Denitration, dust removal and waste heat recovery integrated system for cement kiln

Abstract

The utility model discloses a denitration, dust removal and waste heat recovery integrated system for a cement kiln. Comprising a preheater (2) and a dust, nitrate and waste heat recovery integrated device (9), an inlet of the preheater (2) is connected with an outlet flue of a rotary kiln (1), and the dust, nitrate and waste heat recovery integrated device (9) sequentially comprises a dust removal unit (901), a denitration unit (902) and a waste heat recovery unit (903) from bottom to top; an inlet flue at the lower part of the dust nitrate waste heat recovery integrated device (9) is connected with an outlet flue of the preheater (2); an outlet of the preheater (2) is connected with the ammonia water spraying device (5); an emergency cooling device (6) and a flue gas heater (8) are further arranged on an outlet flue of the preheater (2); and a humidifying and cooling device (11) is arranged at an outlet flue of the dust nitrate waste heat recovery integrated device (9). According to the utility model, the lengths of a connecting flue and an external flue between equipment are effectively reduced, the resistance of a system is reduced, the temperature loss is reduced, and the occupied area and the construction cost are saved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to cement industry kiln tail flue gas treatment technical field, concretely relates to a cement kiln denitration dust removal and waste heat recovery integrated system. BACKGROUND

[0002] Cement industry is the main nitrogen oxides (NOx) emission source in China, traditional cement kiln adopts low nitrogen combustion and selective non catalytic reduction denitration (SNCR) technology, can reduce NOx emission in a certain extent, but along with the environmental protection standard day by day strict, existing technology cannot satisfy the requirement of ultra low emission.

[0003] Selective catalytic reduction denitration (SCR) technology is an effective technology that can effectively reduce the NOx content in flue gas, and has been widely used in power, steel and chemical industry and other industries; the application of SCR technology in cement industry can effectively reduce the NOx in kiln tail flue gas.

[0004] But the cement kiln tail flue gas has the following characteristics: high temperature, generally up to 320~400℃; dust content is large, generally concentration can reach 80~120g / Nm 3 ; Part of the cement kiln takes into account the synergistic treatment of garbage, resulting in complex flue gas composition and high heavy metal content; severe operating conditions pose a serious test to the stable operation of SCR.

[0005] Traditional high temperature high dust SCR denitration technology, the dust content in the flue is large, which will cause the wear and blockage of the catalyst, and the heavy metals contained in the dust of the cement kiln will accelerate the poisoning and deactivation of the catalyst. And the reactor is independently arranged, causing the reactor inlet and outlet flue to be long, which is inconvenient to arrange and has large heat loss, affecting the heat recovery effect of the boiler.

[0006] Traditional high temperature medium dust SCR denitration technology, the dust remover, denitration reactor and waste heat boiler are arranged separately, which occupies a large area, and it is difficult to reform the old cement kiln production line, and the investment cost is also large. SUMMARY

[0007] The utility model provides a cement kiln denitration dust removal and waste heat recovery integrated system aiming at the deficiency of prior art.

[0008] The technical solution of the utility model is: a cement kiln denitration dust removal and waste heat recovery integrated system, including preheater, dust and nitre waste heat recovery integrated device, the inlet of preheater is connected with the outlet flue of rotary kiln, the inside of dust and nitre waste heat recovery integrated device includes dust removal unit, denitration unit, waste heat recovery unit from bottom to top successively, the lower part of dust and nitre waste heat recovery integrated device is provided with inlet flue, and the upper part is provided with outlet flue, the inlet flue of lower part of dust and nitre waste heat recovery integrated device is connected with the outlet flue of preheater, the outlet of preheater is connected with ammonia water injection device, and the outlet flue of preheater is also provided with emergency cooling device and flue gas heater, and the outlet flue of dust and nitre waste heat recovery integrated device is provided with humidification cooling device.

[0009] Further, the dust removal unit includes a corona electrode, a dust collection electrode, a dust hopper, and a water bath type dust conveying machine; the dust collection electrode has an anode plate, and the corona electrode has a cathode wire; the corona electrode and the dust collection electrode are connected with a high-voltage power supply, and impact vibration dust removal is adopted.

