ORC power generation system for recovering waste heat of lubricating oil of air compressor

Abstract

The invention discloses an air compressor lubricating oil waste heat recovery ORC power generation system which comprises a worm type compressor, an evaporator, a vortex expansion machine, a working medium pump, a condenser, a capacitor and a controller. A hot oil outlet of the evaporator is communicated with a lubricating oil inlet of the worm type compressor, a working medium outlet of the vortex expansion machine is connected with a working medium inlet of the condenser, a service interface of the vortex expansion machine is connected with a load electric box, the load electric box provides overcurrent protection and maintains stable operation, and the capacitor is connected with the load electric box. And electricity is generated through the vortex expansion machine and the capacitor. The capacitor in the power generation system replaces the position of a generator in an existing unit, and the power generation system has the advantages of being small in occupied space and excellent in economical efficiency; and the temperature of the lubricating oil flowing out of the worm type compressor is stable, and the heat absorption of the evaporator is stable, so that the waste heat recovery efficiency of the lubricating oil of the air compressor is improved.

Description

Technical Field

[0001] The invention relates to the technical field of waste heat recovery of compressor lubricating oil, and in particular to an air compressor lubricating oil waste heat recovery ORC power generation system. Background Art

[0002] The working process of a screw air compressor mainly includes: the air filter inside the air machine filters impurities, and then enters the compressor body, mixes with the injected cooling lubricating oil during the compression process, and the compressed mixed gas enters the oil-gas separation tank through the compression chamber; at this time, high-temperature and high-pressure oil and gas are obtained, and the high-temperature and high-pressure oil and gas need to enter their respective cooling systems for cooling, the cooled compressed air is transmitted to the use system, and the cooled lubricating oil returns to the oil circuit to enter the next working cycle.

[0003] The waste heat recovery of air compressors uses the high temperature and high pressure oil and gas to heat cold water, reuses the excess heat of the air compressor, saves energy consumption and saves costs. The waste heat recovery device of the air compressor mainly includes a transmission pipe installed outside the transmission lubricating oil and gas pipeline and a water tank for storing hot water. Tap water is directly transmitted to the transmission pipe for heating, which effectively reduces energy waste.

[0004] However, the temperature of the lubricating oil flowing out of the traditional worm compressor is unstable, which leads to unstable heat absorption at the evaporator, resulting in low efficiency of waste heat recovery of the air compressor lubricating oil. Summary of the invention

[0005] In view of the above-mentioned prior art, the present invention provides an air compressor lubricating oil waste heat recovery ORC power generation system. The capacitor in the power generation system of the present invention replaces the position of the generator in the existing unit, and has the characteristics of small footprint and excellent economy. The temperature of the lubricating oil flowing out of the worm compressor is stable, and the heat absorption at the evaporator is stable, thereby improving the efficiency of air compressor lubricating oil waste heat recovery.

[0006] In order to solve the above technical problems, the present invention proposes an air compressor lubricating oil waste heat recovery ORC power generation system, comprising a worm compressor, an evaporator, a scroll expander, a working fluid pump, a condenser and a controller; the bottom of the worm compressor is provided with a lubricating oil inlet, and the top of the worm compressor is provided with an oil-gas separation port; the evaporator comprises an upper coil and a lower coil, and the evaporator is provided with a hot oil inlet, a hot oil outlet, a working fluid inlet, a working fluid outlet, an upper coil outlet and a lower coil inlet; the scroll expander is provided with a working fluid inlet and a working fluid outlet; the condenser is provided with a working fluid inlet, a working fluid outlet, a cold water inlet and a cold water outlet; the connection relationship of the above related components is as follows:

[0007] The oil-gas separation port of the worm compressor is connected to the hot oil inlet of the evaporator through a pipeline A, and a temperature sensor is provided on the pipeline A; the hot oil outlet of the evaporator is connected to the inlet of a hot oil pump through a pipeline B, and the outlet of the hot oil pump is connected to the lubricating oil inlet of the worm compressor, and the hot oil pump is provided with a frequency converter; the temperature sensor and the frequency converter are both connected to the controller;

[0008] The upper coil outlet of the evaporator is connected to the lower coil inlet through a pipeline C, the working fluid outlet of the evaporator is connected to the working fluid inlet of the scroll expander through a pipeline D, and the working fluid outlet of the scroll expander is connected to the working fluid inlet of the condenser through a pipeline E, and an electromagnetic flow meter is provided on the pipeline E;

[0009] The working fluid outlet of the condenser is connected to the working fluid inlet of the evaporator through a pipeline F, and a working fluid pump is provided on the pipeline F. The service interface of the scroll expander is electrically connected to a load electrical box, and a capacitor is connected to the load electrical box. Electricity is generated by the scroll expander and the capacitor, and the load electrical box provides overcurrent protection.

