EP4656878A1

EP4656878A1 - Exhaust heat recovery system

Info

Publication number: EP4656878A1
Application number: EP25165705.2A
Authority: EP
Inventors: Yuto SHIMIZU; Masakazu Hase; Takashi Nakajima
Original assignee: Hitachi Industrial Equipment Systems Co Ltd
Current assignee: Hitachi Industrial Equipment Systems Co Ltd
Priority date: 2024-05-30
Filing date: 2025-03-24
Publication date: 2025-12-03
Also published as: US20250369609A1; JP2025180798A; CN121048421A

Abstract

An exhaust heat recovery system comprises: a plurality of gas compressors (3); an exhaust heat recovery equipment (2); and a controller (1), wherein an exhaust heat recovery path connects the plurality of gas compressors (3) and the exhaust heat recovery equipment (2), and the plurality of gas compressors (3) can select whether or not to use the exhaust heat recovery path based on instructions from the controller (1), the controller (1) compares a set required water temperature with a supply water temperature, which is the temperature of the water supplied from the exhaust heat recovery equipment (2) to the outside, and at least one of the plurality of gas compressors (3) is instructed to use the exhaust heat recovery path when the supply water temperature is lower than the required water temperature.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an exhaust heat recovery system.

2. Description of Related Art

The effective use of thermal energy has become increasingly important in recent years due to energy conservation and environmental issues.
Patent Document 1 discloses a heat recovery compressor and a centralized control device for the purpose of efficiently using energy.

Citation List

Patent Document

[Patent Document 1] JP 2018-168724 A

SUMMARY OF THE INVENTION

In the system of Patent Document 1, exhaust heat is not recovered from some gas compressors, and there is room for further improvement from the viewpoint of effective use of thermal energy contained in the exhaust heat. Further, the configuration described in Patent Document 1 assumes that a part of the gas compressor is not connected to the exhaust heat recovery device. Therefore, the situation in which all gas compressors are connected to the waste heat recovery device is not considered.
Therefore, an object of the present invention is to effectively utilize thermal energy in a system in which all gas compressors are connected to a exhaust heat recovery device.
An example of the means for solving the above problem is as follows.
An exhaust heat recovery system comprising: a plurality of gas compressors; a exhaust heat recovery equipment; and a controller, wherein further comprising a exhaust heat recovery path connecting the plurality of gas compressors and the exhaust heat recovery equipment, and the plurality of gas compressors can select whether or not to use the exhaust heat recovery path based on instructions from the controller,
the controller compares the set required water temperature with the supply water temperature, which is the temperature of the water supplied from the exhaust heat recovery equipment to the outside, and at least one of the plurality of gas compressors is instructed to use the exhaust heat recovery path when the supply water temperature is lower than the required water temperature.
According to the present invention, thermal energy can be efficiently recovered by recovering exhaust heat from all gas compressors constituting the system.
Further composition and effects of the present invention will become apparent through the entire text of the specification below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example of a system configuration diagram of one embodiment of the present invention.
FIG. 2 is a flowchart of one embodiment of the present invention.
FIG. 3 is a flowchart explaining details of the process in step 107 of FIG. 2.
FIG. 4 is a flowchart explaining details of the process in step 106 of FIG. 2.
FIG. 5 is an example of a system configuration diagram of one embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Embodiment 1

