A device for reducing the energy consumption of a reciprocating compressor in a light hydrocarbon recovery unit

Abstract

This application relates to a device for reducing the energy consumption of a reciprocating compressor in a light hydrocarbon recovery unit. The device includes a feed gas compressor, a desulfurization tower and a molecular sieve tower connected to the feed gas compressor, a first expander connected to the molecular sieve tower, and a cold box connected to one side of the first expander. A second expander is disposed between the feed gas compressor and the desulfurization tower, and the pressurization ends of the feed gas compressor and the second expander are in relative communication. A circulating cooling device is also provided between the feed gas compressor and the desulfurization tower. This application reduces the outlet pressure of the reciprocating compressor and the inlet temperature of the feed gas in the cold box of the light hydrocarbon recovery unit, thereby reducing the energy consumption of the reciprocating compressor and improving the operating efficiency and yield of the light hydrocarbon recovery unit.

Description

Technical Field

[0001] This application relates to the field of light hydrocarbon separation and purification technology in petrochemical production processes, and in particular to a device for reducing the energy consumption of a reciprocating compressor in a light hydrocarbon recovery unit. Background Technology

[0002] Light hydrocarbon recovery units are generally divided into a raw gas pressurization unit, a desulfurization unit, a molecular sieve dehydration unit, an expansion refrigeration unit, and a distillation unit, which separate the raw natural gas into three products: purified natural gas, liquefied petroleum gas, and stabilized light hydrocarbons.

[0003] The raw material gas boosting unit generally uses a reciprocating compressor driven by an electric motor for boosting. The reciprocating compressor is the main power-consuming equipment in the whole set of equipment. The outlet pressure of the reciprocating compressor determines the power of the reciprocating compressor. The higher the outlet pressure, the greater the power of the reciprocating compressor and the higher the energy consumption; the lower the outlet pressure, the smaller the power of the reciprocating compressor and the lower the energy consumption.

[0004] The light hydrocarbon recovery unit uses a cryogenic condensation process to separate heavy components (C3 and above) from natural gas. To improve operating efficiency and yield, the unit's refrigeration temperature needs to be minimized. Referring to Figure 1, the feed gas inlet temperature of Cold Box 1 is the main factor limiting the yield of the light hydrocarbon recovery unit. A lower feed gas inlet temperature results in a higher yield, and vice versa.

[0005] Regarding the aforementioned technologies, the inventors believe that during the summer, due to the influence of ambient temperature, the inlet temperature of the raw gas in the cold box will rise to 40°C, and the efficiency and yield of the light hydrocarbon recovery device will decrease significantly. Summary of the Invention

[0006] In order to reduce the outlet pressure of the reciprocating compressor and the inlet temperature of the raw gas in the cold box of the light hydrocarbon recovery unit, thereby reducing the energy consumption of the reciprocating compressor and improving the operating efficiency and yield of the light hydrocarbon recovery unit, this application provides a device for reducing the energy consumption of the reciprocating compressor of the light hydrocarbon recovery unit.

[0007] This application provides a device for reducing the energy consumption of a reciprocating compressor in a light hydrocarbon recovery unit, which adopts the following technical solution:

[0008] A device for reducing the energy consumption of a reciprocating compressor in a light hydrocarbon recovery unit includes a raw material gas compressor, a desulfurization tower and a molecular sieve tower connected to the raw material gas compressor, a first expander connected to the molecular sieve tower, a cold box connected to one side of the first expander, a second expander provided between the raw material gas compressor and the desulfurization tower, the boosting ends of the raw material gas compressor and the second expander being connected to each other, and a circulating cooling device provided between the raw material gas compressor and the desulfurization tower.

[0009] By adopting the above technical solution, the expander can perform secondary pressurization on the natural gas at the outlet of the feed gas compressor, thereby reducing the outlet pressure of the feed gas compressor. The temperature of the pressurized natural gas is reduced by the set circulating cooling device, which reduces the outlet pressure of the reciprocating compressor and the inlet temperature of the feed gas in the cold box of the light hydrocarbon recovery unit. This reduces the energy consumption of the reciprocating compressor and improves the operating efficiency and yield of the light hydrocarbon recovery unit.

[0010] Optionally, the circulating cooling device includes a circulating water cooler, one end of which is provided with a circulating cooling water inlet, and the other end of which is provided with a circulating cooling water outlet.

[0011] By adopting the above technical solution, the cooling liquid enters the interior of the circulating water cooler through the circulating cooling water inlet and is discharged from the circulating cooling water outlet. This allows the circulating water cooler to cool the gas discharged from the raw material gas compressor, thereby reducing the compressor's energy consumption and improving the operating efficiency and yield of the light hydrocarbon recovery unit.

