The Technical Field of the Invention

The present invention relates to a method and a system for optimal use of heat produced in a thermal system on board a marine unit, the thermal system comprises one or more heat generating units and one or more heat consumer units with a pipeline and valve system associated therewith for circulation of thermal fluid between the various units, the heat generating unit(s) comprising at least one fuel fired heater; at least one thermal fluid cooling unit selected from the group of a cooling system on one or more engines, exhaust gas economizer associated with the exhaust line(s) from the one or more engines and/or incinerator(s).

Background of the Invention

For central heating production in a thermal system on board a marine unit, each unit producing a work or generating heat is provided with heat exchangers in order to cool down to and maintain the unit at a predefined temperature and exchange such recovered energy to a circulating cooling fluid. Such units may for example be a motor, the exhaust system associated with such motors, and fuel powered combustors. The fuel powered combustor may optionally be connected to the system, depending on the availability and sufficiency of green energy delivered from the other units. Also other systems such as waste incinerators, etc. may be incorporated into the thermal system. The various units may be interconnected by means of a piping or circulation pipes, connection the various units in parallel and comprising manifolds and valves. The circulation of the cooling fluid may be driven by a main circulation pump, delivering heat to various customer units on board the vessel.

Two publication, published by Aalborg Industries (Enclosure 1) describe a system for retrieving waste heat from a main motor of a vessel and also a separate system for retrieving heat from auxiliary engines. There is no information in said publications of a control system for controlling the supply and recovery of the separate heat generating units.

It is a need for economizing the entire energy production and delivery on board a vessel, avoiding dependency of using addition non-renewal fuel and/or eliminating the need for production of electricity production as much as possible. It is also a need for an optimized use and take-out of recovered energy as much as possible.

Summary of the Invention

When referred to the term "green energy" below, the following type of energy is meant: Heat which is recovered as a secondary energy source from an working engine, and which otherwise would be lost if not recovered, such type of energy being for example the energy recovered from engine cooling systems, energy recovered from cooling down the flue gases produced by combustion in an engine, heat recovered from the an incinerator, heat produced as a secondary effect in other types of working machinery or in air conditioning systems, sewage, etc..

An object of the invention is to provide a method and a system for reducing the energy consumption required for heating heat requiring means onboard a marine installation or a vessel.

Another object of the present invention is to enable optimal use of energy produced by the machinery onboard a vessel during periods with variable loads on the vessel machinery, such as for a service or supply vessel working offshore, a vessel which frequently have to maneuver in and out of and/or along the costal line, etc.

Another object is to recover and utilize green energy as much as possible for delivery of heat to heat consuming apparatus, equipment and machinery.

Another object of the invention is to provide a method and a system for providing a more economical and a more optimal use of generated heat, thus requiring reducing the need for burning additional fuel in order to heat various systems.

Yet another object of the invention is to use waste energy produced by engines and incineration systems in a sustainable manner. A further object of the present invention is to reduced the total fuel consumption for powering and operating a vessel.

The objects are achieved by means of a method and a system as further defined by the independent claims, while embodiments and alternatives are defined by the dependent claims.

According to the present invention sanitary water generator is integrated into the fuel powered combustor, allowing water heated by "green heat" to pass through the combustor in order to become further heated.

A further feature of the present invention is that controlled valves are associated with the various parallel units and piping system are fitted into the parallel circuit for each unit of the thermal system. The control of the valve is achieved by means of a control consol, for example centrally arranged in the engine room of the vessel. By means of such controlled valves and the control consol it is possible to achieve a balanced flow through the entire system, directing the flow to units producing heat at any instant and/or directing heated water to units requiring heat. If no heat is produced, then there is no circulation of heat transferring water. The system may further be provided with one or more by-pass lines with corresponding controlled valves, enhancing the controlled and balanced, adjustable flow in the system, thus together with the control of the other valves of the system, securing an optimal flow delivering the required volume of heat to the requiring unit as and when needed.

The system also includes sensors and meters for measuring flow rates, pressure and the temperature at relevant points in the system. The sensed values provided by said sensors are used for achieving automatic control of the controlled valves, achieving optimal reduction in use of fuel for operating the vessel.

According to the invention, heat from the cooling systems of the heat generating units is recovered and used for delivering heat to heat consumers, the thermal system being configured in such way that heat recovered from the heat recovery generators is primarily utilized and that heat delivered from the conven- tional fuel burners is used only or as a supplement if the heat from the heat recovery generators is not sufficient for the intended purpose. In particular, but not exclusively, temperatures, pressures and/or flow are measured by sensors arranged on the various units of the thermal system, such measurements being transmitted to a computer system where the values are compared against set values and where control signals are communicated to automated valves for opening or closing of such valves in order to achieve an optimal delivery of heat to the heat consuming unit(s).

