Absorption chiller heater

Abstract

An absorption type hot and cold water machine that moves heat by circulation of a refrigerant and an absorbent, comprising: a regenerator having a combustor that combusts a fuel of a gas mainly composed of hydrogen to generate heat for heating the absorbent; a fuel pipe that guides the fuel to the combustor; an inert gas pipe that supplies inert gas to the fuel pipe; an inert gas detector that detects whether or not the inert gas can be supplied to the fuel pipe; and a control device that controls combustion operation in the combustor. In the middle of combustion of the fuel in the combustor, in the case where the inert gas detector detects a state in which the inert gas cannot be supplied to the fuel pipe, the control device controls the combustion operation in the combustor in such a manner that the combustion of the fuel in the combustor is continued until an instruction to stop the absorption type hot and cold water machine is accepted.

Description

Technical Field

[0001] This disclosure relates to absorption chillers and hot water systems. Background Technology

[0002] An absorption chiller / hot water heater cools the target medium (typically cold water) by removing the latent heat of vaporization required when the refrigerant liquid evaporates into refrigerant vapor in the evaporator. The refrigerant vapor generated in the evaporator is absorbed by the absorbent liquid in the absorber. The absorbent liquid in the absorber, whose concentration has decreased due to the absorption of refrigerant vapor, is sent to a regenerator where it is heated, thereby increasing its concentration. The absorbent liquid, with its increased concentration in the regenerator, returns to the absorber and can again absorb the refrigerant vapor generated in the evaporator. One method for heating the absorbent liquid in the regenerator is to install a combustion device for burning fuel in the regenerator. Regarding combustion devices for burning fuel, with the negative impacts of global warming in recent years being noted, the use of hydrogen as fuel is being studied to reduce greenhouse gas emissions. Hydrogen is easier to ignite than fuels such as city gases, which are mainly composed of hydrocarbons; therefore, configurations that implement nitrogen-based purging control in hydrogen burners are being studied (for example, see Japanese Patent No. 7546632 (paragraph 0005)).

[0003] When a combustion device with a hydrogen burner as described in Japanese Patent No. 7546632 is applied to the regenerator of an absorption chiller, if the inert gas (mainly nitrogen) used for purging combustible gases in the hydrogen discharge pipe is detected to be gone, inert gas purging at shutdown cannot be performed, thus controlling the operation of the absorption chiller to stop. However, even if the inert gas used for purging is depleted, it will not directly affect the operation of the absorption chiller. Summary of the Invention

[0004] In view of the above, this disclosure relates to providing an absorption chiller / hot water heater that can continue to operate even in the event that an inert gas supply is unavailable.

[0005] The first aspect of this disclosure relates to an absorption chiller / water heater that moves heat through the circulation of a refrigerant undergoing a phase change and an absorbent liquid mixed with the refrigerant. The absorption chiller / water heater comprises: a regenerator having a burner that burns a gaseous fuel, primarily composed of hydrogen, to generate heat for heating the absorbent liquid; a fuel line that directs the fuel to the burner; an inert gas line that supplies inert gas to the fuel line; an inert gas detector that detects whether inert gas can be supplied to the fuel line; and a control device that controls the combustion operation in the burner. If, during fuel combustion in the burner, the inert gas detector detects that inert gas cannot be supplied to the fuel line, the control device controls the combustion operation in the burner to continue fuel combustion in the burner until an instruction is received to stop the absorption chiller / water heater.

[0006] If configured in this way, the inability to supply inert gas will not directly affect the combustion of fuel. Therefore, even if the inert gas cannot be supplied, combustion can continue.

[0007] Furthermore, based on the absorption chiller and hot water unit involved in the first aspect of this disclosure, the absorption chiller and hot water unit involved in the second aspect of this disclosure can also be configured such that, when the fuel is burning in the burner, if the inert gas detector detects that the inert gas cannot be supplied to the fuel piping, the control device reports such a condition.

[0008] If configured in this way, by issuing a report, it is possible, for example, to provide the person receiving the report with an opportunity to resolve the defect in the supply of inert gas.

[0009] Furthermore, based on the absorption chiller and hot water unit involved in the first or second aspect of this disclosure, the absorption chiller and hot water unit involved in the third aspect of this disclosure may also be configured as follows: it includes a temperature-related value detector that detects the temperature of the absorbent liquid in the regenerator or a physical quantity related to the temperature. When the inert gas detector detects that the inert gas cannot be supplied to the fuel piping, and an instruction is received to stop the absorption chiller and hot water unit, if the value detected by the temperature-related value detector exceeds a predetermined value, the control device controls the combustion operation in the burner to perform a low-combustion operation that reduces the amount of combustion in the burner, so that the value detected by the temperature-related value detector is reduced to below the predetermined value, and then the combustion of the fuel in the burner is stopped.

[0010] If configured in this way, even if the fuel remaining inside the fuel piping cannot be purged with inert gas when combustion stops, the occurrence of ignition of the fuel remaining inside the fuel piping can be reduced by lowering the temperature of the regenerator.

[0011] Furthermore, based on the absorption chiller and hot water unit involved in the first or second aspect of this disclosure, the absorption chiller and hot water unit involved in the fourth aspect of this disclosure may also be configured as follows: it includes a temperature-related value detector that detects the temperature of the absorbent liquid in the regenerator or a physical quantity related to the temperature. When the inert gas detector detects that the inert gas cannot be supplied to the fuel piping, and an instruction is received to stop the absorption chiller and hot water unit, if the value detected by the temperature-related value detector exceeds a predetermined value, the control device controls the combustion operation in the burner so as to stop the combustion of the fuel in the burner after performing low combustion operation that reduces the amount of combustion in the burner until a predetermined time has elapsed.

[0012] With this configuration, even if the fuel remaining inside the fuel piping cannot be purged with inert gas when combustion operation stops, the temperature of the regenerator can be reduced by performing low-combustion operation for a specified period of time, and the occurrence of ignition of the fuel remaining inside the fuel piping can be decreased.

[0013] According to this disclosure, combustion can continue even in situations where an inert gas cannot be supplied. Attached Figure Description

[0014] Figure 1 This is a schematic system diagram of an absorption chiller / hot water heater according to an embodiment of this disclosure.

[0015] Figure 2 This is a schematic system diagram of the combustion device included in the absorption chiller according to the embodiments of this disclosure.

[0016] Figure 3 This is a block diagram illustrating the hardware configuration of the control device included in the combustion device of an absorption chiller according to an embodiment of the present disclosure.

