Automatic control device for hydrochloric acid furnace APC

Abstract

The utility model relates to the technical field of chemical production, provide a kind of hydrochloric acid furnace APC automatic control device, solve the problem of tail chlorine alarm caused by the inaccuracy control of chlorine and hydrogen ratio due to the complex source of chlorine, component fluctuation. The utility model includes hydrochloric acid synthesis furnace, chlorine buffer tank, hydrogen supply pipeline, primary falling film absorber and controller, the outlet of chlorine buffer tank is connected with the chlorine inlet of hydrochloric acid synthesis furnace by chlorine supply pipeline, chlorine flow control valve and chlorine on-line analyzer are sequentially arranged on the chlorine supply pipeline along the chlorine flow direction;The gas inlet of primary falling film absorber is connected with the gas outlet of hydrochloric acid synthesis furnace, and a hydrochloric acid concentration analyzer is arranged on the hydrochloric acid outlet pipeline of primary falling film absorber;The utility model can sense the change of chlorine purity and hydrochloric acid concentration in real time, and automatically adjust material flow, fundamentally avoid the "over-chlorination" phenomenon caused by ratio disorder.

Description

Technical Field

[0001] This utility model relates to the field of chemical production technology, specifically to an APC automatic control device for a hydrochloric acid furnace. Background Technology

[0002] The hydrochloric acid synthesis furnace is the equipment used to produce hydrochloric acid. The production process involves chlorine and hydrogen entering the hydrochloric acid furnace through proportional control and automatic flow control. The combustion produces HCl gas, which is then absorbed by deionized water in a first-stage falling film absorber and a second-stage falling film absorber. The resulting hydrochloric acid is then sent to the tank area for sale. The unabsorbed HCl tail gas is absorbed by deionized water in the tail gas absorption tower and then discharged into the atmosphere. The heat generated from combustion heats the deionized water to produce low-pressure steam, which is then sent to the pipeline network.

[0003] Currently, the chlorine required for production comes from two sources: one is raw chlorine gas with high purity (≥95%), and the other is liquefied tail gas with low purity (≥75%, approximately 12-16% oxygen). When adjusting the load, the proportion of raw chlorine and liquefied tail gas in the chlorine gas is unknown, and the liquefied tail chlorine contains oxygen, which also consumes some hydrogen. It is impossible to accurately control the ratio, which often leads to tail-end chlorine alarms (i.e., excess chlorine discharged into the atmosphere causes GDS chlorine alarms) during load adjustment. Summary of the Invention

[0004] Therefore, in order to address the above problems, this utility model provides an APC automatic control device for a hydrochloric acid furnace, which solves the problem of tail-end chlorine alarm caused by the inability to accurately control the ratio of chlorine to hydrogen due to the complex source and composition fluctuation of chlorine.

[0005] To achieve the above objectives, this utility model is implemented through the following technical solution: An APC automatic control device for a hydrochloric acid furnace includes a hydrochloric acid synthesis furnace, a chlorine buffer tank, a hydrogen supply pipeline, a primary falling film absorber, and a controller. The outlet of the chlorine buffer tank is connected to the chlorine inlet of the hydrochloric acid synthesis furnace through the chlorine supply pipeline. A chlorine flow control valve and an online chlorine analyzer are sequentially arranged along the chlorine flow direction on the chlorine supply pipeline. A hydrogen flow control valve is installed on the hydrogen supply pipeline, and the hydrogen supply pipeline is connected to the hydrogen inlet of the hydrochloric acid synthesis furnace. The absorption water inlet of the first-stage falling film absorber is connected to an absorption water supply pipeline, and an absorption water flow control valve is installed on the absorption water supply pipeline. The gas inlet of the first-stage falling film absorber is connected to the gas outlet of the hydrochloric acid synthesis furnace, and a hydrochloric acid concentration analyzer is installed on the hydrochloric acid outlet pipeline of the first-stage falling film absorber. The controller is communicatively connected to the online chlorine analyzer and the hydrochloric acid concentration analyzer; The controller is communicatively connected to the chlorine flow control valve, the hydrogen flow control valve, and the absorption water flow control valve.

