JP2008175123A - Rankine cycle power recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize the piping for an expander lubricating oil, to reduce the total amount of the expander lubricating oil in use, and to eliminate an expander lubricating oil cooler, in a Rankine cycle power recovery device with a plurality of expanders. <P>SOLUTION: This Rankine cycle power recovery device comprises: a steam generator 3; a waste heat source such as an internal combustion engine 1; a scroll high-pressure stage expander 5; a scroll low-pressure stage expander 6; a condenser 7; and a condensate pump 8. The lubricating oil inlet 5c of the high-pressure stage expander 5 is connected to the lubricating oil outlet 6d of the low-pressure stage expander 6 through a high-pressure stage lubricating oil pump 21. The lubricating oil inlet 6c of the low-pressure stage expander 6 is connected to the lubricating oil outlet 5d of the high-pressure stage expander 5 through a low-pressure stage lubricating oil pump 22. Consequently, the expander lubricating oil is heat-exchanged with a working medium in each of the expanders 5, 6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a Rankine cycle power recovery device that is composed of a steam generator, a waste heat source, a plurality of scroll-type expanders, a condenser, a condensate pump, and the like, and is used for power generation and the like. The present invention relates to the circulation of the expander lubricating oil used in the expander and the cooling thereof.

  A scroll-type expander provided in a Rankine cycle power recovery device generally includes a fixed scroll and an orbiting scroll that are arranged opposite to each other in the axial direction so that their scroll wraps mesh with each other, and the orbiting scroll having a drive shaft. Is arranged eccentrically with respect to the fixed scroll, and the orbiting scroll is revolved by expanding the gas phase working medium in the expansion chamber formed between the scroll wraps, thereby driving the drive shaft. It is configured. The revolving orbiting scroll is slidably sandwiched between the fixed scroll and the thrust bearing, and in order to prevent output loss due to friction of the drive shaft and thrust bearing during the revolving motion of the orbiting scroll, Lubrication of the sliding part is necessary.

As a method of lubricating each sliding portion of the scroll-type expander, a conventional method (Patent Document 1) in which the working medium of the expander mixed with lubricating oil is used, and an expander lubricating oil is used separately from the working medium. Although there is a method to circulate, in terms of lubrication performance, a method using another expander lubricating oil is superior to a method in which lubrication is performed with the working medium itself, and the degree of freedom of oil path formation in the expander is also improved. Large and easy to manufacture.
JP 2000-227081 A

  In the method of circulating the expander lubricating oil different from the working medium, a lubricating oil pump and a lubricating oil cooler for cooling the lubricating oil after use are required, and the Rankine cycle having a single scroll type expander The power recovery device only needs to have one small-capacity lubricating oil pump and one small-capacity lubricating oil cooler. However, in the Rankine cycle power recovery device including a plurality of expanders, each expander is lubricated. An oil pump and a lubricating oil cooler must be provided, or a large-capacity lubricating oil pump and a lubricating oil cooler must be provided, and a large amount of lubricating oil is required.

[Object of the invention]
The present invention relates to a Rankine cycle power recovery apparatus including a plurality of scroll type expanders, and by devising a supply path of a working medium supplied to each expander and a circulation path of the expander lubricating oil, etc. An object of the present invention is to provide an economical and compact expander lubricating oil circulation structure that can save the amount of oil used and can omit a lubricating oil cooler.

  In order to solve the above-mentioned problem, the invention described in claim 1 of the present application is a plurality of scroll type driven by steam of a steam generator, a waste heat source for heating the steam generator, and steam of a working medium generated by the steam generator. Rankine, comprising: a condenser that condenses the vapor of the working medium discharged from the expander; and a condensate pump that supplies a condensate of the working medium condensed in the condenser to the steam generator. In the cycle power recovery apparatus, the expander includes: a high-pressure stage expander to which high-pressure steam is supplied; and a low-pressure stage expander to which steam at a lower pressure than the high-pressure stage expander is supplied, and the high-pressure stage The lubricant inlet of the expander is connected to the lubricant outlet of the low-pressure stage expander via a high-pressure stage lubricant pump, and the lubricant inlet of the low-pressure stage expander is connected via a low-pressure stage lubricant pump. Contact the lubricant outlet of the high-pressure stage expander. Is, the in each expansion machine, and an an expander lubricant working medium is configured to heat exchange.

