Butene-1 rectification heat energy utilization system

Abstract

The utility model discloses a butylene-1 rectification heat energy utilization system which comprises a first rectification tower and a second rectification tower which are respectively a light component removal tower and a heavy component removal tower, and a tower bottom discharge port of the first rectification tower is communicated with a feed port of the second rectification tower. The waste heat of the light fraction is fully utilized through the flash tank, a part of the light fraction is returned after flash evaporation, enters the compressor to be pressurized and then exchanges heat with the reboiler again, the heat exchange temperature difference is larger, the waste heat is fully utilized, and economic benefits are increased.

Description

Technical Field

[0001] The utility model belongs to the technical field of butene-1 distillation, and in particular relates to a butene-1 distillation heat energy utilization system. Background Art

[0002] Butene-1 is an important basic chemical raw material, and its main uses are as polyethylene comonomer, polybutene-1, methyl ethyl ketone, 2-butanol, etc.

[0003] At present, the separation technologies of butene-1 at home and abroad mainly include extraction distillation process and precision distillation process. The butene-1 obtained by extraction distillation has low purity and high impurity content. The precision distillation process can obtain polymerization-grade butene-1.

[0004] At present, China mainly uses mixed C4 to obtain butene-1 products through precision distillation technology. Mixed C4 mainly contains isobutylene, butene-1, cis-2-butene, trans-2-butene, n-butane, isobutane, 1,3-butadiene and other components. The sources of mixed C4 include residual C4, catalytic cracking C4, MTO C4, etc. In order to obtain polymerization-grade butene-1 products, mixed C4 first passes through the MTBE device, and the isobutylene is removed by etherification reaction to generate MTBE, and then through selective hydrogenation, the content of 1,3-butadiene is controlled within the product requirements, and finally the butene-1 product is obtained through distillation. Precision distillation requires two distillation towers to remove the light component isobutane first, and then remove the heavy components cis-2-butene, trans-2-butene, n-butane, etc. The two distillation towers require upper and lower towers respectively, with a large number of plates, a large reflux ratio, and high energy consumption. Therefore, it is necessary to introduce comprehensive thermal energy technology to reduce the energy consumption of the device and improve the economy of the device.

[0005] Patent document CN112358375 discloses a two-tower dual heat pump integrated 1-butene refining energy-saving process and device, which uses heat pump technology to establish a heat pump distillation system of a heavy removal tower and a light removal tower and integrates waste heat recycling, thereby reducing energy consumption. However, in the patent document CN112358375, the light component is directly decompressed and refluxed after being compressed and heat exchanged, and the heat is still not fully utilized, and the reboiler needs to be supplemented with heat, so the energy consumption is still high. Utility Model Content

[0006] Aiming at the technical problem that the light component in patent document CN112358375 is directly decompressed and refluxed after being compressed for heat exchange, but the heat is not fully utilized and the energy consumption is high, the purpose of this utility model is to provide a novel butene-1 distillation heat energy utilization system.

[0007] The utility model discloses a butene-1 distillation heat energy utilization system, comprising a first distillation tower and a second distillation tower, which are respectively a light removal tower and a heavy removal tower, and the bottom discharge port of the first distillation tower is connected with the feed port of the second distillation tower, wherein:

[0008] The first distillation tower is connected to the first reboiler at the bottom, and the top discharge port of the first distillation tower is connected to the first compressor, the first flash tank and the first reflux tank in sequence, and one port of the first reflux tank is connected to the top reflux port of the first distillation tower; wherein the first light fraction pressurized by the first compressor is heat exchanged with the first heavy fraction in the first reboiler and then circulated into the first flash tank, and the first outlet of the first flash tank is connected to the first reflux tank; the second outlet of the first flash tank is connected to the first compressor;

[0009] The second distillation tower is connected to a second reboiler at its bottom, and the top discharge port of the second distillation tower is connected to a second compressor, a second flash tank and a second reflux tank in sequence, and one port of the second reflux tank is connected to the top reflux port of the second distillation tower; wherein, the second light fraction pressurized by the second compressor is heat exchanged with the second heavy fraction in the second reboiler and then circulated into the second flash tank, and the first outlet of the second flash tank is connected to the second reflux tank; the second outlet of the second flash tank is connected to the second compressor.

[0010] Preferably, a first condenser is connected between the first flash tank and the first reflux tank;

[0011] A second condenser is also connected between the second flash tank and the second reflux tank.

[0012] Preferably, the other port of the first reflux tank is connected to the first light fraction recovery pipeline for the production of the first light fraction product;

[0013] The other port of the second reflux tank is connected to the second light fraction recovery pipeline for production of the second light fraction product.

