Centrifugal unit and reliable operation system and control method thereof

Abstract

The reliable operation system comprises an evaporator, after refrigerants in the evaporator sequentially pass through a filter, a refrigerant pump and a first one-way valve, one path of the refrigerants enters a condenser through a first electromagnetic valve and a second one-way valve, and the other path of the refrigerants enters an air suction port of a compressor through a second electromagnetic valve; a liquid level sensor is arranged on the evaporator to collect the liquid level height of the evaporator; the control device is used for controlling start and stop of the first electromagnetic valve and the refrigerant pump by judging the liquid level height of the evaporator and the preset target liquid level height. The high-pressure end of the ejector is connected with a high-pressure refrigerant outlet of the condenser, the low-pressure end is connected with an air suction port of the compressor, and the outlet end is connected with the oil tank; when the centrifugal unit is started, excessive refrigerants in the evaporator can be pumped into the condenser, normal starting of the centrifugal unit is guaranteed, when the centrifugal unit runs, the problem of oil return failure can be avoided, and the running reliability of the centrifugal unit is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of centrifugal unit, in particular to a centrifugal unit, a reliable operation system thereof and a control method. BACKGROUND

[0002] In addition to the refrigeration cycle system for realizing the main refrigeration and heating functions, the centrifugal unit also needs to be equipped with corresponding compressor bearing lubricating oil supply system, oil return system, auxiliary starting system and the like to ensure reliable operation of the unit.

[0003] During operation of the unit, a small amount of lubricating oil inevitably dissolves into the refrigerant. Since the lubricating oil has a small specific gravity and cannot be evaporated, this part of oil will eventually stay at the liquid level position of the evaporator. In the unit of the prior art, a double-ejector mode is generally used to recover this part of lubricating oil. One ejector sends the mixed liquid in the evaporator to the suction port of the compressor for oil separation through the pressure difference between the condenser and the evaporator, and the other ejector ejects the lubricating oil separated from the suction port to the oil tank. This double-ejector oil return system is mainly driven by the pressure difference between the condenser and the evaporator of the unit. When the pressure difference between the condenser and the evaporator is too small, the effect of the unit oil return system is weakened, and even failure occurs, resulting in oil shortage of the unit and failure to start, or oil running to cause suction liquid carrying and other phenomena that easily lead to damage of the compressor. Moreover, the use of two sets of ejectors increases the complexity and cost of the pipeline.

[0004] When the unit has oil running or the liquid level of the evaporator is too high, the unit starting process is prone to suction liquid carrying, the load of the compressor motor starting process is too large, and the unit cannot be normally started and operated. SUMMARY

[0005] To solve the problems in the prior art, the present application provides a centrifugal unit, a reliable operation system thereof and a control method.

[0006] The present application adopts the following technical solutions:

[0007] The first aspect of the present application provides a centrifugal unit reliable operation system, comprising: an evaporator, a condenser, an oil tank, an ejector and a control device; the refrigerant in the evaporator passes through a filter, a refrigerant pump and a first one-way valve in sequence, and then one of the refrigerant can enter the condenser through a first electromagnetic valve and a second one-way valve, and the other of the refrigerant can enter a compressor suction port through a second electromagnetic valve, so as to separate the refrigerant dissolved in the lubricating oil through the compressor suction port; a liquid level sensor is arranged on the evaporator and used to collect the liquid level height of the evaporator; the control device is used to control the start and stop of the first electromagnetic valve and the refrigerant pump by judging the size of the liquid level height of the evaporator and a preset target liquid level height, so as to ensure the normal start of the centrifugal unit; the high-pressure end of the ejector is connected with the high-pressure refrigerant outlet of the condenser and used to introduce high-pressure refrigerant, the low-pressure end is connected with the compressor suction port and used to introduce the lubricating oil separated from the compressor suction port, and the outlet end is connected with the oil tank and used to introduce the refrigerant introduced from the high-pressure end and the lubricating oil introduced from the low-pressure end into the oil tank.

[0008] According to the centrifugal unit reliable operation system, the oil tank is provided with an electric heater, which is used to heat and evaporate the refrigerant, and the gaseous refrigerant after evaporation enters the compressor suction port.

[0009] According to the centrifugal unit reliable operation system, the reliable operation system further comprises a differential pressure gauge, one end of the differential pressure gauge is connected with the oil pump inlet, the other end is connected with the oil pump outlet, so as to measure the oil supply pressure difference, and the control device controls the start and stop of the refrigerant pump by judging the size of the oil supply pressure difference and a preset pressure difference.

