JP2008175108A - Rankine cycle power recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep Rankine cycle efficiency generally constant without wastefully using steam even if the heat quantity of the steam is changed, in a Rankine cycle power recovery device. <P>SOLUTION: This Rankine cycle power recovery device comprises: displacement expanders 5-1 or the like; steam opening/closing valves 15-1 or the like for the displacement expanders; a steam pressure detection means 30 for detecting the pressure of the steam generated by a steam generator 3; a recognizing means for recognizing the quantity of the operating displacement expanders 5-1 or the like; and a control device 31 for controllably increasing or decreasing the quantity of the operating displacement expanders. The steam pressure detected by the steam pressure detection means 30 is compared with a set pressure range corresponding to the quantity of the operating expanders recognized by the recognizing means. When the detected steam pressure exceeds the upper limit value of the appropriate steam pressure range, the quantity of the operating expanders is increased. When it is lower than the lower limit value, the quantity is controlled to be decreased. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a Rankine cycle power recovery device in which a plurality of expanders driven by steam are connected to a single steam generator, and the output of each expander is used for a common load portion whose rotation speed is restricted. About.

  A Rankine cycle power recovery device including an expander driven by steam is used in a power generator or an air compressor, and a steam turbine is generally used as the expander (Patent Document 1). When equipped with a steam turbine, it is suitable for a large power recovery device, such as a power generation device with an output of 100 MW level, but when used as a small output device utilizing the exhaust heat of an internal combustion engine, etc. Is not suitable because Rankine cycle efficiency is low because turbine efficiency is low.

Apart from this, as shown in FIG. 9, there is a Rankine cycle power recovery device provided with a positive displacement expander 206 such as a scroll expander, which is more efficient even with a small output than the device equipped with the steam turbine. Operate. 9, the steam generator 203 is connected to the exhaust device 202 of the internal combustion engine 201, and the steam inlet 206 a of the displacement expander 206 is connected to the steam outlet 203 b of the steam generator 203 via the throttle valve 205. It is connected. The steam outlet 206 b of the positive displacement expander 206 is connected to the inlet 210 a of the condenser 210, and the outlet 210 b of the condenser 210 is connected to the steam inlet 203 a of the steam generator 203 via the condensate pump 211. A bypass passage 215 is provided between the steam outlet 203b of the steam generator 203 and the steam outlet 206b of the positive displacement expander 206. A bypass valve 216 is disposed in the bypass passage 215, and another steam using device is used. 218 is connected. For example, an air compressor 218 is connected to the power take-out unit 217 of the positive displacement expander 206 as a load unit, and a rotation speed detection device 219 is provided, and the detected rotation speed is input to the control device 220. Then, the opening degree of the throttle valve 205 is controlled according to the rotational speed.
Japanese Patent No. 3166033

  The general features of the positive displacement expander will be briefly described. Since the volume ratio of the steam inlet and the steam outlet is determined, the ratio of the pressure after the end of the steam intake stroke and immediately before the start of discharge is determined. Therefore, when the steam outlet pressure of the positive displacement expander is constant and the steam inlet pressure decreases, the steam pressure once falls below the steam outlet pressure inside the positive displacement expander, and then returns to the outlet pressure at the start of discharge. In a so-called overexpanded state, unnecessary work is required. Therefore, as shown in the graph of FIG. 11, when the steam pressure at the steam inlet of the positive displacement expander falls below the design pressure (point C), the effective efficiency ratio of the positive displacement expander decreases. FIG. 11 is a graph showing the out-of-design performance of one positive displacement expander under a constant rotational speed. The vertical axis represents the effective efficiency ratio, and the horizontal axis represents the steam pressure at the steam inlet of the positive displacement expander. Point C is a design point as described above. After the steam starts to be supplied to the positive displacement expander, when the steam pressure reaches the operation start pressure P1, the effective efficiency ratio changes from 0 to a positive value, and the effective efficiency ratio is close to 1.0 due to the increase of the steam pressure. It rises rapidly until it reaches the design point C. When the steam pressure at the steam inlet decreases from the design point C, the effective efficiency ratio decreases as described above.

  Moreover, since the volume of the vapor | steam suck | inhaled per rotation is constant in a positive displacement expander, the volume flow rate of the vapor | steam inlet of a positive displacement expander is substantially proportional to a rotational speed. When the rotational speed is constant, the inlet volume flow is constant regardless of the expander inlet pressure. However, when one positive displacement expander is connected to the steam generator, as shown in FIG. 12, if the exhaust heat amount or the like decreases and the steam heat amount decreases, the positive displacement expander is used unless the rotational speed is reduced. The steam pressure at the steam inlet of the expander decreases. FIG. 12 is a graph showing changes in steam pressure and steam outlet pressure with respect to changes in steam heat amount of one positive displacement expander under a constant rotational speed, and the vertical axis shows the steam pressure and steam outlet volume flow rate, The horizontal axis is the amount of steam heat.

