February 22, 2022

Application of spray system technology in metallurgical combustion

The spray system usually has four categories of cooling, cleaning, spraying and special applications, and is widely used in metallurgical gas systems, mainly including gas cooling, dust removal, mixing, pipeline compressor impeller equipment cleaning, equipment anti-corrosion, etc.

1. Gas cooling in the clean gas pipeline in front of the gas tank

1. Gas cooling in the clean gas pipeline in front of the gas tank
Using a bag filter, the temperature of the outlet gas can reach 200 degrees. If it needs to enter the gas tank, it must be cooled to 50 degrees to protect the sealing material of the gas tank. Saturated cooling towers or indirect water-cooled heat exchangers are often used for cooling, and there is a large amount of cooling water. , heat exchanger scaling and other problems, we have successfully adopted the partial evaporative cooling technology of nitrogen atomizing nozzles in the gas pipeline, and achieved remarkable results.

2. Gas cooling before the inlet of the blast furnace bag filter

In the blast furnace smelting process, blast furnace gas is discharged from the top of the furnace through the rising pipe and the descending pipe. After dust removal and purification, it is directly used for combustion equipment such as hot blast stoves. The remaining part will be sent to the gas cabinet through the pipeline for storage. In the blast furnace gas system, the nozzle spray system is mainly used for gas cooling on the top of the blast furnace/gravity dust collector, and anti-corrosion of the gas pipeline in the gas pipeline in front of the gas cabinet.
Under abnormal conditions of the blast furnace, the top gas temperature will be high, up to 700 degrees, and it must be cooled quickly. The use of ordinary furnace roar watering can meet the protection of the furnace top equipment, but it is easy to cause the bag to stick, and sometimes it is forced to It is wasteful and polluting to release waste gas. We have successfully solved this contradiction by using nitrogen atomizing nozzles, which can achieve dry cooling. The blast furnace gas does not need to be released when water is drawn, and it can still enter the bag. The system is best located on the top of the furnace. , can play a dual function, and some blast furnaces are arranged in the gravity dust collector, just to protect the bag, after using the nitrogen air atomizing nozzle, you can no longer use the metal tube heat exchanger, reduce the maintenance amount and TRT power generation efficiency, The direction of further upgrading and improvement of this technology is to have the function of rapidly heating up to 150 degrees when the gas temperature is low (below 85 degrees).

3. Spray lye to prevent corrosion of clean gas pipeline

In blast furnace smelting, due to the presence of chlorine in the charge, there is also chlorine in blast furnace gas. In dry dust removal, as the temperature of the gas decreases, the moisture in the gas will condense out, and the chloride ions will condense into acid water. There is a serious threat to the clean gas pipeline, compensator, valve and other equipment. In some plants, the pipeline is corroded and leaked after a long time of operation. The use of anti-corrosion pipeline is very expensive, and it also corrodes the valves, stainless steel compensators, Pipeline leakage plates and other equipment are scaled on the pipes, and after the scales fall off, they block the pipes and the grid bricks of the hot blast stove. Therefore, measures must be taken to remove chloride ions. Water spray absorbs chloride ions to reduce the corrosive effect on the equipment. The spray water is replaced after a certain concentration. This method is simple and reliable, and the equipment investment, operation cost and maintenance amount are high. In particular, it will offset the dry dust removal and increase power generation. And the effect of water saving, we designed a method of spraying lye to dechloride ion, that is, spraying lye with nitrogen air atomizing nozzle to achieve evaporative cooling, and at the same time play the role of cooling and dechlorination, and can also use alkaline wastewater , to achieve waste treatment, reduce equipment investment and operating costs.

4. Wet dust removal of blast furnace gas saves water and energy

We still have a considerable part, especially the large blast furnaces still use the wet dust removal method of the two or the steam spray tower, the large amount of water spray and water treatment, and the high system resistance cause a lot of waste of energy and operating costs. Method cooling technology, assisting the improvement of nozzle type, layout and water supply system, can reduce the water volume by 30%-50%, solve the problem of nozzle blockage, and reduce system resistance. Large-aperture air atomizing nozzle, using on-site small circulation series water supply, etc.