[0010] The second aspect of the present application provides a control method of a centrifugal unit reliable operation system, comprising the following steps:

[0011] When the centrifugal unit starts, the liquid level height of the evaporator is acquired;

[0012] If the liquid level height of the evaporator is higher than the preset target liquid level height, the refrigerant pump and the first electromagnetic valve are started, the refrigerant in the evaporator is pumped into the condenser, and then the centrifugal unit is started when the liquid level height of the evaporator is lower than the preset target liquid level height; otherwise, the centrifugal unit is normally started.

[0013] After the centrifugal unit starts, the oil supply pressure difference between the oil pump inlet and the oil pump outlet of the oil tank is acquired in real time;

[0014] When the oil supply pressure difference is lower than a preset pressure difference value, the refrigerant pump and the second electromagnetic valve are started, the mixed liquid in the evaporator is pumped into the compressor suction port for oil separation, and the lubricating oil after separation is introduced into the oil tank by the ejector; otherwise, the centrifugal unit is normally operated.

[0015] According to the control method, the control method further comprises:

[0016] The temperature of the lubricating oil in the oil tank is acquired, when the temperature of the lubricating oil is lower than a preset temperature T1, the electric heater is started to evaporate the refrigerant in the oil tank, when the temperature of the lubricating oil is higher than a preset temperature T2, the electric heater is closed to avoid lubrication failure of the lubricating oil; wherein T1

[0017] The third aspect of the present application provides a centrifugal unit, comprising: the reliable operation system.

[0018] The fourth aspect of the present application provides a storage medium, the storage medium comprises a stored program, wherein, when the program is running, the device where the storage medium is located executes the control method.

[0019] Compared with the prior art, the beneficial effects of the present application at least include:

[0020] 1、The present application sets up a liquid level sensor on the evaporator, which is used to collect the liquid level height of the evaporator, when the centrifugal unit starts, if the liquid level height of the evaporator is higher than the target liquid level height, the excessive refrigerant in the evaporator can be pumped into the condenser, avoiding the suction liquid of the centrifugal unit, reducing the load of the compressor motor starting process, and ensuring the normal start of the centrifugal unit.

[0021] 2、The present application detects that the oil supply pressure difference is lower than the threshold value when the centrifugal unit runs, the mixed liquid in the evaporator is pumped into the compressor suction port through the refrigerant pump, and the lubricating oil separated from the compressor suction port is injected back to the oil tank through the ejector, avoiding the problem of oil return failure, and greatly improving the reliability of the centrifugal unit operation.

[0022] 3、The present application acquires the temperature of the lubricating oil in the oil tank through the thermometer, and judges the size of the temperature of the lubricating oil and the preset temperature, so as to ensure that when the temperature of the lubricating oil is low, the refrigerant entering the oil tank is evaporated by heating, and when the temperature of the lubricating oil is high, the electric heater is closed to avoid the lubrication failure caused by the too high temperature of the lubricating oil. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0024] Figure 1 The system working principle diagram of the lubricating oil-free unit of the present application;

[0025] Figure 2 The system working principle diagram of the lubricating oil unit of the present application;

[0026] Figure 3 The flow chart of the normal start control method of the centrifugal machine set of the present application is shown in Figure 1.

[0027] Figure 4 The flow chart of the normal operation control method of the centrifugal machine set of the present application is shown in Figure 1.

[0028] In the figure, 1, compressor; 2, condenser; 3, throttle valve; 4, evaporator; 5, filter; 6, refrigerant pump; 7, first check valve; 8, first electromagnetic valve; 9, second check valve; 10, liquid level sensor; 11, oil tank; 12, ejector; 13, second electromagnetic valve; 14, electric heater; 15, oil pump. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. The following description of at least one exemplary embodiment is merely illustrative in nature and not intended to limit the present application and its applications or uses in any way. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort fall within the scope of the present application.

[0030] Unless otherwise specified, the relative arrangement of the components and steps, numerical expressions, and values set forth in these embodiments do not limit the scope of the present application.

[0031] Meanwhile, it should be understood that the sizes of the various parts shown in the drawings are not drawn in proportion for the convenience of description.

[0032] The techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered as part of the authorized description where appropriate.

