Molten slag of blast furnace temperatures up to 1400 ℃ ~1500 ℃, heat, is a high-quality waste heat. Our main water quenching slag treatment processes, a lot of slag by high 


temperature slag-washing water for cooling, temperature of 70℃ ~85℃-producing hot water. Typically, in order to ensure the recycling of slag-washing water needs to be filtered into 


this part of the slag-washing water precipitation-cooling tower, cooling to below 50 deg recycled slag-flushing, or continue to cycle after temperature granulated slag. This process 


is losing a lot of heat, which caused energy waste and pollution to the environment.
Blast furnace slag-washing water as heat energy, because of its temperature stability, flow characteristics, is gradually becoming the waste heat recovery and utilization of research. 


Currently, hedge against water waste heat recovery systems using residue-washing water heating, bath water and waste heat to generate electricity. Slag-washing water research and 


development direction of waste heat power generation is one of the most valuable, but because of its relatively high technical requirements and a longer payback period, is still in 


the research stage of development. Make use of slag-washing water heating or hot tub water has been part of steel mill in the North, and bring good economic benefits.
Water of blast furnace slags containing CaO, SiO2, MgO, Al2O3, and small amounts of Fe2O3,pH value is greater than 7, weakly alkaline. Blast furnace slag in slag-flushing water of 


impurities in the form of solid particles or suspended matter, over time, impurities can make the heating system pipes, valves, radiator massive silting, blockage, blast furnace 


slag-washing water as heat source of heat is not suitable for direct use. Through indirect heat recycle slag-washing water in the form of heating or hot tub water utilization 


technology of blast furnace slag water points, and blast furnace slag water dedicated heat exchanger apply high heat medium hanging in suspended particles, viscosity under severe 


conditions, such as entities.
Slag-washing water heat recovery tool
Slag-washing water dedicated heat exchanger is made of spiral flat-tube heat exchanger components manufacture of new type high efficient heat exchangers, spiral elliptical flat tube 


cross section, the Canal outflow tract are spirally, and obtained the national patent for utility model. The in the heat exchanger has the following characteristics:
Small pressure drop. Shell-and-tube heat exchanger in the shell in order to reduce dead zones and short circuit set a number of baffles and accordingly increases the resistance and 


application of spiral flat-tube making directly to shell the twists and turns of the medium flowing in spiral up-flow, no dead zones, without setting up a baffle. Canceled baffles to 


reduce drag, and greatly improves the efficiency of heat transfer. Slag-washing water dedicated heat exchanger and pressure drop of spiral plate heat exchanger 30kPa and plate heat 


exchangers with fixed tube-sheet heat exchanger pressure drop of the 50kPa~100kPa.
High heat transfer efficiency. In tube drive, fluid of spiral flow enhanced has its turbulence degree, reduction thin has as heat main hot resistance of delay flow within layer of 


thickness, makes tube heat get strengthened; in shell drive, due to spiral flat tube Zhijian of flow road also is spiral-like, fluid in course movement Shi by centrifugal role and 


cyclical to change speed and direction, thus strengthened has fluid of longitudinal mixed. Coupled with fluid after the adjacent tubes form when spirals contact points out in wake of 


the pipe wall, enhanced the degree of turbulence of the fluid itself, makes the shell side of heat transfer can be enhanced. Tube, pipe and its heat transfer enhancement of heat 


transfer effects significantly, especially for larger larger fluid suspensions, viscosity and heat transfer in a viscous flow on one or both sides of the body the effect is 


particularly prominent.
Easy scaling. Fluid in the tubes the spiral flow, centrifugal, constantly scour the lining and the outer wall of the tube so that heat is not easy to scale. Shell and tube sides 


reduces dirt deposits on the Eddy current, and because of the change in flow rate, reducing the likelihood of tube blockage and fouling.
Not blocked. Special heat exchange element with self-cleaning properties, once the matter out of the heat exchanger, particularly filamentous aggregation of suspended matter in slag-


washing water, not easy to stay in the heat exchange element form a wall and clogging the heat exchanger, maintaining long-term normal operation of heat exchangers.
Maintenance-friendly. Slag-washing water dedicated heat exchanger uses a modular design, can be integrated into different systems according to demand freedom, each module is composed 


of two slag-washing water dedicated heat exchanger composed of two heat exchangers as well as during normal operation, in the early, late or heat exchanger heating maintenance and can 


be used alone. Meanwhile, can reserve heat capacity at design time, add modules, the overhaul changes very easily. Because without fouling of heat exchangers, reduce the amount of 


