Method for preventing flue leakage of exhaust-heat boiler of converter

Abstract

The invention discloses a method for preventing flue leakage of an exhaust-heat boiler of a converter. When the pressure of a steam drum of the exhaust-heat boiler of the converter is no less than 1.8 MPa, a blow-off valve of the steam drum is opened by 20%; when the pressure of the steam drum is no less than 1.9 MPa and no more than 2.1 MPa, the blow-off valve of the steam drum is opened by 70%; and when the pressure of the steam drum is more than 2.1 MPa, the blow-off valve of the steam drum is opened by 100%. According to the invention, the openness of the blow-off valve is controlled in segments according to the pressure of the steam drum, so the pressure of water current in the flue of the exhaust-heat boiler is stabilized; the pressure of cooling water is stabilized at 1.5 to 1.9 MPa, and the flow velocity of water in closely pitched tubes of the flue reaches 1.3 to 1.5 m/s; so water cooling intensity of the exhaust-heat boiler of the converter to the flue is improved, forced shutdown and overhauling of the converter caused by tube explosion and leakage of the flue are effectively reduced, and the smelting efficiency of the converter is improved. The method provided by the invention has the characteristics of simpleness, substantial leakproof effect on the flue, conservation of considerable soft water resources and prolongation of the service life of the flue.

Description

technical field [0001] The invention belongs to the technical field of converter smelting, and in particular relates to a method for preventing the flue leakage of a converter waste heat boiler with simple method, remarkable flue leakage prevention effect, prolonging the service life of the flue, and saving soft water resources. Background technique [0002] Oxygen converter steelmaking is the dominant steelmaking method today. In the process of converter steelmaking, flue gas containing a large amount of CO and iron powder will be generated above 1000 degrees. In order to recover converter gas and avoid direct emission of dust to pollute the environment, converters are generally used The waste heat boiler recovers the waste heat in the flue gas to lower its temperature and then perform purification treatment so that the recovered gas can be used to reduce costs and reduce environmental pollution. The flue in the converter waste heat boiler is an important part of it. Howeve...

AI Technical Summary

Problems solved by technology

Since the flue of the converter waste heat boiler is restricted by many complicated factors, water leakage in the flue is the most common and difficult problem in the maintenance of the flue, which seriously affects the service life of the flue and not only wastes a lot of soft water resources, and it will also cause the shutdown or production reduction of the converter. Severe water leakage will also cause the following problems: the steam generated increases the air volume of the flue, which may cause flue gas to overflow and cause pollution; affect the gas yield and the flue Utilization of waste heat; threat to safe production

However, due to the intermittent smelting mode of the converter, the amount of flue gas increases sharply during the blowing peak period, and the heating of the inner wall of the flue causes the local pressure of the cooling circulating water to rise too fast, and the instantaneous expansion pressure is greater than the circulating pressure, resulting in local stagnation; In addition, changes in the amount of oxygen blowing during oxygen blowing will also cause changes in flue gas volume and flue gas temperature, which will also cause fluctuations in circulating cooling water pressure; when the blowing is stopped, the total amount of flue gas will drop to zero, and the heat load will decrease. The temperature of the pipe wall will drop sharply, and the circulating cooling water pressure will drop accordingly.

Therefore, simply increasing the circulating water pressure will cause water pressure shock due to oxygen blowing in smelting, which will cause periodic thermal alternating stress on the heat pipe, which will easily cause thermal fatigue leakage and even pipe burst

[0004] Therefore, in order to ensure safety in actual production, if the leakage caused by high pressure is not completely solved, steam can only be released to make the system operate under low pressure.

However, low-pressure operation will lead to low flow rate of the close-packed tubes of the converter waste heat boiler, resulting in low water cooling strength of the heat exchange surface of the flue, not only incomplete separation of steam and water, large amount of water in the steam released by the converter waste heat boiler, and high operating costs of the process; it will also cause cooling smoke. The temperature of the pipe wall exceeds 400°C, while the actual temperature inside the close-packed pipe is about 250°C, resulting in a large temperature difference between the inner and outer walls of the close-packed pipe, resulting in a large difference in thermal expansion at the micro level; and the bubbles formed on the inner pipe wall cannot be taken away in time , causing the bubbles to grow up before they float up. When the bubbles are attached, the pipe wall is dry-burned. Leakage occurs due to damage, which not only reduces production efficiency and increases safety hazards, but also increases labor intensity in the repair of the flue, which leads to an increase in production costs

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