JPH116602A - Structure of heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the structure of a high efficiency heat exchanger to effect heat-exchange between exhaust gas and water or steam. SOLUTION: This structure of a heat-exchanger comprises a casing 7 incorporated in an exhaust gas passage 8; a partition wall 33 arranged in the casing 7, a water of steam passage 36 which is formed in the partition wall 33 and through which water or steam flows, and an exhaust gas passage 29 which is formed at the external part of the partition wall 33 and through which exhaust gas flows. Porous members 38 and 41 are arranged in the water steam passage 36 and the exhaust gas passage 29, and a reinforced member having ceramics mixed with a fiber material is arranged in porous members 38 and 42 made of ceramic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a structure of a heat exchanger provided in an exhaust passage for recovering exhaust heat energy from exhaust gas discharged from an engine.

[0002]

2. Description of the Related Art Conventionally, a heat shield type engine equipped with a turbocharger is provided with a turbocharger equipped with a turbine and a compressor in the first stage of an exhaust system, and a turbine having a generator downstream of the turbocharger. Energy recovery equipment is installed. In the heat shield type engine, the combustion chamber has a heat shield structure, and the thermal energy of the exhaust gas discharged from the combustion chamber is recovered as electric power by a turbocharger or an energy recovery device, or overheated by driving a compressor of the turbocharger. Collected by feeding.

An energy recovery system that does not reduce the efficiency of exhaust gas energy recovery for the above-mentioned heat shield type engine is disclosed in Japanese Patent Application Laid-Open No. Hei 5-17972. The energy recovery system is
An energy recovery device including a first turbine provided in an exhaust passage and a generator operated by the first turbine, a second turbine connected to an outlet passage of the first turbine, and a turbine operated by the second turbine; The turbocharger includes a turbocharger provided with a supply compressor, and a wastegate installed in an outlet passage of the first turbine.

In the cogeneration system, power is taken out as electric energy by a generator, and heat energy of exhaust gas is heated by a heat exchanger provided in an electric power or exhaust passage to make hot water to be used for hot water supply. I have. Such a cogeneration system is expected to be used as an electric power supply system in an urban area, a mountainous area, or the like, with a rated operation and a small load fluctuation.

[0005] As a cogeneration system as described above, there is one disclosed in Japanese Patent Application Laid-Open No. 6-33707. The cogeneration system generates steam with exhaust gas energy, recovers the steam energy as electric energy to improve thermal efficiency, and drives a turbocharger with the exhaust gas energy of a heat shield type gas engine. The energy recovery device equipped with a generator is driven by the exhaust gas energy from the turbocharger. The thermal energy of the exhaust gas from the energy recovery device is converted into steam by the first heat exchanger, and the steam drives the steam turbine to recover the electrical energy. Furthermore, the second
The heat exchanger generates hot water with high-temperature steam from the steam turbine, and uses the hot water for hot water supply.

[0006]

However, when it is desired to generate electric power with high efficiency by an engine using natural gas or the like as a fuel, it is effective to combine several systems. Since natural gas is difficult to burn, the combustion chamber should be constructed with a heat shield structure to improve combustion, and the part where exhaust gas discharged from the combustion chamber comes into contact should be constructed with a heat shield structure using a material such as ceramics. Is preferred. Therefore, in the heat shield type engine as described above, the combustion chamber is configured as a heat shield structure,
It is conceivable to arrange a turbocharger to effectively collect the pressure of the exhaust gas discharged from the combustion chamber. Furthermore,
Regardless of the pressure of the exhaust gas discharged from the combustion chamber, it is conceivable to recover heat energy by a heat exchanger.
However, the exhaust gas is a gas, and recovery of thermal energy from the gas requires a large surface area with which the gas contacts.

