Power generation system using waste heat

Abstract

The present invention relates to a power generation system using waste heat. More specifically, the power generation system using waste heat comprises: an organic Rankine cycle unit for generating power by using thermal energy; and a waste heat supply line for supplying waste heat from a plurality of waste heat sources to the organic Rankine cycle unit. The organic Rankine cycle unit includes: a refrigerant line having a closed curve formed such that a refrigerant circulates therein; a plurality of heat exchangers for raising the temperature of the refrigerant in the refrigerant line; an expander rotated by a vaporized refrigerant; a generator connected to the expander to generate electricity; a condenser for condensing the vaporized refrigerant discharged from the expander; and a pump for transferring the liquefied refrigerant discharged from the condenser to the heat exchangers. The waste heat supply line connects the plurality of waste heat sources and the plurality of heat exchangers such that a channel extending from the exit end of the pump to the front end of the expander is used to successively supply waste heat sources having relative high temperatures from waste heat sources having relative low temperatures, thereby producing power by using various waste heat sources in a ship in a combined manner.

Description

Power generation system using waste heat

[0001] The present invention relates to a power generation system utilizing waste heat, and more specifically, provides a power generation system utilizing waste heat that produces power by complexly utilizing various waste heat sources within a ship by arranging a plurality of heat exchangers connected to a plurality of waste heat sources between the outlet end of a pump and the inlet end of an expander, and sequentially supplying waste heat sources with relatively low temperatures to waste heat sources with relatively high temperatures along the flow path from the pump outlet end to the front end of the expander.

[0002] Approximately half of the thermal energy generated by burning fuel in ship propulsion or power generation engines is used for propulsion or power generation, while the remaining heat is wasted as unused waste heat.

[0003] If waste heat emitted externally can be recycled, it is possible to significantly reduce the total energy consumed by ships as well as decrease carbon dioxide emissions; therefore, research on methods to utilize this waste heat is currently underway.

[0004] For example, in the marine sector, a Waste Heat Recovery System (WHRS) is being applied to enable the generation of electricity by additionally installing a gas turbine that uses high-temperature exhaust gas emitted from an engine as the working fluid, or a steam turbine that uses a portion of the steam generated using the heat of the high-temperature exhaust gas as the working fluid.

[0005] However, as more shipowners seek to reduce fuel costs by operating ships at low speeds, problems are arising with conventional methods of generating electricity using waste heat recovery systems. This is because the engine output of ships operating at low speeds is only 30 to 50% of their maximum output, and the temperature of the exhaust gas emitted from engines operating at low loads is low. Consequently, conventional waste heat recovery systems, which require high temperatures, are unable to perform their function properly.

[0006] In order to solve these problems, the relevant industry has turned its attention to the development of Organic Rankine Cycle (ORC) devices.

[0007] An organic Rankine cycle device refers to a system that utilizes low-energy waste heat to produce electricity through a closed cycle of evaporation, expansion, condensation, and compression processes using a fluid with high vapor pressure.

[0008] Specifically, the organic Rankine cycle device vaporizes the working fluid through a constant pressure heating process that absorbs heat from an external heat source in the evaporator, and when the pressure inside the cycle device increases rapidly due to vaporization, the turbine installed inside the cycle rotates with the increased pressure.

[0009] During the adiabatic expansion process, the rotating turbine generates electricity by converting rotational kinetic energy into electrical energy. The gas that drives the turbine flows back into the condenser, where it undergoes adiabatic compression through a constant-pressure heat dissipation process, losing heat via heat exchange with an external heat source.

[0010] The liquefied working fluid is recirculated to the evaporator using a pump, and thus, the organic Rankine cycle device can continuously generate power. This organic Rankine cycle device has the characteristic that its efficiency increases as the temperature of the external heat source on the high-temperature side increases and as the temperature of the external heat source on the low-temperature side decreases.

[0011] FIG. 1 is a drawing illustrating an energy-saving vessel (90) equipped with a conventional power generation device utilizing a temperature difference, which is disclosed in Korean Patent Publication No. 10-2011-0063935 (June 15, 2011).

[0012] An energy-saving vessel (90) equipped with a power generation device utilizing the above temperature difference is configured to include a heat engine (91) that cools with fresh water, a cooler (92) through which fresh water and seawater flow and exchange heat with each other, a hot water pipe (93) connecting the heat engine (91) and the cooler (92) through which hot water discharged from the heat engine (91) flows, a cold water pipe (94) connecting the heat engine (91) and the cooler (92) through which cold water discharged from the cooler (92) flows, a cold seawater pipe (95) that guides seawater introduced from outside the hull to flow into the cooler (92), a hot seawater pipe (96) through which seawater discharged after heat exchange with fresh water in the cooler (92) is discharged, and an organic Rankine cycle device (97) that generates power while a working fluid circulates through an evaporator, a turbine, a condenser, and a pump.

