Expander sealing gas heating system

Abstract

The utility model discloses a sealing gas heating system of an expander. The sealing gas heating system comprises a propylene heat exchanger, a sealing gas temperature detection device and a propylene flow regulating valve, the first input end of the propylene heat exchanger is connected with the top of the methane hydrogen self-demethanizing tower, and the first output end of the propylene heat exchanger is connected with the expansion machine; a second input end of the propylene heat exchanger is connected with a propylene receiving tank, and a second output end of the propylene heat exchanger is connected with a propylene machine three-section suction tank; the sealed gas temperature detection device is connected between the propylene heat exchanger and the expansion machine; and the propylene flow regulating valve is connected between the propylene heat exchanger and the propylene machine three-section suction tank. The problems that in the prior art, the flow and temperature stability of sealing gas subjected to electric heating is poor, and interlocking shutdown is likely to be triggered are solved, stable heating of the sealing gas is achieved, the system stability is improved, frequent shutdown accidents are avoided, and the technical effects of saving energy and reducing consumption are further achieved.

Description

Technical Field

[0001] The present application relates to the technical field of sealing gas heating, and in particular to an expander sealing gas heating system. Background Art

[0002] The expansion side medium temperature of the methane tail gas expansion recompressor in the ethylene plant is much lower than the compressor side medium temperature. In order to avoid the low temperature cold energy being transferred along the axial compressor side, it is usually necessary to use a sealing system for isolation. The sealing gas is usually the low temperature methane tail gas at the expansion recompressor inlet (i.e. the top of the demethanizer tower), which is heated to a suitable temperature (about 20°C) by a heat exchanger, and then the sealing gas is adjusted to a suitable pressure by a differential pressure control regulating valve and then introduced into the sealing cavity.

[0003] The existing device design uses an electric heater to heat the expansion recompressor seal gas, which needs to be heated from -98°C to 20°C. However, in actual production practice, it is found that the temperature stability of the seal gas after electric heating is poor, which can easily trigger an interlock shutdown accident and have an adverse effect on the stable operation of the unit and refrigeration system. At the same time, the electric heater runs almost uninterruptedly all year round, with high energy consumption. In view of this, it is urgent to explore a more stable and reliable seal gas heating method. Utility Model Content

[0004] The embodiment of the present application provides an expander sealing gas heating system, which solves the problem in the prior art that the flow and temperature stability of the sealing gas after electric heating are poor and easily triggers interlock shutdown, thereby achieving stable heating of the sealing gas, improving system stability, avoiding the occurrence of frequent shutdown accidents, and also achieving the technical effect of energy saving and consumption reduction.

[0005] The utility model embodiment provides an expander sealing gas heating system, comprising a propylene heat exchanger, a sealing gas temperature detection device and a propylene flow regulating valve; the first input end of the propylene heat exchanger is connected to the top of the methane hydrogen self-demethanization tower, and the first output end of the propylene heat exchanger is connected to the expander; the second input end of the propylene heat exchanger is connected to a self-propylene receiving tank, and the second output end of the propylene heat exchanger is connected to a three-stage suction tank of the propylene machine; the sealing gas temperature detection device is connected between the propylene heat exchanger and the expander; the propylene flow regulating valve is connected between the propylene heat exchanger and the three-stage suction tank of the propylene machine.

[0006] In a possible implementation, an electric heater is further included; the input end of the electric heater is connected to the top of the methane hydrogen self-demethanization tower, and the output end of the electric heater is connected to the expander.

[0007] In a possible implementation, a sealing gas flow monitoring device is further included; the sealing gas flow monitoring device is connected between the propylene heat exchanger and the expander.

[0008] In a possible implementation, a propylene flow monitoring device is further included; the propylene flow monitoring device is connected between the propylene heat exchanger and the self-propylene receiving tank.

[0009] In a possible implementation, it also includes a sealing gas cut-off valve, a front gate valve of the electric heater and a rear gate valve of the electric heater; the sealing gas cut-off valve is connected to the output end of the methane hydrogen from the top of the demethanizer; the front gate valve of the electric heater is connected to the input end of the electric heater; the rear gate valve of the electric heater is connected to the output end of the electric heater; the first input end of the propylene heat exchanger is connected between the front gate valve of the electric heater and the sealing gas cut-off valve.

[0010] In a possible implementation, it also includes a gate valve before the propylene flow regulating valve and a gate valve after the propylene flow regulating valve; the gate valve before the propylene flow regulating valve is connected between the propylene heat exchanger and the propylene flow regulating valve; the gate valve after the propylene flow regulating valve is connected between the propylene flow regulating valve and the three-stage suction tank of the propylene machine.

