Process for separating butene-1 from etherified C4

Abstract

The invention relates to a process for separating butene-1 from etherified C4, which is characterized in that an original process of removing light component first and then removing heavy component is changed into a process of removing heavy component first and then removing light component by changing a separation sequence; the method comprises the following steps of: removing light components such as C3 and iso-butane from the etherified C4 which firstly enters a de-isobutane tower instead of removing heavy components such as butene-2, n-butane and cis-trans-2-butene from the etherified C4 which firstly enters a butene-1 rectifying tower; then introducing a butene-1 rectifying tower top product into a deisobutanizer, separating to obtain light component products rich in C3, iso-butane and the like from the tower top, and obtaining a butene-1 product with the mass concentration of more than or equal to 99.9% at the tower bottom, so that the tower bottom temperatures of the deisobutanizer and the butene-1 rectifying tower are reduced, and hot water with the temperature of 75 DEG C and 95 DEG C is adopted as a reboiling heat source to replace 0.45 MPa steam; steam consumption is saved, waste heat is upgraded and utilized to reduce the process cooling load, and the device is suitable for new device construction and old device transformation.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical engineering, and particularly to a process for separating 1-butene from C4 hydrocarbons after MTBE production. Background Art

[0002] In the process of petroleum processing, multiple process units, such as fluid catalytic cracking units, delayed coking units, continuous reforming units, etc., all produce liquified petroleum gas (LPG). The main components of LPG are C3 and C4 hydrocarbons. C3 hydrocarbons include propylene and propane, and generally propylene is separated by a gas separation unit and used as a raw material for polypropylene production. C4 hydrocarbons include n-butane, isobutane, isobutene, 1-butene, etc., and generally are sent to an MTBE unit where isobutene reacts with methanol to produce methyl tert-butyl ether (MTBE), which is used as an additive for high-octane gasoline. The mixed C4 hydrocarbons after removing isobutene are called C4 hydrocarbons after MTBE production, and industrial-grade 1-butene can be separated from them and used as a comonomer for polyolefin units. The existing process for separating 1-butene from C4 hydrocarbons after MTBE production is "removing light components first and then heavy components", that is, first removing trace C 3 and light components such as isobutane from C4 hydrocarbons after MTBE production through a deisobutanizer, and then separating 1-butene from components such as 2-butene, n-butane, cis / trans-2-butene, etc. through a 1-butene rectification column to obtain a 1-butene product with a mass concentration of ≥99.9%. Since the boiling points of the components are close, the deisobutanizer and the 1-butene rectification column have a large number of trays, and it is necessary to set up two towers in series, resulting in high investment and energy consumption. Moreover, 0.45 MPag steam is used as the reboiling heat source, and the energy grade is high. Therefore, how to develop a new process for separating 1-butene from C4 hydrocarbons after MTBE production to reduce energy consumption and investment costs is an urgent problem to be solved at present. Summary of the Invention

[0003] Aiming at the technical problems existing in the prior art, the object of the present invention is to provide a process for separating 1-butene from C4 hydrocarbons after MTBE production. By optimizing the process to "remove heavy components first and then light components", that is, by changing the separation sequence, the bottom temperature of the tower is reduced, so as to utilize low-grade energy to replace steam, such as hot water generated by recovering waste heat as the reboiling heat source, reducing the cooling load of the device, and further reducing energy consumption and investment costs.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A process for separating 1-butene from C4 hydrocarbons after etherification, characterized by comprising the following steps: introducing the C4 hydrocarbons after etherification into the upper part of the lower column of 1-butene rectification, and arranging a heat source at the bottom of the lower column of 1-butene rectification for heating, controlling the operation under the rectification conditions of the lower column of 1-butene rectification, separating light components containing 1-butene and residual C4 from the top of the lower column of 1-butene rectification, refluxing a part of the heavy components containing residual C4 separated from the bottom thereof, and flowing out the rest; introducing the light components containing 1-butene and residual C4 into the bottom of the upper column of 1-butene rectification, flowing out from the top of the upper column of 1-butene rectification and introducing into the middle part of the upper column of deisobutanization; the upper column of deisobutanization fractionates the light components containing 1-butene and residual C4 into light components containing residual C4 and 1-butene substances, the light components containing residual C4 flow out from the top of the upper column of deisobutanization, and the 1-butene substances flow out from the bottom of the upper column of deisobutanization; introducing the 1-butene substances into the top of the lower column of deisobutanization, flowing out from the bottom of the lower column of deisobutanization, arranging a heat source at the bottom of the lower column of deisobutanization for heating, controlling the operation under the rectification conditions of the lower column of deisobutanization, refluxing a part of the 1-butene substances flowing out from the bottom of the lower column of deisobutanization, and flowing out the rest as 1-butene products.