[0012] Optionally, a heat exchange cold box is fixedly connected to the inlet pipeline of the raw material flow channel of the first cold box, and the heat exchange cold box is in relative communication with the first cold box.

[0013] Optionally, the second expansion end of the second expander is connected to a high-pressure natural gas inlet, which can drive the impeller of the second expansion end of the second expander to rotate.

[0014] By adopting the above technical solution, the impeller of the second expansion end is blown by a high-pressure natural gas from the outside. The high-speed rotation of the impeller of the second expansion end drives the rotation of the impeller of the second pressurization end, thereby realizing the secondary pressurization of the natural gas in the outlet pipeline of the reciprocating compressor of the light hydrocarbon recovery device, reducing the pressure at the outlet of the reciprocating compressor, and thus reducing the energy consumption of the reciprocating compressor.

[0015] Optionally, the first pressurization end pipe of the first expander extends into the interior of the heat exchange cold box.

[0016] By adopting the above technical solution, the cold energy generated by the gas expansion at the second expansion end exchanges heat with the newly added heat exchange cold box, reducing the temperature of the natural gas entering the cold box one of the light hydrocarbon recovery unit, and improving the operating efficiency and yield of the light hydrocarbon recovery unit.

[0017] Optionally, the second expansion end of the second expander is connected to a heat exchange pipeline, which is in relative communication with the heat exchange cold box, so that the gas at the second expansion end of the second expander can exchange heat with the gas at the pressurization end of the first expander inside the heat exchange box.

[0018] Optionally, an air cooler is provided between the first pressurization end of the first expander and the heat exchange cold box.

[0019] Optionally, an oil remover is provided between the circulating cooling device and the desulfurization tower.

[0020] In summary, this application includes at least one of the following beneficial technical effects:

[0021] 1. The impeller at the second booster end is driven by the power generated by the depressurization process of an external high-pressure gas, which realizes secondary boosting of the outlet pressure of the reciprocating compressor of the light hydrocarbon recovery unit. This can reduce the outlet pressure of the reciprocating compressor, thereby reducing the energy consumption of the reciprocating compressor. The cooling capacity generated by the second expansion end of the newly added second expander can also be used to reduce the temperature of the raw gas in the light hydrocarbon recovery unit, thereby improving the operating efficiency of the light hydrocarbon recovery unit.

[0022] 2. The second expander is used to perform secondary pressurization on the natural gas at the outlet of the reciprocating compressor, thereby reducing the outlet pressure of the reciprocating compressor.

[0023] 3. Install a new heat exchange cold box on the inlet pipeline of the raw material gas flow channel of the cold box one of the light hydrocarbon recovery unit. Use the cooling energy generated during the depressurization process of the high-pressure transported natural gas through the second expansion end of the second expander to cool the raw material natural gas at the inlet of the cold box one, so as to reduce the unit's refrigeration temperature and improve the unit's operating efficiency. Attached Figure Description

[0024] Figure 1 The accompanying drawings are illustrations of existing technology.

[0025] Figure 2 This is a schematic diagram of the structure of a reciprocating compressor energy consumption reduction device for a light hydrocarbon recovery unit according to an embodiment of this application.

[0026] Explanation of reference numerals in the attached diagram: 1. Raw material gas compressor; 2. Second expander; 21. Second booster end; 22. Second expansion end; 3. Circulating water cooler; 31. Circulating cooling water inlet; 32. Circulating cooling water outlet; 4. Oil separator; 5. Desulfurization tower; 6. Molecular sieve tower; 7. First expander; 71. First booster end; 72. First expansion end; 8. Air cooler; 9. Heat exchange cold box; 10. Cold box one. Detailed Implementation

[0027] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0029] The following is in conjunction with the appendix Figure 2 This application will be described in further detail.

[0030] This application discloses a device for reducing the energy consumption of a reciprocating compressor in a light hydrocarbon recovery unit. (Refer to...) Figure 2 A device for reducing the energy consumption of a reciprocating compressor in a light hydrocarbon recovery unit includes a raw material gas compressor 1. The outlet end of the raw material gas compressor 1 is connected to a second expander 2, and the outlet end of the raw material gas compressor 1 is in relative communication with the second boosting end 21 of the second expander 2, so that the outlet gas of the raw material gas compressor 1 enters the second boosting end 21 of the second expander 2.

