CN219319088U - Hydrochloric acid recovery system in tail gas of phosphorous acid production - Google Patents

Abstract

The utility model relates to the field of phosphorous acid production, and provides a hydrochloric acid recovery system in tail gas generated in phosphorous acid production. Consists of three condensers, a tail gas absorption tower, a water seal tank and the like. Three condensers are connected in series in turn for cooling the incoming gas. Hydrochloric acid in each storage tank flows back to the condenser of the current stage or the previous stage in a circulating pump or overflow mode. The system is provided with a tail gas absorption tower, the unabsorbed hydrochloric acid in the three-stage condenser is absorbed again through the tail gas absorption tower, residual gas which is not absorbed in the absorption tower is absorbed for the last time through a water seal tank, and the residual gas after multiple times of absorption is sent into a tail gas absorption total tower; after the absorption is completed, the residual gas in each storage tank is sent into a tail gas absorption total tower for treatment; according to the technical scheme, through the three condensers, the tail gas absorption tower and the water seal tank, the modes of condensation, backflow, water absorption and the like are matched, hydrochloric acid in the tail gas of the hydrolysis tower is fully absorbed, waste is less, and the tail gas absorption capacity of the tail gas absorption total tower is less.

Description

Hydrochloric acid recovery system in tail gas of phosphorous acid production

technical field

The utility model relates to the field of phosphorous acid production, in particular to a recovery system for hydrochloric acid in the tail gas of phosphorous acid production.

Background technique

The production process of phosphorous acid is to use hydrochloric acid and phosphorus trichloride to hydrolyze at high temperature. After hydrolysis, phosphorous acid and hydrochloric acid are obtained. The liquid phosphorous acid and part of hydrochloric acid are left at the bottom of the hydrolysis tower, pumped out and sent to the deacidification tower. After treatment, the by-product hydrochloric acid is extracted and a high-purity phosphorous acid product is obtained. The tail gas discharged from the top of the hydrolysis tower contains a large amount of gaseous hydrogen chloride gas and water vapor.

Since hydrochloric acid is one of the raw materials for the reaction and hydrochloric acid is an important raw material in chemical production, if the gaseous hydrochloric acid is directly sent to the tail gas absorption tower of the workshop for neutralization treatment, it will cause waste of materials and waste of chemicals used for tail gas absorption , increase the workload of exhaust gas absorption. Therefore, in the production process, the hydrochloric acid in the tail gas will be recovered. The usual way is to condense the tail gas, and the hydrogen chloride and water vapor will be condensed into hydrochloric acid and collected. Because the tail gas passes through the condenser faster, the hydrochloric acid cannot be guaranteed. The complete condensate recovery, part of the unrecovered gas containing hydrochloric acid still needs to be absorbed and treated by the total tail gas absorption tower.

Contents of the invention

In order to solve the recovery problem of hydrochloric acid in the process of producing phosphorous acid by hydrolysis and avoid the waste of hydrochloric acid and the load on the total tail gas absorption tower, the purpose of this utility model is to provide a recovery system for hydrochloric acid in the tail gas of phosphorous acid production with multi-stage condensation recovery.

The technical scheme that the utility model takes is:

Hydrochloric acid recovery system in the tail gas of phosphorous acid production, including at least one condensate receiving tank, a primary condenser and a hydrochloric acid product tank, the primary condenser is fed with circulating cooling water, and the tail gas containing hydrochloric acid in the hydrolysis tower enters the primary condenser The condensed liquid hydrochloric acid enters the condenser receiving tank, and the hydrochloric acid collected by the condenser receiving tank enters the hydrochloric acid product tank, which also includes a secondary condenser, a tertiary condenser and a tail gas absorption tower. In the primary condenser and The unliquefied gas entering the hydrochloric acid product tank enters the secondary condenser through the pipeline, and the unliquefied gas in the secondary condenser and the hydrochloric acid product tank enters the third-stage condenser through the pipeline, and the bottom of the third-stage condenser is connected with an intermediate The unliquefied gas in the acid receiving tank, the three-stage condenser and the intermediate acid receiving tank enters the tail gas absorption tower through pipelines; the bottom of the receiving tower is a hydrochloric acid receiving tank, and packing is installed above the hydrochloric acid receiving tank, and the tail gas absorbing tower The air inlet is located between the hydrochloric acid receiving tank and the filler, and the top of the tail gas absorption tower is provided with a tail gas discharge port, which is connected to the tail gas absorption total tower of the workshop; the hydrochloric acid in the hydrochloric acid receiving tank and the intermediate acid receiving tank are respectively Return to the third condenser and the second condenser.

