Device for producing isoamylene by cracking tert-amyl methyl ether

Abstract

The utility model discloses a device for producing isopentene by cracking tert-amyl methyl ether. The device comprises a multiphase mixer, an oil-water separator, a water scrubber, an isomerization reactor, an isoamylene refining tower and a methanol recovery tower, the multiphase mixer performs multiphase mixing on raw materials and water, and an outlet of the multiphase mixer is connected with an inlet of the oil-water separator; the water phase is input into a methanol recovery tower, and the oil phase crude isopentene is input into a water scrubber; methanol in the oil-phase crude isopentene is extracted into water by the water washing tower, a tower bottom material is conveyed to a methanol recovery tower, and the washed oil-phase crude isopentene enters an isomerization reactor; an outlet of the isomerization reactor is connected with an inlet of the isopentene refining tower, and the isopentene refining tower is used for refining a product; and the methanol recovery tower is used for separating methanol from water. Most methanol in a reaction product is separated out through oil-water separation, and the use amount of subsequent washing water is reduced, so that the treatment capacity of the methanol recovery tower is reduced, and the purpose of reducing the operation cost of the device is achieved.

Description

Technical Field

[0001] This utility model relates to the field of isopentenyl ether production technology, and in particular to an apparatus for producing isopentenyl ether by cracking. Background Art

[0002] Isoprene is an important chemical raw material, with three isomers: 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene. Commercially available isoprene is a mixture of 2-methyl-1-butene and 2-methyl-2-butene. Isoprene can be used to produce pinacolone, which in turn produces highly effective triazole fungicides, plant growth regulators, herbicides, and other pesticides, as well as antioxidants such as 2,4-di-tert-amylphenol. High-quality isoprene can also be used in the production of galena fragrance.

[0003] There are several production routes for isopentene, including the crude isopentene method, the isopentane method, the isopentanol method, and the n-pentene method. The crude isopentene method utilizes isopentene from the raffinate C5 carbon residue and methanol to synthesize methyl tert-amyl ether. The methyl tert-amyl ether is then cracked to obtain methanol and isopentene. The isopentene is then concentrated to obtain high-purity isopentene. The isopentane method utilizes isopentane and n-pentane from the etherified C5 carbon residue. The n-pentane in the raw material is isomerized to isopentane, and then purified by dehydrogenation to obtain high-purity isopentene. The isopentanol method uses isopentanol as a raw material, undergoes a dehydration reaction to obtain a C5-rich mixed gas, and then undergoes isomerization and distillation to obtain the isopentene product. The n-pentene method converts n-pentene to isopentene through an isomerization reaction. Currently, the crude isopentene method is the main industrial method for producing isopentene.

[0004] The crude isopentenene process involves washing a mixture of C5 hydrocarbons rich in isopentenene with water, followed by selective hydrogenation to remove dienes. The pretreated feedstock is then mixed with methanol for etherification. The isopentenene in the feedstock reacts with methanol to form methyl tert-amyl ether, which is then washed and purified. The purified methyl tert-amyl ether undergoes etherification, washing, isomerization, and isopentenene purification to obtain the required isopentenene product. Nearly one-third of the energy consumption in this entire process comes from methanol recovery.

[0005] Patent CN1148337C discloses a method for preparing isopentenene with high 2-methyl-2-butene content from methyl tert-amyl ether. The method involves passing methyl tert-amyl ether through a catalyst bed in the gas phase for etherification, washing the reactants with water to remove methanol, and obtaining isopentenene material containing 2-methyl-1-butene and 2-methyl-2-butene. Subsequently, through an isomerization reaction, 2-methyl-1-butene is converted to 2-methyl-2-butene, yielding an isopentenene product containing a large amount of 2-methyl-2-butene. While this method discloses a process route for preparing isopentenene from methyl tert-amyl ether, it suffers from high energy consumption.