  According to the above configuration, the expander lubricating oil discharged from the high-pressure stage expander is directly used for lubricating the low-pressure stage expander, and the expander lubricating oil discharged from the low-pressure stage expander is directly used for lubricating the high-pressure stage expander. Since it is used, the expander lubricating oil can be circulated through both expanders through a short circulation path, and the expander lubricating oil circulation path becomes compact.

  Moreover, in the low-pressure stage expander, the expander lubricant is cooled by heat exchange between the high-temperature expander lubricant discharged from the high-pressure stage expander and the working medium. On the other hand, since the working medium is heated, the output of the low-pressure expander is improved. That is, the heat loss and engine loss of the high-pressure stage expander can be partially recovered as the output of the low-pressure stage expander by heat exchange of the expander lubricating oil.

  The invention according to claim 2 is the Rankine cycle power recovery device according to claim 1, wherein the working medium outlet of the high-pressure stage expander is connected to the working medium inlet of the low-pressure stage expander.

  According to the above configuration, both expanders can be operated by one type of working medium, the working medium upstream side expander is a high pressure (high temperature) type expander, and the working medium downstream expander is low pressure. It can be easily set as a (low temperature) type expander.

  According to a third aspect of the present invention, in the Rankine cycle power recovery device according to the first aspect, a liquid-cooled reciprocating internal combustion engine is provided as the waste heat source, and the exhaust gas of the reciprocating internal combustion engine is used as the steam generator. A high-pressure stage steam generator that evaporates the working medium using the heat of the gas and supplies the working medium to the high-pressure stage expander; and evaporates the engine coolant of the reciprocating internal combustion engine with the heat of the reciprocating internal combustion engine. And a low-pressure stage steam generator for supplying to the low-pressure stage expander.

  According to the above configuration, the heat of the exhaust gas of the single internal combustion engine and the heat of the required cooling section in the internal combustion engine are utilized for the working medium evaporation of the high-pressure stage expander and the low-pressure stage expander, respectively. The power recovery efficiency of the internal combustion engine is improved.

  According to a fourth aspect of the present invention, in the Rankine cycle power recovery device according to the third aspect, the working medium inlet of the low-pressure stage expander is operated by the working medium outlet of the high-pressure stage expander and the operation of the low-pressure stage steam generator. Connected to the medium outlet, the working medium from the high-pressure stage expander and the working medium from the low-pressure stage steam generator are merged and supplied to the low-pressure stage expander.

  According to the above configuration, since the amount of the working medium supplied to the low-pressure stage expander can be increased, more working medium can be heated and engine lubricating oil can be cooled.

  A fifth aspect of the present invention is the Rankine cycle power recovery apparatus according to any one of the first to fourth aspects, wherein the low-pressure stage expander is provided with a heat exchange chamber, and the internal combustion engine as a waste heat source in the heat exchange chamber The engine lubricating oil and the working medium in the low-pressure stage expander are configured to exchange heat.

  According to the above configuration, in the heat exchange chamber, heat is exchanged between the engine lubricating oil that has reached a high temperature in the internal combustion engine and the working medium in the low-pressure stage expander, thereby giving heat to the working medium. On the other hand, the engine lubricating oil cooler can be miniaturized by cooling the engine lubricating oil.

  According to a sixth aspect of the present invention, in the Rankine cycle power recovery device according to the fifth aspect, an engine lubricating oil outlet of the heat exchange chamber is connected to an engine lubricating oil inlet of the internal combustion engine via an engine lubricating oil cooler. The engine lubricating oil cooler is configured to supply the condensate of the condensate pump as a cooling medium.

  According to the said structure, the temperature of the working medium supplied to a steam generator from a condensate pump can be raised, the steam generation in a steam generator can be accelerated | stimulated, and the quantity can be increased.

