Apparatus and method for producing working fluid for a power plant

Apparatus and a method for forming a gas hydrate for use in the production of pressurised gas due to the decomposition of the gas-hydrate in a storage chamber, and for controlled delivery of the pressurised gas as working medium to a turbine engine which is preferably coupled to a generator for the production of electricity.

The present invention relates an apparatus and method for producing working 
medium for supply to an engine of a power installation. More especially 
the invention relates to the area of power-plant engineering of 
electricity-generating installations for the transformation of 
low-potential and high-potential thermal energy into mechanical and 
electrical energy, and also in the area of a means of preparation of a 
working medium for such installations. 
TECHNICAL BACKGROUND 
There exists an electricity-generating installation containing a 
high-potential heat source. The installation has a closed circuit with an 
intermediate heat-transfer medium, a power turbine, heat-exchangers for 
heating and cooling the working medium. Patent USSR No. 70147, Int. class. 
F03G7/00, publ. 1948 applies. 
There also exists an electricity-generating installation containing a 
turbine for driving a load, a cooler, a circulating pump and two or more 
chambers for preparing the working medium, all of the above connected by 
means of pipelines. The chambers are connected to the turbine and have a 
heater, a separator and sealing devices at the outlet. The circulation 
pump is connected to the cooler and to each of the chambers to form a 
circuit for the circulation of liquid. Patent USSR No. 1170180, Int. class 
FO125/00, publ. 1985 applies. 
There exists a means for the preparation of the working medium of an 
electricity-generating installation, consisting in the filling of an 
intermediate heat transfer medium circuit with a volatile liquid and its 
subsequent evaporation in an heat-exchanger by air compressed in an 
compressor and the supply of the vapour to the turbine. Patent USSR No. 
70147, Int. class F03G7/00, publ. 1948 applies. 
There also exists a means for the preparation of the working medium of an 
electricity-generating installation, including the filling of one or more 
chambers with a liquid, the introduction into one of the chambers of an 
additional component and the raising of its pressure, the heating of the 
working medium formed in it and, following the supply of the working 
medium to the turbine, the performance of these operations in another 
chamber. Patent USSR No. 1170180, Int. class F01K25/00, publ. 1985 
applies. 
Further, U.S. Pat. No. 3943719 discloses apparatus for supplying working 
medium to an engine (e.g. turbine), this apparatus comprising generating 
means for producing working medium and delivery means for supplying said 
working medium to an engine. In particular the generating means comprises 
reactor means for the formation of a compoung (i.e. hydride) from which 
the working medium (i.e. Hydrogen) is obtained, while storage means are 
provided for holding said compound formed by said reactor means, said 
delivery means including control means for controlled delivery of working 
medium from the storage means to the engine. 
According to one aspect of the present invention there is provided 
apparatus for supplying working medium for a gas expansion engine 
comprising generating means for producing working medium, storage means 
for the working medium, and delivery means for supplying the working 
medium to an engine from the storage means, the delivery means including 
control means for controlled delivery of the working medium from the 
storage means to the engine wherein the generating means comprises reactor 
means arranged and adapted for the formation of a gas-hydrate from which 
the working medium for the engine is obtained, the storage means holding 
the gas hydrate formed by the reactor means, and a liquid recirculation 
circuit is provided for recycling liquid discharged from the reactor means 
back to the reactor means, the recirculation circuit including a 
recirculating pump and a heat-exchanger. The method in particular using 
water condensate from a steam turbo-generator plant for the production of 
the gas hydrate (with a further component) in a reaction chamber, the gas 
hydrate so produced being stored in suitable storage means in readiness 
for the formation of the working medium. 
DISCLOSURE OF THE INVENTION 
The principal object of the present invention is to raise the efficiency of 
an electricity-generating installation by means of the exclusion of 
wasteful losses of heat and mechanical energy, the use in the working 
cycle of low-potential and high-potential heat and the creation of an 
ecologically sound system for the transformation of heat to work. 
To meet this object there is provided apparatus for supplying working 
medium to a gas expansion engine, as set out in the appended claim 1. 
Preferably, the storage means comprises a plurality of separate containers, 
the delivery means including conduit means for supplying working medium to 
the engine from the containers and in that the control means comprise 
valves operable for sequential delivery of working medium from the 
containers to the engine via said conduit meams. 
