Device for recovering hydrochloric acid in cellulose ether production waste gas treatment process

Abstract

The utility model relates to a hydrochloric acid recovery device in a cellulose ether production waste gas treatment process, which belongs to the technical field of waste gas treatment in the cellulose ether industry and comprises a first-stage water scrubber and a second-stage water scrubber which are connected in series in a pipeline and are both provided with graphite heat exchangers for cooling circulating water. A flue gas spraying tower for pre-cooling flue gas is further arranged on a flue gas inlet pipe of the first-stage water washing tower; the hydrochloric acid recovery device in the cellulose ether production waste gas treatment process is mounted in front of an alkali spray tower, hydrogen chloride in flue gas is absorbed and removed through two stages of water scrubber, the recovery rate of acid gas formed by burning the cellulose ether production waste gas can reach 75-80%, and the hydrochloric acid recovery rate can reach 75-80% on the premise of ensuring that gas emission reaches the standard. The consumption of the liquid caustic soda, the yield of the waste brine and the treatment cost are all reduced by 75-80%, meanwhile, diluted hydrochloric acid is generated, the use amount of acid in a plant is saved, and the operation cost is reduced.

Description

Technical Field

[0001] The utility model relates to a hydrochloric acid recovery device in the process of treating waste gas produced by cellulose ether, belonging to the technical field of waste gas treatment in the cellulose ether industry. Background Art

[0002] The production waste gas of the cellulose ether industry is generally treated by incineration. Since the waste gas contains a large amount of incompletely reacted methyl chloride, the flue gas after incineration will contain a high concentration of hydrogen chloride gas. In the prior art, the deacidification process after incineration uses alkali spraying to remove hydrogen chloride in the flue gas to ensure that the exhaust gas meets the standards. However, this method consumes a large amount of liquid alkali, and the evaporation treatment of the waste brine formed requires additional steam resources, and the overall operating cost is extremely high. Utility Model Content

[0003] In view of the above deficiencies in the prior art, the technical problem to be solved by the utility model is to provide a hydrochloric acid recovery device during the treatment of cellulose ether production waste gas, which can significantly reduce the operating cost of the post-incineration deacidification process while ensuring that the gas emissions meet the standards.

[0004] The utility model discloses a hydrochloric acid recovery device in the process of treating waste gas produced by cellulose ether, comprising a primary water washing tower and a secondary water washing tower, wherein the primary water washing tower and the secondary water washing tower are connected in series in a pipeline, and both the two-stage water washing towers are provided with a graphite heat exchanger for cooling circulating water, and a flue gas spray tower for pre-cooling the flue gas is also provided on the flue gas inlet pipe of the primary water washing tower.

[0005] The technical solution of the utility model is to provide a hydrochloric acid recovery device in the process of treating waste gas from cellulose ether production, which is installed in front of the alkali spray tower, and absorbs and removes hydrogen chloride in the flue gas through a two-stage water washing tower, thereby reducing the subsequent consumption of liquid alkali and the output of waste brine, reducing operating costs, and generating dilute hydrochloric acid at the same time, saving acid usage in the factory.

[0006] Preferably, the primary water scrubber and the secondary water scrubber are both provided with a circulating spray pipe, which sequentially connects the water tank of the water scrubber, the circulating pump in the water scrubber, the graphite heat exchanger and the spray pipe above the water scrubber; the graphite heat exchanger is used to cool the circulating water to ensure that the spray temperature is at a relatively low level.

[0007] Preferably, the top of the flue gas spray tower is connected to the flue gas inlet pipe, and the bottom of the flue gas spray tower is connected to the air inlet of the primary water washing tower through a pipeline. The flue gas spray tower is provided with a spray pipe, and the flue gas spray tower is sequentially connected to the pre-cooling circulation pump and the water tank of the primary water washing tower through the spray pipe; the circulating water in the water tank of the primary water washing tower is sent into the flue gas spray tower through the pre-cooling circulation pump, and the flue gas is sprayed and pre-cooled, and then enters the interior of the primary water washing tower through the air inlet of the primary water washing tower along the pipeline.

[0008] Furthermore, the water washing tower water tank is provided with a water washing tower water supply pipe and an acid external discharge pipe, valves are installed on the water washing tower water supply pipe and the acid external discharge pipe, and the water washing tower water tank is also equipped with an acidity meter for detecting the concentration of hydrochloric acid in the water tank.

[0009] Furthermore, the top air outlet of the primary water washing tower is connected to the air inlet of the secondary water washing tower through a pipeline, and the top air outlet of the secondary water washing tower is connected to the alkali spray tower of the subsequent process through a pipeline.

