Process air circulating system of belt type roasting machine

Abstract

The invention discloses a process air circulating system of a belt type roasting machine. The process air circulating system comprises a main induced draft fan used for outputting to-be-desulfurized and to-be-denitrated flue gas. The main induced draft fan comprises a heat exchanger. The heat exchanger comprises a heat release portion, a heat absorption portion arranged in a front flue of the maininduced draft fan, a cold medium input pipe connected to an outlet of the heat release portion and an inlet of the heat absorption portion and a hot medium input pipe connected to an outlet of the heat absorption portion and an inlet of the heat release portion. A main temperature sensor used for detecting temperature of flue gas is arranged in a rear flue of the main induced draft fan. The process air circulating system further comprises a controller connected to the heat exchanger and the main temperature sensor. When the temperature of flue gas in the rear flue is larger than first presettemperature, the controller controls the heat exchanger to improve the circulating quantity of a heat exchange medium and / or reduce the temperature of the heat exchange medium. The heat exchanger is arranged in the front flue of the main induced draft fan, the flue gas oxygen content of the belt type roasting machine is not increased, meanwhile, the cooling effect of flue gas is guaranteed, loadsof a subsequent flue gas disposal system can be reduced, and the production cost can be reduced.

Description

technical field [0001] The invention relates to the technical field of desulfurization and denitrification, and more specifically relates to a process air circulation system of a belt roaster. Background technique [0002] In the "Opinions on Promoting the Implementation of Ultra-Low Emissions in the Iron and Steel Industry" document issued by the state in 2019, it is stipulated that the benchmark oxygen content for the flue gas of the grate rotary kiln and the belt roaster to reach the target is 18%. [0003] The air system of the belt roaster is a relatively complex sealed circulation system. The flue gas drawn by the main induced draft fan has high content of particulate matter, sulfur dioxide and nitrogen oxides, and needs to be further purified before it can be discharged into the atmosphere. The air temperature is usually 100-180°C, and may exceed 200°C under extreme conditions. In order to ensure the normal operation of the process equipment during design, it is neces...

AI Technical Summary

Problems solved by technology

The oxygen content of desulfurization and denitrification flue gas after temperature adjustment increases by 0.6 to 1.5 percentage points, and the higher the flue temperature that needs to be reduced, the higher the oxygen content increases, resulting in the oxygen content of the flue gas exceeding the benchmark oxygen content stipulated by environmental protection, and also increasing Increased the load of subsequent flue gas dust removal, desulfurization and denitrification systems, and increased operation and equipment maintenance costs

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