Accurate and efficient denitration device for flue gas of smelting kiln

Abstract

The utility model belongs to the field of smelting kiln flue gas treatment, and provides a smelting kiln flue gas accurate and efficient denitration device which comprises a reducing agent storage and supply system, an efficient denitration reactor and a tail oxidation process denitration system, the whole system is controlled by a control system, and a front temperature testing device is arranged at the front end of the efficient denitration reactor; when the flue gas temperature of the kiln is above 750 DEG C, the control system controls the precise ammonia spraying system to work; and when the temperature of the flue gas is below 750 DEG C, the control system controls an oxidation process denitration system arranged at the tail part to carry out denitration work. The disadvantage that low-temperature denitration or single-oxidation-method denitration is high in operation cost is effectively overcome, denitration is conducted through an efficient and accurate denitration system under the condition that the flue gas temperature is higher than 750 DEG C, and under the condition that the flue gas temperature is lower than 750 DEG C, denitration is conducted through supplementation of a tail oxidation device. And long-term stable up-to-standard emission of pollutants during normal production of an enterprise smelting kiln is ensured, so that the operation cost of the system is greatly saved.

Description

Technical Field

[0001] The utility model relates to the field of smelting furnace flue gas treatment, in particular to a precise and efficient denitrification device for smelting furnace flue gas. Background Art

[0002] At present, the flue gas composition of smelting kilns is complex, and the flue gas contains a large amount of heavy metals, especially arsenic. At the same time, the sulfur content in the flue gas before desulfurization is very high, sometimes as high as 50,000 mg / Nm3. At the same time, the temperature of the flue gas of the smelting kiln fluctuates periodically according to the periodicity of the feed. Therefore, the denitrification of the flue gas of this type of smelting kiln is a difficulty and pain point in this industry.

[0003] Conventional flue gas denitrification technologies are categorized as in-furnace denitrification and end-of-pipe treatment. These technologies include low-NOx combustion, SNCR flue gas denitrification, SCR flue gas denitrification, and oxidation denitrification. Smelting kilns generally lack burners, making low-NOx burner retrofitting unnecessary. Furthermore, because arsenic in flue gas irreversibly affects SCR denitrification catalysts, SCR flue gas denitrification cannot be performed on smelting kiln flue gas before desulfurization. After desulfurization, the flue gas temperature is only around 60°C. Using SCR denitrification requires heating the flue gas, consuming significant energy and resulting in high operating costs and uneconomical efficiency. Using oxidation denitrification alone would be prohibitive due to high system operating costs and wastewater treatment issues, making it unacceptable to the enterprise.

[0004] This application conducts new attempts and research and development under such background, and proposes a new idea and system for a precise and efficient denitrification device for smelting furnace flue gas to solve the above problems. Utility Model Content

[0005] The purpose of the present utility model is to overcome the above-mentioned deficiencies of the prior art and to provide a device that can automatically adjust denitrification according to the set temperature. When the flue gas temperature is higher than 750°C, denitrification is carried out by a high-efficiency and precise denitrification system. When the flue gas temperature is less than 750°C, the tail oxidation device is supplemented to ensure that the pollutants in the enterprise's smelting kiln are discharged in a long-term and stable manner in normal production and meet the emission standards, and simultaneously save the system operating costs, thereby achieving a precise and efficient denitrification device for the flue gas of the smelting kiln.

[0006] The technical solution of the utility model is: a precise and efficient denitrification device for smelting furnace flue gas, comprising a reducing agent storage and supply system, a high-efficiency denitrification reactor and a tail oxidation denitrification system, wherein the front end of the high-efficiency denitrification reactor is provided with a precise injection system, the precise injection system is connected to the reducing agent metering and distribution system via a pipeline, the reducing agent metering and distribution system is connected to the reducing agent storage and supply system via a pipeline, the rear end of the high-efficiency denitrification reactor is provided with a tail oxidation denitrification system, and the rear end of the tail oxidation denitrification system is provided with a spray alkali washing tower; the entire system is controlled by a control system, and the front end of the high-efficiency denitrification reactor is provided with a pre-temperature testing device;

[0007] When the kiln flue gas temperature is above 750℃, the control system controls the operation of the precise ammonia injection system, so that the flue gas and the reducing agent injected by the precise ammonia injection system enter the high-efficiency denitrification reactor together;

[0008] When the flue gas temperature is below 750℃, the control system controls the denitrification system installed at the tail to perform denitrification.