Further, the bottoms of the intermediate acid receiving tank and the hydrochloric acid receiving tank are respectively connected with circulation pumps, the hydrochloric acid in the intermediate acid receiving tank is sent to the third condenser for circulation by the circulation pump, and the hydrochloric acid in the hydrochloric acid receiving tank is circulated by the circulation pump The top circulation of the tail gas absorption tower is produced.

Further, a liquid distribution pipe is installed on the top of the tail gas absorption tower, the liquid distribution pipe is located above the filler, and the liquid distribution pipe is connected to the output end of the corresponding circulation pump.

Further, a water seal tank is provided on one side of the tail gas absorption tower, and the water seal tank is connected with pure water input, and the exhaust port at the top of the tail gas absorption tower is inserted below the liquid level of the water seal tank through a pipeline, and the water seal tank is The top is connected to the total exhaust gas absorption tower of the workshop through pipelines.

Further, the water seal tank is connected with a circulation pump, and the circulation pump extracts hydrochloric acid from the water seal tank and sends it to the third condenser.

Further, the hydrochloric acid product tank is provided with a tanker interface, the hydrochloric acid product pipe is connected to a hydrochloric acid extraction pump, and the output end of the hydrochloric acid extraction pump is respectively connected to a hydrochloric acid metering tank and a hydrochloric acid storage tank through a branch pipeline.

Further, the tops of the hydrochloric acid receiving tank, the intermediate acid receiving tank and the hydrochloric acid receiving tank are respectively connected to the tail gas absorption total tower through pipelines, and valves are installed on each pipeline.

After adopting the above technical scheme, the beneficial effects of the utility model are:

Through the setting of three-stage condensers in series, the uncondensed gas in the upper-stage condenser enters the next-stage condenser to continue to condense, and the condensed hydrochloric acid enters the corresponding storage tank. Under the guidance, the height difference between the storage tanks is used to overflow to the finished hydrochloric acid tank for centralized collection. The concentrated hydrochloric acid finished product can be directly loaded on a car or sent to a large storage tank or a metering tank, which is convenient for repeated use in production.

The hydrochloric acid in each storage tank is returned to the condenser of the current stage or the previous stage through the circulation pump or the overflow method. The reflux process can accelerate the absorption of gaseous hydrochloric acid and make the recovery of hydrochloric acid more complete.

The system is equipped with a tail gas absorption tower, which absorbs the unabsorbed hydrochloric acid in the third-stage condenser again through the tail gas absorption tower, and absorbs the unabsorbed residual gas in the absorption tower through the water seal tank for the last time. The residual gas is sent to the total tail gas absorption tower; after the absorption is completed, the residual gas in each storage tank is sent to the total tail gas absorption tower for treatment;

This technical solution fully absorbs the hydrochloric acid in the tail gas of the hydrolysis tower through three condensers, a tail gas absorption tower and a water-sealed tank, in conjunction with condensation, reflux, and water absorption, with less waste and less tail gas absorption in the total tail gas absorption tower.

Description of drawings

Fig. 1 is the system schematic diagram of the utility model.

Figure 2 is a schematic structural view of the tail gas absorption tower.