[0014] Preferably, the raw material of the butene-1 distillation heat energy utilization system is a C4 raw material, which enters the first distillation tower from the feed inlet of the first distillation tower.

[0015] Preferably, the C4 raw material is cracked C4, MTO C4 or raffinate C4, and the concentration of butene-1 in the C4 raw material is 20wt% to 69wt%.

[0016] Preferably, the first distillation tower is a light fractionation tower; the second distillation tower is a heavy fractionation tower, and the second light fraction of the second distillation tower is a butene-1 product.

[0017] Preferably, the first reboiler comprises a first reboiler first partition and a first reboiler second partition, and the first reboiler first partition and the first reboiler second partition are respectively connected to the bottom of the first distillation tower;

[0018] The second reboiler includes a second reboiler first partition and a second reboiler second partition, and the second reboiler first partition and the second reboiler second partition are respectively connected to the bottom of the second distillation tower.

[0019] Preferably, the first heavy fraction of the first reboiler first separator is heat exchanged with the first light fraction pressurized by the first compressor; the first reboiler second separator is used for start-up and heat supplement;

[0020] The second heavy fraction of the first separator of the second reboiler is heat-exchanged with the second light fraction pressurized by the second compressor; the second separator of the second reboiler is used for start-up and heat supplement.

[0021] Preferably, the bottom of the second distillation tower is connected to a second heavy fraction recovery pipeline for extracting the second heavy fraction.

[0022] The positive and progressive effects of the utility model are:

[0023] 1) The gas phase at the top of the tower in the butene-1 distillation heat energy utilization system of the utility model is pressurized by a compressor, exchanges heat with a reboiler and flows into a flash tank. Since the temperature of the gas phase becomes higher after pressurization, the heat exchange temperature difference is large, the waste heat is more fully utilized, and the consumption of steam and circulating water is greatly reduced, which has significant economic benefits.

[0024] 2) The flash tank in the butene-1 distillation heat energy utilization system of the utility model can achieve the effect of secondary utilization, that is, a part of the light fraction in the flash tank can be returned to the compressor for pressurization and temperature increase to exchange heat with the reboiler, which can make full use of the light fraction and prevent the pressurized amount in the compressor from being insufficient for heat exchange with the reboiler.

[0025] 3) The raw material of the butene-1 distillation heat energy utilization system of the utility model is C4 raw material. In addition to the residual C4 raw material, the high-energy-consuming cracked C4 and MTO C4 raw materials can be used to efficiently utilize heat energy to obtain butene-1 through this system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the utility model. DETAILED DESCRIPTION

[0027] The following is an explanation of the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] like Figure 1 As shown, the butene-1 distillation heat energy utilization system of the utility model includes a first distillation tower T1 and a second distillation tower T2.

[0029] In this example, the first distillation tower T1 is a light-removing distillation tower for removing fractions lighter than butene-1. The bottom of the first distillation tower T1 is connected to a first reboiler, and the first reboiler includes a first reboiler first separator E1 and a first reboiler second separator E2, that is, the first reboiler first separator E1 and the first reboiler second separator E2 are respectively connected to the bottom of the first distillation tower T1. Among them, the first reboiler second separator E2 is used for starting and supplementing heat. The top discharge port of the first distillation tower T1 is connected to the first compressor C1, the first flash tank D3 and the first reflux tank D1 in sequence. The first condenser E5 is also connected between the first flash tank D3 and the first reflux tank D1. The first reflux tank D1 has two ports, one port of the first reflux tank D1 is connected to the top reflux port of the first distillation tower T1, and the other port of the first reflux tank D1 is connected to the first light fraction recovery pipeline for the extraction of the first light fraction product. In order to utilize the thermal energy of the light fraction at the top of the de-lightening tower, the first light fraction pressurized by the first compressor C1 is heat exchanged with the first heavy fraction in the first reboiler first fractionator E1 and then circulated to the first flash tank D3, so that the first reboiler first fractionator E1 can utilize the heat of the pressurized first light fraction.

[0030] It is worth noting that at this time, the first light fraction in the first flash tank D3 still has residual heat energy that has not been fully exchanged, and the heat of the first light fraction flowing out from the top of the first distillation tower T1 in the first compressor C1 after all entering the first compressor C1 is still not enough for the heat required by the first reboiler first distributor E1. Therefore, the utility model further provides the first flash tank D3 with two outlets, the first outlet of the first flash tank D3 is connected to the first reflux tank D1, and the second outlet of the first flash tank D3 is connected to the first compressor C1, so that the first compressor C1 continues to pressurize and heat the first light fraction replenished, and the residual heat of the first light fraction after the first heat exchange continues to be provided to the first reboiler first distributor E1 for heat exchange, thereby fully utilizing the residual heat of the first light fraction after the first heat exchange.

