CN111895799A - A multi-pollutant collaborative treatment system for heating furnace exhaust gas - Google Patents

Abstract

The invention discloses a multi-pollutant cooperative treatment system for heating furnace exhaust gas. Including a soot purification system and an air and smoke purification system, the soot purification system and the air and smoke purification system respectively include an SCR denitration reactor, a desulfurization reaction tower, and a bag filter; the SCR denitration reactor in the soot purification system The front end of the flue gas inlet is connected to the soot primary heat exchanger and the soot secondary heat exchanger through pipes, and the soot secondary heat exchanger is connected to the air-heated furnace; the SCR denitration reactor in the air and smoke purification system The front end of the flue gas inlet is connected to the air-smoke primary heat exchanger and the air mixing device through a pipeline, and the air mixing device is connected to the soot secondary heat exchanger. This system can effectively realize the synchronous operation of heating furnace exhaust gas purification, waste heat recovery and joint temperature rise; the system has high purification efficiency, and can effectively remove sulfur dioxide, nitrogen oxides and particulate matter in the exhaust gas at the same time, which can fully meet the emission limit requirements of the new standard or Ultra-low emission targets.

Description

A multi-pollutant collaborative treatment system for heating furnace exhaust gas

technical field

The invention belongs to the technical field of industrial flue gas pollution prevention and control, and relates to a multi-pollutant coordinated treatment system for heating furnace waste gas, in particular to a steel rolling heating furnace waste gas purification system.

Background technique

The heating furnace is a reprocessing equipment that heats materials or workpieces, and is also a device that heats materials or workpieces.

The waste gas produced by the combustion of the heating furnace gas mainly includes SO2, NOx, soot, etc. The pollutants are continuously discharged from the organized elevated point source, and the pollution to the atmospheric environment caused by the large amount of waste gas emissions cannot be ignored.

In April 2019, the Ministry of Ecology and Environment, the National Development and Reform Commission and other departments jointly issued the "Opinions on Promoting the Implementation of Ultra-Low Emissions in the Iron and Steel Industry", which requires the emission indicators of flue gas pollutants generated by heating furnaces: at the benchmark oxygen content of 8%, particulate matter, sulfur dioxide, The hourly mean emission concentration of nitrogen oxides shall not be higher than 10, 50 and 200 mg/m3 respectively.

As mentioned above, the temperature of the flue gas produced by the steel rolling heating furnace is 80-110 °C, the concentration of particulate matter is less than 100 mg/m ³ , the concentration of SO ₂ is greater than 300 mg/m ³ and the concentration of NOx is greater than 500 mg/m ³ . The flue gas of the heating furnace passes through the soot. The chimney and the empty chimney are discharged separately, in which the soot contains CO explosive gas.

Literature review shows that the current domestic heating furnace NOx adopts circulating flue gas low-nitrogen combustion technology, but NOx still cannot meet the national environmental protection emission requirements, and lacks the treatment technology for particulate matter and sulfur dioxide.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a multi-pollutant cooperative treatment system for heating furnace exhaust gas, and propose a joint heating method according to the characteristics of the flue gas of the steel rolling heating furnace, that is, the soot side flue gas is heated first, and the heated soot side smoke is used at the same time. The hot air of the air is mixed to heat up the flue gas on the air smoke side to meet the requirements of new environmental protection standards or ultra-low emission requirements.

The technical solution of the present invention is: a multi-pollutant collaborative treatment system for heating furnace exhaust gas, including a soot purification system and an air and smoke purification system, and the air and smoke purification system respectively includes an SCR denitration reactor, a desulfurization reaction tower, and a bag filter. ; The front end of the flue gas inlet of the SCR denitration reactor in the soot purification system is connected to a soot primary heat exchanger and a soot secondary heat exchanger through a pipeline, and the soot secondary heat exchanger is connected to an air-heated furnace ; The front end of the flue gas inlet of the SCR denitration reactor in the air and smoke purification system is connected to the air and smoke primary heat exchanger and the air mixing device through a pipeline, and the air mixing device is connected to the soot secondary heat exchanger; the The hot blast stove is mainly to heat up the soot and air smoke to meet the SCR denitration temperature; the high temperature air generated by the hot blast stove first heats the soot indirectly, and then directly mixes with the air smoke in the mixing device to heat up; Smoke purification system and air smoke purification system, the two sets of purification systems run at the same time without interfering with each other to ensure safety.

According to the embodiment of the present invention, the net flue gas outlet of the bag filter is connected to an induced draft fan and a chimney; the induced draft fan provides power for the exhaust gas purification system, and the fan control can be conventional control or frequency conversion control as required.

