CN1962035A - Spray cyclone bed type gas liquid solid tri-phase reactor - Google Patents

Abstract

The jet swirl bed type gas-liquid-solid three-phase reactor uses several circulating pumps to extract the slurry in the slurry pool from the four corners or four walls, and after being accelerated by the circulating pump, multiple high-speed jets flow from the surrounding of the slurry pool. Tangential spraying into the slurry tank drives the overall rotation of the slurry tank, replacing the stirring effect of the mechanical paddle agitator on the slurry tank. The entire flow field roughly forms a stable single rotating flow field, which can control the sorting process of solid phase particles more conveniently. The oxidizing air is directly injected into the nozzle of the high-speed jet, and there is a large speed difference between the liquid phase and the gas phase. The high-speed liquid phase crushes the bubbles, which greatly strengthens the mixing between the gas and liquid, and can increase the gas-liquid reaction intensity. , The gas phase forms a spiral trajectory in the pulp tank instead of a free floating state, which will prolong the residence time of the bubbles in the pulp tank, thereby improving the utilization rate of oxidizing air.

Description

Jet swirl bed gas-liquid-solid three-phase reactor

technical field

The invention belongs to the technical field of three-phase reactors, and in particular relates to a jet swirl bed type gas-liquid-solid three-phase reactor used for a large-scale wet flue gas desulfurization slurry pool.

Background technique

Wet desulfurization completes the absorption of SO ₂ in the absorption tower, and completes the oxidation and solidification of SO ₂ in the slurry tank. The slurry tank is an important part of the gas-solid mixture to absorb gas. It undertakes important tasks such as the separation of gas and absorption liquid, the neutralization of absorption liquid, the oxidation and crystallization of gypsum, and its operation directly determines the mass concentration and chemical reaction of the absorption liquid. The status of the process and the quality of the discharged material.

The main functions of the slurry tank are: preparation of slurry: fresh limestone powder (or limestone slurry) and fresh water for supply need to be fully mixed in the slurry tank first to prepare a desulfurization slurry with suitable concentration and composition; oxidation of CaSO ₃ : oxidation of air directly Enter the slurry tank, and carry out oxidation reaction with the slurry falling back in the absorption tower (because of reacting with SO ₂ to generate a large amount of CaSO ₃ ), and oxidize CaSO ₃ to CaSO ₄ , this link is not only related to whether the sulfur fixation can be fully realized (put Easily decomposed CaSO ₃ is converted into stable CaSO ₄ ), which is also directly related to the scaling of the slurry pipeline; adjusting the pH value and other components of the slurry: the balance of various materials in the slurry tank and the input status of additives will determine the system The pH value and other components of the circulating slurry, the pH value of the slurry is directly related to the absorption capacity of SO ₂ in the absorption tower, and also affects the progress of the CaSO ₃ oxidation reaction. The adjustment of the pH value needs to be carried out in the slurry tank; Solid separation: Because gypsum must crystallize and grow to a certain particle size, it can be discharged as a qualified by-product, and at the same time, it is necessary to ensure that the content of other impurities (mainly CaCO ₃ and CaSO ₃ ) in the discharged gypsum slurry is within a limited range , at this time, the liquid-solid separation process in the slurry tank must be reasonably organized to ensure the sorting quality of gypsum particles; adjust the residence time of the reactants: in the design of the slurry tank for wet desulfurization, there are three important residence times that need to be guaranteed. One is the residence time of limestone particles used as a desulfurizer in the system. Because limestone is a kind of insoluble substance, it takes about 8 to 14 hours to dissolve completely under weakly acidic conditions, so it must be ensured that there is sufficient desulfurization in the system. The residence time can ensure that limestone fully participates in the desulfurization reaction; the second is the residence time of the circulating slurry entering the absorption tower, because the slurry falling back from the absorption tower is a state close to saturation for absorbing SO ₂ and must stay in the slurry pool Enough time, so that SO ₃ ^2- is fully converted into other components (such as solid-phase CaCO ₃ , CaSO ₄ or SO ₄ ^2- ), can regain the ability to absorb SO ₂ and enter the absorption tower again; the third is as an oxidant The residence time of oxidizing air in the system. Oxygen is not a gas that is easily soluble in water, and oxygen must be dissolved in the slurry to participate in the oxidation reaction of CaSO ₃ . Ensure the depth of oxidation reaction and high utilization rate of oxidation air. The above three residence times must also be matched with each other to ensure the full completion of various desulfurization and sulfur fixation reactions; system buffer: various parameters of the desulfurization system are constantly changing during operation, such as changes in the load of power plant boilers lead to changes in flue gas volume , The change of the coal quality of the combustion leads to the change of the flue gas composition, the change of the composition of the limestone powder, and the change of various parameters caused by the possible other conditions of the whole system. In the case of these parameter changes, the whole system should be stable and not sensitive , to ensure the desulfurization rate of the flue gas, the quality of the discharged gypsum slurry and the stable operation of the system itself. At this time, the pH value of the slurry, the main components of the slurry, and the particle size and distribution of solid particles should not change significantly. It needs to be guaranteed by the physical buffer and chemical buffer capacity of the slurry pool itself.

In the wet desulfurization system, the slurry tank is also a component with a high failure rate, and there are still problems in many aspects such as material strength, installation shock absorption, slurry overflow, and engineering efficiency. The traditional slurry tank is a mechanically agitated bubbling bed reactor. Oxidation air is input from the bottom of the slurry tank or in front of the agitator through the air inlet pipe. A vertical agitator is used. Generally, only one agitator is arranged in a slurry tank, and the flow field structure is relatively simple. , solid-phase separation works well, however. For boiler units above 300MW, the diameter of the blades of the agitator is 10 meters or even more than 15 meters, which not only has a heavy structure, but also brings certain difficulties to the arrangement of the absorption tower above the slurry tank. At this time, the absorption tower and slurry must be used. The eccentric layout of the tank is not concentric, or the double tower structure must be adopted; the number of agitators can be increased by using the side wall mechanical stirring method, but the flow field in the entire slurry tank is very complicated, and it is difficult to take into account the problem of solid phase separation. Moreover, the stressed state of the slurry tank wall is not good, and the seal between the rotating shaft and the slurry tank wall is difficult, and the situation of slurry leakage often occurs.

