Patent Publication Number: US-10788204-B2

Title: Injection feedwater heater for steam power generating system

Description:
BACKGROUND OF THE PRESENT INVENTION 
     Field of Invention 
     The present invention relates to a power generating system, and more particularly to a steam power generating system for a steam power plant, wherein the steam power generating system comprises at least one injection feedwater heater which has enhanced heat exchange efficiency between steam and condensate water. 
     Description of Related Arts 
     A conventional power plant, such as a steam power plant, usually comprises a boiler, a turbine assembly including at least one turbine unit, a generator, a condenser and a feedwater heater. The boiler is arranged to generate steam which is then guided to produce work in the turbine assembly. The steam may spin or rotate the turbine unit which is connected to the generator. When the turbine unit is rotated, the generator is arranged to produce electricity. Heat energy is then converted into mechanical energy which is then further converted into electrical energy. 
     Conventionally, the steam used to turn the turbine unit is guided to enter into a condenser in which the steam is arranged to be cooled down and condensed into water. The condensate water may then be guided to enter a feedwater heater. The feedwater heater is arranged to raise the temperature of the water by utilizing extraction steam from various stages of the turbine assembly. 
     Two conventional types of feedwater heaters have been used. Feedwater heaters may be open heat exchangers in which extracted steam may be allowed to mix with condensate water. On the other hand, feedwater heaters may also be closed in which condensate water and steam perform heat exchange through a plurality of heat exchanging tubes. As a matter of conventional practices, most feedwater heaters employed in steam power plants are closed feedwater heaters. 
     A major disadvantage of closed feedwater heaters is that they have relatively low heat exchange efficiency and complicated installation and manufacturing procedures. Since heat exchange between condensate water and steam are through heat exchanging tubes, a typical closed feedwater heater may comprise many heat exchanges tubes which may be arranged in manifold for maximizing the surface area through which heat exchange process may take place. The manufacturing and installation of this type of feedwater heaters are very complicated and expensive in costs. 
     As a result, there is a need to develop a new type of feedwater heater which is suitable to be utilized in a steam power plant or other situations. 
     SUMMARY OF THE PRESENT INVENTION 
     Certain variations of the present invention provide a steam power generating system comprising an injection feedwater heater with enhanced heat exchange efficiency between steam and condensate water. 
     Certain variations of the present invention provide an injection feedwater heater for use in a steam power generating system, wherein steam and condensate water may be evenly and effectively mixed for preheating condensate water before it is circulated back to a steam generator. 
     In one aspect of the present invention, it provides a steam power generating system, comprising: 
     a plurality of connecting pipes; 
     a steam generator arranged to produce a predetermined amount of steam; 
     a turbine assembly comprising at least one turbine connected to the steam generator through at least one of the connecting pipes, the steam generated by the steam generator being arranged to produce work on the turbine assembly; 
     an electric generator connected to the turbine assembly, the work produced in the turbine assembly being converted to a predetermined amount of electricity; 
     a condenser connected to the turbine assembly through at least one of the connecting pipes, the steam from the turbine assembly being condensed into condensate water in the condenser; and 
     a feedwater preheat arrangement comprising at least one injection feedwater heater which is connected to the condenser and the turbine assembly through at least one of the connecting pipes, and comprises: 
     a main heater body having a heat exchange compartment, a water inlet, a steam inlet, and a water outlet formed on the main heater body; and 
     an injection nozzle provided in the main heater body at a position adjacent to the water inlet, wherein a predetermined amount of the condensate water from the condenser is arranged to be pumped into the main heater body through the water inlet, the condensate water passing through the water inlet being arranged to be injected into the heat exchange compartment through the injection nozzle for creating a negative pressure in the heat exchange compartment, the negative pressure drawing a predetermined amount of steam from the turbine assembly to enter the heat exchange compartment through the steam inlet for mixing with the condensate water, the condensate water being heated up by the steam which is then condensed into water and arranged to be discharged out of the heat exchange compartment through the water outlet. 
     Another aspect of the present invention provides a steam power generating system, comprising: 
     a plurality of connecting pipes; 
     a steam generator arranged to produce a predetermined amount of steam; 
     a turbine assembly comprising at least one turbine connected to the steam generator through at least one of the connecting pipes, the steam generated by the steam generator being arranged to produce work on the turbine assembly; 
     an electric generator connected to the turbine assembly, the work produced in the turbine assembly being converted to a predetermined amount of electricity; 
     a condenser connected to the turbine assembly through at least one of the connecting pipes, the steam from the turbine assembly being condensed into condensate water in the condenser; and 
     a feedwater preheat arrangement provided between the condenser and the steam generator, the feedwater preheat arrangement comprising: 
     a first injection feedwater heater which comprises: 
     a first main heater body having a first heat exchange compartment, a first water inlet connected to the condenser, a first steam inlet connected to the turbine assembly, and a first water outlet formed on the first main heater body and connected to the steam generator; and 
     a first injection nozzle provided in the first main heater body at a position adjacent to the first water inlet; 
     a second injection feedwater heater, which comprises: 
     a second main heater body having a second heat exchange compartment, a second water inlet connected to the condenser and the first water inlet, a second steam inlet connected to the turbine assembly, and a second water outlet formed on the second main heater body and connected to the steam generator and the first water outlet in parallel; and 
     a second injection nozzle provided in the second main heater body at a position adjacent to the second water inlet; and 
     a third injection feedwater heater, which comprises: 
     a third main heater body having a third heat exchange compartment, a third water inlet connected to the condenser and the first water inlet and the second water inlet, a third steam inlet connected to the turbine assembly, and a third water outlet formed on the third main heater body and connected to the steam generator and the first water outlet and the second water outlet all in parallel; and 
     a third injection nozzle provided in the third main heater body at a position adjacent to the third water inlet; 
     the first through third injection feedwater heater being connected in parallel with each other, wherein a predetermined amount of condensate water from the condenser is arranged to be pumped into the first through third main heater body via the first through third water inlet respectively, the condensate water passing through the first through third water inlet being arranged to be injected into the first through third heat exchange compartment via the first through the third injection nozzle respectively for creating a negative pressure in the first heat exchange compartment, the second heat exchange compartment and the third heat exchange compartment, the negative pressure drawing a predetermined amount of steam from the turbine assembly to enter the first through third heat exchange compartment via the first through the third steam inlet for mixing with the condensate water, the condensate water being heated up by the steam which is then condensed into water and arranged to be discharged out of the corresponding first through the third heat exchange compartment via the first through third water outlet. 
     Another aspect of the present invention provides a steam power generating system, comprising 
     a plurality of connecting pipes; 
     a steam generator arranged to produce a predetermined amount of steam; 
     a turbine assembly comprising at least one turbine connected to the steam generator through at least one of the connecting pipes, the steam generated by the steam generator being arranged to produce work on the turbine assembly; 
     an electric generator connected to the turbine assembly, the work produced in the turbine assembly being converted to a predetermined amount of electricity; 
     a condenser connected to the turbine assembly through at least one of the connecting pipes, the steam from the turbine assembly being condensed into condensate water in the condenser; and 
     a feedwater preheat arrangement provided between the condenser and the steam generator, the feedwater preheat arrangement comprising: 
     a deaerator connected to the turbine assembly; 
     a first injection feedwater heater which comprises: 
     a first main heater body having a first heat exchange compartment, a first water inlet connected to the condenser, a first steam inlet connected to the turbine assembly, and a first water outlet formed on the first main heater body and connected to the deaerator; and 
     a first injection nozzle provided in the first main heater body at a position adjacent to the first water inlet; 
     a second injection feedwater heater, which comprises: 
     a second main heater body having a second heat exchange compartment, a second water inlet connected to the deaerator, a second steam inlet connected to the turbine assembly, and a second water outlet formed on the second main heater body; and 
     a second injection nozzle provided in the second main heater body at a position adjacent to the second water inlet; and 
     a third injection feedwater heater, which comprises: 
     a third main heater body having a third heat exchange compartment, a third water inlet connected to the second water outlet of the second injection feedwater heater, a third steam inlet connected to the turbine assembly, and a third water outlet formed on the third main heater body and connected to the steam generator; and 
     a third injection nozzle provided in the third main heater body at a position adjacent to the third water inlet; 
     wherein a predetermined amount of condensate water from the condenser is arranged to sequentially pass through the first injection feedwater heater, the deaerator, the second injection feedwater heater, the third injection feedwater heater, and back to the steam generator; 
     for the first through third injection feedwater heater, the condensate water being arranged to be pumped into the corresponding first through third main heater body via the first through third water inlet respectively, the condensate water passing through the corresponding first through third water inlet being arranged to be injected into the corresponding first through third heat exchange compartment via the first through the third injection nozzle respectively for creating a negative pressure in the first through third heat exchange compartment, the negative pressure drawing a predetermined amount of steam from the turbine assembly to enter the first through third heat exchange compartment via the first through the third steam inlet for mixing with the condensate water, the condensate water being heated up by the steam which is then condensed into water and arranged to be discharged out of the corresponding first through the third heat exchange compartment via the first through third water outlet. 
     Another aspect of the present invention provides a steam power generating system, comprising: 
     a plurality of connecting pipes; 
     a steam generator arranged to produce a predetermined amount of steam; 
     a turbine assembly comprising at least one turbine connected to the steam generator through at least one of the connecting pipes, the steam generated by the steam generator being arranged to produce work on the turbine assembly; 
     an electric generator connected to the turbine assembly, the work produced in the turbine assembly being converted to a predetermined amount of electricity; 
     a condenser connected to the turbine assembly through at least one of the connecting pipes, the steam from the turbine assembly being condensed into condensate water in the condenser; and 
     a feedwater preheat arrangement provided between the condenser and the steam generator, the feedwater preheat arrangement comprising: 
     a deaerator connected to the turbine assembly; 
     a first injection feedwater heater which comprises: 
     a first main heater body having a first heat exchange compartment, a first water inlet connected to the condenser, a first steam inlet connected to the turbine assembly, and 
     first water outlet formed on the first main heater body and connected to the deaerator; and 
     a first injection nozzle provided in the first main heater body at a position adjacent to the first water inlet; 
     a second injection feedwater heater, which comprises: 
     a second main heater body having a second heat exchange compartment, a second water inlet connected to the condenser and the first water inlet in parallel, a second steam inlet connected to the turbine assembly, and a second water outlet formed on the second main heater body and connected to the deaerator and the first water outlet in parallel; and 
     a second injection nozzle provided in the second main heater body at a position adjacent to the second water inlet; and 
     a third injection feedwater heater, which comprises: 
     a third main heater body having a third heat exchange compartment, a third water inlet connected to the deaerator, a third steam inlet connected to the turbine assembly, and a third water outlet formed on the third main heater body and connected to the steam generator; and 
     a third injection nozzle provided in the third main heater body at a position adjacent to the third water inlet; 
     a fourth injection feedwater heater, which comprises: 
     a fourth main heater body having a fourth heat exchange compartment, a fourth water inlet connected to the deaerator and the third water inlet in parallel, a third steam inlet connected to the turbine assembly, and a third water outlet formed on the third main heater body and connected to the steam generator and the third water outlet in parallel; and 
     a fourth injection nozzle provided in the fourth main heater body at a position adjacent to the fourth water inlet; 
     wherein a predetermined amount of condensate water from the condenser is arranged to be pumped into the first injection feedwater heater and the second injection feedwater heater in parallel, the water coming out of the first injection feedwater heater and the second injection feedwater heater being arranged to enter the deaerator and thereafter guided to enter the third injection feedwater heater and the fourth injection feedwater heater in parallel, the condensate water coming out of the third injection feedwater heater and the fourth injection feedwater heater being arranged to flow back to the steam generator for another cycle of electricity generation; 
     for the first through fourth injection feedwater heater, the condensate water being arranged to be pumped into the corresponding first through fourth main heater body via the first through fourth water inlet respectively, the condensate water passing through the corresponding first through fourth water inlet being arranged to be injected into the corresponding first through fourth heat exchange compartment via the first through the fourth injection nozzle respectively for creating a negative pressure in the first through fourth heat exchange compartment, the negative pressure drawing a predetermined amount of steam from the turbine assembly to enter the first through fourth heat exchange compartment via the first through the fourth steam inlet for mixing with the condensate water, the condensate water being heated up by the steam which is then condensed into water and arranged to be discharged out of the corresponding first through the fourth heat exchange compartment via the first through fourth water outlet. 
