Screw expander oil pump and shaft head pump switching system

Abstract

The utility model discloses a screw expander oil pump and shaft head pump switching system which comprises an oil tank, an alternating current lubricating oil pump, a filter, a heat exchanger and a shaft head pump, the shaft head pump is a gear pump, and the shaft head pump and the alternating current lubricating oil pump are respectively installed on two branch oil outlet pipes which are arranged in parallel. The filter and the heat exchanger are installed on a public oil pipe, the filter is located at the front end of the heat exchanger, a pressure transmitter is installed on the public oil pipe at the rear end of the heat exchanger, the pressure transmitter, the shaft head pump and the alternating current lubricating oil pump are arranged in an interlocking mode, and the public oil pipe is connected with the oil tank through a first oil return pipe; a public oil pipe between the heat exchanger and the pressure transmitter is connected with the oil tank through an oil return pipe II; according to the oil pump and shaft head pump switching system, when a power supply system or an alternating-current lubricating oil pump breaks down, the shaft head pump keeps operating together with equipment, lubricating oil is continuously provided for a lubricating and cooling system of the screw expander, and normal operation of the equipment is effectively protected.

Description

Technical Field

[0001] The utility model relates to the technical field of lubricating and cooling systems for screw expanders, and particularly relates to a switching system for a screw expander oil pump and a shaft head pump. Background Art

[0002] The initial lubricating oil cooling systems of screw expanders were all designed to operate with a single pump or a dual-pump operation system with one in use and one in reserve. In actual operation, if a single-pump system fails, the screw expander must be shut down. If it cannot be repaired in a short time, significant economic losses will occur. For a dual-pump system with one in use and one in reserve, if a single pump fails, although it can be switched to the standby pump for operation, the main defect is that if the power supply system fails, the standby pump cannot be put into operation either. The sliding bearing system of the screw expander will quickly burn out or even seize during high-speed operation due to the inability to supply oil, resulting in relatively large economic losses. Content of the Utility Model

[0003] The purpose of the utility model is to provide a switching system for a screw expander oil pump and a shaft head pump.

[0004] The above technical purpose of the utility model is achieved through the following technical solutions:

[0005] A switching system for a screw expander oil pump and a shaft head pump includes an oil tank, an AC lubricating oil pump, a filter, and a heat exchanger, and further includes a shaft head pump. The shaft head pump is a gear pump, which is installed on the extension shaft of the screw expander in the front bearing box and is rigidly connected to the main shaft of the screw expander and directly driven by the main shaft of the screw expander. The shaft head pump and the AC lubricating oil pump are respectively installed on two parallel branched outlet oil pipes. One end of the two branched outlet oil pipes is connected to the oil tank, and the other ends of the two branched outlet oil pipes are connected to a common oil pipe through a three-way joint. The filter and the heat exchanger are installed on the common oil pipe, and the filter is located at the front end of the heat exchanger. A pressure transmitter is installed on the common oil pipe at the rear end of the heat exchanger, and an interlock is set between the pressure transmitter and the shaft head pump and the AC lubricating oil pump. A pressure gauge is provided on the common oil pipe at the front end of the filter, and this section of the common oil pipe is connected to the oil tank through a first return oil pipe, and a safety valve is installed on the first return oil pipe; the common oil pipe between the heat exchanger and the pressure transmitter is connected to the oil tank through a second return oil pipe, and a self-operated regulating valve is installed on the second return oil pipe.

[0006] Furthermore, a pressure gauge is also installed on the common oil pipe between the heat exchanger and the filter to monitor the oil pressure on this pipeline. Through the two pressure gauges, the pressures at both ends of the inlet and outlet of the filter are monitored to determine whether the filter is working properly.

[0007] Further, the heat exchanger is a plate heat exchanger, which can be selected according to requirements. Its main function is to reduce the temperature of the oil fluid and provide a cooling medium with a lower temperature for the screw expander.

[0008] In summary, the present utility model has the following beneficial effects:

[0009] 1. For the oil pump and shaft head pump switching system designed by the present utility model, when the power supply system or the AC lubricating oil pump fails, the shaft head pump will continue to operate with the equipment and continuously supply lubricating oil to the lubrication and cooling system of the screw expander, effectively protecting the normal operation of the equipment.

[0010] 2. This oil pump and shaft head pump switching system effectively overcomes the defects of single pump operation or one - use - one - standby dual - pump operation systems in the prior art, improves the stability of equipment operation, reduces downtime for maintenance, and improves production economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic structural diagram of the system of the present utility model;

[0012] Figure 2 is the start - up of the AC lubricating oil pump and the switching logic control with the shaft head pump Figure 1 ;

[0013] Figure 3 is the start - up of the AC lubricating oil pump and the switching logic control with the shaft head pump Figure 2 ;

[0014] Figure 4 is the start - up of the AC lubricating oil pump and the switching logic control with the shaft head pump Figure 3 ;

