CN216755430U - Double-tower rectification system for alkylation reaction product - Google Patents

Abstract

The utility model discloses a double-tower rectification system for an alkylation reaction product, and particularly relates to the field of petroleum refining industry, wherein the double-tower rectification system comprises an isobutane removing tower, an n-butane removing tower, a reboiler and a circulating heat extraction line; the upper part of the deisobutanizer is provided with an alkylation reaction product feeding line, the top of the deisobutanizer is communicated with the deisobutanizer, the top of the n-butane removing tower is communicated with the n-butane removing condenser, the middle of the deisobutanizer is provided with a first reboiler, the bottom of the deisobutanizer is respectively provided with a second steam reboiler and a mixture material line which are communicated with the middle of the n-butane removing tower, the bottom of the n-butane removing tower is respectively provided with a third steam reboiler and an alkylated gasoline product material discharging line, and a circulating heat taking line is respectively connected with the deisobutanizer, the n-butane removing condenser, the compressor and the first reboiler in sequence. Compared with the prior art, the method can obviously reduce the energy consumption and the cost of the alkylation reaction product rectification system, improve the efficiency and facilitate the later maintenance treatment.

Description

Double-tower rectification system for alkylation reaction product

Technical Field

The utility model relates to the field of petroleum refining industry, in particular to a double-tower rectification system for an alkylation reaction product.

Background

In the petroleum refining industry, the types of gasoline mainly include catalytic cracking gasoline, reformed gasoline, alkylated gasoline, direct current gasoline, hydrogenated gasoline and the like according to different refining modes, wherein the alkylated gasoline has high octane number, low content of harmful substances (sulfur, nitrogen and the like) and higher anti-explosion performance, is an ideal clean gasoline blending component, can improve the overall efficiency of the gasoline and meets the development requirements of the chemical industry.

The alkylation gasoline is a product of alkylation reaction of isobutane and olefin under the action of an acid catalyst, and the alkylation reaction product contains a large amount of unreacted isobutane and n-butane besides the alkylation gasoline mainly containing isooctane after deacidification, and the isobutane and n-butane removal treatment is carried out on the alkylation product, so that the high content of octane number in the alkylation reaction product can be ensured. At present, a single-tower type structure is mostly adopted in an alkylation device for deisobutanizing in a product fractionation and refining process, circulating water is adopted for cooling isobutane separated at the top of a tower and normal butane extracted from the tower, 1.0MPa (G) steam is adopted as a heat source of a reboiler at the bottom of the tower, the number of required cooling equipment is large, the energy consumption is high, and the production and operation cost is influenced by high energy consumption. And moreover, the single-tower type is adopted, the height of the tower is at least 50 meters, and great difficulty is caused to later production and maintenance.

In order to solve the problems, the utility model provides a double-tower rectification system for an alkylation reaction product, which reduces the operation cost of the whole production process by an energy-saving technology.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a double-tower rectification system for alkylation reaction products, which is used for solving the problems of high energy consumption, high cost and difficult equipment maintenance in the fractionation and refining process of the alkylation reaction products.

In order to achieve the purpose, the utility model provides the following scheme:

the utility model discloses a double-tower rectification system for alkylation reaction products, which comprises an isobutane removing tower, an n-butane removing tower, a reboiler and a circulating heat extraction line, wherein the isobutane removing tower is connected with the reboiler; the upper part of the deisobutanizer is communicated with an alkylation reaction product feeding line, the reboiler is used for heating materials in the deisobutanizer and/or the n-butane removing tower, the bottom of the deisobutanizer is communicated with the middle part of the n-butane removing tower, the bottom of the n-butane removing tower is communicated with an alkylated gasoline product discharging line, and the circulating heat-taking line is used for taking the gas discharged from the top of the deisobutanizer and the heat in the gas discharged from the top of the n-butane removing tower as heat sources of the reboiler;

preferably, the circulating heat-taking line comprises an deisobutanizer, an n-butane-removing condenser and a compressor, a top discharge port of the deisobutanizer is communicated with an isobutane inlet of the deisobutanizer, a top discharge port of the n-butane-removing condenser is communicated with an n-butane inlet of the n-butane-removing condenser, an isobutane outlet of the deisobutanizer is connected and communicated with an isobutane return line and an isobutane product discharge line, the isobutane return line is communicated with a return port formed in the upper portion of the deisobutanizer, an n-butane outlet of the n-isobutane condenser is connected and communicated with an n-butane return line and an n-butane product discharge line, the n-butane return line is communicated with a return port formed in the upper portion of the n-butane-removing condenser, and cooling medium inlets of the deisobutanizer and the n-butane-removing condenser are used for introducing cooling media of the circulating heat-taking line, the cooling medium outlets of the deisobutanizer and the deisobutanizer condenser are communicated with the inlet of the compressor, and the outlet of the compressor is communicated with at least one reboiler gas inlet;

