CN101788233B - Heating-furnace cogeneration system and method thereof - Google Patents

Abstract

A heating furnace waste heat power generation system and method thereof, belonging to the field of waste energy and waste heat recovery and utilization, the system includes a heating furnace, a heating furnace waste heat boiler, a heating furnace air preheater, a heating furnace heat pipe type gas preheater, and a heating furnace tail suction fan , superheated steam boiler, steam turbine generator set, chemical water system; at the tail of the heating furnace, arrange the waste heat boiler of the heating furnace, the air preheater of the heating furnace, the heat pipe type gas preheater of the heating furnace, and the exhaust suction of the heating furnace The fan recovers the waste heat of the flue gas of the heating furnace; the waste heat boiler of the heating furnace generates power; the waste heat boiler of the chemical water system heating furnace and the superheated steam boiler provide supplementary water. The advantage is that the superheated steam boiler can still ensure the low-load stable operation of the waste heat power generation system when the heating furnace is waiting for rolling, and the steam parameters of the waste heat power generation equipment of the heating furnace are improved by using the superheated steam boiler, and the power generation efficiency is improved; The waste heat of the furnace is recovered to the greatest extent, which has good economic and environmental benefits, and has good application and promotion value.

Description

A heating furnace waste heat power generation system and method thereof

technical field

The invention belongs to the field of recovery and utilization of waste energy and waste heat, and in particular relates to a heating furnace waste heat power generation system and a method thereof, which are suitable for power generation by waste heat of a steel rolling heating furnace in a steel plant.

Background technique

As a major energy consumer, steel rolling heating furnaces in iron and steel enterprises directly affect the production costs of enterprises. Generally, as a heating equipment, the thermal efficiency of a heating furnace is generally about 30%, and the energy consumption is high and the energy utilization level is low, resulting in a large amount of energy waste. Therefore, recovering the waste heat of the heating furnace has both good economic benefits and certain environmental benefits.

At present, most iron and steel enterprises use vaporization cooling walking beam heating furnace, the general fuel is mixed gas, and the smoke exhaust method is natural smoke exhaust. The exhaust gas temperature in the preheating section of the heating furnace is generally 850-900°C, and a cooling fan is usually used to reduce the exhaust gas temperature to protect the air preheater and gas preheater. In the case of putting the cooling fan into operation, the exhaust gas temperature at the tail of the heating furnace is still above 400°C. At present, the waste heat recovery method is mainly to use the exhaust smoke of the heating furnace to preheat the air and gas in the tail flue, or arrange the waste heat boiler in the tail flue to generate steam and directly generate electricity. These waste heat recovery methods have some problems in the actual operation process: (1) Air preheating and gas preheating only recover part of the flue gas heat, and the recovery of waste heat is limited. (2) Using waste heat recovery steam to directly generate electricity, because the parameters of the steam generated by the waste heat boiler are low, the efficiency of direct power generation is low. (3) Since the heating furnace is often waiting for rolling, the steam generated by the waste heat boiler is not continuous, and the waste heat power generation system cannot operate stably.

In view of the above defects, the waste heat recovery method of the heating furnace should be improved. The core problem is to use the recovered waste heat as efficiently as possible, and at the same time solve the contradiction between the heating furnace waiting for rolling and the continuous operation of the heating furnace waste heat power generation system.

Contents of the invention

The purpose of the present invention is to provide a heating furnace waste heat power generation system and its method. Firstly, through the configuration of the superheated steam boiler combustion system, the superheated steam boiler can still ensure the low load and stable operation of the waste heat power generation system when the heating furnace is waiting to be rolled. It solves the problem that the waste heat power generation system cannot run continuously due to the discontinuous production of the heating furnace when it is waiting for rolling; secondly, the steam parameters of the waste heat power generation equipment of the heating furnace are improved by using the superheated steam boiler, and the power generation efficiency is improved; finally, the waste heat of the heating furnace is improved by the present invention. The maximum recovery has good economic and environmental benefits, and has good application and promotion value. Recover the waste heat of the flue gas of the heating furnace as much as possible; improve the efficiency of waste heat power generation as much as possible; solve the contradiction between the heating furnace waiting for rolling and the continuous operation of the heating furnace waste heat power generation system.