According to an embodiment of the present invention, the SCR denitration reactor includes a catalytic reactor, an ammonia injection grid, and a static mixer, and the SCR denitration reactor is used for removing _NOx in the exhaust gas.

According to the embodiment of the present invention, the bag filter is a straight-through bag filter, a pre-charged bag filter or an electric bag compound bag filter; the bag filter is mainly composed of a filter bag cage, an injection bag filter It is composed of a device, a box, an ash hopper, etc., which are used to efficiently remove particulate matter, ensure low-concentration emission of particulate matter, and meet environmental protection requirements.

According to the embodiment of the present invention, the soot primary heat exchanger, the soot secondary heat exchanger, and the air-smoke primary heat exchanger are gas-gas indirect heat exchangers, and the heat exchangers are of plate type, heat pipe or column-and-tube type. The heat exchanger has the function of waste heat recovery.

The desulfurization reaction tower is to spray desulfurization agent in the reaction tower to remove SO ₂ efficiently, to ensure low concentration of sulfur dioxide emission, and to meet environmental protection requirements; different dry or semi-dry desulfurization processes can be used according to different working conditions. (including but not limited to calcium method, sodium-alkali method, etc.).

The technical route of the invention is: due to the characteristics of the flue gas of the heating furnace, a soot purification system and an air smoke purification system are used, and each system adopts SCR denitration + dry (or semi-dry) desulfurization to remove nitrogen oxides, Efficient removal of sulfur dioxide and particulate matter, purifying exhaust gas and discharging up to standard; using heat exchanger for cooling and heat energy recovery and utilization; using joint heating for soot and air smoke, that is, the high-temperature air generated by the hot blast stove first heats the soot indirectly , and then directly mixed with air smoke to heat up.

The remarkable feature of the system of the present invention is that it includes three circuits of exhaust gas purification, waste heat recovery and combined temperature rise.

The purification system of the invention is as follows: the combustion exhaust gas of the heating furnace is divided into soot and air smoke. Because the soot contains CO explosive gas, the soot and the air smoke are each provided with a set of purification systems, namely the soot purification system and the air smoke purification system.

Soot purification system: the soot first enters the primary heat exchanger and the secondary heat exchanger, and the flue gas first enters the SCR denitrification device to remove _NOx in the exhaust gas, and then undergoes dry (or semi-dry) desulfurization. SO ₂ is removed, and then the particulate matter in the exhaust gas is removed by the bag filter, and the clean flue gas is discharged into the chimney at high altitude by the induced draft fan.

Air and smoke purification system: the air smoke first enters the primary heat exchanger and mixes to heat up, and then enters the SCR denitration device to remove _NOx from the exhaust gas, and then dry (or semi _- dry) desulfurization for SO2 removal. Then, the particulate matter in the exhaust gas is removed by the bag filter, and the clean flue gas is discharged into the chimney at high altitude by the induced draft fan.

The purification system of the present invention is characterized in that: a combined heating process is adopted. Due to the characteristics of the flue gas of the heating furnace, the CO concentration in the flue gas on the soot side is about 30,000 ppm, and the highest can reach 70,000 ppm. Therefore, it is not possible to use hot air and flue gas to directly mix and heat, and only indirect heat exchange can be used. The flue gas is heated by the device; the hot air after heating the soot side flue gas is directly mixed with the air smoke side flue gas, so as to achieve the purpose of comprehensive utilization of thermal energy between soot and air smoke.

The beneficial effects of the invention are as follows: the system can effectively realize the simultaneous purifying, waste heat recovery and joint temperature rise of the heating furnace; the purification efficiency of the system is high, and the sulfur dioxide, nitrogen oxides and particulate matter in the exhaust gas can be effectively removed at the same time, so that the discharged SO ₂ concentration is lower than 30mg/m ³ , NO _x concentration is lower than 50mg/m ³ , and particulate matter is lower than 10mg/m ³ , which can fully meet the new standard emission limit requirements or ultra-low emission targets; the system has the advantages of waste heat utilization and energy saving Consumption reduction, low operating cost, safety and reliability and other notable features, through flue gas heat exchange, the exhaust gas temperature can be reduced to 130~150 ℃; this system adopts combined heating, which can effectively meet the SCR denitration temperature of soot and air smoke, and can ensure Safe and reliable operation of the soot purification system; the adopted SCR denitration method has the advantages of high denitration efficiency, low energy consumption, small land occupation and low operating cost; the adopted dry (or semi-dry) desulfurization method has high desulfurization efficiency High, no waste water, simple operation, low resistance, small footprint and other advantages.

