Waste heat recovery system, waste heat recovery unit, and waste heat recovery method
The system addresses heat exchanger damage by diverting fluids using bypass passages and control valves when temperatures rise, maintaining safe operating conditions and enabling efficient waste heat recovery.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- HITACHI IND EQUIP SYST CO LTD
- Filing Date
- 2024-12-26
- Publication Date
- 2026-07-08
AI Technical Summary
Conventional waste heat recovery systems risk damage to heat exchangers due to rising temperatures of waste heat recovery water exceeding its boiling point, leading to increased internal pressure and potential structural failure.
A waste heat recovery system with a bypass passage and control valves to divert coolant or waste heat recovery liquid away from heat exchangers when temperatures exceed a threshold, using temperature sensors and controllers to manage flow paths and prevent overheating.
Prevents damage to heat exchangers by controlling fluid flow to maintain safe operating temperatures, ensuring continuous operation and efficient waste heat recovery.
Smart Images
Figure 2026114763000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a waste heat recovery system, a waste heat recovery unit, and a waste heat recovery method.
Background Art
[0002] A gas compressor that sucks in a gas such as air and discharges a high-pressure gas such as compressed air by a suction compression mechanism is known. In particular, an air compressor is used in factory lines and work sites as an air source for machine tools, presses, air blows, etc. Here, it is said that the total energy consumed by the gas compressor accounts for 20 to 25% of the energy consumed throughout the factory, and the effect of recovering waste heat from the gas compressor is great. In particular, in order to achieve the goal of reducing CO2 emissions starting from the global warming problem, the utilization of waste heat from gas compressors is expected to be further emphasized in the future.
[0003] A gas compressor is composed of a compressor body that compresses a gas such as air, a cooling system that absorbs the heat generated by compression, a motor that is a driving power source of the compressor, etc. Also, in a gas compressor, assuming the motor input power is 100%, the amount of heat absorbed in the cooling system corresponds to 90% or more of it, and that amount of heat is usually released to the outside air, and a very large amount of energy is discharged into the atmosphere. In order to reduce the amount of waste heat, the improvement of the efficiency of the compressor body and the motor has been promoted, but the effect is limited to a few percent, and the effective utilization of waste heat from the gas compressor is required.
[0004] As a conventional technique in this technical field, there is Patent Document 1. Patent Document 1 describes a waste heat recovery system having a temperature sensor installed downstream of a heat exchanger for waste heat recovery in an exhaust heat recovery liquid pipe, a temperature control valve, and a temperature controller that controls the opening and closing angle of the temperature control valve according to the temperature of the exhaust heat recovery water measured by the temperature sensor and the set recovery water temperature.
Prior Art Documents
Patent Documents
[0005] [Patent Document 1] Japanese Patent Publication No. 2021-96043 [Overview of the project] [Problems that the invention aims to solve]
[0006] In the technology described in Patent Document 1, the waste heat recovery water flowing through the heat exchanger is supplied to the waste heat utilization side and cooled by being used as a heat source. However, if the customer does not utilize the waste heat recovery water as a heat source, the waste heat recovery water will return to the heat exchanger without being cooled, causing its temperature to rise further. Since the temperature of compressed air can reach up to approximately 170 degrees Celsius, if the temperature of the waste heat recovery water exceeds its boiling point, the internal pressure of the heat exchanger piping will increase, potentially damaging the heat exchanger.
[0007] Therefore, the present invention aims to provide a technology that can prevent damage to heat exchangers used for waste heat recovery. [Means for solving the problem]
[0008] To solve the above problems, one representative waste heat recovery system of the present invention is a waste heat recovery system comprising a fluid machine body through which a fluid flows and a waste heat recovery machine that recovers waste heat from the fluid, wherein the fluid machine body comprises a cooling heat exchanger that exchanges heat between a coolant and a fluid, and a coolant piping through which the coolant flows, and the waste heat recovery machine comprises a waste heat recovery heat exchanger that exchanges heat between a waste heat recovery liquid and a fluid, a waste heat recovery liquid piping through which the waste heat recovery liquid flows, and the upstream of the waste heat recovery heat exchanger in the waste heat recovery liquid piping and the fluid machine body The system includes a first bypass passage connecting the coolant piping to the outlet side of the auxiliary cooling equipment which is not connected to the coolant piping, a second bypass passage connecting the downstream side of the waste heat recovery heat exchanger in the waste heat recovery liquid piping to the inlet side of the auxiliary cooling equipment, a first valve for opening and closing the first bypass passage, a second valve for opening and closing the second bypass passage, and a control unit for controlling the first and second valves. The control unit controls the first and second valves to open the first and second bypass passages when the temperature of the waste heat recovery liquid exceeds a threshold. [Effects of the Invention]
[0009] According to the present invention, damage to the heat exchanger for waste heat recovery can be prevented.
[0010] Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]
[0011] [Figure 1] This is a schematic diagram showing an example of the general configuration of the waste heat recovery system of the first embodiment. [Figure 2] This figure shows an example of the flow path of waste heat recovery water and cooling water under normal conditions in the waste heat recovery system of the first embodiment. [Figure 3] This figure shows an example of the flow path between waste heat recovery water and cooling water when the temperature of the waste heat recovery water exceeds a threshold in the waste heat recovery system of the first embodiment. [Figure 4] This flowchart shows an example of the control performed by the temperature controller in the waste heat recovery system of the first embodiment. [Figure 5] This graph shows an example of the temperature change of the waste heat recovered water in the waste heat recovery system of the first embodiment. [Figure 6] This is a schematic diagram showing an example of the general configuration of the waste heat recovery system in the second embodiment. [Figure 7] This figure shows an example of the flow path of waste heat recovery water and cooling water under normal conditions in the waste heat recovery system of the second embodiment. [Figure 8] This figure shows an example of the flow path between waste heat recovery water and cooling water when the temperature of the waste heat recovery water exceeds a threshold in the waste heat recovery system of the second embodiment. [Figure 9] This is a schematic diagram showing a modified example of the general configuration of the waste heat recovery system of the second embodiment. [Figure 10] This figure shows an example of the flow path of waste heat recovery water and cooling water under normal conditions in a modified example of the waste heat recovery system of the second embodiment. [Figure 11]It is a diagram showing an example of the flow paths of waste heat recovery water and cooling water when the temperature of the waste heat recovery water in a modified example of the waste heat recovery system of the second embodiment exceeds the threshold value. [Figure 12] It is a flowchart showing an example of the control performed by the temperature regulator in the waste heat recovery system of the second embodiment.
Mode for Carrying Out the Invention
[0012] Hereinafter, embodiments of the present invention will be described based on the drawings. In this embodiment, as an air compressor, a water-cooled packaged two-stage oil-free screw compressor that compresses air will be described as an example.
[0013] FIG. 1 is a schematic diagram showing an example of the schematic configuration of the waste heat recovery system of the first embodiment.
[0014] As shown in FIG. 1, the waste heat recovery system 100 includes an air compressor 1 that compresses air and a waste heat recovery machine 2 that recovers waste heat from the compressed air discharged from the air compressor 1.
[0015] The air compressor 1 includes compressor bodies 101 and 102, heat exchangers 103 and 104 for cooling, and an oil cooler 105, and these devices are arranged inside a housing. Although not shown, the housing has a base on which devices such as the compressor bodies 101 and 102 are installed, and a box-shaped cover composed of a plurality of panels made of metal or the like installed on the base so as to cover the devices such as the compressor bodies 101 and 102, and has excellent sound insulation performance.
[0016] The waste heat recovery machine 2 includes heat exchangers 201 and 202 and a temperature regulator 206, and these devices are arranged inside a housing. Although not shown, the housing has a base on which devices such as the heat exchangers 201 and 202 are installed, and a box-shaped cover composed of a plurality of panels made of metal or the like installed on the base so as to cover the devices such as the heat exchangers 201 and 202, and has excellent sound insulation performance.
