Marine thermal system, marine thermal system incorporated into a ship, ship equipped with a marine thermal system, method for controlling a thermal system, and control device.

Abstract

To improve marine thermal systems, marine thermal systems incorporated into ships, ships equipped with marine thermal systems, control methods for thermal systems, and control devices. [Solution] The marine thermal system comprises a thermal fluid circuit (10); a pump system (11) for circulating thermal fluid within the thermal fluid circuit (10); a plurality of thermal consumers (20), which are arranged in parallel in the thermal fluid circuit (10) and in series with their respective pressure-independent control valves (PICVs) (30); and a control device (12) for controlling the pump system (11). A differential pressure sensor (13) is adapted to detect a differential pressure indicating the differential pressure applied to a critical pressure-independent control valve (30.1a), and the signal from the differential pressure sensor (13) is used by the control device (12) as a basis for controlling the pump system.

Description

Technical Field

[0001] The present invention relates to a marine thermal system comprising a thermal liquid circuit; a pump system for circulating a thermal liquid within the thermal liquid circuit; a plurality of thermal consumers arranged in parallel within the thermal liquid circuit and arranged in series with respective pressure independent control valves (PICVs); and a control device for controlling the pump system. The present invention further relates to a ship equipped with a thermal system, a method for controlling the thermal system, and a control device.

Background Art

[0002] In ships of a certain size, thermal systems such as the cooling systems of the above technologies are used to provide cooling to a number of cooling consumers.

[0003] It should be noted that although cooling is the main purpose of the present invention, the present invention can also be used for central heating of ships.

[0004] Therefore, in this specification, the term "thermal" can be understood as either "cooling" or "heating".

[0005] Considering that in many cases about 20% of the ship's power production is used to drive the pumps, reducing the energy demand of the pumps can potentially result in significant energy savings in the operation of the ship.

[0006] Thermal systems, particularly cooling systems, use pumps to circulate a thermal liquid, particularly a cooling liquid, within a liquid circuit that can branch out over a wide area of a ship where cooling is required, i.e., where there are thermal or cooling consumers.

[0007] For the sake of simplicity of explanation, reference will be made to cooling hereinafter.

[0008] Consumer cooling includes engines and other mechanical devices, air conditioners, and the like.

[0009] Under certain circumstances, the cooling demands of various consumers remain relatively constant, but under other circumstances, such as when the engine is running at only a partial load, the cooling demand may be lower than normal.

[0010] In the thermal or cooling systems of the type described in the introduction, the amount of thermal or coolant circulated through a given consumer is controlled by a PICV, or Pressure Independent Control Valve. Such valves are known in the art and include a pressure absorber or mechanism generally known as a differential pressure regulator, which absorbs a portion of the differential pressure applied to the valve, so that another part of the valve can supply at least a substantially desired flow rate through the valve, depending on the remainder of the differential pressure, which is regulated by the pressure absorber of the valve. Thus, the pressure of the remainder is kept constant by the pressure absorber of the valve.

[0011] To properly regulate the flow rate through the PICV, a constant differential pressure needs to be applied to the PICV.

[0012] Therefore, in prior art thermal or cooling systems, the pump system is operated at a level that provides a sufficient differential pressure throughout the entire thermal or cooling system. [Overview of the project] [Problems that the invention aims to solve]

[0013] However, in many cases, the majority of the differential pressure supplied in this way is absorbed by the PIVC within the system, so operating the pump system at a predetermined high level to ensure sufficient differential pressure throughout the thermal or cooling system involves significant energy loss.

[0014] The objective of this invention is to reduce such energy losses. [Means for solving the problem]

[0015] In the first aspect, the objective is achieved in a thermal system of the type described in the introduction, characterized by a differential pressure sensor adapted to detect a differential pressure indicating a differential pressure relating to a critical pressure among pressure-independent control valves, wherein the signal from the differential pressure sensor is used by a control device as the basis for controlling the pump system.

[0016] The term "critical" in relation to multiple pressure-independent control valves (PICVs) should be understood to mean PICVs in a thermal or cooling system where there is a risk of the differential pressure becoming too low if the pump energy drops to too low a level.

[0017] Expressions such as "differential pressure acting on an element (e.g., a valve)" and "differential pressure applied to an element (e.g., a valve)" should be understood to mean the difference between the pressure on the upstream side (directly above) the element and the pressure on the downstream side (directly below) the element.

[0018] When selecting which PICV to consider as the critical PICV in a given thermal or cooling system, it should be understood that the differential pressure requirements of a given PICV may differ from those of another PICV.