[0017] Figure 4 This is a flowchart illustrating the control of the operation of the absorption chiller / hot water heater according to the embodiments of this disclosure.

[0018] Figure 5 It is a partial representation Figure 4 The flowchart shows a modified example of the control of the operation. Detailed Implementation

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Furthermore, in each drawing, identical or equivalent parts are labeled with the same or similar reference numerals, and repeated descriptions are omitted. Additionally, for ease of explanation, the dimensions and scales of the drawings are exaggerated and sometimes differ from the actual scales.

[0020] First, refer to Figure 1 The absorption chiller 1 according to the embodiments of this disclosure will be described. Figure 1 This is a schematic system diagram of an absorption chiller / hot water heater 1. The absorption chiller / hot water heater 1 comprises an absorber 10, an evaporator 20, a regenerator 30, and a condenser 40 as the main components for the absorption cycle. Additionally, the absorption chiller / hot water heater 1 includes a combustion device 70 and a control device 60. The absorption chiller / hot water heater 1 performs thermal transfer by circulating a refrigerant V while undergoing a phase change relative to the absorbent liquid S, typically lowering the temperature of chilled water C, the temperature-regulating medium, during refrigeration operation. The absorption chiller / hot water heater 1 is typically capable of both refrigeration and heating operation, and can perform both cooling and heating of chilled and hot water; however, in this disclosure, it is described as a device for refrigeration operation (i.e., operation that lowers the temperature of chilled water C). Furthermore, one characteristic of the absorption chiller / hot water heater 1 is the use of a gaseous fuel F, primarily composed of hydrogen, as the fuel supplied to the regenerator 30.

[0021] In the following description, the absorbent S is referred to as "dilute solution Sw," "concentrated solution Sa," etc., depending on its properties and position in the absorption cycle for easy differentiation. However, when properties are not limited, it is generally referred to as "absorbent S." Similarly, the refrigerant V is referred to as "evaporator refrigerant vapor Ve," "regenerator refrigerant vapor Vg," and "refrigerant liquid Vf," etc., depending on its properties and position in the absorption cycle for easy differentiation. However, when properties are not limited, it is generally referred to as "refrigerant V." In this embodiment, an aqueous solution of lithium bromide (LiBr) is used as the absorbent S (typically a mixture of absorbent and refrigerant), and water (H2O) is used as the refrigerant V. However, this is not a limitation; other combinations of refrigerants and absorbents (or absorbents) can also be used.

[0022] The absorber 10 is a device that uses a concentrated solution Sa to absorb the refrigerant vapor Ve generated in the evaporator 20. Inside the absorber tank 17, the absorber 10 has cooling pipes 11 that serve as a cooling water flow path for cooling water D, and concentrated solution spray nozzles 12 that spray the concentrated solution Sa toward the outer surface of the cooling pipes 11. The concentrated solution spray nozzles 12 are positioned above the cooling pipes 11 so that the sprayed concentrated solution Sa falls onto the cooling pipes 11. The absorber 10 stores a dilute solution Sw, whose concentration has decreased due to the absorption of the evaporator refrigerant vapor Ve by the sprayed concentrated solution Sa, in the lower part of the absorber tank 17. In the absorber 10, the cooling water D removes (i.e., eliminates) the heat of absorption generated when the evaporator refrigerant vapor Ve is absorbed by the concentrated solution Sa.

[0023] In cooling pipe 11, a cooling water inlet pipe 11a, through which cooling water D flows, is connected to one end (or the first end). A cooling water connecting pipe 14 is connected to the other end (or the second end) of cooling pipe 11. A cooling water outlet pipe 98 outside the absorption chiller 1 is connected to the cooling water inlet pipe 11a. The cooling water outlet pipe 98 is connected to a cooling tower (not shown) outside the absorption chiller 1. A cooling water pump 91 outside the absorption chiller 1 is installed on the cooling water outlet pipe 98. The absorption chiller 1 uses the operation of the cooling water pump 91 to make cooling water D flow within cooling pipe 11. The cooling water pump 91 can also adjust the discharge flow rate of cooling water D via an inverter.

[0024] Evaporator 20 is a device that cools cold water C by removing the latent heat of vaporization required for the refrigerant liquid Vf to change into refrigerant vapor Ve from the cold water C. Inside evaporator tank 27, evaporator 20 has evaporation tubes 21 serving as a cold water flow path for the cold water C, and refrigerant liquid spray nozzles 22 that spray refrigerant liquid Vf toward the outer surface of evaporation tubes 21. The refrigerant liquid spray nozzles 22 are positioned above evaporation tubes 21 so that the sprayed refrigerant liquid Vf falls onto evaporation tubes 21. Evaporator 20 also includes: a refrigerant liquid pipe 28 that guides the refrigerant liquid Vf accumulated in the lower part of evaporator tank 27 toward the refrigerant liquid spray nozzles 22; and a refrigerant pump 29 that delivers the refrigerant liquid Vf from the refrigerant liquid pipe 28 to the refrigerant liquid spray nozzles 22. The evaporator 20 cools the cold water C by taking away the heat of vaporization from the cold water C flowing in the evaporator tube 21 to evaporate the refrigerant liquid Vf sprayed onto the outer surface of the evaporator tube 21 into evaporator refrigerant vapor Ve, and the unevaporated refrigerant liquid Vf in the sprayed refrigerant liquid Vf is stored in the lower part of the evaporator tank 27.

[0025] A cold water inlet pipe 21a, through which cold water C flows, is connected to one end (or the first end) of the evaporator pipe 21. A cold water outlet pipe 21b, through which cold water C flows out of the evaporator pipe 21, is connected to the other end (or the second end) of the evaporator pipe 21. A cold water return pipe 95, external to the absorption chiller 1, is connected to the cold water inlet pipe 21a. A cold water outflow pipe 96, external to the absorption chiller 1, is connected to the cold water outlet pipe 21b. The cold water return pipe 95 and the cold water outflow pipe 96 are connected to a heat utilization device (not shown) that utilizes the heat and cold of the cold water C. A cold water pump 92, external to the absorption chiller 1, is installed on the cold water return pipe 95. The absorption chiller 1 uses the operation of the cold water pump 92 to make the cold water C flow within the evaporator pipe 21. The cold water pump 92 can also regulate the discharge flow rate of the cold water C via an inverter.

