CN104645812A - Purification method for tail gas of calcium carbide furnace - Google Patents

Abstract

The invention relates a purification method for tail gas of a calcium carbide furnace. The invention aims at providing an effective process, and solid dust particles and the like in the tail gas of the calcium carbide furnace can be removed, so that the clean emission of the tail gas is realized. The purification method particularly comprises a wet-process absorption step and a dry-process dust removing step; and in the wet-process absorption step, dust in the tail gas can be absorbed by an absorption tower, and in the dry-process dust removing step, residual dust in the gas can be further removed by adopting a dust remover.

Description

A method for purifying tail gas of calcium carbide furnace

technical field

The invention relates to a method for purifying tail gas of a calcium carbide furnace.

Background technique

Calcium carbide production is generally carried out in calcium carbide furnaces, where high temperatures are generated by electric arcs, and calcium oxide reacts with carbon to form calcium carbide (calcium carbide) and carbon monoxide. In addition to a large amount of carbon monoxide, the exhaust gas of the closed calcium carbide furnace also contains a large amount of dust. For example, about 400 cubic meters of exhaust gas can be produced by producing one ton of calcium carbide furnace. The exhaust gas of calcium carbide furnace mainly contains CO, _H2, etc., of which 85% All of the above are CO gas. For the treatment of calcium carbide furnace tail gas, most enterprises burn it with torches, which pollutes the environment and wastes carbon monoxide resources. Carbon monoxide can be used to manufacture sodium formate, ethylene glycol and other products, which has high commercial value and should be effectively use. If it is necessary to utilize the CO in the exhaust gas of the calcium carbide furnace, a large amount of dust contained in the exhaust gas of the calcium carbide furnace must be treated to remove particulate pollutants to obtain a clean CO-based exhaust gas, which can then be utilized. The currently known dust treatment methods mainly include wet treatment and dry treatment, both of which have their own advantages and disadvantages. It is difficult for existing technologies to efficiently remove dust particles in the exhaust gas of calcium carbide furnaces. Therefore, it is urgent to develop a more It is an effective technical means to process the exhaust gas to obtain clean exhaust gas.

Contents of the invention

The object of the present invention is to provide an effective process for removing solid particles in the tail gas of a calcium carbide furnace, so as to realize clean discharge of the tail gas.

The technical scheme adopted by the present invention to solve the technical problem is: a method for purifying calcium carbide furnace tail gas, including a wet absorption step and a dry dust removal step, characterized in that the tail gas first enters the absorption tower 1, and the gas inlet 2 of the absorption tower enters After the absorption tower 1, it becomes a plurality of branch inlets 6, and the branch inlets 6 are evenly distributed in the absorption tower along the oblique line from top to bottom. The uppermost branch inlet is the closest to the gas inlet 2, and the lowermost branch inlet is the furthest A corresponding sprayer 5 is arranged on the upper part of each branch entrance, and the distance between each sprayer 5 and the corresponding branch entrance is 0.5-2m; the water sprayed by the sprayer catches the dust particles in the exhaust gas of the calcium carbide furnace and falls into the bottom of the absorption tower , the water at the bottom is circulated back to the sprayer under the action of the circulation pump 7 to continue to absorb and remove dust;

The exhaust gas discharged from the absorption tower 1 then enters the dust collector 10. The exhaust gas first enters the dust collector from the inlet 11 of the dust collector, and the exhaust gas impacts on the shunt cover 12 head-on. The flow chamber 33 in the device expansion section 17, the exhaust gas passes through the flow chamber 33 and contacts the filter element 30 in the filter element support frame 29, and the gas passes through the filter element 30 and is filtered and enters the exhaust chamber 32 to be discharged from the dust collector;

