Device and process for utilizing waste heat of waste flue gas of hot-blast stove

Abstract

The invention relates to a device and process for utilizing waste heat of waste flue gas of a hot-blast stove. The process is characterized by comprising the steps that during normal operation, the waste flue gas sequentially enters secondary heat exchangers and primary heat exchangers through flue gas pipelines, and gas passing through the heat exchangers is preheated; when the temperature of the flue gas is higher than a design value, the amount of the flue gas entering the heat exchangers is controlled by adjusting regulating valves of the flue gas pipelines and inlets of the heat exchangers; and when the temperature of the flue gas is lower than the design value, the procedure includes the following steps that a, the valves arranged on the flue gas pipelines at the front ends of the heat exchangers are adjusted, and the amount of the flue gas entering the secondary heat exchangers is controlled; b, valves on bypass pipelines of the primary heat exchangers are opened, and the flue gas passing through the secondary heat exchangers are made to directly enter the flue gas pipelines at the rear ends of the primary heat exchangers by bypassing the primary heat exchangers; and c, the gas to be preheated sequentially enters the primary heat exchangers and the secondary heat exchangers and then enters bypass channels enabling outlets of the secondary heat exchangers and the inlets of the primary heat exchangers to be communicated, and therefore the temperature of the gas at the inlets of the primary heat exchangers is increased.

Description

technical field [0001] The invention belongs to the technical field of waste heat utilization of metallurgical hot blast stove exhaust gas, and in particular relates to a hot blast stove waste flue gas waste heat utilization equipment and process. Background technique [0002] At present, for the utilization of waste flue gas from hot blast stoves, the relatively common method adopted is to use heat pipe heat exchangers, tube heat exchangers, plate heat exchangers, and rotary heat exchangers to recover waste heat. The process of the furnace is to alternately supply air to the furnace, so the demand for preheating and the supply of waste heat will change repeatedly at regular intervals. One hot blast furnace is supplying air, and the other two or three furnaces are firing, and vice versa. , the exhaust gas produced in this way will have periodic changes in both temperature and quantity, which requires relatively high equipment and needs to adapt to changes in temperature and ...

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Problems solved by technology

[0002] At present, for the utilization of waste flue gas from hot blast stoves, the relatively common method adopted is to use heat pipe heat exchangers, tube heat exchangers, plate heat exchangers, and rotary heat exchangers to recover waste heat. The process of the furnace is to alternately supply air to the furnace, so the demand for preheating and the supply of waste heat will change repeatedly at regular intervals. One hot blast furnace is supplying air, and the other two or three furnaces are firing, and vice versa. , the exhaust gas produced in this way will have periodic changes in both temperature and quantity, which requires relatively high equipment and needs to adapt to changes in temperature and flow. Traditional heat pipe heat exchangers are usually integral heat exchangers , using the heat pipe as the heat transfer element, the area of ​​the heat exchanger is designed according to the design conditions. Under the condition of low temperature or small flow, the temperature of the end tube wall of the heat exchanger is lower than the dew point corrosion due to the non-adjustable heat exchange area. temperature, thus causing damage to the equipment; the tubular heat exchanger performs heat exchange in the way that the flue gas goes through the tube side, and the cold side medium goes through the shell side. The heat area cannot be adjusted, and corrosion at the tail of the heat exchanger is also inevitable under low temperature and small flow conditions; the plate heat exchanger is made of multi-layer corrugated heat transfer plates by welding or rubber gaskets at certain intervals. High-efficiency heat exchange equipment composed of compression, hot and cold fluids convect each other on both sides of the thin-walled heat transfer plate for heat exchange, the disadvantage is that the sealing is poor, easy to leak, and the operating pressure is limited to a certain extent, generally not exceeding 1MPa , the operating temperature is limited by the temperature resistance of the gasket material, the heat transfer area is also not adjustable, and it is easy to cause low temperature dew point corrosion problems; the structure of the rotary air preheater is: flue gas and air pass through the heating surface alternately, and the heat is transferred The heat is transferred to the heating surface, the heat is absorbed by the heating surface, and then the air passes through the heating surface, and the heat is transferred to the air from the heating surface. Affected by the structure of the device itself, the air leakage of the rotary air preheater is serious, which is 8-10% in normal operation. The defect can reach 20-30%. At the same time, the non-adjustable heat exchange area will also cause low temperature dew point corrosion

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