Alkylation unit with circulating refrigerant impurity removal function

Abstract

The application discloses an alkylation device with a circulating refrigerant impurity removal function, which comprises an alkali washing assembly, a water washing assembly, a depropanizing tower and a deisobutane tower; the alkali washing assembly and the water washing assembly are connected in series on a circulating refrigerant feeding conveying pipe; a water washing assembly discharge port is in pipeline communication with a depropanizing tower feeding inlet; and a depropanizing tower lower discharge port is in pipeline communication with a deisobutane tower feeding inlet. The device can remove SO2, sulfides such as mercaptans and free water in the circulating refrigerant of the alkylation device, thereby effectively reducing the plugging frequency of the depropanizing tower, improving the propane removal efficiency of the alkylation device system, avoiding the increase of the content of propane in the system, maintaining a better alkylene ratio in the circulating material and improving the quality of the obtained isooctane product.

Description

Technical Field

[0001] This application relates to the field of petrochemical technology, and in particular to an alkylation unit with a circulating refrigerant purification function. Background Technology

[0002] The propane removal tower of the sulfuric acid alkylation unit is used to maintain the propane content balance of the system and meet the alkane-to-olefin ratio balance of the feed to the alkylation reactor. It maintains the propane balance of the entire system by continuously removing some propane from the circulating refrigerant; at the same time, it removes the residual propane from the saturated liquefied gas, and the remaining isobutane is added to the alkylation reactor to maintain the alkane-to-olefin ratio balance of the system.

[0003] The circulating refrigerant used in existing alkylation units is fed directly into the propane stripper without any treatment, which presents the following problems:

[0004] 1. Directly introducing circulating refrigerant into the alkylation unit will cause scaling and blockage of multiple trays in the sulfuric acid alkylation unit's propane removal tower on average every 60 days, resulting in a short operating cycle for the propane removal tower.

[0005] 2. Untreated circulating refrigerant entering the system will cause a decrease in the propane removal efficiency of the alkylation unit system, and the alkane-to-olefin ratio of the system will not meet the requirements.

[0006] 3. Due to the decreased propane removal efficiency, the propane content in the materials processed by the system increases, resulting in a high load on the refrigerant compressor and increased power consumption. At the same time, the alkane-to-olefin ratio in the circulating material cannot meet the requirements, leading to a decrease in the quality of the final isooctane product.

[0007] 4. The alkylation unit is a continuous production unit. When the depropanizer tower becomes blocked, it is necessary to frequently repair the depropanizer tower, which affects the production load.

[0008] The information disclosed in the background section is intended only to enhance the understanding of the overall background of this utility model and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Utility Model Content

[0009] This application addresses the aforementioned technical problems by providing an alkylation device with a circulating refrigerant for impurity removal. This device can reduce scaling inside the propane stripper, reduce maintenance frequency, lower energy consumption, improve product separation efficiency, and enhance product quality.

[0010] This application provides an alkylation device with a circulating refrigerant purification function, including: an alkaline washing assembly, a water washing assembly, a propane removal tower, and an isobutane removal tower;

[0011] The alkaline washing assembly and the water washing assembly are connected in series on the circulating refrigerant feed conveying pipe; the outlet of the water washing assembly is connected to the inlet pipe of the propane stripping tower; the lower outlet of the propane stripping tower is connected to the inlet pipe of the isobutane stripping tower.

[0012] The reflux pipe assembly outlet of the propane stripper is connected to the propane storage tank;

[0013] The reflux pipe assembly outlet of the isobutane removal tower is connected to the pipeline of the alkylation reactor.

[0014] Preferably, the alkaline washing assembly includes: a first coalescer, a first mixer, and a first circulating pump; the feed inlet of the first coalescer is provided with a pipeline connected to the circulating refrigerant conveying pipe, and the first mixer is provided on the pipeline; the raw material feed inlet of the first mixer is connected to the C4 conveying pipe;

[0015] The inlet of the first circulating pump is connected to the circulating outlet of the first coalescer; the outlet of the first circulating pump is connected to the circulating refrigerant delivery pipe.

