Venturi counter-jet liquid column enhanced flue gas desulfurization device and method

Abstract

The application provides a venturi pair jet liquid column enhanced flue gas desulfurization device and method, which comprises an absorption tower and a reverse jet tower, the upper part of the reverse jet tower is provided with a tail gas inlet, and the gas-liquid outlet of the lower part of the reverse jet tower is communicated to the gas-liquid inlet of the absorption tower; the reverse jet tower is provided with two groups of upper and lower venturi jet devices which spray each other, the liquid inlet end of the venturi jet devices is communicated to the liquid outlet of the absorption tower, the top of the absorption tower is provided with a gas outlet, and the absorption tower is provided with a demister which is located above the gas-liquid inlet; the tail gas to be treated which enters the reverse jet tower is absorbed by the absorption liquid after the absorption liquid is sprayed and collided by the two groups of venturi jet devices, then enters the absorption tower, and is discharged from the gas outlet of the absorption tower after being treated by the demister. The flue gas desulfurization device and method can realize small-scale jet liquid drop circulation desulfurization, and has the advantages of high desulfurization efficiency, good desulfurization effect, and low consumption of absorption liquid.

Description

Technical Field

[0001] This invention patent belongs to the field of flue gas desulfurization technology, specifically relating to a Venturi-assisted liquid spray column enhanced flue gas desulfurization device and method. Background Technology

[0002] SO2 is one of the most common air pollutants. With continuous industrial development, SO2 emissions are increasing. The large-scale emission of sulfur dioxide gas exacerbates acid rain, causing serious harm to the natural environment and directly impacting human health. If not effectively treated, it will worsen soil and water acidification, disrupt ecological balance, and affect biodiversity.

[0003] With increasing environmental awareness and the widespread adoption of environmental regulations, most sulfuric acid enterprises in my country have increased their investment in sulfuric acid tail gas treatment. Combining their own unique characteristics with theoretical research, they have developed many industrial desulfurization technologies with distinct enterprise features. Among these, the liquid column desulfurization tower has become a focus of attention due to its advantages of sufficient gas-liquid mass transfer and high desulfurization efficiency. However, in actual industrial production, problems still exist, such as insufficient absorption efficiency of the liquid column alkaline scrubbing tower, preventing direct discharge, and high alkali consumption.

[0004] CN201423243Y discloses a uniform-flow spray pipe structure liquid column tower, including a tower body with a flue gas outlet. A slurry pool for holding desulfurization scrubbing liquid is located at the bottom of the tower body. Spray pipes are horizontally arranged inside the tower body, located below the flue gas outlet and connected to the slurry pool via a circulating pump. Multiple upward-spraying nozzles are installed on the spray pipes. A flue gas inlet is also provided on the tower body, located below the spray pipes. A flow equalization plate for adjusting the spray height of the desulfurization scrubbing liquid is installed inside the spray pipes, and the flow equalization plate is correspondingly arranged with the nozzles on the outer surface of the spray pipes. Although this device improves desulfurization efficiency, the flue gas after absorption by this technology has a high mist content at the outlet, increasing the load on the subsequent demister, thus having little positive effect on energy saving and consumption reduction.

[0005] CN 108579396 A discloses a device and method for flue gas desulfurization. The invention includes: an absorption tower body; a flue gas inlet at the bottom and a flue gas outlet at the top of the absorption tower body; a slurry circulation device, a liquid column injection device, a high-efficiency atomizing spray device, and a demister device arranged sequentially from bottom to top inside the absorption tower body; the liquid column injection device is located above the flue gas inlet; the liquid column injection device includes several liquid column injection branch pipes; the several liquid column injection branch pipes are evenly distributed along one or more horizontal layers inside the absorption tower body; the bottom end of each liquid column injection branch pipe communicates with the slurry circulation device, and the top end is provided with a liquid column injection nozzle; an inlet flue communicating with the flue gas inlet; and a flue gas flue communicating with the flue gas outlet. Although this method has the characteristic of high desulfurization efficiency, it increases the amount of absorbent liquid. In actual industrial applications, the cost of absorbent liquid accounts for a large proportion of the liquid column tower cost, therefore, this method has low economic viability in practical industrial applications.