[0013] The above energy-saving ship (90) has the characteristic of saving fuel oil and reducing greenhouse gas emissions by recycling energy sources that were previously discharged into the sea, by installing an organic Rankine cycle device (97) in the cooling system of various heat engines of the ship, which generates power through the repetition of vaporization and liquefaction processes by repeatedly circulating an evaporator and a condenser using a working fluid that is easily vaporized at a temperature such as high-temperature water in the main engine, auxiliary engine, and boiler drain cooler, and easily liquefied at a temperature such as room temperature or low-temperature water in the cooler.

[0014] However, conventional organic Rankine cycle devices had a problem in that the turbine producing electricity would repeatedly rotate fast and then slow, resulting in uneven production of electrical energy.

[0015] In addition, ships produce the steam required for the vessel using exhaust gas generated from the main engine. If less steam is produced than the amount used, additional steam can be produced using an auxiliary boiler. However, if more steam is produced than the amount used, the steam is forcibly cooled using a dump condenser to maintain the main steam line at a constant pressure. Consequently, a problem arises where excess steam is not utilized and is wasted during this process.

[0016] In addition, conventional ORC systems have limitations in that they cannot utilize various waste heat sources such as engine jacket water cooling, scavenge air cooling, exhaust gas, or excess steam in combination, and there is a problem in that an ORC system for each waste heat source must be operated separately.

[0017] In particular, as ammonia co-firing engines and the like are being used as ship engines due to the recent tightening of environmental regulations, there are fewer places to utilize the surplus steam generated on ships, and the amount of steam that is wasted without being consumed by users is increasing.

[0018] Consequently, the relevant industry is demanding the development of technology that utilizes excess steam for power generation while ensuring stable electricity production by uniformly rotating the turbines.

[0019] The present invention aims to solve the problems of the aforementioned prior art and comprises an organic Rankine cycle unit that produces electricity using thermal energy and a waste heat supply line that supplies waste heat from a plurality of waste heat sources to the organic Rankine cycle unit. The organic Rankine cycle unit comprises a refrigerant line forming a closed curve to allow refrigerant to circulate inside, a plurality of heat exchangers that heat the refrigerant within the refrigerant line, an expander that rotates by the vaporized refrigerant, a generator connected to the expander that produces electricity, a condenser that condenses the vaporized refrigerant discharged from the expander, and a pump that transfers the liquefied refrigerant discharged from the condenser to the heat exchanger side. The waste heat supply line is configured to connect the plurality of waste heat sources and the plurality of heat exchangers, thereby providing a power generation system using waste heat that can generate electricity through a single organic Rankine cycle using waste heat transferred from the plurality of waste heat sources.

[0020] In addition, the present invention aims to provide a power generation system utilizing waste heat that can efficiently utilize waste heat, wherein a plurality of heat exchangers are arranged between the outlet end of the pump of the refrigerant line and the inlet end of the expander, and the temperature of the waste heat supplied to the plurality of heat exchangers arranged according to the flow of the refrigerant line is sequentially increased so that the refrigerant is sequentially heated as it passes through the plurality of heat exchangers.

[0021] In addition, the present invention aims to provide a power generation system utilizing waste heat that increases power generation efficiency and prevents the refrigerant from vaporizing at an unnecessary location by causing the refrigerant to vaporize while passing through the heat exchanger closest to the inlet end of the expander.

[0022] In addition, the present invention aims to provide a power generation system using waste heat that can efficiently reuse various waste heats of a ship by including two or more of jacket water, excess steam, scavenging air, and exhaust gas among the waste heat source that cools the engine, and supplying a waste heat source with a relatively low temperature to a heat exchanger on the outlet side of the pump through the waste heat supply line.

[0023] In addition, the present invention aims to provide a power generation system using waste heat that enables temperature control of the refrigerant caused by over-supply or under-supply of waste heat during power generation using various waste heats, wherein the organic Rankine cycle unit further includes a refrigerant flow controller that controls the flow of the refrigerant in the refrigerant line so that the refrigerant flowing into the plurality of heat exchangers is controlled within a preset range.

[0024] However, the technical problems that the embodiments of the present invention aim to solve are not limited to the technical problems described above, and other technical problems may exist.

[0025] As a technical means for achieving the above-mentioned technical problem, a power generation system using waste heat according to one embodiment of the present invention comprises an organic Rankine cycle unit that generates power using thermal energy, and a waste heat supply line that supplies waste heat from a plurality of waste heat sources to the organic Rankine cycle unit, wherein the organic Rankine cycle unit comprises a refrigerant line forming a closed curve to allow refrigerant to circulate inside, a plurality of heat exchangers that heat the refrigerant within the refrigerant line, an expander that rotates by the vaporized refrigerant, a generator connected to the expander that generates electricity, a condenser that condenses the vaporized refrigerant discharged from the expander, and a pump that transfers the liquefied refrigerant discharged from the condenser to the heat exchanger side, wherein the waste heat supply line can connect between the plurality of waste heat sources and the plurality of heat exchangers.