[First Embodiment of the Invention]
1 and 2 show a first embodiment of a Rankine cycle power recovery device according to the present invention, and the first embodiment will be described based on these drawings.

(Overview of Rankine cycle power recovery system)
FIG. 1 is a schematic piping diagram of a Rankine cycle power recovery device. The Rankine cycle power recovery device includes an internal combustion engine 1 as a waste heat source, a steam generator 3 connected to an exhaust device 2 of the internal combustion engine 1, and a scroll type. High-pressure stage expander 5, scroll-type low-pressure stage expander 6, condenser 7, condensate pump 8, and the like. Are connected to each other.

  Water (steam) is used as a working medium for driving the scroll-type expanders 5 and 6. The working medium outlet (steam outlet) 3 b of the steam generator 3 is connected to the working medium inlet (steam inlet) 5 a of the high-pressure stage expander 5 via the steam passage 11, and the working medium outlet (steam outlet) of the high-pressure stage expander 5 is connected. ) 5 b is connected to the working medium inlet (steam inlet) 6 a of the low-pressure stage expander 6 via the steam passage 62, and the working medium outlet (steam outlet) 6 b of the low-pressure stage expander 6 is connected to the condenser via the steam passage 63. 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 working medium inlet 3 a of the steam generator 3. Reference numeral 8 a is a pump for the cooling medium of the condenser 7.

  The Rankine cycle power recovery device is provided with an expander lubricating oil circulation path for supplying lubricating oil to each of the expanders 5 and 6 separately from the circulation path of the working medium, and the expander lubricating oil circulation path Are provided with a high-pressure stage lubricating oil pump 21 and a low-pressure stage lubricating oil pump 22. The discharge port 21b of the high-pressure stage lubricating oil pump 21 is connected to the lubricating oil inlet 5c of the high-pressure stage expander 5 via the oil path 31, and the suction port 21a is lubricated oil of the low-pressure stage expander 6 via the oil path 32. The lubricating oil connected to the outlet 6 d and discharged from the lubricating oil outlet 6 d of the low-pressure stage expander 6 is supplied to the lubricating oil inlet 5 c of the high-pressure stage expander 5. The discharge port 22b of the low-pressure stage lubricating oil pump 22 is connected to the lubricating oil inlet 6c of the low-pressure stage expander 6 via the oil path 33, and the suction port 22a is lubricated oil of the high-pressure stage expander 5 via the oil path 34. Connected to the outlet 5d, the lubricating oil discharged from the lubricating oil outlet 5d of the high-pressure stage expander 5 is supplied to the lubricating oil inlet 6c of the low-pressure stage expander 6.

(Structure of the high-pressure stage expander 5)
FIG. 2 shows the internal structure of each of the scroll type expanders 5 and 6. The high-pressure stage expander 5 shown on the left side includes a fixed scroll 25 and an orbiting scroll 26 that are arranged opposite to each other in the axial direction, and an annular shape. A thrust bearing 27, a crank-shaped drive shaft 28 integrally including a swing shaft portion (eccentric shaft portion) 28a, a roller bearing 37 that rotatably supports the drive shaft 28, the roller bearing 37, and the thrust And a bearing housing 38 that supports the bearing 27.

The fixed scroll 25 includes a disk-shaped base plate 25a, a spiral fixed scroll wrap 25b formed on the mirror surface of the base plate 25a, and an annular outer peripheral wall 25c formed on the outer peripheral end of the base plate 25a. It is prepared as one.

  The swing scroll 26 is integrally provided with a disk-shaped base plate 26a and a spiral swing scroll wrap 26b formed on the mirror surface of the base plate 26a.

  The two scrolls 25 and 26 are arranged opposite to each other in the axial direction so that the two scroll wraps 25b and 26b mesh with each other, and a plurality of crescent-shaped expansion chambers 29 are formed between the two scroll wraps 25b and 26b and the mirror surface. . A working medium supply body 40 is provided at the shaft core portion of the fixed scroll 25, and the working medium inlet 5 a is formed in the working medium supply body 40, and the working medium inlet 5 a is disposed through the working medium passage 41. It communicates with a partial expansion chamber 29.