[0019] The differential pressure detected or measured by the differential pressure sensor may be the sum of the differential pressures applied to the thermal consumer and the PICV attached to it. In such cases, the measured differential pressure represents the differential pressure applied to the PICV. This is because, if the flow resistance of the thermal client is known at least as an estimated value, the differential pressure applied to the PICV can be calculated or approximated as an indicated differential pressure based on the measured differential pressure and the known or estimated flow resistance of the thermal consumer.

[0020] Regarding the term "pump system," it should be noted that a pump system may consist of a single pump, as is known in the art, or it may consist of multiple pumps operating in parallel or in series.

[0021] In one embodiment, the thermal fluid is water, preferably freshwater. Here, “freshwater” should be understood as being in contrast to the saline water in which ships normally navigate. Therefore, the term “freshwater” should not be understood as excluding additives such as corrosion inhibitors that are typically added to the circulating fluid of a thermal or cooling system.

[0022] In one embodiment, each thermal consumer is placed in series with a pressure-independent control valve, so that the total flow rate of the thermal fluid is controlled and balanced by the pressure-independent control valve. This enables excellent flow control of the thermal or coolant at all points in the system.

[0023] In one embodiment, at least one first thermal consumer is arranged in series with a controllable pressure-independent control valve, preferably a pressure and / or temperature sensor is attached to the first thermal consumer and provides a control signal for controlling the controllable pressure-independent control valve. The controllable pressure-independent control valve is known in the art and may comprise a valve body whose position is controlled by a control element, which itself can receive input from, for example, a temperature sensor, thereby adjusting the position of the valve body to regulate the flow rate through the PICV, i.e., the flow rate through a thermal or cooling consumer attached to the PICV, thereby allowing the temperature detected by the sensor to be kept substantially constant or according to a given scheme. The control element may also receive input from a pressure sensor, or the PICV may be controlled by an external signal, such as an operating signal from a motor, or another external signal from individual consumers requiring cooling or heating.

[0024] The control of the PICV controllable based on temperature can be performed based on a temperature difference as an alternative or supplement to a specific temperature. Thus, for example, the temperature measurements for control, from which the temperature difference across each consumer can be measured to provide a temperature difference signal for controlling the controllable PICV, may be obtained from the thermal fluid in a strict sense, either from a specific temperature or a temperature difference, or may be obtained from the fluid on the second side of a heat exchanger through which the thermal fluid of the thermal fluid circuit flows on the first side.

[0025] Regardless of whether it is a specific temperature or a temperature difference, controlling the PICV based on temperature can be combined with, for example, controlling based on an operation signal. In such a case, it is possible to adjust the PICV to fully open when receiving an operation signal prior to receiving a temperature signal when starting one of the devices such as an engine as each consumer. This can avoid trips of the device due to too little cooling because the response of the temperature measurement from the cooling / thermal fluid to the rapid heat generation at the start of the device is slow.

[0026] In one embodiment, the second thermal consumer comprises a further minor thermal consumer, which is arranged in parallel or in series and is arranged in series in common with each second pressure-independent control valve. Thereby, the number of PICVs in the thermal system can be reduced compared to a system in which all consumers are attached to their own PICVs.

[0027] In one embodiment, a further differential pressure sensor is provided adapted to detect the respective differential pressure indicating the differential pressure of each pressure-independent control valve. In particular, it is foreseen that each PICV has its own differential pressure sensor or that a differential pressure sensor is attached to it. This may be appropriate, for example, in a thermal system where it is difficult or impossible to determine which PICV is the critical PICV. This is the case, for example, in a thermal system where a certain thermal consumer is occasionally shut down and substantially removed from the thermal system (the active part of it). In such embodiments, a control device for controlling the pump system may be adapted to use the indicated differential pressure closest to the differential pressure required for each pressure-independent control valve as the basis for controlling the pump system. Therefore, it is desirable that the control device has information on differential pressure requests for multiple PICVs (PICVs) whose differential pressure is measured, calculated, or indicated, and for each of these PICVs, compare the differential pressure request with the measured, calculated, or indicated differential pressure of that PICV to determine which PICV has the smallest difference between the measured, calculated, or indicated differential pressure and the differential pressure request, and then use the differential pressure applied to that PICV as the basis for controlling the pump system.

[0028] Pressure measurement can be incorporated into the PICV via a built-in PT-plug or via a permanently mounted pressure (differential) sensor. The output signal from such a pressure sensor may be transmitted to a control unit individually, or it may be incorporated into the PICV's actuator and transmitted from there to the control unit. A communication network (such as MODBUS®) can be used in this regard. Thus, the PICV and / or their respective actuators can constitute a network for controlling the pump rate.

