MTBE production plant
By optimizing the process design and equipment connection of the MTBE production unit, the problems of complex processes and low recovery rates in the existing technology have been solved, thereby improving the MTBE yield and the flexibility of product switching, and reducing energy consumption and resource waste.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WISON ENG
- Filing Date
- 2025-06-27
- Publication Date
- 2026-07-24
AI Technical Summary
Existing MTBE production facilities have complex processes, low MTBE recovery rates, and cannot flexibly switch between blending and chemical products.
An MTBE production unit was designed, comprising an etherification reactor, a catalytic distillation column, a refining column, and multiple auxiliary devices. By returning the light components at the top of the catalytic distillation column to the catalytic reaction and then refining them, a blended MTBE outflow branch was set up, and the connection between the catalytic distillation column and the refining column was established to achieve free product switching. At the same time, a methanol recovery system was used to reduce nitrogen usage and optimize thermal energy utilization.
It improved the yield of MTBE, simplified the production process, enabled the free switching between blending and chemical products, reduced energy consumption and resource waste, and improved the economic efficiency of the plant.
Smart Images
Figure CN224541696U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of chemical technology and relates to an MTBE production device. Background Technology
[0002] MTBE, or methyl tert-butyl ether, is an important basic chemical raw material. It is an ideal blending component for increasing the octane rating and adjusting the oxygen content of automobiles, and is also crucial for producing high-purity isobutylene for butyl rubber. Based on its application, it is commonly classified into two types: "fuel-blending MTBE" and "chemical-grade MTBE." Fuel-blending MTBE has lower purity and is mainly used as a gasoline additive to increase the octane rating of gasoline. Chemical-grade MTBE has higher purity and is mainly used in the cracking of feedstocks to produce high-purity isobutylene, which is used as a chemical monomer.
[0003] The current domestic production process for MTBE mainly includes: ① Reacting mixed C4 and methanol in an etherification reactor to obtain a reaction solution. The mixed C4 mainly contains isobutene, butene-1, cis-2-butene, trans-2-butene, n-butane, isobutane, 1,3-butadiene, etc. The mixed C4 comes from raffinate C4, catalytic cracking C4, MTO C4, etc.; ② The reaction solution is then further reacted and distilled in a catalytic distillation column to obtain the bottom liquid (oil-blended MTBE) and the etherified C4 at the top of the column; ③ The etherified C4 is washed with water to recover methanol.
[0004] Patent CN109384653 introduces the crude product from the bottom of a catalytic distillation column into a distillation column for further purification of MTBE. The product at the top of the distillation column undergoes adsorption purification to ensure it meets the quality requirements for chemical-grade MTBE. This process is complex, requiring an additional purification step to obtain chemical-grade MTBE, and the stream is not effectively utilized. Patent CN113943213A adds a distillation separation column between the reactor and the catalytic distillation column to obtain high-purity MTBE. However, this equipment is complex and cannot switch between blended and chemical-grade products. Utility Model Content
[0005] This invention addresses the technical problems of complex process flow and low MTBE recovery rate in existing MTBE production equipment, and aims to provide an MTBE production equipment.
[0006] The MTBE production apparatus of this utility model includes:
[0007] At least one etherification reactor, said etherification reactor having an inlet and an outlet;
[0008] The catalytic distillation column is connected to the etherification reactor outlet and the etherified material inlet of the catalytic distillation column, and the bottom outlet of the catalytic distillation column is connected to an oil-blending MTBE outflow branch.
[0009] The purification column, wherein the bottom outlet of the catalytic distillation column is also connected to the inlet of the purification column, and the side of the purification column has a chemical MTBE outflow branch, wherein the light component outlet at the top of the purification column is connected to the ether post-material inlet of the catalytic distillation column.
[0010] Preferably, the MTBE production apparatus further includes:
[0011] The methanol feedstock tank has a methanol inlet and a gas replenishment port. The first branch of the methanol feedstock tank outlet is combined with the mixed C4 inlet pipe and then connected to the feed inlet of the etherification reactor.
[0012] A catalytic distillation column reflux tank, wherein a first outflow pipeline is provided between the top outlet of the catalytic distillation column and the inlet of the catalytic distillation column reflux tank, and the bottom of the catalytic distillation column reflux tank has a catalytic distillation outflow branch and a catalytic distillation reflux branch that returns to the upper part of the catalytic distillation column;
[0013] The C4 water washing tower has a catalytic distillation outlet branch of the reflux tank of the catalytic distillation tower connected to the C4 inlet of the C4 water washing tower, and the top of the C4 water washing tower has a C4 outlet after water washing.
[0014] The methanol recovery tower has its bottom outlet connected to the inlet of the C4 water washing tower, and its bottom water outlet connected to the water inlet of the C4 water washing tower.
[0015] The methanol recovery tower reflux tank has the following configuration: the top outlet of the methanol recovery tower is connected to the inlet of the methanol recovery tower reflux tank; the methanol recovery reflux branch at the bottom of the methanol recovery tower reflux tank is connected to the upper part of the methanol recovery tower; the methanol recovery collection branch at the bottom of the methanol recovery tower reflux tank is connected to the methanol feedstock tank; and the top of the methanol recovery tower reflux tank is connected to the gas phase pressure replenishment of the methanol feedstock tank.
[0016] Preferably, the top of the catalytic distillation column is also provided with a second collection pipeline connected in parallel with the first collection pipeline, and the second collection pipeline is provided with an open heat pump system.
[0017] Preferably, the MTBE production unit further includes a purification column condenser and a purification column pressurization pump arranged sequentially between the light component outlet at the top of the purification column and the ether post-material inlet of the catalytic distillation column, and the bottom of the purification column has a heavy component outlet.
