Ferric trichloride preparation system

Abstract

The utility model belongs to the technical field of chemical preparation, and particularly relates to a ferric trichloride preparation system which comprises a chlorination reactor, a pretreatment unit and a dechlorination unit, the gas output end of the chlorination reactor is connected with the input end of the pretreatment unit, and the liquid output end of the chlorination reactor is connected with a chloroacetic acid buffer tank; the dechlorination unit comprises a dechlorination tower, a ferric chloride finished product tank and an alcohol absorption tank, the gas output end of the pretreatment unit is connected with the input end of the dechlorination tower, the liquid output end of the dechlorination tower is connected with the ferric chloride finished product tank, and the gas output end of the dechlorination tower is connected with the alcohol absorption tank. Free chlorine in hydrogen chloride is absorbed by ferrous chloride to generate a byproduct ferric trichloride, the purity of hydrogen chloride and ferric trichloride is improved while tail gas emission is reduced, a high-quality flocculating agent is provided for downstream customers, production consumption is greatly reduced, and economic benefits are improved.

Description

Technical Field

[0001] This utility model belongs to the field of chemical preparation technology, specifically relating to a ferric chloride preparation system. Background Technology

[0002] Chloroacetic acid is generally synthesized by reacting glacial acetic acid and chlorine gas under the catalysis of acetic anhydride. During the reaction, hydrogen chloride gas, a byproduct, is also generated. The hydrogen chloride gas contains free chlorine and needs to be purified. Currently, solvents such as potassium bromide or formic acid are commonly used to remove the free chlorine from the hydrogen chloride, but this method results in the waste of chlorine gas.

[0003] Ferric chloride is an important chemical product with a wide range of applications: it is used as a water purifier in drinking water treatment, as a flocculant in wastewater treatment, as an etchant in the electronics industry, as an oxidant and mordant for indigo dyes in the printing and dyeing industry, and when added to concrete, it can increase the strength of buildings, provide corrosion resistance, and prevent water seepage.

[0004] The chlorination process for preparing ferric chloride requires the introduction of a large amount of chlorine gas. Therefore, how to integrate the ferric chloride preparation system with the chloroacetic acid system to improve the utilization rate of chlorine in the tail gas of the chloroacetic acid system, thereby reducing tail gas generation and lowering production costs, has become a challenge. Utility Model Content

[0005] To address the problems existing in the prior art, this invention provides a ferric chloride preparation system that utilizes ferrous chloride to absorb free chlorine from hydrogen chloride to generate ferric chloride as a byproduct. This reduces exhaust emissions while increasing the purity of both hydrogen chloride and ferric chloride, providing downstream customers with high-quality flocculants, significantly reducing production consumption, and improving economic efficiency.

[0006] The specific technical solution adopted in this utility model is as follows:

[0007] A ferric chloride preparation system includes a chlorination reactor, a pretreatment unit, and a dechlorination unit. The gas output end of the chlorination reactor is connected to the input end of the pretreatment unit, and the liquid output end of the chlorination reactor is connected to a chloroacetic acid buffer tank. The dechlorination unit includes a dechlorination tower, a ferric chloride product tank, and an alcohol absorption tank. The gas output end of the pretreatment unit is connected to the input end of the dechlorination tower, the liquid output end of the dechlorination tower is connected to the ferric chloride product tank, and the gas output end of the dechlorination tower is connected to the alcohol absorption tank.

[0008] Furthermore, a vacuum negative pressure dehydration tank is also provided between the dechlorination tower and the ferric chloride finished product tank. The input end of the vacuum negative pressure dehydration tank is connected to the liquid output end of the dechlorination tower, and the output end of the vacuum negative pressure dehydration tank is connected to the input end of the ferric chloride finished product tank.

[0009] Furthermore, multiple dechlorination towers are connected in series. The gas input end of the first-stage dechlorination tower is connected to the gas output end of the pretreatment unit, the gas output end of the first-stage dechlorination tower is connected to the gas input end of the intermediate-stage drying tower, the gas output end of the intermediate-stage drying tower is connected to the gas input end of the final-stage dechlorination tower, the gas output end of the final-stage dechlorination tower is connected to the alcohol absorption tank, and the liquid output ends of the first-stage dechlorination tower, the intermediate-stage dechlorination tower, and the final-stage dechlorination tower are respectively connected to the ferric chloride finished product tank.

[0010] Furthermore, a drying tower is also provided between the dechlorination tower and the alcohol absorption tank. Multiple drying towers are connected in series. The input end of the first-stage drying tower is connected to the gas output end of the dechlorination tower, the output end of the first-stage drying tower is connected to the input end of the intermediate-stage drying tower, the output end of the intermediate-stage drying tower is connected to the input end of the final-stage drying tower, and the output end of the final-stage drying tower is connected to the input end of the alcohol absorption tank.

