Process device for low-temperature denitration, dust removal and white smoke removal after wet desulphurization

Abstract

The utility model discloses a low-temperature denitration, dust removal and white smoke removal process device after wet desulfurization. The device comprises a desulfurization circulating pool, a desulfurization spraying system, a desulfurization liquid reflux system, a primary condensation system water return system and a secondary condensation system water return system, a flue gas outlet in the top of the desulfurization tower is connected with the temperature compensation heating system through the primary condensation system and the low-temperature side of the heat exchanger in sequence; flue gas passes through the denitration reducing agent injection grid, the flow field mixer and the rectifier and then enters the SCR denitration catalyst layer; and the denitrated flue gas enters a bag-type dust collector through the high-temperature side of the heat exchanger, and then enters a secondary condensation system through an induced draft fan for white smoke removal treatment. According to the device, liquid flows back to the desulfurization circulating pool through the desulfurization liquid backflow system, the primary condensation system water return system and the secondary condensation system water return system, so that cyclic utilization is realized. According to the invention, collaborative treatment of flue gas desulfurization, low-temperature denitration, dust removal and white smoke removal is realized, and the system has the advantages of compact structure, energy saving, water saving and low operation cost.

Description

Technical Field

[0001] The utility model belongs to the technical field of flue gas denitration, dust removal and whitening, and specifically relates to a novel low-temperature denitration, dust removal and whitening process device after wet desulfurization. Background Art

[0002] Regarding the management of wet desulfurization, low-temperature flue gas desulfurization, denitrification, and dust removal, the problems existing in the comprehensive management technology of wet desulfurization and low-temperature flue gas industry are as follows:

[0003] 1) To reduce equipment costs, the SCR denitrification system is placed before the desulfurization process. High concentrations of sulfur dioxide react with the injected reducing agent, and the reactants are deposited on the catalyst surface and pores, causing serious problems such as reduced catalyst activity and clogging. Furthermore, the large amount of moisture in the flue gas causes catalyst deactivation, seriously affecting the stable operation of the system equipment.

[0004] 2) In order to reduce equipment investment, wet oxidation denitrification and wet desulfurization technologies are selected, resulting in huge equipment operating costs, as well as potential risks of denitrification and excessively high operating costs;

[0005] 3) The use of ozone denitrification or wet oxidation denitrification creates new environmental pollution, while also posing potential risks in denitrification treatment and excessively high operating costs;

[0006] 4) The use of SCR denitrification or ozone denitrification through flue gas heating has high equipment investment costs and huge subsequent operating costs;

[0007] 5) In order to reduce operating costs and equipment costs, the SNCR denitrification technology with low removal efficiency is selected, which cannot meet the ultra-low emission control requirements;

[0008] 6) Adding wet oxidation denitrification or ozone denitrification after the desulfurization tower and building a new alkaline washing tower to remove nitrogen oxides at the same time, the treatment technology selection is inappropriate and results in waste of resources;

[0009] 7) Building a new bag filter after wet desulfurization and low-temperature flue gas without treatment will cause operational problems such as bag sticking and severe corrosion, indicating inappropriate treatment technology selection;

[0010] 8) Choosing banned treatment technologies such as ozone denitrification and wet oxidation denitrification has high removal risks and is not conducive to long-term investment;

[0011] 9) The use of wet desulfurization, wet denitrification, ozone denitrification and other treatment technologies that cause flue gas whitening will result in high costs for later dewhitening treatment;

[0012] 10) In the treatment of wet flue gas desulfurization, low-temperature flue gas desulfurization, denitrification and dust removal, the issues of flue gas desulfurization, energy saving and water saving have not been considered as resources, and the diversified and systematic treatment goals cannot be achieved.

[0013] Therefore, it is particularly important to seek a new low-temperature denitrification, dust removal and dewhitening process after wet desulfurization, which can also achieve the goals of energy and water conservation in the treatment process and realize diversified and systematic treatment.

[0014] While fully utilizing wet desulfurization and low-temperature flue gas, by adding reasonable technical and process layouts and fully combining the characteristics of the desulfurization, denitrification, dust removal, and whitening processes, the impact of existing process parameters mentioned in the desulfurization, denitrification, and dust removal processes on the treatment technology is avoided. While ensuring the stable operation of desulfurization, denitrification, and dust removal, the whitening treatment is coordinated to achieve the treatment goals of energy and water conservation. This does not cause unnecessary huge economic losses to existing enterprises. At the same time, ensuring the integration of desulfurization, denitrification, dust removal, whitening, energy conservation, and water conservation to achieve optimal coordination is the problem to be solved by this utility model. Summary of the Invention

[0015] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present utility model is to provide a new type of low-temperature denitrification, dust removal and dewhitening process device after wet desulfurization, which can realize wet desulfurization, denitrification, dust removal, dewhitening, energy saving and water saving management of low-temperature flue gas, so that the flue gas can meet the requirements of ultra-low emissions, and at the same time achieve the principle of minimizing construction cost and operating cost; it can also recover a large amount of heat energy and water resources in the discharged flue gas, and has the characteristics of energy saving, water saving and rational utilization of resources.