[0029] In one embodiment, the thermal system further includes a central thermal unit; a branch of the thermal fluid circuit passing through the central thermal unit; a bypass of the thermal fluid circuit bypassing the central thermal unit; a three-way valve for controlling the flow rate passing through the branch and the flow rate passing through the bypass; a temperature sensor for measuring the flow temperature downstream from the branch and the bypass; and a controller for controlling the three-way valve according to a signal from the temperature sensor. The central thermal unit can supply a thermal fluid at a lower or higher temperature according to whether the thermal system is a cooling system or a heating system. By means of the three-way valve, the fluid from the central thermal unit is mixed with the thermal fluid flowing through the thermal fluid circuit, and a desired flow temperature in the thermal fluid circuit can be obtained.

[0030] In another embodiment, the thermal system includes a central thermal unit, which includes a heat exchanger having a primary side and a secondary side. The primary side is part of the thermal fluid circuit of the thermal system, and the secondary side of the central thermal unit is supplied with a second thermal fluid by a heat exchanger pump system. The thermal system further includes a branch of the thermal fluid circuit passing through the central thermal unit; a bypass of the thermal fluid circuit bypassing the central thermal unit; a three-way valve for controlling the flow rate passing through the branch and the flow rate passing through the bypass; a temperature sensor for measuring the flow temperature downstream from the branch and the bypass; and a controller for controlling the pump system of the heat exchanger in response to a signal from the temperature sensor. In this embodiment, the central thermal unit can provide a thermal fluid at a lower or higher temperature according to whether the thermal system is a cooling system or a heating system, and by adjusting the energy supplied to the pump system of the heat exchanger, and thus adjusting the operating level of the pump system of the heat exchanger, the amount of heat transferred in the heat exchanger can be adjusted, whereby the flow temperature in the thermal fluid circuit can be adjusted to approach the desired flow temperature in the thermal fluid circuit.

[0031] In a further embodiment, the controller is adapted to control the three-way valve in response to signals from at least a temperature sensor. This makes it possible, for example, to reduce the amount of cooling or heating introduced into the thermal fluid circuit to the minimum amount that the central thermal unit can transmit.

[0032] In a second embodiment, the objective is achieved by a vessel equipped with a thermal system according to the present invention.

[0033] In a third aspect, the invention is obtained by a method for controlling the thermal system according to the present invention outlined above, which includes: circulating thermal fluid in a thermal fluid circuit by a pump system; obtaining a signal from a differential pressure sensor indicating the differential pressure on a critical pressure-independent control valve; and adjusting the power of the pump system to obtain a signal from the differential pressure sensor within a desired range of values. As a result, energy losses can be reduced.

[0034] In one embodiment, the thermal system includes further differential pressure sensors adapted to detect each differential pressure indicating the differential pressure across each pressure-independent control valve, and the method includes determining the minimum required value of the signal provided by each differential pressure sensor for each of the differential pressure sensors, and adjusting the power of the pump system in accordance with the signal of one of the differential pressure sensors that provides the lowest value signal for each minimum required value. In such an embodiment, the control device controlling the pump system may be adapted to use the indicated differential pressure closest to the required differential pressure of each pressure-independent control valve as the basis for controlling the pump system. Thus, it is desirable that the control device has differential pressure request information for a plurality of PICVs whose differential pressure is measured, calculated, or indicated, and for each of these plurality of PICVs, it compares the differential pressure request with the measured, calculated, or indicated differential pressure of the respective PICV to determine which PICV has the smallest difference between the measured, calculated, or indicated differential pressure and the differential pressure request, and uses the differential pressure across that PICV as the basis for controlling the pump system.

[0035] In one embodiment, at least one first thermal consumer is arranged in series with a controllable pressure-independent control valve, and a pressure and / or temperature sensor is attached to the first thermal consumer, and the method includes obtaining a control signal from the pressure and / or temperature sensor and adjusting the controllable pressure-independent control valve depending on the control signal from the pressure and / or temperature sensor. In such an embodiment, the temperature detected by the sensor can be kept substantially constant or according to a given scheme.

[0036] In one embodiment, the thermal system comprises a central thermal unit; a branch of a thermal fluid circuit passing through the central thermal unit; a bypass of the thermal fluid circuit bypassing the central thermal unit; a three-way valve for controlling the flow rate through the branch and the bypass; and a temperature sensor for measuring the flow temperature downstream from the branch and the bypass. The method includes acquiring a temperature signal from the temperature sensor and controlling the three-way valve in accordance with the temperature signal from the temperature sensor. The central thermal unit can supply a lower or higher temperature thermal fluid depending on whether the thermal system is a cooling system or a heating system, and the liquid from the central thermal unit is mixed by the three-way valve with the thermal fluid flowing through the thermal fluid circuit to obtain a desired flow temperature in the thermal fluid circuit.