[0011] In a possible implementation, a propylene gate valve is further included; the propylene gate valve is connected between the self-propylene receiving tank and the propylene flow monitoring device.

[0012] One or more technical solutions provided by this application have at least the following technical effects:

[0013] The embodiment of the utility model adopts a propylene heat exchanger, a sealing gas temperature detection device and a propylene flow regulating valve; the first input end of the propylene heat exchanger is connected between the electric heater and the top of the methane hydrogen self-demethanizer, and the first output end of the propylene heat exchanger is connected to the expander; the sealing gas output from the top of the methane hydrogen self-demethanizer can also be heat-exchanged by the propylene heat exchanger and then input into the expander; the second input end of the propylene heat exchanger is connected to the self-propylene receiving tank, and the second output end of the propylene heat exchanger is connected to the three-stage suction tank of the propylene machine, wherein the self-propylene receiving tank can output propylene with a higher temperature, and the top of the methane hydrogen self-demethanizer can output sealing gas with a lower temperature, the propylene heat exchanger can heat the sealing gas, and reduce the temperature of the propylene output from the self-propylene receiving tank, which has the technical effect of energy saving and consumption reduction. Furthermore, the sealing gas temperature detection device is connected between the propylene heat exchanger and the expander, and can monitor the temperature of the sealing gas output from the propylene heat exchanger; the propylene flow control valve is connected between the propylene heat exchanger and the three-stage suction tank of the propylene machine, and the propylene flow control valve can adjust the flow of propylene. The temperature of the sealing gas output from the propylene heat exchanger can be adjusted by the sealing gas temperature detection device and the propylene flow control valve, which ensures the stability of the temperature of the sealing gas after heating, thereby improving the stability of the system. The present application solves the problem in the prior art that the flow and temperature stability of the sealing gas after electric heating are poor and interlocking parking is easily triggered, realizes stable heating of the sealing gas, improves the stability of the system, avoids the occurrence of frequent parking accidents, and also achieves the technical effect of energy saving and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments of the utility model will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 A schematic diagram of an expander sealing gas heating system provided in an embodiment of the present application.

[0016] Icons: 1-electric heater; 2-propylene heat exchanger; 3-sealing gas temperature detection device; 31-sealing gas temperature remote meter; 32-sealing gas temperature local meter; 4-propylene flow regulating valve; 5-sealing gas flow monitoring device; 51-sealing gas remote flow meter; 52-sealing gas on-site flow meter; 6-propylene flow monitoring device; 61-propylene remote flow meter; 62-propylene on-site flow meter; 7-sealing gas cut-off valve; 8-gate valve before electric heater; 9-gate valve after electric heater; 10-gate valve before propylene flow regulating valve; 11-gate valve after propylene flow regulating valve; 12-propylene gate valve. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0018] In the description of the embodiments of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. The terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present utility model can be understood according to specific circumstances.

[0019] The utility model embodiment provides an expander sealing gas heating system, such as Figure 1 As shown, it includes an electric heater 1, a propylene heat exchanger 2, a sealing gas temperature detection device 3 and a propylene flow control valve 4; the first input end of the propylene heat exchanger 2 is connected to the top of the methane hydrogen self-demethanization tower, and the output end of the electric heater 1 is connected to the expander; the first input end of the propylene heat exchanger 2 is connected between the electric heater 1 and the top of the methane hydrogen self-demethanization tower, and the first output end of the propylene heat exchanger 2 is connected to the expander; the second input end of the propylene heat exchanger 2 is connected to the self-propylene receiving tank, and the second output end of the propylene heat exchanger 2 is connected to the three-stage suction tank of the propylene machine; the sealing gas temperature detection device 3 is connected between the propylene heat exchanger 2 and the expander; the propylene flow control valve 4 is connected between the propylene heat exchanger 2 and the three-stage suction tank of the propylene machine.

[0020] Exemplarily, the sealing gas temperature detection device 3 includes a sealing gas temperature remote transmission meter 31 and a sealing gas temperature local meter 32. One end of the sealing gas temperature local meter 32 is connected between the propylene heat exchanger 2 and the expander, and the sealing gas temperature remote transmission meter 31 is connected to the other end of the sealing gas temperature local meter 32. After the temperature is measured, it is transmitted to the sealing gas temperature remote transmission meter 31 (display TI) via the sealing gas temperature local meter 32 (temperature transmitter TT) for display.

[0021] Exemplarily, a controller is also included, and the sealing gas temperature remote transmission meter 31 and the propylene flow regulating valve 4 are both electrically connected to the controller. The controller can adjust the flow of propylene by operating the propylene flow regulating valve 4 according to the temperature of the sealing gas temperature remote transmission meter 31, thereby accurately controlling the temperature of the sealing gas and ensuring that the temperature of the sealing gas is within an appropriate range.

