FORM 2
THE PATENTS ACT 1970
(39 f 1970)
&
The Patent Rules, 2003
Complete Specification
(See section 10 and rule 13)
A System To Recover And Use Heat From Condensers
Mahindra and Mahindra Ltd.
An Indian company registered under the Indian Companies Act, 1956. Mahindra Towers, R.K. Kurne Chowk, Worli, Mumbai - 400 018, Maharashtra, India
The following specification particularly describes the invention and the manner in which it is to be performed.

A System To Recover And Use Heat From Condensers
Field of Invention:
Present invention relates to recovering heat from the condenser(s) of chiller(s) used in the industrial cooling plants and using it to heat up any other processes in the plants. In particular the present invention is applied in the paint shops used in industrial units such as those used for manufacture of automotives, white goods, other household or industrial appliances that require painting, or indeed ceramic industry.
Background of Invention:
As a part of the painting process, the painted articles are baked and then cooled down. The liquid paint itself is heated and cooled down during the process. Liquid chemicals are heated & paints are cooled during the process. Paint shops conventionally use electrically operated chillers to cool the paints used in painting operations in manufacturing plants. Typical chillers run on vapor compression principle. These chillers perform the function of chilling through its evaporators whereupon heat is rejected to the atmosphere at the condenser end of a chiller via a cooling tower. The amount of heat rejected to the atmosphere through this process is not insignificant, for example a 100 ton chiller rejects heat to the order of 300k Kcal/hr.

On the other hand, the pretreatment processes in a typical paint shop associated with manufacturing require heating at the pretreatment process stage. This is conventionally achieved through a hot water generator, which is energized by liquefied petroleum gas (LPG), High Speed Diesel (HSD), or even by electricity. This incurs a huge cost & adds to CO2 emissions.
As there are already operations involving heat rejection taking place in the paint shop, it makes all the sense to recover the heat and use it elsewhere. Although there have been systems in use where such heat recovery is made possible, these systems are not suggested for large operations such as the paint shop units of manufacturing plants. There is therefore a need to provide systems to recover heat from various sources of waste of heat energy in a paint shop and reuse it in processes that need heating thereby the cost of manufacturing and damage to the environmental, especially in the large manufacturing facilities.
Currently there are some systems where heat recovery from chillers is attempted. Mcaquay chillers (www.mcquay.com) talk about heat recovery from the condensers in the form of templifiers. A templifier is a heat pump, however, the system proposed by Mcquay doesn't use a heat pump that runs on the vapor absorption principle. The templifier can generate up to 160Deg F i.e. 71 Deg C temperature. However, several industrial processes require greater temperatures, ie, 90 Deg C water. Moreover, the templifiers, while expected to reduce impact on heating system & is mentioned to be used for domestic purposes.

In another systems such as the one proposed on, (www.intel.com/it/pdf/Data-Center-Heat-Recoverv.pdf) heat is recovered from condenser through heat exchangers & produces hot water of 104 Deg F i.e. 40 Deg C & is used for office warming or preheat water for kitchens. Once again these systems are unsuitable for industrial uses.
In yet another type of heat recovery systems, such as the dedicated heat recovery chiller (DHRC) proposed on www.multistack.com, the water from condenser at 54 Deg C is used as preheated water for the boiler used for space heating. Once again, there's no suggestion of teaching of how these systems may be of use in the industrial environments.
None of the above described systems are suitable for use in industrial paint shops. There is therefore a need to recover heat from the paint-cooling operations undertaken in the industrial paint shops and using the recovered heat in the paint shop pretreatment processes.
Objects of the invention:
Accordingly the one of the objects of the present invention is to recover the rejected heat from the chiller condenser.

Another object of the present invention is to use the recovered heat towards the industrial processes.
Yet another object of the invention is to provide a source of heating in the form of heat recovered from the chiller condenser which would reduce the operational costs and the adverse environmental impact.
Summary of the invention:
A system is proposed that would harness heat otherwise rejected to the atmosphere from industrial processes involving chiller condensers and recycle it back into another industrial processes. The system uses a number different types of equipment such as a heat pump and heat exchangers an also an hot water generator in a inventive combination to recover the heat from the condensers of the chillers that are used for cooling of paints or any other systems of an industrial process and provide the recovered heat to pretreatment operations that typically take place at the upstream end of said industrial processes. The heat pump used for recovering from the chiller condenser preferably works on 'vapor absorption' principle and the heat exchangers used to transfer the recovered heat preferably work on a liquid to liquid heat transfer principle.