  9 adjusts the steam pressure supplied to the expander 206 by adjusting the opening of the throttle valve 205, and if the steam pressure exceeds the upper limit value of the proper steam pressure range of the expander 206. The surplus steam is bypassed or discarded via the bypass valve 216, and it cannot be said that exhaust heat is effectively recovered. Further, when the amount of steam used in the other steam-using device 218 increases and the inlet pressure of the expander 206 decreases, as shown in FIG. 13, due to a decrease in theoretical work and a decrease in expander effective efficiency, Rankine cycle efficiency drops rapidly, making power recovery difficult. That is, when there is a difference between the amount of steam generated and consumed by the steam generator 203, the power cannot be recovered efficiently. Therefore, the amount of steam generated by the steam generator 203 is overwhelmingly larger than the capacity of the expander 206, and is mostly applied when used in combination with other steam using devices 218.

[Object of the invention]
An object of the present invention is to provide a Rankine cycle power recovery device that can recover power without waste without reducing Rankine cycle efficiency even if the amount of steam heat (steam amount) generated by the steam generator increases or decreases.

  In order to solve the above-mentioned problem, in the invention according to claim 1 of the present application, a plurality of expanders driven by steam are connected to one steam generator, and the rotational speed of the output of each expander is restricted. In the Rankine cycle power recovery device used for a common load section, the expander includes a plurality of positive displacement expanders connected in parallel to the steam generator, and the steam upstream of the steam inlet of each positive displacement expander A steam on-off valve on each side, steam pressure detecting means for detecting the pressure of steam generated by the steam generator, and expander operation number recognition means for recognizing the number of operation of the positive displacement expander, A control device is provided for controlling the number of expander operations by opening and closing each steam on-off valve. The control device stores in advance an appropriate steam pressure range for each number of expander operations, and the steam pressure detection means Comparing the generated steam pressure with the appropriate steam pressure range corresponding to the number of expander operating units recognized by the expander operating unit number recognizing means, the detected steam pressure exceeded the upper limit value of the appropriate steam pressure range In this case, the number of expander operating units is increased, and when the detected steam pressure falls below the lower limit value of the appropriate steam pressure range, the opening / closing of the steam on / off valves is controlled so as to decrease the number of expander operating units.

  According to the above configuration, even if the amount of heat of the internal combustion engine or the like that serves as a heat source fluctuates and the amount of steam generated by the steam generator fluctuates, the volume type is increased or decreased according to the fluctuation of the amount of steam generated. The pressure of the steam supplied to the expander can be kept substantially constant. In particular, when a steam using device is connected to the steam generator in addition to the positive displacement expander, the pressure of the steam supplied to the positive displacement expander even if the steam usage of the other steam using device fluctuates. Is kept approximately constant. As a result, the theoretical efficiency of the Rankine cycle can also be maintained near the original planned value, which is optimal when supplying electric power or the like to a load portion where the rotational speed is restricted. Further, since the decrease in the effective efficiency of the positive displacement expander is suppressed, the actual Rankine cycle efficiency, that is, the theoretical recovery power x the expander effective efficiency (= recovery power) / heat input can be kept high. In other words, even if the amount of steam that can be used in the Rankine cycle power recovery device varies, the recovered power / heat input can be kept at a high value, so that the exhaust heat or the like can be efficiently converted into power.

  According to a second aspect of the present invention, in the Rankine cycle power recovery device according to the first aspect, exhaust heat of the internal combustion engine is introduced into the steam generator as a heat source of the steam generator, and the output portion of the internal combustion engine and the A power take-out portion of each positive displacement expander is connected by a one-way clutch and a power transmission mechanism capable of transmitting power only from the positive displacement expander side to the internal combustion engine side.

  According to the above configuration, since power is transmitted from the positive displacement expander side to the output portion of the internal combustion engine via the one-way clutch, it is connected only when the positive displacement expander performs positive work with respect to the internal combustion engine. When only work is possible, the positive displacement expander side is not driven from the internal combustion engine side. Therefore, the output corresponding to the rotation speed determined by the internal combustion engine and the pressure of the supplied steam can be recovered. That is, the power can be efficiently recovered over a wide load range of the internal combustion engine, which is suitable when the internal combustion engine is driving a mechanical load or a generator load with constant rotation.

  According to a third aspect of the present invention, in the Rankine cycle power recovery device according to the first aspect, exhaust heat of the internal combustion engine is introduced into the steam generator as a heat source of the steam generator, and the output portion of the internal combustion engine and the The power take-out part of each positive displacement expander is connected by an electromagnetic clutch and a power transmission mechanism.

  According to the above configuration, if the rotational speed of the positive displacement expander reaches a predetermined value, the clutch is engaged and a load is applied. Therefore, the output corresponding to the rotational speed determined by the internal combustion engine and the pressure of the supplied steam is recovered. it can. This is also suitable when the internal combustion engine is driving a constant rotation mechanical load or generator load.

  According to a fourth aspect of the present invention, in the Rankine cycle power recovery device according to the second or third aspect, a power transmission mechanism and an electromagnetic clutch are provided between the output part of the internal combustion engine and the power take-out part of each positive displacement expander. Alternatively, a speed change mechanism is provided in addition to the one-way clutch.

  According to the above configuration, even if the rotational speed of the internal combustion engine changes, the speed ratio is changed by the speed change mechanism so that the rotational speed of the positive displacement expander becomes constant, so a marine main engine that drives a propeller for ship propulsion etc. Suitable for

  According to a fifth aspect of the present invention, in the Rankine cycle power recovery device according to the first aspect, exhaust heat of an internal combustion engine is introduced into the steam generator as a heat source of the steam generator, and the power of each positive displacement expander is An induction generator is connected to the take-out portion, and a power generation device is connected to the internal combustion engine as the common load portion, and each induction generator is electrically connected to the power generation device.

