Device for producing chlorine by using hydrogen chloride and oxygen

Abstract

The utility model relates to a device for producing chlorine by using hydrogen chloride and oxygen, which belongs to the technical field of treatment and utilization of hydrogen chloride, and comprises a preheater for mixing and preheating hydrogen chloride gas and oxygen and introducing the mixed gas into a reactor; the reactor is used for carrying out catalytic oxidation on the hydrogen chloride gas through a copper-based catalyst to form chlorine and water vapor, and introducing the mixed gas into the quench tower; the quench tower is used for cooling the mixed gas, absorbing hydrogen chloride gas which is not completely reacted in the mixed gas, and introducing the mixed gas without the hydrogen chloride gas into the drying tower; the drying tower is used for drying the mixed gas and introducing the dried mixed gas into the chlorine rectifying tower; and the chlorine rectifying tower is used for separating oxygen in the mixed gas and extracting filtrate. The device for producing chlorine by using hydrogen chloride and oxygen is simple in process, low in energy consumption and low in operation cost.

Description

Technical Field

[0001] The utility model belongs to the technical field of treatment and utilization of by-product hydrogen chloride in the chlorine industry, in particular to a device for producing chlorine by using hydrogen chloride and oxygen. Background Art

[0002] Chlorine is a critical chemical raw material. my country's annual chlorine consumption exceeds 20 million tons, accounting for over one-third of global chlorine consumption. Chlor-alkali production supplies almost all of this chlorine. However, chlor-alkali production consumes a staggering 2,760 kWh of electricity per ton of chlorine, and the entire chlor-alkali industry accounts for approximately 5% of my country's electricity consumption. Furthermore, fluctuations in market demand for chlorine and alkali can lead to unbalanced development in the chlor-alkali industry.

[0003] On the other hand, the production of chlorine-related products such as MDI, TDI, and methane chloride generally suffers from the problem of low chlorine atom utilization. For every mole of chlorine consumed, one mole of by-product hydrogen chloride is produced. Currently, most of the by-product hydrogen chloride is absorbed by water and made into hydrochloric acid. According to incomplete statistics, the total amount of industrial by-product hydrogen chloride in my country is close to 4 million tons / year. With the large-scale expansion of chlorine-related products such as MDI, TDI, and methane chloride and the development of the chlor-alkali industry, the total amount of by-product hydrogen chloride is expected to reach 5 million tons / year in the next five years. Hydrochloric acid has low added value, high transportation and storage costs, and is difficult to sell. The discharge destination of hydrochloric acid has become a bottleneck restricting the further development of chlorine-consuming industries.

[0004] If hydrogen chloride, a large industrial byproduct that is difficult to process, could be directly converted into chlorine for utilization, achieving a closed-loop chlorine cycle and zero emissions during the reaction process, it would not only solve the problem of excess hydrogen chloride in chlorine-consuming industries but also, to a certain extent, meet the growing industrial demand for chlorine, promote the healthy development of emerging industries, and optimize and upgrade the chlor-alkali industry, meeting the overall requirements for sustainable development. Currently, methods for producing chlorine from hydrogen chloride can be divided into three main categories: electrolysis, direct oxidation, and catalytic oxidation.

[0005] Electrolysis converts hydrogen chloride into chlorine gas through electrolysis, and can be categorized as either a dry or wet process. However, this method suffers from high operating costs and significant investment. Furthermore, the electrolysis process is highly sensitive to impurities in the hydrochloric acid raw material, and the byproduct hydrogen chloride gas and hydrochloric acid both contain other impurities to varying degrees. Consequently, hydrochloric acid electrolysis has limited widespread adoption of chlorine production technology.

[0006] Direct oxidation is a method for producing chlorine by directly oxidizing hydrogen chloride with inorganic oxidants such as MnO2, H2O2, and NO2. Typical examples include the Weldson process, the Kel-Chlor process, and the Degussa process. However, direct oxidation methods are difficult to commercialize due to complex reaction equipment, difficulty in product separation, high energy consumption, and wastewater treatment.

[0007] Catalytic oxidation involves the oxidation of hydrogen chloride to chlorine and H₂O using oxygen under catalytic conditions. Representative methods include the Deacon process, the Shell process, and Sumitomo's technology. Sumitomo Chemical Co., Ltd. of Japan developed a rutile TiO₂-supported ruthenium oxide catalyst and has applied for numerous patents, creating a technological blockade. The company has also developed a complete plant utilizing this catalyst, but the process is complex and the catalyst is expensive, resulting in high costs. Utility Model Content

[0008] The technical problem to be solved by the utility model is to propose a device for preparing chlorine from hydrogen chloride and oxygen, so as to solve the problems existing in the industry of preparing chlorine from hydrogen chloride, such as complex equipment, difficult product separation, high energy consumption, expensive catalyst and cumbersome and complicated process of the complete device.

