Method for reversely driving MTBE-butene device
By directly introducing the heavy four carbon components in the mixed carbon four tanks into the distillation tower for 1-butene separation and purification, and driving the entire system after the output of the DMTO and olefin separation device is qualified, the preparation of 1 in the prior art was solved. -The problem of long butene time has achieved a significant improvement in efficiency.
Patent Information
- Application Number
- CN202411326508.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2024-12-27
AI Technical Summary
In the prior art, 1-butene purification is required to stabilize the production of mixed carbon tetrachloride, resulting in a long time to prepare 1-butene and affect production efficiency.
By directly introducing the heavy four carbon components in the mixed carbon four tanks into the first distillation tower, 1-butene is separated and purified, and the entire system is driven after the DMTO and olefin separation device are qualified to produce, shortening the production time.
The 1-butene preparation time is effectively shortened, from the traditional 72 hours to 24 hours, improving production efficiency.
Smart Images
Figure CN119186000A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of 1-butene preparation technology, and in particular relates to a method for reverse start-up of an MTBE-butene device. Background Art
[0002] Polymerization-grade 1-butene can be produced by ethylene dimerization. Since ethylene itself is very expensive, the production cost is very high and it cannot be applied on a large scale in industry. The mixed C4 produced by the cracking process of petroleum hydrocarbons, after extraction and removal of 1,3-butadiene, is an excellent raw material for producing high-purity 1-butene. Therefore, how to extract 1-butene from mixed C4 is a hot topic of research. The main components of mixed C4 are isobutane, n-butane, isobutylene, 1-butene, trans-2-butene, cis-2-butene and 1,3-butadiene. Among them, the boiling points of 1-butene, isobutylene and 1,3-butadiene are very close. Therefore, it is impossible to obtain high-purity 1-butene by directly using the residual C4 as a raw material and using the separation method. Isobutylene and 1,3-butadiene must be removed to a very low content.
[0003] Nowadays, in industry, mixed C4 is first etherified with MTBE to separate methyl tert-butyl ether, and then the remaining materials are catalytically selectively hydrogenated to remove isobutylene and 1,3-butadiene. The main components after catalytic hydrogenation are H2, H2O, methanol, isobutane, 1-butene, n-butane, trans-2-butene and cis-2-butene. Then, high-purity 1-butene is obtained through distillation of the first distillation tower and the second distillation tower, as well as the heavy C4 product produced by the mixed C4 tank connected to the bottom of the second distillation tower. However, in the above process, the mixed C4 raw material needs to wait for the DMTO and olefin separation unit to start up and stably produce qualified mixed C4 before it can be started up and 1-butene can be refined, which makes the preparation of 1-butene take a long time, affecting production efficiency.
[0004] Therefore, it is necessary to provide a method that can shorten the preparation time of 1-butene. Summary of the invention
[0005] In order to solve the problem in the prior art that 1-butene refining can only be carried out after the mixed four-carbon production is stable, thereby reducing the 1-butene preparation efficiency, the present invention provides a method for reverse start-up of an MTBE-butene device.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows.
[0007] A method for reverse start-up of an MTBE-butene unit comprises the following steps:
[0008] The heavy C4 in the mixed C4 tank is introduced into the first distillation tower through a pipeline to remove the light components, and the C4 fraction at the bottom of the first distillation tower is sent to the second distillation tower, and the C4 fraction is separated in the second distillation tower to remove the heavy components. After part of the gas at the top of the second distillation tower is condensed by a condenser, a part of it is sent out as a butene-1 product, and the n-butane and 2-butene at the bottom of the second distillation tower are sent to the isomerization unit;
[0009] After the DMTO and olefin separation units produce qualified mixed C4, the heavy C4 will be replaced by the mixed C4 and introduced into the first distillation tower through a pipeline before the whole system is started up.
[0010] In another preferred embodiment, the first distillation tower comprises an upper tower and a lower tower;
[0011] The gaseous material of the lower tower enters the bottom of the upper tower through a pipeline as an ascending gaseous material flow, and the liquid of the upper tower is pumped to the top of the lower tower through an intermediate pump for internal reflux;
[0012] The bottom material of the lower tower is the C4 fraction from which the light component of isobutane has been removed, which is pumped out through the bottom pump and sent to the second distillation tower.