The system of the present invention includes a heating furnace, a heating furnace waste heat boiler, a heating furnace air preheater, a heating furnace heat pipe gas preheater, a heating furnace tail suction fan, a superheated steam boiler, a steam turbine generator set, a chemical water system, and the like. The invention arranges the waste heat boiler of the heating furnace, the air preheater of the heating furnace, the heat pipe type gas preheater of the heating furnace, and the suction fan at the tail of the heating furnace in sequence along the flue gas flow direction at the tail of the heating furnace to fully recover the waste heat of the flue gas of the heating furnace. The saturated steam produced by the waste heat boiler of the heating furnace enters the superheated steam boiler to further increase the temperature and then enters the turbogenerator unit for power generation. The chemical water system mainly provides supplementary water for the waste heat boiler of the heating furnace and the superheated steam boiler.

The chemical water system of the present invention mainly treats the raw water, reduces the hardness and salt content of the water, and provides chemical supplementary water for the waste heat boiler of the heating furnace and the superheated steam boiler.

The technology of waste heat power generation of the present invention comprises the waste heat recovery process of heating furnace flue gas and the steam-water circulation process of steam turbine generator set; the specific process is as follows:

Heating furnace flue gas waste heat recovery process: the exhaust gas temperature in the preheating section of the heating furnace is 1000°C-850°C (depending on the feed temperature), and after the heat is recovered by the waste heat boiler of the heating furnace to generate saturated steam, the exhaust gas temperature is 650°C -550°C. After the flue gas passes through the air preheater of the heating furnace to preheat the air, the exhaust gas temperature is 300°C-250°C. After the flue gas passes through the gas preheater of the heating furnace to preheat the gas, the exhaust gas temperature drops to 150°C. The flue gas from the heating furnace is finally discharged into the chimney of the heating furnace through the tail suction fan of the heating furnace, and finally discharged into the atmosphere. In the present invention, the original mixed cooling fan does not need to operate.

The steam-water circulation process of the turbo-generator unit: the saturated steam generated by the waste heat boiler of the heating furnace is sent to the superheater inlet header of the superheated steam boiler, and the saturated steam is superheated to reach the rated parameters of the turbo-generator unit and then sent to the turbo-generator unit for power generation. The condensed water produced by the steam turbine generator set is sent to the low-pressure heater through the condensed water pump. The heat source of the low-pressure heater is provided by the saturated steam generated by the vaporization cooling drum of the water beam of the heating furnace. The heated condensed water enters the high-pressure deaerator after deaeration , sent to the high-pressure heater by the feed water pump. The high-pressure feed water is sent to the superheated steam boiler and the waste heat boiler of the heating furnace respectively for steam-water circulation. After the drainage of the low-pressure heater flows into the low-level water tank, it is sent to the low-pressure deaerator by the drainage pump, and then enters the heating furnace water beam vaporization cooling circulation system. The saturated steam produced by the vaporization cooling of the water beam of the heating furnace is no longer directly supplied to the pipe network in the plant area, but is supplied by the regulated extraction steam of the turbogenerator unit.

Main innovation of the present invention is:

(1) Use the adjustment of the evaporation capacity of the superheated steam boiler to solve the contradiction between the heating furnace waiting for rolling and the heating furnace waste heat power generation system needing continuous operation.

(2) Improve the steam parameters of the power generation system through the superheated steam boiler, and improve the power generation efficiency of waste heat recovery steam.

(3) The exhaust gas temperature of the heating furnace is reduced to 150°C, and the waste heat recovery of the heating furnace reaches the limit level.

The positive effects of the present invention are as follows:

(1) The waste heat boiler of the heating furnace and the steam produced by the superheated steam boiler are mixed and superheated to ensure the stable operation of the power generation system. When the heating furnace is waiting for rolling, the steam production of the waste heat boiler of the heating furnace decreases. The superheated steam boiler produces part of the steam as a supplement, which ensures the stability of the steam required by the power generation system. This solves the contradiction between the heating furnace waiting for rolling and the heating furnace waste heat power generation system needing continuous operation.

(2) The saturated steam generated by the waste heat boiler of the heating furnace is passed through the superheated steam boiler to improve the steam parameters and improve the efficiency of waste heat power generation. The saturated steam produced by the waste heat boiler of the heating furnace and the saturated steam produced by the superheated steam boiler are mixed in the superheater inlet header of the superheated steam boiler, and sent to the superheated steam boiler for superheating. After reaching the required parameters of the unit, it enters the power generation system for power generation.

