Claims:WE CLAIM:
1. A heat recovery system (100) for recovery of waste heat from low temperature industrial fluids, the system (100) comprising:
i) a first heat surplus unit (102);
ii) a first heat exchanger (108);
iii) a first conduit (112) to allow flow of a first fluid at a temperature in the range of 30° C to 40° C from the first heat surplus unit (102) to an inlet (a) of the first heat exchanger (108);
iv) a second heat surplus unit (104);
v) a second heat exchanger (110);
vi) a second conduit (114) to allow flow of a second fluid at a temperature in the range of 30° C to 60° C from the second heat surplus unit (104) to an inlet (e) of the second heat exchanger (110);
vii) a heat converting unit comprising either one of an active heat receiving unit (106a) or a cooling tower (106b);
viii) a third conduit (116) to allow the flow of a third fluid from the output of the active heat receiving unit (106a) to an inlet (b) of the first heat exchanger (108);
ix) a fourth conduit (118) connecting the outlet (c) of the first heat exchanger (108) to an inlet (f) of the second heat exchanger (110);
x) a fifth conduit (120) for connecting the outlet (d) of the first heat exchanger (108) to the first heat surplus unit (102);
xi) a sixth conduit (122) for connecting the outlet (h) of the second heat exchanger (110) to the second heat surplus unit (104);
xii) a seventh conduit (124) for connecting the outlet (g) of the second heat exchanger (110) to the active heat receiving unit (106a);
xiii) an eighth conduit (126) for connecting the cooling tower (106b) to the inlet (f) of the second heat exchanger (110);
xiv) a ninth conduit (128) for connecting the outlet (g) of the second heat exchanger (110) to the cooling tower (106b);
xv) a tenth conduit for circulating the fourth fluid in the active heat receiving unit;

the system (100) configured in:
? a first arrangement in which the first heat surplus unit (102), the first heat exchanger (108), the second heat surplus unit (104), the second heat exchanger (110) and the active heat receiving unit (106a) are connected in a circuit to heat relatively cool fluid emanating from the active heat receiving unit (106a) in the first and second heat exchanger by heat exchange from first and second heat surplus unit, and resupply the third fluid from second heat exchanger to the active heat receiving unit (106a) for supplying heat to the third fluid in need of heat therein;
? a second arrangement in which the first heat surplus unit (102), the first heat exchanger (108), the second heat surplus unit (104), the second heat exchanger (110), the active heat receiving unit (106a) and the cooling tower (106b) are in circuit for cooling the second fluid emanating from the second heat surplus unit (104) below 40°C; and
Unit control means provided to switch the heat recovery circuit between the first and second arrangement.
2. The heat recovery system (100) as claimed in claim 1, further comprises a first taped point (T1) formed at the junction of the fourth conduit (118) and eighth conduit (126), and a second taped point (T2) formed at the junction of the seventh conduit (124) and ninth conduit (128).
3. The heat recovery system (100) as claimed in claim 1, wherein the third fluid flowing through the fourth conduit (118) emanating from the first heat exchanger (108) is at a temperature relatively lower than the temperature of the second fluid flowing through the second conduit (114).
4. The heat recovery system (100) as claimed in claim 1, wherein a plurality of control valves are provided for controlling the fluid flow, a first control valve (136) is disposed on the fourth conduit (118), and a second control valve (138) is disposed on the seventh conduit (124), a third control valve (140) is disposed on the eighth conduit (126) coming from cooling tower (106b), and a fourth control valve (142) is disposed on the ninth conduit (128).
5. The heat recovery system (100) as claimed in claim 1, further comprising a first pump (130) on the third conduit (116), a second pump (132) on eighth conduit (126), and a third pump (134) on the ninth conduit (128).
6. The heat recovery system (100) as claimed in claim 1, wherein the first and second heat surplus units can be selected from a pre-treatment rinse tank.
7. The heat recovery system (100) as claimed in claim 1, wherein the active heat receiving unit (106a) can be selected from an air supply unit.
