Potential of hydrogen (pH) value system of lean solvent / stripping water heat exchanger

Abstract

The utility model relates to the technical field of chemical engineering, in particular to a pH value system of a lean solvent / stripping water heat exchanger, which comprises a lean solvent / stripping water heat exchanger, a reflux pipeline, a heat exchanger inlet line, a heat exchanger outlet line, a lean solvent / feeding heater, an extraction distillation tower, a first outlet line and a second outlet line, one end of the reflux pipeline is connected to an outlet I of the lean solvent / stripping water heat exchanger, and the other end is connected to an inlet I of the lean solvent / stripping water heat exchanger; a shell pass outlet valve, a solvent regeneration tower, a solvent recovery tower, a recovery tower top air cooler, a recovery tower top water cooler, a reflux tank, a steam stripping water pump, a stripping water flow meter, a front valve, a stripping water regulating valve, a rear valve and a shell pass inlet valve are sequentially arranged on the reflux pipeline. The stable pH value in the system is ensured when the lean solvent / stripping water heat exchanger is overhauled, so that water circulates in the system, and the economic loss caused by continuous injection of monoethanolamine into the system is reduced.

Description

Technical Field

[0001] This utility model relates to the field of chemical technology, specifically to a pH system for a lean solvent / stripping water heat exchanger. Background Technology

[0002] Heat exchangers are a crucial type of heat exchange equipment in petrochemical production. For shell-and-tube heat exchangers, the thin walls of the tube bundles make them susceptible to corrosion and leakage. Once a heat exchanger leaks, it can only be shut down for repair, either by replacing the tube bundle or sealing the leak. Steam is then used instead of stripping water. However, because the lean solvent / stripping water heat exchanger is shut down, steam is replenished from its outlet while water is discharged from the stripping water pump outlet, causing the system pH to drop rapidly. Therefore, monoethanolamine needs to be continuously injected into the system to maintain pH stability.

[0003] Currently, the operation of the unit only considers that the lean solvent / stripping water heat exchanger can be disconnected for maintenance, but it does not consider that the water in the system needs to be discharged after the lean solvent / stripping water heat exchanger is disconnected, which will cause the system pH value to drop. Stabilizing the system pH value requires continuous injection of monoethanolamine, which will waste a large amount of monoethanolamine. Utility Model Content

[0004] In view of the deficiencies of the prior art, this utility model provides a pH system for a lean solvent / stripping water heat exchanger, which ensures the stability of the pH value within the system during maintenance, allows water to circulate within the system, and reduces the economic losses caused by continuous injection of monoethanolamine into the system.

[0005] To achieve the above objectives, the technical solution provided by this utility model is a pH system for a lean solvent / stripping water heat exchanger, comprising a lean solvent / stripping water heat exchanger, a reflux pipeline, a heat exchanger inlet line, a heat exchanger outlet line, a lean solvent / feed heater, an extraction distillation column, a first outlet line, and a second outlet line; one end of the reflux pipeline is connected to the first outlet of the lean solvent / stripping water heat exchanger, and the other end is connected to the first inlet of the lean solvent / stripping water heat exchanger. The reflux pipeline is sequentially equipped with a shell-side outlet valve, a solvent regeneration column, a solvent recovery column, an air-cooled recovery column top, a water-cooled recovery column top, a reflux tank, a stripping water pump, and a stripping water flow... The system includes a gauge, a front valve, a stripping water regulating valve, a rear valve, and a shell-side inlet valve. The heat exchanger inlet line is connected to inlet two of the lean solvent / stripping water heat exchanger, and a tube-side inlet valve is installed on the heat exchanger inlet line. One end of the heat exchanger outlet line is connected to outlet two of the lean solvent / stripping water heat exchanger, and the other end is connected to inlet one of the lean solvent / feed heat exchanger, and a tube-side outlet valve is installed on the heat exchanger outlet line. The first outlet line is connected to outlet one of the lean solvent / feed heater. One end of the second outlet line is connected to outlet two of the lean solvent / feed heater, and the other end is connected to the extraction distillation column.

[0006] Furthermore, it also includes a steam line, an extraction feed line, a bypass line, and a first bypass line. The steam line is connected to the reflux line, and the first joint between the steam line and the reflux line is located between the solvent regeneration tower and the shell-side outlet valve. The extraction feed line is connected to the inlet of the lean solvent / feed heater. One end of the bypass line is connected to the reflux line, and the other end is connected to the extraction feed line. The second joint between the bypass line and the reflux line is located between the downstream valve and the shell-side inlet valve. One end of the first bypass line is connected to the heat exchanger inlet line, and the other end is connected to the heat exchanger outlet line. The fourth joint between the first bypass line and the heat exchanger inlet line is located upstream of the tube-side inlet valve, and the fifth joint between the first bypass line and the heat exchanger outlet line is located downstream of the tube-side outlet valve. A first bypass valve assembly is installed on the first bypass line.