The heat generating unit(s) and the heat consuming unit(s) may preferably be divided into separate temperature circuits and connected together for optimal energy saving. Further, the thermal fluid circulation lines for each thermal generating units, and each circulation line for the heat consuming units may preferably be arranged in parallel, allowing individual supply of heat from or to said units, dependent on level of available heat.

According to the present invention the thermal fluid may be circulated in a forced manner in the pipeline system by means of at least two circulation pumps, the running and stand-by of the pumps being controlled by a control unit, dependent on available heat and the required flow of thermal fluid for meeting the set values for the heat consuming units.

Correspondingly, the system depend on heat from the cooling systems of the heat generating units, recovered and used for delivery to the at least one heat consumer, the thermal system being configured in such way that heat recovered from the heat recovery generators is primarily utilized and that the conventional fuel burners is used for production of heat only or as a supplement if the heat from the heat recovery generators is not sufficient for obtaining the intended temperature.

According to one embodiment, the pipeline system comprises sensors and communication means for producing and sending signals between the heat generating and heat consuming units. The system also comprises a control unit and remotely operating valves associated with the heat generating and heat consuming units, controlled by the control unit.

The heat generating unit(s) and the heat consuming unit(s) may preferably be divided into separate temperature circuits and connected together for optimal energy saving. Further, the thermal fluid circulation lines for each thermal generating units, and each circulation line for the heat consuming units are arranged in parallel, allowing individual supply from or to said units, dependent on level of available heat.

According to one embodiment, the system may comprise at least two circulation pumps, the running and stand-by being controlled by a control unit, dependent on required flow of thermal fluid for meeting the set values.

According to the present invention it is possible to automatically regulate and control the fluid flow of heated water to units where it is possible to collect and exchange heat and thereupon circulate such heated fluid to consuming units, requiring heat in an optimal manner.

Further, the system may in a simple and uncomplicated manner be configured with respect to the required number of heat generating units and heat consuming or heat requiring units.

The system consists of few components, all of which being available on the market on a commercial scale. Additionally, due to the limited number of

components, the system is simple in installation.

It should also be appreciated that the system is configured in such way that it may be automatically controlled for example by a PLS-system. In such way it may be possible to register and log all readings and trend the values for reports from an environmental point of view. In such way it may be possible to more effectively and optimally use "green energy", achieving a more optimum and economical operation.

Short Description of the Drawings

An embodiment of the present invention shall now be described in further detail, referring to the accompanying drawings, wherein:

Figure 1 shows schematically a simplified arrangement and flow chart, indicating the principle used according to the present invention; and

Figure 2 shows schematically the arrangement and the flow chart for a marine installation or vessel, indication various heat generating units, heat consuming units, the pipelines for circulating the thermal fluid and the

communication lines for signals between the sensors and the valves and the control unit; and

Figure 3 shows schematically in an enlarged scale parts of the arrangement and flow chart shown in Figurer 1. Detailed Description of the Invention

Figure 1 shows the arrangement and the flow chart for a thermal system 10 on board a marine installation or vessel (not shown). In principle the thermal system 10 comprises various heat generating units, such as a fuel powered combustor 1 1 , heat consuming units such as an oil tank 12 or a waste incinerator 13, a piping system, comprising pipes 14 with valves 15 for circulating a thermal fluid through the system 0, connecting the heat generating units and the heat consuming units. A main circulation pump 16 is connected to the pipe system in order to secure circulation of the heat carrying fluid through the system. The thermal system 10 comprises further by-pass lines 18 with associated valves 15.

As further indicated in Figure 1 , the thermal system also comprises a control and metering system for controlling the valves 15 and the pump 16 in order to secure optimal heat production and delivery in the system 10. The control and metering system comprises preferably remotely actuation on the valves for individually opening or closing of these and sensors and meters for sensing temperature and measuring the pressure and/or flow rate through the pipe systems at relevant section thereof. For such purpose the thermal system 10 comprises communication lines 40, communicating signals for actuating the valves and transmitting signals to or from the control or measurement system to and/or from a control unit 17.

The heating system 10 disclosed is a closed, pressurized heating system for marine installations based on circulating thermal fluid, such as water/glycol, in the pipeline system 14 at a working temperature up to 1 10 °C. The working pressure is normally up to 3 bar.