[0009] The advantage of this solution is that it can effectively adapt to the actual situation where the flue gas composition of the kiln is complex and the flue gas temperature changes periodically. It perfectly solves the high operating cost problem of SCR flue gas denitrification and single oxidation denitrification, greatly reduces the waste gas pollution problem of single oxidation denitrification, and simultaneously achieves environmental protection and economic benefits.

[0010] Furthermore, the reducing agent storage and supply system includes a multi-stage centrifugal pump, a metering pump and a horizontal pump to pressurize the reducing agent. A filtering device is provided at the pump inlet, and the filtering device is a basket filter or a Y-type filter.

[0011] Furthermore, the reducing agent metering and distribution system is an integral skid-mounted module, including an automatic control ball valve, an automatic control regulating valve and a flow meter; the automatic control ball valve and the electric control ball valve are both electrically or pneumatically controlled, and the flow meter is an electromagnetic flow meter or a float flow meter.

[0012] Furthermore, the precision injection system includes an injection device, a pre-NOx / O2 monitoring device, and a post-NOx / O2 monitoring device. The pre-NOx / O2 monitoring device and the post-NOx / O2 monitoring device are respectively installed at the front and rear ends of the high-efficiency denitrification reactor, and the injection device is installed between the pre-NOx / O2 monitoring device and the high-efficiency denitrification reactor. Preferably, the pre-NOx / O2 monitoring device and the post-NOx / O2 monitoring device can withstand high temperatures of 1000°C.

[0013] Furthermore, the spray device is a mechanical atomizing device or a compressed air atomizing device, and is provided with a nozzle made of silicon carbide or Hastelloy. Preferably, the body of the spray device is made of SS316, SS304 or SS310 to ensure the service life of the spray device.

[0014] Furthermore, the front temperature testing device is arranged at the front end of the front NOx / O2 monitoring device and is provided with at least three temperature measuring points.

[0015] Furthermore, the residence time of the flue gas in the high-efficiency denitration reactor is 1.5s-2s; the high-efficiency denitration reactor is a cyclone separator type or a mixer type.

[0016] Furthermore, an outer protective plate and a high-temperature casting material layer are provided on the outside of the high-efficiency denitrification reactor, and the thickness of the outer protective plate is 6-10 mm. Preferably, the thickness of the outer protective plate is 7 mm, 8 mm or 9 mm.

[0017] Furthermore, a dust removal and desulfurization device is provided between the high-efficiency denitrification reactor and the tail oxidation denitrification system; the tail oxidation denitrification system includes an oxidation denitrification device, and the operation of the oxidation denitrification device is controlled by a controller according to the test data of the post-NOx / O2 monitoring equipment and the CEMS device, and the CEMS device is arranged on the chimney.

[0018] Furthermore, the oxidation denitrification device includes a plate heat exchanger, an air compressor system and an ozone generator. The plate heat exchanger dissipates heat for the ozone generator, and the air compressor dilutes the pure oxygen used by the ozone generator to provide an oxygen source.

[0019] The utility model has the following beneficial effects: it effectively overcomes the disadvantage that the flue gas of the smelting kiln is complex and conventional SCR denitrification cannot be carried out, such as the high operating cost of low-temperature denitrification or single oxidation denitrification. When the flue gas temperature is higher than 750°C, denitrification is carried out through a high-efficiency and precise denitrification system. When the flue gas temperature is less than 750°C, the tail oxidation device is supplemented to ensure that the pollutants in the enterprise's smelting kiln are discharged in a long-term and stable manner during normal production, and at the same time achieve a significant saving in system operating costs, and simultaneously complete the maximization of the environmental protection benefits and economic benefits of the relevant enterprises.

