FIELD OF THE INVENTION
[001] The present invention relates to a method for recovering waste heat which pass through thermoelectric generator from boiler. More particularly, the present invention relates to a structural arrangement in Boiler flue gas duct for increasing boiler combustion air temperature by using heat rejection of thermoelectric generator. Furthermore, improvement in the arrangement of Boiler gas duct is leading to the recovery of waste heat from Thermoelectric generator for its effective utilization in Boiler furnace.
BACKGROUND OF THE INVENTION
[002] Background description includes information that may be useful in understanding the present subject matter. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed subject matter, or that any publication specifically or implicitly referenced is prior art.
[003] There is a huge wastes of heat in the field of thermoelectric generation. Between half to two-third of the fuel is used to burn to create energy, which is being dissipated as heat into the atmosphere leading to enormous pollution and hence, global warming. While it has been known for long that this waste heat is converted into energy. Early thermoelectric generation systems were bearing low efficiency limiting the process’s usefulness. In the absorption of Heat from the boiler flue gas, which can be harvested into energy with the addition of thermoelectric generator in the boiler flue gas duct.
[004] Thermoelectric generators (and also called thermo generators) are essentially devices designed to convert heat into electricity, using two materials at different temperatures, directly into electrical energy. The greater the temperature difference between the “hot” side and the “cold”

side, the more power can be produced. The open circuit voltage is directly proportional to temperature difference across the Thermoelectric generator. A few related prior arts are discussed in below:
[005] The cited prior art US 7687704 discussed a thermoelectric generator that reduces the size of an entire exhaust apparatus for an internal combustion engine, while ensuring the amount of electric power generated by a thermoelectric generation element and the purging effect of a catalyst device. The thermoelectric generator includes a catalyst device, arranged in the exhaust passage, for purging exhaust. A thermoelectric generation element, which is arranged on the catalyst device, converts thermal energy of the exhaust passing through the exhaust passage to electric energy. The thermoelectric generation element is arranged at a downstream portion of the catalyst device with respect to the flow of the exhaust.
[006] Another cited prior art US20110146743 disclosed an exhaust system for a combustion engine, more preferably of a road vehicle, with at least one exhaust gas-conducting component having a ring-shaped closed inner wall in circumferential direction, whose inner side is exposed to the exhaust gas. The energetic efficiency of the combustion engine can be improved with at least one thermoelectric generator which converts heat into electric energy and which is arranged on an outer side of the inner wall.
[007] The aforementioned cited patents documents have suggested TEGs for exhaust of internal combustion engine. Whereas, the present invention relates the waste heat recovery from flue gas through thermoelectric generator for Boiler application in Thermal power plants. The rejected heat of the thermoelectric generator can be used for combustion in boiler. The novel arrangement of the annular ducting system is presented here. Hence the searched US patent though similar in nature but not relevant to the present invention.

[008] Hence, there is a requirement of a method and system for recovering the waste heat from boiler by overcoming the problems as discussed above.
OBJECTS OF THE INVENTION
[009] In view of the foregoing limitations inherent in the state of the art, some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed herein below.
[011] The primary objective of the invention is to provide a method for recovering waste heat which pass through thermoelectric generator from boiler for generating thermoelectric power.
[010] Another object of the invention is to configure a structural arrangement of thermoelectric generator in Boiler flue gas duct for absorption of heat rejected by Thermoelectric generator in Chimney.
[012] Yet another object of the invention is to explore the suitable positioning of thermoelectric generator for effective absorption of heat reject.
[013] Still another objective of the invention is ensuring availability of additional heat input for Boiler furnace due to the absorption of heat reject from Thermoelectric generator in Boiler flue gas duct.
[015] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.
SUMMARY OF THE INVENTION
[016] One or more drawbacks of conventional system/method of boiler structure for recovering waste heat and other problems are overcome, and additional advantages are provided through the system in the present

