CN104073581A - Process method and device for forcibly recovering diffused gas of blast furnace - Google Patents

Abstract

The invention relates to a process for forced recovery of blown gas from a blast furnace, comprising the following steps: when starting to blow off, the gas in the weighing material tank is introduced into a dry-type bag filter through a pipeline through a natural recovery method, and the clean gas after being dedusted by the bag filter Enter the low-pressure clean gas main pipe; when the gas pressure in the weighing material tank drops to the set value, start the gas exhaust fan for a second forced recovery of the diffused gas, and the residual diffused gas will be discharged into the net through the outlet pipe of the fan after being dusted by the bag filter. Gas main pipe; the present invention simultaneously provides the device that realizes this technological method. Compared with the prior art, the beneficial effect of the present invention is that it overcomes the shortcomings of the natural gas recovery process, adopts the secondary recovery method combining natural recovery and forced recovery to realize high-efficiency recovery of the gas released from the top of the blast furnace, and can be produced in the blast furnace More than 90% of the blast furnace vent gas is recovered within the allowable time (40 seconds), reducing environmental pollution and producing more obvious economic benefits at the same time.

Description

Process method and device for forced recovery of blown gas from blast furnace

technical field

The invention relates to the technical field of blast furnace blow-off gas recovery, in particular to a process method and device for forced recovery of blow-furnace blow-off gas.

Background technique

The blast furnace top charging equipment needs to regularly discharge the residual gas in the weighing tank or the big bell sealed bin to the atmosphere during the charging process, so as to open the upper sealing valve or the small bell equipment, and the receiving tank or small bell The charge in the bell bucket is discharged into the weighing material tank or the big bell warehouse, and the charging to the lower material tank or the big bell warehouse is completed.

The CO concentration in the residual gas in the feeding tank exceeds 20%, the dust concentration exceeds 5g/m ³ , and its calorific value exceeds 3000kj/Nm ³ . The discharge of this gas into the atmosphere will not only cause serious pollution to the surrounding environment, but also cause secondary pollution. The serious waste of energy, the recovery of this part of gas is the need to realize energy saving, emission reduction and environmental protection.

At present, there is only a natural recovery method for blast furnace gas release, that is, to use the gas residual pressure in the weighing material tank or the big bell warehouse to recover naturally. The disadvantages of this method are: first, only part of the gas can be recovered, and about 40% of the remaining gas remains It will be discharged into the atmosphere, causing pollution to the atmosphere; second, the recovery time is long, generally more than 1 minute, which affects the normal feeding and production of the blast furnace.

Contents of the invention

The invention provides a process method for forced recovery of blast furnace blow-off gas, which overcomes the deficiency of the natural recovery of gas process, can recover more than 90% of blast furnace blow-off gas within the time allowed for blast furnace production (within 40 seconds), and reduces environmental pollution. At the same time produce more obvious economic benefits. The present invention also provides a device capable of realizing the process described in the present invention.

In order to achieve the above object, the present invention adopts the following technical solutions to realize:

The process method of forced recovery of blast furnace vented gas adopts the secondary recovery method combining natural recovery and forced recovery to realize high-efficiency recovery of blast furnace top vented gas, and the recovery rate of vented gas exceeds 90%. It includes the following steps: Due to the dual effects of the self-pressure of the gas in the measuring tank and the negative pressure at the outlet generated by the suction and discharge of the ejector, the gas in the weighing tank is introduced into the dry bag filter through the pipeline, and the clean gas after dust removal by the bag filter is cleaned. The gas bypass pipe enters the low-pressure clean gas main pipe; when the gas pressure in the weighing material tank drops to the set value, that is, at the end of the recovery of the diffused gas, the gas exhaust fan is started to forcibly recover the diffused gas for a second time, and the remaining diffused gas is passed through the cloth bag After the dust is removed by the dust collector, it is discharged into the clean gas main pipe through the outlet pipe of the fan; the dust is sent to the user point by means of suction and discharge vehicles or pneumatic conveying.

The bag filter is composed of 1 to 2 boxes, all of which are working boxes; when the bag filter is shut down for maintenance, the diffused gas passes through the furnace top gas diffuser silencer and the release pipe to achieve standard discharge.

The gas exhaust fan adopts a continuous working system, and the flow rate is controlled by the frequency conversion speed regulation of the motor.

