Flue suction and thermal carrier temperature control method in coke oven waste heat recovery

Abstract

The invention relates to a method for controlling flue suction and thermal carrier temperature in waste gas recovery. The method comprises: by taking total flue waste gas suctions P1 and P2 of coke ovens as controlled parameters, sending PID adjusting instructions to a 1# coke oven flue suction pipe electric adjusting valve, a 2# coke oven flue suction pipe electric adjusting valve or a frequency converter of a waste gas induced draft fan by detecting P1 and P2 actual suctions and input set suction through comparison with PLC to realize stable control of P1 and P2 suctions; and controlling the P1 and P2 separately by adopting different control strategies when the T4 actual temperature is less than the standard temperature T or the T4 actual temperature is greater than or equal to the standard temperature T. The method has the advantages that the flue suction stability is greatly improved; when the thermal carrier temperature T4 is less than T, the flue suction is stable and the temperature can be quickly raised to satisfy the user demand, and meanwhile, the total recovery of flue waste gas waste heat is increased. When T4 is greater than or equal to T, T4 is increased or decreased at a temperature difference of deltaT4=+ / -2 DEG C, so that the problem of radical change of temperature can be effectively prevented.

Description

technical field [0001] The invention relates to the technical field of coke oven thermal control and exhaust gas waste heat utilization in the coking industry, in particular to a method for controlling flue suction and heat carrier temperature in waste gas waste heat recovery. Background technique [0002] In the coking industry, coke oven flue gas waste heat recovery potential is great (taking 2×55 holes JN60-6 coke oven as an example, after heat exchange, the flue gas temperature will be reduced to 105°C at least, and the energy saving will be 14674t(ce) / a) , high availability (for example, flue gas is reduced from 230°C to 105°C, the sensible heat is recovered, which is very easy to realize in engineering; the heat recovery method is to directly use the waste heat of the exhaust gas to adjust the humidity of the coking coal, and the second is to heat the heat carrier Such as low-pressure steam or high-temperature hot water, heat transfer oil and other secondary energy med...

AI Technical Summary

Problems solved by technology

[0006] (1) The suction of the flue is controlled by the exhaust gas suction main pipe of the flue, which is caused by 1 # ,2 # The total flue competes for suction and the distribution is uneven and unstable; the stability rate of the set value of P1 and P2 ± 30Pa is only 75% to 80%.

[0007] (2) The exhaust gas temperature of the coke oven flue and the total supply of waste heat are relatively stable, but the heat demand of the heat utilization system is not stable due to various factors. In order to achieve the heat balance between the two, it is necessary to maintain the flue Suction, so in addition to adjusting K5, K6 or the frequency of the induced draft fan, it is also necessary to frequently adjust the total flue damper K1, K2, because there is a lag in the adjustment response, which aggravates the fluctuation of the total flue suction; in addition, the total flue damper weighs Several tons, K1, K2 electric actuators are prone to fatigue damage due to long-term frequent work

[0008] (3) Secondary heat carriers such as steam / high-temperature hot water and heat-conducting oil require high temperature stability (take high-temperature hot water as an example, the process generally requires T4=140±10°C), simply use T4 temperature and P3 Suction cascade control, on the one hand, there is often a trade-off between P3 and T4 (for example, in order to improve T4, it is necessary to increase the air volume of the induced draft fan to increase the recovery of exhaust gas waste heat, the suction of the coke oven flue increases synchronously and cannot be stabilized; To reduce T4, it is necessary to reduce the air volume of the induced draft fan to reduce the recovery of waste gas waste heat, and the suction of the coke oven flue will decrease synchronously and cannot be stabilized); Users (such as indirect heating coal humidity control system need for heat carrier stability

[0009] (4) The waste heat recovery of coke oven flue gas is limited

In this way, part of the high-temperature exhaust gas must be discharged directly through the chimney without passing through the heat exchanger and induced draft fan, so that the waste heat recovery cannot be maximized.

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