Title of Invention

AN EXHAUST GAS HEAT EXCHANGER TO GENERATE STEAM PARTICULARLY A THERMIC FLUID STEAM GENERATOR

Abstract

(1) An exhaust gas heat exchanger to generate steam, particularly, a thenmc fluid steam generator comprising an expansion tank (3),for recycled thermic fluid, mecffls for passing the thermic fluid through fluid circulation pump (5) to a primary thermic fluid heat exchanger (1), heated by liquid or solid fiiel, a secondary heat exchanger (2),in flow relationship with the thermic fluid heat exchanger (1), flie expansion tank, the thermic fluid heat exchanger and the secondary heat exchanger being in closed relationship, there being provided a feed water unit (4) for the secondary heat exchanger (2), the arrangement being such that the hot exhaust gas exdianges heat with the cold thermic fluid in the primary thennic fluid heat exchanger (l),and the hot fluid exiting the primary heat exchanger flows through the said secondary heat exchanger thereby exchanging heat th^eto and producing steam.

Full Text

THE PATENT ACT, 1970 COMPLETE SPECIFICATION (SECTION-10) Rules 13 TITLE AN EXHAUST GAS HEAT EXCHANGER TO GENERATE STEAM PARTICULARLY A THERMIC FLUID STEAM GENERATOR. APPLICANT THERMAX LIMITED, D-13, IVIIDC INDUSTRIAL AREA, CHINCHWAD, PUNE-411 019, MAHARASHTRA, INDIA, AN INDIAN COMPANY The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed. INTRODUCTION TO THE FIELD OF INVENTION: This invention relates to a new exhaust gas heat exchanger to generate steam and particularly to a thermic fluid steam generator (TSG). This invention more particularly relates to the development of a thermic fluid steam generator in which the water hold-up does not exceed 22.75 litres. PRIOR ART AND DRAWBACKS: It is already known in the prior art to generate steam, using heat in the thermic fluid and in these conventional thermic fluid steam generators (TSG), it is known to generate steam by exchange of heat from hot thermic fluid to the water/ steam with pool boiling as steam generating phenomena. In this process, the heat transfer coefficient ranges from 15 to 50 kcal/h.m^ C. Hence the water holdup invariably exceeds 22.75 litres. The main limitation of the prior art is that the water hold-up of the pressure part exceeds 22.75 litres bringing this unit under purview of Indian Boiler Regulations Act (IBR). The conventional prior art also suffers from higher capital cost of the thermic fluid steam generator. OBJECTS OF THE INVENTION: It is the principal object of this invention to propose a new design or improvement in the existing thermic fluid steam generator design (TSG). It is another object of this invention to propose this new design with nucleate boiling inside the tubes instead of pool boiling outside the tubes. It is yet another object of this invention to propose a new heat exchanger/ steam generator design in which the heat transfer co-efficient is in the range of 400 to 3000 kcal /m^ C and hence being able to maintain the water hold-up below 22.75 litres. Thus out of the purview of IBR. Further details of the Prior Art We are aware of the following prior art patents viz. (1) J.P. 7110197 dated 25.04.1995 (2) RU. 2168673 dated 10.06.2001 and (3) WO 9837314 dated 27.08.1998. We have studied all these prior art in detail and state as follows: (1) Japanese Patent 7110197- This is entirely for a different purpose and is not for recovering heat from a Thermic fluid. It is clear that steam is used as a heat source in the heat exchanger of the Japanese Patent. This is not a closed circuit simple loop connection and no cold Thermic fluid is not recovered as it is not used at all. Moreover, the steam is directly discharged from the heat exchanger through a set of pipeline heat exchangers. The hot water produced in the heat exchanger is split for different purposes. This patent has nothing to do with our invention. (2) Russian Patent No. RU 2168673 - This Patent is for the proposes of controlling scaling (deposit of salt) inside heating surfaces. For this purpose the feed water is first preheated by steam followed by the removal of the condensate and re-injecting part of the condensate with steam. There is nothing in common with our invention. (3) WO 9837314 - This is mainly for an installation with a gas steam turbine. The purpose of this Patent is entirely different in that it is meant for increasing the energetic efficiency of gas steam turbine. It has primarily a multistage gas steam turbine equipped with combustors, air compressor, combined heat exchanger and another set of water heaters economizers. This also includes water condensate purifying column from Carbon dioxide and Oxygen and other things. These are entirely different and are not meant for closed circuit Thermic fluids as in an invention. Our invention has no turbine and compressor and other unit of the W.O. Patent. We state that none of the above known prior art either alone or in any combination can destroy the novelty and inventive step of our invention. BRIEF STATEMENT OF THE INVENTION According to this invention, there is provided an exhaust gas heat exchanger