The main disadvantage of this kind of reactor is: due to the separation of solid phase, the flow rate of mechanical stirring cannot be as high as about 50r/min, the bubbles of oxidizing air are basically in a state of free floating, and the gas-liquid mixing is not enough Strong, the oxidation reaction speed is relatively slow, and once a failure occurs, the utilization rate of the oxidation air is lower than 30%; the desulfurization tower is a large-scale reaction device, and when the mechanical agitator is large-scale, the structure is bulky, difficult to arrange, and the failure rate is high. Maintenance is inconvenient and must be shut down for maintenance.

Contents of the invention

The object of the present invention is to overcome the above-mentioned shortcoming of prior art, provide a kind of jet swirl bed type gas-liquid-solid three-phase reactor that does not need mechanical stirring parts, can prevent fouling, wear and other mechanical parts failure.

In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is to include a slurry tank, one or more slurry circulation pumps are respectively arranged on the four walls of the slurry tank, and the inlet and outlet of the slurry circulation pump are respectively passed through pipes. The road is connected with the outlet and the inlet of the slurry tank, and the pipeline of the inlet is also connected with the oxidation air pipeline, and the tangential angle between the outlet and the inlet and the four corners or four walls of the slurry tank is 5°~40° °.

Because the present invention uses several circulation pumps, the slurry in the slurry pool is extracted from the four corners or four walls, and after the acceleration of the circulation pump, multiple high-speed jets are formed and sprayed into the slurry pool tangentially from the periphery of the slurry pool to drive the slurry. The overall rotation of the material tank replaces the stirring effect of the mechanical paddle agitator on the slurry tank. The entire flow field roughly forms a stable single rotating flow field, which can control the sorting process of solid phase particles more conveniently. The oxidizing air is directly injected into the nozzle of the high-speed jet, and there is a large speed difference between the liquid phase and the gas phase. The high-speed liquid phase crushes the bubbles, which greatly strengthens the mixing between the gas and liquid, and can increase the gas-liquid reaction intensity. , the gas phase forms a trajectory of spiral motion in the slurry tank instead of a free floating state, which will prolong the residence time of the air bubbles in the pulp tank, thereby improving the utilization rate of oxidation air, and the present invention only needs to use several circulation pumps and connecting pipes, The layout is convenient and flexible, eliminating the need for heavy mechanical stirring blades, which is very conducive to the enlargement of the reactor.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Referring to Fig. 1, the present invention includes a slurry tank 1, and a slurry circulating pump 2 is respectively arranged on the four walls of the slurry tank 1. When the system is running, the slurry is drawn out from the outlet 3 and sent to the delivery port 4 by the slurry circulating pump 2 for re-use. Enter the slurry pool 1, the cutting angle between the outlet 3 and the delivery port 4 of the slurry pool 1 and the four corners or four walls of the slurry pool 1 is 5°~40°, and it can be placed in the slurry pool 1 after setting according to this angle. The two layers that form the water flow rotate horizontally, so as to realize the turbulent mixing of the gas-liquid two-phase, which is similar to the four-corner tangential combustion in the fire chamber combustion furnace, so as to achieve the expected effect of stirring.

If the diameter of the slurry tank is relatively large, the present invention arranges multiple slurry circulation pumps 2 on the four corners or walls of the slurry tank 1, and the multiple slurry circulation pumps 2 are on the same level.

If the slurry pool 1 is relatively high, the present invention arranges a plurality of slurry circulation pumps 2 on the four walls of the slurry pool 1 along the height direction of the slurry pool 1 .

In the present invention, there are multiple high-speed gas-liquid mixed jets sprayed tangentially into the slurry pool 1 around the slurry pool 1. The momentum of these jets is enough to drive the overall rotation of the slurry pool 1, and the gas-liquid two-phase mixing is strong, which also meets the requirements of the slurry. The need for mass transfer in the pool 1; the gas-liquid-solid three-phase flow in the slurry pool 1 is a swirling flow as a whole, which can maintain a strong liquid-solid mixing intensity and form a reasonable solid phase layer to achieve solid phase particles. Reasonable sorting; no mechanical agitator, but by adjusting the jet velocity, the concentration and particle size distribution of the solid phase can be dynamically adjusted to meet the requirements of particle sorting. The gas that participates in the reaction is fed into the inlet 4 from the jet nozzle, the gas-liquid phase velocity difference is large, the gas is forcibly crushed into small bubbles, the specific surface area is large, the residence time is long, and the gas-liquid reaction is strong. Gas can also be fed into the bottom of the slurry tank 1 or outside the feeding port 4 as required, which is easy to realize the modification of existing equipment.

Claims (1)

1, a kind of spray cyclone bed type gas liquid solid tri-phase reactor, comprise slurry pool (1), it is characterized in that: on four jiaos of slurry pool (1) or wall, respectively be furnished with one or more slurry circulating pump (2), the inlet of this slurry circulating pump (2) and outlet be the outlet (3) by pipeline and slurries pond (1) and send into mouth (4) and be connected respectively, the pipeline of sending into mouthful (4) also is connected with oxidation air pipeline (5), and outlet (3) and to send into that mouthful (4) and slurry pool (1) four jiaos or four walls cut angle be 5 °～40 °.

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