disclosure. With boiler flue gas reaching temperatures of about 150˚C, the enormous surface area of the flue gas duct would be capable of generating the electricity, which in turn improves the boiler efficiency. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure.
[017] In boiler flue gas duct, the flue gas temperature is around 150˚C, heat is recovered by introducing TEG (thermoelectric generator) with hot side attached to hot surface of duct and cold side attached to extended surface under cooling fan positioned between stiffeners on the duct surface. More than 90% of heat rejected through thermoelectric generator and these heats are collected by another annular ducting system. The flow of annular ducting system is counter flow which is against the flow of flue gas flow. The air of annular air ducting system is used for combustion in boiler and the annular duct is connected to fan.
[018] The cold side of the Thermoelectric Generator with extended surface is exposed to air in annular ducting for enhancing heat transfer. The proposed invention is related to a method and system for recovering waste heat and generating thermoelectric power from boiler exhaust flue gas. The structural arrangement is required to form a waste heat thermoelectric recovery system which is an annular ducting system. The structural arrangement includes of the structural material like retainer type-A, casing support and out casing duct plate of the arrangement Thermoelectric waste heat recovery system in Boiler flue gas duct. A 6 mm diameter fixing pin is to hold the thermoelectric cooling air duct system through support type-A retainer placed in parallel to duct plate. The casing support is placed on three successive retainers-A by self-tapping screw, which is to hold the outer wall arrangement of annular duct. The longitudinal and transverse

pitch of 6 mm diameter fixing pin is having length of 480 mm and 240 mm respectively for the proposed structural arrangement of thermoelectric waste heat recovery system in Boiler flue gas duct. A four edge of the plate segments are welded with angles to make a segments of annular duct wall arrangement. One or more segments of annular duct wall arrangement are connected with bolts and nuts to easy remove and attend maintenance of TEG during overhauling. One or more segments of annular duct wall arrangement are formed an annular ducting system.
[017] The present invention is directed to a method for recovering waste heat by using a system in the boiler flue gas duct, the method comprising the steps of: doing a structural arrangement for forming an annular ducting system (25) in the boiler; placing a plurality of thermoelectric generator (TEG) to receive waste heat from the boiler flue gas, wherein each of the TEG device has a TEG hot surface (13) configured to be positioned in thermal communication with boiler flue gas duct and a TEG cold surface with extended surface, exposed to air in annular ducting for enhancing heat transfer through heat sink (12); passing flue gas (26) through one or more zone; and converting heat into electricity by using said TEG device by maintaining high temperature difference between hot side and cold side of TEG device, wherein a plurality of thermoelectric modules formed by joining of P-type semiconductor and N-type semiconductor, and a side of each of P-type semiconductor or N-type semiconductor, is in contact with the hot temperature of boiler flue gas duct, and other side of each of N-type semiconductor or P-type semiconductor, is in contact with one or more extended surface exposed to cold air, to generate electricity caused by temperature difference across TEG devices.
[019] In the aspect of the present invention, the present invention is having following features:

(i) said annular duct system (25) is configured by connecting one or more segments of annular duct wall arrangement, wherein a segment of annular duct wall arrangement (24) is configured by welding of a plate (23) segments with four edge and a “L” shape angles (17), and wherein one or more annular duct arrangement (24) are connected with bolts and nuts (16) for easy assembly and dismantling the segments;
(ii) the thermoelectric generator module (13) is held tightly by holding bolt and nuts (11);
(iii) all the thermoelectric generators are arranged in square pitch as transverse and longitudinal pitch arranged on the boiler flue gas duct with in the stiffeners arrangement of boiler flue gas ducting system;
(iv) the flue gas flows from air heater outlet to ESP inlet duct and directed the flue gas from ESP outlet to inducted draft (ID) fans inlet (5) and further directed the flue gas from ID fan outlet to chimney inlet duct (7).
[020] The preferred embodiment of the present invention is having other features and advantages which are disclosed in the appended dependent claims.
[021] Other objects, features, and advantages of the present disclosure will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating specific embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

[022] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
[023] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of apparatus that are consistent with the subject matter as claimed herein, wherein:
[024] Fig. 1 illustrates an embodiment of elevation view of typical thermal power plant according to the prior art.
[025] Fig. 2 illustrates an embodiment of top view of typical thermal power plant according to the prior art.
[026] Fig. 3 illustrates an embodiment of elevation view of thermal power plant with an arrangement of waste heat thermoelectric recovery system and increasing combustion air temperature.
[027] Fig. 4 illustrates an embodiment of top view of thermal power plant with arrangement of waste heat thermoelectric recovery system and increasing combustion air temperature.
[028] Fig. 5 illustrates an embodiment of the cross section view of an arrangement of Thermoelectric waste heat recovery system in Boiler flue gas duct according to the present invention. The waste heat recovery system in Boiler flue gas duct is the annular ducting system (25) as shown in fig 7.