  The above configuration is effective when applied to a power generation apparatus such as a marine auxiliary engine that also has partial load operation.

  The invention according to claim 6 is the Rankine cycle power recovery device according to claim 5, wherein the internal combustion engine is provided with a water-cooled internal combustion engine, the internal combustion engine is provided with a low-pressure steam generator for evaporating cooling water, A plurality of low-pressure volume displacement expanders connected in parallel to the low-pressure steam generator, each having a low-pressure steam on-off valve on the steam upstream side of the steam inlet of each of the low-pressure displacement expanders; A low-pressure system steam pressure detecting means for detecting the pressure of the cooling water steam generated inside, and a low-pressure system expander operating number recognition means for recognizing the number of operating low-pressure volumetric expanders, The appropriate steam pressure range is stored in advance for each number of low-pressure system expander operating units, and the steam pressure detected by the low-pressure system steam pressure detecting unit is recognized by the low-pressure system expander operating unit number recognizing unit. Compared with the appropriate steam pressure range corresponding to the number of operating pressure system expanders, if the detected steam pressure exceeds the upper limit of the appropriate steam pressure range, the number of operating low pressure system expanders is increased, the detected steam When the pressure falls below the lower limit value of the appropriate steam pressure range, the low-pressure system steam on / off valves are controlled so as to reduce the number of low-pressure system expanders operated.

  According to the above configuration, the exhaust heat of one internal combustion engine and the waste heat of the cooling water can be used effectively, and the cooling is also performed from the high-pressure Rankine cycle system using the exhaust heat according to the load fluctuation of the internal combustion engine. Power can also be efficiently recovered from a low-pressure Rankine cycle system that uses waste heat of water.

[First Embodiment]
1 to 3 show a first embodiment of a Rankine cycle power recovery device according to the present invention, and the first embodiment will be described with reference to these drawings.

  FIG. 1 is a schematic diagram of piping of a Rankine cycle power recovery device. The Rankine cycle power recovery device includes a single internal combustion engine 1, a single steam generator 3 connected to an exhaust device 2 of the internal combustion engine 1, A plurality of, for example, six positive displacement expanders (such as scroll expanders) 5-1, 5-2,... 5-6, one condenser 7, one condensate pump 8, etc. , And 5-6, induction generators 9-1, 9-2,..., 6-6 are connected to the power take-out portions of the positive displacement expanders 5-1, 5-2,. The machines 9-1, 9-2,..., 9-6 are connected to a common load section 11, for example, a commercial power line such as factory power, via the electric switches 10-1, 10-2,. Electrically connected. The six positive displacement expanders 5-1, 5-2,... 5-6, the six induction generators 9-1, 9-2,. 1, 10-2,..., 10-6 are shown as three and three for simplification of the drawing, and the remaining three and three are omitted.

  The steam passage 13 connected to the steam outlet 3b of the steam generator 3 includes six branch passages 13a for the expander, one branch passage 13b for the safety valve, and one other steam-using device 18. The branch passages 13a for the expanders are respectively connected to the positive displacement expanders 5-1, 5-2 via the steam on-off valves 15-1, 15-2,. ,..., 5-6 are respectively connected to the steam inlets, the branch passage 13b for the safety valve is connected to the safety valve 17 via the steam on / off valve 16, and the branch passage 13c for the other steam using device 18 is the other steam using device. 18 is connected.

  Vapor passages 20a and 20b connected to the respective positive displacement expanders 5-1, 5-2,... 5-6 and the vapor outlet of the safety valve 17 are gathered into one vapor passage 20 to be the vapor inlet of the condenser 7. The outlet of the condenser 7 is connected to the inlet of the condensate pump 8, and the outlet of the condensate pump 8 is connected to the steam inlet 3 a of the steam generator 3.

  As is well known, each induction generator 9-1, 9-2,... It is configured to exhibit any of the functions of the machine, the electric motor, and the brake, and specifically, it functions as any device depending on the value of the slip S = (Ns−N) / Ns. For example, when the actual rotational speed N is higher than the synchronous rotational speed Ns and the slip S <0, it functions as a generator, and when the actual rotational speed N is lower than the synchronous rotational speed Ns and 0 <slip S <1, It functions as an electric motor, and further functions as a brake when the actual rotational speed N is lower than the synchronous rotational speed Ns and 1 <slip S.

  In this embodiment, since the induction generators 9-1, 9-2,... 9-6 are used as generators, the slip S is −0.03 to (−0.05) (the slip rate is −3. The rotational speed is constrained to be about -5%. For example, if the synchronous rotational speed Ns is 1800 rpm under the condition of 60 Hz, the actual rotational speed N of the positive displacement expanders 5-1, 5-2,... 5-6 is restricted to a rotational speed of about 1854 rpm to 1890 pm. Configured to be.

(Control system)
In the steam passage 13 connected to the steam outlet 3b of the steam generator 3, a steam pressure detecting means 30 for detecting the pressure of the steam generated by the steam generator 3 is arranged. The steam pressure detecting means 30 is a control device. The detected steam pressure is input to the control device 31.