[0026] In this embodiment, the absorber 10 is arranged adjacent to the evaporator 20, and the upper part of the absorber tank 17 is connected to the upper part of the evaporator tank 27. With this structure, the evaporator refrigerant vapor Ve generated inside the evaporator tank 27 can be guided into the interior of the absorber tank 17.

[0027] The regenerator 30 is a device that removes refrigerant V from a dilute solution Sw by introducing and heating it, thereby generating a concentrated solution Sa. In the regenerator 30, the refrigerant V removed from the dilute solution Sw is in a vapor state, and this vapor of refrigerant V is referred to as regenerator refrigerant vapor Vg. The regenerator 30 is equipped with a combustion device 70 for heating the dilute solution Sw. The regenerator 30 has a regenerator tank 37, which stores the introduced absorbent S. Inside the regenerator tank 37 is a burner 71, which is one of the components of the combustion device 70. The burner 71 generates heat of combustion by introducing fuel F and air A and burning the fuel F. The regenerator 30 generates heat for heating the dilute solution Sw by burning the fuel F in the burner 71. A detailed description of the configuration of the combustion device 70 will follow.

[0028] The condenser 40 is a device that introduces refrigerant vapor Vg, which evaporates from the dilute solution Sw in the regenerator 30, and cools it to condense it, generating refrigerant liquid Vf that is supplied to the evaporator 20. The condenser 40 has a condenser tube 41 inside the condenser tank 47, which is a component forming the flow path (or cooling water flow path) for the cooling water D. In this embodiment, the other end (or the second end) of the cooling water connecting pipe 14 is connected to one end (or the first end) of the condenser tube 41. Furthermore, as described above, one end (or the first end) of the cooling water connecting pipe 14 is connected to the cooling pipe 11. A cooling water outlet pipe 41b is connected to the other end (or the second end) of the condenser tube 41 for the cooling water D flowing out of the condenser tube 41. A cooling water return pipe 99 outside the absorption chiller 1 is connected to the cooling water outlet pipe 41b. The cooling water return pipe 99 is connected to a cooling tower (not shown) outside the absorption chiller 1. With this structure, the cooling water D flowing in the cooling water return pipe 99 is cooled by the cooling tower (not shown) and supplied to the cooling water return pipe 98.

[0029] The condenser tank 47 and the regenerator tank 37 are disposed close to each other. In this embodiment, the upper part of the regenerator tank 37 is connected to the upper part of the condenser tank 47 via a regenerator refrigerant vapor flow path 35 (e.g., constructed by piping). Regenerator refrigerant vapor Vg is introduced into the condenser 40 from the regenerator 30 via the regenerator refrigerant vapor flow path 35. Cooling water D flowing in the condenser tube 41 removes heat from the regenerator refrigerant vapor Vg, thereby condensing the regenerator refrigerant vapor Vg into refrigerant liquid Vf. In other words, the cooling water D flowing in the condenser tube 41 removes the condensation heat generated during the phase change of the regenerator refrigerant vapor Vg into refrigerant liquid Vf. In this embodiment, the condenser tank 47 and the regenerator tank 37 are disposed above the evaporator tank 27 and the absorber tank 17. The bottom or lower part of the condenser tank 47 is connected to the evaporator tank 27 via a condenser refrigerant liquid pipe 48. This structure allows the refrigerant liquid Vf in the condenser tank 47 to be guided into the evaporator tank 27 by the position head and the pressure difference between the two.

[0030] The bottom or lower part of the absorber tank 17 is connected to the regenerator tank 37 via a dilute solution pipe 18. A solution pump 19 is installed in the dilute solution pipe 18. The absorption chiller 1 can transport the dilute solution Sw from the absorber tank 17 to the regenerator tank 37 via the solution pump 19. Inside the regenerator tank 37, as the introduced dilute solution Sw moves from the inlet to the outlet, the refrigerant V is separated from the dilute solution Sw and its concentration increases. The portion of the concentrated solution Sa flowing out of the regenerator tank 37 is connected to the concentrated solution spray nozzle 12 of the absorber 10 via a concentrated solution pipe 38. A concentrated solution thermometer 53 is installed in the concentrated solution pipe 38 near the regenerator 30 to detect the temperature of the concentrated solution Sa flowing out of the regenerator 30. The concentrated solution thermometer 53 is a device for detecting the outlet temperature of the absorbent liquid S in the regenerator 30, equivalent to a temperature correlation value detector. The concentrated solution thermometer 53 can also be installed in the regenerator tank 37. The absorption chiller 1 uses a solution pump 19 to transport a dilute solution Sw to a regenerator tank 37. Inside the regenerator tank 37, a concentrated solution Sa, generated by the removal of refrigerant V, is introduced via a concentrated solution pipe 38 to a concentrated solution spray nozzle 12. A solution heat exchanger 81 is inserted into and configured in both the dilute solution pipe 18 and the concentrated solution pipe 38. This heat exchanger 81 facilitates heat exchange between the dilute solution Sw flowing in the dilute solution pipe 18 and the concentrated solution Sa flowing in the concentrated solution pipe 38.

[0031] Here, please refer to the same. Figure 2 The combustion device 70 installed in the regenerator 30 will be described. Figure 2 This is a schematic system diagram of the combustion device 70. The combustion device 70 is suitable for burning fuel F, which is a gas whose main component is hydrogen. Here, the gas whose main component is hydrogen is a gas containing more than 50% by volume of hydrogen, and typically contains more than 80% by volume of hydrogen, or it can be a gas containing 100% hydrogen. The combustion device 70 includes a burner 71, a mechanism for supplying fuel F to the burner 71, a mechanism for supplying nitrogen N as an inert gas, and a mechanism for supplying air A to the burner 71, and also includes a control device 60.

[0032] The burner 71 is a device that generates heat of combustion by introducing fuel F and air A and burning the fuel F. In addition to the main burner, the burner 71 may also have an ignition burner. The burner 71 is connected to a fuel pipe 72 that guides fuel F to the burner 71 and an air pipe 82 that guides air A to the burner 71.

