Dry quenching circulating gas diffused gas purification and waste heat utilization system

Abstract

The utility model belongs to the technical field of dry quenching circulating gas diffused gas purification, and particularly relates to a dry quenching circulating gas diffused gas purification and waste heat utilization system which comprises a desulfurization unit, a dust removal unit, a diffused gas induced draft fan and a chimney, the desulfurization unit and the dust removal unit are connected through a flue gas pipeline, and the diffused gas induced draft fan serves as a power source. The method is characterized in that the emission port of the dust removal unit passes through the CO removal unit and then is discharged to the chimney; the CO removal unit comprises a CO catalytic oxidation device and a waste heat recovery device, and a flue gas heating device is arranged at the preceding stage of the CO catalytic oxidation device; the waste heat recovery device and a heat user form a waste heat recovery loop through a heating medium conveying device and a pipeline. According to the utility model, CO in the flue gas can be synchronously removed while SO2 and particulate matters in the diffused gas of the dry quenching circulating gas are removed; meanwhile, reaction heat in the CO catalytic oxidation process can be effectively recycled, and cooperative treatment of pollution reduction and carbon reduction is achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of dry coke quenching circulating gas emission gas purification, in particular to a dry coke quenching circulating gas emission gas purification and waste heat utilization system. Background Art

[0002] The CDQ process is a coke quenching process that uses inert gas to cool down red coke. During the production process, the 850-980℃ circulating gas discharged from the CDQ furnace annular airway passes through the primary dust collector for gravity sedimentation to remove coarse coke powder, and then enters the CDQ boiler for heat exchange, where the temperature drops to 160-180℃. The cold circulating gas from the CDQ boiler passes through the secondary dust collector to remove finer dust, and then is sent to the CDQ furnace by the circulating fan for recycling.

[0003] Since the CDQ oven needs to maintain a certain pressure and prevent the CO concentration in the circulating gas from being too high, causing explosion and other dangers, a part of the cold circulating gas needs to be continuously discharged in actual production. In addition, some exhaust gas will also be generated during the coke loading and exhausting process. The exhaust gas of the circulating gas generally contains a high concentration of SO2 (500-200mg / m 3 ), particulate matter and CO (3% to 6%) and other pollutants must be treated to meet the standards before they can be discharged.

[0004] The Chinese utility model patent with application number 202123314108.2 discloses a subcritical ultra-high temperature CDQ circulating fan outlet flue gas desulfurization and dust removal device, including a circulating gas unit connected by a circulating fan, a secondary economizer, a CDQ furnace, a primary dust collector, a CDQ boiler, and a secondary dust collector through a circulating gas pipeline. When the CDQ flue gas is desulfurized by dry method, the temperature of the flue gas reaches the temperature requirement of the dry desulfurization process, and the desulfurization and dust removal of the CDQ flue gas are completed, meeting the ultra-low emission requirements specified in national regulations.

[0005] At present, the purification technology for the exhaust gas of CDQ circulating gas is usually to discharge the exhaust gas after desulfurization and dust removal. The CO in the flue gas will be discharged into the atmosphere, which will not only cause environmental pollution but also waste energy. Utility Model Content

[0006] The purpose of the utility model is to provide a CDQ cycle gas exhaust gas purification and waste heat utilization system, which overcomes the shortcomings of the prior art and can remove SO2 and particulate matter in the exhaust gas while removing CO in the flue gas, and at the same time recycle the reaction heat in the flue gas, thereby controlling the emission of pollutants in the flue gas and effectively utilizing the reaction heat in the flue gas, and ultimately achieving coordinated pollution reduction and carbon reduction.

[0007] To achieve the above purpose, the utility model is implemented through the following technical solutions:

[0008] A system for purifying and utilizing waste heat of a dry coke quenching cycle gas exhaust gas, comprising a desulfurization unit, a dust removal unit, an exhaust gas induced draft fan and a chimney, wherein the desulfurization unit and the dust removal unit are connected via a flue gas pipeline, and the exhaust gas induced draft fan is used as a power source, and is characterized in that the exhaust port of the dust removal unit is discharged to the chimney after passing through a CO removal unit; the CO removal unit comprises a CO catalytic oxidation device and a waste heat recovery device, and a flue gas heating device is provided in the front stage of the CO catalytic oxidation device; the waste heat recovery device forms a waste heat recovery loop through a heat medium conveying device, a pipeline and a heat user.