[0009] In order to solve the above technical problems, the technical solutions provided by the present invention are as follows:

[0010] The utility model relates to a device for producing chlorine by using hydrogen chloride and oxygen, which comprises:

[0011] a preheater, used for mixing and preheating hydrogen chloride gas and oxygen, and passing the mixed gas into the reactor;

[0012] A reactor for catalytically oxidizing hydrogen chloride gas to form chlorine gas and water vapor using a copper-based catalyst, and passing the mixed gas into a quenching tower;

[0013] The quenching tower is used to cool the mixed gas, absorb the unreacted hydrogen chloride gas in the mixed gas, and pass the mixed gas with the hydrogen chloride gas removed into the drying tower;

[0014] The drying tower is used to dry the mixed gas and pass the dried mixed gas into the chlorine distillation tower;

[0015] Chlorine distillation tower, used to separate oxygen from mixed gas and extract filtrate.

[0016] Preferably, a heat cycler and a waste heat boiler are connected between the preheater and the reactor. The heat cycler is used to collect and store the heat released by the catalytic oxidation reaction in the reactor and transfer the heat to the waste heat boiler using a high-temperature medium. The waste heat boiler includes a water inlet and two steam outlets, one of which is connected to the preheater and the other to the outside. The waste heat boiler uses the high-temperature medium to heat water input into the water inlet and generate steam, some of which is transferred to the preheater to preheat the hydrogen chloride gas and oxygen. The provision of the heat cycler and waste heat boiler fully utilizes the heat released by the catalytic oxidation reaction, thereby reducing the energy consumption of the preheater.

[0017] Preferably, the quenching tower is provided with a water inlet at the top and a hydrochloric acid recovery port at the bottom; the quenching tower is cooled by pure water introduced through the water inlet at the top and absorbs incompletely reacted hydrogen chloride gas to form hydrochloric acid, which is then recovered through the hydrochloric acid recovery port.

[0018] Preferably, the drying tower is provided with a sulfuric acid inlet at the top and a sulfuric acid recovery port at the bottom, and the drying tower absorbs water vapor through sulfuric acid.

[0019] Preferably, a compressor and a condenser are sequentially connected between the drying tower and the chlorine distillation tower;

[0020] A compressor, used for compressing the dried mixed gas;

[0021] The condenser is used to cool the compressed mixed gas.

[0022] Preferably, an oxygen recovery port is provided at the top of the chlorine distillation tower, and the oxygen recovery port is connected to the preheater to recover the separated oxygen and reduce the oxygen consumption.

[0023] Compared with the prior art, the technical solution provided by this utility model has the following beneficial effects:

[0024] 1. The apparatus for producing chlorine from hydrogen chloride and oxygen disclosed in the present invention comprises a reactor, a quenching tower, a drying tower, a compressor, and a chlorine distillation tower connected in sequence. A copper-based catalyst is used to catalytically oxidize hydrogen chloride to form a mixed gas. The quenching tower absorbs incompletely reacted hydrogen chloride gas. The drying tower dries the mixed gas. The chlorine distillation tower separates oxygen to ultimately produce a high-concentration filtrate. The complete apparatus has a simple process, low energy consumption, and low operating costs.

[0025] 2. The quenching tower of the device for producing chlorine from hydrogen chloride and oxygen involved in the utility model is provided with a water inlet at the top and a hydrochloric acid recovery port at the bottom. The temperature can be directly lowered to the target temperature through the quenching tower without first being cooled by a cooler, further reducing investment costs. At the same time, distilled water can also be introduced into the quenching tower to absorb unreacted hydrogen chloride gas, thereby simultaneously achieving the purpose of cooling and removing hydrogen chloride.

[0026] 3. The apparatus for producing chlorine from hydrogen chloride and oxygen involved in the utility model has a heat cycler and a waste heat boiler connected between the preheater and the reactor. The heat cycler removes the heat released during the reaction, thereby controlling the temperature of the reactor within the required range. At the same time, the heat is transferred to the waste heat boiler to heat the distilled water introduced into the preheating boiler and form steam. The steam returns to the preheater to preheat the hydrogen chloride gas and oxygen, fully utilizing the heat generated during the reaction and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The utility model is a schematic structural diagram of a device for producing chlorine by using hydrogen chloride and oxygen.