The exhaust heat recovery system according to the present invention includes a gas compressor that generates compressed gas, a exhaust heat recovery device that recovers heat generated in the process of generating compressed gas, and a control device that oversees them. And carrying out operation in accordance with the parameters for operation.
In this specification, the gas compressor has an electric motor that drives the compressor body. Then, a gas compressor that mechanically controls loading (making compressed air) and unloading (waiting in non-making air operation) by driving an electric motor is called a constant speed machine.
In a gas compressor, a gas compressor that controls the rotational speed of an electric motor by changing the operating frequency by an inverter is called a variable speed machine. In addition, when the variable speed machine operates the rotational speed of the electric motor at full speed according to the command of the control device or control device, it is called full-speed operation.
According to the operating parameters, the gas compressor first operates a frequency-controlled variable speed machine, then a full-speed operation machine, and finally a constant-speed machine. And stopping in the same order.
In the embodiment described below, as an example, a exhaust heat recovery system including four gas compressors, one exhaust heat recovery device, and one control device that controls them will be described.
FIG. 1 is a block diagram showing the configuration of the present invention. The exhaust heat recovery equipment 2 is connected to the gas compressor 3 via an output piping 6 that supplies the heat transfer fluid to the gas compressor 3 and a return piping 7 that captures the heat transfer fluid from the gas compressor 3. Heat is exchanged between the circulating water taken in from the input piping 10 and the heat transfer fluid. The hot water obtained by the heat exchange is supplied via the output piping 11. The controller 1 includes a signal line 9 for performing RS 485 communication with the exhaust heat recovery equipment 2 and a signal line 8 for performing RS 485 communication with the gas compressor 3. And from the operating state and temperature of the gas compressor 3, the controller 1 takes charge in control of this invention and control each device according to the program stored inside. The partition solenoid valve 4 opens and closes according to the command of the exhaust heat recovery equipment 2 to prevent heat transfer fluid from flowing to the gas compressor that is not subject to exhaust heat recovery. The check valve 5 prevents the heat transfer fluid returning to the exhaust heat recovery equipment 2 from flowing back to the gas compressor 3. 20 is the air tank that stores the compressed air generated by the gas compressor. In addition, in FIG. 1, the controller 1 is separately disposed from the exhaust heat recovery equipment 2, but the case where it is configured as an integral part is also within the scope of the disclosure of this embodiment.
In the present invention, a exhaust heat recovery path is constructed between the gas compressor 3 and the exhaust heat recovery equipment 2 by the output piping 6 and the return piping 7. The exhaust heat at this time means the heat generated in the gas compressor 3 due to the operation of the gas compressor 3. Therefore, by recovering the heat generated in the gas compressor 3 by this exhaust heat recovery path, energy efficiency is improved.
At the same time, the recovery of this heat also functions as a cooling loop of the gas compressor 3. Therefore, in some cases, it is possible to reduce the scale of the heat dissipation mechanism to be provided in the gas compressor 3, and in such a case, it also contributes to reducing the cost of the gas compressor 3 itself.
The gas compressor 3 in the present invention is configured so that it is possible to select whether or not to use a exhaust heat recovery path. This selection can be realized based on instructions from the controller 1, for example, by opening and closing a valve provided in the exhaust heat recovery path in the gas compressor 3.
In addition, the case where a valve is provided between the gas compressor 3 and the exhaust heat recovery equipment 2, and the use or non-use of the exhaust heat recovery path can be selected by opening and closing the valve is also included in the scope of the present invention.
In the configuration of FIG. 1, first, for example, the controller 1 compares the set required water temperature with the supply water temperature, which is the temperature of the supply water supplied from the exhaust heat recovery equipment 2 to the outside by the output piping 11. When the supply water temperature is lower than the required water temperature, a exhaust heat recovery system can be realized by instructing at least one of the plurality of gas compressors to use the exhaust heat recovery path.
FIG. 5 is an example in which the controller 1 performs whether or not to use the exhaust heat recovery path by controlling the opening and closing of the partition solenoid valve 4.
By means of the signal line 30, the controller 1 controls the opening and closing of the partition solenoid valve 4 corresponding to the gas compressor to be indicated, and as a result, at least one of the plurality of gas compressors is instructed to use the exhaust heat recovery path. Thus, exhaust heat recovery system can be realized.
As shown in FIG. 1 and FIG. 5, for example, in the present invention, specification, the expression "the gas compressor can be selected based on instructions from the controller whether or not to use the exhaust heat recovery path", or, various expressions such as "instructing at least one of the gas compressor to use the exhaust heat recovery path", even if it is realized by instructing the gas compressor itself, or by opening and closing the valve of the exhaust heat recovery path in the middle, the technical concept is substantially the same. For this reason, as an expression that includes both instructions to the gas compressor itself and instructions to valves and the like in any case, for example, the expression "the gas compressor can be selected based on instructions from the controller whether or not to use the exhaust heat recovery path", or the expression "at least one of the gas compressor is instructed to use the exhaust heat recovery path" is used.
