阅读说明：本技术 一种烧结烟气湿法脱硫后的脱白脱硝系统及方法 (System and method for removing white and nitrate after sintering flue gas wet desulphurization ) 是由 孙军如 于 2019-11-29 设计创作，主要内容包括：本发明公开一种烧结烟气湿法脱硫后的脱白脱硝系统及方法,在湿法脱硫后增加湿式电除尘器,用于脱除烟气中水滴和灰尘,然后通过脱白回转式换热器,利用脱硫前烟气热量加热经过湿电除尘器除尘的烟气,使进入脱硝系统的烟气为过热烟气,经过脱白回转式换热器加热后的烟气,进入脱硝回转式换热器继续加热,然后经过热风炉升温至脱硝反应温度,通过喷氨装置向加热后烟气中喷入氨气,含有氨气的烟气在脱硝反应器中,在催化剂作用下,脱除烟气中NOx,从而实现对烟气脱硝。脱硝后的烟气经过脱硝回转式换热器,放出热量加热需要脱硝的烟气,确保外排烟囱的烟气与半干法脱硫一样不会冒白烟。(The invention discloses a system and a method for removing white and nitrate from sintering flue gas after wet desulphurization, wherein a wet electric dust remover is added after the wet desulphurization for removing water drops and dust in the flue gas, then the flue gas which is dedusted by a wet electric dust remover is heated by utilizing the heat of the flue gas before desulphurization through a rotary white-removing heat exchanger, so that the flue gas entering a denitration system is superheated flue gas, the flue gas which is heated by the rotary white-removing heat exchanger enters a rotary denitration heat exchanger for continuous heating, then the temperature is raised to the denitration reaction temperature through a hot blast stove, ammonia gas is sprayed into the heated flue gas through an ammonia spraying device, the flue gas containing the ammonia gas is in a denitration reactor, and NOx in the flue gas is removed under the action of a catalyst, thereby realizing the denitration of the flue. The denitrated flue gas passes through the rotary denitration heat exchanger, the heat is released to heat the flue gas to be denitrated, and the flue gas discharged out of the chimney is ensured not to emit white smoke as the flue gas discharged out of the chimney by the semi-dry desulfurization process.)

1. A de-whitening and denitration system after sintering flue gas wet desulphurization is characterized by comprising a wet desulphurization unit, a wet electric precipitator, a de-whitening rotary heat exchanger, a denitration unit and a denitration rotary heat exchanger, wherein a sintering flue gas inlet pipeline is connected with an original flue gas high-temperature section interface of the de-whitening rotary heat exchanger; the raw flue gas low-temperature section interface of the rotary type de-whitening heat exchanger is connected with the flue gas inlet of the wet desulphurization unit; the flue gas outlet of the wet desulphurization unit is connected with the inlet of the wet electric dust collector; the outlet of the wet electric dust collector is connected with the clean flue gas low-temperature section interface of the rotary type de-whitening heat exchanger; the clean flue gas high-temperature section interface of the rotary de-whitening heat exchanger is connected with the raw flue gas low-temperature section interface of the rotary de-nitrification heat exchanger; the raw flue gas high-temperature section interface of the rotary denitration heat exchanger is connected with an inlet of the denitration unit; the outlet of the denitration unit is connected with a clean flue gas high-temperature section interface of the rotary denitration heat exchanger; and the clean flue gas low-temperature section interface of the rotary denitration heat exchanger is used for sending out the final flue gas obtained by the system treatment.

2. The de-whitening and de-nitration system after sintering flue gas wet desulphurization according to claim 1, characterized in that: the denitration device is characterized in that an ammonia spraying device is arranged on an inlet flue of the denitration unit.

3. The de-whitening and de-nitration system after sintering flue gas wet desulphurization according to claim 1, characterized in that: and a hot blast stove is connected between a raw flue gas high-temperature section interface and a clean flue gas low-temperature section interface of the denitration rotary heat exchanger, an inlet of the hot blast stove is connected with the clean flue gas low-temperature section interface of the denitration rotary heat exchanger, and an outlet of the hot blast stove is connected with the raw flue gas high-temperature section interface of the denitration rotary heat exchanger.

