FORM-2
THE PATENT ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003
PROVISIONAL SPECIFICATION
(See section 10 and Rule 13)
FLUIDISED BED THERMIC FLUID HEATER WITH THERMIC FLUID INBED HEAT EXCHANGER


THERMAX LIMITED
an Indian Company of D-13, MIDC Industrial Area, R.D. Aga Road, Chinchwad,Pune-411 019, Maharashtra, India.

THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION


INTRODUCTION TO THE INVENTION:
This invention relates to Fluidised Bed Thermic Fluid Heater with Thermic Fluid Inbed Heat Exchanger.
This invention more particularly relates to the combination of Fluidised bed combustor with Inbed heat exchanger which circulates thermic fluid. Fluidised Bed Thermic Fluid Heater with Thermic Fluid Inbed Heat Exchanger can burn a wide variety of conventional and non-conventional solid fuels more efficiently.
PRIOR ART:
It is already known in the prior art Fluidised Bed Thermic Fluid Heater system which are powered mostly by solid fuel but without any thermic fluid heat exchanger provided inside the fluidized bed due to high risk involved.
DRAWBACKS OF THE PRIOR ART:
1. Low Combustion Efficiency
2. Higher power consumption
3. Higher floor space
4. Higher size of pollution control equipment
OBJECT OF THE INVENTION:
It is therefore a principle object of this invention to propose new concept of Fluidised Bed Thermic Fluid Heater with Thermic Fluid Inbed Heat Exchanger for realizing all the potentials untapped so far.
2

It is another object of this invention to propose use of embedded Heat Exchanger tubes which circulates thermic fluid itself inside the bed of a Fluidised Bed Thermic Fluid Heater which has never been considered feasible.
It is also another object of this invention to propose such a process which will have high thermal efficiency
It is also another object of this is to propose a system which is combination of fluidized bed and thermic fluid inbed heat exchanger in a novel manner so as to be very compact with smaller foot print
It is a further object of this invention to propose such a system which can utilize both conventional and non conventional solid fuels and handling them effectively
It is a further object of the invention to propose such a Fluidised Bed Thermic Fluid Heater with Thermic Fluid Inbed Heat Exchanger wherein greater amount of heat can be recovered at the site of the fluidised bed itself than hitherto possible.
It is a still further object of this invention to propose such Fluidised Bed Thermic Fluid Heater with Inbed Heat Exchanger in which the usual pollution problem can be effectively controlled.
It is an additional object of this invention to propose such a Fluidised Bed Thermic Fluid Heater with Thermic Fluid Inbed Heat Exchanger wherein the thermic fluid is pre-heated before being admitted into the Fluidised Bed Thermic Fluid Heater .
3

A still further object of this invention to propose such a Fluidised Bed Thermic Fluid Heater with Thermic Fluid Inbed Heat Exchanger wherein not only the rate of heat transfer is enhanced but also the heat economy is significantly improved compared to conventional Fluidised Bed Thermic Fluid Heater .
These and other objects in this invention will be apparent from the following paragraphs
In accordance with thin invention there is provided a Fluidized Bed Thermic Fluid Heater with Thermic Fluid Inbed Heat Exchanger.
The heat exchanger in accordance with this invention is capable of burning single or multiple solid fuels.
Particularly, the heat exchanger in accordance with this invention has principally three sections, namely, a first lower most section having means for admission of fluidization air, a second intermediate section, above the said first section having, on a perforated support, a bed of inert solids adopted to be fluidized by fluidization air when admitted through the said first section, the said bed having embedded therein heat transfer tubes adopted for passing thermic fluid to effect heat exchange with the hot fluidised bed, said second intermediate section having means for feeding required fuel thereto, the said third section being provided at the top of the said column having a set of heat exchanger tubes for passing thermic fluid there through, in heat exchange relationship with the hot gases evolved from the fluidised bed, the thermic fluid exit end having means for connecting same to an end
4

use section, the top end of the column having means for connecting it to pollution control equipment and stack.
Still particularly, the heat exchanger in accordance with this invention has an embedded tube which is in the form of straight tubes, coils etc extending substantially to the whole area of the fluidised bed.
Again, the heat exchanger is provided at the top of the column and is separated and spaced apart from the fluidised bed.
The invention in accordance with another aspect of thereof extends to an improved method for the recovery of heat in a thermic fluid fluidised bed heat exchanger wherein a thermic fluid is admitted at the top section of the heat exchanger which is heated by flue gasses passing from the fluidised bed characterised in that a part of the heat generated by the burning of the fuel in the fluidised bed is recovered at the fluidised bed section itself by means of thermic fluid.
Typically, said heating of the thermic fluid in the embedded tubes is carried out by direct heat exchange relationship with fluidized bed.
Typically, the thermic fluid returned from the end user section is directly used in the inbed heat exchanger and the pre-heated thermic fluid is further heated in the fluidised bed heat exchanger at the third section.
In accordance with one embodiment of the invention , a part of the thermic fluid returned from the end user is used in the said inbed heat exchanger while
5