[0017] The compressor bodies 101 and 102 each include a screw rotor composed of one male rotor and one female rotor not shown in the figure. Further, the compressor bodies 101 and 102 are configured to be driven by a main motor (not shown) disposed within the housing, for example, via a power transmission mechanism. Note that the power of the compressor bodies 101 and 102 is not limited to an electric motor, and an internal combustion engine or the like may be used.
[0018] The compressor body 101 is the first-stage compressor body disposed on the upstream side of the air flow, and the compressor body 102 is the second-stage compressor body disposed downstream of the air flow with respect to the first-stage compressor body 101.
[0019] Since the compressor bodies 101 and 102 in the present embodiment are oil-free screw compressors, unlike a liquid supply type air compressor that injects a liquid such as oil or water into the compression working chamber, the compressor bodies 101 and 102 tend to generate heat particularly due to the heat generated during air compression. And since the compressed air is at a high temperature, it may not be suitable for use by the demand source of the compressed air. For this reason, in the air compressor 1, cooling water is supplied to each part. Further, as will be described later, the air compressor 1 of the present embodiment is configured to be able to recover the waste heat generated when the compressor bodies 101 and 102 compress air.
[0020] The heat exchangers 201 and 202 for waste heat recovery perform heat exchange between the waste heat recovery water as the waste heat recovery liquid sent from the waste heat treatment facility 4 on the utilization side of the waste heat generated by the compressor bodies 101 and 102 and the compressed air discharged from the compressor bodies 101 and 102.
[0021] The heat exchanger 201 is an intermediate-stage waste heat recovery heat exchanger disposed between the first-stage compressor body 101 and the second-stage compressor body 102, and the heat exchanger 202 is a discharge-stage waste heat recovery heat exchanger disposed on the discharge side (downstream side) of the second-stage compressor body 102.
[0022] The heat treatment equipment 4 cools the waste heat recovery water by exchanging heat with chilled water and converts the chilled water into hot water for use by the user, but is not limited to this; the waste heat recovery water may also be exchanged with oil or air, or the user may use the waste heat recovery water itself.
[0023] The cooling heat exchangers 103 and 104 perform heat exchange between cooling water, which is supplied as a coolant from a cooling system 3 located outside the air compressor 1, and compressed air discharged from the compressor bodies 101 and 102.
[0024] Heat exchanger 103 is a cooling heat exchanger located between the first-stage compressor body 101 and the second-stage compressor body 102 (hereinafter referred to as the intercooler), and heat exchanger 104 is a cooling heat exchanger located on the discharge side of the second-stage compressor body 102 (hereinafter referred to as the aftercooler).
[0025] The cooling equipment 3 cools the cooling water by exchanging heat with the outside atmosphere or other external heat sources of the waste heat recovery system 100.
[0026] Between the first-stage compressor body 101 and the second-stage compressor body 102, an intermediate-stage waste heat recovery heat exchanger 201 and an intercooler 103 are arranged in order from the upstream side. On the discharge side of the second-stage compressor body 102, a discharge-stage waste heat recovery heat exchanger 202 and an aftercooler 104 are arranged in order from the upstream side. In some cases, the arrangement order of the waste heat recovery heat exchangers 201 and 202 and the intercooler 103 and aftercooler 104 may be reversed.
[0027] The first-stage compressor body 101, the intermediate-stage heat exchanger 201 for waste heat recovery, the intercooler 103, the second-stage compressor body 102, the discharge-stage heat exchanger 202 for waste heat recovery, and the aftercooler 104 are connected by air piping 108 through which the air to be compressed flows.
[0028] The above flow path is for load operation. During unload operation, the vent air flows through the first-stage compressor body 101, the intermediate-stage heat exchanger 201 for waste heat recovery, the intercooler 103, the second-stage compressor body 102, and the discharge-stage heat exchanger 202 for waste heat recovery. As a result of unload operation, the check valve 109 is fully closed, and the vent air is released into the atmosphere through the vent pipe 107. This structure allows vent air to flow through the heat exchangers 201 and 202 even during no-load operation, enabling waste heat recovery regardless of the operating conditions and improving the waste heat recovery rate.
[0029] Furthermore, there are waste heat recovery liquid pipes 211 through which waste heat recovery water, which exchanges heat with compressed air in heat exchangers 201 and 202 for waste heat recovery, flows, and cooling liquid pipes 106 through which cooling water, which exchanges heat with compressed air in the intercoolers 103 and aftercoolers 104 for cooling, flows.
[0030] The waste heat recovery liquid piping 211 is sent from the heat treatment facility 4 on the waste heat utilization side by the operation of the circulation pump 207, and is connected to the heat treatment facility 4 via the heat exchanger 201 for intermediate stage waste heat recovery and the heat exchanger 202 for discharge stage waste heat recovery.
[0031] Furthermore, the waste heat recovery liquid piping 211 is equipped with a temperature sensor 205 for measuring the temperature of the waste heat recovery water and a flow meter 209 for measuring the flow rate of the waste heat recovery water downstream of the heat treatment equipment 4.
[0032] The coolant piping 106 is configured to branch off from the cooling equipment 3 into a first coolant piping 106a, a second coolant piping 106b, and a third coolant piping 106c, after which they all merge and connect to the cooling equipment 3.
[0033] The first coolant pipe 106a connects from the cooling equipment 3 to the cooling equipment 3 via the aftercooler 104. The second coolant pipe 106b connects from the cooling equipment 3 to the cooling equipment 3 via the oil cooler 105, the cooling jacket provided on the casing of the second-stage compressor body 102, and the cooling jacket provided on the casing of the first-stage compressor body 101. The third coolant pipe 106c connects from the cooling equipment 3 to the cooling equipment 3 via the intercooler 103.
[0034] The upstream sections of the coolant piping 106, including the intercooler 103, aftercooler 104, and oil cooler 105, and the upstream section of the heat exchanger 201 for intermediate-stage waste heat recovery in the waste heat recovery fluid piping 211 are connected by a branch pipe 110 on the coolant inlet side.
[0035] Furthermore, the downstream side of the heat exchanger 202 for waste heat recovery at the discharge stage of the waste heat recovery liquid piping 211 is connected to the downstream side of the intercooler 103, aftercooler 104, and oil cooler 105 of the coolant piping 106 by a branch pipe 111 on the coolant outlet side.
[0036] At the connection point between the waste heat recovery liquid piping 211 and the branch pipe 110 on the coolant inlet side, an inlet-side flow path switching three-way valve 203 is provided to switch between the flow path from the upstream of the waste heat recovery liquid piping 211 and the flow path from the branch pipe 110 on the coolant inlet side.
[0037] Furthermore, at the connection point between the waste heat recovery liquid piping 211 and the branch pipe 111 on the coolant outlet side, there is an outlet-side flow path switching three-way valve 204 that switches between the flow path downstream of the waste heat recovery liquid piping 211 and the flow path to the branch pipe 111 on the coolant outlet side.
[0038] The upstream side of the flow path switching three-way valve 203 on the inlet side of the waste heat recovery liquid piping 211 and the downstream side of the flow path switching three-way valve 204 on the outlet side of the waste heat recovery liquid piping 211 are connected by the waste heat recovery liquid circulation piping 210, and a temperature control valve 208 that can open and close the waste heat recovery liquid circulation piping 210 is provided.
[0039] The temperature controller 206 controls the flow path switching three-way valves 203 and 204 and the temperature control valve 208 according to the temperature measured by the temperature sensor 205 and the set temperature.