[0020] The detailed structure of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 - is a schematic diagram of the structure of this utility model;

[0022] 1-Kiln flue gas, 2-Pre-temperature testing equipment, 3-Pre-NOx / O2 monitoring equipment, 4-Precision injection system, 5-High-efficiency denitrification reactor, 6-Control system, 7-Reducing agent metering and distribution system, 8-Reducing agent storage and supply system, 9-Dust removal and desulfurization device, 10-Post-NOx / O2 monitoring equipment, 11-Plate heat exchanger, 12-Ozone generator, 13-Air compressor system, 14-Specialized power distribution control cabinet, 15-Spray alkali washing tower, 16-Chimney, 17-CEMS device. DETAILED DESCRIPTION

[0023] Example 1

[0024] As shown in the accompanying drawings: a precise and efficient denitration device for smelting furnace flue gas 1, comprising a reducing agent storage and supply system 8, a high-efficiency denitration reactor 5 and a tail oxidation denitration system, a front end of the high-efficiency denitration reactor 5 is provided with a precise injection system 4, the precise injection system 4 is connected to the reducing agent metering and distribution system 7 through a pipeline, the reducing agent metering and distribution system 7 is connected to the reducing agent storage and supply system 8 through a pipeline, the rear end of the high-efficiency denitration reactor 5 is provided with a tail oxidation denitration system, and the rear end of the tail oxidation denitration system is provided with a spray alkali washing tower 15; the entire system is controlled by a control system 6, and the front end of the high-efficiency denitration reactor 5 is provided with a pre-temperature testing device 2;

[0025] When the temperature of the kiln flue gas 1 is above 750°C, the control system 6 controls the operation of the precise ammonia injection system, so that the flue gas and the reducing agent injected by the precise ammonia injection system enter the high-efficiency denitrification reactor 5 together;

[0026] When the flue gas temperature is below 750°C, the control system 6 controls the oxidation denitrification system set at the tail to perform denitrification.

[0027] This solution can effectively adapt to the actual situation where the kiln flue gas 1 has complex components and the flue gas temperature changes periodically. It perfectly solves the high operating cost problem of SCR flue gas denitrification and single oxidation denitrification, greatly reduces the wastewater pollution problem of single oxidation denitrification, and simultaneously achieves environmental protection and economic benefits.

[0028] In an embodiment, the reducing agent storage and supply system 8 includes a multi-stage centrifugal pump, a metering pump and a horizontal pump to pressurize and supply the reducing agent. A filtering device is provided at the pump inlet, and the filtering device is a basket filter or a Y-type filter.

[0029] In the embodiment, the reducing agent metering and distribution system 7 is an integral skid-mounted module, including an automatic control ball valve, an automatic control regulating valve and a flow meter; the automatic control ball valve and the electric control ball valve are both electrically or pneumatically controlled, and the flow meter is an electromagnetic flow meter or a float flow meter.

[0030] In the embodiment, the precision injection system 4 includes an injection device, a front NOx / O2 monitoring device 3 and a rear NOx / O2 monitoring device 10. The front NOx / O2 monitoring device 3 and the rear NOx / O2 monitoring device 10 are respectively arranged at the front end and the rear end of the high-efficiency denitrification reactor 5, and the injection device is arranged between the front NOx / O2 monitoring and the high-efficiency denitrification reactor 5. Preferably, the front NOx / O2 monitoring device 3 and the rear NOx / O2 monitoring device 10 can withstand a high temperature of 1000°C. Preferably, the injection device is a compressed air atomization device, and the injection device is provided with a nozzle made of silicon carbide to ensure the service life and wear and corrosion resistance of the nozzle. Preferably, the main body of the injection device is made of SS304 material to ensure the service life of the injection device. More preferably, the front temperature testing device is arranged at the front end of the front NOx / O2 monitoring device 3, and at least 3 temperature measuring points are set; in this embodiment, 4 temperature measuring points are set, which are evenly distributed at four different positions of the flue gas duct.