[0018] Preferably,
[0019] The at least one etherification reactor specifically includes a first-stage etherification reactor, a second-stage etherification reactor, and a third-stage etherification reactor, which are connected in series in a ring, with the outlet of the current etherification reactor and the inlet of the next etherification reactor being openable or closable. The first branch of the methanol feedstock tank outlet is merged with the mixed C4 inlet pipe and then connected to the inlets of the first-stage, second-stage, and third-stage etherification reactors in an openable or closable manner. The outlets of the first-stage, second-stage, and third-stage etherification reactors are also connected to the post-etherification material inlet of the catalytic distillation column in an openable or closable manner. Preferably, the first branch of the methanol feedstock tank outlet is merged with the mixed C4 inlet pipe and then connected to a feedstock C4 preheater for heat exchange before being connected to the inlets of the first-stage, second-stage, and third-stage etherification reactors in an openable or closable manner.
[0020] Preferably,
[0021] The outlets of the first-stage etherification reactor, the second-stage etherification reactor, and the third-stage etherification reactor are respectively connected to the inlet of their own etherification reactor by a first-stage cooler, a second-stage cooler, and a third-stage cooler for heat exchange.
[0022] The outlet of the first-stage etherification reactor and the inlet of the second-stage etherification reactor share a first branch; the outlet of the second-stage etherification reactor and the inlet of the third-stage etherification reactor share a second branch; and the outlet of the third-stage etherification reactor and the inlet of the first-stage etherification reactor share a third branch, which can be connected in an openable or closable manner.
[0023] Preferably, the discharge ports of the first-stage etherification reactor, the second-stage etherification reactor, and the third-stage etherification reactor are respectively provided with a first-stage circulating pump, a second-stage circulating pump, and a third-stage circulating pump that can be turned on or off between their respective first-stage coolers and third-stage coolers.
[0024] Preferably, the second branch of the methanol feedstock tank outlet is also connected to the methanol inlet of the catalytic distillation column. More preferably, the second branch of the methanol feedstock tank outlet is first connected to the protection reactor and then connected to the methanol inlet of the catalytic distillation column.
[0025] Preferably,
[0026] A catalytic distillation column feed heat exchanger is provided between the bottom outlet pipe of the catalytic distillation column and the ether post-material inlet of the catalytic distillation column;
[0027] And / or, the inlet of the catalytic distillation column reflux tank is equipped with a catalytic distillation column condenser, and / or, the bottom of the catalytic distillation column reflux tank is equipped with a catalytic distillation column reflux pump;
[0028] And / or, a C4 cooler is provided on the catalytic distillation outflow branch before the C4 inlet;
[0029] And / or, the bottom water outlet of the methanol recovery tower is connected to the inlet of the methanol recovery tower by a methanol recovery tower feed heat exchanger.
[0030] And / or, a water circulation cooler and a water circulation pump are also installed sequentially between the inlet and outlet heat exchanger of the methanol recovery tower and the water inlet of the C4 water washing tower;
[0031] And / or, a methanol recovery tower cooler is provided between the top outlet of the methanol recovery tower and the inlet of the methanol recovery tower reflux tank. Preferably, a methanol recovery tower reflux pump is provided at the bottom of the methanol recovery tower reflux tank.
[0032] Preferably,
[0033] The open heat pump system includes a compressor and a heat exchanger. One end of the compressor is connected to the top outlet of the catalytic distillation column, and the other end of the compressor is connected to the heat exchanger for heat exchange and then connected to the inlet of the reflux tank of the catalytic distillation column. Preferably, the heat exchanger is a reboiler of the purification column.
[0034] Preferably,
[0035] The bottom of the catalytic distillation column is equipped with a catalytic distillation column reboiler;
[0036] The reboiler of the refining tower is equipped with a reboiler.
[0037] The methanol recovery tower bottom is equipped with a methanol recovery tower reboiler.
[0038] Another objective of this invention is to provide a method for producing MTBE, comprising the following steps:
[0039] Step S1: After mixing C4 and methanol, the mixture is fed into an etherification reactor for etherification reaction. After the ether is collected from the reactor bottom, the material is fed into a catalytic distillation column.
[0040] In step S2, the etherified material in the catalytic distillation column is mixed with methanol for further catalytic reaction and distillation. The gaseous C4 fraction is collected from the top of the catalytic distillation column, and a portion of the MTBE fraction is collected from the bottom of the catalytic distillation column as blended MTBE. The other portion of the MTBE fraction enters the purification column.
[0041] In step S3, another portion of the MTBE fraction is purified in a purification column. The light gaseous component collected from the top of the purification column is returned to the catalytic distillation column for cyclic catalytic reaction and distillation. The chemical-grade MTBE is directly collected from the side stream of the purification column, and the heavy component is collected from the bottom of the purification column.
[0042] Preferably,
[0043] Step S2 specifically includes: the gaseous C4 fraction taken from the top of the catalytic distillation column is cooled and then enters the reflux tank of the catalytic distillation column; a portion of the C4 fraction is refluxed into the catalytic distillation column, and another portion of the C4 fraction enters the C4 water washing column; preferably, the other portion of the C4 fraction is condensed and then enters the C4 water washing column.
[0044] The method further includes:
[0045] In step S4, the C4 fraction is washed with water in the C4 water washing tower. The separated washed C4 is collected from the top of the C4 water washing tower, and the methanol-water solution collected from the bottom of the C4 water washing tower enters the methanol recovery tower.
[0046] In step S5, the methanol-water solution in the methanol recovery tower is heated, and gaseous methanol is collected from the top of the methanol recovery tower. After condensation, it enters the methanol recovery tower reflux tank. A portion of the methanol is refluxed back into the methanol recovery tower, and the remaining methanol is returned to the etherification reactor and / or catalytic distillation tower for recycling. The recycled water from the bottom of the methanol recovery tower is recycled into the C4 water washing tower.
