Co-processing system for carbon monoxide and nitrogen oxide in sintering flue gas

Abstract

The utility model relates to a flue gas purification technology, and particularly discloses a sintering flue gas carbon monoxide and nitrogen oxide cooperative treatment system which comprises a GGH, a CO removal device, an SCR denitration device and a waste heat recovery device, and the CO removal device and the SCR denitration device are sequentially connected through a pipeline in the flue gas flowing direction; the waste heat recovery device comprises an energy conversion device, an adjusting piece and a bypass flue, the adjusting piece comprises a first adjusting valve, a second adjusting valve and a third adjusting valve, and the two ends, extending in the flue gas flowing direction, of the bypass flue communicate with a gas inlet pipeline and a gas outlet pipeline of the energy conversion device in a one-to-one correspondence mode. The first regulating valve is arranged on a gas inlet pipeline of the energy conversion device, the second regulating valve is arranged on a gas outlet pipeline of the energy conversion device, and the third regulating valve is arranged on the bypass flue. The waste heat recovery device has the advantage of sufficient waste heat recovery.

Description

TECHNICAL FIELD

[0001] The present application relates to the industrial flue gas purification technology, and particularly relates to a sintering flue gas carbon monoxide and nitrogen oxide collaborative treatment system. BACKGROUND

[0002] CO is widely emitted from almost all combustion devices, and the content of CO in sintering flue gas is as high as 6000-10000 mg / Nm 3 , which is one of the main CO emission sources in steel enterprises. The removal of CO in sintering flue gas has attracted more and more attention and emphasis. At present, the main way of CO removal in flue gas is to use a catalyst to oxidize CO into CO2, and a large amount of heat will be released in the process. Making full use of the heat released by CO removal can help save energy and reduce consumption and save operation cost.

[0003] The sintering SCR denitration is generally arranged after desulfurization and dust removal, and the operation temperature is 280℃. After desulfurization and dust removal, the flue gas temperature is 80-100℃. In order to meet the requirement of the operation temperature of denitration, a GGH and a heating furnace are configured. The flue gas needs to be heated by about 30℃ for SCR denitration. When 1000 mg / Nm 3 of CO in flue gas is removed, the flue gas can be increased by about 7℃. If the heat of CO removal can be fully utilized, not only the coal gas required for heating flue gas by SCR can be saved, but also a part of it can be recycled.

[0004] The prior art discloses a sintering flue gas CO removal system and method, which comprises a semi-dry desulfurization process reactor, a GGH heat exchanger, a noble metal catalyst oxidation reactor, a hot blast furnace and an SCR reactor connected in sequence. When the CO concentration is high, the flue gas temperature after CO catalytic oxidation is higher than 200℃. The flue gas enters the heat exchanger to generate steam. By adjusting the steam production, the outlet flue gas temperature is controlled to keep the flue gas temperature at 200℃, and the flue gas enters the SCR denitration. When the CO concentration of the flue gas is just right to make the flue gas temperature after CO catalytic oxidation equal to 200℃, the flue gas enters the heat exchanger, the oxygen removal water valve of the heat exchanger is closed, and the heat exchange is stopped. When the CO concentration of the flue gas is low, the flue gas temperature after CO catalytic oxidation is still lower than 200℃. The flue gas enters the hot blast furnace, and is further heated to 200℃ by the hot blast furnace to enter the SCR reactor for denitration.

[0005] The technology sets a heat exchanger between the GGH raw flue gas outlet and the SCR reactor, adjusts the flue gas temperature entering the SCR reactor by adjusting the steam output, the adjustment mode responds slowly, the temperature adjustment range is limited, when the temperature needs to be adjusted, the steam quality produced by the heat exchanger cannot be stable. When the temperature is 200℃, the deoxygenated water of the heat exchanger is closed, the heating is stopped, and the heat exchanger is only used as a flue, which affects the service life of the heat exchanger when used for a long time. When the temperature is higher than 200℃, the flue gas has waste heat recovery before entering the SCR reactor, which does not fully utilize the characteristics that the activity of the catalyst increases with the increase of the temperature, and when the NO X The emission value is difficult to control when there is fluctuation. Practical new type content

[0006] In order to solve the problem that the waste heat recovery is not reasonable, the application provides a sintering flue gas carbon monoxide and nitrogen oxide collaborative treatment system.

