DESC:The present application is an application for a patent of addition to the Indian Patent Application no. 201821045038, filed on 29/11/2018.
FIELD
Embodiments disclosed herein relate to a heat recovery system related generally to recovery of rejected heat from heat surplus units and used to transfer to active heat supplying 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 all the rejected heat.
DEFINITIONS
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.
Heat surplus unit: The term “ heat surplus unit” refers to a unit or equipment at high temperature in a heat recovery system and works as a heat source.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
In the production process of an automotive paint shop, LNG gas is used as a fuel source for heating in the paint and sealer baking oven, an air supply unit of the painting booth and a hot water generator. In prior art, the exhaust 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 drained, and the heat energy is not fully utilized, resulting in a lot of wastage of heat energy.
The method for waste heat recovery disclosed in the Indian patent application 201821045038 works perfectly well for low temperature waste heat recovery, when the heat surplus unit 104 is working between 30° C - 60° C. However, it is less efficient when the temperature of the heat surplus unit rises to 60°-100°C or to 110°-220°C. Therefore, alternative systems and methods will be required for the recovery of the waste heat from the heat surplus unit at medium and high temperature ranges.
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 medium and high 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 discloses a system for reusing heat of a process fluid received in a tank having heat recovery circuits configured to absorb heat of the process fluid. The system comprises a plurality of conduit loops with a conduit loop configured between each of the heat recovery units and the tank, and interconnecting the heat recovery units; a plurality of control valves, a control valve configured along each of the conduits and positioned upstream and downstream of each of the heat recovery units; a control unit coupled to the control valves; and a temperature sensor configured on the tank to sense the temperature of the process fluid, and connected to the control unit to communicate the sensed temperature. The control unit is configured to selectively actuate the control valves in response to the sensed temperature of the process fluid and circulate the process fluid between the tank and each of the heat recovery units.
In a preferred embodiment, a first conduit loop is defined by connection of the first control valve, the high temperature heat recovery circuit, the fourth control valve, the medium temperature heat recovery circuit, the fifth control valve, and the low temperature heat recovery circuit. The control unit is configured to enable circulation of the process fluid through the first conduit loop when temperature of the process fluid is in between the range of 110 degree to 220 degree Celsius. Similarly, a second conduit loop is defined by connection of the second control valve, the medium temperature heat recovery circuit, the fifth control valve and the low temperature heat recovery circuit. The control unit is configured to enable circulation of the process fluid through the second conduit loop when temperature of the process fluid is in the range of 60 degree to 110 degree Celsius. Similarly a third conduit loop is defined by connection of the third control valve, the low temperature heat recovery circuit. The control unit is configured to enable circulation of the process fluid through the third conduit loop when temperature of the process fluid is in the range of 30 degree to 60 degree Celsius.
In another embodiment, the control tank is configured with at least one hot fluid inlet and at least three hot fluid outlets.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The heat recovery system of the present 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 - Control tank
104 - High temperature heat recovery circuit
106 - Medium temperature heat recovery circuit
108 - Low temperature heat recovery circuit
110 - Temperature sensor
111 - Control unit
112a - First control valve
112b - Second control valve
112c - Third control valve
112d - Forth control valve
112e - Fifth control valve
114 - First conduit
116 - Second conduit
118 - Third conduit
120 - Fourth conduit
122 - Fifth conduit
124 - Sixth conduit

DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
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, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, 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.
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.
The method for waste heat recovery disclosed in the Indian patent application 201821045038 works perfectly well for low temperature waste heat recovery, when the heat surplus unit 102 is working between 30°-60°C. However, it is not so efficient when the temperature of the heat surplus unit rises to 60°-110°C or to 110°-220°C. The heat surplus unit is cooled down to 30°-60°C by rejecting heat in a cooling tower. Therefore, alternative systems and methods will be required for the recovery of the waste heat from the heat surplus unit.