[0040] The oil cooler 105, although not shown in the diagram, is a water-cooled heat exchanger for cooling the lubricating oil that lubricates the bearings of the compressor bodies 101 and 102, the power transmission mechanism, etc. The lubricating oil cooled by the oil cooler 105 lubricates the bearings of the compressor bodies 101 and 102, etc., and is then stored in an oil reservoir (not shown). Subsequently, the lubricating oil is guided to the oil cooler 105 by a transport mechanism such as an oil pump (not shown) to be cooled and circulated through this lubrication path.
[0041] Next, the operation of the waste heat recovery system 100 configured in this manner will be described.
[0042] In Figure 1, the air compressor 1 draws in air through a capacity control valve (not shown) located upstream of the first-stage compressor body 101, and compresses the air in the first-stage compressor body 101. The compressed high-temperature air (for example, about 160°C) then exchanges the required amount of heat in the intermediate-stage waste heat recovery heat exchanger 201, and is further cooled in the intercooler 103. Here, heat exchange takes place in the intermediate-stage waste heat recovery heat exchanger 201 as compressed high-temperature air and waste heat recovery water flow through it, and heat exchange takes place in the intercooler 103 as compressed air whose temperature has decreased due to heat exchange in the intermediate-stage waste heat recovery heat exchanger 201 and cooling water flow through it.
[0043] Next, the air cooled by the intercooler 103 (for example, around 40°C) is compressed further by the second-stage compressor body 102 to increase its pressure. Then, the compressed high-temperature air (for example, around 160°C or even higher) is used to exchange the required amount of heat again in the heat exchanger 202 for waste heat recovery from the discharge stage, and is further cooled by the aftercooler 104. Finally, the air cooled by the aftercooler 104 (for example, around 40°C) is sent to the source of the compressed air demand.
[0044] Next, the distribution routes for waste heat recovery water and cooling water in the waste heat recovery system 100 will be described.
[0045] Figure 2 shows an example of the flow path of waste heat recovery water and cooling water in the waste heat recovery system 100 of the first embodiment under normal conditions.
[0046] As shown by the dashed line, the waste heat recovery water flows in from the heat treatment facility 4 on the waste heat utilization side by operating the circulation pump 207, flows through the waste heat recovery liquid piping 211, has its temperature measured by the temperature sensor 205, exchanges heat with compressed air in the waste heat recovery heat exchangers 201 and 202, and then flows out towards the heat treatment facility 4 on the waste heat utilization side.
[0047] As shown by the dotted line, the cooling water flows in from the cooling equipment 3, branches off from the cooling liquid piping 106 into the first cooling liquid piping 106a, the second cooling liquid piping 106b, and the second cooling liquid piping c, exchanges heat with compressed air in the intercooler 103 and aftercooler 104, or exchanges heat with lubricating oil in the oil cooler 105, before rejoining and flowing out towards the cooling equipment 3.
[0048] If the user does not use the heat treatment equipment 4 to exchange heat between the waste heat recovery water and the chilled water, the waste heat recovery water that has exchanged heat with compressed air in the waste heat recovery heat exchangers 201 and 202 will not be cooled by the heat treatment equipment 4, causing the temperature of the waste heat recovery water circulating in the waste heat recovery liquid piping 211 to rise. If the temperature of the waste heat recovery water exceeds its boiling point, the internal pressure of the waste heat recovery liquid piping 211 will increase, potentially damaging the waste heat recovery heat exchangers 201 and 202.
[0049] Therefore, in this embodiment, if the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds a preset threshold, the temperature controller 206 switches the flow path switching three-way valves 203 and 204 and opens the temperature control valve 208, thereby switching the flow path of the waste heat recovery water and the cooling water.
[0050] Figure 3 shows an example of the flow path between waste heat recovery water and cooling water when the temperature of the waste heat recovery water exceeds a threshold in the waste heat recovery system 100 of the first embodiment.
[0051] If the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds a threshold, the temperature controller 206 switches the flow path switching three-way valves 203 and 204, causing the cooling water to flow in from the cooling equipment 3 as shown by the dotted line, and then branch out from the cooling liquid piping 106 to the first cooling liquid piping 106a, the second cooling liquid piping 106b, the second cooling liquid piping c, and the branch piping 110 on the cooling liquid inlet side.
[0052] The coolant flowing from the coolant pipe 106 into the first coolant pipe 106a, the second coolant pipe 106b, or the second coolant pipe c exchanges heat with compressed air in the intercooler 103 and aftercooler 104, or with lubricating oil in the oil cooler 105, before merging and flowing out toward the cooling equipment 3.
[0053] The cooling water that flows from the cooling liquid piping 106 into the branch piping 110 on the cooling liquid inlet side flows through the waste heat recovery liquid piping 211, exchanges heat with compressed air in the waste heat recovery heat exchangers 201 and 202, and then rejoins the cooling liquid piping 106 via the branch piping 111 on the cooling liquid outlet side and flows out toward the cooling equipment 3.
[0054] Furthermore, if the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds a threshold, the temperature controller 206 opens the temperature control valve 208, causing the waste heat recovery water to flow in from the heat treatment facility 4 on the waste heat utilization side, as shown by the dashed line, through the waste heat recovery liquid piping 211, and via the waste heat recovery liquid circulation piping 210, without passing through the heat exchangers 201 and 202 for waste heat recovery, and flow out towards the heat treatment facility 4 on the waste heat utilization side.
[0055] According to this embodiment, if the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds a threshold, the temperature controller 206 switches the flow path switching three-way valves 203 and 204, and uses the cooling water from the cooling equipment 3 for heat exchange with compressed air in the waste heat recovery heat exchangers 201 and 202. This prevents the temperature of the waste heat recovery water from rising and prevents damage to the waste heat recovery heat exchangers.
[0056] Figure 4 is a flowchart showing an example of the control performed by the temperature controller 206 in the waste heat recovery system 100 of the first embodiment.
[0057] In Figure 4, it is assumed that at the start of processing, the waste heat recovery water and cooling water are flowing through the normal distribution route shown in Figure 2.
[0058] When the air compressor 1 starts operating, power is supplied to the temperature controller 206 and control begins.
[0059] In S302, the temperature controller 206 acquires the temperature of the waste heat recovery water in the waste heat recovery liquid piping 211, which was measured by the temperature sensor 205.
[0060] In S303, the temperature controller 206 determines whether the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds 95°C. If the temperature of the waste heat recovery water exceeds 95°C in S303, the process proceeds to S304. On the other hand, if the temperature of the waste heat recovery water does not exceed 95°C in S303, the process proceeds to S314, where the system waits in a normal state for a preset time before returning to S302.
[0061] In S304, the temperature controller 206 switches the inlet-side flow path switching three-way valve 203, allowing the coolant from the coolant pipe 106 to flow into the waste heat recovery liquid pipe 211 using the branch pipe 110 on the coolant inlet side. At the same time, the temperature controller 206 switches the outlet-side flow path switching three-way valve 204, allowing the coolant that has passed through the intermediate-stage waste heat recovery heat exchanger 201 and the discharge-stage waste heat recovery heat exchanger 202 to flow into the coolant outlet-side branch pipe 111.
[0062] In S305, the temperature controller 206 opens the temperature control valve 208, thereby opening the waste heat recovery liquid circulation pipe 210 and enabling the circulation of waste heat recovery water from the heat treatment equipment 4.
[0063] In S306, after executing S304 and S305, the system waits for a predetermined time. The waiting time is set to a time sufficient for the temperature of the waste heat recovery water, which has exceeded 95°C, to decrease.
[0064] In S307, the temperature controller 206 reacquires the temperature of the waste heat recovery water in the waste heat recovery liquid piping 211, which was measured by the temperature sensor 205.