List of Figures:
Figure 1 shows the conventional paint cooing using electrically operated Chiller working on vapor compression principle.
Figure 2 shows the conventional way of heating up the pretreatment process tanks using a hot water generator (HWG).
Figure 3 shows an embodiment of the present invention incorporating chillers, a heat pump, and a hot water generator.
Figure 3A shows an embodiment incorporating heat exchangers at the chiller end of the system, chillers, a heat pump, and a hot water generator.
Figure 3B shows an embodiment incorporating chillers, a heat pump, a hot water generator, and heat exchangers at the pretreatment end of the system.

Figure 3C shows yet another embodiment incorporating heat exchanger at chiller end, chillers, a heat pump, a hot water generator, and heat exchangers at the prerreatment end of the system.
List of parts:
System of heat exchange (1) Sixth Loop (5E)
Paint tanks (2) Seventh loop (5F)
Chiller (2A), Cooling tower (2AA), First main collector pipe (6)
Heat exchanger (2AB)
Second main collector pipe (6A)
Heat pump (2B)
Third main collector pipe (6B)
First heat exchanger (4)
Fourth main collector pipe (6C)
Second heat exchanger (4A)
Fifth main collector pipe (6D)
First loop (5)
Sixth main collector pipe (6E)
Second loop (5A)
Seventh main collector pipe (6F)
Third loop (5B)
First secondary collector pipe (7)
Fourth loop (5C)
Second secondary collector pipe (7A)
Fifth loop (5D)
Third secondary collector pipe (7B)

Fourth secondary collector pipe (7C) Seventh main return pipe (8F)
Fifth secondary collector pipe (7D) First secondary return pipe (9)
Sixth secondary collector pipe (7E) Second secondary return pipe (9A)
Seventh secondary collector pipe (7F) Third secondary return pipe (9B)
First main return pipe (8) Fourth secondary return pipe (9C)
Second main return pipe (8A) Fifth secondary return pipe (9D)
Third main return pipe (8B) Sixth secondary return pipe (9E)
Fourth main return pipe (8C) Seventh secondary return pipe (9F)
Fifth main return pipe (8D) Pretreatment tank (10)
Sixth main return pipe (8E) Hot water generator (11)
Detailed description of the invention:
In order to understand the present invention it is necessary to look at how the conventional cooling towers work. The conventional process of using a cooling tower (2AA) to reject the heat from the condenser unit of the chiller (2A) into the atmosphere is shown in Figure 1. The cooling water circuit of the chiller (2A) passes through the condenser of the chiller, which is necessarily an shell & tube type heat exchanger & gets heated up to 37°C after extracting heat from the

refrigerant in the chiller. This water is passed to the cooling tower, where by virtue of evaporative cooling the water is cooled till 32 °C. Thus the cooling of the water in the cooling circuit is achieved by rejecting the heat in to the atmosphere. The water cooled in the cooling tower is pumped back to the chiller condenser, thus making it a loop (an open loop in this case as the water is exposed to atmosphere). Also seen in the figure 1 is another loop of water (a closed loop in this case) passing through the evaporator of the chiller. This Chilling water loop gets cooled till 7°C & in turn cools paint or any other liquid that needs cooling through heat exchanger. This water comes back to the evaporator at 12°C thus completing the closed loop.
Figure 2 shows conventional processes requiring heating at temperatures above those of the heat recovered from industrial processes typically use hot water generated through a hot water generator (11) and a heat exchanger (2AB) that provides the heat to the process or the application that requires it, A typical conventional system used for this purpose is shown in Figure 2. It shows a hot water generator (HWG) which is used to heat up the pretreatment process tanks (10). The hot water generators are typically fired with LPG but HSD or electric energy source is also known to be used.

