Circulating water stepped utilization device of gas separation device

Abstract

The utility model relates to the technical field of gas separation devices, in particular to a circulating water stepped utilization device of a gas separation device. The circulating water stepped utilization device for the gas separation device comprises a depropanizer, a deethanizer, a propylene rectifying tower, a depropanizer top cooler, a depropanizer bottom cooler, a deethanizer top cooler, a propylene rectifying tower top cooler, a propylene rectifying tower bottom cooler and a heat exchanger arranged on a feeding pipe, a cooling water outlet of the propylene rectifying tower top cooler is respectively connected with cooling water inlets of the depropanizing tower top cooler, the deethanizing tower top cooler, the depropanizing tower bottom cooler and the propylene rectifying tower bottom cooler; and a cooling water outlet of the depropanizing tower bottom cooler is connected with a hot water inlet of the heat exchanger. According to the utility model, the circulating cooling water with lower temperature is secondarily recycled through a method that the circulating water is put into use in series, so that the energy consumption of the device is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of gas separation devices, in particular to a circulating water step utilization device for a gas separation device. Background Art

[0002] At present, the gas separation unit of an oil refinery generally adopts a three-tower process flow, which passes the liquid hydrocarbon feedstock through a depropanizer, a deethanizer, and a propylene distillation tower in sequence to produce propylene products that meet quality indicators, as well as by-products such as propane, dry gas, and depropanized oil.

[0003] In the existing gas separation device, the circulating cooling water of the top and bottom coolers of each tower are all designed in parallel. In actual production, due to the different heat loads of each tower, the top pressure of the tower is adjusted by controlling the opening of the circulating water return valve, which leads to a large deviation in the return water temperature of some circulating water coolers. The delivery temperature of each product is controlled between 25 and 40°C, which is a wide range. The product delivery temperature is mostly adjusted by controlling the opening of the circulating water return valve on site. This parallel design of circulating cooling water consumes a large amount of circulating cooling water and the energy consumption of the entire device is high. Utility Model Content

[0004] In view of the deficiencies in the prior art, the purpose of the utility model is to provide a circulating water step utilization device for a gas separation device, which has a simple structure and is easy to operate. By using the circulating water in series, the circulating cooling water with a lower temperature is recycled for a second time to reduce the amount of circulating water. At the same time, the circulating cooling water with a higher temperature is used for preheating raw materials, thereby reducing the amount of steam used and reducing the energy consumption of the device as a whole.

[0005] The utility model discloses a gas separation device circulating water step-by-step utilization device, comprising a depropanizer, a deethanizer, and a propylene distillation tower which are connected in sequence, and a depropanizer top cooler and a depropanizer bottom cooler which are sequentially arranged on a depropanizer top discharge pipe and a bottom discharge pipe, a deethanizer top cooler which is arranged on a deethanizer top discharge pipe, a propylene distillation tower top cooler and a propylene distillation tower bottom cooler which are sequentially arranged on a propylene distillation tower top discharge pipe and a bottom discharge pipe, and a heat exchanger which is arranged on a feed pipe; the cooling water outlet of the propylene distillation tower top cooler is respectively connected to the cooling water inlets of the depropanizer top cooler, the deethanizer top cooler, the depropanizer bottom cooler, and the propylene distillation tower bottom cooler; and the cooling water outlet of the depropanizer bottom cooler is connected to the hot water inlet of the heat exchanger.

[0006] Preferably, the cooling water inlets of the depropanizer top cooler, the deethanizer top cooler, the propylene distillation tower top cooler, the depropanizer bottom cooler, and the propylene distillation tower bottom cooler are all connected to a fresh cooling water inlet pipe. When the cooling water outlet of the propylene distillation tower top cooler is insufficient to provide cooling capacity for other coolers, cooling water can be added to each cooler through the fresh cooling water inlet pipe.