[0026] In addition, according to one embodiment of the present invention, a plurality of the heat exchangers may be disposed between the outlet end of the pump of the refrigerant line and the inlet end of the expander.

[0027] In addition, according to one embodiment of the present invention, the temperature of the waste heat supplied to a plurality of heat exchangers arranged according to the flow of the refrigerant line can be sequentially increased.

[0028] In addition, according to one embodiment of the present invention, the refrigerant may be vaporized while passing through the heat exchanger closest to the inlet end of the expander.

[0029] In addition, according to one embodiment of the present invention, the waste heat source includes two or more of jacket water, excess steam, scavenging air, and exhaust gas that cools the engine, and a waste heat source with a relatively low temperature can be supplied to a heat exchanger on the outlet side of the pump through the waste heat supply line.

[0030] In addition, according to one embodiment of the present invention, the organic Rankine cycle may further include a refrigerant flow controller that controls the flow of refrigerant in the refrigerant line so that the refrigerant flowing into the plurality of heat exchangers is controlled within a preset range.

[0031] In addition, according to one embodiment of the present invention, a bypass is provided so that the refrigerant in the refrigerant line bypasses at least some of the heat exchangers, and the refrigerant flow controller can control the refrigerant to bypass at least some of the heat exchangers through the bypass when the temperature of the refrigerant within a predetermined section of the refrigerant line is above a set range.

[0032] In addition, according to one embodiment of the present invention, a resupply line is provided so that the refrigerant in the refrigerant line is resupplied to at least some of the heat exchangers, and the refrigerant flow controller can control the refrigerant to be additionally heated through at least some of the heat exchangers when the temperature of the refrigerant in a predetermined section of the refrigerant line is below a set range.

[0033] The above-described means for solving the problem are merely exemplary and should not be interpreted as intended to limit the invention. In addition to the exemplary embodiments described above, additional embodiments may exist in the drawings and the detailed description of the invention.

[0034] According to the means for solving the problem of the present invention described above, the organic Rankine cycle unit that produces electricity using thermal energy and the waste heat supply line that supplies waste heat from a plurality of waste heat sources to the organic Rankine cycle unit are included, wherein the organic Rankine cycle unit includes a refrigerant line that forms a closed curve to allow refrigerant to circulate inside, a plurality of heat exchangers that heat the refrigerant in the refrigerant line, an expander that rotates by the vaporized refrigerant, a generator connected to the expander that produces electricity, a condenser that condenses the vaporized refrigerant discharged from the expander, and a pump that transfers the liquefied refrigerant discharged from the condenser to the heat exchanger side, and wherein the waste heat supply line is configured to connect between the plurality of waste heat sources and the plurality of heat exchangers, thereby having the effect of enabling power generation through a single organic Rankine cycle using waste heat transferred from the plurality of waste heat sources.

[0035] In addition, the present invention allows the plurality of heat exchangers to be arranged between the outlet end of the pump of the refrigerant line and the inlet end of the expander, and by causing the temperature of the waste heat supplied to the plurality of heat exchangers arranged according to the flow of the refrigerant line to rise sequentially, the refrigerant is heated sequentially as it passes through the plurality of heat exchangers, and the waste heat can be utilized efficiently.

[0036] In addition, the present invention has the effect of increasing power generation efficiency and preventing the refrigerant from vaporizing at unnecessary locations by causing the refrigerant to vaporize while passing through the heat exchanger closest to the inlet end of the expander.

[0037] In addition, the present invention provides a power generation system using waste heat that can efficiently reuse various waste heats of a ship by including two or more of jacket water, excess steam, scavenging air, and exhaust gas among the waste heat source that cools the engine, and supplying a waste heat source with a relatively low temperature to a heat exchanger on the outlet side of the pump through the waste heat supply line.

[0038] In addition, the present invention has the effect of enabling temperature control of the refrigerant caused by over-supply or under-supply of waste heat when generating power using various waste heats, by further including a refrigerant flow controller in the organic Rankine cycle section that controls the flow of the refrigerant in the refrigerant line so that the refrigerant flowing into the plurality of heat exchangers is controlled within a preset range.

[0039] However, the effects obtainable from the present invention are not limited to those described above, and other effects may exist.

[0040] FIG. 1 is a drawing illustrating an energy-saving ship equipped with a power generation device utilizing a conventional temperature difference.

