A slurry oxidation device and method for jet exhaust desulfurization tower

Abstract

The present invention discloses a jet exhaust desulfurization tower slurry oxidation device and method; comprising a desulfurization tower and a slurry pool at its lower part; multiple jet oxidation devices are arranged tangentially along the circumference of the slurry pool; the jet oxidation device first extracts the slurry in the slurry pool, mixes and oxidizes it with air in the slurry pool, and sprays the high-pressure mixed fluid into the neutralization zone in the tangential direction, and a uniform cyclone field is formed in the slurry along the inscribed circle direction for reoxidation, thereby replacing the role of the agitator and the large oxidation fan. The method and the device not only solve the problems of oxidation air duct blockage, uneven oxidation flow field, and high slurry temperature in traditional oxidation devices, but also improve the oxidation efficiency, and have the characteristics of small space occupation, low energy consumption, and simple system.

Description

Technical Field

[0001] The invention relates to an oxidation process in a wet flue gas desulfurization device, and in particular to a jet exhaust desulfurization tower slurry oxidation device and method. Background Art

[0002] With the rapid development of thermal power plants, SOx emissions have continued to increase. Excessive SOx emissions not only endanger human health, but also form acid rain. Acid rain can damage the ecological environment and cause huge economic losses. Industries such as metallurgy, papermaking, cement, shipbuilding, and ceramics also face huge flue gas desulfurization pressure.

[0003] The wet limestone / gypsum flue gas desulfurization system is the most widely used desulfurization system.

[0004] The oxidation system is one of the most important energy-consuming systems in the wet limestone / gypsum flue gas desulfurization system. Optimizing the existing oxidation system is of great significance for energy saving.

[0005] In the wet limestone / gypsum flue gas desulfurization system, there are mainly two oxidation processes: natural oxidation process and forced oxidation process.

[0006] In the traditional natural oxidation process, only a portion of the HSO3 in the slurry 2- Oxidized into SO4 in the absorption zone by the remaining oxygen in the flue gas 2- , the oxidation rate is low, which cannot make gypsum crystals grow rapidly, causing gypsum to adhere to the desulfurization equipment and cause equipment scaling, increasing the number of manual cleaning times for demisters, pump inlets and nozzles, and increasing the possibility of damage to the absorption tower lining and internal components due to scaling accumulation and shedding, while also increasing system maintenance costs. In addition, the natural oxidation product in the tower has a high sulfite content, is in a molten state and difficult to dehydrate, and is difficult to solidify, resulting in high processing costs.

[0007] In the forced oxidation process, a large forced oxidation fan must be installed. The oxidation air compressed by the oxidation fan has a high temperature. When the high-temperature oxidation air is blown into the slurry in the reaction tank, the slurry temperature and desulfurization efficiency are affected.

[0008] In the forced oxidation process, currently, pipe network jet type and agitator and air gun combined forced oxidation devices are widely used. These methods have the following disadvantages:

[0009] (1) Oxidation fans are required to provide oxidation air, which consumes a lot of energy;

[0010] (2) The oxidizing air is heated by the oxidizing fan and then enters the desulfurization tower, which will increase the slurry temperature and reduce the desulfurization reaction rate of the slurry. Many devices are forced to install slurry coolers;

[0011] (3) Structural blockage is prone to occur in pipes such as oxidation ducts;

[0012] (4) It is necessary to design a special water distribution system for flushing, which results in a complex pipe network, increased maintenance costs and initial investment;

[0013] (5) An agitator is required. In order to keep the slurry flowing, after startup, even if the absorption tower is shut down, the agitator must continue to operate, which makes the agitator easy to wear and increase maintenance costs;

[0014] (6) It is difficult to coordinate the contradiction between injecting sufficient air and preventing bubbles from being sucked into the circulation pump. When the volume of bubbles sucked into the circulation pump exceeds 3%, the liquid-gas ratio is reduced, aggravating the cavitation of the pump; when the oxidation air flow rate is adjusted to reduce the air sucked into the circulation pump, the oxidation rate is reduced, resulting in a decrease in desulfurization efficiency. In severe cases, it will also make it difficult to deslurry the gypsum. Summary of the invention

[0015] The purpose of the present invention is to overcome the above-mentioned shortcomings and deficiencies of the prior art and to provide a jet exhaust desulfurization tower slurry oxidation device and method.

[0016] The present invention gives full play to the advantages of both forced oxidation and natural oxidation processes, and provides an energy-saving and high-efficiency desulfurization slurry oxidation process which combines the advantages of both processes and overcomes their disadvantages.

