Denitration reactor adopting ultralow-temperature and medium-low-temperature series connection

Abstract

The invention relates to the technical field of denitration reactors, and provides an ultralow-temperature and medium-low-temperature series-connection denitration reactor which comprises an ultralow-temperature reactor and a medium-low-temperature reactor, a flue gas inlet area comprises a flue gas inlet and further comprises a reducing agent inlet, and a discharge area comprises an induced draft fan and a flue gas discharge chimney which are communicated with each other. The system further comprises a low-pressure steam pipe network of another path. A two-stage temperature zone is formed in a mode that ultralow-temperature deacidification denitration and medium-low-temperature denitration are connected in series, so that denitration reactions with different temperature gradients are continuously carried out on flue gas, finally, the treated flue gas is subjected to final treatment through the waste heat recovery mechanism, heat of the flue gas is recovered, and low-pressure steam is generated for external supply. The high-concentration flue gas can be treated, reaction heat can be taken away in time to avoid high-temperature inactivation of the catalyst, waste heat is recycled, and the requirements for energy conservation and environmental protection are met.

Description

Technical Field

[0001] The present invention relates to the technical field of denitration reactors, and more specifically, to a denitration reactor that uses ultra-low temperature and medium-low temperature in series. Background Art

[0002] During industrial production processes such as coal combustion, coking, glass manufacturing, and chemical engineering, a certain amount of dust, SO2, nitrogen oxides (NOx), and harmful metal elements are generated. The emission of NOx in flue gas is more harmful to the environment than that of SO2. The emission of a large amount of nitrogen oxides (NOx) will cause a series of environmental problems such as acid rain, photochemical smog, ozone layer depletion, and the greenhouse effect. Therefore, it is necessary to carry out deacidification and denitration treatment before emission to protect the environment. Currently, there are the following problems in the treatment and emission of high-concentration NOx: 1. To achieve an ultra-low emission standard in the treatment and emission of high-concentration NOx, the denitration efficiency needs to exceed 99.5%, which cannot be directly achieved by traditional SCR denitration technology. 2. Denitration itself is an exothermic reaction. It is not obvious for the treatment of low-concentration NOx, but it is very obvious for the treatment of high-concentration NOx. In industrial flue gas, for every 10,000 mg / Nm3 of NOx removed, the flue gas temperature rises by 80 - 100°C; for the denitration of flue gas with a NOx concentration reaching tens of thousands of mg / Nm3, the temperature rise is huge, and existing catalysts have temperature range requirements and cannot directly meet this temperature rise demand. 3. During the catalytic denitration reaction of the catalyst, the heat released by the denitration reaction will accumulate in the catalyst. If the reaction heat cannot be quickly removed, it will cause the catalyst to be deactivated at high temperature. To solve the above problems, a dual-temperature zone integrated deacidification and denitration reactor using ultra-low temperature and medium-low temperature in series is proposed in this application. Summary of the Invention

[0003] The purpose of the present invention is to provide a denitration reactor that uses ultra-low temperature and medium-low temperature in series. Through the treatment method of series connection of ultra-low temperature and medium-low temperature zones, and by using an independent granular catalyst combined with an intermittent moving bed, it meets the requirements for the treatment and emission of high-concentration NOx.

[0004] To solve the above technical problems, the present invention is realized through the following technical solutions: A denitration reactor that uses ultra-low temperature and medium-low temperature in series includes an ultra-low temperature reactor and a medium-low temperature reactor. The flue gas inlet area includes a flue gas inlet and also includes a reductant inlet. The discharge area includes an induced draft fan and a flue gas discharge chimney that are interconnected, and also includes a low-pressure steam going to the pipe network in another path. A waste heat recovery boiler, located at the outlet end of the medium-low temperature reactor, is interconnected with the ultra-low temperature reactor and the medium-low temperature reactor. The ultra-low temperature reactor is provided with a deacidification bed body at the lower layer and a denitration bed body at the upper layer, and the deacidification bed body and the denitration bed body are of an intermittent moving bed structure; The medium and low temperature reactor is provided with a denitration bed body, and the ultra-low temperature reactor and the medium and low temperature reactor are connected in series to form a two-stage temperature zone relay mechanism; The inlet end and the outlet end of the ultra-low temperature reactor are respectively provided with primary ammonia injection and secondary ammonia injection, both of which are communicated with the reductant inlet.