  The steam on / off valves 15-1, 15-2,... 15-6 and 16 are electrically connected to the control device 31, and each steam on / off valve 15 is controlled by an open / close command signal from the control device 31. -1, 15-2, ... 15-6 and 16 are controlled to be opened and closed. In addition, each of the steam on-off valves 15-1, 15-2,... 15-6 is configured to input the open / closed state of the steam on / off valves 15-1, 15-2,. The control device 31 recognizes the number of displacement-type expander operating units by counting the number of the steam opening / closing valves 15-1 for the expander in the open state. In addition to the method of counting the number of open steam on-off valves as described above, the power take-out section of the positive displacement expanders 5-1, 5-2,. It is also possible to adopt a method of detecting whether or not the vehicle is rotating and recognizing that it is in an operating state when rotating.

(Control content)
The storage unit in the control device 31 stores an appropriate steam pressure range that is set in advance for each of the operating units of the positive displacement expanders 5-1, 5-2,. To the steam pressure detected by the steam pressure detecting means 30 and the number of operating capacity expansion machines 5-1, 5-2,... 5-6 recognized by the expanding machine operating number recognition means. When the detected steam pressure exceeds the upper limit value of the proper steam pressure range, the number of the capacity expansion machines 5-1, 5-2,. When the detected steam pressure falls below the lower limit value of the appropriate steam pressure range, the steam on / off valves 15-1, 15-2,... It is programmed to control the opening and closing of -6. That is, when the detected steam pressure exceeds the upper limit value of the appropriate steam pressure range, a new closed steam on-off valve is opened, and the detected steam pressure falls below the lower limit value of the appropriate steam pressure range. Outputs a command signal to close one open steam on-off valve.

  FIG. 2 is a graph showing the relationship between the amount of steam heat (steam amount), the detected steam pressure, and the number of operating expanders in the Rankine cycle power recovery device of FIG. Graph X1 shows the change in the steam pressure at the steam outlet 3b of the steam generator 3, the solid line shows the change when the pressure rises, and the broken line shows the change when the pressure drops. Graph X2 shows the change in the number of operating expanders. The solid line shows the change when the pressure rises, and the broken line shows the change when the pressure drops.

  PH1 and PL1 are the upper limit of steam pressure and the lower limit of steam pressure when one expander is operating, PH2 and PL2 are the upper limit of steam pressure and the lower limit of steam pressure when two expanders are operating, PH3 and PL3 are the upper limit of steam pressure and the lower limit of steam pressure when three expanders are operating, PH4 and PL4 are the upper limit of steam pressure and the lower limit of steam pressure when four expanders are operating, PH5 and PL5 are the vapor pressure upper limit and vapor pressure lower limit when the number of expanders operating is 5, and PH6 and PL6 are the vapor pressure upper limit and vapor pressure lower limit when the number of expanders is 6 is there. That is, the pressure range between PH1 and PL1 is the proper steam pressure range when the number of expander units is one, and the pressure range between PH2 and PL2 is the appropriate range when the number of expander units is two The steam pressure range, the pressure range between PH3 and PL3 is the proper steam pressure range when the number of expander units is 3, and the pressure range between PH4 and PL4 is 1 unit of expanders Is the proper steam pressure range at the time of, the pressure range between PH5 and PL5 is the proper steam pressure range when the number of expander operation is one, and the pressure range between PH6 and PL6 is the expander operation This is the proper steam pressure range when the number is one.

  In this embodiment, the vapor pressure upper limit values PH1, PH2, PH3, PH4, PH5, and PH6 are set to substantially the same value, while the vapor pressure lower limit value is PL1 <PL2 <PL3 <PL4 <PL5 <. It is set to be PL6. In addition, each steam pressure lower limit value PL2, PL3, PL4, PL5, PL6 is a little lower than each steam pressure value PD2, PD3, PD4, PD5, PD6 that decreased when the number of expander units increased by one. Is set. For example, the amount of steam heat (steam amount) QH1, QH2, QH3, QH4, QH5, QH6 at each point of time when the number of expander operating units is added to the expander inlet pressure corresponding to about 5% less steam heat, Steam lower limit values PL2, PL3, PL4, PL5, and PL6 are set. Explaining with a specific example, if the steam heat amount (steam amount) when the number of operating units is increased from one to two is QH1, the steam pressure PL2 corresponding to the heat amount QL2 which is approximately 5% less than the steam heat amount QH1. Is the lower limit for reducing the number of expander operations from two to one. Other lower limit values PL3, PL4, PL5, and PL6 are set similarly to PL2. However, the lower limit value PL1 that decreases from one to zero is set to the steam pressure 0 as shown, but the operation start pressure value P1 in FIG. 11 can also be set to the lower limit value PL1. .

  Further, in FIG. 1, six steam on-off valves 15-1, 15-2,... 15-6 are arranged in the above order from the steam on-off valve 15-1 as the amount of steam heat generated in the steam generator 3 increases. It is set so that it opens and closes in the reverse order with the decrease in the amount of steam heat generated in the steam generator 3. Further, the steam on / off valve 16 of the safety valve 17 is configured so that the steam pressure in FIG. 2 after the steam on / off valve 15-6 of the sixth positive displacement expander 9-6 is opened is the upper limit of the steam pressure of six expander units. It is set to open when the value PH6 is reached.