[0006] Patent CN101723777B discloses a method for preparing isopentenene using methyl tert-amyl ether as a raw material. The process involves the etherification of methyl tert-amyl ether in the gas phase through a catalyst bed. Methanol is removed from the etherification product to obtain crude isopentenene. Water is added to the crude isopentenene, which is then passed through a fixed-bed catalyst bed composed of sulfonic acid-based cation exchange resin for isomerization, converting 2-methyl-1-butene in the crude isopentenene to 2-methyl-2-butene. While the disclosed method suppresses the formation of dimers during the isopentenene isomerization reaction, the energy consumption of the process is not reduced.

[0007] Patent CN109651057A discloses a method for preparing isopentene. Based on the different polymerization activities of dienes and monoolefins, crude isopentene is polymerized in the liquid phase through a catalyst bed, causing the dienes in the crude isopentene to polymerize, thereby reducing the diene content in the crude isopentene raw material before etherification. High-purity isopentene is then obtained through etherification, distillation, etherification, and further distillation. While the disclosed method reduces the limitations on raw materials during etherification by pretreating them, it does not improve subsequent processes.

[0008] Based on the above description, the existing process for producing isopentenene via the cracking of methyl tert-amyl ether suffers from high energy consumption. Therefore, to address this issue, a new energy-saving process for producing isopentenene via the cracking of methyl tert-amyl ether is proposed. Utility Model Content

[0009] To reduce energy consumption in the process of producing isopentenene by cracking methyl tert-amyl ether, this invention provides an apparatus for producing isopentenene by cracking methyl tert-amyl ether.

[0010] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0011] An apparatus for producing isopentenene by cracking methyl tert-amyl ether, the apparatus comprising a multiphase mixer, an oil-water separator, a water washing tower, an isomerization reactor, an isopentenene purification tower, and a methanol recovery tower;

[0012] The multiphase mixer is used to multiphase mix the cracking reaction product of the raw material methyl tert-amyl ether with water.

[0013] The outlet of the multiphase mixer is connected to the inlet of the oil-water separator; the oil-water separator has two outlets, one of which is connected to the methanol recovery tower for feeding the aqueous phase separated by the oil-water separator into the methanol recovery tower, and the other outlet is connected to the water washing tower for feeding the crude isopentenyl oil phase separated by the oil-water separator into the water washing tower.

[0014] The water washing tower is used to extract methanol from crude isopentenyl oil phase into water. The bottom material of the tower is transported to the methanol recovery tower. The crude isopentenyl oil phase after water washing enters the isomerization reactor from the top of the water washing tower to convert 2-methyl-1-butene into 2-methyl-2-butene.

[0015] The outlet of the isomerization reactor is connected to the inlet of the isopentene refining tower, which refines the product and produces qualified isopentene product from the side stream.

[0016] The methanol recovery tower is used to separate methanol and water, with the methanol at the top of the tower being reused and the fresh water obtained at the bottom of the tower being reused.

[0017] According to the apparatus of this invention, the mass flow rate of water entering the multiphase mixer is 15%-150% of the mass flow rate of methanol in the methyl tert-amyl ether cracking reaction product, preferably 25%-100%, and more preferably 25%-50%.

[0018] According to the device described in this utility model, the multiphase mixer is a static mixer.

[0019] According to the device described in this utility model, the oil-water separator is an oil-water separation tank, and the oil-water separation tank is a storage tank with a baffle and an oil-water separation function.

[0020] According to the apparatus of this utility model, the upper part of the water washing tower has a first inlet for water to enter the water washing tower; the lower part of the water washing tower has a second inlet for the crude isopentene in the oil phase to enter the water washing tower and come into countercurrent contact with the water from the upper part of the water washing tower. The crude isopentene in the oil phase enters the water washing tower from the lower part, and the crude isopentene in the oil phase comes into countercurrent contact with the water from the upper part of the water washing tower, thereby extracting methanol from the crude isopentene in the oil phase into the water, which is then collected from the bottom of the water washing tower.

[0021] According to the device described in this utility model, the theoretical number of plates in the methanol recovery tower is 20 to 45.

[0022] According to the apparatus described in this utility model, the methanol mass concentration of the methanol aqueous solution in the methanol recovery tower is 25%-62%, preferably 36.8%-60.7%, and more preferably 45.6%-60.7%.