[0007] Furthermore, the extraction feed line is sequentially equipped with a boundary zone three-valve group, an extraction feed flow meter, and an extraction feed regulating valve group.

[0008] Furthermore, a first valve, a second drain valve, and a second valve are sequentially arranged on the cross line, and the connector three between the cross line and the extraction feed line is located downstream of the extraction feed regulating valve group.

[0009] Furthermore, a first drain valve is provided between the front valve and the stripping water regulating valve.

[0010] Furthermore, it also includes a second bypass pipeline, one end of which is connected to the inlet line of the heat exchanger, and the other end is connected to the first outlet line through a second bypass valve group, and a third drain valve is provided on the second bypass valve group.

[0011] Furthermore, a steam boundary valve, a third valve, and a fourth valve are sequentially installed on the steam pipeline.

[0012] The method for controlling the pH value system of a lean solvent / stripping water heat exchanger described above includes the following steps:

[0013] When the S100 lean solvent / stripping water heat exchanger is in normal operation, close the first valve, the second valve, the first bypass valve group, the steam boundary valve, the third valve, and the fourth valve.

[0014] S200: Open the shell-side outlet valve, front valve, stripping water regulating valve, rear valve, shell-side inlet valve, tube-side inlet valve, and tube-side outlet valve. The stripping water of the lean solvent / stripping water heat exchanger forms a closed loop through the return pipeline. The lean solvent of the lean solvent / stripping water heat exchanger enters through the heat exchanger inlet line and flows out through the heat exchanger outlet line into the lean solvent / feed heater, and flows out from the first outlet line.

[0015] Furthermore, the steps also include

[0016] When the S300 lean solvent / stripping water heat exchanger is shut down for maintenance, open the first bypass valve group, the steam boundary valve, the first valve, the second valve, the third valve, and the fourth valve.

[0017] S400, close the shell-side outlet valve, shell-side inlet valve, tube-side inlet valve and tube-side outlet valve. The steam from the steam line is introduced into the extraction feed line through the return line and the bypass line. It merges with the material in the extraction feed line and flows into the lean solvent / feed heater. The lean solvent of the lean solvent / stripping water heat exchanger flows into the lean solvent / feed heater through the first bypass line and the heat exchanger outlet line.

[0018] S500, Open the second bypass valve group and adjust the opening degree to control the temperature of the extraction feed entering the extraction distillation column;

[0019] S600, disconnect the lean solvent / stripping water heat exchanger, and intermittently inject monoethanolamine.

[0020] The beneficial effects of this invention are as follows: Whether the lean solvent / stripping water heat exchanger is in normal operation or being shut down for maintenance, the pH system of the lean solvent / stripping water heat exchanger of this invention can achieve a stable output. After the lean solvent / stripping water heat exchanger is shut down, the water that was originally required to be discharged is sent to the extraction feed line to ensure the pH value of the system. The original situation of needing to continuously inject monoethanolamine but still not having a high pH value is changed to intermittent injection of monoethanolamine while ensuring the pH value of the system, which saves production costs and improves production efficiency. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the present invention;

[0022] In the diagram: 100, lean solvent / stripping water heat exchanger; 110, first bypass pipeline; 111, first bypass valve assembly.

[0023] 200. Reflux line; 201. Shell-side outlet valve; 210. Solvent regeneration tower; 220. Solvent recovery tower; 230. Reflux tank; 240. Stripping water pump; 250. Stripping water flow meter; 202. Inlet valve; 203. Stripping water regulating valve; 204. Outlet valve; 205. Shell-side inlet valve; 206. First drain valve; 260. Air cooler at the top of the recovery tower; 270. Water cooler at the top of the recovery tower.

[0024] 300. Heat exchanger inlet line; 310. Tube-side inlet valve.

[0025] 400. Heat exchanger outlet line; 410. Tube-side outlet valve.

[0026] 500. Lean solvent / feed heater; 510. First outlet line; 520. Second outlet line; 530. Second bypass line; 531. Second bypass valve assembly; 5311. Third drain valve.