[0010] Further, the denitration unit includes a catalyst layer, and the catalyst layer includes a denitration catalyst and a supporting steel structure; each catalyst layer is provided with multiple rake-type soot blowers and acoustic soot blowers.

[0011] Further, the waste heat recovery unit includes a heat exchange unit composed of multiple groups of tubes.

[0012] Further, the rake-type soot blower is provided with multiple nozzles on the rake rod, and the aperture is 2-3 mm; the distance from the nozzle of the rake-type soot blower to the surface of the catalyst is not greater than 120 mm; and the rake-type soot blower is connected with an air compression station.

[0013] Further, the humidification cooling device is connected with a process water pump and a process water tank.

[0014] Further, the outlet flue of the dust and nitre waste heat recovery integrated device is connected with a high-temperature fan and a kiln tail bag-type dust collector; the kiln tail bag-type dust collector is connected with a circulating fan and a raw material vertical mill; and the outlet of the kiln tail bag-type dust collector is connected with a kiln tail dust collection fan and a chimney.

[0015] Further, the emergency cooling device is provided with multiple humidification cooling nozzles, which are distributed in a mesh shape; the humidification cooling nozzles adopt double-fluid spray guns, and each group of spray guns is provided with a flow adjusting device.

[0016] Further, the ammonia water injection device is connected with an ammonia water conveying pump and an ammonia water tank; the ammonia water injection device is provided with multiple ammonia water spray guns, and the spray heads are arranged in a mesh shape; the spray heads adopt double-fluid spray guns, and each spray gun is provided with a flow adjusting device.

[0017] The beneficial technical effect of the utility model is: the flue gas enters the dust and denitration waste heat recovery integrated device, the dust content in the flue gas of the denitration unit is effectively reduced through the dust removal unit first, then enters the denitration unit, the blockage of the denitration catalyst is effectively reduced, finally enters the waste heat recovery unit, and the heat is recovered; in the denitration unit, the special dust removal mode can further reduce the risk of catalyst blockage and prolong the service life of the catalyst; the integrated device is composed of the dust removal unit, the denitration unit and the waste heat recovery unit, the three process units adopt a longitudinal combination arrangement mode, effectively reducing the length of the connecting flue and the external flue between the equipment, reducing the resistance of the system, reducing the temperature loss, saving the land occupation and construction cost. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a cement kiln denitration dust removal and waste heat recovery integrated system schematic diagram.

[0019] In the figure: 1-rotary kiln, 2-preheater, 3-ammonia water tank, 4-ammonia water conveying pump, 5-ammonia water injection device, 6-emergency cooling device, 7-air compression station, 8-flue gas heater, 9-dust and denitration waste heat recovery integrated device, 901-dust removal unit, 902-denitration unit, 90201-catalyst layer, 90202-rake type soot blower, 90203-acoustic soot blower, 903-waste heat recovery unit, 10-water bath type ash conveyor, 11-flue humidification and cooling device, 12-process water pump, 13-process water tank, 14-high temperature fan, 15-raw material vertical mill, 16-circulating fan, 17-kiln tail bag type dust collector, 18-kiln tail dust collection fan, 19-chimney. DETAILED DESCRIPTION

[0020] The specific embodiments of the utility model are described in detail below, but it should be understood that the protection scope of the utility model is not limited by the specific embodiments.

[0021] The following briefly describes one or more aspects of the utility model with reference to the drawings to provide a basic understanding of these aspects. These drawings are all simplified schematic diagrams and only show the structures related to the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model and not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the utility model.

[0022] The application relates to a cement kiln denitration dust removal and waste heat recovery integrated system, which comprises a preheater 2 and a dust and denitration waste heat recovery integrated device 9; the inlet of the preheater 2 is connected with the outlet flue of a rotary kiln 1; the dust and denitration waste heat recovery integrated device 9 comprises, from bottom to top, a dust removal unit 901, a denitration unit 902 and a waste heat recovery unit 903; the dust and denitration waste heat recovery integrated device 9 is provided with an inlet flue at the lower part and an outlet flue at the upper part; the inlet flue at the lower part of the dust and denitration waste heat recovery integrated device 9 is connected with the outlet flue of the preheater 2; the outlet of the preheater 2 is connected with an ammonia water spraying device; the outlet flue of the preheater 2 is further provided with an emergency cooling device 6 and a flue gas heater 8; and the outlet flue of the dust and denitration waste heat recovery integrated device 9 is provided with a humidification and cooling device 11.