[0033] For fuel piping 72, a burner 71 is connected to a first end, and a fuel source 73 is connected to a second end on the opposite side of the first end. The fuel source 73 can be, for example, a source of gas that produces fuel F, such as a hydrogen production process; it can be a conduit supplying commercial hydrogen; or it can be a gas cylinder filled with fuel F. The fuel F flowing in fuel piping 72 can be pure hydrogen or by-product hydrogen. Fuel piping 72 allows fuel F to flow from fuel source 73 towards burner 71, i.e., from the second end towards the first end. A fuel shut-off valve 74 and a fuel control valve 75 are provided in fuel piping 72. The fuel shut-off valve 74 is a valve that cuts off the flow of fuel F in fuel piping 72; a solenoid valve may also be used. The fuel control valve 75 is a valve that regulates the flow rate of fuel F introduced into burner 71; an electric valve may also be used. The fuel control valve 75 can also change its opening degree according to commands from control device 60, thereby enabling stepless regulation of the flow rate of fuel F introduced into burner 71. Viewed from the direction of fuel F flow, the fuel cut-off valve 74 is located upstream of the fuel control valve 75. The fuel piping 72, fuel source 73, fuel cut-off valve 74, and fuel control valve 75 correspond to the mechanism for supplying fuel F to the burner 71.

[0034] The nitrogen supply mechanism in the combustion device 70 supplies nitrogen N to the fuel line 72. The fuel F burned in the burner 71 is a gas primarily composed of hydrogen; therefore, compared to fuels such as city gas, which are primarily composed of hydrocarbons, it has a wider combustion range and a faster combustion speed, making it easier to ignite. Considering this, the combustion device 70 is equipped with a nitrogen supply mechanism to replace some of the fuel F in the fuel line 72 with air when the combustion is stopped, thereby preventing it from entering the combustion range and accidentally burning. This ensures that fuel F does not remain in the fuel line 72. Furthermore, although nitrogen N is used as the substance for replacing the fuel F in the fuel line 72 in this embodiment, an inert gas other than nitrogen N can also be used. The term "inert gases" as used here refers to a collective of gases that are chemically stable and do not readily react with other elements or compounds. Besides noble gases (i.e., the six elements in group 0 of the periodic table: He, Ne, Ar, Kr, Xe, and Rn), it also includes nitrogen and carbon dioxide, which are far less reactive than oxygen. In this embodiment, nitrogen (N) is used for ease of acquisition. Nitrogen (N) can be any type of nitrogen commonly used in industrial applications.

[0035] The combustion device 70 includes a nitrogen pipe 76 and a nitrogen source 77 as mechanisms for supplying nitrogen (N). The nitrogen pipe 76 is a pipe that supplies nitrogen (N) to the fuel pipe 72, essentially an inert gas pipe. A first end of the nitrogen pipe 76 is typically connected to the fuel pipe 72 between the fuel shut-off valve 74 and the fuel control valve 75. A second end of the nitrogen pipe 76, opposite to the first end, is connected to the nitrogen source 77. The nitrogen source 77 is the source of nitrogen (N) supplied to the fuel pipe 72; for example, it can be extracted from a nitrogen-utilizing process or a gas cylinder storing nitrogen (N). The nitrogen pipe 76 is equipped with a nitrogen shut-off valve 79 that cuts off the flow of nitrogen (N) within the nitrogen pipe 76, and a check valve 80 that prevents the backflow of hydrogen.

[0036] A pressure switch 78 is installed on the nitrogen pipe 76 between the nitrogen source 77 and the nitrogen shut-off valve 79. The pressure switch 78 is a switch that turns on when the pressure inside the nitrogen pipe 76 being tested is lower than a specified pressure; it is sometimes referred to as a low-pressure switch. The specified pressure is typically the minimum pressure required to supply the amount of nitrogen N needed to displace the fuel F inside the fuel pipe 72. Therefore, the pressure switch 78 turning on means that the required nitrogen N cannot be supplied from the nitrogen source 77 to the nitrogen pipe 76. Thus, the pressure switch 78 detects whether nitrogen N, in the form of an inert gas, can be supplied to the fuel pipe 72, acting as an inert gas detector.

[0037] For the air pipe 82 that guides air A to the burner 71, the burner 71 is connected to a first end, and an air fan 83 is connected to a second end on the opposite side of the first end. The air fan 83 is a device that compresses the air surrounding the combustion device 70 toward the burner 71. An air control valve 85 is provided on the air pipe 82. The air control valve 85 is a valve that regulates the flow rate of air A introduced into the burner 71, and an electric valve may also be used. The air control valve 85 can also change its opening degree according to the command from the control device 60, thereby enabling stepless regulation of the flow rate of air A introduced into the burner 71. In this embodiment, the opening degree of the air control valve 85 can be adjusted independently relative to the operation of the fuel control valve 75, but the opening degree of the air control valve 85 and the fuel control valve 75 can also be adjusted in a linked manner (i.e., in conjunction). Alternatively, it can be used to steplessly change the opening of the air control valve 85, or together with it to perform inverter control of the air fan 83, thereby regulating the flow rate of air A flowing in the air piping 82.

[0038] The control device 60 is a device that controls the operation of the combustion device 70, including the combustion operation in the burner 71. Here, controlling the combustion operation typically means starting and stopping the combustion and adjusting the combustion rate. The control device 60 has a control unit 61, a communication unit 62, and a storage unit 63. Although the above units are referred to by their functions here for ease of explanation, they are typically configured to be integrated within the control device 60, or one or more of the above units may be physically separated, or a single unit may be physically divided into multiple units.

[0039] The control unit 61 is the part that controls the operation of the various devices and equipment constituting the combustion device 70. The control unit 61 is connected to the fuel cut-off valve 74 and the nitrogen cut-off valve 79 via communication lines (wired or wireless, hereinafter the same), and controls the opening and closing of these valves. Additionally, the control unit 61 is connected to the fuel control valve 75 and the air control valve 85 via communication lines, and typically controls the opening degree of these valves to any degree between 0% and 100%. Furthermore, the control unit 61 is connected to the air fan 83 via a communication line, and typically controls the start and stop of the air fan 83, but can also control the rotational speed of the air fan 83. In addition, the control unit 61 has a timing unit such as a clock or timer for measuring time. Furthermore, the control unit 61 may also have a program for properly operating the aforementioned devices and equipment. The control unit 61 may also include a processor and / or memory (RAM) as its physical components.

[0040] The communication unit 62 is the part that transmits and receives signals from the instrument or equipment. The communication unit 62 is connected to the pressure switch 78 via a communication line, and receives the pressure switch 78 as a signal when it is turned on. Additionally, the communication unit 62 is connected to the concentrated solution thermometer 53 (see reference 53) via a communication line. Figure 1 The communication unit 62 connects to and receives temperature information detected by the concentrated solution thermometer 53 as a signal. Additionally, the communication unit 62 reports to an external monitoring panel (not shown) and terminal (not shown). Reports are typically issued as attention-grabbing notifications, including warnings and error alarms. In this disclosure, warnings are mild notifications, communicated via lights or text messages without sound, while error alarms are moderate or severe notifications, accompanied by a warning sound and communicated via lights or text messages. The communication unit 62 may also be configured as a communication interface.

