A raffinate drying device and process for preparing hydrogen peroxide by anthraquinone method

Abstract

The present invention discloses a raffinate drying device and process for preparing hydrogen peroxide by anthraquinone method. The device comprises a drying tank and a related medium conveying pipeline. The raffinate enters the drying tank from top to bottom in countercurrent through the raffinate conveying pipeline. The oxidation tail gas of the oxidation tower enters the drying tank from the oxidation tail gas inlet after being conveyed through the oxidation tail gas conveying pipeline and cooled by a cooling device. The raffinate from top to bottom is fully contacted and mixed with the oxidation tail gas from bottom to top to be dried. The dried working liquid leaves the drying tank from the working liquid outlet; the water-rich oxygen-poor gas is discharged from the oxidation tail gas outlet at the top of the drying tank. The present invention preferentially selects the oxidation tail gas coming out of the top of the oxidation tower to contact the raffinate in the equipment in the reverse or same direction, and the water absorbed by the oxidation tail gas from the raffinate is separated in the form of condensate. The method is easy to operate, has low energy consumption, does not require complex control equipment, and can reliably give the circulating working liquid that is about to enter the hydrogenation process with a suitable water content.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen peroxide production, and particularly relates to a raffinate drying device and process for preparing hydrogen peroxide by an anthraquinone process. Background Art

[0002] Currently, most of the methods for producing hydrogen peroxide (commonly known as hydrogen peroxide) in the world use the anthraquinone method, which is currently the most important method for producing hydrogen peroxide in the world.

[0003] The process is to prepare a working solution of alkyl anthraquinone and an organic solvent, introduce hydrogen for hydrogenation at a pressure of 0.15-0.30 MPa (gauge pressure), a temperature of 45-65°C, and the presence of a catalyst, and then carry out oxidation reaction with air (or oxygen) at 40-55°C, and obtain a hydrogen peroxide aqueous solution product with a mass fraction of 27.5%-35% after extraction, purification, dehydration, and regeneration. The main reaction equation is:

[0004] Hydrogen peroxide aqueous solution product. Its main reaction equation:

[0005]

[0006] Specifically, the working carrier and hydrogen react in the presence of a palladium catalyst in a hydrogenation tower to hydrogenate anthraquinone to generate the corresponding hydroanthraquinone and tetrahydroanthraquinone. The hydrogenated working liquid (called hydrogenation liquid in the industry) enters the oxidation tower, and the hydroanthraquinone and tetrahydroanthraquinone in the hydrogenation liquid react with oxygen in the air to be reduced to anthraquinone and tetrahydroanthraquinone, and hydrogen peroxide is generated in the working liquid (called oxidation liquid in the industry). The oxidized oxidation liquid enters the extraction tower, and the solubility of hydrogen peroxide in water and working liquid is different. Through pure water extraction and separation, a crude hydrogen peroxide product with a concentration of 27.5-35% is obtained. The crude product is purified in a purification tower to obtain a qualified 27.5%-35% hydrogen peroxide product.

[0007] The working liquid (called raffinate in the industry) coming out of the extraction tower will be saturated with water and carry a small amount of finely divided free water. If the raffinate with this water directly enters the hydrogenation tower, it will deactivate the palladium catalyst, which is not conducive to the hydrogenation reaction. "Chemical Technology" points out that the water content of the working liquid in the hydrogenation project cannot exceed about 98% relative humidity. All raffinates must be dehydrated before returning to the hydrogenation tower and entering the next working cycle. In addition, the water content in the circulating working liquid cannot be too low, because the appropriate amount of uniformly dissolved water in the circulating working liquid can activate the hydrogenation catalyst.

[0008] In order to obtain the relative humidity required for the reaction in the working solution, some suitable separation methods can be provided to reduce the content of free water in the working solution.

[0009] Until now, one of the methods used to remove part of the uniformly dissolved in the working liquid has been to dry the working liquid by bringing it into contact with a hygroscopic liquid, such as a 35% potassium carbonate solution. During drying, the carbonate solution will be diluted with water, but in order to maintain its drying capacity, more carbonate must be continuously added, or the solution must be evaporated, which means consuming energy. In addition, the contact with the potassium carbonate solution may give the working liquid an alkalinity that is not suitable for oxidation.