[0027] 600. Extraction distillation column,

[0028] 700. Steam pipeline; 710. Steam boundary valve; 720. Third valve; 730. Fourth valve.

[0029] 800. Extraction feed line; 810. Boundary three-valve assembly; 820. Extraction feed flow meter; 830. Extraction feed regulating valve assembly.

[0030] 900, Cross-line; 910, First valve; 920, Second drain valve; 930, Second valve.

[0031] A. Connector 1, B. Connector 2, C. Connector 3, D. Connector 4, E. Connector 5. Detailed Implementation

[0032] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0033] like Figure 1As shown, in one embodiment of this utility model, a pH system for a lean solvent / stripping water heat exchanger 100 includes a lean solvent / stripping water heat exchanger 100, a reflux line 200, a heat exchanger inlet line 300, a heat exchanger outlet line 400, a lean solvent / feed heater 500, an extraction distillation column 600, a first outlet line 510, and a second outlet line 520. One end of the reflux line 200 is connected to the outlet of the lean solvent / stripping water heat exchanger 100, and the other end is connected to the inlet of the lean solvent / stripping water heat exchanger 100. The reflux line 200 is sequentially equipped with a shell-side outlet valve 201, a solvent regeneration column 210, a solvent recovery column 220, a recovery column top air cooler 260, a recovery column top water cooler 270, a reflux tank 230, and a stripping water... Pump 240, stripping water flow meter 250, front valve 202, stripping water regulating valve 203, rear valve 204, and shell-side inlet valve 205; heat exchanger inlet line 300 is connected to inlet two of lean solvent / stripping water heat exchanger 100, and tube-side inlet valve 310 is installed on heat exchanger inlet line 300; one end of heat exchanger outlet line 400 is connected to outlet two of lean solvent / stripping water heat exchanger 100, and the other end is connected to inlet one of lean solvent / feed heat exchanger, and tube-side outlet valve 410 is installed on heat exchanger outlet line 400; first outlet line 510 is connected to outlet one of lean solvent / feed heater 500; one end of outlet line is connected to outlet two of lean solvent / feed heater 500, and the other end is connected to extraction distillation column 600.

[0034] It should be noted that the stripping water regulating valve 203 is also equipped with a bypass valve.

[0035] Based on the pH system of the aforementioned lean solvent / stripping water heat exchanger 100, it further includes a steam line 700, an extraction feed line 800, a bypass line 900, and a first bypass line 110. The steam line 700 is connected to the reflux line 200, and the joint A between the steam line 700 and the reflux line 200 is located between the solvent regeneration tower 210 and the shell-side outlet valve 201. The extraction feed line 800 is connected to the inlet of the lean solvent / feed heater 500. One end of the bypass line 900 is connected to the reflux line 200, and the other end is connected to the extraction line 800. The feed line 800, the cross line 900 and the return line 200 are connected at joint 2B between the downstream valve 204 and the shell-side inlet valve 205; one end of the first bypass line 110 is connected to the heat exchanger inlet line 300 and the other end is connected to the heat exchanger outlet line 400; the joint 4D between the first bypass line 110 and the heat exchanger inlet line 300 is located upstream of the tube-side inlet valve 310; the joint 5E between the first bypass line 110 and the heat exchanger outlet line 400 is located downstream of the tube-side outlet valve 410; and the first bypass valve group 111 is installed on the first bypass line 110.

[0036] It should be noted that 0.46MPa steam is introduced into the steam pipeline 700; the stripping water pump 240 comes from the water tank 230 of the return tank.

[0037] In one embodiment, the extraction feed line 800 is sequentially provided with a boundary three-valve group 810, an extraction feed flow meter 820, and an extraction feed regulating valve group 830.

[0038] In one embodiment, a first valve 910, a second drain valve 920, and a second valve 930 are sequentially arranged on the cross line 900, and the connector 3C between the cross line 900 and the extraction feed line 800 is located downstream of the extraction feed regulating valve group 830.

[0039] In one embodiment, a first drain valve 206 is provided between the front valve 202 and the stripping water regulating valve 203.

[0040] Based on one embodiment, it further includes a second bypass line 530, one end of which is connected to the heat exchanger inlet line 300, and the other end is connected to the first outlet line 510 through a second bypass valve group 531. A third drain valve 5311 is provided on the second bypass valve group 531.

[0041] In one embodiment, a steam boundary valve 710, a third valve 720, and a fourth valve 730 are sequentially installed on the steam pipeline 700.