[0041] Storage unit 63 stores programs, data, and other information required for the operation of combustion device 70. Storage unit 63 may also store sequences related to the operation of combustion device 70. Furthermore, storage unit 63 may store the standard opening degrees of fuel control valve 75 and air control valve 85 under combustion conditions such as rated combustion operation and low combustion operation. Storage unit 63 may also include the physical configuration of a storage device and / or memory (RAM and / or ROM).

[0042] In addition, such as in Figure 1 As shown in the diagram, the control device 60, in this embodiment, controls not only the operation of the combustion device 70 but also the operation of the absorption chiller 1. The control unit 61 is connected to the solution pump 19 and the refrigerant pump 29 via communication lines to control the start / stop and discharge flow rate of each pump 19 and 29. Additionally, the control unit 61 is connected to the cooling water pump 91 and the cold water pump 92 via communication lines to control the start / stop and discharge flow rate of each pump 91 and 92. The communication unit 62, in order to monitor the operating status of the absorption chiller 1, is connected via a communication line to an instrument located at an appropriate position to receive information detected by the instrument as a signal. The storage unit 63 stores a program for controlling the operation of the absorption chiller 1.

[0043] Here, please refer to the same. Figure 3 The block diagram shown illustrates the hardware configuration of the control device 60. Figure 3 The block diagram shown illustrates the concept of the physical configuration of the control device 60. The control device 60 includes a processor 65, a memory 66, a storage device 67, and a communication interface 68. The control device 60 may also be a computer.

[0044] The processor 65 processes various information from the control device 60. This information includes the content and timing of control signals sent to the various devices and equipment constituting the absorption chiller 1. The processor 65 can be a single processor or two or more processors. The operation of the processor 65 can be performed not only by one processor 60, but also by multiple processors 65 located in physically separate positions working together. The processor 65 may also include a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor, a circuit board, or other electrical circuitry. The processor 65 is capable of executing programs and manipulating data to perform actions of the control device 60, including actions using any of the algorithms, methods, functions, procedures, and steps described in this disclosure.

[0045] Memory 66 (which can also be considered a first memory) temporarily or permanently records programs and / or data used for information processing in control device 60. Memory 66 may also store programs used by control device 60 to make various decisions and judgments. These programs can be added to and modified afterwards (i.e., after the manufacture of control device 60). Memory 66 may be a single memory or two or more memories. Memory 66 may also include volatile memories such as RAM and cache, and non-volatile memories such as ROM.

[0046] Storage device 67 (which can also be considered a second memory) temporarily or permanently records programs and / or data used for information processing in control device 60. Additionally, storage device 67 may store the relationship between values ​​detected by measuring instruments and their substitute values. Furthermore, storage device 67 can record data related to the acquired operating status of the absorption chiller 1 as needed. Storage device 67 may also hold other programs, including an operating system, that can be executed by control device 60 or other devices. Storage device 67 may also include hard disk drives (HDDs), solid-state drives (SSDs), and / or flash memory, etc.

[0047] Communication interface 68 communicates with fuel shut-off valve 74 and nitrogen shut-off valve 79, sending control signals related to their opening and closing to these valves. Additionally, communication interface 68 communicates with fuel control valve 75 and air control valve 85, sending control signals related to their opening degree to these valves. Furthermore, communication interface 68 communicates with air fan 83, sending control signals related to its start / stop. Additionally, communication interface 68 communicates with pressure switch 78, receiving control signals indicating that the switch is on. Furthermore, communication interface 68 communicates with concentrated solution thermometer 53, receiving temperature-related control signals from it. Additionally, communication interface 68 communicates with solution pump 19, refrigerant pump 29, cooling water pump 91, and chilled water pump 92, sending control signals related to their start / stop and discharge flow rate to these pumps. Furthermore, communication interface 68 can receive control signals related to the operating status of the absorption chiller / hot water unit 1 as needed. The communication interface 68 can also have the function of sending and receiving signals in the communication unit 62.

[0048] The components of the control device 60 (including the processor 65, memory 66, storage device 67, and communication interface 68) are interconnected and communicate with each other via buses such as system bus and control bus. Additionally, the control device 60 has a power supply 69. The power supply 69 typically includes a power plug for drawing power from commercial power or other sources. The power supply 69 may include a replaceable or non-replaceable battery, which may also be charged by receiving power from commercial power or other sources.

[0049] In the description of the hardware configuration of the control device 60 above, the programs and / or data stored in the memory 66 and / or storage device 67 may also be stored on a non-transitory computer-readable medium. The non-transitory computer-readable medium stores computer-readable commands and / or utilized data by executing methods implemented by a computer. Computer-readable media may include optical disks and optical storage devices, digital video discs (DVDs), CD-ROMs, DVD+ / -Rs, DVD-RAMs, DVD-ROMs, HD-DVDs, and BLURAY (registered trademark), etc. Computer-readable media may also include magnetic devices such as magnetic tapes, magnetic tape cassettes, cassette tapes, and removable discs. Each program (including program products) may include one or more modules of computer program commands encoded on a tangible, non-transitory computer-readable medium for execution by an information processing device, including a computer (control device 60 in this embodiment), or for controlling the operation of the information processing device. Alternatively, programs and / or data may be downloaded from an external device via a network.

[0050] Next, refer to Figure 1 and Figure 2 The operation of the absorption chiller 1 will be explained below. Furthermore, unless otherwise specified, the operation of each device connected to the control device 60 via a communication line, as shown below, is typically controlled by the control device 60. When the absorption chiller 1 is started, inert gas pre-purging of the fuel line 72 is performed before combustion begins in the burner 71. During inert gas pre-purging of the fuel line 72, the fuel control valve 75 and the nitrogen cut-off valve 79 are opened while the fuel shut-off valve 74 is closed. As a result, nitrogen N flows to the fuel line 72 and the burner 71, which are downstream of the fuel shut-off valve 74. Additionally, the air control valve 85 is opened, and the air fan 83 is started. As a result, air A flows to the air line 82 and the burner 71. This removes any unburned fuel F that may be present in the burner 71 from the fuel line 72 and the regenerator 30. Once the inert gas pre-purging of the fuel line 72 and the regenerator 30 is complete, the nitrogen shut-off valve 79 closes, and then the fuel shut-off valve 74 opens. Therefore, fuel F and air A are supplied to burner 71, and combustion of fuel F in burner 71 occurs. Furthermore, when combustion of fuel F in burner 71 begins, combustion first occurs in the ignition burner; after an ignition spark is generated in the ignition burner, combustion then occurs in the main burner. When using the ignition burner, the hydrogen piping of the ignition burner is also purged with inert gas before and after combustion. However, if the length of the ignition burner piping is short enough that backfire would not be a problem, the inert gas purging of the ignition burner piping is sometimes omitted.