Implementation

Below in conjunction with accompanying drawing, the specific embodiment of the present utility model is described in further detail:

As shown in Figure 1, the hydrochloric acid recovery system in the phosphorous acid production tail gas consists of a primary condenser 1, a hydrochloric acid receiving tank 2, a secondary condenser 3, a hydrochloric acid finished product tank 4, a tertiary condenser 5, an intermediate acid receiving tank 6, The tail gas absorption tower 7, the water seal tank 8 and related pipelines and pumps are composed. The three condensers are sequentially connected in series, and the three condensers respectively pass through circulating cooling water for cooling the incoming gas.

The high-temperature gas containing hydrogen chloride, water vapor and a small amount of other substances at the top of the hydrolysis tower enters the primary condenser 1 and is partially liquefied in the primary condenser 1. The liquefied hydrochloric acid enters from the outlet at the bottom of the primary condenser 1 through a pipeline. Collected in the hydrochloric acid receiving tank 2, the uncondensed gas in the primary condenser 1 enters the secondary condenser 3 from its bottom side through the pipeline to continue to condense, and the hydrochloric acid condensed in the secondary condenser 3 is discharged from its bottom Enter the hydrochloric acid finished product tank 4 through the pipeline; the unliquefied gas in the secondary condenser 3 enters the tertiary condenser 5 through the pipeline from the side of the bottom to condense, and the condensed hydrochloric acid enters the intermediate acid receiving tank 6 through the pipeline and collects; After the three-stage condensation, there is still a small amount of gas containing hydrochloric acid and high-boiling acid, which is sent from the bottom side of the three-stage condenser 5 to the tail gas absorption tower 7 through pipelines, and enters from the middle of the tail gas absorption tower 7.

The bottom of the tail gas absorption tower 7 is a hydrochloric acid receiving tank 71, pure water passes through the hydrochloric acid receiving tank 71, a packing 72 is installed in the middle, and a liquid separator 73 is arranged on the top, and the tail gas enters the tail gas absorbing tower from the air inlet 76 below the packing 72 within 7. A circulation pump 74 is installed outside the tail gas absorption tower, and the liquid in the hydrochloric acid receiving tank 71 is drawn out by the circulation pump 74, and the liquid distribution pipe 75 sent to its top is sprayed downward, and the hydrochloric acid gas and liquid are contacted and absorbed in the packing section 72 Absorbed and dropped into the hydrochloric acid receiving tank 71. The top of the tail gas absorption tower 7 is provided with an exhaust port 75, and a small amount of residual gas after the exhaust gas absorption treatment is discharged from the exhaust port 75 and introduced into the water seal tank 8 through a pipeline. The water seal tank 8 is a seal tank with pure water inside, the tail gas pipeline is inserted below the liquid level, and the residual gas is finally absorbed in the pure water. The gas that cannot be absorbed is guided to the tail gas absorption total tower 10 in the workshop from the pipeline at the top of the water seal tank 8 for processing.

In order to improve the liquefaction and absorption effect of the condenser, the hydrochloric acid in the water seal tank 8, the hydrochloric acid receiving tank 71 and the intermediate acid receiving tank 6 enters the three-stage condenser 5 by means of a circulation pump or overflow, absorbs the gas therein, and Return to intermediate acid receiving tank 6 at last. The excess hydrochloric acid in the intermediate acid receiving tank 6 enters the secondary condenser 3 through overflow, absorbs the gas therein, and finally enters the hydrochloric acid product tank 4 . The hydrochloric acid in the hydrochloric acid receiving tank 2 finally enters the hydrochloric acid finished product tank 4 by means of overflow.

The tops of the hydrochloric acid receiving tank 2, the intermediate acid receiving tank 6 and the hydrochloric acid product tank 4 are respectively connected to the tail gas absorption tower of the workshop through pipes and valves. After the absorption is completed, the residual gas in each storage tank is sent to the tail gas absorption tower 10 treatments.

All the pipelines of this system are equipped with valves, pressure gauges, flow meters and other components necessary for control, which are convenient for remote monitoring.