[0023] According to the apparatus of this utility model, the mass flow rate of the water from the upper part of the water washing tower is 150%-1500% of the mass flow rate of methanol in the crude isopentene of the oil phase, preferably 494%-1500%, and more preferably 494%-1200%.

[0024] The crude isopentenyl isoprene, after being washed with water, enters the isomerization reactor from the top of the water washing tower to convert 2-methyl-1-butene into 2-methyl-2-butene. Then, it enters the isopentenyl refining tower for product refining, and qualified isopentenyl product is produced from the side stream. The mass fraction of isopentenyl in the product is greater than 99.9%. The bottom material of the water washing tower enters the methanol recovery tower.

[0025] The methanol recovery tower is used to separate methanol and water, with the methanol at the top of the tower being reused and the fresh water obtained at the bottom of the tower being reused.

[0026] According to the apparatus of this invention, the mixing process is preferably carried out in a static mixer to ensure good dispersion and thorough mixing of different fluids.

[0027] According to the apparatus of this utility model, the methyl tert-amyl ether pyrolysis reaction product comprises isopentenene, methanol and methyl tert-amyl ether, wherein the isopentenene content in the reaction product is 60wt% to 69wt% and the methanol content is 25wt% to 31.4wt%.

[0028] As a further improvement of this utility model, the methanol recovery tower has a theoretical number of plates of 20 to 45, a reflux ratio of 1 to 6, an operating pressure of 100 kPa to 250 kPa, a top operating temperature of 65°C to 90°C, and a bottom operating temperature of 102°C to 128°C. Preferably, the methanol recovery tower has a theoretical number of plates of 25 to 35, a reflux ratio of 2 to 4, an operating pressure of 110 kPa to 180 kPa, a top operating temperature of 66.5°C to 79°C, and a bottom operating temperature of 104°C to 117°C.

[0029] As a further improvement of this utility model, the oil-water separator is provided with a heating or cooling device on the outside to regulate the temperature inside the tank and optimize the oil-water separation effect.

[0030] As a further improvement of this utility model, the water washing tower is also equipped with a liquid level control system to monitor and adjust the liquid level in the water washing tower to ensure the stable operation of the water washing process.

[0031] As a further improvement of this utility model, the water washing tower is also provided with multiple layers of packing material to enhance the contact area and extraction efficiency between water and crude isopentene in the oil phase.

[0032] As a further improvement of this utility model, the apparatus for producing isopentenene by cracking methyl tert-amyl ether also includes an automatic control system for monitoring and controlling the operating parameters of the multiphase mixer, oil-water separator, water washing tower, isomerization reactor, isopentenene refining tower and methanol recovery tower, such as temperature, pressure, flow rate and liquid level, so as to realize the automation and intelligence of the production process.

[0033] Compared with the prior art, the beneficial effects of this utility model are as follows: by adding a multiphase mixer to inject a small amount of water into the etherification product, the different fluids are well dispersed and fully mixed. Then, the mixture enters an oil-water separator with oil-water separation function, so that most of the methanol and crude isopentene in the etherification product are separated and removed in the oil-water separator, reducing the processing load of the subsequent water washing tower. At the same time, it reduces the amount of washing water used in the water washing tower and increases the concentration of methanol in the methanol-water solution entering the methanol recovery tower, thereby reducing the processing capacity and separation difficulty of the methanol recovery tower, reducing the steam load used by the reboiler of the methanol recovery tower, and achieving the goal of reducing the operating cost of the equipment. Attached Figure Description

[0034] Figure 1 This is a diagram of an apparatus for producing isopentenene by cracking methyl tert-amyl ether according to this invention.

[0035] Figure 2 This is a diagram of an existing apparatus for the cracking of methyl tert-amyl ether to produce isopentenene. DETAILED DESCRIPTION

[0036] The technical solution of this utility model will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments improved or adjusted by those skilled in the art are within the protection scope of this utility model. Since this utility model mainly focuses on the improvement of the methanol removal process by water washing and the operation of the methanol recovery tower, while other parts are basically the same as the prior art, the embodiments will focus on listing the experimental data of methanol removal by water washing and the methanol recovery tower.