[0023] The flue gas from the rotary kiln 1 and the preheater 2 C1 has a temperature of about 320-400 DEG C and contains dust of about 80-120 g / Nm 3； The high-temperature flue gas is communicated with the dust and denitration waste heat recovery integrated device 9 through the C1 outlet flue; the flue gas enters the dust and denitration waste heat recovery integrated device 9 through the inlet flue arranged at the lower part of the device and is discharged through the outlet flue arranged at the top; ammonia water is sprayed into the system as a denitration reducing agent before the dust and denitration waste heat recovery integrated device 9, and an emergency cooling device 6 is arranged on the high-temperature flue gas.

[0024] After the flue gas passes through the dust removal unit 901 in the dust and denitration waste heat recovery integrated device 9, most of the dust is settled into the ash hopper of the dust removal unit 901; the bottom of the ash hopper is further provided with a water bath type ash conveying machine which conveys the dust in the ash hopper back to a raw material bin; the outlet flue of the dust and denitration waste heat recovery integrated device 9 is provided with a humidification and cooling device 11 which can supplement and quickly adjust the outlet flue gas temperature according to the needs of the subsequent process; the flue gas from the dust and denitration waste heat recovery integrated device 9 is conveyed to the rear-end process through a high-temperature fan 14.

[0025] The dust removal unit 901 comprises a corona electrode, a dust collection electrode, an ash hopper and a water bath type ash conveying machine; the dust collection electrode has an anode plate and the corona electrode has a cathode wire; the corona electrode and the dust collection electrode are connected with a high-voltage power supply and adopt impact vibration ash removal; the angle of the ash hopper is greater than 60 DEG.

[0026] The water bath type ash conveying machine comprises an inner shell, an outer shell, a pipeline and a conveying chain; cooling water flows through the middle of the inner shell and the outer shell to cool the conveyed dust.

[0027] The denitration unit 902 comprises a catalyst layer 90201; the catalyst layer 90201 comprises denitration catalysts and a supporting steel structure; each catalyst layer 90201 is provided with multiple rake type soot blowers 90202 and acoustic soot blowers 90203; the number of catalyst layers 90201 in the denitration unit 902 can be one or more according to the content of nitrogen oxides, and a standby layer is reserved; the catalysts are high-temperature catalysts.

[0028] The rake-type soot blower 90202 is provided with a plurality of nozzles with a diameter of 2-3 mm; the distance from the nozzles of the rake-type soot blower 90202 to the surface of the catalyst is not greater than 120 mm; the rake-type soot blower 90202 is connected to the air compression station 7.

[0029] The compressed air used by the rake-type soot blower 90202 is from the air compression station 7, which is provided with an air compressor, a filter, a dryer and the like to ensure that the dew point of the air is lower than -40℃.

[0030] The compressed air used by the rake-type soot blower 90202 needs to be heated to above 200℃ to avoid the formation of water droplets at the nozzles of the rake-type soot blower 90202 due to the use of compressed air for blowing, which may directly damage the catalyst or cause the dust to be hardened and clog the catalyst.

[0031] The rake-type soot blower 90202 is provided with a plurality of soot blowers in a running mode for cooperative blowing: during the travel of the soot blower, blowing is started when going and stopped when returning, while the second soot blower is started to blow, thereby shortening the blowing time interval and strengthening the blowing effect.

[0032] The waste heat recovery unit 903 includes a plurality of groups of heat exchange tubes to recover the heat in the high-temperature flue gas and simultaneously reduce the temperature of the flue gas. The temperature of the flue gas after heat recovery is generally 180-200℃.

[0033] The humidification and cooling device 11 is connected to a process water pump 12 and a process water tank 13.