[0013] In another preferred embodiment, the second distillation tower comprises an upper tower and a lower tower;
[0014] The gas at the top of the upper tower is condensed by a condenser and enters a reflux tank at the top of the tower. After being pressurized by a reflux pump, a portion of the gas is pumped into the top of the upper tower as reflux, and a portion of the gas is sent out as a 1-butene product.
[0015] The gaseous material at the top of the lower tower enters the bottom of the upper tower through a pipeline as an ascending gaseous material flow, and the liquid in the upper tower bottom is pumped to the top of the lower tower through an intermediate pump for internal reflux; the bottom of the lower tower produces a heavy fraction mainly composed of n-butane and butene-2, which is pumped out by a bottom pump, sent to a butene-2 cooler for cooling, and a part of it is sent to the isomerization unit as a raw material, and the other part is sent out as a by-product after being mixed with heavy carbon four returned from the isomerization unit.
[0016] In another preferred embodiment, the lower tower of the first distillation tower is connected to the upper section of the second distillation tower through a pipeline.
[0017] In another preferred embodiment, the pressure range of the first distillation tower is 0.55 MPa to 0.75 MPa, the top temperature is 45°C to 55°C, the bottom temperature is 65°C to 80°C, and the top reflux ratio is 1320.
[0018] In another preferred embodiment, the pressure range of the second distillation tower is 0.40-0.50 MPa, the top temperature is 40°C-55°C, the bottom temperature is 55°C-70°C, and the top reflux ratio is 28.
[0019] In another preferred embodiment, the specific source process of the heavy four carbons in the mixed four carbon tank is as follows:
[0020] The heavy C4 in the bottom of the second distillation tower is extracted in two ways, one way is used as feed for the isomerization unit, and the other way is sent to the mixed C4 tank as the heavy C4 product.
[0021] In another preferred embodiment, the heavy four carbons include n-butane, cis-2-butene, trans-2-butene and butene.
[0022] In another preferred embodiment, after the DMTO and olefin separation unit produce qualified mixed C4, the heavy C4 is replaced by the mixed C4 and introduced into the first distillation tower through a pipeline, and then the whole system is started up.
[0023] Compared with the prior art, the present invention has the following beneficial effects:
[0024] The present invention directly introduces the heavy C4 in the production line into the 1-butene distillation tower for directly producing 1-butene, thereby effectively improving the time for producing 1-butene. During the entire production process, the start-up can be carried out without waiting for the mixed C4, and the reverse start-up can effectively shorten the start-up time and improve production efficiency. After the DMTO and olefin separation device produce qualified mixed C4, the feed is slowly switched from the heavy C4 to the mixed C4 for full system start-up. Compared with the traditional method of preparing qualified 1-butene products, which takes 72 hours, the method of the present invention only takes 24 hours, which effectively improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 The invention discloses a process for preparing 1-butene by using a prior art MTBE-butene unit.
[0026] Figure 2 This is the process of preparing 1-butene by reverse start-up in an embodiment of the present invention. DETAILED DESCRIPTION
[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0028] Unless otherwise specified, the experimental methods described in the following examples are all conventional methods; the reagents and materials described are all commercially available unless otherwise specified.
[0029] Nowadays, in industry, mixed C4 is first etherified with MTBE to separate methyl tert-butyl ether, and then the remaining materials are catalytically selectively hydrogenated to remove isobutylene and 1,3-butadiene. The main components after catalytic hydrogenation are H2, H2O, methanol, isobutane, 1-butene, n-butane, trans-2-butene and cis-2-butene, and then high-purity 1-butene can be obtained by distillation.