[029] Fig. 6 illustrates an embodiment of the longitudinal cross section view of arrangement of Thermoelectric waste heat recovery system in Boiler flue gas duct according to the present invention. The waste heat recovery system in Boiler flue gas duct is the annular ducting system (25) as shown in fig 7.
[030] Fig. 7 illustrates an embodiment of the isometric view of arrangement of Thermoelectric waste heat recovery system in Boiler flue gas duct according to the present invention. The waste heat recovery system in Boiler flue gas duct is the annular ducting system (25) as shown in fig 7.
[031] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION OF THE INVENTION:
[032] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[033] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting

principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes”, “consisting” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[035] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[036] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[037] The present invention is directed to a method and a system for recovering heat from boiler flue gas and transferring this heat to convert into thermoelectric power by using thermoelectric generator and further

transferring heat into the boiler again by ensuring availability of additional heat input for Boiler furnace.
[038] Further, the present invention is directed to a method for recovering waste heat by using a system in the boiler flue gas duct, the method comprising the steps of: doing a structural arrangement of an annular ducting system (25) in the boiler; placing a plurality of thermoelectric generator (TEG) to receive waste heat from the boiler flue gas, wherein each of the TEG device has a TEG hot surface (13) configured to be positioned in thermal communication with boiler flue gas duct and a TEG cold surface with extended surface, exposed to air in annular ducting for enhancing heat transfer through heat sink (12); passing flue gas (26) through one or more zone; and converting heat into electricity by using said TEG device by maintaining high temperature difference between hot side and cold side of TEG device, wherein a plurality of thermoelectric modules formed by joining of P-type semiconductor and N-type semiconductor, and a side of each of P-type semiconductor or N-type semiconductor, is in contact with the hot temperature of boiler flue gas duct, and other side of each of N-type semiconductor or P-type semiconductor, is in contact with one or more extended surface exposed to cold air, to generate electricity due to seebeck effect caused by temperature difference across TEG devices. Further, the claimed system is an annular duct system (25) which is configured by connecting one or more segments of annular duct wall arrangement, wherein a segment of annular duct wall arrangement (24) is configured by welding of a plate (23) segments with four edge and a “L” shape angles (17), and wherein one or more annular duct arrangement (24) are connected with bolts and nuts (16) for easy assembly and dismantling the segments.

[039] In the present invention, Fig. 1 illustrates the elevation view and Fig. 2 illustrates the plan view of typical Thermal power plant layout where heat flows from Boiler furnace (1) into Air heater (2) to Chimney (8) in Boiler flue gas duct (3,5,7) through Electrostatic Precipitator (4) and FD fan (6). In boiler flue gas duct, the flue gas temperature is around 150˚C, heat is recovered by introducing TEG with hot side attached to hot surface (2) of duct and cold side (23) attached to extended surface under cooling air annular ducting arrangement. The enormous surface area of the flue gas duct would be capable of generating the electricity, which in turn improves the boiler efficiency.
[040] In the present invention, Figure. 3 illustrates the elevation view and Fig. 4 illustrates the plan view of proposed plant layout where an outer duct (3,5,7) are introduced for placing Thermoelectric generator (9) in the area after Air heater (2) till Chimney inlet (10) for effective absorption of dissipated heat in the existing duct arrangement. More than 90 % of heat is rejected through thermoelectric generator and these heats are collected by another annular ducting system. The flow of annular ducting system is counter flow which is against the flow of flue gas flow. The air of annular air ducting system is used for combustion in boiler and the annular duct is connected to fan.
[038] In the embodiment of the present invention, Fig. 5, Fig. 6 and Fig. 7 illustrates the cross section, the longitudinal cross section and isometric view of an arrangement of thermoelectric waste heat recovery system in Boiler flue gas duct, according to the present invention. Thermoelectric Generator assembly setup is used for Boiler Flue gas duct (3) wall where the waste hot flue gas flows through the inlet from air heater (2) and comes out up to chimney (8). In Boiler flue gas duct (3), there are stiffeners (14)

