FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL
Specification
(See section 10 and rule 13)
LiBr Vapor Absorption Machine (LiBr VAM)
THERMAX LIMITED
an Indian Company
of Chinchwad, Pune 411 019, Maharashtra, India
THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION.

Field of invention
This invention relates to a LiBr Vapor Absorption Machine (LiBr VAM) which utilizes solid fuels directly as a heat source for providing refrigeration effect and more particularly relates to a High Temperature Generator (HTG) of a LiBr Vapor Absorption Machine.
Background and prior art
It is already known in the prior art that the heat sources for a LiBr VAM are mostly one of the following:
1. Live steam at around 8 kg/cm. sup. 2 generated from any steam boiler.
2. Pressurized hot water generated from any hot water generator and normally pumped through the generator of a VAM.
3. Direct firing of liquid / gaseous fuels in a High Temperature Generator (HTG).
4. Use of Exhaust gases from DG sets / micro turbines and the like, for recovering its waste heat directly in a HTG.
5. High temperature thermic fluid pumped through the tubes of a generator.
6. Waste heat in any form such as low pressure steam / hot water / Flue gases etc.
Drawbacks:
1. The main limitation of first two types mentioned above is the
requirement of additional equipment for overall system and
associated higher capital cost.

2. Another limitation is that in case of a hot water generator, a pump is required to force working medium through the generator tubes or in case of a boiler for forcing the condensate back to the boiler. There is an high operating cost associated with it.
3. In the case of a steam boilers, the system is an open loop type and the total hold up of such a boiler generally exceeds 22.75 liters, bringing it under the purview of IBR.
4. Less availability due to annual inspection and mechanical maintenance in case of steam boilers.
5. The limitation of direct firing of liquid / gaseous fuels in LiBr VAM is that the cost of such fuels is comparatively high and it is not always commercially viable to fire such fuels to produce cooling effect through a VAM.
6. The availability of waste heat or exhaust gases from a DG sets and the like is limited and strictly applicable on case to case basis and is viable only when the DG set is running on base load continuous.
Objects of the invention
One of the objects of the present invention is to provide an apparatus which has a lower operating cost.
Another objective of the present invention is to provide an apparatus wherein the heat is recovered from combustion of solid fuels.
Yet another objective of the present invention is to provide an apparatus which utilizes solid fuels directly as a heat source for providing refrigeration effect.

Yet another objective of the present invention is to provide an apparatus wherein crystallization of the LiBr solution is prevented.
Yet another objective of the present invention is to provide an apparatus which is robust.
Yet another objective of the present invention is to provide an apparatus which is easy to manufacture.
Brief Description of the Drawings
The invention will now be described with reference to accompanying drawings in which,
FIG. 1 represents a process diagram for solid fuel combustion system along with a high temperature generator and accessory components in accordance with the present invention;
FIG. 2 represents the cross sectional view of the heat transfer generator (HTG) along the section XX as shown in FIG. 1;
FIG. 3 represents the alternative design for heat exchanger tubes of the HTG as shown in FIG. 1; and
FIG. 4 represents yet another alternative design for the heat exchanger tubes of the HTG as shown in FIG 1.
The apparatus comprises following components:
1. Solid fuel combustion system and its accessories (SFCS)
2. New design of HTG (HTG)

3. Remaining components of LiBr VAM (CS)
4. Associated protection and safety devices
All the above components are operatively connected as explained in the cycle description below.
With reference to Fig. 2, the solid fuel combustion system and its accessories comprising Solid fuel storage and conveying system (1), a Combustion air fan (2), a Dust separation and collection equipment (3), an Induced draft fan (4), a Combustion air supply and distribution system (5) and a fuel firing mechanism (6).
With reference to Fig. l & 2, the new design of a High Temperature Generator (HTG) (29) consists of the Fuel firing mechanism (6), a Combustion air supply system (5), Furnace where solid fuel is fired (7), a combustion Chamber (8) for carrying products of combustion i.e. exhaust gases out of furnace, Heat exchanger tubes (9) to transfer heat from exhaust gases to the LiBr solution on the outer side of tubes and a exhaust gas Chamber (10) to collect cooled exhaust gases from the tubes. It also has LiBr weak solution inlet connection, Intermediate solution outlet connection, Set of eliminators and vapor outlet connection.
With reference to Fig. 1, Remaining components of LiBr VAM comprises major components such as a Lower shell (11) comprising of an Evaporator (12) and an Absorber (13), an Upper shell (14) consisting of a condenser (15) and a Low temperature generator (LTG) (16), Set of heat exchangers such as a Low temperature heat exchanger (17), a High temperature heat exchanger (18) and a Refrigerant heat exchanger (19), a LiBr solution pump (20) and a Refrigerant pump (21). Major protection and safety devices consisting of a dump cooler (22), a purge system and a