[0051] If the absorption chiller 1 is started and the aforementioned inert gas pre-purging is completed, or during the inert gas pre-purging process, the cooling water pump 91 and the cold water pump 92 are started. If the cooling water pump 91 is operating, in this embodiment, cooling water D circulates through the cooling water inlet pipe 98, cooling water inlet pipe 11a, cooling pipe 11, cooling water connecting pipe 14, condenser pipe 41, cooling water outlet pipe 41b, cooling water return pipe 99, and the cooling tower (not shown). Additionally, if the cold water pump 92 is operating, cold water C circulates through the cold water return pipe 95, cold water inlet pipe 21a, evaporator pipe 21, cold water outlet pipe 21b, cold water inlet pipe 96, and the heat utilization equipment (not shown). If the cooling water pump 91 and the cold water pump 92 are started, the solution pump 19 and the refrigerant pump 29 are started as appropriate.

[0052] Regarding the absorption cycle, when observing the circulation on the refrigerant V side, the refrigerant vapor Vg introduced from the refrigerant 30 to the condenser 40 via the refrigerant vapor flow path 35 is cooled and condensed by the cooling water D flowing in the condenser tube 41, becoming refrigerant liquid Vf and accumulating in the lower part of the condenser tank 47. The temperature of the cooling water D, which has cooled the refrigerant vapor Vg, rises and flows out from the cooling water return pipe 99, and is supplied to the cooling tower (not shown). The refrigerant liquid Vf in the condenser tank 47 is introduced into the evaporator tank 27 via the condensed refrigerant liquid pipe 48.

[0053] The refrigerant liquid Vf introduced from the condenser tank 47 into the evaporator tank 27 mixes with the unevaporated refrigerant liquid Vf sprayed from the refrigerant liquid spray nozzle 22 and accumulates in the lower part of the evaporator tank 27. The refrigerant liquid Vf in the evaporator tank 27 flows through the refrigerant pump 29 in the refrigerant liquid pipe 28 and reaches the refrigerant liquid spray nozzle 22. The refrigerant liquid Vf that reaches the refrigerant liquid spray nozzle 22 is sprayed toward the evaporator pipe 21, gains heat from the cold water C flowing in the evaporator pipe 21, and partially evaporates to become evaporator refrigerant vapor Ve, which is then introduced into the absorber tank 17. The temperature of the cold water C, which has lost heat to the sprayed refrigerant liquid Vf, decreases and flows out from the evaporator pipe 21, and is supplied to heat utilization equipment such as air conditioners (not shown). The refrigerant liquid Vf sprayed from the refrigerant liquid spray nozzle 22 but not evaporated mixes with the refrigerant liquid Vf introduced from the condenser tank 47 and accumulates in the lower part of the evaporator tank 27.

[0054] Next, when observing the circulation of the solution S side of the absorption chiller 1, the concentrated solution Sa flowing from the regenerator 30 to the concentrated solution pipe 38 flows in the concentrated solution pipe 38, exchanges heat with the dilute solution Sw in the solution heat exchanger 81 and its temperature decreases, and then reaches the concentrated solution spray nozzle 12. The concentrated solution Sa that reaches the concentrated solution spray nozzle 12 is sprayed toward the cooling pipe 11, absorbs the evaporator refrigerant vapor Ve introduced from the evaporator 20 and its concentration decreases, becoming the dilute solution Sw. In the absorber tank 17, heat absorption is generated when the concentrated solution Sa absorbs the evaporator refrigerant vapor Ve. This heat absorption is removed by the cooling water D flowing in the cooling pipe 11. In this embodiment, the cooling water D flowing in the cooling pipe 11 absorbs the heat absorption and its temperature rises and flows out to the cooling water connecting pipe 14, and is supplied to the condenser pipe 41 of the condenser 40. The dilute solution Sw generated in the absorber tank 17 is stored in the absorber tank 17.

[0055] The dilute solution Sw in absorber tank 17 flows through dilute solution pipe 18 via solution pump 19. After its temperature rises in solution heat exchanger 81, it is introduced into regenerator tank 37. The dilute solution Sw introduced into regenerator tank 37 is heated by the combustion heat of fuel F in burner 71, causing refrigerant V to separate and become concentrated solution Sa. The refrigerant V that has separated from dilute solution Sw by combustion heat is transported as regenerator refrigerant vapor Vg through regenerator refrigerant vapor flow path 35 into condenser tank 47. The concentrated solution Sa generated in regenerator tank 37 flows out into concentrated solution pipe 38.

[0056] If a command to stop the absorption chiller 1 is input, the absorption chiller 1 proceeds to the stop procedure. When the absorption chiller 1 stops, a dilution operation is performed. This dilution operation can also be performed by diluting the absorbent liquid S by transferring the refrigerant liquid Vf accumulated inside the evaporator tank 27 to the inside of the absorber tank 17. Additionally, when the absorption chiller 1 stops, inert gas post-purging is performed on the fuel line 72 and the regenerator 30. During the inert gas post-purging of the fuel line 72, the fuel shut-off valve 74 is closed and the nitrogen shut-off valve 79 is opened. This allows nitrogen N to discharge the fuel F remaining in the fuel line 72 and burner 71 downstream of the fuel shut-off valve 74 into the regenerator 30. At this time, since the air fan 83 continues to operate, the fuel F discharged into the regenerator 30 is released into the atmosphere. If a preset time has elapsed since the inert gas purging of fuel line 72 began, the nitrogen shut-off valve 79 is closed, and if a predetermined time has elapsed, the air fan 83 is stopped. Furthermore, based on the dilution operation described above, the solution pump 19, refrigerant pump 29, cooling water pump 91, and chilled water pump 92 are stopped as needed. Thus, the absorption chiller / hot water unit 1 is brought to a stopped state.