[0034] The outlet flue of the dust and nitre waste heat recovery integrated device 9 is connected to a high-temperature fan 14 and a kiln tail bag-type dust collector 17; the kiln tail bag-type dust collector 17 is connected to a circulating fan 16 and a raw material vertical mill 15; the outlet of the kiln tail bag-type dust collector 17 is connected to a kiln tail dust collection fan 18 and a chimney 19.

[0035] When the flue gas at the C1 outlet of the preheater 2 exceeds 420℃, the emergency cooling device 6 is automatically started to avoid irreversible damage to the catalyst caused by high-temperature flue gas; the emergency cooling device 6 is provided with a plurality of humidification and cooling nozzles in a net-like distribution; the humidification and cooling nozzles are double-fluid spray guns, each of which is provided with a flow adjusting device.

[0036] The system can automatically adjust each group of spray guns according to the temperature of the flue gas to achieve precise control of the water spraying amount. After the flue gas is cooled to below 400℃ by spraying water, the system automatically stops the water spraying and cooling; at the same time, the spraying of water can promote the reaction of calcium oxide and sulfur dioxide in the dust, thereby achieving a certain desulfurization effect.

[0037] The ammonia water injection device 5 is connected with the ammonia water conveying pump 4 and the ammonia water tank 3; the ammonia water injection device 5 is provided with multiple ammonia water spray guns, and the spray heads are arranged in a mesh shape; the spray heads adopt double-fluid spray guns, and each spray gun is provided with a flow adjusting device.

[0038] The C1 outlet flue of the preheater 2 is provided with the ammonia water injection device 5, the ammonia water injection device 5 is provided with multiple ammonia water spray guns, and the spray heads are arranged in a mesh shape; the ammonia water adopts double-fluid spray guns, and each spray gun is provided with a flow adjusting device; the system can automatically adjust each spray gun according to the total ammonia water injection amount set, realize precise ammonia injection, ensure the relative stability of the flow and pressure at a single nozzle, and ensure the atomization effect.

[0039] The ammonia water comes from an ammonia station, the ammonia station uses 20% ammonia water as a denitration agent, and after the ammonia water is injected into the high-temperature flue, it is rapidly atomized, evaporated and diluted, and the concentration of NH3 is much lower than the explosion limit.

[0040] After the ammonia water spray gun at the C1 outlet flue of the preheater 2, an emergency cooling device 6 is arranged; the emergency cooling device 6 is used when the flue gas is overheated, so that the temperature of the flue gas entering the dust and denitration waste heat recovery integrated device 9 is not higher than 420 DEG C, and damage to the denitration catalyst is avoided.

[0041] The outlet of the dust and denitration waste heat recovery integrated device 9 is provided with a flue humidification and cooling device 11 to adjust the flue gas humidity and control the kiln tail smoke plume, and at the same time, the flue gas temperature can be reduced to ensure that the flue gas temperature at the inlet of the high-temperature fan is not higher than 220 DEG C, and damage to the filter bag of the tail bag-type dust collector is avoided.

[0042] The flue humidification and cooling device 11 is provided with multiple humidification and cooling nozzles, which are distributed in a mesh shape and divide the high-temperature flue into multiple small grids; the emergency cooling device 6 and the flue humidification and cooling device 11 both adopt double-fluid spray guns, and each group of spray guns is provided with a flow adjusting device; the system can automatically adjust the flow of each group of spray guns according to the flue gas temperature, realize precise control of the water injection amount, ensure the relative stability of the flow and pressure at a single nozzle, and avoid the formation of high-concentration dust agglomerates and hardening caused by the failure of water droplets to be atomized in time.

[0043] The flue humidification and cooling device 11 can adjust the flue gas humidity and control the kiln tail smoke plume when it is put into operation; at the same time, the flue gas temperature can be reduced to ensure that the flue gas temperature at the inlet of the high-temperature fan is not higher than 220 DEG C, and damage to the filter bag of the tail bag-type dust collector 17 is avoided.