[0007] The application provides a sintering flue gas carbon monoxide and nitrogen oxide collaborative treatment system, which adopts the following technical scheme:

[0008] A sintering flue gas carbon monoxide and nitrogen oxide collaborative treatment system, comprising a GGH, a CO removal device, an SCR denitration device and a waste heat recovery device, the CO removal device and the SCR denitration device are connected in sequence along the flue gas flow direction; the waste heat recovery device comprises an energy conversion device, an adjusting part and a bypass flue, the adjusting part comprises a first adjusting valve, a second adjusting valve and a third adjusting valve, the two ends of the bypass flue extending along the flue gas flow direction are respectively in one-to-one correspondence with the gas inlet pipe and the gas outlet pipe of the energy conversion device, the first adjusting valve is arranged on the gas inlet pipe of the energy conversion device, the second adjusting valve is arranged on the gas outlet pipe of the energy conversion device, and the third adjusting valve is arranged on the bypass flue; the flue gas to be treated flows into the GGH from the raw flue gas inlet of the GGH, the raw flue gas outlet of the GGH is communicated with the gas inlet of the CO removal device, and the net flue gas inlet of the GGH is communicated with the gas outlet of the SCR denitration device through the bypass flue.

[0009] By adopting the above technical scheme, the flue gas to be treated flows into the GGH from the raw flue gas inlet of the GGH, exchanges heat with the net flue gas, the temperature of the flue gas is raised, then enters the CO removal device, and the released heat raises the temperature of the flue gas, and then the flue gas enters the SCR denitration device to remove NO XThe waste heat recovery device is arranged behind the SCR denitration device, the flue gas amount passing through the energy conversion device and the bypass flue is adjusted according to the flue gas temperature at the net flue gas inlet of the GGH, part of the flue gas enters the energy conversion device through the first adjusting valve, and the flue gas after waste heat recovery is discharged through the second adjusting valve. Part of the flue gas passes through the third adjusting valve, and then is mixed with the flue gas discharged from the energy conversion device and enters the GGH through the net flue gas inlet of the GGH, and then exchanges heat with the original flue gas at the net flue gas side to heat the original flue gas, and then is discharged through the net flue gas outlet of the GGH.

[0010] Therefore, the above waste heat recovery device is arranged between the SCR denitration device and the net flue gas inlet of the GGH, on the one hand, the characteristics that the activity of the denitration catalyst increases with the increase of the temperature are fully utilized, the NO X is removed at a high temperature, and then the waste heat is recovered; on the other hand, the flue gas after waste heat recovery enters the net flue gas side of the GGH, so that the fluctuation of the CO concentration can be coped with, the temperature at the net flue gas inlet of the GGH is stabilized, the waste heat utilization is maximized, and the jamming of the GGH caused by the excessively high temperature is avoided, thereby affecting the system operation.

[0011] Preferably, the heating device is arranged behind the CO removal device.

[0012] By adopting the above technical scheme, as a specific structural example, the heating device is arranged behind the CO removal device, and is used when the flue gas temperature after CO removal is insufficient to reach the SCR denitration temperature.

[0013] Preferably, the heating device is a direct-fired furnace with an internal flue, and the internal flue of the heating device is in communication with the gas inlet of the SCR denitration device and the gas outlet of the CO removal device respectively.

[0014] By adopting the above technical scheme, as a specific structural example, the heating device is in the form of a direct-fired furnace with an internal flue, and the switching of the heating device only needs to stop the gas supply, so that the switching is convenient.

[0015] Preferably, the heating device is a direct-fired furnace with an internal flue, and the internal flue of the heating device is in communication with the gas inlet of the SCR denitration device and the gas outlet of the CO removal device respectively.

[0016] By adopting the above technical scheme, as a specific structural example, the flue gas enters the ammonia injection device, and the ammonia injection device is used to inject ammonia into the flue gas to meet the needs of subsequent removal of NO x .

[0017] Preferably, the system further comprises a fan and a chimney, the net flue gas outlet of the GGH is communicated with the air inlet of the fan, and the air outlet of the fan is connected with the chimney through a pipeline.

