Combined system of air compressor and refrigerating machine and energy-saving control method thereof

Abstract

The application discloses a combined system of an air compressor and a cold dryer and an energy-saving control method thereof, relates to the technical field of compressed air systems of thermal power plants, and comprises an air compressor unit and a cold dryer unit, further comprises an instrument primary mother pipe, an ash removal primary mother pipe, an instrument secondary mother pipe and an ash removal secondary mother pipe; the air compressor unit comprises a plurality of air compressors, the outlets of the air compressors are connected with the instrument primary mother pipe and the ash removal primary mother pipe through air compressor outlet electric three-way valve groups respectively; the cold dryer unit comprises a plurality of cold dryers, the inlets of the cold dryers are connected with the instrument primary mother pipe and the ash removal primary mother pipe through cold dryer inlet electric three-way valve groups respectively; the outlets of the cold dryers are connected with the instrument secondary mother pipe and the ash removal secondary mother pipe through cold dryer outlet electric valve groups respectively; a gas supplement regulating valve and a pressure regulating bypass valve are arranged in parallel between the instrument secondary mother pipe and the ash removal secondary mother pipe.

Description

Technical Field

[0001] This invention relates to the field of compressed air system technology for thermal power plants, specifically a combined system of an air compressor and a refrigerated dryer and its energy-saving control method. Background Technology

[0002] The conventional combination of air compressors and refrigerated dryers is a one-to-one pairing, which has the following drawbacks:

[0003] 1. If any air compressor or refrigerated dryer malfunctions, it must be taken out of service, and the equipment will lose its backup.

[0004] 2. Increased gas consumption necessitates the addition of new equipment, but the combination options are limited and cannot be matched with any single option.

[0005] 3. When the instantaneous consumption of compressed air for ash removal increases, and the pressure of the compressed air for ash removal suddenly drops, the backup equipment is activated to maintain the pressure. This cannot achieve the best match between the supply and demand of compressed air in the compressed air system, and the energy consumption of the equipment increases. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a combined system of an air compressor and a refrigerated dryer, along with its energy-saving control method. This system solves the problem of the original one-to-one operation mode of the air compressor and refrigerated dryer, which lacks flexible matching, thus improving the operational stability of the equipment. It also meets the requirements for system expansion, allowing for the integration of new equipment at any time, improving the overall system's compatibility. The air compressor and refrigerated dryer can be freely grouped and operated, with pressure leveling functionality enabled to achieve energy-saving operation and reduce the overall system's energy consumption.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a combined system of an air compressor and a refrigerated dryer, comprising an air compressor unit and a refrigerated dryer unit, and further comprising a primary header for instrumentation, a primary header for ash removal, a secondary header for instrumentation, and a secondary header for ash removal; the air compressor unit comprises several air compressors, the outlet of each air compressor being connected to the primary header for instrumentation and the primary header for ash removal via an air compressor outlet electric three-way valve assembly; the refrigerated dryer unit comprises several refrigerated dryers, the inlet of each refrigerated dryer being connected to the primary header for instrumentation and the primary header for ash removal via a refrigerated dryer inlet electric three-way valve assembly; the outlet of each refrigerated dryer being connected to the secondary header for instrumentation and the secondary header for ash removal via a refrigerated dryer outlet electric valve assembly; a supplementary air regulating valve and a pressure leveling bypass valve are connected in parallel between the secondary header for instrumentation and the secondary header for ash removal.

[0008] Based on the above technical solution, a front switch valve is provided between the gas supply regulating valve and the instrument secondary main pipe, and a check valve is provided between the gas supply regulating valve and the ash removal secondary main pipe.

[0009] Based on the above technical solution, the instrument primary header is equipped with instrument primary header pressure; the ash removal primary header is equipped with ash removal primary header pressure; the instrument secondary header is equipped with instrument secondary header pressure; and the ash removal secondary header is equipped with ash removal secondary header pressure.

[0010] Based on the above technical solution, a controller is also included. The controller is electrically connected to the air compressor unit, the air compressor outlet electric three-way valve group, the refrigerated dryer unit, the refrigerated dryer inlet electric three-way valve group, the refrigerated dryer outlet electric valve group, the instrument primary main pipe pressure, the ash removal primary main pipe pressure, the instrument secondary main pipe pressure, the ash removal secondary main pipe pressure, the air replenishment regulating valve, the air replenishment regulating valve front switch, and the pressure leveling bypass valve.

