Control system and method for controlling the inlet temperature of low-temperature propylene BOG compressor

Abstract

The present invention provides a control system and method for controlling the inlet temperature of a low-temperature propylene BOG compressor, relates to the technical field of propylene production process, and solves the technical problem that the BOG compressor in the prior art often undergoes interlocking shutdown due to high outlet temperature. The control system includes a BOG compressor, a BOG compressor inlet buffer tank, a BOG compressor outlet tank, an air cooler, and a propylene pump, wherein the BOG compressor inlet buffer tank, the BOG compressor, the air cooler, the BOG compressor outlet tank, and the propylene pump are connected in sequence, the BOG compressor inlet buffer tank is connected to the low-temperature propylene tank through a pipeline, and the propylene pump is connected to the low-temperature propylene tank through a pipeline; the control system also includes a cooling circuit, which is used to transport liquid propylene to the BOG compressor inlet buffer tank so that the inlet temperature of the BOG compressor is reduced by gasification of liquid propylene. The present invention is used to prevent the BOG compressor from frequently undergoing interlocking shutdown due to high outlet temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of propylene production process, and in particular to a control system for controlling the inlet temperature of a low-temperature propylene BOG compressor and a method for adjusting the inlet temperature of a low-temperature propylene BOG compressor by using the control system. Background Art

[0002] The low-temperature propylene tank is affected by the temperature, ship connection, and device feed, and part of the liquid propylene is vaporized, resulting in an increase in tank pressure. In order to reduce the tank pressure, the BOG compressor needs to be turned on to pressurize the gaseous propylene, condense the gaseous propylene into liquid propylene through the air cooler, and then send it back to the low-temperature propylene tank by the propylene pump. Because the tank pressure of the low-temperature propylene tank will not rise quickly, the BOG compressor is turned on intermittently. During the shutdown of the BOG compressor, due to the influence of the environment, the propylene gas in the inlet pipe of the BOG compressor is heated by the environment and the temperature rises. When the BOG compressor is turned on again, the BOG compressor often shuts down due to the high outlet temperature, and this problem is particularly prominent in summer. Summary of the invention

[0003] The object of the present invention is to provide a control system and method for controlling the inlet temperature of a low-temperature propylene BOG compressor, which solves the technical problem in the prior art that the BOG compressor often undergoes interlocking shutdown due to high outlet temperature. The preferred technical solutions among the many technical solutions provided by the present invention can produce many technical effects as described below.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] The present invention provides a control system for controlling the inlet temperature of a low-temperature propylene BOG compressor, comprising a BOG compressor, a BOG compressor inlet buffer tank, a BOG compressor outlet tank, an air cooler and a propylene pump, wherein the BOG compressor inlet buffer tank, the BOG compressor, the air cooler, the BOG compressor outlet tank and the propylene pump are connected in sequence, the BOG compressor inlet buffer tank is connected to a low-temperature propylene tank through a pipeline, and the propylene pump is connected to the low-temperature propylene tank through a pipeline; the control system also includes a cooling circuit, which is used to transport liquid propylene to the BOG compressor inlet buffer tank so that the inlet temperature of the BOG compressor is reduced by gasification of liquid propylene.

[0006] Furthermore, the cooling circuit connects the propylene pump and the BOG compressor inlet buffer tank, and the propylene pump can transport the liquid propylene in the BOG compressor outlet tank to the BOG compressor inlet buffer tank through the cooling circuit to reduce the inlet temperature of the BOG compressor.

[0007] Furthermore, the cooling circuit includes a cooling pipe and a valve body, the cooling pipe connects the propylene pump and the BOG compressor inlet buffer tank, the valve body is arranged on the cooling pipe, and the valve body is a manual valve or an automatic valve.

[0008] Furthermore, the valve body is an automatic control valve; the control system also includes a temperature sensor and a temperature control device, the temperature sensor and the valve body are connected to the temperature control device, the temperature sensor is arranged in the pipeline between the BOG compressor and the BOG compressor inlet buffer tank, the temperature sensor is used to transmit the detected temperature signal to the temperature control device, and the temperature control device can control the opening and closing of the valve body according to the received temperature signal.

[0009] Furthermore, an atomizing nozzle is also provided at the end of the cooling loop, and the liquid propylene in the cooling loop is discharged into the inlet buffer tank of the BOG compressor through the atomizing nozzle.