[0010] Furthermore, the air compressor lubricating oil waste heat recovery ORC power generation system of the present invention, wherein:

[0011] The controller is a programmable logic controller. The controller controls the operating speed of the hot oil pump through the frequency converter according to the temperature detected by the temperature sensor. The operating speed is divided into high speed, medium speed and low speed, which are: low speed operation when the oil temperature is less than 60°C, medium speed operation when the oil temperature is greater than 60°C and less than 80°C, and high speed operation when the oil temperature exceeds 80°C. The controller converts the temperature detected by the temperature sensor into a control signal and controls the operating speed of the hot oil pump through the frequency converter.

[0012] The hot oil pump, worm compressor, evaporator, frequency converter and controller cooperate to realize the circulation of lubricating oil.

[0013] The cold water inlet and the cold water outlet of the condenser are respectively connected to water pipes. After the cold water exchanges heat with the working medium in the condenser, the heat in the condenser is taken out.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] In the air compressor lubricating oil waste heat recovery ORC power generation system proposed by the present invention, the load electric box is connected to a capacitor. During the charging and discharging process of the capacitor, current will flow in the capacitor wire. When the current flows through the wire, a magnetic field will be generated. The capacitor is connected with wires. These changing magnetic fields will interact with the wires, and the movement of the rotor 302 and the stator 301 in the scroll expander 3 cuts the magnetic flux lines, thereby generating electricity.Figure 2 shown.

[0016] In the air compressor lubricating oil waste heat recovery ORC power generation system proposed by the present invention, the temperature of the lubricating oil flowing out of the worm compressor 1 can be detected by the temperature sensor 10. When the oil temperature is too low, the controller 91 will control the inverter 9 to reduce the speed of the hot oil pump 8 and reduce the flow rate of the lubricating oil, so that the hot oil can fully release heat inside the evaporator 2, and the lubricating oil can also fully absorb heat inside the worm compressor 1, thereby improving the efficiency of lubricating oil waste heat recovery. Figure 1 shown. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the air compressor lubricating oil waste heat recovery ORC power generation system of the present invention;

[0018] Figure 2 is a schematic diagram of power generation of the power generation system of the present invention;

[0019] Figure 3 It is a structural schematic diagram of conducting a power generation capacity experiment on the power generation system of the present invention;

[0020] Figure 4 is a graph showing the relationship between the electrical output power and the lubricating oil flow rate of the power generation system of the present invention;

[0021] Figure 5 is a graph showing the relationship between the electrical output power and the cooling water inlet temperature of the power generation system of the present invention;

[0022] Figure 6 It is a relationship diagram between the electrical output power and the capacitor capacity of the power generation system of the present invention.

[0023] In the figure:

[0024] 1- Worm compressor 11- Lubricating oil inlet of worm compressor

[0025] 12-Oil and gas separation port of worm compressor 2-Evaporator

[0026] 21-Hot oil inlet of evaporator 22-Hot oil outlet of evaporator

[0027] 23- Working fluid inlet of evaporator 24- Working fluid outlet of evaporator