[0006] Furthermore, the hydrogen supply pipeline is also equipped with an online hydrogen analyzer for detecting hydrogen purity, and the online hydrogen analyzer is communicatively connected to the controller.

[0007] Furthermore, it also includes a flash tank connected to the hydrochloric acid synthesis furnace, the flash tank being connected to a venting pipeline, the venting pipeline being equipped with a venting valve, the chlorine supply pipeline being connected to the hydrogen supply pipeline via a nitrogen replacement pipeline, the nitrogen replacement pipeline being equipped with a nitrogen instrument valve, and the controller being communicatively connected to the venting valve and the nitrogen instrument valve.

[0008] Furthermore, a chlorine flow meter is installed on the chlorine supply pipeline, a hydrogen flow meter is installed on the hydrogen supply pipeline, and an absorption water flow meter is installed on the absorption water supply pipeline. The chlorine flow meter, hydrogen flow meter, and absorption water flow meter are all communicatively connected to the controller.

[0009] Furthermore, the online chlorine analyzer is installed on the pipeline between the outlet of the chlorine buffer tank and the chlorine flow control valve.

[0010] Furthermore, it also includes a secondary falling film absorber, wherein the gas outlet of the primary falling film absorber is connected to the gas inlet of the secondary falling film absorber.

[0011] Furthermore, the controller is a DCS (Distributed Control System).

[0012] Furthermore, the hydrochloric acid synthesis furnace is equipped with a pressure transmitter, which is communicatively connected to the controller.

[0013] Compared with the prior art, the beneficial effects of this utility model are: This invention achieves full automation of a series of operations such as shutdown, load increase / decrease, and concentration adjustment through the APC program control on the DCS, thereby improving the continuity of production and stabilizing the concentration of hydrochloric acid products. By adding an online chlorine analyzer and a hydrochloric acid concentration analyzer and connecting them together with each flow control valve to the controller, a closed-loop automatic control system is constructed.

[0014] This device can sense changes in chlorine purity and hydrochloric acid concentration in real time and automatically adjust the material flow rate, fundamentally avoiding the "overchlorination" phenomenon caused by improper proportioning, eliminating tail-end chlorine alarms, and ensuring that tail gas emissions meet national standards (≤20 mg / m³), guaranteeing operational safety and environmental compliance. Through real-time feedback and feedforward adjustment of the hydrochloric acid concentration analyzer, it can quickly respond to and correct concentration deviations, ensuring that the final output hydrochloric acid concentration is stable and qualified. Operations such as increasing and decreasing load and adjusting concentration, which originally required frequent manual intervention, are now automatically completed by the control system, significantly reducing the frequency of manual operation from about 3 times / person / hour to about 0.5 times / person / hour, greatly reducing labor intensity and improving production efficiency. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of an embodiment of the present utility model.

[0016] Explanation of icon numbers: Hydrochloric acid synthesis furnace 1; pressure transmitter 11; 2. Primary falling film absorber; 21. Absorbent water supply pipeline; 22. Absorbent water flow control valve; 23. Hydrochloric acid concentration analyzer; 24. Absorbent water flow meter; Secondary falling film absorber 3; 4. Chlorine buffer tank; 41. Chlorine supply pipeline; 42. Chlorine flow control valve; 43. Chlorine online analyzer; 44. Chlorine flow meter; 5. Hydrogen supply pipeline; 51. Hydrogen flow control valve; 52. Online hydrogen analyzer; 53. Hydrogen flow meter; Flash tank 6; Vent line 61; Vent valve 62; Nitrogen purging pipeline 7; nitrogen instrument valve 71. Detailed Implementation

[0017] The following will describe the implementation of this utility model in detail with reference to specific embodiments, so that the process of how this utility model uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0018] Example: Figure 1 As shown in this embodiment, the core of the hydrochloric acid furnace APC automatic control device lies in constructing a hardware system with a DCS system as the control center, integrating multiple online detection instruments and actuator valves, thereby realizing the automation and precision of production.

[0019] The device in this embodiment includes the following core components: a reaction and absorption unit, a material supply unit, a detection unit, an auxiliary and safety unit, and a controller.

[0020] The reaction and absorption unit mainly includes a hydrochloric acid synthesis furnace 1, a primary falling film absorber 2 and a secondary falling film absorber 3 connected to it in sequence through pipelines. This is the main equipment for realizing the synthesis and absorption of hydrochloric acid.