[0006] Therefore, it is essential to develop a more efficient flue gas desulfurization device and method with lower alkali consumption, which is of great significance to the field of environmental protection. Summary of the Invention

[0007] In view of the above problems, the present invention provides a venturi-assisted liquid spray column enhanced flue gas desulfurization device and method to achieve more efficient and lower alkali consumption flue gas desulfurization.

[0008] The technical solution of the present invention is as follows: a Venturi-inspired flue gas desulfurization device, comprising an absorption tower and a reverse-spraying tower, wherein the upper part of the reverse-spraying tower has a tail gas inlet, and the lower gas-liquid outlet is connected to the gas-liquid inlet of the absorption tower; the reverse-spraying tower is provided with two sets of opposing Venturi spraying devices, and the liquid inlet of the Venturi spraying devices is connected to the liquid outlet of the absorption tower; the top of the absorption tower has a gas outlet, and the absorption tower is provided with a demister located above its gas-liquid inlet; the tail gas to be treated enters the reverse-spraying tower through the tail gas inlet, is absorbed and reacted by the absorbent liquid of the two sets of opposing Venturi spraying devices, and then enters the absorption tower, and is discharged from the gas outlet through the demister.

[0009] The present invention is further configured such that the exhaust gas inlet is located between the upper and lower sets of the Venturi injection devices, and is close to one end of the upper Venturi injection device.

[0010] The present invention is further configured such that the inlet end of the Venturi jet device is also connected to a liquid distributor, and the inlet end pipe of the liquid distributor is connected to the outlet.

[0011] The present invention is further configured such that the reverse spray tower is provided with two liquid distributors respectively connected to two sets of Venturi spray devices, and the absorbent discharged from the drain outlet of the absorption tower is respectively transported to the two liquid distributors through pipelines and sprayed out through the Venturi spray devices connected to the liquid distributors.

[0012] The present invention is further configured such that each group of the Venturi injection devices includes at least two Venturi injectors, which are uniformly distributed along the liquid distributor within the reverse nozzle.

[0013] The present invention is further configured such that each of the Venturi injectors is provided with a liquid inlet and a liquid outlet at both ends, a self-priming air inlet is provided on the side wall of the Venturi injector, the throat convergence angle of the Venturi injector is 30-35°, and the gas-liquid ratio is 3-5.

[0014] The present invention is further configured such that a tail gas composition detection device and a tail gas flow monitoring device are provided at both the tail gas inlet of the reverse spray tower and the gas outlet of the absorption tower; a liquid flow meter, a pressure gauge and a circulating water pump are provided on the pipe connecting the drain outlet of the absorption tower and the two sets of Venturi spray devices to regulate the height of the liquid column sprayed by the Venturi spray device.

[0015] The present invention is further configured such that the absorption tower is provided with a liquid inlet for replenishing the absorption liquid.

[0016] The present invention also provides a method for flue gas desulfurization using any of the above-mentioned Venturi-type spray column enhanced flue gas desulfurization devices.

[0017] The present invention is further configured such that the flue gas desulfurization method includes the following process: the exhaust gas to be treated first enters the reverse spray tower, first flows in the same direction as the lower spray column injected by the two sets of Venturi spray devices, then flows in the opposite direction to the upper spray column, and then flows in the same direction as the falling liquid column and droplets. At the same time, the tiny droplets ejected from the lower and upper spray columns, as well as the droplets generated by the collision between the upper and lower spray columns, react with and are absorbed by the exhaust gas; the gas after reaction enters the absorption tower through the lower part of the reverse spray tower, and is then treated by the demister before being discharged from the gas outlet.

[0018] In the above process, the desulfurization process of the Venturi jet spray column all occurs within the reverse spray tower. Due to the opposing spray configuration of the upper and lower sets of Venturi jet devices, the liquid columns sprayed by the two sets of devices collide, resulting in a larger number of smaller droplets. This leads to greater turbulence and a higher degree of gas-liquid interweaving within the tower. Furthermore, the smaller droplets have a larger specific surface area for mass transfer, resulting in higher mass transfer efficiency. Reducing the droplet size can enhance mass transfer. In addition, since the self-priming inlet of the Venturi jets in the reverse spray tower can absorb the tail gas within the tower under negative pressure, the tail gas can be repeatedly circulated and absorbed, significantly increasing the tail gas absorption efficiency.

[0019] The present invention is further configured such that the height of the liquid column sprayed by the Venturi jet device is 0.7-1.5m.