     Another aspect of the present invention provides a steam power generating system, comprising 
     a plurality of connecting pipes; 
     a steam generator arranged to produce a predetermined amount of steam; 
     a turbine assembly comprising at least one turbine connected to the steam generator through at least one of the connecting pipes, the steam generated by the steam generator being arranged to produce work on the turbine assembly; 
     an electric generator connected to the turbine assembly, the work produced in the turbine assembly being converted to a predetermined amount of electricity; 
     a condenser connected to the turbine assembly through at least one of the connecting pipes, the steam from the turbine assembly being condensed into condensate water in the condenser; and 
     a feedwater preheat arrangement provided between the condenser and the steam generator, the feedwater preheat arrangement comprising: 
     a first and a second deaerator connected to the turbine assembly; 
     a first injection feedwater heater which comprises: 
     a first main heater body having a first heat exchange compartment, a first water inlet connected to the condenser, a first steam inlet connected to the turbine assembly, and a first water outlet formed on the first main heater body and connected to the first deaerator; and 
     a first injection nozzle provided in the first main heater body at a position adjacent to the first water inlet; 
     a second injection feedwater heater, which comprises: 
     a second main heater body having a second heat exchange compartment, a second water inlet connected to the condenser and the first water inlet in parallel, a second steam inlet connected to the turbine assembly, and a second water outlet formed on the second main heater body and connected to the second deaerator; and 
     a second injection nozzle provided in the second main heater body at a position adjacent to the second water inlet; and 
     a third injection feedwater heater, which comprises: 
     a third main heater body having a third heat exchange compartment, a third water inlet connected to the first deaerator, a third steam inlet connected to the turbine assembly, and a third water outlet formed on the third main heater body; and 
     a third injection nozzle provided in the third main heater body at a position adjacent to the third water inlet; 
     a fourth injection feedwater heater, which comprises: 
     a fourth main heater body having a fourth heat exchange compartment, a fourth water inlet connected to the second deaerator, a fourth steam inlet connected to the turbine assembly, and a fourth water outlet formed on the fourth main heater body; and 
     a fourth injection nozzle provided in the fourth main heater body at a position adjacent to the fourth water inlet; 
     a fifth injection feedwater heater, which comprises: 
     a fifth main heater body having a fifth heat exchange compartment, a fifth water inlet connected to the third water outlet, a fifth steam inlet connected to the turbine assembly, and a fifth water outlet formed on the fifth main heater body and connected to the steam generator; 
     a fifth injection nozzle provided in the fifth main heater body at a position adjacent to the fifth water inlet; 
     a sixth injection feedwater heater, which comprises: 
     a sixth main heater body having a sixth heat exchange compartment, a sixth water inlet connected to the fourth water outlet, a sixth steam inlet connected to the turbine assembly, and a sixth water outlet formed on the sixth main heater body and connected to the steam generator and the fifth water outlet in parallel; and 
     a sixth injection nozzle provided in the sixth main heater body at a position adjacent to the sixth water inlet; 
     wherein a predetermined amount of condensate water from the condenser is arranged to be pumped into the first injection feedwater heater and the second injection feedwater heater in parallel, the water coming out of the first injection feedwater heater and the second injection feedwater heater being arranged to enter the first deaerator and the second deaerator respectively, the condensate water coming out from the first deaerator being arranged to sequentially enter the third injection feedwater heater and the fifth injection feedwater heater, the condensate water coming out from the second deaerator being arranged to sequentially enter the fourth injection feedwater heater and the sixth injection feedwater heater, the condensate water coming out of the fifth injection feedwater heater and the sixth injection feedwater heater being arranged to flow back to the steam generator for another cycle of electricity generation; 
     for the first through sixth injection feedwater heater, the condensate water being arranged to be pumped into the corresponding first through sixth main heater body via the first through sixth water inlet respectively, the condensate water passing through the corresponding first through sixth water inlet being arranged to be injected into the corresponding first through sixth heat exchange compartment via the first through the sixth injection nozzle respectively for creating a negative pressure in the first through sixth heat exchange compartment, the negative pressure drawing a predetermined amount of steam from the turbine assembly to enter the first through sixth heat exchange compartment via the first through the sixth steam inlet for mixing with the condensate water, the condensate water being heated up by the steam which is then condensed into water and arranged to be discharged out of the corresponding first through the sixth heat exchange compartment via the first through sixth water outlet. 
     Another aspect of the present invention provides an injection feedwater heater for a steam power generating system comprising a steam generator, a turbine assembly, an electric generator and a condenser, the injection feedwater heater comprising: 
     a main heater body having a heat exchange compartment, a water inlet, a steam inlet, and a water outlet formed on the main heater body; and 
     an injection nozzle provided in the main heater body at a position adjacent to the water inlet, wherein a predetermined amount of condensate water is arranged to be pumped into the main heater body through the water inlet, the condensate water passing through the water inlet being arranged to be injected into the heat exchange compartment through the injection nozzle for creating a negative pressure in the heat exchange compartment, the negative pressure drawing a predetermined amount of steam to enter the heat exchange compartment through the steam inlet for mixing with the condensate water, the condensate water being heated up by the steam which is then condensed into water and arranged to be discharged out of the heat exchange compartment through the water outlet. 
     This summary presented above is provided merely to introduce certain concepts and not to identify any key or essential features of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a steam power generating system according to a first preferred embodiment of the present invention. 
         FIG. 2  is a schematic view of an injection feedwater heater according to the first preferred embodiment of the present invention. 
         FIG. 3  is a schematic diagram of a water collection head according to the first preferred embodiment of the present invention. 
         FIG. 4  is an alternative configuration of the water collection head according to the first preferred embodiment of the present invention. 
         FIG. 5  is a sectional schematic view of an injection nozzle according to the first preferred embodiment of the present invention. 
         FIG. 6  is an alternative configuration of an injection nozzle according to the first preferred embodiment of the present invention. 
         FIG. 7  is a top schematic view of nozzle holes forming on a nozzle base according to the first preferred embodiment of the present invention. 
         FIG. 8  is an alternative configuration of nozzle holes forming on the nozzle base according to the first preferred embodiment of the present invention. 
         FIG. 9  is a schematic diagram of a first alternative mode of the injection feedwater heater according to the first preferred embodiment of the present invention. 
         FIG. 10  is a schematic diagram of a second alternative mode of the injection feedwater heater according to the first preferred embodiment of the present invention. 
         FIG. 11  is a schematic diagram of a third alternative mode of the injection feedwater heater according to the first preferred embodiment of the present invention. 
         FIG. 12  a schematic diagram of a fourth alternative mode of the injection feedwater heater according to the first preferred embodiment of the present invention. 
         FIG. 13  is a schematic diagram of a steam power generating system according to a second preferred embodiment of the present invention. 
         FIG. 14A  to  FIG. 14C  are schematic diagrams of first through third injection feedwater heater according to a second preferred embodiment of the present invention respectively. 
         FIG. 15  is a schematic diagram of a steam power generating system according to a third preferred embodiment of the present invention. 
         FIG. 16  is a schematic diagram of a steam power generating system according to a fourth preferred embodiment of the present invention. 
         FIG. 17  is a schematic diagram of a fourth injection feedwater heater according to the fourth preferred embodiment of the present invention. 
         FIG. 18  is a schematic diagram of a steam power generating system according to a fifth preferred embodiment of the present invention. 
         FIG. 19A  to  FIG. 19B  are schematic diagrams of fifth through sixth injection feedwater heater according to a fifth preferred embodiment of the present invention respectively. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following detailed description of the preferred embodiment is the preferred mode of carrying out the invention. The description is not to be taken in any limiting sense. It is presented for the purpose of illustrating the general principles of the present invention. 
     Referring to  FIG. 1  to  FIG. 7  of the drawings, a steam power generating system according a first preferred embodiment of the present invention is illustrated. Broadly, the steam power generating system may comprise a plurality of connecting pipes  101 , a steam generator  102 , a turbine assembly  300 , an electric generator  400 , a condenser  500 , and a feedwater preheat arrangement  1  which comprises at least one injection feedwater heater  10 . 
     The connecting pipes  101  may connect one of more components in the steam power generating system and may allow steam or water to pass therethrough. The steam generator  102  may be arranged to produce a predetermined amount of steam. The steam generator  102  may be configured as a boiler. 
     The turbine assembly  300  may comprise at least one turbine  310  and may be connected to the steam generator  102  through at least one of the connecting pipes  101 , wherein the steam generated by the steam generator  102  may be arranged to feed into and produce work on the turbine assembly  300 . 
     The electric generator  400  may be connected to the turbine assembly  300 , wherein the work produced in the turbine assembly  300  may be converted to a predetermined amount of electricity through turning the turbine  310 . 
     The condenser  500  may be connected to the turbine assembly  300  through at least one of the connecting pipes  101 , wherein the steam from the turbine assembly  300  may be guided to flow into the condenser  500  which may be arranged to condense the steam into condensate water. 
     The injection feedwater heater  10  may be connected to the condenser  500  and the turbine assembly  300  through at least one of the connecting pipes  101 , and may comprise a main heater body  11  and an injection nozzle  12 . 
     The main heater body  11  may have a heat exchange compartment  111 , a water inlet  112 , a steam inlet  113 , and a water outlet  114  formed on the main heater body  11 . 
     The injection nozzle  12  may be provided in the main heater body  11  at a position adjacent to the water inlet  112 , wherein a predetermined amount of the condensate water from the condenser  500  may be arranged to be pumped into the main heater body  11  through the water inlet  112 . The condensate water passing through the water inlet  112  may be arranged to be injected into the heat exchange compartment  111  through the injection nozzle  12  for creating a negative pressure in the heat exchange compartment  111 . The negative pressure may then draw a predetermined amount of steam from the turbine assembly  300  to enter the heat exchange compartment  111  through the steam inlet  113  for mixing with the condensate water. The condensate water may be heated up by the steam which is then condensed into water and arranged to be discharged out of the heat exchange compartment  111  through the water outlet  114 . 
     Thus, the feedwater preheat arrangement  1  may be provided between the steam generator  102  and the condenser  500  for preheating the condensate water from the condenser  500  before feeding to the steam generator  102 . 
     According to the first preferred embodiment of the present invention, the steam power generating system may operate in accordance with thermodynamics theories, such as following the heat exchange model predicted by Rankine cycle. The connecting pipes  101  may connect each of the elements of the steam power generating system which may be employed in a steam power plant. The steam generator  102  may be configured as a boiler which may heat up water by using a predetermined type of fuel. The water may be converted into superheated steam which may be guided to flow to the turbine assembly  300 . 
     The turbine assembly  300  may comprise at least one turbine  310  arranged in such a manner that the superheated steam produced by the steam generator  102  may be allowed to turn the turbine  310  for converting heat energy into mechanical energy. More than one turbine  310  may be employed according to different circumstances in which the present invention is utilized. 
     The electric generator  400  may be connected to the turbine assembly  300  and may be arranged to convert mechanical energy into electrical energy when the turbine  310  is turned. The electric generator  400  may be connected to other electrical components so that people may make further use of the electricity generated by the electric generator  400 . 
     The condenser  500  may be connected to the turbine assembly  300  wherein the steam used to turn the turbine  310  may be guided to flow into the condenser  500 . The steam flowing into the condenser  500  may be arranged to perform heat exchange with a predetermined heat exchange medium (such as water) so as to be condensed back into water (referred to “condensate water in this specification). Heat may be extracted from the steam, and condensate water may be arranged to flow out of the condenser  500 . The condensate water may be preheated by at least one injection feedwater heater  10  before being circulated back to the steam generator  102 . 