[0016] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a new type of low-temperature denitrification, dust removal and whitening process device after wet desulfurization, including a desulfurization spray system connected to the desulfurization circulation pool, a desulfurization liquid reflux system, a primary condensation system return water system and a secondary condensation system return water system; the outlet of the desulfurization spray system is connected to the left flue gas inlet of the desulfurization tower; the top flue gas outlet of the desulfurization tower is connected to the low-temperature side inlet of the heat exchanger in turn through the connecting flue 1, the primary condensation system and the pipeline 1; the low-temperature side outlet of the heat exchanger is connected to the temperature compensation heating system, the denitrification reducing agent ammonia spray grid, the flue gas flow field mixer in turn , the flue gas flow field rectifier is connected; the lower side of the flue gas flow field rectifier is a reserved space for the SCR denitration catalyst; the lower part of the SCR denitration catalyst reserved space is provided with SCR denitration catalyst 1 and SCR denitration catalyst 2 in sequence; the denitration reducing agent storage system sprays the reducing agent into the denitration reducing agent injection grid through the denitration reducing agent injection system; the outlet end of the reactor is connected to the high-temperature side inlet of the heat exchanger; the high-temperature side outlet of the heat exchanger is connected to the bag filter through the connecting flue 2; the outlet of the bag filter is connected to the secondary condensation system through the connecting flue 3, the induced draft fan power system, and the connecting flue 4;

[0017] The desulfurization liquid reflux system pipeline is connected to the bottom of the desulfurization tower; the outlet pipelines of the primary condensation system return water system and the secondary condensation system return water system are respectively connected to the desulfurization circulation pool.

[0018] The second pipeline is provided with a denitrification reducing agent injection grid and a flue gas flow field mixer; the denitrification reducing agent injection grid is connected to the denitrification reducing agent storage system through the denitrification reducing agent injection system.

[0019] The temperature compensation heating system is connected to the low temperature side outlet of the heat exchanger.

[0020] The high-temperature side outlet of the heat exchanger is connected to the bag dust collector through the second connecting flue, the high-temperature side inlet of the heat exchanger is connected to the reactor, the low-temperature side outlet of the heat exchanger is connected to the temperature compensation heating system, and the low-temperature side inlet of the heat exchanger is connected to the primary condensation system.

[0021] The reactor is provided with a reserved space for an SCR denitration catalyst, a first SCR denitration catalyst and a second SCR denitration catalyst.

[0022] The heat exchanger realizes heat exchange through the rotating heating surface.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1) This utility model utilizes wet desulfurization, low-temperature flue gas + primary condensation system + proprietary heat exchanger + temperature compensation heating + SCR denitrification + bag filter + secondary condensation system (chimney) treatment technology to achieve desulfurization, denitrification, dust removal, dewhitening, energy saving and water saving treatment with wet desulfurization and low-temperature flue gas;

[0025] 2) This utility model utilizes wet desulfurization, with low-temperature flue gas passing through a primary condensation system, resulting in a temperature drop of approximately 20°C. This condenses and separates a large amount of water from the flue gas, ensuring that the flue gas moisture content meets the inlet standards of the heat exchanger. At the same time, the recovered condensed water is collected and transported to the desulfurization system for recycling, achieving initial water conservation.

[0026] 3) This utility model utilizes proprietary heat exchanger technology and reasonable technical design to recover 70% of the heat in the exhaust gas, heating the low-temperature original flue gas from 50°C to above 260°C, thus realizing the recovery and reuse of the waste heat of the exhaust gas and achieving the purpose of energy saving;

[0027] 4) Since low-temperature flue gas is corrosive before entering the heat exchanger, the utility model performs anti-corrosion treatment on the inner wall of the heat exchanger, and specially designs the heat exchange fins. The enamel anti-corrosion process is added to the special-shaped heat exchange fins to ensure the technical performance of the heat exchanger;

[0028] 5) This utility model uses temperature compensation heating technology and reasonable structural arrangement. If the flue gas temperature after the heat exchanger cannot reach the SCR denitrification inlet temperature of 280°C or above, appropriate temperature compensation heating is performed;

