External heat extraction alkylation capacity expansion system

Abstract

The utility model provides an external heat extraction alkylation capacity expansion system which comprises a feeding pipe, a first heat exchanger, a second heat exchanger, an alkylation reactor, a first compressor, a third heat exchanger, a refrigerant water tank and a refrigerating unit, the feeding pipe sequentially passes through the first heat exchanger and the second heat exchanger, and the second heat exchanger is connected with the inlet end of the alkylation reactor; the outlet end of the alkylation reactor is connected with the first compressor; the second heat exchanger is further connected with a third heat exchanger through a bypass, the third heat exchanger, the refrigerant water tank and the refrigerating unit are sequentially connected to form a circulating water path, a circulating pump is arranged on the circulating water path, and the third heat exchanger is connected with the inlet end of the alkylation reactor. According to the alkylation reactor, the device capacity expansion can be better realized in the allowable range of the airspeed of the reactor by reducing the raw material feeding temperature and the reaction temperature, meanwhile, the refrigeration load can be flexibly adjusted according to the feeding temperature of the alkylation reactor, and the shutdown time is short and the equipment transformation cost is low when the equipment is upgraded.

Description

Technical Field

[0001] This application relates to the technical field of petroleum refining equipment, and particularly relates to a system for expanding the energy capacity of external heat extraction alkylation. Background Art

[0002] Alkylation technology is an important technology for producing clean gasoline. The alkylation gasoline (mainly composed of trimethylpentane) produced by the reaction of isobutane and low-molecular-weight olefins under the action of a strong acid catalyst (usually sulfuric acid or hydrofluoric acid) is a mixture of isoparaffins. Compared with catalytic gasoline containing a large amount of olefins and reformed gasoline containing a large amount of aromatics, it has the advantages of high octane number, small difference between motor octane number and research octane number, low vapor pressure, no olefins and aromatics, and low sulfur content. Blending it into gasoline can dilute and reduce the content of harmful components such as olefins, aromatics, and sulfur in gasoline, and at the same time improve the octane number and anti-knock performance of gasoline. It is the most ideal clean vehicle gasoline component.

[0003] The hydrofluoric acid alkylation unit has the advantages of reacting at room temperature and not requiring a refrigeration system. However, the catalyst hydrofluoric acid has strong corrosiveness and toxicity, and the quality requirements for device materials are higher than those of the sulfuric acid method alkylation unit. Some materials need to use imported Monel alloy. The volatility of hydrofluoric acid is strong, and its impact on the environment is also greater than that of the sulfuric acid method alkylation unit. The sulfuric acid method alkylation unit uses low-temperature reaction and needs to add a refrigeration compression system to meet the reaction conditions. The low-temperature condition relies on the gasification of isobutane in the raw material and recycled isobutane in the reactor to absorb heat. The gasified isobutane is compressed and cooled into liquid-phase isobutane by a refrigeration compressor, and then pumped and recycled back to the reactor to continuously remove the reaction heat. At the same time, a spent acid regeneration facility needs to be set up, but the corrosiveness of its catalyst sulfuric acid and its impact on the environment are smaller than those of hydrofluoric acid.

[0004] Sulfuric acid alkylation and hydrofluoric acid alkylation each have their own characteristics in the process and are widely used. From 1993 to the present, nearly 90% of the alkylation units rebuilt or newly built have adopted the sulfuric acid method process. The main reason is that the safety of the sulfuric acid method alkylation technology is better than that of the hydrofluoric acid method; most acid-related parts can use carbon steel equipment, and the corrosion of the device is controllable; the reaction raw materials do not need to be strictly refined; the cracking and regeneration of alkylation spent acid are complete, and there are no secondary pollution problems such as solid waste and acid-soluble oil. The spent acid regeneration technology is mature and reliable, so it has become the mainstream alkylation technology selected by today's refinery enterprises.