[0006] Further, the heat source is selected from a reboiler, and the reboiler is heated by hot water at 75-95 °C.

[0007] Further, the reboiler of the lower column of 1-butene rectification is heated by hot water at 95 °C, and the reboiler of the lower column of deisobutanization is heated by hot water at 75 °C.

[0008] Further, a reboiler is arranged in the middle part of the lower column of deisobutanization, and the reboiler is heated by hot water at 75-95 °C.

[0009] Further, the number of theoretical plates of the lower column of 1-butene rectification is 70-90, and the number of theoretical plates of the upper column of 1-butene rectification is 70-90; the number of theoretical plates of the lower column of deisobutanization is 50-90, and the number of theoretical plates of the upper column of deisobutanization is 70-90.

[0010] Further, the light components containing 1-butene and residual C4 flowing out from the top of the upper column of 1-butene rectification are subjected to gas-liquid separation after condensation and cooling, and a part of the liquid phase containing the light components of 1-butene and residual C4 is returned to the upper column of 1-butene rectification after pressure boosting, and the rest flows out and is introduced into the middle part of the upper column of deisobutanization.

[0011] Furthermore, the light components containing the remaining C4 in the overhead stream of the upper deisobutanizer tower are condensed and cooled and then separated into gas and liquid phases. The liquid phase containing the light components with the remaining C4 is pressurized and part of it is returned to the upper deisobutanizer tower, and the rest flows out.

[0012] Furthermore, part of the light components containing 1-butene and the remaining C4 at the bottom of the 1-butene rectifying upper tower is refluxed to the top of the 1-butene rectifying lower tower.

[0013] Furthermore, part of the 1-butene substance at the top of the lower deisobutanizer tower is refluxed to the bottom of the upper deisobutanizer tower.

[0014] Furthermore, the pressure at the top of the 1-butene rectifying upper tower is controlled at 530 ± 50 kPag, and the temperature at the top is controlled at 36.8 ± 5 °C. The pressure at the bottom of the 1-butene rectifying lower tower is controlled at 620 ± 50 kPag, and the temperature at the bottom is controlled at 65.7 ± 5 °C. The pressure at the top of the upper deisobutanizer tower is controlled at 540 ± 50 kPag, and the temperature at the top is controlled at 36.6 ± 5 °C. The pressure at the bottom of the lower deisobutanizer tower is controlled at 640 ± 50 kPag.

[0015] In the present invention, the C4 after etherification in the traditional process for separating 1-butene first enters the upper deisobutanizer tower to remove the remaining C 4 light components (including C 3 and isobutane, etc.) is changed to first enter the 1-butene rectifying lower tower to remove the remaining C 4 heavy components (including 2-butene, n-butane, cis- and trans-2-butene, etc.). The overhead material of the 1-butene rectifying upper tower is sent to the middle of the upper deisobutanizer tower, and the remaining C 4 light component product (rich in C 3 and isobutane) is obtained from the top after separation. Then it enters from the top of the 1-butene rectifying lower tower at the bottom, and finally a 1-butene product with a mass concentration ≥ 99.9% is obtained from the bottom of the 1-butene rectifying lower tower.

[0016] The present invention optimizes and reforms the process by using the original deisobutanizer tower, 1-butene rectifying tower, heat exchange and mechanical equipment.

[0017] In the traditional process for separating 1-butene, a 0.45 MPag steam is used as the heat source for the reboiler at the bottom of the 1-butene rectifying lower tower. In the present invention, 95 °C hot water is used as the heat source (or 95 °C hot water could be used at the previous temperature level), which greatly reduces the energy consumption grade and can also upgrade the waste heat as the reboiling heat source, reducing the consumption of steam and cooling water in the device. In the traditional process for separating 1-butene, a 0.45 MPag steam is used as the heat source for the reboiler at the bottom of the lower deisobutanizer tower. In the present invention, 75 °C hot water is used as the heat source (or 95 °C hot water could be used at the previous temperature level), with better energy-saving effect and further deepening the utilization of waste heat upgrade.

[0018] Since the heat-driven characteristics of the oil processing process determine an excess of waste heat, and the present invention has a lower requirement for the grade of the reboiler heat source, the present invention further reduces the number of trays in the deisobutanizer and the 1-butene rectification column, and appropriately increases the separation energy consumption of the deisobutanizer and the 1-butene rectification column, at the cost of using more waste heat, thereby reducing the equipment investment cost of the deisobutanizer and the 1-butene rectification column. Using more waste heat can help reduce the cooling load, achieving a win-win situation in energy conservation and investment.