[0007] Preferably, the feed pipe is connected to the feed port of the depropanizer after passing through a heat exchanger and a heater in sequence. After the cooling water is heat exchanged in the bottom cooler of the depropanizer, the temperature is relatively high, and this part of the hot water is used to preheat the raw material, and then heated to the required temperature by the heater.

[0008] Preferably, the depropanizer top discharge port is connected to a depropanizer reflux tank after passing through a depropanizer top cooler, and the depropanizer reflux tank is respectively connected to a depropanizer top reflux port and a deethanizer feed port.

[0009] Preferably, the deethanizer tower top discharge port is connected to the deethanizer tower reflux tank after passing through the deethanizer tower top cooler, and the deethanizer tower reflux tank is connected to the deethanizer tower top reflux port.

[0010] Preferably, the bottom outlet of the deethanizer is connected to the feed inlet of the propylene distillation tower.

[0011] Preferably, the top discharge port of the propylene distillation tower is connected to a reflux tank of the propylene distillation tower after passing through a top cooler of the propylene distillation tower, and the reflux tank of the propylene distillation tower is connected to a top reflux port of the propylene distillation tower.

[0012] The various coolers of the existing gas separation device generally adopt the cooling water parallel connection mode. According to the different heat loads of each tower, the circulating cooling water flow rate in each cooler is quite different. Among them, the circulating cooling water flow rate of the top cooler of the propylene distillation tower is much higher than that of other coolers, and higher than the total circulating cooling water flow rate used by other coolers. At the same time, the cooling water outlet temperature of the top cooler of the propylene distillation tower is about 34°C, which is much lower than the medium temperature (between 45-95°C) required to be cooled by other coolers. Therefore, the utility model considers dividing the cooling water outlet of the top cooler of the propylene distillation tower as the cooling water inlet of other coolers, so as to reduce the amount of circulating cooling water while ensuring that the heat load of each tower remains unchanged.

[0013] In addition, the temperature of the bottom discharge of the depropanizer is about 95°C. After heat exchange with cooling water in the bottom cooler of the depropanizer, the temperature drops to below 35°C. At this time, the temperature of the cooling water after heat exchange can reach between 45-50°C. This part of hot water can be used to preheat the raw materials to reduce the energy consumption of the heater. At the same time, the hot water can be returned to the circulating water cooling system after the temperature is lowered.

[0014] Compared with the prior art, the utility model has the following beneficial effects:

[0015] The utility model discloses a circulating water step utilization device for a gas separation device, which has a simple structure and is easy to operate. By using the circulating water in series, the circulating cooling water with a lower temperature is recycled for a second time to reduce the amount of circulating water used. At the same time, the circulating cooling water outlet with a higher temperature is used for preheating raw materials, thereby reducing the amount of steam used and reducing the energy consumption of the device as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of the step-by-step utilization device for circulating water in the gas separation device of the utility model;

[0017] In the figure: 1. depropanizer top cooler; 2. deethanizer top cooler; 3. propylene distillation tower top cooler; 4. fresh cooling water inlet pipe; 5. depropanizer reflux tank; 6. deethanizer reflux tank; 7. propylene distillation tower reflux tank; 8. feed pipe; 9. heat exchanger; 10. heater; 11. depropanizer; 12. deethanizer; 13. propylene distillation tower; 14. depropanizer bottom cooler; 15. propylene distillation tower bottom cooler. DETAILED DESCRIPTION

[0018] The specific implementation modes of the present utility model are further described below in conjunction with the accompanying drawings and embodiments. In order to avoid too many unnecessary details, well-known structures or functions will not be described in detail in the following embodiments.