[0028] 25 Evaporator upper coil outlet 26 Evaporator lower coil inlet

[0029] 3-Scroll expander 31- Working fluid inlet of scroll expander

[0030] 32-Working medium outlet of scroll expander 33-Service interface

[0031] 301-stator of scroll expander 302-rotor of scroll expander

[0032] 4- Working fluid pump 5- Condenser

[0033] 51-Condenser working fluid inlet 52-Condenser working fluid outlet

[0034] 53- cold water inlet of condenser 54- cold water outlet of condenser

[0035] 6- Load electric box 7- Capacitor

[0036] 8-Hot oil pump 9-Inverter

[0037] 10- Temperature sensor 91- Controller

[0038] 35-Electromagnetic flow meter DETAILED DESCRIPTION

[0039] The design concept of the air compressor lubricating oil waste heat recovery ORC power generation system proposed in the present invention is as follows: Figure 1 As shown, the system includes a worm compressor 1, an evaporator 2, a scroll expander 3, a working fluid pump 4, a condenser 5 and a controller 91. The oil-gas separation gas port 12 (i.e., the lubricating oil outlet) of the worm compressor is connected to the hot oil inlet 21 of the evaporator, the hot oil outlet 22 of the evaporator is connected to the lubricating oil inlet 11 of the worm compressor, the working fluid outlet 32 ​​of the scroll expander is connected to the working fluid inlet 51 of the condenser, and the service interface of the scroll expander is connected to the load electric box 6, which provides overcurrent protection to maintain stable operation. The capacitor 7 is connected to it and generates electricity through the scroll expander 3 and the capacitor 7. Generally, the rotor 302 of the scroll expander is usually made of a conductor and is installed on a rotating shaft. When the rotor 302 of the scroll expander rotates, the conductor moves in a fixed magnetic field and cuts the magnetic induction intensity passing through the magnetic field; the stator 301 of the scroll expander is responsible for receiving the current generated by the rotor cutting the magnetic induction intensity. When the current passes through the stator, the magnetic field generates a stable rotating magnetic field to assist the rotor. The motion of cutting the magnetic induction intensity will generate electromotive force in the conductor, which will make the free electrons in the conductor move in the conductor, thus emitting current, such as Figure 2 shown.

[0040] In the present invention, it is considered that a capacitor 7 is connected to the load electrical box 6, and electric wires are connected around the capacitor 7. These changing magnetic fields will interact with the electric wires, resulting in a reduction in the magnetic induction intensity. In the present invention, a temperature sensor 10 is also arranged on the pipeline of the oil-gas separation air port 12 of the worm compressor to detect the temperature of the lubricating oil flowing out of the worm compressor 1. When the oil temperature is too low, the controller will control the frequency converter 9 connected to the hot oil pump 8 to reduce the speed of the hot oil pump 8, so that the lubricating oil can fully absorb heat inside the worm compressor 1, thereby improving the efficiency of waste heat recovery of the lubricating oil.

[0041] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the following embodiments are by no means intended to limit the present invention in any way.

[0042] The present invention proposes an air compressor lubricating oil waste heat recovery ORC power generation system, such as Figure 1 As shown, it includes a worm compressor 1, an evaporator 2, a scroll expander 3, a working fluid pump 4, a condenser 5 and a controller 91; the bottom of the worm compressor 1 is provided with a lubricating oil inlet 11, and the top of the worm compressor 1 is provided with an oil-gas separation gas port 12; the evaporator 2 includes an upper coil and a lower coil, and the evaporator 2 is provided with a hot oil inlet 21, a hot oil outlet 22, a working fluid inlet 23, a working fluid outlet 24, an upper coil outlet 25 and a lower coil inlet 26; the scroll expander 3 is provided with a working fluid inlet 31 and a working fluid outlet 32; the condenser 5 is provided with a working fluid inlet 51, a working fluid outlet 52, a cold water inlet 53 and a cold water outlet 54; the connection relationship of the above-mentioned related components is as follows:

[0043] The oil-gas separation air port 12 of the worm compressor 1 is connected to the hot oil inlet 21 of the evaporator 2 through a pipeline A, and a temperature sensor 10 is provided on the pipeline A; the hot oil outlet 22 of the evaporator 2 is connected to the inlet of a hot oil pump 8 through a pipeline B, and the outlet of the hot oil pump 8 is connected to the lubricating oil inlet 11 of the worm compressor 1, and the hot oil pump 8 is provided with a frequency converter 9; the temperature sensor 10 and the frequency converter 9 are both connected to the controller 91.

[0044] The upper coil outlet 25 of the evaporator 2 is connected to the lower coil inlet 26 through a pipeline C, the working fluid outlet 24 of the evaporator 2 is connected to the working fluid inlet 31 of the scroll expander 3 through a pipeline D, and the working fluid outlet 32 ​​of the scroll expander 3 is connected to the working fluid inlet 51 of the condenser 5 through a pipeline E, and an electromagnetic flow meter 35 is provided on the pipeline E.