control system. The dump condenser (22) has a cooling tube (23) through which cooling water flows. Other components are a shell (24), a vapor inlet pipe (25), a refrigerant liquid outlet pipe (26), a solenoid valve (27) and an isolating valve (28).
In accordance with this invention there is a provided a system comprising a Vapor Absorption machine (VAM), a newly designed HTG and solid fuel combustion system, suitably connected so as to render the desired cooling effect wherein solid fuels are burnt and the resultant heat is directly transferred to the LiBr solution that is directly utilizing energy from combustion of solid fuels, wherein the newly designed HTG recovers heat from combustion products of solid fuel firing and in turn provides heat source for operating VAM and a method for protection against crystallization of LiBr in HTG due to residual heat of solid fuels through a dump condenser.
In one of the embodiment as shown in fig. 2, a new design of a direct solid fuel fired HTG heat exchanger tubes (9A) is connected to LiBr VAM. The HTG and furnace is having a semi circular cum rectangular cross section.
In another embodiment as shown in fig. 4, alternative design of a solid fuel fired HTG heat exchanger tubes (9B) is connected to LiBr VAM. The HTG and furnace is having circular cross section.
In another embodiment as shown in fig. 3, another alternative design of a direct solid fuel fired HTG connected to the LiBr VAM. It is having external membrane type furnace and heat exchanger tubes have LiBr solution inside the tubes.

In yet another embodiment of the present invention there is provided a dump condenser to prevent crystallization of LiBr solution in the HTG which may form due to over firing or due to residual heat in case of power failures.
Typically, the HTG design shown here has internal furnace and is having almost a rectangular shape (cross section). HTG can also be of different type and shapes such as shell and tube with internal or external furnace / circular cross section / water tube type design where LiBr is on tube side. The tubes can be either plain or with fins.
LiBr VAM can be operated with many types of solid fuel such as coal / lignite / agro wastes / biomass/biomass briquettes / biomass pellets provided fuel firing mechanism is properly selected.
The above description of components is for illustration and the components especially the HTG and solid fuel firing system can be made of different design as explained at the end of cycle description.
Cycle description:
Accordingly, in this system different types of solid fuels (coal, biomass, lignite etc) are burnt in the furnace part of new HTG. The products of combustion pass through the heat transfer tubes of HTG. The heat from the flue gases is transferred to the LiBr solution which is on the outer side of heat transfer tubes. Refer to the figure no. 2.
The operation of LiBr VAM is as follows:

In the present invention water is used as a refrigerant and LiBr solution as an absorbent. The absorber and the evaporator are located in the same shell. The refrigerant water is circulated and sprayed over the evaporator tubes in the evaporator (12) where it is converted into water vapor. These water vapor formed absorbs heat from the chilled water which passes through the evaporator tubes and hence cools the same further the refrigerant water vapor enters the absorber (13) and is absorbed by LiBr solution sprayed over the absorber tubes. The heat of absorption is taken away by cooling water flowing through the absorber tubes. The strong LiBr solution gets weaker in LiBr after absorbing water vapor. The weak solution of LiBr thus formed in the bottom of the absorber is pumped to the high temperature generator (29) by the weak solution pump (20) through the low temperature heat exchanger (17) and the high temperature heat exchanger (18). In the high temperature generator LiBr solution is heated and gets concentrated. The refrigerant water vapor thus formed is sent to tube side of the low temperature generator (17) where the water vapor condenses. The concentrated solution from high temperature generator is sent to the shell side of the low temperature generator (16) where it is further concentrated to form strong solution. The water vapor generated is then condensed in the condenser (15) by cooling water flowing through the condenser tubes. The refrigerant water condensed in the condenser and tube side of the low temperature generator is throttled and returned to the evaporator. The strong solution generated in the low temperature generator (16) is cooled down in the low temperature heat exchanger (17) and spread over the absorber tubes to complete the cycle.
Solid fuels always have some residual heat and in case of power failures or over firing conditions such residual heat can lead to crystallization of

LiBr solution in the HTG itself. To prevent such malfunctioning, a dump condenser (22) is provided. In the dump condenser (22), cooling water is continuously flowing through the cooling tubes (23). Water vapor from the HTG condenses over the tubes and accumulates as liquid in the shell (24) of the dump condenser (22). The bottom of shell is connected to the HTG through a solenoid valve (27) and an isolation valve (28). The solenoid valve (27) is of NC type i.e. it opens only when electrical supply is cut off. When there is power failure, solenoid valve (28) opens and the liquid refrigerant accumulated in the shell is dumped in to LiBr solution in the HTG thus diluting it. This dilution takes care of the residual heat in the furnace and prevents possibility of crystallization of the LiBr solution.
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.