[0019] In the present invention, if there is surplus 75°C hot water in the 1-butene unit area, an intermediate reboiler can be installed in the stripping section of the lower column of the 1-butene rectification column, and 75°C hot water can be used as the heat source, thereby reducing the consumption of 95°C reboiling hot water in the lower column of the 1-butene rectification column and further making good use of the regional waste heat resources.

[0020] The present invention has the following advantages:

[0021] 1. The process for separating 1-butene from C4 after etherification in the present invention changes from "removing light components first and then heavy components" to "removing heavy components first and then light components", reducing the bottom temperature of the 1-butene rectification column and the deisobutanizer, replacing 0.45MPag steam. The former uses 95°C hot water as the reboiler heat source, and the latter uses 75°C hot water as the reboiler heat source, not only saving steam but also reducing the cooling load.

[0022] 2. Given the general excess of waste heat in the refining process, the present invention can appropriately reduce the number of trays in the deisobutanizer and the 1-butene rectification column, saving about 10-20% in investment.

[0023] 3. The process for separating 1-butene from C4 after etherification in the present invention is applicable to the construction of new plants and the renovation of old plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic flow diagram of Comparative Example 1 of the traditional process for separating 1-butene from C4 after etherification.

[0025] Figure 2 is a schematic flow diagram of Example 1 of the process for separating 1-butene from C4 after etherification in the present invention.

[0026] Figure 3 is a schematic flow diagram of Example 2 of the process for separating 1-butene from C4 after etherification in the present invention.

[0027] Figure 4 is a schematic flow diagram of Example 3 of the process for separating 1-butene from C4 after etherification in the present invention.

[0028] Among them, 1 is the upper isobutane removal tower, 2 is the air cooler for the overhead gas of the upper isobutane removal tower, 3 is the reflux drum of the upper isobutane removal tower, 4 is the reflux pump of the upper isobutane removal tower, 5 is the bottom oil pump of the upper isobutane removal tower, 6 is the lower isobutane removal tower, 7 is the reboiler of the lower isobutane removal tower, 8 is the bottom oil pump of the lower isobutane removal tower, 9 is the upper tower of the 1-butene distillation column, 10 is the air cooler for the overhead gas of the upper 1-butene distillation column, 11 is the reflux drum of the upper 1-butene distillation column, 12 is the reflux pump of the upper 1-butene distillation column, 13 is the bottom oil pump of the upper tower of the 1-butene distillation column, 14 is the lower tower of the 1-butene distillation column, 15 is the reboiler of the lower 1-butene distillation column, 16 is the bottom oil pump of the lower tower of the 1-butene distillation column, 17 is the intermediate reboiler liquid pump of the lower tower of the 1-butene distillation column, and 18 is the intermediate reboiler of the lower tower of the 1-butene distillation column. Detailed implementation manners

[0029] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0030] A certain petroleum project uses C4 after MTBE as raw material, with a raw material quantity of 10.1 t / h, and is equipped with a device for producing 5 t / h of 1-butene product. The main operating conditions of Comparative Example 1, Example 1, Example 2, and Example 3 are as follows.

[0031] Comparative Example 1

[0032] As Figure 1 shown, a traditional process for separating 1-butene from C4 after MTBE is adopted, that is, the existing four-tower (upper isobutane removal tower 1, lower isobutane removal tower 6, upper tower of the 1-butene distillation column 9, lower tower of the 1-butene distillation column 14) separation process. The upper isobutane removal tower 1 and the lower isobutane removal tower 6 form the isobutane removal tower system, and the upper and lower towers are arranged in series. The C4 after MTBE generated from the upstream MTBE device is used as raw material and enters from the middle of the upper isobutane removal tower 1. The overhead gas of the upper isobutane removal tower 1 is cooled by the air cooler for the overhead gas of the isobutane removal tower 2 and then enters the reflux drum 3 of the isobutane removal tower for gas-liquid separation. The gas phase part is transported to the gas pipeline network, and the liquid phase part is pressurized by the reflux pump 4 of the isobutane removal tower. Part of the remaining C 4 light components are sent out of the device, and the rest is returned as reflux to the top of the upper isobutane removal tower 1.