The dust-removing bag adopts low-pressure nitrogen online pulse cleaning, and uses the intermittent time of gas release to complete the cleaning operation; the bag filter has a pressure difference detection at the crude gas inlet and clean gas outlet, and when the pressure difference between the crude gas inlet and the clean gas outlet is ΔP ≥8.0kPa, low-pressure nitrogen pulse cleaning is performed on the dust collector; when the pressure difference after cleaning is ≤2.0kPa, the cleaning process ends.

There is a dust level meter in the ash bin below the bag filter to detect the ash accumulation in the ash bin. When the ash accumulation surface reaches the upper limit, the ash accumulation needs to be discharged. The ash discharge pipe in the ash bin is connected to the ash discharge truck, and the ash accumulation in the ash bin is sucked into the suction and discharge vehicle; when the ash accumulation level in the ash bin drops to the lower limit, the ash discharge operation is stopped.

The dust content of the blast furnace net gas purified by bag dust removal is ≤5mg/m ³ , the temperature of the net gas is less than 200°C, and the pressure is greater than 20kPa.

The device used to realize the process method of forced recovery of blast furnace exhaust gas, including a furnace top crude gas release system, a dust removal and dust removal ash recovery system, and a release gas recovery system connected in sequence by pipelines. The furnace top crude gas release system is composed of weighing It is composed of a material tank, a release muffler and a discharge pipe; the dust removal and dust removal ash recovery system is composed of a nitrogen delivery pipeline, a bag filter and a dust removal ash suction and discharge vehicle; the release gas recovery system is composed of a gas ejector, a gas exhaust fan, The net gas outlet bypass pipe and the net gas main pipe are composed.

A cut-off valve is set on the diffused gas discharge pipe and the muffler inlet pipe of the crude gas release system on the furnace top; an explosion-proof safety valve is set on the upper part of the bag filter of the dust removal and dust recovery system, and a nitrogen cut-off valve is set on the nitrogen delivery pipeline and a blowback nitrogen pressure reducing valve; a gas recovery control valve is set in front of the gas ejector of the diffused gas recovery system, an inlet cut-off valve is set in front of the gas exhaust fan, and a cut-off valve is set on the clean gas outlet bypass pipe.

A differential pressure gauge is provided on the gas inlet and outlet pipelines of the bag filter.

An ash bin is arranged under the bag filter, an ash discharge pipe is arranged under the ash bin, and a pendulum ash discharge valve and a star ash discharge valve are arranged on the ash discharge pipe.

Compared with prior art, the beneficial effect of the present invention is:

The invention overcomes the deficiency of the natural gas recovery process, and adopts the secondary recovery method combining natural recovery and forced recovery to realize high-efficiency recovery of the gas emitted from the top of the blast furnace, and can recover 90% of the gas within the time allowed by the blast furnace production (within 40 seconds) The above-mentioned blast furnace releases gas, reduces environmental pollution, and produces more obvious economic benefits at the same time.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

In the figure: 1. Weighing material tank 2. Diffuse gas discharge pipe 3. Diffuse gas discharge pipe cut-off valve 4. Muffler inlet cut-off valve 5. Diffuse muffler 6. Diffuse pipe 7. Gas recovery control valve 8. Gas injection 9. Bag filter inlet pipe 10. Differential pressure gauge 11. Explosion-proof safety valve 12. Bag filter 13. Gas exhaust fan inlet cut-off valve 14. Gas exhaust fan inlet pipe 15. Gas exhaust fan outlet pipe 16. Back blowing nitrogen Pressure reducing valve 17. Nitrogen cut-off valve 18. Bag dust collector ash bin 19. Dust removal ash suction and discharge vehicle 20. Clean gas bypass pipe 21. Clean gas bypass pipe cut-off valve 22. Gas exhaust fan 23. Clean gas supervisor

Detailed ways

The specific embodiment of the present invention will be further described below in conjunction with accompanying drawing:

See Fig. 1, it is process flow diagram of the present invention, the process method of the forced recovery blast furnace blowing gas of the present invention, adopts the secondary recovery mode that natural recovery and forced recovery combine to blast furnace roof blowing gas realizes high-efficiency recovery, blowing off gas The recovery rate exceeds 90%; it comprises the following steps: when starting to disperse, utilize the dual effect of the self pressure of the gas in the weighing material tank 1 and the outlet negative pressure produced by the suction and discharge of the ejector 8, and transfer the gas in the weighing material tank 1 through the pipeline. The coal gas is introduced into the dry bag filter 12, and the clean gas after the dust removal by the bag filter 12 enters the low-pressure clean gas main pipe 23 through the clean gas bypass pipe 20; when the gas pressure in the weighing material tank 1 drops to the set value, that is At the end of the recovery of the diffused gas, start the gas exhaust fan 22 to recycle the diffused gas for a second time, and the residual diffused gas will be discharged into the clean gas main pipe 23 through the fan outlet pipe 15 after dust removal by the bag filter 12; The delivery method is sent to the user point.

