increasing the utilization of heat sources, but also the slag water cooling. Preparation of steam can be used for plant or plant around the building heating, bath or make up for the boiler. Take a steel plant with an annual output value of 100,000 tons of steel as an example, it produces 180,000 tons of 90% slag water every year. Through the absorption heat pump to slag water cooling to 60 ℃, you can get 62.8MW heat, equivalent to 1046 tons of standard coal combustion heat. 2. Preparation of process cooling water There are many departments in the iron and steel industry in the production process need to obtain low-temperature refrigerant water for process cooling and air conditioning and refrigeration, such as steel mills, coke oven gas purification process, the main electrical room, electrical control room, computer room, console, instrumentation , Various office buildings, residential areas and so on. From the cooling requirements, some can use higher temperature cooling water, and the cooling process must use lower temperature cooling water, this part of the low temperature cooling water will need to be made through the refrigeration unit. Absorption heat pump units can be used, the use of blast furnace slag water cooling. Shougang is the first steel company in China that uses blast-furnace slag water for refrigeration. While meeting the cooling capacity of air-conditioners in multiple departments, it fully utilizes the waste heat resources to achieve the purpose of saving energy and reducing consumption. To take the 5000kW cold as an example, such as the use of compressed air compressor units, electric compressor unit energy efficiency COP calculated by 3.0, hourly full load costs, power consumption of 5000kW / 3.0 = 1666.7kWh. Electricity cost per kilowatt-hour is calculated at 0.55 yuan, then the operating cost per hour of compressing cold-water unit is 916.7 yuan. Selection of double-effect absorption heat pump refrigeration, hourly full load costs, the consumption of steam 6.25t / h, steam price 80 yuan / ton, then 500 yuan per hour. It can be seen that the absorption heat pump refrigeration costs 54.5% of electricity. Power generation The general idea of ​​slag-water waste heat recovery power generation system is: The system is mainly composed of a circulating refrigerant generator, a power machine, a working fluid circulating booster pump and a generator. Recycle the working fluid into the waste heat steam generator to absorb the heat of the slag to vaporize the working substance vapor. Working fluid into the power machine steam, to promote power machine rotation, and drive the generator to generate electricity. Power engine itself has the function of reducing temperature and decompression. Under the action of the booster pump, the liquid working fluid enters the waste heat steam generator to absorb the heat again and circulates back and forth. Each tonne of 90 ℃ hot water can generate 1.5kWh, discount coal 0.6kg, 80 ℃ hot water can generate 1kWh, discount coal 0.4kg. Taking a steel plant with an annual output value of 100,000 tons of steel as an example, it produces 180,000 tons of 90% slag water each year. Slag water is cooled and recycled after being used in the cooling tower. The annual water consumption is about 19,000 tons. The slag residue waste heat for power generation, the annual power generation capacity of 270000kWh, 108 tons of standard coal savings, saving 19,000 tons. Twinkle System Technology Co Ltd , https://www.pickingbylight.com