[0033] The bottom liquid of the upper isobutane removal tower 1 (containing 1-butene and remaining C 4 heavy components) is pumped to the top of the lower isobutane removal tower 6 by the bottom oil pump 5 of the upper isobutane removal tower. The overhead gas of the lower isobutane removal tower 6 returns to the bottom of the upper isobutane removal tower 1. Part of the liquid in its kettle is pressurized by the bottom oil pump 8 of the lower isobutane removal tower and then enters the lower tower 14 of the 1-butene distillation column, and the rest enters the reboiler 7 of the isobutane removal tower for partial vaporization and then returns to the bottom of the lower isobutane removal tower 6. Among them, the reboiling heat source is 0.45 MPag steam.

[0034] The upper column 9 of the 1-butene distillation column and the lower column 14 of the 1-butene distillation column form the 1-butene distillation column system. The upper and lower columns are arranged in series to achieve the separation of 1-butene from the remaining C 4 heavy components (2-butene, n-butane, cis- and trans-2-butene). The material from the bottom of the lower column 6 of the deisobutanizer enters the upper part of the lower column 14 of the 1-butene distillation column. The overhead gas of the lower column 14 of the 1-butene distillation column is transported to the bottom of the upper column 9 of the 1-butene distillation column. Part of the bottom liquid of the lower column 14 of the 1-butene distillation column is pressurized by the bottom oil pump 16 of the lower column 14 of the 1-butene distillation column and sent out of the unit together with the material from the top of the upper column 1 of the deisobutanizer. The rest enters the reboiler 15 of the 1-butene distillation column for partial vaporization and then returns to the bottom of the lower column 14 of the 1-butene distillation column. Among them, the reboiling heat source is 0.45 MPag steam.

[0035] The material from the top of the lower column 14 of the 1-butene distillation column enters the bottom of the upper column 9 of the 1-butene distillation column. The overhead gas of the upper column 9 of the 1-butene distillation column is cooled and fully condensed by the air cooler 10 of the overhead gas of the 1-butene distillation column and then enters the reflux drum 11 of the 1-butene distillation column for gas-liquid separation. The liquid phase is pressurized by the reflux pump 12 of the 1-butene distillation column. Part of it is drawn out as the 1-butene product, and 1-butene with a mass purity of more than 99.9% is obtained. The rest is returned as reflux to the top of the upper column 9 of the 1-butene distillation column. The bottom liquid of the upper column 9 of the 1-butene distillation column returns to the top of the lower column 14 of the 1-butene distillation column through the bottom oil pump 13 of the upper column 9 of the 1-butene distillation column.

[0036] Table 1 shows the composition of the carbon four after etherification of the raw material.

[0037]

[0038]

[0039] Table 2 shows the composition of the product 1-butene.

[0040] No. Component Unit Simulation Value 1 1-Butene % wt 99.92 2 Isobutane % wt 0.07 Total % wt 99.99 Flow Rate t / h 5

[0041] It can be seen that the product 1-butene meets the requirement of mass purity ≥ 99.9%.

[0042] Table 3 shows the main operating parameters of the deisobutanizer and the 1-butene distillation column.

[0043] No. Item Unit Isobutane Stripper 1-Butene Rectifying Column 1 Theoretical Plate Number 175 162 2 Feed Plate Location 72 83 3 Total Feed Rate t / h 10.1 9.0 4 Overhead Product Rate t / h Liquid 0.8 (Gas 0.3) 5.0 5 Bottom Product Rate t / h 9.0 4.0 6 Overhead Pressure kPag 540 530 7 Bottom Pressure kPag 640 620 8 Feed Temperature ℃ 33.3 61.8 9 Overhead Temperature ℃ 36.6 41.0 10 Bottom Temperature ℃ 61.8 65.7 11 Reflux Ratio 76.4 16.1 12 Overhead Cooling Load kW 7475 8243 13 Bottom Reboiler Load kW 7676 8513 14 Intermediate Reboiler Load kW / /

[0044] Note: The total number of theoretical plates = the number of theoretical plates in the tower body + the air cooler + the reboiler.

[0045] Example 1

[0046] As Figure 2As shown, it shows one of the preferred embodiments of the present invention. On the basis of the original process flow of Comparative Example 1, the separation sequence of C4 after etherification is changed. The specific process is as follows:

[0047] Using the four towers and related equipment of the original process, the upper tower 9 of the 1-butene distillation column and the lower tower 14 of the 1-butene distillation column form a 1-butene distillation column system, which is transformed to separate light components (C 3 , isobutane, 1-butene) from heavy components (2-butene, n-butane, cis- and trans-2-butene). As shown in the figure, the C4 after etherification is introduced into the upper part of the lower tower 14 of the 1-butene distillation column, and a heat source is set at the bottom of the lower tower 14 of the 1-butene distillation column for heating. The operation is carried out under the distillation conditions of the lower tower 14 of the 1-butene distillation column. Light components containing 1-butene and residual C4 are separated from the top of the lower tower of the 1-butene distillation column, and a part of the heavy components containing residual C4 are refluxed at the bottom, and the rest flows out. Specifically, the C4 after etherification from the upstream MTBE unit is used as the raw material of the 1-butene unit and enters from the upper part of the lower tower 14 of the 1-butene distillation column. The top gas of the lower tower 14 of the 1-butene distillation column is transported to the bottom of the upper tower 9 of the 1-butene distillation column. The liquid in its kettle (containing heavy components of residual C 4 ) is pressurized by the bottom oil pump 16 of the lower tower of the 1-butene distillation column and then exits the device. The rest enters the reboiler 15 of the 1-butene distillation column for partial vaporization and then returns to the bottom of the lower tower 14 of the 1-butene distillation column. Among them, the reboiling heat source is 95°C hot water.

[0048] The light components containing 1-butene and residual C4 are introduced into the bottom of the upper tower 9 of the 1-butene distillation column, flow out from the top of the upper tower 9 of the 1-butene distillation column and are introduced into the middle part of the deisobutanizer upper tower 1. A part of the light components containing 1-butene and residual C4 at the bottom of the upper tower of the 1-butene distillation column is refluxed to the top of the lower tower of the 1-butene distillation column. Specifically, the material from the top of the lower tower 14 of the 1-butene distillation column enters the bottom of the upper tower 9 of the 1-butene distillation column. The top gas of the upper tower 9 of the 1-butene distillation column is cooled and fully condensed by the air cooler 10 of the top gas of the 1-butene distillation column and then enters the reflux drum 11 of the 1-butene distillation column for gas-liquid separation. The liquid phase contains light components of 1-butene and residual C4, which are pressurized by the reflux pump 12 of the 1-butene distillation column. A part is transported to the deisobutanizer column system for further separation, and the rest is returned as reflux to the top of the upper tower 9 of the 1-butene distillation column. The bottom liquid of the upper tower 9 of the 1-butene distillation column returns to the top of the lower tower 14 of the 1-butene distillation column through the bottom oil pump 13 of the upper tower of the 1-butene distillation column.

[0049] The debutanizer upper column 1 fractionates the light components containing 1-butene and the remaining C4s into the light components containing the remaining C4s and the 1-butene substance. The light components containing the remaining C4s flow out from the top of the debutanizer upper column 1, and the 1-butene substance flows out from the bottom of the debutanizer upper column 1. A part of the 1-butene substance at the top of the debutanizer lower column 6 is refluxed to the bottom of the debutanizer upper column 1. The 1-butene substance is introduced into the top of the debutanizer lower column 6 and flows out from the bottom of the debutanizer lower column 6. A heat source is set at the bottom of the debutanizer lower column 6 for heating, and it is operated under the rectification conditions of the debutanizer lower column 6. A part of the 1-butene substance flowing out from the bottom of the debutanizer lower column 6 is refluxed, and the rest flows out as the 1-butene product. Specifically, the material from the top of the 1-butene rectifying column upper column 9 enters the lower part of the debutanizer upper column 1. The overhead gas of the debutanizer upper column 1 is cooled by the debutanizer overhead gas air cooler 2 and then enters the debutanizer reflux drum 3 for gas-liquid separation. The gas phase goes to the gas pipeline network, and the liquid phase containing the light components of the remaining C4s is pressurized by the debutanizer reflux pump 4. A part of it is sent out of the device as the light components containing the remaining C4s, and the rest is returned as reflux to the top of the debutanizer upper column 1. The bottom liquid of the debutanizer upper column 1 enters the top of the debutanizer lower column 6 through the debutanizer bottom oil pump 5. The overhead gas of the debutanizer lower column 6 is transported back to the bottom of the debutanizer upper column 1. A part of its bottom liquid is pressurized by the debutanizer bottom oil pump 8 and then extracted as the 1-butene product, obtaining 1-butene with a mass purity of more than 99.9%. The rest enters the debutanizer reboiler 7 for partial vaporization and then returns to the bottom of the debutanizer lower column 6. Among them, the reboiling heat source is 75°C hot water.

[0050] Among them, the reboiling return tower temperature of the debutanizer tower system is ≤59°C, and the reboiling return tower temperature of the 1-butene rectifying column tower system is ≤75°C.

[0051] Table 4 shows the main operating parameters of the debutanizer and the 1-butene rectifying column in Example 1.

