High-efficiency absorption device for hydrogen chloride gas volatilized from concentrated hydrochloric acid tank

Abstract

The utility model provides a highly efficient absorption device for volatilized hydrogen chloride gas from a concentrated hydrochloric acid tank, comprising a primary heat exchange absorber, a secondary heat exchange absorber, a tail gas absorber, an intermediate tank, and an alkali washing absorption tower. The scheme provides a dilute acid pipeline for the intermediate tank, and conveys low-concentration dilute hydrochloric acid to the tail gas absorber through the dilute acid pipeline, so as to repeatedly absorb hydrogen chloride gas as an absorption liquid, thereby reducing the amount of absorption water added from the outside, alleviating the difficulty of rapid increase of the liquid level in the intermediate tank, and reducing the amount of water added, thereby accelerating the rapid enrichment and improvement of the acid solution concentration obtained by absorbing hydrogen chloride; at the same time, the problem that the low-concentration dilute hydrochloric acid in the intermediate tank is directly discharged into the concentrated hydrochloric acid tank, resulting in the concentration in the concentrated hydrochloric acid tank being lowered, and affecting the raw material index of the subsequent analytical process is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of hydrochloric acid decomposition hydrogen chloride gas treatment, in particular to a high-efficiency absorption device for hydrogen chloride gas volatilized from a concentrated hydrochloric acid tank. Background Art

[0002] The raw material used in hydrochloric acid analysis is concentrated hydrochloric acid with a concentration of 31%. Concentrated hydrochloric acid tanks are usually used to store this concentrated hydrochloric acid. Existing concentrated hydrochloric acid tanks easily volatilize hydrogen chloride gas, which is directly discharged, causing environmental pollution and also resulting in the waste of this part of hydrogen chloride. There is also a technology that absorbs the volatilized hydrogen chloride gas by configuring a spray absorption method to obtain dilute hydrochloric acid. However, the absorption process requires continuous replenishment of absorption water, resulting in an increasing amount of dilute hydrochloric acid solution. When the storage capacity of the intermediate tank is exceeded, the dilute hydrochloric acid can only be discharged directly into the concentrated hydrochloric acid tank, resulting in a lower concentration in the concentrated hydrochloric acid tank, affecting the raw material indicators of the subsequent analysis process. Utility Model Content

[0003] In view of the above defects, the utility model proposes a high-efficiency absorption device for volatilized hydrogen chloride gas from a concentrated hydrochloric acid tank, comprising a primary heat exchange absorber, a secondary heat exchange absorber, a tail gas absorber, an intermediate tank, and an alkali washing absorption tower, wherein the gas phase inlet of the primary heat exchange absorber is connected to the gas phase balance port of the concentrated hydrochloric acid tank, the gas phase outlet of the primary heat exchange absorber is connected to the gas phase inlet of the secondary heat exchange absorber, the gas phase outlet of the secondary heat exchange absorber is connected to the gas phase inlet of the tail gas absorber, the gas phase outlet of the tail gas absorber is connected to the alkali washing absorption tower, the liquid phase inlet of the alkali washing absorption tower is used to introduce leaching alkali solution, and the liquid phase outlet of the alkali washing absorption tower is used to discharge waste alkali solution; the tail gas absorption tower is used to absorb the alkali solution. The liquid phase outlet of the receiver is connected to the liquid phase inlet of the secondary absorption tower, the liquid phase outlet of the secondary heat exchange absorber is connected to the liquid phase inlet of the primary heat exchange absorber, the liquid phase outlet of the primary heat exchange absorber is connected to the liquid phase inlet of the intermediate tank, the tail gas absorber is also provided with a liquid phase inlet to be connected to the external absorption water, the intermediate tank is also provided with a liquid phase outlet, and an intermediate liquid phase pipeline connected to the liquid phase outlet, the intermediate liquid phase pipeline is connected to the concentrated hydrochloric acid tank to transport the concentrated hydrochloric acid with the required concentration to the concentrated hydrochloric acid tank for storage, the intermediate tank is also provided with a dilute acid pipeline to be connected to the liquid phase inlet of the tail gas absorber to transport the low-concentration dilute hydrochloric acid in the intermediate tank to the tail gas absorber.