[0016] Preferably, the alkaline washing assembly includes: a first discharge valve; the outlet of the first coalescer is connected to the inlet pipe of the water washing assembly, and the first discharge valve is installed on the connected pipe.

[0017] Preferably, the water washing assembly includes: a second coalescer, a second mixer, and a second circulating pump; the inlet of the second coalescer is provided with a pipeline connected to the outlet of the alkaline washing assembly, and the second mixer is provided on the pipeline;

[0018] The raw material inlet of the second mixer is connected to the C4 conveying pipe;

[0019] The inlet of the second circulation pump is connected to the circulation outlet of the second coalescer; the outlet of the second circulation pump is connected to the pipeline connecting the alkaline washing component and the water washing component.

[0020] Preferably, the water washing assembly includes: a second discharge valve; the outlet of the second coalescer is connected to the inlet pipeline of the propane stripper, and the second discharge valve is installed on the connected pipeline.

[0021] Preferably, it includes: a saturated liquefied gas conveying pipe; one end of the saturated liquefied gas conveying pipe is connected to a saturated liquefied gas storage tank, and the other end of the saturated liquefied gas conveying pipe is connected to a pipeline that connects to a water washing assembly and a propane removal tower.

[0022] Preferably, the propane stripper includes: a tower body, trays, and a spray assembly; multiple trays are longitudinally spaced within the tower body; a spray assembly is installed in the upper part of the tower body; and the outlet at the bottom of the tower body is connected to the inlet pipeline of the isobutane stripper.

[0023] Preferably, the propane removal tower includes: a cooler, a reflux tank, a reflux pump, and a reflux valve; the cooler is connected to the evaporation port at the top of the tower via a pipeline; the liquid outlet of the cooler is connected to the feed inlet of the reflux tank via a pipeline.

[0024] The outlet of the reflux tank is connected to the inlet pipe of the reflux pump;

[0025] A return branch pipe and a delivery pipe are installed at the outlet of the return pump;

[0026] The delivery pipe is connected to the propane storage tank, and the return branch pipe is connected to the feed inlet of the spray assembly of the depropane tower.

[0027] Preferably, the propane removal tower includes a reflux valve; the reflux valve is installed on the reflux branch pipe.

[0028] Preferably, the isobutane removal tower includes: a tower body, tower plates, and a spray assembly; multiple tower plates are longitudinally spaced within the tower body; a spray assembly is installed in the upper part of the tower body; and the outlet at the bottom of the tower body is connected to the inlet pipeline of the isobutane removal tower.

[0029] The beneficial effects that this application can produce include:

[0030] 1) The alkylation device with circulating refrigerant impurity removal function provided in this application can remove SO2, mercaptan and other sulfides from the circulating refrigerant of the alkylation device, and can also remove free water from the circulating refrigerant, thereby effectively reducing the clogging frequency of the propane removal tower, improving the propane removal efficiency of the alkylation device system, avoiding the increase of propane content in the material processed by the system, maintaining a good alkane-to-olefin ratio in the circulating material, and improving the quality of the final isooctane product.

[0031] 2) The alkylation unit with circulating refrigerant impurity removal function provided in this application can solve the problem of scaling and clogging of the trays in the depropanizer; removing impurities before the circulating refrigerant of the alkylation unit enters the depropanizer can effectively ensure the normal removal of propane from the system, while ensuring long-term operation of the depropanizer of the sulfuric acid alkylation unit and reducing the frequency of shutdown and maintenance.

[0032] 3) The alkylation unit with circulating refrigerant impurity removal function provided in this application removes impurities from the circulating refrigerant before it enters the propane stripper. This ensures that the plates and float valves of the propane stripper do not become scaled or clogged, reduces the occurrence of blockages, ensures long-term operation of the propane stripper, stably maintains the propane balance and alkane-to-olefin ratio balance of the alkylation unit system, ensures the quality of isooctane products, and at the same time reduces the operating load of the refrigerant compressor, reduces power consumption, and increases the reactor load of the alkylation unit. Attached Figure Description

[0033] Figure 1A schematic diagram of an alkylation apparatus with a circulating refrigerant impurity removal function in at least one embodiment provided in this application;

[0034] Figure 2 The following are before-and-after comparison images of the apparatus in at least one embodiment provided in this application: a is an internal photograph of the propane stripper after 35 days of operation before using the apparatus; b is a photograph of the disassembled and inspected components of the propane stripper after 35 days of operation before using the apparatus; c is an internal photograph of the propane stripper after 2 years of operation after using the apparatus; d is a photograph of the inspected components of the propane stripper after 2 years of operation after using the apparatus.