8. A method for heat recovery with the heat recovery system (100) as claimed in claim 1, the method comprising the following steps:
i) operating the active heat receiving unit (106a) such that the first heat surplus unit (102) and first heat exchanger (108) of the heat recovery system (100) such that the active heat receiving unit (106a) has a heat exchange relationship with the first heat surplus unit (102), wherein the third fluid emanating from the active heat receiving unit (106a) is recovering heat which is rejected by the first fluid emanating from the first heat surplus unit (102);
ii) operating the active heat receiving unit (106a) such that the second heat surplus unit (104) and second heat exchanger (110) of the heat recovery system (100) such that the active heat receiving unit (106a) has a heat exchange relationship with the second heat surplus unit (104), wherein the third fluid flowing through the fourth conduit recovering heat which is rejected by the second fluid emanating from the second heat surplus unit (104); and
iii) operating the heat recovery system (100) such that the first heat surplus unit (102) transfer heat to the third fluid flowing through the third conduit (116) by way of first heat exchanger (108), and then the second heat surplus unit (104) transfer heat to third fluid flowing through the fourth conduit (118) by way of second heat exchanger (110), and then the third fluid flowing through the seventh conduit (124) return to the active heat receiving unit (106a) to transfer the extracted heat to the fourth fluid flowing through the tenth conduit (144).
9. The method for heat recovery as claimed in claim 8, wherein the heat recovery system (100) is operated in first arrangement by keeping the third and fourth control valves (142) (140) closed, and keeping the first and second control valves (136) (138) open when the temperature of the second fluid flowing through the second conduit (114) is below 40°C.
10. The method for heat recovery as claimed in claim 8 further comprises operating the heat recovery system (100) in second arrangement by keeping the first, second, third and fourth control valves open when the temperature of the second fluid flowing through second conduit (114) is above 40°C.
11. The method for heat recovery as claimed in claim 10, wherein the cooling tower (106b) and the active heat receiving unit (106a) work in combination as a heat converting unit (106) to cool down the second fluid flowing through the second conduit (114) to a temperature below 40°C.
, Description:FIELD
Embodiments disclosed herein a heat recovery system related generally to recovery of rejected heat from heat surplus units and used to transfer to active heat receiving unit. In particular, a method, system, and apparatuses are disclosed that employ for instance a connection from a heating unit to a cooling unit, depending on system conditions to recover the rejected heat.
DEFINITION
As used in the present disclosure, the following term is generally intended to have the meaning as set forth below, except to the extent that the context in which it is used indicates otherwise.
First heat surplus unit: The term “first heat surplus unit” refers to a unit or equipment at high temperature in a heat recovery system and works as a heat source.
Second heat surplus unit: The term “Second heat surplus unit” refers to a unit or equipment at a temperature higher than the temperature of first heat surplus unit in a heat recovery system and works as a heat source.
Active heat receiving unit: The term “active heat receiving unit” refers to a unit or equipment in a heat recovery system that receives the heat in the heat recovery system and supply the recovered heat to a fluid in need thereof.
BACKGROUND
With the auto industry, people have become increasingly demanding quality car. In order to adapt to the development of the automobile era and consumer demand, car manufacturers around the world are constantly innovate, not only to improve the effectiveness and quality of auto parts, but also for the production of automotive components of some of the tooling and production lines are also engaged in various kinds of improvements to increase the productivity and reduce costs.
In the production process of automotive paint shop, LNG gas is used as a fuel source for heating purpose in paint and sealer baking oven, air supply unit of painting booth, and hot water generator. In prior art, the exhaust or effluents of high heat content from heat surplus units like electro-deposit oven, top coat oven, sealer oven, hot water generation unit and pre-treatment rinse line are vented out to atmosphere, and the heat energy is not fully utilized, resulting in a lot of waste.
The traditionally known heat recovery system for recovering the rejected heat in industries utilizes a heat circuit comprising evaporators, condensers, or heat pump. Such heat recovery system requires high capital expenditure and high implementation time which leads to lower internal rate of returns.
Therefore, there is felt a need for a heat recovery system that mitigates the hereinabove mentioned drawbacks.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a heat recovery system.
Another object of the present disclosure is to provide a method for heat recovery.
Still another object of the present disclosure is to provide a heat recovery system with low capital expenditure requirement.