A small part of the exhaust gas hits the shunt cover 12 and flows down along the shunt cover 12, and hits 3-10 blades 28 fixed on the upper top plate 39 of the filter element support frame 29. The inner wall of the filter element support frame 29 is provided with a spiral slideway 36, The spiral slideway 36 cooperates with the second spiral slideway on the outer wall of the annular inner baffle plate 15, the exhaust gas hits the blade 28, and the blade 28 drives the filter element support frame 29 to move downward while rotating along the second spiral slideway, and the bottom of the support frame 29 The bottom plate 40 is connected with a buffer component 27, and the other end of the buffer component 27 is fixed on the support block 20 on the inner wall 19 of the ash collection chamber; the support frame 29 rotates and moves downward together with the filter core 30, and the lower end of the filter core 30 enters the ash collection chamber 34, A scraper 22 is arranged on the outer wall 18 of the ring-shaped ash-collecting chamber near the entrance of the ash-collecting chamber 34. A brush 23 is provided below the scraper 22. A nozzle 24 is provided at a corresponding position in the inner wall 19 of the ash-collecting chamber opposite to the brush 23 to feed the filter element. 30 blows back blowing gas; under the joint action of the scraper 22, the brush 23 and the nozzle 24, the particles adsorbed and filtered by the filter element 30 are removed, and the filter element 30 is regenerated.

Preferably, the number of branch entrances is 4-8.

Preferably, the distance between the sprayer and the branch inlet is 1-1.5m.

Preferably, the filter element of the dust remover is an activated carbon filter element, polypropylene fiber, metal fiber, glass fiber.

Preferably, the number of blades is 7 pieces.

Preferably, the buffer component is a damping rod, a hydraulic rod or a spring, and the number thereof may be 2-8.

Preferably, the shunt cover is provided with a discharge port.

The beneficial effects of the present invention are:

1. The method of absorbing tabu gas is unique, which greatly improves the gas distribution effect and gas-liquid contact efficiency, and greatly improves the purification effect.

2. During the work of the dust collector, the filter element can rotate continuously for regeneration and recycling, and the regeneration operation does not require additional operating power, and the movement of the filter element can be realized only by the kinetic energy of the exhaust gas itself, saving energy and low consumption.

3. Through the combination of wet dust removal and dry dust removal, the solid particles in the exhaust gas of calcium carbide furnace can be efficiently removed, which is energy-saving and environmentally friendly.

Description of drawings

Fig. 1 is a process roadmap of the present invention.

Fig. 2 is a schematic diagram of the wet absorption tower of the present invention.

Fig. 3 is a front view of the dust remover of the present invention.

Fig. 4 is an AA sectional view of the dust remover of the present invention.

Fig. 5 is a schematic diagram of the shunt hood of the dust remover of the present invention.

Fig. 6 is a perspective view of the support frame of the dust remover of the present invention.

The descriptions of the reference signs and their corresponding parts are as follows:

1. Absorption tower; 2. Absorption tower gas inlet; 3. Absorption tower gas outlet; 4. Demister; 5. Sprayer; 6. Branch inlet; 7. Circulation pump; 10. Dust collector; 11. Dust collector inlet; 12. Shunt cover; 13. Discharge port; 14. Annular outer baffle; 15. Annular inner baffle; 16. Gradually expanding section; 17. Expansion section; 19. Lower baffle; 20. Support block; 21. Seal Ring; 22, scraper; 23, brush; 24, nozzle; 25, blowback valve; 26, ash discharge valve; 27, buffer component; 28, blade; 29, support frame; 30, filter element; 31 filter plate; , exhaust cavity; 33, flow cavity; 34, ash collection cavity; 35, discharge cavity; 36, spiral slideway; 38, fastening ring; 39, top plate; 40, bottom plate

Detailed ways

The following examples are used to illustrate the present invention, but not to limit the scope of the present invention.

The invention relates to a method for purifying the tail gas of a calcium carbide furnace, which comprises a wet absorption step and a dry dust removal step. The temperature of the tail gas from the calcium carbide furnace is about 600°C. The tail gas first enters the absorption tower, and the tail gas enters from the gas inlet of the absorption tower, and reacts with the atomized water. The tail gas releases heat to cool down, and the water evaporates rapidly; the particles and fog in the tail gas The chemical water is fully contacted, the dust content in the tail gas leaving the absorption tower is below 40mg/Nm ³ , and the temperature is below 45°C. The absorbed dust falls into the bottom of the absorption tower together with the absorption liquid.

The exhaust gas treated by the absorption tower then enters the dust collector, and passes through the filter element of the dust collector to effectively remove the remaining solid particles in the exhaust gas. Since a large amount of dust in the exhaust gas has been removed in the absorption tower, the filter element selection in the dust collector is better. For the fine level, further remove fine dust. The purified exhaust gas can be discharged into the atmosphere through induced draft fan and other mechanisms.