[0033] In all examples shown and discussed herein, any specific values should be interpreted as merely illustrative and not as a limitation. Thus, other examples of the example embodiments can have different values.

[0034] It should be noted that similar reference numerals and letters refer to similar items throughout the accompanying drawings, and thus, once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0035] The machine set can be divided into an oil machine set using oil lubricated bearings and an oil-free machine set using magnetic suspension bearings and gas suspension bearings. When the liquid level of the evaporator is too high, it is easy to cause the machine set to fail to operate normally, and the oil return of the machine set using oil lubricated bearings may fail.

[0036] When the centrifugal unit is running, the compressor 1 is connected with the condenser 2, the throttle valve 3 and the evaporator 4 in sequence to form a loop.

[0037] As shown in Figure 1 Embodiment 1 of the present application provides a centrifugal unit reliable running system, which comprises an evaporator 4, a condenser 2 and a control device.

[0038] The refrigerant in the evaporator 4 passes through a filter 5, a refrigerant pump 6, a first one-way valve 7, a first electromagnetic valve 8 and a second one-way valve 9 in sequence and enters the condenser 2.

[0039] The evaporator 5 is provided with a liquid level sensor 10 to obtain the liquid level height of the evaporator.

[0040] The control device controls the start and stop of the first electromagnetic valve 8 and the refrigerant pump 6 by judging the size of the liquid level height of the evaporator and the preset target liquid level height, so as to ensure the normal start of the centrifugal unit.

[0041] When the centrifugal unit starts, if the liquid level height of the evaporator is higher than the target liquid level height, the control device controls the start of the first electromagnetic valve 8 and the refrigerant pump 6 to move the excessive refrigerant in the evaporator 4 to the condenser 2, reduce the refrigerant amount in the evaporator 4, avoid the suction liquid of the centrifugal unit, reduce the load of the compressor motor during the start process, and ensure the normal start of the centrifugal unit.

[0042] As shown in Figure 2 Embodiment 2 of the present application provides a centrifugal unit reliable running system, which further comprises an oil tank 11 and an ejector 12.

[0043] The mixed liquid of the refrigerant and the lubricating oil in the evaporator 4 passes through the filter 5, the refrigerant pump 6, the first one-way valve 7 and a second electromagnetic valve 13 in sequence and enters the suction port of the compressor to separate the mixed liquid through the suction port of the compressor.

[0044] The refrigerant pump 6 ejects the mixed liquid of the refrigerant and the oil in the evaporator 4 to the suction port of the compressor. Since the suction port of the compressor has low pressure, the refrigerant is separated from the lubricating oil, evaporates into a gaseous state and enters the compressor for compression, and the separated lubricating oil falls to the bottom of the suction port of the compressor.

[0045] The high-pressure end of the ejector 12 is connected with the high-pressure refrigerant outlet of the condenser 2 to introduce high-pressure refrigerant, the low-pressure end is connected with the suction port of the compressor to introduce the separated lubricating oil, and the outlet end is connected with the oil tank 11 to eject the refrigerant introduced by the high-pressure end and the separated lubricating oil introduced by the low-pressure end into the oil tank 11.

[0046] The ejector works by the pressure difference between the high-pressure refrigerant introduced at the high-pressure end and the low-pressure lubricating oil introduced at the low-pressure end being large enough to be normal; the ejector needs a stable low-pressure fluid source to be injected, and when there is no low-pressure fluid at the low-pressure end, the ejector cannot form a mixed-pressurization process and is in a state similar to idling, without actual liquid injection to the outlet end.

[0047] In the embodiment, if the refrigerant pump does not pump the mixed liquid in the evaporator into the compressor suction port to form separated lubricating oil, the ejector cannot inject the high-pressure refrigerant in the condenser into the oil tank.

[0048] The oil tank 11 is provided with an electric heater 14 for heating and evaporating the refrigerant to separate the refrigerant and the lubricating oil, and the evaporated gaseous refrigerant enters the compressor suction port from the pipeline at the top of the oil tank 11;

[0049] The oil tank further includes an oil pump 15, a high-position oil tank and a thermometer, the lubricating oil in the oil tank 11 is pressurized by the oil pump 15 according to the pressure difference corresponding to the set flow rate, then enters the high-position oil tank, and the lubricating oil with high cleanliness obtained after being filtered by the oil filter built in the high-position oil tank enters the compressor bearing inlet, forms a dynamic pressure oil film to support the rotor rotation in the bearing, and timely takes away the heat of the bearing, and then reenters the oil tank through the bearing outlet, to complete a cycle.