another part of the returned thermic fluid is used in the fluidised bed heat exchanger at the third section and the heated thermic fluid from the inbed heat exchanger and the fluidised bed heat exchanger are used together for end user section.
In accordance with another embodiment all the thermic fluid returned from the end user section is used in the fluidised bed heat exchanger to pre-heat the same and the said pre-heated thermic fluid is then used in the said additional heat exchanger for recovering additional heat from the hot liquid taken from the embedded tubes.
BRIEF DESCRIPTION OF THE DRAWING:
The invention will now be more fully described with reference to the accompanying drawings which are only schematic representation of the Fluidised Bed Thermic Fluid Heater with thermic fluid inbed heat exchanger.
In the accompanying drawings Figure 1 shows a conventional Fluidised Bed Thermic Fluid Heater.
Figures 2 & 3 show one embodiment of the Fluidised Bed Thermic Fluid Heater with Thermic Fluid Inbed Heat Exchanger according to the invention.
Figure 4 shows a second embodiment of the Fluidised Bed Thermic Fluid Heater with Thermic Fluid Inbed Heat Exchanger according to the invention.
6

Figure 5 shows a third embodiment of the improved Fluidised Bed Thermic Fluid Heater with Thermic Fluid Inbed Heat Exchanger according to the invention.
Figure 6 shows a further embodiment of the improved Fluidised Bed Thermic Fluid Heater with Thermic Fluid Inbed Heat Exchanger according to the invention.
Referring now to Figure 1, it \vill be observed that in the conventional Fluidised Bed Thermic Fluid Heater -f, necessary air is supplied by fan-3 and the air travels upwards through a hot fluidised bed-2.
The fluidised bed is made of inert solids which can be selected from silica sand, refractory grog etc of suitable particle sizes.
The necessary fuel can be selected from coal / rice husk / lignite and other agro-waste fuels and the fuel is fed into the bed by any known standard fuel feeding system with all accessories and is not shown in the figure.
The space above the fluidised bed is provided with heat exchange tubes-4 through which the thermic fluid to be heated is pumped by pump-5.
In a conventional heat exchange between the hot gases and thermic fluid, heat recovery rate is limited and hence for a fixed amount of heat to be recovered, the whole system becomes large and is not economical.
Referring now to Figure-2, it will be noticed that there is an inbed heat exchanger 6 embedded in the fluidised bed-2 itself. This heat exchanger-6is provided with supply of thermic fluid from thermic fluid pump - 5.
7

This thermic fluid extracts substantial amount of heat from the fluidised bed and is heated to a temperature depending upon the type of the fluid and conditions of the circulation.
The preheated thermic fluid leaving the heat exchanger-6, is then introduced into the conventional heat exchanger tubes- 4, provided at the top end of the body of the Fluidised Bed Thermic Fluid Heater . The heated thermic fluid is sent for the end uses.
In both figures 1&2, the exhaust gases leaving the Fluidised Bed Thermic Fluid Heater is subjected to usual pollution control in the pollution control equipment. Additional heat can be recovered in an air pre-heated APH.
In both the instances the flue gas can be exhausted into the stack or further heat can be recovered from it by pre-heating combustion / fluidising air in any known air pre-heater APH.
Figure-3 is a replica of Figure-2 only shown in a different manner. In this Figure the thermic fluid is first admitted to the heat exchanger-6, preheated and then admitted to the convection bank - 4, from where it picks up additional heat and then sent for end uses.
It will thus be observed from Figure-3, that pre-heated air is blown into Fluidised Bed Thermic Fluid Heater with thermic fluid inbed heat exchanger.
8

The thermic fluid is passed through the inbed heat exchanger-6 as in Figure-2, which is heated and the pre-heated thermic fluid is sent to the convention bank-4 at the top of the Fluidised Bed Thermic Fluid Heater as in Figure-2 and the heated thermic fluid is sent to end uses.
The air stream or the flue gas is treated in the same manner as in Figure-2.
Figure-4 is the same as Figure-3 excepting for the reverse flow of the thermic fluid, first through the convection bank-4 and then through inbed heat exchanger-7. Thus in Figure-4 the thermic fluid is pre-heated in the convection bank picking up heat from the flue gases and then further heated in the inbed heat exchanger-6 picking up heat from the fluidised bed. The flue gases exiting the convention bank is used to preheat incoming air in an air pre-heater and then sent to the stack.
While considerable emphasis has been placed herein on the particular features of the preferred embodiment and the improvisation with regards to it, it will be appreciated the various modifications can be made in the preferred embodiments without departing from the principles of the invention. These and the other modifications in the nature of the invention will be apparent to those skilled in art from disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to interpreted merely as illustrative of the invention and not as a limitation.
Dated this 5th day of June, 2008
Monan Dewan Applicants' Patent Agent
9