holding the duct (3) preventing from buckling. So, full occupancy of duct surface area cannot be done with Thermoelectric Generator (13). Thermoelectric Generator (TEG) (13) is placed directly on those areas between these stiffeners (14) on hot surface of the duct (3) and cold side wherein cold side is placed on the extended surface (12) which is exposed to air in annular duct arrangement. The heat flow direction (26) is shown in Fig. 5 and Fig. 6 from flue gas to cold air. The Thermoelectric Generator module (13) is then held tightly by the holding bolt and nuts (11) which reduces the gap (20) between Thermoelectric Generator (13) to hot side and cold side in the assembly setup. Thermal interface material (20) is introduced between hot side of Thermoelectric Generator (13) and Flue gas duct (3); and cold side of Thermoelectric Generator (13) and extended surface (12). The thermal conductivity of Thermal interface material should be adequate enough to maintain high temperature difference between hot side and cold sides TEG.
[039] The cold side of the Thermoelectric Generator (13) with extended surface is exposed (12) to air in annular ducting for enhancing heat transfer. The apparatus for structural arrangement comprises of the structural material like retainer type-A (15), casing support (21) and out casing duct plate (18) of the arrangement Thermoelectric waste heat recovery system in Boiler flue gas duct. A 6 mm diameter fixing pin (19) is to hold the thermoelectric cooling air duct system (18) through support type-A retainer (15) placed in parallel to duct plate (3). The casing support (21) is placed on three successive retainers-A (15) by self-tapping screw (22), which shall hold the outer wall arrangement of annular duct (18). The outer wall arrangement of annular duct (6) is shaped to substantially conform to the outer surface of the base plate structure like duct (3). The longitudinal and transverse pitch of 6 mm diameter fixing pin (19) is having length of 480 mm and 240 mm respectively for proposed structural arrangement of

thermoelectric waste heat recovery system in Boiler flue gas duct. The thermoelectric waste heat recovery system in Boiler flue gas duct is the annular duct system (25). Fig. 5 illustrates the isometric view of annular duct wall arrangement and a segments of annular duct wall arrangement is comprising plates (23) and angles (17). A four edge of the plate (23) segments are welded (18) with “L-shape” angles (17) to make a segments of annular duct wall arrangement (24). One or more segments of annular duct wall arrangement (24) are connected with bolts and nuts (16) to easy remove and attend maintenance of TEG during overhauling. One or more segments of annular duct wall arrangement are formed an annular ducting system (25).
[040] A thermoelectric generator (TEG) is a solid-state device, which can directly convert heat into electricity which is based on the discovery of Seebeck effect by which temperature difference across the TEG is directly converted into heat. In order to maintain a high temperature difference across a TEG (13) heat must efficiently move from the heat source to the hot side of a TEG (13) and also be efficiently drawn from the cold side of the TEG (13) to a cold air duct through heat sink (12). The hot side of the TEG is facing towards flue gas duct and cold side of TEG is facing towards cold air annular duct.
[041] Moreover the claim system is an annular ducting system (25) formed by using said structural arrangement for recovery of waste heat from the boiler flue gas as claimed in claim 1 , the system comprises: a pre-determined diameter fixing pin (3) to hold the thermoelectric cooling air duct system (18) through support type-A-retainer (15) placed in parallel to duct plate (3) and the casing support (21) is placed on three successive retainer-A (15) by self tapping screw (22) that hold the outer wall arrangement of annular duct (18); the longitudinal pitch and the transverse pitch are fixed with said fixing pin, for waste heat recovery system in boiler

flue gas duct, wherein the length of the longitudinal pitch is 480mm and the length of transverse pitch is 240mm; a four edge of the plate (23) segments are welded with L-shaped angle (17) to make a segments of annular duct wall arrangement (24); one or more segments of annular duct wall arrangement (24) are connected with bolts and nuts (16) for easy assembly and dismantling the segments; and one or more segments of annular duct wall arrangement are connected together to form said annular ducting system (25). The technical advantages of the present invention are illustrated in below:
TECHNICAL ADVANTAGES:
[042] One of the advantages of the present invention is to improve efficiency in terms of additional heat input for boiler furnace according to the claimed system.
[043] Another advantages of the present invention is to generate thermoelectric power by recovering the waste heat of boiler flue gas. [044] Another advantages of the present invention is to generate thermoelectric power by recovering the waste heat of boiler flue gas. [045] Another advantage of the present invention is that the proposed invention is used for increasing boiler combustion air temperature by using heat rejection of thermoelectric generator.
[046] Thus, the present invention is achieving the cost savings through additional heat input for boiler and performance improvement by using the proposed method.
[047] Furthermore, each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the “invention” may in some cases refer to certain specific embodiments only. In other cases, it