[0037] In one embodiment, the thermal system is a central thermal unit; the central thermal unit comprises a heat exchanger having a primary side and a secondary side, the primary side being part of the thermal fluid circuit of the thermal system, and the secondary side of the central thermal unit being supplied with a second thermal fluid by a pump system of the heat exchanger; a branch of the thermal fluid circuit passing through the central thermal unit; a bypass of the thermal fluid circuit bypassing the central thermal unit; a three-way valve controlling the flow rate through the branch and the bypass; and a temperature sensor measuring the flow temperature downstream from the branch and the bypass, wherein the method includes acquiring a temperature signal from the temperature sensor and controlling the heat exchanger in accordance with the temperature signal from the temperature sensor. In this embodiment, the central thermal unit can supply a lower or higher temperature thermal fluid depending on whether the thermal system is a cooling system or a heating system, and can adjust the amount of heat transferred in the heat exchanger by adjusting the energy supplied to the heat exchanger's pump system, thereby adjusting the operating level of the heat exchanger's pump system, and thereby adjusting the flow temperature of the thermal fluid circuit to approach a desired flow temperature in the thermal fluid circuit.

[0038] In a further embodiment, the present invention includes a control device for a thermal system, the control device being adapted to perform the method described above.

[0039] Embodiments and advantages described with reference to one aspect of the present invention apply to other aspects unless otherwise specified.

[0040] The present invention will be described in more detail below with reference to the following schematic diagram, illustrating an example of an embodiment. [Brief explanation of the drawing]

[0041] [Figure 1] Figure 1 is a diagram showing the configuration of the cooling system according to the present invention. [Figure 1a] Figure 1a shows an alternative embodiment of the cooling system according to the present invention. [Figure 2] Figure 2 shows the characteristics of PICV in pressure / flow rate mode. [Modes for carrying out the invention]

[0042] Figure 1 shows a thermal system, particularly a cooling system, that is incorporated into a ship.

[0043] The system comprises a coolant circuit 10; a pump system 11 for circulating coolant within the coolant circuit 10, which in this embodiment is represented by a single pump symbol; a plurality of cooling consumers 20, the cooling consumers 20 arranged in parallel within the coolant circuit 10, and the cooling consumers 20 arranged in series with their respective pressure-independent control valves (PICVs) 30; and a control device 12 for controlling the pump system 11.

[0044] The system includes a differential pressure sensor 13 adapted to detect a differential pressure indicating the differential pressure across a critical pressure 30.1a of the pressure-independent control valves 30.

[0045] In this embodiment, the coolant circulating within the coolant circuit 10 is fresh water to which a conventional rust inhibitor or the like has been added.

[0046] In this embodiment, each of the cooling consumers 20 is arranged in series with a pressure-independent control valve 30, thereby controlling and balancing the total flow rate of the coolant by the pressure-independent control valve 30.

[0047] A group of first cooling consumers 20.1 are each arranged in series with a controllable first pressure-independent control valve 30.1. A pressure sensor and / or temperature sensor 20.11 is attached to each first cooling consumer 20.1 to supply control signals for controlling the controllable first pressure-independent control valve 30.1.

[0048] In this embodiment, the second cooling consumer 20.2 comprises further (two shown in this example) small cooling consumers 20.2a, which are arranged in parallel such that the small cooling consumers are shared in series with each pressure-independent control valve 30.2.

[0049] In this embodiment, a group of third cooling consumers 20.3, each in series with a third pressure-independent control valve 30.3, are shared and arranged in series with a fourth cooling consumer 20.3a, which has less demand for lower cooling water temperatures. Therefore, the flow rate through the fourth cooling consumer 20.3a is equal to the total amount of combined flow through the third cooling consumers 20.3.

[0050] The cooling system further includes a central cooling unit 40.

[0051] Branch 10.1 of the coolant circuit passes through the central cooling unit 40, and bypass 10.2 of the coolant circuit bypasses the central cooling unit 40. A three-way valve 10.3 controls the flow rate through branch 10.1 and bypass 10.2. A temperature sensor 10.4 measures the temperature downstream from branch 10.1 and bypass 10.2. A controller 10.5 is provided to control the three-way valve 10.3 in response to signals from the temperature sensor 10.4.

[0052] The central cooling unit 40 supplies cooler coolant compared to the coolant circulating in the coolant circuit 10, and especially compared to the coolant entering the three-way valve 10.3. The three-way valve 10.3 mixes the cooler coolant from the central cooling unit 40 with the coolant flowing in the coolant circuit 10, allowing the desired flow temperature in the coolant circuit 10 to be obtained by measurement with the temperature sensor 10.4.

