Ultra-clean exhaust system for flue gas of industrial kiln

Abstract

The industrial kiln flue gas ultra-clean emission system comprises a low-temperature catalytic oxidation device, an absorption tower, a waste heat recovery device and a dehydration and denitration device, electromagnetic valves are arranged at an inlet and an outlet of the low-temperature catalytic oxidation device, and the electromagnetic valves are connected with a flue gas communication pipeline; the low-temperature catalytic oxidation device is connected with the absorption tower through the flue gas communicating pipe, the absorption tower is communicated with the waste heat recovery device, and the waste heat recovery device is communicated with the dehydration and denitration device. Efficient desulfurization and denitrification are achieved through the low-temperature catalysis technology, heat obtained through waste heat recovery is reused in the desulfurization and denitrification process, and waste heat is efficiently recovered and comprehensively utilized while ultra-clean emission of flue gas is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of resource and environmental protection, and in particular to an ultra-clean emission system for industrial furnace fume. Background Art

[0002] With the global emphasis on environmental protection and sustainable development, countries have introduced strict energy-saving and emission-reduction policies, requiring industrial enterprises to reduce energy consumption and pollutant emissions. In this context, the development of efficient industrial furnace flue gas ultra-clean emission and waste heat recovery and comprehensive utilization technology has become an inevitable choice for industrial enterprises.

[0003] The desulfurization and denitrification technology and waste heat recovery technology of the traditional flue gas purification system can no longer meet the requirements for energy conservation, emission reduction and environmental protection. The traditional flue gas purification system has the following disadvantages: 1. Some traditional desulfurization and denitrification technologies are not thorough enough in removing pollutants in flue gas, making it difficult to meet increasingly stringent environmental protection standards. They are not effective in removing pollutants with low content, resulting in a certain amount of harmful components in the emitted flue gas, causing environmental pollution.

[0004] 2. Some desulfurization technologies are difficult to remove all pollution at one time during operation, and the flue gas with residual pollution may be discharged into the atmosphere, which may cause secondary pollution to the environment.

[0005] 3. During the low-temperature catalytic oxidation process, the long-term catalytic reaction will lead to a decrease in the activity of the catalyst, thereby reducing its catalytic efficiency, failing to achieve the effect of converting the pollutants in the flue gas, and making the flue gas purification incomplete.

[0006] 4. Traditional waste heat recovery technology and flue gas treatment system are independent of each other and lack overall optimization design of the system, which affects the effects of waste heat recovery and flue gas treatment and the comprehensive utilization efficiency of energy is low. Summary of the invention

[0007] The purpose of the present invention is to solve the above-mentioned problems and to propose an ultra-clean exhaust system for industrial furnace flue gas.

[0008] In order to achieve the above purpose, the following technical solutions are adopted: An ultra-clean emission system for flue gas from an industrial kiln comprises a low-temperature catalytic oxidation device, an absorption tower, a waste heat recovery device and a dehydration and denitrification device. Solenoid valves are provided at the inlet and outlet of the low-temperature catalytic oxidation device, and the solenoid valves are connected to a flue gas connecting device. The low-temperature catalytic oxidation device is connected to the absorption tower through the flue gas connecting pipe, and the absorption tower is connected to the waste heat recovery device, and the waste heat recovery device is connected to the dehydration and denitrification device.

[0009] Preferably, the low-temperature catalytic oxidation device is provided with two sets and is connected by a solenoid valve. The low-temperature catalytic oxidation device includes a gas distribution layer, a catalyst bed layer, a heating device No. 1 and a heating device No. 2, which are the gas distribution layer, the catalyst bed layer and the heating device No. 1 from bottom to top.

[0010] Preferably, the interior of the catalyst bed is filled with a low-temperature SCR catalyst, the temperature of which is usually 120-200°C, the interior of the catalyst bed is equipped with the No. 2 heating device, a control valve is installed in the middle of the No. 2 heating device, and the No. 1 heating device and the No. 2 heating device are respectively connected to the waste heat recovery device.

[0011] Preferably, the absorption tower includes a tower body, a No. 1 spray device, a demister and an absorption liquid storage tank, the No. 1 spray device is arranged inside the tower body, and the demister is arranged on the top of the tower body.

[0012] Preferably, the No. 1 spray device is equipped with a nozzle, the absorption liquid inside the No. 1 spray device is one of sodium hydroxide or ammonia water, and the other end of the demister is connected to the flue gas connecting pipe.