[0011] Based on the above technical solution, the controller is also electrically connected to the touch screen and the operator station.

[0012] Based on the above technical solution, the pressure leveling bypass valve is equipped with an emergency button.

[0013] Based on the above technical solution, the instrument secondary header is connected to an instrument compressed air storage tank; the ash removal secondary header is connected to an ash removal compressed air storage tank.

[0014] The present invention also provides an energy-saving control method based on the above-mentioned combined system, comprising the following steps:

[0015] Step S1. Select the combination of air compressor and refrigerated dryer according to the on-site air consumption;

[0016] Step S2. Set the instrument air supply pressure value in advance. When the instrument pressure meets the requirements, the pressure leveling function can be activated, the pressure leveling bypass valve will be automatically closed, the air supply valve front switch will be opened, and the air supply valve opening will be adjusted according to the pressure difference between the instrument secondary main pipe pressure and the ash removal secondary main pipe pressure. The instrument primary main pipe pressure and the ash removal primary pressure will be used as the feedforward amount for adjusting the air supply valve, and the air supply valve opening will be adjusted in advance.

[0017] Step S3. The pressure balancing function prioritizes the safety of instrument air pressure. If the pressure difference between the instrument primary main pipe and the ash removal primary pressure shows a downward trend, the make-up air regulating valve and the valve in front of the make-up air regulating valve should be closed in time to ensure the stability of instrument air pressure. If the instrument air pressure continues to drop to the set value due to abnormal output of the instrument air compressor or the inability of the standby air compressor to start normally, the pressure balancing bypass valve should be opened to ensure the safety of instrument air by loading or starting the ash removal air compressor.

[0018] Based on the above technical solution, in step S1, each air compressor and refrigerated dryer can be selected to supply air for instrumentation or ash removal. Those not in operation can be selected as standby for instrumentation or ash removal, and can be started in conjunction with each other when the pressure drops or the operating air compressor fails.

[0019] Based on the above technical solutions, operators can freely group the operating modes of air compressors and refrigerated dryers via touch screen and operator station, and set up a one-button opening function for the pressure leveling bypass valve.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. In this invention, the air compressor and the refrigerated dryer can serve as backups for each other, satisfying the equipment combination operation under any circumstances, and achieving energy-saving and economical operation.

[0022] 2. In this invention, when expanding the capacity of air compressors and refrigerated dryers, the new equipment can be directly connected to the original system in sequence to meet the requirements of the system's expansion.

[0023] 3. In this invention, the pressure leveling function of instrument air and ash removal air is added. When the compressed air for ash removal drops instantaneously, air is supplied to the ash removal air compressor on the premise of meeting the main pipe pressure of the instrument air compressor. This reduces the need for the ash removal air compressor to start due to low pressure, keeps the operating air compressor in a loaded state as much as possible, and improves the utilization efficiency of the equipment. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the combined system of air compressor and refrigerated dryer in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the controller in an embodiment of the present invention.

[0026] Figure label:

[0027] 1. Air compressor unit; 2. Air compressor outlet electric three-way valve assembly; 3. Instrument primary main pipe; 4. Ash removal primary main pipe; 5. Refrigerated dryer inlet electric three-way valve assembly; 6. Refrigerated dryer unit; 7. Refrigerated dryer outlet electric valve assembly; 8. Instrument secondary main pipe; 9. Ash removal secondary main pipe; 10. Instrument primary main pipe pressure; 11. Ash removal primary main pipe pressure; 12. Instrument secondary main pipe pressure; 13. Ash removal secondary main pipe pressure; 14. Inlet air regulating valve front switch; 15. Inlet air regulating valve; 16. Check valve; 17. Pressure leveling bypass valve; 18. Instrument compressed air storage tank; 19. Ash removal compressed air storage tank; 20. Emergency stop button; 21. Controller; 22. Touch screen; 23. Operator station. Detailed Implementation

[0028] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0029] The following description, in conjunction with the accompanying drawings, further illustrates specific embodiments of the present invention, making the technical solution and its beneficial effects clearer and more explicit. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the invention.

