JP2006316704A - Exhaust heat recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust heat recovery device of an internal combustion engine efficiently recovering exhaust heat and power from exhaust gas and cooling liquid. <P>SOLUTION: The exhaust heat recovery device comprises a steam generating tank 10 communicating with a cooling liquid chamber 6 of the internal combustion engine 1, which obtains low pressure steam by maintaining pressure in the tank at saturation pressure corresponding to medium temperature necessary for cooling, a first expander 21 for low pressure obtaining power by expanding the low pressure steam supplied from the steam generating tank 10, a high pressure generator 15 for obtaining steam of higher pressure than the steam of the steam generating tank 10 by heat-exchanging part of the cooling liquid with the exhaust gas of the internal combustion engine, a second expander 22 for obtaining power independently from the first expander by expanding the high pressure steam supplied from the high pressure steam generator 15, and a condenser 27 for liquefying the expanded steam discharged from the respective expanders 21, 22. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust heat recovery apparatus using a Rankine cycle that uses exhaust heat of an internal combustion engine to obtain power of a load device such as a generator by an expander.

In large-sized gas turbine power generators having an output number of MW or more, combined power generation that generates steam from the exhaust heat and obtains power from the steam turbine is often employed, and the power generation efficiency exceeds 50%. However, combined power generation has not been put into practical use for low-power internal combustion engines for the following reasons. That is,
(1) A low-power steam turbine is inefficient.
(2) A small output internal combustion engine is mainly a reciprocating engine because of its efficiency. In addition to the exhaust gas, a lot of heat escapes to the cooling water. The amount of heat recovered from the exhaust gas does not increase as much as the turbine.
(3) System cost increases.

  In contrast to devices that recover power only from exhaust gas exhaust heat, such as the large gas turbine power generators described above, in small power generators and the like, the exhaust gas of the internal combustion engine and the coolant after cooling the engine Devices for recovering power from exhaust heat have also been developed.

  FIG. 16 is an example of a conventional exhaust heat recovery device that recovers exhaust gas of an internal combustion engine and exhaust heat of coolant after engine cooling is used as power for power generation (see Patent Document 1).

  The exhaust heat recovery apparatus of FIG. 16 will be briefly described. The first generator 202 connected to the output shaft of the gas engine 201, and the second power generation driven using the heat of the exhaust gas and the heat of the coolant. A machine 203 is provided. The second generator 203 includes a first steam turbine 211 and a second steam turbine 212 attached to a turbine shaft 205 connected to the generator shaft 204, and the first steam turbine is provided in the middle of an exhaust pipe 213. A high temperature side power generation unit 215 that drives 211, and a low temperature side power generation unit 216 that drives the second steam turbine 212 downstream of the high temperature side power generation unit 215.

  The first power generation unit 215 includes an exhaust heat boiler 217, a superheater 218, a condenser 219, a pump 220, and the like, and these form a water circulation circuit with one water jacket 222 of the engine. The second power generation unit 216 includes a waste heat boiler 230, a condenser 231, a pump 232, and a heat exchanger 233, and constitutes a secondary circulation circuit that circulates chlorofluorocarbon or alternative chlorofluorocarbon between them. In addition, a primary water circulation circuit that circulates the cooling water between the heat exchanger 233 and the other water jacket 234 of the engine is also configured.

According to the exhaust heat recovery apparatus of FIG. 16, the cooling water discharged from one water jacket 222 exchanges heat with the exhaust gas in the exhaust pipe 213 in the exhaust heat boiler 217 and the superheater 218, thereby generating high-pressure steam. The high-pressure steam is supplied to the first steam turbine 211, and the turbine shaft 205 is rotated. Further, the cooling water discharged from the other water jacket 234 is preheated in the heat exchanger 233 to the secondary side chlorofluorocarbon or alternative chlorofluorocarbon, and the preheated secondary medium is supplied to the exhaust heat boiler 230. The low-pressure steam is obtained, the low-pressure steam is supplied to the second steam turbine 212, and the turbine shaft 205 is rotated.
JP 2002-161716 A

The exhaust heat recovery apparatus shown in FIG. 16 has the following problems.
(1) In the second power generation unit 216 on the low pressure side, two types of heat transfer media such as engine cooling water and alternative chlorofluorocarbon are used, and heat is exchanged between both media via the heat transfer surface. In addition, since the new heat exchanger 233 is provided, the cost is increased and the maintenance of the medium is troublesome.

(2) Heat exchange between the engine coolant and the secondary medium is performed by the heat exchanger 233, and the secondary medium is preheated. Thus, when the heat exchanger 233 is interposed, the heat at the time of heat exchange Loss is large and it is difficult to effectively utilize the preheating.

  The reason why it is difficult to effectively use the preheating will be briefly described. FIG. 15 is a temperature-exchange heat quantity diagram showing a general heat exchange between a heat receiving fluid such as cooling water having a phase change and a heating fluid such as exhaust gas, and a solid line X1 is an exhaust gas. The change in temperature and the broken line X2 indicated by a two-dot chain line indicate changes in the cooling water. Cooling water changes into three phases, liquid phase, mixed phase, and gas phase, but when cooling water is evaporating (mixed phase), it is in a state of receiving so-called latent heat. Since the gas gives heat to the cooling water, the temperature of the exhaust gas decreases. Therefore, the pinch point PP is formed near the boiling point during heat exchange. The amount of heat that can be given to the steam is exhaust gas flow rate × specific heat × (exhaust gas inlet temperature−exhaust gas temperature at the pinch point).

  When the cooling water is preheated for heat exchange as shown in FIG. 15 and then heat exchange with the exhaust gas, the heat exchange as shown in FIG. 17 is performed. That is, in FIG. 17, for example, the cooling water is heated to 90 ° C. with another heat source of about 90 ° C. (point A 1), and then is made 100 ° C. with exhaust gas (point A 2). Considering the process in which the steam temperature rises from (Point A3) to superheated steam, the amount of steam that can be produced is determined by the exhaust gas inlet temperature and amount higher than the pinch point PP temperature (T3). Become. Therefore, even if the cooling water is preheated, the amount of heat recovered by the preheating causes the exhaust gas to be taken out of the system, and the exhaust gas outlet temperature T2 is higher than the outlet temperature T1 in the case of FIG. As a result, an increase in the total recovered heat cannot be expected.