[0031] The second expansion end 22 of the second expander 2 is connected to high-pressure natural gas. The high-pressure natural gas blows the impeller of the second expansion end 22 of the second expander 2 to rotate, causing the impeller of the second expansion end 22 to rotate at high speed, which in turn drives the impeller of the second booster end 21 to rotate, thereby giving secondary boost to the gas generated by the raw material gas compressor 1, reducing the outlet pressure, and thus reducing the energy consumption of the compressor.

[0032] The outlet of the second pressurization end 21 of the second expander 2 is connected to a circulating water cooler 3. One end of the circulating water cooler 3 is provided with a circulating cooling water inlet 31, and the other end of the circulating water cooler 3 is provided with a circulating cooling water outlet 32. The pressurized gas can be cooled by the circulating water cooler 3, and then the cooled gas is connected to the inlet pipeline of the oil remover 4 of the light hydrocarbon recovery device.

[0033] The light hydrocarbon recovery unit includes an oil separator 4, the inlet end of which is connected to the outlet end of the circulating water cooler 3, so that the natural gas discharged from the outlet end of the circulating water cooler 3 enters the interior of the oil separator 4.

[0034] The outlet end of the oil separator 4 is connected to the desulfurization tower 5, and the outlet end of the desulfurization tower 5 is connected to the molecular sieve tower 6, so that the natural gas discharged from the oil separator 4 can enter the interior of the desulfurization tower 5 and the molecular sieve tower 6 in sequence for processing.

[0035] The outlet end of the molecular sieve tower 6 is connected to a first expander 7. The first pressurization end 71 of the first expander 7 is connected to the outlet end of the molecular sieve tower 6. The first pressurization end 71 of the first expander 7 is also connected to an air cooler 8, so that the natural gas discharged from the molecular sieve tower 6 can enter the interior of the first expander 7 and then enter the air cooler 8.

[0036] A heat exchange cold box 9 is installed between the outlet end of the air cooler 8 and the inlet end of the cold box 10. The gas discharged from the air cooler 8 can enter the heat exchange cold box 9 through the pipeline.

[0037] The inlet pipeline of the second expansion end 22 of the second expander 2 is connected to the high-pressure natural gas transported from the outside. The outlet pipeline of the second expansion end 22 of the second expander 2 extends into the interior of the heat exchange cold box 9 and is connected to the cold box 10. This allows the high-pressure natural gas to be depressurized by the second expander 2, and the depressurized gas is input into the interior of the heat exchange cold box 9 through the pipeline. Heat exchange takes place inside the heat exchange cold box 9. The low-pressure, low-temperature natural gas enters the heat exchange cold box 9 and exchanges heat with the natural gas at the outlet of the first pressurization end 71 of the first expander 7, and then enters the downstream low-pressure external transmission pipeline network.

[0038] In this invention, the term "multiple" refers to at least two or more, unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A device for reducing the energy consumption of a reciprocating compressor of a light hydrocarbon recovery device, comprising a raw material gas compressor (1), a desulfurization tower (5) and a molecular sieve tower (6) connected to the raw material gas compressor (1), a first expander (7) connected to the molecular sieve tower (6), and a cold box I (10) connected to one side of the first expander (7), characterized in that: The raw material gas compressor (1) is communicated with the pressurizing end of the second expander (2) oppositely, and a circulating cooling device is further arranged between the raw material gas compressor (1) and the desulfurization tower (5); a heat exchange cold box (9) is fixedly connected to the raw material gas flow channel inlet pipeline of the cold box (10), and the heat exchange cold box (9) is communicated with the cold box (10) oppositely; a heat exchange pipeline is connected to the second expansion end (22) of the second expander (2), the heat exchange pipeline is communicated with the heat exchange cold box (9) oppositely, and the gas of the second expansion end (22) of the second expander (2) can exchange heat with the gas of the pressurizing end of the first expander (7) in the heat exchange cold box (9). ​ 2. The apparatus of claim 1, wherein: The circulating cooling device comprises a circulating water cooler (3), one end of the circulating water cooler (3) is provided with a circulating cooling water inlet (31), and the other end of the circulating water cooler (3) is provided with a circulating cooling water outlet (32).

3. The apparatus of claim 1, wherein: The second expansion end (22) of the second expander (2) is connected with a high-pressure natural gas inlet, which can drive the impeller of the second expansion end (22) of the second expander (2) to rotate.

4. The apparatus of claim 1, wherein: The first pressurizing end (71) pipeline of the first expander (7) extends into the heat exchange cold box (9).

5. The apparatus of claim 4, wherein: An air cooler (8) is arranged between the first pressurizing end (71) of the first expander (7) and the heat exchange cold box (9).

6. The apparatus of claim 1, wherein: An oil remover (4) is arranged between the circulating cooling device and the desulfurization tower (5).

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