[0047] Preferably, in step S2, a portion of the gaseous C4 fraction collected from the top of the catalytic distillation column is separated, pressurized by a compressor, then exchanged with a heat exchanger and cooled before entering the reflux tank of the catalytic distillation column. Preferably, the heat exchanger is a reboiler of the refining column.
[0048] Preferably, in step S5, the remaining methanol in the methanol recovery tower reflux tank is returned to the methanol feed tank and then recycled into the etherification reactor and / or catalytic distillation tower; the gas phase of the methanol recovery tower reflux tank pressurizes the gas phase of the methanol feed tank.
[0049] Preferably, before step S1, the following is also present:
[0050] In step S0, the methanol feedstock stored in the methanol feedstock tank is mixed with the mixed C4 feedstock under pressure and enters the C4 feedstock preheater for preheating. The preheated mixed feedstock enters the etherification reactor. Preferably, the pressure is applied by nitrogen and / or the gas phase pressure of the methanol recovery tower reflux tank.
[0051] Preferably, in step S3, the light gaseous components collected from the top of the purification column are condensed by the purification column condenser and then transported by the purification column pressurization pump into the catalytic distillation column for cyclic catalytic reaction and distillation.
[0052] Preferably, in step S2, a portion of the methanol feedstock stored in the methanol feedstock tank enters the catalytic distillation column after passing through a protective reactor.
[0053] Preferably, in step S5, the recycled water from the bottom of the methanol recovery tower is circulated into the C4 water washing tower after exchanging heat with the methanol aqueous solution before entering the methanol recovery tower.
[0054] Preferably, step S1 specifically includes:
[0055] After mixing C4 and methanol, the mixture is sequentially fed into the first-stage etherification reactor, the second-stage etherification reactor, and the third-stage etherification reactor for etherification. The ether is collected from the outlet of the third-stage etherification reactor, and the material is then heat-exchanged in a catalytic distillation column heat exchanger before entering the catalytic distillation column. Alternatively, after mixing C4 and methanol, the mixture is sequentially fed into the second-stage etherification reactor, the second-stage etherification reactor, the third-stage etherification reactor, and the first-stage etherification reactor for etherification. The ether is collected from the outlet of the first-stage etherification reactor, and the material is then heat-exchanged in a catalytic distillation column inlet and outlet heat exchanger before entering the catalytic distillation column. Alternatively, after mixing C4 and methanol, the mixture is sequentially fed into the third-stage etherification reactor, the first-stage etherification reactor, and the second-stage etherification reactor for etherification. The ether is collected from the outlet of the second-stage etherification reactor, and the material is then heat-exchanged in a catalytic distillation column inlet and outlet heat exchanger before entering the catalytic distillation column.
[0056] After a portion of the ether is separated from the outlet of the first-stage etherification reactor, the material is cooled by a first-stage circulating pump and a first-stage cooler, and then mixed with the material at the inlet of the first-stage etherification reactor and controlled at temperature before entering the first-stage etherification reactor. After a portion of the ether is separated from the outlet of the second-stage etherification reactor, the material is cooled by a second-stage circulating pump and a second-stage cooler, and then mixed with the material at the inlet of the second-stage etherification reactor and controlled at temperature before entering the second-stage etherification reactor. After a portion of the ether is separated from the outlet of the third-stage etherification reactor, the material is cooled by a third-stage circulating pump and a third-stage cooler, and then mixed with the material at the inlet of the third-stage etherification reactor and controlled at temperature before entering the third-stage etherification reactor.
[0057] Preferably,
[0058] The catalytic distillation column is heated by a catalytic distillation column reboiler;
[0059] The refining column is heated using a reboiler.
[0060] The methanol recovery tower is heated by a methanol recovery tower reboiler.
[0061] The positive and progressive effects of this utility model are as follows:
[0062] 1) This invention greatly improves the yield of MTBE by returning the light component stream from the top of the purification column to the catalytic distillation column for cyclic catalytic reaction and distillation.
[0063] 2) This utility model provides an oil-blending MTBE outflow branch in the bottom of the catalytic distillation column and connects the bottom of the catalytic distillation column to the inlet of the refining column, thereby enabling free switching between the production of oil-blending MTBE products and chemical MTBE products.
[0064] 3) This utility model utilizes the gaseous methanol recovered by the methanol recovery tower to replace nitrogen in pressurizing the methanol feedstock tank, thereby reducing the use of nitrogen and further reducing the loss of C4 caused by nitrogen emissions, which is both environmentally friendly and effective.
[0065] 4) This utility model reduces the consumption of steam and circulating water in the purification tower by installing an open heat pump system at the top of the catalytic distillation tower. The gas phase at the top of the catalytic distillation tower is pressurized and heated, and then heat is transferred to the purification tower, thereby improving the economic efficiency of the device. Attached Figure Description
[0066] Figure 1 This is a schematic diagram of the MTBE production apparatus in Example 1;
[0067] Figure 2 This is a schematic diagram of the MTBE production apparatus in Example 2;
[0068] Figure 3 This is a schematic diagram of the MTBE production unit for Comparative Example 1. Detailed Implementation
[0069] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model.