The present inventor has developed a heat exchanger using a porous ceramic member, and has previously filed an application as Japanese Patent Application No. Hei 9-118657. As described in the specification of the application, in the process of transferring heat between substances, the heat transfer amount Q is expressed by the following equation. Q = K · A _S (T _G −T _S ) · t where K: heat transmission coefficient, A _S : average area of heat transfer path,
T _G : high temperature gas temperature, T _s : low temperature medium temperature, t: heat transfer period. The heat transfer rate K is expressed by the following equation. K = 1 / (X ₁ + X ₂ + X ₃ ) where X ₁ = (1 / α _g ) × (A _S / A ₁ ) X ₂ = (δ ₁ / λ ₁ ) × (A _S / A ₂ ) X ₃ = (1 / α _c ) × (A _S / A ₃ ) Further, α _g : heat transfer coefficient of high-temperature gas, λ ₁ : heat conductivity of solid,
α _c : heat transfer coefficient in the low temperature area, A ₁ , A ₂ , A ₃ : contact area of the heat transfer member, δ ₁ : wall thickness of the wall.

In the above equation, when the values of the heat transfer coefficient of the exhaust gas, the heat conductivity of the heat exchanger, and the heat transfer coefficient of the steam are substituted, the heat transfer coefficient K is
It can be seen that the contribution rate of the heat transfer coefficient of the dry steam has a large effect. Therefore, in order to reduce the value that affects the value of the heat transfer rate K, it is necessary to increase the values of A ₁ and A ₃ and reduce the contribution rate. On the other hand, the material constituting the heat exchanger needs to have a low thermal conductivity and strong characteristics against exhaust gas.

[0009]

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to dispose a porous ceramic in an exhaust passage for recovering thermal energy of exhaust gas discharged from a combustion chamber. It is an object of the present invention to provide a heat exchanger structure in which the members are arranged to form a large contact area of a fluid such as exhaust gas and steam, and the porous ceramic member is reinforced with a fiber material to increase the strength.

The present invention provides a casing incorporated in an exhaust gas passage, a partition disposed in the casing, a low-temperature side passage formed in the partition, through which a low-temperature fluid flows, and the casing outside the partition. In a heat exchanger structure for heating a fluid with an exhaust gas formed of a high-temperature side passage through which a high-temperature gas flows, a ceramic porous member is disposed in the low-temperature side passage and the high-temperature side passage; The present invention relates to a structure of a heat exchanger, wherein a reinforcing member in which a fiber material is mixed with ceramics is disposed in a porous member.

The reinforcing member comprises a number of fins extending radially from the inner and outer surfaces of the partition into the ceramic porous member. The reinforcing member has a core made of carbon fiber and an outer part made of silicon carbide. Further, the reinforcing member on the side where the exhaust gas flows is provided with a core formed of a nonwoven fabric of carbon fiber, a core mixed with a slurry of a mixture of Si powder and carbon powder, and a surface of the core formed with the slurry. And sintering it in N ₂ gas at a temperature of about 1500 ° C. to 1700 ° C. to form the carbon fibers of the core into a structure coated with the silicon nitride on the outside where the slurry is converted. Have been.

The reinforcing member on the side where the exhaust gas flows is made of a composite material containing carbon fibers coated with silicon carbide and silicon nitride. The porous ceramic member on the side where water or steam flows is made of silicon nitride whose surface is coated with silicon carbide. Alternatively, the ceramic porous member on the side where exhaust gas flows and on the side where water or steam flows is made of silicon carbide or silicon nitride coated with silicon carbide.

In the heat exchanger structure, the ceramic porous member disposed in the low-temperature side passage through which water and steam flow is made of silicon carbide. The ceramic porous member disposed in the high-temperature side passage through which exhaust gas flows is made of silicon nitride.

In the structure of the heat exchanger, the partition walls are made of a carbon fiber non-woven fabric or a silicon carbide fiber molded partition wall core, and the partition wall core is made to permeate a slurry obtained by mixing Si powder and carbon powder. The surface of the core of the partition wall is coated with the slurry.
Sintered in N ₂ gas at a temperature of about 1 ° C. to 1700 ° C. to form a structure in which the carbon fiber or silicon carbide fiber is not exposed on the surface. Therefore, since the carbon fiber is coated with SiC, the carbon fiber does not come into contact with oxygen and does not oxidize, so that the strength can be secured for a long period of time. Further, since the SiC fiber is covered with Si ₃ N ₄ , recrystallization between particles does not occur even at a high temperature.
The fiber strength of SiC does not decrease.

