Technical Field
-
The present invention relates to combustion of gas in marine vessels, and in particular to a system and a method for combusting boil-off gas generated from a liquefied fuel storage tank of such a vessel.
Background
-
Liquefied marine fuels, such as liquefied natural gas (LNG), ammonia, and hydrogen, are increasingly being used in marine vessels. However, one challenge associated with the storage of such fuels is the production of boil-off gas. Boil-off gas is generated as the liquefied fuel evaporates due to ambient heat absorption, leading to an increase in pressure within the fuel storage tank.
-
To manage the rising pressure, one approach is to design the fuel storage tank to withstand higher pressures. While this method can effectively contain the gas, it often requires more complex and expensive tank designs.
-
Another approach is to discharge the boil-off gas directly into the atmosphere. However, this practice has serious environmental and safety concerns. The release of unburnt fuels, such as e.g. methane and hydrogen, contributes to global warming and environmental degradation. Additionally, the release of ammonia poses serious safety hazards.
-
Given these challenges, there is a need for alternative and improved technologies for handling boil-off gases generated from liquefied marine fuels.
Summary
-
It is an object of the present disclosure to provide a technology that addresses at least some of the above concerns.
-
According to a first aspect of the present invention, there is provided a gas combustion system for a marine vessel, comprising a burner configured to combust a fuel feed comprising boil-off gas generated from a liquefied fuel in a fuel storage of the marine vessel. The system further comprises a combustion feed subsystem configured to supply the burner with the fuel feed and air for the combustion, a heat exchange element configured to absorb thermal energy from exhaust gases produced by the combustion of the fuel feed, and an energy recycling subsystem configured to receive the thermal energy from the heat exchange element. Further, a control unit is provided, which is configured to control an operation of the energy recycling subsystem to cause it to operate in at least one of an internal mode in which the energy recycling subsystem powers the combustion feed subsystem, and an external mode in which the energy recycling subsystem transfers energy to a vessel subsystem external to the gas combustion system.
-
According to a second aspect, there is provided a method in a gas combustion system combusting a fuel feed comprising boil-off gas generated from a liquefied fuel in a fuel storage of a marine vessel. The method comprises supplying, by a combustion feed subsystem, the fuel feed and air to a burner, absorbing, by a heat exchange element, thermal energy from exhaust gases produced by the combustion of the fuel feed in the burner, and transferring the absorbed thermal energy to an energy recycling subsystem. Further, the method comprises operating the energy recycling subsystem in at least one of an internal mode to power the combustion feed subsystem based on the transferred thermal energy, and an external mode to transfer energy to a vessel subsystem external to the gas combustion system.
-
Combusting the boil-off gas in the burner helps preventing the direct release of gaseous fuels into the atmosphere, which can pose significant environmental and safety concerns. For example, methane and hydrogen have a relatively high global warming potential, contributing to climate change, while ammonia presents serious safety hazards. By combusting the boil-off gas, these harmful gases may be converted into substances with lower global warming potential and reduces safety risks.
-
Furthermore, the above aspects allow thermal energy, generated by combusting the boil-off gas, to be recovered by the energy recycling system. The recovered energy may be utilised within the vessel, such as for powering the gas combustion system itself, for heating of auxiliary systems of the vessel, or delivering electricity to a shipboard electrical system. This energy recovery may improve the overall energy efficiency of the vessel, reducing the need for additional fuel consumption.
-
In the internal mode, the recovered energy may be fed back to the gas combustion system, where it can be used to power components involved in the combustion process, such as fuel heaters and fans and compressors providing air and fuel to the burner. This reduces the need for external power to be provided to the system, such as electricity from the shipboard electrical system and heat from thermal management systems of the vessel.
-
In the external mode, surplus energy which is not used to meet internal demands of the gas combustion system, may be utilised by other subsystems of the vessel. When the external mode is activated, any recovered energy can be directed to, for example, the vessel's thermal management system, auxiliary equipment, or the shipboard electrical system. For example, the recovered energy can be used to power HVAC systems, run additional machinery, or be stored for later use, thus reducing the vessel's overall consumption of primary energy sources.
-
In some examples, the energy recycling subsystem may be designed to prioritise the use of recovered energy in the form of heat before considering its conversion into electricity. This approach may help increasing the efficiency of the energy recovery process by first utilising the thermal energy directly where it is most effective, such as in heating systems, pre-heating of the fuel, or supplying heat to the vessel's thermal management system. By recycling the energy as heat, the system may reduce energy losses associated with conversion processes and ensures that the thermal energy is used in an efficient manner. Once the demand for heat has been fully met, any remaining excess energy may then be converted into electricity. This staged approach may help ensuring that the vessel's energy resources are used more efficiently, reducing reliance on primary energy sources.