  The thrust bearing 27 has an outer peripheral end sandwiched between an outward flange portion of the fixed scroll 25 and an outward flange portion of the bearing housing 38, and an annular land portion 27 a is formed at the inner peripheral end portion of the thrust bearing 27. The back surface of the swing scroll 26 is slidably supported by the land portion 27a.

  A boss portion 26 c is integrally formed at the center of the back surface of the orbiting scroll 26, and the drive shaft 28 is oscillated on the inner peripheral surface of the boss portion 26 c via a needle bearing (or bearing metal) 43. The shaft portion 28a is rotatably fitted. The axis of the oscillating shaft 28 a is displaced from the axis of the drive shaft 28 by a certain amount, and the oscillating shaft 28 a revolves around the drive axis together with the oscillating scroll 26, thereby rotating the drive shaft 28. It is supposed to be. Further, a ring-shaped Oldham coupling 45 is interposed between the back surface of the swing scroll 26 and the bearing housing 38 in order to prevent the swing scroll 26 from rotating when the swing scroll 26 revolves. ing.

  A lubricating oil passage 50 extending in the axial length direction is formed in the shaft core portion of the drive shaft 28, and one end of the lubricating oil passage 50 serves as the lubricating oil inlet 5c. The other end of the lubricating oil passage 50 opens into the boss portion 26c of the orbiting scroll 26 through the restrictor 51, and the lubricating oil is injected toward the center portion of the base plate 26a of the orbiting scroll 26. Yes. A lubricating oil reservoir 53 is formed at the lower end portion of the space formed between the back surface of the base plate 26a of the orbiting scroll 26 and the front surface of the bearing housing 31, and the lubricating oil reservoir 53 serves as the lubricating oil outlet. The suction port 22 a of the low-pressure stage lubricating oil pump 22 is communicated with the oil passage 34 through the oil passage 34.

(Structure of low-pressure stage expander 6)
In FIG. 2, the basic structure of the low-pressure stage expander 6 is substantially the same as that of the high-pressure stage expander 5 except for the lubricating oil path, and parts having the same names that perform the same functions are denoted by the same reference numerals. It is.

  In the low-pressure stage expander 6 shown on the right side of FIG. 2, a lubricating oil passage 50 extending in the axial length direction is formed in the shaft core portion of the drive shaft 28, and one end of the lubricating oil passage 50 is at the lubricating oil inlet 6c. It has become. The other end of the lubricating oil passage 50 opens into the boss portion 26c of the orbiting scroll 26 through the restrictor 51 so that the lubricating oil is injected toward the central portion of the base plate 26a of the orbiting scroll 26. . In the present embodiment, in addition to the lubricating oil path, a lubricating oil inlet 6 c is also formed on the outer peripheral wall of the bearing housing 38, and is formed in the land portion 27 a of the thrust bearing 27 via the lubricating oil inlet 6 c and the oil passage 56. The annular oil chamber 58 is communicated with.

(Working medium flow)
(1) In FIG. 1, a passage 61 through which a liquid-phase working medium (condensate or the like) passes is indicated by a broken line, and passages 11, 62, 63 through which a gas-phase working medium (steam) passes are indicated by a solid line. . The high-temperature and high-pressure steam (vapor-phase working medium) generated by the steam generator 3 is supplied to the working medium inlet 5 a at the center of the high-pressure stage expander 5.

(2) In FIG. 2, the high-temperature and high-pressure steam press-fitted into the expansion chamber 29 near the center from the working medium inlet 5 a at the center of the high-pressure stage expander 5 expands in the expansion chamber 29, thereby The dynamic scroll 26 is revolved, thereby rotating the drive shaft 28 and generating electric power.

