DE112011100603T5 - Exhaust heat recovery system, energy supply system and exhaust heat recovery process - Google Patents

Abstract

The object of the present invention is to increase the efficiency of useful energy recovery as compared with an exhaust heat recovery process by the generation of water vapor. To achieve this object, the present invention provides an embodiment having a heat conduction path (1) that conducts the exhaust heat, and a high-boiling-point heat medium steam generator (2) that receives a high-boiling-point heat medium vapor (R2) through heat exchange between the exhaust heat passed through the heat conduction path (1) and the high boiling point heat medium (R1) having a higher evaporation temperature than water (R3).

Description

Technical area

The present invention relates to an exhaust heat recovery system, a power supply system, and an exhaust heat recovery method.

The priority of Japanese Patent Application No. 2010-034776 is claimed, filed on 19 February 2010, the content of which is hereby incorporated by reference.

State of the art

As with a variety of systems, such as combined heat and power systems, power generation systems such. B. thermal power plants, as well as steam generating devices, such. As boilers, the energy efficiency of the device is improved by the heat of the combustion exhaust gas is recovered (exhaust heat recovery). The below-mentioned Patent Document 1 discloses an example of a combined heat and power (CHP) apparatus using exhaust heat recovery boilers. The below-mentioned Patent Document 2 discloses an example of a vertical natural circulation heat recovery boiler of the multiple press design. The below-mentioned Patent Document 3 discloses an example of a combined cycle power plant combining heat recovery boilers. The below-mentioned Patent Document 4 discloses an example of a multiple-pressure heat recovery boiler.

Combined heat and power systems are known as power generation systems that derive thermal energy used for heating / cooling, hot water supply, and the like by utilizing the exhaust heat generated in power generation. In such combined heat and power systems, the heat recovery is usually performed by generating water vapor by means of the heat recovery boilers as described in Patent Document 1.

Further, Patent Document 5 discloses a heat recovery device which recovers waste heat (exhaust heat) from a comparatively low temperature heat source in the range of 200 ° C by using a first working medium and a second working medium having different boiling points. This heat recovery device uses water as the first working medium and freon or a freon substitute having a lower boiling point than water, especially chlorofluorocarbon, hydrochlorofluorocarbon, hydrofluorocarbon, ammonia, ammonia water or the like as the second working medium, thereby increasing the efficiency of power generation by using larger amounts be recovered from heat from a heat source with a comparatively low temperature.

List of citations

Patent documents

• Patent Document 1: Japanese Laid-Open Publication, First Publication No. JP 2003-021302 Patent Document 2: Japanese Laid-Open Publication, First Publication No. JP 2000-346303
• Patent Document 3: Japanese Laid-Open Publication, First Publication No. JP 2002-021583
• Patent Document 4: Japanese Patent Publication No. JP 2753169
• Patent Document 5: Japanese Laid-Open Publication, First Publication No. JP 2008-267341

Summary of the invention

Technical problem

With regard to the aforementioned conventional exhaust heat recovery method with the generation of water vapor from water, the efficiency of recovering the available energy that can be obtained from the energy contained in the exhaust gas (exhaust heat) is not necessarily sufficient and further improvements in the energy recovery efficiency are expected. In particular, with regard to the heat recovery of exhaust gas heat high temperature, which far exceeds the water boiling temperature, z. B. Exhaust gas of 300 ° C are limits for the evaporation temperature during the evaporation of water. As a result, the current situation is such that the available efficiency of energy recovery of conventional exhaust heat recovery processes is insufficient, causing the loss of a large amount of available energy. The above-mentioned available energy is a thermodynamic concept, also called "exergy", commonly known as the energy extracted from a system as a mechanical work. The available energy in the present Invention means energy (an amount of work) that can be recovered as mechanical work (dynamic force of electricity or the like) from the total energy having the exhaust gas.

Further, the conventional exhaust heat recovery method using water (as a first working medium) and a second working liquid having a lower boiling point than water is provided for heat recovery from a heat source having a comparatively low temperature in the range of 200 ° C. Since the temperature of the vapor obtained by evaporation of the second working liquid is lower than the temperature of the vapor obtained by the evaporation of the first working liquid, the recovery of the available energy from exhaust heat with a comparatively high temperature is almost impossible ,

The object of the present invention is to improve the efficiency of recovery of the available energy via an exhaust heat recovery process, which gains the available energy by evaporation of water, and an exhaust heat recovery process, the available energy by means of evaporation of water and a liquid with a lower boiling point than water.

Another object of the present invention is to provide a power system having a higher efficiency, a higher power saving rate, and a higher CO ₂ savings than the prior art.

Solution of the task

In order to achieve the above objects and as a means for solving an exhaust heat recovery system, the present invention provides: a heat conduction path which conducts exhaust heat, and a high-boiling-point heat medium steam generator which generates a high-boiling-point heat medium vapor by means of a heat exchange the high-boiling-point heat medium having a higher evaporation temperature than water and the exhaust gas heat passed through the heat conduction path.

Advantageous Effects of the Invention

According to the present invention, instead of generating water vapor by the evaporation of water or in addition to the generation of water vapor by the evaporation of water, a vapor of a high-boiling-point heat medium is generated by evaporating a high boiling point heat medium having a higher boiling point Evaporation temperature than water (that is, a lower vapor pressure than water) has. As a result, it is possible to improve the efficiency of recovery of the available energy over that of the conventional exhaust heat recovery methods which generate water vapor by evaporation of water.

Brief description of the drawings:

1 Fig. 10 is a system block diagram showing the functional construction of a power supply system P1 according to a first embodiment of the present invention.

2 FIG. 14 is a characteristic diagram showing the heat exchange conditions of each heat medium of a heat recovery unit K1 of the power supply system P1 of the first embodiment of the present invention in relation to the exchanged heat amount (horizontal axis) and the temperature (vertical axis).

3 Fig. 10 is a system block diagram showing the functional construction of a power supply system P2 according to a second embodiment of the present invention.

4 Fig. 14 is a characteristic diagram showing the heat exchange conditions of each heat medium of a heat recovery unit K2 of the power supply system P2 of the second embodiment of the present invention in relation to the exchanged heat quantity (horizontal axis) and the temperature (vertical axis).

5 Fig. 13 is a characteristic diagram showing the energy saving rates when ethylene glycol or diethylene glycol is used as the high boiling point heat medium R1 in the second embodiment of the present invention.