The structure of the heat exchanger is applied to a heat exchange device disposed in an exhaust passage from which exhaust gas of an engine is discharged, and the heat exchange device converts water into steam by using heat energy of the exhaust gas. Heating. The heat exchange device is provided downstream of a turbocharger provided in the exhaust passage for discharging exhaust gas from the engine. Further, the present invention is applied to an energy recovery device in which a steam turbine is driven by high-temperature steam generated in the heat exchange device and power is generated by a generator provided in the steam turbine. Further, the present invention is applied to a second-stage heat exchanger provided downstream of the first-stage heat exchanger in the heat exchange device, and the second-stage heat exchanger is provided with the exhaust gas passing through the first-stage heat exchanger. The water is heated by the gas to convert the water into steam, and the steam is sent to the first-stage heat exchanger.

As described above, the structure of this heat exchanger is compactly composed of a two-stage heat exchanger, and in particular, the heat exchange contact areas of exhaust gas and steam, and of exhaust gas and water, respectively, are appropriately configured. Therefore, the heat exchange efficiency can be greatly improved. This gas engine incorporates the above heat exchange device with good heat exchange efficiency into the exhaust passage, recovers energy using a heat exchange device that does not require high exhaust pressure, and can reduce loss by reducing back pressure. At the same time, since the exhaust heat energy can be effectively recovered, the fuel efficiency can be reduced.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the structure of a heat exchanger according to the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of the structure of the heat exchanger according to the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

The structure of the heat exchanger is applied to a heat exchanger for heating a fluid with exhaust gas, that is, a second-stage heat exchanger 6. The pipe 33 constituting the arranged partition wall, the low-temperature side passage or water / steam passage 36 formed inside the pipe 33 through which the low-temperature fluid flows, and the high temperature formed inside the casing 7 outside the pipe 33. A high-temperature side passage through which gas flows, that is, an exhaust gas passage 29 is formed. In the heat exchanger 6, a ceramic porous member 38 is provided in the water / steam passage 36.
Are disposed, and a ceramic porous member 42 is disposed in the exhaust gas passage 29, and the ceramic porous members 38 and 4 are disposed.
2 includes a reinforcing member 39 obtained by mixing a fiber material with ceramics.
Is arranged. The heat transfer portion 40 extending in the ceramic porous member 42 of the heat exchanger 6 receives heat energy sufficiently from the exhaust gas to heat the steam passing through the ceramic porous member 38 through the pipe 33. Become.

The reinforcing member 39 is constructed in the form of a multiplicity of fins extending radially from the inner and outer surfaces of the partition wall or tube 33 into the ceramic porous members 38,42. Reinforcing member 39 constituting high-temperature side passage 29 through which exhaust gas flows
Is composed of a composite material containing carbon nitride and silicon nitride coated with silicon carbide.

In the structure of this heat exchanger, the ceramic porous member 38 disposed in the water / steam passage 36 on the low temperature side passage through which water and steam flow has a core made of silicon nitride.
The surface of the silicon nitride is composed of a composite material coated with silicon carbide. Or a ceramic porous member 38
Is composed of silicon carbide. The ceramic porous member 42 is made of ceramics such as silicon nitride and silicon carbide.

The structure of the heat exchanger can be manufactured as follows. The tubular body 33 constituting the partition wall is formed by forming a partition wall core portion into a cylindrical shape with a nonwoven fabric of carbon fiber, then infiltrating a slurry of a mixture of Si powder and carbon powder into the partition wall core portion, The surface is coated with the slurry. Therefore, the core of the partition wall, on which the slurry has penetrated and coated on the surface, is placed at 1500 ° C. to 170 ° C.
When sintering in N ₂ gas at a temperature of about 0 ° C., the slurry of Si powder and carbon reacts and is converted into Si ₃ N _4, and the amount of carbon fiber in the core of the partition wall increases. Carbon fibers will remain on the surface. Therefore, it is possible to form the tubular body 33 having a structure in which the carbon fibers coated with Si ₃ N ₄ on the outer side are not exposed on the surface. Further, a slurry of SiC is injected into the surface of the partition wall on the side where water or steam flows, and sintered to form a SiC slurry.
₃ SiC was coated on the surface of the N _4, constituting a structure which can prevent the corrosion of the silicon nitride.