Still another object of the present disclosure is to provide a heat recovery system to recover low temperature heat.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure provides a heat recovery system to recover heat rejected by the heat surplus units and transfer it to an active heat receiving unit. The heat recovery system forms a heat recovery circuit comprising heat exchangers connecting heat surplus units to the heat receiving unit in a cascading manner. The heat recovery circuit transfer heat from the first heat surplus unit and the second heat surplus unit to active heat receiving unit by way of first heat exchanger and second heat exchanger having fluid communication with first heat surplus unit and active heat receiving unit. The heat recovery system also comprises a cooling tower. The cooling tower is in fluid communication with the first heat exchanger and works as a heat sink for the second heat surplus unit when the heat recovery circuit is open.
The present disclosure further provides a heat recovery method. The heat recovery is carried out by operating the active heat receiving unit, first heat surplus unit and first heat exchanger of the heat recovery system such that the active heat receiving unit has a heat exchange relationship with the first heat surplus unit, wherein the active heat receiving unit extracts heat which is rejected by the first heat surplus unit. The active heat receiving unit has a heat exchange relationship with the second heat surplus unit, wherein the active heat receiving unit extracts heat which is rejected by the second heat surplus unit. The first heat surplus unit transfer heat to the active heat receiving unit fluid stream by way of first heat exchanger, and then the second heat surplus unit transfer heat to the active heat receiving unit fluid stream by way of second heat exchanger. The cooling tower works as a heat sink for the second heat surplus unit when the temperature of the output stream from second heat surplus unit exceeds 40°C.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates a schematic representation of a system for heat recovery in accordance with the present disclosure.

LIST OF REFERENCE NUMERALS
100 - Heat recovery system
102 - First heat surplus unit
104 - Second heat surplus unit
106 - Heat converting unit
106 a Active heat receiving unit
106 b Cooling tower
108 - First heat exchanger
a First heat exchanger hot stream inlet
b First heat exchanger cold stream inlet
c First heat exchanger cold stream outlet
d First heat exchanger hot stream outlet
110 - Second heat exchanger
e Second heat exchanger hot stream inlet
f Second heat exchanger cold stream inlet
g Second heat exchanger cold stream outlet
h Second heat exchanger hot stream outlet
112 - First conduit connecting the first heat surplus unit to inlet (a) of the first heat exchanger
114 - Second conduit connecting the second heat surplus unit to inlet (e) of the second heat exchanger
116 - Third conduit connecting the active heat receiving unit to inlet (b) of the first heat exchanger
118 - Fourth conduit connecting outlet (d) of the first heat exchanger to inlet (f) of the second heat exchanger
120 - Fifth conduit connecting outlet (s) of the first heat exchanger to the first heat surplus unit
122 - Sixth conduit connecting outlet (h) of the second heat exchanger to the second heat surplus unit
124 - Seventh conduit connecting outlet (g) of the second heat exchanger to the active heat receiving unit
126 - Eighth conduit connecting the cooling tower to outlet (f) of the second heat exchanger
128 - Ninth conduit connecting inlet (g) of the second heat exchanger to the cooling tower
130 - First pump on third conduit
132 - Second pump on first conduit
134 - Third pump on second conduit
136 - First control valve on fourth conduit
138 - Second control valve on seventh conduit
140 - Third control valve on eighth conduit
142 - Fourth control valve on ninth conduit
144 - Tenth conduit for circulating the fourth fluid in the active heat receiving unit
DETAILED DESCRIPTION
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
When an element is referred to as being "mounted on," “engaged to,” "connected to," or "coupled to" another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Terms such as “inner,” “outer,” "beneath," "below," "lower," "above," "upper," and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.
In the production process of automotive paint shop, LNG gas is used as a fuel source for heating purpose in paint and sealer baking oven, air supply unit of painting booth, and hot water generator. In prior art, the exhaust or effluents of high heat content from heat surplus units like electro-deposit oven, top coat oven, sealer oven, hot water generation unit and pre-treatment rinse line are vented out to atmosphere, and the heat energy is not fully utilized, resulting in a lot of waste.