[0005] At present, ethylene projects are being built on a large scale across the country. The cracked C4 by-products in ethylene projects have broadened the raw material sources for sulfuric acid method alkylation raw materials. Because the sulfuric acid method alkylation process involves low-temperature reaction, the most restricted problem is the surplus capacity of the original refrigeration compressor and reactor. Therefore, a system for expanding the energy capacity of external heat extraction alkylation is needed, which is mainly used for expanding the capacity on the basis of existing alkylation units. It has low input cost, strong flexibility, short shutdown time for transformation, and is convenient for enterprises to expand their capacity. Summary of the Utility Model

[0006] To solve the above problems, the present application proposes a system for expanding the capacity of external heat extraction alkylation, which is mainly used for expanding the capacity based on the existing alkylation unit. It has low input cost, strong flexibility, short shutdown time for transformation, and is convenient for enterprises to expand their capacity.

[0007] The present application is achieved through the following technical solutions:

[0008] The present application proposes a system for expanding the capacity of external heat extraction alkylation, including: a feed pipe, a first heat exchanger, a second heat exchanger, an alkylation reactor, a first compressor, a third heat exchanger, a refrigerant water tank, and a refrigeration unit. The feed pipe passes through the first heat exchanger and the second heat exchanger in sequence. The second heat exchanger is connected to the inlet end of the alkylation reactor, and the outlet end of the alkylation reactor is connected to the first compressor. The second heat exchanger is also connected to the third heat exchanger through a bypass. The third heat exchanger, the refrigerant water tank, and the refrigeration unit are connected in sequence to form a circulating water path, and a circulating pump is provided on the circulating water path. The third heat exchanger is connected to the inlet end of the alkylation reactor.

[0009] Further, the refrigeration unit includes an evaporator, a second compressor, and a condenser. The outlet end of the second compressor is connected to the inlet end of the condenser, the outlet end of the condenser is connected to the refrigerant inlet of the evaporator, and the refrigerant outlet of the evaporator is connected to the inlet end of the second compressor.

[0010] Further, the evaporator is provided with a cold water inlet and a cold water outlet. The cold water inlet of the evaporator is connected to the refrigerant water tank through a circulating pump, and the cold water outlet of the evaporator is connected to the third heat exchanger.

[0011] Further, a first regulating valve is provided between the second heat exchanger and the alkylation reactor and between the second heat exchanger and the third heat exchanger.

[0012] Further, the refrigerant water tank is vertically installed, and a nitrogen sealing device is provided above the refrigerant water tank.

[0013] Further, the cold medium outlet of the first heat exchanger is connected to the cold medium inlet of the second heat exchanger.

[0014] Advantages of the present application:

[0015] 1. By reducing the raw material feed temperature and the reaction temperature, it can preferably solve the problem of expanding the capacity of the device within the allowable range of the reactor space velocity. The present utility model is an environmentally friendly and low-cost technical reform scheme that does not require major modification of the original reactor and refrigeration compression system;

[0016] 2. It has strong flexibility and can adapt well to raw material loads. When the raw material procurement volume or product sales are blocked, it can flexibly adjust the external heat extraction refrigeration load without significantly affecting the original refrigeration compressor.

[0017] 3. Due to the large temperature difference between winter and summer outdoors, the refrigeration load can be flexibly adjusted according to the feed temperature of the alkylation reactor. In winter, due to the low outdoor temperature, the refrigeration unit can even be shut down, and production can still be satisfied.

[0018] 4. Since there is no need to transform the original reactor and the original refrigeration compressor, and there is no need for a complete shutdown of the device for transformation, it can be transformed while in production. Only a short shutdown of 2 to 3 days is required when connecting the pipelines, and then it can be transformed and put into trial production. Moreover, the equipment transformation cost is low. Brief Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of the present utility model;

[0020] In the figure: 1 - feed pipe, 2 - first heat exchanger, 3 - second heat exchanger, 4 - alkylation reactor, 5 - first compressor, 6 - third heat exchanger, 7 - refrigerant water tank, 8 - circulation pump, 9 - evaporator, 10 - second compressor, 11 - condenser, 12 - first regulating valve, 13 - second regulating valve. Detailed Implementation Modes

[0021] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Among them, the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.

[0022] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present application are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0023] In addition, the descriptions involving "first", "second", etc. in this application are for descriptive purposes only, and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the said features. In addition, the technical solutions between various embodiments may be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this utility model.