[Object of invention]
The present invention is to make it possible to use exhaust heat effectively for power generation and the like by making efficient use of exhaust heat of exhaust gas and exhaust heat of coolant in an internal combustion engine.

In order to solve the above-mentioned problem, an exhaust heat recovery apparatus according to the invention of claim 1 of the present application,
A steam generation tank that communicates with a coolant chamber of an internal combustion engine, and maintains a pressure in the tank at a saturation pressure corresponding to a medium temperature necessary for cooling, thereby reducing a low pressure from the coolant used for engine cooling. A steam generation tank for obtaining steam;
A first low-pressure expander that obtains power by expanding low-pressure steam supplied from the steam generation tank;
A high-pressure steam generator that takes in a part of the coolant before use for engine cooling and exchanges heat with the exhaust gas of the internal combustion engine to obtain steam at a pressure higher than that of the steam generating tank;
A second high-pressure expander that obtains power independently of the first expander by expanding the high-pressure steam supplied from the high-pressure steam generator;
And a condenser that liquefies the expanded steam discharged from each expander and supplies the liquefied coolant to the coolant chamber of the internal combustion engine and the high-pressure steam generator.

  According to the above configuration, the exhaust heat of the exhaust gas of the internal combustion engine and the exhaust heat of the coolant can be efficiently recovered and used efficiently as power for a load device such as a generator. In addition, as the medium used in the Rankine cycle, a secondary medium such as an alternative chlorofluorocarbon is not used as in the past, and only the coolant of the internal combustion engine is used, so a heat exchanger between the coolant and the secondary medium is required. The cost can be reduced and heat loss in the heat exchanger can be eliminated.

  The cooling water recovers the heat of the internal combustion engine as sensible heat, and also recovers the cooling water as latent heat by adjusting the pressure to generate saturated steam, which is a first independent of the second expander. Since the power is recovered by supplying it to the low-pressure expander, the power can be recovered more than the conventional preheating method.

  According to a second aspect of the present invention, in the exhaust heat recovery apparatus according to the first aspect, the cooling liquid chamber is divided into a high temperature side cooling liquid chamber portion and a low temperature side cooling liquid chamber portion having different cooling liquid rising temperatures, The steam generation tank is partitioned into a first steam generation tank communicating with the low temperature side coolant chamber part and a second steam generation tank communicating with the high temperature side coolant chamber part, and the first, first Of the two steam generation tanks, a second steam generation tank that generates steam at a relatively high pressure is connected to a steam inlet of the first expander to generate steam at a relatively low pressure. This steam generation tank is connected to a part of the first expander in the middle of expansion downstream from the steam inlet.

  According to the above configuration, since additional steam is introduced during the expansion of the first expander, compared with the configuration in which the steam is supplied only from the steam inlet of the first expander, the expansion chamber is in the process until the end of expansion. The pressure can be kept high and much power can be recovered.

  According to a third aspect of the present invention, in the exhaust heat recovery apparatus according to the first or second aspect, the first expander and the second expander are connected to independent generators.

  According to the said structure, the generator of the capacity | capacitance according to each electric power generation amount can be provided, and the electric power of each generator can also be utilized for another apparatus according to each electric power generation amount.

  The invention according to claim 4 is the exhaust heat recovery apparatus according to claim 1 or 2, wherein the first expander is connected to one end of the power generation shaft of one generator and the second expander is connected to the other end. is doing.

  According to the above configuration, when the exhaust heat of the internal combustion engine is recovered as electric energy by the generator, it is possible to reduce the size and cost of the exhaust heat recovery device.

  According to a fifth aspect of the present invention, in the exhaust heat recovery apparatus according to the first aspect, the pressure at the steam outlet of the second expander for high pressure is maintained at substantially the same pressure as the internal pressure of the steam generation tank, and the steam outlet is Instead of connecting to the condenser, the steam is supplied to the steam inlet of the first expander for low pressure.

  According to the above configuration, the expansion ratio of the second expander for high pressure can be reduced. For example, if the second expander is a steam turbine type (speed type) expander, the number of turbine stages can be reduced. If it is a scroll type (volume type) expander, the number of expansion chambers can be reduced. In any case, the second expander can be reduced in size and the cost can be reduced. be able to.

The exhaust heat recovery apparatus according to the invention of claim 6 is
Partitioning the coolant chamber of the internal combustion engine into a high temperature side coolant chamber portion and a low temperature side coolant chamber portion having different coolant rise temperatures;
A first steam generation tank communicating with the cooling chamber portion on the low temperature side, and maintaining the pressure in the tank at a saturation pressure corresponding to the medium temperature required for cooling, cooling after use for engine cooling A first steam generation tank for obtaining steam from the liquid;
A second steam generation tank communicating with the cooling chamber portion on the high temperature side, wherein the pressure in the tank is made higher than the pressure in the first steam generation tank; A second steam generation tank for obtaining steam having a pressure higher than that of the first steam generation tank from the coolant;
A high-pressure steam generator that takes a part of the coolant before use for engine cooling and exchanges heat with the exhaust gas of the internal combustion engine to obtain steam at a pressure higher than that of each steam generation tank;
A steam inlet for taking in the steam of the high-pressure steam generator, an intermediate steam inlet for taking in the steam of the second steam generation tank from the middle of expansion, and the first steam generation tank in the middle of expansion downstream from the intermediate steam inlet An expander having a downstream steam inlet for taking in
And a condenser that liquefies the expanded steam discharged from the expander and supplies the liquefied coolant to the coolant chamber of the internal combustion engine and the high-pressure steam generator.