[0070] like Figure 1 and Figure 2 As shown, the MTBE production apparatus of this utility model includes a methanol feedstock tank D4, a C4 feedstock preheater E1, at least one etherification reactor, a protection reactor R4, a catalytic distillation column T1, a purification column T2, a C4 water washing column T3, a methanol recovery column T4, a catalytic distillation column reflux tank D1, and a methanol recovery column reflux tank D3. Continuing as... Figure 1 and Figure 2As shown, methanol feedstock tank D4 has a methanol inlet and a gas replenishment port at one end, and a first branch and a second branch at the outlet at the other end. The first branch at the outlet of methanol feedstock tank D4 is merged with the mixed C4 inlet pipe and then connected to the feedstock C4 preheater E1 for heat exchange before being connected to the feed inlet of the etherification reactor. In this example, continuing as shown in the figure, at least one etherification reactor specifically includes a first-stage etherification reactor R1, a second-stage etherification reactor R2, and a third-stage etherification reactor R3. The first-stage, second-stage, and third-stage etherification reactors all have feed inlets and outlets. The first branch of the methanol feedstock tank D4 outlet is merged with the mixed C4 inlet pipe and then connected to the feedstock C4 preheater E1 for heat exchange before being connected to the feed inlet of the first-stage etherification reactor R1, the second-stage etherification reactor R2, or the third-stage etherification reactor R3. The first-stage etherification reactor R1, the second-stage etherification reactor R2, and the third-stage etherification reactor R3 are connected in series to form a ring. However, the outlet of each etherification reactor and the inlet of the next etherification reactor can be opened or closed according to the reaction sequence of the etherification reactors, thereby realizing the switching of the reaction sequence of the etherification reactors. Specifically, when the first branch of the methanol feedstock tank D4 outlet is merged with the mixed C4 inlet pipe and then connected to the feed inlet of the first-stage etherification reactor R1 via heat exchange in the feedstock C4 preheater E1, the first branch between the outlet of the first-stage etherification reactor R1 and the inlet of the second-stage etherification reactor R2, and the second branch between the outlet of the second-stage etherification reactor R2 and the inlet of the third-stage etherification reactor R3 are opened in sequence to achieve series connection, while the third branch between the outlet of the third-stage etherification reactor R3 and the inlet of the first-stage etherification reactor R1 is closed. At this time, only the outlet of the third-stage etherification reactor R3 is openly connected to the post-etherification material inlet of the catalytic distillation column T1. When the first branch of the methanol feedstock tank D4 outlet merges with the mixed C4 inlet pipe and is first connected to the feedstock C4 preheater E1 for heat exchange, and then connected to the feed inlet of the second-stage etherification reactor R2, the second branch between the outlet of the second-stage etherification reactor R2 and the feed inlet of the third-stage etherification reactor R3, and the third branch between the outlet of the third-stage etherification reactor R3 and the feed inlet of the first-stage etherification reactor R1 are opened in sequence to achieve series connection, while the first branch between the outlet of the first-stage etherification reactor R1 and the feed inlet of the second-stage etherification reactor R2 is closed. At this time, only the outlet of the first-stage etherification reactor R1 is opened to connect with the post-ether material inlet of the catalytic distillation column T1.When the first branch of the methanol feedstock tank D4 outlet merges with the mixed C4 inlet pipe and is first connected to the feedstock C4 preheater E1 for heat exchange before being connected to the inlet of the three-stage etherification reactor R3, the third branch between the outlet of the three-stage etherification reactor R3 and the inlet of the first-stage etherification reactor R1, and the first branch between the outlet of the first-stage etherification reactor R1 and the inlet of the second-stage etherification reactor R2, are sequentially opened to achieve series connection. The second branch between the outlet of the second-stage etherification reactor R2 and the inlet of the three-stage etherification reactor R3 is closed. At this time, only the outlet of the second-stage etherification reactor R2 is opened to connect with the post-etherification material inlet of the catalytic distillation column T1. Of course, it is also feasible to connect two etherification reactors in series according to the above rules when using only two etherification reactors, i.e., one stage and two stage etherification reactors, one stage and three stage etherification reactors, or two stage and three stage etherification reactors. In addition, the outlet of the first-stage etherification reactor R1 and the inlet of the first-stage etherification reactor R1 are connected in sequence by a first-stage circulating pump and a first-stage cooler E2, which can be turned on or off. Similarly, the vessel of the second-stage etherification reactor R2 and the inlet of the second-stage etherification reactor R2 are connected in sequence by a second-stage circulating pump and a second-stage cooler E3, which can be turned on or off. The same applies to the third-stage etherification reactor R3.
[0071] Continue as Figure 1 and Figure 2 As shown, a catalytic distillation column T1 is equipped with a feed heat exchanger E5 before the ether inlet, which exchanges heat with the material exiting the bottom of the column. The catalytic distillation column T1 also has a methanol inlet; the second branch of the methanol feedstock tank outlet D4 is first connected to the protection reactor R4 and then to the methanol inlet of the catalytic distillation column T1. The bottom of the catalytic distillation column T1 is equipped with a reboiler E7 for heating the process material inside the column. A first outflow pipe connects the top outlet of the catalytic distillation column T1 to the inlet of the catalytic distillation column reflux tank D1, and a catalytic distillation column condenser E6 is installed on this first outflow pipe. A catalytic distillation column reflux tank D1 is equipped with a catalytic distillation column reflux pump P1 at its bottom. Following pump P1, the bottom branch of the catalytic distillation column reflux tank D1 splits into a catalytic distillation outflow branch connected to the C4 inlet of the C4 water washing tower T3, and a catalytic distillation reflux branch returning to the upper part of the catalytic distillation column. In this example, a C4 cooler E10 is also installed on the catalytic distillation outflow branch before the C4 inlet of the C4 water washing tower T3. Figure 2As shown, the top of the catalytic distillation column T1 is also equipped with a second production pipeline connected in parallel with the first production pipeline. The second production pipeline is equipped with an open-loop heat pump system, which includes a compressor K1 and a heat exchanger. One end of the compressor K1 is connected to the top outlet of the catalytic distillation column T1, and the other end is connected to the heat exchanger for heat exchange, and then connected to the inlet of the catalytic distillation column reflux tank D1 via the catalytic distillation column condenser E6. Preferably, the heat exchanger is the reboiler E9 of the refining column. The bottom outlet of the catalytic distillation column T1 is connected to an oil-blending type MTBE production branch.
