Abstract:
A combination power generating system includes a first power generating system, which boils water into steam to turn a first turbine for driving a first generator to generate electricity, and a second power generating system, which utilizes waste heat from the first power generating system to heat an organic solvent into organic vapor for turning a second turbine to drive a second generator to generate electricity.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to power generating technology and more particularly, to a combination power generating system, which comprises a first power generating system, and a second power generating system that utilizes waste heat from the first power generating system to heat an organic solvent into high-pressure organic vapor for turning a turbine to drive a generator for generating electricity. 
         [0003]    2. Description of the Related Art 
         [0004]    A conventional steam-driven power generating system, as shown in  FIG. 1 , generally comprises a steam boiler  10  holding a certain amount of water W, a heater  11  adapted to heat the water W in the steam boiler  10  into steam, a turbine  12  in communication with the steam boiler  10  and turned by steam produced by the steam boiler  10 , a generator G is driven by the turbine  12  to generate electricity, a steam pipe  13  extended from one end of the turbine  12  remote from the steam boiler  10 , a cooling pond  16 , a water outlet pipe  17  for guiding hot water out of the cooling pond  16 , a water inlet pipe  18  for guiding cooling water from an external water source into the cooling pond  16 , a steam pipe  13  for guiding steam out of the turbine  12 , a cooling coil pipe  14  extended from the steam pipe  13  through the cooling pond  16  for guiding steam through the cooling pond  16  for condensing into water, a return pipe  15  connected between the cooling coil pipe  14  and the steam boiler  10 , and a motor pump MP mounted in junction between the cooling coil pipe  14  and the return pipe  15  for pumping condensed water from the cooling coil pipe  14  back into the steam boiler  10 . 
         [0005]    The aforesaid prior art of power generating system is still not satisfactory in function because of the drawbacks that this power generating system has low efficiency and wastes much heat energy. When steam is produced to turn the turbine  12 , a big amount of cooling water is circulated through the cooling pond  16  to cool down steam into water for recycling. According to analysis, about 33% of heat energy is converted into electricity (net output) and about 7% of heat energy is consumed internally (in turbine, piping and motor pump), and about 60% of heat energy is wasted in heat exchange between the cooling coil pipe  14  and cooling water in the cooling pond  16 . 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a combined power generating system, which utilizes waste heat to enhance power generation, saving energy consumption. 
         [0007]    To achieve this and other object of the present invention, a combination power generating system comprises a first power generating system, which boils water into steam to turn the first turbine for driving the first generator to generate electricity, and a second power generating system, which utilizes waste heat from the first power generating system to heat an organic solvent into organic vapor for turning the second turbine to drive the second generator to generate electricity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a system block diagram of a power generating system according to the prior art. 
           [0009]      FIG. 2  is a system block diagram of a combined power generating system according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0010]    Referring to  FIG. 2 , a combined power generating system in accordance with the present invention is shown comprising a first power generating system  100  and a second power generating system  200 . 
         [0011]    The first power generating system  100  comprises a steam boiler  10 , a heater  11  adapted to heat water W in the steam boiler  10  into steam, a turbine  12  is connected with the steam boiler  10 , a generator G 1  coupled to the turbine shaft of the turbine  12 , a steam pipe  13  extended from one end of the turbine  12  remote from the steam boiler  10 , a cooling coil pipe  14  connected to one end of the steam pipe  13  remote from the turbine  12 , and a return pipe  15  connected between the other end of the cooling coil pipe  14  and the steam boiler  10 , and a motor pump MP 1  mounted in junction between the cooling coil pipe  14  and the return pipe  15  to pump condensed water from the cooling coil pipe  14  back into the steam boiler  10 . 
         [0012]    The second power generating system  200  comprises a boiler  20  that holds the cooling coil pipe  14  to enable a solvent H in the boiler  20  to be heated into organic vapor by steam that flows through the cooling coil pipe  14 , a turbine  22  is connected with the steam boiler  20 , a generator G 2  coupled to the turbine shaft of the turbine  22 , a cooling pond  24 , a water outlet pipe  25  for guiding hot water out of the cooling pond  24 , a water inlet pipe  26  for guiding cooling water from an external water source into the cooling pond  24 , a cooling coil pipe  23  extending through the cooling pond  24  and connected between the turbine  22  and the boiler  20 , and a motor pump MP 2  is set for pumping condensed fluid from the cooling coil pipe  23  back to the boiler  20 . Further, sea water can be pumped by MP 3  into the cooling pond  24  for cooling the organic vapor that flows through the cooling coil pipe  23 . 
         [0013]    During operation, the heater  11  heats water in the steam boiler  10  of the first power generating system  100  into high-pressure high-temperature steam that turns the turbine  12 , causing the generator G 1  of the first power generating system  100  to generate electricity. High-pressure high-temperature steam that goes through the turbine  12  become low-temperature low-pressure steam (120° C., 290 psi) and it is guided into the cooling coil pipe  14  to heat the low boiling point of solvent H in the boiler  20  of the second power generating system  200  into high-pressure organic vapor that turns the turbine  22 , causing the generator G 2  of the second power generating system  200  to generate electricity. After passing through the cooling coil pipe  14  to make heat exchange with the solvent H in the boiler  20 , steam is condensed into water and pumped by the motor pump MP 1  back to the steam boiler  10 . Organic vapor that flows through the cooling coil pipe  23  is cooled down by cooling water circulating through the cooling pond  24  and condensed into solvent H that is pumped by the motor pump MP 2  back to the boiler  20 . 
         [0014]    As stated above, the second power generating system  200  utilizes waste heat from the first power generating system  100  to heat the solvent H into organic vapor for driving the turbine  22  to cause the associating generator G 2  to generate electricity. 
         [0015]    Various solvents can be selectively used according to the cooling condition. A solvent relating function such as “more thermal efficiency” and “more electricity generated” is listed in table 1: 
         [0000]                                                  TABLE 1                   Boiling   More thermal   More electricity       Organic Solvent   point (° C.)   efficiency (%)   generated (%)                                Ethanol   78   2.8   8.5       Methanol   64.5   4.2   12.7       2,2, Dimethyl Butane   50   5.5   16.7       Dichloromethane   41   6.4   19.3       n-Pentane   36   6.8   20.6       Isopentane   28   7.5   22.7       Monochloroethane   12.5   9.0   27.3       Neopentane   9.5   9.4   28.5       n-Butane   0   10.2   30.9                    
Interpretation of table 1:
 
1. In the conventional power generating system, if 100 cal of heat is produced from heater  11 , only  33  cal is converted into electricity (net output). In table 1, take methanol as example, 4.2 cal of heat is converted into electricity. The calculation equation is shown as the following:
 
         [0000]      More thermal efficiency=4.2/100×100%=4.2%
 
         [0000]      More electricity generated=4.2/33×100%=12.7%
 
         [0000]    2. The boiling point of the chosen organic solvent must be higher than the cooling water applied in the cooling pond  24 . 
         [0016]    As indicated in the above table, waste heat from the first power generating system can drive the second power generating system to increase electricity generation by about 7.3%˜30%. It requires cooling water to cool down the organic vapor produced during operation of the second power generating system. 
         [0017]    Further, a partition wall  27  is set between the first power generating system  100  and the second power generating system  200  to prohibit entering of organic vapor from the second power generating system  200  into the first power generating system  100  in case of a leakage and to avoid damage to both the two power generating system. 
         [0018]    Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.