[0057] In the absorption chiller 1 of this disclosure, the fuel F burned in the burner 71 is a gaseous fuel with hydrogen as its main component, and therefore it is easier to ignite than fuels such as city gas, which are mainly composed of hydrocarbons. Because of this, when the absorption chiller 1 is stopped, the conditions for ignition of fuel F are not met; that is, air A and the heat required for ignition are not supplied to fuel F. Therefore, in order to prevent fuel F from remaining in the fuel line 72 downstream of the fuel shut-off valve 74 and inside the burner 71, inert gas purging with nitrogen N (i.e., an inert gas) as described above is usually performed. However, during the operation of the absorption chiller 1, due to certain circumstances such as the cessation of the nitrogen N (i.e., inert gas) supply process or the depletion of nitrogen N in the gas cylinder, a situation may arise where nitrogen N cannot be supplied to the combustion device 70. Conventionally, in the event that inert gas cannot be supplied, the device is immediately stopped and an alarm is issued. However, if such a conventionally conceivable approach is applied to the absorption chiller 1, the inert gas purging of fuel F is not performed, and fuel F remains in the fuel piping 72 and burner 71, causing the high-temperature absorption chiller 1 to stop operating. If, in this state, a portion of the fuel F remaining in the fuel piping 72 and burner 71 is replaced by air, the hydrogen concentration enters the combustion range, potentially creating a risk of combustion inside the fuel piping 72. On the other hand, the inability to supply nitrogen (N) to the combustion unit 70 inherently means that inert gas purging of fuel F cannot be performed, but this does not affect the continued operation of the absorption chiller 1. In view of this situation, the following controls are implemented in the absorption chiller 1 according to this disclosure.

[0058] Figure 4 This is a flowchart illustrating the control of the operation of the absorption chiller / hot water heater 1. In the following control description, when referring to the configuration of the absorption chiller / hot water heater 1, please refer to the relevant documentation as appropriate. Figure 1 and Figure 2Furthermore, the control unit 61 and communication unit 62 are typically operated based on the program stored in the storage unit 63, thereby performing the following control via the control device 60. If the absorption chiller 1, which is in a stopped state, receives a start signal (St1), the control device 60 checks whether the pressure switch 78 is on (St2). If the pressure switch 78 is on (yes in St2), it means that the nitrogen N supplied from the nitrogen source 77 is absent or insufficient, so inert gas purging using nitrogen N cannot be performed, and therefore an error alarm is reported and the start-up process is stopped (St3). On the other hand, if the pressure switch 78 is not on (no in St2), inert gas pre-purging is performed as described above (St4), and then combustion of fuel F in the burner 71 begins (St5). In addition, before and after the start of this combustion (St5), the cooling water pump 91, cold water pump 92, solution pump 19, and refrigerant pump 29 are started in a timely manner as described above, and the absorption chiller 1 returns to normal operation.

[0059] During normal operation of the absorption chiller 1, the control device 60 determines whether the pressure switch 78 is on (i.e., whether the pressure switch 78 receives an on signal) (St6). If the pressure switch 78 is not on (no in St6), the control device 60 determines whether it has received an instruction to stop the absorption chiller 1 (St7). If it has not received an instruction to stop the absorption chiller 1 (no in St7), it returns to the step of determining whether the pressure switch 78 is on during normal operation of the absorption chiller 1 (St6). Thus, normal operation continues. In other words, combustion in the burner 71 required for the normal operation of the absorption chiller 1 continues until an instruction to stop the operation of the absorption chiller 1 is received. On the other hand, if an instruction to stop the absorption chiller 1 is received (yes in St7), the aforementioned inert gas purging is performed (St8), and then the absorption chiller 1 is stopped (St15).

[0060] In the process of determining whether the pressure switch 78 is on during the normal operation of the absorption chiller 1 (St6), if the pressure switch 78 is on (yes in St6), the control device 60 issues a warning (St9). This warning typically notifies relevant personnel (e.g., the manager or user of the absorption chiller 1) that a state where nitrogen (N) cannot be supplied is being addressed. By issuing the warning, relevant personnel are given an opportunity to resolve the defect of a state where nitrogen (N) cannot be supplied. Although the warning report indicates a state where nitrogen (N) cannot be supplied, as described above, the normal operation of the absorption chiller 1 does not require nitrogen (N), therefore, the absorption chiller 1 continues to operate normally without being erroneously stopped, until an instruction to stop the absorption chiller 1 is received.

[0061] If an alarm is reported (St9), the control device 60 determines whether the pressure switch 78 is deactivated (i.e., whether the pressure switch 78 is deactivated) (St10). If the alarm indicates that personnel are unable to supply nitrogen (N), the pressure switch 78 can be deactivated by repairing the process or replacing the cylinder with one filled with nitrogen (N). If the pressure switch 78 is deactivated (yes in St10), the process returns to the step of determining whether the pressure switch 78 is activated during normal operation of the absorption chiller 1 (St6). On the other hand, if the pressure switch 78 is not deactivated (no in St10), the control device 60 determines whether an instruction to stop the absorption chiller 1 has been received (St11). If no instruction to stop the absorption chiller 1 has been received (no in St11), the process returns to the step of determining whether the pressure switch 78 is deactivated (St10). Thus, even if nitrogen (N) cannot be supplied, as long as no instruction is received to stop the absorption chiller 1, the normal operation of the absorption chiller 1 and the combustion in the burner 71 required for the normal operation of the absorption chiller 1 will continue.

[0062] In the process of determining whether an instruction to stop the absorption chiller 1 has been received (St11), if such an instruction is received (yes in St11), the control device 60 determines whether the temperature detected by the concentrated solution thermometer 53 exceeds a predetermined temperature (St12). The predetermined temperature is the temperature at which the absorption chiller 1 is stopped without inert gas purging, resulting in a low probability of ignition of residual fuel F even if it remains in the fuel pipe 72. The predetermined temperature can be, for example, 100°C or approximately 100°C, or any temperature set between 80°C and 120°C.

[0063] If the temperature detected by the concentrated solution thermometer 53 exceeds the specified temperature (in St12), the control device 60 infers that the possibility of ignition of the residual fuel F is not low, and switches the combustion device 70 to low-combustion operation (St13). Low-combustion operation typically suppresses heat generation by reducing the amount of fuel F burned in the burner 71, thereby reducing the temperature of the concentrated solution Sa flowing out of the regenerator 30, in other words, the value detected by the concentrated solution thermometer 53. If low-combustion operation is performed, the temperature of the absorbent S inside the regenerator tank 37 is lowered, thus lowering the temperature of the regenerator tank 37. Even if inert gas purging cannot be performed on the fuel F remaining inside the fuel pipe 72, the possibility of ignition of the fuel F inside the fuel pipe 72 can be reduced. If the combustion device 70 switches to low-combustion operation, the process returns to the step of determining whether the temperature detected by the concentrated solution thermometer 53 exceeds the specified temperature (St12). If the temperature detected by the concentrated solution thermometer 53 does not exceed the specified temperature (no in St12), the control device 60 infers that the possibility of the residual fuel F igniting is low and stops the absorption chiller 1 (St15).