[0072] Continue as Figure 1 and Figure 2 As shown, the bottom outlet of the catalytic distillation column T1 is also connected to the inlet of the purification column T2. The bottom of the purification column T2 is equipped with a purification column reboiler E9 for heating the process materials inside the column. The light component outlet at the top of the purification column T2 is also connected to the ether post-effect material inlet of the catalytic distillation column T1. A purification column condenser E8 and a purification column booster pump P2 are sequentially installed between the light component outlet at the top of the purification column T2 and the ether post-effect material inlet of the catalytic distillation column T1. A chemical-grade MTBE outflow branch is provided on the side of the purification column T2, while the bottom has a heavy component outlet.
[0073] Continue as Figure 1 and Figure 2 As shown, the top of the C4 water washing tower T3 has a C4 outlet after water washing. The bottom outlet of the C4 water washing tower T3 is connected to the inlet of the methanol recovery tower T4. The bottom water outlet of the methanol recovery tower T4 is connected to the water inlet of the C4 water washing tower T3 after being connected in sequence through the methanol recovery tower feed heat exchanger E11, the water circulation cooler and the water circulation pump.
[0074] Continuing as shown in the figure, the methanol recovery tower T4 has a reboiler E13 at the bottom to heat the process materials inside the tower, and a methanol recovery tower reflux tank D3 at the top of the tower. In this example, the top outlet of the methanol recovery tower T4 is connected to the inlet of the methanol recovery tower reflux tank D3 via a methanol recovery tower cooler E12. The top of the methanol recovery tower reflux tank D3 is connected to the vapor phase pressure replenishment of the methanol feedstock tank D4, and the bottom of the methanol recovery tower reflux tank D3 is equipped with a methanol recovery tower reflux pump P3. Through this pump P3, the bottom of the methanol recovery tower reflux tank D3 is further divided into a methanol recovery reflux branch connected to the upper part of the methanol recovery tower T4 and a methanol recovery outlet branch connected to the methanol feedstock tank D4.
[0075] Another objective of this invention is to provide a method for producing MTBE.
[0076] like Figure 1As shown, isobutylene-containing C4 feedstock and methanol are mixed in a specific ratio (molecular ratio of alcohol to olefins is 1.0:1-1.5:1). After preheating by C4 feedstock preheater E1, the feedstock is selectively fed into one of three etherification reactors: a first-stage etherification reactor R1, a second-stage etherification reactor R2, or a third-stage etherification reactor R3 for etherification. When the preheated feedstock is fed into the first-stage etherification reactor R1, the reactor first catalyzes the reaction between isobutylene and methanol. The resulting etherified material flows from the outlet of the first-stage reactor R1 through a first branch into the second-stage etherification reactor R2 for further catalytic reaction. The material generated in the second-stage etherification reactor R2 then flows from its outlet through a second branch into the third-stage etherification reactor R3, and finally, the etherified material is collected from the outlet of the third-stage etherification reactor R3 and enters the catalytic distillation column T1. When the mixed raw materials are preheated and selected to enter the second-stage etherification reactor R2 through the feed inlet for etherification reaction, the second-stage etherification reactor R2 first catalyzes the reaction of isobutylene and methanol in the C4 raw materials. The ether produced by the reaction enters the third-stage etherification reactor R3 through the second branch from the discharge outlet of the second-stage etherification reactor R2 for further catalytic reaction. The material produced in the third-stage etherification reactor R3 then enters the first-stage etherification reactor R1 through its discharge outlet and the third branch, and finally the ether produced by the first-stage etherification reactor R1 is collected from the discharge outlet and enters the catalytic distillation column T1. When the preheated mixed feedstock enters the three-stage etherification reactor R3 through its inlet for etherification, the reactor first catalyzes the reaction of isobutylene and methanol in the C4 feedstock. The resulting etherified material then flows from the outlet of the three-stage reactor R3 through a third branch into the first-stage etherification reactor R1 for further catalytic reaction. The material generated in the first-stage reactor R1 then flows through its outlet and the first branch into the second-stage etherification reactor R2, and finally, the etherified material is collected from the outlet of the second-stage reactor R2 and enters the catalytic distillation column T1. This allows for flexible switching of the reaction sequence in the etherification reactors, significantly extending the lifespan of the catalysts in each reactor.
[0077] In addition, continue as Figure 1 and Figure 2As shown, since the etherification reaction is exothermic, the post-etherified material has a high temperature. If not controlled, this will increase side reactions and reduce the conversion rate of the etherification reaction. Therefore, a method can be adopted whereby a portion of the post-etherified material from the outlet of the first-stage etherification reactor R1 is separated, cooled by a first-stage cooler E2, and then mixed with the material from the inlet of the first-stage etherification reactor R1 at a controlled temperature before entering the first-stage etherification reactor R1. Similarly, a portion of the post-etherified material from the outlet of the second-stage etherification reactor R2 is separated, cooled by a second-stage cooler E3, and then mixed with the material from the inlet of the second-stage etherification reactor R2 at a controlled temperature before entering the second-stage etherification reactor R2. Similarly, a portion of the post-etherified material from the outlet of the third-stage etherification reactor R3 is separated, cooled by a third-stage cooler E4, and then mixed with the material from the inlet of the third-stage etherification reactor R3 at a controlled temperature before entering the third-stage etherification reactor R3. This method effectively regulates the feed temperature of the material in each etherification reactor and further controls the reaction temperature of each post-etherification reactor. Of course, the circulating rate of the material entering each etherification reactor can be adjusted according to the temperature of its own etherification reactor. When the temperature of the etherification reactor is low, its circulating rate is reduced, and vice versa. In addition, since most of the isobutylene is reacted in the first-stage etherification reactor R1, the catalyst lifetime in the first-stage etherification reactor R1 is relatively shorter than that in the following two etherification reactors. Therefore, in order to balance the catalyst lifetime in each etherification reactor, the reactor sequence can be switched and adjusted at any time.