  According to the above configuration, a relatively high pressure steam and a relatively low pressure steam are sequentially added in two stages from the second steam generation tank and the first steam generation tank 11 during expansion in the expander. Since it is introduced, the pressure in the expansion chamber can be kept higher until the end of the expansion, and much power can be recovered, even when compared with the structure in which the low-pressure steam is added only once during the expansion.

  The invention according to claim 7 is the exhaust heat recovery apparatus according to any one of claims 1 to 6, wherein the expander is a speed type expander.

  According to the said structure, an expander becomes small compared with a positive displacement type expander, and is suitable for a high output use.

  The invention according to claim 8 is the exhaust heat recovery apparatus according to any one of claims 1 to 6, wherein the expander is a positive displacement expander.

  According to the said structure, compared with the case where a steam turbine (speed type | mold expander) is used, the generation | occurrence | production decline and the generation | occurrence | production of erosion by drag increase can be suppressed. That is, when expanding the saturated steam in the expander, from dry steam to wet steam, when the wetness increases, in the case of a speed type expander such as a steam turbine, drag increases and efficiency decreases, In addition, erosion may occur. On the other hand, in the case of a positive displacement expander such as the scroll type, the partially liquefied medium serves as a seal for the sealed chamber, and on the contrary, the efficiency is improved, and the medium is oscillated compared to the speed type. Since scrolling and other rotations are slow, there is no worry of erosion.

  The invention according to claim 9 is the exhaust heat recovery apparatus according to any one of claims 1 to 8, wherein the high-pressure steam generator is a saturated boiler.

  According to the above configuration, for the same reason as described in the paragraph “0029”, the superheater may not be used, and the wetness of the steam may be increased at the expander outlet. That is, the cost required for the superheater can be reduced. Incidentally, in the case of using a speed expander such as a steam turbine, a superheater that further superheats the saturated steam is necessary to prevent the wetness of the steam after expansion from increasing.

  As described above, according to the present invention, the heat of the coolant together with the heat of the exhaust gas of the internal combustion engine can be efficiently recovered and used efficiently as power for a load device such as a generator. As a medium to be used, it is possible to use only the cooling liquid of the internal combustion engine and eliminate the heat exchanger between the cooling liquid and the secondary medium without using a secondary medium such as an alternative chlorofluorocarbon as in the past. In addition, the cost can be reduced and heat loss in the heat exchanger can be eliminated.

[First Embodiment]
FIG. 1 shows a first embodiment of the present invention, which is an exhaust heat recovery apparatus that generates power by Rankine cycle using heat of exhaust gas and heat of a coolant of an internal combustion engine 1. As the internal combustion engine 1, a reciprocating internal combustion engine such as an evaporative cooling horizontal water cooling engine for agricultural machinery is used.

  A coolant chamber (water jacket) 6 formed in the internal combustion engine 1 surrounds the heat generating portions such as the cylinder liner 2, the cylinder head 3, and the exhaust port 14a. The coolant chamber 6 contains coolant as a coolant. Cooling water is injected, a coolant inlet 6a is provided at the lower end of the coolant chamber 6, and a coolant outlet 6b is provided at the upper end.

  The exhaust heat recovery apparatus includes a steam generation tank (so-called hopper tank) 10 that is provided at an upper end coolant outlet 6b of the coolant chamber 6, a first expander 21 for low pressure, a first expander 21 for high pressure, A second expander 22; a high-pressure steam generator 15 that generates steam by heat exchange between exhaust gas and cooling water; a condenser (condenser) 27; a low-pressure pump 30; and a high-pressure pump 31. The first and second expanders 21 and 22 constituting the Rankine cycle are coupled to the first and second generators 24 and 25 as load devices, respectively.

  In the steam generation tank 10 communicating with the upper end coolant outlet 6b of the coolant chamber 6, the tank internal pressure is set to a saturation pressure corresponding to the required cooling temperature of the coolant, and the pressure in the coolant chamber 6 is also saturated. It is designed to keep the pressure. As a result, the cooling water that has received heat in the coolant chamber 6 and has been heated is evaporated at low temperature and low pressure (saturation temperature and saturation pressure) to obtain low-pressure saturated steam.

  The high-pressure steam generator 15 is disposed in the middle of the exhaust pipe 14 of the internal combustion engine 1, and an evaporation conduit 16 is disposed in the high-pressure steam generator 15. The cooling water inlet 16a of the evaporation conduit 16 is provided at the downstream end of the exhaust gas, and the steam outlet 16b is provided at the upstream end of the exhaust gas. The flow of the cooling water (and steam) inside is generally configured to be a counterflow. The cooling water inlet 16 a of the evaporation conduit 16 is connected to the condensate outlet 28 b of the condenser 27 through the cooling water pipe 40, the high pressure pump 31, the cooling water pipe 41 and the low pressure pump 30. On the other hand, the steam outlet 16 b of the evaporation conduit 16 is connected to the steam inlet 22 a of the second expander 22 via the steam pipe 42.

  The second expander 22 for high pressure can be either a speed type such as a turbine type or a volume type such as a scroll type. The steam outlet 22 b of the second expander 22 is connected to the steam inlet 28 a of the condenser 27 through a steam pipe 43.

  The first expander 21 for low pressure can be either a speed type such as a turbine type or a volume type such as a scroll type. The steam inlet 21a of the first expander 21 is connected to the steam outlet 10b of the steam generation tank 10 via a steam pipe 45, and the steam outlet 21b of the first expander 21 is connected to the second expander 22. Are connected to a steam inlet 28 a of the condenser 27.

  The condenser 27 is supplied with a secondary cooling water of a discharge system from a water supply or a pool or the like by a discharge system cooling water pump 35, and a liquefying conduit 28 is arranged, and a steam inlet 28 a of the liquefying conduit 28 has a steam inlet 28 a. The condensate outlet 28b of the liquefaction conduit 28 is provided at the upstream end of the discharge water secondary cooling water, and is provided at the upstream end of the discharge water secondary cooling water. The secondary cooling water and the steam from the expanders 21 and 22 are configured to face each other.