[0029] 6) This utility model fully utilizes the characteristics of SCR denitrification with high efficiency and low investment and operation cost. Through reasonable ammonia injection flow field design, temperature compensation heating flow field design, flue gas diversion design, etc., the denitrification reducing agent injection grid, flue gas flow field mixer, and flue gas flow field rectifier fully and evenly mix the flue gas, reducing agent, and high-temperature flue gas to achieve SCR high-efficiency denitrification;

[0030] 7) This utility model utilizes the high removal efficiency of the bag dust collector and its suitability for ultra-low emissions. It processes the low-temperature flue gas through condensation, heat exchange, and compensatory heating technologies, while ensuring that the temperature entering the bag dust collector is above the dew point temperature of 105°C. The humidity of the treated flue gas is far lower than the inlet index of the bag dust collector, thus achieving the rational, efficient and practical use of the bag dust collector.

[0031] 8) This utility model fully utilizes the chimney as a secondary condensation system to condense the moisture in the exhaust flue gas. The condensed water is collected and then enters the desulfurization circulation system. While saving water, the flue gas undergoes a two-stage condensation process, a temperature rise and fall heat exchange process, and a temperature compensation heating process. Without any investment in desulfurization treatment, it achieves a coordinated desulfurization treatment of flue gas.

[0032] 9) This utility model technology has been designed to be resource-based, and on the basis of desulfurization, denitrification and dust removal, it has achieved whitening treatment, thus avoiding the huge investment of enterprises in whitening treatment;

[0033] 10) The utility model is designed with two-stage condensation water process technology, which greatly reduces the water loss of wet desulfurization flue gas and greatly reduces the operating cost of the enterprise desulfurization system;

[0034] 11) This utility model recovers 70% of the waste heat in the exhaust flue gas through reasonable heat exchanger process design to heat the inlet flue gas, greatly reducing the operating cost of the enterprise's denitrification system;

[0035] 12) The utility model reserves space for catalyst filling in the denitrification reaction. When environmental protection indicators are improved in the later stage, only catalyst needs to be added to achieve lower emissions without the need for secondary modification, which greatly reduces the cost of subsequent modification for secondary improvement.

[0036] 13) The utility model opens up a new management concept for wet desulfurization and low-temperature flue gas treatment, realizes resource-based and diversified energy-saving and water-saving management, and provides valuable technology for wet desulfurization and low-temperature flue gas desulfurization, denitrification, dust removal, and whitening treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural diagram of the present utility model.

[0038] Figure 1: Desulfurization circulation pool; 2: Desulfurization spray system; 3: Desulfurization liquid reflux system; 4: Desulfurization tower; 5: Primary condensation system; 6: Denitrification reducing agent injection grid; 7: Flue gas flow mixer; 8: Temperature compensation heating system; 9: SCR denitrification catalyst 1; 10: SCR denitrification catalyst 2; 11: Flue gas flow rectifier; 12: SCR denitrification catalyst reserved space; 13: Low temperature side inlet of heat exchanger; 14: Bag filter; 15: Induced draft fan Power system; 16—Secondary condensation system; 17—Primary condensation system return water system; 18—Secondary condensation system return water system; 19—Connecting flue one; 20—DeNOx reducing agent storage system; 21—DeNOx reducing agent injection system; 22—High-temperature side outlet of heat exchanger; 23—Low-temperature side outlet of heat exchanger; 24—High-temperature side inlet of heat exchanger; 25—Heat exchanger; 26—Connecting flue two; 27—Connecting flue three; 28—Connecting flue four; 29—Reactor. DETAILED DESCRIPTION

[0039] The structural principle and working principle of the present invention are further described in detail below with reference to the accompanying drawings and embodiments.

[0040] See also Figure 1 A novel low-temperature denitrification, dust removal and whitening process device after wet desulfurization includes a desulfurization spray system 2 connected to a desulfurization circulation pool 1, a desulfurization liquid reflux system 3, a primary condensation system return water system 17 and a secondary condensation system return water system 18; the outlet of the desulfurization spray system 2 is connected to the left flue gas inlet of the desulfurization tower 4; the top flue gas outlet of the desulfurization tower 4 is connected to the low-temperature side inlet 13 of the heat exchanger through a connecting flue 19, a primary condensation system 5 and a pipe 1 in sequence; the low-temperature side outlet 23 of the heat exchanger is connected to a temperature compensation heating system 8, a denitrification reducing agent ammonia spraying grid 6, a flue gas flow field mixer 7, and a flue gas flow field rectifier 11; the flue gas flow field rectifier 11 The lower side is a reserved space 12 for the SCR denitration catalyst; the lower part of the SCR denitration catalyst reserved space 12 is sequentially provided with an SCR denitration catalyst 1 9 and an SCR denitration catalyst 2 10; a denitration reducing agent storage system 20 sprays the reducing agent into the denitration reducing agent injection grid 6 via a denitration reducing agent injection system 21; the outlet end of the reactor 29 is connected to the high-temperature side inlet 24 of the heat exchanger; the high-temperature side outlet 22 of the heat exchanger is connected to the bag filter 14 via a connecting flue 2 26; the outlet of the bag filter 14 is connected to the secondary condensation system (chimney) 16 via a connecting flue 3 27, an induced draft fan power system 15, and a connecting flue 4 28;