The present disclosure envisages a system 100 for reusing heat of a process fluid received in a tank. The system 100 is an integrated cascade heat recovery system, which can be used for waste heat recovery over a wide range of temperature 30°C-220° C. The system 100 includes a tank 102 in which a process fluid at high temperature is handled. Such a process fluid is typically a byproduct of another process used in the plant. The tank 102 is configured with at least one inlet for incoming of the hot process fluid, so as to facilitate heat recovery from multiple process fluid sources. The tank 102 is also referred as a ‘heat surplus unit’. The system 100 further includes heat recovery circuits 104, 106, 108 configured to absorb heat of the process fluid contained in the tank 102. The tank 102 is configured with at least three outlets so as to divert the hot process fluid from the tank 102 to any of the heat recovery circuits as desired. The system 100 comprises conduit loops configured between each of the heat recovery circuits 104, 106, 108 and the tank 102. The conduit loops interconnect the heat recovery circuits 104, 106, 108. The system 100 further comprises control valves 112a, 112b, 112c, 112d, 112e configured along each of the conduit loops and are positioned upstream and downstream of each of the heat recovery circuits 104, 106, 108. A control unit 111 is provided on the tank 102 to be in communication with each of the control valves 112a, 112b, 112c, 112d, 112e. The control unit 111 is configured to selectively actuate each of the control valves 112a, 112b, 112c, 112d, 112e.
In an embodiment as shown in the figure 1, the high temperature heat recovery circuit 104 facilitates recovery of heat from the tank 102 which has a process fluid at a temperature in the range of 110°C to 220°C, a medium temperature heat recovery circuit 106 to facilitate recovery of heat of the process fluid contained in the tank 102 at a temperature in the range of 60°C to 110°C, a low temperature heat recovery circuit 106 to facilitate recovery of heat of the process fluid contained in the tank 102 at a temperature in the range of 30° C to 60° C.
The hot fluid outlet from the control tank 102 of the low temperature heat recovery circuit 108 is connected to the inlet of the control tank 102. The control tank 102 comprises a temperature sensor that senses the temperature of the water in the control tank 102. The temperature sensor is connected to a control unit 111. The control unit 111 receives signals from the temperature sensor 110 and controls the opening and closing of the control valves 112a, 112b, 112c, 112d, 112e.
In an operative configuration, when the temperature of the fluid in the control tank 102 is in the range from 110°C to 220°C, then the heat recovery system 100 is configured to operate in a way that the first control valve 112a, the fourth control valve 112d, the fifth control valve 112e are opened, while the second control valve 112b and the third control valve 112c are closed. The hot fluid from the control tank 102 is transferred to the high temperature heat recovery circuit 104 via a first conduit 114 for heat recovery. The fluid in the temperature range from 60°C to 110°C emanating from the high temperature heat recovery circuit 104 is transferred to the medium temperature heat recovery circuit 106 via a fourth conduit 120. The fluid in the temperature range from 30°C to 60°C, emanating from the medium temperature heat recovery circuit 106 is transferred to the low temperature heat recovery circuit 108 via a fifth conduit 122. Finally, the fluid flows from the low temperature heat recovery circuit 108 to the control tank 102 via a sixth conduit 124. The path traversed by the fluid as explained thus defines the first conduit loop.
In another operative configuration, when the temperature of the fluid in the tank 102 is in the range from 60°C to 110°C, then the system 100 is configured to operate in a way that the second control valve 112b and the fifth control valve 112e are opened, while the first control valve 112a, the fourth control valve 112d and the third control valve 112c are configured to be closed. The hot fluid from the control tank 102 is transferred to the medium temperature heat recovery circuit 106 via a second conduit 116 for heat recovery. The fluid in the temperature range from 30°C to 60°C, emanating from the medium temperature heat recovery circuit 106 is transferred to the low temperature heat recovery circuit 108 via the fifth conduit 122. Finally, the fluid flows from the low temperature heat recovery circuit 108 to the control tank 102 via the sixth conduit 124. The path traversed by the fluid as explained thus defines the second conduit loop.