(3) The steam expanded in the high-pressure stage expander 5 is discharged from the working medium outlet 5b at the outer peripheral end, and is supplied to the working medium inlet 6a of the low-pressure stage expander 6 through the passage 62 in FIG. In the low pressure stage expander 6, it expand | swells similarly to the said high pressure stage expander 5, drives the generator 9, and is discharged | emitted from the working-medium exit 6b.

(4) The steam discharged from the low-pressure stage expander 6 also includes condensed water, which is supplied to the condenser 7 through the passage 63 and condensed as a whole.

(5) The working medium condensed in the condenser 7 is sucked into the condensate pump 8 through the passage 61, supplied again to the steam generator 3, and evaporated by the heat of the exhaust gas of the internal combustion engine 1.

(Expansion machine lubricant flow)
(1) In FIG. 1, the expander lubricating oil circulation path is indicated by a thick solid line. The expander lubricating oil pressurized in the high-pressure stage lubricating oil pump 21 and discharged from the discharge port 21b enters the high-pressure stage expander 5 from the lubricating oil inlet 5c of the high-pressure stage expander 5, and moves each sliding portion. While lubricating, it exchanges heat with the working medium in the high-pressure stage expander 5, rises in temperature, is discharged from the lubricating oil outlet 5 d, and is sucked into the low-pressure stage lubricating oil pump 22 through the oil passage 34.

(2) The high-temperature expander lubricating oil pressurized in the low-pressure stage lubricant pump 22 and discharged from the discharge port 22 b enters the low-pressure stage expander 6 from the lubricant inlet 6 c of the low-pressure stage expander 6. Each sliding portion is lubricated and heat exchanged with the working medium in the low-pressure stage expander 6 is cooled, discharged from the lubricating oil outlet 6d, and sucked into the high-pressure stage lubricating oil pump 21.

(3) The flow and action of the expander lubricating oil in each of the expanders 5 and 6 will be described in detail with reference to FIG. In the high-pressure stage expander 5 shown on the left side of FIG. 2, the expander lubricating oil supplied to the lubricating oil passage 50 in the drive shaft 28 is sprayed from the throttle 51 to the back surface of the center portion of the swing scroll 26. Thus, the steam (working medium) in the expansion chamber 29 at the center is impingement cooled, while the temperature of the expander lubricating oil rises due to heat exchange. The expander lubricating oil whose temperature has risen lubricates the bearing 43 in the boss portion 26 c and moves radially outward, lubricates the land portion 27 a of the thrust bearing 27, and then accumulates in the (high temperature) lubricating oil reservoir 53. The oil is discharged from the lubricating oil outlet 5d and sucked into the low-pressure stage lubricating oil pump 22.

(4) In the low-pressure stage expander 6 shown on the right side of FIG. 2, the high-temperature expander lubricating oil pressurized by the low-pressure stage lubricating oil pump 22 is supplied from the lubricating oil inlet 6 c formed on the drive shaft 28. At the same time, it is also supplied from a lubricating oil inlet 6 c formed on the outer peripheral wall of the fixed scroll 25. The high-temperature expander lubricating oil supplied to the lubricating oil passage 50 in the drive shaft 28 is sprayed from the throttle 51 to the back surface of the center portion of the orbiting scroll 26, and steam (working medium) in the expansion chamber 29 in the center portion. Heat. This increases the output of the low-pressure stage expander 6, while the expander lubricating oil is cooled. In heat exchange (heating and cooling) by impingement, a large heat transfer rate can be obtained even with a small amount of lubricating oil, and efficient heat transfer can be achieved. The expander lubricant supplied from the lubricant inlet 6c at the outer peripheral end of the fixed scroll 25 is supplied to the annular oil chamber 58 of the thrust bearing 27, thereby lubricating the land 27a and the low-pressure stage expander. The working medium near the outer peripheral end of 6 is heated, and the output of the low-pressure stage expander 6 is increased. Lubricating oil that has lubricated the bearing 43 of the low-pressure stage expander 6 and the land portion 27a of the thrust bearing 27 is accumulated in the (low temperature) lubricating oil reservoir 53 and sucked into the high-pressure stage lubricating oil pump 21 through the lubricating oil outlet 6d. .