[0030] See Figure 1 As shown, this embodiment of the invention provides a combined system of an air compressor and a refrigerated dryer, including an air compressor unit 1 and a refrigerated dryer unit 6, and also includes an instrument primary header 3, an ash removal primary header 4, an instrument secondary header 8, and an ash removal secondary header 9;

[0031] Air compressor unit 1 includes several air compressors, and the outlet of each air compressor is connected to the instrument primary main pipe 3 and the ash removal primary main pipe 4 through the air compressor outlet electric three-way valve group 2.

[0032] The refrigerated air dryer unit 6 includes several refrigerated air dryers. The inlet of each refrigerated air dryer is connected to the instrumentation primary header 3 and the ash removal primary header 4 through the refrigerated air dryer inlet electric three-way valve group 5. The outlet of each refrigerated air dryer is connected to the instrumentation secondary header 8 and the ash removal secondary header 9 through the refrigerated air dryer outlet electric valve group 7. A three-way valve is added to the outlet of each air compressor to ensure that any air compressor can supply air to the instrumentation and ash removal primary headers. A three-way valve is added to the inlet of each refrigerated air dryer to ensure that any refrigerated air dryer can be connected to the instrumentation and ash removal primary headers. A three-way valve is added to the outlet of each refrigerated air dryer to ensure that steam can be supplied to the instrumentation and ash removal secondary headers through any refrigerated air dryer. Qualified compressed air is stored in the corresponding compressed air storage tank.

[0033] A make-up air regulating valve 15 and a pressure leveling bypass valve 17 are connected in parallel between the instrumentation secondary header 8 and the ash removal secondary header 9. Specifically, a make-up air regulating valve 15 is connected to the instrumentation secondary header 8 via a front switch valve 14, and a check valve 16 is connected to the ash removal secondary header 9. When the pressures of the instrumentation primary header and secondary header meet the on-site pressure requirements, and the pressures of the ash removal primary and secondary headers decrease, the opening of the make-up air valve is adjusted to allow the instrumentation secondary header to supply air to the ash removal secondary header, thereby increasing the pressure of the ash removal header. Throughout this process, the air compressor is frequently in a loaded state during operation, reducing the need for simultaneous start-up of the ash removal air compressor and achieving energy-saving effects for the air compressor unit.

[0034] The instrument primary header 3 is equipped with an instrument primary header pressure of 10; the ash removal primary header 4 is equipped with an ash removal primary header pressure of 11; the instrument secondary header 8 is equipped with an instrument secondary header pressure of 12; and the ash removal secondary header 9 is equipped with an ash removal secondary header pressure of 13.

[0035] The instrumentation secondary header 8 is connected to the instrumentation compressed air storage tank 18; the ash removal secondary header 9 is connected to the ash removal compressed air storage tank 19.

[0036] When expanding the capacity of air compressors and refrigerated dryers, any number of air compressors or refrigerated dryers can be added according to the output requirements. The newly added air compressors and their outlet three-way valves, and the refrigerated dryers and their inlet and outlet three-way valves, should be connected to the primary and secondary instrumentation and ash removal main pipes in sequence according to the original design. The newly added air compressors and refrigerated dryers can then be sequentially integrated into the original system to meet the needs of equipment expansion.

[0037] See Figure 2 As shown, the combined system of the air compressor and refrigerated dryer also includes a controller 21. The controller 21 is electrically connected to the air compressor unit 1, the air compressor outlet electric three-way valve group 2, the refrigerated dryer unit 6, the refrigerated dryer inlet electric three-way valve group 5, the refrigerated dryer outlet electric valve group 7, the instrument primary main pipe pressure 10, the ash removal primary main pipe pressure 11, the instrument secondary main pipe pressure 12, the ash removal secondary main pipe pressure 13, the make-up air regulating valve 15, the make-up air regulating valve pre-operated switch 14, and the pressure leveling bypass valve 17. Specifically, the controller 21 is also electrically connected to the touch screen 22 and the operator station 23. The pressure leveling bypass valve 17 is equipped with an emergency stop button 20. The air compressor unit, electric three-way valve group, refrigerated dryer unit, instrument primary and secondary header pressure, and ash removal primary and secondary header pressure are respectively connected to the controller (PLC / DCS). The controller collects signal data from the field, receives instructions from operators (operator station / touch screen), and controls the start and stop of the air compressor unit and refrigerated dryer unit. The air compressor outlet three-way valve switches direction with the air compressor, and the refrigerated dryer inlet and outlet three-way valves switch direction with the refrigerated dryer. Based on the changes in instrument primary and secondary header pressure and ash removal primary and secondary header pressure, the controller adjusts the opening of the air supply regulating valve to achieve pressure balancing.

