Enhanced oxidation device applied to ammonia desulfurization

Abstract

The utility model relates to a strengthened oxidation device applied to ammonia desulfurization, which comprises an oxidant supply device, an oxidation device, a strengthened oxidation device and an oxidant distributor, the oxidant supply device is connected with the oxidant distributor, and the strengthened oxidation device is connected with the oxidant distributor in the oxidation process of desulfurization absorption liquid. The oxidation of ammonium sulfite (hydrogen) in the absorption liquid is enhanced by adopting ultrasonic waves and sound waves, and an oxidizing agent is used in the oxidation process and is oxygen, oxygen-enriched air and air; and air is preferably selected, so that the equipment investment and the power consumption of the circulating pump are reduced under the condition of realizing the same oxidation rate.

Description

Technical Field

[0001] The utility model relates to the field of flue gas desulfurization, in particular to a device for enhanced oxidation applied to ammonia-based desulfurization. Background Art

[0002] Currently, there are hundreds of mature desulfurization technologies, of which wet flue gas desulfurization is the most widely used, accounting for approximately 85% of the world's total installed desulfurization capacity. Common wet flue gas desulfurization technologies include the limestone-gypsum method, the double-alkali method, the sodium carbonate method, the ammonia method, and the magnesium oxide method. Ammonia desulfurization uses ammonia as an absorbent. This method can be used to produce ammonium sulfate fertilizer from SO2. It is a low-energy, high-value-added, and green flue gas treatment solution that achieves resource recycling. The chemical industry generates large amounts of waste ammonia during its production processes, so ammonia desulfurization of boiler exhaust gases in the chemical industry has unique advantages.

[0003] The ammonia desulfurization process is mainly divided into three steps: absorption, oxidation, and concentration (crystallization). First, ammonium sulfite is used to absorb sulfur dioxide to obtain a mixed solution of ammonium sulfite and ammonium bisulfite. After adding ammonia to neutralize, ammonium sulfite is obtained again:

[0004] (NH4)2SO3+H2O+SO2=2NH4HSO3

[0005] (NH4) X H(2-x)SO3+(2-x)NH3=(NH4)2SO3

[0006] The solution is passed through oxidizing air to oxidize ammonium sulfite to obtain ammonium sulfate:

[0007] (NH4)2SO3+1 / 2O2=(NH4)2SO4

[0008] The ammonium sulfate solution is concentrated, crystallized, solid-liquid separated and dried to obtain the final product ammonium sulfate.

[0009] The three processes of absorption, oxidation and concentration seem simple, but they actually affect each other. For a long time, in order to ensure the absorption efficiency, the absorption liquid has a high content of ammonium sulfite and free ammonia and a low content of ammonium sulfate. Although this is conducive to absorption, it is not conducive to oxidation and concentration.

[0010] The oxidation of ammonium sulfite is a critical step in ammonia-based desulfurization. Low oxidation rates can easily lead to ammonium sulfite decomposition, resulting in ammonia escape and aerosol formation. Traditional oxidation methods often utilize aeration tubes alone to oxidize ammonium sulfite. To achieve the required oxidation rate, the oxidation section or oxidation tank must be taller to increase the contact time between the oxidizing gas and the solution. This increases equipment investment and pump power consumption, increasing desulfurization costs.

[0011] Chinese invention patent CN02136906.2 proposes a method and apparatus for removing and recovering SO2 from flue gas. The method controls the concentration of ammonium sulfite between 0.1-5% (wt), preferably between 0.5-2.0%, to create conditions most conducive to oxidation and reduce energy consumption and investment. The resulting ammonium sulfite solution reacts with air to produce an ammonium sulfate solution. The compressed air pressure is generally between 0.05-0.2 MPa (gauge pressure), and the flow rate of the compressed air is 1-5 times, and more commonly 2-4 times, the theoretical amount required for ammonium sulfite oxidation. The oxidation reaction residence time is generally between 1-3 hours, preferably about 2 hours. Under these conditions, the oxidation rate can be greater than 95%. The concentration of the ammonium sulfate solution is generally between 5-20% (wt). This process has disadvantages such as large amounts of oxidizing air required, long oxidation time, difficulty in ensuring the air quality of the post-processing workshop due to the high oxidation rate, low concentration of the oxidizing solution, high investment, and high operating costs.