  The steam inlet 28 a of the liquefying conduit 28 is connected to the steam outlets 21 b and 22 b of the expanders 21 and 22 as described above, and the condensate outlet 28 b is connected to the cooling liquid chamber via the low-pressure pump 30 and the cooling water pipe 41. 6 is connected to the cooling water inlet 6a and partly branched to be connected to the cooling water inlet 16a of the high-pressure steam generator 15 via the high-pressure pump 31 as described above.

(Recovery of heat and power from exhaust gas by high-pressure steam generator and second expander)
A part of the cooling water in the cooling water pipe 41 before being used for engine cooling (before the temperature rise) is supplied by the high pressure pump 31 to the steam inlet 16a of the high pressure steam generator 15 through the cooling water pipe 40 at a high pressure. Then, it flows in the evaporation conduit 16 opposite to the flow of the exhaust gas, and evaporates by exchanging heat with the exhaust gas. The high-pressure steam (saturated steam) obtained by this evaporation is led into the second high-pressure expander 22 from the steam outlet 16b via the steam pipe 42, and is expanded to output the second expander 22. The shaft is rotated, and thereby the second generator 25 is driven to generate power. That is, the exhaust heat of the exhaust gas is recovered as electric power. The steam expanded in the second expander 22 is discharged from the steam outlet 22b, supplied into the liquefying conduit 28 of the condenser 27 via the steam pipe 43, cooled with secondary cooling water, and liquefied. After liquefaction, the low pressure pump 30 returns the coolant to the coolant chamber 6 from the coolant inlet 6 a via the coolant pipe 41, and a part thereof is supplied again to the high pressure steam generator 16 via the high pressure pump 31.

(Recovery of heat and power of cooling liquid by steam generation tank and first expander)
By setting the internal pressure of the steam generation tank 10 to a saturation pressure corresponding to the required cooling temperature of the cooling water, the inside of the cooling liquid chamber 6 is also set to the above-mentioned saturation pressure, and the cooling water is heated (received heat) by engine cooling. Evaporate to obtain low temperature and low pressure steam (saturated steam). The low-temperature and low-pressure steam is led from the steam outlet 10b through the steam pipe 45 to the low-pressure first expander 21, and rotates to rotate the output shaft of the first expander 21. 1 generator 24 is driven to generate power. That is, the heat of the cooling water is recovered as electric power.

  The steam expanded in the first expander 21 is discharged from the steam outlet 21 b, merged with the steam from the second expander 22 in the steam pipe 43, and supplied to the condenser 27.

  In such a Rankine cycle of low-pressure steam using the steam generation tank 10, a furnace tube boiler and a steam generation tank 10 are provided in the coolant chamber 6 and the steam generation tank 10 that cool the surroundings of the heat generating portions such as the cylinder liner 1 and the cylinder head 3. Since the same role is played, a new heat exchanger for exchanging heat between the engine cooling water and the secondary heat medium as in the conventional apparatus of FIG. Can be reduced.

  Further, by adjusting the pressure in the steam generation tank 10, the temperature in the coolant chamber 6 is set to the saturation temperature, and the heat of the cooling water is also recovered as latent heat at the saturated steam temperature of about the preheating of the conventional example. For example, more heat and power can be recovered than the configuration in which the sensible heat of the cooling water is recovered for preheating of the high-pressure steam system as in Patent Document 1.

  FIG. 2 is a TS diagram (temperature-entropy diagram) in the present embodiment. A graph X1 indicated by a one-dot chain line indicates a temperature change of exhaust gas in the high-pressure steam generator 15, a broken line X2 indicated by a solid line. Is a temperature change of the cooling water (steam) in the high-pressure steam generator 15, and a broken line X3 indicated by a broken line indicates a temperature change of the cooling water in the steam generation tank. As can be seen from the broken line X3, in the Rankine cycle of low-pressure steam, even if the temperature is lower than the temperature (T3) of the exhaust gas at the pinch point PP for heat exchange between the high-pressure steam (X2) and the exhaust gas (X1), Even at a temperature (saturation temperature) lower than the exhaust gas discharge temperature (T1), sufficiently low-pressure steam (X3) can be generated in the steam generation tank 10, and the exhaust heat of the cooling water can be efficiently used as latent heat. It can be recovered.

[Second Embodiment]
3 to 6 show a second embodiment of the present invention. Compared with the first embodiment of FIG. 1, the coolant chamber 6 and the low-pressure steam generation tank 10 of the internal combustion engine 1 are provided. The difference is that each of the two is divided into two and that a mixed type is used as the first expander 21 for low pressure, but the other structure is the same as that of the first embodiment of FIG. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 3, the coolant chamber 6 of the internal combustion engine 1 has a low temperature side first cooling chamber portion 7 surrounding a portion where the temperature rise is small like the cylinder liner 2, and the cylinder head 3 and the exhaust port 14a. The steam generation tank 10 disposed at the upper end of the coolant chamber 6 is also divided into the second cooling chamber portion 8 on the high temperature side that surrounds the portion where the rise is large. The first steam generation tank 11 that communicates with the coolant chamber portion 7 and the second steam generation tank 12 that communicates with the second coolant chamber portion 8 on the high temperature side are partitioned.

  The inside of the first steam generation tank 11 is set to a pressure corresponding to the saturation temperature of the cooling water with a small temperature rise in the first cooling chamber portion 7, and the inside of the second steam generation tank 12 is The pressure corresponding to the saturation temperature of the cooling water having a large temperature rise in the two cooling chamber portions 8 is set. Since the saturation temperature of the cooling water in the second cooling fluid chamber portion 8 is higher than the saturation temperature of the cooling water in the first cooling fluid chamber portion 7, the first steam generation is generated in the second steam generation tank 12. The internal pressure is set to be higher than that in the tank 11, whereby relatively high-pressure steam is generated in the second steam generation tank 12 than in the first steam generation tank 11.