     The steam power generating system may further comprise at least one pumping device  70  connected to at least one of the connecting pipes  101  for pumping fluid flowing through the various components of the steam power generating system. In the first preferred embodiment, the steam power generating system may comprise two pumping devices  70  one of which may be connected between the injection feedwater heater  10  and the condenser  500 , while the other one may be connected between the injection feedwater heater  60  and the steam generator  102 . The pumping devices  70  may facilitate circulation of the condensate water from the condenser  500  to the steam generator  102 . 
     The injection feedwater heater  10  may be connected to the condenser  500  and the turbine assembly  300  so that the water coming out from the condenser  500  may be guided to flow into the injection feedwater heater  10 . At the same time, steam from the turbine assembly  300  may be guided to flow into the injection feedwater heater  60  to perform heat exchange with the condensate water. 
     Specifically, the water inlet  112  may be connected to the condenser  500  through at least one connecting pipe  101 . The condensate water coming from the condenser  500  may be guided to flow into the injection feedwater heater  10  through the water inlet  112 . In the first preferred embodiment of the present invention, the main heater body  11  may comprise a heat exchanging tube  115  and a water collection head  116  connected to the heat exchanging tube  115 , wherein the water inlet  112  may be formed on the water collection head  116  while the heat exchange compartment  111  may be formed in the heat exchanging tube  115 . The heat exchanging tube  115  may be configured as having an elongated structure and may be installed in vertical orientation. In this orientation, the water collection head  116  may be provided on top of the heat exchanging tube  115 , as shown in  FIG. 2  of the drawings. 
     The main heater body  11  may further comprise a water discharging tube  117  extended from the heat exchanging tube  115 , wherein the water outlet  114  may be formed on the water discharging tube  117 . Condensate water coming from the condenser  500  may sequentially pass through the water inlet  112 , the water collection head  116 , the heat exchanging tube  115 , the water discharging tube  117 , and the water outlet  114 . As shown in  FIG. 2  of the drawings, the water collection head  116  and the water discharging tube  117  may be provided on two opposite ends of the heat exchanging tube  115  respectively. Thus, when in vertical orientation, the water discharging tube  117  may be provided below the heat exchanging tube  115 . 
     Referring to  FIG. 3  of the drawings, the water collection head  116  may have a water collection chamber  1161 . The water inlet  112  may be formed on the water collection head  116  and may communicate with the water collection chamber  1161 . Condensate water from the condenser  500  may pass through the water inlet  112  and may be temporarily accommodated in the water collection chamber  1161  before passing through the injection nozzle  12 . Note that the water inlet  112  may be formed along a longitudinal axis of the heat exchanging tube  115  so as to substantially align therewith. Alternatively, the water inlet  112  may be formed substantially parallel to a transverse axis of the heat exchanging tube  115 , as shown in  FIG. 4  of the drawings. 
     The heat exchanging tube  115  may comprise an external tube member  1151  and an internal tube member  1152  for forming a double wall structure of the heat exchanging tube  115 . The steam inlet  113  may be formed on the external tube member  1151  of the heat exchanging tube  115 . A diameter of the internal tube member  1152  may be less than that of the external tube member  1151  so as to form a receiving gap  1153  between the external tube member  1151  and the internal tube member  1152 . The heat exchange compartment  111  may be formed inside the internal tube member  1152 . 
     Furthermore, the internal tube member  1152  may have a plurality of holes  1154  formed thereon for communicating the receiving gap  1153  with the heat exchange compartment  111 . Thus, steam from the turbine  310  may enter the heat exchanging tube  115  through the steam inlet  113 . The steam passing through the steam inlet  113  may be temporarily accommodated in the receiving gap  1153  and may eventually be guided to enter the heat exchange compartment  111  through the holes  1154 . In this preferred embodiment, each of the external tube member  1151  and the internal tube member  1152  may have a circular cross section. Other cross-sectional shapes may also be possible and should be covered and protected by the present patent. Similarly, each of the external tube member  1151  and the internal tube member  1152  may have a uniform diameter along a longitudinal axis thereof. However, non-uniform diameter along the longitudinal axis of each or both of the external tube member  1151  and the internal tube member  1152  may also be possible. 
     As shown in  FIGS. 2 and 5  of the drawings, the injection nozzle  12  may be provided between the water collection head  116  and the heat exchanging tube  115 . The injection nozzle  12  may comprise a nozzle base  121  and have a plurality of injection holes  122  formed on the nozzle base  121 , wherein the injection holes  122  may communicate the water collection chamber  1161  with the heat exchange compartment  111  so that water collected in the water collection chamber  1161  may be injected into the heat exchange compartment  111  through the injection holes  122 . 
     The two different configurations of the injection nozzle  12  may be illustrated in  FIG. 5  and  FIG. 6  of the drawings. As shown in  FIG. 5  of the drawings, the injection nozzle  12  may further comprise a plurality of nozzle units  123  wherein the injection holes  122  may be formed in the nozzle units  123  respectively. Each of the nozzle units  123  may have a nozzle head  1231  provided on the nozzle base  121 , and an elongated nozzle pin  1232  extending from the nozzle head  1231  and penetrating through the nozzle base  121 , wherein the corresponding injection hole  122  may extend along the nozzle head  1231  and the elongated nozzle pin  1232 . The injection hole  122  extending in the nozzle head  1231  may have a tapered cross-sectional shape. 
     Alternatively, as shown in  FIG. 6  of the drawings, the injection holes  122  may be formed directly on the nozzle base  121  so that water collection in the water collection chamber  1161  may be injected into the heat exchange compartment  111  through the injection holes  122  without passing through any nozzle units  123 . 
     Referring to  FIG. 7  to  FIG. 8  of the drawings, the nozzle base  121  may be configured to have a substantially circular cross section wherein the injection holes  122  may be spacedly formed on the nozzle base  121 . The exact distribution of the injection holes  122  or the injection units  123  forming on the nozzle base  121  may vary depending on the manufacturing or application circumstances of the case. For example,  FIG. 7  illustrates a radial projection of the nozzle holes  122  from the center of the nozzle base  121 . Thus, the nozzle holes  122  may be distributed on the nozzle base  121  along several imaginary projection lines radially extended from the center of the nozzle base  121 . In the case where nozzle units  123  are used, the nozzle units  123  may be distributed on the nozzle base  121  along several imaginary projection lines radially extended from the center of the nozzle base  121 . 
     As another example,  FIG. 8  illustrates that the nozzle holes  122  may be distributed on the nozzle base  121  randomly. The exact manner in which the nozzle holes  122  may be distributed depend on the manufacturing and operational circumstances of the present invention. 
     The water discharging tube  117  may extend from the heat exchanging tube  115  at a position opposite to the water collection head  116 . Thus, the water collection head  116  and the water discharging tube  117  may be provided on two opposite end portions of the heat exchanging tube  115  respectively. As shown in  FIG. 2  of the drawings, the water discharging tube  115  may extend from the internal tube member  1152  of the heat exchanging tube  115 . 
     The water discharging tube  117  may have a guiding portion  1171 , a pressurizing portion  1172 , and a buffering portion  1173  extended between the guiding portion  1171  and the pressurizing portion  1172 . The guiding portion  1171  may extend from the heat exchanging tube  115  and may have a diameter gradually decreasing from the heat exchanging tube  115  so as to form a tapered cross-section shape for collecting and guiding water flow in the guiding portion. 
     The pressurizing portion  1172  may extend from the buffering portion  1173  and may have a diameter gradually increasing from the buffering portion  1173  so that the water passing through the pressurizing portion  1172  may have increasing pressure but decreasing flow rate. 
     The injection feedwater heater  10  may further comprise a safety arrangement  14  provided on the heat exchanging tube  115  for preventing fluid, such as condensate water, from exiting the heat exchanging tube  115  and reaching the turbine  310  through the steam inlet  113 . 
     To accommodate the safety arrangement  14 , the main heater body  11  may further comprise a steam input tube  118  extending from the external tube member  1151 , wherein the steam inlet  113  may be formed in the steam input tube  118 . Thus, steam coming from the turbine  310  may flow into the heat exchanging tube  115  through the steam input tube  118  and the steam inlet  113 . On the other hand, the safety arrangement  14  may comprise a unidirectional valve  141  mounted in the steam input tube  118  for preventing water from exiting the heat exchanging tube  115  and reaching the turbine  310  through the steam inlet  113 . 
     The safety arrangement  14  may further comprise an electromagnetic valve  142  mounted in the steam input tube  118 , and a plurality of pressure sensors  143  provided in the internal tube member  1152  and the steam input tube  118  respectively for measuring the pressure in the internal tube member  1152  (i.e. the heat exchange compartment  111 ) and the steam input tube  118  respectively. The pressure sensors  143  may be electrically connected to the electromagnetic valve  142  so that when the pressure sensors  143  detect that the pressure in the steam input tube  118  is lower than that of the heat exchange compartment  111 , the electromagnetic valve  142  may be arranged to turn off the corresponding pumping device  70  for stopping condensate water from further feeding into the injection feedwater heater  10 . 
     The operation of the present invention is as follows: the steam power generating system may be utilized to generate electricity through applications of thermodynamics theories such as Rankin cycle. Water in the steam generator  102  may be heated to become superheated steam. The superheated steam may be guided to flow to the turbine assembly  300  so that the energy stored in the superheated steam may be used to turn one or more turbine  310 . The movement of the turbines  310  may be used to generate electricity by the electric generator  400 . 
     The steam leaving the turbine assembly  300  may be guided to flow into the condenser  500  which may condense the steam into condensate water. The condensate water may then be guided to leave the condenser  500  and enter the injection feedwater heater  10 . The purpose of feeding the water into the injection feedwater heater  10  is to preheat the condensate water to a predetermined temperature by using the heat from the steam extracted from the turbine assembly  300  so as to maximize the overall efficiency of the entire steam power generating system. The condensate water may then be guided to leave the injection feedwater heater  10  and flow back to the steam generator  102  for being converted back into superheated steam to perform another cycle of electricity generation in the manner described above. 
     In the injection feedwater heater  10 , condensate water may first be fed into the water collection head  116  through the water inlet  112 . The condensate water may then be temporarily collected in the water collection chamber  1161  and ready to pass through the injection nozzle  12 . The condensate water in the water collection chamber  1161  may then be injected into the heat exchange compartment  111  by the injection nozzle  12 . The injection of the condensate water in the heat exchange compartment  111  may create a negative pressure in the heat exchange compartment  111  which may tend to create a suction effect to the fluid staying out of the heat exchange compartment  111 . As a result, steam may be sucked into the heat exchanging tube  115  through the steam inlet  113 . The steam passing through the steam inlet  113  may go on to pass through the holes  1154  and eventually enter the heat exchange compartment  111 . The steam entering the heat exchange compartment  111  may be arranged to mix with the condensate water and perform heat exchange therewith. The result is that the condensate water may be “pre-heated” while the steam may be condensed in the heat exchange compartment  111  after performing heat exchange with the condensate water. 
     The resulting product which is also water may be guided to sequentially pass through the guiding portion  1171 , the buffering portion  1173  and the pressurizing portion  1172  of the water discharging tube  117 . The water passing through the water discharging tube  117  may be guided to leave the injection feedwater heater  10  through the water outlet  114 . The water leaving the injection feedwater heater  10  may be guided to flow back to the steam generator  102  in the manner described above. 
     Referring to  FIG. 9  of the drawings, a first alternative mode of the injection feedwater heater  10 ′ according to the first preferred embodiment of the present invention is illustrated. The first alternative mode is similar to the injection feedwater heater  10  described above, except that the injection feedwater heater  10 ′ may be designed primarily for use in a horizontal orientation. 