will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims. [048] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.
[049] Furthermore, those skilled in the art can appreciate that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[050] The claims, as originally presented and as they may be amended,
encompass variations, alternatives, modifications, improvements,
equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[051] While the foregoing describes various embodiments of the present disclosure, other and further embodiments of the present disclosure may

be devised without departing from the basic scope thereof. The scope of the present disclosure is determined by the claims that follow. The present disclosure is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

We claim:
1. A method for recovering waste heat by using a system in the boiler flue gas duct, the method comprising the steps of :
- doing a structural arrangement of an annular ducting system (25) in the boiler;
- placing a plurality of thermoelectric generator (TEG) to receive waste heat from the boiler flue gas, wherein each of the TEG device has a TEG hot surface (13) configured to be positioned in thermal communication with boiler flue gas duct and a TEG cold surface with extended surface, exposed to air in annular ducting for enhancing heat transfer through heat sink (12);
- passing flue gas (26) through one or more zone; and
- converting heat into electricity by using said TEG device by maintaining high temperature difference between hot side and cold side of TEG device, wherein a plurality of thermoelectric modules formed by joining of P-type semiconductor and N-type semiconductor, and a side of each of P-type semiconductor or N-type semiconductor, is in contact with the hot temperature of boiler flue gas duct, and other side of each of N-type semiconductor or P-type semiconductor, is in contact with one or more extended surface exposed to cold air, to generate electricity due to Seebeck effect caused by temperature difference across TEG devices.
2. The method as claimed in claim 1, wherein said annular duct
system (25) is configured by connecting one or more segments of annular duct wall arrangement, wherein a segment of annular duct wall arrangement (24) is configured by welding of a plate (23) segments with four edge and a “L” shape angles (17), and wherein one or more annular duct arrangement (24) are connected with

bolts and nuts (16) for easy assembly and dismantling the segments.
3. The method as claimed in claim 1, wherein thermoelectric generator module (13) is held tightly by holding bolts and nuts (11).
4. The method as claimed in claim 1, wherein all the thermoelectric
generators are arranged in square pitch as transverse and
longitudinal pitch arranged on the boiler flue gas duct with in the
stiffeners arrangement of boiler flue gas ducting system.
5. The method as claimed in claim 1, wherein the flue gas (26) flows from air heater outlet to ESP inlet duct and directed the flue gas from ESP outlet to inducted draft (ID) fans inlet (5) and further directed the flue gas from ID fan outlet to chimney inlet duct (7).
6. An annular ducting system (25) formed by using said structural arrangement for recovery of waste heat from the boiler flue gas as claimed in claim 1 , the system comprises:

a) a pre-determined diameter fixing pin (3) to hold the thermoelectric cooling air duct system (18) through support type-A-retainer (15) placed in parallel to duct plate (3) and the casing support (21) is placed on three successive retainer-A (15) by self tapping screw (22) that hold the outer wall arrangement of annular duct (18);
b) the longitudinal pitch and the transverse pitch are fixed with said fixing pin, for waste heat recovery system in boiler flue gas duct, wherein the length of the longitudinal pitch is 480mm and the length of transverse pitch is 240mm;

c) a four edge of the plate (23) segments are welded with L-shaped angle (17) to make a segments of annular duct wall arrangement (24);
d) one or more segments of annular duct wall arrangement (24) are connected with bolts and nuts (16) for easy assembly and dismantling the segments; and
e) one or more segments of annular duct wall arrangement are connected together to form said annular ducting system (25).

7. The system as claimed in claim 6, wherein the fixing pin (3) is a 6mm diameter, for holding the thermoelectric cooling air duct system (18).
8. The system as claimed in claim 6, wherein the TEG device is configured with all four side of the boiler flue gas ducting system.
9. The system as claimed in claim 6, wherein the flue gas temperature is reduced due to extraction of heat by thermoelectric generator leading to improvement in collection efficiency of Electrostatic precipitator.