  Among the first and second steam generation tanks 11 and 12, the steam outlet 12 b of the relatively high-pressure second steam generation tank 12 is connected to the steam inlet 21 a of the first expander 21 via the steam pipe 45. The steam outlet 11b of the first steam generation tank 11 that is connected and generates relatively low-pressure steam is a part of the first expander 21 that is in the middle of expansion downstream of the steam inlet 21a via the steam pipe 47. Are connected to the intermediate steam inlet 21c.

  FIG. 4 shows an example in which a multistage steam turbine is used as the mixed first expander 21. On the same turbine output shaft 54, a small-diameter high-pressure stage turbine section 51, a medium-diameter medium-pressure stage turbine section 52, and a large-diameter low-pressure stage turbine section 53 are provided in this order from the steam inlet 21a side. Reference numerals 51, 52, and 53 include fixed blades 51a, 52a, and 53a and rotary blades 51b, 52b, and 53b, respectively. Among the three turbine parts 51, 52, 53, the fixed blade 51 a of the high-pressure stage turbine part 51 is provided with a steam inlet 21 a connected to the high-pressure steam generator 15, and the fixed blade 53 a of the low-pressure stage turbine part 53 is provided with An intermediate steam inlet 21 c connected to the first steam generation tank 11 is provided.

  The operation in the present embodiment is basically the same as that in the first embodiment except for the operation related to the first expander 21 for low pressure. That is, in the first expander 21 for low pressure, the low pressure steam of the first steam generation tank 11 is additionally introduced from the intermediate steam inlet 21c during the expansion, and steam is supplied only from the steam inlet 21a. In contrast, the pressure in the expansion chamber can be kept high until the end of the expansion, the expansion work can be performed efficiently, and a large amount of power can be recovered.

[Third Embodiment]
In the third embodiment of the present invention, as shown in FIG. 3, the coolant chamber 6 and the steam generation tank 10 are replaced with the first coolant chamber portion 7 and the first steam generation tank 11 on the low temperature side, In the exhaust heat recovery apparatus in which the first expander 21 is a mixed type, the mixed first first expander 21 is classified into the second coolant chamber portion 8 and the second steam generation tank 12 on the high temperature side. As an example, a positive displacement scroll expander shown in FIG. 5 is used. That is, except for the structure of the first expander 21, it is the same as the second embodiment of FIG.

  5A, the scroll-type first expander 21 includes a fixed scroll 60 having a spiral blade 60a and a spiral meshing with the spiral blade 60a of the fixed scroll 60 in a sealed case (not shown). A plurality of expansion chambers 65 are provided between the spiral blades 60a and 61a, and the volume of the chamber increases sequentially from the center to the outer periphery, and includes a swing side (swivel side) scroll 61 having blades 61a. The swing-side scroll 61 is configured to turn (swing in the radial direction) without rotating with respect to the stationary-side scroll 60 in a stationary state.

  A steam inlet 21a is formed in the center of the room where the expansion starts, and the second steam generation tank 12 on the high temperature side in FIG. 3 is connected to the steam inlet 21a, so that relatively high-pressure steam is introduced. It has become so. On the other hand, the intermediate steam inlet 21c is formed in the vicinity of the spiral blade 60a of the fixed-side scroll 60 that is apart from the center by a certain distance, and is about the blade thickness. The steam generation tank 11 is connected so that relatively low-pressure steam is introduced into the expansion chamber 65 during expansion. A pair of the intermediate steam inlets 21c are arranged at positions symmetrical with respect to the center. The spiral blade 60a of the fixed scroll 60 is shown by a solid line. However, in order to make the distinction different from this, the spiral blade 61a of the swing scroll 61 is shown by a broken line, and The resulting expansion chamber 65 is indicated by a number of dots.

  The state shown in FIG. 5A is a state immediately after relatively low-pressure steam is introduced from the intermediate steam inlet 21c into the expansion chamber 65 in the middle of expansion. The state of B in FIG. 5 is a state immediately before closing the intermediate steam inlet 21c. The state of C in FIG. 5 is a state after the intermediate steam inlet 21c is closed.

  FIG. 6 shows a pressure change in the expansion chamber 65 in the mixed scroll expander 21 of FIG. 5, and a horizontal straight line W1 indicated by a solid line is an expansion in which the steam inlet 21a of FIG. 5 is open. The broken line W2 indicated by a solid line is a change in the pressure in the expansion chamber when additional steam is introduced from the intermediate steam inlet 21c during the expansion, and the broken line W3 indicated by a broken line is a pressure from the intermediate steam inlet 21c. This is a change in pressure in the expansion chamber when steam is not added during expansion.

  By adding low-pressure steam from the intermediate steam inlet 21c when the swing angle of the swing scroll 61 is θ1, in this embodiment (W2), the pressure drop is extremely reduced in the expansion process from the angle θ1 to the angle θ2. It can be suppressed to a small value. On the other hand, when no additional steam is introduced from the intermediate steam inlet 21c as shown by the broken line (W3), the pressure is greatly reduced during the expansion process from the angle θ1 to the angle θ2, and then reaches the next angle θ3. In addition, the pressure further decreases. That is, according to the present embodiment, by adding steam during expansion, the pressure in the expansion chamber is kept high until the end of expansion, and much power can be recovered.

  Further, when the scroll type expander (volume type expander) is used as in the present embodiment, the drag increase is caused as compared with the case where the steam turbine (speed type expander) of FIG. 4 is used. Reduction in efficiency and occurrence of erosion can be suppressed. This can be said not only in the mixed expander but also in a normal expander that supplies steam only from the steam inlet 21a as shown in FIG.

  That is, when the saturated steam is expanded in the first expander 21, the dry steam is changed to the wet steam, and when the wetness is increased, the drag increases in the case of a speed type expander such as a steam turbine. Efficiency may be reduced and erosion may occur. On the other hand, in the case of a volume type expander 21 such as a scroll type, the partially liquefied medium serves as a seal for the sealed chamber, and on the contrary, the efficiency is improved, and moreover, it is more rocky than the speed type. Since the rotation of the dynamic scroll or the like is slow, there is no fear of erosion.