[0005] Advantages of the present invention: The present invention combines the ultra-low temperature reactor and the medium and low temperature reactor in series to form an integrated treatment method for deacidification, ultra-low temperature denitration and medium and low temperature denitration. The two-stage temperature zone relay avoids the sintering and inactivation of the catalyst caused by the over-limit temperature rise of a single reactor, can remove acidic gas, dust, liquid water, etc. entrained in the flue gas, effectively improves the denitration reaction efficiency and reduces the heat accumulation phenomenon; The present invention utilizes the characteristic of the ultra-low temperature particulate denitration catalyst to activate at low temperature to start the entire denitration reaction, and then cooperates with the medium and low temperature denitrator and the waste heat recovery boiler, which can reasonably utilize the flue gas temperature range, recover the flue gas heat at the same time, and generate steam as a by-product to generate economic benefits; The way of combining ultra-low temperature deacidification and denitration with medium and low temperature denitration in the present invention has a temperature rise range of 300 °C, meeting the treatment requirements of most high-concentration NOx in the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0007] Figure 1 It is a schematic diagram of the overall external structure of the deacidification and denitration integrated reaction equipment of the present invention; Figure 2 It is a schematic diagram of the internal structure of the ultra-low temperature reactor of the present invention; Figure 3 It is a schematic diagram of the internal structure of the medium and low temperature reactor of the present invention; Figure 4 It is a schematic diagram of the flue gas treatment module of the deacidification and denitration integrated reaction equipment of the present invention; In the drawings, the list of components represented by each reference numeral is as follows: In the figure: 100. Ultra-low temperature reactor; 200. Medium and low temperature reactor; 110. Secondary denitration bed; 120. Primary denitration bed; 130. Secondary deacidification bed; 140. Primary deacidification bed; 210, Four - stage denitration bed; 220, Three - stage denitration bed; 301, Flue gas inlet; 302, Reducing agent inlet; 303, Primary ammonia injection; 304, Secondary ammonia injection; 305, Waste heat recovery boiler; 306, Induced draft fan; 307, Low - pressure steam to pipe network; 308, Flue gas to emission chimney. Specific implementation mode

[0008] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0009] Please refer to Figure 1 - Figure 4 As shown, the present invention provides a super - low - temperature and medium - low - temperature series denitration reactor, including a super - low - temperature reactor 100 and a medium - low - temperature reactor 200. The flue gas inlet area includes a flue gas inlet 301, and also includes a reducing agent inlet 302. The emission area includes an induced draft fan 306 and a flue gas to emission chimney 308 that are interconnected, and also includes a low - pressure steam to pipe network 307 in another path. The flue gas flows from bottom to top; The waste heat recovery boiler 305, located at the outlet end of the medium - low - temperature reactor 200, is interconnected with the super - low - temperature reactor 100 and the medium - low - temperature reactor 200, and is used to recover the heat of the flue gas discharged after treatment, thereby generating steam as a by - product to produce economic benefits, and thus reducing the final flue gas discharge temperature to reduce the load of the induced draft fan; In the super - low - temperature reactor 100, a deacidification bed body is arranged at the lower layer and a denitration bed body is arranged at the upper layer. The super - low - temperature reactor 100 and the deacidification bed body and the denitration bed body form an intermittent moving bed structure, which has the characteristics of both a moving bed and a fixed bed at the same time. By supplementing the catalyst through the top feed valve and discharging the waste agent through the bottom discharge port, the desulfurization agent and the catalyst can be replaced online, thereby achieving the effect of unattended operation; In the medium - low - temperature reactor 200, a denitration bed body is arranged, and an intermittent moving bed structure is also formed. The super - low - temperature reactor 100 and the medium - low - temperature reactor 200 are connected in series to form a two - stage temperature zone relay mechanism; The inlet end and the outlet end of the ultra-low temperature reactor 100 are respectively provided with a primary ammonia injection 303 and a secondary ammonia injection 304, both of which are connected to the reductant inlet 302. The primary ammonia injection 303 and the secondary ammonia injection 304 both include an ammonia metering and regulating system, an ammonia injection grid or a spray gun, a mixer, and a monitoring instrument. The primary ammonia injection 303 is used to quantitatively remove the concentration of NOx, that is, to control the ammonia injection amount, and control the NOx removal efficiency within a certain range during the deacidification and ultra-low temperature denitration reactor process to ensure the stability of the deacidification and ultra-low temperature denitration reactor system and the effect of the subsequent treatment device.

[0010] Further, the denitration bed body in the ultra-low temperature reactor 100 is a layered structure, with the upper layer being the secondary denitration bed 110 and the lower layer being the primary denitration bed 120. The secondary denitration bed 110 and the primary denitration bed 120 are filled with granular denitration catalysts, and the active temperature range is 90-180 °C.