[0019] Example 1

[0020] like Figure 1 As shown, the gas separation device circulating water step utilization device described in the utility model comprises a depropanizer 11, a deethanizer 12, and a propylene distillation tower 13 connected in sequence, and a depropanizer top cooler 1 and a depropanizer bottom cooler 14 arranged in sequence at the top discharge pipe and the bottom discharge pipe of the depropanizer 11, a deethanizer top cooler 2 arranged at the top discharge pipe of the deethanizer 12, a propylene distillation tower top cooler 3 and a propylene distillation tower bottom cooler 15 arranged in sequence at the top discharge pipe and the bottom discharge pipe of the propylene distillation tower 13, and a heat exchanger 9 arranged on the feed pipe 8; the cooling water outlet of the propylene distillation tower top cooler 3 is connected to the cooling water inlet of the depropanizer top cooler 1, the deethanizer top cooler 2, the depropanizer bottom cooler 14, and the propylene distillation tower bottom cooler 15 respectively; the cooling water outlet of the depropanizer bottom cooler 14 is connected to the hot water inlet of the heat exchanger 9.

[0021] The cooling water inlets of the depropanizer top cooler 1, the deethanizer top cooler 2, the propylene distillation tower top cooler 3, the depropanizer bottom cooler 14, and the propylene distillation tower bottom cooler 15 are all connected to the fresh cooling water inlet pipe 4. When the cooling water outlet of the propylene distillation tower top cooler 3 is insufficient to provide cooling capacity for other coolers, cooling water can be added to each cooler through the fresh cooling water inlet pipe 4.

[0022] The feed pipe 8 is connected to the feed port of the depropanizer 11 after passing through the heat exchanger 9 and the heater 10 in sequence. After the cooling water passes through the depropanizer bottom cooler 14 for heat exchange, the temperature is relatively high. This part of the hot water is used to preheat the raw material, and then heated to the required temperature by the heater 10.

[0023] The top discharge port of the depropanizer 11 is connected to the depropanizer reflux tank 5 after passing through the depropanizer top cooler 1, and the depropanizer reflux tank 5 is connected to the top reflux port of the depropanizer 11 and the feed port of the deethanizer 12 respectively.

[0024] The top discharge port of the deethanizer 12 is connected to the deethanizer reflux tank 6 after passing through the deethanizer top cooler 2, and the deethanizer reflux tank 6 is connected to the top reflux port of the deethanizer 12.

[0025] The bottom outlet of the deethanizer 12 is connected to the feed inlet of the propylene distillation tower 13 .

[0026] The top discharge port of the propylene distillation tower 13 is connected to the propylene distillation tower reflux tank 7 after passing through the propylene distillation tower top cooler 3, and the propylene distillation tower reflux tank 7 is connected to the top reflux port of the propylene distillation tower 13.

[0027] The working process of the circulating water step utilization device of the gas separation device is as follows:

[0028] After desulfurization, the qualified liquefied gas enters the gas separation device for separation after buffering. It is first preheated by the heat exchanger 9 and heated to about 65°C by the heater 10, and then enters the depropanizer 11. The bottom kettle liquid is cooled to below 35°C by the depropanizer bottom cooler 14 and sent out to the device. The carbon 2, carbon 3 and a small amount of carbon 4 fractions from the top of the tower are condensed by the depropanizer top cooler 1 and enter the depropanizer reflux tank 5. A part of it is refluxed to the top of the depropanizer 11, and a part of it enters the deethanizer 12; the carbon 2 and carbon 3 distilled from the top of the deethanizer 12 are A small amount of C3 fraction is condensed by the deethanizer top cooler 2, and the temperature drops to about 38°C, and enters the deethanizer reflux tank 6, and all of it is refluxed to the top of the deethanizer 12, and the bottom kettle liquid enters the propylene distillation tower 13; the gaseous material at the top of the propylene distillation tower 13 is condensed by the propylene distillation tower top cooler 3, and the temperature drops to about 38°C, and enters the propylene distillation tower reflux tank 7, a part of it is refluxed to the top of the propylene distillation tower 13, and a part of it is sent out of the device, and the bottom kettle liquid is cooled to below 38°C by the propylene distillation tower bottom cooler 15 and sent out of the device.