[0011] Furthermore, the pretreatment unit includes a hydrochloric acid scrubbing tower, a falling film absorption tower, and a finished acid tank. The tail gas output of the chlorination reactor is connected to the gas input of the hydrochloric acid scrubbing tower, the gas output of the hydrochloric acid scrubbing tower is connected to the gas input of the dechlorination tower, the liquid output of the hydrochloric acid scrubbing tower is connected to the input of the falling film absorption tower, the output of the falling film absorption tower is connected to the input of the finished acid tank, and the finished acid tank is also connected to the liquid input of the hydrochloric acid scrubbing tower via a circulating pump.

[0012] Furthermore, a cryostat is also provided between the chlorination reactor and the hydrochloric acid scrubbing tower. The gas input end of the cryostat is connected to the gas output end of the chlorination reactor, the gas output end of the cryostat is connected to the gas input end of the hydrochloric acid scrubbing tower, and the liquid output end of the cryostat is connected to the chlorination reactor.

[0013] The beneficial effects of this utility model are:

[0014] 1. In this invention, the hydrogen chloride gas and free chlorine generated from the reaction of chloroacetic acid are used in the preparation of ferric chloride. Ferrous chloride absorbs the free chlorine in the hydrogen chloride to generate ferric chloride as a byproduct, reducing exhaust emissions while improving the purity of hydrogen chloride and ferric chloride. This provides downstream customers with high-quality flocculants, significantly reducing production consumption and improving economic efficiency.

[0015] 2. The process equipment in this utility model requires little investment, is highly operable, energy-saving and environmentally friendly, and its by-products have wide applications. Attached Figure Description

[0016] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0018] Specific embodiments, such as Figure 1 As shown, this utility model provides a ferric chloride preparation system, including a chlorination reactor, a pretreatment unit, and a dechlorination unit. The gas output end of the chlorination reactor is connected to the input end of the pretreatment unit, and the liquid output end of the chlorination reactor is connected to a chloroacetic acid buffer tank. The dechlorination unit includes a dechlorination tower, a ferric chloride product tank, and an alcohol absorption tank. The gas output end of the pretreatment unit is connected to the input end of the dechlorination tower, the liquid output end of the dechlorination tower is connected to the ferric chloride product tank, and the gas output end of the dechlorination tower is connected to the alcohol absorption tank.

[0019] Since hydrogen chloride gas, a byproduct containing free chlorine, is generated during the reaction of chloroacetic acid, and a large amount of chlorine gas needs to be introduced during the chlorination process of ferric chloride, it has become a challenge to integrate the ferric chloride preparation system with the chloroacetic acid system to improve the utilization rate of chlorine gas in the tail gas of the chloroacetic acid system, thereby reducing tail gas generation and lowering production costs.

[0020] In this invention, the hydrogen chloride gas and free chlorine generated from the reaction of chloroacetic acid are used in the preparation of ferric chloride. Ferrous chloride absorbs the free chlorine in the hydrogen chloride to generate ferric chloride as a byproduct, reducing exhaust emissions while increasing the purity of hydrogen chloride and ferric chloride. This provides downstream customers with high-quality flocculants, significantly reducing production consumption and improving economic efficiency.

[0021] During production, glacial acetic acid and chlorine are added to the chlorination reactor. Under the catalysis of acetic anhydride, monochloroacetic acid is synthesized by controlling parameters such as reaction temperature, reaction pressure, reaction time, and the ratio of raw materials and auxiliary materials. The generated tail gas passes through a pretreatment unit to remove acetic acid and other gases. Hydrogen chloride containing free chlorine is passed into a dechlorination tower and purified by ferrous chloride solution in the dechlorination reactor. After ferrous chloride reacts with chlorine, it produces ferric chloride and hydrogen chloride. The high-purity hydrogen chloride in the dechlorination reactor is absorbed by an acid-alcohol solution to obtain a high-quality hydrochloric acid-alcohol solution.

[0022] A vacuum negative pressure dehydration tank is also provided between the dechlorination tower and the ferric chloride product tank. The input end of the vacuum negative pressure dehydration tank is connected to the liquid output end of the dechlorination tower, and the output end of the vacuum negative pressure dehydration tank is connected to the input end of the ferric chloride product tank. The ferric chloride solution carrying hydrogen chloride in the dechlorination tower enters the stable vacuum negative pressure dehydration tank for ferric chloride purification. The purity of the purified ferric chloride product can reach more than 99%.

[0023] Multiple dechlorination towers are connected in series. The gas input of the first-stage dechlorination tower is connected to the gas output of the pretreatment unit. The gas output of the first-stage dechlorination tower is connected to the gas input of the intermediate-stage drying tower. The gas output of the intermediate-stage drying tower is connected to the gas input of the final-stage dechlorination tower. The gas output of the final-stage dechlorination tower is connected to the alcohol absorption tank. The liquid outputs of the first-stage, intermediate-stage, and final-stage dechlorination towers are respectively connected to the ferric chloride product tank. By dechlorinating hydrogen chloride through multi-stage dechlorination towers, the free chlorine in hydrogen chloride can be almost completely absorbed, ensuring the purity of the hydrogen chloride gas.

