Hydrogen chloride gas absorption device-modified double-path pure water absorption system and process method

Abstract

The invention discloses a hydrogen chloride gas absorption device-modified double-path pure water absorption system and a process method, and relates to the technical field of chemical waste gas treatment and resource recovery. The device comprises a hydrochloric acid synthesis furnace, a first-stage falling film absorber, a second-stage falling film absorber, a combined tail gas absorption tower and a tail gas purification unit which are sequentially connected, as well as a pure water supply system and an automatic control system. The system is characterized in that the pure water supply system is divided into two independent branches through a water inlet header pipe to be connected to the combined tail gas absorption tower, and each branch is provided with an automatic regulating valve. According to the method, a traditional single-path water absorption system is transformed into a double-path standby system through low-cost technical improvement of an existing single-path absorption device, automatic and rapid switching to the other path when one path breaks down is achieved, and therefore the problems that in the prior art, production is discontinuous, product concentration fluctuation is large, and potential safety hazards exist are effectively solved; the effects of efficiently, continuously and safely producing high-concentration hydrochloric acid and realizing near-zero emission of tail gas are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste gas treatment and resource recycling in chemical production, in particular to an improvement of hydrogen chloride gas absorption process and device. Specifically, the present application provides a device and method for transforming a traditional single-path pure water absorption device into a double-path pure water absorption system, which is used to realize efficient, continuous and safe absorption of hydrogen chloride gas, and to stabilize the production of high-concentration hydrochloric acid. BACKGROUND

[0002] In the production process of fine chemicals such as pesticides, pharmaceuticals, dyes and electronic chemicals, the generation of by-product hydrogen chloride gas is often accompanied. How to efficiently and safely absorb and treat such acidic gas and convert it into a commercially valuable hydrochloric acid product is a key link to realize resource recycling and clean production. At present, the traditional hydrogen chloride absorption process widely used in the industry is to use single-path pure water as the absorbent and to process it through a system composed of a falling film absorber and a tail gas absorption tower.

[0003] The traditional single-path pure water absorption device is usually composed of a hydrochloric acid synthesis furnace, a falling film absorber, a tail gas absorption tower and an alkali washing tower. Although this process is widely used, it has some inherent defects in long-term operation. First of all, its biggest limitation is poor production continuity. Since the entire absorption process relies on a single water path, when the only pipeline or its key components such as valves and pumps fail, the upstream hydrochloric acid synthesis furnace must be stopped urgently, resulting in interruption of the entire production process and seriously affecting the stable operation of upstream and downstream devices, which brings great challenges to continuous production. Secondly, in the single-path water absorption system, the control accuracy of the absorption water volume is limited, and it is difficult to achieve highly stable regulation, which directly leads to a wide fluctuation range of the concentration of finished hydrochloric acid, poor consistency of product quality, and difficulty in meeting the market demand for high-concentration and high-stability hydrochloric acid, affecting the commodity value of the product. In addition, the single pipeline system has significant safety hazards. Once the absorption water supply is interrupted or the pipeline is broken, it is easy to cause incomplete absorption or even leakage of hydrogen chloride gas, which not only corrodes the equipment, but also seriously threatens the health and safety of the operators. In the prior art, a double-tower series process has been proposed to improve the absorption efficiency, but these improvement schemes mainly focus on improving the tail gas purification effect, and have limited effect on the production continuity and quality stability of the main product hydrochloric acid. At the same time, such schemes often mean that a complete set of absorption equipment needs to be added, resulting in large equipment investment, complex process flow, increased land occupation, especially not conducive to the upgrading and modification of existing devices, and poor economic benefits. Therefore, the present application provides a double-path pure water absorption system and process method for hydrogen chloride gas absorption device to solve the above technical problems. SUMMARY

[0004] The hydrogen chloride gas absorption device improved double-path pure water absorption system and process method aims at solving the problems of discontinuous production, large product concentration fluctuation and safety hidden trouble in the prior art by low-cost technical transformation of the existing single-path absorption device to transform the traditional single-path absorption water system into a double-path standby system, realizing automatic and rapid switching to the other path when one path fails, and achieving the effects of efficient, continuous and safe production of high-concentration hydrochloric acid and near-zero emission of tail gas.