FIG. 2 is a flowchart illustrating the operation of the present invention. The operation based on the flowchart is as follows.
Step 101 is a process for determining the presence or absence of the gas compressor 3 in a stop according to the internal program of the controller 1. Specifically, the controller 1 performs RS 485 communication with the gas compressor 3 and acquires the operating state. If there is a stopped gas compressor 3, the process proceeds to step 102. If there is no stopped gas compressor, the process proceeds to step 103.
Step 102 is a process of stopping the exhaust heat recovery effective from the exhaust heat recovery equipment 2 with respect to the stopped gas compressor 3. Specifically, by closing the partition solenoid valve 4 corresponding to the stopped gas compressor 3 by the command of the exhaust heat recovery equipment 2, the supply of heat transfer fluid supplied from the exhaust heat recovery equipment 2 to the gas compressor 3 via the output piping 6 is cut off.
In the present invention, the partition solenoid valve 4 includes both cases of being incorporated into the gas compressor 3 or being placed separately.
Step 103 is a process for determining whether or not exhaust heat recovery is necessary according to the internal program of the exhaust heat recovery equipment 2. Specifically, the user can set the necessity of exhaust heat recovery in the operation of the exhaust heat recovery equipment 2, and the setting value is recorded in the internal memory of the exhaust heat recovery equipment 2. If it is determined that exhaust heat recovery is necessary, the process proceeds to step 104. If it is determined that exhaust heat recovery is not necessary, the process is ended.
Step 104 is a process for determining whether or not the required amount of heat can be recovered by exhaust heat recovery according to the internal program of the exhaust heat recovery equipment 2. Specifically, in the operation of the exhaust heat recovery equipment 2, the user can set the required water temperature, and the setting value is recorded in the internal memory of the exhaust heat recovery equipment 2. The exhaust heat recovery equipment 2 acquires the temperature of the water temperature from the internal temperature sensor, and determines by comparing it with the required water temperature set by the user. If it is determined that the water temperature required by the user is satisfied, the process proceeds to step 105. If it is determined that the water temperature is not satisfied, the process proceeds to step 107.
Step 105 is a process for determining whether or not the amount of heat being recovered is excessive for the water temperature required by the user according to the internal program of the exhaust heat recovery equipment 2. Specifically, it is calculated and determined whether or not the water temperature obtained from the temperature sensor is rising by comparing it with the required water temperature set by the user. If it is determined that the amount of heat is excessive, the process proceeds to step 106. If it is determined that the amount of heat is not excessive, the process is ended.
Step 106 is a process for reducing the gas compressor 3 to be recovered with exhaust heat. Specifically, by closing the partition solenoid valve 4 corresponding to the gas compressor 3 to be recovered with the command of the exhaust heat recovery equipment 2, the supply of heat transfer fluid supplied from the exhaust heat recovery equipment 2 to the gas compressor 3 via the output piping 6 is cut off, and the process is ended.
Step 107 is a process of increasing the gas compressor 3 to be recovered from exhaust heat. Specifically, by opening the partition solenoid valve 4 corresponding to the gas compressor 3 to be recovered with the command of the exhaust heat recovery equipment 2, the heat transfer fluid is supplied from the exhaust heat recovery equipment 2 to the gas compressor 3 via the output piping 6, and the process is ended.
FIG. 3 is a flowchart showing a process for determining the priority of which of the plurality of gas compressors 3 to perform exhaust heat recovery for when the process of step 107 is executed in FIG. 2. This is an example of the details of the contents to be executed in step 107.
Step 201 is a process in which the controller 1 acquires the operating state of the gas compressor 3 via RS 485 communication via the signal line 8.
Step 202 refers to the operating state acquired in step 201 and is a process of determining loading or unloading according to the internal program of the controller 1. In the case of loading, proceed to step 203. In the case of unloading, proceed to step 210.
Step 203 is a process of determining whether or not there is a constant-speed gas compressor 3 according to the internal program of the controller 1. Specifically, in the operation of the controller 1, the user registers in advance whether the gas compressor 3 connected to the controller 1 is a constant speed or a variable speed, and the setting value is recorded in the internal memory of the controller 1. If there is a constant-speed gas compressor 3, the process proceeds to step 209. If not, proceed to step 204.
Step 204 is a process in which the controller 1 determines whether or not there is a variable speed gas compressor 3 and in full speed operation according to an internal program. Specifically, in the operation of the controller 1, the user registers in advance whether the gas compressor 3 connected to the controller 1 is frequency control or full-speed operation, and the setting value is recorded in the internal memory of the controller 1. If there is a gas compressor 3 in full-speed operation, the process proceeds to step 208. If not, proceed to step 205.