(5) As described above, the heat loss and mechanical loss of the high-pressure stage expander 5 and the mechanical loss of the low-pressure stage expander 6 are partially reduced through the heat exchange between the expander lubricating oil and the working medium. Since it is used for heating the working medium in the machine 6, the loss can be recovered as a part of the output. By the way, Rankine cycle efficiency is set to 20%, and 2% can be recovered from 10% heat input with respect to the ideal work of the expander, and the expander efficiency is improved by about 2 points. Of course, an external lubricating oil cooling mechanism can also be omitted.

[Second Embodiment of the Invention]
FIG. 3 shows a second embodiment of the present invention, in which the high-pressure stage expander 5 and the low-pressure stage expander 6 are arranged on the same rotating shaft (drive shaft) 70, and both expanders 5, 6 are arranged. It has a structure in which a common generator 9 is arranged in the central part. A high-pressure stage lubricating oil pump 21 and a high-pressure side lubricating oil reservoir 53 are disposed between the high-pressure stage expander 5 and the generator 9, and the low-pressure stage lubricating oil is disposed between the low-pressure stage expander 6 and the generator 9. A pump 22 and a low-pressure side lubricating oil reservoir 53 are arranged. The other structure is the same as that of the first embodiment, and details are omitted.

  According to this embodiment, the lubricating oil in each of the lubricating oil pumps 21 and 22 and the lubricating oil reservoirs 53 and 53 serves as a heat cutoff buffer, cuts off heat transfer from each of the expanders 5 and 6 to the generator 9, and generates power. The temperature rise of the machine 9 can be prevented. Of course, in the low-pressure stage expander 6, as in the first embodiment, part of the mechanical loss and heat loss can be recovered as output by heat exchange of the lubricating oil.

[Third Embodiment of the Invention]
4 to 6 show a third embodiment of the present invention. In FIG. 4, a reciprocating internal combustion engine is provided as the internal combustion engine 1, and the working medium of the low-pressure stage expander 6 is the reciprocating internal combustion engine 1. Engine coolant is used. Furthermore, a heat exchange chamber 81 is added to the low-pressure stage expander 6, and heat exchange between the high-temperature engine lubricating oil discharged from the internal combustion engine 1 and the working medium in the low-pressure stage expander 6 is performed in the heat exchange chamber 81. To do.

  explain in detail. In FIG. 4, as a working medium circulation path of the low-pressure stage expander 6, an evaporation tank (low-pressure stage steam generator) 80 is provided on the upper side of the required cooling section (cylinder, cylinder head, etc.) of the internal combustion engine 1, The vapor outlet (low pressure stage working medium outlet) 80 b of the evaporation tank 80 is connected to the working medium inlet 6 a of the low pressure stage expander 6. The working medium outlet 6 b of the low-pressure stage expander 6 joins the passage 62 connected to the working medium outlet 5 b of the high-pressure stage expander 5 and is connected to the condenser 7. The outlet of the condenser 7 is connected to the first condensate pump 8 via a passage 61. The passage 71 connected to the outlet of the first condensate pump 8 is connected to the coolant passage in the internal combustion engine 1 via the branch passage 71a and to the second condensate pump 72. . The passage 74 connected to the outlet of the second condensate pump 72 is connected to the working medium inlet 3a of the steam generator 3 via an engine lubricating oil cooler 73 described later.

  The lubricating oil inlet 81 a of the heat exchange chamber 81 added to the low-pressure stage expander 6 is connected to the lubricating oil outlet 1 b of the internal combustion engine 1, and the lubricating oil outlet 81 b of the heat exchange chamber 81 is connected via the lubricating oil cooler 73. The lubricating oil inlet 1a of the internal combustion engine 1 is connected. The engine lubricating oil cooler 73 is supplied with the liquid working medium from the condensate pump 72 as described above, and finally the engine lubricating oil is cooled by this working medium and returned to the internal combustion engine 1. It is like that.