[0009] A smoke standby heater is provided on the front side or the rear side of the smoke heating device, and the smoke standby heater can be heated by electricity or gas hot air.

[0010] The desulfurization unit is composed of a desulfurization agent preparation device, a desulfurization agent conveying device and a desulfurization tower which are connected in sequence. Dry desulfurization is adopted and the desulfurization agent is fine sodium bicarbonate powder or fine slaked lime powder.

[0011] The dust removal unit is composed of a pulse bag dust collector and a dust ash conveying system, and the dust ash conveying system adopts a mechanical or pneumatic conveying method.

[0012] The CO oxidation catalyst in the CO catalytic oxidation device is a honeycomb hollow structure.

[0013] The waste heat recovery device is a waste heat boiler or a thermal oil heater; the heat medium conveying device is a centrifugal pump.

[0014] Instruments are respectively provided on the pipelines at the inlet of the desulfurization unit, the inlet of the CO removal unit or the inlet and outlet of the CO catalytic oxidation device and the outlet of the waste heat recovery device. The instruments are any one of a thermometer, a pressure gauge, a flow meter and a component analyzer or a combination of any two or more thereof.

[0015] The pipeline of the CO removal unit is provided with a parallel bypass branch, and the parallel bypass branch is provided with a flue gas bypass electric regulating valve.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] 1) The process system of the utility model can remove CO from the flue gas simultaneously while removing SO and particulate matter from the coke oven flue gas; 2) In the process of oxidative removal of CO from the flue gas, the process system of the utility model can effectively recover the reaction heat and use this part of the heat for heat users in the plant area; 3) The process system of the utility model can not only control the emission of pollutants in the flue gas, but also effectively utilize the reaction heat in the flue gas, and finally realize the coordinated governance of pollution reduction and carbon reduction, which is in line with the national energy conservation and emission reduction policy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1It is a schematic diagram of the process structure of an embodiment of the utility model.

[0019] In the figure: 1-desulfurizing agent preparation device, 2-desulfurizing agent injection device, 3-desulfurization tower, 4-pulse bag filter, 5-dust ash conveying system, 6-flue gas standby heater, 7-flue gas heating device, 8-CO catalytic oxidation device, 9-waste heat recovery device, 10-heat medium conveying device, 11-heat user, 12-discharge air induced draft fan, 13-instrument, 14-flue gas electric regulating valve, 15-flue gas bypass electric regulating valve, 16-air introduction electric regulating valve, 17-air introduction pipe, 18-CO removal unit, 19-parallel bypass branch. DETAILED DESCRIPTION

[0020] The technical solution of the present utility model will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present utility model, rather than all of the embodiments.

[0021] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the specific embodiments required to be used in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some implementation methods of the utility model. For ordinary technicians in this field, other specific embodiments can be obtained based on these specific embodiments without paying creative work.

[0022] The components of the embodiments of the present invention generally described and shown in the specific embodiments herein can be arranged and designed in countless different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the specific embodiments is not intended to limit the scope of the utility model claimed, but only represents the selected embodiments of the utility model.

[0023] See Figure 1 , is a schematic structural diagram of an embodiment of a CDQ cycle gas exhaust gas purification and waste heat utilization system of the utility model, comprising a desulfurization unit, a dust removal unit, an exhaust gas induced draft fan 12 and a chimney, the desulfurization unit and the dust removal unit are connected through a flue gas pipeline, with the exhaust gas induced draft fan 12 as a power source, the exhaust port of the dust removal unit is discharged to the chimney after passing through the CO removal unit; the CO removal unit 18 comprises a CO catalytic oxidation device 8 and a waste heat recovery device 9, and a flue gas heating device 7 is provided in the front stage of the CO catalytic oxidation device 8; the waste heat recovery device 9 forms a waste heat recovery loop through a heat medium conveying device 10, a pipeline and a heat user 11, and the CDQ cycle exhaust gas is discharged to the chimney after desulfurization, dust removal and CO removal.