Step 205 refers to the operating state acquired in step 201 and determines whether or not there is a gas compressor 3 having a rotation speed less than the number of revolutions required for exhaust heat recovery according to an internal program. Specifically, the operating state of the inverter inside the gas compressor 3 is acquired by the controller 1 via RS 485 communication, and judge by comparing required water temperature recorded in the internal memory and the minimum operating frequency X [Hz] of the electric motor required for exhaust heat recovery calculated by the internal program. If there is a gas compressor 3 having an operating frequency of the electric motor less than X [Hz], the process proceeds to step 206. If not, proceed to step 211.
Step 206 refers to the operating state acquired in step 201 and is a process for determining whether or not there is a gas compressor 3 that exceeds the rotation speed required for exhaust heat recovery according to an internal program. The specific process is the same as in step 205. If there is a gas compressor 3 having an operating frequency of X [Hz] or higher of the electric motor, the process proceeds to step 207. If not, proceed to step 210.
In step 207, by processing steps 205 and 206, in the configuration of the gas compressor in the present invention, it can be seen that the gas compressor 3 having an electric motor operating frequency of less than X [Hz] and the gas compressor 3 having an electric motor operating frequency of X [Hz] or more are mixed. Since the gas compressor 3 having an operating frequency of the electric motor of less than X [Hz] is considered to have a small amount of heat that can be recovered even in a loaded state, and by removing such a gas compressor from the exhaust heat recovery target, it is a process to recover exhaust heat by giving priority to the gas compressor 3 having a large amount of heat.
In step 208, since the gas compressor 3 during full-speed operation has a larger amount of heat that can be recovered compared to the gas compressor 3 during rotation control, the gas compressor 3 other than the gas compressor 3 during full-speed operation is excluded from the exhaust heat recovery target.
In step 209, since the gas compressor 3 of the constant speed is stopped after the gas compressor 3 of the variable speed, the possible exhaust heat recovery time is long, and stable exhaust heat recovery is possible, by removing the gas compressor 3 other than the gas compressor 3 of the constant speed from the exhaust heat recovery, exhaust heat is recovered in priority from the gas compressor 3 of the constant speed machine.
In step 210, when the exhaust heat cannot be recovered and the water temperature required by the user cannot be satisfied, guidance of "less than the set temperature" is displayed on the display of the controller 1, and the process is ended.
Step 211 starts exhaust heat recovery by opening the partition solenoid valve 4 corresponding to the gas compressor 3 that stops at the end according to the internal program of the controller 1. The specific process is the same as in step 107. By setting the gas compressor 3 to stop at the end, it is possible to secure a long time for exhaust heat recovery.
FIG. 4 is a flowchart showing a process for determining the priority of stopping exhaust heat recovery for which of the plurality of gas compressors 3 when the process of step 106 is executed in FIG. 2. This is an example of the details of the contents of step 106 of FIG. 2.
Step 301 is a process in which the controller 1 acquires the operating state of the gas compressor 3 via RS 485 communication via the signal line 8.
Step 302 is a process of determining whether or not there is a gas compressor 3 under frequency control according to the internal program of the controller 1. The specific process is the same as in step 204. If there is a gas compressor 3 under frequency control, the process proceeds to step 303. If not, proceed to step 304.
Step 303 is a process in which the gas compressor 3 during frequency control is set to a target of priority exhaust heat recovery stopping, as the gas compressor 3 during frequency control is difficult to do stable exhaust heat recovering since the amount of heat varies depending on the operating conditions .
Step 304 stops exhaust heat recovery by closing the partition solenoid valve 4 corresponding to the gas compressor 3 that first stops according to the internal program of the controller 1. The specific process is the same as in step 106. By leaving the gas compressor 3 that stops at the end, it is possible to secure a long time for exhaust heat recovery.
In the above-described embodiment, the case where the operating state of the gas compressor is determined by loading/unloading or frequency is taken as an example, but for example, the present invention can be used in the same way in processing referring to the discharge temperature and discharge pressure. Specifically, in step 205, it can be replaced that the one with a high discharge pressure recovers exhaust heat, and the one with a low discharge pressure does not recover exhaust heat, or the one with the high discharge temperature recovers exhaust heat, and the one with the low discharge temperature does not recover exhaust heat.
The present invention is not limited to the above-mentioned embodiments, and various modifications are included. For example, the above examples have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those comprising all the described configurations. Further, it is possible to add, delete, or replace other configurations for a part of the configuration of the embodiment. Information such as a program that realizes each function can be placed in a memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD.
Further, the technical idea of the present invention can be expressed as a heat energy recovery equipment if we focus on the controller 1 and the exhaust heat recovery equipment 2. Further, an example of the invention disclosed herein described above can be expressed as follows.