Alternatively, the core of the partition wall for forming the partition wall 33 is made of S
The iC fiber is rolled into a round shape to form a cylindrical shape, and then
The SiC fiber is bent to form a bellows and arranged in a cylindrical shape. This is set in a mold, and then a slurry of SiC is injected and sintered, and the SiC fiber in the core of the partition wall is carbonized on the outer side. It is also possible to form the tubular body 33 coated with silicon and having a structure in which the SiC fiber portion is not exposed on the surface.

The reinforcing member 39 has a central portion made of carbon fiber and an outer portion made of silicon carbide. The structure composed of the central portion and the outer portion of the reinforcing member 39 can be configured as follows, for example. First,
A core is formed from a nonwoven fabric of carbon fiber, a slurry of a mixture of Si powder and carbon powder is infiltrated into the core, and the surface of the core is coated with the slurry.
When sintering in N ₂ gas at a temperature of about 00 ° C. to about 1700 ° C., the Si powder and the carbon slurry react to form Si ₃ N
₄ and the amount of carbon fiber in the core increases, so that the carbon fiber remains in the core. Therefore, it is possible to form the reinforcing member 39 having a structure in which the carbon fiber of the core of the reinforcing member 39 coated with silicon nitride on the outer side is not exposed on the surface. As a result, the carbon fibers in the core can be formed into a structure covered with the silicon nitride on the outer side where the slurry is converted. Furthermore,
The reinforcing member 39 located in the water / steam passage 36 has SiC
The slurry of Si ₃ N ₄ is injected and sintered.
Is coated with SiC to improve corrosion resistance.

Next, with reference to FIG. 3, an embodiment of a heat exchanger incorporating the structure of the heat exchanger will be described. The structure of this heat exchanger can be applied to a heat exchange device that is disposed in an exhaust passage 8 through which exhaust gas of an engine is discharged and that converts water into steam with the heat energy of the exhaust gas and heats the steam. A description will be given of an embodiment in which the second heat exchanger 6 in the latter stage of the apparatus is incorporated.

As shown in FIG. 3, the heat exchanger is provided with a first-stage heat exchanger 4 and a first-stage heat exchanger 4 provided in an exhaust passage 8 for heating steam with exhaust gas from an engine. A second stage heat exchanger 6 is provided in the stream and heats water to steam with the exhaust gas from the first stage heat exchanger 4. The first-stage heat exchanger 4 includes a steam passage 35 through which the steam heated by the second-stage heat exchanger 6 disposed in the casing 2 flows, and a plurality of exhaust gas through which the exhaust gas flows through the steam passage 35. And a tube body 22 that constitutes the passage 28. A ceramic porous member 42 similar to the above is disposed in the exhaust gas passage 28. In the steam passage 35,
A ceramic porous member 38 similar to the above is disposed. Further, the second-stage heat exchanger 6 is disposed in a casing 7 provided adjacent to the casing 2, and the configuration thereof is as described above.

A second-stage heat exchanger 6 is arranged below the first-stage heat exchanger 4. The pipes 33 constituting the water / steam passages 36 of the second-stage heat exchanger 6 are arranged vertically, and the partition walls constituting the second pipes 36, that is, the lower part 3 of the pipes 33.
4 stores water. Furthermore, casings 2, 7,
Tube 22, water / steam passage 3 constituting exhaust gas passage 28
6 is made of SiC or AlN ceramics having a low thermal conductivity.