6 Fig. 12 is a characteristic diagram showing the CO ₂ savings rates when ethylene glycol or diethylene glycol is used as the high boiling point heat medium R1 in the second embodiment of the present invention.

7 Fig. 10 is a system block diagram showing the functional configuration of a power supply system P3 according to a third embodiment of the present invention.

8th FIG. 14 is a characteristic diagram showing the heat exchange conditions of each heat medium of a heat recovery unit K3 of the power supply system P3 of the third embodiment of the present invention in relation to the exchanged heat quantity (horizontal axis) and the temperature (vertical axis).

Description of the embodiments

Embodiments of the present invention will be described with reference to the drawings.

First embodiment

First, a first embodiment of the present invention will be described with reference to FIGS 1 and 2 described.

Like in the 1 is shown, a power supply system P1 of the first Ausführüngsbeispiels an exhaust pipe 1 , a steam generator 2 the high boiling point heat medium, a steam generator 3 , a preheater 4 the high boiling point heat medium, a water pre-heater 5 , a superheater 6 the vapor of the high boiling point heat medium, a steam superheater 7 , a supply pump 8th the high boiling point heat medium, a water feed pump 9 , a steam turbine power generator 10 the high boiling point heat medium, a vapor compressor 11 the high boiling point heat medium, a liquid collection tank 12 , a steam turbine generator 13 , a steam compressor 14 , a water collection tank 15 and a cooling water supply device 16 on. In the 1 "G" denotes a high-temperature exhaust gas, R1 denotes a high-boiling-point heat medium, R2 denotes a steam of the high-boiling-point heat medium, R3 denotes water, and R4 denotes water vapor.

Among these corresponding components form the exhaust pipe 1 , the steam generator 2 the high boiling point heat medium, the steam generator 3 , the preheater 4 the high boiling point heat medium, the water pre-heater 5 , the superheater 6 the vapor of the high boiling point heat medium and the steam superheater 7 an exhaust heat recovery unit K1 which recovers exhaust heat from the exhaust gas G of high temperature. The exhaust heat recovery unit K1 corresponds to an exhaust heat recovery system of the present invention.

Among the previous components form the supply pump 8th the high boiling point heat medium, the water feed pump 9 , the steam turbine generator 10 the high boiling point heat medium, the steam compressor 11 the high boiling point heat medium, the liquid collection tank 12 , the steam turbine generator 13 , the steam compressor 14 , the water collection tank 15 and the cooling water supply device 16 a power generation unit W. The power generation unit W is a dynamic force generator that generates a power (dynamic force) by the steam R2 of the high-boiling-point heat medium and the steam R4 as working fluids by supplying the high-boiling-point heat medium R1 to the exhaust heat recovery unit K1 supplying the water R3, which are the liquid heat medium, and obtaining, from the exhaust heat recovery unit K1, the vapor R2 of the high-boiling-point heat medium and the water vapor R4 by evaporating these liquid media from the aforementioned exhaust heat. The power supply system P1 is constituted of the exhaust heat recovery unit K1 and the power generation unit W (dynamic force generator), and is a power supply system which generates power which is a dynamic force mode by means of the steam R2 of the high-boiling heat medium and the water vapor R4, which were generated by recovering the exhaust heat from the exhaust gas G high temperature in the exhaust heat recovery unit K1.

In this type of power supply system P1 is the exhaust pipe 1 a heat conduction path through which the exhaust gas G of high temperature flows, which is supplied from the outside. The exhaust gas G high temperature is a high-temperature exhaust gas (ie, a gas having exhaust heat), which z. B. is ejected from a combustion chamber and which has a temperature of z. B. 300 ° C or more, which far exceeds the temperature required for the evaporation of the water R3. The exhaust gas G of high temperature circulates from the left side (upstream side) to the right side (downstream side) of the exhaust pipe 1 , like in the 1 is shown.

The steam generator 2 of the high-boiling-point heat medium is in a middle position in the exhaust pipe 1 , like in the 1 and an apparatus which generates the vapor R2 of the high-boiling-point heat medium at a high pressure by means of heat exchange between the high-boiling-point heat medium R1 and the high-temperature exhaust gas G. The steam generator 3 is downstream to the steam generator 2 the high boiling point heat medium in the exhaust pipe 1 , like in the 1 shown, provided and is a device (combustion chamber), which generates the high pressure water vapor R4 by means of heat exchange between the water R3 and the exhaust gas G of high temperature.

Here, the high boiling point heat medium R1 is a liquid having a higher evaporation temperature than the water R3 (ie, having a lower evaporation pressure than the water R3) and which is a chemically stable compound in heat exchange with the exhaust gas G of high temperature. As examples, ethylene glycol (empirical formula: C ₂ H ₆ O ₂ ), diethylene glycol (empirical formula: C ₂ H ₁₀ O ₃ ), propylene glycol (empirical formula: C ₃ H ₈ O ₂ ), triethylene glycol (empirical formula: C ₆ H ₁₄ O ₄ ), Propylene carbonate (empirical formula: C ₄ H ₅ O ₃ ), propylene-ethylene glycol (empirical formula: C ₃ H ₈ O ₂ ), formanide (empirical formula: CH ₃ NO) and so on.

Like in the 1 is shown is the preheater 4 the high boiling point heat medium between the steam generator 2 the high boiling point heat medium and the steam generator 3 in the exhaust pipe 1 intended. The preheater 4 of the high-boiling-point heat medium is a type of heat exchanger which is capable of preheating the high-boiling-point heat medium R1 to e.g. Example, a temperature that is just below the boiling point, by means of heat exchange between the exhaust gas G high temperature and the heating medium R1 with high boiling point, which from the supply pump 8th of the high-boiling-point heat medium, and the high-boiling-point preheated heat medium R1 to the steam generator 2 of the high boiling point heat medium.

Like in the 1 shown is the water pre-heater 5 downstream of the steam generator 3 in the exhaust pipe 1 intended. The water pre-heater 5 is a kind of heat exchanger, which preheating the water R3 to z. B. a temperature which is just below the boiling point, by means of heat exchange between the exhaust gas G high temperature and the water R3, which from the water supply pump 9 is fed, and the preheated water R3 to the steam generator 3 and to the steam compressor 11 of the high boiling point heat medium.