[0042] See Figure 1 As shown, the method for controlling the pH value of the above-mentioned lean solvent / stripping water heat exchanger 100 includes the following steps:

[0043] When S100 and lean solvent / stripping water heat exchanger 100 are in normal operation, close the first valve 910, the second valve 930, the first bypass valve group 111, the steam boundary valve 710, the third valve 720 and the fourth valve 730.

[0044] S200, open shell-side outlet valve 201, front valve 202, stripping water regulating valve 203, rear valve 204, shell-side inlet valve 205, tube-side inlet valve 310 and tube-side outlet valve 410. The stripping water of the lean solvent / stripping water heat exchanger 100 forms a closed loop through the return line 200. The lean solvent of the lean solvent / stripping water heat exchanger 100 enters through the heat exchanger inlet line 300 and exits through the heat exchanger outlet line 400 into the lean solvent / feed heater 500 and exits from the first outlet line 510.

[0045] Furthermore, in one embodiment, the steps also include...

[0046] When S300 and lean solvent / stripping water heat exchanger 100 are shut down for maintenance, open the first bypass valve group 111, steam boundary valve 710, first valve 910, second valve 930, third valve 720 and fourth valve 730.

[0047] S400, close shell-side outlet valve 201, shell-side inlet valve 205, tube-side inlet valve 310 and tube-side outlet valve 410. Steam from steam line 700 is introduced into extraction feed line 800 through return line 200 and cross line 900, and merges with the material from extraction feed line 800 into lean solvent / feed heater 500. Lean solvent from lean solvent / stripping water heat exchanger 100 flows into lean solvent / feed heater 500 through first bypass line and heat exchanger outlet line 400.

[0048] S500, open the second bypass valve group 531, and adjust the opening degree to control the temperature of the extraction feed entering the extraction distillation column 600;

[0049] S600, cut off lean solvent / stripping water heat exchanger 100, and intermittently inject monoethanolamine.

[0050] When the pH system of the aforementioned lean solvent / stripping water heat exchanger 100 needs maintenance, the original operating procedure is as follows: First, open the first bypass valve on the tube side of the lean solvent / stripping water heat exchanger 100, then close the inlet valve 310 and outlet valve 410 on the tube side of the lean solvent / stripping water heat exchanger 100. Next, close the shell-side inlet valve 205 and outlet valve 201 of the lean solvent / stripping water heat exchanger 100 to disconnect the lean solvent / stripping water heat exchanger 100. Simultaneously, fully open the 0.46MPa steam boundary valve 710, allowing 0.46MPa steam to reach the third outlet valve 720 on the shell side of the lean solvent / stripping water heat exchanger 100. Adjust the opening of the fourth outlet valve 730 on the shell side of the lean solvent / stripping water heat exchanger 100. Steam at 0.46 MPa is introduced into the solvent regeneration tower 210, with the flow rate controlled to be consistent with the original stripping water flow rate. The flow rate can be monitored by the stripping water flow meter 250. Water is then sent to the solvent recovery tower 220 through the reflux pipeline 200. The water passes through the top of the solvent recovery tower 220, through the top air cooler 260 and the top water cooler 270, and enters the water tank of the reflux tank 230. It then passes through the water tank of the reflux tank 230 to the stripping water pump 240. The stripping water regulating valve 203 and the downstream valve 204 are closed, while the upstream valve 202 is fully open. The first drain valve 206 controls the drainage volume to discharge the water out of the system. Since the water cannot circulate within the system, the pH value will continuously decrease. A large amount of monoethanolamine needs to be injected into the system to ensure the stability of the system pH value.

[0051] This invention allows water originally discharged from the first drain valve 206 to circulate within the system. Specifically, a tee is used between the shell-side inlet valve 205 and the downstream valve 204 of the lean solvent / stripping water heat exchanger 100, connected to the extraction feed line 800 via a crossover line 900. A tee is used downstream of the extraction feed regulating valve group 830 to close the first drain valve 206, fully open the stripping water regulating valve 203 and the downstream valve 204, and fully open the first valve 910 and the second valve 930 on the crossover line 900. The flow rate is automatically controlled by the stripping water regulating valve 203 to match the original stripping water flow rate, which can be monitored by the stripping water flow meter 250. The water added to the extraction feed will circulate with the system, ensuring a relatively stable system pH value. Monoethanolamine is added according to the pH value of the test sample, which can greatly save the amount of monoethanolamine injected.