[0017] The present invention can realize the full and rapid oxidation of calcium sulfite in the wet limestone / gypsum flue gas desulfurization system, eliminating the use of large oxidation fans and agitators, greatly simplifying the desulfurization system, solving the contradiction that the desulfurization slurry is heated by high-temperature oxidation wind and needs to be cooled again, and achieving the dual goals of energy saving and efficient oxidation.

[0018] The present invention is achieved through the following technical route:

[0019] A jet exhaust desulfurization tower slurry oxidation device comprises a desulfurization tower and a slurry pool at its lower part; a plurality of jet oxidation devices are tangentially arranged along the circumference of the slurry pool;

[0020] The jet oxidation device first extracts the slurry in the slurry pool, and jet mixes and oxidizes it with air. The oxidized slurry is then sprayed back to the bottom of the slurry pool to generate a cyclone field; under the action of the cyclone field, the slurry is stirred and reoxidized.

[0021] The jet oxidation device comprises a Venturi jet oxidation nozzle 2, a slurry injection pump 1 and an air pipe 3;

[0022] The Venturi jet oxidation nozzle 2 includes a Venturi nozzle a, a suction section b, a mixing section c, a diffusion section d, and a slurry discharge port e;

[0023] The diffusion section d is embedded in the bottom of the slurry pool, and is evenly arranged along the circumference of the slurry pool in the same horizontal plane or staggered, in a tangentially circular manner;

[0024] The air pipe 3 is connected to the suction section b;

[0025] The slurry ejection pump 1 extracts the slurry from the upper part of the slurry pool through the slurry pipeline, and the pressurized upper slurry is sent to the Venturi nozzle a as the working medium to form a high-speed jet fluid. At the same time, under the action of the high-speed jet fluid, the air in the air pipe 3 is sucked into the mixing section c, and momentum mixing is performed in the mixing section c, so that the air and the slurry form a uniform flow field in the mixing section c, and are fully mixed and oxidized; the fully oxidized slurry and the air enter the diffuser d again for deceleration and pressurization, and then are ejected into the bottom area of ​​the slurry pool along the tangential direction, and the vortex in the jet turbulence transfers momentum and air to the surrounding slurry, and this cycle forms a continuous vortex mixed with air, so that the slurry is continuously stirred and an oxidation reaction occurs.

[0026] The diffusion angle of the diffusion section d is 3° to 8°.

[0027] The upper end of the air pipe 3 is more than 1m above the liquid level of the slurry pool.

[0028] The jet exhaust desulfurization tower slurry oxidation device also includes a flushing water system;

[0029] The flushing water system consists of three flushing water systems:

[0030] The first flushing water is directly connected to the air pipe 3;

[0031] The second flushing water is connected to the slurry pipeline of the slurry injection pump 1;

[0032] The third flushing water is connected to the backwashing port f arranged on the diffusion section d;

[0033] During the flushing process, if only the slurry pipeline, the slurry injection pump 1 and the venturi jet oxidation nozzle 2 are to be cleaned, the first flushing water is turned on, or the first and second flushing water are turned on at the same time for cleaning;

[0034] The third flushing water is reverse flushing water, which is used for reverse flushing when the Venturi jet oxidation nozzle 2 is blocked;

[0035] A row of slurry ports e is provided at the inlet of the Venturi nozzle a to discharge the residual slurry therein to prevent deposition crystallization corrosion.

[0036] The Venturi nozzle a, the mixing section c and the diffusion section d are made of silicon carbide or alloy.

[0037] The inner surface of the Venturi nozzle a is lined with ceramic or alloy.

[0038] An end cover 5 is provided on the top of the air pipe 3 to prevent dust or rainwater from entering the air pipe 3 .

[0039] A method for oxidizing slurry in a jet exhaust desulfurization tower comprises the following steps:

[0040] The slurry injection pump 1 extracts the slurry from the upper part of the slurry pool through the slurry pipeline;

[0041] The pressurized upper slurry is sent to the Venturi nozzle a as the working medium and forms a high-speed jet fluid. At the same time, under the action of the high-speed jet fluid, the air in the air pipe 3 is sucked into the mixing section c for momentum mixing with the slurry, so that the air and slurry form a uniform flow field in the mixing section c. After being fully oxidized, it enters the diffuser d for deceleration and pressurization, and is then sprayed into the bottom area of ​​the slurry pool along the tangential direction. The vortex in the jet turbulence transfers momentum and air to the surrounding slurry, and this cycle is repeated to form a continuous vortex mixed with air, so that the slurry in the slurry pool is continuously stirred and fully oxidized.