Like in the 1 shown is the superheater 6 the vapor of the high boiling point heat medium on the upstream side of the steam generator 2 the high boiling point heat medium in the exhaust pipe 1 intended. The superheater 6 The vapor of the high boiling point heat medium is a type of heat exchanger which receives the vapor R2 of the high boiling point heat medium coming from the steam generator 2 of the high-boiling-point heat medium, overheated by the high-temperature exhaust gas G by heat exchange, and superheated steam R2 of the high-boiling-point heat medium to the steam turbine power generator 10 of the high boiling point heat medium.

Like in the 1 is shown is the water vapor superheater 7 inlet side to the superheater 6 the high boiling point heat medium in the exhaust pipe 1 intended. The steam superheater 7 is a kind of heat exchanger, which is the water vapor R4 from the steam generator 3 and the vapor compressor 11 the heat medium is supplied with a high boiling point, superheated by means of heat exchange with the exhaust gas G high temperature and superheated steam R4 to the steam turbine generator 13 dissipates.

The supply pump 8th of the high boiling point heat medium is a pump containing the high boiling point heat medium R1 from the liquid collection tank 12 and it's the preheater 4 of the high boiling point heat medium. The water supply pump 9 Pumps the water R3 from the water collection tank 15 and leads it to the water pre-heater 5 to. The steam turbine generator 10 of the high boiling point heat medium is a turbine power plant that generates power by driving a power generator that is axially coupled to a turbine by rotating the turbine with high boiling point, high pressure, high pressure steam R2 of the steam generator 2 of the high boiling point heat medium via the superheater 6 the steam of the high-boiling-point heat medium is supplied.

The steam compressor 11 of the high-boiling-point heat medium is a kind of heat exchanger which densifies (liquefies) the high-boiling-point heat medium vapor R2 to bring it back to the high-boiling-point heat medium R1 and which evaporates the water R3 to produce the high-pressure steam R4 , and it does so by means of heat exchange between the steam R2 of the high-boiling-point heat medium coming from steam turbine power generators 10 of the high boiling point heat medium after power recovery is removed, and the R3 water is removed by the water pre-heater 5 is supplied. The steam compressor 11 of the high-boiling-point heat medium supplies the recovered high-boiling-point heat medium R1 to the liquid collection tank 12 and leads the water vapor R4, which was generated by means of heat exchange with the steam R2 of the high-boiling-point heat medium, to the water vapor preheater 7 ab ,

The liquid collection tank 12 is a storage tank which temporarily stores the high boiling point heat medium R1 coming from the vapor compressor 11 the heat medium is supplied with a high boiling point. The steam turbine generator 13 is a turbine power plant that generates power by operating a power generator that is axially coupled to a turbine by rotating the turbine with the high pressure water vapor R4 coming from the steam generator 3 and the vapor compressor 11 of the high boiling point heat medium via the steam superheater 7 is supplied.

The steam compressor 14 is a kind of heat exchanger which condenses (liquefies) the water vapor R4 produced by the steam turbine generator 13 is discharged after the power recovery, and this returns to the water R3 by means of heat exchange with cooling water from the cooling water supply device 16 is supplied. The steam compressor 14 returns the returned water R3 to the water collection tank 15 from. The water collection tank 15 is a storage tank which temporarily stores the water R3 coming from the water vapor compressor 14 is supplied. The cooling water supply device 16 is a device which controls the circulating supply of cooling water to the water vapor compressor 14 performs.

Next, the operation of the power supply system P1 of the first embodiment will be described in detail with reference to the characteristic diagram of FIG 2 described.

In the energy supply system 1 are a plurality of heat exchangers, which perform a heat exchange with the exhaust gas G high temperature, in the direction of the flow side to the outlet side in the exhaust pipe 1 that is, in the axial direction in the exhaust pipe 1 , like in the 1 shown, arranged. In particular, among the various heat exchangers is the water vapor superheater 7 at the furthest forward-side position of the exhaust pipe 1 arranged and are the superheater 6 the steam of the high-boiling-point heat medium, the steam generator 2 the heat medium with high boiling point, the preheater 4 the high boiling point heat medium, the steam generator 3 and the water pre-heater 5 arranged in this order to the drain side. Since the exhaust gas G high temperature, passing through the area (heat exchange area) of the exhaust pipe 1 where these heat exchangers are arranged, heat value is withdrawn by each heat exchanger by flowing the heat exchange region from the upstream side to the downstream side, the temperature of the high temperature exhaust gas G is higher toward the upstream side than the heat exchange region (ie, the temperature of Exhaust gas G of high temperature is lower toward the downstream side of the heat exchange region).

On the steam generator 2 the high boiling point heat medium and the steam generator 3 As a result, the high boiling point heat medium R1 in the steam generator 2 of the high-boiling-point heat medium, the heat exchange with the exhaust gas G of a higher temperature than that of the water 3 in the steam generator 3 through, as the steam generator 2 of the high boiling point heat medium continues toward the upstream side of the heat exchange area as the steam generator 3 is arranged

2 FIG. 14 is a characteristic diagram showing the heat exchange conditions of the respective heat mediums (ie, the high temperature exhaust gas, the high boiling point heating medium R1, the high boiling point heating medium steam R2, the water R3, and the water vapor R3) in the above-mentioned heat exchange region in FIG Relationship with the exchanged amount of heat (horizontal axis) and the temperature (vertical axis) shows. In 2 Fig. 11 shows a line Lg shown by a solid line showing changes in the conditions of the exhaust gas G of high temperature, a broken line Ls shown by a broken line, the changes in the conditions of the water R3 or the water vapor R4 11 and 11, a broken line Lk shown by a broken line shows changes in conditions of the high-boiling-point heat medium R1 or the high-boiling-point heat medium vapor R2.

There, as in the 2 2, the high temperature exhaust gas G is taken out of each heat exchanger, the relationship of the high temperature exhaust gas G between the heat exchanged amount and the temperature is approximately a proportional relationship, as shown by the line Lg. That is, in the characteristic diagram, an exchanged heat transmission point A1 corresponds to the most downstream side point of the heat exchange region, and an exchanged heat transmission point C3 corresponds to the most upstream side point of the heat exchange region. With respect to the heat exchange properties, the respective heat exchangers are disposed between the exchanged heat transfer point A1 (the most downstream point) and the exchanged heat transfer point C3 (the most upstream point), and conduct the heat exchange with the exhaust gas G of high temperature as the heat source.