[0041] The pipeline of the desulfurization liquid reflux system 3 is connected to the bottom of the desulfurization tower 4; the outlet pipelines of the primary condensation system return water system 17 and the secondary condensation system return water system 18 are respectively connected to the desulfurization circulation pool 1.

[0042] The second pipeline is provided with a denitrification reducing agent injection grid 6 and a flue gas flow field mixer 7 ; the denitrification reducing agent injection grid 6 is connected to the denitrification reducing agent storage system 20 through a denitrification reducing agent injection system 21 .

[0043] The temperature compensation heating system 8 is connected to the low temperature side outlet 23 of the heat exchanger.

[0044] The heat exchanger's high-temperature outlet 22 is connected to the bag filter 14 via a second flue duct 26. The heat exchanger's high-temperature inlet 24 is connected to the reactor 29. The heat exchanger's low-temperature outlet 23 is connected to the temperature-compensating heating system 8. The heat exchanger's low-temperature inlet 13 is connected to the primary condensing system 5. The desulfurized low-temperature flue gas and the denitrified high-temperature flue gas undergo heat exchange via the heat exchanger 25.

[0045] The reactor 29 is provided with a reserved space 12 for SCR denitration catalyst, a SCR denitration catalyst 1 9, and a SCR denitration catalyst 2 10.

[0046] The heat exchanger 25 realizes heat exchange through the rotating heating surface.

[0047] The working principle of this utility model is as follows: Figure 1 , the arrows in the figure indicate the direction of flue gas flow

[0048] 1. Desulfurization:

[0049] Under the action of the induced draft fan power system 15, the flue gas passes through the desulfurization tower 4. The desulfurization liquid in the desulfurization circulation pool 1 is sprayed into the desulfurization tower 4 through the desulfurization spray system 2 and fully mixed with the flue gas to complete the desulfurization ultra-low emission. This achieves ultra-low emission control of sulfur dioxide. The desulfurized liquid is returned to the desulfurization circulation pool 1 through the desulfurization liquid reflux system 3.

[0050] 2. Initial condensation:

[0051] Wet desulfurization and low-temperature flue gas are cooled and condensed through the connected flue duct 19 and the primary condensation system 5, and the condensed water is returned to the desulfurization circulation pool 1 through the primary condensation system return system 17, thereby achieving the purpose of preliminary water saving and reducing the humidity of the flue gas;

[0052] 3. Denitrification reducing agent injection system:

[0053] After the denitration system is started and reaches the operating temperature, the reducing agent stored in the denitration reducing agent storage system 20 enters the denitration reducing agent injection grid 6 after passing through the denitration reducing agent injection system 21, and the reducing agent is sprayed into the reactor through atomization and evaporation;

[0054] 4. Denitrification:

[0055] After condensation, the wet desulfurized and low-temperature flue gas enters the low-temperature side inlet 13 of the heat exchanger through the connecting flue 19, is heated in the heat exchanger 25, and enters the temperature compensation heating system 8 through the low-temperature side outlet 23 of the heat exchanger. If the temperature does not meet the requirements, it continues to be compensated and heated to the SCR denitrification reaction temperature. The flue gas after compensation heating enters the flue gas flow field mixer 7 to complete the forced uniform mixing of the flue gas, reducing agent, and high-temperature flue gas. After being rectified by the flue gas flow field rectifier 11, it enters the SCR denitrification catalyst reserved space 12, SCR denitrification catalyst 1 9, and SCR denitrification catalyst 2 10 to complete denitrification and achieve ultra-low emission control of nitrogen oxides. The high-temperature flue gas after denitrification enters the heat exchanger 25 through the high-temperature side inlet 24 of the heat exchanger for heat exchange, and then enters the connecting flue 2 26 through the high-temperature side outlet 22 of the heat exchanger. The waste heat of the discharged flue gas is reused, achieving the purpose of energy-saving control;

[0056] 5. Dust removal

[0057] The flue gas, whose temperature and humidity meet the dust removal inlet requirements, enters the bag filter 14 through the connecting flue 26 to complete the dust removal and achieve ultra-low emission control of particulate matter. The clean flue gas after dust removal enters the connecting flue 3 27.