[0020] The invention is further configured such that the liquid column ejected by the Venturi jet device ejects tiny droplets with a diameter of 120-250 μm, and the liquid columns ejected by the upper and lower sets of Venturi jet devices collide to generate small droplets of 300-550 μm.

[0021] The present invention is further configured such that the exhaust gas inlet of the reverse spray tower is located above the position where the liquid columns sprayed by the upper and lower sets of the Venturi spray devices collide.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention adds two sets of Venturi jet devices with opposing sprays in the upper and lower parts of the reverse spray tower, so that the sprayed liquid column collides to generate more and smaller droplets, resulting in greater turbulence in the flow field inside the tower and a higher degree of gas-liquid interweaving, thereby improving the mass transfer efficiency; (2) The present invention uses a Venturi jetter as a device for spraying absorbent liquid. Since it can self-absorb the tail gas in the tower through the suction port, the tail gas in the tower can be circulated and absorbed multiple times, thereby greatly increasing the tail gas absorption efficiency; (3) The flue gas desulfurization method described in the present invention can reduce the consumption of absorbent liquid because its mass transfer is more sufficient. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the flue gas desulfurization process described in this invention.

[0024] Figure 2 This is a cross-sectional view of the reverse spray tower in the embodiment along the AA direction.

[0025] Figure 3 This is a schematic diagram of the Venturi injector in the embodiment.

[0026] Figure 4 This is a schematic diagram illustrating the principle of the Venturi ejector for spraying liquid droplets as described in this invention.

[0027] Among them, 1. Absorption tower, 1-1. Gas outlet, 1-2. Drain outlet, 1-3. Liquid inlet, 1-4. Gas-liquid inlet, 2. Backflow inlet tower, 2-1. Tail gas inlet, 3. Venturi jet device, 3-1. Venturi ejector, 3-1-1. Liquid inlet, 3-1-2. Liquid outlet, 3-1-3. Self-priming air inlet, 4. Demister, 5. Liquid distributor, 6. Circulating water pump, 7. Liquid flow meter, 8. Pressure gauge, 9. Tail gas composition detection device, 10. Tail gas flow detection device. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. It should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of the present invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the manufacturer.

[0029] Example 1

[0030] like Figure 1 As shown, the present invention provides a Venturi-style flue gas desulfurization device enhanced by a liquid spray column, comprising an absorption tower 1 and a reverse spray tower 2 connected to each other. The absorption tower 1 contains an absorbent liquid, wherein...

[0031] The reverse spray tower 2 has a tail gas inlet 2-1 and a gas-liquid outlet at its upper and lower parts, respectively. The absorption tower 1 has a gas outlet 1-1 and a liquid outlet 1-2 at its top and bottom, respectively. The absorption tower 1 has a liquid inlet 1-3 and a gas-liquid inlet 1-4 on its side wall. The gas-liquid outlet of the reverse spray tower 2 is connected to the gas-liquid inlet 1-4 of the absorption tower 1. The reverse spray tower 2 is equipped with two sets of Venturi jet devices 3 that spray in opposite directions. The liquid inlet ends of the two sets of Venturi jet devices 3 are connected to the liquid outlet 1-2 of the absorption tower 1. The absorption tower 1 is equipped with a demister 4, which is located between the gas-liquid inlet 1-4 and the gas outlet 1-1 of the absorption tower 1. The sulfur dioxide tail gas to be treated enters the reverse spray tower 2 through the tail gas inlet 2-1. After being absorbed and reacted by the absorbent liquid from the collision of the two sets of Venturi jet devices 3, it enters the absorption tower 1 and is then treated by the demister 4 before exiting the absorption tower 1. Gas is discharged from outlet 1-1.

[0032] In this embodiment, the exhaust gas inlet 2-1 is located between the upper and lower sets of Venturi injection devices 3, and is close to one end of the upper Venturi injection device 3.

[0033] Furthermore, the reverse spray tower 2 is equipped with a liquid distributor 5, which is connected to the inlet end of two sets of Venturi spray devices 3 respectively. The inlet end pipe of each liquid distributor 5 is connected to the outlet 1-2 of the absorption tower 1. The absorbent discharged from the outlet 1-2 of the absorption tower 1 is transported to the two sets of liquid distributors 5 through pipelines and sprayed out through the Venturi sprayers 3-1 connected to the liquid distributors 5.