(Operation)
(1) First, the basic operation of the Rankine cycle power recovery device will be described with reference to FIG. The condensed water supplied from the condensate pump 8 into the single steam generator 3 is heated and evaporated in the steam generator 3 by the heat of the exhaust gas discharged to the exhaust device 2 of the internal combustion engine 1. The steam is discharged from the steam outlet 3b to the steam passage 13.

(2) Among the six expander steam on-off valves 15-1, 15-2,... 15-6, for example, n expander steam on-off valves 15-1,. Then, the steam in the steam passage 13 is supplied to the corresponding expanders 5-1,..., 5-n through the open expander steam opening / closing valves 15-1,. By expanding in the positive displacement expanders 5-1,..., 5-n, the power take-out shaft is rotated, thereby driving the corresponding induction generators 9-1,. The generated electric power is supplied to the common load unit 11 via the electric switches 10-1,..., 10-n.

(3) During operation, the steam expanded in each of the expanders 5-1,..., 5-n is collected in one steam path 20 through each branch path 20 a and supplied to the condenser 7. The condensed water that has been cooled and condensed in the condenser 7 is sent to the condensate pump 8 again.

(control)
(1) While operating the Rankine cycle power recovery device, the positive displacement expander 5 is caused by fluctuations in the amount of heat of the exhaust gas discharged to the exhaust device 2 of the internal combustion engine 1 or fluctuations in the steam consumption of other steam-using devices 18. The amount of steam heat that can be used in -1,..., 5-n, that is, the amount of steam heat (steam amount) generated by the single steam generator 3 varies. The steam pressure at the steam outlet 3b also fluctuates with such a variation in the amount of steam heat generated by the steam generator 3, and the variation in the steam pressure is detected by the steam pressure detecting means 30 and input to the control device 31. .

  On the other hand, from each of the steam on-off valves 15-1, 15-2,... 15-6, their open / closed state is input to the control device 31, and thereby the number of expander operation n is recognized.

(2) In the control device 31, the arithmetic unit compares an appropriate steam pressure range (PHn to PLn) corresponding to the number of expander operating units n stored in advance with the detected steam pressure, and detects the detected steam. When the pressure exceeds the upper limit value PHn of the appropriate steam pressure range, an opening command signal is sent to the (n + 1) th steam on / off valve 15- (n + 1), and the steam on / off valve 15- (n + 1) is turned on. Open, thereby adding one (n + 1) expander operation unit. On the contrary, when the detected steam pressure is lower than the lower limit value PLn of the appropriate steam pressure range, a close command signal is sent to the nth steam on / off valve 15-n, and the steam on / off valve 15-n) is turned on. Close, thereby reducing the number of expander units by one to (n-1) units. When the number of expander units increased from n to n + 1, the steam pressure rapidly decreases to PDn as shown in FIG. 2, but the steam pressure lower limit value PLn so as not to decrease to the steam pressure lower limit value PHLn. Therefore, it is possible to avoid a situation in which the number of expander operations decreases immediately after the number of expander operations increases.

(3) In addition, when all of the six positive displacement expanders 5-1, 5-2,... 5-6 are operating, the detected steam pressure is within the proper steam pressure range corresponding to the number of expander units. When the upper limit value PH6 is exceeded, the steam on-off valve 16 connected to the safety valve 17 is opened, and excess steam is bypassed to the condenser 7.

(Effect of embodiment)
Even if the amount of steam generated by the steam generator 3 (steam amount) fluctuates due to fluctuations in the amount of heat of the exhaust gas of the internal combustion engine 1 or fluctuations in the amount of steam consumed by the other steam-using equipment 18, it depends on the amount of steam heat. Thus, since the number of operating expanders is increased or decreased, the vapor pressure of the steam supplied to each positive displacement expander can be kept substantially constant. As a result, as shown in FIG. 3, the theoretical efficiency of the Rankine cycle can be maintained near the planned value, and the effective efficiency of the expander does not decrease so much, so the actual Rankine cycle efficiency (theoretical recovery power × expander effective) Efficiency (= recovery power) / heat input) can be kept high. That is, even if the amount of steam that can be used in the Rankine cycle power recovery device varies, the recovered power / heat input can be maintained at a high value, and heat can be efficiently converted into power.

[Second Embodiment]
FIG. 4 shows a second embodiment of the present invention in which mechanical power is returned to the output shaft 44 of the internal combustion engine 1 from the heat of the exhaust gas of the internal combustion engine 1 such as a diesel engine, gas engine, gas turbine or the like. The same parts and members as those in FIG. 1 are denoted by the same reference numerals (numbers), and detailed description thereof is omitted.

  In FIG. 4, a driving shaft (crank shaft or the like) of the internal combustion engine 1 is connected to an output shaft 44 via a speed reducer 43, and the output shaft 44 is required to rotate at a constant rotational speed. It is connected to a load portion (for example, a blower fan) 45. The output shaft 44 is provided with a rotational speed detecting means 47, which is connected to the fuel metering device 46 of the internal combustion engine 1 so that the rotational speed of the output shaft 44 becomes a substantially constant value. Weigh out.

  In order to give auxiliary power to the output shaft 44, one-way clutches 40-1,... 40-6 are connected to the power take-out portions of the positive displacement expanders 5-1,. The one-way clutches 40-1,... 40-6 are connected to the output shaft 44 of the speed reducer 43 via a winding power transmission mechanism 41 using a chain or a belt. The one-way clutch 40-1,... 40-6 transmits power from the expander side to the output shaft 44 side of the speed reducer 43 only when doing positive work with respect to the output shaft 44. When the power from the expander side is 0 or only negative work is possible with respect to the output shaft 44 of 43, the power is not transmitted from the output shaft 44 side of the speed reducer 43 to the expander side. .

