Device for removing water from byproduct methyl ether generated in preparation of epoxypropane by HPPO method

Abstract

The utility model relates to the technical field of epoxypropane production, in particular to a device for removing water from a byproduct methyl ether in preparation of epoxypropane by an HPPO method, which comprises an ether-water mixture tank, an ether-water mixture feeding pump, an ether-water mixture preheater and a membrane dehydrator which are connected in sequence, the inlet of the shell is connected with an ether-water mixture preheater, the outlet of the shell is connected with a methyl ether mixture tank, the membrane pipe is provided with a molecular sieve membrane through which only water passes, and the membrane pipe is connected with a water outlet. According to the method disclosed by the invention, the use of an extracting agent benzene is omitted, the wastewater treatment difficulty is reduced, the water content in the dehydrated methyl ether can be reduced to 0.02% or below, and the quality of monomethyl ether and isomethyl ether is effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of propylene oxide production technology, and in particular to a device for removing dimethyl ether, a byproduct of propylene oxide production by the HPPO method. Background Technology

[0002] Propylene oxide (PO) is an important basic organic chemical raw material, ranking second in production volume among propylene derivatives after polypropylene. It is mainly used in the production of polyether polyols, propylene glycol, and propylene glycol ethers, and is also a key raw material for fourth-generation detergent nonionic surfactants, oilfield demulsifiers, and pesticide emulsifiers, showing broad development prospects. Propylene oxide derivatives are also widely used in the food, tobacco, pesticide, and cosmetic industries, with nearly a hundred downstream products, making it an important raw material for fine chemical products.

[0003] Industrially, the main production processes for propylene oxide are the chlorohydrin process and the co-oxidation process, accounting for approximately 70% of global propylene oxide production. This unit uses the hydrogen peroxide direct oxidation process (HPPO process), which uses propylene and hydrogen peroxide as raw materials and methanol as a solvent to produce propylene oxide, with propylene glycol, monomethyl ether, and isomethyl ether as byproducts.

[0004] Monomethyl ether and isomethyl ether azeotropically react with water, requiring dehydration of the ether-water azeotrope to obtain high-purity monomethyl ether and isomethyl ether, thereby improving economic efficiency.

[0005] Currently, in the ether recovery system of the HPPO process for propylene oxide production, for ether-water mixtures, the ether extraction tower uses benzene as the extractant to extract the water in the ether. After the extracted benzene-water material enters the reflux tank, the benzene-water phase is separated into layers. The benzene phase is returned to the ether extraction tower as reflux, while the water phase is treated as wastewater.

[0006] However, in actual operation, a small amount of ether will also evaporate and enter the ether extraction tower reflux tank along with the benzene water material, and will be discharged into the wastewater as an aqueous phase, affecting the COD of the wastewater and causing the loss of the by-product ether. Utility Model Content

[0007] The purpose of this invention is to provide a dehydration device for dimethyl ether, a byproduct of propylene oxide production via the HPPO process, to solve the problem that ether from the ether extraction tower of the ether recovery system in current propylene oxide plants enters the wastewater system, affecting the wastewater system and causing ether loss.

[0008] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0009] A device for removing dimethyl ether, a byproduct of propylene oxide production via the HPPO process, comprises an ether-water mixture tank, an ether-water mixture feed pump, an ether-water mixture preheater, and a membrane dehydrator connected in sequence. The membrane dehydrator includes a shell and a membrane tube. The inlet of the shell is connected to the ether-water mixture preheater, and the outlet of the shell is connected to the dimethyl ether mixture tank. The membrane tube is equipped with a molecular sieve membrane that allows only water to pass through, and the membrane tube is connected to an outlet.

[0010] Preferably, there are multiple membrane tubes connected to the same outlet.

[0011] Preferably, the inside of the membrane tube is in a vacuum state.

[0012] Preferably, the outlet is connected to the wastewater treatment system.

[0013] Preferably, the outlet temperature of the ether-water mixture in the ether-water mixture preheater is in the range of 100-130°C.

[0014] Preferably, the pressure of the ether-water mixture at the outlet of the ether-water mixture preheater is 0.08-0.3 MPaG.

[0015] Preferably, a condenser is connected between the membrane dehydrator and the dimethyl ether mixture tank.

[0016] Preferably, the outlet of the dimethyl ether mixture tank is connected in sequence to a dimethyl ether mixture feed pump, a dimethyl ether mixture preheater, and a dimethyl ether separation system.

[0017] In summary, this utility model has the following beneficial effects:

[0018] Through technical modifications, this device dehydrates the ether-water azeotrope through a molecular sieve membrane, eliminating the need for benzene as an extractant and reducing the difficulty of wastewater treatment. Furthermore, the water content in the dehydrated methyl ether can be reduced to below 0.02%, effectively improving the quality of monomethyl ether and isomethyl ether. Attached Figure Description

[0019] Figure 1 This is a schematic diagram showing the connection relationships between the various components within the device;

[0020] Figure 2 This is a schematic diagram of a membrane dewatering device.