The heat exchanger is formed as described above, and the first-stage heat exchanger 4 and the second-stage heat exchanger 6 are configured as follows. In the first-stage heat exchanger 4, the heat transfer coefficient of the steam sent from the first-stage heat exchanger 4 is small, so that the heat exchange contact area of steam, that is, the heat exchange contact area of the steam passage 35 formed of a porous member is large. Also, the heat exchange contact area of the exhaust gas, that is, the heat exchange contact area of the exhaust gas passage 28 is formed small. The second-stage heat exchanger 6 forms a water / steam passage 36 formed therein, and is filled with water in a partition wall or tube 33 having a small area. Since water and wet steam H ₂ O have a large heat transfer coefficient, the heat exchange contact area of water and wet steam, that is, the heat exchange contact area of the water / steam passage 36 may be small. The passage through which the exhaust gas flows outside the partition wall, that is, the pipe 33, is constituted by the exhaust gas passage 29, and has a large contact area with the exhaust gas.

Next, a gas engine provided with an energy recovery device incorporating the structure of the heat exchanger will be described with reference to FIGS. FIG. 4 is a schematic explanatory view showing a gas engine provided with an energy recovery device incorporating the heat exchange device of FIG. 3, FIG. 5 is a schematic explanatory view showing a turbocharger in the energy recovery device of FIG. 4, and FIG. FIG. 5 is a schematic explanatory view showing a steam turbine in the energy recovery device of FIG. 4.

The heat exchanger constituting the energy recovery device is
It is provided downstream of the turbocharger 3 provided in an exhaust passage 8 that discharges exhaust gas from the engine 1. Further, the energy recovery device drives the steam turbine 5 by high-temperature steam generated by the heat exchange device, and
Is applied to generate electric power by the generator 20 provided in. In addition, the structure of the heat exchanger according to the present invention is applied to the second-stage heat exchanger 6 provided downstream of the first-stage heat exchanger 4 in the heat exchange device, and the second-stage heat exchanger 6 The water is heated by the exhaust gas passing through the first-stage heat exchanger 4 to be converted into steam, and the steam is sent to the first-stage heat exchanger 4.

The gas engine 1 equipped with this energy recovery device is a multi-cylinder or single-cylinder operated by sequentially repeating four strokes of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. It is preferable to apply the present invention to the engine 1 having a small load fluctuation in the generation system.

The gas engine 1 provided with this energy recovery device is a single-cylinder or multi-cylinder engine which uses a gas such as natural gas as a fuel and can be applied to, for example, a cogeneration system, and has a combustion chamber formed in a cylinder. The sub-chamber gas engine is constituted by a main chamber 1A and a sub-chamber 1B formed in a cylinder head 30 communicating with the main chamber 1A through a communication port. The gas engine 1 comprises a main chamber 1 of a combustion chamber.
Exhaust manifold 44 to exhaust exhaust gas from A
And an intake manifold 45 for supplying intake air to the main chamber 1A through the intake passage 10. Intake passage 10
Is supplied to the main chamber 1A of each cylinder through the intake manifold 45, and the exhaust gas from each main chamber 1A is collected by the exhaust manifold 44 and discharged to the exhaust passage 8. The natural gas supplied to the sub-chamber 1B is supplied to each sub-chamber 1B of the combustion chamber through the fuel supply passage 9 by the operation of the fuel pressurizing pump 13.

In this embodiment, the main chamber 1A and the sub-chamber 1B of the combustion chamber of the gas engine 1 are formed in a heat shielding structure by a ceramic member, a heat shielding layer and the like. The gas engine 1 includes a sub-chamber 1B formed in a cylinder head 30 to which reformed fuel is supplied. The sub-chamber 1B is configured to communicate with the main chamber 1A by opening a communication port by a control valve 31. ing. Compressed air from the compressor 16 of the turbocharger 3 is supplied to the main chamber 1A through the intake passage 10, and a fuel valve 32 is provided in the sub-chamber 1B. Gas fuel is supplied from the supply path 9 to the sub chamber 1B.