[Fourth Embodiment]
FIG. 7 shows a fourth embodiment of the present invention. Compared to the first embodiment of FIG. 1, the pressure at the steam outlet 22 b of the second expander 22 is set to the internal pressure of the steam generation tank 10. The structure in which the steam from the steam outlet 22b is combined with the steam from the steam generation tank 10 and supplied to the steam inlet 21a of the first expander 21 is different. ing. The other structure is the same as that of FIG. 1 of the first embodiment, and the same components and the like as those of FIG.

  According to this embodiment, the expansion ratio of the second expander 22 for high pressure can be reduced, so that, for example, if the second expander 22 is a steam turbine type (speed type) expander, The number of turbine stages can be reduced, and a scroll type (volumetric) type expander can reduce the number of expansion chambers, and in any case, the second expander 22 can be miniaturized. At the same time, the cost can be reduced.

[Fifth Embodiment]
FIG. 8 shows a fifth embodiment of the present invention. Compared with the first embodiment of FIG. 1, a single generator 70 is provided as a load device. The structure in which the first expander 21 for low pressure is connected to one end of the power generation shaft and the second expander 22 for high pressure is connected to the other end is different, but the other structure is the first It is the same as that of FIG. 1 of embodiment, the same code | symbol is attached | subjected to the same components as FIG. 1, and detailed description is abbreviate | omitted.

  According to the embodiment, when the exhaust heat of the internal combustion engine 1 is recovered as electric energy by the generator 70, it is possible to reduce the size and cost of the exhaust heat recovery device.

[Sixth Embodiment]
FIG. 9 shows a sixth embodiment of the present invention. The structure including the single generator 70 of the fifth embodiment of FIG. 8 and the fourth embodiment of FIG. And a structure in which the steam outlet 22b of the second expander 22 is connected to the steam inlet 21a of the first expander 21. The other structures are the same as those in FIG. 1, and the same components and the like as those in FIG.

  That is, the generator 70 is provided as a load device, and the first expander 21 and the second expander 22 are connected to both ends of the power generation shaft of the generator 70, respectively. The pressure at the steam outlet 22b of the expander 22 is set to be substantially equal to the internal pressure of the steam generation tank 10, and the steam from the steam outlet 22b is connected to the steam from the steam generation tank 10 via the steam pipe 48. These are combined and supplied to the steam inlet 21 a of the first expander 21.

  According to the embodiment, the expansion ratio of the second expander 22 for high pressure can be reduced. For example, if the second expander 22 is a steam turbine type expander, the number of turbine stages can be reduced. If the scroll expander is used, the number of expansion chambers can be reduced. In any case, the cost of the second expander 22 can be reduced.

  Further, when the exhaust heat of the internal combustion engine 1 is recovered as electrical energy by the generator 70, it is possible to reduce the size and cost of the exhaust heat recovery device.

[Seventh Embodiment]
FIG. 10 shows a seventh embodiment of the present invention. The structure of the fifth embodiment shown in FIG. 8 having the single generator 70 and the cooling of the second embodiment shown in FIG. The liquid chamber 6 and the steam generation tank 10 are divided into a low temperature side first cooling liquid chamber portion 7 and a first steam generation tank 11, and a high temperature side second second cooling chamber portion 8 and a second steam generation. This structure is a combination of the structures sorted into the tank 12. The other structures are the same as those in FIG. 1, and the same components and the like as those in FIG.

  That is, as the load device, one generator 70 is provided, and the first expander 21 and the second expander 22 are connected to both ends of the power generation shaft of the one generator 70, respectively. The coolant chamber 6 of the internal combustion engine 1 includes a first cooling chamber portion 7 surrounding a portion where the temperature rise is small like the cylinder liner 2 and a portion where the temperature rise is high like the cylinder head 3 and the exhaust port 14a. Corresponding to this, the steam generation tank 10 is also divided into a low temperature side first steam generation tank 11 communicating with the first coolant chamber part 7, It is partitioned into a second steam generation tank 12 on the high temperature side communicating with the second coolant chamber portion 8.

  The inside of the first steam generation tank 11 is set to a pressure corresponding to the saturation temperature of the cooling water with a small temperature rise in the first cooling chamber portion 7, and the inside of the second steam generation tank 12 is 2 is set to a pressure corresponding to the saturation temperature of the cooling water having a large temperature rise in the cooling chamber portion 8. Since the saturation temperature of the cooling water in the second cooling fluid chamber portion 8 is higher than the saturation temperature of the cooling water in the first cooling fluid chamber portion 7, the first steam generation is generated in the second steam generation tank 12. The internal pressure is set to be higher than that in the tank 11, whereby relatively high-pressure steam is generated in the second steam generation tank 12 than in the first steam generation tank 11.

  The steam outlet 12b of the second steam generation tank 12 is connected to the steam inlet 21a of the first expander 21, and the steam outlet 11b of the second steam generation tank 11 that generates relatively low-pressure steam is It connects with the intermediate | middle steam inlet 21c of the expansion middle part downstream from the said steam inlet 21a of the 1 expander 21. FIG.

  According to this embodiment, when the exhaust heat of the internal combustion engine is recovered as electric energy by the generator 70, it is possible to reduce the size and cost of the exhaust heat recovery device.

  Further, in the first expander 21 for low pressure, since low pressure steam from the first steam generation tank 11 on the low temperature side is additionally introduced during expansion, steam is supplied only from the steam inlet 21a as in the prior art. Compared to the configuration, the pressure in the expansion chamber is kept high until the end of expansion, and much power can be recovered.

[Eighth Embodiment]
FIG. 11 shows an eighth embodiment of the present invention, which includes a single generator 70 as a load device, and one mixed expander 71 connected to the end of the power generation shaft of the single generator 70. In addition to this structure, as in the second embodiment of FIG. 4, the coolant chamber 6 and the steam generation tank 10 are replaced with the first coolant chamber portion 7 and the first steam generation on the low temperature side. The tank 11 is partitioned into a high temperature side second cooling chamber portion 8 and a second steam generation tank 12.