When the heat exchange of the water R3 and the water vapor R4 with the high temperature exhaust gas G is considered, that is, the heat exchange in the water pre-heater 5 , the steam generator 3 and the steam superheater 7 , the water is R3 after preheating by the water pre-heater 5 distributed and the steam generator 3 and the vapor compressor 11 of the high boiling point heat medium. As a result of the heat exchange with the exhaust gas G of high temperature in the steam generator 3 When a part of the water R3 becomes the water vapor R4 and the remaining water R3 becomes the water vapor R4 as a result of the heat exchange with the vapor R2 of the high-boiling-point heat medium in the vapor compressor 11 the heat medium with high boiling point.

The range of the exchanged heat transfer points A1 to A2 in the broken line Ls corresponds to the temperature rise (the pressure rise) passing through the water pre-heater 5 is caused to a temperature just below the boiling point of the water R3, and the range of the exchanged heat transfer points A2 to B1 in the broken line Ls corresponds to the evaporation of a part of the water R3 (ie, the generation of the water vapor R4) by the steam generator 3 , Further, the area of the exchanged heat transfer points B1 to D in the broken line Ls corresponds to the evaporation of the remaining part of the water R3 (ie, the generation of the water vapor R4) by means of the vapor compressor 11 the heat medium with high boiling point. That is, the water R3, which comes from the water pre-heater 5 was preheated to a temperature only slightly below the boiling point, the water vapor R4 through the exchanged amounts of heat along the exchanged. Heat transfer points A2 to D is.

The steam R4 coming from the steam generator 3 is discharged, and the water vapor R4 coming from the vapor compressor 11 of the high-boiling-point heat medium, are mixed and the steam superheater 7 fed. That is, the water vapor R4 coming from the steam generator 3 and the vapor compressor 11 of the high boiling point heat medium which becomes water vapor R4 (superheated steam) which exceeds the boiling point by means of heat exchange with the high temperature exhaust gas G in the steam superheater 7 is overheated. The range of the exchanged heat transfer points C2 to C3 in the broken line Ls is the superheated region of the water vapor R4 due to the steam superheater 7 , The temperature of the exchanged heat transfer point C2 corresponding to the superheat start point of the water vapor R4 is equal to the temperature of the exchanged heat transfer point D (evaporation end point) of the water vapor R4, as shown in the drawing.

On the other hand, when the heat exchange of the high-boiling-point heat medium R1 and the high-boiling-temperature heat medium R2 with the high-temperature exhaust gas G, that is, the heat exchange in the preheater 4 the heat medium with high boiling point, the steam generator 2 the heat medium with high boiling point and the superheater 6 of the vapor of the high-boiling-point heat medium, the high-boiling-point heat medium R1 becomes heat-exchanged with the high-temperature exhaust gas G in the preheater 4 of the high-boiling-point heat medium is preheated to a temperature only slightly lower than the boiling point, and subsequently becomes the steam generator 2 of the high-boiling-point heat medium to become the high-boiling-point heat medium vapor R2. The range of the exchanged heat transfer points B1 to B2 in the broken line Ls corresponds to the temperature rise (the pressure rise) passing through the preheater 4 of the high-boiling-point heat medium up to a temperature just below the boiling point of the high-boiling-point heat medium G and. the range of the exchanged heat transfer points B2 to C1 in the broken line Lk corresponds to the vaporization of the high boiling point heat medium R1 (ie, the generation of the high boiling point heat medium vapor R2) by the steam generator 2 the heat medium with high boiling point.

The vapor R2 of the high boiling point heat medium coming from the steam generator 2 of the high-boiling-point heat medium, the vapor R2 of the high-boiling-point heat medium (superheated high-boiling-point heat medium vapor) becomes higher than the boiling point by heat exchange with the high-temperature exhaust gas G in the superheater 6 the vapor of the high-boiling-point heat medium is overheated. The area of the exchanged heat transfer points C1 to C2 in the broken line Lk is the superheated area of the vapor R2 of the high-boiling-point heat medium due to the superheater 6 of steam high-boiling-point heat medium.

Here, the heat medium R1 with high boiling point, which is the preheater 4 the high boiling point heat medium with the supply pump 8th the high boiling point heat medium is supplied in the vapor compressor 11 of the high boiling point heat medium by means of heat exchange between the vapor R2 of the high boiling point heat medium discharged from the Steam turbine power generator 10 of the high boiling point heat medium, and the water R3 coming from the water pre-heater 5 is discharged, liquefied. The heat exchange in the vapor compressor 11 of the high boiling point heat medium corresponds to the range of exchanged heat transfer points D to B1 in the broken line Lk.

In the region of the exchanged heat transfer points D to B1 in the broken line Lk, the heat from the heat exchange initially acts on the vapor R2 of the high-boiling-point heat medium as self-heat, with the result that the temperature of the high-boiling-point heat medium vapor R2 gradually increases decreases, after which the heat acts on the vapor R2 of the high-boiling-point heat medium as the heat of conversion, with the result that the vapor R2 of the high-boiling-point heat medium is condensed in a constant quantity while keeping the temperature at a constant value. This change in the conditions of the steam R2 of the high-boiling-point heat medium relates to the case where the high-boiling-point heat medium R1 is ethylene glycol (empirical formula: C ₂ H ₆ O ₂ ) and changes in the manner of the high-boiling-point heat medium R1.

Specifically, in the exhaust heat recovery unit K1 of the power supply system P1, the water R3 of a condition Ys corresponding to the exchanged heat transfer point A1, the water vapor R2 of a condition Xs corresponding to a temperature corresponding to the exchanged heat transfer point C3 in the broken line Lk by means of heat exchange the high-temperature exhaust gas G from a low-temperature comparison in the water pre-heater 5 , and the steam generator 3 and by heat exchange with the vapor R2 of the high-boiling-point heat medium (high-boiling-point heat medium vapor) and by means of heat exchange with the high-temperature exhaust gas G in the steam superheater 7 is overheated. The steam R4 of the condition Xs is then the steam turbine generator 13 is supplied as a source of dynamic force and releases energy, after which it is cooled, compressed and brought back to the water R3 of condition Ys, which corresponds to the exchanged heat transfer point A1.