The gas engine 1 is provided with a heat exchanger incorporating the heat exchanger of FIG. The gas engine 1 includes a fuel tank 11 containing a natural gas fuel mainly composed of CH ₄ , a fuel pressurizing pump 13 for supplying gas fuel to the sub-chamber 1B of the combustion chamber, and an exhaust passage 8 downstream of the turbocharger 3. First heat exchanger 4 provided in the first heat exchanger 4
Steam turbine 5 driven by the steam generated in the first heat exchanger 4 and the steam turbine 5
And a second heat exchanger 6 that converts fluid (low-temperature steam and water) discharged from the steam into steam and supplies the steam to the first heat exchanger 4.

In the gas engine 1, the main chamber 1A and the sub-chamber 1B of the combustion chamber are constituted by a ceramic member and a heat-insulating layer in a heat-shielding structure.
Exhaust gas discharged through 4 is about 900 ° C to 800 ° C
Hot gas. Therefore, the gas engine 1 is configured to recover the heat energy of the exhaust gas by the turbocharger 3, the first heat exchanger 4, and the second heat exchanger 6.

As shown in FIG. 5, the turbocharger 3 is a turbine 15 driven by exhaust gas, connected to the turbine 15 by a shaft 18 and provided with a turbine 1.
5 comprises a compressor 16 driven by the motor 5 and an alternator or generator 17 provided for the shaft 18. The compressor 16 is driven by the turbine 15 to compress air to form compressed air, and supply the compressed air from the intake manifold 45 to the main chamber 1A of each cylinder through the intake passage 10. The generator 17 is the turbine 1
The exhaust gas energy can be collected as electric energy by extracting the rotational force of No. 5 as electric power.

The first heat exchanger 4 is disposed in a steam passage 35 composed of a ceramic porous member through which the steam heated by the second stage heat exchanger 6 disposed in the first casing 2 flows. And a plurality of exhaust gas passages 28 through which the exhaust gas flows. In addition, the second-stage heat exchanger 6
Are located around the water / steam passage 36 and the water / steam passage 36 that can store water, and are disposed in the second casing 7 provided adjacent to the first casing 2. And an exhaust gas passage 29 through which the exhaust gas flows.

As shown in FIG. 6, the steam turbine 5 includes a turbine 19 driven by steam generated in the first heat exchanger 4, a turbine 24 driven by steam discharged from the turbine 19, and a turbine 19. 24 is provided with a generator 20 provided for a shaft 21 connected thereto. Therefore, the steam energy is transferred to the turbine 19,
24, and its rotational force is recovered as electric power by the generator 20.

The second heat exchanger 6 provided in the exhaust passage 8
Is a gas-liquid heat exchanger which generates steam by the exhaust gas energy, and the steam is sent to the first heat exchanger 4 through the steam passage 41. The steam that drives the steam turbine 5 becomes a fluid of water and low-temperature steam, and becomes a fluid passage 27.
The water is discharged to the condenser 14 through the condenser 14, becomes high-temperature water, and is sent again by the water pump 12 to the second heat exchanger 6 through the water passage 26. Further, the exhaust gas that has passed through the second heat exchanger 6 is discharged to the outside as a low-temperature exhaust gas (for example, about 200 ° C.) in a state where heat energy is almost recovered.

The gas engine provided with this energy recovery device is configured as described above and operates as follows.

With the control valve 31 closed, air from the compressor 16 of the turbocharger 3 is supplied from the intake manifold 44 to the main chamber 1A through the intake passage 10 by opening an intake valve (not shown). The air in the main chamber 1A is compressed in the compression stroke with the control valve 31 closed.
On the other hand, when the control valve 31 is closed, the fuel valve 32 is opened, and the operation of the fuel pressurizing pump 13 causes natural gas fuel to flow from the fuel tank 11 through the gas fuel supply passage 9 to the sub-chamber 1B.
Supplied to The control valve 31 is opened near the top dead center of the compression stroke, the compressed air in the main chamber 1A flows into the sub-chamber 1B, the reformed fuel mixes with the compressed air, ignites, and shifts to the expansion stroke. To work.