[0024] The desulfurization unit is composed of a desulfurizer preparation device 1, a desulfurizer conveying device 2 and a desulfurization tower 3 connected in sequence. Dry desulfurization is adopted, and the desulfurizer is sodium bicarbonate fine powder or slaked lime fine powder. A flue gas standby heater 6 is provided on the front side of the flue gas heating device 7. The flue gas standby heater 6 can be heated by electric heating or gas hot air. The dust removal unit is composed of a pulse bag dust collector 4 and a dust ash conveying system 5. The dust ash conveying system 5 adopts a mechanical or pneumatic conveying method. The CO oxidation catalyst in the CO catalytic oxidation device 8 is a honeycomb hollow structure. The waste heat recovery device 9 is a waste heat boiler or a thermal oil heater; the heat medium conveying device is a centrifugal pump.

[0025] Instruments 13 are provided on the pipelines at the inlet of the desulfurization unit, the inlet of the CO removal unit 18, or the inlet and outlet of the CO catalytic oxidation device 8 and the outlet of the waste heat recovery device 9. The instrument 13 is a combination of a thermometer, a pressure gauge, a flow meter and a component analyzer. The pipeline of the CO removal unit 18 is provided with a parallel bypass branch 19, and the parallel bypass branch is provided with a flue gas bypass electric regulating valve 15. When the CO removal unit 18 is under maintenance, fails or the vented gas meets the standard, the flue gas bypass electric regulating valve 15 is opened, and the parallel bypass branch 19 forms a bypass vent.

[0026] The pipeline of the CO removal unit 18 is provided with a flue gas electric regulating valve 15 and an air inlet pipe 17. The air inlet pipe is provided with an air inlet electric regulating valve 16. The air inlet electric regulating valve 16 is interlocked with the instrument 13 to control the valve opening according to the CO concentration, O2 concentration and the reaction temperature of the CO catalytic oxidation device in the exhaust gas.

[0027] The SO2 concentration in the qualified exhaust gas discharged through the chimney after treatment by the utility model is less than 50mg / Nm 3 、Particle concentration<10mg / Nm 3 , CO concentration <1000mg / Nm 3 , flue gas temperature <130°C. The utility model process and device can simultaneously remove CO2 from flue gas while removing SO and particulate matter from the exhaust gas of CDQ circulating gas, and can effectively recover the reaction heat in the catalytic oxidation process of CO, and use this part of heat for heat users in the plant area, thus realizing the coordinated governance of pollution reduction and carbon reduction.

[0028] During normal production of CDQ, the purification process of the exhaust gas of CDQ circulating gas is as follows: the exhaust gas at about 160°C is introduced into the desulfurization tower 3 of the desulfurization unit through the flue gas pipeline, and the dry powder desulfurizer prepared by the desulfurizer preparation device 1 of the desulfurization unit is sent into the desulfurization tower 3 through the desulfurizer injection device 2. In the desulfurization tower 3, the SO2 component in the exhaust gas reacts with the desulfurizer to remove the SO2 in the flue gas, and the generated desulfurization ash and the coke powder particles in the exhaust gas are filtered out by the pulse bag dust collector 4 in the dust removal unit, and the generated dust is discharged by the dust removal ash conveying system 5. After the exhaust gas is desulfurized and dusted, the flue gas temperature is about 140-150°C, and the efficient working temperature of the CO removal catalyst is above 180°C, so the exhaust gas needs to be heated to above 180°C before being sent into the CO catalytic oxidation device 8, so a flue gas standby heater 6 is provided to heat the exhaust gas to above 180°C during the start-up of the device. When the exhaust gas passes through the CO catalytic oxidation device 8, the CO (content is generally 3% to 6%) in the exhaust gas reacts with O2 to generate CO2 under oxygen-containing conditions through the action of the catalyst, and releases a large amount of reaction heat. The outlet exhaust gas temperature of the CO catalytic oxidation device 8 reaches 400-600°C, and then the heat of the exhaust gas is utilized through the waste heat recovery device 9. A part of the heat medium is sent to the flue gas heating device 7 to heat the exhaust gas to be de-COed, raising its temperature to above 180°C, and the other part is sent to the heat users of the coking plant, and the exhaust gas outlet temperature is reduced to about 110°C before being discharged into the atmosphere.

[0029] Flue gas temperature, pressure and flow detection instruments are arranged on the pipeline for the vented gas to enter the desulfurization tower 3. Flue gas thermometer, pressure gauge and gas component detector are arranged before the vented gas enters the CO catalytic removal unit after desulfurization and dust removal, so as to monitor the concentrations of SO2, particulate matter and CO in the vented gas. Flue gas temperature and pressure detection are arranged before the vented gas enters the CO catalytic oxidation device 8 after being heated. Flue gas temperature and pressure detection are also arranged after the vented gas passes through the CO catalytic oxidation device 8. Flue gas temperature, pressure, gas component and other detection instruments are arranged after the vented gas recovers heat through the waste heat recovery device 9. Finally, flue gas temperature, pressure, flow and gas component and other detection instruments are also arranged on the vented gas external exhaust chimney to monitor the emission of pollutants.