[0034] Furthermore, a power unit, a circulating water pump 6, a liquid flow meter 7, and a pressure gauge 8 are installed on the pipeline connecting the drain port 1-2 of the absorption tower 1 and the liquid distributor 5. The height of the liquid column generated by the Venturi ejector 3-1 is controlled by controlling the liquid flow rate and pressure. In order to ensure that the sulfur dioxide absorbent can smoothly enter the Venturi ejector and generate a liquid column of a certain height, in this embodiment, the head of the circulating water pump 6 is ≥20m.

[0035] Furthermore, a tail gas composition detection device 9 and a tail gas flow monitoring device 10 are installed at the tail gas inlet 2-1 of the reverse spray tower 2 and the gas outlet 1-1 of the absorption tower 1.

[0036] like Figure 2 As shown, in this embodiment, each group of Venturi injection devices 3 includes 3 Venturi injectors 3-1, which are evenly distributed along the liquid distributor 5 in the reverse spray tower 2.

[0037] like Figure 3 As shown, each Venturi injector 3-1 has a liquid inlet 3-1-1 and a liquid outlet 3-1-2 at both ends. A self-priming air inlet 3-1-3 is provided on the side wall of each Venturi injector 3-1. The liquid inlet 3-1-1 is connected to the liquid distributor 5, and the liquid outlet 3-1-2 ejects a liquid column. The throat convergence angle of the Venturi injector 3-1 is 30-35°, and the gas-liquid ratio is 3-5. In this embodiment, the liquid inlet 3-1-1 of the Venturi injector 3-1 is 15mm in diameter, the liquid outlet 3-1-2 has a diameter of 8mm and a height of 12cm, and the self-priming air inlet 3-1-3 has a diameter of 4mm.

[0038] In this embodiment, each connecting pipe is equipped with a regulating valve.

[0039] like Figure 1 and Figure 4 As shown, the present invention also provides a method for flue gas desulfurization using the above-mentioned Venturi jet-enhanced flue gas desulfurization device. The specific process is as follows: after the sulfur dioxide tail gas enters the reverse spray tower 2 through the tail gas inlet 2-1, it first flows in the same direction as the downward jet of the Venturi jet device 3 above, then flows in the opposite direction to the upward jet of the Venturi jet device 3 below, and then flows in the same direction as the falling liquid column and droplets. At the same time, the tiny droplets ejected from the liquid column of the Venturi jet device 3 and the small droplets ejected from the collision of the liquid columns sprayed by the two sets of Venturi jet devices 3 react with the tail gas for absorption. The reacted gas enters the absorption tower 1 from the lower part of the reverse spray tower 2, and is then discharged from the gas outlet 1-1 of the absorption tower 1 after being treated by the demister 4.

[0040] Preferably, the exhaust gas inlet 2-1 of the reverse spray tower 2 is located above the point where the upper and lower spray columns of the two sets of Venturi spray devices 3 meet and collide.

[0041] In this embodiment, the height of the jetting liquid column of the Venturi injector 3-1 is 0.7-1.5m, and the liquid column sprayed by the Venturi injector 3-1 ejects tiny droplets with a diameter of 120-250μm; the liquid columns sprayed by the two sets of Venturi injector devices 3 spraying in opposite directions collide to generate small droplets of 300-550μm.

[0042] The above-mentioned Venturi jet-enhanced flue gas desulfurization device and method were used to desulfurize sulfur dioxide tail gas, with sodium hydroxide as the absorbent. After several days of stable operation, the concentration of sulfur dioxide inlet and outlet tail gas and the alkali consumption were recorded. The results are recorded in Table 1.

[0043] Comparative Example

[0044] In a chemical plant in Nanjing, the liquid column tower uses a traditional injection method. The absorbent is the same as in Example 1. Under the condition of the same inlet tail gas flow rate, the concentration of sulfur dioxide in the inlet and outlet tail gas and the alkali consumption are recorded after the device has been running stably for several days. The results are compared with those of Example 1 and are recorded in Table 1.

[0045] Table 1 SO2 inlet and outlet concentrations, alkali consumption, and absorption efficiency

[0046] experimental group <![CDATA[Import SO2 concentration (mg / m 3 )]]> <![CDATA[Outlet SO2 concentration (mg / m 3 )]]> Alkali consumption (t / day) Absorption efficiency Comparative Example 1486 200 16 86.5％ Example 1 1493 153 12 89.8％

[0047] As can be seen from the results in Table 1, under the condition of almost the same SO2 inlet concentration, the SO2 outlet concentration of Example 1 is significantly lower than that of the comparative example, its absorption efficiency is significantly higher than that of the comparative example, and its alkali consumption is also significantly lower than that of the comparative example. In summary, the improved flue gas desulfurization device and method of this invention will significantly reduce the SO2 tail gas absorption cost in actual production.