[0041] FIG. 2 is a drawing illustrating a power generation system using waste heat according to an embodiment of the present invention.

[0042] FIG. 3 is a drawing illustrating a power generation system using waste heat according to another embodiment of the present invention.

[0043] FIGS. 4 and 5 are schematic diagrams of an organic Rankine cycle section (30) according to embodiments of the present invention.

[0044] FIG. 6 is a drawing illustrating a bypass (31a) and a bypass valve (371) provided according to an embodiment of the present invention.

[0045] FIG. 7 is a drawing illustrating a resupply line (31b) and a resupply valve (373) provided according to an embodiment of the present invention.

[0046] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0047] Throughout the specification of this invention, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "electrically connected" or "indirectly connected" with other elements interposed between them.

[0048] Throughout the entire specification of the present invention, when a member is described as being located "on," "on the upper," "on the top," "under," "on the lower," or "on the bottom" of another member, this includes not only cases where the member is in contact with the other member, but also cases where another member exists between the two members.

[0049] Throughout the specification of the present invention, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0050] In addition, terms related to direction or position (upper side, upper surface, lower side, etc.) in the description of the embodiments of the present invention are established based on the arrangement state of each component shown in the drawings.

[0051] Referring to FIG. 2, a power generation system (1) using waste heat according to one embodiment of the present invention connects various waste heat sources (10) of a ship, such as jacket water, surplus steam, scavenging air, and exhaust gas, to an organic Rankine cycle section (30) to supply waste heat sources, and by sequentially supplying waste heat sources with relatively low temperatures to waste heat sources with relatively high temperatures along the flow path from the pump outlet to the expander, power can be generated by utilizing various waste heat sources within the ship in combination.

[0052] In addition, as shown in Fig. 3, when the waste heat source is a steam generator, to prevent the generated steam from being condensed and wasted by a dump condenser without being fully utilized at the steam usage site, an organic Rankine cycle is configured using the excess produced steam to generate electricity from the surplus steam, and a pressure reduction buffer tank section is configured in front of the organic Rankine cycle section so that the excess produced steam is supplied to the organic Rankine cycle section consistently and continuously, thereby enabling stable power generation.

[0053] In this specification, referring to FIGS. 2 and 3, the refrigerant flows through the refrigerant line (31), and the refrigerant rotates the expander (32) in a gaseous state and then condenses in the condenser (34). The condensed liquid refrigerant is transferred from the condenser (34) through the pump (35), flows through a plurality of heat exchangers (36a to 36n), and then flows back to the expander (32). Depending on the flow of the refrigerant, the outlet and inlet ends of each component on the refrigerant line (31) can be defined. For example, the outlet end of the pump (35) may be the outlet on the heat exchanger (36a) side, and the inlet end of the expander (32) may be the inlet through which the refrigerant flows from the last heat exchanger (36n) to the expander (32).

[0054] Referring to FIG. 2, the power generation system (1) using waste heat may include a plurality of waste heat sources (10) and an organic Rankine cycle section (30). Additionally, referring to FIG. 3, when a steam generating section that generates steam is provided among the plurality of waste heat sources (10), the power generation system (1) using waste heat may include a pressure reduction buffer tank section (20), an organic Rankine cycle section (30), a dump condenser section (40), a feed tank section (50), and a fluid supply line section (60).

[0055] The waste heat source (10) may be various heat sources generated within the vessel. For example, the waste heat source (10) may be jacket water, scavenging air, exhaust gas, or excess steam used to cool the engine. Multiple waste heat sources may have various temperatures. For example, jacket water may be approximately 90 to 100 degrees, excess steam 150 to 170 degrees, scavenging air 200 to 220 degrees, and exhaust gas discharged from the engine 250 to 360 degrees. However, other waste heat sources may exist in addition to these.

[0056] Referring to FIG. 4, two waste heat sources (10a, 10n) can supply waste heat to the organic Rankine cycle section (30). Two waste heat sources among jacket water, scavenging air, exhaust gas, or excess steam can supply heat to the organic Rankine cycle section (30) to heat the refrigerant through heat exchange.

[0057] Referring to FIG. 5, three waste heat sources (10a, 10b, 10n) can supply waste heat to the organic Rankine cycle section (30). Three waste heat sources among jacket water, scavenging air, exhaust gas, or excess steam can supply heat to the organic Rankine cycle section (30) to heat the refrigerant through heat exchange.

[0058] Although two or three waste heat sources are shown in FIGS. 4 and 5, n waste heat sources (36a, 36b, 36n) connected to the organic Rankine cycle section (30) to supply waste heat may be provided.