[0065] In S308, the temperature controller 206 determines whether the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds 95°C. If the temperature of the waste heat recovery water exceeds 95°C in S308, the process proceeds to S310.
[0066] In S310, the temperature controller 206 outputs a severe fault signal.
[0067] In S311, the temperature controller 206 stops the operation of the circulation pump 207, air compressor 1, and waste heat recovery unit 2 installed in the waste heat recovery liquid piping 211, and terminates the process.
[0068] On the other hand, if the temperature of the waste heat recovery water does not exceed 95°C in S308, the process proceeds to S309.
[0069] In S309, it is determined whether the temperature of the waste heat recovery water obtained in S307 is below 40°C. If the temperature of the waste heat recovery water is not below 40°C in S309, the process returns to S306 and waits for a predetermined time.
[0070] On the other hand, if the temperature of the waste heat recovery water is below 40°C in S309, the process proceeds to S312.
[0071] In S312, the temperature controller 206 switches the inlet-side flow path switching three-way valve 203, sending the waste heat recovered water from the heat treatment equipment 4 to the waste heat recovery heat exchangers 201 and 202. At the same time, the temperature controller 206 switches the outlet-side flow path switching three-way valve 204, sending the waste heat recovered water from the waste heat recovery heat exchangers 201 and 202 back to the heat treatment equipment 4.
[0072] In S313, the temperature controller 206 closes the waste heat recovery liquid circulation pipe 210 by closing the temperature control valve 208.
[0073] In S314, the system waits in a normal state for a predetermined time, then returns to S302.
[0074] Figure 5 is a graph showing an example of the temperature change of the waste heat recovered water in the waste heat recovery system 100 of the first embodiment.
[0075] In Figure 5, the vertical axis represents the temperature of the waste heat recovery water measured by the temperature sensor 205, and the horizontal axis represents the passage of time.
[0076] If the user does not use the heat treatment equipment 4 to exchange heat between the waste heat recovery water and the chilled water, the waste heat recovery water that has exchanged heat with compressed air in the heat exchangers 201 and 202 for waste heat recovery will not be cooled by the heat treatment equipment 4, causing the temperature of the waste heat recovery water circulating in the waste heat recovery liquid piping 211 to rise.
[0077] If the temperature of the waste heat recovery water exceeds 95°C, the temperature controller 206 switches the flow path switching three-way valves 203 and 204 and opens the temperature control valve 208 by performing the control shown in Figure 4.
[0078] As a result, the waste heat recovery water circulates through a distribution path that does not pass through the waste heat recovery heat exchangers 201 and 202 shown in Figure 3, thereby preventing the temperature of the waste heat recovery water from rising and preventing damage to the waste heat recovery heat exchangers.
[0079] Subsequently, if the temperature of the waste heat recovery water measured by the temperature sensor 205 falls below 40°C, the temperature controller 206 switches the flow path switching three-way valves 203 and 204 and closes the temperature control valve 208.
[0080] As a result, the waste heat recovery water circulates through the flow path shown in Figure 2, passing through the waste heat recovery heat exchangers 201 and 202. In this way, it exchanges heat with compressed air in the waste heat recovery heat exchangers 201 and 202, and the waste heat from the air compressor 1 can be recovered.
[0081] Although examples have been described above, the present invention is not limited to the above-described examples and includes various modifications. For example, the above-described examples are described in detail for the purpose of explaining the present invention in an easy-to-understand manner and are not necessarily limited to those having all the configurations described.
[0082] For example, in this embodiment, the waste heat recovery liquid piping 211 is configured to connect from the heat treatment equipment 4 to the heat treatment equipment 4 via a heat exchanger 201 for intermediate-stage waste heat recovery and a heat exchanger 202 for discharge-stage waste heat recovery, but it is not limited to this configuration. That is, multiple waste heat recovery liquid piping 211s are provided to correspond to multiple heat exchangers for waste heat recovery, and each of the multiple waste heat recovery liquid pipings may be provided as a separate, independent path within the housing.
[0083] Here, the multiple heat exchangers for waste heat recovery may consist of an intermediate-stage waste heat recovery heat exchanger 201 and a discharge-stage waste heat recovery heat exchanger 202. Alternatively, the multiple heat exchangers for waste heat recovery may be configured as multiple heat exchangers in which the intermediate-stage waste heat recovery heat exchanger 201 (or the discharge-stage waste heat recovery heat exchanger 202) are connected in series.
[0084] With this configuration, it is possible to obtain and utilize waste heat recovery water at multiple different temperatures from each of the multiple waste heat recovery liquid pipes. This makes it possible to accommodate multiple facilities that require waste heat recovery water at different temperatures.
[0085] Furthermore, in this embodiment, the coolant piping 106 is configured to branch off from the cooling equipment 3 into a first coolant piping 106a, a second coolant piping 106b, and a third coolant piping 106c, which then merge and connect to the cooling equipment 3, but the invention is not limited to this configuration.
[0086] For example, multiple coolant pipes 106 are provided to correspond to multiple heat exchangers for cooling, and each of the multiple coolant pipes may be provided as a separate, independent path within the housing.
[0087] Here, the multiple cooling heat exchangers may be intercoolers 103 and aftercoolers 104. Alternatively, the multiple cooling heat exchangers may be configured as multiple heat exchangers in which intercoolers 103 (or aftercoolers 104) are connected in series.
[0088] Furthermore, in this embodiment, the flow paths of the waste heat recovery water and cooling water are controlled by a temperature sensor 205, a temperature controller 206, flow path switching three-way valves 203 and 204, and a temperature control valve 208. However, the invention is not limited to this, and it is sufficient if the flow path can be controlled by the temperature of the waste heat recovery water. For example, a self-operating automatic temperature control valve that does not require auxiliary power such as pneumatic, hydrostatic, hydraulic, or electric power may be used without using the temperature sensor 205 or the temperature controller 206.
[0089] Figure 6 is a schematic diagram showing an example of the general configuration of the waste heat recovery system of the second embodiment. In Figure 6, components identical to those in the first embodiment in Figure 1 are denoted by the same reference numerals, and their descriptions are omitted.
[0090] The waste heat recovery system 100 of the second embodiment differs from the first embodiment in that an auxiliary cooling system 3a is provided separately from the cooling system 3. The cooling system 3 cools the waste heat recovery water by exchanging heat with the outside atmosphere or the like.
[0091] Furthermore, the waste heat recovery system 100 of the second embodiment is provided with a waste heat recovery liquid outlet pipe 114 to the auxiliary cooling equipment, which connects the outlet side flow path switching three-way valve 204 to the inlet side of the auxiliary cooling equipment 3a, instead of the branch pipe 111 of the first embodiment. In addition, the waste heat recovery system 100 of the second embodiment is provided with a waste heat recovery liquid inlet pipe 113 from the auxiliary cooling equipment, which connects the outlet side and the inlet side flow path switching three-way valve 203 of the auxiliary cooling equipment 3a, instead of the branch pipe 110 of the first embodiment. An auxiliary cooling pump 207a is provided on the waste heat recovery liquid inlet pipe 113 from the auxiliary cooling equipment.
[0092] Next, the flow paths of the waste heat recovery water and cooling water in the waste heat recovery system 100 of the second embodiment will be described.
[0093] Figure 7 shows an example of the flow path of waste heat recovery water and cooling water in the waste heat recovery system 100 of the second embodiment under normal conditions.
[0094] The inlet-side flow path switching three-way valve 203 closes the flow path from the auxiliary cooling equipment 3a to the intermediate-stage waste heat recovery heat exchanger 201, and opens the flow path from the heat treatment equipment 4 to the intermediate-stage waste heat recovery heat exchanger 201. The outlet-side flow path switching three-way valve 204 closes the flow path from the discharge-stage waste heat recovery heat exchanger 202 to the auxiliary cooling equipment 3a, and opens the flow path from the discharge-stage waste heat recovery heat exchanger 202 to the heat treatment equipment 4.