In the exhaust stroke, the exhaust gas in the main chamber 1A and the sub-chamber 1B is sent to the turbocharger 3 through the exhaust passage 8. In the turbocharger 3, the turbine 15
, And its rotational force is converted into electric energy by a generator 17 and also drives a compressor 16. The electric power obtained by the generator 17 is stored in a battery or consumed for driving auxiliary equipment. Further, the compressor 16 has a function of supercharging air into the combustion chamber through the intake passage 10. The exhaust gas passing through the turbine 15 of the turbocharger 3 is sent to the first heat exchanger 4 through the exhaust passage 8.

The exhaust gas sent to the first heat exchanger 4 passes through the exhaust gas passage 28, and is then sent to the second heat exchanger 6 through the exhaust gas 8. When passing through the exhaust gas passage 28, the exhaust gas exchanges heat with the steam sent from the second heat exchanger 6 through the steam passage 41 to the steam passage 35, and is heated to a high temperature. The steam heated to a high temperature in the first heat exchanger 4 is sent to the steam turbine 5 through the high-temperature steam passage 25 and drives the turbines 19 and 24. The generator 20 generates electric power by driving the turbines 19 and 24. The electric power generated by the generator 20 is stored in a battery or consumed for driving auxiliary equipment. After driving the steam turbine 5, the high-temperature steam is converted into a fluid composed of low-temperature steam and water, and the fluid is sent to the condenser 14 through the fluid passage 27 to become water. It is sent to the water / steam passage 36 of the second heat exchanger 6 through 26.

The exhaust gas sent from the first heat exchanger 4 to the second heat exchanger 6 is supplied to the exhaust gas passage 2 of the second heat exchanger 6.
The gas is sent out to the exhaust passage 8 through 9. When passing through the exhaust gas passage 29, the exhaust gas exchanges heat with water passing through the water / steam passage 36 to be converted into steam. The exhaust gas sent to the exhaust passage 8 is supplied to the turbocharger 3, the first heat exchanger 4
The heat energy is recovered by the second heat exchanger 6, and the temperature is reduced to, for example, about 200 ° C.

[0044]

Since the structure of the heat exchanger according to the present invention is constructed as described above, the heat exchange efficiency can be greatly improved, the strength can be increased, and the durability is high. When the structure of the heat exchanger is incorporated into a two-stage heat exchanger, the heat energy of the exhaust gas is exchanged with water by the first and second heat exchangers, and the water is removed. It can be converted to high-temperature steam, and the energy of the high-temperature steam is effectively recovered as electric energy in a steam turbine.

In the gas engine, the turbocharger is driven by the heat energy of the exhaust gas, and the heat energy is recovered by the compressor and the generator, and as described above, the exhaust gas discharged from the turbocharger turbine is exhausted. Then, steam is generated in the first heat exchanger and the second heat exchanger, and the steam is driven by the steam, and the steam turbine is driven to be recovered as electric power by the generator. Therefore, in the gas engine, since the exhaust heat energy is recovered by the heat exchange device instead of the conventional energy recovery turbine, there is no loss due to the back pressure unlike the conventional one, and the exhaust heat energy is effectively recovered. As a result, fuel efficiency can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a structure of a heat exchanger according to the present invention.

FIG. 2 is a cross-sectional view of the heat exchanger of FIG. 1 taken along line AA.

FIG. 3 is an explanatory diagram showing one embodiment of a heat exchange device incorporating the heat exchanger of FIG. 1;

FIG. 4 is an explanatory view showing a gas engine provided with an energy recovery device incorporating the heat exchanger of FIG. 1;

FIG. 5 is an explanatory diagram showing a turbocharger including a generator incorporated in the gas engine of FIG. 4;

FIG. 6 is an explanatory view showing a steam turbine incorporated in the gas engine of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas engine 1A Main chamber 1B Subchamber 2,7 Casing 3 Turbocharger 4 First heat exchanger 5 Steam turbine 6 Second heat exchanger 8 Exhaust passage 11 Fuel tank 13 Fuel pressurizing pump 28,29 Exhaust gas passage 33 Wall Body (partition wall) 35 Steam passage 36 Water / steam passage 38, 42 Porous ceramic member 39 Reinforcement member