[0012] CN201520771658.2 discloses a desulfurization tower for high-concentration sulfur-containing flue gas, comprising a flue gas inlet, a desulfurization tower mounting frame, a spray head, a spray water inlet pipe, an ultrasonic reactor, a granite filter, and an alkaline adhesion layer. The reactant inlet of the ultrasonic reactor is connected to the exhaust port of the desulfurization tower via a pipeline, and the ultrasonic reactor is mounted next to the exhaust port of the desulfurization tower via a reactor bracket. The ultrasonic reactor in this solution is installed after the desulfurization tower. Through the vibration of the ultrasonic device, the oxidant and catalyst aqueous phase in the ultrasonic reactor are mixed with the sulfur-containing flue gas. The aqueous solution after the reaction, including sulfone and sulfate, is discharged through the reactant outlet. The ultrasonic reactor is not used to enhance the oxidation of ammonium sulfite solution.

[0013] Chinese utility model patent CN200820081420.7 proposes a novel ammonia-based desulfurization and ammonium sulfite oxidation tower, comprising a housing (1), a sieve plate (2), a microporous aeration device (3), an oxidation temperature regulating tube (4) directly heated by a steam pipe and placed between the microporous aeration device (3) and the single-layer sieve plate (2), and other components; the sieve plate (2) placed above the microporous aeration device (3) is a single-layer sieve plate made of PP and HPDE polymer materials punched by a laser. A catalyst is added to the tower body (1), and oxidizing air is introduced from the bottom of the tower body (1) to oxidize ammonium sulfite into ammonium sulfate. This process has the disadvantages of using a catalyst affecting product quality, increasing energy consumption due to steam heating, large investment, and high operating costs.

[0014] Therefore, it is necessary to select a more appropriate oxidation process to reduce the investment and operating costs of oxidation equipment. Utility Model Content

[0015] In order to solve the above problems, the utility model proposes an enhanced oxidation device for ammonia desulfurization, which reduces equipment investment and circulation pump power consumption while achieving the same oxidation effect.

[0016] The principle of ultrasonic enhanced oxidation is that under the action of ultrasound, the tiny bubble nuclei in the liquid vibrate. When the sound pressure reaches a certain value, the bubble will continue to expand and then suddenly close, generating a shock wave (i.e., ultrasonic cavitation) when the bubble closes. When the small bubble collapses rapidly, a high temperature of 5000°C and a high pressure of more than 1000 atmospheres are generated inside the bubble. The liquid around the bubble rushes into the bubble at high speed, and a strong local shock wave is generated in the liquid near the bubble, forming a local high temperature and high pressure, which promotes the dissolution of oxygen and the oxidation reaction.

[0017] feature:

[0018] An enhanced oxidation device applied to ammonia desulfurization comprises an oxidant supply device, an oxidation device, and an enhanced oxidation device.

[0019] The oxidation device is a tank-type container, comprising an oxidant distributor for dispersing the oxidant entering the oxidation device.

[0020] The oxidant distributor adopts an aeration structure.

[0021] The enhanced oxidation equipment uses a sonic / ultrasonic generator.

[0022] The sonic / ultrasonic wave generator is of focused energy type.

[0023] The sonic / ultrasonic generator is located in the oxidation tank, above the oxidant distributor and below the liquid level.

[0024] Multiple sonic / ultrasonic wave generating devices can be set on the same horizontal cross section of the oxidation tank and arranged evenly on the cross section.

[0025] The sonic / ultrasonic wave generating equipment can be arranged on multiple horizontal sections of the oxidation tank.

[0026] The oxidation of ammonium sulfite (bisulfite) in the ammonia desulfurization absorption liquid is enhanced by using ultrasonic waves. The frequency of the ultrasonic waves is 10-200 kHz, preferably 15-160 kHz, more preferably 18-120 kHz, and most preferably 20-100 kHz. The power of the ultrasonic wave generator is 10-5000 W, preferably 50-4000 W, and more preferably 100-3000 W.

[0027] An oxidant is used in the oxidation process, and the oxidant is oxygen, oxygen-enriched air, or air; preferably air.

[0028] The residence time of the absorption liquid in the oxidation equipment is 5 to 50 minutes, preferably 10 to 40 minutes, more preferably 12 to 30 minutes;

[0029] The amount of the oxidant added is 1.1-6 times, preferably 1.5-3 times, the theoretical amount of the oxidant required for oxidation by ammonium (bisulfite).