     In the first alternative mode, the main heater body  11 ′ may comprise a heat exchanging tube  115 ′ and a water collection head  116 ′ connected to the heat exchanging tube  115 ′, wherein the water inlet  112 ′ may be formed on the water collection head  116 ′ while the heat exchange compartment  111 ′ may be formed in the heat exchanging tube  115 ′. The heat exchanging tube  115 ′ may also be configured as having an elongated structure. 
     The main heater body  11 ′ may further comprise a water discharging tube  117 ′ extended from the heat exchanging tube  115 ′, wherein the water outlet  114 ′ may be formed on the water discharging tube  117 ′. Condensate water coming from the condenser  500  may sequentially pass through the water inlet  112 ′, the water collection head  116 ′, the heat exchanging tube  115 ′, the water discharging tube  117 ′, and the water outlet  114 ′. As shown in  FIG. 9  of the drawings, the water collection head  116 ′ and the water discharging tube  117 ′ may be provided on two opposite ends of the heat exchanging tube  115 ′ respectively. Moreover, one end portion  1155 ′ of the heat exchanging tube  115 ′ may be inclined with respect to longitudinal axis thereof. 
     As in the first preferred embodiment, the water collection head  116 ′ may have a water collection chamber  1161 ′. The water inlet  112 ′ may be formed on the water collection head  116 ′ and may communicate with the water collection chamber  1161 ′. The water inlet  112 ′ may be formed along a longitudinal axis of the heat exchanging tube  115 ′ so as to substantially align therewith. 
     The heat exchanging tube  115 ′ may comprise an external tube member  1151 ′ and an internal tube member  1152 ′ for forming a double wall structure of the heat exchanging tube  115 ′. The steam inlet  113 ′ may be formed on the external tube member  1151 ′ of the heat exchanging tube  115 ′. A diameter of the internal tube member  1152 ′ may be less than that of the external tube member  1151 ′ so as to form a receiving gap  1153 ′ between the external tube member  1151 ′ and the internal tube member  1152 ′. The heat exchange compartment  111 ′ may be formed inside the internal tube member  1152 ′. 
     Furthermore, the internal tube member  1152 ′ may have a plurality of holes  1154 ′ formed thereon for communicating the receiving gap  1153 ′ with the heat exchange compartment  111 ′. The heat exchanging tube  115 ′ may further have a water release port  1156 ′ formed on the external tube member  1151 ′ for allowing residual water to be discharged out of the receiving gap  1153 ′. 
     Again, the injection nozzle  12 ′ may be provided between the water collection head  116 ′ and the heat exchanging tube  115 ′. The injection nozzle  12 ′ comprise a nozzle base  121 ′ and have a plurality of injection holes  122 ′ formed on the nozzle base  121 ′, wherein the injection holes  122 ′ may communicate the water collection chamber  1161 ′ with the heat exchange compartment  111 ′ so that water collected in the water collection chamber  1161 ′ may be injected into the heat exchange compartment  111 ′ through the injection holes  122 ′. 
     The water discharging tube  117 ′ may also extend from the heat exchanging tube  115 ′ at a position opposite to the water collection head  116 ′. The water discharging tube  117 ′ may extend from the internal tube member  1152 ′ of the heat exchanging tube  115 ′. 
     The water discharging tube  117 ′ may have a guiding portion  1171 ′, a pressurizing portion  1172 ′, and a buffering portion  1173 ′ extended between the guiding portion  6171 ′ and the pressurizing portion  1172 ′. The guiding portion  1171 ′ may extend from the heat exchanging tube  115 ′ and may have a diameter gradually decreasing from the heat exchanging tube  115 ′ so as to form a tapered cross-section shape for collecting and guiding water flow in the guiding portion. 
     Note that in this first alternative mode, the guiding portion  1171 ′ may have an inclined guiding surface  1174 ′ wherein the water coming from the heat exchanging tube  115 ′ may be arranged to hit the inclined guiding surface  1174 ′ and be guided to flow to the buffering portion  1173 ′. 
     The pressurizing portion  1172 ′ may extend from the buffering portion  1173 ′ and may have a diameter gradually increasing from the buffering portion  1173 ′ so that the water passing through the pressurizing portion  1172 ′ may have increasing pressure but decreasing flow rate. 
     The injection feedwater heater  10 ′ may further comprise a safety arrangement  14 ′ provided on the heat exchanging tube  115 ′ for preventing fluid, such as condensate water, from exiting the heat exchanging tube  115 ′ and reaching the turbine  310  through the steam inlet  113 ′. As in the preferred embodiment, the main heater body  11 ′ may further comprise a steam input tube  118 ′ extending from the external tube member  1151 ′, wherein the steam inlet  113 ′ is formed in the steam input tube  118 ′. Thus, steam coming from the turbine  310  may flow into the heat exchanging tube  115 ′ through the steam input tube  118 ′ and the steam inlet  113 ′. On the other hand, the safety arrangement  14 ′ may comprise a unidirectional valve  141 ′ mounted in the steam input tube  118 ′ for preventing water from exiting the heat exchanging tube  115 ′ and reaching the turbine  310  through the steam inlet  113 ′. 
     The safety arrangement  14 ′ may further comprise an electromagnetic valve  142 ′ mounted on the steam inlet  113 ′, and a plurality of pressure sensors  143 ′ provided in the internal tube member  1152 ′ and the steam input tube  118 ′ respectively for measuring the pressure in the internal tube member  1152 ′ and the steam input tube  118 ′ respectively. The operation of the safety arrangement  14 ′ is the same as that mentioned in the preferred embodiment above. 
     Referring to  FIG. 10  of the drawings, a second alternative mode of the injection feedwater heater  60 ″ according to the preferred embodiment of the present invention is illustrated. The second alternative mode is similar to the injection feedwater heater  10 ′ described in the first alternative mode, except that the heat exchanging tube  115 ″ of the injection feedwater heater  10 ″ may have a curved portion  1157 ″ formed adjacent to the guiding portion  1171 ″ of the water discharging tube  117 ″. 
     The water discharging tube  117 ″ may have a guiding portion  1171 ″, a pressurizing portion  1172 ″, and a buffering portion  1173 ″ extended between the guiding portion  1171 ″ and the pressurizing portion  1172 ″. The guiding portion  1171 ″ may extend from the heat exchanging tube  115 ″ and may have a diameter gradually decreasing from the heat exchanging tube  115 ″ so as to form a tapered cross-section shape for collecting and guiding water flow in the guiding portion. In this second alternative mode, the guiding portion  1171 ″ may also have an inclined guiding surface  1174 ″ wherein the water coming from the heat exchanging tube  115 ″ may be arranged to hit the inclined guiding surface  1174 ″ and be guided to flow to the buffering portion  1173 ″. 
     The pressurizing portion  1172 ″ may extend from the buffering portion  1173 ″ and may have a diameter gradually increasing from the buffering portion  1173 ″ so that the water passing through the pressurizing portion  1172 ″ may have increasing pressure but decreasing flow rate. 
     The injection feedwater heater  12 ″ may further comprise a safety arrangement  14 ″ provided on the heat exchanging tube  115 ″ for preventing fluid, such as condensate water, from exiting the heat exchanging tube  115 ″ and reaching the turbine  310  through the steam inlet  113 ″. As in the preferred embodiment, the main heater body  11 ″ may further comprise a steam input tube  118 ″ extending from the external tube member  1151 ″, wherein the steam inlet  113 ″ may be formed in the steam input tube  118 ″. On the other hand, the safety arrangement  14 ″ may comprise a unidirectional valve  141 ″ mounted in the steam input tube  118 ″ for preventing water from exiting the heat exchanging tube  115 ″ and reaching the turbine  310  through the steam inlet  113 ″. 
     The safety arrangement  14 ″ may further comprise an electromagnetic valve  142 ″ mounted on the steam inlet  113 ″, and a plurality of pressure sensors  143 ″ provided in the internal tube member  1152 ″ and the steam input tube  118 ″ respectively for measuring the pressure in the internal tube member  1152 ″ and the steam input tube  118 ″ respectively. The operation of the safety arrangement  14 ″ is the same as that mentioned in the preferred embodiment and the first alternative mode above. 
     The injection feedwater heater  10 ″ may also comprise a water collection head  116 ″ having a water collection chamber  1161 ″. The water inlet  112 ″ may be formed on the water collection head  116 ″ and may communicate with the water collection chamber  1161 ″. The water inlet  112 ″ may be formed along a longitudinal axis of the heat exchanging tube  115 ″ so as to substantially align therewith. 
     Moreover, the steam inlet  113 ″ may be formed on the external tube member  1151 ″ of the heat exchanging tube  115 ″. A diameter of the internal tube member  1152 ″ may be less than that of the external tube member  1151 ″ so as to form a receiving gap  1153 ″ between the external tube member  1151 ″ and the internal tube member  1152 ″. The heat exchange compartment  111 ″ may be formed inside the internal tube member  1152 ″. 
     Furthermore, the internal tube member  1152 ″ may have a plurality of holes  1154 ″ formed thereon for communicating the receiving gap  1153 ″ with the heat exchange compartment  111 ″. The heat exchanging tube  115 ″ may further have a water release port  1156 ″ formed on the external tube member  1151 ″ for allowing residual water to be discharged out of the receiving gap  1153 ″. 
     The injection nozzle  12 ″ may be provided between the water collection head  116 ″ and the heat exchanging tube  115 ″. The injection nozzle  12 ″ comprise a nozzle base  121 ″ and have a plurality of injection holes  122 ″ formed on the nozzle base  121 ″. 
     Referring to  FIG. 11  of the drawings, a third alternative mode of the injection feedwater heater  10 A according to the first preferred embodiment of the present invention is illustrated. The third alternative mode is structurally identical to the injection feedwater heater  10 ′ described in the first alternative mode, except that the both ends  1155 A of the heat exchanging tube  115 A may not be inclined with respect to longitudinal axis thereof. 
     Moreover, in this third alternative mode, the inclined guiding surface  1174 A may also be formed in the guiding portion  1171 A of the water discharging tube  117 A. Water passing through the guiding portion  1171 A may sequentially pass through the buffering portion  1173 A and the pressurizing portion  1172 A. 
     The water release port  1156 A may be formed on the external tube member  1151 A for allowing residual water to be discharged out of the receiving gap  1153 A, which is formed between the external tube member  1151 A and the internal tube member  1152 A. The holes  1154 A may be formed on the internal tube member  1152 A. Moreover, the injection nozzle  12 A may be provided between the water collection head  116 A and the heat exchanging tube  115 A. The injection nozzle  12 A may comprise a nozzle base  121 A and have a plurality of injection holes  122 A formed on the nozzle base  121 A. The water collection chamber  1161 A may communicate with the water inlet  112 A. 
     The safety arrangement  14 A may comprise an electromagnetic valve  142 A mounted on the steam inlet  113 A, and a plurality of pressure sensors  143 A provided in the internal tube member  1152 A and the steam input tube  118 A respectively for measuring the pressure in the internal tube member  1152 A and the steam input tube  118 A respectively. The operation of the safety arrangement  14 A is the same as that mentioned in the preferred embodiment and the first alternative mode above. 
     Referring to  FIG. 12  of the drawings, a fourth alternative mode of the injection feedwater heater  10 B according to the first preferred embodiment of the present invention is illustrated. The fourth alternative mode is structurally identical to the injection feedwater heater  10 ′ described in the third alternative mode, except the water discharging tube  117 B. 
     According to the fourth alternative mode, the water discharging tube  117 B may have a guiding portion  1171 B, a pressurizing portion  1172 B, and a buffering portion  1173 B extended between the guiding portion  1171 B and the pressurizing portion  1172 B. The guiding portion  1171 B may extend from the heat exchanging tube  115 B and may have a diameter gradually decreasing from the heat exchanging tube  115 B. In this fourth alternative mode, the guiding portion  1171 B may also have an inclined guiding surface  1174 B wherein the water coming from the heat exchanging tube  115 B may be arranged to hit the inclined guiding surface  1174 B and be guided to flow to the buffering portion  1173 B. 