  The single expander 71 includes a steam inlet 71a, an intermediate steam inlet 71c, and a downstream steam inlet 71d downstream of the intermediate steam inlet 71c, and expands the steam outlet 16b of the high-pressure steam generator 15. Connected to the steam inlet 71a of the expander 71, the steam outlet 12b of the second steam generation tank 12 on the high temperature side is connected to the intermediate steam inlet 71c of the expander 71, and the steam outlet of the first steam generation tank 11 on the low temperature side 11b is connected to the downstream steam inlet 71d of the expander 71. The other structures are the same as those in FIG. 1, and the same components and the like as those in FIG.

  FIG. 12 is an example of the mixed expander 71 of FIG. 11 and shows an example applied to a three-stage steam turbine. The expander 71 includes a small-diameter high-pressure stage turbine section 51, a medium-diameter medium-pressure stage turbine section 52, and a large-diameter low-pressure stage turbine section 53 in order from the steam inlet 21a side on the same turbine output shaft 54. Each turbine section 51, 52, 53 is composed of fixed blades 51a, 52a, 53a and rotary blades 51b, 52b, 53b, respectively. Among the three turbine parts 51, 52, 53, a steam inlet 71a is provided in the fixed blade 51a of the high-pressure stage turbine part 51, and the steam outlet 16b of the high-pressure steam generator 15 is connected to the steam inlet 71a. An intermediate steam inlet 71c is provided in the fixed blade 52a of the section 52, the steam outlet 12b of the second steam generation tank 12 is connected to the intermediate steam inlet 71c, and the downstream steam inlet 71d is connected to the fixed blade 53a of the low-pressure turbine section 53. The steam outlet 11b of the first steam generation tank 11 is connected to the downstream steam inlet 71d.

  According to the embodiment, since the single expander 71 and the single generator (load device) 70 are provided, the cost can be reduced. Further, during the expansion, since the additional steam is sequentially introduced in two stages from the second steam generation tank 12 and the first steam generation tank 11, the low-pressure steam is supplied only once during the expansion as shown in FIG. Even when compared with the structure to be added, the pressure in the expansion chamber is kept higher until the end of expansion, and much power can be recovered.

[Ninth Embodiment]
The ninth embodiment of the present invention comprises a mixed single expander 71 and a single generator 7 as in the eighth embodiment of FIG. 11, and includes a coolant chamber 6 and steam. The generation tank 10 is partitioned into a first coolant chamber portion 7 and a first steam generation tank 11 on the low temperature side, and a second coolant chamber portion 8 and a second steam generation tank 12 on the high temperature side. In the exhaust heat recovery apparatus, a volumetric scroll expander 71 shown in FIG. 13 is provided as the mixed first expander 71. Except for the structure of the mixed first expander 71, the structure is the same as that of the eighth embodiment shown in FIG.

  13A, a scroll-type first expander 71 includes a fixed scroll 60 having a spiral blade 60a and a spiral meshing with the spiral blade 60a of the fixed scroll 60 in a sealed case (not shown). A plurality of expansion chambers 65 are provided between the spiral blades 60a and 61a, and the volume of the chamber increases sequentially from the center to the outer periphery, and includes a swing side (swivel side) scroll 61 having blades 61a. The swing-side scroll 61 is configured to swing (turn) in the radial direction without rotating with respect to the stationary-side scroll 60 in a stationary state.

  A steam inlet 71a connected to the high-pressure steam generator 15 is formed at the center of the room where expansion begins, and an intermediate steam inlet 71c connected to the second steam generation tank 12 is fixed at a fixed distance from the center. A downstream steam inlet 71d that is formed in the vicinity of the spiral blade 60a of the side scroll 60 and has a thickness of about the blade thickness and is connected to the first steam generation tank 11 further extends in the radial direction from the intermediate steam inlet 71c. The outer side of the fixed side scroll 60 is formed in the vicinity of the spiral blade 60a and is formed in a size about the blade thickness.

  FIG. 13A shows a state immediately after the steam in the second steam generation tank 12 on the high temperature side is introduced from the intermediate steam inlet 71c, and FIG. 71 d shows a state immediately after the relatively low pressure steam is introduced into the expansion chamber 65.

  As in this embodiment, after introducing high-pressure steam from the steam inlet 71a, in the expansion process, relatively high-pressure steam is added from the intermediate steam inlet 21c, and thereafter, relatively high-pressure from the downstream steam inlet 21d. When low-pressure steam is added, the pressure in the expansion chamber 65 can be kept high until the end of expansion, as compared with the structure in which steam is added only once in the expansion process, as shown in FIG. Power can be recovered.

[Tenth embodiment]
In the first to ninth embodiments, a saturated steam boiler is provided as the high-pressure steam generator 15 when the second expander 22 or the expander 71 connected to the high-pressure steam generator 15 is a positive displacement type.

  According to this embodiment, in the second expander 22 or the common expander 71, the wetness of the steam may be increased, so that a superheater is not necessary. That is, the cost required for the superheater can be reduced.

Incidentally, in the case of using a speed expander such as a steam turbine, as shown in FIG. 14, in order to prevent the steam from expanding after the expansion, the saturated steam is further superheated as indicated by an arrow E. A superheater is required.
[Other embodiments]
In the exhaust heat recovery device of each internal combustion engine, a generator is provided as a load device, but other load devices can also be connected.