[0010] Thermometers are installed on the connecting pipes between the flue gas spray tower and the air inlet of the primary water washing tower, and on the connecting pipes between the air outlet of the primary water washing tower and the air inlet of the secondary water washing tower.

[0011] Compared with the prior art, the utility model has the following beneficial effects:

[0012] The hydrochloric acid recovery device in the process of treating the waste gas from the production of cellulose ether disclosed by the utility model is installed in front of the alkali spray tower, and the hydrogen chloride in the flue gas is absorbed and removed by a two-stage water washing tower, and the recovery rate of the acid gas formed by the incineration of the waste gas from the production of cellulose ether can reach 75-80%. Under the premise of ensuring that the gas emission meets the standard, the subsequent consumption of liquid alkali and the output of waste brine are reduced, and the consumption of liquid alkali, the output of waste brine and the treatment cost are all reduced by 75-80%. At the same time, dilute hydrochloric acid is generated, which saves the acid consumption in the factory and reduces the operation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a process flow chart of the utility model.

[0014] In the figure: 1. Primary water scrubber; 2. Pre-cooling circulation pump; 3. Circulation pump inside the water scrubber; 4. Thermometer; 5. Water supply pipe for the water scrubber; 6. Graphite heat exchanger; 7. Acidity meter; 8. Acid exhaust pipe; 9. Flue gas inlet pipe; 10. Flue gas spray tower; 11. Secondary water scrubber. DETAILED DESCRIPTION

[0015] The utility model is further described below in conjunction with specific embodiments.

[0016] However, the description of the present invention is merely an embodiment of structural and even functional description, and the scope of rights of the present invention is not limited by the embodiments described in the text.

[0017] For example, multiple embodiments may have multiple changes and multiple forms, and it should be understood that the scope of rights of the present utility model includes equivalents that can realize the technical idea.

[0018] like Figure 1As shown, this embodiment is implemented through the following technical scheme: it includes a primary water scrubber 1 and a secondary water scrubber 11, the material of the water scrubber is glass fiber reinforced plastic, the spraying medium is water, and the water is circulated and sprayed in the water scrubber; the primary water scrubber 1 and the secondary water scrubber 11 are connected in series in the pipeline, and the two-stage water scrubbers are both provided with a graphite heat exchanger 6 for cooling the circulating water, and the flue gas inlet pipe 9 of the primary water scrubber 1 is also provided with a flue gas spray tower 10 for pre-cooling the flue gas.

[0019] In this embodiment, the primary water scrubber 1 and the secondary water scrubber 11 are both provided with a circulating spray pipe, which sequentially connects the water scrubber water tank, the circulating pump 3 in the water scrubber, the graphite heat exchanger 6 and the spray pipe above the water scrubber; the graphite heat exchanger 6 is used to cool the circulating water to ensure that the spray temperature is at a relatively low level. The top of the flue gas spray tower 10 is connected to the flue gas inlet pipe 9, and the bottom of the flue gas spray tower 10 is connected to the air inlet of the primary water scrubber 1 through a pipe. The flue gas spray tower 10 is provided with a spray pipe, and the flue gas spray tower 10 is sequentially connected to the pre-cooling circulating pump 2 and the water tank of the primary water scrubber 1 through the spray pipe; the circulating water in the water tank of the primary water scrubber 1 is sent into the flue gas spray tower 10 through the pre-cooling circulating pump 2, and the flue gas is sprayed and pre-cooled, and then enters the interior of the primary water scrubber 1 through the air inlet of the primary water scrubber 1 along the pipe.

[0020] The water tank of the water washing tower is provided with a water washing tower water supply pipe 5 and an acid external discharge pipe 8. The water washing tower water supply pipe 5 is used to replenish circulating water to the water washing tower, and the acid external discharge pipe 8 is used to discharge the hydrochloric acid produced by the continuous circulation of the water washing tower; valves are installed on the water washing tower water supply pipe 5 and the acid external discharge pipe 8, and the water tank of the water washing tower is also installed with an acidity meter 7 for detecting the concentration of hydrochloric acid in the water tank. The top air outlet of the primary water washing tower 1 is connected to the air inlet of the secondary water washing tower 11 through a pipeline, and the top air outlet of the secondary water washing tower 11 is connected to the alkali spray tower of the subsequent process through a pipeline. The thermometer 4 is installed on the pipe connecting the flue gas spray tower 10 with the air inlet of the primary water washing tower 1, and the pipe connecting the air outlet of the primary water washing tower 1 and the air inlet of the secondary water washing tower 11.