[0010] The commonly used method now is flash dehydration, which is to heat the raffinate to 50-60°C and pass it into a flash tank with a vacuum degree of -0.086 to -0.094Mpa (gauge pressure). After the flash gas is sucked out by a vacuum pump, it must be cooled with chilled water to recover the organic materials. After flash dehydration, the raffinate goes to the circulating working liquid storage tank and is pumped into the hydrogenation tower by the circulating working liquid pump for the next cycle reaction.

[0011] This drying method requires steam to heat the raffinate and a vacuum pump to extract a certain degree of vacuum. Both measures will increase energy consumption. In order to ensure sufficient air leg, higher requirements are placed on the height of the equipment layout and the smoothness of the pipeline layout. Summary of the invention

[0012] In view of the above problems, the present invention provides a raffinate drying device and process for producing hydrogen peroxide by anthraquinone method, wherein the raffinate is dried by contacting the raffinate with a gas (or gas mixture) whose water vapor pressure is lower than that of the raffinate. The present invention provides a new drying mode for raffinate with a simple process, extremely low energy consumption, safety and reliability for drying the circulating working fluid during the production of hydrogen peroxide (commonly known as hydrogen peroxide) by anthraquinone method.

[0013] In order to achieve the above object, the technical solution adopted by the present invention is:

[0014] A raffinate drying device for preparing hydrogen peroxide by an anthraquinone process comprises a drying tank, wherein a raffinate inlet and an oxidized tail gas outlet are arranged at the upper end of the drying tank, the raffinate inlet is connected to the upper outlet of an extraction tower via a raffinate delivery pipeline, an oxidized tail gas inlet and a working liquid outlet are arranged at the lower end of the drying tank, the working liquid outlet is connected to the liquid inlet of a hydrogenation tower via a working liquid delivery pipeline, the oxidized tail gas inlet is connected to the oxidized tail gas outlet of an oxidation tower via an oxidized tail gas delivery pipeline, and a cooling device is arranged on the oxidized tail gas delivery pipeline for cooling the oxidized tail gas.

[0015] Furthermore, the raffinate delivery pipeline and the oxidation tail gas delivery pipeline are provided with flow regulating devices for controlling the flow of the raffinate and the oxidation tail gas.

[0016] Furthermore, the cooling device is provided with a chilled water inlet and a chilled water return port for cooling the oxidation tail gas.

[0017] Furthermore, the drying tank has an inner diameter of 500-560 mm, an effective height of 3.6 m, and is filled with 16x16 ceramic Raschig rings to a height of 2 meters.

[0018] The present invention also proposes a raffinate drying process for preparing hydrogen peroxide by anthraquinone method, which is carried out using the above-mentioned device and includes the following processes: the raffinate coming out of the extraction tower passes through the raffinate conveying pipeline and controls the flow rate before countercurrently entering the drying tank from top to bottom through the raffinate inlet; the oxidized tail gas coming out of the oxidation tower is adjusted in flow rate, conveyed through the oxidized tail gas conveying pipeline and cooled by the cooling device before entering the drying tank from the oxidized tail gas inlet; inside the drying tank, the raffinate from top to bottom contacts and mixes with the cooled oxidized tail gas from bottom to top, and is dried after being fully mixed; the dried working liquid leaves the drying tank from the working liquid outlet of the drying tank; and the water-rich oxygen-poor gas is discharged from the oxidized tail gas outlet at the top of the drying tank.

[0019] In the above process, the drying temperature in the drying tank is 22-85°C, preferably 33-68°C.

[0020] In the above process, the pressure in the drying tank is 0.05-0.25Mpa, preferably 0.1-0.18Mpa.

[0021] In the above process, the flow rate of the raffinate entering the drying tank through the raffinate delivery pipeline is controlled to be 850-900 L / h, and the temperature of the raffinate is controlled to be 50-55°C.

[0022] In the above process, the flow rate of oxidation tail gas entering the drying tank is controlled to be 25-30Nm 3 / h; before the oxidized tail gas enters the drying tank, the temperature is controlled at 18-20℃, and the pressure of the oxidized tail gas is reduced from 0.18Mpa to 0.14Mpa.

[0023] The present invention preferably uses the oxidation tail gas from the top of the oxidation tower, and uses it when the solvent vapor does not need to be removed. The oxidation tail gas is cooled and passed into a drying tank, and contacts with the raffinate in the device in the reverse or same direction, and the water absorbed by the oxidation tail gas from the raffinate is separated in the form of condensate.