[0024] As Figure 1 shown, an embodiment of the present utility model provides a system for expanding the capacity of external heat extraction alkylation, including: a feed pipe 1, a first heat exchanger 2, a second heat exchanger 3, an alkylation reactor 4, a first compressor 5, a third heat exchanger 6, a refrigerant water tank 7, and a refrigeration unit. The feed pipe 1 sequentially passes through the first heat exchanger 2 and the second heat exchanger 3. The second heat exchanger 3 is connected to the inlet end of the alkylation reactor 4. The outlet end of the alkylation reactor 4 is connected to the first compressor 5. The second heat exchanger 3 is also connected to the third heat exchanger 6 through a bypass. The third heat exchanger 6, the refrigerant water tank 7, and the refrigeration unit are sequentially connected to form a circulating water path. A circulating pump 8 is provided on the circulating water path. The third heat exchanger 6 is connected to the inlet end of the alkylation reactor 4.

[0025] Before the capacity expansion transformation, the liquefied gas raw material is pre-treated and then exchanges heat with the reaction product from the feed pipe 1 through the first heat exchanger 2 and the second heat exchanger 3, and then is sent into the alkylation reactor 4. After the reaction is completed, it is compressed by the first compressor 5 and then cooled by an air cooler.

[0026] After the capacity expansion transformation, the first regulating valve 12 between the second heat exchanger 3 and the alkylation reactor 4 is closed, and the first regulating valve 12 between the second heat exchanger 3 and the third heat exchanger 6 is opened. The liquefied gas raw material is pre-treated and then exchanges heat with the reaction product from the feed pipe 1 through the first heat exchanger 2 and the second heat exchanger 3, and then enters the third heat exchanger 6 through a pipeline to exchange heat with the refrigerant water, and then enters the alkylation reactor 4 for reaction. After the reaction is completed, it is compressed by the first compressor 5 and then cooled by an air cooler. By increasing the refrigeration capacity of the equipment through the third heat exchanger 6, the feed temperature of the raw material entering the alkylation reactor 4 for reaction is reduced, so as to increase the throughput and realize the capacity expansion of the device within the allowable space velocity range of the alkylation reactor 4.

[0027] Since there is no need to transform the original alkylation reactor and the original refrigeration compressor, and there is no need for a full shutdown of the device for transformation, it is possible to carry out the transformation while in production. It only takes a short shutdown of 2 to 3 days for pipeline connection and butting to complete the transformation and put it into trial production.

[0028] In winter, when the outside temperature drops, the load of the refrigeration unit can be reduced or even stopped, which can improve production flexibility and reduce energy consumption. At the same time, when the purchase of raw materials or product sales is blocked, the equipment does not need to be fully produced. At this time, the load of the refrigeration unit can be reduced according to the production situation to reduce the power consumption of the refrigeration unit.

[0029] Preferably, the refrigeration unit includes an evaporator 9, a second compressor 10, and a condenser 11. The outlet end of the second compressor 10 is connected to the inlet end of the condenser 11, the outlet end of the condenser 11 is connected to the refrigerant inlet of the evaporator 9, and the refrigerant outlet of the evaporator 9 is connected to the inlet end of the second compressor 10. After the second compressor 10 compresses the refrigerant, it condenses and liquefies in the condenser 11 and releases heat to the outside. Then the refrigerant enters the evaporator 9 to evaporate and absorbs heat from the outside, so that the temperature of the evaporator 9 is reduced. When the refrigerant water flows through the evaporator 9, it absorbs heat, so that the temperature of the refrigerant water drops to 0°C to -3°C.

[0030] In a preferred embodiment, the evaporator 9 is provided with a cold water inlet and a cold water outlet, the cold water inlet of the evaporator 9 is connected to the refrigerant water tank 7 through the circulation pump 8, and the cold water outlet of the evaporator 9 is connected to the third heat exchanger 6. The refrigerant in the evaporator 9 absorbs heat externally when evaporating, and can absorb heat from the refrigerant water flowing through the evaporator 9, so that the refrigerant water is cooled to 0°C to -3°C, and then the refrigerant water is sent to the third heat exchanger 6 to exchange heat with the raw material to reduce the temperature of the raw material.