[0011] Further, the denitration bed body in the medium and low temperature reactor 200 is divided into a fourth-level denitration bed 210 in the upper layer and a third-level denitration bed 220 in the lower layer, and the active temperature range of the filled granular denitration catalyst is 190-300 °C.

[0012] Among them, the catalyst is in the form of granules, which has a higher denitration efficiency compared with the traditional honeycomb body, meets the treatment requirements of high-concentration NOx, and at the same time uses this structural form to reduce the overall volume of the equipment; Further, the deacidification bed body in the ultra-low temperature reactor 100 is a layered structure, with the upper layer being the secondary deacidification bed 130 and the lower layer being the primary deacidification bed 140. Granular fine desulfurizer is filled therein to remove acidic gases, dust, and liquid water, which can prevent these impurities from affecting the subsequent denitration catalyst. Secondly, setting the deacidification bed body can better make the flue gas evenly distributed in the reactor, make the denitration reaction more uniform, improve the efficiency of the denitration reaction, and reduce the phenomenon of heat accumulation.

[0013] Further, the primary ammonia injection 303 controls the NOx removal rate to be 40%-60%, makes the flue gas temperature rise ≤70 °C, controls the primary ammonia injection amount according to NH3 / NOx = 0.85, the denitration rate is 52% → the temperature rise is 65 °C, and the secondary ammonia injection 304 controls the final NOx emission concentration ≤50 mg / Nm³.

[0014] Further, the waste heat recovery boiler 305 recovers the heat of the flue gas to generate steam at 0.3-0.6 MPa, the exhaust gas temperature drops below 130 °C, the steam discharge port of the waste heat recovery boiler 305 is connected to the low-pressure steam to the pipe network 307, and the flue gas discharge port is connected to the flue gas to the discharge chimney 308 through the induced draft fan 306 to release the low-temperature qualified tail gas outward, and the induced draft fan provides power for the entire equipment system.

[0015] Furthermore, the series-connected denitration reactor is adapted to waste gas with a NOx concentration of 10,000 - 50,000 mg / Nm³, and the total denitration efficiency is ≥ 99.5%.

[0016] It can be understood that the present invention adopts a series connection of ultra-low temperature deacidification and denitration and medium-low temperature denitration to form a two-stage temperature zone, so as to continuously carry out denitration reactions with different temperature gradients on the flue gas. Finally, the treated flue gas is finally processed by the waste heat recovery mechanism, and its heat is recovered to generate low-pressure steam for external supply. Finally, the low-temperature qualified flue gas is discharged outwards. It can not only treat high-concentration flue gas, but also timely take away the reaction heat to avoid high-temperature deactivation of the catalyst, and the recovery and utilization of waste heat meet the requirements of energy conservation and environmental protection.

[0017] The specific working process is as follows: First, the high-concentration flue gas generated by production devices such as chemical industry is sent into the inlet of the ultra-low temperature reactor by a fan, and during this period, it passes through the first-stage ammonia injection 303. At this time, ammonia is mixed with the flue gas to quantitatively remove the NOx concentration and take away a certain amount of heat. Subsequently, the mixed gas enters the medium-low temperature reactor and sequentially passes through the deacidification bed layer (the first-stage deacidification bed 140 and the second-stage deacidification bed 130) and the denitration bed layer (the first-stage denitration layer 120 and the second-stage denitration layer 110) from bottom to top. In the deacidification bed layer, acidic gas, dust, liquid water, etc. entrained in the flue gas are removed to prevent these impurities from affecting the subsequent denitration catalyst. As the reaction proceeds, the temperature rises, and at the same time, the deacidification bed layer can better make the flue gas evenly distributed in the reactor, making the denitration reaction more uniform and sufficient, and improving the efficiency of the denitration reaction to reduce the heat accumulation phenomenon; Furthermore, the heated flue gas contacts the denitration bed layer and undergoes a denitration reaction through the ultra-low temperature granular denitration catalyst filled therein to quantitatively remove the NOx concentration, ensuring that the temperature does not exceed the limit after the reaction exotherms, and will not cause harm to the catalyst and equipment. At the same time, the control of flow rate, speed control, etc. ensures that the reaction heat can be taken away to avoid catalyst heat accumulation. As the reaction proceeds, the temperature of the flue gas rises again; Subsequently, the flue gas enters the medium-low temperature denitration reactor 200. Before entering, it is further mixed through the second-stage ammonia injection 304 to reduce the NOx concentration. The denitration bed layer (the third-stage denitration bed 220 and the fourth-stage denitration bed 210) in the low-temperature denitration reactor 200 reduces the NOx concentration to below the ultra-low emission concentration, and takes away the reaction heat by controlling the flow rate, space velocity, etc.; Furthermore, the flue gas after denitration reaches the standard and continues to enter the waste heat recovery boiler 305 to recover the heat of the flue gas, thereby generating steam as a by-product to generate economic benefits, and at the same time reducing the final flue gas discharge temperature to reduce the fan load; Finally, the treated flue gas is discharged through the flue gas to chimney discharge 308.