[0018] By using the above technical scheme, as a structural example, the flue gas after heat exchange in the GGH is discharged to the outside by using the fan and the chimney.

[0019] Preferably, the energy conversion device is a steam generator.

[0020] By using the above technical scheme, as a structural example, the energy conversion device uses a steam generator to convert the waste heat into steam and then realize recycling.

[0021] In summary, the present application has at least the following beneficial effects:

[0022] The sintering flue gas carbon monoxide and nitrogen oxide collaborative treatment system of the present application, the CO removal device is coupled with the SCR denitration device, and the waste heat recovery device is arranged after the SCR denitration device. X The efficient removal is completed at a high temperature, and then the waste heat is recovered; on the other hand, the waste heat recovery device of the present application can better adapt to the change of the flue gas temperature, so that the flue gas temperature at the net flue gas inlet of the GGH can be maintained within a preset temperature range (for example, 200 DEG C or 280 DEG C), and the waste heat is fully recovered and utilized on the basis of meeting the denitration requirement. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic diagram of the sintering flue gas carbon monoxide and nitrogen oxide collaborative treatment system of the embodiment of the present application.

[0024] Label explanation:

[0025] 1, GGH; 2, CO removal device; 3, SCR denitration device; 41, energy conversion device; 42, bypass flue; 43, first regulating valve; 44, second regulating valve; 45, third regulating valve; 5, heating device; 6, ammonia injection device; 7, fan; 8, chimney. DETAILED DESCRIPTION

[0026] Although the present application can be easily embodied in different forms of embodiments, only some specific embodiments are shown in the drawings and will be described in detail in the present specification, and it can be understood that the present specification should be regarded as a demonstrative description of the principles of the present application, and is not intended to limit the present application to that described herein.

[0027] Thus, one feature that is described in the specification will be used to illustrate one feature of one embodiment of the application, and is not meant to imply that every embodiment of the application must have the described feature. Furthermore, it should be noted that the specification describes many features. Although certain features can be combined in one embodiment, these features can also be used in other embodiments that do not explicitly combine these features. Thus, unless otherwise noted, the combination of features is not intended to limit the application.

[0028] In the embodiments shown in the drawings, the indications of direction, such as up, down, left, right, front and back, are used to explain the structure and movement of various elements of the application are not absolute but relative. These indications are appropriate when the elements are in the position shown in the drawings. If the position of the elements changes, the indications of direction also change accordingly.

[0029] The application is further described in detail below with reference to the drawings and embodiments.

[0030] Word meaning explanation:

[0031] GGH: is the abbreviation of Gas Gas Heater, i.e. flue gas heat exchanger.

[0032] SCR: is the abbreviation of Selective Catalytic Reduction, i.e. selective catalytic reduction.

[0033] Embodiment 1

[0034] According to one embodiment shown in the present embodiment, it can be seen from Figure 1 , throughout the view, the same reference signs represent corresponding parts. It should be understood that the sintering flue gas carbon monoxide and nitrogen oxides co-processing system according to the present application can be used in all flue gas purification equipment that needs to process CO and NO X .

[0035] As Figure 1 shown, the sintering flue gas carbon monoxide and nitrogen oxides co-processing system of the present embodiment includes GGH1, CO removal device 2, SCR denitration device 3, waste heat recovery device, heating device 5, ammonia injection device 6, induced draft device 7 and chimney 8, the waste heat recovery device includes energy conversion device 41, adjusting piece and bypass flue 42, the adjusting piece includes first adjusting valve 43, second adjusting valve 44, third adjusting valve 45.

[0036] In this embodiment, the CO removal device 2 is a CO catalytic oxidation reactor, the GGH 1 is a rotary GGH, the induced draft device 7 is an induced draft fan, the ammonia injection device 6 is an ammonia injection grid, the heating device 5 is a direct-fired furnace with an internal flue, and the energy conversion device 41 is a steam generator (i.e., a boiler). The first regulating valve 43, the second regulating valve 44, and the third regulating valve 45 are all conventional gas flow control valves.