[0038] This invention also provides an energy-saving control method based on the above-described combined system, comprising the following steps:

[0039] Step S1. Select the combination of air compressor and refrigerated dryer according to the on-site air consumption; specifically, each air compressor and refrigerated dryer can be selected to supply air for instrumentation or ash removal. If not in operation, it can be selected as standby for instrumentation or ash removal. It can be started in conjunction with the air compressor when the pressure drops or the operating air compressor fails.

[0040] Step S2. Set the instrument air supply pressure value in advance. When the instrument pressure meets the requirements, the pressure leveling function can be activated, the pressure leveling bypass valve 17 will be automatically closed, the air supply valve front switch 14 will be opened, and the air supply valve opening will be adjusted according to the difference between the instrument secondary main pipe pressure 12 and the ash removal secondary main pipe pressure 13. The instrument primary main pipe pressure 10 and the ash removal primary pressure will be used as the feedforward amount for adjusting the air supply valve, and the air supply valve opening will be adjusted in advance.

[0041] Step S3. The pressure leveling function prioritizes the safety of the instrument air pressure. If the pressure difference between the instrument primary main pipe pressure 10 and the ash removal primary pressure shows a downward trend, the make-up air regulating valve 15 and the switch 14 before the make-up air regulating valve should be closed in time to ensure the stability of the instrument air pressure. If the instrument air pressure continues to drop to the set value due to abnormal output of the instrument air compressor or the inability of the standby air compressor to start normally, the pressure leveling bypass valve 17 should be opened to ensure the safety of the instrument air by loading or starting the ash removal air compressor.

[0042] Operators can freely group the operating modes of air compressors and refrigerated dryers via touch screen 22 and operator station 23, and at the same time set the function of one-button opening of pressure leveling bypass valve 17.

[0043] The present invention will be further described below through specific embodiments.

[0044] The instrument pressure is set to 0.65MPa (can be freely set). When the instrument pressure is met, the pressure leveling function is allowed. The ash removal pressure is set to 0.45MPa (can be freely set). When there is a positive difference between the instrument secondary main pipe pressure and the ash removal secondary main pipe pressure, the controller adjusts the system to calculate the air supply valve opening value (0-100) and open it.

[0045] The pressure of the instrument's primary main pipe and the pressure of the ash removal primary main pipe are used as feedforwards for adjusting the air supply valve.

[0046] When the pressure of the primary main pipe for instrumentation is within the normal range (which can be set), it proves that the output of the instrumentation air compressor is normal and the air supply valve is open normally. When the pressure drops, the current opening of the air supply valve is locked. After the pressure returns to normal, the air supply valve is opened again according to the pressure difference of the secondary main pipe for ash removal in the instrumentation.

[0047] When the pressure of the primary main pipe for ash removal increases, the air supply valve is slowly closed. When the pressure continues to decrease, it proves that the pressure leveling circuit can no longer meet the air requirements for ash removal, and the controller starts the standby ash removal air compressor.

[0048] Set the external interlock condition for the air supply valve to open, and the interlock will be opened when the instrument air compressor is switching operation.

[0049] If any of the selected instrument air compressors exhibit abnormal output or a continuous drop in instrument pressure, the pressure balancing function will automatically disengage, and the pressure balancing bypass valve will be interlocked and opened. The bypass valve can be opened with a single press of the emergency button if the controller malfunctions or if the operator deems it necessary.