[0095] As shown by the dashed line, the waste heat recovery water flows in from the heat treatment facility 4 on the waste heat utilization side by operating the circulation pump 207, flows through the waste heat recovery liquid piping 211, has its temperature measured by the temperature sensor 205, exchanges heat with compressed air in the waste heat recovery heat exchangers 201 and 202, and then flows out towards the heat treatment facility 4 on the waste heat utilization side.
[0096] As shown by the dotted line, the cooling water flows in from the cooling equipment 3, branches off from the cooling liquid piping 106 into the first cooling liquid piping 106a, the second cooling liquid piping 106b, and the second cooling liquid piping c, exchanges heat with compressed air in the intercooler 103 and aftercooler 104, or exchanges heat with lubricating oil in the oil cooler 105, before rejoining and flowing out towards the cooling equipment 3.
[0097] The auxiliary cooling pump 207a is stopped, and the auxiliary cooling equipment 3a, the waste heat recovery liquid inlet pipe 113 from the auxiliary cooling equipment, and the waste heat recovery liquid outlet pipe 114 to the auxiliary cooling equipment are not used.
[0098] If the user does not use the heat treatment equipment 4 to exchange heat between the waste heat recovery water and the chilled water, the waste heat recovery water that has exchanged heat with compressed air in the waste heat recovery heat exchangers 201 and 202 will not be cooled by the heat treatment equipment 4, causing the temperature of the waste heat recovery water circulating in the waste heat recovery liquid piping 211 to rise. If the temperature of the waste heat recovery water exceeds its boiling point, the internal pressure of the waste heat recovery liquid piping 211 will increase, potentially damaging the waste heat recovery heat exchangers 201 and 202.
[0099] Therefore, in this embodiment, if the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds a preset threshold, the temperature controller 206 switches the flow path switching three-way valves 203 and 204, operates the auxiliary cooling pump 207a, and opens the temperature control valve 208, thereby switching the flow paths of the waste heat recovery water and the cooling water.
[0100] Figure 8 shows an example of the flow path between waste heat recovery water and cooling water when the temperature of the waste heat recovery water exceeds a threshold in the waste heat recovery system 100 of the second embodiment.
[0101] If the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds a threshold, the temperature controller 206 switches the flow path switching three-way valves 203 and 204. The inlet-side flow path switching three-way valve 203 opens the flow path from the auxiliary cooling equipment 3a to the intermediate-stage waste heat recovery heat exchanger 201 and closes the flow path from the heat treatment equipment 4 to the intermediate-stage waste heat recovery heat exchanger 201. The outlet-side flow path switching three-way valve 204 opens the flow path from the discharge-stage waste heat recovery heat exchanger 202 to the auxiliary cooling equipment 3a and closes the flow path from the discharge-stage waste heat recovery heat exchanger 202 to the heat treatment equipment 4.
[0102] As a result, the waste heat recovery water that exchanges heat in heat exchangers 201 and 202 flows in from the auxiliary cooling equipment 3a, as shown by the dashed line, through the waste heat recovery liquid inlet pipe 113 and waste heat recovery liquid pipe 211 from the auxiliary cooling equipment, exchanges heat with compressed air in the heat exchangers 201 and 202 for waste heat recovery, and then flows out towards the auxiliary cooling equipment 3a from the waste heat recovery liquid outlet pipe 114 to the auxiliary cooling equipment. The waste heat recovery liquid that has exchanged heat in heat exchangers 201 and 202 is sent to the auxiliary cooling equipment 3a to be cooled without passing through the heat treatment equipment 4, and then continues to cool the high-temperature compressed air in the intermediate stage waste heat recovery heat exchanger 201 and the discharge stage waste heat recovery heat exchanger 202 within the waste heat recovery machine 2.
[0103] Furthermore, if the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds a threshold, the temperature controller 206 opens the temperature control valve 208, causing the waste heat recovery water from the heat treatment equipment 4 to flow in from the heat treatment equipment 4 on the waste heat utilization side, as shown by the dashed line, through the waste heat recovery liquid piping 211, and via the waste heat recovery liquid circulation piping 210, and then flow out towards the heat treatment equipment 4 on the waste heat utilization side without passing through the heat exchangers 201 and 202 for waste heat recovery.
[0104] When the temperature of the waste heat recovery water exceeds the threshold, the flow path of the cooling water flowing in from cooling equipment 3 is the same as the normal flow path in Figure 7, as shown by the dotted line.
[0105] According to the second embodiment, if the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds a threshold, the temperature controller 206 switches the flow path switching three-way valves 203 and 204 and operates the auxiliary cooling pump 207a, so that the cooling water from the auxiliary cooling equipment 3a is used for heat exchange with compressed air in the waste heat recovery heat exchangers 201 and 202, thereby preventing the temperature of the waste heat recovery water from rising and preventing damage to the waste heat recovery heat exchangers.
[0106] Furthermore, according to the configuration of the second embodiment, if the temperature of the waste heat recovery water exceeds a predetermined threshold, the waste heat recovery water is passed through an auxiliary cooling system 3a independent of the cooling system 3 of the air compressor 1. This allows the waste heat recovery water to be cooled without changing its water quality by mixing it with the cooling water that flows through the cooling system 3.
[0107] For example, the waste heat recovery water supplied to some heat treatment equipment, such as boilers, may require the use of water that has undergone water softening or other water quality adjustments. On the other hand, cooling water generally uses economical industrial water that is not of relatively high quality. Therefore, there may be cases where mixing cooling water and waste heat recovery water is undesirable.
[0108] Figure 9 is a schematic diagram showing a modified example of the general configuration of the waste heat recovery system of the second embodiment. In Figure 9, components identical to those in the second embodiment in Figure 6 are denoted by the same reference numerals, and their descriptions are omitted.
[0109] The waste heat recovery system 100 in Figure 9 is equipped with a waste heat recovery liquid inlet valve 212 and an auxiliary cooling inlet valve 213 for the waste heat recovery liquid, instead of the inlet-side flow path switching three-way valve 203 in Figure 6. Furthermore, the waste heat recovery system 100 in Figure 9 is equipped with a waste heat recovery liquid outlet valve 214 and an auxiliary cooling outlet valve 215 for the waste heat recovery liquid, instead of the outlet-side flow path switching three-way valve 204 in Figure 6. In other words, instead of the two three-way valves on the inlet and outlet sides in Figure 6, two two-way valves are provided on each side.
[0110] The waste heat recovery liquid inlet valve 212 is located on the waste heat recovery liquid piping 211 upstream of the heat exchanger 201 for intermediate stage waste heat recovery, and controls the inflow of waste heat recovery liquid from the outlet side of the heat treatment equipment 4 into the waste heat recovery liquid piping 211.
[0111] The waste heat recovery liquid outlet valve 214 is located on the waste heat recovery liquid piping 211 downstream of the heat exchanger 202 for discharge stage waste heat recovery, and controls the outflow of waste heat recovery liquid from the waste heat recovery liquid piping 211 to the heat treatment equipment 4.
[0112] The auxiliary cooling inlet valve 213 for the waste heat recovery liquid is installed between the waste heat recovery liquid inlet branch pipe 115, which branches off from the waste heat recovery liquid piping 211 upstream of the heat exchanger 201 for intermediate stage waste heat recovery, and the waste heat recovery liquid inlet pipe 113 from the auxiliary cooling equipment, and controls the inflow of waste heat recovery liquid from the auxiliary cooling equipment 3a to the waste heat recovery liquid piping 211.