[0015] Figure 5 is the start - up of the AC lubricating oil pump and the switching logic control with the shaft head pump Figure 4 。 DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The following further describes the present utility model in detail with reference to the drawings. The technical solutions in the embodiments of the present utility model are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of them. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0017] A screw expander oil pump and shaft head pump switching system, as Figure 1As shown in the figure, it includes an oil tank, an AC lubricating oil pump, a filter, and a heat exchanger, and also includes a shaft head pump. The shaft head pump is a gear pump, which is installed on the extension shaft of the screw expander in the front bearing box, rigidly connected to the main shaft of the screw expander, and directly driven by the main shaft of the screw expander. The shaft head pump and the AC lubricating oil pump are respectively installed on two parallel branch outlet oil pipes. One end of the two branch outlet oil pipes is connected to the oil tank, and the other ends of the two branch outlet oil pipes are connected to the common oil pipe through a three-way joint. The filter and the heat exchanger are installed on the common oil pipe, and the filter is located at the front end of the heat exchanger. A pressure transmitter is installed on the common oil pipe at the rear end of the heat exchanger. The pressure transmitter is interlocked with the shaft head pump and the AC lubricating oil pump. Whether the AC lubricating oil pump or the shaft head pump starts, the change of the system pressure can be shown on this pressure transmitter. The pressure transmitter outputs a 4-20MA signal, and the PLC system reads this signal and participates in the logic interlock to judge whether to start or stop the AC lubricating oil pump. A pressure gauge is provided on the common oil pipe at the front end of the filter, and this section of the common oil pipe is connected to the oil tank through a first return oil pipe. A safety valve is installed on the first return oil pipe; the common oil pipe between the heat exchanger and the pressure transmitter is connected to the oil tank through a second return oil pipe, and a self-operated regulating valve is installed on the second return oil pipe.

[0018] Furthermore, a pressure gauge is also installed on the common oil pipe between the heat exchanger and the filter to monitor the oil pressure on this pipeline. Through the two pressure gauges, the pressures at both ends of the inlet and outlet of the filter are monitored to judge whether the filter is working properly.

[0019] Furthermore, the heat exchanger adopts a plate heat exchanger. The heat exchanger can be selected according to requirements. Its main function is to reduce the temperature of the oil and provide a cooling medium with a lower temperature for the screw expander.

[0020] Working principle:

[0021] When the screw expander starts: First, start the AC lubricating oil pump to establish the oil pressure in the oil lubrication and cooling system. Then, during the turning process, the system will be supplied with lubricating oil by both the AC lubricating oil pump and the shaft head pump. If the oil pressure is too high, the lubricating oil will be returned to the oil tank through the self-operated regulating valve and the safety valve through the return oil pipeline. When the screw expander is connected to the grid and generates electricity, the rotational speed of the screw expander will stabilize at the rated speed. At this time, the rotational speed of the shaft head pump is stable, and the oil supply pressure is stable. In order to ensure the stable operation and smooth switching of the oil supply system, the oil supply pressure is monitored in real time through the PLC system. When the operation requirements of the system are met (P≥0.2Mpa), after a 10S delay, the AC lubricating oil pump will be automatically stopped, and the shaft head pump will provide the cooling and lubrication for the entire lubricating oil system.

[0022] During the parallel operation of the screw expander: If the PLC system monitors that the oil supply pressure of the shaft head pump is lower than the minimum requirement of the system (P ≤ 0.14 Mpa), the AC lubricating oil pump will automatically start through the PLC system and supply lubricating oil to the system together with the shaft head pump.

[0023] The start-up of the AC lubricating oil pump and the switching logic control with the shaft head pump are as follows:

[0024] As Figure 2 shown, for the start-up and rotation signal of the screw expander, when the start lubricating oil pump and start screw expander buttons are clicked on the WINCC system, the oil pressure ≥ 0.2 Mpa, and there is no shutdown interlock signal at the same time, the screw expander enters the start-up and rotation state.

[0025] As Figure 3 shown, 10S after the parallel operation of the screw expander, when the lubricating oil pressure ≥ 0.2 Mpa, the AC lubricating oil pump will automatically stop.

[0026] As Figure 4 shown, when the lubricating oil pressure ≤ 0.14 Mpa during the parallel operation of the screw expander, the AC lubricating oil pump will automatically start.

[0027] As Figure 5 shown, when the shutdown signal of the screw expander is triggered and the grid-connected circuit breaker is tripped, the AC lubricating oil pump will automatically start.

[0028] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A screw expander oil pump and shaft head pump switching system, comprising an oil tank, an AC lubricating oil pump, a filter and a heat exchanger, characterized in that: It also includes a shaft head pump, which is respectively installed on two branch oil outlet pipes arranged in parallel. One end of the two branch oil outlet pipes is connected to the oil tank, and the other end of the two branch oil outlet pipes is connected to the common oil pipe through a three-way joint. The filter and the heat exchanger are installed on the common oil pipe, and the filter is located at the front end of the heat exchanger. A pressure transmitter is installed on the common oil pipe at the rear end of the heat exchanger. The pressure transmitter is interlocked with the shaft head pump and the AC lubricating oil pump. A pressure gauge is provided on the common oil pipe at the front end of the filter, and this section of the common oil pipe is connected to the oil tank through a return oil pipe 1, and a safety valve is installed on the return oil pipe 1; the common oil pipe between the heat exchanger and the pressure transmitter is connected to the oil tank through a return oil pipe 2, and a self-operated regulating valve is installed on the return oil pipe 2.

2. A screw expander oil pump and shaft head pump switching system according to claim 1, characterized in that: A pressure gauge is also installed on the common oil pipe between the heat exchanger and the filter.

3. A screw expander oil pump and shaft head pump switching system according to claim 1, characterized in that: The heat exchanger is a plate heat exchanger.

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