An integrated double-tower ethane recovery device and recovery process

Abstract

The present invention discloses an integrated double-tower ethane recovery device and recovery process, including a stripping integrated tower and a rectifying integrated tower, wherein a first integrated raw gas precooling heat exchange coil is arranged inside the stripping integrated tower, a second integrated raw gas precooling heat exchange coil is arranged at the upper end inside the rectifying integrated tower, an integrated supercooled gas heat exchange coil is arranged at the lower part of the second integrated raw gas precooling heat exchange coil, and the raw gas entering the device is divided into two branches, namely a first branch and a second branch. The advantages of the present invention are: it realizes equipment deletion and combined integration, and optimizes the overall process; the process flow is flexible and can be adjusted according to product market demand; the efficiency of ethane recovery is increased, bringing more significant economic benefits.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum and natural gas chemical industry, and in particular to an integrated double-tower ethane recovery device and a recovery process. Background Art

[0002] Most domestic oil and gas fields usually only consider the recovery of propane and heavier hydrocarbon components, but do not recover ethane. Ethane is recovered from natural gas, mainly as a raw material for ethylene production. With the construction and commissioning of ethylene plants that use ethane as raw material, the demand for ethane will increase significantly. For oil and gas production companies, the recovery of ethane will bring more significant economic benefits. The traditional deep-cold recovery device uses a "cold box" with a plate-fin heat exchange core, which has a complicated process, a large number of equipment, and a large area. The present invention uses a heat exchange distillation tower to delete and integrate the equipment to optimize the process. Therefore, it is necessary to design an integrated double-tower ethane recovery device, the purpose of which is to solve the defects of the existing technology in recovering ethane, such as the large number of equipment and the complicated process. Summary of the invention

[0003] The present invention aims to solve the problem of a large number of ethane recovery devices and a complicated process in the prior art.

[0004] The present invention is achieved through the following technical solutions:

[0005] An integrated double-tower ethane recovery device comprises a stripping integrated tower and a rectifying integrated tower, wherein a first integrated raw gas precooling heat exchange coil is arranged inside the stripping integrated tower, a second integrated raw gas precooling heat exchange coil is arranged at the upper end inside the rectifying integrated tower, an integrated supercooled gas heat exchange coil is arranged at the lower part of the second integrated raw gas precooling heat exchange coil, the raw gas is divided into two branches, namely a first branch and a second branch, the first branch is sequentially arranged along the gas flow output direction with the second integrated raw gas precooling heat exchange coil, a raw gas precooler and a separator, and the second branch is sequentially arranged along the gas flow output direction with the first integrated raw gas precooling heat exchange coil, a raw gas precooler, a separator, an expander and a rectifying integrated tower.

[0006] The existing technology uses a "cold box" of a plate-fin heat exchange core in the traditional process for recycling. The recycling device cannot be integrated, the operation process is complicated, the number of equipment is large, and the area occupied is large.

[0007] The present invention adopts the form of coil heat exchange, and the integrated raw gas precooling heat exchange coil and the integrated supercooled gas heat exchange coil are arranged in the distillation integrated tower and the distillation integrated tower, and the distillation tower and the coil heat exchanger are integrated at the same time. The liquid separated from the separator and the low-temperature condensate sent to the packing area are unqualified, but after the coil heat exchange heating at the bottom of the stripping and distillation tower, qualified NGL is obtained at the bottom of the tower. The device of the invention focuses on the deletion and combination of equipment, and develops an integrated ethane recovery integrated equipment, optimizes the process, and can adjust the process parameters and processes according to the product market demand to realize the operation mode of recovering ethane.

[0008] Furthermore, the outlet of the lower part of the rectification integrated tower is connected to the inlet of the third filling area through a pipeline, the inlet of the third filling area is located at the top of the distillation integrated tower, and the bottom pump of the rectification integrated tower is arranged on the pipeline;

[0009] Furthermore, a separator outlet is provided at the top of the separator, and the precooled raw gas at the separator outlet is divided into two branches, the first branch is connected to the expansion end of the expander, the expansion end outlet of the expander is connected to the inlet of the first filling area of ​​the distillation integrated tower, and the second branch is connected to the inlet of the integrated subcooled gas heat exchange coil;

[0010] Furthermore, the outlet at the top of the distillation integrated tower is connected to the boost end of the expander inlet, and the outlet of the expander is connected to the port of the external dry gas pipe.