[0018] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0019] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A denitration reactor using ultra-low temperature and medium-low temperature in series, comprising an ultra-low temperature reactor (100) and a medium-low temperature reactor (200). The flue gas inlet area includes a flue gas inlet (301), and also includes a reductant inlet (302). The discharge area includes a connected induced draft fan (306) and a flue gas discharge chimney (308), and also includes a low-pressure steam to the pipe network (307) in another path. The flue gas is conveyed from bottom to top, and is characterized in that: A waste heat recovery boiler (305), located at the outlet end of the medium-low temperature reactor (200), is interconnected with the ultra-low temperature reactor (100) and the medium-low temperature reactor (200); In the ultra-low temperature reactor (100), a deacidification bed body is arranged at the lower layer and a denitration bed body is arranged at the upper layer, and the deacidification bed body and the denitration bed body are of an intermittent moving bed structure; In the medium-low temperature reactor (200), a denitration bed body is arranged, and the ultra-low temperature reactor (100) and the medium-low temperature reactor (200) are connected in series to form a two-stage temperature zone relay mechanism; An ammonia injection at the first stage (303) and an ammonia injection at the second stage (304) are respectively arranged at the inlet end and the outlet end of the ultra-low temperature reactor (100), and both are connected to the reductant inlet (302).

2. The ultra-low temperature and medium-low temperature series-connected denitration reactor according to claim 1, wherein: The denitration bed body in the ultra-low temperature reactor (100) is of a layered structure, with a secondary denitration bed (110) at the upper layer and a primary denitration bed (120) at the lower layer. Granular denitration catalysts are filled in the secondary denitration bed (110) and the primary denitration bed (120), and the active temperature range is 90 - 180 °C.

3. The ultra-low temperature and medium-low temperature tandem denitration reactor according to claim 1, characterized in that: The denitration bed body in the medium-low temperature reactor (200) is divided into a quaternary denitration bed (210) at the upper layer and a tertiary denitration bed (220) at the lower layer. Granular denitration catalysts filled therein have an active temperature range of 190 - 300 °C.

4. The ultra-low temperature and medium-low temperature tandem denitration reactor according to claim 1, wherein: The deacidification bed body in the ultra-low temperature reactor (100) is of a layered structure, with a secondary deacidification bed (130) at the upper layer and a primary deacidification bed (140) at the lower layer. Granular fine desulfurization agents are filled therein to remove acidic gases, dust, and liquid water.

5. The ultra-low temperature and medium-low temperature series-connected denitration reactor according to claim 1, wherein: The ammonia injection at the first stage (303) controls the NOx removal rate to be 40% - 60%, and the flue gas temperature rise ≤ 70 °C. The ammonia injection at the second stage (304) controls the final NOx emission concentration ≤ 50 mg / Nm³.

6. The ultra-low temperature and medium-low temperature series-connected denitration reactor according to claim 1, characterized in that: The waste heat recovery boiler (305) recovers the heat of the flue gas to generate steam of 0.3 - 0.6 MPa, and the flue gas discharge temperature drops below 130 °C.

7. The ultra-low temperature and medium-low temperature series-connected denitration reactor according to claim 6, characterized in that: The waste heat recovery boiler (305) has two discharge ports. One discharge port is connected to the low-pressure steam to the pipe network (307), and the other discharge port is connected to the flue gas discharge chimney (308) through the induced draft fan (306).

8. The ultra-low temperature and medium-low temperature tandem denitration reactor according to claim 1, wherein: The ammonia injection at the first stage (303) and the ammonia injection at the second stage (304) both include an ammonia metering and regulating system, an ammonia injection grid (or spray gun), a mixer, and monitoring instruments. The ammonia injection at the first stage (303) is used to quantitatively remove the concentration of NOx.

9. The ultra-low temperature and medium-low temperature series-connected denitration reactor according to claim 1, characterized in that: The ultra-low temperature reactor (100) and the medium-low temperature reactor (200) are intermittent moving beds, and simultaneously have the characteristics of a moving bed and a fixed bed, and are used for online replacement of desulfurization agents and catalysts.

10. The ultra-low temperature and medium-low temperature series-connected denitration reactor according to claim 1, wherein: The series-connected denitration reactor is adapted to waste gas with a NOx concentration of 10,000 - 50,000 mg / Nm³, and the total denitration efficiency is ≥ 99.5%.

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