[0053] The central cooling unit 40 includes a heat exchanger 40.1 having a primary side 40.1a and a secondary side. The primary side 40.1a is part of the cooling fluid circuit 10 of the cooling system. The secondary side 40.1b of the central cooling unit 40 is supplied with a second thermal fluid by a heat exchanger pump system 40.2. In the illustrated embodiment, the second thermal fluid is seawater taken in from the surrounding seawater where the ship is navigating through a seawater intake 40.3, circulated by the heat exchanger pump system 40.2 through the secondary side 40.1b of the heat exchanger 40.1, and discharged into the surrounding seawater through a seawater outlet 40.4.

[0054] In one embodiment, a controller, such as a control device 12, is adapted to control a heat exchange pump system 40.2 in response to a signal from a temperature sensor 10.4.

[0055] In such embodiments, the central cooling unit 40 can cool the entire volume of water circulating in the cooling fluid circuit by adjusting the three-way valve 10.3 to shut off the bypass 10.2 and allow all the water to pass through the heat exchanger 40.1. The amount of heat transferred in the heat exchanger can be adjusted by adjusting the energy supplied to the heat exchanger pump system 40.2, thereby adjusting the operating level of the heat exchanger pump system 40.2, and thereby adjusting the flow temperature of the thermal fluid circuit indicated by the temperature sensor 10.4 to approximate a desired flow temperature.

[0056] Furthermore, in such embodiments, the control device 12 can be adapted to also control the three-way valve 10.3 or activate the controller 10.5 in response to signals from at least the temperature sensor 10.4. This makes it possible, for example, to reduce the amount of cooling introduced into the thermal fluid circuit 10 to the minimum amount that the central thermal unit 40 can transmit.

[0057] As shown above, each cooling consumer 20 is arranged in series with a pressure-independent control valve 30, thereby controlling and balancing the flow rate of the coolant in the coolant circuit 10 by the pressure-independent control valve 30.

[0058] Each pressure-independent control valve 30 requires a certain minimum differential pressure to control the flow rate intended for each pressure-independent control valve 30. This differential pressure is supplied to the entire coolant circuit 10 by the pump system 11.

[0059] To reduce the power supplied to the pump system 11 to the minimum necessary to ensure sufficient differential pressure at all points in the coolant circuit 10, the differential pressure sensor 13 provides an indication of the differential pressure applied to the critical pressure-independent control valve 30.1a, and the pump system 11 is adjusted by the control device 12 according to the above indication of the differential pressure applied to the critical pressure-independent control valve 30.1a. This allows for significant energy savings compared to a system where the pump system operates continuously at a predetermined power level.

[0060] Figure 1a shows an alternative embodiment in which, as exemplified by differential pressure sensor 13a, further differential pressure sensors are provided adapted to detect respective differential pressures indicating the differential pressure across each pressure-independent control valve 30, and the control device 12 for controlling the pump system 11 is adapted to use the indicated differential pressure closest to the differential pressure required for each pressure-independent control valve as the basis for controlling the pump system. In particular, it is foreseen that each pressure-independent control valve 30 is equipped with or fitted with its own differential pressure sensor.