[0004] This solution sets a dilute acid pipeline for the intermediate tank, through which low-concentration dilute hydrochloric acid is transported to the tail gas absorber, where it is used as an absorption liquid to repeatedly absorb hydrogen chloride gas. This not only reduces the amount of external absorption water used, alleviating the difficulty of rapidly rising the liquid level in the intermediate tank, but also reduces the amount of water used, which accelerates the rapid enrichment and increase of the acid concentration obtained by absorbing hydrogen chloride. At the same time, it solves the problem of low-concentration dilute hydrochloric acid in the intermediate tank being directly discharged into the concentrated hydrochloric acid tank, resulting in a lower concentration in the concentrated hydrochloric acid tank and affecting the raw material indicators of the subsequent analytical process. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 This is a structural diagram of this scheme.

[0006] In the figure: primary heat exchange absorber 10, gas phase inlet 11, liquid phase outlet 12, desalted water inlet 13, desalted water outlet 14, secondary heat exchange absorber 20, gas phase inlet 21, liquid phase outlet 22, tail gas absorber 30, gas phase inlet 31, liquid phase outlet 32, liquid phase inlet 33, intermediate tank 40, dilute acid pipeline 41, liquid phase outlet 42, intermediate liquid phase pipeline 43, gas phase outlet 44, intermediate gas phase pipeline 45, alkali wash absorption tower 50, liquid phase inlet 51, liquid phase outlet 52, vent 53, concentrated hydrochloric acid tank 60, gas phase balance port 61. DETAILED DESCRIPTION

[0007] See also Figure 1 The present invention proposes a highly efficient absorption device for volatilized hydrogen chloride gas from a concentrated hydrochloric acid tank, comprising a primary heat exchange absorber 10, a secondary heat exchange absorber 20, a tail gas absorber 30, an intermediate tank 40, and an alkali washing absorption tower 50. The gas phase inlet of the primary heat exchange absorber 10 is connected to the gas phase equilibrium port 61 of the concentrated hydrochloric acid tank 60, the gas phase outlet 11 of the primary heat exchange absorber 10 is connected to the gas phase inlet 21 of the secondary heat exchange absorber 20, the gas phase outlet of the secondary heat exchange absorber 20 is connected to the gas phase inlet 31 of the tail gas absorber 30, the gas phase outlet of the tail gas absorber 30 is connected to the alkali washing absorption tower 50, the liquid phase inlet 51 of the alkali washing absorption tower 50 is used to introduce leaching alkali solution, and the liquid phase outlet 52 of the alkali washing absorption tower 50 is used to discharge waste alkali solution; the tail gas absorber 30 is provided with a liquid The phase inlet 33 is connected to the external absorption water, the liquid phase outlet 32 ​​of the tail gas absorber 30 is connected to the liquid phase inlet of the secondary heat exchange absorber 20, the liquid phase outlet 22 of the secondary heat exchange absorber 20 is connected to the liquid phase inlet of the primary heat exchange absorber 10, and the liquid phase outlet 12 of the primary heat exchange absorber 10 is connected to the liquid phase inlet of the intermediate tank 40. The intermediate tank 40 is also provided with a liquid phase outlet 42 and an intermediate liquid phase pipeline 43 connected to the liquid phase outlet 42. The intermediate liquid phase pipeline 43 is connected to the concentrated hydrochloric acid tank 60 to transport concentrated hydrochloric acid with the required concentration to the concentrated hydrochloric acid tank 60 for storage. The intermediate tank 40 is also provided with a dilute acid pipeline 41 to be connected to the liquid phase inlet 33 of the tail gas absorber 30 to transport the low-concentration dilute hydrochloric acid in the intermediate tank 40 to the tail gas absorber 30.

[0008] This solution adopts a three-stage absorption and progressive absorption method to complete the gradual absorption of hydrogen chloride gas, while solving the problem of severe heat release during the first and second stage absorption. In this system, the hydrogen chloride gas volatilized from the concentrated hydrochloric acid tank 60 enters the system via the primary heat exchange absorption process. Therefore, the concentration of the hydrogen chloride gas is the highest during the primary absorption process, and the hydrochloric acid solution obtained after absorption is directly stored in the intermediate tank 40. Next, the hydrogen chloride gas not absorbed by the primary absorber enters the secondary heat exchange absorber 20 for absorption. The concentration of the acid solution after absorption in the secondary heat exchange absorber 20 is much lower than that in the primary absorber. Therefore, the acid solution after absorption in the secondary heat exchange absorber 20 is fed to the primary absorber as an absorption medium to absorb the hydrogen chloride gas. Similarly, the amount of gas remaining after absorption in the secondary heat exchange absorber 20 is further reduced and passed to the tail gas absorber 30 for absorption, forming an acid solution with an even lower concentration. This acid solution then enters the secondary heat exchange absorber 20 as an absorption medium to absorb the hydrogen chloride gas. As a result, the concentration of the absorption solution gradually decreases from the tail gas absorber 30, the secondary heat exchange absorber 20, and the primary absorber, and is progressively used by the next stage absorber to absorb the hydrogen chloride gas.