Description of drawings

Figure 1 is a multi-pollutant collaborative treatment system for heating furnace exhaust gas.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings.

As shown in Figure 1, a multi-pollutant collaborative treatment system for heating furnace exhaust gas includes a soot purification system and an air and smoke purification system. The soot purification system and the air and smoke purification system respectively include an SCR denitration reactor, a desulfurization reaction tower, a bag The front end of the flue gas inlet of the SCR denitration reactor in the soot purification system is connected to the soot primary heat exchanger and the soot secondary heat exchanger through pipes, and the soot secondary heat exchanger is connected to An air-heated furnace; the front end of the flue gas inlet of the SCR denitration reactor in the air-smoke purification system is connected to the air-smoke primary heat exchanger and the air mixing device through a pipeline, and the air mixing device is connected to the soot secondary heat exchanger.

As shown in Figure 1, the soot purification system and the air smoke purification system, the two sets of purification systems run at the same time without interfering with each other to ensure safety.

The SCR denitration reactor includes a catalytic reactor, an ammonia injection grid, and a static mixer, and is used for removing _NOx in the exhaust gas.

The desulfurization reaction tower is to spray desulfurization agent in the reaction tower to remove SO ₂ efficiently, to ensure low concentration of sulfur dioxide emission, and to meet environmental protection requirements; different dry or semi-dry desulfurization processes can be used according to different working conditions. (including but not limited to calcium method, sodium-alkali method, etc.).

The bag filter is mainly composed of a filter bag cage, a blowing device, a box, an ash hopper, etc., which are used to efficiently remove particulate matter, ensure low-concentration emission of particulate matter, and meet environmental protection requirements; the bag filter includes: But not limited to straight-through bag filter, pre-charged bag filter, electric bag compound bag filter, etc.

The soot primary heat exchanger, soot secondary heat exchanger, and air-smoke primary heat exchanger are gas-gas indirect heat exchange, and the heat exchanger type adopts plate type, heat pipe or tube type; The function of waste heat recovery.

The induced draft fan provides power for the exhaust gas purification system, and the fan control can be conventional control or frequency conversion control as required.

The hot blast stove is mainly to heat up the soot and air smoke to meet the SCR denitration temperature; the high temperature air generated by the hot blast stove first heats the soot indirectly, and then directly mixes with the air smoke in the mixing device to heat up.

The above detailed description of the embodiments in conjunction with the accompanying drawings are only preferred embodiments of the present invention, but the present invention is not limited to the specific details in the above-mentioned solutions, and any modifications and substitutions made within the spirit and principles of the present invention; Desulfurization process (including but not limited to calcium method, sodium-alkali method, etc.) or semi-dry desulfurization process are all within the protection scope of the present invention.

Claims (5)

1. A heating furnace waste gas multi-pollutant cooperative treatment system is characterized by comprising a soot purification system and an air-smoke purification system, wherein the soot purification system and the air-smoke purification system respectively comprise an SCR (selective catalytic reduction) denitration reactor, a desulfurization reaction tower and a bag type dust collector; the front end of a flue gas inlet of an SCR denitration reactor in the soot purification system is connected with a soot primary heat exchanger and a soot secondary heat exchanger through pipelines, and the soot secondary heat exchanger is connected with an air heating furnace; the front end of a flue gas inlet of an SCR denitration reactor in the air-flue purification system is connected with an air-flue primary heat exchanger and an air mixing device through pipelines, and the air mixing device is connected with a coal-flue secondary heat exchanger.

2. The heating furnace waste gas multi-pollutant cooperative treatment system according to claim 1, wherein a clean flue gas outlet of the bag type dust collector is connected with an induced draft fan and a chimney.

3. The heating furnace exhaust gas multi-pollutant cooperative treatment system according to claim 1, wherein the SCR denitration reactor comprises a catalytic reactor, an ammonia injection grid and a static mixer.

4. The heating furnace exhaust gas multi-pollutant cooperative treatment system according to claim 1, wherein the bag filter is a straight-through bag filter, a pre-charged bag filter or an electric bag composite bag filter.

5. The heating furnace exhaust gas multi-pollutant cooperative treatment system according to claim 1, wherein the first-stage soot heat exchanger, the second-stage soot heat exchanger and the first-stage air-smoke heat exchanger are in a gas-gas indirect heat exchange mode, and the heat exchangers are plate type, heat pipe type or tube type.

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