[0059] Additionally, the waste heat supply line (11) may be configured to connect a plurality of waste heat sources (10) and an organic Rankine cycle section (30). Specifically, the waste heat supply line (11) may connect a plurality of waste heat sources (10) and a plurality of heat exchangers (36). In embodiments of the present invention, each waste heat source (10) may be understood to be connected to each heat exchanger (36) through the waste heat supply line (11) to supply waste heat generated from the waste heat source. That is, one waste heat source is connected to one heat exchanger (36) within the organic Rankine cycle section (30).

[0060] As illustrated in FIG. 3, if the waste heat source (10) is configured to generate steam, it may preferably be a steam-producing boiler. It may be configured to produce steam using waste heat generated from the ship's engine and condensate supplied from the feed tank section (50) described later. The produced steam is supplied to various steam usage points within the ship where steam is required. In this process, the present invention diverts excess steam to the pressure reduction buffer tank section (20) described later so that waste heat that is not fully used at the steam usage points can be utilized for power generation.

[0061] The pressure reduction buffer tank section (20) is formed on the steam supply line section (61) to be described later, and is located in front of the organic Rankine cycle section (30) as shown in FIG. 3, so as to maintain the pressure of the steam supplied to the organic Rankine cycle section (30) at a constant set pressure. Preferably, the pressure reduction buffer tank section (20) can regulate the pressure of the steam supplied to the organic Rankine cycle section (30) to a constant 7 bar. Therefore, if the pressure of the steam exceeds 7 bar, the excess portion can be supplied to the dump condenser section (40) to be described later and condensed. By configuring the pressure reduction buffer tank section (20) so that the excess produced steam is supplied consistently and continuously to the organic Rankine cycle section (30) to be described later, power can be produced stably.

[0062] In one embodiment, the pressure reduction buffer tank section (20) is connected to each heat exchanger (36) described later through a waste heat supply line (11) so as to supply waste heat to the heat exchanger.

[0063] The organic Rankine cycle section (30) is configured to produce electricity using thermal energy, and the present invention allows waste heat to be used for electricity production by heating the refrigerant within the organic Rankine cycle (30) using waste heat transferred from a plurality of waste heat sources (10). Preferably, the capacity of the organic Rankine cycle section (30) can be adjusted to match the steam usage of the ship, taking into account efficiency and boiler operation. Referring to FIGS. 4 and 5, the organic Rankine cycle section (30) may include a refrigerant line (31), an expander (32), a generator (33), a condenser (34), a pump (35), and a heat exchanger (36).

[0064] The refrigerant line (31) is configured such that refrigerant flows through it, and the refrigerant may be configured to pass through the heat exchanger (36) so that it is heated and vaporized by the heat exchanger (36). The refrigerant line (31) may form a closed curve so that the refrigerant circulates within it. The refrigerant flowing along the refrigerant line (31) is heated as it passes through a plurality of heat exchangers (36), and the gas evaporated as it passes through the last heat exchanger (36) at the inlet end of the expander rotates the expander (32) to produce electricity through the generator (33).

[0065] As illustrated in FIGS. 4 and 5, the refrigerant line (31) can circulate the refrigerant internally. The refrigerant rotates the expander (32) in a gaseous state and then condenses in the condenser (34). The condensed liquid refrigerant is transferred from the condenser (34) through a pump (35), flows through a plurality of heat exchangers (36a to 36n), and then flows back to the expander (32).

[0066] The expander (32) is configured to rotate by vaporized refrigerant and refers to a power engine that receives kinetic energy from the flow of fluid and converts it into rotational force. The expander (32) is connected to a generator (33) to be described later, and electricity can be produced by the rotational force of the expander as the gaseous refrigerant passes through the expander.

[0067] The generator (33) is configured to be connected to the expander (32) to produce electricity. As the expander (32) rotates due to the fluid flow of the evaporated refrigerant, electricity is produced in the generator (33) connected to the expander (32). According to the present invention, the effect of producing power required for ships, etc., by utilizing the waste heat of the remaining steam is obtained.

[0068] The above condenser (34) refers to a configuration that condenses the vaporized refrigerant discharged from the expander (32). The cooling source used for cooling in the condenser (34) of the organic Rankine cycle section (30) may be fresh water or seawater, but preferably, the vaporized refrigerant is condensed with the boil-off gas (BOG) of LNG, thereby utilizing the low-temperature gas naturally vaporized during LNG transport for cooling, which can increase system efficiency.

[0069] The above pump (35) is configured to transfer the liquefied refrigerant discharged from the above condenser (34) to the heat exchanger (36). The present invention configures the above condenser (34) and the pump (35) within the above organic Rankine cycle section (30) so that the vaporized refrigerant can be liquefied again and circulated. Referring to the embodiments illustrated in FIGS. 4 and 5, the refrigerant transferred from the outlet end of the pump (35) can be heated and heated or vaporized while passing through a plurality of heat exchangers (36a, 36n) in sequence.