(3) The superheated steam boiler adopts a moving flame center combustion system to ensure the stable operation of the superheated steam boiler under low load. The flame center of the superheated steam boiler can move up and down with the change of working conditions. When the heating furnace is running normally, the center of the flame moves up, and the evaporation of the boiler decreases; when the heating furnace is waiting for rolling, the center of the flame moves down, and the evaporation of the boiler increases. This ensures the stable operation of the steam turbine generator set.

(4) Cascade utilizes the waste heat of the flue gas of the heating furnace, and arranges waste heat boilers, air preheaters, and gas preheaters in sequence according to different temperature requirements, and the exhaust gas temperature is reduced to 150°C, so that the waste heat recovery reaches the limit.

(5) Use the steam produced by the heating furnace to vaporize and cool the walking beam instead of extracting steam from the original low-pressure heater, and further efficiently utilize the waste heat of the heating furnace to improve power generation efficiency.

Main technical advantages of the present invention: (1) The stable operation of the waste heat power generation system is ensured by using the superheated steam boiler. (2) Through the superheated steam boiler, the parameters of waste heat recovery steam are improved, and the power generation efficiency is improved. In addition, the invention does not make major changes to the heating furnace, does not affect the original performance of the heating furnace, and has a short investment recovery period and quick results.

The invention significantly improves the existing waste heat power generation process of the heating furnace, and has good application and popularization value.

Description of drawings

Fig. 1 is a schematic diagram of the heating furnace waste heat recovery power generation equipment system of the present invention. Among them, heating furnace 1, heating furnace waste heat boiler 2, heating furnace air preheater 3, heating furnace gas preheater 4, heating furnace tail suction fan 5, heating furnace blower 6, steam turbine generator set 7, condensate water pump 8, Low pressure heater 9, high pressure deaerator 10, feed water pump 11, high pressure heater 12, superheated steam boiler 13, low drain tank 14, drain pump 15, low pressure deaerator 16, vaporization cooling drum 17, water beam cooling cycle Pump 18, mixed cooling fan 19, heating furnace chimney 20.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

The system of the present invention includes a heating furnace 1, a heating furnace waste heat boiler 2, a heating furnace air preheater 3, a heating furnace heat pipe type gas preheater 4, a heating furnace tail suction fan 5, a superheated steam boiler 13, and a steam turbine generator set 7 , chemical water system, etc. In the present invention, the waste heat boiler 2 of the heating furnace, the air preheater 3 of the heating furnace, the heat pipe type gas preheater 4 of the heating furnace, and the suction fan 5 at the tail of the heating furnace are sequentially arranged at the tail of the heating furnace 1 along the flow direction of the flue gas to fully recover the fume from the heating furnace. Air waste heat. The saturated steam generated by the waste heat boiler 2 of the heating furnace enters the superheated steam boiler 13 to further raise the temperature, and then enters the turbogenerator unit 7 for power generation. The chemical water system mainly provides supplementary water for the waste heat boiler of the heating furnace and the superheated steam boiler.

Referring to accompanying drawing 1, it is a schematic diagram of the waste heat recovery power generation equipment system of the heating furnace of the present invention. Heating furnace flue gas waste heat recovery process: The exhaust gas temperature in the preheating section of heating furnace 1 is 1000°C-850°C (depending on the temperature of the feed material). It is 650°C-550°C. After the flue gas passes through the heating furnace air preheater 3 to preheat the air, the exhaust gas temperature is about 300°C-250°C. After the flue gas passes through the heating furnace gas preheater 4 to preheat the gas, the exhaust gas temperature drops to about 150°C. The flue gas of the heating furnace is finally discharged into the chimney 20 of the heating furnace through the tail suction fan 5 of the heating furnace, and finally discharged into the atmosphere. In the present invention, the original mixed cooling air blower 19 does not have to operate. The steam-water circulation process of the steam turbine generator set: the saturated steam generated by the waste heat boiler 2 of the heating furnace is sent to the superheater inlet header of the superheated steam boiler 13, and the saturated steam is sent to the steam turbine generator set 7 after overheating to reach the rated parameters of the steam turbine generator set To generate electricity. The condensed water produced by the steam turbine generator unit 7 is sent to the low-pressure heater 9 through the condensed water pump 8, and the heat source of the low-pressure heater 9 is provided by the saturated steam generated by the vaporization cooling drum 17 of the heating furnace water beam, and the heated condensed water enters the high-pressure removal After deoxygenation by the oxygen tank 10, it is sent to the high-pressure heater 12 by the feed water pump 11. The high-pressure feed water is respectively sent to the superheated steam boiler 13 and the waste heat boiler 2 of the heating furnace for steam-water circulation. After the drainage of the low-pressure heater 9 flows into the low-level water tank 14, it is sent to the low-pressure deaerator 16 by the drainage pump 15, and enters the heating furnace water beam vaporization cooling circulation system. The saturated steam produced by the vaporization cooling of the water beam of the heating furnace is no longer directly supplied to the pipe network in the plant area, but is supplied by the regulated extraction steam of the turbogenerator unit 7 .