[0010] Furthermore, the BOG compressor inlet buffer tank includes a first inlet, a second inlet and a discharge port, the first inlet is connected to the low-temperature propylene tank, the second inlet is connected to the cooling circuit, and the discharge port is connected to the BOG compressor through a pipeline.

[0011] Furthermore, an outlet valve is provided on the pipeline connecting the BOG compressor inlet buffer tank and the BOG compressor, and the outlet valve is close to the discharge port; the pipeline between the BOG compressor inlet buffer tank and the low-temperature propylene tank is a gas phase pipeline, and an inlet valve is provided on the gas phase pipeline, and a pressure sensor is provided on the section of the inlet valve close to the low-temperature propylene tank.

[0012] Furthermore, a propylene liquid level gauge is provided on the inlet buffer tank of the BOG compressor; the propylene liquid level gauge is provided with a high liquid level alarm device, and when the liquid level in the inlet buffer tank of the BOG compressor reaches a predetermined height value, the high liquid level alarm device can send out an alarm signal.

[0013] A method for adjusting the inlet temperature of a low-temperature propylene BOG compressor by using the control system comprises the following contents: before starting the BOG compressor, judging whether it is necessary to lower the inlet temperature of the BOG compressor; if it is judged that it is necessary to lower the inlet temperature of the BOG compressor, transmitting liquid propylene to the inlet buffer tank of the BOG compressor through the cooling circuit so as to lower the inlet temperature of the BOG compressor by gasifying the liquid propylene.

[0014] Furthermore, the cooling circuit connects the propylene pump and the BOG compressor inlet buffer tank. When the inlet temperature of the BOG compressor is higher than a preset value, the valve body between the propylene pump and the BOG compressor outlet tank is automatically opened to start the propylene pump. The propylene pump transports the liquid propylene in the BOG compressor outlet tank to the BOG compressor inlet buffer tank through the cooling circuit to reduce the inlet temperature of the BOG compressor.

[0015] The control system for controlling the inlet temperature of a low-temperature propylene BOG compressor provided by the present invention aims to reduce the outlet temperature of the BOG compressor by reducing the inlet temperature of the BOG compressor, thereby reducing the interlocking shutdown phenomenon caused by high outlet temperature. The specific method is as follows: a cooling circuit is added, and liquid propylene is transported to the inlet buffer tank of the BOG compressor through the cooling circuit so that the inlet temperature of the BOG compressor is reduced by gasification of the liquid propylene. The cooling method is simple and easy to implement.

[0016] The preferred technical solution of the present invention can at least produce the following technical effects:

[0017] The present invention provides power through a propylene pump to transport the liquid propylene in the BOG compressor outlet tank to the BOG compressor inlet buffer tank. That is to say, during operation, a certain amount of liquid propylene needs to be reserved in the compressor outlet tank, and not all of it is pumped into the low-temperature propylene tank, so as to be used for liquid propylene gasification to reduce the BOG compressor inlet temperature.

[0018] The temperature sensor and the valve body are connected to the temperature control device. The temperature sensor is arranged in the pipeline between the BOG compressor and the buffer tank at the inlet of the BOG compressor. When the temperature in the inlet pipe of the BOG compressor exceeds the preset value in the temperature control device, the temperature control device controls the valve body to open, thereby realizing automatic opening of the valve body.

[0019] The liquid propylene in the cooling circuit is discharged into the buffer tank at the inlet of the BOG compressor through the atomizing nozzle, and the atomizing nozzle is conducive to the gasification of the liquid propylene;

[0020] A propylene level gauge is provided on the inlet buffer tank of the BOG compressor. The propylene level gauge can be used to grasp the liquid level status of the liquid propylene in the inlet buffer tank of the BOG compressor to avoid the risk of BOG compressor liquid hammer caused by too much liquid propylene in the inlet buffer tank of the BOG compressor. The propylene level gauge is provided with a high liquid level alarm device. When the liquid level in the inlet buffer tank of the BOG compressor reaches a predetermined height value, the high liquid level alarm device can send out an alarm signal. The alarm signal can be an acoustic signal and / or a light signal. The high liquid level alarm device can be used to warn and improve safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of a control system for controlling the inlet temperature of a low-temperature propylene BOG compressor provided by an embodiment of the present invention.