[0070] The heat exchanger (36) is configured to heat the refrigerant in the refrigerant line circulating in the organic Rankine cycle section (30) to raise the temperature or vaporize it, and a plurality of heat exchangers may be arranged between the outlet end of the pump (35) of the refrigerant line (31) and the inlet end of the expander (32).

[0071] In one embodiment, the heat exchanger (36n) at the inlet end of the expander (32) can function as an evaporator. The refrigerant flowing along the refrigerant line (31) is heated as it passes through a plurality of heat exchangers (36a, 36b, 36n), and the refrigerant can be vaporized by waste heat supply at the last heat exchanger (36n) before entering the expander (32). That is, the refrigerant is vaporized as it passes through the heat exchanger (36n) closest to the inlet end of the expander (32). In addition, the refrigerant flowing along the refrigerant line (31) through a plurality of heat exchangers excluding the last heat exchanger (36n) can be gradually heated as it passes through the plurality of heat exchangers.

[0072] Referring to FIGS. 4 and 5, the temperature of waste heat supplied from a plurality of waste heat sources (10) to a plurality of heat exchangers (36a, 36b, 36n) arranged along the flow of the refrigerant line can be sequentially increased. As described above, the jacket water may be approximately 90 to 100 degrees, the excess steam 150 to 170 degrees, the scavenging air 200 to 220 degrees, and the exhaust gas discharged from the engine 250 to 360 degrees, and thus waste heat with different temperatures can be supplied to different heat exchangers depending on the temperature. For example, since the temperatures of the heat sources supplied from the waste heat sources increase in the order of jacket water, excess steam, scavenging air, and exhaust gas, the jacket water can be supplied to the first heat exchanger (36a) on the outlet side of the pump (35), and the excess steam can then be supplied to the second heat exchanger (36b). Additionally, exhaust gas can be supplied to the last heat exchanger (36n) on the inlet side of the expander (32).

[0073] Accordingly, the temperature of the waste heat supplied to the plurality of heat exchangers arranged according to the flow of the refrigerant line can be sequentially increased. And, a waste heat source with a relatively low temperature can be supplied to the heat exchanger (36) on the outlet side of the pump (35) through the waste heat supply line (11), and a waste heat source with a relatively high temperature can be supplied to the heat exchanger (36) on the inlet side of the expander (32) through the waste heat supply line.

[0074] Referring to FIGS. 6 and 7, the organic Rankine cycle section (30) may further include a refrigerant flow controller (37) that controls the flow of refrigerant in the refrigerant line (31) so that the refrigerant flowing into the plurality of heat exchangers (36) is controlled within a preset range. If waste heat is not properly supplied to the refrigerant line or is over-supplied, the temperature of the refrigerant in the refrigerant line may deviate from the preset range, and in this case, the refrigerant may vaporize excessively early or may not vaporize at all. For example, the refrigerant must be heated sequentially along the refrigerant line and vaporized at the last heat exchanger (36n) on the inlet side of the expander (32), but if waste heat is over-supplied, the refrigerant may vaporize at a heat exchanger other than the last one, and if waste heat is not properly supplied, the refrigerant may not vaporize sufficiently at the last one. Accordingly, the refrigerant flow controller (37) controls the flow of refrigerant in the refrigerant line (31) so that the refrigerant is normally vaporized in the last heat exchanger (36n) to rotate the expander (32) and produce power in the generator (33).

[0075] Referring to FIG. 6, a bypass (31a) may be provided within the refrigerant line (31) so that the refrigerant flows by bypassing the heat exchanger (36a) before entering the inlet end of the heat exchanger (36). A bypass valve (371) may be provided at the front end (pump side end) of the bypass (31a). A refrigerant flow controller (37) may control the refrigerant to bypass at least some of the heat exchanger (36) through the bypass (31a) when the temperature of the refrigerant within a predetermined section of the refrigerant line (31) is above a set range.

[0076] Although FIG. 6 is illustrated so that the bypass (31a) bypasses only one heat exchanger (36a), a bypass may be provided for each heat exchanger (36) within each refrigerant line (31), and the refrigerant flow controller (37) may detect the refrigerant temperature of each section within the refrigerant line (31) from a sensor that detects the refrigerant temperature of the refrigerant line (31). The refrigerant temperature sensing sensor may be placed near each heat exchanger. For example, the refrigerant temperature sensing sensor may be placed at the inlet and outlet ends of each heat exchanger (36).