[0078] Isobutylene in the C4 feedstock reacts with methanol under the action of a catalyst to produce MTBE. The post-etherification feed still contains a significant proportion of isobutylene, which is preheated by the inlet / outlet heat exchanger E5 before entering the catalytic distillation column T1. Part of the methanol in the methanol feedstock tank D4 also enters the catalytic distillation column T1 via the protective reactor R4, where it continues the etherification reaction with the post-etherification feed in T1 under the action of a catalyst. The vaporous C4 fraction at the top of the catalytic distillation column T1 is condensed by the catalytic distillation column condenser E6 and enters the catalytic distillation column reflux tank D1. A portion of this reflux is then used as reflux, while the remaining portion is cooled by the C4 fraction cooler E10 before going to the C4 water washing column T3. The C4 fraction and water are in countercurrent contact in the C4 water washing column T3, and the C4 fraction washed at the top of the column is discharged outside the boundary. The methanol and water-containing material from the bottom of the C4 water washing tower T3 enters the methanol recovery tower T. Methanol and water are separated. The top vaporous methanol is condensed by the methanol recovery tower cooler E12 and then enters the methanol recovery tower reflux tank D3. The residual vaporous phase at the top of the tank is returned to the methanol feedstock tank D4 to replace nitrogen for pressurization, thus reducing nitrogen usage and further minimizing C4 loss due to nitrogen emissions. The condensed liquid phase is pressurized by the methanol recovery tower reflux pump P3, with part of it returning to the methanol recovery tower T4 as reflux and the other part being sent to the methanol feedstock tank D4 for recycling. The water discharged from the bottom of the methanol recovery tower T4 exchanges heat with the feed material of the methanol recovery tower T4 in the methanol recovery tower inlet / outlet heat exchanger E11 and then returns to the C4 water washing tower T3 for recycling.
[0079] The bottom of catalytic distillation column T1 yields blended MTBE, a portion of which is collected as product, while the remainder enters purification column T2. The blended MTBE entering purification column T2 undergoes further distillation, removing heavy components such as polymers at the bottom. The overhead stream, containing a small amount of isobutylene, is condensed in purification column condenser E8 and then pressurized by purification column booster pump P2 before being recycled back to catalytic distillation column T1. The side stream from purification column T2 yields high-purity chemical-grade MTBE. On one hand, blended MTBE can be directly collected from the bottom of catalytic distillation column T1, or a portion of the blended MTBE can be purified in purification column T2 to produce chemical-grade MTBE, thus enabling free switching between the production volumes of blended MTBE and chemical-grade MTBE. On the other hand, the light component outlet at the top of the purification column T2 is connected to the ether post-material inlet of the catalytic distillation column T1. The gas stream at the top of the purification column T2 can be directly returned to the catalytic distillation column T1 for internal circulation catalytic reaction and distillation, which simplifies the purification process and improves the recovery rate of MTBE.
[0080] In another example, such as Figure 2 As shown, a portion of the vaporous C4 fraction from the top of catalytic distillation column T1 is sent to compressor K1 for pressurization and heating. This heat is then transferred to the reboiler E9 of the purification column, reducing the consumption of steam and circulating water in purification column T2 and improving the economic efficiency of the unit. The heat-exchanged C4 fraction, along with another portion of the vaporous C4 fraction directly collected from the top of catalytic distillation column T1 (which does not enter compressor K1), is sent to the condenser E6 of the catalytic distillation column for condensation. After condensation, a portion is refluxed, and the remaining portion is cooled by the C4 fraction cooler E10 before being sent to the C4 water washing column T3.