[0045] The working fluid outlet 52 of the condenser 5 is connected to the working fluid inlet 23 of the evaporator 2 through a pipeline F, and a working fluid pump 4 is provided on the pipeline F. The service interface of the vortex expander 3 is electrically connected to the load electric box 6, and the load electric box 6 is connected to a capacitor 7. The vortex expander 3 and the capacitor 7 generate electricity, and the load electric box 6 provides overcurrent protection. The cold water inlet 53 and the cold water outlet 54 of the condenser 5 are respectively connected to water pipes, and the cold water takes out the heat in the condenser 5 after heat exchange with the working fluid in the condenser 5.

[0046] The controller 91 in the present invention is a programmable logic controller. The controller 91 controls the operating speed of the hot oil pump 8 through the frequency converter 9 according to the temperature detected by the temperature sensor 10. The operating speed is divided into three modes: high speed, medium speed and low speed, which are: low speed operation when the oil temperature is less than 60°C, medium speed operation when the oil temperature is greater than 60°C and less than 80°C, and high speed operation when the oil temperature exceeds 80°C. The controller 91 transmits the signal to the frequency converter 9 after a certain delay after detecting the temperature. According to the temperature of the lubricating oil flowing out of the worm compressor 1 detected by the temperature sensor 10, it is converted into a control signal and sent to the inside of the controller 91. The controller 91 sends a signal according to the oil temperature to adjust the operating speed of the hot oil pump 8 through the frequency converter 9. In the present invention, the oil temperature is transmitted to the frequency converter 9 after a certain period of time to avoid a sudden error in detecting the temperature, which causes the hot oil pump 8 to rotate at an unmatched speed. The power generation system of the present invention realizes lubricating oil circulation through the cooperative action of the hot oil pump 8, the worm compressor 1, the evaporator 2, the frequency converter 9 and the controller 91. Specifically, the hot oil pump 8 is turned on, so that the lubricating oil heated inside the worm compressor 1 flows into the evaporator 2 from the hot oil inlet 21 of the evaporator, the evaporator 2 cools the hot lubricating oil, and the cooled lubricating oil flows back into the worm compressor 1 through the hot oil outlet 22 of the evaporator to circulate the lubricating oil, the condenser 5 flows the condensed process fluid to the evaporator 2 through the working fluid pump 4, the evaporator 2 is heat-protected, the working fluid enters the evaporator 2 to absorb and generate steam with appropriate pressure and temperature, the working steam then enters the scroll expander 3, and then enters the condenser 5 through the pipeline to form a cycle.

[0047] like Figure 3 As shown, in order to verify the power generation capacity of the air compressor lubricating oil waste heat recovery ORC power generation system of the present invention, Figure 1Under the premise of the power generation system structure shown, thermometers are installed on the pipe section of the hot oil inlet 21 of the evaporator, the pipe section of the working fluid outlet 24 of the evaporator, the pipe section of the outlet of the working fluid pump 4, and the pipe section of the working fluid outlet 32 ​​of the vortex expander, and valve bodies are respectively provided on the connecting pipe section C between the upper coil outlet 25 of the evaporator and the lower coil inlet 26 of the evaporator and the pipe section between the outlet of the working fluid pump and the working fluid inlet 23 of the evaporator. During the experiment, the temperature of the lubricating oil at the inlet of the evaporator was set to 75, 80, 85, 90, 95, 100, and 105°C, respectively, and the temperature at the cold water inlet of the condenser was set to 19, 27, and 30°C, respectively. Since the temperature fluctuation is controlled within ±0.1°C, the entire experimental system is in a stable state. The Agilent-34970A data acquisition system is used to continuously record the temperatures of all the above thermometers at a rate of 4 values ​​per minute, and measure the flow rate of the electromagnetic flow meter 35. The output power can be directly read by the power tester that comes with the load box. In addition, the capacitance value of the capacitor used in the test is 150μF / piece. Figure 4 The graph shows how the output power changes with the lubricating oil flow rate at different lubricating oil temperatures. As the lubricating oil flow rate increases, the output power also increases, and the maximum output power can reach 1.16kW. Figure 5 The graph shows the variation of electrical output power with cooling water inlet temperature. It can be seen that increasing the cooling water inlet temperature of the condenser will lead to a decrease in output power. When the condensing water inlet temperature is 19°C and the lubricating oil temperature is 105°C, the maximum electrical output power can reach 1.81kW. Figure 6 It shows that the electric power output changes with the capacitance of the capacitor at different lubricating oil temperatures. It can be seen that the larger the capacitance, the higher the output power. When the capacitance of the capacitor is in the range of 150μF to 900μF, the output electric power increases from 0.389kW to 1.361kW when the lubricating oil temperature is 75℃. When the lubricating oil temperature is 105℃ and the capacitor is connected to 900μF, the maximum electric output power is 1.72kW. It can be seen that the behavior of replacing the generator with the capacitor has been verified to generate electricity, and the system has a certain power generation capacity.