[0050] The thermometer is used to detect the temperature of the lubricating oil in the oil tank, and the control device controls the switch of the electric heater by judging the size of the temperature of the lubricating oil and the preset temperature.

[0051] The reliable operation system further includes a differential pressure gauge, one end of the differential pressure gauge is connected with the oil pump inlet, and the other end is connected with the oil pump outlet, to obtain the oil supply pressure difference, and the control device controls the start and stop of the refrigerant pump by judging the size of the oil supply pressure difference and the preset pressure difference.

[0052] When the centrifugal unit is running, if the oil supply pressure difference is detected to be lower than the threshold value, the mixed liquid in the evaporator 4 is pumped into the compressor suction port by the refrigerant pump 6, and the separated lubricating oil at the compressor suction port is injected back to the oil tank 11 by the ejector 12, thereby avoiding the problem of oil return failure, and greatly improving the reliability of the centrifugal unit operation.

[0053] As shown in Figure 3 The embodiment 3 of the present application provides a control method of a centrifugal unit reliable operation system, which includes the following steps:

[0054] Step 301, when the centrifugal unit starts, the liquid level height of the evaporator is obtained;

[0055] If the liquid level height is higher than the preset target liquid level height, the refrigerant pump and the first electromagnetic valve are started to pump the refrigerant in the evaporator to the condenser until the liquid level height in the evaporator is lower than the preset target liquid level height, then the first electromagnetic valve and the hydraulic pump are closed, and the centrifugal unit is started again, otherwise, the centrifugal unit is started normally.

[0056] As shown in Figure 4 Embodiment 4 of the present application provides a control method of a centrifugal unit reliable operation system, comprising the following steps:

[0057] After the centrifugal unit is started, the oil supply pressure difference between the oil pump inlet and the oil pump outlet is acquired in real time.

[0058] When the oil supply pressure difference is lower than the preset pressure difference value, the refrigerant pump and the second electromagnetic valve are started to pump the mixed liquid in the evaporator to the compressor suction port for oil separation, and the separated lubricating oil is injected into the oil tank by the ejector, otherwise, the centrifugal unit is operated normally.

[0059] The control method further comprises: acquiring the temperature of the lubricating oil in the oil tank, starting the electric heater to evaporate the refrigerant in the oil tank when the temperature of the lubricating oil is lower than the preset temperature T1, and closing the electric heater to avoid lubrication failure of the lubricating oil when the temperature of the lubricating oil is higher than the preset temperature T2; wherein T1 < T2. The efficient separation of the refrigerant and the lubricating oil can be realized, the pure state of the lubricating oil can be ensured, and the reliability of the compressor lubrication system can be ensured.

[0060] The temperature of the lubricating oil in the oil tank is acquired by a thermometer, and the temperature of the lubricating oil is compared with the preset temperature to ensure that the refrigerant in the oil tank is evaporated by heating when the temperature of the lubricating oil is low, and the electric heater is closed when the temperature of the lubricating oil is high to avoid lubrication failure caused by the excessively high temperature of the lubricating oil.

[0061] Embodiment 5 of the present application provides a centrifugal unit comprising the reliable operation system.

[0062] Embodiment 6 of the present application provides a storage medium storing a computer program, and the program is executed by a processor to realize the control method of the centrifugal unit reliable operation system disclosed by the present application.

[0063] Storage media can be any available media that can be accessed by a computing device. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other storage medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computing device. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, or twisted pair, then the coaxial cable, fiber optic cable, or twisted pair are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), and Blu-Ray® disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0064] In other embodiments, the computing device 100 includes one or more input devices 102, one or more output devices 104, one or more communication interfaces 106, and one or more storage devices 108. The input device 102 can include, for example, a keyboard, a mouse, a trackpad, a trackball, a touchscreen, a microphone, a camera, a scanner, a network interface, a wireless interface, or any other input device. The output device 104 can include, for example, a display, a monitor, a speaker, a printer, a network interface, a wireless interface, or any other output device. The communication interface 106 can include, for example, a network interface, a wireless interface, or any other communication interface. The storage device 108 can include, for example, a hard drive, a solid state drive, a flash drive, a memory card, a floppy disk, a zip disk, a CD-ROM, a DVD, a Blu-Ray® disc, a magnetic tape, or any other storage device.