Figure 2 shows schematically the arrangement and the flow chart for a marine installation or vessel. The thermal system 10 shown in Figure 2 is a more detailed embodiment of the system shown in Figure 1 . The thermal system 10 comprises in general a main circulation line 24, circulating a fluid by means of one or more main circulation pumps 16. According to the embodiment shown two equal pumps, mounted on skid, are used. One pump may be running while one pump is stand-by, each pump with capacity for delivery heated fluid total heat consumption. Alternatively, on may be dimensioned for maximum heat consumption, while the other may be configured for 50% heat consumption/stand-by. The thermal system 10 according to the embodiment shown includes four engines 20, for example for propulsion and/or auxiliary services. Each engine 20 is provided with a HT-cooling system 21 for cooling the engines 20, the cooling system 21 including heat exchanging means for producing "green energy" to the thermal system according to the present invention. The flow of heated coolant from the heat exchanger in each cooling system 21 is in counter flow with the coolant of the motor. Further, said flow for heated fluid flow for each engine is arranged in parallel by means of a pipeline 23, the ends of the pipelines 23 being connected to the main circulation pipeline 24 in parallel, while connected to the combustor in series. At least one actuated valve 25 is incorporated into the pipeline 23 for heated fluid.

The exhaust gas from each motor 20 is also cooled down by means of an exhaust gas economizer 22. Likewise, the fluid heated by the heat exchanger in the exhaust gas economizers 22 are flowing in corresponding pipelines 26 passing through a counter flow heat exchanger incorporated in the exhaust gas economizer 22. Said pipelines 26 for the various exhaust gas economizers are also arranged in parallel and include actuated valves 27 The exhaust gas economizer may preferably have an automatic by-pass regulation for minimum and maximum exhaust gas temperature and include an automatic control system.

A fuel fired heater 1 1 is incorporated in the main circulation line 25, for heating the circulating fluid in the main circulation line 24 in case where the "green energy" from the engines and/or the exhaust gas economizers, and possible a waste incinerator 13 is not sufficient to provide the required heat. A conventional expander tank 29 is also incorporated in the main circulation line 24. The fuel fired heater 1 1 is preferably used as the primary heating source for heating the fresh water in a separate, but integrated sanitary water system with the combustor 11 , since such sanitary water shall be fresh water and not necessary glycol or other types of liquids as the case may be for the fluid circulating through the main circulation line 24. Said sanitary water system is of a conventional type well known for the person skilled in the art, the water being delivered by means of a pump 30.

Further, the heated water is delivered to heat consuming units 12 of various types, such as liquid tanks, etc. The circulation lines 32, i.e. supply lines and exhaust lines, for each unit 12 are arranged in parallel and are also provided with actuated valves 33, arranged upstream of the heat consuming unit 12. A by-pass line 31 is provided to this end allowing the pumped fluid to by-pass all the flow

consuming units 12 or at least a major part of said units 12.

Each of the actuated valves are connected to a control cabinet 17, allowing an operator or a computer to regulate the opening and closure of the valves completely or partly, depending on required rate of needed heat. In case of a fully automated system an automation system including computer hardware and software may be used, linked to the control cabinet 17. Lines for transmitting signals from sensors and meters in the system, and communicating with the control cabinet 17/automation system, are also incorporated in the system. The control cabinet may for example have a 15" touch screen showing mimic diagram for the main pipeline components and may further be able to display total kW, "green kW" and fuel consumption. The control cabinet may also display temperatures, pressures and valve status and may further include alarm display. The unit may further have user interface for system operation and parameter settings. The system may also have an interface to IAS.

Figure 3 shows schematically in an enlarged scale parts of the arrangement and flow chart shown in Figurer 2.

The thermal system according to the present invention utilizes first the surplus energy from heat recovery generators associated for example with propulsion motors, auxiliary motors and the exhaust systems associated with of such motors. The system does only use fuel burners 1 1 if and when the "green energy" from the heat recovery generator system is not suffice to heat the various units 12 sufficiently to the required temperatures.

As indicated above, the system is automatically controlled and monitored by a control system and can be interfaced to the main computer system (IAS). Safety control system and system for manual control is standard features. The control system is type approved in the major class society and in accordance with class notation (E0).

The control system is PLC based and controls automatically the thermal fluid flow to the individual heat generators and heat consumer groups and balances the system in an optimal way. It also controls the exhaust gas outlet temperature in the exhaust gas economizer to avoid too low temperature in the exhaust gas system. The circulation system is operated by two or more main circulation pumps 16. Running and stand-by functionality is built into control system. The flow to the particular heat generator and heat consumer is automatically controlled by motor controlled valves operating from 0-100%. Manual control and emergency control is standard.

The heat generators and the heat consumers can be divided in separate temperature circuits and connected together for optimal energy saving. Further, it should be appreciated that in addition to the major parts described above, the system also contains piping and accessories like manual valves, temperature gauges, pressure gauges etc. which are well known for the person skilled in the art, and hence, is not disclosed herein.