Specifically, in the exhaust heat recovery unit K1, the high boiling point heat medium R1 of a condition Yk corresponding to the exchanged heat transfer point D, the high boiling point heat medium vapor R2 of a condition Xk which is at a temperature corresponding to the exchanged heat transfer point C2 in the broken line Lk corresponds to, by means of heat exchange with the exhaust gas G high temperature of compared high temperature in the preheater 4 the heat medium with high boiling point, the steam generator 2 the heat medium with high boiling point and the superheater 6 the heating medium of high boiling point is overheated. The vapor R2 of the high boiling point heat medium of condition Xk is then sent to the steam turbine generator 10 of the high-boiling-point heat medium is supplied as a source of dynamic force, and gives off energy, thereby being returned to the high-boiling-point heat medium R1 of the condition YL corresponding to the exchanged heat transfer point D.

After the exhaust heat recovery unit K1, in addition to the heat recovery by the evaporation of the water R3 by the heat exchange with the high-temperature exhaust gas G to convert it into steam R4, heat recovery is also performed by using the high boiling point heat medium R1 having a higher evaporation temperature than the water R3 (that is, a lower evaporation pressure than the water R3) evaporates by means of heat exchange with the high-temperature exhaust gas G to convert it to the vapor R2 of the high-boiling-point heat medium, thereby improving the recovery efficiency of the heat medium available energy compared to the conventional exhaust heat recovery method is made possible.

In particular, it is possible to obtain a Rankine process which obtains a dynamic force from the enthalpy difference of the condition Xk (gas phase) and the condition VL (gas phase or mixed gas liquid phase) by using the heat medium R1 having a high boiling point. With respect to a low-boiling-point heat medium (conventional freon or freon substitute) having a lower boiling point than the water R3, the generation of a dynamic force by a Rankine process is not possible because the high-temperature zone exceeds the critical point. That is, the exhaust heat recovery unit K1 corresponding to the use of a high boiling point heat medium G enables efficient recovery of the available energy in the high temperature zone, which is not possible with a low boiling point heat medium.

In addition, since after the exhaust heat recovery unit K1, the vapor R2 of the high-boiling-point heat medium by means of the superheater 6 the steam of the high-boiling-point heat medium is superheated, and there the steam R4 by means of the steam superheater 7 is overheated, the heat recovery efficiency in the Compared to the conventional heat recovery process can be further improved.

Second embodiment

Next, a second embodiment will be described with reference to FIGS 3 and 4 described.

In the 3 The components which are the same as those of the power supply system P1 of the first embodiment are given the same reference numerals.

The power supply system P2 of the second embodiment includes an exhaust heat recovery unit K2 and a power generation / steam output unit W2. Like in the 3 is shown, the power supply system P2 has a structure which the steam superheater 7 , the steam turbine generator 13 , the water vapor compressor 14 , the water collection tank 15 and the cooling water supply device 16 omits the first embodiment. This means that in the power supply system P2 the water vapor R4 coming from the steam generator 3 is discharged, and the water vapor R4 coming from the vapor compressor 11 of the high-boiling-point heat medium, mixed, and supplied to an external steam load and that the recovered water recovered from the steam load is the water supply pump 9 is supplied.

In the power supply system P2, as in the 3 is shown, the exhaust heat recovery unit K2 leaves the steam superheater 7 and this is constructed from the exhaust pipe 1 , the steam generator 2 the high boiling point heat medium, the steam generator 3 , the preheater 4 the heat medium with high boiling point, the water pre-heater 5 and the superheater 6 the vapor of the high boiling point heat medium. The power generation / steam output unit W2 is composed of the supply pump 8th the high boiling point heat medium, the water feed pump 9 , the steam turbine generator 10 the high boiling point heat medium, the vapor compressor 11 the high boiling point heat medium and the liquid collection tank 12 ,

The heat exchange conditions of the respective heat mediums (that is, the high-temperature exhaust gas G, the high-boiling heat medium R1, the high-boiling heat medium steam R2, the water R3, and the steam R4) in the heat exchange region of the exhaust heat recovery unit K2 are referred to in FIG 4 shown. In particular, when the heat exchange of the water R3 and the water vapor R4 with the high-temperature exhaust gas G is taken into consideration, that is, the heat exchange in the water pre-heater 5 and the steam generator 3 As shown in the broken line Ls1, the water R3 becomes a condition Ys1 corresponding to an exchanged heat transfer point Aa to an exchanged heat transfer point Ab which is a temperature slightly lower than the boiling point by heat exchange with the exhaust gas G of high temperature relatively low temperature in the water pre-heater 5 preheated and then the water vapor R4 of a condition Xs1, which corresponds to an exchanged heat transfer point Da, by means of heat exchange with the exhaust gas G high temperature in the steam generator 3 and by heat exchange with the vapor R2 of the high boiling point heat medium (high boiling point heat medium vapor) in the vapor compressor 11 the heat medium with high boiling point. The water vapor R4 of the condition Xs1 is supplied as a heat source to an external heat load and releases energy in the external heat load, thereby returning the water R3 to the condition Ys1 corresponding to the exchanged heat transfer point Aa.

On the other hand, the high boiling point heat medium R1 of a condition Yk1 corresponding to an exchanged heat transfer point B1, the vapor R2 of the high boiling point heat medium becomes a condition corresponding to an exchanged heat transfer point C1 of a broken line Lk1 by heat exchange with the exhaust gas G of high temperature a relatively high temperature in the preheater 4 the high boiling point heat medium and the steam generator 2 of the high-boiling-point heat medium, and the high-boiling-medium heat medium vapor R2 become the high-boiling-point heat medium vapor (high-boiling-point superheated steam) of a condition Xk1 which exceeds the boiling point by heat exchange with the high-temperature exhaust gas G. in the superheater 6 the steam is overheated with high boiling point heat medium. The vapor R2 of the high-boiling-point heat medium (superheated high-boiling-point heat medium vapor) of the condition Xk1 is then supplied to the steam turbine power generator 10 of the high-boiling-point heat medium is supplied as a dynamic driving force and releases energy, thereby returning to the high-boiling-point heat medium R1 of a condition YL1 corresponding to an exchanged heat transfer point Da.