[0035] Legend:

[0036] First circulation pump 1, second circulation pump 11, first coalescer 21, second coalescer 22

[0037] First mixer 222, second mixer 223

[0038] First discharge valve 224, second discharge valve 225

[0039] Propane removal tower 23, tray 231, spray assembly 232

[0040] Isobutane removal tower 243, cooler 241, reflux tank 242, reflux pump 12, reflux valve 125. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0042] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0043] Technical means not detailed in this application and not used to solve the technical problems of this application are all set according to common general knowledge in the field, and multiple common general knowledge setting methods can be implemented.

[0044] See Figure 1The alkylation apparatus with circulating refrigerant impurity removal function provided in this application includes: an alkali washing assembly, a water washing assembly, a propane stripping tower 23, and an isobutane stripping tower 243; the alkali washing assembly and the water washing assembly are connected in series on the circulating refrigerant feed conveying pipe; the outlet of the water washing assembly is connected to the inlet pipe of the propane stripping tower 23; the lower outlet of the propane stripping tower 23 is connected to the inlet pipe of the isobutane stripping tower 243.

[0045] The reflux pipe assembly of the propane stripper 23 outputs propane to a propane storage tank (not shown in the diagram) via pipeline; the reflux pipe assembly of the isobutane stripper 243 outputs isobutane to the alkylation reactor for alkylation reaction via pipeline. The discharge port at the bottom of the isobutane stripper 243 outputs the debutane product, which contains n-butane, isobutane, and other substances.

[0046] Using this device can effectively prevent blockage in the propane stripper 23. (See [link]) Figure 2 From a to d, it can be seen that before using this device, see [reference]. Figure 2 After 35 days of operation, the propane stripper 23 of the a-b alkylation unit developed severe scaling inside. The image shows the disassembly and inspection of the blockage during maintenance, indicating severe blockage inside the unit.

[0047] See Figure 2 Images c-d show disassembled and inspected components inside the propane stripper 23 of the alkylation unit after two years of use. The absence of obvious structures on the surface of each component indicates that the device can effectively reduce scaling inside the propane stripper 23 and reduce the occurrence of blockages.

[0048] Tables 1-3 compare the operating conditions of the alkylation unit before and after using this device. Table 1 shows a comparison of the operating cycles of the propane stripper before and after using this device.

[0049] Table 1

[0050]

[0051] As shown in Table 1, after using the device provided in this application, the operating time is effectively extended and the number of maintenance operations is effectively reduced; the required saturated liquefied gas processing capacity of the device is effectively increased; the circulating coolant processing capacity is also larger, and the propane removal capacity is larger.

[0052] Table 2 compares the production load and energy consumption of the alkylation unit before and after using this device:

[0053] Table 2

[0054]

[0055]

[0056] As shown in Table 2, the average load of the alkylation unit is increased after adopting the device provided in this application, and the propane content produced by the alkylation unit is effectively reduced, thereby effectively improving product quality; power consumption is also reduced.

[0057] Table 3 shows the economic benefits of using this device to purify the feed of the alkylation depropanizer tower.

[0058] Table 3

[0059]

[0060] As can be seen from Table 3, using the device provided in this application can effectively improve economic benefits and reduce production costs.

[0061] In one specific embodiment, the alkaline washing assembly includes: a first coalescer 21, a first mixer 222, and a first circulating pump 1; the inlet of the first coalescer 21 is provided with a pipeline connected to the circulating refrigerant conveying pipe, and the first mixer 222 is installed on the pipeline; the raw material inlet of the first mixer 222 is connected to the C4 conveying pipe; thereby realizing that the raw material C4 is mixed with the circulating refrigerant and enters the first coalescer 21, and fully contacts the sodium hydroxide solution with a concentration of about 6% in the first coalescer 21, thereby realizing the removal of impurities in the circulating refrigerant; the inlet of the first circulating pump 1 is connected to the circulating outlet pipeline of the first coalescer 21; the outlet of the first circulating pump 1 is connected to the circulating refrigerant conveying pipe; realizing the circulation and impurity removal of materials in the first coalescer 21.