[0030] During normal CDQ production, the CO concentration in the exhaust gas is relatively stable, generally between 3% and 6%. After desulfurization and dust removal, the exhaust gas enters the CO catalytic removal unit. At this time, the flue gas electric regulating valve 14 is in the open state, and the flue gas bypass electric regulating valve 15 is in the closed state. The opening of the air introduction electric regulating valve 16 is controlled according to the ratio of CO and O2 in the exhaust gas, so that CO can be basically completely removed. When the CO concentration in the exhaust gas is higher than 6% and lower than 10%, the opening of the flue gas electric regulating valve 14 is reduced, and the opening of the flue gas bypass electric regulating valve 15 is adjusted to bypass a part of the exhaust gas without passing through the CO removal unit 18. At the same time, the air introduction electric regulating valve 16 is adjusted to ensure that the outlet temperature of the CO catalytic oxidation device 8 does not exceed 650°C; when it is detected that the CO in the exhaust gas exceeds 10%, the air introduction electric regulating valve 16 and the flue gas electric regulating valve 14 are immediately interlocked and closed, and the flue gas bypass electric regulating valve 15 is opened. When the CO concentration continues to rise and exceeds 11%, the exhaust gas induced draft fan 12 and each unit device are interlocked and closed.

[0031] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for purifying and utilizing waste heat of a CDQ circulating gas exhaust gas, comprising a desulfurization unit, a dust removal unit, an exhaust gas induced draft fan and a chimney, wherein the desulfurization unit and the dust removal unit are connected via a flue gas duct, and the exhaust gas induced draft fan is used as a power source, and is characterized in that: The emission port of the dust removal unit is discharged to the chimney after passing through the CO removal unit; the CO removal unit includes a CO catalytic oxidation device and a waste heat recovery device, and a flue gas heating device is provided in the front stage of the CO catalytic oxidation device; the waste heat recovery device forms a waste heat recovery loop through a heat medium conveying device, a pipeline and a heat user.

2. A CDQ cycle gas exhaust gas purification and waste heat utilization system according to claim 1, characterized in that: A smoke standby heater is provided on the front side or the rear side of the smoke heating device, and the smoke standby heater can be heated by electricity or gas hot air.

3. A CDQ cycle gas exhaust gas purification and waste heat utilization system according to claim 1, characterized in that: The desulfurization unit is composed of a desulfurization agent preparation device, a desulfurization agent conveying device and a desulfurization tower which are connected in sequence. Dry desulfurization is adopted and the desulfurization agent is fine sodium bicarbonate powder or fine slaked lime powder.

4. A CDQ cycle gas exhaust gas purification and waste heat utilization system according to claim 1, characterized in that: The dust removal unit is composed of a pulse bag dust collector and a dust ash conveying system, and the dust ash conveying system adopts a mechanical or pneumatic conveying method.

5. The CDQ circulating gas exhaust gas purification and waste heat utilization system according to claim 1, characterized in that: The CO oxidation catalyst in the CO catalytic oxidation device is a honeycomb hollow structure.

6. A CDQ cycle gas exhaust gas purification and waste heat utilization system according to claim 1, characterized in that: The waste heat recovery device is a waste heat boiler or a thermal oil heater; the heat medium conveying device is a centrifugal pump.

7. The CDQ circulating gas exhaust gas purification and waste heat utilization system according to claim 1, characterized in that: Instruments are respectively provided on the pipelines at the inlet of the desulfurization unit, the inlet of the CO removal unit or the inlet and outlet of the CO catalytic oxidation device and the outlet of the waste heat recovery device. The instruments are any one of a thermometer, a pressure gauge, a flow meter and a component analyzer or a combination of any two or more thereof.

8. The CDQ circulating gas exhaust gas purification and waste heat utilization system according to claim 1, characterized in that: The pipeline of the CO removal unit is provided with a parallel bypass branch, and the parallel bypass branch is provided with a flue gas bypass electric regulating valve.

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