[0031] Specifically, a first regulating valve 12 is provided between the second heat exchanger 3 and the alkylation reactor 4 and between the second heat exchanger 3 and the third heat exchanger 6. The first regulating valve 12 can adjust the flow direction of the raw material and the flow ratio of the raw material in different pipelines, so that the factory can produce under different production capacities and different temperature conditions.

[0032] Preferably, the refrigerant water tank 7 is installed vertically, and a nitrogen sealing device is provided above the refrigerant water tank 7. The refrigerant water tank 7 can store refrigerant water and play a buffering role to avoid excessive temperature changes in the condensed water. The nitrogen sealing device fills the upper part with nitrogen to prevent the refrigerant water from entering the air and oxidizing and deteriorating. A second regulating valve 13 is provided on the upper part of the refrigerant water tank 7. The nitrogen pressure on the upper part of the refrigerant water tank 7 can be adjusted by the second regulating valve 13 to keep the air pressure in the refrigerant water tank 7 within a reasonable range.

[0033] In a preferred embodiment, the cold medium outlet of the first heat exchanger 2 is connected to the cold medium inlet of the second heat exchanger 3, so that the first heat exchanger 2 and the second heat exchanger 3 are connected in parallel with each other, and the temperature of the reactants synthesized by the reaction is relatively low. They are sent to the first heat exchanger 2 and the second heat exchanger 3 through pipelines to exchange heat with the raw materials, thereby avoiding waste of cold resources.

[0034] Of course, the present application may have many other implementation manners. Based on this implementation manner, other implementation manners obtained by those of ordinary skill in the art without any creative work all fall within the scope protected by the present application.

Claims

1. A system for expanding the capacity of external heat extraction alkylation, characterized in that, Including: A feed pipe (1), a first heat exchanger (2), a second heat exchanger (3), an alkylation reactor (4), a first compressor (5), a third heat exchanger (6), a refrigerant water tank (7), and a refrigeration unit. The feed pipe (1) passes through the first heat exchanger (2) and the second heat exchanger (3) in sequence. The second heat exchanger (3) is connected to the inlet end of the alkylation reactor (4), and the outlet end of the alkylation reactor (4) is connected to the first compressor (5). The second heat exchanger (3) is also connected to the third heat exchanger (6) through a bypass. The third heat exchanger (6), the refrigerant water tank (7), and the refrigeration unit are connected in sequence to form a circulating water path, and a circulating pump (8) is provided on the circulating water path. The third heat exchanger (6) is connected to the inlet end of the alkylation reactor (4).

2. The system for expanding the capacity of external heat extraction alkylation according to claim 1, wherein The refrigeration unit includes an evaporator (9), a second compressor (10), and a condenser (11). The outlet end of the second compressor (10) is connected to the inlet end of the condenser (11), the outlet end of the condenser (11) is connected to the refrigerant inlet of the evaporator (9), and the refrigerant outlet of the evaporator (9) is connected to the inlet end of the second compressor (10).

3. The system for expanding the capacity of an externally heated alkylation according to claim 2, wherein, The evaporator (9) is provided with a cold water inlet and a cold water outlet. The cold water inlet of the evaporator (9) is connected to the refrigerant water tank (7) through the circulating pump (8), and the cold water outlet of the evaporator (9) is connected to the third heat exchanger (6).

4. A system for expanding the capacity of externally heated alkylation according to claim 1, characterized in that, A first regulating valve (12) is provided between the second heat exchanger (3) and the alkylation reactor (4) and between the second heat exchanger (3) and the third heat exchanger (6).

5. The system for expanding the capacity of external heat extraction alkylation according to claim 1, characterized in that, The refrigerant water tank (7) is vertically installed, and a nitrogen sealing device is provided above the refrigerant water tank (7).

6. The system for expanding the capacity of external heat alkylation according to claim 1, wherein The cold medium outlet of the first heat exchanger (2) is connected to the cold medium inlet of the second heat exchanger (3).

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