4. The de-whitening and de-nitration system after sintering flue gas wet desulphurization according to claim 3, characterized in that: and a booster fan is arranged on a dilution air flue at the inlet of the hot blast stove.

5. The de-whitening and de-nitration system after sintering flue gas wet desulphurization according to claim 1, characterized in that: the heat exchange element of the rotary de-whitening heat exchanger is a straight-through flat plate type with an enamel surface; the contact part of the rotary de-whitening heat exchanger and the flue gas is provided with glass flakes for corrosion prevention; the rotary type de-whitening heat exchanger is provided with a telescopic high-pressure water washing device and a telescopic compressed air flushing device.

6. The de-whitening and de-nitration system after sintering flue gas wet desulphurization according to claim 1, characterized in that: the heat exchange element of the rotary denitration heat exchanger is a heat exchange sheet with corrugations, and the material of the heat exchange element at the low-temperature section is acid-resistant steel; the rotary denitration heat exchanger is provided with a telescopic compressed air sweeping device.

7. The de-whitening and de-nitration system after sintering flue gas wet desulphurization according to claim 1, characterized in that: the anode tube of the wet electric dust collector is made of honeycomb-shaped glass fiber reinforced plastic.

8. A method for removing white and nitrate after sintering flue gas wet desulphurization is characterized by comprising the following steps: sintering flue gas firstly enters an original flue gas section of the rotary de-whitening heat exchanger through a flue to heat a heat exchange element of the rotary de-whitening heat exchanger, and meanwhile, the flue gas to be desulfurized is cooled by the heat exchange element of the rotary de-whitening heat exchanger, the flue gas after being cooled enters a wet desulphurization unit to be desulfurized, the flue gas after being desulfurized enters a wet electric precipitator through the flue to be dedusted and water drops are removed, then the flue gas enters the rotary de-whitening heat exchanger, and is heated by the heat exchange element, the heated flue gas enters an original flue gas section of the rotary de-whitening heat exchanger to be heated by the heat exchange element of the rotary de-whitening heat exchanger, and then is heated by a hot blast stove, ammonia gas is uniformly sprayed into the flue gas heated by the hot blast.

9. The method for removing white and nitrate after sintering flue gas wet desulphurization according to claim 8, characterized by comprising the following steps: the temperature of the flue gas is raised by 25-30 ℃ through a hot blast stove, and the denitration reaction temperature is 200-280 ℃.

Technical Field

The invention relates to a de-whitening and de-nitrating device used after sintering flue gas wet desulphurization, belonging to the field of sintering flue gas desulphurization and de-whitening.

Background

At present, with the increasingly strict requirements on environmental protection, the sintering flue gas and the power plant boiler flue gas are both subjected to ultra-low emission treatment, and the wet desulphurization flue gas is subjected to whitening treatment. At present, a plurality of units change wet desulphurization into semi-dry desulphurization for solving the problem of white smoke emission by the wet process, and some units build a white removal device after the wet desulphurization for eliminating the white smoke phenomenon. The first scheme has too high investment and also has the problem that semi-dry desulfurization is difficult to treat; the second scheme also has high investment, and also has the problems of blockage and corrosion of a whitening device, and in addition, the sensory effect of whitening implementation is not obvious.

Utility model patent "an integrated process systems for steel mill sintering flue gas denitration takes off white" (patent number is 201821740452.3), adopts earlier high temperature denitration, then the desulfurization takes off white at last, takes off white device and adopts two sets of indirect heat exchangers to carry out the heat transfer, is exactly MGGH heat transfer technology in fact. This technique is unproblematic to the denitration, nevertheless is relatively poor to taking off white effect, does not utilize the intensification heat of denitration (can heat up the flue gas 30 degrees), and the sensory effect of taking off white is not obvious, and is more serious to the corrosion problem of second heat exchanger simultaneously, if adopts the PTFE material, then the heat transfer effect is poor, and the resistance is high, and the investment is high, and the working costs is high. In the technical scheme, no wet electric dust removal device is used, and ultralow emission is difficult to achieve.