[0037] Referring to Figure 1 , in the direction of flue gas flow (i.e., the direction indicated by the arrow in the figure), the original flue side of the GGH 1, the CO removal device 2, the heating device 5, the ammonia injection device 6, the SCR denitration device 3, the waste heat recovery device, the clean flue side of the GGH 1, the induced draft device 7, and the chimney 8 are sequentially connected by pipelines. Specifically, the flue gas to be treated after desulfurization and dust removal flows into the original flue gas inlet of the GGH 1. The original flue gas outlet of the GGH 1 is connected to the gas inlet of the CO removal device 2. One end of the internal flue of the heating device 5 is connected to the gas outlet of the CO removal device 2, and the other end is connected to the gas inlet of the ammonia injection device 6. The gas outlet of the ammonia injection device 6 is connected to the gas inlet of the SCR denitration device 3. The gas outlet of the SCR denitration device 3 is connected to the clean flue gas inlet of the GGH 1 via the waste heat recovery device. The clean flue gas outlet of the GGH 1 is connected to the induced draft device 7 by a pipeline. The induced draft device 7 is connected to the chimney 8 by a pipeline. The flue gas is discharged to the outside through the chimney 8.

[0038] In the waste heat recovery device of this embodiment, the bypass flue 42 extends in the direction of flue gas flow. One end of the bypass flue 42 is connected to the gas outlet of the SCR denitration device 3, and the other end is connected to the clean flue gas inlet of the GGH 1. An inlet pipeline is connected to the gas inlet of the steam generator, and an outlet pipeline is connected to the gas outlet of the steam generator. One end of the bypass flue 42 is connected to the inlet pipeline of the steam generator, and the other end is connected to the outlet pipeline of the steam generator. The first regulating valve 43 is arranged on the inlet pipeline of the steam generator, the second regulating valve 44 is arranged on the outlet pipeline of the steam generator, and the third regulating valve 45 is arranged on the bypass flue 42.

[0039] Based on the above structural description, the embodiment is specifically described as follows:

[0040] Referring to Figure 1, the flue gas temperature after desulfurization and dust removal is 50-100℃, the flue gas is heated to about 250℃ by GGH1 and the clean flue gas, then enters CO removal device 2 to remove CO by oxidation, and heat is released during the oxidation removal process. The released heat increases the flue gas temperature, and due to the change of CO concentration, the flue gas temperature after CO removal also changes. In order to deal with the situation of insufficient flue gas temperature, heating device 5 is arranged after CO removal device 2. If the temperature is still less than 280℃, heating device 5 is started to supplement heat, so that the flue gas temperature is not less than 280℃, so that the SCR denitrification reaction can proceed normally. After the flue gas temperature after denitrification meets the requirement, ammonia is injected into the flue gas through ammonia injection device 6, and then the flue gas enters SCR denitrification device 3 to remove NO X , the waste heat recovery device is arranged after SCR denitrification device 3. According to the flue gas temperature at the clean flue gas inlet of GGH1, the flue gas amount passing through the steam generator and bypass flue 42 is adjusted. The flue gas is mainly adjusted by the third adjusting valve 45 arranged in the bypass flue 42. Part of the flue gas enters the steam generator through the first adjusting valve 43, and the flue gas after waste heat recovery is discharged through the second adjusting valve 44. Part of the flue gas passes through the third adjusting valve 45, and then enters GGH1 after being combined with the flue gas discharged from the steam generator. The flue gas is heated by heat exchange with the original flue gas at the clean flue gas side. After heat exchange, the flue gas is discharged to the chimney 8 through the induced draft device 7, and finally discharged to the outside. The opening of the first adjusting valve 43, the second adjusting valve 44 and the third adjusting valve 45 is adjusted according to the outlet temperature of the SCR denitrification device 3.

[0041] Through the above flue gas process, the CO removal and SCR denitrification of the present embodiment are coupled, which can maximize the benefits of pollutant removal and waste heat recovery. First, CO oxidation removal heats the flue gas temperature. When the CO concentration is sufficient, the SCR denitrification device 3 does not need to consume coal gas to heat the flue gas. However, in order to deal with the situation of insufficient CO concentration, heating device 5 is still arranged before ammonia injection device 6. When the CO removal temperature is less than 280℃, the flue gas temperature is heated to meet the denitrification requirement. When the heat required for normal operation of the SCR denitrification device 3 is exceeded, the steam generator is arranged after the SCR denitrification device 3, and adjusting parts are arranged to adapt to the change of the flue gas temperature, so that the flue gas temperature at the clean flue gas inlet of GGH1 is maintained at about 280℃. On the basis of meeting the denitrification requirement, the waste heat is fully recovered and utilized.