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02B 37/00 302 F02B 37/00 302B 43/00 43/00 A F02G 5/02 F02G 5/02 B F28D 7/10 F28D 7 / 10 Z

Claims (13)

[Claims] 1. A casing incorporated in an exhaust gas passage, a partition disposed in the casing, a low-temperature side passage formed in the partition, through which a low-temperature fluid flows, and in the casing outside the partition. In the structure of a heat exchanger for heating a fluid with an exhaust gas comprising a formed high-temperature passage through which a high-temperature gas flows, a ceramic porous member is disposed in the low-temperature passage and the high-temperature passage, and the ceramic porous member is disposed. A structure of a heat exchanger, wherein a reinforcing member in which a fibrous material is mixed with ceramics is disposed in the quality member. 2. The heat exchanger structure according to claim 1, wherein the reinforcing member comprises a plurality of fins extending radially from the inner and outer surfaces of the partition into the ceramic porous member. 3. The heat exchanger structure according to claim 1, wherein the reinforcing member comprises a core made of silicon carbide fiber or carbon fiber, and an outer part made of silicon carbide. 4. A reinforcing member constituting the high-temperature side passage through which exhaust gas flows, a core portion formed of a non-woven fabric of carbon fiber, a slurry in which a Si powder and a carbon powder are mixed penetrate into the core portion, and The surface of the core is coated with the slurry, which is sintered at about 1500 ° C. to 1700 ° C. in N ₂ gas, and the carbon fibers of the core are converted to Si _{3 of} the outer part where the slurry is converted. structure of the heat exchanger according to claim 1, which is formed on the coated structure N _4. 5. The heat exchanger according to claim 1, wherein the reinforcing member constituting the high-temperature side passage through which the exhaust gas flows is made of a composite material containing carbon fibers coated with silicon carbide and silicon nitride. Vessel structure. 6. The heat exchanger structure according to claim 1, wherein the ceramic porous member is made of silicon nitride, and the surface of the silicon nitride is coated with silicon carbide. 7. The ceramic porous member disposed in the low temperature side passage through which water and steam flow, comprises silicon carbide,
The structure of the heat exchanger according to claim 1, wherein the heat exchanger is made of silicon nitride coated with silicon carbide. 8. The heat exchanger structure according to claim 1, wherein said ceramic porous member disposed in said high-temperature side passage through which exhaust gas flows is made of silicon nitride. 9. The partition wall on the side where exhaust gas flows, the partition wall core formed of a non-woven fabric of carbon fiber, a slurry in which Si powder and carbon powder are mixed penetrate into the partition core, and the partition core is Is coated with the slurry, and the slurry is coated with N ₂ at a temperature of about 1500 ° C. to 1700 ° C.
The structure of the heat exchanger according to claim 1, wherein the structure is sintered in a gas, and the carbon fibers are formed in a structure coated with the converted silicon nitride of the slurry. 10. The present invention is applied to a heat exchange device disposed in an exhaust passage from which exhaust gas of an engine is exhausted, wherein the heat exchange device converts water into steam with the heat energy of the exhaust gas and heats the water. The structure of the heat exchanger according to claim 1. 11. The heat exchanger according to claim 10, wherein the heat exchange device is provided downstream of a turbocharger provided in the exhaust passage for discharging exhaust gas from the engine. Construction. 12. The steam turbine according to claim 10, wherein the steam turbine is driven by high-temperature steam generated by the heat exchange device, and the steam turbine is applied to an energy recovery device that generates power by a generator provided in the steam turbine. Heat exchanger structure. 13. The heat exchanger according to claim 1, wherein the second heat exchanger is provided downstream of the first heat exchanger in the heat exchanger, and the second heat exchanger passes through the first heat exchanger. The structure of a heat exchanger according to claim 10, comprising heating the water with the exhaust gas to convert the water into steam, and sending the steam to the first-stage heat exchanger.