[0024] The raffinate drying process of the present invention is easy to operate, has low energy consumption, does not require complex control equipment, and can reliably impart appropriate water content to the circulating working fluid that is about to enter the hydrogenation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a raffinate drying device and a process schematic diagram of the anthraquinone method for preparing hydrogen peroxide;

[0026] In the figure: 1. drying tank; 2. raffinate inlet; 3. oxidation tail gas outlet; 4. raffinate delivery pipeline; 5. oxidation tail gas inlet; 6. working liquid outlet; 7. working liquid delivery pipeline; 8. oxidation tail gas delivery pipeline; 9. cooling device. DETAILED DESCRIPTION

[0027] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0028] like Figure 1 As shown, a raffinate drying device for preparing hydrogen peroxide by anthraquinone process comprises a drying tank 1, wherein a raffinate inlet 2 and an oxidized tail gas outlet 3 are provided at the upper end of the drying tank 1, wherein the raffinate inlet 2 is connected to the upper outlet of the extraction tower via a raffinate delivery pipeline 4, and an oxidized tail gas inlet 5 and a working liquid outlet 6 are provided at the lower end of the drying tank 1, wherein the working liquid outlet 6 is connected to the liquid inlet of the hydrogenation tower via a working liquid delivery pipeline 7, and the oxidized tail gas inlet 5 is connected to the oxidized tail gas outlet 3 of the oxidation tower via an oxidized tail gas delivery pipeline 8, and a cooling device 9 is provided on the oxidized tail gas delivery pipeline 8 for cooling the oxidized tail gas.

[0029] The raffinate delivery pipeline 4 and the oxidation tail gas delivery pipeline 8 are provided with flow regulating devices for controlling the flow of the raffinate and the oxidation tail gas.

[0030] The cooling device 9 is provided with a chilled water inlet and a chilled water return port for cooling the oxidation tail gas.

[0031] The raffinate drying process for preparing hydrogen peroxide by anthraquinone method is carried out by using the above-mentioned device, and includes the following process: the raffinate (drawn from the outlet pipe at the top of the extraction tower and equipped with a flow regulating device) enters the drying tank 1 from top to bottom through the conduit in countercurrent, and in the tank, it contacts and mixes with the cooled oxygen-depleted gas (drawn from the oxidation tail gas delivery pipe 8 and equipped with a flow regulating device) from bottom to top, and is dried after being fully mixed. The dried working liquid leaves the drying tank 1 from the working liquid outlet 6 at the bottom of the drying tank 1. The water-rich oxygen-depleted gas is discharged from the oxidation tail gas outlet 3 at the top of the drying tank 1.

[0032] The drying method according to the present invention can be carried out at a temperature of 22-85°C, preferably at a temperature of 33-68°C.

[0033] According to the present invention, the suitable pressure range for drying is 0.05-0.25 MPa (gauge pressure), and the preferred pressure is 0.1-0.18 MPa (gauge pressure).

[0034] The present invention will now be described in more detail with the following test data:

[0035] The drying tank 1 has an inner diameter of 560 mm and an effective height of 3.6 m. It is filled with 16x16 ceramic Raschig rings to a height of 2 m. The flow rate of the raffinate entering the drying tank is controlled to be 900 L / h, and the raffinate temperature is 52°C.

[0036] Control the flow rate of oxidation tail gas entering the drying tank to 28Nm 3 / h. The solvent composition of the raffinate is: heavy aromatics: (T10) 75%, TBU: 15%, TOP: 10%, and the raffinate contains 3.48g / l of saturated water before entering the drying tank.

[0037] Before the oxidized tail gas enters the drying tank 1, under the condition of temperature control at 18°C, the pressure of the oxidized tail gas drops from 0.18Mpa (gauge pressure) to 0.14Mpa (gauge pressure), the relative humidity is about 48%, and the pressure at the top of the drying tank is 0.10Mpa (gauge pressure).

[0038] When the raffinate is discharged from the bottom of the drying tank, its water content is 2.23 g / L and its relative humidity is about 65.2%.

[0039] The present invention provides a new drying mode for raffinate with simple process, extremely low energy consumption, safety and reliability for drying circulating working fluid in the process of producing hydrogen peroxide (commonly known as hydrogen peroxide) by anthraquinone method.