The bag filter 12 is composed of 1 to 2 boxes, all of which are working boxes; when the bag filter 12 is shut down for maintenance, the released gas passes through the furnace top gas release muffler 5 and the release pipe 6 to achieve standard discharge.

The gas exhauster 22 adopts a continuous working system, and the flow rate is controlled by the motor frequency conversion speed regulation, so as to adapt to the intermittent working state of gas release, eliminate the damage caused by frequent starting to the motor, and save electric energy.

The dust-removing bag adopts low-pressure nitrogen online pulse cleaning, and uses the intermittent time of gas release to complete the cleaning operation; the bag filter 12 is equipped with a pressure difference detection at the crude gas inlet 9 and the clean gas outlet. If the difference △P≥8.0kPa, perform low-pressure nitrogen pulse cleaning on the dust collector 12; when the pressure difference after cleaning is ≤2.0kPa, the cleaning process ends.

The ash bin 18 below the bag filter 12 is provided with a dust level meter to detect the ash accumulation in the ash bin 18. When the ash accumulation surface reaches the upper limit, the ash accumulation needs to be discharged; 19 is connected with the ash discharge pipe of the bag filter, and the ash accumulation in the ash bin 18 is sucked into the suction and discharge vehicle 19; when the ash accumulation surface in the ash bin 18 drops to the lower limit, the ash discharge operation is stopped.

The dust content of the blast furnace net gas purified by bag dust removal is ≤5mg/m ³ , the temperature of the net gas is less than 200°C, and the pressure is greater than 20kPa.

The device for realizing the process method of forced recovery of blast furnace blowing gas described in the present invention includes a furnace top rough gas blowing system, a dust removal and dust removal ash recovery system, and a blown gas recovery system connected in sequence by pipelines. The system is composed of a weighing tank 1, a release muffler 5 and a release pipe 6; the dust removal and dust removal ash recovery system is composed of a nitrogen delivery pipeline, a bag filter 12 and a dust removal ash suction and discharge vehicle 19; the release gas recovery system consists of Gas ejector 8, gas exhaust fan 22, clean gas outlet bypass pipe 20 and clean gas main pipe 23 form.

The gas inlet pipe before the gas ejector 8 is connected to the diffused gas discharge pipe 2 before the gas diffuser muffler 5, the gas outlet pipe behind the gas ejector 8 is also the gas inlet pipe 9 of the bag filter 12, and the nitrogen delivery pipe The gas ejector 8 and the bag filter 12 are respectively connected; the clean gas output pipeline of the bag filter 12 is divided into two routes, one is connected to the clean gas main pipe 23 through the gas exhaust fan 22, and the other is connected to the clean gas pipeline through the gas bypass pipe 20. Gas main 23.

Shut-off valves 3, 4 are set on the diffused gas discharge pipe 2 and the muffler inlet pipe of the furnace top crude gas diffuser system; explosion-proof safety valve 11 is set on the upper part of the bag filter 12 of the dust removal and dust removal ash recovery system, and nitrogen transport A nitrogen cut-off valve 17 and a blowback nitrogen pressure reducing valve 16 are arranged on the pipeline; a gas recovery control valve 7 is set in front of the gas ejector 8 of the diffused gas recovery system, an inlet cut-off valve 13 is set in front of the gas exhaust fan 22, and a clean gas outlet A cut-off valve 21 is provided on the bypass pipe 20 .

A differential pressure gauge 10 is provided on the gas inlet and outlet pipelines of the bag filter 12 .

An ash bin 18 is arranged under the bag filter 12, an ash discharge pipe is arranged under the ash bin, and a pendulum ash discharge valve and a star ash discharge valve are arranged on the ash discharge pipe.