[0021] The working process of the utility model is:

[0022] 1. The flue gas after incineration enters the flue gas spray tower 10 through the flue gas inlet pipe 9. The pre-cooling circulation pump 2 draws circulating water from the water tank of the primary water washing tower 1 to spray and pre-cool the flue gas to prevent the flue gas from damaging the subsequent devices due to excessive temperature;

[0023] 2. The cooled flue gas enters the primary water scrubber 1 from the air inlet below the primary water scrubber 1 and is discharged from the air outlet at the top of the primary water scrubber 1. During this process, the circulating water in the water tank of the primary water scrubber 1 is drawn by the circulating pump 3 in the water scrubber to spray the flue gas, and the circulating water is cooled by the graphite heat exchanger 6 to ensure that the spraying temperature is at a low level. The circulating water absorbs the hydrogen chloride in the flue gas to generate hydrochloric acid.

[0024] 3. The flue gas discharged from the primary water scrubber 1 enters the secondary water scrubber 11 along the pipeline, undergoes secondary absorption treatment in the secondary water scrubber 11, and the treated flue gas is discharged from the air outlet at the top of the secondary water scrubber 11 and enters the subsequent alkali spray tower;

[0025] 4. With the continuous treatment of flue gas, the concentration of hydrochloric acid in the water tank of the two-stage water washing tower gradually increases. When the acidity meter 7 reaches the set value, the valve on the acid discharge pipe 8 automatically opens to discharge the hydrochloric acid and reuse it in production; when the circulating water in the water tank of the water washing tower is discharged to a lower liquid level, circulating water is added to the water washing tower through the water washing tower water supply pipe 5.

[0026] Of course, the above contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of the embodiments of the present invention. The present invention is not limited to the above examples, and any equivalent changes and improvements made by ordinary technicians in the technical field within the essential scope of the present invention shall fall within the scope of the patent coverage of the present invention.

Claims

1. A hydrochloric acid recovery device in the process of treating waste gas from cellulose ether production, characterized in that: The invention comprises a primary water scrubber (1) and a secondary water scrubber (11), wherein the primary water scrubber (1) and the secondary water scrubber (11) are connected in series in a pipeline, and both the primary water scrubbers are provided with a graphite heat exchanger (6) for cooling circulating water, and a flue gas spray tower (10) for pre-cooling the flue gas is also provided on the flue gas inlet pipe (9) of the primary water scrubber (1).

2. The hydrochloric acid recovery device in the process of treating waste gas from cellulose ether production according to claim 1, characterized in that: The primary water washing tower (1) and the secondary water washing tower (11) are both provided with a circulating spray pipe, which sequentially connects the water tank of the water washing tower, the circulating pump (3) in the water washing tower, the graphite heat exchanger (6) and the spray pipe above the water washing tower.

3. The hydrochloric acid recovery device in the process of treating waste gas from cellulose ether production according to claim 2, characterized in that: The top of the flue gas spray tower (10) is connected to the flue gas inlet pipe (9), and the bottom of the flue gas spray tower (10) is connected to the air inlet of the primary water washing tower (1) through a pipeline. The flue gas spray tower (10) is provided with a spray pipeline, and the flue gas spray tower (10) is connected to the pre-cooling circulation pump (2) and the water tank of the primary water washing tower (1) in sequence through the spray pipeline; the circulating water in the water tank of the primary water washing tower (1) is sent into the flue gas spray tower (10) through the pre-cooling circulation pump (2).

4. The hydrochloric acid recovery device in the process of treating waste gas from cellulose ether production according to claim 2, characterized in that: The water washing tower water tank is provided with a water washing tower water supply pipe (5) and an acid external discharge pipe (8), both of which are equipped with valves. The water washing tower water tank is also equipped with an acidity meter (7) for detecting the concentration of hydrochloric acid in the water tank.

5. The hydrochloric acid recovery device in the process of treating waste gas from cellulose ether production according to claim 1, characterized in that: The top air outlet of the primary water washing tower (1) is connected to the air inlet of the secondary water washing tower (11) through a pipeline, and the top air outlet of the secondary water washing tower (11) is connected to the alkali spray tower of the subsequent process through a pipeline.

6. The hydrochloric acid recovery device in the process of treating waste gas from cellulose ether production according to claim 3, characterized in that: Thermometers (4) are installed on the pipe connecting the flue gas spray tower (10) and the air inlet of the primary water washing tower (1), and on the pipe connecting the air outlet of the primary water washing tower (1) and the air inlet of the secondary water washing tower (11).

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