preferably, the reboiler is used for heating the materials in the deisobutanizer or the normal butane removal tower, the reboilers are respectively a first reboiler, a second reboiler and a third reboiler, the first reboiler is communicated with a middle discharge port of the deisobutanizer through a feed pipeline, the first reboiler is communicated with a middle feed port of the deisobutanizer through a discharge pipeline, a middle discharge port of the deisobutanizer is arranged below the middle feed port, the second reboiler is communicated with a discharge port at the bottom of the deisobutanizer through a feed pipeline, the second reboiler is communicated with a lower feed port of the deisobutanizer through a discharge pipeline, a discharge port at the bottom of the deisobutanizer is arranged below the lower feed port, and the third reboiler is communicated with a discharge port at the bottom of the normal butane removal tower through a feed pipeline, the third reboiler is communicated with a feeding port at the lower part of the n-butane removing tower through a discharge pipeline, and a discharge port at the bottom of the n-butane removing tower is arranged below the feeding port at the lower part;

preferably, the outlet of the compressor is communicated with the gas inlet of the first reboiler, the gas outlet of the first reboiler is communicated with the inlet of the heat-taking circulation cooler, and the outlet of the heat-taking circulation cooler is communicated with the cooling medium inlets of the deisobutanizer and the normal butane-removing condenser;

preferably, the cooling medium of the circulating heat extraction line comprises a carbon tetra-medium;

preferably, the carbon-tetrad medium in the cooling medium of the circulating heat extraction line is isobutane;

preferably, the compressor comprises roots, centrifugal or screw type, and the reboiler comprises a plate heat exchanger, shell and tube heat exchanger or forced circulation heat exchanger.

Compared with the prior art, the utility model has the following technical effects:

the double-tower rectification system for the alkylation reaction product adopts a rectification system combined by a circulating heat extraction line and a reboiler in the tower as a refining scheme of double-tower rectification, compared with a single-tower system, the double-tower rectification system for the alkylation reaction product adjusts the communication mode of a plurality of groups of parallel reboilers at the bottom of the single-tower, can effectively utilize heat energy, improve reboiling efficiency and separation efficiency, has high utilization rate and purification efficiency for the alkylation reaction product, and can obtain the alkylation gasoline product with high isooctane purity and high product quality, reduce the number of tower plates of the single tower, reduce the height of the tower and facilitate subsequent maintenance treatment. The gas phase waste heat at the tops of the deisobutanizer and the normal butane removing tower is fully utilized, the gas phase at the tops of the deisobutanizer and the normal butane removing tower is communicated with the condenser for heat exchange, so that the cooling medium in the circulating heat extraction line is vaporized, the vaporized gas medium is used as the heat source of the reboiler, the reboiler steam consumption required by the deisobutanizer is effectively reduced, and the cost is reduced.

Furthermore, a cooling medium in the circulating heat extraction line exchanges heat with the condenser, so that a tower top cooler in the prior art is replaced, and the consumption of circulating water is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic diagram of the two-column rectification system for alkylate in example 1;

FIG. 2 is a schematic diagram of a conventional alkylated product single column rectification process scheme in comparative example 1;

description of reference numerals: 1-alkylation reaction product feed line; 2-deisobutanizer; 3-a compressor; 4-deisobutanizer condenser; 5-a first steam reboiler; 6-a second steam reboiler; 7-n-butane removing tower; 8-n-butane removing condenser; 9-a third steam reboiler; 10-mixture strand; 11-isobutane product discharge line; discharging a 12-n-butane product line; 13-alkylate gasoline product draw line; 14-cyclic heat extraction line; 15-circulating heat-taking cooler; 16-deisobutanizer; 17-overhead condenser; 18-overhead reflux drum; 19-reflux pump; a 20-isobutane cooler; 21-bottom reboiler.