[0029] In the above-mentioned gas separation device, according to the different heat loads of each tower, the circulating cooling water flow rates in each cooler vary greatly, among which the circulating cooling water flow rate of the top cooler 3 of the propylene distillation tower is much higher than that of other coolers, and higher than the total circulating cooling water flow rate used by other coolers. At the same time, the cooling water outlet temperature of the top cooler 3 of the propylene distillation tower is about 34°C, which is much lower than the medium temperature (between 45-95°C) required to be cooled by other coolers. Therefore, the utility model diverts the cooling water outlet of the top cooler 3 of the propylene distillation tower as the cooling water inlet of other coolers, thereby reducing the amount of circulating cooling water while ensuring that the heat load of each tower remains unchanged.

[0030] In addition, the outlet temperature of the bottom of the depropanizer 11 is about 95°C. After heat exchange with cooling water in the depropanizer bottom cooler 14, the temperature drops to below 35°C. At this time, the temperature of the cooling water after heat exchange can reach between 45-50°C. This part of hot water can be used to preheat the raw materials to reduce the energy consumption of the heater. At the same time, the hot water can be returned to the circulating water cooling system after the temperature is reduced.

[0031] The above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A step-by-step utilization device for circulating water of a gas separation device, characterized in that: The invention comprises a depropanizer (11), a deethanizer (12), and a propylene distillation tower (13) connected in sequence, a depropanizer top cooler (1) and a depropanizer bottom cooler (14) arranged in sequence at the top discharge pipe and the bottom discharge pipe of the depropanizer (11), a deethanizer top cooler (2) arranged at the top discharge pipe of the deethanizer (12), and a propylene distillation tower top cooler (3) arranged in sequence at the top discharge pipe and the bottom discharge pipe of the propylene distillation tower (13). ) and a propylene distillation tower bottom cooler (15), and a heat exchanger (9) arranged on a feed pipe (8); the cooling water outlet of the propylene distillation tower top cooler (3) is respectively connected to the cooling water inlets of a depropanizer tower top cooler (1), a deethanizer tower top cooler (2), a depropanizer tower bottom cooler (14), and a propylene distillation tower bottom cooler (15); the cooling water outlet of the depropanizer tower bottom cooler (14) is connected to the hot water inlet of the heat exchanger (9).

2. The circulating water step utilization device of the gas separation device according to claim 1 is characterized in that: The cooling water inlets of the depropanizer top cooler (1), the deethanizer top cooler (2), the propylene distillation tower top cooler (3), the depropanizer bottom cooler (14), and the propylene distillation tower bottom cooler (15) are all connected to the fresh cooling water inlet pipe (4).

3. The circulating water step utilization device of the gas separation device according to claim 1 is characterized in that: The feed pipe (8) is connected to the feed port of the depropanizer (11) after passing through the heat exchanger (9) and the heater (10) in sequence.

4. The circulating water step utilization device of the gas separation device according to claim 1 is characterized in that: The top outlet of the depropanizer (11) is connected to a depropanizer reflux tank (5) after passing through a depropanizer top cooler (1), and the depropanizer reflux tank (5) is respectively connected to a top reflux port of the depropanizer (11) and a feed port of a deethanizer (12).

5. The circulating water step utilization device of the gas separation device according to claim 1 is characterized in that: The top discharge port of the deethanizer (12) is connected to the deethanizer reflux tank (6) after passing through the deethanizer top cooler (2), and the deethanizer reflux tank (6) is connected to the top reflux port of the deethanizer (12).

6. The circulating water step utilization device of the gas separation device according to claim 1 is characterized in that: The bottom outlet of the deethanizer (12) is connected to the feed inlet of the propylene distillation tower (13).

7. The circulating water step utilization device of the gas separation device according to claim 1 is characterized in that: The top discharge port of the propylene distillation tower (13) is connected to the propylene distillation tower reflux tank (7) after passing through the propylene distillation tower top cooler (3), and the propylene distillation tower reflux tank (7) is connected to the top reflux port of the propylene distillation tower (13).

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