1 is a schematic piping diagram showing a first embodiment of an exhaust heat recovery apparatus according to the present invention. It is a TS diagram in a 1st embodiment. It is piping schematic which shows 2nd Embodiment of the waste heat recovery apparatus by this invention. It is a simplified sectional view of the 1st expander of a 2nd embodiment. It is a simplified sectional view of the 2nd expander of a 3rd embodiment of the exhaust heat recovery device by the present invention. It is a figure which shows the expansion chamber pressure change in 3rd Embodiment. It is piping schematic which shows 4th Embodiment of the waste heat recovery apparatus by this invention. It is piping schematic which shows 5th Embodiment of the waste heat recovery apparatus by this invention. It is piping schematic which shows 6th Embodiment of the waste heat recovery apparatus by this invention. It is piping schematic which shows 7th Embodiment of the waste heat recovery apparatus by this invention. It is piping schematic which shows 8th Embodiment of the waste heat recovery apparatus by this invention. It is a simplified sectional view of an expander of an eighth embodiment. It is a simplified sectional view of an expander of a ninth embodiment of the exhaust heat recovery apparatus according to the present invention. It is a TS diagram of a 9th embodiment. It is a general temperature-exchange heat quantity diagram in a heat exchanger. It is piping schematic which shows an example of the conventional waste heat recovery apparatus. FIG. 17 is a temperature-exchange heat quantity diagram when the primary medium of the heat exchanger is preheated in the conventional exhaust heat recovery apparatus of FIG. 16.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder liner 3 Cylinder head 6 Coolant chamber 7 Low temperature side first cooling chamber portion 8 High temperature side second cooling chamber portion 10 Steam generation tank (hopper tank)
DESCRIPTION OF SYMBOLS 11 Low pressure side first steam generation tank 12 High pressure side second steam generation tank 14 Exhaust pipe 14a Exhaust port 21 Low pressure first expander 21a Steam inlet 21b Steam outlet 21c Intermediate steam outlet 22 High pressure second tank Second expander 22a Steam inlet 22b Steam outlet 24 First generator (an example of a load device)
25 Second generator (an example of a load device)
27 Condenser 51 High-pressure stage turbine section 52 Medium-pressure stage turbine section 53 Low-pressure stage turbine section 71 Shared type expander 71a Steam inlet 71b Steam outlet 71c Intermediate steam outlet 71d Downstream intermediate steam outlet

Claims (9)

A steam generation tank that communicates with a coolant chamber of an internal combustion engine, and maintains a pressure in the tank at a saturation pressure corresponding to a medium temperature necessary for cooling, thereby reducing a low pressure from the coolant used for engine cooling. A steam generation tank for obtaining steam;
A first low-pressure expander that obtains power by expanding low-pressure steam supplied from the steam generation tank;
A high-pressure steam generator that takes in a part of the coolant before use for engine cooling and exchanges heat with the exhaust gas of the internal combustion engine to obtain steam at a pressure higher than that of the steam generating tank;
A second high-pressure expander that obtains power independently of the first expander by expanding the high-pressure steam supplied from the high-pressure steam generator;
A condenser for liquefying the expanded steam discharged from each expander and supplying the liquefied cooling liquid to the cooling liquid chamber of the internal combustion engine and the high-pressure steam generator;
An exhaust heat recovery apparatus comprising: The exhaust heat recovery apparatus according to claim 1,
Partitioning the cooling liquid chamber into a high temperature side cooling liquid chamber portion and a low temperature side cooling liquid chamber portion having different cooling liquid rising temperatures;
Dividing the steam generation tank into a first steam generation tank communicating with the low temperature side coolant chamber part and a second steam generation tank communicating with the high temperature side coolant chamber part;
Of the first and second steam generation tanks, a second steam generation tank that generates steam at a relatively high pressure is connected to the steam inlet of the first expander,
An exhaust heat recovery apparatus, wherein a first steam generation tank that generates steam at a relatively low pressure is connected to a part of the first expander that is in the middle of expansion downstream of the steam inlet. In the exhaust heat recovery apparatus according to claim 1 or 2,
The exhaust heat recovery apparatus, wherein the first expander and the second expander are connected to independent generators. In the exhaust heat recovery apparatus according to claim 1 or 2,
An exhaust heat recovery apparatus in which a first expander is connected to one end of a power generation shaft of one generator and a second expander is connected to the other end. The exhaust heat recovery apparatus according to claim 1,
The pressure of the steam outlet of the second expander for high pressure is maintained at substantially the same pressure as the internal pressure of the steam generation tank, and instead of connecting the steam outlet to the condenser, the steam of the first expander for low pressure is used. An exhaust heat recovery apparatus characterized by being supplied to an inlet. Partitioning the coolant chamber of the internal combustion engine into a high temperature side coolant chamber portion and a low temperature side coolant chamber portion having different coolant rise temperatures;
A first steam generation tank communicating with the cooling chamber portion on the low temperature side, and maintaining the pressure in the tank at a saturation pressure corresponding to the medium temperature required for cooling, cooling after use for engine cooling A first steam generation tank for obtaining steam from the liquid;
A second steam generation tank communicating with the cooling chamber portion on the high temperature side, wherein the pressure in the tank is made higher than the pressure in the first steam generation tank; A second steam generation tank for obtaining steam having a pressure higher than that of the first steam generation tank from the coolant;
A high-pressure steam generator that takes a part of the coolant before use for engine cooling and exchanges heat with the exhaust gas of the internal combustion engine to obtain steam at a pressure higher than that of each steam generation tank;
A steam inlet for taking in the steam of the high-pressure steam generator, an intermediate steam inlet for taking in the steam of the second steam generation tank from the middle of expansion, and the first steam generation tank in the middle of expansion downstream from the intermediate steam inlet An expander having a downstream steam inlet for taking in
A condenser for liquefying the expanded steam discharged from the expander and supplying the liquefied coolant to the coolant chamber of the internal combustion engine and the high-pressure steam generator;
An exhaust heat recovery apparatus comprising: In the exhaust-heat recovery apparatus in any one of Claims 1-6,
The exhaust heat recovery apparatus according to claim 1, wherein the expander is a speed expander. In the exhaust-heat recovery apparatus in any one of Claims 1-6,
The exhaust heat recovery apparatus, wherein the expander is a positive displacement expander. In the exhaust-heat-recovery apparatus in any one of Claims 1-8,
An exhaust heat recovery apparatus, wherein the high-pressure steam generator is a saturated boiler.

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