-
In some examples, the energy recycling subsystem is configured to convert the thermal energy that is absorbed by the heat exchange element into electric energy. This may be referred to as the energy recycling subsystem being operated in an electricity generation mode. The energy recycling subsystem may, for example, comprise an organic Rankine cycle, ORC, unit for converting the thermal energy into mechanical work that can be used to drive an electric generator. The electricity may in the internal mode be employed to power at least one of a fan and a compressor of the combustion feed subsystem. In the external mode, the electricity may be transferred to a main grid of the vessel, i.e., the shipboard electrical system, or other vessel subsystems.
-
In some examples, the energy recycling subsystem is configured to operate in a thermal management mode, in which it transfers at least some of the absorbed thermal energy to the combustion feed subsystem and/or the vessel subsystem. In the internal mode, the energy recycling subsystem may transfer at least some of the thermal energy absorbed by the heat exchange element to the combustion feed subsystem, such as to a heater for pre-heating the boil-off gas prior to combustion. In the external mode, the energy recycling subsystem may transfer at least some of the thermal energy to a thermal management system of the vessel.
-
As mentioned above, the energy recycling subsystem may be designed to prioritise the use of recovered energy in the form of heat before converting it into electricity. Hence, in some examples, a thermal energy demand of the combustion feed subsystem and/or the vessel subsystem may be determined. The energy demand may be compared with a predetermined threshold, which may be selected to indicate whether there is a need for additional thermal energy or not. This allows the energy recycling subsystem to be operated in the thermal management mode for thermal energy demands meeting or exceeding the threshold, and in the electricity generation mode for thermal energy demands being below the threshold.
-
The recycling of the thermal energy may be determined by the operation of the heat exchange element, which according to some examples may be arranged either in an active mode or an inactive mode. In the active mode, a working fluid may circulate through the heat exchange element and a heat exchanger circuit to absorb thermal energy from the exhaust gases. In the inactive mode, there may be no or very little flow of working fluid in the heat exchange circuit. By switching the heat exchange element from the inactive mode to the active mode, the transfer of the absorbed thermal energy to the energy recycling subsystem may be initiated.
-
Hence, in some examples, sensor data indicative of a temperature of the exhaust gases may be received. This data may be used when controlling the operation of the heat exchange element, such that the heat exchange element is operated in the active mode for temperatures at or above a predetermined limit and maintained in the inactive mode for temperatures below the limit.
-
By providing a flexible approach to managing and allocating energy, the ability to operate the energy recycling subsystem in various modes - such as the external mode, the internal mode, the heat management mode, and the electricity generation mode - can help optimising the overall energy efficiency and sustainability of the vessel's operations.
-
The burner may be provided to initiate and sustain the combustion process. This may be achieved by mixing fuel (i.e., boil-off gas in the fuel feed) with air and igniting the mixture to provide a flame. The burner typically comprises a fuel injector or nozzle, an air intake system, a mixing system where the air and fuel may be combined, and an ignition system that initiates the combustion.
-
In some examples, the burner comprises a spark igniter for initiating the combustion. The spark igniter may comprise a pair of electrodes, forming a gap in which an electrical spark can be generated when a high voltage is applied across the electrodes. This spark may ignite the air-fuel mixture provided by the combustion feed subsystem, starting the combustion process. Some example configurations include variations in the electrode design, such as single-electrode systems where the spark jumps to a grounded surface.
-
Alternatives to spark igniters include hot surface igniters and pilot flames, which maintain a small, continuous flame that can ignite the main burner when needed. However, the spark igniter may be preferred over pilot flames due to its energy efficiency, rapid response time, and ability to operate only when necessary.
-
The combustion feed subsystem may be arranged to provide the burner with the right mixture of fuel and air at the right pressure and flow rate to enable efficient and stable combustion. Hence, the combustion feed subsystem may comprise a fuel supply system for delivering fuel to the burner and an air supply system for delivering air for combustion. The fuel supply system typically comprises a series of components such as fuel pumps, compressors, control valves, heaters, and fuel lines. The air supply system may comprise an air intake, valves to regulate airflow, and fans or blowers that force air into the burner. Depending on the burner design, the air supply system may be configured to supply either pre-heated air or ambient air.