[0023] In the figure, 1-BOG compressor; 2-BOG compressor inlet buffer tank; 201-first inlet; 202-second inlet; 203-discharge port; 3-BOG compressor outlet tank; 4-air cooler; 5-propylene pump; 6-low-temperature propylene tank; 7-cooling pipeline; 8-valve body; 9-temperature control device; 10-gas phase pipeline; 11-inlet valve; 12-outlet valve; 13-propylene liquid level meter. DETAILED DESCRIPTION

[0024] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0025] See also Figure 1The present invention provides a control system for controlling the inlet temperature of a low-temperature propylene BOG compressor, comprising a BOG compressor 1, a BOG compressor inlet buffer tank 2, a BOG compressor outlet tank 3, an air cooler 4 and a propylene pump 5, wherein the BOG compressor inlet buffer tank 2, the BOG compressor 1, the BOG compressor outlet tank 3, the air cooler 4 and the propylene pump 5 are connected in sequence, the BOG compressor inlet buffer tank 2 is connected to the low-temperature propylene tank 6 through a pipeline, and the propylene pump 5 is connected to the low-temperature propylene tank 6 through a pipeline; the control system also includes a cooling circuit, which is used to transport liquid propylene to the BOG compressor inlet buffer tank 2 so that the inlet temperature of the BOG compressor 1 is reduced by gasification of liquid propylene. In the prior art, the BOG compressor needs to be turned on intermittently. During the shutdown of the BOG compressor, due to the influence of the environment, the propylene gas in the inlet pipe of the BOG compressor is heated by the environment and the temperature rises. When the BOG compressor is turned on again, the BOG compressor often stops due to the high outlet temperature, and this problem is particularly prominent in summer. The control system provided by the present invention aims to reduce the outlet temperature of the BOG compressor by reducing the inlet temperature of the BOG compressor 1, thereby reducing the interlocking shutdown phenomenon caused by high outlet temperature. The specific method is as follows: a cooling circuit is added, and liquid propylene is transported to the inlet buffer tank 2 of the BOG compressor through the cooling circuit so that the inlet temperature of the BOG compressor 1 is reduced by gasification of the liquid propylene. The cooling method is simple and easy to implement.

[0026] Regarding the cooling circuit, the details are as follows: Figure 1 The cooling circuit connects the propylene pump 5 and the BOG compressor inlet buffer tank 2. The propylene pump 5 can transport the liquid propylene in the BOG compressor outlet tank 3 to the BOG compressor inlet buffer tank 2 through the cooling circuit to reduce the inlet temperature of the BOG compressor 1. The present invention provides power through the propylene pump 5 to transport the liquid propylene in the BOG compressor outlet tank 3 to the BOG compressor inlet buffer tank 2. That is to say, during operation, a certain amount of liquid propylene needs to be reserved in the compressor outlet tank 3, and not all of it is pumped into the low-temperature propylene tank 6. A propylene liquid level gauge can be provided on the compressor outlet tank 3 to grasp the liquid level of the liquid propylene in the compressor outlet tank 3.

[0027] See also Figure 1 The cooling circuit includes a cooling pipe 7 and a valve body 8. The cooling pipe 7 connects the propylene pump 5 and the BOG compressor inlet buffer tank 2. The valve body 8 is arranged on the cooling pipe 7, and the valve body 8 is a manual valve or an automatic valve. When it is not necessary to transport the liquid propylene from the compressor outlet tank 3 to the BOG compressor inlet buffer tank 2, the valve body 8 is in a closed state. When it is necessary to transport the liquid propylene from the compressor outlet tank 3 to the BOG compressor inlet buffer tank 2, the valve body 8 is in an open state. In addition, a valve can also be arranged on the pipe between the propylene pump 5 and the low-temperature propylene tank 6.

[0028] The valve body 8 is preferably an automatic control valve; the control system also includes a temperature sensor and a temperature control device 9, the temperature sensor and the valve body 8 are connected to the temperature control device 9, the temperature sensor is arranged in the pipeline between the BOG compressor 1 and the BOG compressor inlet buffer tank 2, the temperature sensor is used to transmit the detected temperature signal to the temperature control device 9, and the temperature control device 9 can control the opening and closing of the valve body 8 according to the received temperature signal. When the BOG compressor 1 is shut down, due to the influence of the environment, the propylene gas in the inlet pipe of the BOG compressor 1 is heated by the environment and the temperature rises. When the temperature in the inlet pipe of the BOG compressor 1 exceeds the preset value in the temperature control device 9, the temperature control device 9 controls the valve body 8 to open, the propylene pump 5 is started, and the liquid propylene in the BOG compressor outlet tank 3 is transported to the BOG compressor inlet buffer tank 2 through the cooling pipeline 7.