[0031] The second distillation tower T2 is a de-heavy distillation tower, and the feed port of the second distillation tower T2 is connected to the discharge port at the bottom of the first distillation tower T1, which is used to introduce the raw material from which the fraction lighter than butene-1 has been removed into the second distillation tower T2 to remove the fraction heavier than butene-1. The bottom of the second distillation tower T2 is also connected to a second reboiler, and the second reboiler includes a second reboiler first separator E4 and a second reboiler second separator E3, that is, the second reboiler first separator E4 and the second reboiler second separator E3 are respectively connected to the bottom of the second distillation tower T2. Among them, the second reboiler second separator E3 is used for starting and supplementing heat. The bottom of the second distillation tower T2 is connected to a second heavy fraction recovery pipeline for the extraction of the second heavy fraction. The top discharge port of the second distillation tower T2 is sequentially connected to a second compressor C2, a second flash tank D4 and a second reflux tank D2. The second reflux tank D2 has two ports, one of which is connected to the top reflux port of the second distillation tower T2, and the other port of the second reflux tank D2 is connected to the second light fraction recovery pipeline for the extraction of the second light fraction product. The second flash tank D4 is also connected to the second reflux tank D2 with a second condenser E6. In order to utilize the heat energy of the light fraction at the top of the deweighting tower, the second light fraction pressurized by the second compressor C2 is heat-exchanged with the second heavy fraction in the first reboiler E4 and then circulated to the second flash tank D4, so that the first reboiler E4 can utilize the heat of the pressurized second light fraction.

[0032] It is worth noting that at this time, the second light fraction in the second flash tank D4 still has residual heat energy that has not been fully exchanged, and the heat of the second light fraction flowing out from the top of the second distillation tower T2 in the second compressor C2 after all entering the second compressor C2 is still not enough for the heat required by the first distributor E4 of the second reboiler. Therefore, the utility model further provides the second flash tank D4 with two outlets, the first outlet of the second flash tank D4 is connected to the second reflux tank D2, and the second outlet of the second flash tank D4 is connected to the second compressor C2, so that the second light fraction replenished by the second compressor C2 continues to be pressurized and heated, and the residual heat of the second light fraction after the first heat exchange continues to be provided to the first distributor E4 of the second reboiler for heat exchange, thereby making full use of the residual heat of the second light fraction after the first heat exchange. In a preferred example, the second light fraction of the second distillation tower T2 is a butene-1 product.

[0033] The raw material of the butene-1 distillation heat energy utilization system of the utility model is a C4 raw material, which enters the first distillation tower T1 from the feed port of the first distillation tower T1. Further, the C4 raw material is cracked C4, MTO C4 or raffinate C4, wherein the concentration of butene-1 in the C4 raw material is 20wt% to 69wt%.

[0034] In this system, the C4 raw material first passes through the top of the first distillation tower T1 to remove isobutane from the first light fraction recovery pipeline at the other port of the first reflux tank D1, and then passes through the bottom of the second distillation tower T2 to remove the remaining C4 from the second heavy fraction recovery pipeline, and the butene-1 product is extracted from the second light fraction recovery pipeline through the top of the second distillation tower T2.

[0035] Among them, the first light fraction evaporated from the top of the first distillation tower T1 is pressurized and heated by the first compressor C1, and heat exchanged with the first reboiler first sub-tank E1, and then enters the first flash tank D3. A part of the first light fraction passes through the first condenser E5 and the first reflux tank D1, and the other part of the first light fraction is sent back to the first compressor C1 for pressurization and temperature increase to exchange heat with the first reboiler first sub-tank E1. The second light fraction evaporated from the top of the second distillation tower T2 is pressurized and heated by the second compressor C2, and heat exchanged with the second reboiler first sub-tank E4, and then enters the second flash tank D4. A part of the second light fraction passes through the second condenser E6 and the second reflux tank D2, and the other part of the second light fraction is sent back to the second compressor C2 for pressurization and temperature increase to exchange heat with the second reboiler first sub-tank E4. That is, the flash tank can make the light fraction available for multiple use, so that the light fraction can be fully utilized and the amount of pressurization in the compressor is prevented from being insufficient for heat exchange with the reboiler.