In the conventional industrial processes, the two systems, namely the chiller system used for cooling and the pretreatment process tanks (10) heated with the help of HWG are operated independently of each other.
In any conventional industrial paint processes, paint needs cooling, as in the course of painting process it gets heated, and some other chemicals need heating as pretreatment process. Chillers and hot water generators along with heat exchangers are already in use. However, as discussed above, the two systems operate independently and there's a lot of wastage of heat from the cooling towers. The present invention provides a system which introduces a heat pump to recover heat from the condensers of the chillers and distributes it to the pretreatment tanks.
Figure 3 describes an embodiment of the present invention. Here heat is recovered from the paint tanks (2) (or tanks containing any other liquid that needs cooling, for example, that used in electro-deposition process) and provided to pretreatment process tanks (10) through a system of chillers (2 A), a heat pump (2B), and a hot water generator (11). The recovered heat may be provided to any other unit or process that requires it. A number of chillers (2A) are provided which are typically used for cooling of the paint systems or any other systems in industrial processes used in manufacturing industry. The cooling is done through the

chilling water loop. The heat pump (2B) is provided in the cooling water loop of the chiller (2A). Thus here the cooling water loop is also a closed loop. Since the temperature of the fluid heated with the heat recovered through the paint cooling process, by the time it leaves the condenser unit of a chiller, is of the order of 42 °C, the heat pump (2B) (along with the second heat exchanger) brings its temperature to that required in the pretreatment processes, which may be of the order of 55 to 60 °C or even higher depending on the process and the chemicals used in them. Additional heat, typically required at the start-up stage of the pretreatment process, is provided through hot water generated using a hot water generator.
As seen from Figure 3, a first loop (5) circulates the paint that needs cooling down through the evaporator of the chiller using a network of first secondary collector pipes (7) and first secondary return pipes (9). Where there are a number of paint tanks (2) and chillers (2A) a first main collector pipe (6) and a first main return pipe (8) are used into which the respective secondary return pipes (7 and 9) are connected. The first loop (5) is an open loop.
A second loop (5 A) circulates water between the condenser of the chillers and the evaporator of the heat pump (2B) using a network if second secondary collector pipes (7A) and second secondary return pipes (9A), Where there are a number of

chillers (2A) in operation, a second main collector pipe (6A) and a second main return pipe (8A) are used into which the respective secondary pipes (7A and 9A) are connected. The second loop (5A) is an open loop.
A third loop (5B), which is an open loop, connects the heat pump (2B) and the pretreatment tanks through a network of third secondary collector pipes (7B) and third secondary return pipes (9B). Where there are a number of pretreatment process tanks (10) in operation, a third main collector pipe (6B) and a third main return pipe (8B) are used into which the respective secondary pipes (7B and 9B) are connected.
In another embodiments of the present invention, heat exchangers (4 or 4A or 4 and 4A) are introduced between either the paint tanks (2) and the chillers (2A) (as shown in Figure 3 A), or between the heat pump (2B) and the pretreatment process tanks (10) (as shown in Figure 3B), or in both locations (as shown in Figure 3C).
In the automotive paint shops where the temperature of the paint in the paint tanks (2) is at about 30-33 °C and that of the chemicals in the pretreatment process tanks (10) is at around 50-55 °C, the heat exchangers are required either to step up or step down temperatures of fluids in the system. As in the case of the earlier embodiment, several loops are used for fluid circulation, the loops being open or

close and constructed using main and secondary pipes depending upon the number of components to be connected with each other.
As shown in Figure 3 A, a fourth loop (5C), which is an open loop, connects the paint cooling tanks and a set of first heat exchangers. The fourth loop (5C) comprises a set of fourth secondary collector pipes (7C) and fourth secondary return pipes (9C). Where there are a number of paint cooling tanks or a number of first heat exchangers, a fourth main collector pipe (6C) and a fourth main return pipe (8C) is provided into which the respective secondary pipes (7C and 9C) connect. The first heat exchangers are of a plate type.
A fifth loop (5D), which is a closed loop, is formed between the set of first heat exchangers (4) and the evaporators of set of chillers. The fifth loop (5D) is formed using a set of fifth secondary collector pipes (7D) and fifth secondary return pipes (9D). Where there are a number of first heat exchangers (4) or a number of chillers, a fifth main collector pipe (6D) and a fifth main return pipe (8D) are provided into which the respective secondary pipes (7D and 9D) connect. A single first heat exchanger may connect with a number of chillers or conversely a single chiller may be connected to a number of first heat exchangers.