[0031] In this embodiment, the flue gas residence time within the high-efficiency denitration reactor 5 is 1.5s-2s; the high-efficiency denitration reactor 5 is a cyclone separator; and an outer protective plate and a high-temperature casting material layer are provided on the outside of the high-efficiency denitration reactor 5. The thickness of the outer protective plate is 6-10mm. Preferably, in this embodiment, the thickness of the outer protective plate is 8mm, which improves the thermal insulation effect and also provides a heat insulation function.

[0032] In this embodiment, a dust removal and desulfurization device 9 is provided between the high-efficiency denitration reactor 5 and the tail oxidation denitration system. The tail oxidation denitration system includes an oxidation denitration device, the operation of which is controlled by a controller based on test data from a post-mounted NOx / O2 monitoring device 10 and a CEMS device 17. The CEMS device 17 is mounted on a chimney 16. Preferably, the oxidation denitration device includes a plate heat exchanger 11, an air compressor system 13, and an ozone generator 12. The plate heat exchanger 11 dissipates heat for the ozone generator 12, and the air compressor dilutes the pure oxygen used by the ozone generator 12, providing an oxygen source. A dedicated power distribution control cabinet 14 is also provided to ensure that the ozone generator 12 produces ozone.

[0033] During use, the pre-temperature testing equipment is used to monitor the data before the flue gas enters the high-efficiency denitrification reactor 5, and transmits the temperature information to the control system 6. The control system 6 automatically controls the operation of the precise ammonia injection system or the oxidation denitrification system set at the tail according to the temperature information. When the monitored temperature is higher than 750°C, the control system 6 automatically controls the operation of the precise ammonia injection system, and sprays ammonia water into the flue gas before the flue gas enters the high-efficiency denitrification reactor 5. The ammonia water is evenly mixed with the flue gas in the flue and enters the high-efficiency denitrification reactor 5 for reaction and denitrification. After dust removal and desulfurization by the dust removal and desulfurization device 9, the flue gas is monitored by the post-NOx / O2 monitoring device 10, and then passes through the spray alkali washing tower 15 for alkaline washing and then discharged through the chimney 16; when the monitored temperature is lower than 750°C, the controller automatically controls the operation of the oxidation denitrification system, and sprays ozone before the spray alkali washing tower 15 for alkaline washing, so that denitrification meets the emission standards, and the emission data is monitored in real time; thereby solving the problem of high operating costs of other denitrification schemes, thereby reducing the flue gas treatment cost.

[0034] The utility model effectively overcomes the disadvantages of high operating costs of the flue gas of the smelting kiln, such as the complexity of the flue gas of the smelting kiln and the inability to carry out conventional SCR denitrification, such as the use of low-temperature denitrification or single oxidation denitrification. When the flue gas temperature is higher than 750°C, denitrification is carried out by a high-efficiency and precise denitrification system. When the flue gas temperature is less than 750°C, the tail oxidation device is supplemented to ensure that the pollutants in the enterprise's smelting kiln are discharged in a long-term and stable manner in the normal production and meet the emission standards, and simultaneously achieve a significant saving in the system operation cost and simultaneously complete the maximization of the environmental protection benefits and economic benefits of the relevant enterprises.

[0035] Example 2

[0036] A precise and efficient denitrification device for smelting furnace flue gas 1 includes a reducing agent storage and supply system 8, a reducing agent metering and distribution system 7, a precise injection system 4, a high-efficiency denitrification reactor 5, and a tail oxidation denitrification system. After exiting the furnace, the high-temperature flue gas is tested by a pre-temperature testing device 2. If the flue gas temperature exceeds 750°C, the precise and efficient denitrification device is activated under the control of the control system, and the reducing agent is sprayed into the flue gas. Under the action of the high-efficiency denitrification reactor 5, the flue gas and the reducing agent undergo a thorough mixing reaction, thus completing denitrification. If the test temperature is below 750°C, the precise and efficient denitrification device stops injecting the reducing agent, and denitrification is carried out by the tail oxidation denitrification device. This ensures that the NOx in the entire flue gas is continuously and stably discharged in compliance with emission standards, significantly saving the enterprise's operating costs and creating economic benefits.