  The steam generator 3 is equipped with a liquid level detection device 49 for detecting the amount of water supplied from the condensate pump 8, and the liquid level data detected by the liquid level detection device 49 is controlled by the control device 31. To enter. Based on the detected liquid level data, the control device 31 issues an operation command to the condensate pump 8 so as to maintain a predetermined liquid level, and controls the discharge amount by the condensate pump 8.

  Regarding the operation of each positive displacement expander 5-1,..., 5-6, each positive displacement expander 5-1,... 5-6 performs positive work on the output shaft 44 of the transmission 43. The corresponding steam on-off valves 15-1,... 15-6 are not opened until.

  According to the present embodiment, the output (mechanical power) corresponding to the rotation speed of the output shaft 44 determined by the internal combustion engine 1 and the supplied steam pressure can be recovered, and the exhaust heat quantity of the internal combustion engine 1 is reduced. However, the amount of steam commensurate with it flows stably in the steam passage 13 and the branch passage 13a, and power can be recovered efficiently over a wide load range of the internal combustion engine. The present embodiment is suitable when the internal combustion engine is driving a mechanical load or a generator load with a constant rotation.

[Third Embodiment]
FIG. 5 shows a third embodiment. Instead of the one-way clutch of the second embodiment shown in FIG. 4, the electromagnetic clutches 51-1 to 51-6 are replaced with corresponding positive displacement expanders 5-1. ,..., 5-6 are connected to the power take-out portions, and the electromagnetic clutches 51-1 to 51-6 are electrically connected to the control device 31. The same parts and members as those in FIG. 4 are denoted by the same reference numerals (numbers), and detailed description thereof is omitted.

  Rotational speed detecting means 52-1 to 52-6 are respectively provided in the power take-out portions of the positive displacement expanders 5-1,... 5-6, and the detected positive displacement expanders 5-1,. 6 is input to the control device 31.

  In the control device 31, the rotational speed detected by the rotational speed detecting means 52-1 to 52-6 reaches a predetermined rotational speed, for example, a rotational speed at which the output shaft 44 of the speed reducer 43 can perform positive work. At this time, the corresponding electromagnetic clutch 51-1 or the like is connected, and power is transmitted to the output shaft 44 of the transmission 43 via the winding power transmission mechanism 41.

  Similar to the second embodiment, the structure of this embodiment is also suitable when the internal combustion engine is driving a mechanical load or a generator load of constant rotation.

[Fourth Embodiment]
FIG. 6 shows a fourth embodiment. In addition to the configuration of the second embodiment shown in FIG. 4, the distance between the driven portion of the power transmission mechanism 41 and the output shaft 44 of the speed reducer 43 of the internal combustion engine 1. In addition, a continuously variable transmission 60 such as a belt type is disposed, and a rotational speed detecting means 61 is provided in the power transmission mechanism 41. The rotational speed detecting means 61 and the continuously variable transmission 60 are electrically connected to the control device 31. The same parts and members as those in FIG. 4 are denoted by the same reference numerals (numbers), and detailed description thereof is omitted.

  The rotational speed detection means 47 and 61 detect the rotational speed of the output shaft 44 of the internal combustion engine 1 and the rotational speed on the drive unit side of the power transmission mechanism 41, and the control device 31 compares both rotational speeds to determine the power. The gear ratio of the continuously variable transmission 60 is changed so that the rotational speed of the transmission mechanism 41 shifts to a speed that matches or slightly increases the rotational speed of the output shaft 44 of the internal combustion engine 1.

  That is, even when the rotational speed of the output shaft 44 of the internal combustion engine 1 is changed, the rotational speed of the positive displacement expander 5-1,... 5-6 is changed by changing the speed ratio of the continuously variable transmission 60. The power can be recovered efficiently.

  The embodiment is suitable for a marine main engine that drives a propeller for marine propulsion and the like. In other words, even if the rotation speed of the propeller 45 is changed in order to change the navigation speed of the ship with a propeller as the load portion 45, the exhaust heat of the internal combustion engine 1 can be efficiently recovered.

[Fifth Embodiment]
FIG. 7 shows a fifth embodiment in which the power of each positive displacement expander 5-1 to 5-6 is collected as an electrical output. The internal combustion engine 1 is coupled to a synchronous generator 70, and the synchronous generator 70 is electrically connected to a power supply line 72 via a switch 71. The synchronous generator 70 is provided with a rotational speed detection device 73 for detecting the rotational speed of the synchronous generator 70, and the rotational speed detection means 73 is connected to the fuel metering device 46 of the internal combustion engine 1 to synchronize. The fuel is metered so that the rotational speed of the generator 70 becomes a substantially constant value. Dielectric generators 9-1,... 9-6 are respectively connected to the power take-out portions of the positive displacement expanders 5-1,... 5-6, and the dielectric generators 9-1,. 10-1 through 10-6 are connected to the power supply line 72. Each of the dielectric generators 9-1,... 9-6 is provided with rotational speed detecting means 75-1,... 75-6, and the detected generator rotational speed is input to the control device 31. . Other structures are the same as those of the first embodiment in FIG. 1, and the same components are denoted by the same reference numerals.