[0050] In the description of this specification, references to terms such as "an embodiment," "preferred," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. Illustrative expressions of the above terms in this specification do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0051] This invention is not limited to the embodiments described above. Those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. An energy-saving control method based on a combined system, the combined system including an air compressor unit (1) and a refrigerated dryer unit (6), and also including an instrument primary header (3), an ash removal primary header (4), an instrument secondary header (8) and an ash removal secondary header (9). The air compressor unit (1) includes several air compressors, and the outlet of each air compressor is connected to the instrument primary main pipe (3) and the ash removal primary main pipe (4) through the air compressor outlet electric three-way valve group (2); The refrigerated air dryer unit (6) includes several refrigerated air dryers. The inlet of each refrigerated air dryer is connected to the instrument primary main pipe (3) and the ash removal primary main pipe (4) through the refrigerated air dryer inlet electric three-way valve group (5); the outlet of each refrigerated air dryer is connected to the instrument secondary main pipe (8) and the ash removal secondary main pipe (9) through the refrigerated air dryer outlet electric valve group (7). An air supply regulating valve (15) and a pressure leveling bypass valve (17) are connected in parallel between the instrument secondary main pipe (8) and the ash removal secondary main pipe (9). A front switch (14) is provided between the gas supply regulating valve (15) and the instrument secondary main pipe (8), and a check valve (16) is provided between the gas supply regulating valve (15) and the ash removal secondary main pipe (9). The instrument primary header (3) is equipped with an instrument primary header pressure (10); the ash removal primary header (4) is equipped with an ash removal primary header pressure (11); the instrument secondary header (8) is equipped with an instrument secondary header pressure (12); and the ash removal secondary header (9) is equipped with an ash removal secondary header pressure (13). It also includes a controller (21), which is electrically connected to the air compressor unit (1), the air compressor outlet electric three-way valve group (2), the refrigerated dryer unit (6), the refrigerated dryer inlet electric three-way valve group (5), the refrigerated dryer outlet electric valve group (7), the instrument primary main pipe pressure (10), the ash removal primary main pipe pressure (11), the instrument secondary main pipe pressure (12), the ash removal secondary main pipe pressure (13), the air replenishment regulating valve (15), the air replenishment regulating valve front switch (14), and the pressure leveling bypass valve (17). The controller (21) is also electrically connected to the touch screen (22) and the operator station (23); The pressure leveling bypass valve (17) is equipped with an emergency button (20); The instrument secondary header (8) is connected to an instrument compressed air storage tank (18); the ash removal secondary header (9) is connected to an ash removal compressed air storage tank (19), characterized in that... Includes the following steps: Step S1. Select the combination of air compressor and refrigerated dryer according to the on-site air consumption; Step S2. Set the instrument air supply pressure value in advance. When the instrument pressure meets the requirements, activate the pressure leveling function, automatically close the pressure leveling bypass valve (17), open the air supply valve front switch (14), adjust the air supply valve opening according to the difference between the instrument secondary main pipe pressure (12) and the ash removal secondary main pipe pressure (13), and use the instrument primary main pipe pressure (10) and the ash removal primary pressure as the feedforward of the air supply valve adjustment to adjust the air supply valve opening in advance. Step S3. The pressure leveling function prioritizes the safety of the instrument air pressure. If the pressure difference between the instrument primary main pipe pressure (10) and the ash removal primary pressure shows a downward trend, the make-up air regulating valve (15) and the valve in front of the make-up air regulating valve (14) should be closed in time to ensure the instrument pressure is stable. If the instrument pressure continues to drop to the set value due to abnormal output of the instrument operating air compressor or the inability of the standby air compressor to start normally, the pressure leveling bypass valve (17) should be opened to ensure the safety of the instrument air by loading or starting the ash removal air compressor.

2. The energy-saving control method as described in claim 1, characterized in that: In step S1, each air compressor and refrigerated dryer can be selected to supply air for instrumentation or ash removal. Those not in operation can be selected as standby for instrumentation or ash removal. They can be activated in case of pressure drop or failure of the operating air compressor.

3. The energy-saving control method as described in claim 1, characterized in that: Operators can freely group the operating modes of air compressors and refrigerated dryers through the touch screen (22) and operator station (23), and at the same time set the function of one-button opening of pressure leveling bypass valve (17).

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