[0037] The reducing agent is stored and supplied via the reducing agent storage and supply system 8. The reducing agent is pressurized and supplied using a multi-stage centrifugal pump, a metering pump, and a horizontal pump. A filter device, preferably a basket filter, is required before the pump. If the reducing agent supply system is used to supply multiple smelting kilns, a multi-stage centrifugal pump is preferred. If the reducing agent supply system is used to supply one smelting kiln, a metering pump is preferred.

[0038] The reductant metering and distribution system 7 is a skid-mounted module that includes an automatic control ball valve, an automatic control regulating valve, and a flow meter. Both the automatic control ball valve and the electric control ball valve are electrically controlled, and the flow meter can be a float flow meter. If explosion-proof requirements are met, pneumatic control valves are preferred. If not, both electric and pneumatic control valves are acceptable.

[0039] The precision injection system 4 includes an injection device, a pre-mounted NOx / O2 monitoring device 3, a pre-mounted temperature test device 2, and a post-mounted NOx / O2 monitoring device 10. The injection device can utilize a mechanical atomizer, with the main body made of SS316 and the nozzle made of Hastelloy. This system is recommended for use with a two-stage atomizing spray gun, where over 90% of the atomization occurs at the rear of the gun, leaving only 10% at the nozzle. This significantly improves system reliability.

[0040] The pre-NOx / O2 monitoring equipment 3 and post-NOx / O2 monitoring equipment 10 are primarily used to monitor the NOx concentration in the raw and treated flue gas, controlling the amount of reducing agent used and significantly impacting the overall system operating costs. These monitoring equipment are located at the inlet and outlet of the high-efficiency denitrification reactor 5. During operation of the precise and efficient denitrification system, flue gas temperatures can reach as high as 1000°C. Therefore, the relevant testing equipment must be able to withstand temperatures of 1000°C to ensure operational stability.

[0041] The pre-temperature test equipment is arranged before the high-efficiency denitrification reactor 5. It is the starting condition for whether the precise and high-efficiency denitrification device is put into operation, so its accuracy is very important. In order to ensure the accuracy of temperature measurement, more than 3 temperature measurement points need to be arranged. Generally, 3 measurement points are arranged, and the data is in the form of 2 out of 3.

[0042] The high-efficiency denitrification reactor 5 is a core component of a precise and efficient denitrification device for smelting furnace flue gas 1. It provides a place for the full mixing and reaction of the reducing agent and the flue gas, can ensure the full mixing of the reducing agent and the flue gas, and needs to ensure that the residence time of the flue gas is 1.5s-2s.

[0043] The high-efficiency denitration reactor 5 can be a cyclone separator or a mixer. Based on previous experience in boiler flue gas denitration, the high-efficiency denitration reactor in this embodiment generally adopts a cyclone separator, which is more conducive to improving the efficiency of denitration.

[0044] The high-efficiency denitrification reactor 5 is generally constructed by adding an outer protective plate and high-temperature casting materials. The outer protective plate can be made of carbon steel. According to the processing scale, the thickness of the outer protective plate is 10 mm.

[0045] Due to the cyclical problem of smelting, the smelting flue gas also has cyclical characteristics. When the flue gas temperature is lower than 750℃, in order to ensure stable and long-term emission of NOx that meets the standards, it is necessary to install an oxidation denitrification device after the original flue gas desulfurization and dust removal device. The oxidation denitrification device generally adopts the ozone oxidation method. Its operation mode is flexible and can be put into operation and withdrawn at any time. The ozone oxidation denitrification device includes an ozone generator 12, an air compressor system 13, a dedicated distribution cabinet, a plate heat exchanger 11 and a spray alkali washing tower 15.