[0030] The process of producing 1-butene in the prior art is as follows: Figure 1 As described above, it is the normal start-up sequence of the MTBE-butene unit. After the DMTO and olefin separation units produce qualified mixed C4, the mixed C4 enters the first distillation tower T3001A / B through the pipeline for distillation to remove light components such as water, propane, isobutane, etc. The top gas enters the reflux tank V3001 after passing through the condenser E3001A / B, and is then pumped out through the reflux pump P3001A / B. A part of it is pumped into the top of the tower as reflux, and a part of it is used as a light C4 delivery device rich in isobutane byproduct. A small amount of non-condensable gas at the top of the tower is discharged into the flare through a regulating valve. Since the first distillation tower is relatively high, it must be divided into two sections, respectively called the upper section of T3001A and the lower section of T3001B. The gaseous material of the lower tower T3001B of the first distillation tower enters the bottom of the upper tower T3001A through a pipeline as an ascending gaseous material flow, and the liquid in the bottom of the tower T3001A is sent to the top of T3001B for internal reflux through the intermediate pump P3003A / B. The bottom material of T3001B is the C4 fraction after removing light components such as isobutane, which is pumped out by the bottom pump P3002A / B and sent to the second distillation tower T3002A / B. The bottom of the first distillation tower is heated by the reboiler E3002, and the heat source is the sub-low pressure steam from the system. The materials from the first distillation tower are separated in the second distillation tower to remove heavy components such as 2-butene and normal butane. The gas at the top of the second distillation tower T3002A is condensed by the condenser E3003 A / B and enters the top reflux tank V3002. After being pressurized by the second distillation tower top reflux pump P3004A / B, part of it is pumped into the top of the second distillation tower as reflux, and part of it is sent out of the boundary area as butene-1 product with a purity of ≥99%. The bottom of the second distillation tower is heated by the reboiler E3004, and the heat source is the sub-low pressure steam from the system.
[0031] The second distillation tower must also be divided into two sections, namely the upper section of T3002A and the lower section of T3002B. The gaseous material at the top of T3002B enters the bottom of T3002A as the ascending gaseous material flow, and the liquid at the bottom of T3002A is sent to the top of T3002B for internal reflux through the intermediate pump P3006A / B. The material at the bottom of T3002B is a heavy fraction mainly composed of n-butane and 2-butene, which is extracted by the bottom pump P3005A / B and sent to the 2-butene cooler E3005 for cooling. A part of it is sent to the isomerization unit as a raw material, and the other part is mixed with the heavy carbon four returned from the isomerization unit as a by-product and then sent out of the device.
[0032] The heavy C4 from pump P3005A / B enters the feed buffer tank V4001, and is vaporized by E4001. The vaporized C4 material is further heat-exchanged with the reaction product in the inlet and outlet heat exchanger E4002 to about 286°C, and then enters the electric heater EH4001. After the raw material is heated to the reaction temperature of 330°C, it enters the reactor R4001 from the top for isomerization reaction. The reactor outlet gas exchanges heat with the feed C4 in the inlet and outlet heat exchanger E4002. After the heat exchange, the temperature of the reaction gas drops to about 121°C, and then enters the 1-butene concentration tower T4001. A crude 1-butene product with a concentration of about 34% is obtained at the top of the tower. The top condenser E4003 uses circulating cooling water for condensation. The liquid phase material in the top reflux tank V4003 is pressurized by the 1-butene concentration tower reflux pump P4001A / B, and a part of it is returned to the 1-butene concentration tower T4001 as reflux liquid, and the other part is sent to the lower tower T3001B of the first distillation tower. The bottom discharge of the tower is mainly a mixed C4 fraction rich in 2-butene, which is sent to the heavy C4 product line after being cooled by the 1-butene concentration tower bottom liquid cooler E4005.
[0033] It can be seen from the above process that in the prior art, 1-butene can only be separated and purified after the DMTO and olefin separation devices have produced qualified mixed C4, and 1-butene can be refined, which makes the preparation time of 1-butene longer and affects the production efficiency.
[0034] It can be seen from the process of preparing 1-butene in the prior art that the raw material mixed C4 used to prepare 1-butene needs to wait for the DMTO and olefin separation units to start up and stably produce qualified mixed C4 before starting up and refining 1-butene, which makes the preparation time of 1-butene longer and affects the production efficiency.