[0048] Although the technical solutions of the present invention have been described and enumerated in detail, it should be understood that any modifications to the above embodiments or the adoption of equivalent alternatives shall fall within the scope of protection claimed by the present invention.

Claims

1. A Venturi-assisted liquid-sprayed enhanced flue gas desulfurization device, characterized in that, The system includes an absorption tower and a backspray tower. The backspray tower has an exhaust gas inlet at its upper part and a gas-liquid outlet at its lower part connected to the gas-liquid inlet of the absorption tower. The backspray tower is equipped with two sets of opposing Venturi jet devices, each set including at least two Venturi injectors. The liquid inlet of the Venturi jet device is connected to the liquid outlet of the absorption tower. The top of the absorption tower has a gas outlet, and a demister is located above the gas-liquid inlet inside the absorption tower. The exhaust gas to be treated entering the backspray tower is absorbed and reacted by the absorbent liquid from the opposing collision of the two sets of Venturi jet devices before entering the absorption tower, and then discharged from the gas outlet through the demister. The exhaust gas inlet is located above the point where the liquid columns ejected by the upper and lower sets of Venturi injectors collide; the Venturi injectors have inlet and outlet ports at both ends, and a self-priming air inlet is provided on the side wall of the Venturi injectors; the throat convergence angle of the Venturi injectors is 30-35°, and the gas-liquid ratio is 3-5; the liquid columns ejected by the Venturi injectors spew out tiny droplets with a diameter of 120-250μm, and the collision of the liquid columns ejected by the upper and lower sets of Venturi injectors produces small droplets of 300-550μm.

2. The Venturi-assisted liquid-sprayed enhanced flue gas desulfurization device according to claim 1, characterized in that, The inlet end of the Venturi jet device is also connected to a liquid distributor, and the inlet pipe of the liquid distributor is connected to the outlet; the Venturi jets are evenly distributed along the liquid distributor in the reverse spray tower.

3. The Venturi-assisted liquid-sprayed enhanced flue gas desulfurization device according to claim 1, characterized in that, The exhaust gas inlet of the reverse spray tower and the gas outlet of the absorption tower are both equipped with exhaust gas composition detection devices and exhaust gas flow monitoring devices; the drain outlet of the absorption tower and the pipeline connecting the two sets of Venturi spray devices are equipped with liquid flow meters, pressure gauges and circulating water pumps.

4. A method for enhancing flue gas desulfurization with a Venturi spray column, characterized in that, Flue gas desulfurization is performed using the Venturi jet-enhanced flue gas desulfurization device according to any one of claims 1-3.

5. The method for enhanced flue gas desulfurization using a Venturi spray column according to claim 4, characterized in that, The process includes the following steps: the exhaust gas to be treated enters the reverse spray tower, first flows in the same direction as the downward spray columns of the two sets of Venturi spray devices, then flows in the opposite direction to the upward spray columns, and then flows in the same direction as the falling liquid columns and droplets. At the same time, the tiny droplets ejected from the downward and upward spray columns, as well as the droplets generated by the collision between the upward and downward spray columns, react with and are absorbed by the exhaust gas. The gas after the reaction enters the absorption tower through the lower part of the reverse spray tower, and is then treated by the demister before being discharged from the gas outlet.

6. The method for enhanced flue gas desulfurization using a Venturi spray column according to claim 4, characterized in that, The height of the liquid column sprayed by the Venturi jet device is 0.7-1.5m.

7. The method for enhanced flue gas desulfurization using a Venturi jet column according to claim 4, characterized in that, The Venturi jet device ejects a liquid column that bursts out into tiny droplets with a diameter of 120-250μm. The upper and lower sets of Venturi jet devices spray liquid columns that collide to produce small droplets of 300-550μm.

8. The method for enhanced flue gas desulfurization using a Venturi jet column according to claim 4, characterized in that, The exhaust gas inlet is located above the point where the liquid columns injected by the upper and lower sets of Venturi injection devices meet and collide.

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