[0021] In the diagram, 1 is the ether-water mixture tank; 2 is the ether-water mixture feed pump; 3 is the ether-water mixture preheater; 4 is the membrane dehydrator; 41 is the shell; 42 is the membrane tube; 43 is the outlet; 44 is the condenser; 5 is the dimethyl ether mixture tank; 6 is the dimethyl ether mixture feed pump; and 7 is the dimethyl ether mixture preheater. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings.

[0023] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

[0024] Example:

[0025] like Figure 1 and Figure 2 As shown, this device includes an ether-water mixture tank 1, an ether-water mixture feed pump 2, an ether-water mixture preheater 3, a membrane dehydrator 4, a dimethyl ether mixture tank 5, a dimethyl ether mixture feed pump 6, and a dimethyl ether mixture preheater 7, which are connected in sequence.

[0026] The ether-water mixture in ether-water mixture tank 1 is a gaseous material from the top of the ether dehydration tower in the previous process, with a temperature above 110℃, mainly composed of ethers and water. The ether-water mixture in tank 1 is conveyed to ether-water mixture preheater 3 by ether-water mixture feed pump 2. Ether-water mixture preheater 3 is used to preheat the ether-water mixture before it enters membrane dehydrator 4, ensuring that the pressure of the ether-water mixture entering membrane dehydrator 4 is 0.08-0.3 MPaG and the temperature is 100-130℃, maintaining a gaseous state before entering membrane dehydrator 4.

[0027] The membrane dewatering device 4 includes a housing 41 and membrane tubes 42. Each membrane tube 42 has a molecular sieve membrane and is evacuated internally. Multiple membrane tubes 42 are arranged inside the housing 41 and are connected to a common outlet 43. A gaseous ether-water mixture enters the housing 41. As it passes through the membrane tubes 42, water can enter from the outside of the membrane tubes 42 and flow out of the membrane dewatering device 4. After collection, the water enters the wastewater treatment system through the outlet 43.

[0028] Methyl ether flows through the outside of membrane tube 42, collects, and exits the membrane dehydrator 4 through the outlet of shell 41. At this point, the water content in the methyl ether mixture is <0.02℃. A condenser 44 is installed between the membrane dehydrator 4 and the methyl ether mixture tank 5. After passing through the condenser 44, the methyl ether mixture is cooled to 90-100℃ and becomes liquid before entering the methyl ether mixture tank 5. Then, under the action of the methyl ether mixture feed pump 6, it passes through the methyl ether mixture preheater 7 and is transported to the methyl ether separation system.

Claims

1. A device for dehydrating dimethyl ether, a byproduct of propylene oxide production via the HPPO process, characterized in that, The system includes an ether-water mixture tank (1), an ether-water mixture feed pump (2), an ether-water mixture preheater (3), and a membrane dewatering device (4) connected in sequence. The membrane dewatering device (4) includes a shell (41) and a membrane tube (42). The inlet of the shell (41) is connected to the ether-water mixture preheater (3), and the outlet of the shell (41) is connected to the dimethyl ether mixture tank (5). The membrane tube (42) is equipped with a molecular sieve membrane that only supplies water. The membrane tube (42) is connected to an outlet (43).

2. The device for dehydrating dimethyl ether, a byproduct of propylene oxide production via the HPPO method, as described in claim 1, is characterized in that... There are multiple membrane tubes (42), and multiple membrane tubes (42) are connected to the same outlet (43).

3. The device for dehydrating dimethyl ether, a byproduct of propylene oxide production via the HPPO method, as described in claim 1, is characterized in that... The membrane tube (42) is in a vacuum state.

4. A device for dehydrating dimethyl ether, a byproduct of propylene oxide production via the HPPO method, as described in claim 1, characterized in that... The outlet (43) is connected to the wastewater treatment system.

5. A device for dehydrating dimethyl ether, a byproduct of propylene oxide production via the HPPO method, as described in claim 1, characterized in that... The outlet temperature range of the ether-water mixture in the ether-water mixture preheater (3) is 100-130℃.

6. A device for dehydrating dimethyl ether, a byproduct of propylene oxide production via the HPPO method, as described in claim 1, characterized in that... The outlet pressure of the ether-water mixture preheater (3) is 0.08-0.3 MPaG.

7. A device for dehydrating dimethyl ether, a byproduct of propylene oxide production via the HPPO method, as described in claim 1, characterized in that... A condenser (44) is connected between the membrane dehydrator (4) and the dimethyl ether mixture tank (5).

8. A device for dehydrating dimethyl ether, a byproduct of propylene oxide production via the HPPO method, as described in claim 1, characterized in that... The outlet of the dimethyl ether mixture tank (5) is connected in sequence to the dimethyl ether mixture feed pump (6), the dimethyl ether mixture preheater (7), and the dimethyl ether separation system.

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