[0052] No. Item Unit Isobutane Stripper 1-Butene Rectifying Column 1 Theoretical Plate Number 175 162 2 Feed Plate Location 72 83 3 Total Feed Rate t / h 6.1 10.1 4 Overhead Product Rate t / h Liquid 0.8 (Gas 0.3) 6.1 5 Bottom Product Rate t / h 5.0 4.0 6 Overhead Pressure kPag 540 530 7 Bottom Pressure kPag 640 620 8 Feed Temperature ℃ 36.8 33.3 9 Overhead Temperature ℃ 36.6 36.8 10 Bottom Temperature ℃ 58.2 65.7 11 Reflux Ratio 98.1 9.1 12 Overhead Cooling Load kW 9567 6423 13 Bottom Reboiler Load kW 9653 6536 14 Intermediate Reboiler Load kW / /

[0053] Table 5 shows the composition of the 1-butene product in Example 1.

[0054] No. Component Unit Value 1 1-Butene % wt 99.92 2 Isobutane % wt / 2 n-Butane % wt 0.06 3 Trans-Butene % wt 0.01 Total % wt 99.99 Flow Rate t / h 5

[0055] It can be seen from Tables 2 - 5.

[0056] (1) The number of trays, the feed tray position, and the overhead operating pressure of the debutanizer and the 1-butene rectifying column in Example 1 are the same as those in Comparative Example 1.

[0057] (2) Example 1 can ensure the quality and output of the 1-butene product.

[0058] (3) In Example 1, the effective bottom reboiler load: for the isobutane removal column, it increased from 7676 kw to 9653 kw; for the 1-butene rectification column, it decreased from 8513 kw to 6536 kw. The total is 16189 kw, which is the same as that in Comparative Example 1.

[0059] (4) In Example 1, for the bottom temperature of the isobutane removal column, it decreased from 61.8 °C to 58.2 °C, and for the 1-butene rectification column, it remained at 65.7 °C. Therefore, for the former, 75 °C hot water was used as the reboiling heat source, saving 10.6 t / h of 0.45 MPag steam; for the latter, 95 °C hot water was used as the reboiling heat source, saving 11.8 t / h of 0.45 MPag steam. In total, 22.4 t / h of 0.45 MPa steam was saved.

[0060] (5) In Example 1, the total overhead cooling load of the isobutane removal column and the 1-butene rectification column increased from 15718 kw to 15990 kw, an increase of 272 kw compared to Comparative Example 1.

[0061] (6) Calculated based on 170 yuan / t for 0.45 MPa steam, 0.65 yuan / kwh for electricity, 0.06 yuan / kwh for 95 °C hot water, and the annual operation of the unit for 8000 hours, Example 1 saved 25.912 million yuan / year in energy consumption costs compared to Comparative Example 1.

[0062] Example 2

[0063] As Figure 3 shown, in this example, based on Example 1, the number of theoretical plates of the lower tower 6 of the isobutane removal column was reduced to 140, and other processes and operating parameters remained unchanged. Although the separation energy consumption of the lower tower 6 of the isobutane removal column increased, the number of theoretical plates of the lower tower 6 of the isobutane removal column was reduced, thereby reducing the equipment investment cost.

[0064] Table 6 shows the main equipment parameters and operating parameters of Example 2.

[0065] No. Item Unit Isobutane Stripper 1-Butene Rectifying Column 1 Theoretical Plate Number 140 162 2 Feed Plate Location 72 83 3 Total Feed Rate t / h 6.1 10.1 4 Overhead Product Rate t / h Liquid 0.8 (Gas 0.3) 6.1 5 Bottom Product Rate t / h 5.0 4.0 6 Overhead Pressure kPag 540 530 7 Bottom Pressure kPag 640 620 8 Feed Temperature ℃ 36.8 33.3 9 Overhead Temperature ℃ 36.6 36.8 10 Bottom Temperature ℃ 58.0 65.7 11 Reflux Ratio 142.7 9.1 12 Overhead Cooling Load kW 13871 6423 13 Bottom Reboiler Load kW 13956 6536 14 Intermediate Reboiler Load kW / /

[0066] Table 7 shows the product composition of Example 2.

[0067] No. Component Unit Value 1 1-Butene % wt 99.92 2 Isobutane % wt / 2 n-Butane % wt 0.06 3 Trans-Butene % wt 0.01 Total % wt 99.99 Flow Rate t / h 5

[0068] It can be seen from Tables 2, 3, 6, and 7.

[0069] (1) The feed plate positions and overhead operating pressures of the isobutane removal column and the 1-butene rectification column in Example 2 are the same as those in Comparative Example 1.