When furnace charge is emptied in the furnace top weighing tank 1, and the upper and lower sealing valves are closed, start to reclaim and release gas. The specific method is: close the muffler inlet cut-off valve 4, open the gas discharge pipe cut-off valve 3, the gas recovery control valve 7, the gas exhaust fan inlet cut-off valve 13, the clean gas outlet bypass pipe cut-off valve 21, so that the gas outlet to the clean gas The gas pipeline of the supervisor 23 is connected; the nitrogen shut-off valve 17 is opened, the nitrogen gas enters the gas ejector 8 and produces a low-pressure area at the outlet of the gas ejector 8, and releases the dual effects of the gas on its own pressure and the suction force of the gas ejector 8 Down enters the bag filter 12, the clean gas after the bag filter 12 dedusts enters the clean gas main pipe 20 through the clean gas bypass pipe 20, and completes the primary recovery of the diffused gas. When the pressure in the weighing material tank 1 is lower than the set value, the gas exhaust fan 22 is turned on, and the low-pressure residual gas in the weighing material tank 1 and the system is forced into the clean gas main pipe 23 through the gas exhaust fan 22 to complete the release Secondary recovery of gas. When the pressure in the weighing material tank 1 was lower than the lower limit, the gas exhaust fan 23 stopped working, closed the gas recovery control valve 7, closed the nitrogen shut-off valve 17, and the furnace top equipment began to charge normally.

When the gas blower 22 breaks down, utilize the self pressure of releasing the gas and the gas injector 8 to carry out the recovery of releasing the gas. Now close the gas blower inlet cut-off valve 13, open the clean gas outlet bypass pipe cut-off valve 21, open the nitrogen cut-off valve 17, and release the gas into the bag filter 12 under the force of its own pressure and the ejector 8. The clean gas after dust removal by the bag filter 12 enters the clean gas main pipe 24 through the clean gas bypass pipe 20 to complete the recovery of the diffused gas. At this time, a small amount of gas remains in the system, which can be discharged into the atmosphere through the silencing and dispersing system. The operation steps are: open the cut-off valve 3 of the gas discharge pipe, open the cut-off valve 4 of the muffler inlet, and then close the cut-off valve 13 of the gas exhaust fan inlet. Clean gas outlet bypass pipe cut-off valve 21, close the gas recovery control valve 7, close the nitrogen cut-off valve 17, the residual gas in the system is discharged through the release pipe 6 to reach the standard after being silenced and dust-removed by the release silencer 5.

A differential pressure gauge is provided on the gas inlet and outlet pipelines of the bag filter. When the pressure difference between the crude gas inlet and the clean gas outlet is △P≥6.0kPa, it is necessary to carry out ash cleaning operation on the gas bag filter 12. Use the intermittent time of gas release to carry out the dust removal operation of the bag. The duration of a gas release is about 40s, the intermittent time is about 150s, and the back blowing cleaning time is controlled within 100s.

Low-pressure nitrogen pulse cleaning is used. When the pressure difference after cleaning is ≤2.0kPa, the cleaning process is over.

The operation mode of dust cleaning operation: close the gas recovery control valve 7, close the shut-off valve of gas exhaust fan inlet 13, open the nitrogen shut-off valve 17, open the nitrogen pressure reducing valve for back blowing of bag filter 16, open the clean gas outlet bypass pipe shut-off valve 21. The back blowing nitrogen enters the bag box, and the bag is controlled by the pulse valve to carry out back blowing and dust removal operation. The dust accumulated on the outer surface of the bag is shaken off and falls to the bag dust collector ash bin 18 below the bag filter. , the back blowing nitrogen enters the clean gas main pipe 24 through the clean gas bypass pipe 20, and completes the nitrogen back blowing and dust removal operation.

A dust level meter is provided in the ash bin 18 below the gas bag filter 12 to detect the ash accumulation in the ash bin. When the ash accumulation area reaches the upper limit, the ash accumulation needs to be discharged. When ash is discharged, the dust removal ash suction and discharge vehicle 19 is connected with the bag filter ash discharge pipe, and the accumulated dust in the ash bin 18 is sucked into the suction and discharge vehicle. When the ash accumulating surface in the ash bin 18 drops to the lower limit, stop the ash discharge operation.

An explosion-proof safety valve 11 is installed on the upper part of the bag filter 12. When an explosion occurs in the system, the explosion-proof safety valve 11 will automatically open to release the pressure to ensure the safety of the system.

Taking a blast furnace with an effective volume of 3,200m ³ as an example, the recycled blast furnace released gas is about 1.5×10 ⁷ Nm ³ per year. Calculation of the calorific value of the gas is 3,200kj/Nm ³ . The heat contained in the recycled gas is about 48,000Gj, and the direct economic benefit exceeds 2 million. Yuan.