Example:

As shown in Figure 1 and Figure 2, the temperature of the tail gas of the calcium carbide furnace is about 600°C, and the tail gas contains CO, dust, etc. The exhaust gas first enters the absorption tower 1, and after the gas inlet 2 of the absorption tower enters the absorption tower 1, it becomes four branch inlets 6. The branch inlets 6 are evenly distributed in the absorption tower along the oblique line from top to bottom, and the uppermost branch inlet is far from the gas inlet. 2 is the closest, and the lowermost branch inlet is farthest from the gas inlet 2. The 4 branch inlets can basically realize the uniform distribution of gas. A corresponding sprayer 5 is provided on the upper part of each branch entrance, and the sprayer 5 is 1m away from the branch entrance. Since the gas inlet is divided into several branch inlets, the capture efficiency can be improved by setting corresponding sprayers at each branch inlet, and the distribution degree of the tail gas in the absorption tower can be improved. In addition to the sprayer 5 provided correspondingly, a conventional sprayer is also arranged on the top of the absorption tower to further improve the gas-liquid contact efficiency. After the atomized water fully captures the dust, it falls into the bottom of the absorption tower, and the absorption liquid at the bottom is circulated back to the sprayer under the action of the circulation pump 7 to continue to participate in the absorption. Through this strong mass transfer process, most of the dust in the exhaust gas can be fully removed. A mist eliminator 4 is installed on the top of the absorption tower, and the wet exhaust gas passes through the mist eliminator 4 and is discharged from the absorption tower gas outlet 3. In the tail gas after passing through the absorption tower, the dust removal rate can reach more than 90%, and the temperature of the tail gas drops below 60°C.

The tail gas discharged from the absorption tower 1 then enters the dust collector 10. The tail gas first enters the dust collector from the dust collector inlet 11, and the tail gas first impacts on the shunt cover 12 head-on. The shunt cover is a conical body. Part of the exhaust gas enters the flow chamber 33 in the expansion section of the dust collector through the gradual expansion section. The wall of the expansion section of the dust collector and the inner annular outer baffle 14 constitute the flow chamber 33. Contact with the filter element 30, the filter element 30 is a glass fiber filter element. The annular outer baffle plate 14 together with the annular inner baffle plate 15, the outer wall 18 of the ash collection chamber and the inner wall 19 of the ash collection chamber together constitute the gas flow path on the filter element 30, and a sealing ring 21 is arranged between the filter element 30 and the outer wall 18 of the ash collection chamber. It is used to prevent gas from entering the ash collection chamber 34 without passing through the filter element 30 . Particles in the gas are adsorbed and filtered by the filter element 30, and the purified gas enters the exhaust chamber 32 and is discharged from the dust collector after being filtered by the filter element 30. The ring-shaped filter element 30 will deposit a layer of filtered particles on the surface of the filter element during filtering, and the deposited particles will reduce the filtering effect of the filter element, so the filter element needs to be periodically regenerated.

The regeneration process of the filter element 30: see Fig. 3, Fig. 4, Fig. 6. After the exhaust gas enters the dust collector from the dust collector inlet 11, as mentioned above, most of the exhaust gas enters the flow chamber 33 under the guidance of the shunt cover 12 and enters the filtering stage. The cover 12 flows downwards and hits the fixed blade 28 on the top plate 39 of the filter element support frame 29. The inner wall of the filter element support frame 29 is provided with a spiral slideway 36, and the spiral slideway 36 and the spiral slideway on the outer wall of the annular inner baffle (not shown) Shown) fits, therefore, tail gas hits vane 28, and vane 28 drives filter element support frame 29 to move downwards while rotating under the support and guidance of the spiral slideway. The support frame 29 rotates and moves downward together with the filter element 30 and enters the ash collection chamber 34. The support frame 29 is in close contact with the inner wall 19 of the ash collection chamber. There is a certain space between the filter element 30 and the outer wall 18 of the ash collection chamber. Close to the entrance of the ash collection chamber, there are two scrapers 22 correspondingly arranged first. The scrapers 22 are close to the filter element 30. A brush 23 is arranged under the scraper 22. The bristles of the brush 23 contact the filter element 30. The inner wall 19 of the ash collection chamber opposite to the brush 23 is A nozzle 24 is provided at a corresponding position for blowing back blowing gas to the back of the filter element 30 , and a back blowing valve 25 controls the flow rate of the back blowing gas. Under the action of the scraper 22, the impurities deposited on the surface of the rotating filter element 30 are scraped off by the scraper, and the filter element 30 further rotates and descends, and then the particulate matter adsorbed and filtered by the filter element 30 is further removed under the combined action of the brush 23 and the nozzle 24. It can be regenerated under the treatment of multiple regeneration methods. The removed impurities fall into the bottom of the ash collecting chamber 34, and after accumulating to a certain extent, they are discharged out of the dust collector through the ash unloading valve 26. The amount of ash accumulated in the ash collection chamber 34 can be detected by automatic detection means such as particle sensor detection.