     In this fourth alternative mode, the guiding portion  1171 B may extend from the internal tube member  1152 B along a longitudinal direction thereof, while the buffering portion  1173 B and the pressurizing portion  1172 B may extend from the guiding portion  1171 B along a transverse direction thereof. In other words, a longitudinal axis of the buffering portion  1173 B and the pressurizing portion  1172 B may form an approximately 90° of inclination with respect to a longitudinal axis of the guiding portion  1171 B. This configuration is graphically depicted in  FIG. 12  of the drawings. 
     On the other hand, the water release port  1156 B may be formed on the external tube member  1151 B for allowing residual water to be discharged out of the receiving gap  1153 B, which is formed between the external tube member  1151 B and the internal tube member  1152 B. The holes  1154 B may be formed on the internal tube member  1152 B. Moreover, the injection nozzle  12 B may be provided between the water collection head  116 B and the heat exchanging tube  115 B. The injection nozzle  12 B may comprise a nozzle base  121 B and have a plurality of injection holes  122 B formed on the nozzle base  121 B. The water collection chamber  1161 B may communicate with the water inlet  112 B. 
     The safety arrangement  14 B may comprise an electromagnetic valve  142 B mounted on the steam inlet  113 B, and a plurality of pressure sensors  143 B provided in the internal tube member  1152 B and the steam input tube  118 B respectively for measuring the pressure in the internal tube member  1152 B and the steam input tube  118 B respectively. The operation of the safety arrangement  14 B is the same as that mentioned in the preferred embodiment and the first alternative mode above. 
     Referring to  FIG. 13 , and  FIG. 14A  to  FIG. 14C  of the drawings, a steam power generating system according to a second preferred embodiment of the present invention is illustrated. The second preferred embodiment is similar to what has been disclosed in the first preferred embodiment except the configuration of the various components of the steam power generating system. According to the second preferred embodiment of the present invention, the feedwater preheat arrangement  1 C may comprise first through third injection feedwater heater  10 C,  20 C,  30 C connected in parallel by the connecting pipes  101 C, wherein the first through third injection feedwater heater  10 C,  20 C,  30 C may be connected to the turbine assembly  300 C (comprising at least one turbine  310 C) and the steam generator  102 C. Each of the first through third injection feedwater heater  10 C,  20 C,  30 C may be structurally identical, or may be a combination of the above-disclosed variation of the injection feedwater heater. The first through third injection feedwater heater  10 C,  20 C,  30 C may be structurally identical to those disclosed in the first preferred embodiment above. 
     Thus, the first through third injection feedwater heater  10 C,  20 C,  30 C may be connected to the condenser  500 B and the turbine assembly  300 C through at least one of the connecting pipes  101 C. A total of four pumping devices  70 C may be utilized in the second preferred embodiment. The turbine assembly  300 C may be connected to an electric generator  400 C. 
     As shown in  FIG. 14A  of the drawings, the first injection feedwater heater  10 C may comprise a first main heater body  11 C and a first injection nozzle  12 C. The first main heater body  11 C may have a first heat exchange compartment  111 C, a first water inlet  112 C, a first steam inlet  113 C, and a first water outlet  114 C formed on the first main heater body  11 C. 
     The first injection nozzle  12 C may be provided in the first main heater body  11 C at a position adjacent to the first water inlet  112 C, wherein a predetermined amount of the condensate water from the condenser  500 C may be arranged to be pumped into the first main heater body  11 C through the first water inlet  112 C. The condensate water passing through the first water inlet  112 C may be arranged to be injected into the first heat exchange compartment  111 C through the first injection nozzle  12 C for creating a negative pressure in the first heat exchange compartment  111 C. The negative pressure may then draw a predetermined amount of steam from the turbine assembly  300 C to enter the first heat exchange compartment  111 C through the steam inlet  113 C for mixing with the condensate water. The condensate water may be heated up by the steam which is then condensed into water and arranged to be discharged out of the first heat exchange compartment  111 C through the first water outlet  114 C. 
     The first main heater body  11 C may comprise a first heat exchanging tube  115 C and a first water collection head  116 C connected to the first heat exchanging tube  115 C, wherein the first water inlet  112 C may be formed on the first water collection head  116 C while the first heat exchange compartment  111 C may be formed in the first heat exchanging tube  115 C. 
     The first main heater body  11 C may further comprise a first water discharging tube  117 C extended from the first heat exchanging tube  115 C, wherein the first water outlet  114 C may be formed on the first water discharging tube  117 C. Condensate water coming from the condenser  500 B may sequentially pass through the first water inlet  112 C, the first water collection head  116 C, the first heat exchanging tube  115 C, the first water discharging tube  117 C, and the first water outlet  114 C. 
     The first water collection head  116 C may have a first water collection chamber  1161 C. The first water inlet  112 C may be formed on the first water collection head  116 C and may communicate with the first water collection chamber  1161 C. The first heat exchanging tube  115 C may comprise a first external tube member  1151 C and a first internal tube member  1152 C for forming a double wall structure of the first heat exchanging tube  115 C. The first steam inlet  113 C may be formed on the first external tube member  1151 C of the first heat exchanging tube  115 C. A diameter of the first internal tube member  1152 C may be less than that of the first external tube member  1151 C so as to form a first receiving gap  1153 C between the first external tube member  1151 C and the first internal tube member  1152 C. The first heat exchange compartment  111 C may be formed inside the first internal tube member  1152 C. 
     The first internal tube member  1152 C may have a plurality of first holes  1154 C formed thereon for communicating the first receiving gap  1153 C with the first heat exchange compartment  111 C. Thus, steam from the turbine  310 C may enter the first heat exchanging tube  115 C through the first steam inlet  113 C. 
     The first injection nozzle  12 C may be provided between the first water collection head  116 C and the first heat exchanging tube  115 C. The first injection nozzle  12 C comprise a first nozzle base  121 C and have a plurality of first injection holes  122 C formed on the first nozzle base  121 C, wherein the first injection holes  122 C may communicate the first water collection chamber  1161 C with the first heat exchange compartment  111 C so that water collected in the first water collection chamber  1161 C may be injected into the first heat exchange compartment  111 C through the first injection holes  122 C. 
     The first water discharging tube  117 C may have a first guiding portion  1171 C, a first pressurizing portion  1172 C, and a first buffering portion  1173 C extended between the first guiding portion  1171 C and the first pressurizing portion  1172 C. The first guiding portion  1171 C may extend from the first heat exchanging tube  115 C and may have a diameter gradually decreasing from the first heat exchanging tube  115 C so as to form a tapered cross-section shape for collecting and guiding water flow in the guiding portion. 
     The first pressurizing portion  1172 C may extend from the first buffering portion  1173 C and may have a diameter gradually increasing from the first buffering portion  1173 C so that the water passing through the first pressurizing portion  1172 C may have increasing pressure but decreasing flow rate. 
     The first injection feedwater heater  12 C may further comprise a first safety arrangement  14 C provided on the first heat exchanging tube  115 C for preventing fluid, such as condensate water, from exiting the first heat exchanging tube  115 C and reaching the turbine  310 B through the first steam inlet  113 C. 
     The first main heater body  11 C may further comprise a first steam input tube  118 C extending from the first external tube member  1151 C, wherein the first steam inlet  113 C may be formed in the first steam input tube  118 C. The first safety arrangement  14 C may comprise a first unidirectional valve  141 C mounted in the first steam input tube  118 C for preventing water from exiting the first heat exchanging tube  115 C and reaching the turbine  310 B through the first steam inlet  113 C. 
     The first safety arrangement  14 C may further comprise a first electromagnetic valve  142 C mounted on the first steam inlet  113 C, and a plurality of first pressure sensors  143 C provided in the first internal tube member  1152 C and the first steam input tube  118 C respectively for measuring the pressure in the first internal tube member  1152 C and the first steam input tube  118 C respectively. The first pressure sensors  143 C may be electrically connected to the first electromagnetic valve  142 C so that when the first pressure sensors  143 C detect that the pressure in the first steam input tube  118 C is lower than that of the first heat exchange compartment  111 C, the first electromagnetic valve  142 C may be arranged to turn off the corresponding pumping device  70 B for stopping condensate water from further feeding into the first injection feedwater heater  10 C. 
     As shown in  FIG. 14B  of the drawings, the second injection feedwater heater  20 C may comprise a second main heater body  21 C and a second injection nozzle  22 C. The second main heater body  21 C may have a second heat exchange compartment  211 C, a second water inlet  212 C, a second steam inlet  213 C, and a second water outlet  214 C formed on the second main heater body  21 C. 
     The second injection nozzle  22 C may be provided in the second main heater body  21 C at a position adjacent to the second water inlet  212 C, wherein a predetermined amount of the condensate water from the condenser  500 C may be arranged to be pumped into the second main heater body  21 C through the second water inlet  212 C. 
     The second main heater body  21 C may comprise a second heat exchanging tube  215 C and a second water collection head  216 C connected to the second heat exchanging tube  215 C, wherein the second water inlet  212 C may be formed on the second water collection head  216 C while the second heat exchange compartment  211 C may be formed in the second heat exchanging tube  215 C. 
     The second main heater body  21 C may further comprise a second water discharging tube  217 C extended from the second heat exchanging tube  215 C, wherein the second water outlet  214 C may be formed on the second water discharging tube  217 C. Condensate water coming from the condenser  500 C may sequentially pass through the second water inlet  212 C, the second water collection head  216 C, the second heat exchanging tube  215 C, the second water discharging tube  217 C, and the second water outlet  214 C. 
     The second water collection head  216 C may have a second water collection chamber  2161 C. The second water inlet  212 C may be formed on the second water collection head  216 C and may communicate with the second water collection chamber  2161 C. The second heat exchanging tube  215 C may comprise a second external tube member  2151 C and a second internal tube member  2152 C for forming a double wall structure of the second heat exchanging tube  215 C. The second steam inlet  213 C may be formed on the second external tube member  2151 C of the second heat exchanging tube  215 C. A diameter of the second internal tube member  2152 C may be less than that of the second external tube member  2151 C so as to form a second receiving gap  2153 C between the second external tube member  2151 C and the second internal tube member  2152 C. The second heat exchange compartment  211 C may be formed inside the second internal tube member  2152 C. 
     The second internal tube member  2152 C may have a plurality of second holes  2154 C formed thereon for communicating the second receiving gap  2153 C with the second heat exchange compartment  211 C. Thus, steam from the turbine  310 C may enter the second heat exchanging tube  215 C through the second steam inlet  213 C. 
     The second injection nozzle  22 C may be provided between the second water collection head  216 C and the second heat exchanging tube  215 C. The second injection nozzle  22 C comprise a second nozzle base  221 C and have a plurality of second injection holes  222 C formed on the second nozzle base  221 C, wherein the second injection holes  222 C may communicate the second water collection chamber  2161 C with the second heat exchange compartment  211 C so that water collected in the second water collection chamber  2161 C may be injected into the second heat exchange compartment  211 C through the second injection holes  222 C. 
     The second water discharging tube  217 C may have a second guiding portion  2171 C, a second pressurizing portion  2172 C, and a second buffering portion  2173 C extended between the second guiding portion  2171 C and the second pressurizing portion  2172 C. The second guiding portion  2171 C may extend from the second heat exchanging tube  215 C and may have a diameter gradually decreasing from the second heat exchanging tube  215 C so as to form a tapered cross-section shape for collecting and guiding water flow in the guiding portion. 
     The second pressurizing portion  2172 C may extend from the second buffering portion  2173 C and may have a diameter gradually increasing from the second buffering portion  2173 C so that the water passing through the second pressurizing portion  2172 C may have increasing pressure but decreasing flow rate. 
     The second injection feedwater heater  22 C may further comprise a second safety arrangement  24 C provided on the second heat exchanging tube  215 C for preventing fluid, such as condensate water, from exiting the second heat exchanging tube  215 C and reaching the turbine  310 C through the second steam inlet  213 C. 