[0052] In addition, the water incorporated into the extraction feed circulates with the system, exchanges heat with the solvent through the lean solvent / feed heat exchanger, and adjusts the temperature of the extraction feed entering the tower by adjusting the second bypass valve group of the lean solvent / feed heat exchanger at 531 degrees, thereby achieving temperature regulation.

[0053] It should be noted that the main purpose of this invention is to send the water that was originally to be discharged to the extraction feed line after the lean solvent / stripping water heat exchanger 100 is disconnected, thus ensuring the pH value of the system. This changes the situation where the pH value is still not high even after continuous injection of monoethanolamine to intermittent injection of monoethanolamine, while still ensuring the pH value of the system. The original design only considered safe maintenance after disconnecting the lean solvent / stripping water heat exchanger 100, without considering the economic losses caused by the rapid drop in pH value after disconnection and the need for continuous injection of monoethanolamine. This invention can intermittently inject monoethanolamine according to the system pH value after disconnection of the lean solvent / stripping water heat exchanger 100, thus saving costs.

[0054] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0055] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0056] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0057] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature. It should be noted that when an element is referred to as "fixed to" or "set on" another element, it can be directly on the other element or there may be an intermediate element present. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element present. The terms "vertical," "horizontal," "above," "below," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

Claims

1. A pH system for a lean solvent / stripping water heat exchanger, characterized in that: include Lean solvent / stripping water heat exchanger; The reflux line is connected at one end to the outlet of the lean solvent / stripping water heat exchanger and at the other end to the inlet of the lean solvent / stripping water heat exchanger. The reflux line is sequentially equipped with a shell-side outlet valve, a solvent regeneration tower, a solvent recovery tower, an air-cooled recovery tower top, a water-cooled recovery tower top, a reflux tank, a stripping water pump, a stripping water flow meter, a front valve, a stripping water regulating valve, a rear valve, and a shell-side inlet valve. The heat exchanger inlet line is connected to the inlet phase two of the lean solvent / stripping water heat exchanger, and a tube-side inlet valve is installed on the heat exchanger inlet line; The heat exchanger outlet line is connected at one end to outlet two of the lean solvent / stripping water heat exchanger and at the other end to inlet one of the lean solvent / feed heat exchanger. A tube-side outlet valve is installed on the heat exchanger outlet line. Lean solvent / feed heater; Extractive distillation column; The first outlet line is connected to the outlet of the lean solvent / feed heater; and The second outlet line is connected at one end to outlet two of the lean solvent / feed heater and at the other end to the extraction distillation column.

2. The pH system for a lean solvent / stripping water heat exchanger according to claim 1, characterized in that: Also includes A steam line is connected to a reflux line, and the joint between the steam line and the reflux line is located between the solvent regeneration tower and the shell-side outlet valve. The extraction feed line is connected to the two-phase inlet of the lean solvent / feed heater. A crossover line, one end of which is connected to the reflux pipeline and the other end of which is connected to the extraction feed line, wherein the second joint between the crossover line and the reflux pipeline is located between the rear valve and the shell-side inlet valve; The first bypass pipeline has one end connected to the heat exchanger inlet line and the other end connected to the heat exchanger outlet line. The fourth joint of the first bypass pipeline to the heat exchanger inlet line is located upstream of the tube-side inlet valve, and the fifth joint of the first bypass pipeline to the heat exchanger outlet line is located downstream of the tube-side outlet valve. A first bypass valve group is installed on the first bypass pipeline.

3. The pH system for a lean solvent / stripping water heat exchanger according to claim 2, characterized in that: The extraction feed line is sequentially equipped with a boundary zone three-valve group, an extraction feed flow meter, and an extraction feed regulating valve group.

4. The pH system for a lean solvent / stripping water heat exchanger according to claim 3, characterized in that: The cross-line is sequentially equipped with a first valve, a second drain valve, and a second valve. The connector between the cross-line and the extraction feed line is located downstream of the extraction feed regulating valve group.

5. The pH system for a lean solvent / stripping water heat exchanger according to claim 1, characterized in that: A first drain valve is provided between the front valve and the stripping water regulating valve.

6. The pH system for a lean solvent / stripping water heat exchanger according to claim 1, characterized in that: It also includes a second bypass pipeline, one end of which is connected to the inlet line of the heat exchanger, and the other end is connected to the first outlet line through a second bypass valve group. A third drain valve is installed on the second bypass valve group.

7. The pH system for a lean solvent / stripping water heat exchanger according to claim 2, characterized in that: The steam pipeline is equipped with a steam boundary valve, a third valve, and a fourth valve in sequence.

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