Detailed Description

The utility model will be further explained with reference to the drawings. The experimental procedures used in the following examples are all conventional procedures unless otherwise specified. The devices, materials, reagents and the like used in the following examples are commercially available unless otherwise specified. In the description of the present invention, the terms of direction or positional relationship indicated by the terms "upper", "lower", "left", "right", "inside", "outside", and the like are based on the directions or positional relationships shown in the drawings, which are merely for convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

The utility model aims to provide an alkylation reaction product double-tower rectification system, which is used for solving the technical problems in the prior art, reducing high energy consumption and high cost in the rectification process of the alkylation reaction product and facilitating the later maintenance of a double-tower structure.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

As shown in fig. 1, the present embodiment provides a two-tower rectification system for an alkylation reaction product, which includes an isobutane removing tower 2, an n-butane removing tower 7, a reboiler and a circulating heat removal line 14, wherein the upper part of the isobutane removing tower 2 is provided with an alkylation reaction product feeding line 1, and the reboiler is used for heating materials in the isobutane removing tower 2 and/or the n-butane removing tower 7; the bottom of the deisobutanizer 2 is communicated with the middle of the normal butane removal tower 7 through a deisobutanizer bottom mixture material line 10, so that the reboiling efficiency and the separation efficiency are improved; the bottom of the n-butane removing tower 7 is communicated with an alkylated gasoline product discharging line 13; the heat-exchanging tube side of the circulating heat-taking line 14 is connected with the deisobutanizer 4 and the normal butane-removing condenser 8, the medium in the circulating heat-taking line 14 is used as the cooling medium of the gas at the top of the deisobutanizer 2 and the gas at the top of the normal butane-removing tower 7, the heat is obtained and vaporized by the deisobutanizer 4 and the normal butane-removing condenser 8, and then the heat enters the reboiler to be condensed and discharged, thereby effectively reducing the steam consumption required by the system and reducing the cost.

The top of the deisobutanizer 2 is communicated with an isobutane inlet of the deisobutanizer 4, an isobutane outlet pipeline of the deisobutanizer 4 is divided into two parts, one line reflows to the upper part of the deisobutanizer 2, the position of a reflow opening on the tower wall is higher than the position of an alkylation reaction product feeding line, and the other line is an isobutane product discharging line 11; the top of the n-butane removing tower 7 is communicated with an n-butane removing condenser 8, an n-butane outlet pipeline of the n-butane removing condenser 8 is divided into two parts, one line reflows to the upper part of the n-butane removing tower 7, and the other line is an n-butane product discharging line 12; the cooling medium inlets of the deisobutanizer 4 and the normal butane removing condenser 8 are used for introducing cooling medium of the circulating heat taking line 14, the cooling medium outlets of the deisobutanizer 4 and the normal butane removing condenser 8 are communicated with the inlet of the compressor 3, the compressor 3 is compressed, further heated and pressurized, and then partially condensed in the first reboiler 5 to release heat, so that the steam consumption of a steam reboiler at the bottom of the deisobutanizer tower is effectively reduced, the cost is reduced, and then the circulating heat taking cooler 15 is used for condensing all the medium in the circulating heat taking line 14 into a liquid phase to enter the next circulation.

The first reboiler 5 is communicated with a middle discharge hole of the deisobutanizer 2 through a feeding pipeline, the first reboiler 5 is communicated with a middle feeding hole of the deisobutanizer 2 through a discharging pipeline, a middle discharge hole of the deisobutanizer 2 is arranged below the middle feeding hole, the second reboiler 6 is communicated with a bottom discharge hole of the deisobutanizer 2 through a feeding pipeline, the second reboiler 6 is communicated with a lower feeding hole of the deisobutanizer 2 through a discharging pipeline, a bottom discharge hole of the deisobutanizer 2 is arranged below the lower feeding hole, the third reboiler 6 is communicated with a bottom discharge hole of the n-butane removal tower 7 through a feeding pipeline, the third reboiler 6 is communicated with a lower feeding hole of the n-butane removal tower 7 through a discharging pipeline, and a bottom discharge hole of the n-butane removal tower 7 is arranged below the lower feeding hole.

The cooling medium in the circulating heat extraction line 14 is a carbon four medium comprising isobutane, the gasification temperature of the carbon four medium is low, the carbon four medium has high vaporization latent heat capacity, and the carbon four medium is suitable for serving as a refrigerant, replaces a tower top cooler in the prior art, and reduces circulating water consumption.

The compressor 3 is Roots type, centrifugal type or screw type, and the reboiler is a plate heat exchanger, shell-and-tube heat exchanger or forced circulation heat exchanger.

Taking an alkylation reaction product obtained by an alkylation device in a certain refinery as an example, the alkylated gasoline (isooctane) product at the bottom of the tower is required to meet the requirement. Annual operating time 8400 h.

The alkylation reaction product composition is shown in table 1 (mass percent).