[0037] The apparatus of the embodiment is as follows Figure 1As shown, an apparatus for producing isopentene by cracking methyl tert-amyl ether includes a static mixer 1, an oil-water separator 2, a water washing tower 3, an isomerization reactor 4, an isopentene purification tower 5, and a methanol recovery tower 6. The static mixer 1 is used to perform multiphase mixing of the cracking reaction product of the raw material methyl tert-amyl ether and water; the outlet of the static mixer 1 is connected to the inlet of the oil-water separator 2; the oil-water separator 2 is a storage tank with baffles and oil-water separation function, having two outlets, one of which is connected to the methanol recovery tower 6 for inputting the aqueous phase separated from the oil-water separator into the methanol recovery tower, and the other outlet is connected to the water washing tower 3 for inputting the crude isopentene oil phase separated from the oil-water separator into the water washing tower; the water washing tower 3 is used to... Methanol in the crude isopentenyl isolene is extracted into water, and the bottom material is conveyed to methanol recovery tower 6. After being washed with water, the crude isopentenyl isolene enters the isomerization reactor 4 from the top of the washing tower, converting 2-methyl-1-butene into 2-methyl-2-butene. The outlet of the isomerization reactor 4 is connected to the inlet of the isopentenyl refining tower 5, which refines the product and produces qualified isopentenyl product from the side stream. The methanol recovery tower 6 is used to separate methanol and water, with the methanol at the top of the tower being reused and the fresh water at the bottom being reused.

[0038] Specifically, the method for producing isopentenene using the above-mentioned apparatus includes the following steps: the methyl tert-amyl ether cracking reaction product (hereinafter referred to as etherification product) enters a static mixer 1 and is mixed with a certain amount of water to obtain a mixture; the mixture enters an oil-water separator 2 to separate the aqueous phase and the oil phase. The oil-water separator 2 is a storage tank with a baffle and an oil-water separation function. Part of the methanol in the mixture enters the aqueous phase; the aqueous phase enters the methanol recovery tower 6; the crude isopentenene in the oil phase separated from the oil-water separator 2 enters the water washing tower 3 from the bottom. The crude isopentenene in the oil phase comes into countercurrent contact with water from the top of the water washing tower 3, extracting the methanol in the crude isopentenene in the oil phase into the water, and is collected from the bottom of the water washing tower 3. The crude isopentenyl isoprene, after being washed with water, enters the isomerization reactor 4 from the top of the water washing tower 3, where 2-methyl-1-butene is converted to 2-methyl-2-butene. Then, it enters the isopentenyl refining tower 5 for product refining, and qualified isopentenyl product is produced from the side stream. The mass fraction of isopentenyl in the product is greater than 99.9%. The bottom material of the water washing tower 3 enters the methanol recovery tower 6. The methanol recovery tower 6 is used to separate methanol and water. The methanol at the top of the tower is reused, and the fresh water obtained at the bottom of the tower is reused.

[0039] Comparative devices such as Figure 2As shown, an apparatus for producing isopentene by cracking methyl tert-amyl ether includes a water washing tower 3, an isomerization reactor 4, an isopentene purification tower 5, and a methanol recovery tower 6. The comparative example differs from the embodiment in that it does not use a static mixer, does not employ an oil-water separator, and lacks oil-water separation functionality. The method for producing isopentenene using a comparative apparatus includes the following steps: the etherification product enters a water washing tower from the bottom and comes into countercurrent contact with water from the top of the water washing tower 3, extracting methanol from the etherification product into the water, and collecting the methanol-water solution from the bottom of the water washing tower 3; the etherification product after washing enters an isomerization reactor 4 from the top of the water washing tower 3, converting 2-methyl-1-butene into 2-methyl-2-butene, and then enters an isopentenene purification tower 5 for product purification, producing qualified isopentenene product from the side stream, wherein the mass fraction of isopentenene in the product is greater than 99.9%; the material from the bottom of the water washing tower 3 enters a methanol recovery tower 6; the methanol recovery tower 6 is used to separate methanol and water, with the methanol at the top of the tower being reused and the fresh water obtained at the bottom of the tower being reused.