[0028] Description of the drawings: 1-preheater, 2-waste heat boiler, 3-heat circulation device, 4-reactor, 5-quenching tower, 6-drying tower, 7-compressor, 8-condenser, 9-chlorine distillation tower. DETAILED DESCRIPTION

[0029] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with embodiments. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0030] Refer to the attached Figure 1 As shown, the utility model relates to a device for producing chlorine from hydrogen chloride and oxygen, comprising:

[0031] The preheater 1 has an input end for inputting hydrogen chloride gas and oxygen, and an output end connected to the input end of the reactor 4, for mixing and preheating the hydrogen chloride gas and oxygen, and passing the mixed gas into the reactor 4.

[0032] The reactor 4 has an input end connected to the output end of the preheater 1 and an output end connected to the quenching tower 5, and is used to catalytically oxidize the hydrogen chloride gas to form chlorine and water vapor using a copper-based catalyst, and pass the mixed gas into the quenching tower 5.

[0033] A heat cycle device 3 and a waste heat boiler 2 are also connected between the preheater 1 and the reactor 4. The heat cycle device 3 is used to collect and store the heat released by the catalytic oxidation reaction in the reactor, and use a high-temperature medium to transport the heat to the waste heat boiler 2; the waste heat boiler 2 includes a water inlet and two steam outlets, one of which is connected to the preheater 1 and the other is connected to the outside. The waste heat boiler 2 uses the high-temperature medium to heat the water input into the water inlet and generate steam, and transports part of the steam to the preheater 1 to preheat the hydrogen chloride gas and oxygen.

[0034] A quenching tower 5 is provided with a water inlet at the top and a hydrochloric acid recovery port at the bottom. The input end of the quenching tower 5 is connected to the output end of the reactor 4, and the output end of the quenching tower 5 is connected to the drying tower 6. The quenching tower 5 cools the mixed gas with pure water introduced through the water inlet at the top, absorbs the unreacted hydrogen chloride gas in the mixed gas to form hydrochloric acid, and introduces the mixed gas from which the hydrogen chloride gas has been removed into the drying tower 6 and the hydrochloric acid is recovered through the hydrochloric acid recovery port.

[0035] The drying tower 6 is provided with a sulfuric acid inlet at the top and a sulfuric acid recovery port at the bottom. The input end of the drying tower 6 is connected to the output end of the quenching tower 5, and the output end of the drying tower 6 is connected to the input end of the compressor 7. The drying tower 6 absorbs water vapor through sulfuric acid, thereby drying the mixed gas, and then passes the dried mixed gas into the compressor 7.

[0036] The compressor 7 has an input end connected to the output end of the drying tower 6 , and an output end of the compressor 7 is connected to an input end of the condenser 8 . The compressor 7 is used to compress the dried mixed gas.

[0037] The condenser 8 has an input end connected to the output end of the compressor 7 , and an output end of the condenser 8 is connected to an input end of the chlorine distillation tower 9 . The condenser 8 is used to cool the compressed mixture.

[0038] A chlorine distillation tower 9 is provided, wherein the input end of the chlorine distillation tower 9 is connected to the output end of the condenser 8. An oxygen recovery port is provided on the top of the chlorine distillation tower 9, which is connected to the preheater, and a filtrate collecting port is provided at the bottom. The chlorine distillation tower 9 is used to separate oxygen from the compressed and cooled mixed gas and extract filtrate, wherein the separated oxygen is returned to the preheater 1 through the oxygen recovery port for reuse, and the filtrate is collected from the filtrate collecting port.

[0039] The method for using the above-mentioned device for producing chlorine from hydrogen chloride and oxygen comprises the following steps:

[0040] Step 1. Hydrogen chloride gas B and oxygen A are charged into a preheater 1 for mixing and preheating. After preheating to 200-350°C, the mixed gas C is input into a reactor 4 containing a copper-based catalyst. Reactor 4 can be a single reactor or multiple reactors connected in parallel. The hydrogen chloride gas is catalytically oxidized to form chlorine and water vapor, while releasing heat. The reaction formula is:

[0041] ;

[0042] Under the action of the catalyst, approximately 93 wt% of the hydrogen chloride is oxidized to chlorine. The entire reaction is exothermic. Therefore, heat is removed from reactor 4 via thermal cycler 3, maintaining the temperature within reactor 4 at 260-400°C and the pressure at 0-1.0 MPaG. Thermal cycler 3 employs a molten salt circulation device or a pressurized thermal oil circulation device. The removed high-temperature medium H2 enters waste heat boiler 2, into which distilled water I is introduced. Upon heating, saturated steam at a pressure of 2.3 MPaG is produced as a by-product. Part of this steam returns to preheater 1 to preheat the hydrogen chloride gas and oxygen, while the remaining steam J is discharged. The medium in thermal cycler 3 cools down upon passing through waste heat boiler 2. The cooled medium H1 returns to reactor 4 to absorb heat again. After catalytic oxidation, a high-temperature mixed gas D containing chlorine, water vapor, unreacted hydrogen chloride gas, and oxygen is formed.