In yet another operative configuration, when the temperature of the fluid in the control tank 102 is in the range from 30°C to 60°C, then the heat recovery system 100 operates in such a way that the third control valve 112c is opened, while the first control valve 112a, the second control valve 112b, the fourth control valve 112d and the fifth control valve 112e are closed. The hot fluid from the control tank 102 is transferred to low temperature heat recovery circuit 108 via a third conduit 118 for heat recovery. Finally, the fluid flows from the low temperature heat recovery circuit 108 to the control tank 102 via the sixth conduit 124. The path traversed by the fluid as explained thus defines the third conduit loop.
Typically, the high temperature heat recovery circuit 104, the medium temperature heat recovery circuit 106 and the low temperature heat recovery circuit 108 are plate type heat exchangers.
The system 100 and the method described herein can solve several issues related to the existing heat recovery system and improves the operation of the system. Firstly, re-use of the rejected heat from various heat sources in the paint shop of the automobile industry is facilitated. Secondly, use of a cooling tower and a heat pump is eliminated in the heat recovery system. The heat recovery system requires less capital expenditure, less time for implementation, and high internal rate of returns. Additionally, running of active air supply unit burners is minimized, LNG consumption is reduced and lastly, heat recovery is maximized.
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 sources in a paint shop of the automobile industry;
• Less running of active heat supplying unit burners;
• Reduced LNG consumption;
• Less use of a heat pump; and
• Elimination of a cooling tower.
The foregoing disclosure has been described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
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 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.
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.
,CLAIMS:WE CLAIM:
1. A system (100) for reusing heat of a process fluid received in a tank (102), said system (100) having heat recovery circuits (104, 106, 108), conduit loops and control valves (112a, 112b, 112c, 112d, 112e) configured to absorb heat of said process fluid:
characterized in that, said system (100) comprises a temperature sensor (110) mounted within said tank (102) and a control unit (111), said control unit (111) configured to receive temperature signals from said temperature sensor (110) and further configured to selectively actuate said control valves (112a, 112b, 112c, 112d, 112e) for circulating said process fluid through said conduit loops connecting said heat recovery circuits (104, 106, 108).
2. The system (100) as claimed in claim 1, wherein a conduit loop is configured between each of said heat recovery units (104, 106, 108) and said tank (102), and interconnecting said heat recovery units (104, 106, 108).
3. The system (100) as claimed in claim 1, wherein a control valve (112a, 112b, 112c, 112d, 112e) is configured along each of said conduit loops and positioned upstream and downstream of each of said heat recovery units (104, 106, 108).
4. The system (100) as claimed in claim 1, wherein a first conduit loop is defined by connection of the first control valve (112a), the high temperature heat recovery circuit (104), the fourth control valve (112d), the medium temperature heat recovery circuit (106), the fifth control valve (112e), and the low temperature heat recovery circuit (108), said control unit (111) configured to enable circulation of the process fluid through said first conduit loop when temperature of said process fluid is in between the range of 110 degree to 220 degree Celsius.
5. The system (100) as claimed in claim 1, wherein a second conduit loop is defined by connection of the second control valve (112b), the medium temperature heat recovery circuit (106), the fifth control valve (112e) and the low temperature heat recovery circuit (108), said control unit (111) configured to enable circulation of the process fluid configured through said second conduit loop when temperature of said process fluid is in the range of 60 degree to 110 degree Celsius.
6. The system (100) as claimed in claim 1, wherein a third conduit loop is defined by connection of the third control valve (112c), the low temperature heat recovery circuit (108), said control unit (111) configured to enable circulation of the process fluid through said third conduit loop when temperature of said process fluid is in the range of 30 degree to 60 degree Celsius.
7. The system (100) as claimed in claim 1, wherein said tank (102) is configured with at least one hot fluid inlet and at least three hot fluid outlets.
8. The system (100) as claimed in claim 1, wherein said temperature sensor (110) and said control unit (111) are configured on said tank (102).
9. The system (100) as claimed in claim 1, wherein the high temperature heat recovery circuit (104), the medium temperature heat recovery circuit (106) and the low temperature heat recovery circuit (108) are heat exchangers.