[0013] Preferably, the waste heat recovery device includes a heat pipe heat exchanger, a medium circulation system and a medium delivery pipeline. The heat pipe heat exchanger is located inside the waste heat recovery device and is installed on the flue gas connecting pipeline. The medium circulation system is installed on the top of the waste heat recovery device. The medium circulation system is connected to the heat pipe heat exchanger through the medium delivery pipeline.

[0014] Preferably, the medium in the heat pipe heat exchanger is water or heat transfer oil, and the outlet of the heat pipe heat exchanger is respectively connected to the first heating device and the third heating device through the medium delivery pipeline.

[0015] Preferably, the medium circulation system comprises a liquid storage tank and a circulation pump, the liquid storage tank is arranged at the top of the waste heat recovery device, and the circulation pump is arranged at the outlet of the heat pipe heat exchanger.

[0016] Preferably, the dehydration and denitration device includes a dehydration unit and a denitration unit, the dehydration unit includes a No. 3 heating device and a molecular sieve, the No. 3 heating device is installed on the flue gas connecting pipe, and the molecular sieve is installed between the dehydration unit and the denitration unit.

[0017] Preferably, a No. 2 spray device is installed inside the denitration unit, the reducing agent sprayed by the No. 2 spray device is ammonia water, and the No. 2 spray device is connected to a liquid ammonia storage tank.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: the system first adopts low-temperature catalytic oxidation technology, which can efficiently and selectively convert NOx and part of SO2 in flue gas into high-valent nitrogen oxides and sulfates at a relatively low temperature, and then utilizes alkaline absorption liquid to react with high-valent nitrogen oxides and sulfates in the flue gas to generate sodium sulfite, sodium nitrite, sodium nitrate and water; low-temperature catalytic oxidation technology realizes preliminary desulfurization and denitrification, and the absorption treatment can remove high-valent nitrogen oxides and sulfates in the flue gas, and also increases the temperature of the flue gas. On this basis, subsequent deep treatments such as flue gas dehydration and denitrification can further reduce pollutant emissions; the heat recovered by the waste heat recovery device can not only be used for conventional energy recovery, but also can be introduced into the ultra-clean emission system of industrial kiln flue gas. By controlling the temperature of the recovered heat, the efficiency and rate of the chemical reaction in the system are promoted, the comprehensive utilization of waste heat is realized, and the energy utilization efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of an ultra-clean exhaust system for industrial furnace flue gas according to Example 1 of the present invention; Figure 2 This is a schematic diagram of a low-temperature catalytic oxidation device of an ultra-clean exhaust system for industrial furnace flue gas according to Example 1 of the present invention; Figure 3 This is a schematic diagram of an absorption tower of an ultra-clean exhaust system for industrial furnace flue gas according to Example 1 of the present invention; Figure 4 Schematic diagram of a waste heat recovery device for an ultra-clean exhaust system of industrial furnace flue gas in Example 1 of the present invention Figure 5 Schematic diagram of a dehydration and denitration device of an ultra-clean exhaust system for industrial furnace flue gas in Example 1 of the present invention DETAILED DESCRIPTION

[0020] Hereinafter, a light-cured hollow glass microsphere reinforced bio-based resin composite material and a preparation method thereof of the present invention will be described in detail with reference to the accompanying drawings.

[0021] like Figure 1 As shown, the industrial furnace flue gas ultra-clean emission system includes a low-temperature catalytic oxidation device 1, an absorption tower 2, a waste heat recovery device 3 and a dehydration and denitrification device 4. Solenoid valves 6 are provided at the inlet and outlet of the low-temperature catalytic oxidation device 1. The solenoid valve 6 is connected to a flue gas connecting pipe 5. The low-temperature catalytic oxidation device 1 is connected to the absorption tower 2 through the flue gas connecting pipe 5. The absorption tower 2 is connected to the waste heat recovery device 3, and the waste heat recovery device 3 is connected to the dehydration and denitrification device 4.

[0022] like Figure 2As shown, two sets of low-temperature catalytic oxidation devices 1 are provided and connected by a solenoid valve 6. The low-temperature catalytic oxidation device 1 includes a gas distribution layer 11, a catalyst bed 12, a No. 1 heating device 13 and a No. 2 heating device 14, which are the gas distribution layer 11, the catalyst bed 12 and the No. 1 heating device 13 from bottom to top; the interior of the catalyst bed 12 is filled with a low-temperature SCR catalyst, and the temperature is usually 120~250℃, the interior of the catalyst bed 12 is equipped with a No. 2 heating device 14, and a control valve 141 is installed in the middle of the No. 2 heating device, and the No. 1 heating device 13 and the No. 2 heater 14 are respectively connected to the waste heat recovery device 3.