[0062] In one specific embodiment, the alkaline washing assembly includes: a first discharge valve 224; the discharge port of the first coalescer 21 is connected to the inlet pipe of the water washing assembly, and the first discharge valve 224 is installed on the connected pipe. By setting the first discharge valve 224, the discharge of the first coalescer 21 can be effectively controlled, ensuring that the discharge meets the impurity removal requirements.

[0063] In one specific embodiment, the water washing assembly includes: a second coalescer 22, a second mixer 223, and a second circulating pump 11. The inlet of the second coalescer 22 is connected to a pipeline that communicates with the outlet of the alkaline washing assembly, and the second mixer 223 is installed on this pipeline. The raw material inlet of the second mixer 223 is connected to a C4 conveying pipe. This allows the raw material C4 to be mixed with the circulating refrigerant after primary impurity removal before entering the second coalescer 22. After entering the second coalescer 22, the raw material C4 comes into full contact with the demineralized water, thus achieving secondary removal of impurities from the circulating refrigerant. The inlet of the second circulating pump 11 is connected to the circulating outlet pipeline of the second coalescer 22. The outlet of the second circulating pump 11 is connected to a pipeline connecting the alkaline washing assembly and the water washing assembly, enabling the material to circulate and remove impurities in the second coalescer 22.

[0064] In one specific embodiment, the washing assembly includes: a second discharge valve 225; the outlet of the second coalescer 22 is connected to the inlet pipeline of the propane removal tower 23, and the second discharge valve 225 is installed on the connected pipeline. By setting the second discharge valve 225, effective control of the discharge from the second coalescer 22 is achieved, ensuring that the discharge meets the impurity removal requirements.

[0065] In one specific embodiment, the system includes: a saturated liquefied petroleum gas (LPG) delivery pipe; one end of the saturated LPG delivery pipe is connected to a saturated LPG storage tank (not shown in the figure), and the other end of the saturated LPG delivery pipe is connected to a pipeline connecting the water washing assembly and the propane removal tower 23. This allows saturated LPG to be added during the feeding of the propane removal tower 23.

[0066] The coalescer used in this application is a Type II coalescer manufactured by Sulzer.

[0067] In one specific embodiment, the propane stripping tower 23 includes: a tower body, trays 231, and a spray assembly 232; multiple trays 231 are longitudinally spaced within the tower body; the spray assembly 232 is installed in the upper part of the tower body; the outlet at the bottom of the tower body is connected to the inlet pipe of the isobutane stripping tower 243. The structure of the propane stripping tower 23 is not described in detail and differs from existing... The alkylation reactor setup is the same and will not be described in detail here.

[0068] In one specific embodiment, the propane stripper 23 includes: a cooler 241, a reflux tank 242, a reflux pump 12, and a reflux valve 125; the cooler 241 is connected to the evaporation port at the top of the tower; the outlet of the cooler 241 is connected to the inlet of the reflux tank 242; the outlet of the reflux tank 242 is connected to the inlet of the reflux pump 12; a reflux branch pipe and a delivery pipe are provided on the outlet of the reflux pump 12; the delivery pipe is connected to a propane storage tank, and the reflux branch pipe is connected to the inlet of the spray assembly 232 of the propane stripper 23. This achieves control of the reflux ratio within the propane stripper 23.

[0069] In one specific embodiment, the propane stripper 23 includes a reflux valve 125; when the reflux ratio reaches the required level and the discharge requirements are met, the reflux valve 125 is opened to discharge propane. The reflux valve 125 is installed on the reflux branch pipe.