[0022] Exemplarily, propylene with a higher temperature can be output from the propylene receiving tank, and methane hydrogen can output a sealing gas with a lower temperature from the top of the demethanizer. The propylene heat exchanger 2 can heat the sealing gas and reduce the temperature of the propylene output from the propylene receiving tank, which has the technical effect of energy saving and consumption reduction.

[0023] Exemplarily, the sealing gas temperature detection device 3 and the propylene flow regulating valve 4 can also adjust the sealing gas temperature output from the propylene heat exchanger 2, ensuring the stability of the temperature of the sealing gas after heating, thereby improving the system stability and avoiding frequent shutdown accidents.

[0024] In the present application embodiment, Figure 1 As shown, it also includes an electric heater 1; the input end of the electric heater 1 is connected to the top of the methane hydrogen self-demethanizer, and the output end of the electric heater 1 is connected to the expander.

[0025] Exemplarily, the present application is an improvement on the original scheme, therefore, the present application also includes an electric heater 1, and the methane hydrogen can output a sealing gas with a lower temperature from the top of the demethanizer. The sealing gas output from the top of the methane hydrogen demethanizer can be heated by the electric heater 1 and then input into the expander for use. The electric heater 1 is provided with a front gate valve 8 and a rear gate valve 9 at both ends, which are in a closed state when not in use, so that the sealing gas output from the top of the methane hydrogen demethanizer is only heat exchanged through the propylene heat exchanger 2 and then input into the expander. The propylene output from the propylene receiving tank can be input into the propylene heat exchanger 2 for heat exchange, and while heating the sealing gas, the temperature of the propylene output from the propylene receiving tank is reduced, which has the technical effect of energy saving and consumption reduction.

[0026] In the present application embodiment, Figure 1 As shown, a sealing gas flow monitoring device 5 is also included; the sealing gas flow monitoring device 5 is connected between the propylene heat exchanger 2 and the expander.

[0027] Exemplarily, the sealing gas flow monitoring device 5 includes a sealing gas remote flowmeter 51 and a sealing gas on-site flowmeter 52. One end of the sealing gas on-site flowmeter 52 is connected between the propylene heat exchanger 2 and the expander, and the other end of the sealing gas on-site flowmeter 52 is connected to the sealing gas remote flowmeter 51. After the flow is measured, it is transmitted to the sealing gas remote flowmeter 51 (display FI) via the sealing gas on-site flowmeter 52 (flow transmitter FT) for display.

[0028] Exemplarily, the sealing gas flow rate monitoring device 5 can display the sealing gas flow rate delivered to the expander through the propylene heat exchanger 2, which is convenient for manual monitoring and control.

[0029] In the present application embodiment, Figure 1 As shown, a propylene flow monitoring device 6 is also included; the propylene flow monitoring device 6 is connected between the propylene heat exchanger 2 and the self-propylene receiving tank.

[0030] Exemplarily, the propylene flow monitoring device 6 includes a propylene on-site flow meter 62 and a propylene remote flow meter 61; one end of the propylene on-site flow meter 62 is connected between the propylene heat exchanger 2 and the propylene receiving tank, and the other end of the propylene on-site flow meter 62 is connected to the propylene remote flow meter 61. After the flow is measured, it is transmitted to the propylene remote flow meter 61 (display FI) via the propylene on-site flow meter 62 (flow transmitter FT) for display.

[0031] Exemplarily, the propylene flow rate monitoring device 6 can display the propylene flow rate transmitted from the propylene receiving tank to the propylene heat exchanger 2, which is convenient for manual monitoring and control.

[0032] In the present application embodiment, Figure 1 As shown, it also includes a sealing gas cut-off valve 7, a front gate valve 8 of the electric heater and a rear gate valve 9 of the electric heater; the sealing gas cut-off valve 7 is connected to the output end of the methane hydrogen from the top of the demethanizer; the front gate valve 8 of the electric heater is connected to the input end of the electric heater 1; the rear gate valve 9 of the electric heater is connected to the output end of the electric heater 1; the first input end of the propylene heat exchanger 2 is connected between the front gate valve 8 of the electric heater and the sealing gas cut-off valve 7.

[0033] Exemplarily, the sealing gas cut-off valve 7 can control the on-off of the sealing gas output from the top of the methane hydrogen self-demethanizer. When the electric heater front gate valve 8 and the electric heater rear gate valve 9 are closed, the electric heater 1 can be removed from the entire system, so that the sealing gas output from the top of the methane hydrogen self-demethanizer is only heat-exchanged by the propylene heat exchanger 2 and then input into the expander. By exchanging heat with propylene, the sealing gas can be heated and the temperature of propylene output from the propylene receiving tank can be reduced, which has the technical effect of energy saving and consumption reduction.