[0113] The auxiliary cooling outlet valve 215 for the waste heat recovery liquid is installed between the outlet-side branch pipe 116 for the waste heat recovery liquid, which branches off from the waste heat recovery liquid piping 211 downstream of the heat exchanger 202 for discharge-stage waste heat recovery, and the waste heat recovery liquid outlet pipe 114 to the auxiliary cooling equipment, and controls the outflow of waste heat recovery liquid from the waste heat recovery liquid piping 211 to the auxiliary cooling equipment 3a.
[0114] Next, the flow paths of the waste heat recovery water and cooling water in a modified example of the waste heat recovery system 100 of the second embodiment will be described.
[0115] Figure 10 shows an example of the flow path of waste heat recovery water and cooling water in the waste heat recovery system 100 of the second embodiment.
[0116] The auxiliary cooling inlet valve 213 and auxiliary cooling outlet valve 215 are closed, while the waste heat recovery liquid inlet valve 212 and waste heat recovery liquid outlet valve 214 are open.
[0117] As shown by the dashed line, the waste heat recovery water flows in from the heat treatment facility 4 on the waste heat utilization side by operating the circulation pump 207, flows through the waste heat recovery liquid piping 211, has its temperature measured by the temperature sensor 205, exchanges heat with compressed air in the waste heat recovery heat exchangers 201 and 202, and then flows out towards the heat treatment facility 4 on the waste heat utilization side.
[0118] As shown by the dotted line, the cooling water flows in from the cooling equipment 3, branches off from the cooling liquid piping 106 into the first cooling liquid piping 106a, the second cooling liquid piping 106b, and the second cooling liquid piping c, exchanges heat with compressed air in the intercooler 103 and aftercooler 104, or exchanges heat with lubricating oil in the oil cooler 105, before rejoining and flowing out towards the cooling equipment 3.
[0119] The auxiliary cooling pump 207a is stopped, and the auxiliary cooling equipment 3a, the waste heat recovery liquid inlet pipe 113 from the auxiliary cooling equipment, and the waste heat recovery liquid outlet pipe 114 to the auxiliary cooling equipment are not used.
[0120] If the user does not use the heat treatment equipment 4 to exchange heat between the waste heat recovery water and the chilled water, the waste heat recovery water that has exchanged heat with compressed air in the waste heat recovery heat exchangers 201 and 202 will not be cooled by the heat treatment equipment 4, causing the temperature of the waste heat recovery water circulating in the waste heat recovery liquid piping 211 to rise. If the temperature of the waste heat recovery water exceeds its boiling point, the internal pressure of the waste heat recovery liquid piping 211 will increase, potentially damaging the waste heat recovery heat exchangers 201 and 202.
[0121] Therefore, in this embodiment, if the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds a preset threshold, the temperature controller 206 opens the auxiliary cooling inlet valve 213 and the auxiliary cooling outlet valve 215, closes the waste heat recovery liquid inlet valve 212 and the waste heat recovery liquid outlet valve 214, operates the auxiliary cooling pump 207a, and opens the temperature control valve 208, thereby switching the flow paths of the waste heat recovery water and the cooling water.
[0122] Figure 11 shows an example of the flow path between waste heat recovery water and cooling water when the temperature of the waste heat recovery water exceeds a threshold in a modified example of the waste heat recovery system 100 of the second embodiment.
[0123] If the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds a threshold, the temperature controller 206 opens the auxiliary cooling inlet valve 213 and the auxiliary cooling outlet valve 215, closes the waste heat recovery liquid inlet valve 212 and the waste heat recovery liquid outlet valve 214, and operates the auxiliary cooling pump 207a.
[0124] As a result, the waste heat recovery water that exchanges heat in heat exchangers 201 and 202 flows in from the auxiliary cooling equipment 3a, as shown by the dashed line, through the waste heat recovery liquid inlet pipe 113 from the auxiliary cooling equipment, the waste heat recovery liquid inlet side branch pipe 115, and the waste heat recovery liquid pipe 211, exchanges heat with compressed air in the heat exchangers 201 and 202 for waste heat recovery, and then flows out towards the auxiliary cooling equipment 3a through the waste heat recovery liquid outlet side branch pipe 116 and the waste heat recovery liquid outlet pipe 114 to the auxiliary cooling equipment. The waste heat recovery liquid that has exchanged heat in heat exchangers 201 and 202 is sent to the auxiliary cooling equipment 3a to be cooled without passing through the heat treatment equipment 4, and then continues to cool the high-temperature compressed air in the intermediate stage waste heat recovery heat exchanger 201 and the discharge stage waste heat recovery heat exchanger 202 within the waste heat recovery machine 2.
[0125] Furthermore, if the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds a threshold, the temperature controller 206 opens the temperature control valve 208, causing the waste heat recovery water from the heat treatment equipment 4 to flow in from the heat treatment equipment 4 on the waste heat utilization side, as shown by the dashed line, through the waste heat recovery liquid piping 211, and via the waste heat recovery liquid circulation piping 210, and then flow out towards the heat treatment equipment 4 on the waste heat utilization side without passing through the heat exchangers 201 and 202 for waste heat recovery.
[0126] When the temperature of the waste heat recovery water exceeds the threshold, the flow path of the cooling water flowing in from cooling equipment 3 is the same as the normal flow path in Figure 10, as shown by the dotted line.
[0127] According to a modified version of the second embodiment, if the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds a threshold, the auxiliary cooling inlet valve 213 and the auxiliary cooling outlet valve 215 are opened, the waste heat recovery liquid inlet valve 212 and the waste heat recovery liquid outlet valve 214 are closed, and the auxiliary cooling pump 207a is operated. This allows the cooling water from the auxiliary cooling equipment 3a to be used for heat exchange with compressed air in the waste heat recovery heat exchangers 201 and 202, thereby preventing the temperature of the waste heat recovery water from rising and preventing damage to the waste heat recovery heat exchangers.
[0128] Furthermore, according to the configuration of the second embodiment, if the temperature of the waste heat recovery water exceeds a predetermined threshold, the waste heat recovery water is passed through an auxiliary cooling system 3a independent of the cooling system 3 of the air compressor 1. This allows the waste heat recovery water to be cooled without changing its water quality by mixing it with the cooling water that flows through the cooling system 3.
[0129] Furthermore, according to a modification of the second embodiment, a two-way valve with a simple internal structure, high maintainability, and low cost is used for switching the distribution route, thus reducing manufacturing and maintenance costs compared to using a three-way valve.
[0130] Figure 12 is a flowchart showing an example of the control performed by the temperature controller 206 in the waste heat recovery system 100 of the second embodiment.
[0131] In Figure 12, it is assumed that at the start of processing, the waste heat recovery water and cooling water are flowing through the normal distribution routes shown in Figure 7 or Figure 10.
[0132] When the air compressor 1 starts operating, power is supplied to the temperature controller 206 and control begins. In S501, the temperature controller 206 obtains the temperature of the waste heat recovery water in the waste heat recovery liquid piping 211, which is measured by the temperature sensor 205.
[0133] In S502, the temperature controller 206 determines whether the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds 95°C. If the temperature of the waste heat recovery water exceeds 95°C in S502, the process proceeds to S503. On the other hand, if the temperature of the waste heat recovery water does not exceed 95°C in S502, the process proceeds to S515, where the system waits in a normal state for a preset time before returning to S501.
[0134] In S503, the temperature controller 206 switches the inlet and outlet valves. In the second embodiment, the inlet-side flow path switching three-way valve 203 is switched, and the coolant from the coolant pipe 106 flows into the waste heat recovery liquid pipe 211 using the branch pipe 110 on the coolant inlet side. At the same time, the temperature controller 206 switches the outlet-side flow path switching three-way valve 204, and the coolant that has passed through the heat exchanger 201 for intermediate stage waste heat recovery and the heat exchanger 202 for discharge stage waste heat recovery flows into the branch pipe 111 on the coolant outlet side. In a modified version of the second embodiment, the auxiliary cooling inlet valve 213 and the auxiliary cooling outlet valve 215 are opened, and the waste heat recovery liquid inlet valve 212 and the waste heat recovery liquid outlet valve 214 are closed.