[0042] Compared with the prior art, the present invention has the following advantages and effects:

[0043] 1. Energy saving: Compared with the traditional oxidation process, the energy consumption caused by the need to set up a large oxidation fan in the oxidation device is reduced. The present invention adopts a Venturi jet oxidation nozzle to replace the oxidation fan and the agitator. Since the Venturi jet oxidation nozzle has no moving parts, the equipment is simple and does not require mechanical power consumption. In the present invention, only the slurry pump needs to consume power, and the power consumption is much less than that required by the oxidation fan. Since the present invention does not require the installation of an agitator, the energy consumption required by the agitator is also reduced.

[0044] 2. Anti-blocking: In the traditional oxidation system, several oxidation air main pipes are arranged on the cross section at the bottom of the oxidation zone. The oxidation air is blown into the oxidation zone through a fixed pipe network, which easily leads to scaling and blockage of the oxidation air nozzles.

[0045] The venturi jet oxidation nozzles of the present invention are all arranged outside the desulfurization tower body, and are combined with a multi-channel high-pressure water system for regular flushing. A slurry discharge port e is provided in the venturi jet oxidation nozzle, which can effectively avoid flushing dead corners, making it difficult for the pipeline and pipe fittings to be scaled and blocked.

[0046] 3. The low oxidation air temperature solves the problem of high oxidation air temperature in traditional desulfurization towers that requires slurry re-cooling: In the traditional desulfurization tower oxidation process, the large oxidation fan will inevitably transfer heat to the air due to the dissipation effect of the blade movement during the process of pressurizing the air, which will increase the temperature of the oxidation air, affect the oxidation efficiency and desulfurization efficiency of the slurry, and also increase the additional cost of cooling.

[0047] The present invention utilizes a Venturi jet oxidation nozzle in combination with an air pipe to draw in relatively low-temperature air in the environment for mixing, which can effectively solve the influence of high oxidation air temperature on desulfurization efficiency and oxidation effect.

[0048] 4. The gas and liquid are mixed evenly, which improves the oxidation efficiency of the slurry: In the Venturi jet oxidation nozzle, the slurry and air are mixed violently in the mixing section c, which improves the degree of oxidation of the slurry by the air. When the gas-slurry two-phase flow is ejected from the diffusion section d along the tangential direction, the jet turbulence is formed and sprayed into the slurry neutralization zone, forming a continuous vortex, forming a violently disturbed swirl zone in the tower, and carrying out a strong mixed oxidation mass transfer process, which effectively improves the oxidation efficiency of the slurry.

[0049] 5. Oxidation and stirring are combined to eliminate the agitator: several Venturi jet oxidation nozzles are arranged along the outer inscribed circle of the desulfurization tower. During operation, the slurry-air two-phase flow forms a jet turbulence jet from the diffusion section d into the slurry neutralization zone. The eddy current in the jet turbulence diffuses the kinetic energy into the surrounding slurry, forming a continuous eddy current, and a violent swirl zone is formed along the inscribed circle direction, so that the slurry undergoes continuous and stable motion, which can effectively prevent the slurry from depositing and crystallizing. It replaces the agitator that is easy to wear, reducing the initial investment cost of the system and a large amount of operation and maintenance costs.

[0050] 6. Eliminate oxidation air ducts and nozzles: The turbulent jet flow injected into the desulfurization tower by the Venturi jet oxidation nozzle carries a large amount of oxidation air, and the oxidation air reacts evenly and violently with the slurry along with the inscribed circular swirl flow in the tower, replacing a large number of oxidation air ducts and nozzles arranged in the slurry pool, thereby greatly simplifying the system of the present invention and reducing the maintenance cost of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the slurry oxidation device of the jet exhaust desulfurization tower of the present invention.

[0052] Figure 2 It is a schematic diagram of the arrangement of the Venturi jet oxidation nozzle 2 spraying in a tangential direction along the inner circumferential surface of the slurry pool according to the present invention.

[0053] Figure 3 It is a schematic diagram of the structure of the Venturi jet oxidation nozzle 2 of the present invention.

[0054] In the figure: a is the Venturi nozzle, b is the suction section, c is the mixing section, d is the diffusion section, e is the slurry discharge port, and f is the backwash port. DETAILED DESCRIPTION

[0055] The present invention is further described in detail below in conjunction with specific embodiments.

[0056] like Figure 1-3 The present invention discloses a jet exhaust desulfurization tower slurry oxidation device, comprising a desulfurization tower and a slurry pool at its lower part; a plurality of jet oxidation devices are arranged along the circumference of the slurry pool;

[0057] The jet oxidation device first extracts the slurry in the slurry pool and oxidizes it with air. The oxidized slurry is then sprayed back to the bottom of the slurry pool, generating a cyclone field under the action of the tangential jet; the slurry is stirred and fully oxidized under the action of the cyclone field.