[0035] The present invention utilizes the heavy four carbon components in the mixed carbon four tank connected to the bottom of the second distillation tower, and introduces the heavy four carbons directly into the first distillation tower by reverse driving, so as to separate and purify 1-butene, thereby effectively improving the efficiency of 1-butene refinement. When DMTO and the olefin separation device stably output the mixed four carbons, stop passing the heavy four carbon components at the bottom of the second distillation tower into the first distillation tower, introduce the output mixed carbon four into the first distillation tower, and carry out the normal driving sequence. The method in the present invention can effectively utilize the time before the DMTO and the olefin separation device output qualified mixed carbon four, improve the work efficiency, and also make full use of the heavy four carbon components in the mixed carbon four tank connected to the bottom of the second distillation tower, effectively shorten the working time.
[0036] A method for reverse start-up of an MTBE-butene unit is described in detail below.
[0037] like Figure 2As shown, before the DMTO and olefin separation unit produces qualified mixed C4, the heavy C4 in the mixed C4 tank connected to the lower section T3002B of the second distillation tower is introduced into T3001A / B of the first distillation tower through a pipeline for distillation to remove light components such as water, propane, isobutane, etc. The top gas enters the reflux tank V3001 after passing through the condenser E3001A / B, and is then pumped out through the reflux pump P3001A / B. A part of it is pumped into the top of the tower as reflux, and a part of it is sent to the device as a light C4 byproduct rich in isobutane. A small amount of non-condensable gas at the top of the tower is discharged into the flare through a regulating valve.
[0038] Since the first distillation tower is relatively high, it must be divided into two sections, namely the upper section T3001A and the lower section T3001B. The gaseous material of the lower tower T3001B of the first distillation tower enters the bottom of the upper tower T3001A through a pipeline as an ascending gaseous phase flow, and the liquid in the bottom of T3001A is sent to the top of T3001B for internal reflux through the intermediate pump P3003A / B. The bottom material of the lower section T3001B is the C4 fraction with light components such as isobutane removed, which is pumped out by the bottom pump P3002A / B and sent to the second distillation tower T3002A / B. The bottom of the first distillation tower is heated by a reboiler E3002, and the heat source is the sub-low pressure steam from the system.
[0039] The materials from the first distillation tower are separated in the second distillation tower to remove heavy components such as butene-2 and normal butane. The gas at the top of the tower T3002A of the upper section of the second distillation tower is condensed by the condenser E3003A / B and enters the tower top reflux tank V3002. After being pressurized by the second distillation tower top reflux pump P3004A / B, part of it is pumped into the top of the upper tower of the second distillation tower as reflux, and the other part is sent out of the boundary area as a butene-1 product with a purity of ≥99%. The bottom of the lower tower T3002B produces a heavy fraction mainly composed of normal butane and 2-butene. It is pumped out by the bottom pump and sent to the 2-butene cooler for cooling. Part of it is sent to the isomerization unit as a raw material, and the other part is sent out as a by-product after mixing with the heavy carbon four returned from the isomerization unit.
[0040] After the DMTO and olefin separation units produce qualified mixed C4, the heavy C4 will be replaced by the mixed C4 and introduced into the first distillation tower through a pipeline before the whole system is started up.
[0041] By using the method of the present invention, the time for obtaining qualified 1-butene is 24 hours, while the time for producing qualified 1-butene by using the traditional method is 72 hours. It can be seen that the time for producing 1-butene can be effectively shortened by using the method of the present invention.
[0042] The present invention directly introduces the heavy C4 in the production line into the 1-butene distillation tower for directly producing 1-butene, thereby effectively improving the time for producing 1-butene. During the entire production process, the start-up can be carried out without waiting for the mixed C4, and the reverse start-up can effectively shorten the start-up time and improve production efficiency. After the DMTO and olefin separation device produce qualified mixed C4, the feed is slowly switched from the heavy C4 to the mixed C4 for full system start-up. Compared with the traditional method of preparing qualified 1-butene products, which takes 72 hours, the method of the present invention only takes 24 hours, which effectively improves production efficiency.
