FORM-2 THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE
Specification
(See section 10; rule 13)


MULTI NON-UNIFORM USERS HEAT EXCHANGE SYSTEM
THERMAX LIMITED
an Indian Company
of D-13, MIDC Industrial Area, R. D. Aga Road, Chinchwad,
Pune 411 019, Maharashtra, India
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED


Field of invention
The present invention relates to the thermosyphon system.
More particularly this system relates multi non- uniform users heat exchange system.
Background and Existing knowledge
It is already known that the thermosyphon system works on natural convection. Thermosyphon refers to a method of passive heat exchange based on natural convection, which circulates liquid in an operative vertical closed-loop circuit without requiring a conventional pump.
Convective movement of the liquid starts when liquid in the loop is heated, causing it to expand and become less dense, and thus more buoyant than the cooler water in the operative bottom of the loop. Convection moves heated liquid upwards in the system as it is simultaneously replaced by cooler liquid returning by gravity. In many cases, the liquid flows easily because the thermosyphon is designed to have very little hydraulic resistance.
To operate any heat exchanging equipment pump is used to circulate the fluid. To operate pump lots of energy and electric charge is used; this in turn raises the economy of the system. Moreover, the energy loses while using pump is also considerable. Hence, there is a need to save energy and have a system where there is less energy loss.
Because of the higher fuel oil, cost there is shift in using solid fuels has increased. The existing solid fuel fired system has low combustion efficiency; moreover, the primitive solid fuel fired systems are incapable of handling many
i

non-conventional fuels. Hence, there is need of the combustion system, which can comparatively provide high combustion efficiency and can handle variety of fuels. Above all there is a need of system which should me ecofriendly and can meet the standards set by the pollution control board.
Existing knowledge
US3902819 describes a turbo machinery blade operating at elevated temperature. It is in a strong centrifugal field. It is cooled by a coolant loop located within the blade constituting an open, mixed convection, thermosyphon system utilizing water as the coolant. The density difference is established in the coolant within the loop by injecting cooler water into one portion of the loop and extracting coolant fluid from another portion of the loop to maintain system pressure and coolant mass at desired levels to there by establish continuous coolant recirculation within the coolant loop. However, this invention is restricted to only turbo machinery blade.
US7055339 describes an invention directed towards an improved heat recovery system. More particularly, the invention describes improved water heating method that utilizes the thermosyphon and coriolus effects to produce a more efficient and cost effective water heater. However, the invention is restricted to only water heating only.
Object of the invention
It is therefore a primary object of this invention to provide an improved process for the optimum utilization of solid fuels in a fluidized bed combustor

It is another object of this invention to provide such a process, which will be environmental friendly by producing less pollution by way of capturing sulfur during the process
It is also another object of this invention to provide such a process, which will have high thermal efficiency
It is also another object of this is to provide a system, which is combination of fuel source and thermosyphon in a novel manner to be very compact with smaller footprint
It is also another object of this invention to provide a Fluidized bed combustor with or without in-bed heat extraction depending on the fuel burnt for Thermosyphon system.
It is a further object of this invention to provide such a system, which can utilize both conventional and non-conventional solid fuels and handling them effectively
It is also another object of this invention to provide a thermosyphon system capable of simultaneously catering to multiple user conditions of pressure and temperature
Summary of the invention
In accordance with the present invention there is provided a multi non- uniform users heat exchange system comprising
4

a heat source;
a primary heat exchanger adapted to extract heat from said heat source;
a first heat transfer media adapted to be circulated in said primary heat
exchanger by thermo siphon system;
an intermediate heat exchangers adapted to extract heat from said
primary heat exchanger;
a second heat transfer media adapted to be circulated in said intermediate
heat exchanger by thermo siphon system;
a plurality of user point for dissipating said extracted heat;
a plurality of heat transfer media adapted to be circulated in said user
points by thermo siphon system;
an intermediate heat exchangers connected to primary heat exchanger and
to said user points; characterized in that said user points are adapted to
operate at unequal pressures and/or temperatures.
Typically, the primary heat exchanger is adapted to be positioned within said heat source.
Typically, an aeration grid is provided in said heat source.
Typically, said heat source is provided with fuel metering and feeding apparatus.
Typically, said heat source is provided with an in bed heat exchanger adapted to control flue gas temperature.
5

Typically, said heat source is selected from a group of heat source consisting of electrical heater, exhaust gas recovery, supplementary-fired exhaust gas recovery, fluidized bed combustor, oil fired heat source and solar heat source.
Typically, said primary exchanger is selected from a group of heat exchanger consisting of shell and tube, plate type, floating header type and kettle type.
Typically, said first heat transfer media is selected from group of media consisting of thermic fluid and water.
Typically, said primary heat exchanger is provided with flue gas outlet adapted to remove unwanted flue gas from said primary heat exchanger.
Typically, said intermediate heat exchanger is selected from a group of heat exchanger consisting of shell and tube, plate type, floating header type and kettle type.
Typically, said second heat transfer media is selected from group of media consisting of thermic fluid and water.
Typically, said heating media is circulated without using electrically or mechanically driven pump.
Typically, pollution control equipment is provided with purification unit to purify the unwanted flue gas before releasing it in air.
6