Claims (10)

1. The process method of forced recovery of blast furnace vented gas adopts a secondary recovery method combining natural recovery and forced recovery to realize efficient recovery of blast furnace top vented gas, and the recovery rate of vented gas exceeds 90%; it is characterized in that it includes the following steps: At the beginning of the release, the gas in the weighing tank is introduced into the dry bag filter through the pipeline by using the dual function of the gas's own pressure in the weighing tank and the outlet negative pressure generated by the suction and discharge of the ejector, and the dust is removed by the bag filter. The final clean gas enters the low-pressure clean gas main pipe through the clean gas bypass pipe; when the gas pressure in the weighing material tank drops to the set value, that is, at the end of the recovery of the released gas, the gas exhaust fan is started to forcibly recover the released gas for a second time. The residual diffused gas is dedusted by the bag filter and discharged into the clean gas main pipe through the outlet pipe of the fan; the dedusted ash is sent to the user site by suction and discharge vehicles or pneumatic conveying. 2. The process for forced recovery of blast furnace gas release according to claim 1, characterized in that the bag filter consists of 1 to 2 boxes, all of which are working boxes; when the bag filter is shut down for maintenance , release the gas through the furnace top gas release muffler and release pipe to achieve standard discharge. 3. The process for forced recovery of blast furnace gas release according to claim 1, characterized in that the gas exhaust fan adopts a continuous working system, and the flow rate is controlled by motor frequency conversion and speed regulation. 4. The process of forced recovery of blast furnace gas release according to claim 1, characterized in that, the dust removal bag adopts low-pressure nitrogen online pulse cleaning, and utilizes the intermittent time of gas release to complete the cleaning operation; The inlet and the clean gas outlet are equipped with pressure difference detection. When the pressure difference between the crude gas inlet and the clean gas outlet is △P≥8.0kPa, the dust collector is cleaned by low-pressure nitrogen pulse; when the pressure difference after cleaning is ≤2.0kPa, the cleaning process is over. . 5. The process for forced recovery of blast furnace gas release according to claim 1, characterized in that a dust level meter is provided in the ash bin below the bag filter to detect the ash accumulation in the ash bin. When the ash surface reaches the upper limit, it is necessary to discharge the accumulated ash; when discharging the ash, connect the dust removal ash suction and discharge vehicle to the ash discharge pipe of the bag filter, and the ash accumulated in the ash bin is sucked into the suction and discharge vehicle; when the ash accumulation surface in the ash bin drops to the bottom Within a limited time, stop the ash discharge operation. 6. The process for forced recovery of blast furnace gas release according to claim 1, characterized in that the dust content of the blast furnace net gas after bag dust removal and purification is ≤5 mg/m ³ , the net gas temperature is less than 200°C, and the pressure is >20kPa. 7. The device for realizing the process method of the forced recovery of blast furnace blowing gas according to claim 1, characterized in that it comprises a furnace top crude gas blowing system, a dust removal and dust removal ash recovery system and a blown gas recovery system connected successively by pipelines , the furnace top crude gas release system is composed of a weighing tank, a release silencer and a release pipe; the dust removal and dust recovery system is composed of a nitrogen delivery pipeline, a bag filter and a dust suction and discharge vehicle; the release of gas The recovery system consists of a gas ejector, a gas exhaust fan, a clean gas outlet bypass pipe and a clean gas main pipe. 8. The device for forced recovery of blast furnace gas release according to claim 6, characterized in that, a cut-off valve is set on the gas release pipe and the muffler inlet pipe of the crude gas release system on the top of the furnace; the dust removal and dust removal The upper part of the bag dust collector of the ash recovery system is equipped with an explosion-proof safety valve, and the nitrogen delivery pipeline is equipped with a nitrogen shut-off valve and a blowback nitrogen pressure reducing valve; the gas ejector of the diffused gas recovery system is equipped with a gas recovery control valve and a gas exhaust fan. There is an inlet cut-off valve at the front, and a cut-off valve on the clean gas outlet bypass pipe. 9. The device for forced recovery of blast furnace gas release according to claim 6, characterized in that a differential pressure gauge is provided on the gas inlet and outlet pipelines of the bag filter. 10. The device for forced recovery of blast furnace gas release according to claim 6, characterized in that an ash bin is arranged below the bag filter, an ash discharge pipe is arranged below the ash bin, and a pendulum ash discharge valve and ash discharge valve are arranged on the ash discharge pipe. Star dust discharge valve.