In particular, the energy supply system P2 is a combined heat and power system, which conducts electrical energy to the outside and which also thermal energy by means of water vapor leads to the outside. After the exhaust heat recovery unit K2 of the power supply system P2, as in the exhaust heat recovery unit K1 of the first embodiment, in addition to the exhaust heat recovery, which generates the water vapor R4 from the water R3 by means of heat exchange with the exhaust gas G high temperature, also an exhaust heat recovery is performed, which the steam R2 of the high-boiling-point heat medium of the high boiling point heating medium R1 having a higher evaporation temperature than the water R3 (that is, a low evaporation pressure than the water R3) is heat-exchanged with the high-temperature exhaust gas G, thereby improving the present invention Efficiency of the recovery of the available energy compared to the conventional heat recovery method is made possible.

Here, when the overall efficiency is calculated for the case where ethylene glycol (molecular formula: C ₂ H ₆ O ₂ ) is used as the high-boiling-point heating medium R1, and for the case where diethylene glycol (empirical formula: C ₂ H ₁₀ O ₃ ) is used as the high boiling point heat medium R1, it is 81.26% (= 30.56% (power generation efficiency) + 50.70% (waste heat recovery efficiency)) in the case of ethylene glycol and 80.66% (= 33 , 15% (power generation efficiency) + 47.56% (waste heat recovery efficiency)) in the case of diethylene glycol.

In particular, when ethylene glycol is used, the overall efficiency is slightly higher than when diethylene glycol is used, but the power generation efficiency is higher when diethylene glycol is used than when ethylene glycol is used. The difference in the power generation efficiency results from the gas-liquid pressure difference of the two heat media. In the case where at the same temperature conditions, the gas pressure of the two heat media z. B. is 1.5 MPa, the liquid pressure of ethylene glycol is 0.109 MPa, while the liquid pressure of diethylene glycol is 0.027 MPa. Because diethylene glycol has a lower liquid pressure than ethylene glycol, diethylene glycol has a higher gas liquid pressure differential than ethylene glycol. This difference in the gas-liquid pressure difference is the cause of the power generation efficiency.

5 FIG. 12 shows the energy saving rate when ethylene glycol is used as the high boiling point heat medium R1 and when diethylene glycol is used for this purpose. 5 shows a power saving rate of η _s1 when ethylene glycol is used, and a power saving rate of η _s2 when using diethylene glycol in a characteristic graph showing the gross thermal efficiency of power generation η _E under a low heat value standard (LHV) on the horizontal axis and an exhaust heat recovery efficiency η _H on the vertical axis. Like in the 5 is shown, the energy saving rate of η _{s1 is} 23.5%, while the energy saving rate of η _{s2 is} 25.1%, indicating that a slightly higher value is achieved when diethylene glycol is used than when ethylene glycol is used.

Furthermore, the shows 6 the CO ₂ -reduction rate when ethylene glycol is used as the high-boiling-point heat medium R1 and when diethylene glycol is used for this purpose. The 6 shows a CO ₂ reduction rate S ₁ when ethylene glycol is used and a CO ₂ reduction rate S ₂ when diethylene glycol is used in a characteristic graph showing the gross thermal efficiency of power generation η _E below a low heat value standard (LHV) on the horizontal axis and an exhaust heat recovery efficiency η _H on the vertical axis. Like in the 6 ₂ , the CO ₂ -reduction rate S _{1 is} 38.4%, while the CO ₂ -reduction rate S _{2 is} 40.4%, which indicates a slightly higher value when diethylene glycol is used than when ethylene glycol is used as in the energy saving rates mentioned above.

The energy supply system P2 is a combined heat and power system, which leads electrical energy to the outside and which also leads thermal energy by means of water vapor to the outside. The power supply system P <b> 2 differs from a power supply device which converts only the available energy obtained from the exhaust gas heat recovery from the exhaust gas into electric energy to be discharged outside, as in the power supply system P <b> 1 of the first embodiment a power supply device, which converts the available energy, only into thermal energy, to lead them to the outside, as in conventional boilers. In these power supply devices, the available energy is converted into a single type of energy, such as electrical energy or thermal energy, and it is not possible to achieve high energy saving rates and CO ₂ reduction rates as in the power supply system P2.

Third embodiment

Next, a third embodiment will be described with reference to FIGS 7 and 8th described. In the 7 become the ingredients, which are the same as those of the power supply system P2 of the second embodiment, the same reference numerals

Like in the 7 1, the main feature of the power supply system P3 of the third embodiment is that it is the steam generator 3 with a relaxation tank 17 in the power supply system P2 of the second embodiment. The power supply system P3 further includes a pressurizing pump 18 as an auxiliary component of the flash tank 17 on.

In particular, an exhaust heat recovery unit K3 in the power supply system P3 has the exhaust pipe 1 , the steam generator 2 the heat medium with high boiling point, the preheater 4 the high boiling point heat medium, the water pre-heater 5 , the superheater 6 steam high-boiling heat medium and flash tank 17 on. In addition, a power generation / steam output unit W3 has the supply pump 8th the high boiling point heat medium, the water feed pump 9 , the steam turbine generator 10 the high boiling point heat medium, the steam compressor 11 the high boiling point heat medium, the liquid collection tank 12 and pressurizing pump 18 on.

The relaxation tank 17 is a steam generator of the type of relaxation, which is water (high temperature and high pressure water) coming from the water pre-heater 5 is converted by means of the phenomenon of relaxation in water vapor. The relaxation tank 17 is a type of container in which the internal pressure is adjusted so that the water (high temperature and high pressure water), that of the water pre-heater 5 is evaporated, vaporized by the phenomenon of relaxation and generates the water vapor R4 (flash steam) and saturated water R5. The phenomenon of relaxation is known as a phenomenon where a portion of the high-temperature and high-pressure water is vaporized as saturated water vapor when the high-temperature and high-pressure water is discharged into a low-pressure atmosphere area to release pressure.

The pressurization pump 18 is a pump that pressurizes the water, which is collected by an external heat load. The water coming from the pressurization pump 18 is discharged, is distributed and the water supply pump 9 and the vapor compressor 11 of the high boiling point heat medium. The water vapor R4, which is in the flash tank 17 is generated, the external heat load is supplied and the saturated water R5, which is similar in the expansion tank 1 is generated, is distributed and the water supply pump 9 and the vapor compressor 11 supplied to the high boiling point heat medium by z. B. a branch point j of the water supply pump 9 and the vapor compressor 11 of the high boiling point heat medium for the water supplied by the pressurizing pump 18 is discharged, as shown in the drawing.