In addition, the apparatus may be provided with a gas supercharger, 
connected to the containers so as to form one or more circuits for gas 
recirculation. The containers may be constructed with one or more external 
separators and/or one external reactors connected via a gas-hydrate 
emulsion outlet to the containers, while the separator is situated at the 
outlet of the chambers and connected via its liquid outlet to the inside 
volume of the chambers, which are in addition connected to a circuit for 
the circulation of liquid. The apparatus can include a heater and cooler 
constructed in the form of a single heat-exchange device, supplied 
intermittently from external sources with two heat-transfer media at 
different temperatures. The apparatus may also be fitted with an 
electrolyzer, and the load may take the form of a generator, with the 
electrolyzer being connected to the generator and the working-chamber 
being connected to an additional heat-exchanger so as to form an 
additional heat recovery path to add the heat produced by electrolysis to 
the working media of the system before it enters the engine (turbine). The 
installation may be fitted with an additional turbine, and the 
electrolyzer may be constructed to accept oxygen and hydrogen and be 
fitted with an oxygen outlet which is connected to the additional turbine. 
According to another aspect of the present invention there is provided a 
method of producing a working medium for supply to a gas expansion engine 
comprising introducing liquid and an additional component such as water 
and a gas into a reaction chamber to form by reaction a gas-hydrate from 
which the working medium is obtained and storing the gas-hydrate so 
produced in storage means, wherein for maintaining desirable conditions of 
reaction in the reaction chamber the liquid discharged from the reaction 
chamber is passed in a recirculating circuit including heat exchanger 
means back to the reaction chamber. Thus the present invention can 
encompass the introduction into one or more chambers filled with liquid of 
a low-pressure gaseous component, which is absorbed by the liquid to form 
a solid-phase compound, which subsequently when heated decomposes in the 
same chamber or another chamber and produces a high-pressure gas-phase 
working medium for electricity-generating installation, which medium 
drives the turbine. The substances used for the liquid and gas-phase 
components are, respectively, water and a gas such as a methane-propane 
mixture, which reacts with water to form a gas-hydrate, while (optimal) 
conditions of heat-mass transferring process in the chamber are achieved 
by the water's being recirculated and cooled by an external heat-transfer 
medium, and also by the recirculation of the gas which has not reacted. In 
addition, before the working medium is supplied to the turbine, it may be 
additionally heated by a heat-transfer medium at a high temperature.

Referring to FIG. 1, an electricity-generating installation comprises a 
turbine 3 for driving a load in the form of an electrical generator 4 and 
two or more chambers 5, 6 constructed with a reactor for the formation of 
gas-hydrate from which the gaseous working medium for the turbine 3 is 
obtained, pipelines 1 and 2 serving for the supply of working medium to 
the turbine 3 and medium discharge therefrom respectively, the pipelines 
1, 2 forming a closed circuit with the turbine 3 and chambers, 5, 6. The 
chambers 5, 6 include emulsators 7, 8 and separators 5S, 6S in the upper 
section of the chambers 5, 6. The chambers, 5, 6 are included via the 
circulation pumps 9, 10 in the circuits for the circulation of liquid 11, 
12, the circuit including heat-exchange devices 13, 14, which are external 
selective heaters and coolers supplied through the pipelines 15, 16 and 
the adjustable three-phase valves 17, 18 from external sources 
intermittently with two heat-transfer media at different temperatures. The 
substance used for the heating heat-transfer medium may be a low potential 
heat-transfer liquid such as water heated by means of waste heat from 
industrial installations, or by means of solar converters, thermosorbent 
heat-pump installations, or the heat from the condensation of steam, for 
instance, in industrial and natural sources. The substance used for the 
cooling heat-transfer medium may be any fluid with a temperature lower 
than the substance H of the heating heat-transfer medium. The 
heat-transfer media may be water obtained from any suitable source, for 
example from various depths in reservoirs so as to obtain water at a 
suitable temperature level. The temperature of the heating heat-transfer 
medium may be, for instance, 28.degree. C. (see FIG. 4, point B') and the 
temperature of the cooling heat-transfer medium, for instance, 4.degree. 