[0040] In the comparative examples and embodiments, the parameters of the isomerization reactor, isopentenene refining tower, and methanol recovery tower were set the same. The relevant parameters of the methanol recovery tower were: 30 theoretical plates, reflux ratio of 3, operating pressure of 120 kPa, top temperature of 68.1-68.3℃, and bottom temperature of 104.7-104.9℃.

[0041] Both the examples and comparative examples use the etherification products from a certain factory as examples. The composition of the etherification products is shown in Table 1 below, and the methanol mass flow rate is 1053.352 kg / h.

[0042] Table 1

[0043]

[0044] Table 2 shows the static mixer water injection rate, water washing tower inlet water rate, methanol content in the methanol recovery tower, and methanol recovery tower results.

[0045] Table 2

[0046]

[0047]

[0048] Compared with the traditional methyl tert-amyl ether cracking to produce isopentene, this invention achieves the same separation index with the same processing capacity, and reduces the energy consumption of the methanol recovery tower by nearly 30%.

[0049] This embodiment is merely exemplary and not all embodiments. All other embodiments modified or adjusted by those skilled in the art are within the protection scope of this utility model.

Claims

1. An apparatus for producing isopentenene by cracking methyl tert-amyl ether, characterized in that, The apparatus includes a multiphase mixer, an oil-water separator, a water washing tower, an isomerization reactor, an isopentenene refining tower, and a methanol recovery tower; The multiphase mixer is used to multiphase mix the cracking reaction product of raw material methyl tert-amyl ether with water; the outlet of the multiphase mixer is connected to the inlet of the oil-water separator; the oil-water separator has two outlets, one of which is connected to the methanol recovery tower for feeding the aqueous phase separated by the oil-water separator into the methanol recovery tower, and the other outlet is connected to the water washing tower for feeding the crude isopentenyl oil phase separated by the oil-water separator into the water washing tower. The water washing tower is used to extract methanol from crude isopentenyl oil phase into water. The bottom material of the tower is transported to the methanol recovery tower. The crude isopentenyl oil phase after water washing enters the isomerization reactor from the top of the water washing tower to convert 2-methyl-1-butene into 2-methyl-2-butene. The outlet of the isomerization reactor is connected to the inlet of the isopentenene refining tower. The isopentenene refining tower is used to refine the product and produce qualified isopentenene product from the side stream. The methanol recovery tower is used to separate methanol and water, with the methanol at the top of the tower being reused and the fresh water obtained at the bottom of the tower being reused.

2. The apparatus according to claim 1, characterized in that, The multiphase mixer is a static mixer.

3. The apparatus according to claim 1, characterized in that, The oil-water separator is an oil-water separation tank, which is a storage tank with baffles and oil-water separation function.

4. The apparatus according to claim 1, characterized in that, The upper part of the water washing tower has a first inlet for water to enter the water washing tower; the lower part of the water washing tower has a second inlet for the crude isopentene in the oil phase to enter the water washing tower and come into countercurrent contact with the water from the upper part of the water washing tower.

5. The apparatus according to claim 1, characterized in that, The theoretical number of plates in the methanol recovery tower is 20 to 45.

6. The apparatus according to claim 5, characterized in that, The theoretical number of plates in the methanol recovery tower is 25 to 35.

7. The apparatus according to claim 1, characterized in that, The oil-water separator is equipped with an external heating or cooling device to regulate the temperature inside the tank.

8. The apparatus according to claim 1, characterized in that, The washing tower is also equipped with a liquid level control system to monitor and adjust the liquid level inside the washing tower.

9. The apparatus according to claim 1, characterized in that, The water washing tower also has multiple layers of packing material inside.

10. The apparatus according to claim 1, characterized in that, The device also includes an automatic control system for monitoring and controlling the operating parameters of the multiphase mixer, oil-water separator, water washing tower, isomerization reactor, isopentenyl refining tower, and methanol recovery tower.

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