TABLE 1 composition of isooctane and isobutane mixture

Example 2

This example employed the alkylation reaction product two-column rectification system of example 1, using the process scheme shown in figure 1. The preparation condition parameters related in this embodiment are described below in a unified manner, and are not described again in detail:

the alkylation reaction product (323K, 2.0MPa (G)) enters an isobutane removal tower for rectification, and gas-phase isobutane at the top of the tower (326K, 0.63MPa (G)) is cooled by a circulating carbon four-medium (313K, 0.5MPa (G)). The gas phase at the top of the tower is cooled by a condenser of the deisobutanizer and then divided into two parts, one part is taken as an isobutane product (324K) to be pumped out, and the other part flows back to the upper part of the deisobutanizer. The middle part of the deisobutanizer is provided with a first reboiler, and the bottom of the deisobutanizer is provided with a second steam reboiler. The mixed material at the bottom of the deisobutanizer enters a deisobutanizer to remove n-butane, and gas-phase n-butane (331K, 0.42MPa (G)) at the top of the deisobutanizer is cooled by a circulating carbon four-medium (313K, 0.5MPa (G)). The gas phase at the top of the tower is cooled by a condenser of the n-butane removing tower and then divided into two parts, wherein one part is extracted as a n-butane (327K) product, and the other part is refluxed to the upper part of the n-butane removing tower.

And the circulating carbon four medium exchanges heat with the gas phase at the top of the tower for vaporization, enters a first reboiler of the deisobutanizer as a heat source after being compressed by a compressor (351K, 1.4MPa (G)) to exchange heat with the liquid extracted from the middle section of the tower, and the liquid discharged from the middle section of the deisobutanizer is gasified by a reboiler and then returns to the deisobutanizer. The circulating carbon four-medium is cooled to (313K) by a circulating heat-taking cooler and then recycled.

The bottoms of the deisobutanizer and the normal butane removing tower use 1.0MPa (G) steam as a heat source. The mixture (407K, 0.69MPa (G)) extracted from the bottom of the deisobutanizer enters a deisobutanizer for rectification. Obtaining an alkylated gasoline product (418K, 0.46MPa (G)) at the bottom of the tower after the rectification of the n-butane removing tower.

The operation pressure of the deisobutanizer is 0.63MPa, the temperature of the tower top is 326K, and the temperature of the tower bottom is 407K.

The operating pressure of the n-butane removing tower is 0.42MPa, the tower top temperature is 331K, and the tower bottom temperature is 418K.

The compressor is a centrifugal compressor.

The deisobutanizer and the normal butane removing tower are plate towers or packed towers.

Comparative example 1

Comparative example 1A conventional single-column rectification process was used, 1.0MPa (G) steam was used as a heat source at the bottom of the column, a portion of isobutane at the top of the column was used for the internal circulation of the column, a portion of isobutane was used as a product withdrawal device, n-butane was withdrawn at the side line in the column, and mixed isooctane (product alkylate) was withdrawn at the bottom of the column. The flow of the conventional single column rectification process of comparative example 1 is shown in FIG. 2.

The utility consumption of each process equipment in the conventional single-column rectification process of comparative example 1 and the double-column rectification system of the example 2 is detailed as shown in the following table:

TABLE 2 summary of consumption of conventional single-column rectification utilities in COMPARATIVE EXAMPLE 1

TABLE 3 Utility consumption List for the double column rectification System of example 2

As can be seen from tables 2 and 3: compared with the comparative example 1, the method has the advantages that the circulating water consumption of the cooling equipment is remarkably saved by adopting the embodiment 2, one reboiler is heated by adopting the circulating heat extraction line, and the steam consumption of other reboilers in the system is reduced.

Comparative example 1 utility consumption of the conventional rectification process versus the rectification system of this example 2 is shown in table 4 below (annual operating time 8400 h).

TABLE 4 comparison of Utility consumption of example 2 and comparative example 1

As can be seen from table 4 above: compared with the comparative example 1, the energy consumption of circulating water and steam of the whole system is remarkably saved by adopting the embodiment 2.

Comparative example 1 the operating costs of the conventional distillation process and the distillation system process of example 2 are compared as shown in table 5 below.

TABLE 5 comparison of operating costs for example 2 and comparative example 1

As can be seen from table 5 above: although the present example 1 is higher in the operation cost of electricity than the comparative example 1, the present example 1 provides a great saving in the operation cost compared to the comparative example 1 in comparison with the total operation cost of the entire system.