[0029] As an optional implementation, an atomizing nozzle is further provided at the end of the cooling loop, and the liquid propylene in the cooling loop is discharged into the BOG compressor inlet buffer tank 2 through the atomizing nozzle, and the atomizing nozzle is conducive to the gasification of the liquid propylene.

[0030] See also Figure 1 The BOG compressor inlet buffer tank 2 includes a first inlet 201, a second inlet 202 and an outlet 203. The first inlet 201 is connected to the low-temperature propylene tank 6, the second inlet 202 is connected to the cooling circuit, and the outlet 203 is connected to the BOG compressor 1 through a pipeline. An outlet valve 12 is provided on the pipeline connecting the BOG compressor inlet buffer tank 2 and the BOG compressor 1, and the outlet valve 12 is close to the outlet 203. The pipeline between the BOG compressor inlet buffer tank 2 and the low-temperature propylene tank 6 is a gas phase pipeline 10, and an inlet valve 11 is provided on the gas phase pipeline 10. A pressure sensor is provided on the section of the inlet valve 11 close to the low-temperature propylene tank 6.

[0031] As an optional implementation, a propylene liquid level meter 13 is provided on the BOG compressor inlet buffer tank 2. The propylene liquid level meter 13 is used to grasp the liquid level state of the liquid phase propylene in the BOG compressor inlet buffer tank 2 to avoid too much liquid phase propylene in the BOG compressor inlet buffer tank 2, which may cause the risk of liquid hammer in the BOG compressor 1; the propylene liquid level meter 13 is provided with a high liquid level alarm device. When the liquid level in the BOG compressor inlet buffer tank 2 reaches a predetermined height value, the high liquid level alarm device can send an alarm signal. The alarm signal may be an acoustic signal and / or an optical signal. The high liquid level alarm device is used to provide a warning to improve safety.

[0032] A method for adjusting the inlet temperature of a low-temperature propylene BOG compressor by using a control system includes the following contents: before starting the BOG compressor 1, judging whether the inlet temperature of the BOG compressor 1 needs to be lowered; if it is judged that the inlet temperature of the BOG compressor 1 needs to be lowered, liquid propylene is transported to the inlet buffer tank 2 of the BOG compressor through a cooling circuit so as to reduce the inlet temperature of the BOG compressor 1 by gasifying the liquid propylene. Then, the BOG compressor 1 is started, and at the same time, the inlet temperature of the BOG compressor 1 is detected in real time. When the inlet temperature of the BOG compressor 1 is reduced to a preset value, the liquid propylene is prevented from being transported to the inlet buffer tank 2 of the BOG compressor through the cooling circuit.

[0033] Specifically, the cooling circuit connects the propylene pump 5 and the BOG compressor inlet buffer tank 2, and the temperature sensor detects the inlet temperature of the BOG compressor 1 in real time. Before starting the BOG compressor 1, when it is detected that the temperature in the inlet pipe of the BOG compressor 1 exceeds the preset value in the temperature control device 9, the temperature control device 9 controls the valve body 8 to open (that is, the valve body 8 is automatically opened). At the same time, the temperature sensor transmits a signal to the PLC control device of the control system, so that the PLC control device controls the propylene pump 5 to start, and the propylene pump 5 transports the liquid propylene in the BOG compressor outlet tank 3 to the BOG compressor inlet buffer tank 2 through the cooling pipeline 7 to reduce the inlet temperature of the BOG compressor 1. Then the BOG compressor 1 is turned on, and as the inlet temperature of the BOG compressor 1 gradually decreases, the valve body 8 is controlled to gradually reduce the opening. When the inlet temperature of the BOG compressor 1 decreases to the preset value, the valve body 8 is completely closed to achieve stable operation of the BOG compressor 1.