[0135] In S504, the temperature controller 206 opens the temperature control valve 208, thereby opening the waste heat recovery liquid circulation pipe 210 and enabling the circulation of waste heat recovery water from the heat treatment equipment 4.
[0136] In S505, the auxiliary cooling pump 207a is operated to cause waste heat recovery water from the auxiliary cooling equipment 3a to flow into the waste heat recovery liquid inlet pipe 113 from the auxiliary cooling equipment.
[0137] In S506, after executing S503 and S504, the system waits for a predetermined time. The waiting time is set to a time sufficient for the temperature of the waste heat recovery water, which has exceeded 95°C, to decrease.
[0138] In S507, the temperature controller 206 reacquires the temperature of the waste heat recovery water in the waste heat recovery liquid piping 211, which was measured by the temperature sensor 205.
[0139] In S508, the temperature controller 206 determines whether the temperature of the waste heat recovery water measured by the temperature sensor 205 exceeds 95°C. If the temperature of the waste heat recovery water exceeds 95°C in S508, the process proceeds to S510.
[0140] In S510, the temperature controller 206 outputs a serious fault signal. In S511, the temperature controller 206 stops the operation of the circulation pump 207, auxiliary cooling pump 207a, air compressor 1, and waste heat recovery unit 2, which are installed in the waste heat recovery liquid piping 211, and terminates the process.
[0141] On the other hand, if the temperature of the waste heat recovery water does not exceed 95°C in S508, the process proceeds to S509. In S509, it is determined whether the temperature of the waste heat recovery water obtained in S507 is below 40°C. If the temperature of the waste heat recovery water is not below 40°C in S509, the process returns to S506 and waits for a predetermined time.
[0142] On the other hand, if the temperature of the waste heat recovery water is below 40°C in S509, the process proceeds to S512.
[0143] In S512, the temperature controller 206 switches the inlet and outlet valves. In the second embodiment, the inlet-side flow path switching three-way valve 203 is switched to send the waste heat recovery water from the heat treatment equipment 4 to the waste heat recovery heat exchangers 201 and 202. At the same time, the temperature controller 206 switches the outlet-side flow path switching three-way valve 204 to send the waste heat recovery water from the waste heat recovery heat exchangers 201 and 202 to the heat treatment equipment 4. In a modified version of the second embodiment, the auxiliary cooling inlet valve 213 and auxiliary cooling outlet valve 215 are closed, and the waste heat recovery liquid inlet valve 212 and waste heat recovery liquid outlet valve 214 are opened.
[0144] In S513, the temperature controller 206 closes the temperature control valve 208, thereby closing the waste heat recovery liquid circulation pipe 210. In S514, the auxiliary cooling pump 207a is stopped. In S515, the system waits in a normal state for a preset time and returns to S501.
[0145] Furthermore, while the air compressor 1 in the embodiment is specifically applicable to a screw compressor, the present invention is not limited thereto. That is, although the embodiment uses a screw rotor for the compressor body 101, 102, the invention is not limited thereto, and various types of compression means can be used, such as turbo type (centrifugal, axial flow, etc.) or positive displacement type (scroll, reciprocating, claw, etc.).
[0146] Furthermore, although a single-screw rotor is used in this embodiment, a twin or triple-screw rotor may also be used.
[0147] Furthermore, although the number of stages of the compressor bodies 101 and 102 in the embodiment is two, it is not limited to this, and may be one stage or three or more stages.
[0148] Furthermore, although the air compressor 1 in this embodiment is an oil-free screw compressor, it is not limited to this, and may be a liquid-supplied air compressor in which oil or water is injected into the compression chamber. Also, although the gas to be compressed is described as air, it is not limited to this, and may be nitrogen or the like.
[0149] Furthermore, the temperature threshold of the waste heat recovery water used in the control of the embodiment is not limited to this.
[0150] Furthermore, in this embodiment, the cooling water whose temperature has risen is cooled by heat exchange with the atmosphere in the cooling equipment 3, but it is not limited to this, and it is also possible to recover and utilize the heat from the cooling water whose temperature has risen.
[0151] Furthermore, although the embodiment described the air compressor 1 as a water-cooled type in which the compressor body, intercooler, aftercooler, and oil cooler are cooled by cooling water, it is not limited to this, and may also be an air-cooled type equipped with an air-cooled intercooler, aftercooler, oil cooler, etc. that are cooled by an air-cooled intercooler, aftercooler, oil cooler, etc. that are cooled by an air-cooled fan that draws in outside air and the cooling air generated by the fan.
[0152] Furthermore, it is possible to replace parts of the configuration of one embodiment with parts of the configuration of another embodiment, and it is also possible to add parts of the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with parts of other configurations. [Explanation of Symbols]
[0153] 1: Air compressor, 2: Waste heat recovery unit, 3: Cooling equipment, 3a: Auxiliary cooling equipment, 4: Heat treatment equipment, 100: Waste heat recovery system, 101: First stage compressor body, 102: Second stage compressor body, 103: Heat exchanger for cooling (intercooler), 104: Heat exchanger for cooling (aftercooler), 105: Oil cooler, 106: Coolant piping, 107: Ventilation piping, 108: Air piping, 109: Check valve, 110: Branch piping on the coolant inlet side, 111: Branch piping on the coolant outlet side, 113: Waste heat recovery liquid inlet piping from auxiliary cooling equipment, 114: Waste heat recovery liquid outlet piping to auxiliary cooling equipment, 115: 116: Inlet branch piping for waste heat recovery liquid, 201: Outlet branch piping for waste heat recovery liquid, 202: Heat exchanger for intermediate stage waste heat recovery, 203: Three-way valve for switching flow path on the inlet side, 204: Three-way valve for switching flow path on the outlet side, 205: Temperature sensor, 206: Temperature controller, 207: Circulation pump, 207a: Auxiliary cooling pump, 208: Temperature control valve, 209: Flow meter, 210: Waste heat recovery liquid circulation piping, 211: Waste heat recovery liquid piping, 212: Inlet valve for waste heat recovery liquid, 213: Inlet valve for auxiliary cooling of waste heat recovery liquid, 214: Outlet valve for waste heat recovery liquid, 215: Outlet valve for auxiliary cooling of waste heat recovery liquid
Claims
1. In a waste heat recovery system comprising a fluid machine body through which a fluid flows and a waste heat recovery machine that recovers waste heat from the fluid, The fluid machine body is A cooling heat exchanger that exchanges heat between the coolant and the fluid, The system includes a coolant pipe through which the coolant flows, The aforementioned waste heat recovery machine is A heat exchanger for waste heat recovery that exchanges heat between the waste heat recovery liquid and the aforementioned fluid, The waste heat recovery liquid piping through which the aforementioned waste heat recovery liquid flows, A first bypass channel connects the upstream side of the waste heat recovery heat exchanger in the waste heat recovery liquid piping to the outlet side of the auxiliary cooling equipment that is not connected to the cooling liquid piping of the fluid machine body, A second bypass channel connects the downstream side of the waste heat recovery liquid piping to the inlet side of the auxiliary cooling equipment, A first valve for opening and closing the first bypass passage, A second valve for opening and closing the second bypass passage, The system comprises a control unit that controls the first valve and the second valve, The control unit controls the first valve and the second valve to open the first bypass channel and the second bypass channel when the temperature of the waste heat recovery liquid exceeds a threshold, in a waste heat recovery system.