[0021] Material supply unit: including chlorine supply, hydrogen supply and absorption water supply.

[0022] Chlorine supply: Raw chlorine from upstream and liquefied tail gas enter chlorine buffer tank 4 for mixing. The outlet of chlorine buffer tank 4 is connected to the chlorine inlet of hydrochloric acid synthesis furnace 1 through chlorine supply pipeline 41. Chlorine flow control valve 42 and chlorine online analyzer 43 are installed sequentially along the chlorine flow direction on chlorine supply pipeline 41. Chlorine online analyzer 43 is preferably installed on the pipeline between the outlet of chlorine buffer tank 4 and chlorine flow control valve 42 to analyze the purity of mixed chlorine from chlorine buffer tank 4 as early as possible.

[0023] Hydrogen supply: A hydrogen flow control valve 51 is installed on the hydrogen supply pipeline 5. The hydrogen supply pipeline 5 is connected to the hydrogen inlet of the hydrochloric acid synthesis furnace 1. The hydrogen supply pipeline 5 is also equipped with an online hydrogen analyzer 52, which is used to detect the hydrogen purity in real time and provide a more comprehensive basis for the controller to calculate the ratio.

[0024] Absorption water supply: The absorption water inlet of the first-stage falling film absorber 2 is connected to an absorption water supply pipeline 21, and an absorption water flow control valve 22 is installed on the absorption water supply pipeline 21.

[0025] Detection unit: A hydrochloric acid concentration analyzer 23 is installed on the hydrochloric acid outlet pipeline of the first-stage falling film absorber 2 to monitor the concentration of the produced hydrochloric acid in real time. A pressure transmitter 11 is installed on the hydrochloric acid synthesis furnace 1 to monitor the furnace pressure in real time. A chlorine flow meter 44, a hydrogen flow meter 53, and an absorption water flow meter 24 are respectively installed on the chlorine supply pipeline 41, the hydrogen supply pipeline 5, and the absorption water supply pipeline 21 to detect the instantaneous flow rate of each material.

[0026] Auxiliary and safety units: The system includes a flash tank 6 connected to the hydrochloric acid synthesis furnace 1, used to recover reaction heat and generate steam. The flash tank 6 is connected to a venting pipeline 61, which is equipped with a venting valve 62. The chlorine supply pipeline 41 and the hydrogen supply pipeline 5 are also connected, either together or separately, to a nitrogen replacement pipeline 7. The nitrogen replacement pipeline 7 is equipped with a nitrogen instrument valve 71 for safe replacement during furnace shutdown.

[0027] Controller (not shown in the figure): In this embodiment, the controller preferably adopts a DCS distributed control system. The signal input terminal of the DCS control system is connected to the chlorine online analyzer 43, hydrochloric acid concentration analyzer 23, pressure transmitter 11, chlorine flow meter 44, hydrogen flow meter 53, absorption water flow meter 24, and hydrogen online analyzer 52 via cables for real-time acquisition of relevant parameters. The control output terminal of the DCS control system is connected to the chlorine flow control valve 42, hydrogen flow control valve 51, absorption water flow control valve 22, vent valve 62, and nitrogen instrument valve 71 via cables, thereby enabling the actuators to operate based on the acquired data.

[0028] The aforementioned chlorine online analyzer 43, hydrochloric acid concentration analyzer 23, pressure transmitter 11, hydrogen online analyzer 52, flow meter, control valve, vent valve 62, and nitrogen instrument valve 71 can all be purchased on the market and will not be described in detail here.

[0029] The construction of this hardware system provides the physical foundation for realizing the fully automatic control described above. Its working process is as follows: During normal operation, the chlorine online analyzer 43, various flow meters, pressure transmitter 11, and hydrochloric acid concentration analyzer 23 continuously send data to the controller. Based on the chlorine purity and target HCl purity parameters, the controller calculates and outputs signals to the hydrogen flow control valve 51 and chlorine flow control valve 42 in real time to ensure accurate hydrogen-chlorine ratio. Simultaneously, based on feedback from the hydrochloric acid concentration analyzer, the controller outputs a signal to adjust the absorption water flow control valve to stabilize the product concentration.