[0058] 6. Secondary condensation and de-whitening treatment

[0059] After desulfurization, denitrification, and dust removal, the clean flue gas enters the secondary condensation system (chimney) 16 through the connecting flue duct 4 28. The condensed clean flue gas meets the discharge standards. The condensed water flows back to the desulfurization circulation tank 1 through the secondary condensation system return water system 18, achieving secondary water conservation.

[0060] 7. Collaborative whitening management

[0061] After the wet desulfurized flue gas passes through the primary condensation system 5, heat exchanger 25, temperature compensation heating system 8, and secondary condensation system (chimney) 16, a large amount of water in the flue gas is extracted after two condensation cycles and temperature rise and fall. Simultaneously, the exhaust flue gas temperature is much higher than the inlet flue gas temperature. The flue gas humidity content meets the requirements for whitening treatment, and the visual appearance of the flue gas no longer appears white. Through the technical treatment of desulfurization, denitrification, and dust removal, the flue gas whitening treatment is achieved simultaneously.

Claims

1. A low-temperature denitrification, dust removal and whitening process device after wet desulfurization, characterized in that: The invention comprises a desulfurization spray system (2) connected to a desulfurization circulation pool (1), a desulfurization liquid reflux system (3), a primary condensation system return water system (17) and a secondary condensation system return water system (18); the outlet of the desulfurization spray system (2) is connected to the flue gas inlet on the left side of the desulfurization tower (4); the flue gas outlet on the top of the desulfurization tower (4) is connected to the low-temperature side inlet (13) of the heat exchanger through a connecting flue duct (19), a primary condensation system (5) and a pipe (1); the low-temperature side outlet (23) of the heat exchanger is connected to a temperature compensation heating system (8), a denitrification reducing agent injection grid (6), a flue gas flow field mixer (7) and a flue gas flow field rectifier (11); the lower side of the flue gas flow field rectifier (11) is an SCR denitrification catalyst. The SCR denitration catalyst reserved space (12); the lower part of the SCR denitration catalyst reserved space (12) is provided with an SCR denitration catalyst 1 (9) and an SCR denitration catalyst 2 (10) in sequence; the denitration reducing agent storage system (20) sprays the reducing agent into the denitration reducing agent injection grid (6) through the denitration reducing agent injection system (21); the outlet end of the reactor (29) is connected to the high-temperature side inlet (24) of the heat exchanger; the high-temperature side outlet (22) of the heat exchanger is connected to the bag filter (14) through the connecting flue 2 (26); the outlet of the bag filter (14) is connected to the secondary condensation system (16) through the connecting flue 3 (27), the induced draft fan power system (15), and the connecting flue 4 (28); The desulfurization liquid reflux system (3) pipeline is connected to the bottom of the desulfurization tower (4); the outlet pipelines of the primary condensation system return water system (17) and the secondary condensation system return water system (18) are respectively connected to the desulfurization circulation pool (1).

2. A low-temperature denitrification, dust removal and whitening process device after wet desulfurization according to claim 1, characterized in that: The low-temperature side outlet (23) has a denitrification reducing agent injection grid (6) and a flue gas flow field mixer (7) in the upper pipe 2; the denitrification reducing agent injection grid (6) is connected to the denitrification reducing agent storage system (20) through the denitrification reducing agent injection system (21).

3. The low-temperature denitrification, dust removal and whitening process device after wet desulfurization according to claim 1 is characterized in that: The system is added with a temperature compensation heating system (8) connected to the low temperature side outlet (23) of the heat exchanger.

4. A low-temperature denitrification, dust removal and whitening process device after wet desulfurization according to claim 1, characterized in that: The high-temperature side outlet (22) of the heat exchanger is connected to the bag filter (14) via the second connecting flue (26), the high-temperature side inlet (24) of the heat exchanger is connected to the reactor (29), the low-temperature side outlet (23) of the heat exchanger is connected to the temperature compensation heating system (8), and the low-temperature side inlet (13) of the heat exchanger is connected to the primary condensation system (5).

5. The low-temperature denitrification, dust removal and whitening process device after wet desulfurization according to claim 1 is characterized in that: The reactor (29) is provided with a reserved space for an SCR denitration catalyst (12), an SCR denitration catalyst 1 (9), and an SCR denitration catalyst 2 (10).

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