Referring to Fig. 3, the bottom circumference of the shunt cover 12 is fixedly connected with the annular inner baffle 15, the support frame 29 rotates and descends around the annular inner baffle 15, and the bottom plate 40 at the bottom of the support frame 29 is connected with a buffer member 27, the buffer member is preferably The damping rod, the other end of the buffer component 27 is fixed on the support block 20 on the inner wall of the ash collecting cavity. The effect of buffer member 27 is to control the descending speed of support frame 29, prevents descending too fast. The position and quantity of the buffering member 27 can be selected according to needs, and it is advisable not to block the nozzle 24 of course. In FIG. Of course, other devices with similar functions can also be used, such as hydraulic rods, springs and the like. In addition, the descending speed of the support frame 29 can also be adjusted by setting blades 28 of different numbers and angles. In this embodiment, the number of blades is preferably 7. According to the flow velocity of the exhaust gas, 7 blades can achieve a better rotation speed. It is also possible to reduce or increase the descending speed of the support frame 29 by setting fewer or more blades, for example, 3 blades, 5 blades, 10 blades, etc. During the regeneration process, when most of the filter element 30 has fallen into the ash collection chamber 34 and is regenerated, the buffer component or other similar components can be controlled to reversely pressurize the support frame 29, such as stopping the air intake, the compressed buffer component will Prompt the support frame 29 to reversely rotate and rise back to the initial working state, and thus work in a cyclical manner.

Referring to FIG. 5 , this figure is a perspective view of the shunt cover 12 . A discharge port 13 may be provided on the flow cover 12 . Normally, the discharge port 13 is closed and gas cannot pass through the flow cover 12 . When the pressure sensor (not shown) in the dust collector measures that the pressure in the dust collector is higher than the normal value, the discharge port 13 is opened, and the air flow can flow through the discharge port 13, enter the discharge cavity 35, and pass through the filter plate 31 After filtration, it is discharged from the dust collector. The opening and closing of the discharge port 13 can be remotely controlled by a closing switch at the discharge port. When the dust collector is running, sometimes it encounters the input air flow with large fluctuations in flow rate and flow velocity, and sometimes encounters accidental clogging of the filter. When encountering a similar situation that increases the pressure inside the dust collector, it can be opened to ensure production safety. The discharge port 13 is used to quickly reduce the pressure in the dust collector to prevent damage to the filter element or the dust collector. Due to the existence of the filter plate 31, the safety of the discharged gas can also be ensured.

Referring to Fig. 6, this figure is a perspective view of the support frame 29, the blade 28 is fixed on the top plate 39 at the upper end of the support frame 29, the main body of the support frame 29 is composed of a vertical grid and a plurality of fastening rings 38 for reinforcement The substantially net-like air-permeable structure, the inner wall of the support frame 29 is fixed with a spiral slideway 36 to guide the support frame 29 to rotate and descend around the annular inner baffle. The material of the support frame 29 and the spiral slideway 36 can be any material with certain rigidity, such as stainless steel, plastic and the like.

After the tail gas passes through the absorption tower 1 and the dust collector 10, the solid particles in the gas are basically removed, and the gas reaches the discharge standard.