[0070] In one specific embodiment, the isobutane removal tower 243 includes: a tower body, tower plates 231, and a spray assembly 232; multiple tower plates 231 are longitudinally spaced within the tower body; the spray assembly 232 is installed in the upper part of the tower body; the outlet at the bottom of the tower body is connected to a butane removal product storage tank (not shown in the figure) via a pipeline. The structure of the propane removal tower 23 is not described in detail and differs from existing... The alkylation reactor setup is the same and will not be described in detail here.

[0071] In one specific embodiment, the isobutane removal tower 243 includes: a cooler 241, a reflux tank 242, a reflux pump 12, and a reflux valve 125; the cooler 241 is connected to the evaporation port at the top of the tower; the outlet of the cooler 241 is connected to the inlet of the reflux tank 242; the outlet of the reflux tank 242 is connected to the inlet of the reflux pump 12; a reflux branch pipe and a delivery pipe are provided on the outlet of the reflux pump 12; the delivery pipe is connected to the alkylation reactor pipeline, and the reflux branch pipe is connected to the inlet of the spray assembly 232 of the propane removal tower 23. This achieves control of the reflux ratio within the propane removal tower 23.

[0072] In one specific embodiment, the isobutane removal tower 243 includes a reflux valve 125; when the reflux ratio reaches the required level and the discharge requirements are met, the reflux valve 125 is opened to discharge the material. The reflux valve 125 is installed on the reflux branch pipe.

[0073] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An alkylation apparatus with a circulating refrigerant impurity removal function, characterized in that, The alkali washing assembly, the water washing assembly, the depropanizer (23), and the deisobutanizer (243) are connected in series on the circulating refrigerant feeding pipe. The water washing assembly is connected to the depropanizer (23) through a pipe. The depropanizer (23) is connected to the deisobutanizer (243) through a pipe. The deisobutanizer (243) is connected to the alkylation reactor through a pipe. The alkali washing assembly comprises a first coalescer (21), a first mixer (222), and a first circulating pump (1).

2. The alkylation unit with a circulating refrigerant impurity removal function according to claim 1, characterized in that, The first circulating pump (1) is connected to the first coalescer (21) through a pipe. The alkali washing assembly comprises a first discharge valve (224).

3. The alkylation unit with a circulating refrigerant impurity removal function according to claim 2, characterized in that, The water washing assembly comprises a second coalescer (22), a second mixer (223), and a second circulating pump (11).

4. The alkylation unit with a circulating refrigerant impurity removal function according to claim 1, characterized in that, The second circulating pump (11) is connected to the second coalescer (22) through a pipe. The water washing assembly comprises a second discharge valve (225). The water washing assembly is connected to the depropanizer (23) through a pipe.

5. The alkylation unit with a circulating refrigerant impurity removal function according to claim 4, characterized in that, The saturated liquefied gas feeding pipe is connected to the water washing assembly and the depropanizer (23) through a pipe.

6. The alkylation unit with a circulating refrigerant impurity removal function according to claim 1, characterized in that, The depropanizer (23) comprises a tower body, tower plates (231), and a spraying assembly (232). The depropanizer (23) comprises a cooler (241), a reflux tank (242), a reflux pump (12), and a reflux valve (125).

7. The alkylation unit with a circulating refrigerant impurity removal function according to claim 1, characterized in that, The reflux pump (12) is connected to the reflux tank (242) through a pipe.

8. The alkylation unit with a circulating refrigerant impurity removal function according to claim 7, characterized in that, The reflux pump (12) is connected to the deisobutanizer (243) through a pipe. ​ ​ The delivery pipe is connected to the propane storage tank, and the return branch pipe is connected to the feed inlet of the spray assembly (232) of the depropane tower (23).

9. The alkylation unit with a circulating refrigerant impurity removal function according to claim 1, characterized in that, The propane removal tower (23) includes: a reflux valve (125); the reflux valve (125) is installed on the reflux branch pipe.

10. The alkylation unit with a circulating refrigerant impurity removal function according to claim 1, characterized in that, The isobutane removal tower (243) includes: a tower body, a tower plate (231), and a spray assembly (232); multiple tower plates (231) are arranged longitudinally at intervals in the tower body; a spray assembly (232) is arranged in the upper part of the tower body; the outlet at the bottom of the tower body is connected to the inlet pipe of the isobutane removal tower (243).

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