-
The components of the combustion feed subsystem can be powered by recovered energy from the energy recycling subsystem. This may include supplying heat to heaters or other elements that are in thermal contact with the boil-off gas, as well as electricity to pumps, compressors, and fans.
-
The energy recycling subsystem may be configured to receive recovered energy from the exhaust gases, typically via the heat exchange element, and utilise this energy directly in the form of heat or converting it into electricity. The energy recycling subsystem may comprise a heat exchanger circuit for extracting thermal energy from a working fluid of the heat exchange element arranged to absorb thermal energy from the exhaust gases. The extracted thermal energy can either be distributed internally to components of the gas combustion system, or externally to thermal management systems onboard the vessel. An energy conversion unit may also be provided, which typically comprises components such as an ORC system or a steam turbine, where the extracted thermal energy can be used to generate mechanical power, which may then be converted into electrical energy by a generator.
-
Further features and advantages of the invention will become apparent from the following description of preferred embodiments, given by way of example only, which is made with reference to the accompanying drawings.
Brief Description of the Drawings
-
Various aspects and examples of the present disclosure will be readily understood from the embodiments discussed in the following detailed description and the accompanying drawings, in which:
- Figure 1 shows a schematic outline of a system for a marine vessel, comprising a gas combustion unit, a combustion feed subsystem, and an energy recycling subsystem.
- Figure 2 shows a schematic outline of a system according to another example.
- Figure 3 shows a gas combustion unit according to an example.
- Figures 4A-C are flowcharts of methods according to some examples, in which the energy recycling subsystem is operated in one or more of an internal mode, an external mode, a thermal management mode, and an electricity generation mode.
Detailed Description
-
Figure 1 is a schematic illustration of an example gas combustion system for a marine vessel, such as a cargo ship, a passenger ship, or a naval and defence vessel. The depicted system 100 comprises a burner 110, a combustion feed subsystem 120 for providing the burner 110 with fuel and air, a heat exchange element 130 for recovering thermal energy from exhaust gases from the combustion, and an energy recycling subsystem 140 for feeding the recovered energy back to the gas combustion system 100 or transfer it to a vessel subsystem 160, external to the gas combustion system 100. The burner 110 and the heat exchange element 130 may form part of a gas combustion unit 170, with the burner 110 arranged in a combustion chamber of the gas combustion unit 170 and the heat exchange element 130 arranged in an exhaust stack of the same.
-
The burner 110 is configured to combust a fuel feed comprising boil-off gas generated from a liquefied fuel in a fuel storage tank 105 of the vessel. The liquefied fuel may, for example, be liquefied natural gas (LNG), liquefied petroleum gas, hydrogen, ammonia, or other types of fuels generating boil-off gas that needs to be handled to avoid excessive pressure buildup in the fuel storage tank 105.
-
The combustion feed subsystem 120 is configured to supply the burner 110 with the necessary fuel mixture, or fuel feed, comprising the boil-off gas and, in some cases, other additives or compounds such as nitrogen. The combustion feed subsystem 120 may also provide a controlled flow of air, which may be mixed with the fuel feed to create the appropriate fuel-air ratio for efficient combustion. The flow of boil-off gas may be controlled by a fuel supply system, which may include various components such as control valves, heaters, and compressors. Similarly, the flow of air may be controlled by an air supply system, which may include components such as control valves and fans or blowers forcing air into the burner 110 and gas combustion unit 170. The combustion feed subsystem 120 may be powered by thermal and/or electric energy at least partly provided by the energy recycling subsystem 140.
-
The energy recycling subsystem 140 may be configured to extract thermal energy that has been recovered from the exhaust gases from the burner 110 and utilise the thermal energy by feeding it back into the combustion feed subsystem 120, by transferring it to an external system such as the vessel subsystem 160, or a combination of both. The thermal energy may be extracted from a heat exchange element 130, which may be arranged in a flow path of the exhaust gases to allow thermal energy to be absorbed into a working fluid. The working fluid may be circulated in a heat exchanger circuit thermally connecting the heat exchange element 130 and the energy recycling subsystem 140 to allow the thermal energy to be transferred therebetween.
-
The working fluid may be any suitable fluid known in the art that can be used in thermodynamic cycles for transferring thermal energy. Examples include, but are not limited to, water, such as superheated steam, saturated water/steam (utilising a phase change for heat transfer), or hot water (utilising a temperature change). Other thermal fluids, absorbing and releasing heat through a temperature change, may also be employed. In further examples, such as in systems configured to convert the absorbed thermal energy into electricity, the working fluid may comprise refrigerants comprising organic or natural compounds. Examples include organic refrigerants such as R-245fa, R1233zd, pentane, and toluene, as well as natural refrigerants like ammonia and water. The choice of working fluid can be selected based on the specific application and operation temperature range.