[0030] The ammonium sulfite (bisulfite) content in the absorption liquid is 0.1-20%, and the ammonium sulfate content is 2-38%; the ammonium sulfite (bisulfite) content in the absorption liquid is preferably 0.5-10%; most preferably 1-5%;

[0031] While using an oxidant to oxidize ammonium sulfite (bisulfate) in the oxidation absorption liquid into ammonium sulfate (bisulfate), one or more of ultrasonic waves, infrasound waves, ultraviolet light, infrared light, electron beams, plasma flows, etc. are used to enhance the oxidation effect. While achieving the same oxidation rate, the oxidation contact time is reduced, thereby reducing the height of the oxidation section (tank) and the desulfurization tower and reducing the desulfurization cost.

[0032] A gas-liquid uniform distribution device, such as a perforated sieve plate, is set in the liquid phase of the oxidation equipment to improve gas uniformity and gas-liquid contact.

[0033] When ultrasound is used as a means of enhanced oxidation, the device at least includes an oxidant supply device, an oxidation device, and an ultrasound / sound wave generating device. The specific steps are as follows:

[0034] 1. Absorb the circulating fluid into the oxidation equipment;

[0035] 2. The oxidizing air provided by the oxidant supply device enters the oxidation device and contacts the absorption circulating fluid, oxidizing the ammonium sulfite (bisulfite) in the absorption circulating fluid into ammonium sulfate (bisulfate). At the same time, the ultrasonic generator is turned on.

[0036] 3. The oxidized absorption circulating liquid can be completely fed into the pre-wash section of the desulfurization device for concentrated spraying, or part of it can be fed into the pre-wash section of the desulfurization device for concentrated spraying, and part of it can be fed into the absorption section for cyclic absorption;

[0037] 4. The oxidized air after the reaction is sent to the pre-wash section and / or absorption section of the desulfurization tower, mixed with the flue gas, and discharged after treatment.

[0038] The oxidation rate of ammonium sulfite (bisulfite) in the absorption circulation liquid (ammonium sulfate molar ratio) can reach more than 99%.

[0039] The present utility model also relates to the following implementation schemes.

[0040] 1. An enhanced oxidation device for ammonia-based desulfurization, characterized in that it includes an oxidant supply device, an oxidation device, an enhanced oxidation device, and an oxidant distributor, wherein the oxidant supply device is connected to the oxidant distributor.

[0041] 2. The device as described in embodiment 1 is characterized in that the oxidant distributor is an aeration device.

[0042] 3. The apparatus according to embodiment 1 or 2, wherein the enhanced oxidation device is located inside the oxidation device, above the oxidant distributor and below the liquid level.

[0043] 4. The device as described in any one of embodiments 1 to 3 is characterized in that a plurality of the enhanced oxidation devices are provided on the same horizontal cross-section of the oxidation device and are evenly arranged on the cross-section.

[0044] 5. The apparatus according to any one of embodiments 1 to 4, wherein the enhanced oxidation device is arranged on multiple horizontal sections of the oxidation device.

[0045] 6. The device as described in any one of embodiments 1 to 5 is characterized in that the oxidation equipment includes an oxidation tower (tank), which includes a tower body, an oxidation chamber is formed in the tower body, and an absorption liquid inlet, an absorption liquid outlet, and an oxidant inlet are provided on the tower body.

[0046] 7. The device as described in any one of embodiments 1 to 6 is characterized in that the enhanced oxidation equipment is any one of a sonic / ultrasonic wave generating equipment, an infrared generating equipment, an ultraviolet generating equipment and an electron beam generating equipment, or a combination of any multiple thereof.

[0047] 8. The device as described in embodiment 7 is characterized in that the ultrasonic frequency of the sound wave / ultrasonic wave generating device is 10 to 200 kHz, preferably 15 to 160 kHz, more preferably 18 to 120 kHz, still more preferably 20 to 100 kHz, and most preferably 60 to 85 kHz.

[0048] 9. The device as described in Embodiment 7 is characterized in that the sound wave / ultrasonic wave generating device is a focused sound wave / ultrasonic wave generating device. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is an illustration of the implementation scheme in Example 1 of the present application.

[0050] Figure 2 This is an illustration of the implementation scheme in Example 2 of the present application.