The invention can flexibly adapt to various operating conditions of the heating furnace without affecting the original production conditions of the heating furnace. The operating parameters of the waste heat boiler of the heating furnace are improved, and the efficiency of waste heat power generation is improved. In summary, the present invention has good economic benefits and good application and popularization value.

Claims (3)

1. A heating furnace waste heat power generation system, including a heating furnace, a heating furnace waste heat boiler, a heating furnace air preheater, a heating furnace heat pipe type gas preheater, a heating furnace tail suction fan, a superheated steam boiler, a steam turbine generator set, Chemical water system; it is characterized in that, at the tail of the heating furnace (1), the waste heat boiler (2), the air preheater of the heating furnace (3), the heat pipe type gas preheater of the heating furnace (4 ), the exhaust fan (5) at the tail of the heating furnace recovers the waste heat of the flue gas of the heating furnace; the saturated steam generated by the waste heat boiler of the heating furnace enters the superheated steam boiler to further increase the temperature and then enters the turbogenerator unit for power generation; the chemical water system is the waste heat boiler of the heating furnace and superheated steam boiler to provide make-up water. 2. The system according to claim 1, characterized in that the chemical water system treats the raw water to reduce the hardness and salt content of the water. 3. A method for waste heat power generation using the system according to claim 1, characterized in that the process of waste heat power generation comprises a heating furnace flue gas waste heat recovery process and a steam-water circulation process of a steam turbine generator set; Heating furnace flue gas waste heat recovery process: the exhaust gas temperature in the preheating section of the heating furnace (1) is 1000°C-850°C, and after the heat is recovered by the heating furnace waste heat boiler (2) to generate saturated steam, the exhaust gas temperature is 650°C-550°C; After the flue gas passes through the heating furnace air preheater (3) to preheat the air, the exhaust gas temperature is 300°C-250°C; after the flue gas passes through the heating furnace gas preheater (4) to preheat the gas, the exhaust gas temperature drops to 150°C ℃; the heating furnace flue gas is finally discharged into the heating furnace chimney (20) through the heating furnace tail suction fan (5), and finally discharged into the atmosphere; The steam-water circulation process of the steam turbine generator set: the saturated steam generated by the waste heat boiler (2) of the heating furnace is sent to the inlet header of the superheater of the superheated steam boiler (13), and the saturated steam is sent to the steam turbine generator set after superheating to reach the rated parameters. The turbine generator set (7) generates electricity; the condensed water produced by the turbogenerator set (7) is sent to the low-pressure heater (9) through the condensate pump (8), and the heat source of the low-pressure heater (9) is vaporized and cooled by the water beam of the heating furnace The saturated steam generated by the steam drum (17) is provided, and the heated condensed water enters the high-pressure deaerator (10) to remove oxygen, and then is sent to the high-pressure heater (12) by the feed water pump (11); the high-pressure feed water is respectively sent to the superheated The steam boiler (13) and the waste heat boiler (2) of the heating furnace carry out the steam-water circulation; the drainage of the low-pressure heater (9) flows into the low-level water tank (14), and is sent to the low-pressure deaerator (16) by the drainage pump (15), Enter the water beam vaporization cooling circulation system of the heating furnace; the saturated steam produced by the water beam vaporization cooling of the heating furnace is no longer directly supplied to the pipe network of the plant area, but is supplied by the regulated extraction steam of the steam turbine generator set.

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