-
The operation of the energy recycling subsystem 140 may be controlled by a control unit 150, which may be communicatively coupled to the energy recycling subsystem 140 and operable to cause the subsystem to operate in one or several different operational modes. The operational mode may determine how the recovered energy is utilised, and to where it is fed. In some examples, the energy recycling subsystem 140 is operated in an internal mode, in which it may power the combustion feed subsystem 120, and/or an external mode in which it may transfer energy elsewhere, such as to another subsystem 160 of the vessel, which may not form part of the gas combustion system 100. In further examples, the energy recycling subsystem 140 is operated in a thermal management mode, in which it may transfer at least some of the absorbed thermal energy to the combustion feed subsystem 120 and/or a vessel subsystem 160 not forming part of the gas combustion system 100, and/or an electricity generation mode in which it may convert at least some of the absorbed thermal energy into electrical energy.
-
In the thermal management mode, recovered thermal energy may be fed back to a heater of the combustion feed subsystem 120 to pre-heat boil-off gas before it is supplied to the burner 110. Additionally, or alternatively, the recovered thermal energy may be transferred to a thermal management system of the vessel, which, for example, may be used to heat various auxiliary systems of the vessel such as an HVAC system, a calorifier, or a cargo heating system.
-
In the electricity generation mode, recovered thermal energy may be converted into electricity that can be utilised to power various components of the combustion feed subsystem 120, such as air fans, compressors, heaters, and valve arrangements. Additionally, or alternatively, the electricity may be transmitted to a vessel subsystem 160 such as a shipboard electrical system.
-
Various combinations of operational modes are possible for the energy recycling subsystem 140. For instance, the subsystem 140 can be operated to transfer thermal energy either internally within the gas combustion system 100, externally to other subsystems of the vessel, or a combination of both. Additionally, it can be operated to convert thermal energy into electricity that is used internally, supplied externally, or distributed in a combination of both ways. The energy recycling subsystem 140 may be set up to operate exclusively in one mode, in any two modes, or in three modes, depending on specific operational requirements. Consequently, in some configurations, the subsystem 140 may be designed to function only in internal mode, bypassing the external mode, only in external mode, with the capability to transfer thermal energy exclusively, generate electricity exclusively, or handle both thermal energy and electricity in various combinations.
-
Figure 2 is a schematic illustration of a gas combustion system 100 according to some examples, which may be configured similarly to the system discussed above with reference to figure 1.
-
The depicted system 100 may comprise a gas combustion unit 170 which is configured to receive boil-off gas from a fuel storage 105 of a vessel, where liquefied fuel such as LNG, LPG, ammonia, and hydrogen, may be stored at cryogenic temperatures, ambient temperature, or any temperature in between.
-
The combustion feed subsystem 120 is arranged to deliver the boil-off gas to the burner 110 in the correct proportions, along with the necessary air for combustion. The depicted combustion feed subsystem 120 comprises fuel supply lines 121 for conveying a flow of boil-off gas from the fuel storage 105, a heater 126 for increasing the temperature of the gaseous flow, a compressor 124 for increasing the pressure, and a valve arrangement 123 for controlling the supply to the burner 110. The depicted combustion feed subsystem 120 further comprises one or more fans 122, or blowers, for providing air for the combustion process, as well as for dilution, and cooling of exhaust gases and/or a combustion chamber of the gas combustion unit 170.
-
It should be noted that this is merely an example, and that other configurations are possible. For example, the compressor 124 may be omitted in some systems, allowing the burner 110 to be fed with a flow of boil-off gas driven by the pressure generated by the fuel storage 105.
-
The energy recycling subsystem 140 may be configured to power one or more of the components of the combustion feed subsystem 120. In the current example, the energy recycling subsystem 140 is configured to provide electricity to the fan 122 and the compressor 124, as well as thermal energy (heat) to the heater 126. Electricity may be supplied via electrical supply lines 141 (indicated by dashed lines in figure 2) that extend between the energy recycling subsystem 140 and the respective components, such as the fan 122 and the compressor 124. Thermal energy may be supplied to the heater 126 through a piping system 142 (indicated by solid lines) that conveys a heat transfer medium. This piping system 142 may comprise a circulation loop of pipes or fluid conduits, allowing the heat transfer medium to circulate between the energy recycling subsystem 140 and the heater 126.