to generate steam particularly a thermic fluid steam generator comprising an expansion tank for recycled thermic fluid, means for passing the thermic fluid through a thermic fluid circulation pump -to a primary thermic fluid heat exchanger heated by liquid or solid fuel, a secondary heat exchanger in flow relationship with the thermic fluid heater, the expansion tank, the thermic fluid heater and the secondary heat exchanger being in closed relationship, there being provided a feed water unit for the secondary heat exchanger, the arrangement being such that the hot exhaust gas exchanges heat with the cold thermic fluid in the primary thermic fluid heat exchanger, the hot fluid exiting the primary heat exchanger flows through said secondary heat exchanger, thereby exchanging heat thereto and the producing hot water or steam. The feed water unit is provided with a feed water pump and the feed water unit is a heat exchanger. There is also provided a method for the generation of steam from hot thermic fluid, comprising the steps of passing a cold thermic fluid in indirect heat exchange relationship with the hot liquid or gas to generate hot thermic fluid, passing the hot thermic fluid in indirect heat exchange relationship with water in a steam generator, recycling the heat depleted thermic fluid to a deaerator pr expansion tank, in a closed loop and generating steam in the steam generator. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the accompanying drawings in which figure 1 illustrates schematically the novel steam. DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS The normal known thermic fluid heater (1) fired with either hquid or solid fuel is capable of heating the thermic fluid to a specific temperature. The hot thermic fluid is circulated through a heat exchanger or boiler or steam generator (2) using thermic fluid circulation pump (5). The thermic fluid transfers heat to the feed water, which is pumped by feed pump (4) in to the heat exchanger or boiler (2), which thus generates steam. This relatively cooler thermic fluid is passes through the deaerator or expansion tank (3) to the thermic fluid circulation pump (5) in a closed loop. This heat exchanger (2) can be a single unit or several modular units connected in series or parallel. We have studied the new system and evaluated experimental results as explained below. Data have been generated for various thermic fluid inlet/outlet temperatures. The system has been optimized for higher heat transfer coefficient, limited water hold up. The general findings are tabulated in the table below: Conclusion: It will be seen from the tabulated results that the advantages of the novel system are many. 20- a. Heat transfer co-efficient is: 1500 kcal/hr m 0 b. Water hold up is: 22.75 litres. Other Advantages: Compact and less foot print. Out of the purview of Indian Boiler Regulations Act in single module for themiic fluid steam generator upto 1 TPH F&A 100° C capacity and in multiple modules for themnic fluid steam generator beyond 1 TPH F&A 100° C capacity. Lower capital cost. Lower operational cost. Provides accessibility for water side cleaning. 876/MUM/2001 WE CLAIM, (1) An exhaust gas heat exchanger to generate steam, particularly, a thenmc fluid steam generator comprising an expansion tank (3),for recycled thermic fluid, mecffls for passing the thermic fluid through fluid circulation pump (5) to a primary thermic fluid heat exchanger (1), heated by liquid or solid fiiel, a secondary heat exchanger (2),in flow relationship with the thermic fluid heat exchanger (1), flie expansion tank, the thermic fluid heat exchanger and the secondary heat exchanger being in closed relationship, there being provided a feed water unit (4) for the secondary heat exchanger (2), the arrangement being such that the hot exhaust gas exdianges heat with the cold thermic fluid in the primary thennic fluid heat exchanger (l),and the hot fluid exiting the primary heat exchanger flows through the said secondary heat exchanger thereby exchanging heat th^eto and producing steam. (2) An exhaust gas heat exchanger to generate steam, particularly, a thermic fluid steam generator as claimed in claim (1) wherein the feed water unit is provided with a feed water pump. (3) An exhaust gas heat exchanger to generate steam, particularly, a thennic fluid steam generator substantially as herein described with reference to the accompanying drawings.

Documents:

876-mum-2001-cancelled page(29-11-2004).pdf

876-mum-2001-claim(granted)-(29-11-2004).pdf

876-mum-2001-claims(granted)-(29-11-2004).doc

876-mum-2001-correspondence(14-3-2005).pdf

876-mum-2001-correspondence(ipo)-(20-2-2007).pdf

876-mum-2001-drawing(14-3-2005).pdf

876-mum-2001-form 1(12-9-2001).pdf

876-mum-2001-form 19(12-3-2004).pdf

876-mum-2001-form 2(granted)-(29-11-2004).doc

876-mum-2001-form 2(granted)-(29-11-2004).pdf

876-mum-2001-form 26(14-3-2005).pdf

876-mum-2001-form 3(12-9-2001).pdf

876-mum-2001-form 5(14-3-2005).pdf

876-mum-2001-genral power of attorney(29-11-2004).pdf

876-mum-2001-petition rule 137(14-3-2005).pdf

abstract1.jpg