maintenance, can be unattended when used during normal operation.
A heating period to recoup investment
3 a company circulating water of blast furnace slag-washing water for low temperature hot water 4200m3/h, 70℃ ~85℃, can at least give 48,800-kilowatt heat, according to 95% of the 


thermal efficiency, available to nearly 600,000 square meters of residential heating, heating in plant area of 80,000 square metres, or 3000 people, staff's bath room. If the waste 


heat in slag-washing water in place of residential boiler rooms, heating not only benefits also saves coal and reduce thermal pollution, elimination of SO2, NOX, CO2, and sewage water 


pollution caused by dust and other air pollution in boiler room. Slag-washing water temperature, can improve quality of blast furnace slag to improve activity of slag cement made 


from. In addition, the factory area of 80,000 square meters of the building, Office building, dormitory, workshops can be used such as steam heating, if the waste heat in slag-washing 


water of blast furnace instead of steam for heating, steam for electricity generation, can effectively relieve the power shortage. 10.25 million Yuan investment, or a heating period 


about 3 months to recoup investment.
Steel mills in northern China at present heating of waste heat recovery of blast furnace slag-washing water, and there are a number of domestic iron and steel enterprise utilizing 


blast furnace slag water dedicated heat exchanger using blast furnace slag-washing water for heating residential and factory, achieved good operating results.
Analysis on the benefit of
Waste heat in slag-washing water of blast furnace has a huge resource, and its effective utilization of waste heat recovery of economic, environmental and social benefits.
Economic benefits. Current waste heat in slag-washing water of blast furnace blower preheating, that can be used for iron and steel enterprises desalted water preheating and mixing 


hot water and heating, dehumidification and cafeteria equipment bathhouse supplied. This technique in iron and steel enterprises to promote can relieve the pressure of steel 


enterprises energy saving and emission reduction, revenue increased steel prices. Waste heat utilization of blast furnace slag-washing water project payback period of only one heating 


period, can also apply for State energy conservation subsidies, and by way of collection of heating charges, create benefits for the steel mills, and cost savings. Also, because the 


recovery period is short and obvious economic benefit, provides a new way for mills to develop non-steel industry.
Environmental benefits. Blast furnace slag water efficient recycling technology will significantly reduce smog. Using waste heat recovery of blast furnace slag-washing water in the 


North to replace coal-fired boilers for heating (gas of gas-fired boiler for power generation or replacement), put an end to the outside exhaust, coal-fired boiler emissions of 


pollutants such as SO2, reduce the occurrence of smog. Also, do not need to buy a lot of gas or does not need to store coal warehouse or transportation logistics of the coal-fired, 


human, material costs are significantly reduced, while reducing the operating pressures of the city. Industrialization development of low temperature waste heat resource of the mills 


in southern low temperature waste heat power generation technology of Organic Rankine cycle (ORC), waste heat recovery of blast furnace slag-washing water for low temperature waste 


heat power generation and its market prospects.
Social benefits. Waste heat recovery and utilization technology of blast furnace slag water driven mills and innovation management integration with the city's Green for urban and 


integration provides a new way for the development of iron and steel enterprises. According to incomplete statistics, there are 39 city or urban-type iron and steel enterprises in 


steel plant. Steel for residential heating or cooling, water in cities or other industrial wastewater treatment and reuse for urban-type steel enterprises, steel companies and formed 


cascade recycling, the harmonious development of urban water resources. Urban-type iron and steel enterprises and urban form interdependence, the healthy development of a harmonious 


situation, out of a steel and the environment and harmonious urban development of new roads.
Since the expansion of waste heat utilization of blast furnace slag-washing water project in 2013, more than 20 enterprises have signed and implemented the project, when saving to the 


user 154,300 tons, 558,700 tons of carbon dioxide emissions, emissions reductions 178 tons of sulfur dioxide and 1550 tons of emissions of nitrogen oxides emissions 349.2 tons of 


dust. Is expected in 2015, China's annual output of 760 million tons of pig iron, high slag content of about 243 million tons a year, if 30% of waste heat recovery of blast furnace 


slag, slag volume available 73 million tonnes per year. 1 ton blast furnace slag calories equivalent to 0.058 tonnes, annual energy-saving capacity of 4.23 million tons, the carbon 


emissions of 11.17 million tonnes of CO2. The blast furnace slag water dedicated heat exchanger can be scaled, 1000 sets (sets), the production capacity can meet user needs.