[0036] The butene-1 distillation heat energy utilization system of the utility model specifically includes the following processes:

[0037] (1) After the etherified C4 mixture of MTBE is subjected to a selective hydrogenation reaction, the main components are isobutylene, butene-1, cis-2-butene, trans-2-butene, n-butane, isobutane and 1,3-butadiene. The C4 raw material mixture enters the first distillation tower T1 for distillation. The first light fraction containing isobutane, C3 and a small amount of butene-1 is extracted from the top of the tower, and after being pressurized and heated by the first compressor C1, it is heat exchanged with the first reboiler first separator E1 to recover the heat. After passing through the first flash tank D3, a part of it returns to the first compressor C1 for pressurization and temperature increase and heat exchange with the first reboiler first separator E1. The other part is cooled to the reflux temperature by the first condenser E5 and then decompressed by the pressure reducing valve and enters the first reflux tank D1. A part of the first light fraction in the first reflux tank D1 is refluxed to the first distillation tower T1, and the remaining part is extracted as the isobutane product;

[0038] (2) After the C4 raw material mixture enters the first distillation tower T1 for distillation, the first heavy fraction containing butene-1, cis-2-butene, and trans-2-butene is taken out from the bottom of the first distillation tower T1 and sent to the second distillation tower T2 for distillation;

[0039] (3) The first heavy fraction of the first distillation tower T1 enters the second distillation tower T2 for distillation, and the second heavy fraction is the remaining C4 and is extracted from the bottom of the second distillation tower T2; the second light fraction is the butene-1 product and is extracted from the top of the second distillation tower T2, and after being pressurized and heated by the second compressor C2, it exchanges heat with the first separator E4 of the second reboiler to recover heat, and then passes through the second flash tank D4, a part of which returns to the second compressor C2 for pressurization and temperature increase and exchanges heat with the first separator E4 of the second reboiler, and the other part passes through the second condenser E6 to be cooled to the reflux temperature, and then passes through the pressure valve to enter the second reflux tank D2 after being decompressed. A part of the second light fraction in the second reflux tank D2 is refluxed to the second distillation tower T2, and the remaining part is extracted as the butene-1 product.

[0040] Example 1

[0041] The hydrogenated C4 feedstock (see Table 1) with a temperature of 40°C and a flow rate of 24483 kg / hr enters the first distillation tower T1. The gas phase at the top of the first distillation tower T1 has a flow rate of 155488 kg / hr, a temperature of 48.61°C, and a pressure of 0.56 MPaG. It is pressurized to 1.61 MPaG by the first compressor C1, and the temperature is 91.46°C. Then it passes through the first reboiler first divider E1 for heat exchange to 72°C. Then it passes through the first flash tank D3 with a flash pressure of 0.7 MPaG. 17 wt% of the gas phase is flashed out and returns to the first compressor C1 for pressurization and temperature increase, and is heat exchanged with the first reboiler first divider E1. The other part passes through the first condenser E5, is cooled to 44°C by the first condenser E5, and then enters the first reflux tank D1. One part returns to the first distillation tower T1 for reflux, and the other part is produced as isobutane product. The bottom liquid flow rate of the first distillation tower is 21227 kg / hr, and the temperature is 66°C, and it enters the second distillation tower T2 for distillation. The top gas phase flow rate of the second distillation tower T2 is 152743 kg / hr, the temperature is 44°C, and the pressure is 0.42 MPaG. It is pressurized to 1.3 MPaG by the second compressor C2, and the temperature is 88°C. Then it passes through the second reboiler first divider E4 for heat exchange to 68°C, and then passes through the second flash tank D4 with a flash pressure of 0.55 MPaG. 12 wt% of the gas phase is flashed out and returns to the second compressor C2 for pressurization and temperature increase, and is heat exchanged with the second reboiler first divider E4. Another part is cooled to 40°C by the second condenser E6, and then decompressed and enters the second reflux tank D2. The last part returns to the second distillation tower T2 for reflux, a part is produced as butene-1 product, and the remaining carbon four at the bottom of the tower is cooled to 40°C and then produced.

[0042] Table 1 Ether post-C4 composition

[0043]

[0044]

[0045] Comparative Example 1

[0046] This comparative example corresponds to Example 1, and the raw materials are the same as those of Example 1, except that the light fraction is pressurized and heat-exchanged by the compressor, and then directly enters the condenser for condensation, is decompressed by the pressure reducing valve, and refluxes.

[0047] Conclusion: Comparative Example 1 did not use the flash tank to fully utilize the light fraction after pressurization heat exchange, resulting in insufficient pressurized volume in the compressor for heat exchange with the reboiler, that is, the heat was not fully utilized, and the reboiler needed additional heat, and the energy consumption was still high.