[0058] The jet oxidation device comprises a Venturi jet oxidation nozzle 2, a slurry injection pump 1 and an air pipe 3;

[0059] The Venturi jet oxidation nozzle 2 includes a Venturi nozzle a, a suction section b, a mixing section c, a diffusion section d, and a slurry discharge port e;

[0060] The diffusion section d is embedded in the bottom of the slurry pool, and is evenly arranged along the circumference of the slurry pool in the same horizontal plane or staggered, in a tangentially circular manner;

[0061] The air pipe 3 is connected to the suction section b;

[0062] The slurry ejection pump 1 extracts the slurry from the upper part of the slurry pool through the slurry pipeline, and the pressurized upper slurry is sent to the Venturi nozzle a as the working medium to form a high-speed jet fluid. At the same time, under the action of the high-speed jet fluid, the air in the air pipe 3 is sucked into the mixing section c, and momentum mixing is performed in the mixing section c, so that the air and the slurry form a uniform flow field in the mixing section c and are fully oxidized. The fully oxidized slurry enters the diffuser d together with the air for deceleration and pressurization, and is then ejected into the bottom area of ​​the slurry pool along the tangential direction. The vortex in the jet turbulence transfers momentum and air to the surrounding slurry, and this cycle forms a continuous vortex mixed with air, so that the slurry is continuously stirred and an oxidation reaction occurs.

[0063] The diffusion angle of the diffusion section d is 3° to 8° to reduce diffusion loss.

[0064] The length of the mixing section c (throat) is 6 to 10 times of its diameter, ensuring that the slurry and air are mixed into a two-phase flow with uniform momentum, thereby reducing energy loss.

[0065] In order to ensure the stable operation of the Venturi jet oxidation nozzle 2, it is necessary to ensure that the eccentricity of the Venturi nozzle a, the mixing section c and the diffusion section d is not greater than 0.4 mm.

[0066] The upper end of the air pipe 3 is more than 1 meter above the liquid level of the slurry pool to avoid the phenomenon of spraying when the desulfurization system stops running.

[0067] The jet exhaust desulfurization tower slurry oxidation device also includes a flushing water system;

[0068] The flushing water system consists of three flushing water systems:

[0069] The first flushing water is directly connected to the air pipe 3;

[0070] The second flushing water is connected to the slurry pipeline of the slurry injection pump 1;

[0071] The third flushing water is connected to the backwashing port f arranged on the diffusion section d;

[0072] The above three flushing water routes are all equipped with valves, which can be solenoid valves or manual valves depending on the specific situation.

[0073] During the flushing process, if only the slurry pipeline, the slurry injection pump 1 and the venturi jet oxidation nozzle 2 are to be cleaned, the first flushing water is turned on, or the first and second flushing water are turned on at the same time for cleaning;

[0074] The third flushing water is reverse flushing water, which is used for reverse flushing when the Venturi jet oxidation nozzle 2 is blocked;

[0075] A row of slurry ports e are provided at the inlet of the Venturi nozzle a, which are used to discharge the residual slurry therein when blockage occurs to prevent deposition crystallization corrosion.

[0076] The Venturi nozzle a, mixing section c, and diffusion section d are made of wear-resistant and corrosion-resistant materials such as silicon carbide, which can effectively extend the service life of the jet oxidizer 2.

[0077] The inner surface of the Venturi nozzle a has a ceramic or alloy lining.

[0078] An end cover 5 is provided on the top of the air pipe 3 to prevent dust or rainwater from entering the air pipe 3 .

[0079] The slurry oxidation process of the present invention is as follows:

[0080] The slurry injection pump 1 extracts the slurry from the upper part of the slurry pool through the slurry pipeline;

[0081] The pressurized upper slurry is sent to the Venturi nozzle a as the working medium and forms a high-speed jet fluid. At the same time, under the action of the high-speed jet fluid, the air in the air pipe 3 is sucked into the mixing section c for momentum mixing with the slurry, so that the air and slurry form a uniform flow field in the mixing section c. After being fully oxidized, it enters the diffuser d for deceleration and pressurization, and is then sprayed into the bottom area of ​​the slurry pool along the tangential direction. The vortex in the jet turbulence transfers momentum and air to the surrounding slurry, and this cycle is repeated to form a continuous vortex mixed with air, so that the slurry in the slurry pool is continuously stirred and fully oxidized.