[0044] The outlet flue of the dust and denitration waste heat recovery integrated device 9 is connected with the high-temperature fan 14 and the kiln tail bag-type dust collector 17; the kiln tail bag-type dust collector 17 is connected with the circulating fan 16 and the raw material vertical mill 15; the outlet of the kiln tail bag-type dust collector 17 is connected with the kiln tail dust collection fan 18 and the chimney 19.

[0045] When the raw material vertical mill 15 is normally put into operation, the high-temperature flue gas passes through the high-temperature fan, then passes through the raw material vertical mill, and then passes through the circulating fan 16, the kiln tail bag dust collector 17, the kiln tail dust collection fan 18 and the chimney 19 in turn to achieve standard emission.

[0046] When the raw material vertical mill 15 is stopped, the raw material vertical mill bypass valve is opened, and the high-temperature flue gas directly passes through the kiln tail bag dust collector 17, the kiln tail dust collection fan 18 and the chimney 19 to achieve standard emission.

[0047] The dust and denitration waste heat recovery integrated device 9 is composed of a dust removal unit 901, a denitration unit 902 and a waste heat recovery unit 903. After the flue gas enters the dust and denitration waste heat recovery integrated device 9, it first passes through the dust removal unit 901. The dust in the flue gas is separated from the gas and collected when the dust passes through the high-voltage electric field between the corona electrode and the dust collection electrode, and the gas is electrified and the particles are charged under the action of the strong electric field force around the corona electrode. The charged particles move to the dust collection electrode under the action of the electric field force and deposit on the dust collection electrode. The dust is removed by hammering or electromagnetic vibration to ensure that the dust does not re-enter the flue gas.

[0048] The falling dust enters the bottom ash hopper and is finally sent back to the raw material bin through the water bath type ash conveying machine. The water bath type ash conveying machine is connected with the circulating cooling water to cool the dust discharged from the ash hopper.

[0049] The dust-removed flue gas enters the denitration unit 902, which can also function as a flue gas rectifier. Under the action of the high-temperature catalyst, the nitrogen oxides in the flue gas react with NH3 to remove most of the nitrogen oxides in the flue gas, ensuring that the flue gas meets the emission standards. According to the concentration of the catalyst, the corresponding number of layers of catalyst is set, and one layer is reserved as a backup.

[0050] Each layer of catalyst is provided with a plurality of rake-type soot blowers 90202 and acoustic soot blowers 90203 for combined soot blowing. The rake-type soot blower 90202 uses compressed air as the air source for soot blowing. The rake-type soot blower 90202 is provided with a plurality of nozzles on the rake rod, and the nozzle aperture is 2-3 mm. High-pressure gas is blown through the nozzles to clean the inner and outer surfaces of the catalyst. Unlike traditional arrangements, the actual distance from the nozzle of the rake-type soot blower to the surface of the catalyst in the present application is not more than 120 mm.

[0051] The compressed air used by the rake-type soot blower 90202 comes from the air compression station 7, which is provided with an air compressor, a filter, a dryer and the like to ensure that the air dew point is lower than -40℃. In particular, the compressed air used by the rake-type soot blower 90202 needs to be heated to above 200℃ to further avoid the formation of water droplets in the compressed air used for blowing at the nozzle of the rake-type soot blower 90202, which would directly damage the catalyst or cause the dust to harden and block the catalyst.

[0052] The rake-type soot blower 90202 is provided with a plurality of soot blowers in a cooperative blowing mode: in the soot blower stroke, blowing is started when going, blowing is stopped when returning, and the second soot blower is started to blow at the same time, so as to shorten the blowing time interval and strengthen the blowing effect.

[0053] The waste heat recovery unit 903 comprises a plurality of groups of tubes to form a heat exchange unit, recovers heat in the high-temperature flue gas, generates power through a steam turbine, provides energy for the plant, and reduces the outlet flue gas temperature of the dust and nitrogen oxide waste heat recovery integrated device 9 to 180-200 DEG C.

[0054] The system has the advantages that different functional units are integrated and the corresponding flue adjusting function is added, no flue is needed at the inlet and outlet of the denitration device, no support frame of the dust removal and denitration device needs to be separately arranged, and the system has the function of adjusting the flue gas state.