In contrast to example 1, the conventional rectification process employed in comparative example 1 did not include a compressor, a first reboiler, and a recycle heat-withdrawing line and corresponding connecting lines. A plurality of groups of parallel reboilers at the bottom of the conventional single-tower rectification process are adjusted into a first reboiler which exchanges heat with a circulating heat extraction line, a second reboiler which is respectively arranged at the bottom of the deisobutanizer and a third reboiler which is arranged at the bottom of the normal butane removal tower in the middle of the deisobutanizer, so that heat energy can be effectively utilized, and reboiling efficiency and separation efficiency are improved. In the traditional single-tower rectification process in the comparative example 1, the number of tower plates is 70, and the height of the tower is 50 m; in the embodiment 1, the number of the deisobutanizer tower plates is 40, the tower height is 28m, the number of the deisobutanizer tower plates is 20, the tower height is 18m, the number of the tower plates can be reduced, the height of the rectifying tower is reduced, and the later-stage production maintenance is facilitated.

The principle and the implementation mode of the present invention are explained by applying specific examples in the present specification, and the above descriptions of the examples are only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the utility model.

Claims (7)

1. A double-tower rectification system for alkylation reaction products is characterized by comprising an isobutane removing tower, an n-butane removing tower, a reboiler and a circulating heat extraction line; the upper part of the deisobutanizer is communicated with an alkylation reaction product feeding line, the reboiler is used for heating materials in the deisobutanizer and/or the n-butane removing tower, the bottom of the deisobutanizer is communicated with the middle of the n-butane removing tower, the bottom of the n-butane removing tower is communicated with an alkylated gasoline product discharging line, and the circulating heat-taking line is used for taking the gas discharged from the top of the deisobutanizer and the heat in the gas discharged from the top of the n-butane removing tower as heat sources of the reboiler.

2. The double-tower rectification system for the alkylation reaction product according to claim 1, wherein the circulating heat-extracting line comprises an deisobutanizer, a normal butane-removing condenser and a compressor, a top discharge port of the deisobutanizer is communicated with an isobutane inlet of the deisobutanizer, a top discharge port of the normal butane-removing tower is communicated with a normal butane inlet of the normal butane-removing condenser, an isobutane outlet of the deisobutanizer is connected and communicated with an isobutane return line and an isobutane product discharge line, the isobutane return line is communicated with a return port formed in the upper portion of the deisobutanizer, a normal butane outlet of the normal butane-removing condenser is connected and communicated with a normal butane return line and a normal butane product discharge line, the normal butane return line is communicated with a return port formed in the upper portion of the normal butane-removing tower, and cooling medium inlets of the deisobutanizer and the normal butane-removing condenser are used for introducing the circulating heat-extracting line A cooling medium of the line, the cooling medium outlets of the deisobutanizer and denotane condenser being in communication with the inlet of the compressor, the outlet of the compressor being in communication with the at least one reboiler gas inlet.

3. The alkylation reaction product double-tower rectification system according to claim 2, wherein the reboiler is used for heating the material in the deisobutanizer or the normal butane removal tower, the plurality of reboilers are respectively a first reboiler, a second reboiler and a third reboiler, the first reboiler is communicated with the middle discharge port of the deisobutanizer through a feeding pipeline, the first reboiler is communicated with the middle feeding port of the deisobutanizer through a discharging pipeline, the middle discharge port of the deisobutanizer is arranged below the middle feeding port, the second reboiler is communicated with the bottom discharge port of the deisobutanizer through a feeding pipeline, the second reboiler is communicated with the lower feeding port of the deisobutanizer through a discharging pipeline, and the bottom discharge port of the deisobutanizer is arranged below the lower feeding port, the third reboiler through a pan feeding pipeline with take off n-butane tower bottom discharge gate intercommunication, the third reboiler through a discharge pipeline with take off n-butane tower lower part pan feeding mouth intercommunication, take off n-butane tower bottom discharge gate and set up in lower part pan feeding mouth below.

4. The alkylation reaction product two-tower rectification system according to claim 3, wherein the outlet of the compressor is in communication with the gas inlet of the first reboiler, the gas outlet of the first reboiler is in communication with the inlet of a heat recovery cycle cooler, and the outlet of the heat recovery cycle cooler is in communication with the cooling medium inlets of the deisobutanizer and the denotane condenser.

5. The double column rectification system of alkylation reaction product according to claim 1, wherein the cooling medium of the circulating heat-withdrawing line comprises carbon tetra medium.

6. The alkylation reaction product double column rectification system of claim 5, wherein the carbon tetramedium in the cooling medium of the circulating heat extraction line is isobutane.

7. The alkylation reaction product double column rectification system according to claim 2, wherein the compressor is a roots-type compressor, a centrifugal compressor or a screw compressor, and the reboiler is a plate heat exchanger, a shell-and-tube heat exchanger or a forced circulation heat exchanger.

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