     The second main heater body  21 C may further comprise a second steam input tube  218 C extending from the second external tube member  2151 C, wherein the second steam inlet  213 C may be formed in the second steam input tube  218 C. The second safety arrangement  24 C may comprise a second unidirectional valve  241 C mounted in the second steam input tube  218 C for preventing water from exiting the second heat exchanging tube  215 C and reaching the turbine  310 C through the second steam inlet  213 C. 
     The second safety arrangement  24 C may further comprise a second electromagnetic valve  242 C mounted on the second steam inlet  213 C, and a plurality of second pressure sensors  243 C provided in the second internal tube member  2152 C and the second steam input tube  218 C respectively for measuring the pressure in the second internal tube member  2152 C and the second steam input tube  218 C respectively. The second pressure sensors  243 C may be electrically connected to the second electromagnetic valve  242 C so that when the second pressure sensors  243 C detect that the pressure in the second steam input tube  218 C is lower than that of the second heat exchange compartment  211 C, the second electromagnetic valve  242 C may be arranged to turn off the corresponding pumping device  70 C. 
     As shown in  FIG. 14C  of the drawings, the third injection feedwater heater  30 C may comprise a third main heater body  31 C and a third injection nozzle  32 C. The third main heater body  31 C may have a third heat exchange compartment  311 C, a third water inlet  312 C, a third steam inlet  313 C, and a third water outlet  314 C formed on the third main heater body  31 C. 
     The third injection nozzle  32 C may be provided in the third main heater body  31 C at a position adjacent to the third water inlet  312 C, wherein a predetermined amount of the condensate water from the condenser  500 C may be arranged to be pumped into the third main heater body  31 C through the third water inlet  312 C. The condensate water passing through the third water inlet  312 C may be arranged to be injected into the third heat exchange compartment  311 C through the third injection nozzle  32 C for creating a negative pressure in the third heat exchange compartment  311 B. The negative pressure may then draw a predetermined amount of steam from the turbine assembly  300 C to enter the third heat exchange compartment  311 C through the steam inlet  313 C for mixing with the condensate water. The condensate water may be heated up by the steam which is then condensed into water and arranged to be discharged out of the third heat exchange compartment  311 C through the third water outlet  314 C. 
     The third main heater body  31 C may comprise a third heat exchanging tube  315 C and a third water collection head  316 C connected to the third heat exchanging tube  315 B, wherein the third water inlet  312 C may be formed on the third water collection head  316 C while the third heat exchange compartment  311 C may be formed in the third heat exchanging tube  315 B. 
     The third main heater body  31 C may further comprise a third water discharging tube  317 C extended from the third heat exchanging tube  315 C, wherein the third water outlet  314 C may be formed on the third water discharging tube  317 C. 
     The third water collection head  316 C may have a third water collection chamber  3161 C. The third water inlet  312 C may be formed on the third water collection head  316 C and may communicate with the third water collection chamber  3161 C. The third heat exchanging tube  315 C may comprise a third external tube member  3151 C and a third internal tube member  3152 C for forming a double wall structure of the third heat exchanging tube  315 C. The third steam inlet  313 C may be formed on the third external tube member  3151 C of the third heat exchanging tube  315 C. A third receiving gap  3153 C may be formed between the third external tube member  3151 C and the third internal tube member  3152 C. The third heat exchange compartment  311 C may be formed inside the third internal tube member  3152 C. 
     The third internal tube member  3152 C may have a plurality of third holes  3154 C formed thereon for communicating the third receiving gap  3153 C with the third heat exchange compartment  311 C. Thus, steam from the turbine  310 C may enter the third heat exchanging tube  315 C through the third steam inlet  313 C. 
     Again, the third injection nozzle  32 C may be provided between the third water collection head  316 C and the third heat exchanging tube  315 C. The third injection nozzle  32 C comprise a third nozzle base  321 C and have a plurality of third injection holes  322 C formed on the third nozzle base  321 C. 
     The third water discharging tube  317 C may have a third guiding portion  3171 C, a third pressurizing portion  3172 C, and a third buffering portion  3173 C extended between the third guiding portion  3171 C and the third pressurizing portion  3172 C. The third guiding portion  3171 C may extend from the third heat exchanging tube  315 C and may have a diameter gradually decreasing from the third heat exchanging tube  315 C so as to form a tapered cross-section shape for collecting and guiding water flow in the guiding portion. The third pressurizing portion  3172 C may extend from the third buffering portion  3173 C and may have a diameter gradually increasing from the third buffering portion  3173 C so that the water passing through the third pressurizing portion  3172 C may have increasing pressure but decreasing flow rate. 
     The third injection feedwater heater  32 C may further comprise a third safety arrangement  34 C provided on the third heat exchanging tube  315 C for preventing fluid, such as condensate water, from exiting the third heat exchanging tube  315 C and reaching the turbine  310 C through the third steam inlet  313 C. 
     The third main heater body  31 C may further comprise a third steam input tube  318 C extending from the third external tube member  3151 C, wherein the third steam inlet  313 C is formed in the third steam input tube  318 B. The third safety arrangement  34 C may comprise a third unidirectional valve  341 C mounted in the third steam input tube  318 C for preventing water from exiting the third heat exchanging tube  315 C and reaching the turbine  310 C through the third steam inlet  313 C. 
     Moreover, the third safety arrangement  34 C may further comprise a third electromagnetic valve  342 C mounted on the third steam inlet  313 C, and a plurality of third pressure sensors  343 C provided in the third internal tube member  3152 C and the third steam input tube  318 C respectively for measuring the pressure in the third internal tube member  3152 C and the third steam input tube  318 C respectively. The third pressure sensors  343 C may be electrically connected to the third electromagnetic valve  342 C so that when the third pressure sensors  343 C detect that the pressure in the third steam input tube  318 C is lower than that of the third heat exchange compartment  311 C, the third electromagnetic valve  342 C may be arranged to turn off the corresponding pumping device  70 C for stopping condensate water from further feeding into the third injection feedwater heater  30 C. 
     Referring back to  FIG. 13  of the drawings, the first through third injection feedwater heaters  10 C,  20 C,  30 C are connected in parallel so that condensate water from the condenser  500 C may be guided to flow into the first through third injection feedwater heaters  10 C,  20 C,  30 C simultaneously while at the same time, the steam from the turbine assembly  300 C may also be fed into the first through third injection feedwater heaters  10 C,  20 C,  30 C through the first through third steam inlets  113 C,  213 C,  313 C. 
     Each of the first water outlet  114 C, second water outlet  214 C and the third water outlet  314 C may be connected to a pumping device  70 C. The water from the first through third water outlet  114 C,  214 C,  314 C may be collected and guided to flow back to the steam generator  102 C. Note that the first through third injection feedwater heater  10 C,  20 C,  30 C may be structurally identical, or may take the form of any of the variations or alternatives described above. Thus, the first through third injection feedwater heater  10 C,  20 C,  30 C may be placed vertically, horizontally, or a combination thereof. 
     Referring to  FIG. 145  of the drawings, a steam power generating system according to a third preferred embodiment of the present invention is illustrated. The third preferred embodiment is similar to the second preferred embodiment described above, except the configuration various components of the feedwater preheat arrangement  1 D. 
     According to the third preferred embodiment of the present invention, the steam power generating system may also comprise a steam generator  102 D, a turbine assembly  300 D comprising at least one turbine  310 D, an electric generator  400 D electrically connected to the turbine assembly  300 D, a condenser  500 D connected to the turbine assembly  300 D, and the feedwater preheat arrangement  1 D. The feedwater preheat arrangement  1 D may comprise first through third injection feedwater heater  10 C,  20 C,  30 C. Two pumping devices  70 D may be used in the third preferred embodiment. The various components may also be connected by a plurality of connecting pipes  101 D. These components are structurally identical to those described in the first and the second preferred embodiment above. 
     Referring to  FIG. 145  of the drawings, the steam generator  102 D may be connected to the turbine assembly  300 D so that superheated steam may be used to turn at least one turbine  310 D. The mechanical energy may be converted into electrical energy through the electric generator  400 D 
     The turbine assembly  300 D may be connected to the condenser  500 D for condensing the steam coming from the turbine assembly  300 D. At the same time, the turbine assembly  300 D may also be connected to each of the first through third injection feedwater heater  10 C,  20 C,  30 C so that steam may be arranged to enter the respective heat exchange compartment  111 C ( 211 C) ( 311 C). The condenser  500 D may be connected to a pumping device  70 D which may then be connected to the first injection feedwater heater  10 C. 
     The steam power generating system may further comprise a deaerator  100 D connected to the first injection feedwater heater  10 C so that the condensate water coming out from the first injection feedwater heater  10 C may be arranged to enter the deaerator  100 D. The deaerator  100 D may be utilized to remove a certain amount of oxygen from the condensate water coming out from the first injection feedwater heater  10 C. The deaerator  100 D may also be connected to the turbine assembly  300 D so that steam may also be arranged to enter the deaerator  100 D. 
     The deaerator  100 D may be connected to another pumping device  70 D which may be connected to the second injection feedwater heater  20 C. The second injection feedwater heater  20 C may be connected to the third injection feedwater heater  30 C in series. Finally, the third injection feedwater heater  30 C may be connected to the steam generator  102 D. 
     Thus, the water from the deaerator  100 D may be guided to flow into the second injection feedwater heater  20 C for further heating. The water coming out from the second injection feedwater heater  20 C may be guided to flow into the third injection feedwater heater  30 C for further heating. After that, the water coming out from the third injection feedwater heater  30 C may be guided to flow back to the steam generator  102 D for being converted back to superheated steam to perform another cycle of electricity generation. 
     In the third preferred embodiment, each of the first through third injection feedwater heater  10 C,  20 C,  30 C may be configured to have an identical structure as that described in the second preferred embodiment or the various alternative modes above, or a combination thereof. 
     Referring to  FIG. 15  to  FIG. 16  of the drawings, a steam power generating system according to a fourth preferred embodiment of the present invention is illustrated. The fourth preferred embodiment is similar to the third preferred embodiment described above, except the configuration various components of the steam power generating system. Moreover, the feedwater preheat arrangement  1 E may further comprise a fourth injection feedwater heater  40 D. The fourth injection feedwater heater  40 D may have identical structure as that of the first through third injection feedwater heater  10 C,  20 C,  30 C described above. 
     As shown in  FIG. 16  of the drawings, the fourth injection feedwater heater  40 D may comprise a fourth main heater body  41 D and a fourth injection nozzle  42 D. The fourth main heater body  41 D may have a fourth heat exchange compartment  411 D, a fourth water inlet  412 C, a fourth steam inlet  413 D, and a fourth water outlet  414 D formed on the fourth main heater body  41 D. 
     The fourth injection nozzle  42 D may be provided in the fourth main heater body  41 D at a position adjacent to the fourth water inlet  412 D, wherein a predetermined amount of the condensate water from the condenser  500 E may be arranged to be pumped into the fourth main heater body  41 D through the fourth water inlet  412 D. The condensate water passing through the fourth water inlet  412 D may be arranged to be injected into the fourth heat exchange compartment  411 D through the fourth injection nozzle  42 D for creating a negative pressure in the fourth heat exchange compartment  411 D. The negative pressure may then draw a predetermined amount of steam from the turbine assembly  300 E (comprising at least one turbine  310 E) to enter the fourth heat exchange compartment  411 D through the steam inlet  413 D for mixing with the condensate water. The condensate water may be heated up by the steam which is then condensed into water and arranged to be discharged out of the fourth heat exchange compartment  411 D through the fourth water outlet  414 D. 
     The fourth main heater body  41 D may comprise a fourth heat exchanging tube  415 D and a fourth water collection head  416 D connected to the fourth heat exchanging tube  415 D, wherein the fourth water inlet  412 D may be formed on the fourth water collection head  416 D while the fourth heat exchange compartment  411 D may be formed in the fourth heat exchanging tube  415 D. 