[0024] A drying tower is also installed between the dechlorination tower and the alcohol absorption tank. Multiple drying towers are connected in series. The input end of the first-stage drying tower is connected to the gas output end of the dechlorination tower, the output end of the first-stage drying tower is connected to the input end of the intermediate-stage drying tower, the output end of the intermediate-stage drying tower is connected to the input end of the final-stage drying tower, and the output end of the final-stage drying tower is connected to the input end of the alcohol absorption tank. Since the hydrogen chloride gas also contains a certain amount of water, it needs to be dehydrated and dried by passing through the drying tower.

[0025] The pretreatment unit includes a hydrochloric acid scrubbing tower, a falling film absorption tower, and a finished acid tank. The tail gas output of the chlorination reactor is connected to the gas input of the hydrochloric acid scrubbing tower, the gas output of the hydrochloric acid scrubbing tower is connected to the gas input of the dechlorination tower, the liquid output of the hydrochloric acid scrubbing tower is connected to the input of the falling film absorption tower, and the output of the falling film absorption tower is connected to the input of the finished acid tank. The finished acid tank is also connected to the liquid input of the hydrochloric acid scrubbing tower via a circulating pump. The liquid phase in the hydrochloric acid scrubbing tower is hydrochloric acid, which can recover acetic acid from the tail gas. The purity of the acetic acid can be ensured by the circulating scrubbing of the circulating pump.

[0026] A cryogenic cooler is also installed between the chlorination reactor and the hydrochloric acid scrubbing tower. The gas inlet of the cryogenic cooler is connected to the gas outlet of the chlorination reactor, and the gas outlet of the cryogenic cooler is connected to the gas inlet of the hydrochloric acid scrubbing tower. The liquid outlet of the cryogenic cooler is connected to the chlorination reactor. The cryogenic cooler is a heat exchanger that cools the exhaust gas and recovers heat energy. At the same time, some of the chlorine and acetic acid gases condense after cooling to form liquid chlorine and liquid acetic acid, which flow back to the chlorination reactor to continue the reaction.

Claims

1. A ferric chloride preparation system, comprising a chlorination reactor, a pretreatment unit, and a dechlorination unit, wherein the gas output end of the chlorination reactor is connected to the input end of the pretreatment unit, and the liquid output end of the chlorination reactor is connected to a chloroacetic acid buffer tank, characterized in that, The dechlorination unit includes a dechlorination tower, a ferric chloride product tank, and an alcohol absorption tank. The gas output end of the pretreatment unit is connected to the input end of the dechlorination tower, the liquid output end of the dechlorination tower is connected to the ferric chloride product tank, and the gas output end of the dechlorination tower is connected to the alcohol absorption tank.

2. The ferric chloride preparation system according to claim 1, characterized in that, A vacuum negative pressure dehydration tank is also provided between the dechlorination tower and the ferric chloride finished product tank. The input end of the vacuum negative pressure dehydration tank is connected to the liquid output end of the dechlorination tower, and the output end of the vacuum negative pressure dehydration tank is connected to the input end of the ferric chloride finished product tank.

3. The ferric chloride preparation system according to claim 1, characterized in that, The dechlorination towers are arranged in series in multiple sets. The gas input end of the first-stage dechlorination tower is connected to the gas output end of the pretreatment unit. The gas output end of the first-stage dechlorination tower is connected to the gas input end of the intermediate-stage drying tower. The gas output end of the intermediate-stage drying tower is connected to the gas input end of the final-stage dechlorination tower. The gas output end of the final-stage dechlorination tower is connected to the alcohol absorption tank. The liquid output ends of the first-stage dechlorination tower, the intermediate-stage dechlorination tower, and the final-stage dechlorination tower are respectively connected to the ferric chloride finished product tank.

4. The ferric chloride preparation system according to claim 1, characterized in that, A drying tower is also provided between the dechlorination tower and the alcohol absorption tank. Multiple drying towers are connected in series. The input end of the first-stage drying tower is connected to the gas output end of the dechlorination tower, the output end of the first-stage drying tower is connected to the input end of the intermediate-stage drying tower, the output end of the intermediate-stage drying tower is connected to the input end of the final-stage drying tower, and the output end of the final-stage drying tower is connected to the input end of the alcohol absorption tank.

5. The ferric chloride preparation system according to claim 1, characterized in that, The pretreatment unit includes a hydrochloric acid scrubbing tower, a falling film absorption tower, and a finished acid tank. The tail gas output of the chlorination reactor is connected to the gas input of the hydrochloric acid scrubbing tower, the gas output of the hydrochloric acid scrubbing tower is connected to the gas input of the dechlorination tower, the liquid output of the hydrochloric acid scrubbing tower is connected to the input of the falling film absorption tower, the output of the falling film absorption tower is connected to the input of the finished acid tank, and the finished acid tank is also connected to the liquid input of the hydrochloric acid scrubbing tower via a circulating pump.

6. The ferric chloride preparation system according to claim 5, characterized in that, A cryogenic cooler is also provided between the chlorination reactor and the hydrochloric acid scrubbing tower. The gas input end of the cryogenic cooler is connected to the gas output end of the chlorination reactor, the gas output end of the cryogenic cooler is connected to the gas input end of the hydrochloric acid scrubbing tower, and the liquid output end of the cryogenic cooler is connected to the chlorination reactor.

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