As in the case of the previous embodiment, the second loop (5A) connects the chillers with the heat pump (2B).
As shown in Figures 3B a 3B and 3C, a sixth loop (5E), which is a closed loop, connects the heat pump (2B) and a set of second heat exchangers. The sixth loop (5E) is formed using a set of sixth secondary collector pipes (7E) and sixth secondary return pipes (9E). Where there are a number of second heat exchangers provided, a sixth main collector pipe (6E) and a sixth main return pipe (8E) is provided into which the respective secondary pipes (7E and 9E) connect.
As shown in Figures 3B and 3C, a seventh loop (5F) is provided between the set of second heat exchangers (4A) and the set of pretreatment process tanks (10). The seventh loop (5F), which is an open loop, is formed using a set of seventh secondary collector pipes (7F) and seventh secondary return pipes (9F). Where there are a number of second heat exchangers (4A) or a number of pretreatment process tanks (10), a seventh main collector pipe (6F) and a sixth main return pipe (8F) are provided into which the respective secondary pipes (7F and 9F) connect.
A heat pump (2B) is a machine operating on vapor absorption principle. Figure 4 explains the working of the Vapor absorption heat pump. The machine uses water

as refrigerant & lithium bromide as carrier. The refrigerant absorbs the heat in its evaporator section which is essentially a shell & tube type heat exchanger. The refrigerant absorbs heat from the external water circuit called chilled water (not shown).
In the present invention (refer figure 3) the cooling water loop from the chiller (2A) is rejecting heat in the evaporator, which is absorbed by the refrigerant in the heat pump. Here it converts in to a vapor after evaporation & passes on to the next section, the absorber section. This section also essentially a shell & tube type heat exchanger. The heated lithium bromide, coming from the generator section, also enters absorption section & absorbs the water vapor & also rejects heat to a cooling water loop. The liquid solution of water & lithium bromide, called as diluted solution, is then is carried to the generator section, which is again a shell & tube type heat exchanger. Here the solution is heated & the water evaporates & separates out from the lithium bromide. The heating of the solution can be done by number of sources of energy like, LPG, HSD, Steam, Hot water or even waste hot gases. The concentrated lithium bromide solution then passes on to the absorber section thus completing a closed loop. The evaporated water passes on to the condenser, again a shell & tube type heat exchanger to get cooled & condensed. The heat is rejected to the same cooling water loop which also passes through the absorber section. The condensed water is now sucked in to the

evaporator, which is maintained at vacuum pressure, & vaporized. During vaporization it absorbs heat from the chilled water loop.
The evaporator & absorber sections form the lower shell of the heat pump (2B) & are typically maintained at a pressure (vacuum) of 6 to 7mm of Hg. The generator & condenser form the upper shell. The generator is maintained at about 700mm of Hg & condenser at about 60mm of Hg.
According to our invention the cooling water loop of the Chiller, termed as the second loop (5A), which passes through the condenser of the chiller, brings the water at 42°C to the heat pump (2B). The evaporator of the heat pump (2B) rejects heat from this water and cools it down to 37°C. The cooled water is taken back to the condenser of the chiller, thus completing the close loop. This loop is also shown in Figure 4. In the conventional systems, the cooling water loop is maintained at a temperature profile of 37 °C - 32 °C. However, in consideration of the standard heat pumps which are commercially available, this has been altered to 42 °C/ 37°C, so that the heat absorption in heat pump (2B) is efficient and effective.

In the embodiment represented by Figure 3A, at the condenser end of the heat pump (2B), the heat is rejected to a closed water loop termed as the sixth loop (5E). The water in the sixth loop (5E) is heated up to 90 °C. Thus heat absorbed from the second loop (5 A) in the heat pump (2B) evaporator at lower temperature (of 42 °C) is 'pumped' up to a higher temperature (90 °C) in the heat pump (2B) condenser, to the sixth loop (5E).
According to the present invention, the recovered heat, along with the 'pumped up' heat, which is in the form of heated liquid in the sixth loop (5E), is used to heat any operations, such as a pretreatment operation, in an industrial process. These operations, which are a recipient of the recovered heat, may be located physically distant from the source of heat recovery. The recovered heat is transferred to these operations through a pipe network carrying fluids. Depending on the plant design, a number of heat exchangers may be used towards this purpose.
In accordance with the embodiment shown in Figure 3A, the recovered heat according to the present invention is provided to a second heat exchanger (4A) through second loop (5A). This is typically the case with the paint shop of an automotive manufacturing unit or in the case of other applications such as the white goods manufacture, where chemicals that require heating to 55-60 °C are