[0011] A recovery process of an integrated double-tower ethane recovery device comprises the following steps:

[0012] S1: After the raw gas at the outlet of the raw gas pipe enters the device, it is divided into two parts. One part of the raw gas enters the second integrated raw gas precooling heat exchange coil through the inlet of the first integrated raw gas precooling heat exchange coil at the top of the rectification integrated tower, and then enters the raw gas precooler for precooling through the outlet of the first integrated raw gas precooling heat exchange coil. The other part enters the first integrated raw gas precooling heat exchange coil through the inlet of the second integrated raw gas precooling heat exchange coil in the middle of the stripping integrated tower, and then merges with the other part of the raw gas through the outlet of the second integrated raw gas precooling heat exchange coil in the middle of the rectification integrated tower;

[0013] S2: The combined gas is further cooled by the raw gas precooler and then enters the separator at the bottom of the stripping integrated tower for gas-liquid separation. The gas phase of the separator is divided into two parts: one part of the gas is expanded and refrigerated at the expansion end of the expander and then enters the inlet of the first packing area, and the other part of the gas enters the second integrated raw gas precooling heat exchange coil) and is throttled to the upper part of the packing of the distillation integrated tower as a washing liquid after supercooling, washing ethane and above components in the gas phase at the top of the tower;

[0014] S3: The low-temperature condensate at the bottom of the distillation integrated tower is pressurized by the bottom pump of the distillation integrated tower and then sent to the inlet of the third tower internals after pressurization;

[0015] S4: the liquid phase of the separator at the bottom of the stripping integrated tower is sent to the inlet of the fourth packing zone;

[0016] S5: Heat is supplied to the stripping integrated tower through the raw gas precooler and the first integrated raw gas precooling heat exchange coil to remove methane from the NGL, and a qualified NGL product is obtained at the bottom of the stripping integrated tower.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] 1. The integrated double-tower ethane recovery device of the present invention realizes equipment reduction and combined integration, and optimizes the overall process.

[0019] 2. The present invention provides an integrated double-tower ethane recovery device, which has a flexible process flow and can be adjusted according to product market demand.

[0020] 3. The integrated double-tower ethane recovery device of the present invention has increased ethane recovery efficiency and brought more significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0022] Figure 1 Schematic diagram of the ethane recovery process.

[0023] 1-stripping integrated tower, 2-rectification integrated tower, 3-rectification integrated tower bottom pump, 4-expander, 5-raw gas precooler, 61-integrated raw gas precooling heat exchange coil, 62-integrated subcooled gas heat exchange coil, 7-raw gas pipe outlet, 8-external dry gas pipe port, 9-separator, 103-first packing area inlet, 104-rectification integrated tower inlet, 106-first integrated raw gas precooling heat exchange coil outlet, 111-third packing area inlet, 112-fourth packing area inlet, 114-separator inlet, 116-stripping integrated tower middle side extraction outlet, 119-separator outlet, 120-stripping integrated tower middle side extraction return port. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0025] Embodiment 1:

[0026] like Figure 1As shown, the present invention is an integrated double-tower ethane recovery device, including a stripping integrated tower 1 and a rectifying integrated tower 2, wherein the stripping integrated tower 1 is provided with a first integrated raw gas precooling heat exchange coil 63, the upper end of the rectifying integrated tower 2 is provided with a second integrated raw gas precooling heat exchange coil 61, the lower part of the second integrated raw gas precooling heat exchange coil 61 is provided with an integrated supercooled gas heat exchange coil 62, the raw gas is divided into two branches, namely a first branch and a second branch, the first branch is sequentially provided with the second integrated raw gas precooling heat exchange coil 61, a raw gas precooler 5 and a separator 9 along the gas flow output direction, and the second branch is sequentially provided with the first integrated raw gas precooling heat exchange coil 63, a raw gas precooler 5, a separator 9, an expander 4 and a rectifying integrated tower 2 along the gas flow output direction.

[0027] Embodiment 2:

[0028] like Figure 1 As shown, this embodiment is based on embodiment 1, the outlet of the lower part of the distillation integrated tower 2 is connected to the inlet 111 of the third filling area through a pipeline, the inlet 111 of the third filling area is located at the top of the distillation integrated tower 1, and the bottom pump 3 of the distillation integrated tower is arranged on the pipeline; the separator outlet 119 is arranged on the top of the separator 9, and the precooled raw gas at the outlet of the separator is divided into two branches, the first branch is connected to the expansion end of the expander 4, and the expansion end outlet of the expander 4 is connected to the first filling area inlet 103 of the distillation integrated tower 2, The second branch is connected to the inlet of the integrated supercooled gas heat exchange coil 62; the outlet at the top of the distillation integrated tower 2 is connected to the boost end of the inlet of the expander 4, and the outlet of the expander 4 is connected to the external dry gas pipe port 8; the raw gas precooler 5 has four ports, which are respectively connected to the separator inlet 114, the middle side extraction outlet 116 of the distillation integrated tower, the first integrated raw gas precooling heat exchange coil outlet 106 and the middle side extraction return port 120 of the distillation integrated tower; the top outlet of the distillation integrated tower 1 is connected to the bottom distillation integrated tower inlet 104.