[0081] Example 1
[0082] according to Figure 1As shown, C4 feedstock at 40℃ and a flow rate of 62780 kg / hr and methanol at 25℃ and a flow rate of 15500 kg / hr are mixed and preheated to 40℃ by C4 feedstock preheater E1 before entering the first-stage etherification reactor R1. After the reaction, a material with a temperature of 57.2℃ is generated. Part of this material is pressurized by a first-stage circulation pump, cooled by a first-stage cooler E2, and then circulated back to the feed inlet of the first-stage etherification reactor R1, with the feed inlet temperature adjusted to not exceed 60℃. The other part of the material enters the second-stage etherification reactor R2. After the second-stage reaction, the material with a temperature of 56.5℃ is partly pressurized by a second-stage circulation pump, cooled by a second-stage cooler E3, and then circulated back to the feed inlet of the second-stage etherification reactor R2 to control the reaction temperature. The other part of the material enters the third-stage etherification reactor R3 to continue the reaction, so that the isobutylene conversion rate reaches over 93%. A portion of the material at 54.7℃ after the reaction in the three-stage etherification reactor R3 is pressurized by a three-stage circulating pump, cooled by a three-stage cooler E4, and then circulated back to the three-stage etherification reactor R3 to control the reactor temperature. The etherified C4 material after the reaction exchanges heat with the blended MTBE flowing from the bottom of the catalytic distillation column T1 via the feed heat exchanger E5, preheating it to 80℃ before entering the catalytic distillation column T1. Methanol at 25℃ and a flow rate of 200 kg / hr enters the upper section of the catalytic distillation column T1 via the protective reactor R4, where it undergoes an etherification reaction with a small amount of isobutylene under the action of a catalyst. Unreacted C4 and methanol at 57.6℃ and a flow rate of 93 t / h are collected from the top of the catalytic distillation column T1 and condensed; a portion is used as reflux, and the other portion is cooled to 40℃ by the C4 fraction cooler before going to the C4 water washing column T3. The blended MTBE product from the catalytic distillation column T1, with a bottom temperature of 129°C, is partially sent to the refining column T2 after heat exchange in the feed heat exchanger E5. The C4 fraction is countercurrently contacted with water in the C4 water washing column T3 at a pressure of 0.6 MPaG. After washing with water at 40°C (free of methanol) at the top of the column, the C4 fraction is discharged. The methanol and water-containing material from the bottom of the C4 water washing column T3, at a bottom temperature of 40°C, enters the methanol recovery column T4 at a pressure of 0.05 MPaG. Methanol and water are separated there. A portion of the top vaporized methanol, condensed to a liquid phase at 40°C, is returned to the methanol recovery column T4 as reflux, while another portion is sent to the methanol feedstock tank D4. The remaining vaporized methanol after condensation is used as a gaseous phase to pressurize the methanol feedstock tank D4. The water collected from the bottom of methanol recovery tower T4 at a temperature of 122°C exchanges heat with the inlet and outlet heat exchanger E11 of methanol recovery tower. After being further cooled to 40°C by the water circulation cooler, it is pressurized by the water circulation pump and enters the C4 water washing tower T3 for recycling.A portion of the blended MTBE stream from the bottom of catalytic distillation column T1 enters purification column T2 at a pressure of 0.008 MPaG. The bottom temperature of purification column T2 is 78°C. The overhead vapor stream, after removing polymers and other heavy components and containing a small amount of isobutylene, is condensed in purification column condenser E8 and then pressurized by purification column booster pump P2 before returning to catalytic distillation column T1. The high-purity chemical-grade MTBE product with a side stream temperature of 57.7°C enters the product tank. Compared to Comparative Example 1, the effects are shown in Table 1, reducing MTBE product loss and improving MTBE recovery rate.
[0083] Table 1. Results Analysis of Example 1 and Comparative Example 1
[0084]
[0085] Conclusion: The MTBE loss rates of the entire process in Example 1 and Comparative Example 1 were compared. As shown in Table 1, the MTBE loss rate was reduced by 97.16% by recycling the overhead stream from the purification column back to the catalytic distillation column. Furthermore, returning the vapor phase from the methanol recovery column reflux tank to the methanol feedstock tank instead of nitrogen pressurization saves nitrogen usage, is more environmentally friendly, and reduces C4 loss caused by nitrogen emissions.
[0086] Example 2
[0087] according to Figure 2 As shown in Example 1, based on the above-ground C4 fraction from the catalytic distillation column T1 (57.6℃, 93t / h flow rate) is separated into 77t / h and fed into compressor K1 for pressurization and heating to a superheated gas at 1.5MPaG and 104.7℃. This superheated gas is then fed into the reboiler E9 of the purification column for heat exchange. The unreacted C4 and methanol in the liquid phase (88.3℃ after heat exchange) then enter the catalytic distillation column condenser E6 along with another portion of the above-ground C4 fraction from the catalytic distillation column T1 that did not enter compressor K1. After condensation to 50℃, a portion of this condensate is used as reflux, and the remaining portion is cooled to 40℃ by the C4 fraction cooler before being sent to the C4 water washing column T3.
[0088] Table 2. Results Analysis of Example 2 and Comparative Example 1
[0089]
[0090]
[0091] Conclusion: Comparing Example 2 and Comparative Example 1, Table 2 shows that by adding a compressor at the top of the catalytic distillation column to pressurize and heat the gas phase at the top of the catalytic distillation column and to exchange heat with the reboiler of the refining column, the use of low-pressure steam (11.26 t / h) and circulating water (544 t / h) can be reduced, and the standard oil content can be reduced by 15.9%.
[0092] Comparative Example 1
[0093] Corresponding to Examples 1 and 2, such as Figure 3 As shown, there is no compressor, and the overhead stream of the purification tower T2 is directly discharged without returning to the catalytic distillation tower T1; the methanol reflux tank discharges the vapor phase directly, and the methanol feedstock tank is pressurized with nitrogen.
[0094] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. Those skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention shall be defined by the appended claims.
Claims
1. An MTBE production apparatus, the MTBE production apparatus comprising: At least one etherification reactor, said etherification reactor having a feed inlet and a discharge outlet; The catalytic distillation column is connected to the etherification reactor outlet and the etherified material inlet of the catalytic distillation column, and the bottom outlet of the catalytic distillation column is connected to an oil-blending MTBE outflow branch. The purification column, wherein the bottom outlet of the catalytic distillation column is also connected to the inlet of the purification column, and the side of the purification column has a chemical-grade MTBE outflow branch, characterized in that: the light component outlet at the top of the purification column is connected to the ether post-material inlet of the catalytic distillation column.