[0061] Figure 2 illustrates how a substantially constant flow rate is supplied by each pressure-independent control valve 30 in the coolant circuit 10 (assuming all pressure-independent control valves 30 are intended to supply the same flow rate). Pmin indicates the minimum differential pressure required by the critical pressure-independent control valve 30.1a. The pump system 11 is tuned to operate at a rate that provides the pressure Pc indicated by the differential pressure sensor 13 to the critical pressure-independent control valve 30.1a. Due to general pressure losses within the coolant circuit 10, the minimum differential pressure is located near the critical pressure-independent control valve 30.1a, while higher differential pressures exist throughout the rest of the coolant circuit 10, as indicated by Psyst in Figure 2. As is well known to those skilled in the art, the differential pressure regulators of each pressure-independent control valve 30 absorb excess pressure in each valve to provide the desired flow rate as shown in Figure 2. [Aspect 1] A thermal system for ships, Thermal fluid circuit (10) and; A pump system (11) for circulating thermal fluid within the thermal fluid circuit (10); a plurality of thermal consumers (20), each arranged in parallel within the thermal fluid circuit (10) and in series with its respective pressure-independent control valve (PICVs) (30); A thermal system for a ship, comprising a control device (12) for controlling the pump system (11), A thermal system characterized by a differential pressure sensor (13) adapted to detect a differential pressure indicating the differential pressure of a critical pressure among the pressure-independent control valves (30.1a), wherein the signal from the differential pressure sensor (13) is used by the control device (12) as the basis for controlling the pump system. [Aspect 2] The thermal system according to embodiment 1, wherein the thermal fluid is water, preferably fresh water. [Aspect 3] A thermal system according to embodiment 1 or 2, wherein each of the multiple thermal consumers (20.1, 20.2, 20.3, 20.3a) is arranged in series with a pressure-independent control valve (30.1, 30.1a, 30.2, 30.3), and the total flow rate of the thermal fluid is controlled and balanced by the pressure-independent control valve (30.1, 30.1a, 30.2, 30.3). [Aspect 4] A thermal system according to any one of embodiments 1 to 3, wherein at least one first thermal consumer (20.1) is arranged in series with a controllable pressure-independent control valve (30.1, 30.1a), and preferably a pressure sensor and / or temperature sensor (20.11) is attached to the first thermal consumer (201) to provide a control signal for controlling the controllable pressure-independent control valve (30.1, 30.1a). [Aspect 5] A thermal system according to any one of embodiments 1 to 4, wherein the second thermal consumer (20.2) comprises further smaller thermal consumers (20.2a, 20.2b) arranged in parallel and / or in series, and shared in series with each second pressure-independent control valve (30.2). [Aspect 6] A further differential pressure sensor (13, 13a) is provided adapted to detect a differential pressure indicating a differential pressure across each pressure-independent control valve, and preferably the control device for controlling the pump system is adapted to use the indicated differential pressure closest to the differential pressure required for each pressure-independent control valve as the basis for controlling the pump system, according to any one of embodiments 1 to 5. [Aspect 7] Central thermal unit (40) and; The branch (10.1) of the thermal fluid circuit (10) passes through the central thermal unit (40); A bypass (10.2) of the thermal fluid circuit (10) that bypasses the central thermal unit (40); A three-way valve (10.3) controls the flow rate through the branch (10.1) and the flow rate through the bypass (10.2); A temperature sensor (10.4) for measuring the flow temperature downstream from the branch (10.1) and the bypass (10.2); The thermal system according to any one of embodiments 1 to 6, further comprising a controller (10.5) for controlling the three-way valve (10.3) in response to a signal from the temperature sensor (10.4). [Aspect 8] The central thermal unit (40) is; The central thermal unit (40) comprises a heat exchanger (40.1) having a primary side (40.1a) and a secondary side (40.1b), the primary side (40.1a) being part of the thermal fluid circuit (10) of the thermal system, and the secondary side (40.1b) of the central thermal unit (40) being supplied with a second thermal fluid by a heat exchanger pump system (40.2); The branch (10.1) of the thermal fluid circuit (10) passes through the central thermal unit (40); A bypass (10.2) of the thermal fluid circuit (10) that bypasses the central thermal unit (40); A three-way valve (10.3) controls the flow rate through the branch (10.1) and the flow rate through the bypass (10.2); A temperature sensor (10.4) for measuring the flow temperature downstream from the branch (10.1) and the bypass (10.2); The thermal system according to any one of embodiments 1 to 6, further comprising a controller (12) for controlling the heat exchanger pump system (40.2) in response to a signal from the temperature sensor (10.4). [Aspect 9] The thermal system according to embodiment 8, wherein the controller (12) is also adapted to control the three-way valve (10.3) in response to a signal from at least the temperature sensor (10.4). [Aspect 10] The thermal system is a cooling system, as described in any one of embodiments 1 to 9. [Aspect 11] The thermal system is a thermal system according to any one of embodiments 1 to 10, which is incorporated into a ship. [Aspect 12] A ship equipped with a thermal system as described in any one of embodiments 1 to 11. [Aspect 13] A method for controlling a thermal system according to any one of embodiments 1 to 11, The pump system (11) circulates the thermal fluid within the thermal fluid circuit (10); The differential pressure signal is obtained from the differential pressure sensor (13) for the critical pressure of the pressure-independent control valve (30.1a); A method comprising adjusting the power of the pump system (11) so as to obtain a signal from the differential pressure sensor (13) of a value within a desired range. [Aspect 14] The thermal system comprises further differential pressure sensors (13, 13a) adapted to detect each differential pressure indicating the differential pressure across a plurality of pressure-independent control valves (30), and the method comprises, for each of the differential pressure sensors, determining a minimum required value of the signal provided from each of the differential pressure sensors, and adjusting the power of the pump system depending on the signal from one of the differential pressure sensors that provides the lowest value signal for each of the minimum required values, the method according to embodiment 13. [Aspect 15] The method according to embodiment 13 or 14, wherein at least one first thermal consumer (20.1) is arranged in series with a controllable pressure-independent control valve (30.1, 30.1a), and a pressure sensor and / or temperature sensor (20.11) is attached to the first thermal consumer (201), and the method comprises obtaining a control signal from the pressure sensor and / or the temperature sensor (20.11) and adjusting the controllable pressure-independent control valve (30.1, 30.1a) in reliance on the control signal from the pressure sensor and / or the temperature sensor (20.11). [Aspect 16] The aforementioned thermal system is Central thermal unit (40) and; The branch (10.1) of the thermal fluid circuit (10) passes through the central thermal unit (40); A bypass (10.2) of the thermal fluid circuit (10) that bypasses the central thermal unit (40); A three-way valve (10.3) controls the flow rate through the branch (10.1) and the flow rate through the bypass (10.2); The system includes a temperature sensor (10.4) that measures the flow temperature downstream from the branch (10.1) and the bypass (10.2), The method according to any one of embodiments 13 to 15, comprising acquiring a temperature signal from the temperature sensor (10.4) and controlling the three-way valve (10.3) in accordance with the temperature signal from the temperature sensor (10.4). [Aspect 17] The aforementioned thermal system is The central thermal unit (40) is; The central thermal unit (40) comprises a heat exchanger (40.1) having a primary side (40.1a) and a secondary side (40.1b), the primary side (40.1a) being part of the thermal fluid circuit (10) of the thermal system, and the secondary side (40.1b) of the central thermal unit (40) being supplied with a second thermal fluid by a heat exchanger pump system (40.2); The branch (10.1) of the thermal fluid circuit (10) passes through the central thermal unit (40); A bypass (10.2) of the thermal fluid circuit (10) that bypasses the central thermal unit (40); A three-way valve (10.3) controls the flow rate through the branch (10.1) and the flow rate through the bypass (10.2); A temperature sensor (10.4) for measuring the flow temperature downstream from the branch (10.1) and the bypass (10.2); The method according to any one of embodiments 13 to 16, comprising acquiring a temperature signal from the temperature sensor (10.4) and controlling the heat exchanger pump system (40.2) in accordance with the temperature signal from the temperature sensor (10.4). [Aspect 18] A control device (10.5, 12) for a thermal system according to any one of embodiments 1 to 11, wherein the control device (10.5, 12) is adapted to perform the method described in any one of embodiments 13 to 17.