  In order to obtain a constant frequency, the synchronous generator 70 depends on the load by the rotational speed obtained from the rotational speed detecting means 73 provided in the synchronous generator 70 and the fuel metering device 46 as described above. The internal combustion engine 1 is operated at a constant rotational speed by adjusting the fuel amount.

  As the required power generation amount increases or decreases, the temperature of the exhaust gas discharged to the exhaust device 2 of the internal combustion engine 1 increases or decreases, and the amount of steam generated in the steam generator 3 increases or decreases. For such an increase / decrease in the amount of steam, similarly to the operation described in the first embodiment, the number of the open / close valves 15-1,. . For example, when the amount of steam is increased and one of the steam on / off valves 5-1 to 5-6 is newly opened, the expander 5- ( The rotational speed of the induction generator 9- (n + 1) connected to n + 1) is detected by the rotational speed detecting means 75- (n + 1), and when the speed rises to near the synchronous speed, the electric switch 10- (n + 1) is turned on. To control. On the other hand, when the amount of steam decreases and one of the steam on / off valves 5-1 to 5-6 is closed, the corresponding switch 10-n is disconnected.

  This embodiment is suitable for a power generation apparatus such as a marine auxiliary engine that has partial load operation.

[Sixth Embodiment]
FIG. 8 shows a sixth embodiment. As in the fifth embodiment shown in FIG. 7, the internal combustion engine includes a high-pressure Rankine cycle system that recovers electrical output from the exhaust heat of the internal combustion engine 1. It has a low-pressure Rankine cycle system that recovers electrical output from the waste heat of one cooling water. The same parts as those in FIG.

  The low-pressure Rankine cycle system using the cooling water of the internal combustion engine 1 has, for example, six positive displacement expanders 85-1,... 85-6, and each positive displacement type, similar to the high-pressure system using the exhaust heat. Six steam on-off valves 86-1 for the expander, 86-6, ... 86-6, one condenser 87, and one condensate pump 88, each of the positive displacement expanders 85-1, ... 85-6 are connected to induction generators 89-1, ... 89-6, respectively, and the induction generators 89-1, ... 89-6 are connected to electrical switches 90-1, ... 90-6, respectively. Are electrically connected to a common power supply line 72. In addition, a safety valve 91 and a safety valve steam opening / closing valve 92 are provided in parallel with the positive displacement expanders 85-1,... 85-6, and the induction generators 89-1,. Are provided with rotational speed detecting means 93-1,... 93-6, respectively.

  As a low-pressure steam generator, an evaporation tank (steam generator) 82 is provided above an engine portion (cylinder or the like) 81 that requires cooling of the internal combustion engine 1, and the steam generated inside the engine is stored in the evaporation tank 82. To guide you. The evaporation tank 82 is connected to each of the steam on-off valves 86-1,... 86-6, 91 through a steam passage 84. A liquid level detector 83 is attached to the evaporation tank 82, and the flow rate of the condensate pump 88 is controlled by a liquid level signal from the liquid level detector 83.

  The open / close control of the plurality of low-pressure steam on-off valves 86-1,... 86-6, 92 is performed by the high-pressure expanders 5-1, 5-2,. Same as control.

  According to this embodiment, in the Rankine cycle power recovery system including a single internal combustion engine 1, the cooling water is also supplied from the high-pressure Rankine cycle system using exhaust heat according to the load fluctuation of the internal combustion engine 1. Power can also be efficiently recovered from low-pressure Rankine cycle systems that use waste heat.

[Other embodiments]
(1) In the first embodiment of FIG. 1, as shown in FIG. 2, the vapor pressure upper limit values PH1, PH2, PH3, PH4, PH5, PH6 corresponding to the number of operating expanders are substantially equal. However, it is also possible to set the relationship PH1 <PH2 <PH3 <PH4 <PH5 <PH6. That is, it is possible to set the steam upper limit value to be gradually increased as it goes from PH1 to PH6.

(2) Although each said embodiment is a steam circulation type which condenses the vapor | steam utilized with the positive displacement expander and uses again, this invention is utilized with a positive displacement expander without utilizing a condenser. It is also applicable to an open type that discards the steam and supplies new steam to the steam generator.

(2) In the fifth and sixth embodiments shown in FIGS. 8 and 9, all the steam generated by the steam generator 3 and the evaporation tank 83 is removed from the positive displacement expanders 5-1, 5-2,. Although it is the structure used in No. 6, it is applicable also when using in parallel with other steam using equipment. In that case, it becomes a thermoelectric variable system with high power conversion efficiency.