[0077] Meanwhile, referring to FIG. 7, a resupply line (31b) may be provided within the refrigerant line (31) so that the refrigerant discharged to the outlet end of the heat exchanger (36) is resupplied to the heat exchanger (36a). A resupply valve (373) may be provided at the rear end (expander side end) of the resupply line (31b). The refrigerant flow controller (37) can control the refrigerant flow so that when the temperature of the refrigerant within a predetermined section of the refrigerant line (31) is below a set range, the refrigerant is resupplied to at least some of the heat exchangers (36) through the resupply line (31b) and further heated through the heat exchangers.

[0078] Although FIG. 7 shows a resupply line (31b) being resupplied to one heat exchanger (36a), a resupply line may be provided for each heat exchanger (36) within each refrigerant line (31).

[0079] In one embodiment, the bypass (31a) and the resupply line (31b) may be substantially the same pipe, and a bypass valve (371) and a resupply valve (373) may be provided at both ends of the pipe. The refrigerant flow controller (37) can detect the temperature of the refrigerant flowing through the heat exchanger (36) in the refrigerant line and control the flow of the refrigerant. If the temperature of the refrigerant is within the range set for each section of the refrigerant line (31), the refrigerant may be controlled so that it does not flow along the bypass (31a) or the resupply line (31b). Meanwhile, if the temperature of the refrigerant exceeds the range set for each section, the refrigerant flow controller (37) may control the bypass valve (371) or the resupply valve (373) to allow the refrigerant to flow along the bypass (31a) or the resupply line (31b).

[0080] The dump condenser unit (40) described above refers to a configuration that recovers and condenses steam exceeding the set pressure from the pressure reduction buffer tank unit (20). Preferably, when the set pressure exceeds 7 bar, excess steam can be allowed to flow toward the dump condenser unit (40). The present invention configures the dump condenser unit (40) to recover and condense steam exceeding the set pressure from the pressure reduction buffer tank unit (20), and also allows condensate generated at the steam usage site to be collected in one place.

[0081] The above feed tank section (50) is configured to be connected to the dump condenser section (40) and to receive and store condensate from the dump condenser section (40). Condensate condensed by cooling in the dump condenser section (40) is collected in the feed tank section (50) and stored in one place, and the feed tank section (50) is configured to provide the stored condensate to the steam generating section (10) via the condensate supply line section (65) to be described later.

[0082] Referring again to FIG. 3, the fluid supply line section (60) is a configuration that collectively refers to a pipeline for transporting fluid in a gaseous or liquid state, and the fluid supply line section (60) includes a steam supply line section (61), a waste heat supply line section (62), a steam recovery line section (63), a steam branch line section (64), and a condensate supply line section (65).

[0083] The above steam supply line section (61) refers to a configuration that supplies steam produced in the above steam generation section (10) to the above steam usage location. One side of the above steam supply line section (61) is connected to the above steam generation section (10), and the other side of the above steam supply line section (61) can be connected to the above steam usage location. A waste heat supply line section (62), which will be described later, is connected to the above steam supply line section (61) so that surplus steam that is not fully used at the above steam usage location can be branched out from the above steam supply line section (61) through the waste heat supply line section (62).

[0084] The waste heat supply line section (62) can be understood as being configured to be connected to the organic Rankine cycle section (30) and supply waste heat to the organic Rankine cycle section (30). Preferably, the waste heat supply line section (62) can be configured to supply waste heat to the organic Rankine cycle section (30) through steam. In this case, the steam refers to surplus steam that is produced by the steam generation section (10) which generates steam using waste heat but is not consumed at the steam usage site. One side of the waste heat supply line section (62) may be connected to the steam supply line section (61), and the other side may be connected to the organic Rankine cycle section (30). The waste heat supply line section (62) of FIG. 3 can be understood as having substantially the same configuration as the waste heat supply line (11) shown in FIG. 2.

[0085] The above steam recovery line section (63) is configured such that one side is connected to the pressure reduction buffer tank section (20) and the other side is connected to the dump condenser section (40), thereby transferring steam discharged from the pressure reduction buffer tank section (20) to the dump condenser section (40). As described above, the pressure reduction buffer tank section (20) always maintains a constant bar setting of steam so that steady electricity can be produced in the organic Rankine cycle section (30). When a situation occurs where the set pressure value is exceeded, excess steam is transferred to the dump condenser section (40) through the steam recovery line section (63).

[0086] The above steam branch line section (64) is configured such that one side is connected to the steam supply line section (61) and the other side is connected to the dump condenser section (40), thereby branching the steam flowing through the steam supply line section (61) to the dump condenser section (40). The present invention prevents an increase in pressure within the pipe by configuring the above steam branch line section (64) to recover and condense steam that cannot be used for power generation.