The traditionally known heat recovery system for recovering the rejected heat in industries utilizes a heat circuit comprising evaporators, condensers, or heat pump. Such heat recovery system requires high capital expenditure and high implementation time which leads to lower internal rate of returns.
The disclosure will now be described with reference to the accompanying drawing which will not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The present disclosure envisages a cascade heat recovery system, particularly suitable for recovery of waste heat from low temperature industrial fluids. The heat recovery system (100) as illustrated in the figure 1 of the accompanying drawing, uses a first heat exchanger (108) and second heat exchanger (110) to extract low temperature heat from a first heat surplus unit (102) and second heat surplus unit (104), and transfer the extracted heat to a heat converting unit (106) comprising an active heat receiving unit (106a) and cooling tower (106b).
The heat recovery system (100) of the present disclosure has the appropriate piping to the components in the system. A first conduit (112) is provided to allow the flow of a first fluid at a temperature in the range of 30° C to 40°C from the first heat surplus unit (102) to the inlet (a) of the first heat exchanger (108). A second conduit (114) is provided to allow the flow of a second fluid at a temperature in the range of 40°C to 45°C from the second heat surplus unit (104) to the inlet (e) of the second heat exchanger (110). A third conduit (116) is provided for connecting the output of the active heat receiving unit (106a) to the inlet (b) of the first heat exchanger (108). A fourth conduit (118) is provided for connecting the outlet (c) of first heat exchanger (108) to the inlet (f) of second heat exchanger (110). The third fluid flowing through the fourth conduit (118) is at a temperature relatively lower than the temperature of the second fluid flowing through the second conduit (114). A fifth conduit (120) is provided for connecting the outlet (d) of first heat exchanger (108) to the first heat surplus unit (102). A sixth conduit (122) for connecting the outlet (h) of second heat exchanger (110) to the second heat surplus unit (104). A seventh conduit (124) is provided for connecting the outlet (g) of second heat exchanger (110) to the active heat receiving unit (106a). An eighth conduit (126) is provided for connecting the cooling tower (106b) to the inlet (f) of second heat exchanger (110). A ninth conduit (128) is provided for connecting the outlet (g) of second heat exchanger (110) to the cooling tower (106b). A tenth conduit (144) is provided for circulating the fourth fluid in the active heat receiving unit. A first taped point (T1) formed at the junction of the fourth conduit (118) and eighth conduit (126), and a second taped point (T2) formed at the junction of the seventh conduit (124) and ninth conduit (128).
The system is provided with a unit controller (not shown in the figure), that includes a processor, a memory , and an input/output (I/O) interface that may be required and/or suitable to control operation of the control valves, pumps and equipments, such as shown in figure 1. A first control valve (136) is disposed on the fourth conduit (118). A second control valve (138) is disposed on the seventh conduit (124). A third control valve (140) is disposed on the eighth conduit (126) coming from cooling tower (106b). A fourth control valve (142) is disposed on the ninth conduit (128). The heat recovery system (100) further comprising a first pump (130) on the third conduit (116), a second pump (132) on eighth conduit (126), and a third pump (134) on the ninth conduit (128).
In one embodiment the heat recovery system is configured in a first arrangement in which the first heat surplus unit (102), the first heat exchanger (108), the second heat surplus unit (104), the second heat exchanger (110) and the active heat receiving unit (106) are connected in a circuit to heat the third fluid emanating from the active heat receiving unit (106a) in the first and second heat exchanger by heat exchange from first and second heat surplus unit, and resupply the third fluid from second heat exchanger to the active heat receiving unit (106a) for supplying heat to a fourth fluid flowing through tenth conduit (144) therein. The heat recovery system (100) is operated in first arrangement by keeping the third and fourth control valves (142) (140) closed, and keeping the first and second control valves (136) (138) open when the temperature of the fluids flowing through second conduit (114) is below 40°C.