     The fourth main heater body  11 C may further comprise a fourth water discharging tube  417 D extended from the fourth heat exchanging tube  415 D, wherein the fourth water outlet  414 D may be formed on the fourth water discharging tube  417 D. 
     The fourth water discharging tube  417 D may have a fourth guiding portion  4171 D, a fourth pressurizing portion  4172 D, and a fourth buffering portion  4173 D extended between the fourth guiding portion  4171 D and the fourth pressurizing portion  4172 D. The fourth guiding portion  4171 D may extend from the fourth heat exchanging tube  415 D and may have a diameter gradually decreasing from the fourth heat exchanging tube  415 D so as to form a tapered cross-section shape for collecting and guiding water flow in the guiding portion. 
     The fourth pressurizing portion  4172 D may extend from the fourth buffering portion  4173 D and may have a diameter gradually increasing from the fourth buffering portion  4173 D so that the water passing through the fourth pressurizing portion  4172 D may have increasing pressure but decreasing flow rate. 
     The fourth water collection head  416 D may have a fourth water collection chamber  4161 D. The fourth water inlet  412 D may be formed on the fourth water collection head  416 D and may communicate with the fourth water collection chamber  4161 D. The fourth heat exchanging tube  415 D may comprise a fourth external tube member  4151 D and a fourth internal tube member  4152 D for forming a double wall structure of the fourth heat exchanging tube  415 D. The fourth steam inlet  413 D may be formed on the fourth external tube member  4151 D of the fourth heat exchanging tube  415 D. A fourth receiving gap  4153 D may be formed between the fourth external tube member  4151 D and the fourth internal tube member  4152 D. The fourth heat exchange compartment  411 D may be formed inside the fourth internal tube member  4152 D. The fourth internal tube member  4152 D may have a plurality of fourth holes  4154 D formed thereon for communicating the fourth receiving gap  4153 D with the fourth heat exchange compartment  411 D. 
     The fourth injection nozzle  42 D may be provided between the fourth water collection head  416 D and the fourth heat exchanging tube  415 D. The fourth injection nozzle  42 D comprise a fourth nozzle base  421 D and have a plurality of fourth injection holes  422 D formed on the fourth nozzle base  421 D, wherein the fourth injection holes  422 D may communicate the fourth water collection chamber  4161 D with the fourth heat exchange compartment  411 D so that water collected in the fourth water collection chamber  4161 D may be injected into the fourth heat exchange compartment  411 D through the fourth injection holes  422 D. 
     The fourth injection feedwater heater  42 D may further comprise a fourth safety arrangement  44 D provided on the fourth heat exchanging tube  415 D for preventing fluid, such as condensate water, from exiting the fourth heat exchanging tube  415 D and reaching the turbine  310 E through the fourth steam inlet  413 D. 
     The fourth main heater body  41 D may further comprise a fourth steam input tube  418 D extending from the fourth external tube member  4151 D, wherein the fourth steam inlet  413 D is formed in the fourth steam input tube  418 D. The fourth safety arrangement  44 D may comprise a fourth unidirectional valve  441 D mounted in the fourth steam input tube  418 D for preventing water from exiting the fourth heat exchanging tube  415 D and reaching the turbine  310 E through the fourth steam inlet  413 D. 
     The fourth safety arrangement  44 D may further comprise a fourth electromagnetic valve  442 D mounted on the fourth steam inlet  413 D, and a plurality of fourth pressure sensors  443 D provided in the fourth internal tube member  4152 D and the fourth steam input tube  418 D respectively for measuring the pressure in the fourth internal tube member  4152 D and the fourth steam input tube  418 D respectively. The fourth pressure sensors  443 D may be electrically connected to the fourth electromagnetic valve  442 D so that when the fourth pressure sensors  443 D detect that the pressure in the fourth steam input tube  418 D is lower than that of the fourth heat exchange compartment  411 D, the fourth electromagnetic valve  442 D may be arranged to turn off the corresponding pumping device  70 E. 
     In this fourth preferred embodiment, the first injection feedwater heater  10 C and the second injection feedwater heater  20 C may be connected in parallel with each other, while the third injection feedwater heater  30 C and the fourth injection feedwater heater  40 D may be connected in parallel with each other. 
     As shown in  FIG. 15  of the drawings, superheated steam may be generated in the steam generator  102 E. The superheated steam may be guided to flow into the turbine assembly  300 E comprising at least one turbine  310 E. The turbine assembly  300 E may also be connected to an electric generator  400 E and a condenser  500 E. The steam from the turbine assembly  300 E may be guided to flow through the condenser  500 E which may condense the steam into condensate water. The condenser  500 E may be connected to a pumping device  70 E and the first injection feedwater heater  10 C and the second injection feedwater heater  20 C. Note that the first injection feedwater heater  10 C and the second injection feedwater heater  20 C may be connected in parallel with respect to each other, while the first injection feedwater heater  10 C and the second injection feedwater heater  20 C may be connected in series with the condenser  500 E and the pumping device  70 E. This configuration is graphically depicted in  FIG. 15  of the drawings. 
     Thus, the condensate water from the condenser  500 E may be pumped to the first injection feedwater heater  10 C and the second injection feedwater heater  20 C at the same time through the first water inlet  112 C and the second water inlet  212 C respectively. Steam from the turbine assembly  300 E may be fed into the first injection feedwater heater  10 C and the second injection feedwater heater  20 C through the first steam inlet  113 C and the second steam inlet  213 C respectively to perform heat exchange with the condensate water. After that, the condensate water may exit the first injection feedwater heater  10 C and the second injection feedwater heater  20 C through the first water outlet  114 C and the second water outlet  214 C. 
     The first injection feedwater heater  10 C and the second injection feedwater heater  20 C may also be connected to the deaerator  100 E which may also be connected to the turbine assembly  300 E. The deaerator  100 E may further be connected to the third injection feedwater heater  30 C and the fourth injection feedwater heater  40 D. The third injection feedwater heater  30 C and the fourth injection feedwater heater  40 D may be connected in parallel with respect to each other. But the third injection feedwater heater  30 C and the fourth injection feedwater heater  40 D together may be connected to the deaerator  100 E and the corresponding pumping device  70 E in series. This configuration may be graphically depicted in  FIG. 15  of the drawings. 
     The water from the deaerator  100 E may be guided to flow into the third injection feedwater heater  30 C and the fourth injection feedwater heater  40 D through the third water inlet  312 C and the fourth water inlet  412 D. The third injection feedwater heater  30 C and the fourth injection feedwater heater  40 D may also be connected to the turbine assembly  300 E so that steam may flow into the third heat exchange compartment  311 C and the fourth heat exchange compartment  411 D through the third steam inlet  313 C and the fourth steam inlet  413 D respectively. The water may then go out of the third injection feedwater heater  30 C and the fourth injection feedwater heater  40 D through the third water outlet  314 C and the fourth water outlet  414 D and may be guided to flow back to the steam generator  102 E for performing another cycle of power generator. 
     In the fourth preferred embodiment of the present invention, the condensate water may undergo two stages of pre-heating process, one of which in the first injection feedwater heater  10 C and the second injection feedwater heater  20 C, while the other in the third injection feedwater heater  30 C and the fourth injection feedwater heater  40 D. 
     Referring to  FIG. 18  and  FIG. 19A  and  FIG. 19B  of the drawings, a steam power generating system according to a fifth preferred embodiment of the present invention is illustrated. The fifth preferred embodiment is similar to the fourth preferred embodiment described above, except the configuration of the various components of the steam power generating system. Moreover, the feedwater preheat arrangement  1 F may further comprise a fifth injection feedwater heater  50 E and a sixth injection feedwater heater  60 E. The fifth injection feedwater heater  50 E and the sixth injection feedwater heater  60 E may have identical structure as that of the first through fourth injection feedwater heater  10 C,  20 C,  30 C,  40 D described above. 
     As shown in  FIG. 19A  of the drawings, the fifth injection feedwater heater  50 E may comprise a fifth main heater body  51 E and a fifth injection nozzle  52 E. The fifth main heater body  51 E may have a fifth heat exchange compartment  511 E, a fifth water inlet  512 E, a fifth steam inlet  513 E, and a fifth water outlet  514 E formed on the fifth main heater body  51 E. 
     The fifth injection nozzle  52 E may be provided in the fifth main heater body  51 E at a position adjacent to the fifth water inlet  512 E, wherein a predetermined amount of the condensate water from the condenser  500 F may be arranged to be pumped into the fifth main heater body  51 E through the fifth water inlet  512 E. The condensate water passing through the fifth water inlet  512 E may be arranged to be injected into the fifth heat exchange compartment  511 E through the fifth injection nozzle  52 E for creating a negative pressure in the fifth heat exchange compartment  511 E. The negative pressure may then draw a predetermined amount of steam from the turbine assembly  300 F to enter the fifth heat exchange compartment  511 E through the steam inlet  513 E for mixing with the condensate water. The condensate water may be heated up by the steam which is then condensed into water and arranged to be discharged out of the fifth heat exchange compartment  511 E through the fifth water outlet  514 E. 
     The fifth main heater body  51 E may comprise a fifth heat exchanging tube  515 E and a fifth water collection head  516 E connected to the fifth heat exchanging tube  515 E, wherein the fifth water inlet  512 E may be formed on the fifth water collection head  516 E while the fifth heat exchange compartment  511 E may be formed in the fifth heat exchanging tube  515 E. 
     The fifth main heater body  51 E may further comprise a fifth water discharging tube  517 E extended from the fifth heat exchanging tube  515 E, wherein the fifth water outlet  514 E may be formed on the fifth water discharging tube  517 E. Condensate water coming from the condenser  500 F may sequentially pass through the fifth water inlet  512 E, the fifth water collection head  516 E, the fifth heat exchanging tube  515 E, the fifth water discharging tube  517 E, and the fifth water outlet  514 E. 
     The fifth water collection head  516 E may have a fifth water collection chamber  5161 E. The fifth water inlet  512 E may be formed on the fifth water collection head  516 E and may communicate with the fifth water collection chamber  5161 E. The fifth heat exchanging tube  515 E may comprise a fifth external tube member  5151 E and a fifth internal tube member  5152 E for forming a double wall structure of the fifth heat exchanging tube  515 E. The fifth steam inlet  513 E may be formed on the fifth external tube member  5151 E of the fifth heat exchanging tube  515 E. A fifth receiving gap  5153 E may be formed between the fifth external tube member  5151 E and the fifth internal tube member  5152 E. The fifth heat exchange compartment  511 E may be formed inside the fifth internal tube member  5152 E. 
     The fifth internal tube member  5152 E may have a plurality of fifth holes  5154 E formed thereon for communicating the fifth receiving gap  5153 E with the fifth heat exchange compartment  511 E. Thus, steam from the turbine  310 F may enter the fifth heat exchanging tube  515 E through the fifth steam inlet  513 E. 
     The fifth injection nozzle  52 E may be provided between the fifth water collection head  516 E and the fifth heat exchanging tube  515 E. The fifth injection nozzle  52 E comprise a fifth nozzle base  521 E and have a plurality of fifth injection holes  522 E formed on the fifth nozzle base  521 E, wherein the fifth injection holes  522 E may communicate the fifth water collection chamber  5161 E with the fifth heat exchange compartment  511 E so that water collected in the fifth water collection chamber  5161 E may be injected into the fifth heat exchange compartment  511 E through the fifth injection holes  522 E. 
     The fifth water discharging tube  517 E may have a fifth guiding portion  5171 E, a fifth pressurizing portion  5172 E, and a fifth buffering portion  5173 E extended between the fifth guiding portion  5171 E and the fifth pressurizing portion  5172 E. The fifth guiding portion  5171 E may extend from the fifth heat exchanging tube  515 E and may have a diameter gradually decreasing from the fifth heat exchanging tube  515 E so as to form a tapered cross-section shape for collecting and guiding water flow in the fifth guiding portion  5171 E. 