The hydrochloric acid finished product tank 4 is provided with a tank truck interface and connected with a hydrochloric acid extraction pump 9. When the liquid level in the hydrochloric acid finished product tank is high, the hydrochloric acid inside is transported to the hydrochloric acid storage tank or the hydrochloric acid metering tank through the hydrochloric acid extraction pump 9 Within, the recovery of hydrochloric acid is completed.

Claims (7)

1. Hydrochloric acid recovery system in the tail gas of phosphorous acid production, including at least one condensate receiving tank, a primary condenser and a hydrochloric acid product tank, the primary condenser is fed with circulating cooling water, and the tail gas containing hydrochloric acid in the hydrolysis tower enters the primary Condensation in the condenser, the condensed liquid hydrochloric acid enters the condenser receiving tank, and the hydrochloric acid collected by the condenser receiving tank enters the hydrochloric acid finished product tank, and it is characterized in that it also includes a secondary condenser, a tertiary condenser and a tail gas absorption tower. The unliquefied gas in the primary condenser and the hydrochloric acid product tank enters the secondary condenser through the pipeline, and the unliquefied gas in the secondary condenser and the hydrochloric acid product tank enters the third-stage condenser through the pipeline, and the third-stage condensation The bottom of the tank is connected with an intermediate acid receiving tank, and the unliquefied gas in the three-stage condenser and in the intermediate acid receiving tank enters the tail gas absorption tower through the pipeline; the bottom of the absorption tower is a hydrochloric acid receiving tank, and the top of the hydrochloric acid receiving tank is installed Packing, the inlet of the tail gas absorption tower is located between the hydrochloric acid receiving tank and the packing, the top of the tail gas absorption tower is provided with a tail gas outlet, and the tail gas outlet is connected to the tail gas absorption total tower of the workshop; the hydrochloric acid receiving tank and the intermediate acid The hydrochloric acid in the receiving tank flows back into the third condenser and the second condenser respectively. 2. the hydrochloric acid recovery system in the phosphorous acid production tail gas according to claim 1, is characterized in that, the bottom of described intermediate acid receiving tank and hydrochloric acid receiving tank is respectively connected with circulating pump, and the hydrochloric acid in intermediate acid receiving tank has circulating pump Send it to the third condenser for circulation, and the hydrochloric acid in the hydrochloric acid receiving tank is circulated by the circulating pump to circulate at the top of the tail gas absorption tower. 3. The hydrochloric acid recovery system in the phosphorous acid production tail gas according to claim 2, is characterized in that, the top in the tail gas absorption tower is equipped with a liquid pipe, and the liquid pipe is located above the filler, and the liquid pipe is connected to the corresponding output of the circulating pump. 4. The hydrochloric acid recovery system in the phosphorous acid production tail gas according to claim 1, characterized in that, one side of the tail gas absorption tower is provided with a water seal tank, the water seal tank is connected with pure water input, and the top of the tail gas absorption tower The exhaust port of the exhaust port is inserted below the liquid level of the water seal tank through the pipeline, and the top of the water seal tank is connected to the exhaust gas absorption total tower of the workshop through the pipeline. 5. The hydrochloric acid recovery system in the phosphorous acid production tail gas according to claim 4, characterized in that, the water-sealed tank is connected with a circulating pump, and the circulating pump extracts hydrochloric acid from the water-sealed tank and sends it to the third condenser . 6. the hydrochloric acid recovery system in the phosphorous acid production tail gas according to claim 1, is characterized in that, described hydrochloric acid finished product tank is provided with tanker interface, and hydrochloric acid finished product pipe is connected with hydrochloric acid extraction pump, and the output of described hydrochloric acid takes pump The ends are respectively connected to the hydrochloric acid metering tank and the hydrochloric acid storage tank through branch pipes. 7. The hydrochloric acid recovery system in the phosphorous acid production tail gas according to claim 1 is characterized in that, the hydrochloric acid receiving tank, the intermediate acid receiving tank and the top of the hydrochloric acid receiving tank are respectively connected to the tail gas absorption total tower through pipelines, and valves are installed on each pipeline .

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