[0043] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and variations. The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and their protection scope is not limited thereto. Equivalent substitutions or changes made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention, and the protection scope of the present invention shall be subject to the claims.
Claims
1. A method for reverse start-up of an MTBE-butene unit, characterized in that: The following steps are involved: The heavy C4 in the mixed C4 tank is introduced into the first distillation tower through a pipeline to remove the light components, and then the C4 fraction at the bottom of the first distillation tower is sent to the second distillation tower. The C4 fraction is separated in the second distillation tower. After the heavy components are removed, part of the gas at the top of the second distillation tower is condensed by a condenser and sent out as 1-butene, and the n-butane and 2-butene at the bottom of the second distillation tower are sent to the isomerization unit.
2. The method for reverse start-up of the MTBE-butene unit according to claim 1, characterized in that: The first distillation tower comprises an upper tower and a lower tower; The gaseous material of the lower tower enters the bottom of the upper tower through a pipeline as an ascending gaseous material flow, and the liquid of the upper tower is pumped to the top of the lower tower through an intermediate pump; The bottom product of the lower tower is a C4 fraction from which the light component of isobutane has been removed, which is pumped out through a bottom pump and sent to a second distillation tower.
3. The method for reverse start-up of the MTBE-butene unit according to claim 2, characterized in that: The second distillation tower comprises an upper tower and a lower tower; The gas at the top of the upper tower is condensed by a condenser and enters a reflux tank at the top of the tower. After being pressurized by a reflux pump, a portion of the gas enters the top of the upper tower as reflux, and the other portion is sent out as 1-butene. The gaseous material at the top of the lower tower enters the bottom of the upper tower through a pipeline as an ascending gaseous material flow, and the liquid in the upper tower bottom is pumped to the top of the lower tower through an intermediate pump for internal reflux; the bottom of the lower tower produces a heavy fraction mainly composed of n-butane and butene-2, which is pumped out by a bottom pump, sent to a 2-butene cooler for cooling, and a part of it is sent to the isomerization unit as a raw material, and the other part is sent out as a by-product after being mixed with heavy carbon four returned from the isomerization unit.
4. The method for reverse start-up of an MTBE-butene unit according to claim 3, characterized in that: The lower tower of the first distillation tower is connected to the upper tower of the second distillation tower through a pipeline.
5. The method for reverse start-up of the MTBE-butene unit according to claim 2, characterized in that: The pressure range of the upper tower of the first distillation tower is 0.60MPa-0.65MPa, the top temperature is 45°C-55°C, the bottom temperature is 65°C-80°C, and the top reflux ratio is 1320; The lower tower pressure range of the first distillation tower is 0.65MPa-0.70MPa, the tower top temperature is 60℃-70℃, and the tower bottom temperature is 65℃-75℃.
6. The method for reverse start-up of an MTBE-butene unit according to claim 3, characterized in that: The pressure range of the upper tower of the second distillation tower is 0.40MPa-0.50MPa, the top temperature is 42°C-52°C, the bottom temperature is 46°C-56°C, and the top reflux ratio is 28; The lower tower pressure range of the second distillation tower is 0.45MPa-0.55MPa, the tower top temperature is 46°C-56°C, and the tower bottom temperature is 55°C-65°C.
7. The method for reverse start-up of an MTBE-butene unit according to claim 1, characterized in that: The specific source process of heavy carbon four in the mixed carbon four tank is as follows: The heavy C4 in the bottom of the second distillation tower is connected to the isomerization unit and the mixed C4 tank through pipelines.
8. The method for reverse start-up of an MTBE-butene unit according to claim 1, characterized in that: The heavy four carbons include n-butane, cis-2-butene, trans-2-butene and butene.
9. The method for reverse start-up of an MTBE-butene unit according to claim 1, characterized in that: It also includes that after the DMTO and olefin separation unit produces qualified mixed C4, the heavy C4 is replaced with the mixed C4 and introduced into the first distillation tower through a pipeline, and then the whole system is started up.