Aspect 1

An exhaust heat recovery system comprising: a plurality of gas compressors; a exhaust heat recovery equipment; and a controller, wherein further comprising a exhaust heat recovery path connecting the plurality of gas compressors and the exhaust heat recovery equipment, and the plurality of gas compressors can select whether or not to use the exhaust heat recovery path based on instructions from the controller, the controller compares the set required water temperature with the supply water temperature, which is the temperature of the water supplied from the exhaust heat recovery equipment to the outside, and at least one of the plurality of gas compressors is instructed to use the exhaust heat recovery path when the supply water temperature is lower than the required water temperature.

Aspect 2

The exhaust heat recovery system according to aspect 1, wherein the controller instructs one of the gas compressors using the exhaust heat recovery path to stop using the exhaust heat recovery path in case the supply water temperature is higher than the required water temperature.

Aspect 3

The exhaust heat recovery system according to aspect 1, wherein at the time the controller instructs one of the gas compressors not using the exhaust heat recovery path to use the exhaust heat recovery path, in case a constant speed machine is included in a gas compressor that does not use the exhaust heat recovery path, the controller instructs to use of the exhaust heat recovery path with priority given to the constant speed machine.

Aspect 4

The exhaust heat recovery system according to aspect 1, wherein at the time the controller instructs one of the gas compressors not using the exhaust heat recovery path to use the exhaust heat recovery path, in case a constant speed machine is not included in a gas compressor that does not use the exhaust heat recovery path, and a variable speed machine in full-speed operation is included, the controller instructs to use of the exhaust heat recovery path with priority given to the variable speed machine in full-speed operation.

Aspect 5

The exhaust heat recovery system according to aspect 1, wherein at the time the controller instructs one of the gas compressors using the exhaust heat recovery path not to use the exhaust heat recovery path, in case a variable speed machine during frequency control is included in a gas compressor using the exhaust heat recovery path, the controller instructs to stop using the exhaust heat recovery path with priority given to the variable speed machine during frequency control.

Aspect 6

The exhaust heat recovery system according to aspect 1, wherein at the time the controller instructs one of the gas compressors using the exhaust heat recovery path not to use the exhaust heat recovery path, in case a variable speed machine during frequency control is not included in a gas compressor using the exhaust heat recovery path, and a variable speed machine in full-speed operation is included, the controller instructs to stop using the exhaust heat recovery path with priority given to the variable speed machine in full-speed operation.

Aspect 7

The exhaust heat recovery system according to aspect 1, wherein the controller instructs the use of a exhaust heat recovery path with priority given to a gas compressor having a large amount of recoverable heat amount.