In accordance with this invention there is also provided a method for providing heat at unequal pressure and/or temperature conditions in a multi non- uniform users heat exchange system; said method comprising the following steps,
burning fuel in a heat source to generate heat;
extracting said heat from said heat source;
dissipating said heat from said heat source to primary heat exchanger;
circulating a heat transfer medium by thermo siphon system in said
primary heat exchanger;
dissipating said heat from said primary heat exchanger to intermediate
heat exchanger;
circulating a heat transfer medium by thermo siphon system in said
intermediate heat exchangers;
dissipating said heat from said intermediate heat exchanger to user points
at unequal pressure and /or temperature conditions;
circulating a heat transfer medium by thermo siphon system in said user
points and
circulating heat depleted heat transfer medium from user points to the
primary heat exchanger by thermo siphon system.
Brief description of accompanying drawings:
The invention will now be described with respect to the accompanying drawings in which:
Figure 1- illustrates the complete apparatus with one set of user points in accordance with this invention and;
7

Figure 2- illustrates the complete apparatus with higher set of user point, which allows user point to work at different pressure and temperature conditions.
Detail description of the invention with reference to the accompanying drawings:
Figure 1: The invention consists of a heat source (1). Fuel is fired from the fuel feeder (2)in the heat source (1). The combustor is provided with or without in-bed heat exchanger (IBH) (3).The purpose of IBH is to extract unwanted heat. The air inside the combustor is supplied either by natural draft or by blower (4) through aeration grid (4A). The combustion product (flue gas 5) is passed in the primary heat exchanger (6). This heat exchanger is placed at intermediate level between the heat source (1) and user points (7) and (8).The heat from the flue gas is transferred to the heat transfer medium in the primary heat exchanger. Generally, water or any thermic fluid is used as the heat transfer medium. When this heat transfer medium gets heated, it travels through the transfer pipe (9) to the user point (7) and (8). Heat transfer medium in the primary heat exchanger and the user point may or may not remain same. The heat-depleted heat transfer medium is returned through the return pipe (10) to the heat source (1) having an in bed heat exchanger (3) by thermo siphon system. The user point is located above the thennosyphon system to facilitate the flow of heat transfer medium back to the convective heat exchanger. With this system, the heated medium works at same temperature and pressure conditions. Pressure in the primary heat exchanger and the user point (7) and user point (8) will remain same.
The final flue gases are exited through flue gas outlet (11).This is achieved with the help of exhaust assisted by fan (12). The flue gas before exiting through the
8

exhaust system, pass through pollution control equipment (13) to check the permitted level of unwanted gas. The checked flue gas is then permitted to pass through chimney (14).
Figure 2: The invention consists of a heat source (1). Fuel is fired from the fuel feeder (2) in the heat source (1). The combustor is provided with or without in-bed heat exchanger (IBH) (3).The purpose of IBH is to extract unwanted heat. The air inside the combustor is supplied either by natural draft or by blower (4) through aeration grid (4A). The combustion product (flue gas 5) is passed in the primary heat exchanger (6). This heat exchanger is placed at intermediate level between the heat source (1) and user points (7) and (8).The heat from the flue gas is transferred to the heat transfer medium in the convective heat exchanger. Generally, water or any thermic fluid is used as the heat transfer medium. When this heat transfer medium gets heated, it travels through the transfer pipe (9) to the user point (7) and (8). Heat transfer medium in the primary heat exchanger and the user points may or may not remain same. The heat-depleted heat transfer medium is returned through the return pipe (10) to the heat source (1) having an in bed heat exchanger (3) by thermo siphon system. A closed loop is formed with the user point (7) to dissipate heat to another user point (15) at unequal pressure and/or temperature condition. Similarly, another closed loop is formed with the user point (8) to dissipate heat to various other user points (16) at unequal pressure and/or temperature condition. User point (17) is allowed to work at slightly lower pressure and/or temperature condition with that of user point (16). Hence, it is possible to obtain a plurality of user point to work at equal and/or unequal pressure and /or temperature condition in accordance with the present invention. The user point
9

is located above the thermosyphon system to facilitate the flow of heat transfer medium back to the convective heat exchanger
By introducing an intermediate heat exchanger, it is possible that the user point can get the heated medium at different pressure and temperature and can use the heated medium at different pressure and temperature conditions.
The final flue gases are exited through flue gas outlet (1 l).This is achieved with the help of exhaust assisted by fan (12). The flue gas before exiting through the exhaust system, pass through pollution control equipment (13) to check the permitted level of unwanted gas. The checked flue gas is then permitted to pass through chimney (14).
The invention will now be described with respect to the following examples, which do not limit the invention in any way and only exemplify the invention.
Example 1
For an application with the following two users.
User point 1:
Operating pressure: 95 bar
Heat duty : 1000000 kcal/h
User point 2:
Operating pressure: 65 bar
Heat duty : 1000000 kcal/h
10