Instead of the steam generator 3 In the second embodiment, which generates the water vapor R4 by the influence of the heat obtained from the heat exchange between the water R3 and the high-temperature exhaust gas G, the power supply system P3 particularly has a flash tank 17 on which generates steam R4 by means of influence of pressure (reduced pressure).

Since the pressure of the water, which is collected from the external heat load, is lower than the pressure of the saturated water R5, which from the flash tank 17 is discharged when the pressurizing pump 18 would not be provided, it would be difficult to the water with a sufficient pressure to the vapor compressor 11 of the high-boiling-point heat medium, and the efficiency of supplying the water vapor R4 to the outside would decrease. Accordingly, providing the pressurizing pump 18 although this is not an indispensable component of the third embodiment.

8th FIG. 14 shows the heat exchange conditions of the respective heat mediums (ie, the high temperature exhaust gas, the high boiling point heating medium R1, the high boiling point heating medium steam R2, the water R3, and the steam R4) in the exhaust heat recovery unit K3 of the power supply system P3. As with a dashed line Ls2 the 8th 4, it is possible to preheat the water R3 in a range extending from the exchanged heat transfer points Aa to B1, ie, in a range other than the range extending from the exchanged heat transfer points Aa to Ab of the second embodiment.

Due to the heat exchange between the water R3 and the exhaust gas G of high temperature in the range extending from the exchanged heat transfer points Aa to B1, it is possible to obtain a larger amount of the available energy from the exhaust gas G of high temperature, as shown in FIG a comparison with the 4 to which shows the heat exchange conditions of the second embodiment. Accordingly, according to the third embodiment, since a larger amount of the water R3 can be preheated, it is possible to generate a larger amount of water vapor R4 than in the second embodiment. According to the third embodiment, it is possible to reduce the cost of the system since the expansion tank 17 instead of the steam generator 3 is used.

• (1) Bei den entsprechenden vorstehenden Ausführungsbeispiele wird die Wärme aus der Abgaswärme des Abgases G hoher Temperatur gewonnen, indem zwei Arten von Flüssigkeiten mit verschiedenen Dampfdrücken verwendet werden, d. h. zusätzlich zu dem Wasser R3 wird das Wärmemedium R1 mit hohem Siedepunkt, welches einen niedrigeren Dampfdruck als Wasser aufweist, verwendet. Wahlweise ist es auch denkbar, die Wärmerückgewinnung aus der Abgaswärme des Abgases G hoher Temperatur mit nur dem Wärmemedium R1 mit hohem Siedepunkt, oder drei oder mehr Arten von Flüssigkeiten mit verschiedenen Dampfdrücken durchzuführen.

The present invention is not on. the corresponding foregoing embodiments are limited and z. B. the following changes conceivable.

• (1) In the respective foregoing embodiments, the heat is recovered from the exhaust gas heat of the exhaust gas G of high temperature by using two kinds of liquids having different vapor pressures, ie, in addition to the water R3, the high boiling point heat medium R1 becomes a lower vapor pressure as water. Alternatively, it is also conceivable to perform the heat recovery from the exhaust heat of the exhaust gas G of high temperature with only the heat medium R1 having a high boiling point, or three or more kinds of liquids having different vapor pressures.

• (2) Bei dem ersten und bei dem zweiten Ausführungsbeispiel werden der Vorheizer 4 des Wärmemediums mit hohem Siedepunkt und der Wasservorheizer 5 als Bauteile verwendet, aber es ist auch denkbar, den Vorheizer 4 des Wärmemediums mit hohem Siedepunkt und den Wasservorheizer 5 als notwendig auszulassen, obwohl der Wirkungsgrad der Wärmerückgewinnung sinken wird.
• (3) Jedes der entsprechenden vorstehenden Ausführungsbeispiele bezieht sich auf einen Fall, bei dem die Wärme aus der Abgaswärme des Abgases G hoher Temperatur zurückgewonnen wird, aber die Wärmequelle (Abgaswärme), die das Ziel der Wärmerückgewinnung ist, ist nicht auf ein Abgas G hoher Temperatur beschränkt. Zum Beispiel kann es auch eine Flüssigkeit oder ein Feststoff mit einer Temperatur sein, die 300°C übersteigt.
• (4) Jedes der entsprechenden vorstehenden Ausführungsbeispiele verwendet den Dampfturbinenstromerzeuger 10 des Wärmemediums mit hohem Siedepunkt und den Wasserdampfturbinenstromerzeuger 13 als Bauteile, um Strom zu erzeugen, welcher eine Art einer dynamischen Kraft ist. Wahlweise können verschiedene Moden einer dynamischen Kraft mittels Verbindung mit Kompressoren, Windturbinen, Pumpen, Propellern gewonnen und dergleichen als Antriebsvorrichtung gewonnen werden.
• (5) Das dritte Ausführungsbeispiel ersetzt den Wasserdampferzeuger 3 des zweiten Ausführungsbeispiels durch den Entspannungsbehälter 17, aber es ist auch denkbar den Wasserdampferzeuger 3 des ersten Ausführungsbeispiels durch den Entspannungsbehälter 17 zu ersetzen.
• (6) Bei dem dritten Ausführungsbeispiel ist ein Entspannungsbehälter 17 vorgesehen, aber es ist auch möglich, eine Anzahl an Entspannungsbehältern 17 in einer Abstimmung vorzusehen, und das Wasser R3, welches von dem Wasservorheizer 5 ausgegeben wird, in Wasserdampf mittels der Anzahl der abgestimmten Entspannungsbehältern 17 umzuwandeln.

For z. For example, in the case where the heat recovery from the exhaust gas heat of the high-temperature exhaust gas G is performed only with the high-boiling-point heat medium R1, a heat exchange is made with a smaller temperature difference than when water is used, although it depends on the temperature of the exhaust gas G. high temperature is possible, thereby enabling an improvement in the efficiency of the recovery of the available energy in comparison with the conventional case in which only the water R3 is used, is made possible. In addition to the high boiling point heating medium R1 and the water R3, it is also conceivable to perform the heat recovery from the exhaust gas heat of the high temperature exhaust gas G with the additional combination of a low boiling point heat medium having a lower boiling point than the water R3.