[0005] The hydrogen chloride gas absorption device improved double-path pure water absorption system provided by the first aspect of the application comprises a hydrochloric acid synthesis furnace, a first falling film absorber, a second falling film absorber, a combined tail gas absorption tower, a pure water supply system, an automatic control system, a tail gas purification unit and a hydrochloric acid storage tank.

[0006] The first falling film absorber and the second falling film absorber are connected in series, and the gas phase outlet of the second falling film absorber is connected to the combined tail gas absorption tower.

[0007] The pure water supply system is divided into two branches through a water inlet main pipe and is connected to a first water supplement pipe opening and a second water supplement pipe opening of the combined tail gas absorption tower, respectively, and an automatic regulating valve is arranged on each branch.

[0008] The automatic control system is electrically connected to a liquid level meter arranged on the hydrochloric acid storage tank and the automatic regulating valve, is used for monitoring the hydrochloric acid concentration and temperature in real time, and controls the automatic switching and water supplement process of the two absorption circuits.

[0009] Preferably, the falling film absorbers are graphite falling film absorbers, and a pure water distributor is arranged at the top of each falling film absorber.

[0010] Preferably, the hydrochloric acid storage tank is made of glass fiber reinforced plastic.

[0011] Preferably, the tail gas purification unit is an alkali neutralization tower, and the automatic control system is further connected to an automatic discharge valve for controlling the discharge of the hydrochloric acid storage tank.

[0012] The second aspect of the application provides a hydrogen chloride gas absorption device improved double-path pure water absorption process method, which comprises the following steps.

[0013] S1, hydrogen chloride gas enters the first falling film absorber from a gas inlet main pipe, is countercurrently contacted with circulating absorption liquid sprayed from the combined tail gas absorption tower and is absorbed to form hydrochloric acid, the tail gas after absorption enters the second falling film absorber, the combined tail gas absorption tower and the tail gas purification unit in sequence, and is finally discharged up to the standard; meanwhile, pure water is quantitatively supplemented by the automatic regulating valve according to the hydrochloric acid concentration through the pure water supply system, so as to maintain the stability of the absorption water amount.

[0014] S2, the automation control system detects the concentration and temperature of hydrochloric acid in the hydrochloric acid tank in real time, and when the concentration of hydrochloric acid reaches 31.5±0.3% and the temperature drops to the safety range, it is determined that the hydrochloric acid is qualified;

[0015] S3, when the fluctuation of the concentration of hydrochloric acid exceeds the qualified range or the single absorption water pipeline fails, the automation control system immediately starts the automatic adjusting valve of the standby absorption pure water pipeline to realize double switching and ensure continuous production.

[0016] Preferably, the circulating absorption liquid in step S1 is initially pure water.

[0017] Preferably, the method is suitable for the modification of the existing single hydrogen chloride absorption device, and the double pure water absorption is realized by adding a second absorption water pipeline and an automation control system.

[0018] In summary, the present application has the following beneficial effects:

[0019] 1. The present application designs a double pure water absorption circuit to build a main and standby complementary absorption system, completely avoiding the defect that the traditional single absorption device must be shut down for maintenance due to pipeline or component failure. Relying on the rapid switching function of the automation control system, the absorption circuit can be seamlessly connected when a fault occurs, ensuring the continuous and uninterrupted process of hydrochloric acid synthesis and absorption, effectively maintaining the stable operation of the upstream and downstream devices, and meeting the core needs of continuous chemical production.

[0020] 2. With the help of the automation control system for precise control of the amount of absorption water, combined with the stable operation characteristics of the double absorption circuit, the hydrogen chloride gas absorption reaction can always be in the optimal working condition. Compared with the traditional single system, the present application can greatly reduce the concentration fluctuation of the finished hydrochloric acid, improve the product quality uniformity, and the produced high-concentration hydrochloric acid can stably meet the quality requirements of the market and subsequent production, significantly enhancing the commercial value of the product.

[0021] 3. The whole absorption and water replenishment process is completed by the automation control system in a closed environment, minimizing human intervention and reducing the safety risks caused by human operation errors. At the same time, the double standby design avoids the leakage of hydrogen chloride gas caused by the failure of the single system, reduces the damage of corrosive gas to equipment and the threat to the health of operators, and improves the safety and controllability of the production process.