[0023] like Figure 3 As shown, the absorption tower 2 includes a tower body 21, a No. 1 spray device 22, a demister 23 and an absorption liquid storage tank 24. The No. 1 spray device 22 is arranged inside the tower body 21, and the demister 23 is arranged on the top of the tower body 21; the No. 1 spray device 22 is equipped with a nozzle 221, and the absorption liquid sprayed by the No. 1 spray device 22 adopts one of sodium hydroxide or ammonia water, and the end of the demister 23 is connected to the flue gas connecting pipe 5.

[0024] like Figure 4 As shown, the waste heat recovery device 3 includes a heat pipe heat exchanger 31, a medium circulation system 32 and a medium delivery pipeline 33. The heat pipe heat exchanger 31 is located inside the waste heat recovery device 3 and is installed on the flue gas connecting pipeline 5. The medium circulation system 32 is arranged above the waste heat recovery device 3, and the medium circulation system 32 is connected to the heat pipe heat exchanger 31 through the medium delivery pipeline 33; the medium in the heat pipe heat exchanger 31 is one of water or heat transfer oil, and the outlet of the heat pipe heat exchanger 3 is respectively connected to the No. 1 heating device 13 and the No. 3 heating device 411 through the medium delivery pipeline 33; the medium circulation system 32 includes a liquid storage tank 321 and a circulation pump 322, the liquid storage tank 321 is installed on the top of the waste heat recovery device 3, and the circulation pump 322 is installed at the outlet of the heat pipe heat exchanger 3.

[0025] like Figure 5 As shown, the dehydration and denitrification device 4 includes a dehydration unit 41 and a denitrification unit 42. The dehydration unit 41 includes a No. 3 heating device 411 and a molecular sieve 412. The No. 3 heating device 411 is installed on the flue gas connecting pipe 5, and the molecular sieve 412 is installed between the dehydration unit 41 and the denitrification unit 42. A No. 2 spraying device 421 is installed inside the denitrification unit 42. The reducing agent sprayed by the No. 2 spraying device 421 is ammonia water. The No. 2 spraying device 421 is connected to a liquid ammonia storage tank 422.

[0026] Specifically, a traditional flue gas purification system usually includes a pretreatment device, a dust removal device, a desulfurization device, a denitrification device, a waste heat recovery device and other auxiliary equipment. The present invention innovates the traditional desulfurization and denitrification technology and the utilization of waste heat recovery, but does not innovate other devices.

[0027] In this embodiment, the flue gas after dust removal enters the available low-temperature catalytic oxidation device 1 through the solenoid valve 6. The flue gas passes through the gas distribution layer 11 and is evenly distributed on the catalyst bed 12. The low-temperature SCR catalyst in the catalyst bed 12 converts NOx and part of SO2 in the flue gas into high-valent nitrogen oxides and sulfates. During the conversion process, the heating of the No. 1 heating device can improve the efficiency of catalytic oxidation.

[0028] When the activity of the catalyst in the catalyst bed 12 decreases after a long period of catalytic action, the solenoid valve 6 will introduce the flue gas into another set of low-temperature catalytic oxidation device 1. At this time, the No. 2 heating device 14 heats the catalyst bed 12 that is not in working state through the control valve to restore the activity of the catalyst.

[0029] The flue gas after catalytic oxidation enters the absorption tower 2 through the flue gas connecting pipe 5. The No. 1 spray device 22 in the tower can spray out alkaline absorption liquid sodium hydroxide, which can react chemically with high-valent nitrogen oxides and sulfates in the flue gas to remove pollutants in the flue gas and release heat. The flue gas after the reaction passes through the demister 23 and enters the flue gas connecting pipe 5. The demister 23 can remove droplets and particulate matter in the flue gas to prevent them from polluting subsequent equipment.

[0030] Then the flue gas enters the waste heat recovery device 3, and the high-temperature flue gas passes through the heat pipe heat exchanger 31. The heat in the flue gas is transferred to the medium water in the heat pipe heat exchanger 31 by using the heat pipe technology. The medium circulation system 32 transports the circulated heated water to the low-temperature catalytic oxidation device 1 and the subsequent dehydration and denitrification device 4 through the circulation pump 322. The circulated water will be recovered into the liquid storage tank 321.

[0031] The flue gas will finally enter the dehydration and denitrification device 4. After entering the dehydration unit 41, it will be heated by the No. 3 heating device 411. The molecular sieve 412 will absorb the moisture in the flue gas to dehydrate the flue gas. The dehydrated flue gas enters the denitrification unit 42. The No. 2 spraying device 421 in the denitrification unit 42 can spray the reducing agent ammonia water. The heated flue gas reacts rapidly after contacting with the ammonia water. The NOx in the flue gas is reduced to nitrogen and water, and finally discharged into the atmosphere after meeting the ultra-clean emission standards.