[0029] Embodiment 3:

[0030] like Figure 1 As shown, this embodiment is based on Examples 1 and 2 to implement a recovery process of an integrated double-tower ethane recovery device, comprising the following steps:

[0031] S1: After the raw gas at the raw gas pipe outlet end 7 enters the device, it is divided into two parts. One part of the raw gas enters the second integrated raw gas precooling heat exchange coil 61 through the first integrated raw gas precooling heat exchange coil inlet 101 at the top of the distillation integrated tower 2, and then enters the raw gas precooler 5 for precooling through the first integrated raw gas precooling heat exchange coil outlet 106. The other part enters the first integrated raw gas precooling heat exchange coil 63 through the second integrated raw gas precooling heat exchange coil inlet 113 in the middle of the stripping integrated tower 1, and then merges with the other part of the raw gas through the second integrated raw gas precooling heat exchange coil outlet 117 in the middle of the distillation integrated tower 1;

[0032] S2: The combined gas is further cooled by the raw gas precooler 5 and then enters the separator 9 at the bottom of the stripping integrated tower 1 for gas-liquid separation. The gas phase of the separator 9 is divided into two parts: one part of the gas is expanded and refrigerated at the expansion end of the expander 4 and then enters the inlet 103 of the first packing area, and the other part of the gas enters the second integrated raw gas precooling heat exchange coil 61 and then throttled to the upper part of the packing of the distillation integrated tower 2 as a washing liquid to wash ethane and above components in the gas phase at the top of the tower;

[0033] S3: The low-temperature condensate at the bottom of the rectification integrated tower 2 is pressurized by the rectification integrated tower bottom pump 3 and then sent to the inlet 111 of the third tower internals after being pressurized;

[0034] S4: the liquid phase of the separator 9 at the bottom of the stripping integrated tower 1 is sent to the inlet 112 of the fourth packing zone;

[0035] S5: supplying heat to the stripping integrated tower 1 through the raw gas precooler 5 and the first integrated raw gas precooling heat exchange coil 63 to remove methane from the NGL, and obtaining a qualified NGL product at the bottom of the stripping integrated tower 1.

[0036] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An integrated double-tower ethane recovery device, comprising a stripping integrated tower (1) and a rectifying integrated tower (2), characterized in that: The stripping integrated tower (1) is provided with a first integrated raw gas precooling heat exchange coil (63), the upper end of the rectifying integrated tower (2) is provided with a second integrated raw gas precooling heat exchange coil (61), the lower part of the second integrated raw gas precooling heat exchange coil (61) is provided with an integrated subcooled gas heat exchange coil (62), the raw gas is divided into two branches, namely a first branch and a second branch, the first branch is provided with the second integrated raw gas precooling heat exchange coil (61), a raw gas precooler (5) and a separator (9) in sequence along the gas flow output direction, and the second branch is provided with the first integrated raw gas precooling heat exchange coil (63), a raw gas precooler (5), a separator (9), an expander (4) and a rectifying integrated tower (2) in sequence along the gas flow output direction; The outlet at the bottom of the rectification integrated tower (2) is connected to the inlet (111) of the third filling area via a pipeline, the inlet (111) of the third filling area is located at the top of the stripping integrated tower (1), and the bottom pump (3) of the rectification integrated tower is arranged on the pipeline; The top outlet of the stripping integrated tower (1) is connected to the bottom rectifying integrated tower inlet (104).

2. The integrated double-tower ethane recovery device according to claim 1, characterized in that: A separator outlet (119) is provided at the top of the separator (9), and the pre-cooled raw gas at the separator outlet is divided into two branches, the first branch is connected to the expansion end of the expander (4), the expansion end outlet of the expander (4) is connected to the first filling area inlet (103) of the distillation integrated tower (2), and the second branch is connected to the inlet of the integrated subcooled gas heat exchange coil (62).

3. The integrated double-tower ethane recovery device according to claim 2, characterized in that: The outlet at the top of the rectification integrated tower (2) is connected to the boosting end of the inlet of the expander (4), and the outlet of the expander (4) is connected to the external dry gas pipe port (8).

4. The integrated double-tower ethane recovery device according to claim 1, characterized in that: The raw gas precooler (5) has four ports, which are respectively connected to the separator inlet (114), the middle side extraction outlet (116) of the stripping integrated tower, the first integrated raw gas precooling heat exchange bypass outlet (106) and the middle side extraction return port (120) of the stripping integrated tower.

5. A recovery process based on an integrated double-tower ethane recovery device according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: After the raw gas from the raw gas pipe outlet end (7) enters the device, it is divided into two parts. One part of the raw gas enters the second integrated raw gas precooling heat exchange coil (61), and then enters the raw gas precooler (5) for precooling. The other part enters the first integrated raw gas precooling heat exchange coil (63), and then merges with the other part of the raw gas. S2: The combined gas is further cooled by the raw gas precooler (5) and then enters the separator (9) at the bottom of the stripping integrated tower (1) for gas-liquid separation. The gas phase of the separator (9) is divided into two parts: one part of the gas reaches the inlet (103) of the first packing area, and the other part of the gas goes to the upper part of the packing of the rectification integrated tower (2) as a washing liquid to wash the ethane in the gas phase at the top of the tower; S3: The low-temperature condensate at the bottom of the rectification integrated tower (2) is pressurized by the rectification integrated tower bottom pump (3), and then sent to the inlet (111) of the third packing area after being pressurized; S4: the liquid phase of the separator (9) at the bottom of the stripping integrated tower (1) is sent to the inlet (112) of the fourth packing zone; S5: heat is supplied to the stripping integrated tower (1) through the raw gas precooler (5) and the first integrated raw gas precooling heat exchange coil (63), methane in the NGL is removed, and a qualified NGL product is obtained at the bottom of the stripping integrated tower (1).

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