[0046] The operation of the oxidation denitrification device is controlled based on the test data of the post-NOx / O2 monitoring equipment 10 and the CEMS device 17, ensuring that environmental protection standards are met while minimizing operating costs.

[0047] The above is a preferred embodiment of the present invention and the technical principles used therein. For those skilled in the art, any obvious changes such as equivalent transformations, simple replacements, etc. based on the technical solution of the present invention, without departing from the spirit and scope of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A precise and efficient denitrification device for smelting furnace flue gas, comprising a reducing agent storage and supply system, a high-efficiency denitrification reactor, and a tail oxidation denitrification system, characterized by: The front end of the high-efficiency denitrification reactor is provided with a precision injection system, which is connected to the reducing agent metering and distribution system through a pipeline, and the reducing agent metering and distribution system is connected to the reducing agent storage and supply system through a pipeline. The rear end of the high-efficiency denitrification reactor is provided with a tail oxidation denitrification system, and the rear end of the tail oxidation denitrification system is provided with a spray alkali washing tower; the entire system is controlled by the control system, and the front end of the high-efficiency denitrification reactor is provided with a front temperature testing device.

2. The precise and efficient denitrification device for smelting furnace flue gas according to claim 1 is characterized by: The reducing agent storage and supply system includes a multi-stage centrifugal pump, a metering pump and a horizontal pump to pressurize the reducing agent. A filtering device is provided at the pump inlet, and the filtering device is a basket filter or a Y-type filter.

3. The precise and efficient denitrification device for smelting furnace flue gas according to claim 1 is characterized by: The reducing agent metering and distribution system is an integral skid-mounted module, including an automatic control ball valve, an automatic control regulating valve and a flow meter; the automatic control ball valve and the electric control ball valve are both electrically or pneumatically controlled, and the flow meter is an electromagnetic flow meter or a float flow meter.

4. The precise and efficient denitrification device for smelting furnace flue gas according to claim 1 is characterized in that: The precise injection system includes an injection device, a front NOx / O2 monitoring device and a rear NOx / O2 monitoring device. The front NOx / O2 monitoring device and the rear NOx / O2 monitoring device are respectively arranged at the front end and the rear end of the high-efficiency denitrification reactor, and the injection device is arranged between the front NOx / O2 monitoring and the high-efficiency denitrification reactor.

5. The precise and efficient denitrification device for smelting furnace flue gas according to claim 4 is characterized in that: The spraying device is a mechanical atomizing device or a compressed air atomizing device, and a nozzle made of silicon carbide or Hastelloy is provided on the spraying device.

6. The precise and efficient denitrification device for smelting furnace flue gas according to claim 1 is characterized by: The front temperature testing device is arranged at the front end of the front NOx / O2 monitoring device and is provided with at least three temperature measuring points.

7. The precise and efficient denitrification device for smelting furnace flue gas according to claim 1 is characterized by: The residence time of the flue gas in the high-efficiency denitration reactor is 1.5s-2s; the high-efficiency denitration reactor is a cyclone separator type or a mixer type.

8. The precise and efficient denitrification device for smelting furnace flue gas according to claim 7, characterized in that: An outer protective plate and a high-temperature casting material layer are provided on the outside of the high-efficiency denitrification reactor, and the thickness of the outer protective plate is 6-10 mm.

9. The precise and efficient denitrification device for smelting furnace flue gas according to claim 7, characterized in that: A dust removal and desulfurization device is provided between the high-efficiency denitrification reactor and the tail oxidation denitrification system; the tail oxidation denitrification system includes an oxidation denitrification device, and the operation of the oxidation denitrification device is controlled by a controller according to the test data of the post-NOx / O2 monitoring equipment and the CEMS device, and the CEMS device is arranged on the chimney.

10. The precise and efficient denitrification device for smelting furnace flue gas according to claim 9, characterized in that: The oxidation denitrification device includes a plate heat exchanger, an air compressor system and an ozone generator. The plate heat exchanger dissipates heat for the ozone generator, and the air compressor dilutes the pure oxygen used by the ozone generator to provide an oxygen source.

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