Aspect 8

A heat energy recovery equipment comprising: a exhaust heat recovery equipment and a controller, wherein the controller instructs a plurality of gas compressors whether or not to use a exhaust heat recovery path between the gas compressor and the exhaust heat recovery equipment, wherein further comprising a exhaust heat recovery path connecting the plurality of gas compressors and the exhaust heat recovery equipment, and the plurality of gas compressors can select whether or not to use the exhaust heat recovery path based on instructions from the controller, the controller compares the set required water temperature with the supply water temperature, which is the temperature of the water supplied from the exhaust heat recovery equipment to the outside, and at least one of the plurality of gas compressors is instructed to use the exhaust heat recovery path when the supply water temperature is lower than the required water temperature.

Aspect 9

The heat energy recovery equipment according to aspect 8, wherein the controller instructs one of the gas compressors using the exhaust heat recovery path to stop using the exhaust heat recovery path in case the supply water temperature is higher than the required water temperature.

Aspect 10

The heat energy recovery equipment according to aspect 8, wherein at the time the controller instructs one of the gas compressors not using the exhaust heat recovery path to use the exhaust heat recovery path, in case a constant speed machine is included in a gas compressor that does not use the exhaust heat recovery path, the controller instructs to use of the exhaust heat recovery path with priority given to the constant speed machine.

Aspect 11

The heat energy recovery equipment according to aspect 8, wherein at the time the controller instructs one of the gas compressors not using the exhaust heat recovery path to use the exhaust heat recovery path, in case a constant speed machine is not included in a gas compressor that does not use the exhaust heat recovery path, and a variable speed machine in full-speed operation is included, the controller instructs to use of the exhaust heat recovery path with priority given to the variable speed machine in full-speed operation.

Aspect 12

The heat energy recovery equipment according to aspect 8, wherein at the time the controller instructs one of the gas compressors using the exhaust heat recovery path not to use the exhaust heat recovery path, in case a variable speed machine during frequency control is included in a gas compressor using the exhaust heat recovery path, the controller instructs to stop using the exhaust heat recovery path with priority given to the variable speed machine during frequency control.

Aspect 13

The heat energy recovery equipment according to aspect 8, wherein at the time the controller instructs one of the gas compressors using the exhaust heat recovery path not to use the exhaust heat recovery path, in case a variable speed machine during frequency control is not included in a gas compressor using the exhaust heat recovery path, and a variable speed machine in full-speed operation is included, the controller instructs to stop using the exhaust heat recovery path with priority given to the variable speed machine in full-speed operation.

Aspect 14

The heat energy recovery equipment according to aspect 8, wherein the controller instructs the use of a exhaust heat recovery path with priority given to a gas compressor having a large amount of recoverable heat amount.

Claims

An exhaust heat recovery system comprising:
a plurality of gas compressors (3);

an exhaust heat recovery equipment (2);

and a controller (1),

wherein further comprising a exhaust heat recovery path connecting the plurality of gas compressors (3) and the exhaust heat recovery equipment (2), and the plurality of gas compressors (3) can select whether or not to use the exhaust heat recovery path based on instructions from the controller (1),