[0070] (2) Example 2 can ensure the quality and output of the product 1-butene.

[0071] (3) In Example 2, the effective bottom reboiler load: for the isobutane column, it increased from 7676 kw to 13956 kw; for the 1-butene rectification column, it decreased from 8513 kw to 6536 kw. The total is 20492 kw, an increase of 4303 kw compared with Comparative Example 1 which is 16189 kw.

[0072] (4) In Example 2, the bottom temperature: for the isobutane column, it decreased from 61.8 °C to 58.0 °C; for the 1-butene rectification column, it remained at 65.7 °C. Therefore, for the former, 75 °C hot water was used as the reboiling heat source, saving 10.6 t / h of 0.45 MPag steam; for the latter, 95 °C hot water was used as the reboiling heat source, saving 11.8 t / h of 0.45 MPag steam. In total, 22.4 t / h of 0.45 MPa steam was saved.

[0073] (5) In Example 2, the total overhead cooling load of the isobutane column and the 1-butene rectification column increased from 15718 kw to 20294 kw, an increase of 4576 kw compared with Comparative Example 1.

[0074] (6) Calculated based on 170 yuan / t for 0.45 MPa steam, 0.65 yuan / kwh for electricity, and 0.06 yuan / kwh for 95 °C hot water, with the unit operating 8000 hours per year, Example 2 saved 3.532 million yuan in energy consumption costs per year compared with Comparative Example 1.

[0075] (7) In Example 2, the number of theoretical trays of the isobutane column decreased by 35 (from 175 to 140) compared with Comparative Example 1, saving about 10 - 20% of the investment cost of the column equipment.

[0076] Example 3

[0077] As Figure 4 shown, on the basis of Example 1, this example added a middle reboiler 18 process to the lower column 14 of the 1-butene rectification column, reducing the consumption of 95 °C hot water in the reboiler 15 of the lower column of the 1-butene rectification column in Example 1. A liquid phase was withdrawn from the 88th theoretical tray of the lower column 14 of the 1-butene rectification column, pressurized by the middle reboiler liquid pump 17 of the lower column of the 1-butene rectification column and then transported to the middle reboiler 18 of the lower column of the 1-butene rectification column. After heating, it returned to the column from the 87th theoretical tray. The reboiling heat source was 75 °C hot water. Other processes and operating parameters remained unchanged.

[0078] Table 8 shows the main equipment parameters and operating parameters of Example 3.

[0079]

[0080]

[0081] Note: The middle reboiler extraction temperature of the 1-butene rectification column is 57.8 °C, and 75 °C hot water is used as the heat source.

[0082] Table 9 shows the product composition of Example 3.

[0083] No. Component Unit Value 1 1-Butene % wt 99.92 2 Isobutane % wt / 2 n-Butane % wt 0.06 3 Trans-Butene % wt 0.01 Total % wt 99.99 Flow Rate t / h 5

[0084] As can be seen from Tables 2, 3, 8, and 9.

[0085] (1) The number of trays, feed tray location, and top operating pressure of the deisobutanizer and 1-butene rectification column in Example 3 are the same as those in Comparative Example 1.

[0086] (2) Example 3 can ensure the quality and output of the product 1-butene.

[0087] (3) For the effective bottom reboiler load in Example 3, the deisobutanizer increased from 7676 kw to 9653 kw, and the 1-butene rectification column decreased from 8513 kw to 5630 kw. The 1-butene rectification column added an intermediate reboiler with a load of 1163 kw, totaling 16446 kw, an increase of 257 kw compared to 16189 kw in Comparative Example 1.

[0088] (4) For the bottom temperature in Example 3, the deisobutanizer decreased from 61.8 °C to 58.2 °C, and the 1-butene rectification column remained at 65.7 °C. Therefore, the former switched to 75 °C hot water as the reboiling heat source, saving 10.6 t / h of 0.45 MPag steam, and the latter switched to 95 °C hot water as the reboiling heat source, saving 11.8 t / h of 0.45 MPag steam, saving a total of 22.4 t / h of 0.45 MPa steam.

[0089] (5) The intermediate reboiler extraction temperature of the 1-butene rectification column in Example 3 is 57.8 °C, and its intermediate reboiling heat source uses 75 °C hot water, which can save 1163 kw of 95 °C hot water. Among them, the reboiler load of the intermediate reboiler 18 of the deisobutanizer ≤ 2178 kw.

[0090] (6) The total top cooling load of the deisobutanizer and 1-butene rectification column in Example 3 increased from 15718 kw to 16247 kw, an increase of 529 kw compared to the comparative example.