[0064] In addition, such as Figure 5 As shown, if the combustion device 70 is moved to low combustion operation (St13), the absorption chiller 1 can also be stopped (St15) based on the subsequent time elapsed. Figure 5 This is a flowchart illustrating the control of the operation of the absorption chiller 1, as described in the modified example. In this modified example, the following is applied: Figure 4 The flowchart shown continues up to the step of moving the combustion device 70 to low-combustion operation (St13), therefore repeated explanations are omitted. In this modified example, if the combustion device 70 is moved to low-combustion operation (St13), the control device 60 determines whether a predetermined time has elapsed since the move to low-combustion operation (St14). The predetermined time is typically the time required for the absorbent liquid S flowing from the regenerator 30 to decrease to the aforementioned predetermined temperature through low-combustion operation. If the predetermined time has not elapsed (no in St14), the process returns to the step of determining whether the predetermined time has elapsed (St14). On the other hand, if the predetermined time has elapsed (yes in St14), the absorption chiller / hot water heater 1 is stopped (St15).

[0065] As explained above, the absorption chiller 1 according to this embodiment, even if a state of nitrogen N supply failure occurs during normal operation, will not stop due to error and can continue to operate unless an instruction to stop the absorption chiller 1 is received. Furthermore, since a warning is issued in this state, the situation of nitrogen N supply failure can be communicated to relevant personnel, prompting the resolution of the nitrogen N supply failure. Additionally, if a state of nitrogen N supply failure occurs during normal operation and a stop instruction is received, operation is stopped if the absorbent liquid S in the regenerator 30 does not exceed a predetermined temperature, thus reducing the possibility of residual fuel F igniting.

[0066] In the above description, the temperature correlation detector is a concentrated solution thermometer 53 that detects the outlet temperature of the absorbent S in the regenerator 30. However, it can also be a device that detects a physical quantity that is correlated with the temperature of the absorbent S in the regenerator 30 (i.e., correlated with the temperature of the absorbent S). Examples of physical quantities that are correlated with the temperature of the absorbent S in the regenerator 30 include the temperature of the exhaust gas produced when the fuel F is burned in the burner 71, the pressure of the regenerator 30 (typically the pressure of the gas phase inside the regenerator tank 37), and the dew point temperature of the regenerator 30 (typically the dew point temperature of the gas phase inside the regenerator tank 37). In this case, the temperature correlation detector can also be a thermometer that detects the temperature of the exhaust gas, a pressure gauge that detects the internal pressure of the regenerator 30, and a dew point thermometer that detects the dew point temperature inside the regenerator 30, respectively. In this case, the specified value detected by the temperature correlation detector can be any physical quantity that is equivalent to the value detected by the temperature correlation detector when the temperature detected by the concentrated solution thermometer 53 is a specified temperature.

[0067] In the above description, the inert gas detector is a pressure switch 78 that turns on when the pressure is below a specified level, but it can also be a pressure sensor. If a pressure sensor is used as the inert gas detector, and the pressure detected by the pressure sensor is below the specified level, the control device 60 can respond in the same way as when the pressure switch 78 turns on. Alternatively, the inert gas detector can use methods other than pressure detection; for example, when using an inert gas cylinder, it can use a residual gas mass detection method, or it can input a deficiency signal from an external source.

[0068] In the above description, the absorption cycle is single-effect, but a high-temperature regenerator can also be installed to achieve dual-effect or triple-effect operation. In this case, the combustion device 70 can be installed in the regenerator with the highest operating temperature.

[0069] In the above description, the absorption chiller 1 is capable of both cooling and heating hot and cold water, but it can also be a device that only cools or only heats. That is, in this disclosure, the term "absorption chiller" is used for convenience and does not necessarily require the ability to both cool and heat hot water, but is treated as a concept that includes absorption chillers and absorption heat pumps.

Claims

1. An absorption chiller / hot water heater, wherein heat transfer is achieved through the circulation of a refrigerant undergoing a phase change and an absorbent mixture thereof, wherein... The absorption chiller / hot water heater features: The regenerator has a burner that burns a gaseous fuel, primarily composed of hydrogen, to generate heat for heating the absorbent liquid. Fuel piping directs the fuel to the burner; Inert gas piping supplies inert gas to the fuel piping; An inert gas detector detects whether the inert gas can be supplied to the fuel line; and The control device controls the combustion operation in the burner. While the fuel is burning in the burner, if the inert gas detector detects that the inert gas cannot be supplied to the fuel piping, the control device controls the combustion operation in the burner to continue the combustion of the fuel in the burner until it receives an instruction to stop the absorption chiller.

2. The absorption chiller / hot water heater according to claim 1, wherein, While the fuel is burning in the burner, if the inert gas detector detects that the inert gas cannot be supplied to the fuel piping, the control device reports this event.

3. The absorption chiller / hot water heater according to claim 1 or 2, wherein, The absorption chiller / hot water heater is equipped with a temperature correlation detector that detects the temperature of the absorbent liquid in the regenerator or a physical quantity related to that temperature. When the inert gas detector detects that the inert gas cannot be supplied to the fuel piping, and an instruction is received to stop the absorption chiller, if the value detected by the temperature-related value detector exceeds a predetermined value, the control device controls the combustion operation in the burner to perform low-combustion operation, which reduces the amount of combustion in the burner, so that the value detected by the temperature-related value detector is reduced to below the predetermined value, and then the combustion of fuel in the burner is stopped.

4. The absorption chiller / hot water heater according to claim 1 or 2, wherein, The absorption chiller / hot water heater is equipped with a temperature correlation detector that detects the temperature of the absorbent liquid in the regenerator or a physical quantity related to that temperature. When the inert gas detector detects that the inert gas cannot be supplied to the fuel piping, and an instruction is received to stop the absorption chiller, if the value detected by the temperature correlation detector exceeds a predetermined value, the control device controls the combustion operation in the burner to perform low combustion operation that reduces the amount of fuel burned in the burner until a predetermined time has elapsed, and then stops the combustion of the fuel in the burner.

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