[0042] The sintering flue gas carbon monoxide and nitrogen oxide collaborative treatment system of the present embodiment has the following advantages:

[0043] (1) The waste heat recovery device is arranged between the SCR denitrification device 3 and the clean flue gas inlet of GGH1, which fully utilizes the characteristics that the activity of the denitrification catalyst increases with the increase of the temperature, and the NO X is removed efficiently at a higher temperature, and then the waste heat is recovered.

[0044] (2) The CO removal device 2 is arranged before the SCR denitration device 3, and the heat generated by the oxidation removal of CO can replace or partially replace the coal gas for heating flue gas, so that the heat required for the SCR denitration reaction is provided, and when the CO content is high, the traditional coal gas used for sintering SCR denitration can be completely replaced, and zero coal gas consumption of the SCR denitration is realized;

[0045] (3) A direct combustion furnace is arranged after the CO removal device 3, and when the flue gas temperature after the removal of CO is insufficient to reach the required temperature of the SCR denitration, the direct combustion furnace can be used for heat supplement;

[0046] (4) The waste heat recovery device has simple and reasonable structure design, convenient temperature adjustment, can better adapt to the change of the CO concentration, ensures that the inlet temperature of the flue gas of the GGH 1 is kept at the required temperature, the waste heat utilization is maximized, and meanwhile, the jamming caused by the too high temperature of the GGH 1 and the influence on the system operation are avoided.

[0047] The specific embodiments are only an explanation of the application, and are not a limitation of the application, and the person skilled in the art can make a modification of the embodiments without creative contribution according to the needs after reading the specification, and as long as the modification is within the scope of the claims of the application, it is protected by the patent law.

Claims

1. A system for the simultaneous treatment of carbon monoxide and nitrogen oxides in sintering off-gas, characterized in that, The device comprises a GGH, a CO removal device, an SCR denitration device and a waste heat recovery device, the CO removal device and the SCR denitration device are connected in sequence along the flow direction of flue gas. The waste heat recovery device comprises an energy conversion device, an adjusting member and a bypass flue, the adjusting member comprises a first adjusting valve, a second adjusting valve and a third adjusting valve, the two ends of the bypass flue extending along the flow direction of flue gas are respectively connected with the inlet pipe and the outlet pipe of the energy conversion device, the first adjusting valve is arranged on the inlet pipe of the energy conversion device, the second adjusting valve is arranged on the outlet pipe of the energy conversion device, and the third adjusting valve is arranged on the bypass flue. The flue gas to be treated flows into the GGH from the original flue gas inlet, the original flue gas outlet of the GGH is communicated with the gas inlet of the CO removal device, and the clean flue gas inlet of the GGH is communicated with the gas outlet of the SCR denitration device through the bypass flue.

2. The sintering flue gas CO and NOx co-treatment system according to claim 1, characterized in that, The device further comprises a heating device, which is used for heating the flue gas to be treated at the gas outlet of the CO removal device.

3. The sinter plant flue gas CO and NOx co-treatment system according to claim 2, characterized in that, The heating device is a direct-fired furnace with an internal flue, and the internal flue of the heating device is communicated with the gas inlet of the SCR denitration device and the gas outlet of the CO removal device respectively.

4. The sintering off-gas CO and NOx co-treatment system according to claim 3, characterized in that, The device further comprises an ammonia injection device, the gas inlet of the ammonia injection device is communicated with the gas outlet of the internal flue of the heating device, and the gas outlet of the ammonia injection device is communicated with the gas inlet of the SCR denitration device.

5. The sintering flue gas CO and NOx co-treatment system according to claim 1, characterized in that, The device further comprises an induced draft device and a chimney, the clean flue gas outlet of the GGH is communicated with the gas inlet of the induced draft device, and the gas outlet of the induced draft device is connected with the chimney through a pipe.

6. The sintering flue gas CO and NOx co-treatment system according to claim 1, characterized in that, The energy conversion device is a steam generator.

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