[0087] The above condensate supply line section (65) is configured such that one side is connected to the feed tank section (50) and the other side is connected to the steam generation section (10), thereby supplying the condensate stored in the feed tank section (50) to the steam generation section (10). The present invention improves system efficiency by configuring the above condensate supply line section (65) to supply condensate to the steam generation section (10), thereby allowing the condensate heated by engine waste heat to turn into steam, and thus recycling the condensed water. Referring to FIG. 5, the above condensate supply line section (65) includes a condensate pump (651).

[0088] The above condensate pump (651) is formed on the condensate supply line section (65) and is configured to allow the condensate flowing inside the condensate supply line section (65) to move toward the steam generating section (10). By means of the condensate pump (651), the condensate stored in the feed tank section (50) can be easily transported to the steam generating section (10).

[0089] Waste heat, which is the heat energy remaining from the heat energy generated by burning fuel in the ship's engine (E), can be used to produce steam in the steam generation unit (10). The steam generated in the steam generation unit (10) is supplied to various steam usage points on the ship where steam is needed through the steam supply line (61), and any unused steam can be moved to the organic Rankine cycle unit (30) through the waste heat supply line (62).

[0090] A pressure reduction buffer tank section (20) is formed upstream of the above organic Rankine cycle section (30) to supply a constant amount of steam at a constant pressure, so that the above organic Rankine cycle section (30) can produce steady, constant, and stable power. A heat exchanger (36) is inserted into the pressure reduction buffer tank section (20), and the heat exchanger (36) functions as an evaporator for the organic Rankine cycle.

[0091] The steam that has finished heat exchange in the heat exchanger (36) enters the dump condenser (40) through the steam recovery line (63) and is condensed, and the refrigerant that has been heated and evaporated in the heat exchanger (36) rotates the expander (32) in a gaseous state, and power is produced in the generator (33) by the rotational force of the expander (32).

[0092] The above-mentioned expander (32) is rotated, and the discharged gaseous refrigerant enters the above-mentioned condenser (34) to be cooled. Fresh water, sea water, or boil-off gas (BOG) of LNG can be used as the cooling source.

[0093] Meanwhile, the water condensed by the dump condenser (40) moves to the feed tank (50), where the condensed water is collected and stored, and then moves to the steam generation unit (10) through the condensed water supply line (65) to be used as water needed to make steam.

[0094] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0095] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

Claims

1. Organic Rankine cycle unit that produces electricity using thermal energy, It includes a waste heat supply line that supplies waste heat to the organic Rankine cycle from a plurality of waste heat sources, The above organic Rankine cycle section is, A refrigerant line forming a closed curve to allow refrigerant to circulate inside, A plurality of heat exchangers for heating the refrigerant in the above refrigerant line, Expander rotating by vaporized refrigerant, A generator connected to the above expander to produce electricity, A condenser for condensing the vaporized refrigerant discharged from the above-mentioned expander, and It includes a pump for transferring liquefied refrigerant discharged from the condenser to the heat exchanger side, A power generation system utilizing waste heat, characterized in that the above waste heat supply line connects a plurality of the above waste heat sources and a plurality of the above heat exchangers.

2. In Paragraph 1, A power generation system utilizing waste heat, characterized in that a plurality of the above-mentioned heat exchangers are disposed between the outlet end of the pump of the refrigerant line and the inlet end of the expander.

3. In Paragraph 2, A power generation system using waste heat, characterized in that the temperature of the waste heat supplied to a plurality of heat exchangers arranged according to the flow of the refrigerant line rises sequentially.

4. In Paragraph 3, A power generation system utilizing waste heat, characterized in that the above refrigerant vaporizes while passing through the heat exchanger closest to the inlet end of the expander.

5. In Paragraph 3, The above waste heat source includes two or more of jacket water for cooling the engine, excess steam, scavenging air, and exhaust gas, and A power generation system using waste heat, characterized in that a waste heat source with a relatively low temperature is supplied to a heat exchanger on the outlet side of the pump through the waste heat supply line.

6. In Paragraph 3, The above organic Rankine cycle section is, A power generation system using waste heat, characterized by further including a refrigerant flow controller that controls the flow of refrigerant in the refrigerant line so that the refrigerant flowing into a plurality of the heat exchangers is controlled within a preset range.

7. In Paragraph 6, A bypass is provided so that the refrigerant in the above refrigerant line bypasses at least a portion of the above heat exchanger, and A power generation system using waste heat, characterized in that the above refrigerant flow controller controls the refrigerant to bypass at least some heat exchangers through the bypass when the temperature of the refrigerant within a predetermined section of the refrigerant line is above a set range.

8. In Paragraph 6, A resupply line is provided so that the refrigerant in the above refrigerant line is resupplied to at least a portion of the above heat exchanger, and A power generation system using waste heat, characterized in that the above refrigerant flow controller controls the refrigerant to be additionally heated through at least some heat exchangers when the temperature of the refrigerant within a predetermined section of the refrigerant line is below a set range.

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