The invention discloses a sintering flue gas desulfurization, denitrification, dedusting and whitening removal purification process (patent application number is 201910022040.9), which also adopts an ammonia method for desulfurization and final whitening removal after high-temperature denitrification, desulfurization and desulfurization, and a device for removing the white also adopts two sets of indirect heat exchangers for heat exchange, and is actually an MGGH heat exchange process. The same problem that this technique and aforementioned patent exist, to the denitration problem-free, nevertheless to taking off white effect relatively poor, do not utilize the heat that the denitration heaied up (can heat up the flue gas by 30 degrees), the sensory effect of taking off white is not obvious, and will be more serious to the corruption problem of second heat exchanger simultaneously, if adopt the PTFE material, then the heat transfer effect is poor, and the resistance is high, and the investment is high, and the working costs is high.

Utility model patent "a sintering flue gas denitration desulfurization system" (patent number is 201721840769.X), adopt high temperature denitration earlier equally, then the desulfurization, the ammonia process desulfurization that the desulfurization adopted, this patent technique does not have and takes off white device. The whitening of the smoke cannot be realized.

At present, a denitration system is also directly newly built after wet desulphurization, and the denitration system causes the rotary heat exchanger for denitration to be easily blocked because the flue gas generated by wet desulphurization is not treated, and causes the denitration catalyst to be blocked, thereby seriously influencing the normal operation of the denitration system, and the energy consumption required by the temperature rise of the denitration system is also extremely high.

Disclosure of Invention

The purpose of the invention is as follows: in order to solve the problem that white smoke is emitted by flue gas after wet desulphurization, improve the whitening effect, reduce the investment cost for whitening and realizing ultralow emission and reduce the operating cost of environmental protection facilities, the invention overcomes the defects of the above technology, adopts wet desulphurization, wet electric dust removal, whitening and final denitration, fully utilizes the heat of sintering flue gas and the heat of flue gas after denitration, achieves the whitening effect of a semi-dry method, and simultaneously retains the high efficiency advantage of wet desulphurization. The technology can realize whitening while realizing ultralow emission with lower investment and lower operating cost, has the same or better whitening effect as a semi-dry method, but has better treatment efficiency and desulfurized ash treatment than a semi-dry method, and the desulfurized ash can be fully used in the building material industry such as cement. The invention provides a process for removing white and nitrate from sintering flue gas after wet desulphurization, which can thoroughly solve the ultralow emission of sintering flue gas, solve the problem of white smoke emission after wet desulphurization, and retain the advantages of high wet desulphurization efficiency and resource utilization of desulphurization ash compared with semi-dry desulphurization.

In order to solve the technical problems, the invention specifically adopts the following technical scheme:

a de-whitening and denitration system after sintering flue gas wet desulphurization is characterized by comprising a wet desulphurization unit, a wet electric precipitator, a de-whitening rotary heat exchanger, a denitration unit and a denitration rotary heat exchanger, wherein a sintering flue gas inlet pipeline is connected with an original flue gas high-temperature section interface of the de-whitening rotary heat exchanger; the raw flue gas low-temperature section interface of the rotary type de-whitening heat exchanger is connected with the flue gas inlet of the wet desulphurization unit; the flue gas outlet of the wet desulphurization unit is connected with the inlet of the wet electric dust collector; the outlet of the wet electric dust collector is connected with the clean flue gas low-temperature section interface of the rotary type de-whitening heat exchanger; the clean flue gas high-temperature section interface of the rotary de-whitening heat exchanger is connected with the raw flue gas low-temperature section interface of the rotary de-nitrification heat exchanger; the raw flue gas high-temperature section interface of the rotary denitration heat exchanger is connected with an inlet of the denitration unit; the outlet of the denitration unit is connected with a clean flue gas high-temperature section interface of the rotary denitration heat exchanger; and the clean flue gas low-temperature section interface of the rotary denitration heat exchanger is used for sending out the final flue gas obtained by the system treatment.

A method for removing white and nitrate after sintering flue gas wet desulphurization is characterized by comprising the following steps: sintering flue gas firstly enters an original flue gas section of the rotary de-whitening heat exchanger through a flue to heat a heat exchange element of the rotary de-whitening heat exchanger, and meanwhile, the flue gas to be desulfurized is cooled by the heat exchange element of the rotary de-whitening heat exchanger, the flue gas after being cooled enters a wet desulphurization unit to be desulfurized, the flue gas after being desulfurized enters a wet electric precipitator through the flue to be dedusted and water drops are removed, then the flue gas enters the rotary de-whitening heat exchanger, and is heated by the heat exchange element, the heated flue gas enters an original flue gas section of the rotary de-whitening heat exchanger to be heated by the heat exchange element of the rotary de-whitening heat exchanger, and then is heated by a hot blast stove, ammonia gas is uniformly sprayed into the flue gas heated by the hot blast.