the controller (1) compares the set required water temperature with the supply water temperature, which is the temperature of the water supplied from the exhaust heat recovery equipment (2) to the outside, and at least one of the plurality of gas compressors (3) is instructed to use the exhaust heat recovery path when the supply water temperature is lower than the required water temperature.
The exhaust heat recovery system according to claim 1, wherein the controller (1) instructs one of the gas compressors (3) using the exhaust heat recovery path to stop using the exhaust heat recovery path in case the supply water temperature is higher than the required water temperature.
The exhaust heat recovery system according to claim 1 and/or 2, wherein at the time the controller (1) instructs one of the gas compressors (3) not using the exhaust heat recovery path to use the exhaust heat recovery path, in case a constant speed machine is included in a gas compressor that does not use the exhaust heat recovery path, the controller (1) instructs to use of the exhaust heat recovery path with priority given to the constant speed machine.
The exhaust heat recovery system according to at least one of claims 1 to 3, wherein at the time the controller (1) instructs one of the gas compressors (3) not using the exhaust heat recovery path to use the exhaust heat recovery path, in case a constant speed machine is not included in a gas compressor (3) that does not use the exhaust heat recovery path, and a variable speed machine in full-speed operation is included, the controller (1) instructs to use of the exhaust heat recovery path with priority given to the variable speed machine in full-speed operation.
The exhaust heat recovery system according to at least one of claims 1 to 4, wherein at the time the controller (1) instructs one of the gas compressors (3) using the exhaust heat recovery path not to use the exhaust heat recovery path, in case a variable speed machine during frequency control is included in a gas compressor (3) using the exhaust heat recovery path, the controller (1) instructs to stop using the exhaust heat recovery path with priority given to the variable speed machine during frequency control.
The exhaust heat recovery system according to at least one of claims 1 to 5, wherein at the time the controller (1) instructs one of the gas compressors (3) using the exhaust heat recovery path not to use the exhaust heat recovery path, in case a variable speed machine during frequency control is not included in a gas compressor (3) using the exhaust heat recovery path, and a variable speed machine in full-speed operation is included, the controller (1) instructs to stop using the exhaust heat recovery path with priority given to the variable speed machine in full-speed operation.
The exhaust heat recovery system according to at least one of claims 1 to 6, wherein the controller (1) instructs the use of a exhaust heat recovery path with priority given to a gas compressor (3) having a large amount of recoverable heat amount.
A heat energy recovery equipment comprising:
a exhaust heat recovery equipment (2) and a controller (1) , wherein the controller (1) instructs a plurality of gas compressors (3) whether or not to use a exhaust heat recovery path between the gas compressor (3) and the exhaust heat recovery equipment (2),

wherein further comprising a exhaust heat recovery path connecting the plurality of gas compressors (3) and the exhaust heat recovery equipment (2), and the plurality of gas compressors (3) can select whether or not to use the exhaust heat recovery path based on instructions from the controller (1),

the controller (1) compares the set required water temperature with the supply water temperature, which is the temperature of the water supplied from the exhaust heat recovery equipment (2) to the outside, and at least one of the plurality of gas compressors (3) is instructed to use the exhaust heat recovery path when the supply water temperature is lower than the required water temperature.
The heat energy recovery equipment according to claim 8, wherein the controller (1) instructs one of the gas compressors (3) using the exhaust heat recovery path to stop using the exhaust heat recovery path in case the supply water temperature is higher than the required water temperature.
The heat energy recovery equipment according to at least one of claims 8 to 9, wherein at the time the controller (1) instructs one of the gas compressors (3) not using the exhaust heat recovery path to use the exhaust heat recovery path, in case a constant speed machine is included in a gas compressor (3) that does not use the exhaust heat recovery path, the controller (1) instructs to use of the exhaust heat recovery path with priority given to the constant speed machine.
The heat energy recovery equipment according to at least one of claims 8 to 10, wherein at the time the controller (1) instructs one of the gas compressors (3) not using the exhaust heat recovery path to use the exhaust heat recovery path, in case a constant speed machine is not included in a gas compressor (3) that does not use the exhaust heat recovery path, and a variable speed machine in full-speed operation is included, the controller (1) instructs to use of the exhaust heat recovery path with priority given to the variable speed machine in full-speed operation.
The heat energy recovery equipment according to at least one of claims 8 to 11, wherein at the time the controller (1) instructs one of the gas compressors (3) using the exhaust heat recovery path not to use the exhaust heat recovery path, in case a variable speed machine during frequency control is included in a gas compressor (3) using the exhaust heat recovery path, the controller (1) instructs to stop using the exhaust heat recovery path with priority given to the variable speed machine during frequency control.
The heat energy recovery equipment according to at least one of claims 8 to 12, wherein at the time the controller (1) instructs one of the gas compressors (3) using the exhaust heat recovery path not to use the exhaust heat recovery path, in case a variable speed machine during frequency control is not included in a gas compressor (3) using the exhaust heat recovery path, and a variable speed machine in full-speed operation is included, the controller (1) instructs to stop using the exhaust heat recovery path with priority given to the variable speed machine in full-speed operation.
The heat energy recovery equipment according to at least one of claims 8 to 13, wherein the controller (1) instructs the use of a exhaust heat recovery path with priority given to a gas compressor (3) having a large amount of recoverable heat amount.