[0032] The above description is only a preferred example of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have other optimization schemes and additional functions. 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. The ultra-clean exhaust system of industrial furnace flue gas usually includes a pretreatment device, a dust removal device, a desulfurization device, a denitrification device, a waste heat recovery device and other auxiliary equipment. The present invention innovates the desulfurization and denitrification technology and the waste heat recovery technology, and is characterized by: The invention comprises a low-temperature catalytic oxidation device (1), an absorption tower (2), a waste heat recovery device (3) and a dehydration and denitration device (4), wherein electromagnetic valves (6) are arranged at the inlet and outlet of the low-temperature catalytic oxidation device (1), and the electromagnetic valves (6) are connected to a flue gas communication pipe (5); the low-temperature catalytic oxidation device (1) is connected to the absorption tower (2) via the flue gas communication pipe (5); the absorption tower (2) is connected to the waste heat recovery device (3), and the waste heat recovery device (3) is connected to the dehydration and denitration device (4).

2. The industrial furnace fume ultra-clean emission system according to claim 1, characterized in that: The low-temperature catalytic oxidation device (1) is provided with two sets and is connected via the solenoid valve (6). The low-temperature catalytic oxidation device (1) comprises a gas distribution layer (11), a catalyst bed layer (12), a first heating device (13) and a second heating device (14), which are, from bottom to top, the gas distribution layer (11), the catalyst bed layer (12) and the first heating device (13).

3. The industrial furnace fume ultra-clean emission system according to claim 2, characterized in that: The catalyst bed (12) is filled with a low-temperature SCR catalyst, the temperature of which is usually between 120°C and 250°C. The catalyst bed (12) is provided with the second heating device (14), a control valve (141) is provided in the middle of the second heating device (14), and the first heating device (13) and the second heating device (14) are respectively connected to the waste heat recovery device (3).

4. The industrial furnace fume ultra-clean exhaust system according to claim 1, characterized in that: The absorption tower (2) comprises a tower body (21), a No. 1 spray device (22), a demister (23) and an absorption liquid storage tank (24), wherein the No. 1 spray device (22) is arranged inside the tower body (21), and the demister (23) is arranged on the top of the tower body (2).

5. The industrial furnace fume ultra-clean exhaust system according to claim 4, characterized in that: The first spray device (22) is provided with a nozzle (221), and the absorption liquid inside the first spray device (22) is one of sodium hydroxide and ammonia water. The other end of the demister (23) is connected to the flue gas communication pipe (5).

6. The industrial furnace fume ultra-clean exhaust system according to claim 1, characterized in that: The waste heat recovery device (3) comprises a heat pipe heat exchanger (31), a medium circulation system (32) and a medium delivery pipeline (33); the heat pipe heat exchanger (31) is located inside the waste heat recovery device (3) and is installed on the flue gas connecting pipeline (5); the medium circulation system (32) is arranged above the waste heat recovery device (3); and the medium circulation system (32) is connected to the heat pipe heat exchanger (3) via the medium delivery pipeline (33).

7. The industrial furnace fume ultra-clean exhaust system according to claim 6, characterized in that: The medium in the heat pipe heat exchanger (31) is water or heat transfer oil, and the outlet of the heat pipe heat exchanger (31) is respectively connected to the first heating device (13) and the third heating device (411) through the medium delivery pipeline (33).

8. The industrial furnace fume ultra-clean exhaust system according to claim 6, characterized in that: The medium circulation system (32) comprises a liquid storage tank (321) and a circulation pump (322); the liquid storage tank (321) is arranged at the top of the waste heat recovery device (3); and the circulation pump (322) is arranged at the outlet of the heat pipe heat exchanger (31).

9. The industrial furnace fume ultra-clean exhaust system according to claim 1, characterized in that: The dehydration and denitration device (4) comprises a dehydration unit (41) and a denitration unit (42); the dehydration unit (41) comprises a third heating device (411) and a molecular sieve (412); the third heating device (411) is installed on the flue gas connecting pipe (5); and the molecular sieve (412) is installed between the dehydration unit (41) and the denitration unit (42).

10. The industrial furnace fume ultra-clean exhaust system according to claim 9, characterized in that: The denitration unit (42) is internally provided with a second spray device (421), the reducing agent sprayed by the second spray device (421) is ammonia water, and the second spray device (421) is connected to a liquid ammonia storage tank (422).

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