[0048] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can make many improvements and changes without departing from the purpose of the present invention, which are all within the protection of the present invention.

Claims

1. An air compressor lubricating oil waste heat recovery ORC power generation system, comprising a worm compressor (1), an evaporator (2), a scroll expander (3), a working fluid pump (4), a condenser (5) and a controller (91); the bottom of the worm compressor (1) is provided with a lubricating oil inlet (11), and the top of the worm compressor (1) is provided with an oil-gas separation port (12); the evaporator (2) comprises an upper coil and a lower coil, the evaporator (2) is provided with a hot oil inlet (21), a hot oil outlet (22), a working fluid inlet (23), a working fluid outlet (24), an upper coil outlet (25) and a lower coil inlet (26); the scroll expander (3) is provided with a working fluid inlet (31) and a working fluid outlet (32); the condenser (5) is provided with a working fluid inlet (51), a working fluid outlet (52), a cold water inlet (53) and a cold water outlet (54); characterized in that, The oil-gas separation port (12) of the worm compressor (1) is connected to the hot oil inlet (21) of the evaporator (2) through a pipeline A, and a temperature sensor (10) is provided on the pipeline A; the hot oil outlet (22) of the evaporator (2) is connected to the inlet of a hot oil pump (8) through a pipeline B, and the outlet of the hot oil pump (8) is connected to the lubricating oil inlet (11) of the worm compressor (1), and the hot oil pump (8) is provided with a frequency converter (9); the temperature sensor (10) and the frequency converter (9) are both connected to the controller (91); The upper coil outlet (25) of the evaporator (2) is connected to the lower coil inlet (26) via a pipeline C, the working fluid outlet (24) of the evaporator (2) is connected to the working fluid inlet (31) of the scroll expander (3) via a pipeline D, the working fluid outlet (32) of the scroll expander (3) is connected to the working fluid inlet (51) of the condenser (5) via a pipeline E, and an electromagnetic flow meter (35) is provided on the pipeline E; The working fluid outlet (52) of the condenser (5) is connected to the working fluid inlet (23) of the evaporator (2) via a pipeline F, a working fluid pump (4) is provided on the pipeline F, the service interface of the scroll expander (3) is electrically connected to a load electrical box (6), the load electrical box (6) is connected to a capacitor (7), electricity is generated by the scroll expander (3) and the capacitor (7), and the load electrical box (6) provides overcurrent protection.

2. The air compressor lubricating oil waste heat recovery ORC power generation system according to claim 1 is characterized in that: The controller (91) is a programmable logic controller. The controller (91) controls the operating speed of the hot oil pump (8) through the frequency converter (9) according to the temperature detected by the temperature sensor (10). The operating speed is divided into high speed, medium speed and low speed, which are respectively: low speed operation when the oil temperature is less than 60°C, medium speed operation when the oil temperature is greater than 60°C and less than 80°C, and high speed operation when the oil temperature exceeds 80°C. The controller (91) converts the temperature detected by the temperature sensor (10) into a control signal and controls the operating speed of the hot oil pump (8) through the frequency converter (9).

3. The air compressor lubricating oil waste heat recovery ORC power generation system according to claim 1 is characterized in that: The hot oil pump (8), the worm compressor (1), the evaporator (2), the frequency converter (9) and the controller (91) work together to realize the circulation of lubricating oil.

4. The air compressor lubricating oil waste heat recovery ORC power generation system according to claim 1 is characterized in that: The cold water inlet (53) and the cold water outlet (54) of the condenser (5) are respectively connected to water pipes, and after the cold water exchanges heat with the working medium in the condenser (5), the heat in the condenser (5) is taken out.

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