[0009] This solution is also the most energy-efficient design. The on-site layout of the primary absorber, secondary absorber, and tail gas absorber is the same as shown in the attached figure, that is, the primary absorber is the lowest, the secondary absorber is in the middle, and the tail gas absorber is the highest. According to the principle of natural gas rise, the gas is gradually absorbed from the primary absorber, secondary absorber, and tail gas absorber in sequence. The rise of hydrogen chloride gas does not require external power. Similarly, the absorbed absorption liquid flows from the tail gas absorber, secondary absorber, and primary absorber in sequence, that is, it gradually flows downward from the highest absorber to the lower absorber. The liquid flow can also be achieved by its own gravity, without the need for external power, such as the need for an external power pump for transportation. Therefore, this design has a reasonable structure, the best energy-saving effect, and an excellent absorption effect.

[0010] For example, the concentration of the acid liquid after being absorbed by the tail gas absorber 30 is 3%, the concentration of the acid liquid after entering the secondary heat exchange absorber 20 for absorption again is 5%, and the concentration of the acid liquid after entering the primary absorber for absorption is 10%. The 10% dilute hydrochloric acid enters the intermediate tank 40 for temporary storage, but the liquid phase inlet 33 of the tail gas absorber 30 is continuously replenished with absorption water, and continuously enters the intermediate tank 40 after circulation, resulting in more and more acid liquid in the intermediate tank 40. In the original design, only 10% of the dilute hydrochloric acid in the intermediate tank 40 can be pumped into the concentrated hydrochloric acid tank 60, which eventually leads to the concentration of the concentrated hydrochloric acid tank 60. The concentrated hydrochloric acid tank 60 is used as the raw material for hydrochloric acid analysis in the next process. The raw material requires an acid concentration of not less than 31%. Otherwise, the analytical raw material does not meet the process requirements and will cause large fluctuations in the overall balance of the system. Therefore, in this solution, 10% of the acid in the intermediate tank 40 is transported to the tail gas absorber 30 through the dilute acid pipeline to serve as the absorption liquid to repeatedly absorb the hydrogen chloride gas. This not only reduces the amount of external absorption water, alleviates the difficulty of rapidly rising the liquid level in the intermediate tank 40, but also reduces the amount of water used, which accelerates the rapid enrichment and improvement of the acid concentration obtained by absorbing hydrogen chloride. After the above-mentioned one-cycle absorption, the concentration of the acid liquid entering the intermediate tank 40 is 10%. The acid liquid in the intermediate tank 40 is again pumped into the exhaust gas absorber 30. After another exhaust gas absorption, the concentration may be increased to 11%, the secondary absorption concentration may be increased to 13%, and the primary absorption concentration may be increased to 16%. After multiple cycles, the concentration of the acid liquid entering the intermediate tank 40 continues to increase and quickly reaches 31%. At this time, the acid liquid in the intermediate tank 40 is pumped into the concentrated hydrochloric acid tank 60, so as not to affect the concentration of the acid liquid in the concentrated hydrochloric acid tank 60.

[0011] Furthermore, both the primary heat exchange absorber 10 and the secondary heat exchange absorber 20 are falling film absorbers.

[0012] Furthermore, the falling film absorber is provided with a desalted water inlet 13 and a desalted water outlet 14. The desalted water inlet 13 and the desalted water outlet 14 are used for introducing and discharging desalted water, respectively. The design of the falling film absorber differs from that of a spray tower in that the heat in the tower is quickly removed through tube-to-tube heat exchange without affecting the structure of the contact absorption of hydrogen chloride gas and the absorption liquid. Since the absorption of hydrogen chloride gas by water is an exothermic reaction, if the spray absorption method in the original design is adopted, although the hydrogen chloride gas can be quickly absorbed, the exothermic reaction will cause the temperature in the tower to rise seriously. Secondly, the high temperature will cause the hydrogen chloride gas in the dissolved dilute hydrochloric acid to dissolve. The hydrogen chloride gas is evaporated, resulting in a decrease in absorption capacity. Therefore, this solution adopts a falling film heat exchange method. When the hydrogen chloride gas is absorbed by the water, the heat released is absorbed by the circulating water in the tubes for heat exchange and then discharged in time to prevent the absorbed hydrogen chloride from being evaporated again. Through testing, the inlet water temperature of the desalted water inlet 13 of the first-stage falling film absorber and the second-stage falling film absorber is about 33°C, and the desalted water outlet 14 is about 43°C. The heat exchange effect is significant. The temperature of the dilute hydrochloric acid after absorbing the hydrogen chloride gas does not rise, and it is discharged into the intermediate tank 40.