In the purification method of the present invention, the absorption tower used greatly improves the gas distribution effect and gas-liquid contact efficiency through a unique gas distribution means, and greatly improves the purification effect. The filter element used by the dust collector can be continuously regenerated and recycled during operation, and no additional operating power is required, and the regeneration of the filter element can be realized only by the kinetic energy of the exhaust gas itself. Due to the combined use of the absorption tower and the dust collector of the present invention, the harmful substances in the tail gas of the calcium carbide furnace are effectively removed, and the clean discharge of the tail gas is realized.

The embodiment described above is only a preferred solution of the present invention, and does not limit the present invention in any form. There are other variations and modifications on the premise of not exceeding the technical solution described in the claims.

Claims (7)

1. a purification method of calcium carbide furnace tail gas, comprising wet absorption step and dry dust removal step, is characterized in that: tail gas enters absorption tower (1) at first, and absorption tower gas inlet (2) changes after entering absorption tower (1) It is a plurality of branch inlets (6), and the branch inlets (6) are evenly distributed in the absorption tower along the oblique line from top to bottom, the uppermost branch inlet is the closest to the gas inlet (2), and the lowermost branch inlet is the closest to the gas inlet ( 2) The farthest; a corresponding sprayer (5) is provided on the upper part of each branch entrance, and the distance from each sprayer (5) to the corresponding branch entrance is 0.5-2m; the water sprayed by the sprayer captures the dust in the calcium carbide furnace tail gas The particles fall into the bottom of the absorption tower, and the water at the bottom circulates back to the sprayer under the action of the circulation pump (7) to continue to absorb and remove dust; the tail gas discharged from the absorption tower 1 then enters the dust collector 10, and the tail gas first enters the dust collector from the inlet 11 of the dust collector The tail gas impacts on the shunt cover 12 head-on, and the shunt cover is a conical body. Most of the tail gas enters the flow chamber 33 in the expansion section 17 of the dust collector through the gradual expansion section 16. The filter element 30 contacts, and the gas passes through the filter element 30 to filter and then enters the exhaust chamber 32 to be discharged from the dust collector; a small part of the exhaust gas hits the shunt cover (12) and then flows down along the shunt cover (12), hitting the filter element support frame (29) 3-10 blades (28) are fixed on the upper top plate (39), and the inner wall of the filter element support frame (29) is provided with a spiral slideway (36). With the cooperation of the second spiral slideway, the exhaust gas hits the blade (28), and the blade (28) drives the filter element support frame (29) to move downward while rotating along the second spiral slideway, and the bottom plate (40) at the bottom of the support frame (29) A buffer component (27) is connected to the top, and the other end of the buffer component (27) is fixed on the support block (20) on the inner wall (19) of the ash collection chamber; the support frame (29) rotates and moves downward together with the filter element (30), The lower end of the filter element (30) enters the ash collection chamber (34), and a scraper (22) is correspondingly arranged in the outer wall (18) of the annular ash collection chamber (18) near the entrance of the ash collection chamber (34), and a brush (22) is arranged below the scraper (22). 23), a nozzle (24) is provided at the corresponding position in the ash collecting chamber inner wall (19) opposite to the brush (23) to blow back blowing gas to the back of the filter element (30); at the scraper (22), the brush (23 ) and the nozzle (24) to remove the particulate matter adsorbed and filtered by the filter element (30), and the filter element (30) is regenerated. 2. The method for purifying calcium carbide furnace tail gas according to claim 1, characterized in that: the number of branch inlets (6) is 4-8. 3. The method for purifying calcium carbide furnace tail gas according to claim 1, characterized in that the distance between the sprayer (5) and the branch inlet (6) is 1-1.5m. 4. The purification method of calcium carbide furnace tail gas according to claim 1, characterized in that: the filter element (30) of the dust collector is activated carbon, polypropylene fiber, metal fiber, glass fiber. 5. The method for purifying calcium carbide furnace tail gas according to claim 1, characterized in that: the number of blades (28) is seven. 6. The method for purifying calcium carbide furnace tail gas according to claim 1, characterized in that: the buffer member (27) is a damping rod, a hydraulic rod or a spring, the number of which is 2-8. 7. The method for purifying calcium carbide furnace tail gas according to claim 1, characterized in that: the shunt cover (12) is provided with a discharge port (13).