2. The MTBE production apparatus as described in claim 1, characterized in that, The MTBE production facility also includes: The methanol feedstock tank has a methanol inlet and a gas replenishment port. The first branch of the methanol feedstock tank outlet is combined with the mixed C4 inlet pipe and then connected to the feed inlet of the etherification reactor. A catalytic distillation column reflux tank, wherein a first outflow pipeline is provided between the top outlet of the catalytic distillation column and the inlet of the catalytic distillation column reflux tank, and the bottom of the catalytic distillation column reflux tank has a catalytic distillation outflow branch and a catalytic distillation reflux branch that returns to the upper part of the catalytic distillation column; The C4 water washing tower has a C4 inlet connected to the catalytic distillation outlet branch of the reflux tank of the catalytic distillation tower, and the top of the C4 water washing tower has a C4 outlet after water washing. The methanol recovery tower has its bottom outlet connected to the inlet of the C4 water washing tower, and its bottom water outlet connected to the water inlet of the C4 water washing tower. The methanol recovery tower reflux tank has the following configuration: the top outlet of the methanol recovery tower is connected to the inlet of the methanol recovery tower reflux tank; the methanol recovery reflux branch at the bottom of the methanol recovery tower reflux tank is connected to the upper part of the methanol recovery tower; the methanol recovery collection branch at the bottom of the methanol recovery tower reflux tank is connected to the methanol feedstock tank; and the top of the methanol recovery tower reflux tank is connected to the gas phase pressure replenishment of the methanol feedstock tank.
3. The MTBE production apparatus as described in claim 2, characterized in that, The top of the catalytic distillation column is also provided with a second collection pipeline connected in parallel with the first collection pipeline, and the second collection pipeline is equipped with an open heat pump system.
4. The MTBE production apparatus as described in claim 1, characterized in that, The MTBE production unit also includes a purification column condenser and a purification column pressurization pump arranged sequentially between the light component outlet at the top of the purification column and the ether post-material inlet of the catalytic distillation column, and the bottom of the purification column has a heavy component outlet.
5. The MTBE production apparatus as described in claim 2, characterized in that, The at least one etherification reactor specifically includes a first-stage etherification reactor, a second-stage etherification reactor, and a third-stage etherification reactor, which are connected in series in a ring, with the outlet of the current etherification reactor and the inlet of the next etherification reactor being openable or closable. The first branch of the methanol feedstock tank outlet is merged with the mixed C4 inlet pipe and then connected to the inlets of the first-stage, second-stage, and third-stage etherification reactors in an openable or closable manner. The outlets of the first-stage, second-stage, and third-stage etherification reactors are also connected to the post-etherification material inlet of the catalytic distillation column in an openable or closable manner.
6. The MTBE production apparatus as described in claim 5, characterized in that, The first branch of the methanol feedstock tank outlet is merged with the mixed C4 inlet pipe and then connected to the feedstock C4 preheater for heat exchange before being connected to the feed inlets of the first-stage etherification reactor, the second-stage etherification reactor, and the third-stage etherification reactor in an openable or closed manner.
7. The MTBE production apparatus as described in claim 5, characterized in that, The outlets of the first-stage etherification reactor, the second-stage etherification reactor, and the third-stage etherification reactor are respectively connected to the inlet of their own etherification reactor by a first-stage cooler, a second-stage cooler, and a third-stage cooler for heat exchange. The outlet of the first-stage etherification reactor and the inlet of the second-stage etherification reactor share a first branch; the outlet of the second-stage etherification reactor and the inlet of the third-stage etherification reactor share a second branch; and the outlet of the third-stage etherification reactor and the inlet of the first-stage etherification reactor share a third branch, which can be connected in an openable or closed manner.
8. The MTBE production apparatus as described in claim 7, characterized in that, Each of the first-stage etherification reactor, the second-stage etherification reactor, and the third-stage etherification reactor is further equipped with a first-stage circulating pump, a second-stage circulating pump, and a third-stage circulating pump that can be turned on or off between their respective discharge ports and their respective first-stage coolers, second-stage coolers, and third-stage coolers.
9. The MTBE production apparatus as described in claim 2, characterized in that, The second branch of the methanol feedstock tank outlet is also connected to the methanol inlet of the catalytic distillation column.
10. The MTBE production apparatus as described in claim 9, characterized in that, The second branch of the methanol feedstock tank outlet is first connected to the protection reactor and then connected to the methanol inlet of the catalytic distillation column.
11. The MTBE production apparatus as described in claim 2, characterized in that, A catalytic distillation column feed heat exchanger is provided between the bottom outlet pipe of the catalytic distillation column and the ether post-material inlet of the catalytic distillation column; And / or, the inlet of the catalytic distillation column reflux tank is equipped with a catalytic distillation column condenser, and / or, the bottom of the catalytic distillation column reflux tank is equipped with a catalytic distillation column reflux pump; And / or, a C4 cooler is provided on the catalytic distillation outflow branch before the C4 inlet; And / or, the bottom water outlet of the methanol recovery tower is connected to the inlet of the methanol recovery tower by a methanol recovery tower feed heat exchanger. And / or, a water circulation cooler and a water circulation pump are also installed sequentially between the inlet and outlet heat exchanger of the methanol recovery tower and the water inlet of the C4 water washing tower; And / or, a methanol recovery tower cooler is provided between the top outlet of the methanol recovery tower and the inlet of the methanol recovery tower reflux tank.
12. The MTBE production apparatus as described in claim 11, characterized in that, The methanol recovery tower reflux tank is equipped with a methanol recovery tower reflux pump at the bottom.
13. The MTBE production apparatus as described in claim 3, characterized in that, The open heat pump system includes a compressor and a heat exchanger. One end of the compressor is connected to the top outlet of the catalytic distillation column, and the other end of the compressor is connected to the heat exchanger for heat exchange and then connected to the inlet of the reflux tank of the catalytic distillation column.
14. The MTBE production apparatus as described in claim 13, characterized in that, The heat exchanger is a reboiler for a refining tower.
15. The MTBE production apparatus as described in claim 2, characterized in that, The bottom of the catalytic distillation column is equipped with a catalytic distillation column reboiler; The reboiler of the refining tower is equipped with a reboiler. The methanol recovery tower bottom is equipped with a methanol recovery tower reboiler.