[0022] 4. The synergistic effect of the two-stage falling film absorber and the combined tail gas absorption tower, combined with the design of double stable water replenishment, ensures that the hydrogen chloride gas absorption efficiency always maintains a high level, greatly reduces the hydrogen chloride content in the tail gas, and reduces the processing pressure of the end tail gas purification unit. Combined with the deep treatment of the tail gas purification unit, near-zero emission of tail gas is realized, which not only improves the resource recycling rate, but also meets the environmental protection requirements of clean production.

[0023] 5. This invention is specifically designed for upgrading existing single-path hydrogen chloride absorption devices. It eliminates the need for complete reconstruction; only an additional absorption water pipeline and supporting automation components are required to complete the upgrade. The upgrade process is low-cost and short-cycle, achieving a significant performance improvement with minimal investment. Compared to complex improvement schemes such as existing dual-tower series connections, this invention better meets the actual production needs of enterprises, demonstrating significant economic benefits and practicality. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the experimental materials used, unless otherwise specified, were all purchased from conventional biochemical reagent stores. All quantitative experiments in the following examples were performed in triplicate, and the data are the average of the three replicates or the average ± standard deviation.

[0028] Example 1

[0029] This embodiment provides a specific implementation of a modified hydrogen chloride gas absorption device into a dual-path pure water absorption system. The device includes a hydrochloric acid synthesis furnace, a primary graphite falling film absorber, a secondary graphite falling film absorber, a combined tail gas absorption tower, a pure water supply system, an automatic control system, an alkali neutralization tower as a tail gas purification unit, and a hydrochloric acid storage tank made of fiberglass.

[0030] The primary and secondary falling film absorbers are connected in series. The gas phase outlet of the primary falling film absorber is connected to the gas phase inlet of the secondary falling film absorber, and the gas phase outlet of the secondary falling film absorber is connected to the bottom inlet of the combined tail gas absorption tower. The exhaust port at the top of the combined tail gas absorption tower is connected to the alkali neutralization tower.

[0031] The pure water supply system is divided into a main inlet pipe and a second branch in parallel, which are connected to the first and second water supply ports at the top of the combined tail gas absorption tower, respectively. Each branch is equipped with an automatic regulating valve.

[0032] The automated control system uses a PLC, which is electrically connected to the level gauge, temperature sensor, and online hydrochloric acid concentration detector installed on the hydrochloric acid storage tank to collect real-time data on the hydrochloric acid level, temperature, and concentration. Simultaneously, the automated control system is also electrically connected to the automatic regulating valve on the pure water pipeline and the automatic discharge valve at the outlet of the hydrochloric acid storage tank, executing automatic switching between the two absorption loops, water replenishment control, and automatic discharge of qualified hydrochloric acid according to a preset program.

[0033] The specific steps for modifying a hydrogen chloride gas absorption device into a dual-path pure water absorption process using the system of this embodiment are as follows:

[0034] S1. Start the hydrochloric acid synthesis furnace. The generated hydrogen chloride gas enters the primary falling film absorber. At the same time, the pure water supply system supplies pure water to the combined tail gas absorption tower through the first branch (as the main line). The sprayed pure water comes into countercurrent contact with the rising hydrogen chloride gas in the tower to form a dilute hydrochloric acid absorbent. This absorbent flows through the secondary falling film absorber and the primary falling film absorber in sequence, where it undergoes further mass transfer absorption with the hydrogen chloride gas. The final hydrochloric acid is collected in the hydrochloric acid storage tank. The tail gas that is not completely absorbed passes through the secondary falling film absorber, the combined tail gas absorption tower, and the alkali neutralization tower in sequence for deep purification, ultimately ensuring that it meets the emission standards. During this process, the automatic control system, based on the feedback of the hydrochloric acid concentration in the hydrochloric acid storage tank, precisely controls the water replenishment by adjusting the opening of the automatic regulating valve on the first branch to maintain the system's water balance.

[0035] S2. The automated control system continuously monitors the concentration and temperature of hydrochloric acid in the hydrochloric acid storage tank in real time. When the hydrochloric acid concentration reaches 31.5±0.3% (wt%) and the temperature drops to a safe range below 40℃, the system determines that the hydrochloric acid at the outlet of the first-stage falling film absorber is a qualified product and can control the automatic discharge valve to discharge the product.