[0034] In the present application embodiment, Figure 1As shown, it also includes a gate valve 10 before the propylene flow regulating valve and a gate valve 11 after the propylene flow regulating valve; the gate valve 10 before the propylene flow regulating valve is connected between the propylene heat exchanger 2 and the propylene flow regulating valve 4; the gate valve 11 after the propylene flow regulating valve is connected between the propylene flow regulating valve 4 and the three-stage suction tank of the propylene machine.

[0035] For example, when the propylene flow regulating valve 4 fails and needs to be repaired, the gate valve 10 before the propylene flow regulating valve and the gate valve 11 after the propylene flow regulating valve are closed to make the propylene flow regulating valve 4 in an inoperative state, and then the propylene flow regulating valve 4 is repaired.

[0036] In the embodiment of the present application, a propylene gate valve 12 is also included; the propylene gate valve 12 is connected between the propylene receiving tank and the propylene flow monitoring device 6.

[0037] For example, the propylene gate valve 12 can control the on-off of the propylene output from the propylene receiving tank.

[0038] For example, during normal operation of the system, first, open the propylene gate valve 12 to introduce propylene with a higher temperature. Open the gate valve 10 before the propylene flow regulating valve, and open the gate valve 11 after the propylene flow regulating valve; secondly, open the sealing gas cut-off valve 7 to introduce sealing gas; finally, check the sealing gas temperature remote transmission meter 31, and the propylene flow regulating valve 4 can adjust the flow of propylene, so as to accurately control the temperature of the sealing gas and ensure that the temperature of the sealing gas is within a suitable range. When the propylene flow regulating valve 4 fails and needs maintenance, close the gate valve 10 before the propylene flow regulating valve and the gate valve 11 after the propylene flow regulating valve, so that the propylene flow regulating valve 4 is in an inoperative state, and then the propylene flow regulating valve 4 is repaired.

[0039] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0040] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. An expander sealing gas heating system, characterized in that: It comprises a propylene heat exchanger (2), a sealing gas temperature detection device (3) and a propylene flow regulating valve (4); The first input end of the propylene heat exchanger (2) is connected to the top of the methane hydrogen self-demethanization tower, and the first output end of the propylene heat exchanger (2) is connected to the expander; The second input end of the propylene heat exchanger (2) is connected to the propylene receiving tank, and the second output end of the propylene heat exchanger (2) is connected to the third-stage suction tank of the propylene machine; The sealing gas temperature detection device (3) is connected between the propylene heat exchanger (2) and the expander; The propylene flow regulating valve (4) is connected between the propylene heat exchanger (2) and the third-stage suction tank of the propylene machine.

2. The expander sealing gas heating system according to claim 1, characterized in that: Also includes an electric heater (1); The input end of the electric heater (1) is connected to the top of the methane hydrogen self-demethanization tower, and the output end of the electric heater (1) is connected to the expander.

3. The expander sealing gas heating system according to claim 1, characterized in that: It also includes a sealing gas flow monitoring device (5); The sealing gas flow monitoring device (5) is connected between the propylene heat exchanger (2) and the expander.

4. The expander sealing gas heating system according to claim 1, characterized in that: Also included is a propylene flow monitoring device (6); The propylene flow monitoring device (6) is connected between the propylene heat exchanger (2) and the self-propylene receiving tank.

5. The expander sealing gas heating system according to claim 2, characterized in that: It also includes a sealing gas cut-off valve (7), a front gate valve of the electric heater (8) and a rear gate valve of the electric heater (9); The sealing gas cut-off valve (7) is connected to the output end of the methane hydrogen from the top of the demethanizer; The front gate valve (8) of the electric heater is connected to the input end of the electric heater (1); the rear gate valve (9) of the electric heater is connected to the output end of the electric heater (1); The first input end of the propylene heat exchanger (2) is connected between the electric heater front gate valve (8) and the sealing gas cut-off valve (7).

6. The expander sealing gas heating system according to claim 1, characterized in that: It also includes a gate valve (10) before the propylene flow regulating valve and a gate valve (11) after the propylene flow regulating valve; The gate valve (10) before the propylene flow regulating valve is connected between the propylene heat exchanger (2) and the propylene flow regulating valve (4); The gate valve (11) after the propylene flow regulating valve is connected between the propylene flow regulating valve (4) and the three-stage suction tank of the propylene machine.

7. The expander sealing gas heating system according to claim 4, characterized in that: Also includes a propylene gate valve (12); The propylene gate valve (12) is connected between the self-propylene receiving tank and the propylene flow monitoring device (6).

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