Claims

1. A thermal system for ships, Thermal fluid circuit (10) and; A pump system (11) for circulating thermal fluid within the thermal fluid circuit (10); a plurality of thermal consumers (20), each arranged in parallel within the thermal fluid circuit (10) and in series with its respective pressure-independent control valve (PICVs) (30); A thermal system for a ship, comprising a control device (12) for controlling the pump system (11), A thermal system characterized by a differential pressure sensor (13) adapted to detect a differential pressure indicating a differential pressure relating to a critical pressure among the pressure-independent control valves (30.1a), wherein the signal from the differential pressure sensor (13) is used by the control device (12) as a basis for controlling the pump system by adjusting the power of the pump system (11) so that the signal from the differential pressure sensor (13) is within a desired range.

2. The thermal system according to claim 1, wherein the thermal fluid is water.

3. The thermal system according to claim 1 or 2, wherein each of the multiple thermal consumers (20.1, 20.2, 20.3, 20.3a) is arranged in series with the pressure-independent control valves (30.1, 30.1a, 30.2, 30.3), and the total flow rate of the thermal fluid is controlled and balanced by the pressure-independent control valves (30.1, 30.1a, 30.2, 30.3).

4. The thermal system according to claim 1 or 2, wherein at least one first thermal consumer (20.1) is arranged in series with a controllable pressure-independent control valve (30.1, 30.1a), and a pressure sensor and / or temperature sensor (20.11) is attached to the first thermal consumer (20.1) to provide a control signal for controlling the controllable pressure-independent control valve (30.1, 30.1a).

5. The thermal system according to claim 1 or 2, wherein the second thermal consumer (20.2) comprises further smaller thermal consumers (20.2a, 20.2b) arranged in parallel and / or in series, and arranged in series in common with each second pressure-independent control valve (30.2).

6. The thermal system according to claim 1 or 2, wherein further differential pressure sensors (13, 13a) are provided adapted to detect the respective differential pressures representing the differential pressures applied to each pressure-independent control valve.

7. Central thermal unit (40) and; The branch (10.1) of the thermal fluid circuit (10) passes through the central thermal unit (40); A bypass (10.2) of the thermal fluid circuit (10) that bypasses the central thermal unit (40); A three-way valve (10.3) controls the flow rate through the branch (10.1) and the flow rate through the bypass (10.2); A temperature sensor (10.4) for measuring the flow temperature downstream from the branch (10.1) and the bypass (10.2); The thermal system according to claim 1 or 2, further comprising a controller (10.5) for controlling the three-way valve (10.3) in response to a signal from the temperature sensor (10.4).