[0055] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A cement kiln denitration dust removal and waste heat recovery integrated system, comprising a preheater (2) and a dust and nitrate waste heat recovery integrated device (9), the inlet of the preheater (2) is connected with the outlet flue of a rotary kiln (1), characterized in that The dust and denitration waste heat recovery integrated device (9) comprises, from bottom to top, a dust removal unit (901), a denitration unit (902) and a waste heat recovery unit (903); the dust and denitration waste heat recovery integrated device (9) is provided with an inlet flue at the lower part and an outlet flue at the upper part, and the inlet flue at the lower part of the dust and denitration waste heat recovery integrated device (9) is connected with the outlet flue of the preheater (2); the outlet of the preheater (2) is connected with the ammonia water injection device (5); the outlet flue of the preheater (2) is further provided with an emergency cooling device (6) and a flue gas heater (8); and the outlet flue of the dust and denitration waste heat recovery integrated device (9) is provided with a humidification and cooling device (11).

2. The integrated system for denitration and dust removal and waste heat recovery of a cement kiln according to claim 1, characterized in that The dust removal unit (901) comprises a corona electrode, a dust collection electrode, a dust hopper and a water bath type dust conveying machine; the dust collection electrode has an anode plate, and the corona electrode has a cathode wire; the corona electrode and the dust collection electrode are connected with a high-voltage power supply, and impact vibration dust removal is adopted.

3. The integrated system for denitration and dust removal and waste heat recovery of a cement kiln according to claim 2, characterized in that The water bath type dust conveying machine comprises an inner shell, an outer shell, a pipeline and a conveying chain; the inner shell and the outer shell are provided with cooling water flow channels.

4. The integrated system for denitration and dust removal and waste heat recovery of a cement kiln according to claim 1, characterized in that The denitration unit (902) comprises a catalyst layer (90201), and the catalyst layer (90201) comprises a denitration catalyst and a supporting steel structure; each catalyst layer (90201) is provided with a plurality of rake type soot blowers (90202) and a sound wave soot blower (90203).

5. The integrated system for denitration and dust removal and waste heat recovery of a cement kiln according to claim 1, characterized in that The waste heat recovery unit (903) comprises a heat exchange unit composed of multiple groups of tubes.

6. The integrated system for denitration and dust removal and waste heat recovery of a cement kiln according to claim 4, characterized in that The rake type soot blower (90202) is provided with a plurality of nozzles with a pore diameter of 2-3 mm on the rake rod, and the distance from the nozzles of the rake type soot blower (90202) to the surface of the catalyst is not greater than 120 mm; the rake type soot blower (90202) is connected with an air compression station (7).

7. The integrated system for denitration and dust removal and waste heat recovery of a cement kiln according to claim 1, characterized in that The humidification and cooling device (11) is connected with a process water pump (12) and a process water tank (13).

8. The integrated system for denitration and dust removal and waste heat recovery of a cement kiln according to claim 1, characterized in that The outlet flue of the dust and denitration waste heat recovery integrated device (9) is connected with a high-temperature fan (14) and a kiln tail bag-type dust collector (17); the kiln tail bag-type dust collector (17) is connected with a circulating fan (16) and a raw material vertical mill (15); the outlet of the kiln tail bag-type dust collector (17) is connected with a kiln tail dust collection fan (18) and a chimney (19).

9. The integrated system for denitration and dust removal and waste heat recovery of a cement kiln according to claim 1, characterized in that The emergency cooling device (6) is provided with a plurality of humidification and cooling nozzles which are distributed in a mesh shape; the humidification and cooling nozzles adopt double-fluid spray guns, and each group of spray guns is provided with a flow adjusting device.

10. The integrated system for denitration and dust removal and waste heat recovery of a cement kiln according to claim 1, characterized in that The ammonia water injection device (5) is connected with an ammonia water conveying pump (4) and an ammonia water tank (3); the ammonia water injection device (5) is provided with a plurality of ammonia water spray guns, and the spray heads are arranged in a mesh shape; the spray heads adopt double-fluid spray guns, and each spray gun is provided with a flow adjusting device.

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