Nozzle spray system is usually cooling, cleaning, spraying and special application of four categories, widely used in metallurgical gas systems, mainly gas cooling, dust removal, mixing, pipe compressor impeller equipment cleaning, corrosion prevention equipment. This paper gives a comprehensive introduction, especially the successful application in China, for the reference of relevant personnel.

Nozzle and spray technology

Nozzles are precision perforating parts designed for specific functions. They must be used together with related equipment to form a spray system.

In abnormal situation, blast furnace top gas temperature is high, up to 700 degrees, must undertake rapid cooling. The use of ordinary roar sprinkler can meet the protection of roof equipment; But easy to cause cloth bag adhesion, sometimes forced to release waste gas, both waste and pollution. We successfully use nitrogen atomizing nozzle to solve this contradiction, which can achieve dry cooling, blast furnace gas does not need to be released when pumping water, but can still enter the cloth bag. This system had better be set in furnace top, can have double function. Some blast furnaces are placed in gravity dust removers for the sole purpose of protecting cloth bags. After nitrogen atomization nozzle is adopted, metal tube heat exchanger can be no longer used for switching, reducing maintenance and TRT power generation efficiency.

Use cloth bag dust collector, exit gas temperature of 200 degrees, if you need to enter the gas tank must be cooled to 50 degrees in order to protect the gas tank sealing material. Saturated cooling tower or indirect water cooled heat exchanger is often used for cooling, and there are many problems such as large cooling water volume and scaling of heat exchanger. We have successfully adopted partial evaporation cooling technology of nitrogen atomization nozzle in the gas pipeline, and achieved remarkable results. The actual comparison of a domestic factory is shown in the table below.

In blast furnace smelting, chlorine element also exists in blast furnace gas due to the presence of chlorine element in charge. In dry dust removal, with the decrease of gas temperature, water in the gas will be condensed out, chloride ions will be condensed into acid water, the net gas pipeline, compensator, valve and other equipment has a serious threat: some plant system operating time is not long on the pipeline corrosion leakage; The cost of anti-corrosion pipeline is very high. Also corrosion after the step of the valve, stainless steel compensator, pipe blowout plate (aluminum plate) and other equipment; Scale is formed on the pipe, after scaling falls off, block pipe and brick of hot blast furnace grid again, because this must take measure to remove chloride ion. Dechlorination ion commonly used dilution method, that is, a large amount of water to the gas, the use of water absorption chloride ion, reduce the corrosion of equipment. Spray water cycle use a certain concentration after replacement. This method is simple, reliable, equipment investment and operating costs, maintenance volume is high; In particular, it can offset the effect of dry dust removal to improve power generation and water saving. We have designed the method of spraying alkali solution to remove chloride ions, that is, spraying alkali solution with nitrogen atomization gun to achieve evaporation cooling, which plays the role of cooling and removing chloride ions at the same time. Alkaline wastewater can also be used to treat waste with waste and reduce equipment investment and operating costs.

We still have a considerable part, especially large blast furnaces are still using two wen, or steam jet tower wet dust removal, large amount of water and water treatment, high system resistance caused by energy and operating costs and waste. By adopting our semi-dry cooling technology of partial evaporation and assisting in the improvement of nozzle type, layout and water supply system, 30-50% water volume can be reduced, nozzle blockage can be completely solved and system resistance can be reduced. The main technical measure is to use the double outlet nozzle of up and down spray; Large orifice carbide nozzle is adopted; Small circulation water supply in series is adopted.

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