FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL
Specification
(See section 10 and rule 13)
VAPOUR ABSORPTION DEVICE THERMAX LIMITED
an Indian Company
Chinchwad, Pune411 019, Maharashtra, India
THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION.
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FIELD OF INVENTION:
This invention relates to vapour absorption devices.
PRIOR ART:
It is already known in the prior art that for utilization of waste heat recovered from exhaust gases in a LiBr Vapour Absorption Heat Pumps (VAHPs), following types of systems are in use:
1. Steam at around 8 kg/cm2 generated from exhaust gas fired waste heat recovery steam boilers
2. Pressurized hot water generated from an exhaust gas fired hot water generator and normally pumped through the generator of VAHP
3. Exhaust gas fired Thermosiphon LiBr VAHP
4. Direct utilization of exhaust gases in shell and tube type of High Temperature Generator (HTG) configuration where LiBr solution is on the shell side i.e. outside the tubes through which exhaust gas flow takes place.
Of these four systems, the first three are indirect i.e. an intermediate heat exchanger is required between the waste heat source and the VAHP. These systems are expensive, because in addition to the main system they also require additional equipment such as steam boilers, hot water generators and the like.
Additionally, in the case of exhaust gas fired hot water generators and steam boilers hitherto known, pumps are required to force the working medium through the generator tubes or for forcing condensate back to the hot water generator / boiler. This increases the operating cost.
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In the case of steam boilers, the known systems are open loop type systems and the total hold up of such boiler generally exceeds 22.75 litres, bringing it under the purview of Indian Boiler Regulations (IBR).
The main limitation of conventional shell and tube type HTG of LiBr Vapour Absorption Heat Pumps is that the quantity of LiBr solution required is very high and contributes substantially to the overall capital cost of the machine.
Another limitation is that in exhaust fired units with diesel / heavy oil as Diesel Generator (DG) set fuel, the tubes with relatively larger diameters have to be used to minimize fouling of surfaces due to soot. This further increases size of HTG and the LiBr content in HTG. Even with large diameter tubes, the fouling of surfaces cannot be avoided totally and takes place at fairly frequent intervals, affecting the availability of the system. Further, on line cleaning of Shell and tube type HTG's is not possible.
Availability is further reduced because these systems are required to undergo annual inspections and mechanical maintenance, particularly in the case of steam boilers.
OBJECTS OF THE INVENTION:
An object of this invention is to provide an improved HTG system, which recovers heat from any waste heat source, such as a DG set, and acts as a heat source for operating VAHP.
Another object of this invention is to substantially reduce LiBr solution content of the exhaust gas fired HTG in LiBr VAHP.
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Another object of this invention is to provide an HTG, which is suitable for exhaust gas heat recovery from DG sets fired by any liquid fuel including heavy oil.
SUMMARY OF INVENTION:
This invention relates LiBr Vapour Absorption Heat Pumps (VAHP).
In accordance with this invention there is provided a LiBr Vapour Absorption Heat Pump (VAHP) utilizing heat from flue gases. In one embodiment of the invention the gas envisaged is exhaust gas from DG sets.
It is envisaged that in a preferred embodiment of the invention the heat pump uses a High Temperature Generator (HTG).
This invention envisages a new configuration of HTG for recovery of waste heat from gases such as DG set exhaust through exhaust gas fired LiBr VAHP which is of water tube type of construction and has LiBr solution inside the tubes and the boiling of solution inside the tubes produces natural circulation of LiBr solution.
ADVANTAGES
1. Substantial reduction in LiBr solution content.
2. Reduction in overall capital cost as well as operating cost.
3. Improve up on availability of the overall system.
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BRIEF DESCRIPTION OF THE DRAWING:
The invention will now be described with reference to the accompanying
drawing wherein,
Figure 1 illustrates the schematic of the proposed configuration of the
HTG in accordance with this invention; and
Figure 2 illustrates the HTG of figure 1 connected to rest of the
components of a VAHP.
In figure 1 and 2, (1) is the diverter damper through which exhaust gases from a DG (diesel generator) set pass on to inlet port (2) of the HTG according to this invention. The HTG consists of set of heat exchanger tubes with or with out appropriate fins. The LiBr solution is inside the tubes and exhaust gases flow over the tubes.
The heat exchanger tubes (3) are connected to the header (4). The header (4) is connected to the bottom header (5) at the bottom and to the top header (6) at top. The top header is connected to a separator (8) by means of a riser (7) as shown in figure 2. The entire assembly of heat exchanger tubes, header, top / bottom header is fitted in a casing (10). Depending on the size of DG set and desired heat recovery; there can be single casing or multiple assemblies of casings.
The LiBr solution and vapour formed in the heat exchanger tubes flows to the header (4) then to top header and finally to the separator where vapour is separated from LiBr solution. Part of the LiBr solution circulates back to the bottom header (5) by means of a down comer (9) and forms a natural circulation loop. The remaining LiBr solution and water vapour is led away from the separator to further components in the VAHP cycle.
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The configuration described above is of natural circulation type where any pump does not force flow of the LiBr through the heat exchanger.
In accordance with an alternative embodiment of the invention, an HTG with forced circulation type can also be easily made where LiBr solution is forced through the heat exchanger tubes with the help of a pump.
The exhaust gases enter the HTG through inlet port then pass over heat exchanger tubes where heat is transferred to LiBr solution. The cooled exhaust gases exit HTG through outlet port.
This invention also extends to a method of recovering heat from exhaust gases of waste heat source such as DG set exhaust using an HTG as described above.
Waste heat source can be exhaust gases from DG set or gas turbine or industrial furnaces or boilers / heaters etc at sufficiently high temperature so that heat recovery is possible.
In another embodiment the invention extends to a method of generating refrigerant vapours from LiBr solution utilizing waste gases such as exhaust gases from DG set wherein these vapours can be used for refrigeration purposes in further LiBr VAHP cycles.
A system is envisaged in accordance with this system comprising a set of heat exchangers such as generators, absorber, condenser, evapourator, solution heat exchangers, pumps and an HTG.
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The system in accordance with this invention can be used with either a single or multiple modules of assembled heat exchanger surfaces.
The system is operably connected so as to render the desired cooling effect utilizing exhaust gases from any waste heat source such as exhaust gases from DG set.
While considerable emphasis has been placed herein on the specific structure of the preferred embodiment, it will be appreciated that many alterations can be made and that many modifications can be made in the preferred embodiment without departing from the principles of the invention. These and other changes in the preferred embodiment as well as other embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.
Dated this 7th day of April 2006

Mohan Dewan

Of R. K. Dewan & Co

Applicant's Patent Attorney
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