[0034] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A control system for controlling the inlet temperature of a low-temperature propylene BOG compressor, characterized in that: The invention comprises a BOG compressor (1), a BOG compressor inlet buffer tank (2), a BOG compressor outlet tank (3), an air cooler (4) and a propylene pump (5), wherein the BOG compressor inlet buffer tank (2), the BOG compressor (1), the air cooler (4), the BOG compressor outlet tank (3) and the propylene pump (5) are connected in sequence, the BOG compressor inlet buffer tank (2) is connected to a low-temperature propylene tank (6) via a pipeline, and the propylene pump (5) is connected to the low-temperature propylene tank (6) via a pipeline; The control system further comprises a temperature reduction circuit, wherein the temperature reduction circuit is used to transport the liquid phase propylene to the BOG compressor inlet buffer tank (2) so as to reduce the inlet temperature of the BOG compressor (1) by gasification of the liquid phase propylene; The cooling circuit is connected to the propylene pump (5) and the BOG compressor inlet buffer tank (2), and the propylene pump (5) can transport the liquid propylene in the BOG compressor outlet tank (3) to the BOG compressor inlet buffer tank (2) through the cooling circuit to reduce the inlet temperature of the BOG compressor (1); The cooling circuit comprises a cooling pipe (7) and a valve body (8); the cooling pipe (7) is connected to the propylene pump (5) and the BOG compressor inlet buffer tank (2); the valve body (8) is arranged on the cooling pipe (7), and the valve body (8) is a manual valve or an automatic valve; An atomizing nozzle is also provided at the end of the cooling loop, and the liquid propylene in the cooling loop is discharged into the BOG compressor inlet buffer tank (2) through the atomizing nozzle.

2. The control system for controlling the inlet temperature of the low-temperature propylene BOG compressor according to claim 1, characterized in that: The valve body (8) is an automatic control valve; the control system further comprises a temperature sensor and a temperature control device (9); the temperature sensor and the valve body (8) are connected to the temperature control device (9); the temperature sensor is arranged in a pipeline between the BOG compressor (1) and the BOG compressor inlet buffer tank (2); the temperature sensor is used to transmit a detected temperature signal to the temperature control device (9); and the temperature control device (9) can control the opening and closing of the valve body (8) according to the received temperature signal.

3. The control system for controlling the inlet temperature of the low-temperature propylene BOG compressor according to claim 1 or 2, characterized in that: The BOG compressor inlet buffer tank (2) comprises a first inlet (201), a second inlet (202) and an outlet (203), wherein the first inlet (201) is connected to the low-temperature propylene tank (6), the second inlet (202) is connected to the cooling circuit, and the outlet (203) is connected to the BOG compressor (1) via a pipeline.

4. The control system for controlling the inlet temperature of the low-temperature propylene BOG compressor according to claim 3, characterized in that: An outlet valve (12) is provided on a pipeline connecting the BOG compressor inlet buffer tank (2) and the BOG compressor (1), and the outlet valve (12) is close to the discharge port (203); The pipeline between the BOG compressor inlet buffer tank (2) and the low-temperature propylene tank (6) is a gas phase pipeline (10), an inlet valve (11) is provided on the gas phase pipeline (10), and a pressure sensor is provided on a section of the inlet valve (11) close to the low-temperature propylene tank (6).

5. The control system for controlling the inlet temperature of a low-temperature propylene BOG compressor according to claim 1 or 2, characterized in that: The BOG compressor inlet buffer tank (2) is provided with a propylene liquid level meter (13); The propylene liquid level meter (13) is provided with a high liquid level alarm device, and when the liquid level in the buffer tank (2) at the inlet of the BOG compressor reaches a predetermined height value, the high liquid level alarm device can send out an alarm signal.

6. A method for adjusting the inlet temperature of a low-temperature propylene BOG compressor using the control system according to claim 1 or 2, characterized in that: Includes the following: Before starting the BOG compressor (1), determining whether it is necessary to reduce the inlet temperature of the BOG compressor (1); If it is determined that the inlet temperature of the BOG compressor (1) needs to be lowered, the liquid propylene is transported to the BOG compressor inlet buffer tank (2) through the cooling circuit to lower the inlet temperature of the BOG compressor (1) by gasifying the liquid propylene.

7. The method according to claim 6, characterized in that The cooling circuit connects the propylene pump (5) and the BOG compressor inlet buffer tank (2). When the inlet temperature of the BOG compressor (1) is higher than a preset value, the valve body (8) between the propylene pump (5) and the BOG compressor outlet tank (3) automatically opens to start the propylene pump (5). The propylene pump (5) transports the liquid propylene in the BOG compressor outlet tank (3) to the BOG compressor inlet buffer tank (2) through the cooling circuit to reduce the inlet temperature of the BOG compressor (1).

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