8. A central thermal unit (40) comprising a heat exchanger (40.1) having a primary side (40.1a) and a secondary side (40.1b), wherein the primary side (40.1a) is part of the thermal fluid circuit (10) of the thermal system, and the secondary side (40.1b) of the central thermal unit (40) is supplied with a second thermal fluid by a heat exchanger pump system (40.2); The branch (10.1) of the thermal fluid circuit (10) passes through the central thermal unit (40); A bypass (10.2) of the thermal fluid circuit (10) that bypasses the central thermal unit (40); A three-way valve (10.3) controls the flow rate through the branch (10.1) and the flow rate through the bypass (10.2); A temperature sensor (10.4) for measuring the flow temperature downstream from the branch (10.1) and the bypass (10.2); The thermal system according to claim 1 or 2, further comprising a controller (12) for controlling the heat exchanger pump system (40.2) in response to a signal from the temperature sensor (10.4).

9. The thermal system according to claim 8, wherein the controller (12) is also adapted to control the three-way valve (10.3) in response to a signal from at least the temperature sensor (10.4).

10. The thermal system according to claim 1 or 2, wherein the thermal system is a cooling system.

11. The thermal system is the thermal system according to claim 1 or 2, which is incorporated into a ship.

12. A ship comprising the thermal system described in any one of claims 1 to 11.

13. A method for controlling a thermal system according to any one of claims 1 to 11, The pump system (11) circulates the thermal fluid within the thermal fluid circuit (10); To obtain a signal from the differential pressure sensor (13) indicating the differential pressure of the critical pressure of the pressure-independent control valve (30.1a); A method comprising adjusting the power of the pump system (11) so as to obtain a signal from the differential pressure sensor (13) of a value within a desired range.

14. The thermal system comprises further differential pressure sensors (13, 13a) adapted to detect each differential pressure indicating the differential pressure across a plurality of pressure-independent control valves (30), the method comprising, for each of the differential pressure sensors, determining a minimum required value of the signal provided by each of the differential pressure sensors, and adjusting the power of the pump system depending on the signal from one of the differential pressure sensors that provides the lowest value signal for each of the minimum required values, the method according to claim 13.

15. The method according to claim 13 or 14, wherein at least one first thermal consumer (20.1) is arranged in series with a controllable pressure-independent control valve (30.1, 30.1a), and a pressure sensor and / or temperature sensor (20.11) is attached to the first thermal consumer (201), the method comprising obtaining a control signal from the pressure sensor and / or the temperature sensor (20.11), and adjusting the controllable pressure-independent control valve (30.1, 30.1a) in accordance with the control signal from the pressure sensor and / or the temperature sensor (20.11).

16. The aforementioned thermal system is Central thermal unit (40) and; The branch (10.1) of the thermal fluid circuit (10) passes through the central thermal unit (40); A bypass (10.2) of the thermal fluid circuit (10) that bypasses the central thermal unit (40); A three-way valve (10.3) controls the flow rate through the branch (10.1) and the flow rate through the bypass (10.2); The system includes a temperature sensor (10.4) for measuring the flow temperature downstream from the branch (10.1) and the bypass (10.2), The method according to any one of claims 13 to 15, comprising acquiring a temperature signal from the temperature sensor (10.4) and controlling the three-way valve (10.3) in accordance with the temperature signal from the temperature sensor (10.4).

17. The aforementioned thermal system is The central thermal unit (40) is; The central thermal unit (40) comprises a heat exchanger (40.1) having a primary side (40.1a) and a secondary side (40.1b), the primary side (40.1a) being part of the thermal fluid circuit (10) of the thermal system, and the secondary side (40.1b) of the central thermal unit (40) being supplied with a second thermal fluid by a heat exchanger pump system (40.2); The branch (10.1) of the thermal fluid circuit (10) passes through the central thermal unit (40); A bypass (10.2) of the thermal fluid circuit (10) that bypasses the central thermal unit (40); A three-way valve (10.3) controls the flow rate through the branch (10.1) and the flow rate through the bypass (10.2); A temperature sensor (10.4) for measuring the flow temperature downstream from the branch (10.1) and the bypass (10.2); The method according to any one of claims 13 to 16, comprising acquiring a temperature signal from the temperature sensor (10.4) and controlling the heat exchanger pump system (40.2) in accordance with the temperature signal from the temperature sensor (10.4).

18. A control device (10.5, 12) for a thermal system according to any one of claims 1 to 11, the control device (10.5, 12) adapted to perform the method described in any one of claims 13 to 17.

19. The thermal system according to claim 6, wherein the control device for controlling the pump system is adapted to use the indicated differential pressure closest to the differential pressure required for each of the pressure-independent control valves as the basis for controlling the pump system.

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