Heating systems – Heat and power plants
Reexamination Certificate
2000-03-23
2001-09-18
Joyce, Harold (Department: 3746)
Heating systems
Heat and power plants
C165S299000
Reexamination Certificate
active
06290142
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cogeneration apparatus including a power generator equipment and particularly a cogeneration apparatus capable of properly supplying thermal energy in response to variable requirements of heat.
2. Description of the Related Art
Recently, cogeneration apparatuses applied as on-site power generation utilities for generating electric power and distributing hot water simultaneously with the use of a power source such as a gas engine fueled with town gas have been focused in view of the preservation of the global environments. Such a cogeneration apparatus includes a particular means for minimizing any loss of the thermal energy because the heat produced during the generation of electric power is not always required to consume immediately, although it is ready to be taken out upon the request of supply. For example, a cogeneration system disclosed in Japanese Patent Unexamined Publication (Hei) 8-4586 incorporates a hot water storage tank for saving a volume of hot water, which has been heated by the thermal energy produced with a power generator.
The conventional cogeneration system disclosed in the Publication has an advantage that the thermal energy is saved but not wasted in the air and will thus enable to satisfy any demand of heat supply occurring during out of operation of the power generation. It is however necessary to satisfy a variety of different demands including the supply of hot water and the requirement of heating through responding to each variable of the demand of the thermal energy separately. The problem is that any of the conventional cogeneration systems is hardly capable of satisfying a number of the variable demands for the thermal energy.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide a cogeneration apparatus capable of supplying thermal energy properly in response to a plurality of separate demands for supplying the heat energy.
As a first feature of the present invention, a power generator, a hot water storage tank for storing a first hot water heated by waste heat from the power generator, a first heat exchanger provided in the hot water storage tank for producing the first hot water, a second heat exchanger provided above the first heat exchanger in the hot water storage tank for drawing heat from the first hot water to produce a second hot water, a first temperature sensor provided between the uppermost end of the first heat exchanger and the lowermost end of the second heat exchanger, and a controller arranged responsive to a temperature detected by the first temperature sensor for controlling the operation of the power generator.
As a second feature of the present invention, a second temperature sensor provided above the second heat exchanger and wherein the controller drives the power generator either when a temperature detected by the first temperature sensor is not higher than a first reference temperature or when a temperature detected by the second temperature sensor is not higher than a second reference temperature which is set higher than the first reference temperature. As a third features of the present invention, the power generator is stopped when the temperature detected by the first temperature sensor exceeds a third reference temperature which is set higher than the first reference temperature.
As a forth feature of the present invention, the first reference temperature is set to a higher level than the temperature of hot water required by a thermal load to which the second hot water is supplied. As a fifth feature of the present invention, a re-heating boiler provided on a hot water passage connected to the second heat exchanger, and a valve means for switching between one operation of conveying the second hot water from the re-heating boiler to the thermal load connected across the hot water passage and the other operation of returning back at least a portion of the hot water to the second heat exchanger while bypassing the thermal load.
As a sixth feature of the present invention, the power generator is an engine generator which is interconnected with a commercial power system and driven according to a driving command from the controller to generate a constant rate of an electric power.
According to the first to sixth features of the present invention, the apparatus can yield and distribute the thermal energy collected from its generator system in response to two different demands of heat through judging whether or not the demand of heat is called and examining the temperature of the hot water in the hot water storage tank to determine the level of the demand and thus to control the operation of the generator system. In particular, the second feature of the present invention allows the generation of heat corresponding to two independent demands of heat, which are different in the temperature required.
According the fourth feature of the present invention, the temperature of water detected by the first temperature sensor can be monitored and used for supplying the hot water at a temperature requested by the thermal load. According to the fifth feature, the hot water received from the re-heating boiler can be delivered to the hot water storage tank or the second demand of heat as successfully respond to an abrupt change in the demand of heat.
According to the sixth feature of the present invention, the power supply can be guaranteed by the commercial power supply system when the engine generator is out of operation, and therefore, the engine generator is permitted to run stably at a constant speed of revolution.
REFERENCES:
patent: 2696085 (1954-12-01), Ruff
patent: 3604501 (1971-09-01), Brants
patent: 4065055 (1977-12-01), De Cosimo
patent: 5819843 (1998-10-01), Inoue et al.
patent: 8-4586 (1996-01-01), None
Oyama Kichitarou
Togawa Kazuhiro
Armstrong Westerman Hattori McLeland & Naughton LLP
Boles Derek S.
Honda Giken Kogyo Kabushiki Kaisha
Joyce Harold
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