Option 1 Option 2
1 Type INo of Conventional Fuel Fired thermo siphon system 1 No of Multi non-uniform users heat exchange system 1 No of Multi non-uniform users heat exchange system
2 Heat duty 2000000 kcal/h 1000000 kcal/h 1000000 kcal/
3 Combustor FBC FBC FBC
4 Efficiency 80% 80% 80%
5 Operating pressure 95 bar 95 bar 65 bar
6 Foot print X 0.6X to0.8X
7 Operators X 2X
8 Investment X 1.3X to 1.5X
Table 1 To cater to these two-user points conventional fuel fired thermo siphon system is not viable. Hence two smaller user points has to be deployed. Whereas, Multi non-uniform users heat exchange system can be deployed as shown in the table below, which gives a tremendous advantage in the operating cost. The increase in operating cost will further increase with the number of smaller units being serviced by the heaters.
11

Example 2: For an application with the following two small user points User point 1:
Operating pressure : 95 bar
Heat duty : 500000 kcal/h
User point 2:
Operating pressure: 65 bar
Heat duty : 500000 kcal/h

Option 1 Option 2
1 Type 1 No of Multi non-uniform users heat exchange
system 1 No of Multi non¬uniform users heat exchange system 1 No of Multi non-uniform users heat exchange system
2 Heat duty 1000000 kcal/h 500000 kcal/h 500000 kcal/
3 Combustor FBC Non FBC Non FBC
4 Efficiency 80% 65% 65%
5 Operating pressure 95 bar 95 bar 65 bar
6 Foot print X 0.6X to0.8X
7 Operators X 2X
8 Investment X 1.3X to 1.5X
9 Operating cost X >1.2X
Table 2
12

We Claim:
1. A multi non- uniform users heat exchange system comprising:
• heat source;
• primary heat exchanger adapted to extract heat from said heat source; a first heat transfer media adapted to be circulated in said primary heat exchanger by thermo siphon system;
• intermediate heat exchangers adapted to extract heat from said
primary heat exchanger;
a second heat transfer media adapted to be circulated in said intermediate heat exchanger by thermo siphon system;
• a plurality of user point for dissipating said extracted heat;
a plurality of heat transfer media adapted to be circulated in said user points by thermo siphon system;
• said intermediate heat exchangers connected to primary heat
exchanger and to said user points; characterized in that said user
points are adapted to operate at unequal pressures and/or
temperatures.
13

2. A multi non- uniform users heat exchange system as claimed in claim 1; wherein said primary heat exchanger is adapted to be positioned within said heat source.
3. A multi non- uniform users heat exchange system as claimed in claim 1; wherein an aeration grid is provided in said heat source.
4. A multi non- uniform users heat exchange system as claimed in claim 1; wherein said heat source is provided with fuel metering and feeding apparatus.
5. A multi non- uniform users heat exchange system as claimed in claim 1; wherein heat source is provided with an in bed heat exchanger adapted to control flue gas temperature.
6. A multi non- uniform users heat exchange system as claimed in claiml; wherein said heat source is selected from the group of heat source consisting of electrical heater, exhaust gas recovery, supplementary fired exhaust gas recovery, fluidized bed combustor, oil fired heat source and solar heat source.
7. A multi non- uniform users heat exchange system as claimed in claim 1; wherein said primary exchanger is selected from a group of heat exchanger consisting of shell and tube, plate type, floating header type and kettle type.
14

8. A multi non- uniform users heat exchange system as claimed in claim 1; wherein said first heat transfer media is selected from group of media consisting of thermic fluid and water.
9. A multi non- uniform users heat exchange system as claimed in claim 1; wherein said primary heat exchanger is provided with flue gas outlet adapted to remove unwanted flue gas from said primary heat exchanger.
10. A multi non- uniform users heat exchange system as claimed in claim 1; wherein said intermediate heat exchanger is selected from a group of heat exchanger consisting of shell and tube, plate type, floating header type and kettle type.
1 l.A multi non- uniform users heat exchange system as claimed in claim 1; wherein said second heat transfer media is selected from group of media consisting of thermic fluid and water.
12.A multi non- unifonn users heat exchange system as claimed in claim 8; wherein said heating media is circulated without using electrically or mechanically driven pump.
13.A multi non- unifonn users heat exchange system as claimed in claim 1; wherein pollution control equipment is provided with purification unit to purify the unwanted flue gas before releasing it in air.
15

14. A method for providing heat at unequal pressure and/or temperature conditions in a multi non- uniform users heat exchange system; said method comprising the following steps,
• burning fuel in a heat source to generate heat;
• extracting said heat from said heat source;
• dissipating said heat from said heat source to primary heat exchanger;
• circulating a heat transfer medium by thermo siphon system in said primary heat exchanger;
• dissipating said heat from said primary heat exchanger to intermediate heat exchanger;
• circulating a heat transfer medium by thermo siphon system in said intermediate heat exchangers;
• dissipating said heat from said intermediate heat exchanger to user points at unequal pressure and /or temperature conditions;
• circulating a heat transfer medium by thermo siphon system in said user points and
• circulating heat depleted heat transfer medium from user points to the primary heat exchanger by thermo siphon system.
Dated this 10th day of December, 2008.

Mohl
OfRjLDewan&Co. Applicants' Patent Attorneys

16