[0040] Before the raffinate enters the dehydrogenation tower, it is introduced into the drying tank. After the oxidation tail gas from the top of the oxidation tower is cooled, it enters the drying tank under pressure (cocurrent or countercurrent). While maintaining the original pressure of the tail gas, since the oxidation tail gas is discharged during the production process of the oxidation process, it is a process of changing the pressure from high to low. Therefore, the humidity in the oxidation tail gas is also reduced accordingly, and the raffinate in the drying tank is in contact with the oxidation tail gas at a temperature of about 36-68°C, so the raffinate can be dried to a relative humidity of 22-96%.

[0041] It should be noted that the method of the present invention can be carried out in any desorption equipment suitable for the specific purpose, such as a container or tower with a screen or filler, or a certain type of reactor in which the gas is dispersed in a liquid under stirring. In the container or tower, the gas flows from bottom to top, and the raffinate can flow in the same direction as the gas (cocurrent) or from top to bottom, in the opposite direction to the gas flow (countercurrent).

[0042] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A raffinate drying device for preparing hydrogen peroxide by anthraquinone process, characterized in that: The invention comprises a drying tank (1), wherein the upper end of the drying tank (1) is provided with a raffinate inlet (2) and an oxidized tail gas outlet (3), wherein the raffinate inlet (2) is connected to the upper outlet of the extraction tower via a raffinate delivery pipeline (4), and the lower end of the drying tank (1) is provided with an oxidized tail gas inlet (5) and a working liquid outlet (6), wherein the working liquid outlet (6) is connected to the liquid inlet of the hydrogenation tower via a working liquid delivery pipeline (7), and the oxidized tail gas inlet (5) is connected to the oxidized tail gas outlet of the oxidation tower via an oxidized tail gas delivery pipeline (8), and a cooling device (9) is provided on the oxidized tail gas delivery pipeline (8) for cooling the oxidized tail gas.

2. The raffinate drying device for preparing hydrogen peroxide by anthraquinone process according to claim 1, characterized in that: The raffinate delivery pipeline (4) and the oxidation tail gas delivery pipeline (8) are provided with flow regulating devices for controlling the flow of the raffinate and the oxidation tail gas.

3. The raffinate drying device for preparing hydrogen peroxide by anthraquinone process according to claim 2, characterized in that: The cooling device (9) is provided with a chilled water inlet and a chilled water return port, and is used to cool the oxidation tail gas.

4. The raffinate drying device for preparing hydrogen peroxide by anthraquinone process according to claim 1, characterized in that: The drying tank (1) has an inner diameter of 500-560 mm and an effective height of 3.6 m, and is filled with 16x16 ceramic Raschig rings to a height of 2 m.

5. A raffinate drying process for preparing hydrogen peroxide by anthraquinone method, using the device according to any one of claims 1 to 4, characterized in that: The process comprises the following steps: the raffinate from the extraction tower passes through the raffinate delivery pipeline (4) and controls the flow rate before counter-flowing from top to bottom through the raffinate inlet (2) into the drying tank (1); the oxidized tail gas from the oxidation tower is adjusted in flow rate, transported through the oxidized tail gas delivery pipeline (8) and cooled by the cooling device (9) before entering the drying tank (1) through the oxidized tail gas inlet (5); inside the drying tank (1), the raffinate from top to bottom contacts and mixes with the cooled oxidized tail gas from bottom to top, and is dried after being fully mixed; the dried working liquid leaves the drying tank (1) from the working liquid outlet (6) of the drying tank (1); and the water-rich oxygen-poor gas is discharged from the oxidized tail gas outlet (3) at the top of the drying tank (1).

6. The raffinate drying process for preparing hydrogen peroxide by anthraquinone process according to claim 5, characterized in that: The drying temperature in the drying tank (1) is 22-85°C.

7. The raffinate drying process for preparing hydrogen peroxide by anthraquinone process according to claim 5, characterized in that: The pressure inside the drying tank (1) is 0.05-0.25 MPa.

8. The raffinate drying process for preparing hydrogen peroxide by anthraquinone process according to claim 5, characterized in that: The flow rate of the raffinate entering the drying tank (1) through the raffinate delivery pipeline (4) is controlled to be 850-900 L / h, and the temperature of the raffinate is controlled to be 50-55°C.

9. The raffinate drying process for preparing hydrogen peroxide by anthraquinone method according to claim 5, characterized in that: Control the flow rate of oxidation tail gas into the drying tank (1) to 25-30Nm 3 / h; before the oxidized tail gas enters the drying tank (1), the temperature is controlled at 18-20°C, and the pressure of the oxidized tail gas is reduced from 0.18Mpa to 0.14Mpa.

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