Power plants – Motive fluid energized by externally applied heat – Process of power production or system operation
Reexamination Certificate
2001-11-26
2002-10-08
Nguyen, Hoang (Department: 3748)
Power plants
Motive fluid energized by externally applied heat
Process of power production or system operation
C060S673000, C060S676000
Reexamination Certificate
active
06460338
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an absorption waste-heat recovery system including a generator for recovering heat by receiving heat medium fluid containing waste heat and concentrating a solution with absorbent dissolved therein and generating steam, a condenser capable of condensing the steam generated from the generator, an evaporator operable to evaporate condensed water condensed by the condenser and an absorber operable to dilute the concentrated solution concentrated by the generator by causing the solution to absorb the steam from the evaporator.
2. Description of the Related Art
In the absorption waste-heat recovery system described above, there is provided an absorption cold/hot water producing apparatus including the generator for concentrating solution with absorbent dissolved therein into a concentrated solution and generating steam, the condenser capable of condensing the steam generated by the generator, the evaporator operable to evaporate condensed water condensed by the condenser and the absorber operable to dilute the concentrated solution concentrated by the generator by causing the solution to absorb the steam generated from the evaporator. In operation, by inputting heat medium fluid containing waste heat to the generator, the system recovers heat in the form of concentration heat of the diluted solution.
With the absorption cold/hot water producing apparatus described above, for production of cold water, steam obtained by concentration-separation at the generator is condensed by the condenser and this condensed water is supplied to the evaporator, in which the condensed water is caused to contact a heat exchanger tube adapted for producing cold water thereby to absorb latent heat of evaporation, so that the water inside the heat exchanger tube is cooled. The generated steam is guided to the absorber to be absorbed into the concentrated solution therein, whereby the concentrated solution concentrated by the generator is diluted. This diluted solution which has been diluted and heated also is cooled inside the absorber and then returned to the generator. On the other hand, for production of warm water, in many cases, the heat contained in the steam heated by the generator and in the concentrated solution is used directly for the purpose of hot water production.
With the absorption waste-heat recovery system having the above-described conventional construction, in order to improve its heat recovery efficiency, the system often employs a double-effect cycle involving two generators, one being a high temperature generator and the other being a low temperature generator. However, it is difficult for the high temperature generator to recover the heat contained in the heat medium fluid sufficiently. Hence, there has been a desire for further improvement in heat recovery efficiency. More particularly, for example, exhaust gas from a heat-electricity co-generating plant generally has a temperature of 200 to 300° C. and the diluted solution introduced to the high temperature generator has a temperature of about 150 to 155° C. after being pre-heated through heat exchange reaction with the heated concentrated solution. Therefore, there exists the problem of inability to recover the heat of the exhaust gas sufficiently.
Then, in an attempt to improve this heat recovery efficiency, as known from Japanese laid-open patent application gazette No. Hei. 11-304274 for example, there has been proposed to provide the absorption heat recovery system with still another generator, i.e. an auxiliary heat generator, so that the heat medium fluid after heat recovery by the high temperature generator is introduced to this auxiliary heat generator for further recovery of heat therefrom. In the case of the invention described in the above-identified laid-open gazette, this invention utilizes the reverse flow in order to take advantage of the fact that the steam separated by the high temperature generator has a higher temperature than the concentrated solution after the heat recovery by the auxiliary generator. More particularly, an auxiliary low temperature generator is provided for receiving the concentrated solution from the auxiliary generator and this solution is then separated by the high temperature generator and heated with steam and condensed again. That is, the construction employs the double-effect cycle with heat currents crossing each other. And, for production of hot water with this system, the evaporator is deactivated, so that the cooling water running in a cooling tube of the absorber is taken out as hot or warm water.
More particularly, the diluted solution is fed to the auxiliary generator, where the solution is concentrated. And, this concentrated solution is fed to the low temperature generator. A portion of this concentrated solution concentrated by the low temperature generator is fed to the high temperature generator. On the other hand, the concentrated solution fed to the low temperature generator is heated with steam separated by the high temperature generator. Further, the concentrated solution re-concentrated at the high temperature generator is used for preheating a portion of the concentrated solution from the low temperature generator and then fed to the absorber together the remaining portion of the concentrated solution from the low temperature generator. The steam separated at the high temperature generator and having heated the concentrated solution at the low temperature generator, the steam separated at the low temperature generator and the steam separated at the auxiliary generator are guided to the condenser to be cooled and condensed thereat. Condensed water condensed from the steam at the condenser is evaporated at the evaporator, thereby to absorb latent heat of evaporation, thus producing cold water. The concentrated solution concentrated at the high temperature generator and the remaining portion of the concentrated solution concentrated at the low temperature generator are together guided to the absorber to absorb the steam evaporated at the evaporator, so that the resultant heat of absorption heats the cooling water. Here, if the low temperature generator guides the steam from the high temperature generator after heating the concentrated solution from the auxiliary generator directly to the evaporator via a bypass passage, this steam together with the steam from the auxiliary generator and the steam from the low temperature generator are guided to the evaporator, so that warm water may be produced.
As described above, with the invention disclosed by the above-identified laid-open patent application gazette, the cycle is very complicated. And, the heat source represented by a combustion device such as an internal combustion engine will experience variation in the heat amount contained in its exhaust gas containing the waste heat, in association with load variation. In order to allow the concentrated solution and steam to flow from the generators through the respective components to the absorber in accordance with a pressure which is gradually reduced in association with heat exchange reactions between the concentrated solution and the steam, it is necessary to adjust the circulation amount of the solution containing absorbent dissolved therein and also to adjust its pressure relationship. In particular, in the case of the low temperature generator, the concentrated solution from the auxiliary generator is heated with the steam from the high temperature generator. Then, when variations occur in the amount of exhaust gas and its temperature, it is extremely difficult to control the balance between the temperature of the solution to be heated and the heating steam at least at the low temperature generator. This will lead inevitably to complexity in a control mechanism therefor. If the temperature balance is lost, this will lead also to change in the pressure relationship, thus inviting reduction in the output from the heat recovery system. In this way, because of mutual interference presen
Katayama Masatoshi
Matsuda Kenji
Origane Takafumi
Nguyen Hoang
Takuma Co., Ltd.
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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