2. In the waste heat recovery system according to claim 1, A waste heat recovery system comprising a waste heat recovery liquid heat exchanger provided downstream of the second valve and upstream of the first valve in the waste heat recovery liquid piping, which exchanges heat between the waste heat recovery liquid and the refrigerant.
3. In the waste heat recovery system according to claim 2, The control unit controls the first valve and the second valve to close the first bypass channel and the second bypass channel when the temperature of the waste heat recovery liquid falls below a second threshold, in a waste heat recovery system.
4. In the waste heat recovery system according to claim 2, The first valve consists of a first three-way valve that switches between the flow path from the waste heat recovery liquid piping to the waste heat recovery heat exchanger and the flow path from the auxiliary cooling equipment to the waste heat recovery heat exchanger. The second valve consists of a second three-way valve that switches between the flow path from the waste heat recovery heat exchanger to the waste heat recovery liquid piping and the flow path from the waste heat recovery heat exchanger to the auxiliary cooling equipment. The control unit is a waste heat recovery system that opens the first bypass channel and the second bypass channel by switching the first three-way valve and the second three-way valve.
5. In the waste heat recovery system according to claim 2, The first valve comprises a first two-way valve that opens and closes the flow path from the waste heat recovery liquid piping to the waste heat recovery heat exchanger, and a second two-way valve that opens and closes the flow path from the auxiliary cooling equipment to the waste heat recovery heat exchanger. The second valve comprises a third two-way valve that opens and closes the flow path from the waste heat recovery heat exchanger to the waste heat recovery liquid piping, and a fourth two-way valve that opens and closes the flow path from the waste heat recovery heat exchanger to the auxiliary cooling equipment. A waste heat recovery system in which the control unit closes the first two-way valve and the third two-way valve and opens the second two-way valve and the fourth two-way valve, thereby opening the first bypass flow path and the second bypass flow path.
6. A waste heat recovery unit that recovers waste heat from a fluid discharged from a fluid machine body, which includes a cooling heat exchanger that exchanges heat between a cooling liquid and a fluid, and a cooling liquid piping through which the cooling liquid flows, A heat exchanger for waste heat recovery that exchanges heat between the waste heat recovery liquid and the aforementioned fluid, The waste heat recovery liquid piping through which the aforementioned waste heat recovery liquid flows, A first bypass channel connects the upstream side of the waste heat recovery heat exchanger in the waste heat recovery liquid piping to the outlet side of the auxiliary cooling equipment that is not connected to the cooling liquid piping of the fluid machine body, A second bypass channel connects the downstream side of the waste heat recovery liquid piping to the inlet side of the auxiliary cooling equipment, A first valve for opening and closing the first bypass passage, A second valve for opening and closing the second bypass passage, The system comprises a control unit that controls the first valve and the second valve, The control unit controls the first valve and the second valve to open the first bypass channel and the second bypass channel when the temperature of the waste heat recovery liquid exceeds a threshold, thereby enabling waste heat recovery.
7. In the waste heat recovery unit according to claim 6, A waste heat recovery unit comprising a waste heat recovery liquid heat exchanger provided downstream of the second valve and upstream of the first valve in the waste heat recovery liquid piping, which exchanges heat between the waste heat recovery liquid and the refrigerant.
8. In the waste heat recovery unit according to claim 7, The control unit controls the first valve and the second valve to close the first bypass channel and the second bypass channel when the temperature of the waste heat recovery liquid falls below a second threshold.
9. In the waste heat recovery unit according to claim 7, The first valve consists of a first three-way valve that switches between the flow path from the waste heat recovery liquid piping to the waste heat recovery heat exchanger and the flow path from the auxiliary cooling equipment to the waste heat recovery heat exchanger. The second valve consists of a second three-way valve that switches between the flow path from the waste heat recovery heat exchanger to the waste heat recovery liquid piping and the flow path from the waste heat recovery heat exchanger to the auxiliary cooling equipment. The control unit is a waste heat recovery unit that opens the first bypass channel and the second bypass channel by switching the first three-way valve and the second three-way valve.
10. In the waste heat recovery unit according to claim 7, The first valve comprises a first two-way valve that opens and closes the flow path from the waste heat recovery liquid piping to the waste heat recovery heat exchanger, and a second two-way valve that opens and closes the flow path from the auxiliary cooling equipment to the waste heat recovery heat exchanger. The second valve comprises a third two-way valve that opens and closes the flow path from the waste heat recovery heat exchanger to the waste heat recovery liquid piping, and a fourth two-way valve that opens and closes the flow path from the waste heat recovery heat exchanger to the auxiliary cooling equipment. The control unit opens the first and second bypass channels by closing the first two-way valve and the third two-way valve and opening the second and fourth two-way valves, thereby providing a waste heat recovery unit.
11. In a waste heat recovery system comprising a fluid machine body through which a fluid flows and a waste heat recovery machine that recovers waste heat from the fluid, The fluid machine body is A cooling heat exchanger that exchanges heat between the coolant and the fluid, The system includes a coolant pipe through which the coolant flows, The aforementioned waste heat recovery machine is A heat exchanger for waste heat recovery that exchanges heat between the waste heat recovery liquid and the aforementioned fluid, The waste heat recovery liquid piping through which the aforementioned waste heat recovery liquid flows, A first bypass channel connects the upstream side of the waste heat recovery heat exchanger in the waste heat recovery liquid piping to the outlet side of the auxiliary cooling equipment that is not connected to the cooling liquid piping of the fluid machine body, A second bypass channel connects the downstream side of the waste heat recovery liquid piping to the inlet side of the auxiliary cooling equipment, A first valve for opening and closing the first bypass passage, A second valve for opening and closing the second bypass passage, The system comprises a control unit that controls the first valve and the second valve, A waste heat recovery method wherein the control unit controls the first valve and the second valve to open the first bypass channel and the second bypass channel when the temperature of the waste heat recovery liquid exceeds a threshold.
12. In the waste heat recovery method according to claim 11, The fluid machine body is A waste heat recovery method comprising a waste heat recovery liquid heat exchanger provided downstream of the second valve and upstream of the first valve in the waste heat recovery liquid piping, which exchanges heat between the waste heat recovery liquid and the refrigerant.
13. In the waste heat recovery method according to claim 12, A waste heat recovery method comprising the control unit controlling the first valve and the second valve to close the first bypass channel and the second bypass channel when the temperature of the waste heat recovery liquid falls below a second threshold.
14. In the waste heat recovery method according to claim 12, The first valve consists of a first three-way valve that switches between the flow path from the waste heat recovery liquid piping to the waste heat recovery heat exchanger and the flow path from the auxiliary cooling equipment to the waste heat recovery heat exchanger. The second valve consists of a second three-way valve that switches between the flow path from the waste heat recovery heat exchanger to the waste heat recovery liquid piping and the flow path from the waste heat recovery heat exchanger to the auxiliary cooling equipment. The control unit is a waste heat recovery method that opens the first bypass flow path and the second bypass flow path by switching the first three-way valve and the second three-way valve.
15. In the waste heat recovery method according to claim 12, The first valve comprises a first two-way valve that opens and closes the flow path from the waste heat recovery liquid piping to the waste heat recovery heat exchanger, and a second two-way valve that opens and closes the flow path from the auxiliary cooling equipment to the waste heat recovery heat exchanger. The second valve comprises a third two-way valve that opens and closes the flow path from the waste heat recovery heat exchanger to the waste heat recovery liquid piping, and a fourth two-way valve that opens and closes the flow path from the waste heat recovery heat exchanger to the auxiliary cooling equipment. A waste heat recovery method in which the control unit closes the first two-way valve and the third two-way valve and opens the second two-way valve and the fourth two-way valve, thereby opening the first bypass flow path and the second bypass flow path.