[0030] When the load is increased or decreased, the operator changes the load setting value on the controller. The controller then automatically and gradually adjusts the opening of the absorption water flow control valve 22, the chlorine flow control valve 42 and the hydrogen flow control valve 51 in a preset sequence through output signals until the target load is reached. The flow ratio of each material remains stable throughout the entire process.

[0031] When the furnace is shut down, the operator triggers the shutdown command, and the controller outputs control signals in sequence: first, it controls the vent valve 62 of the flash tank 6 to operate, then it alternately closes the chlorine flow control valve 42 and the hydrogen flow control valve 51 according to logic, and finally, after the valve opening reaches the safe position, it first fully closes the chlorine flow control valve 42 and then fully closes the hydrogen flow control valve 51, and automatically opens the nitrogen instrument valve 71 to replace the system.

[0032] Although the present invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the present invention without departing from the spirit and scope of the present invention as defined in the appended claims, and all such changes shall be within the scope of protection of the present invention.

Claims

1. An automatic control device for a hydrochloric acid furnace (APC), comprising a hydrochloric acid synthesis furnace, a chlorine buffer tank, a hydrogen supply pipeline, a primary falling film absorber, and a controller, characterized in that: The outlet of the chlorine buffer tank is connected to the chlorine inlet of the hydrochloric acid synthesis furnace through a chlorine supply pipeline. A chlorine flow control valve and an online chlorine analyzer are sequentially installed along the chlorine flow direction on the chlorine supply pipeline. A hydrogen flow control valve is installed on the hydrogen supply pipeline, and the hydrogen supply pipeline is connected to the hydrogen inlet of the hydrochloric acid synthesis furnace. The absorption water inlet of the first-stage falling film absorber is connected to an absorption water supply pipeline, and an absorption water flow control valve is installed on the absorption water supply pipeline. The gas inlet of the first-stage falling film absorber is connected to the gas outlet of the hydrochloric acid synthesis furnace, and a hydrochloric acid concentration analyzer is installed on the hydrochloric acid outlet pipeline of the first-stage falling film absorber. The controller is communicatively connected to the online chlorine analyzer and the hydrochloric acid concentration analyzer; The controller is communicatively connected to the chlorine flow control valve, the hydrogen flow control valve, and the absorption water flow control valve.

2. The hydrochloric acid furnace APC automatic control device according to claim 1, characterized in that: The hydrogen supply pipeline is also equipped with an online hydrogen analyzer for detecting hydrogen purity, and the online hydrogen analyzer is communicatively connected to the controller.

3. The hydrochloric acid furnace APC automatic control device according to claim 1, characterized in that: It also includes a flash tank connected to the hydrochloric acid synthesis furnace, the flash tank being connected to a venting pipeline, the venting pipeline being equipped with a venting valve, the chlorine supply pipeline and the hydrogen supply pipeline being connected to a nitrogen replacement pipeline, the nitrogen replacement pipeline being equipped with a nitrogen instrument valve, and the controller being communicatively connected to the venting valve and the nitrogen instrument valve.

4. The hydrochloric acid furnace APC automatic control device according to claim 1, characterized in that: A chlorine flow meter is installed on the chlorine supply pipeline, a hydrogen flow meter is installed on the hydrogen supply pipeline, and an absorption water flow meter is installed on the absorption water supply pipeline. The chlorine flow meter, hydrogen flow meter, and absorption water flow meter are all communicatively connected to the controller.

5. The hydrochloric acid furnace APC automatic control device according to claim 1, characterized in that: The online chlorine analyzer is installed on the pipeline between the outlet of the chlorine buffer tank and the chlorine flow control valve.

6. The hydrochloric acid furnace APC automatic control device according to claim 1, characterized in that: It also includes a secondary falling film absorber, wherein the gas outlet of the primary falling film absorber is connected to the gas inlet of the secondary falling film absorber.

7. The hydrochloric acid furnace APC automatic control device according to claim 1, characterized in that: The controller is a DCS (Distributed Control System).

8. The hydrochloric acid furnace APC automatic control device according to claim 1, characterized in that: The hydrochloric acid synthesis furnace is equipped with a pressure transmitter, which is communicatively connected to the controller.

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