  That is, in the heat exchange chamber 81 of the low-pressure stage expander 6, the engine lubricating oil that has reached a high temperature in the internal combustion engine 1 and the working medium in the low-pressure stage expander 6 are subjected to heat exchange to obtain a working medium. Heat is applied and the output of the low-pressure stage expander 6 is improved, while the engine lubricating oil is cooled, whereby the engine lubricating oil cooler 73 can be miniaturized. Further, by supplying the engine lubricating oil cooler 73 with the working medium from the second condensate pump 72, the temperature of the working medium can be raised and the steam generation in the steam generator 3 can be promoted.

  5 and 6 are specific examples of the heat exchange chamber 81 of the low-pressure stage expander 6, and as shown in FIG. 5, a spiral heat exchange chamber 81 is formed on the back surface of the fixed housing 25 of the low-pressure stage expander 6. And is covered with a cover 83. As shown in FIG. 6, an engine lubricating oil inlet 81a is formed at the outer peripheral end of the spiral heat exchange chamber 81, and an engine lubricating oil outlet 81b is formed at the center.

  The high-temperature (90 ° C. to 100 ° C.) engine lubricating oil discharged from the lubricating oil outlet 1b of the internal combustion engine 1 in FIG. 4 is sent to the heat exchange chamber 81 via the oil passage 84. In FIG. It enters into the heat exchange chamber 81 from the lubricating oil inlet 81a at the outer peripheral end of 81, and flows to the center. The hot engine lubricating oil exchanges heat with the working medium in the expansion chamber 29 of the low-pressure stage expander 6 shown in FIG. 5 while flowing in the heat exchange chamber 81. That is, the engine lubricating oil is cooled and the working medium in the expansion chamber 29 is heated.

  As described above, when high-temperature engine lubricating oil is introduced from the outer peripheral end portion of the heat exchange chamber 81, the working medium of the heat exchange partner is introduced into the expansion chamber 29 from the central portion, so the temperature of the working medium The temperature difference between the working medium and the engine lubricating oil becomes the largest at the outer peripheral end where the temperature drops most, and heat can be exchanged efficiently.

  The internal combustion engine 1 is cooled at about 90 ° C., and the energy that escapes to the engine coolant is about 30% of the fuel energy. On the other hand, the amount of heat that escapes to the engine lubricating oil in the internal combustion engine 1 is 5 to 10% of the fuel energy, and the temperature at the time of discharge is around 90 ° C. In other words, when considered as a heat source, the engine lubricating oil is at the same temperature level as the working medium for the low-pressure stage expander 6, and is quantitatively about 1/6 to 1/3 of the amount of heat that escapes to the cooling water. Since the working medium of the low-pressure stage expander 6 of the Rankine cycle power recovery apparatus drops in temperature from about 90 ° C. to near room temperature, the working medium of the internal combustion engine 1 is heated for heating the working medium during expansion of the low-pressure stage expander 6. Engine lubricating oil can be used sufficiently.

In this embodiment, by passing the working medium from the condensate pump 72 to the coolant side of the engine lubricating oil cooler 73, the energy escaped to the engine lubricating oil can be recovered as the working medium energy, and the power The amount recovered can be increased, and the amount that cannot be cooled in the heat exchange chamber 81 can be sufficiently cooled.

[Fourth Embodiment of the Invention]
FIG. 7 shows a fourth embodiment of the present invention. In addition to the third embodiment, the working medium discharged from the working medium outlet 5 b of the high-pressure stage expander 5 is used as the evaporation tank 80 of the internal combustion engine 1. This is a structure in which the working medium supplied from the steam outlet (low pressure stage working medium outlet) 80 b is joined to the working medium inlet 6 a of the low pressure stage expander 6. Other structures are the same as those of the third embodiment, and the same components are denoted by the same reference numerals.

  According to the fourth embodiment, the amount of the working medium supplied to the low-pressure stage expander 6 is increased as compared with the third embodiment of FIG. The lubricating oil can be cooled.