     The fifth pressurizing portion  5172 E may extend from the fifth buffering portion  5173 E and may have a diameter gradually increasing from the fifth buffering portion  5173 E so that the water passing through the fifth pressurizing portion  5172 E may have increasing pressure but decreasing flow rate. 
     The fifth injection feedwater heater  52 E may further comprise a fifth safety arrangement  54 E provided on the fifth heat exchanging tube  515 E for preventing fluid, such as condensate water, from exiting the fifth heat exchanging tube  515 E and reaching the turbine  310 E through the fifth steam inlet  513 E. 
     The fifth main heater body  51 E may further comprise a fifth steam input tube  518 E extending from the fifth external tube member  5151 E, wherein the fifth steam inlet  513 E is formed in the fifth steam input tube  518 E. The fifth safety arrangement  54 E may comprise a fifth unidirectional valve  541 E mounted in the fifth steam input tube  518 E for preventing water from exiting the fifth heat exchanging tube  515 E and reaching the turbine  310 F through the fifth steam inlet  513 E. 
     The fifth safety arrangement  54 E may further comprise a fifth electromagnetic valve  542 E mounted on the fifth steam inlet  513 E, and a plurality of fifth pressure sensors  543 E provided in the fifth internal tube member  5152 E and the fifth steam input tube  518 E respectively for measuring the pressure in the fifth internal tube member  5152 E and the fifth steam input tube  518 E respectively. The fifth pressure sensors  543 E may be electrically connected to the fifth electromagnetic valve  542 E so that when the fifth pressure sensors  543 E detect that the pressure in the fifth steam input tube  518 E is lower than that of the fifth heat exchange compartment  511 E, the fifth electromagnetic valve  542 E may be arranged to turn off the corresponding pumping device  70 F for stopping condensate water from further feeding into the fifth injection feedwater heater  50 E. 
     As shown in  FIG. 18B  of the drawings, the sixth injection feedwater heater  60 E may comprise a sixth main heater body  61 E and a sixth injection nozzle  62 E. The sixth main heater body  61 E may have a sixth heat exchange compartment  611 E, a sixth water inlet  612 E, a sixth steam inlet  613 E, and a sixth water outlet  614 E formed on the sixth main heater body  61 E. 
     The sixth injection nozzle  62 E may be provided in the sixth main heater body  61 E at a position adjacent to the sixth water inlet  612 E, wherein a predetermined amount of the condensate water from the condenser  500 F may be arranged to be pumped into the sixth main heater body  61 E through the sixth water inlet  612 E. The condensate water passing through the sixth water inlet  612 E may be arranged to be injected into the sixth heat exchange compartment  611 E through the sixth injection nozzle  62 E for creating a negative pressure in the sixth heat exchange compartment  611 E. The negative pressure may then draw a predetermined amount of steam from the turbine assembly  300 F to enter the sixth heat exchange compartment  611 E through the steam inlet  613 E for mixing with the condensate water. The condensate water may be heated up by the steam which is then condensed into water and arranged to be discharged out of the sixth heat exchange compartment  611 E through the sixth water outlet  614 E. 
     The sixth main heater body  61 E may comprise a sixth heat exchanging tube  615 E and a sixth water collection head  616 E connected to the sixth heat exchanging tube  615 E, wherein the sixth water inlet  612 E may be formed on the sixth water collection head  616 E while the sixth heat exchange compartment  611 E may be formed in the sixth heat exchanging tube  615 E. 
     The sixth main heater body  61 E may further comprise a sixth water discharging tube  617 E extended from the sixth heat exchanging tube  615 E, wherein the sixth water outlet  614 E may be formed on the sixth water discharging tube  617 E. Condensate water coming from the condenser  500 F may sequentially pass through the sixth water inlet  612 E, the sixth water collection head  616 E, the sixth heat exchanging tube  615 E, the sixth water discharging tube  617 E, and the sixth water outlet  614 E. 
     The sixth water collection head  616 E may have a sixth water collection chamber  6161 E. The sixth water inlet  612 E may be formed on the sixth water collection head  616 E and may communicate with the sixth water collection chamber  6161 E. The sixth heat exchanging tube  615 E may comprise a sixth external tube member  6151 E and a sixth internal tube member  6152 E for forming a double wall structure of the sixth heat exchanging tube  615 E. The sixth steam inlet  613 E may be formed on the sixth external tube member  6151 E of the sixth heat exchanging tube  615 E. A sixth receiving gap  6153 E may be formed between the sixth external tube member  6151 E and the sixth internal tube member  6152 E. The sixth heat exchange compartment  611 E may be formed inside the sixth internal tube member  6152 E. 
     The sixth internal tube member  6152 D may have a plurality of sixth holes  6154 E formed thereon for communicating the sixth receiving gap  6153 E with the sixth heat exchange compartment  611 E. Thus, steam from the turbine  310 F may enter the sixth heat exchanging tube  615 E through the sixth steam inlet  613 E. 
     The sixth injection nozzle  62 E may be provided between the sixth water collection head  616 E and the sixth heat exchanging tube  615 E. The sixth injection nozzle  62 E comprise a sixth nozzle base  621 E and have a plurality of sixth injection holes  622 E formed on the sixth nozzle base  621 E, wherein the sixth injection holes  622 E may communicate the sixth water collection chamber  6161 E with the sixth heat exchange compartment  611 E so that water collected in the sixth water collection chamber  6161 E may be injected into the sixth heat exchange compartment  611 E through the sixth injection holes  622 E. 
     The sixth water discharging tube  617 E may have a sixth guiding portion  6171 E, a sixth pressurizing portion  6172 E, and a sixth buffering portion  6173 E extended between the sixth guiding portion  6171 E and the sixth pressurizing portion  6172 E. The sixth guiding portion  6171 E may extend from the sixth heat exchanging tube  615 E and may have a diameter gradually decreasing from the sixth heat exchanging tube  615 E so as to form a tapered cross-section shape for collecting and guiding water flow in the sixth guiding portion  6171 E. 
     The sixth pressurizing portion  6172 E may extend from the sixth buffering portion  6173 E and may have a diameter gradually increasing from the sixth buffering portion  6173 E so that the water passing through the sixth pressurizing portion  6172 E may have increasing pressure but decreasing flow rate. 
     The sixth injection feedwater heater  62 E may further comprise a sixth safety arrangement  64 E provided on the sixth heat exchanging tube  615 E for preventing fluid, such as condensate water, from exiting the sixth heat exchanging tube  615 E and reaching the turbine  310 F through the sixth steam inlet  613 E. 
     The sixth main heater body  61 E may further comprise a sixth steam input tube  618 E extending from the sixth external tube member  6151 E, wherein the sixth steam inlet  613 E is formed in the sixth steam input tube  618 E. The sixth safety arrangement  64 E may comprise a sixth unidirectional valve  641 E mounted in the sixth steam input tube  618 E for preventing water from exiting the sixth heat exchanging tube  615 E and reaching the turbine  310 F through the sixth steam inlet  613 E. 
     The sixth safety arrangement  64 E may further comprise a sixth electromagnetic valve  642 E mounted on the sixth steam inlet  613 E, and a plurality of sixth pressure sensors  643 E provided in the sixth internal tube member  6152 E and the sixth steam input tube  618 E respectively for measuring the pressure in the sixth internal tube member  6152 E and the sixth steam input tube  618 E respectively. The sixth pressure sensors  643 E may be electrically connected to the sixth electromagnetic valve  642 E so that when the sixth pressure sensors  643 E detect that the pressure in the sixth steam input tube  618 E is lower than that of the sixth heat exchange compartment  611 E, the sixth electromagnetic valve  642 E may be arranged to turn off the corresponding pumping device  70 F for stopping condensate water from further feeding into the sixth injection feedwater heater  60 E. 
     Referring to  FIG. 17  of the drawings, in this fifth preferred embodiment, the first injection feedwater heater  10 C and the second injection feedwater heater  20 C may be connected in parallel with each other. The steam power generating system may comprise two deaerators  100 F and three pumping devices  70 F. The first injection feedwater heater  10 C may connect to one of the deaerators  100 F which may then connect to one of the pumping devices  70 F and the third injection feedwater heater  30 C in series. Moreover, the third injection feedwater heater  30 C may be connected to the fifth injection feedwater heater  50 E in series. 
     On the other hand, the second injection feedwater heater  20 C may connect to another of the deaerators  100 F which may then connect to another of the pumping devices  70 F and the fourth injection feedwater heater  40 D in series. Moreover, the fourth injection feedwater heater  40 D may be connected to the sixth injection feedwater heater  60 E in series. Each of the first through sixth injection feedwater heater  10 C,  20 C,  30 C,  40 D,  50 E,  60 E may be structurally identical and may be connected to the turbine assembly  300 F. 
     Superheated steam may be generated in the steam generator  102 F. The superheated steam may be guided to flow into the turbine assembly  300 F comprising at least one turbine  310 F. The turbine assembly  300 F may also be connected to an electric generator  400 F and a condenser  500 F. The steam from the turbine assembly  300 F may be guided to flow through the condenser  500 F which may condense the steam into condensate water. The condenser  500 F may be connected to a pumping device  70 F and the first injection feedwater heater  10 C and the second injection feedwater heater  20 C. Note that the first injection feedwater heater  10 C and the second injection feedwater heater  20 C may be connected in parallel with respect to each other, while the first injection feedwater heater  10 C and the second injection feedwater heater  20 C may be connected in series with the condenser  500 F and the pumping device  70 F. This configuration is graphically depicted in  FIG. 17  of the drawings. 
     The condensate water from the condenser  500 F may be pumped to the first injection feedwater heater  10 C and the second injection feedwater heater  20 C at the same time through the first water inlet  112 C and the second water inlet  212 C respectively. Steam from the turbine assembly  300 F may be fed into the first injection feedwater heater  10 C and the second injection feedwater heater  20 C through the first steam inlet  113 C and the second steam inlet  213 C respectively to perform heat exchange with the condensate water. After that, the condensate water may exit the first injection feedwater heater  10 C and the second injection feedwater heater  20 C through the first water outlet  114 C and the second water outlet  214 C. 
     As mentioned above, the first injection feedwater heater  10 C and the second injection feedwater heater  20 C may also be connected to two deaerator  100 F respectively. Each of the deaerator  100 F may be connected to the turbine assembly  300 F for acquiring steam from at least one of the turbine  310 F. The water coming out from the first injection feedwater heater  10 C and the second injection feedwater heater  20 C may enter the two deaerator  100 F respectively. After that, water from the two deaerator  100 F may be guided to flow into the third injection feedwater heater  30 C and the fourth injection feedwater heater  40 D respectively through two pumping devices  70 F for further absorbing heat. 
     The water may then flow out of the third injection feedwater heater  30 C and the fourth injection feedwater heater  40 D and may be guided to flow into the fifth injection feedwater heater  50 E and the sixth injection feedwater heater  60 E respectively. The water in the fifth injection feedwater heater  50 E and the sixth injection feedwater heater  60 E may further absorb heat from the steam of the turbine  310 F. Finally, the condensate water from the fifth injection feedwater heater  50 E and the sixth injection feedwater heater  60 E may exit through the fifth water outlet and the sixth water outlet  514 E,  614 E and go back to the steam generator  102 F. 
     Note that in this fifth preferred embodiment of the present invention, condensate water from the condenser  500 F may undergo three stages of pre-heating before going back to the steam generator  102 F. The three stages of pre-heating may be accomplished by the first and the second injection feedwater heater  10 C,  20 C, the third and the fourth injection feedwater heater  30 C,  40 D, and finally the fifth and the sixth injection feedwater heater  50 E,  60 E. 
     The present invention, while illustrated and described in terms of a preferred embodiment and several alternatives, is not limited to the particular description contained in this specification. Additional alternative or equivalent components could also be used to practice the present invention.