[0048] Table 2 Butene 1 Utilities, Energy Consumption Quota and Consumption Table (Comparative Example 1)

[0049]

[0050] Table 3 Butene 1 Utilities, Energy Consumption Quota and Consumption Table (Example 1)

[0051]

[0052] Tables 2 and 3 are compared based on 5000 kg / hr of butene-1. Table 2 is the energy consumption of the comparative example, and Table 3 is the energy consumption of Example 1. It can be seen from Tables 2 and 3 that the circulating water of the butene-1 distillation heat energy utilization system of the utility model is reduced by 712 t / hr, the steam is reduced by 12.14 t / hr, and the electricity is increased by 1120 kWh.

[0053] The utility model is described in detail above in conjunction with the embodiments of the drawings. A person skilled in the art can make various variations of the utility model according to the above description. Therefore, some details in the embodiments should not constitute a limitation of the utility model, and the utility model shall be protected within the scope defined by the attached claims.

Claims

1. A butene-1 distillation heat energy utilization system, comprising a first distillation tower and a second distillation tower, which are respectively a light removal tower and a heavy removal tower, and the bottom discharge port of the first distillation tower is connected to the feed port of the second distillation tower, characterized in that: The first distillation tower is connected to the first reboiler at the bottom, and the top discharge port of the first distillation tower is connected to the first compressor, the first flash tank and the first reflux tank in sequence, and one port of the first reflux tank is connected to the top reflux port of the first distillation tower; wherein the first light fraction pressurized by the first compressor is heat exchanged with the first heavy fraction in the first reboiler and then circulated into the first flash tank, and the first outlet of the first flash tank is connected to the first reflux tank; the second outlet of the first flash tank is connected to the first compressor; The second distillation tower is connected to a second reboiler at its bottom, and the top discharge port of the second distillation tower is connected to a second compressor, a second flash tank and a second reflux tank in sequence, and one port of the second reflux tank is connected to the top reflux port of the second distillation tower; wherein, the second light fraction pressurized by the second compressor is heat exchanged with the second heavy fraction in the second reboiler and then circulated into the second flash tank, and the first outlet of the second flash tank is connected to the second reflux tank; the second outlet of the second flash tank is connected to the second compressor.

2. The butene-1 distillation heat energy utilization system according to claim 1, characterized in that: A first condenser is also connected between the first flash tank and the first reflux tank; A second condenser is also connected between the second flash tank and the second reflux tank.

3. The butene-1 distillation heat energy utilization system according to claim 1, characterized in that: The other port of the first reflux tank is connected to the first light fraction recovery pipeline for extracting the first light fraction product; The other port of the second reflux tank is connected to the second light fraction recovery pipeline for production of the second light fraction product.

4. The butene-1 distillation heat energy utilization system according to claim 3, characterized in that: The raw material of the butene-1 distillation heat energy utilization system is a C4 raw material, which enters the first distillation tower from the feed inlet of the first distillation tower.

5. The butene-1 distillation heat energy utilization system according to claim 4, characterized in that: The C4 raw material is cracked C4, MTO C4 or raffinate C4, and the concentration of butene-1 in the C4 raw material is 20wt% to 69wt%.

6. The butene-1 distillation heat energy utilization system according to claim 4, characterized in that: The first distillation tower is a light removal distillation tower; the second distillation tower is a heavy removal distillation tower.

7. The butene-1 distillation heat energy utilization system according to claim 4, characterized in that: The second light fraction of the second distillation tower is a butene-1 product.

8. The butene-1 distillation heat energy utilization system according to claim 1, characterized in that: The first reboiler comprises a first reboiler first separator and a first reboiler second separator, and the first reboiler first separator and the first reboiler second separator are respectively connected to the bottom of the first distillation tower; The second reboiler includes a second reboiler first partition and a second reboiler second partition, and the second reboiler first partition and the second reboiler second partition are respectively connected to the bottom of the second distillation tower.

9. The butene-1 distillation heat energy utilization system according to claim 8, characterized in that: The first heavy fraction of the first reboiler first separator is heat exchanged with the first light fraction pressurized by the first compressor; the first reboiler second separator is used for start-up and heat supplement; The second heavy fraction of the first separator of the second reboiler is heat-exchanged with the second light fraction pressurized by the second compressor; the second separator of the second reboiler is used for start-up and heat supplement.

10. The butene-1 distillation heat energy utilization system according to claim 3, characterized in that: The bottom of the second distillation tower is connected with a second heavy fraction recovery pipeline for extracting the second heavy fraction.

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