[0091] (7) Calculated based on 170 yuan / t for 0.45 MPa steam, 0.65 yuan / kwh for electricity, 0.06 yuan / kwh for 95 °C hot water, and the device operating 8000 hours per year, Example 3 saves 25.011 million yuan / year in energy consumption costs compared to Comparative Example 1.

[0092] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A process for separating butene-1 from C4 after etherification, characterized in that: The following steps are involved: The etherified C4 is introduced into the upper part of the lower butene-1 distillation tower, and a heat source is arranged at the bottom of the lower butene-1 distillation tower for heating, and the lower butene-1 distillation tower is operated under the distillation conditions, and a light component containing butene-1 and the remaining C4 is separated from the top of the lower butene-1 distillation tower, and a part of the heavy component containing the remaining C4 is separated from the bottom of the tower, and refluxed, and the rest flows out; The light component containing butene-1 and the remaining carbon four is introduced into the bottom of the butene-1 distillation upper tower, flows out from the top of the butene-1 distillation upper tower and is introduced into the middle of the deisobutane upper tower; The deisobutane upper tower fractionates the light components containing butene-1 and residual carbon four into light components containing residual carbon four and butene-1 substances, wherein the light components containing residual carbon four flow out from the top of the deisobutane upper tower, and the butene-1 substances flow out from the bottom of the deisobutane upper tower; The butene-1 substance is introduced into the top of the lower deisobutanizer tower and flows out from the bottom of the lower deisobutanizer tower. A heat source is set at the bottom of the lower deisobutanizer tower for heating. The lower deisobutanizer tower is controlled to operate under distillation conditions. A part of the butene-1 substance flowing out from the bottom of the lower deisobutanizer tower is refluxed, and the rest flows out as a butene-1 product.

2. A process for separating butene-1 from C4 after etherification according to claim 1, characterized in that: The heat source is selected from a reboiler, and the reboiler is heated by hot water at 75-95°C.

3. A process for separating butene-1 from C4 after etherification according to claim 2, characterized in that: The reboiler of the lower tower of the butene-1 distillation is heated by hot water at 95° C., and the reboiler of the lower tower of the deisobutanization is heated by hot water at 75° C.

4. A process for separating butene-1 from C4 after etherification according to claim 1, characterized in that: A reboiler is arranged in the middle of the lower deisobutanization tower, and the reboiler is heated by hot water at 75-95°C.

5. A process for separating butene-1 from C4 after etherification according to claim 1, characterized in that: The number of theoretical plates of the lower tower of butene-1 distillation is 70-90, and the number of theoretical plates of the upper tower of butene-1 distillation is 70-90; the number of theoretical plates of the lower tower of deisobutanization is 50-90, and the number of theoretical plates of the upper tower of deisobutanization is 70-90.

6. A process for separating butene-1 from C4 after etherification according to claim 1, characterized in that: The light components containing butene-1 and remaining carbon four flowing out from the top of the butene-1 distillation upper tower are condensed and cooled to separate the gas and liquid. After the liquid phase contains butene-1 and remaining carbon four light components, a part of the pressure is increased and returned to the butene-1 distillation upper tower, and the rest flows out and is introduced into the middle part of the deisobutanization upper tower.

7. A process for separating butene-1 from C4 after etherification according to claim 1, characterized in that: The light components containing the remaining C4 flowing out from the top of the deisobutanizer upper tower are condensed and cooled and then separated into gas and liquid. After the pressure of the light components containing the remaining C4 in the liquid phase is increased, a part of the components returns to the deisobutanizer upper tower, and the rest flows out.

8. A process for separating butene-1 from C4 after etherification according to claim 1, characterized in that: A part of the light components containing butene-1 and remaining carbon four at the bottom of the butene-1 distillation upper tower is refluxed to the top of the butene-1 distillation lower tower.

9. A process for separating butene-1 from C4 after etherification according to claim 1, characterized in that: A portion of the butene-1 material at the top of the deisobutanizer lower tower is refluxed to the bottom of the deisobutanizer upper tower.

10. A process for separating butene-1 from C4 after etherification according to claim 1, characterized in that: The pressure at the top of the butene-1 distillation upper tower is controlled at 530±50kPag, and the temperature at the top is controlled at 36.8±5°C; the pressure at the bottom of the butene-1 distillation lower tower is controlled at 620±50kPag, and the temperature at the bottom is controlled at 65.7±5°C; the pressure at the top of the deisobutanization upper tower is controlled at 540±50kPag, and the temperature at the top is controlled at 36.6±5°C; the pressure at the bottom of the deisobutanization lower tower is controlled at 640±50kPag.

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