• (2) In the first and second embodiments, the preheater becomes 4 the high boiling point heat medium and the water pre-heater 5 used as components, but it is also possible to use the preheater 4 the high boiling point heat medium and the water pre-heater 5 as necessary to omit, although the efficiency of heat recovery will decrease.
• (3) Each of the respective foregoing embodiments refers to a case where the heat is recovered from the exhaust heat of the high temperature exhaust gas G, but the heat source (exhaust heat) that is the target of the heat recovery is not high on exhaust gas G. Temperature limited. For example, it may also be a liquid or solid having a temperature exceeding 300 ° C.
• (4) Each of the respective foregoing embodiments uses the steam turbine power generator 10 the high boiling point heat medium and the steam turbine power generator 13 as components to generate electricity, which is a kind of dynamic force. Optionally, various modes of dynamic power may be obtained by connection to compressors, wind turbines, pumps, propellers, and the like as a drive device.
• (5) The third embodiment replaces the steam generator 3 of the second embodiment by the expansion tank 17 but it is also conceivable the steam generator 3 of the first embodiment by the expansion tank 17 to replace.
• (6) In the third embodiment, there is a flash tank 17 provided, but it is also possible a number of relaxation tanks 17 to provide in a vote, and the water R3, which from the water pre-heater 5 in water vapor by means of the number of tuned expansion tanks 17 convert.

Industrial Applicability

According to the present invention, it is possible to provide an exhaust heat recovery system and an exhaust heat recovery method with a higher efficiency than in an exhaust heat recovery method in which the available energy is obtained by evaporating water or in an exhaust heat recovery method in which the available energy Evaporation of water and a liquid with a lower boiling point than water is obtained to provide.

Furthermore, according to the present invention, it is possible to provide a power supply system with higher efficiency than conventional systems due to the above-described higher efficiency of recovery of the available energy.

LIST OF REFERENCE NUMBERS

1

Exhaust pipe (heat conduction path)

2

Steam generator of the heat medium with high boiling point

3

Steam generator

4

Preheater of the high boiling point heat medium

5

water preheater

6

Superheater of the steam of the high boiling point heat medium

7

Steam superheater

8th

Supply pump of the heat medium with high boiling point

9

Water supply pump

10

Steam turbine power generator of the high boiling point heat medium

11

Steam compressor of the high-boiling-point heat medium (heat exchanger)

12

Liquid collection tank

13

Steam turbines power generators

14

Water vapor compressor

15

Water collection tank

16

Cooling water supply device

17

expansion tank

18

pressurizing

G

Exhaust gas of high temperature

R1

Heat medium with high boiling point

R2

Steam of the high boiling point heat medium

R3

water

R4

Steam

P1 to P3

Power system

K1 to K3

Exhaust heat recovery unit (exhaust heat recovery system)

W1

power generation unit

W2, W3

Power generation / steam output unit

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2010-034776 [0002]
• JP 2003-021302 [0006]
• JP 2000-346303 [0006]
• JP 2002-021583 [0006]
• JP 2753169 [0006]
• JP 2008-267341 [0006]

Claims (14)

Exhaust heat recovery system comprising: a heat conduction path which conducts exhaust heat, and a steam generator of the high-boiling-point heat medium which generates the steam of the high-boiling-point heat medium by means of heat exchange between the high-boiling-point heat medium having a higher evaporation temperature than water and the exhaust heat passed through the heat-conducting path. The exhaust heat recovery system according to claim 1, further comprising: a water steam generator disposed in the heat conduction path downstream of the high-boiling-point steam generator and generating water vapor by heat exchange between the water and the exhaust heat. The exhaust heat recovery system according to claim 1, further comprising, upstream of the high boiling point heat medium steam generator in the heat conduction path: a steam superheater of the high boiling point heat medium overheating the steam of the high boiling point heat medium by heat exchange with the exhaust heat, and / or one Steam superheater, which overheats the water vapor by heat exchange with the exhaust heat. The exhaust heat recovery system according to any one of claims 1 to 3, further comprising: a high boiling point heat medium preheater preheating the high boiling point heat medium, and / or a water preheater preheating the water. The exhaust heat recovery system according to any one of claims 1 to 4, wherein the heat pipe path is an exhaust pipe through which the exhaust gas having the exhaust heat flows. The exhaust heat recovery system according to any one of claims 1 to 5, wherein the high boiling point heat medium is ethylene glycol, diethylene glycol, propylene glycol, propylene ethylene glycol or formamide. Exhaust heat recovery system according to one of claims 4 to 6, wherein instead of the steam generator, a relaxation type steam generator is provided, which converts the water which has been preheated in the water heater, by means of the phenomenon of relaxation in water vapor. Energy supply system comprising: an exhaust heat recovery system according to any one of claims 1 to 7, and a dynamic force generating unit that supplies the high boiling point heat medium and / or the water to the exhaust heat recovery system, recovers the steam of the high boiling point heat medium, and / or the steam from the exhaust heat recovery system, and the steam of the high boiling point and / or the heat medium Water vapor as a working fluid generates a dynamic force. The power supply system according to claim 8, wherein the dynamic force generating unit includes a heat exchanger that performs heat exchange between the water and the high-boiling-point heat medium vapor after it is provided to generate a dynamic force to release the steam of the high-boiling heat medium to condense and liquefy and to generate the water vapor. An exhaust heat recovery method that performs heat recovery by evaporating a high-boiling-point heat medium having a higher evaporation temperature than water by means of exhaust heat. The exhaust heat recovery method according to claim 10, which performs the heat recovery by evaporating water by exhaust heat after the heat recovery with the high boiling point heat medium. The exhaust heat recovery method according to claim 10 or 11, wherein the high boiling point heat medium and / or the steam are superheated by heat exchange with the exhaust heat. The exhaust heat recovery method according to any one of claims 10 to 12, wherein the high boiling point heat medium is ethylene glycol, diethylene glycol, propylene glycol, propylene ethylene glycol or formamide. The exhaust heat recovery method according to claim 10, wherein instead of performing the heat recovery by evaporating the water by means of the exhaust heat after the heat recovery by the high boiling point heat medium, heat recovery is performed by preheating the water after heat recovery by the high heat medium Boiling point performed and then the preheated water is evaporated by means of the relaxation phenomenon.

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