[0051] 1. Oxidation equipment; 2. Ultrasonic / sound wave generating equipment; 3. Oxidant inlet; 4. Aeration equipment; 5. Absorption liquid inlet; 6. Absorption liquid entering equipment; 7. Gas-liquid distribution equipment; 8. Absorption liquid outlet; 9. Oxidant outlet. DETAILED DESCRIPTION

[0052] like Figure 1As shown, it mainly includes oxidation equipment 1, ultrasonic / sound wave generating equipment 2, oxidant inlet 3, aeration equipment 4, absorption liquid inlet 5, absorption liquid inlet equipment 6, gas-liquid distribution equipment 7, absorption liquid outlet 8, and oxidant outlet 9.

[0053] The oxidation device 1 may be an oxidation section arranged inside the tower, or an oxidation tank / oxidation tower arranged outside the tower;

[0054] The ultrasonic / sound wave generating device 2 can be arranged in one or more layers and can be a continuous ultrasonic / sound wave device or a pulsed ultrasonic device;

[0055] Aeration equipment 4 is arranged on 1 layer;

[0056] The absorption liquid enters the device 6 through a perforated tube;

[0057] The gas-liquid distribution device 7 can select sieve plates, with 1-4 layers in total;

[0058] Ultrasonic frequency is 60-85kHz;

[0059] Air is used as the oxidant in the oxidation process;

[0060] Power is 1000W;

[0061] The residence time of the absorption liquid in the oxidation equipment is 24 minutes;

[0062] The amount of the oxidant added is 1.8-2.5 times the theoretical amount of oxidant required for oxidation with ammonium (bisulfite).

[0063] The absorption liquid contains 0.35% ammonium sulfite (bisulfite) and 21% ammonium sulfate.

[0064] Example 1

[0065] The device is used for ammonia desulfurization of boiler tail gas, and the boiler flue gas volume treated is 500000Nm 3 / h (standard state, wet basis, actual oxygen), using an external oxidation tank (as oxidation equipment) layout, the oxidation tank diameter is 5.6m, the amount of solution entering the oxidation tank is 1200m 3 / h, and the oxidation tank adopts Figure 1 The device shown.

[0066] The main process includes the following steps:

[0067] 1. The flue gas enters the absorption section of the desulfurization tower and comes into contact with the desulfurization absorption liquid. The SO2 in the flue gas is absorbed. The absorption liquid is then collected and introduced into the oxidation tank 1 through the absorption liquid inlet 5, and sprayed by the absorption liquid sprayer (as the absorption liquid enters the equipment) 6;

[0068] 2. Oxidizing air enters the oxidation tank 1 through the oxidant inlet 3 and is dispersed by the aeration device 4;

[0069] 3. The absorption liquid contacts the oxidizing air in countercurrent to oxidize the ammonium sulfite (bisulfite) in the absorption liquid into ammonium sulfate (bisulfate);

[0070] 4. On the sieve plate (serving as a gas-liquid distribution device) 7, the absorption liquid and the oxidizing air are dispersed again and fully contacted. At the same time, under the action of the ultrasonic generator 2, the oxidation reaction is further strengthened, and more than 99% of the ammonium sulfite (bisulfite) in the absorption liquid is oxidized;

[0071] 5. After the reaction, the absorption liquid enters the concentration section through the absorption liquid outlet 8 for concentration spraying, and the other part enters the absorption section for cyclic absorption;

[0072] 6. The oxidized air after the reaction is sent to the desulfurization tower and mixed with the flue gas and then discharged from the chimney.

[0073] After actual testing and analysis, the oxidation rate of ammonium sulfite (bisulfite) in the oxidation tank can reach 99.5%.

[0074] Example 2

[0075] The device is used for ammonia desulfurization of acid tail gas, and the boiler flue gas volume treated is 750000Nm 3 / h (standard state, wet basis, actual oxygen), adopting the built-in oxidation section (as oxidation equipment) layout, the desulfurization tower diameter is 7m, and the amount of solution entering the oxidation section is 1000m 3 / h, and the oxidation section adopts Figure 2 The device shown.