C. (see FIG. 4, point A'). The installation may be fitted with an 
additional heat-exchanger 19 using a high temperature heat-exchange medium 
and installed prior to the turbine 3 for heating the working medium 
passing to the turbine 3. The substance used as a high temperature 
heat-exchange medium may be the exhaust gases from internal combustion 
engines, the flue gases from industrial installations and so forth. The 
installation is fitted with a gas-supercharger 20 or compressor connected 
to the chambers 5, 6 via the adjustable three-phase valve 21, and via the 
settable valves 22, 23 for recirculating gas which has not reacted in the 
chambers 5, 6. The gas-supercharger 20 is included in the recirculation 
circuits 24, 25 with the common outlet pipe 26. The chambers 5, 6 are 
included in the gas circulation circuits 29, 30 which include settable 
closure valves 27 28. The substance used as a working medium in the 
installation is a gas-hydrate compound formed and decomposed in the 
installation, for instance an 85 per cent methane plus 15 per cent propane 
mixture of the type (CH.sub.4 +C.sub.3 H.sub.8) * 6H.sub.2 0 with a 
relative specific weight of 0.6. It is possible to use special additives, 
for example, glycol in the water, which increase the efficiency of the 
process by which the working medium (gas hydrate) is produced. For 
preparation of the working medium one of the chambers is filled with 
water, for instance chamber 5 (FIG. 1) via the open valve 22 with valves 
23 and 27 closed, and valve 21 closed to close the circuit 24. Gas is 
passed through this water, for instance a methane-propane mixture, via the 
emulsator 7 until the pressure in chamber 5 is raised to the level 
required for the formation of gas-hydrate, for instance 15 atmospheres 
(see point A in FIG. 4). The formation of the gas-hydrate releases heat 
within the reactor chamber. In order to stabilise the reaction to form gas 
hydrate in chamber 5, the pump 9 pumps the water from chamber 5 through 
the heat-exchange device 13, which is supplied with a cooling 
heat-transfer medium. At the same time the supercharger 20 is used to 
recirculate the gas which has not reacted. The process of formation of the 
gas-hydrate is halted when the chamber is substantially filled with 
gas-hydrate. Following this, valve 17 is used to introduce a hot (warm) 
heat-transfer medium into the heat-exchange device 13, and the heat is 
transferred to chamber 5, which results in the disassociation of the 
gas-hydrate under high-pressure. The pressurised gas which is released is 
separated from droplets of water by the separator 5S in the upper section 
of chamber 5. This results in the establishment in chamber 5 of a working 
pressure corresponding to the temperature of decomposition of the gas 
hydrate (see FIG. 4, point B), for instance 300 atmospheres. Following 
this the valve 27 is opened and the high pressure gas is supplied to the 
turbine 3 for the production of work and the driving of the generators, 
for instance, of the generator 4. At the same time as gas is supplied to 
turbine 3 the heating of water in chamber 5 is continued. During the 
supply of gas from chamber 5 to the turbine the operations described above 
for the production of gas-hydrate are performed in chamber 6, using the 
valves 23, 28 and the heat-exchange device 14. When the pressure begins to 
fall in chamber 5 due to all of the gas hydrate having now decomposed, the 
valve 27 is closed, and the heating of water in chamber 6 begins. After a 
working pressure has been developed in chamber 6, valve 28 is opened and 
the pressurised gas is supplied from chamber 6 to the turbine 3. Where 
there is a source of a high-temperature heat-transfer medium the heat 
exchanger 19 is used to further raise the temperature of the gas prior to 
the turbine, thereby increasing the power of the turbine. A regular supply 
of gas to the turbine 3 and a minimal fluctuation of pressure in the 
circuits are achieved by the installation of the requisite number of the 
above mentioned reactor chambers and their operation in phased sequence. 
The installation may be constructed with an external reactor 54 (FIG. 2), 
connected via its outlet 32 through the circulation pump 33 and through 
the adjustable valves 34 and 35 to the chambers 5A and 6A. In turn the 
chambers 5A, 6A are connected via the adjustable valves 36, 37 and the 
pipeline 55 to the cooler 38, and thereby with the circuit 39 for the 
circulation of liquid and with the pump 39A, which is connected to the 
lower section 56 of the reactor 54. The supercharger 20 is connected to 
the upper section 31 of the reactor 54, to the exhaust pipe 2 and to the 
emulsator 7A so as to form the gas circulation circuit 40. The 
installation may include an external separator 41, connected to the upper 
sections of the chambers 5, 6 and connected via its exit pipe 42 to the 
liquid circulation circuit 43 which includes the heater 44, using a 
low-potential external heat-transfer medium, the pump 45, and the 
adjustable valves 46-49, connected to the chambers 5, 6. In addition when 
a large number of chambers is used the separator 41 performs the functions 
of a receiver, which supplies a regular supply of gas to the turbine 3. 