-
A similar approach may be used for transferring energy externally to the vessel subsystem 160, utilising electrical supply lines 141 for electricity and a piping system 142 for thermal energy transfer. It should be noted that this configuration is merely an example, and other arrangements are possible. For instance, the electric energy could also be used to power other components of the gas combustion system 100, such as valve arrangements 123, sensors, and pumps. Additionally, multiple heaters may be employed, some of which could be powered by electricity rather than thermal energy.
-
Figure 3 is a schematic illustration of a gas combustion unit 170, which may be configured similarly to any of the gas combustion units 170 discussed above with reference to figures 1 and 2.
-
The example gas combustion unit 170 comprises a combustion chamber 174 where the combustion process takes place, and an exhaust stack 176 through which exhaust gases are released from the gas combustion unit 170. The combustion chamber 174 accommodates the burner 110, whereas the heat exchange element 130 is arranged in the exhaust stack 176.
-
The burner 110 comprises a spark igniter 112 providing the initial ignition source to start the combustion process. The combustion process is maintained by a fuel feed, comprising boil-off gas evacuated from the fuel storage tank, which is supplied by the combustion feed subsystem 120 to the burner 110 via a feed 127.
-
The combustion feed subsystem 120 further provides air, which is mixed by with the fuel feed to enable combustion. The air may be provided by a fan 122 directing a flow of air F into the combustion chamber 174. In the present example, the fan 122 is configured to provide the flow of air F into a wind chest, or mixing chamber 172, which is arranged to distribute the air through the gas combustion unit 170.
-
The combustion chamber 174 may comprise a double-wall structure for enhancing thermal management and prevent overheating of the gas combustion unit 170. The double-wall structure comprises an inner wall 177 and an outer wall 178, arranged to form a space between them through which a portion of the air flow F can be directed to dissipate heat. Specifically, the combustion chamber 174 may be realised as a smaller cylinder 177 arranged concentrically within a larger, outer cylinder 178, forming an annular air flow channel between the two. The cooling flow F provided by the fan 122 may pass through this channel to absorb heat from the inner wall 177, which is exposed to the high temperatures generated during combustion in the combustion chamber 174 and maintain the outer wall 178 at a lower temperature. In the present example, the inner wall 177 comprises a set of openings through which some of the air F is allowed to flow into the combustion chamber 174 and take part in the combustion.
-
The exhaust gases and cooling air flow F may proceed to the exhaust zone of the gas combustion unit 170, more specifically the exhaust stack 176, where at least some of the thermal energy carried by the cooling air flow F and the exhaust gases may be absorbed by the heat exchange element 130. The heat exchange element 130 may comprise one or more heat recovery coils, which are formed tubes exposed to the flow of exhaust gases. In some configurations, multiple coils may be arranged concentrically. The tubes can either be bare or finned, with finned tubes being used to enhance heat transfer efficiency.
-
The working fluid may be circulated in a heat exchange circuit 132, with the heat exchange element 130 positioned on the hot side of the circuit 132 and the energy recycling subsystem 140 located on the cold side of the circuit 132. During operation, or in active mode, the working fluid is circulated between the heat exchange element 130 and the energy recycling subsystem 140, enabling the transfer thermal energy from the exhaust gases to the energy recycling subsystem 130. The circulation of working fluid may typically be driven by a pump or a similar device.
-
In some examples, a temperature sensor (not shown) may be arranged to monitor the temperature, and hence the thermal energy content, of the exhaust gases. This sensor generates data that can be compared to a predetermined temperature threshold to control the operation of the heat exchange element 130. Specifically, the heat exchange element 130 may be operated in active mode when the exhaust gas temperature meets or exceeds this threshold, allowing energy to be transferred to the energy recycling subsystem 140. Conversely, when the exhaust gas temperature falls below the threshold, the heat exchange element 130 may be operated in inactive mode, reducing or pausing the flow of thermal energy transfer, thereby allowing the thermal energy to remain in the exhaust gases.
-
Figure 4A is a flowchart illustrating a method in a gas combustion system, which may be similarly configured to any of the systems disclosed in figures 1-3. The method comprises supplying 210 a fuel feed, comprising boil-off gas, along with air to the burner 110. This may be achieved by means of the combustion feed subsystem 120, as discussed above, by conveying boil-off gas from the fuel storage tank 105 and mixing it with air. The method may further comprise absorbing 220 thermal energy by means of a heat exchange element 130. The heat exchange element 130 may be arranged in an exhaust flow path of the gas combustion unit 170, where it may be operated to transfer at least some of the thermal energy in the exhaust gases into a working fluid circulating through the heat exchange element 130.