[0076] The main process includes the following steps:

[0077] 1. The flue gas enters the absorption section of the desulfurization tower. The SO2 in the flue gas is absorbed by the desulfurization absorption liquid. The absorption liquid flows by gravity from the absorption liquid inlet 5 into the oxidation section 1 and is sprayed by the absorption liquid sprayer (as the absorption liquid enters the equipment) 6;

[0078] 2. Oxidizing air enters the oxidation section 1 through the oxidant inlet 3 and is dispersed through the aeration holes 4;

[0079] 3. The absorption liquid contacts the oxidizing air in countercurrent to oxidize the ammonium sulfite (bisulfite) in the absorption liquid into ammonium sulfate (bisulfate);

[0080] 4. In the hollow structure (serving as a gas-liquid distribution device) 7 inside the tower, the absorption liquid is fully in contact with the oxidizing air. At the same time, under the action of the ultrasonic generator 2, the oxidation reaction is further enhanced, and more than 99% of the ammonium sulfite (bisulfite) in the absorption liquid is oxidized;

[0081] 5. After the reaction, the absorption liquid enters the concentration section through the absorption liquid outlet 8 for concentration spraying, and the other part enters the absorption section for cyclic absorption;

[0082] 6. The oxidized air after the reaction is mixed with the flue gas from the liquid collector (as the oxidant outlet) 9 and then discharged from the chimney.

[0083] After actual testing and analysis, the oxidation rate of ammonium sulfite (bisulfite) in the oxidation tank can reach 99.7%.

[0084] As shown in the above embodiments, the technical solution of the present invention achieves excellent ammonium (bisulfite) oxidation rate.

[0085] The above description is merely a preferred embodiment of the present invention. Once a skilled artisan understands the technical approach of the present invention, they will naturally be able to adapt the present invention to their specific needs. Therefore, any equivalent changes and modifications made within the scope of the present invention are still covered by the present invention.

Claims

1. A device for enhanced oxidation applied to ammonia desulfurization, characterized in that: The invention comprises an oxidant supply device, an oxidation device, an enhanced oxidation device and an oxidant distributor, wherein the oxidant supply device is connected to the oxidant distributor, and the enhanced oxidation device is located in the oxidation device, above the oxidant distributor and below the liquid level.

2. The device for enhanced oxidation applied to ammonia desulfurization according to claim 1, characterized in that: The oxidant distributor is an aeration device.

3. The device for enhanced oxidation applied to ammonia desulfurization according to claim 1 or 2, characterized in that: The enhanced oxidation devices are provided in plurality on the same horizontal cross section of the oxidation device and are evenly arranged on the cross section.

4. The device for enhanced oxidation applied to ammonia desulfurization according to claim 1 or 2, characterized in that: The enhanced oxidation equipment is arranged on multiple horizontal sections of the oxidation equipment.

5. The device for enhanced oxidation applied to ammonia desulfurization according to claim 1 or 2, characterized in that: The oxidation equipment includes an oxidation tower or an oxidation tank, which includes a tower body or a tank body, an oxidation chamber formed in the tower body or the tank body, and an absorption liquid inlet, an absorption liquid outlet, and an oxidant inlet are provided on the tower body or the tank body.

6. The device for enhanced oxidation applied to ammonia desulfurization according to claim 1 or 2, characterized in that: The enhanced oxidation device is any one of a sonic / ultrasonic wave generating device, an infrared generating device, an ultraviolet generating device and an electron beam generating device, or a combination of any multiple thereof.

7. The device for enhanced oxidation applied to ammonia desulfurization according to claim 6, characterized in that: The ultrasonic frequency of the sound wave / ultrasonic wave generating device is 10 to 200 kHz.

8. The device for enhanced oxidation applied to ammonia desulfurization according to claim 6, characterized in that: The ultrasonic frequency of the sonic / ultrasonic wave generating device is 15 to 160 kHz.

9. The device for enhanced oxidation applied to ammonia desulfurization according to claim 6, characterized in that: The ultrasonic frequency of the sonic / ultrasonic wave generating device is 18 to 120 kHz.

10. The device for enhanced oxidation applied to ammonia desulfurization according to claim 6, characterized in that: The ultrasonic frequency of the sound wave / ultrasonic wave generating device is 20 to 100 kHz.

11. The device for enhanced oxidation applied to ammonia desulfurization according to claim 6, characterized in that: The ultrasonic frequency of the sonic / ultrasonic wave generating device is 60 to 85 kHz.

12. The device for enhanced oxidation applied to ammonia desulfurization according to claim 6, characterized in that: The sonic / ultrasonic wave generating device is an energy-focusing sonic / ultrasonic wave generating device.

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