[0043] Step 2.1. The hot mixed gas D is output from reactor 1 and enters quench tower 5, which can be a single-stage or multi-stage quench tower. Quench tower 5 rapidly cools the hot mixed gas and absorbs unreacted hydrogen chloride gas from mixed gas D. The bottom temperature of quench tower 5 is controlled by a circulating cooler at 20-60°C. Pure water I is added to the top of the tower to absorb the hydrogen chloride gas, forming hydrochloric acid, which is recovered from the bottom of quench tower 5.

[0044] Step 2.2. After the hydrogen chloride gas is removed, the mixed gas E enters the drying tower 6 for drying to remove water vapor. The task of the drying tower 6 is to dry the wet mixed gas to a moisture content of <50 ppm. Specifically, the mixed gas E is countercurrently contacted with 96-98% sulfuric acid L from the top of the tower. The water is absorbed by the sulfuric acid, and the heat of dissolution of the sulfuric acid is removed by the circulating cooler. The dilute sulfuric acid M in the bottom of the tower is discharged and recovered through liquid level control.

[0045] Step 2.3. The dried mixed gas F is sequentially passed into the compressor 7 and the condenser 8 for compression and condensation. The compressor 7 compresses the dried mixed gas to 1-1.5 MPaG, and the condenser 8 cools it to -20--60°C.

[0046] Step 2.4. The compressed and condensed mixed gas F is passed into a chlorine distillation tower 9. The bottom temperature of the chlorine distillation tower 9 is controlled at 60-90°C, and the top temperature is controlled at -20--60°C. The function of the chlorine distillation tower 9 is to separate oxygen and obtain high-purity chlorine liquid. The separated oxygen A is circulated from the top of the distillation tower to the preheater and ultimately enters the reactor for further catalytic oxidation. The high-purity chlorine liquid G is collected from the bottom of the chlorine distillation tower 9.

[0047] The above describes the present invention in detail with reference to the embodiments. However, the above contents are only preferred embodiments of the present invention and should not be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent application of the present invention.

Claims

1. A device for producing chlorine from hydrogen chloride and oxygen, characterized in that: It includes: a preheater, used for mixing and preheating hydrogen chloride gas and oxygen, and passing the mixed gas into the reactor; A reactor for catalytically oxidizing hydrogen chloride gas to form chlorine gas and water vapor using a copper-based catalyst, and passing the mixed gas into a quenching tower; The quenching tower is used to cool the mixed gas, absorb the unreacted hydrogen chloride gas in the mixed gas, and pass the mixed gas with the hydrogen chloride gas removed into the drying tower; The drying tower is used to dry the mixed gas and pass the dried mixed gas into the chlorine distillation tower; Chlorine distillation tower, used to separate oxygen from mixed gas and extract filtrate.

2. The device for producing chlorine from hydrogen chloride and oxygen according to claim 1, characterized in that: A heat circulation device and a waste heat boiler are connected between the preheater and the reactor. The heat circulation device is used to collect and store the heat released by the catalytic oxidation reaction in the reactor and transport the heat to the waste heat boiler using a high-temperature medium. The waste heat boiler includes a water inlet and two steam outlets, one of which is connected to the preheater and the other is connected to the outside. The waste heat boiler uses the high-temperature medium to heat the water input into the water inlet and generate steam, and transports part of the steam to the preheater to preheat the hydrogen chloride gas and oxygen.

3. The device for producing chlorine from hydrogen chloride and oxygen according to claim 1, characterized in that: The top of the quenching tower is provided with a water inlet, and the bottom is provided with a hydrochloric acid recovery port; the pure water introduced into the quenching tower through the top water inlet is cooled and absorbs the unreacted hydrogen chloride gas to form hydrochloric acid, and the hydrochloric acid is recovered through the hydrochloric acid recovery port.

4. The device for producing chlorine from hydrogen chloride and oxygen according to claim 1, characterized in that: The top of the drying tower is provided with a sulfuric acid inlet, and the bottom is provided with a sulfuric acid recovery port. The drying tower absorbs water vapor through sulfuric acid.

5. The device for producing chlorine from hydrogen chloride and oxygen according to claim 1, characterized in that: A compressor and a condenser are connected in sequence between the drying tower and the chlorine distillation tower; A compressor, used for compressing the dried mixed gas; The condenser is used to cool the compressed mixed gas.

6. The device for producing chlorine from hydrogen chloride and oxygen according to claim 1, characterized in that: The top of the chlorine distillation tower is provided with an oxygen recovery port, which is communicated with the preheater.

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