[0065] Computer readable program instructions for carrying out operations of the present disclosure can be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like, and conventional procedural programming languages such as the "C" programming language or similar programming languages. The computer readable program instructions can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) can execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present disclosure.

[0066] Finally, it should be noted that the above-mentioned embodiments are merely used to illustrate the technical solutions of the present application, but not to limit it. Although the present application has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced, and any modification or replacement without departing from the spirit and scope of the present application should be covered in the protection scope of the claims of the present application.

Claims

1. A centrifugal unit reliable operation system, comprising: Evaporator, condenser, oil tank, ejector and control device; characterized by: The refrigerant in the evaporator passes through the filter, refrigerant pump, and first one-way valve in sequence. One path can pass through the first solenoid valve and the second one-way valve to enter the condenser, and the other path can pass through the second solenoid valve to enter the compressor suction port, so as to separate the lubricating oil dissolved in the refrigerant through the compressor suction port. A liquid level sensor is provided on the evaporator to collect the liquid level height of the evaporator; The control device is used to control the start and stop of the first solenoid valve and the refrigerant pump by judging the difference between the liquid level of the evaporator and the preset target liquid level to ensure normal startup of the centrifugal unit; The high-pressure end of the ejector is connected to the high-pressure refrigerant outlet of the condenser for introducing high-pressure refrigerant, the low-pressure end is connected to the compressor suction port for introducing lubricating oil separated from the compressor suction port, and the outlet end is connected to the oil tank for injecting the refrigerant introduced from the high-pressure end and the lubricating oil introduced from the low-pressure end into the oil tank.

2. The reliable operation system of a centrifuge unit according to claim 1, characterized in that: An electric heater is provided in the oil tank for heating the refrigerant in the evaporating oil tank, and the evaporated vapor refrigerant enters the compressor suction port; The oil tank also includes an oil pump, a high-level oil tank and a thermometer. The oil pump is used to pump lubricating oil into the high-level oil tank, and then enter the compressor bearing inlet after passing through the oil filter built into the high-level oil tank, and then return to the oil tank through the bearing outlet to complete a cycle; The thermometer is used to detect the temperature of the lubricating oil in the oil tank, and the control device controls the switch of the electric heater by judging the difference between the temperature of the lubricating oil and the preset temperature.

3. The centrifuge unit reliable operation system according to claim 2, characterized in that: The reliable operation system also includes a differential pressure gauge, one end of which is connected to the oil pump inlet and the other end is connected to the oil pump outlet to measure the oil supply pressure difference. The control device controls the start and stop of the refrigerant pump and the second solenoid valve by judging the size of the oil supply pressure difference and the preset pressure difference.

4. A method for controlling a reliable operation system of a centrifuge unit according to any one of claims 1 to 3, characterized in that: The following steps are involved: When the centrifugal unit is started, obtain the liquid level height of the evaporator; If the liquid level of the evaporator is higher than the preset target liquid level, the refrigerant pump and the first solenoid valve are started to pump the refrigerant in the evaporator into the condenser until the liquid level of the evaporator is lower than the preset target liquid level, and then the centrifugal unit is started; Otherwise, the centrifugal unit will be started normally; After the centrifugal unit is started, the oil supply pressure difference between the oil pump inlet and the oil pump outlet of the oil tank is obtained in real time; When the oil supply pressure difference is lower than the preset pressure difference value, the refrigerant pump and the second solenoid valve are started to pump the mixed liquid in the evaporator into the compressor suction port for oil-liquid separation, and the ejector injects the separated lubricating oil into the oil tank; otherwise, the centrifugal unit operates normally.

5. The control method according to claim 4, characterized in that: The control method further includes: The temperature of the lubricating oil in the oil tank is obtained. When the temperature of the lubricating oil is lower than a preset temperature T1, the electric heater is started to heat the refrigerant in the evaporative oil tank. When the temperature of the lubricating oil is higher than a preset temperature T2, the electric heater is turned off to avoid lubrication failure of the lubricating oil; wherein T1 < T2.

6. A centrifugal unit, characterized in that: include: The reliable operation system according to any one of claims 1 to 3.

7. A storage medium, characterized in that: The storage medium includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the control method according to any one of claims 4 to 5.

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