In another embodiment, the heat recovery system is configured in a second arrangement in which the first heat surplus unit (102), the first heat exchanger (108), the second heat surplus unit (104), the second heat exchanger (110), the active heat receiving unit, and the cooling tower (106b) are in circuit for cooling the third fluid emanating from the second heat surplus unit (104). The heat recovery system is configured to work in second arrangement by keeping the first, second, third and fourth control valves open when the temperature of the fluids flowing through second conduit (114) is above 40°C. The active heat receiving (106a) work in combination as a heat converting unit (106) to cool down the fluids flowing through second conduit (114) to a temperature below 40°C.
The unit control means are provided to switch the heat recovery circuit between the first and second arrangement.
In different embodiments, the first and second heat surplus units can be selected from from air supply unit heat requirement of automobile industries.
The present disclosure in another aspect provides a method for recovering heat using the heat recovery system (100). The method comprises operating the active heat receiving unit (106a), first heat surplus unit (102) and first heat exchanger (108) of the heat recovery system (100) such that the active heat receiving unit (106a) has a heat exchange relationship with the first heat surplus unit (102), wherein the third fluid emanating from the active heat receiving unit (106a) is recovering heat which is rejected by the first heat surplus unit (102). The method further comprises operating the active heat receiving unit (106a), second heat surplus unit (104) and second heat exchanger (110) of the heat recovery system (100) such that the active heat receiving unit (106a) has a heat exchange relationship with the second heat surplus unit (104), wherein the third fluid flowing through the fourth conduit recovering heat which is rejected by the second heat surplus unit (104). The third fluid flowing through the seventh conduit (124) return to the active heat receiving unit (106).
In one embodiment, the heat recovery system (100) is operated in first arrangement by keeping the third and fourth control valves (142) (140) closed, and keeping the first and second control valves (136) (138) open when the temperature of the second fluid flowing through second conduit (114) is below 40°C.
In another embodiment, the heat recovery system (100) is operated in second arrangement by keeping the first, second, third and fourth control valves open when the temperature of the second fluid flowing through second conduit (114) is above 40°C, wherein the cooling tower (106b) and the active heat receiving (106a) work in combination as a heat converting unit (106) to cool down the second fluid flowing through second conduit (114) to a temperature below 40°C.
The system (100) and method described herein can solve several issues related to the existing system and improves the system operation. First, re-use of the rejected heat from various heat source in paint shop of automobile industry.
Second, no use of heat pump in the heat recovery system, and thus the heat recovery system requires less capital expenditure, less time for implementation, and high internal rate of returns.
Third, less running of active Air Supply Unit burners.
Fourth, reduced LNG consumption.
Fifth, stoppage of cooling tower.
The present disclosure is further described in light of the following example which is set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure.
Example 1:
The heat of the pretreatment line is rejected in air supply unit humidifier tank of paint shop for heat recovery in an automobile industry.
The rinse tank 3 of pretreatment line at 36° C works as the first heat surplus unit (102) and the rinse tank 1 pretreatment line at 45° C works as the second heat surplus unit (104). The air supply unit at 21° C works as active heat receiving unit (106a). The rinse tank 3 of pretreatment line is cascaded with the rinse tank 1 pretreatment line.
The first and second heat exchangers are in thermal communication with the rinse tank 1 and 3 of the pretreatment line to extract the heat from the fluid streams of the rinse tanks. The first and second heat exchangers transfer the extracted heat to the fluid stream of air supply unit thereby raising the temperature of the fluid stream from 21° C to 32° C.
A cooling tower is also provided to maintain the temperature of the pretreatment rinse 1 tank below 40° C.
The heat recovery configuration of present disclosure accounts for 427500 Kcal per hour heat recovery with rinse tank 1 of pretreatment line and 563 kg/day saving of LNG which is equivalent to Rs. 25.33 lakhs, when used during the winter season for the time span of 100 days.
It can be concluded from the foregoing that the system and method of the present disclosure reduces LNG consumption.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a heat recovery system and method. The technical advantages are as stated below:
• Re-use of the rejected heat from various heat source in paint shop of automobile industry.
• No use of heat pump in the heat recovery system, and thus the heat recovery system requires less capital expenditure, less time for implementation, and high internal rate of returns.
• Less running of active air supply unit burners.
• Reduced LNG consumption.
• Stoppage of cooling tower.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure, as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure 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 disclosure and not as a limitation.