According to the invention, a wet electric dust collector is added after wet desulfurization for removing water drops and dust in flue gas, then the flue gas dedusted by the wet electric dust collector is heated by utilizing the heat of the flue gas before desulfurization through a rotary de-whitening heat exchanger, so that the flue gas entering a denitration system is superheated flue gas, the flue gas heated by the rotary de-whitening heat exchanger enters a rotary denitration heat exchanger for continuous heating, then the temperature is raised to a denitration reaction temperature (200-280 ℃ for medium-low temperature denitration) through a hot blast stove, ammonia gas is sprayed into the heated flue gas through an ammonia spraying device, the flue gas containing the ammonia gas is removed from the flue gas in the denitration reactor under the action of a catalyst, and thus the denitration of the flue gas is realized. The flue gas after denitration passes through the rotary denitration heat exchanger, the heat is released to heat the flue gas to be denitrated, the temperature of the hot blast stove only needs to be raised by 25-30 ℃ in the whole denitration process, and the temperature of the flue gas discharged after final denitration is raised by about 30 ℃ compared with the temperature of the flue gas after denitration. Thereby ensuring that the smoke of the chimney discharged outside does not emit white smoke as the smoke of the semi-dry desulphurization.

The process for removing the white and the nitrate after the wet desulphurization of the sintering flue gas has the following advantages:

1. after the wet desulfurization flue gas is dedusted by a wet electric precipitator, the flue gas basically does not contain water drops, and the contained dust is less than 5mg/Nm³And the particles realize ultra-low emission.

2. The heat of the sintering flue gas before wet desulphurization is fully utilized to heat the flue gas after the dust removal of the wet electric dust remover. After the flue gas (basically containing no water drops and containing little dust) subjected to wet-type electric precipitation enters the rotary de-whitening heat exchanger, the phenomenon of scaling and blocking is not easy to occur, and meanwhile, the temperature of the heated flue gas can be increased (because the flue gas basically contains no water drops, the heat required by heating the water drops is greatly reduced);

3. after heat exchange of the rotary type white-removing heat exchanger, the temperature of the flue gas entering the desulfurization system is greatly reduced, and the water content (saturated water) in the desulfurized flue gas is greatly reduced.

4. The flue gas heated by the de-whitening heat exchanger is superheated flue gas far away from a dew point (about 20-30 degrees higher). If discharged directly, substantially no white smoke is visible.

5. The flue gas heated by the rotary de-whitening heat exchanger is heated by the rotary denitration heat exchanger, and the heat of the hot blast stove required for heating to the denitration reaction temperature is greatly reduced. And heating the denitrified flue gas after heat exchange of the denitrified flue gas by the rotary denitration heat exchanger, and then pressurizing the denitrified flue gas by the fan to discharge the denitrified flue gas from the chimney, wherein the temperature of the flue gas discharged from the chimney is increased by about 30 ℃ compared with the temperature of the denitrified flue gas. The temperature is far higher than the dew point of the smoke (above 50 ℃, the same as the dry method), and the white smoke phenomenon does not occur.

6. Because the flue gas needing denitration is subjected to desulfurization treatment, the flue gas contains sulfurThe amount is less than 35mg/Nm³Therefore, medium and low temperature denitration can be adopted, the denitration temperature can be 200-280 ℃, high temperature denitration (over 320 ℃) is not needed, and the heating energy consumption of denitration is reduced.

Drawings

FIG. 1 is a flow chart of the process of removing white and nitrate after sintering flue gas wet desulphurization.

Wherein: 1. the system comprises a rotary de-whitening heat exchanger 2, a wet electric dust collector 3, a wet desulphurization unit 4, a hot blast stove 5, an ammonia spraying device 6, a denitration unit 7, a denitration catalyst 8, a rotary denitration heat exchanger 9, a booster fan 10 and a chimney

Detailed Description

The invention will be further described with reference to fig. 1.