[0036] S3. During operation, if the automated control system detects that the hydrochloric acid concentration fluctuation continuously exceeds the acceptable range of ±0.5%, or detects signals such as a fault in the automatic regulating valve of the first branch (main line) or abnormal pipeline pressure, the system will immediately close the automatic regulating valve of the first branch within a few seconds, and at the same time fully open the automatic regulating valve of the second branch (backup line), seamlessly switching the absorption water source to the backup pipeline. This switching process does not require stopping the synthesis furnace, ensuring continuous and uninterrupted production.

[0037] The upgraded dual-path system has achieved more than 8,000 hours of continuous and stable operation, completely solving the problem of unplanned shutdowns caused by water circuit failures in the traditional single-path system. The fault switching time is less than 3 seconds, ensuring the stable operation of upstream and downstream units, stable hydrochloric acid concentration in the product, and consistently compliant exhaust emissions.

[0038] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A modified hydrogen chloride gas absorption device, consisting of a dual-path pure water absorption system, characterized in that... It includes a hydrochloric acid synthesis furnace, a primary falling film absorber, a secondary falling film absorber, a combined tail gas absorption tower, a pure water supply system, an automated control system, a tail gas purification unit, and a hydrochloric acid storage tank. The primary falling film absorber and the secondary falling film absorber are connected in series, and the gas phase outlet of the secondary falling film absorber is connected to the combined tail gas absorption tower. The pure water supply system is divided into two branches through the main water inlet pipe, which are respectively connected to the first water supply port and the second water supply port of the combined tail gas absorption tower. Each branch is equipped with an automatic regulating valve. The automated control system is electrically connected to the level gauge and automatic regulating valve installed on the hydrochloric acid storage tank, and is used to monitor the hydrochloric acid concentration and temperature in real time, and control the automatic switching and water replenishment process of the two absorption circuits.

2. The hydrogen chloride gas absorption device modified into a dual-path pure water absorption system according to claim 1, characterized in that, All falling film absorbers are graphite falling film absorbers, and each is equipped with a pure water distributor at the top.

3. The hydrogen chloride gas absorption device modified into a dual-path pure water absorption system according to claim 1, characterized in that, The hydrochloric acid storage tank is made of fiberglass.

4. The hydrogen chloride gas absorption device modified into a dual-path pure water absorption system according to claim 1, characterized in that, The exhaust gas purification unit is an alkali neutralization tower, and the automated control system is also connected to an automatic discharge valve to control the discharge of hydrochloric acid from the storage tank.

5. A method for modifying a hydrogen chloride gas absorption device using the system described in any one of claims 1-4 into a dual-path pure water absorption process, characterized in that, Includes the following steps: S1. Hydrogen chloride gas enters the first-stage falling film absorber from the main inlet pipe, where it comes into countercurrent contact with the circulating absorbent sprayed from the combined tail gas absorber tower and is absorbed to form hydrochloric acid. The absorbed tail gas then enters the second-stage falling film absorber, the combined tail gas absorber tower, and the tail gas purification unit in sequence, and is finally discharged in compliance with standards. At the same time, pure water is supplied quantitatively through the pure water supply system according to the hydrochloric acid concentration, controlled by an automatic regulating valve to maintain a stable absorption water volume. S2. The automated control system monitors the concentration and temperature of hydrochloric acid in the hydrochloric acid storage tank in real time. When the hydrochloric acid concentration reaches 31.5±0.3% and the temperature drops to a safe range, the hydrochloric acid is deemed to be qualified. S3. When the hydrochloric acid concentration fluctuation exceeds the qualified range or a single absorption water pipeline fails, the automatic control system immediately activates the automatic regulating valve of the backup absorption pure water pipeline to achieve dual-path switching and ensure continuous and uninterrupted production.

6. The method for modifying the hydrogen chloride gas absorption device into a dual-path pure water absorption process according to claim 5, characterized in that, In step S1, the initial circulating absorption liquid is pure water.

7. The method for modifying the hydrogen chloride gas absorption device into a dual-path pure water absorption process according to claim 5, characterized in that, The method is applicable to the modification of existing single-path hydrogen chloride absorption devices, and achieves dual-path pure water absorption by adding a second absorption water pipeline and an automated control system.

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