-
The absorbed thermal energy may be transferred 230 to the energy recycling subsystem 140, which may be operated in different modes depending on how and by whom the absorbed energy will be utilised. In the example method shown in figure 4A, the energy recycling subsystem 140 may be operated in either an internal mode 250, where it powers the combustion feed subsystem 120, or an external mode 251, where it transfers energy to a vessel subsystem 160, which is external to the gas combustion system 100. In some examples, a combination of these operational modes is possible, allowing the energy recycling subsystem 140 to simultaneously power the combustion feed subsystem 120 and transfer energy elsewhere.
-
Figure 4B is a flowchart illustrating another method in a similar gas combustion system 100 as above. Similar to the method depicted in figure 4A, a fuel feed and air may be supplied 210 to the burner for combustion. At least some of the generated heat may be absorbed 220 by the heat exchanger element 130 and then transferred 230 to the energy recycling subsystem 140. In this example, however, the energy recycling subsystem 140 may be operated either in a thermal management mode 252, where the absorbed thermal energy is transferred to the combustion feed subsystem 120 and/or the vessel subsystem 160, or in an electricity generation mode 253, where the thermal energy is converted into electrical energy.
-
The choice of operation mode in the methods illustrated in figures 4A and 4B may be determined based on various parameters, such as the thermal energy demand of the vessel or a desired energy recycling efficiency. An example method will now be discussed with reference to figure 4C.
-
Figure 4C shows a method which may comprise similar steps to those shown in figures 4A and B. However, as illustrated in figure 4C, this method includes a step of determining 240 a thermal energy demand of the vessel, such as the demand from the combustion feed subsystem 120 and/or the vessel subsystem 160. This demand may be based on parameters such as the temperature or pressure of the boil-off gas evacuated from the fuel storage tank 105, or the temperature of the fuel feed being supplied to the burner 110. Additionally, the thermal energy demand may also be determined by monitoring the temperature or pressure of the vessel subsystem 160, such as the thermal management system responsible for heating, for example, HVAC systems or cargo heating systems.
-
The thermal energy demand, or the need for heat, may be evaluated by comparing it against a predetermined threshold. If the thermal energy demand meets or exceeds this threshold, it may indicate a need for additional thermal energy, prompting the energy recycling subsystem 140 to operate in thermal management mode 252. Conversely, if the thermal energy demand on the other hand is below the predetermined threshold, it may suggest that the thermal energy demand is already met and prompting the energy recycling subsystem 140 to enter electricity generation mode 253. This approach allows the system to utilise the recovered thermal energy as a heat source when there is a demand for heat and to convert surplus thermal energy into electricity when heat demand is lower.
-
The recovered thermal energy may be transferred internally, for example to power 254 a heater 126 of the combustion feed subsystem 120, or externally, such as to power 255 a thermal management system of the vessel. If the recovered thermal energy is converted to electricity, it can be used internally to power 256 a fan 122 or compressor 124 of the combustion feed subsystem 120 or supplied 257 externally to the shipboard electrical system.
-
The control unit 150, or controller, may generally comprise one or more processors and one or more non-transitory computer-readable media storing first computer executable instructions that, when executed by the one or more processors, cause the system to perform at least parts of the actions discussed in connection with figures 4A-C. Generally, the control unit 150 may comprise circuitry which is configured to implement (using one or more non-transitory computer-readable media) the functionality described herein. Suitable processors for the execution of a program of instructions include, by way of example, both general and special purpose microprocessors, and the sole processor or one of multiple processors or cores, of any kind of computer. The processors can be supplemented by, or incorporated in, ASICs (application-specific integrated circuits). Those skilled in the art will understand that the above-described exemplary embodiments may be implemented in any suitable software, hardware, or firmware configuration or combination thereof. An exemplary hardware platform for implementing the exemplary embodiments may include, for example, an Intel x86 based platform with compatible operating system, a Windows OS, a Mac platform and MAC OS, a mobile device having an operating system such as iOS, Android, etc. In a further example, the exemplary embodiments of the above-described method may be embodied as a program containing lines of code stored on a non-transitory computer readable storage medium that, when compiled, may be executed on a processor or microprocessor.
-
The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. It is to be understood that any feature described in relation to any one embodiment or example may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.