The installation may be fitted with an electrolyser 50, while the load of 
turbine 3 takes the form of the generator 4. In this case the working 
chamber of the electrolyser 50 is connected to the additional 
heat-exchanger 19, using a high-temperature heat-transfer medium, so as to 
form the additional circulation circuit 51 for the return of the heat of 
electrolysis to the work cycle of the installation. The electrolyser 50 
may be equipped, for instance for the production of hydrogen and oxygen, 
with an outlet 52 for oxygen connected to an additional turbine 53. For 
the installation constructed with an external reactor 54 and a separator 
41, the formation of the gas-hydrate is carried out outside the storage 
chambers 5, 6. This is done by filling the reactor 54 and the liquid 
circulation circuit 39 with water distilled (which may contain additives) 
from an external storage tank. When the system has been filled with water 
the above-mentioned working gas is pumped through the emulsator 7A with 
the valves 34, 35 closed. At the same time water is continuously 
circulated through the cooler 38 and the gas which has not reacted is 
circulated using the impeller fan 20. The gas-hydrate emulsion formed in 
the reactor 54 is pumped by the pump 33 into one of the chambers, for 
instance chamber 5A, with the valve 34 open and the valve 27 closed. As 
the gas-hydrate fills the chamber is displaces the remaining water along 
the pipe-line 55 into the circuit 39. Following this, the valves 46, 48 
are opened and the valves 34, 36 are closed, and the water is pumped by 
the pump 45 through the heater 44. At the same time in the chamber 5A the 
gas-hydrate is dissociated under high pressure, and the gas accumulates in 
the storage section of chamber 5. When the temperature of the water being 
pumped through the heater 44 is stabilised, the valve 27 is opened and the 
gas at working pressure enters the separator 41, where it is separated 
from water droplets and then it is introduced via the pipe 1 into the 
turbine 3. At the same time the pumping of water through the heater 44 
continues. When all the gas has emerged under a constant pressure from the 
chamber 5A, the valves 46 and 48 are closed. Following this, the process 
described above is repeated using chamber 6A, and chamber 6A is filled 
with gas-hydrate. The spent gas from the turbine is led along the pipeline 
2 into the emulsator 7A and the gas bubbles through a layer of water in 
the rector 54, with the result that the gas-hydrate is produced 
continuously in the process of the installation's operation. 
If an external separator 41 is installed when there is a large number of 
chambers, it may also be used as a receiver which excludes fluctuations in 
the pressure of the gas in the system. If the installation uses an 
electrolyser 50, its working chamber is connected to an additional 
heat-exchanger 19, using a high-temperature heat-transfer medium, which 
makes it possible to exploit the heat of electrolysis. In accordance with 
the invention, the installation possesses a high degree of operational 
reliability as a result of the absence of high thermal or mechanical 
stresses, it allows the use of inexpensive construction materials, and its 
working cycle is automatically regulated to a high degree. The invention 
should enable a considerable reduction in the cost of producing 
electricity. 
FIG. 5A shows a modification to provide more efficient formation of 
gas-hydrate, and also give a greater power generating facility. The 
modification operates on an induction principle by drawing or sucking the 
gas into the water flow, and the arrangement is described as a liquid-jet 
(or stream) inducer or injector. Thus, there is provided a mixing chamber 
60 in a throat with an inlet manifold 61 of larger cross section to one 
side while a diverging discharge 62B at the other side leads to the 
chambers 5, 6 or 54. An inlet pipe 63 for the high pressure recirculated 
water extends into the manifold 61 and has a discharge nozzle 63A located 
at the converging inlet 62A of the throat, while a further inlet pipe 64 
feeds the gas to the manifold 61. In operation, the recirculated 
high-pressure cooled water W is discharged from the nozzle 63A, and the 
gas in the manifold 61 is sucked into the flowing water via jet inlet 62A 
and mixing of the gas and water occurs in the mixing chamber 60 resulting 
in efficient and effective formation of gas hydrate. 
FIG. 5A shows a single liquid jet inducer, but it would be possible to 
employ a bank (or battery) of such devices for greater output of gas 
hydrate and consequently greater power capacity, and FIG. 5B shows the 
provision of such a battery. In this case the inducer bank is located at 
zone 54A in the chamber 54 and comprises an aligned array of throats 
defining a plurality of mixing chambers 60. The high-pressure cooled water 
is fed to a manifold formation 63M in the chamber 54 having a plurality of 
nozzle discharges 63A each corresponding to a relevant mixing chamber 60 
(all generally as in FIG. 5A). while the gas is led to an inlet 64A 
appropriately located on the chamber 54. Operation of the inducer bank of 
FIG. 5B is exactly similar to the inducer of FIG. 5A. 
FIG. 6 shows an alternative power generating arrangement usable in the 
inventive system, wherein two or more expansion engines in the form of 
turbines 3,3'. . . are arranged in series with working medium produced 
from gas hydrate passing serially through the turbines, and an additional 
heat exchanger 19' is located in the flow path between successive turbines 
3,3' for intermediate heating of the working medium passing between the 
turbines to provide greater efficiency in the operation of the power 
generating arrangement. 
INDUSTRIAL APPLICATIONS 
The invention is intended for the creation of permanent, ecologically sound 
electricity-generating installations, utilising renewable natural sources 
of low-potential thermal energy. The invention may be used in combination 
with various power-intensive technological processes which produce waste 
heat, which is transformed in the installation into useful work, with a 
high degree of efficiency, for instance for the economically effective 
production of hydrogen. 
The invention could of course be used in installations other than 
electricity-generating installations, for example, in a pumping 
installation, and the invention can be utilised to provide working medium 
for a variety of gas expansion engines generally.