[0013] For the tail gas absorber, the amount of hydrogen chloride gas at this time is very small, so spray absorption is directly used to treat the tail gas, and the absorption heat release is negligible. However, since the amount of hydrogen chloride gas is larger than that of the tail gas in the third stage, spray absorption is not suitable for the first and second stage absorption, and falling film absorption is required.

[0014] Furthermore, the alkaline washing absorption tower 50 is provided with a vent 53 for discharging unabsorbed hydrogen chloride gas. The amount of this hydrogen chloride gas is very small, with a content of less than 1% according to testing.

[0015] Furthermore, intermediate tank 40 is provided with a gas phase outlet 44 and an intermediate gas phase pipeline 45 connected to gas phase outlet 44. Intermediate gas phase pipeline 45 is connected to gas phase inlet 21 of secondary heat exchange absorber 20. Intermediate tank 40 contains a dilute hydrochloric acid solution that absorbs the hydrogen chloride gas. To maintain pressure balance inside and outside the tank and prevent potential volatilization of some hydrogen chloride gas, this pipeline is introduced to deliver any potentially volatilized hydrogen chloride gas into the system for repeated absorption and reuse, eliminating the need for separate disposal of this gas.

[0016] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of this patent.

Claims

1. A highly efficient absorption device for hydrogen chloride gas volatilized from a concentrated hydrochloric acid tank, characterized in that: The invention comprises a primary heat exchange absorber, a secondary heat exchange absorber, a tail gas absorber, an intermediate tank, and an alkali washing absorber, wherein the gas phase inlet of the primary heat exchange absorber is connected to the gas phase balance port of the concentrated hydrochloric acid tank, the gas phase outlet of the primary heat exchange absorber is connected to the gas phase inlet of the secondary heat exchange absorber, the gas phase outlet of the secondary heat exchange absorber is connected to the gas phase inlet of the tail gas absorber, the gas phase outlet of the tail gas absorber is connected to the alkali washing absorber, the liquid phase inlet of the alkali washing absorber is used to introduce leaching alkali solution, and the liquid phase outlet of the alkali washing absorber is used to discharge the waste alkali solution; the liquid phase outlet of the tail gas absorber is connected to the liquid phase inlet of the secondary absorption tower. The liquid phase outlet of the secondary heat exchange absorber is connected to the liquid phase inlet of the primary heat exchange absorber, and the liquid phase outlet of the primary heat exchange absorber is connected to the liquid phase inlet of the intermediate tank. The tail gas absorber is also provided with a liquid phase inlet to be connected with external absorption water. The intermediate tank is also provided with a liquid phase outlet and an intermediate liquid phase pipeline connected with the liquid phase outlet. The intermediate liquid phase pipeline is connected with the concentrated hydrochloric acid tank to transport the concentrated hydrochloric acid reaching the required concentration to the concentrated hydrochloric acid tank for storage. The intermediate tank is also provided with a dilute acid pipeline to be connected with the liquid phase inlet of the tail gas absorber to transport the low-concentration dilute hydrochloric acid in the intermediate tank to the tail gas absorber.

2. The highly efficient absorption device for volatilized hydrogen chloride gas from a concentrated hydrochloric acid tank as claimed in claim 1, characterized in that: The primary heat exchange absorber and the secondary heat exchange absorber are both falling film absorbers.

3. The highly efficient absorption device for volatilized hydrogen chloride gas from a concentrated hydrochloric acid tank as claimed in claim 2, characterized in that: The falling film absorber is provided with a desalted water inlet and a desalted water outlet.

4. The highly efficient absorption device for volatilized hydrogen chloride gas from a concentrated hydrochloric acid tank as claimed in claim 1, characterized in that: The alkali washing absorption tower is also provided with a vent.

5. The highly efficient absorption device for hydrogen chloride gas volatilized from a concentrated hydrochloric acid tank as claimed in claim 1, characterized in that: The intermediate tank is also provided with a gas phase outlet and an intermediate gas phase pipeline connected to the gas phase outlet, and the intermediate gas phase pipeline is connected to the gas phase inlet of the secondary heat exchange absorber.

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