1 is a schematic piping diagram showing a first embodiment of a Rankine cycle power recovery device according to the present invention. It is a figure which shows the change of the steam pressure with respect to the change of steam calorie | heat amount, and the number of expansion machine operation. It is the figure which showed the change of Rankine cycle efficiency with respect to the change of steam calorie | heat amount in the Rankine cycle power recovery system provided with the some expander, and compared the Rankine cycle efficiency in consideration of the expander effective efficiency. It is piping schematic which shows 2nd Embodiment of the Rankine cycle power recovery device by this invention. It is piping schematic which shows 3rd Embodiment of the Rankine cycle power recovery device by this invention. It is piping schematic which shows 4th Embodiment of the Rankine cycle power recovery device by this invention. It is piping schematic which shows 5th Embodiment of the Rankine cycle power recovery device by this invention. It is piping schematic which shows 6th Embodiment of the Rankine cycle power recovery device by this invention. It is a piping schematic diagram of a conventional example. It is a piping schematic diagram of another conventional example. It is a figure which shows the general off-design performance of a positive displacement expander. It is a figure which shows the change of the vapor | steam pressure with respect to the change of the steam calorie | heat amount of one positive displacement expander on conditions with a constant rotational speed, and a steam exit pressure. It is the figure which showed the change of Rankine cycle efficiency with respect to the change of steam calorie | heat amount in the Rankine cycle power recovery system provided with the single expander, and compared the Rankine cycle efficiency which considered the expander effective efficiency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Exhaust device 3 Steam generator 7 Condenser 8 Condensate pump 5-1, 5-2, ... 5-6 Positive displacement expander 9-1, 9-2, ... 9-6 Induction generator 10- DESCRIPTION OF SYMBOLS 1, 10-2, ... 10-6 switch 15-1, 15-2, ... 15-6 Steam on-off valve 30 Steam pressure detection means 31 Control apparatus 82 Low pressure system evaporation tank (low pressure system steam generator)
85-1, ... 85-6 Low-pressure type positive displacement expander 86-1, ... 86-6 Low-pressure system steam on-off valve 87 Low-pressure system condenser 88 Low-pressure system condensate pump 89-1, 89-2, ... 89-6 Low voltage system induction generator 90-1, 90-2, ... 90-6 Low voltage system switch

Claims (6)

In a Rankine cycle power recovery device that connects a plurality of expanders driven by steam to a single steam generator, and uses the output of each expander for a common load portion in which the rotational speed is restricted,
As the expander, comprising a plurality of positive displacement expanders connected in parallel to the steam generator,
A steam on-off valve is provided on the steam upstream side of the steam inlet of each positive displacement expander,
Steam pressure detection means for detecting the pressure of the steam generated by the steam generator;
An expander operation number recognition means for recognizing the number of operation of the positive displacement expander;
Comprising a control device for controlling the number of expander operations by opening and closing each of the steam on-off valves,
The controller stores in advance an appropriate steam pressure range for each number of expander operations, and determines the steam pressure detected by the steam pressure detection means and the number of expander operations recognized by the expander operation number recognition means. Compared with the corresponding appropriate steam pressure range, if the detected steam pressure exceeds the upper limit value of the appropriate steam pressure range, the number of expander operation is increased, the detected steam pressure is the lower limit of the appropriate steam pressure range A Rankine cycle power recovery device that controls the opening and closing of the steam on-off valves so as to reduce the number of operating expanders when the value is below the value. In the Rankine cycle power recovery device according to claim 1,
Introducing exhaust heat of the internal combustion engine into the steam generator as a heat source of the steam generator;
The output part of the internal combustion engine and the power take-out part of each positive displacement expander are connected by a one-way clutch and a power transmission mechanism capable of transmitting power only from the positive displacement expander side to the internal combustion engine side. Rankine cycle power recovery device characterized by. In the Rankine cycle power recovery device according to claim 1,
Introducing exhaust heat of the internal combustion engine into the steam generator as a heat source of the steam generator;
The Rankine cycle power recovery device, wherein an output part of the internal combustion engine and a power take-off part of each positive displacement expander are connected by an electromagnetic clutch and a power transmission mechanism. In the Rankine cycle power recovery device according to claim 2 or 3,
A Rankine cycle power recovery device comprising a transmission mechanism in addition to a power transmission mechanism and an electromagnetic clutch or a one-way clutch between an output section of the internal combustion engine and a power take-out section of each positive displacement expander . In the Rankine cycle power recovery device according to claim 1,
Introducing exhaust heat of the internal combustion engine into the steam generator as a heat source of the steam generator;
An induction generator is connected to the power take-out part of each positive displacement expander,
As the common load portion, a power generator is connected to the internal combustion engine,
The Rankine cycle power recovery device, wherein each induction generator is electrically connected to the power generator. In the Rankine cycle power recovery device according to claim 5,
A water-cooled internal combustion engine is provided as the internal combustion engine,
The internal combustion engine includes a low-pressure steam generator that evaporates cooling water,
Comprising a plurality of low-pressure volumetric expanders connected in parallel to the low-pressure steam generator;
A low-pressure system steam on-off valve on the steam upstream side of the steam inlet of each low-pressure system positive displacement expander,
Low pressure system steam pressure detecting means for detecting the pressure of the steam of the cooling water generated inside the internal combustion engine,
Comprising low-pressure expander operating unit number recognizing means for recognizing the number of operating low-pressure type volume expanders,
In the control device, an appropriate steam pressure range is stored in advance for each number of operating low-pressure system expanders, and the steam pressure detected by the low-pressure system steam pressure detecting means is recognized by the low-pressure system expander operating number recognition means. Compared with the appropriate steam pressure range corresponding to the number of low-pressure system expanders operating, if the detected steam pressure exceeds the upper limit value of the appropriate steam pressure range, increase the number of low-pressure expander operations and detect A Rankine cycle power recovery device that controls each of the low-pressure system steam on / off valves so as to reduce the number of low-pressure system expanders when the steam pressure falls below a lower limit value of the appropriate steam pressure range.

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