[0082] The present invention is not only suitable for cylindrical desulfurization towers, but also suitable for desulfurization towers with rectangular or other cross-sectional shapes.

[0083] As described above, the present invention can be better implemented.

[0084] The implementation methods of the present invention are not limited to the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A jet exhaust desulfurization tower slurry oxidation device, comprising a desulfurization tower and a slurry pool at its lower part; characterized in that: A plurality of jet oxidation devices are arranged tangentially along the circumference of the slurry pool; The jet oxidation device first extracts the slurry in the slurry pool, and jet mixes and oxidizes it with air. The oxidized slurry is then sprayed back to the bottom of the slurry pool to generate a cyclone field. Under the action of the cyclone field, the slurry is stirred and reoxidized. The jet oxidation device comprises a Venturi jet oxidation nozzle (2), a slurry injection pump (1) and an air pipe (3); The Venturi jet oxidation nozzle (2) comprises a Venturi nozzle a, a suction section b, a mixing section c, a diffusion section d, and a slurry discharge port e; The diffusion section d is embedded in the bottom of the slurry pool, and is evenly arranged along the circumference of the slurry pool in the same horizontal plane or staggered, in a tangentially circular manner; The air pipe (3) is connected to the suction section b; The slurry jet pump (1) extracts slurry from the upper part of the slurry pool through the slurry pipeline, and the pressurized upper part of the slurry is sent to the venturi nozzle a as the working medium to form a jet fluid. At the same time, under the action of the jet fluid, the air in the air pipe (3) is sucked into the mixing section c, and momentum mixing is performed in the mixing section c, so that the air and the slurry form a uniform flow field in the mixing section c, and are fully mixed and oxidized; the fully oxidized slurry and the air enter the diffuser d again, decelerate and increase the pressure, and are then sprayed into the bottom area of ​​the slurry pool along the tangential direction. The vortex in the jet turbulence transfers momentum and air to the surrounding slurry, and the cycle is repeated to form a continuous vortex mixed with air, so that the slurry is continuously stirred and an oxidation reaction occurs; The upper end of the air pipe (3) is more than 1m above the liquid level of the slurry pool; The jet exhaust desulfurization tower slurry oxidation device also includes a flushing water system; The flushing water system consists of three flushing water systems: The first flushing water path is directly connected to the air pipe (3); The second flushing water is connected to the slurry pipeline of the slurry injection pump (1); The third flushing water is connected to the backwashing port f arranged on the diffusion section d; During the flushing process, if only the slurry pipeline, the slurry injection pump (1) and the Venturi jet oxidation nozzle (2) are to be cleaned, the first flushing water is turned on, or the first and second flushing water are turned on at the same time for cleaning; The third flushing water is reverse flushing water, which is used for reverse flushing when the Venturi jet oxidation nozzle (2) is blocked; A row of slurry ports e is provided at the inlet of the Venturi nozzle a to discharge the residual slurry therein to prevent deposition crystallization corrosion.

2. The jet exhaust desulfurization tower slurry oxidation device according to claim 1 is characterized in that: The diffusion angle of the diffusion section d is 3° to 8°.

3. The jet exhaust desulfurization tower slurry oxidation device according to claim 1 is characterized in that: The Venturi nozzle a, the mixing section c and the diffusion section d are made of silicon carbide or alloy.

4. The jet exhaust desulfurization tower slurry oxidation device according to claim 3 is characterized in that: The inner surface of the Venturi nozzle a is lined with ceramic or alloy.

5. The jet exhaust desulfurization tower slurry oxidation device according to claim 2 is characterized in that: An end cover (5) is provided on the top of the air pipe (3) to prevent dust or rainwater from entering the interior of the air pipe (3).

6. A method for slurry oxidation in a jet exhaust desulfurization tower, characterized in that The method is implemented by using the jet exhaust desulfurization tower slurry oxidation device according to any one of claims 1 to 5, which comprises the following steps: The slurry ejection pump (1) extracts slurry from the upper part of the slurry pool through the slurry pipeline; The pressurized upper slurry is fed into the venturi nozzle a as a working medium and forms a jet fluid. At the same time, under the action of the jet fluid, the air in the air pipe (3) is sucked into the mixing section c for momentum mixing with the slurry, so that the air and the slurry form a uniform flow field in the mixing section c. After being fully oxidized, the air enters the diffuser d for deceleration and pressurization, and is then ejected into the bottom area of ​​the slurry pool along the tangential direction. The vortex in the jet turbulence transfers momentum and air to the surrounding slurry. This cycle forms a continuous vortex mixed with air, so that the slurry in the slurry pool is continuously stirred and fully oxidized.

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