1 is an overall piping diagram of a first embodiment of a Rankine cycle power recovery device according to the present invention. It is sectional drawing of each expander of the Rankine cycle power recovery device of FIG. It is the whole piping schematic of the 2nd Embodiment of this invention. It is general piping schematic of the 3rd Embodiment of this invention. It is sectional drawing of each expander of 3rd Embodiment. It is a rear view of the heat exchange chamber of 3rd Embodiment. It is the whole piping schematic of the 4th Embodiment of this invention.

Explanation of symbols

1 Reciprocating internal combustion engine (waste heat source)
DESCRIPTION OF SYMBOLS 2 Exhaust device 3 Steam generator 5 Scroll type high-pressure stage expander 5a Working medium inlet 5b Working medium outlet 5c Expander lubricating oil inlet 5d Expander lubricating oil outlet 6 Scroll type low-pressure stage expander 6a Working medium inlet 6b Working medium Outlet 6c Expander lubricant inlet 6d Expander lubricant outlet 7 Condenser 8 Condensate pump 9 Generator 21 High-pressure stage lubricant pump 21a Suction port 21b Discharge port 22 Low-pressure stage lubricant pump 22a Suction port 22b Discharge port 29 Expansion chamber 73 Engine lubricating oil cooler 80 Evaporation tank (example of steam generator for low-pressure stage)
81 Heat exchange room

Claims (6)

A steam generator, a waste heat source for heating the steam generator, a plurality of scroll-type expanders driven by the steam of the working medium generated by the steam generator, and the steam of the working medium discharged from the expander In the Rankine cycle power recovery device, comprising: a condenser for condensing the gas and a condensate pump for supplying a condensate of the working medium condensed in the condenser to the steam generator;
The expander includes a high-pressure stage expander to which high-pressure steam is supplied, and a low-pressure stage expander to which steam at a lower pressure than the high-pressure stage expander is supplied,
The lubricating oil inlet of the high-pressure stage expander is connected to the lubricating oil outlet of the low-pressure stage expander via a high-pressure stage lubricating oil pump, and the lubricating oil inlet of the low-pressure stage expander is a low-pressure stage lubricating oil pump Is connected to the lubricating oil outlet of the high-pressure stage expander, and is configured to exchange heat between the expander lubricating oil and the working medium in each expander. apparatus. In the Rankine cycle power recovery device according to claim 1,
The Rankine cycle power recovery device, wherein the working medium outlet of the high-pressure stage expander is connected to the working medium inlet of the low-pressure stage expander. In the Rankine cycle power recovery device according to claim 1,
As the waste heat source, a liquid-cooled reciprocating internal combustion engine is provided,
As the steam generator, a high-pressure stage steam generator that evaporates a working medium using heat of exhaust gas of the reciprocating internal combustion engine and supplies it to the high-pressure stage expander; and engine cooling of the reciprocating internal combustion engine A Rankine cycle power recovery apparatus comprising: a low-pressure stage steam generator configured to evaporate liquid with heat of the reciprocating internal combustion engine and supply the liquid to the low-pressure stage expander. In the Rankine cycle power recovery device according to claim 3,
The working medium inlet of the low-pressure stage expander is connected to the working medium outlet of the high-pressure stage expander and the working medium outlet of the low-pressure stage steam generator, and the working medium from the high-pressure stage expander and the low-pressure stage Rankine cycle power recovery device that combines working medium from a steam generator and supplies it to a low-pressure stage expander. In the Rankine cycle power recovery device according to any one of claims 1 to 4,
A heat exchange chamber is provided in the low-pressure stage expander,
A Rankine cycle power recovery device configured to exchange heat between engine lubricating oil of an internal combustion engine as a waste heat source and a working medium in a low-pressure stage expander in the heat exchange chamber. In the Rankine cycle power recovery device according to claim 5,
The engine lubricating oil outlet of the heat exchange chamber is connected to the engine lubricating oil inlet of the internal combustion engine via an engine lubricating oil cooler,
A Rankine cycle power recovery device configured to supply a condensate of the condensate pump as a cooling medium to the engine lubricating oil cooler.

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