kept in the pretreatment tanks and which are the final recipients of the recovered heat. The second heat exchanger (4A) is of a plate type and used to transfer heat using a liquid to liquid principle of heat transfer. The heat recovered from the chiller condenser is finally delivered from the second heat exchanger (4A) through a seventh loop (5F) to the applications or operations where it is required.
In Figure 3 A are shown several pretreatment units containing chemicals that require heating. The seventh loop (5F), which is in fact an open loop, comprises a pipe arriving from a first heat exchanger which opens into a pretreatment tank containing chemical that requires heating. A pipe that leads from the pretreatment tank is run back to a second heat exchanger, thus forming a loop. The seventh loop (5F) is thus partially open (the pretreatment tank) and partially close (the pipes). Preferably there is a seventh loop (5F) formed between each second heat exchanger and a corresponding pretreatment tank. The chemical contained within the seventh loop (5F) is maintained at around 55 to 60 CC.
The Figure 3, which shows an embodiment where the final delivery of heat is directly from a third loop (5B) that leads from the heat pump condenser, is suitable in the cases where the process temperatures of around 90 °C are required.

Depending on the plant design a number of first heat exchangers and/or a number of second heat exchangers are used. In the case where more than one first or second heat exchangers is used, adequate piping network is provided for collecting liquids arriving from individual heat exchangers or pretreatment units to feed into the return part of a relevant close loop. Similarly, adequate piping network is provided for delivering liquids from onward part of a relevant close loop to individual heat exchangers or pretreatment units.
A
It has been observed by the inventors that the heat recovered by the condensers is typically sufficient to run the pretreatment tanks in a steady state in an industrial process such as one used in the paint shop of an automobile manufacturing operation. However it is also well known that, during the start-up of a pretreatment process of a paint shop operation, additional source of heat is required as the temperature required at the start-up is typically higher than that required in steady-state or ongoing operations of the pretreatment tanks. The system of the present invention therefore provides a hot water generator in conjunction with the heat pump (2B) so that the hot water generator (HWG) may be used optionally upon requirement. HWG is a shell and tube type heat exchanger which works on an indirect heating principle.

In the conventional processes, the HWG is placed in a separate loop with the first heat exchanger. However, as a further advantageous feature of the present invention and as shown in Figure 1, the heat pump (2B), the HWG and the first heat exchanger are provided in a series connection in the present invention on the onward part of the second close loop. The inventors have found that this allows the optimum use of the recovered heat while providing the additional heat required during the start up stage without having to resort to plant shutdown.
It is observed that there's a gradual temperature drop between the various heat exchange loops that are described here, namely the first loop (5) to second loop (5A), further second to third loop (5B). It is evident that the temperature of the loop at the upstream end (in our case the first loop (5) at the heat pump (2B)) is the highest. The temperature of the fluids in the first close loop is smaller and those of the liquids in the 2nd close loop still smaller with the lowest temperatures achieved in the third loop (5B).
It is however, a substantial benefit that the heat requirement of the entire pretreatment operation which involves 755 m of chemicals maintained at 55-60 °C, is met through the heat that would be wasted to the atmosphere in absence of the present invention.

The pipe network may carry any fluids for heat transfer, preferably liquids, more preferably water.
The temperature of the fluids in the first close loop is approximately 37 °C for fluid leaving the heat pump (2B) and approx. 42 °C for the fluid returning to the heat pump (2B). The temperature of fluids coming out of the heat pump (2B) into the HWG is approximately 90 °C and that of fluids coming out of the HWG approximately 120 °C during the start-up phase of the pretreatment tanks. The temperature of fluids returning to the heat pump from the first heat exchangers is approximately 70 °C. The temperature of the chemicals in the third loop (5B) is approximately 55 to 60 °C.
All the equipment in the system like the Chillers, heat pump (2B)s, heat exchangers & hot water generators work in synchronization & are elaborately automated. Complete system is controlled by PLC and feedback given to and taken from any equipment enables the operation of the complex system. To maintain the required flows of liquids through the loops appropriate sized pumps are provided.
Example of the invention:

The invention was deployed in two separate paint shops installations located adjacent to each other. The first paint shop had overall physical plan dimensions of 330m x 116m. The second paint shop had plan dimensions of 200m x 50m.
The length of piping involved in the condenser heat recovery process was approximately 300m. A pipe size of 300NB was laid for this purpose. The water was circulated through the first close water loop at a rate of 400 m/hr.
Each of the two paint shops had two paint systems containing liquids that need cooling (one for electro-deposition process and one for painting process). Corresponding to each tank was provided a heat exchanger. A total of two chillers (each of 154 ton capacity) was used in a parallel configuration for both paint shops together. A single heat pump was provided to service both chillers.
At the pretreatment end, there were used five tanks in one paint shop and three in the other. A single hot water generator was used to supply heat to all tanks in the start-up phase,

The temperature of the input water to heat pump from the chiller was of 42°C at its evaporator end. This was pumped back the chiller at 37 °C. This lower grade heat, in terms of the low temperature relative to that required by the pretreatment process chemicals, was 'pumped up' to 90 °C at the condenser end of the heat pump. This heated water was then passed through the Hot water generator (HWG), which raised its temperature to 120 oC before it reached the first heat exchangers in the start up phase of the pretreatment process. In the present example eight second heat exchangers were provided. Once the process reached a steady state, the HWG was shut down. The pretreatment chemical temperatures are maintained at 55 to 60 °C. An open loop was formed between a first heat exchanger and a pretreatment tank circulating the pretreatment chemicals between the pretreatment tanks and the second heat exchangers. These chemicals were maintained at 55 to 60 °C at all times. The water returning to the heat pump from the 2nd heat exchangers after passing the heat to the pretreatment was maintained at around 90 °C during the steady state operations as it was returned to the heat pump. An approximately 750m of pipeline constituted the loop between the 2nd heat exchangers and the heat pump. 185 m3 /Hr water flow was maintained through the second loop & the 200NB diameter piping was provided to enable the same.
The pretreatment lines in the two paint shops were stretched over the length of 200m & 70m respectively. The size of the piping used for this purpose was

200NB to carry water at a capacity of 185m3/Hr and then further distribute it to 8 heat exchangers (5 locations in one paint shop & 3 locations in other paint shop)
The 5 heated pretreatment process tanks in first paint shop were of following capacities - 1)13 m3, 2) 20 m3, 3) 160 m3, 4)160 m3, 267 m3. The three heated preatreatment process tanks in the second paint shop were of following capacities - 1) 15 m3, 2) 60 m3, 3)60 m3.
All pipelines were insulated to prevent any heat loss from the system.
The heat recovery was calculated to be of the order of 0.8 Million Kcal / hr both the paint shops together. This represents a rate of recovery of rejected heat at approximately 87% level.
It is evident from the foregoing description and examples that the present invention has the following embodiments:
1. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat, characterized in that said system comprises

at least one paint tank, a system for heat exchange made up using at least one chiller, a heat pump, a set of loops, and at least one pretreatment process tank containing chemicals, said set of/oops connecting said paint tanks, said chillers, said heat pump and said pretreatment tanks such that heat is recovered from the paint from said paint tanks and transferred to the chemicals in said pretreatment process tanks.
2. A system for recovering heat from industrial paint cooling operation and
heating chemicals in pretreatment process tanks using the recovered heat as
claimed in claim 1, wherein
said loops carry fluids as medium of heat transfer, and wherein said set of chillers have individual evaporator and condenser units, said heat pump has its own evaporator and condenser units, and wherein heat is recovered by said chillers from said paint tanks and transferred to the chemicals contained within said pretreatment process tanks through said system of loops.
3. A system for recovering heat from industrial paint cooling operation and
heating chemicals in pretreatment process tanks using the recovered heat as
claimed in claims 1 and 2, wherein said system of heat exchange further
comprises a means for hot water generation.

4. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 3, wherein said set of loops comprises a set of first loops, a second loop and a third loop, wherein
- each of said first loop comprises a first secondary collector pipe and first secondary return pipe and circulates the paint from one said paint tanks through the evaporator of one of said chillers and returns it to respective said paint tanks in a continuous loop,
- said second loop comprises a network of second secondary collector pipes, and second secondary return pipes, a second main collector pipe and a second main return pipe, and circulates water from the condenser of said chillers and the evaporator of said heat pump and returns it to said chillers in a continuous loop,
- said third loop comprises third secondary collector pipes and third secondary return pipes, a second main collector pipe and a second main return pipe, and circulates the chemicals in the pretreatment process tanks through the condenser of said heat pump and returns them to said pretreatment process tanks via said hot water generator in a continuous loop,
thereby completing the process of recovering heat from said paint tanks and transferring it to said pretreatment process tanks.

5. A system for recovering heat from industrial paint cooling operation and
heating chemicals in pretreatment process tanks using the recovered heat
as claimed in claim 4, wherein said first loop further comprises a first main
collector pipe and a first main return pipe in the case where there is more
than one paint tank connected to a single chiller or in the case where more
than one chiller is connected to a single paint tank.
6. A system for recovering heat from industrial paint cooling operation and
heating chemicals in pretreatment process tanks using the recovered heat as
claimed in claim 3, said system further comprising at least one first heat
exchanger, a second loop, a third loop, a set of fourth loops and a fifth loop,
wherein
- each of said fourth loop comprises a network of fourth secondary collector pipes and fourth secondary return pipes and circulates the paint from said paint tanks through said first heat exchanger and returns it to said paint tanks in a continuous loop,
- said fifth loop comprises a network of fifth secondary collector pipes, and fifth secondary return pipes, a fifth main collector pipe and a fifth main return pipe, and circulates water from said first heat exchanger to the evaporators of said chillers returns it to said first heat exchangers in a continuous loop,
- said second loop comprises a network of second secondary collector pipes, and second secondary return pipes, a second main collector pipe and a second

main return pipe, and circulates water from the condenser of said chillers and the evaporator of said heat pump and returns it to said chillers in a continuous loop,
- said third loop comprises third secondary collector pipes and third secondary return pipes, a second main collector pipe and a second main return pipe, and circulates the chemicals in the pretreatment process tanks through the condenser of said heat pump and returns them to said pretreatment process tanks via said hot water generator in a continuous loop,
thereby completing the process of recovering heat from said paint tanks and transferring it to said pretreatment process tanks.
7. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 6, wherein said fourth loop further comprises a fourth main collector pipe and a fourth main return pipe in the case where there is more than one paint tank connected to a single first heat exchanger or in the case where more than one first heat exchanger is connected to a single paint tank.
8. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 3, said system further comprising at least one second heat

exchanger, a set of first loops, a second loop, a sixth loop and a set of seventh loops, wherein
- each of said first loop comprises a first secondary collector pipe and first secondary return pipe and circulates the paint from one said paint tanks through the evaporator of a corresponding said chiller and returns it to respective said paint tanks in a continuous loop,
- said second loop comprises a network of second secondary collector pipes, and second secondary return pipes, a second main collector pipe and a second main return pipe, and circulates water from the condenser of said chillers and the evaporator of said heat pump and returns it to said chillers in a continuous loop,
- said sixth loop comprises sixth secondary collector pipes and sixth secondary return pipes, a sixth main collector pipe and a sixth main return pipe, and circulates water from a set of second heat exchangers through the condenser of said heat pump and returns them to said set of second heat exchangers via said hot water generator in a continuous loop,
- each of said seventh loop comprises seventh secondary collector pipes and seventh secondary return pipes, and circulates the chemicals in the pretreatment process tanks through a corresponding said second heat condenser returns them to said pretreatment process tanks,

thereby completing the process of recovering heat from said paint tanks and transferring it to said pretreatment process tanks.
9. A system for recovering heat from industrial paint cooling operation and
heating chemicals in pretreatment process tanks using the recovered heat as
claimed in claim 8, wherein said seventh loop further comprises a seventh
main collector pipe and a seventh main return pipe in the case where there is
more than one pretreatment process tank is connected to a single second heat
exchanger or in the case where more than one second heat exchanger is
connected to a single pretreatment process tank.
10. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 8, wherein said first loop further comprises a first main collector pipe and a first main return pipe in the case where there is more than one paint tank connected to a single chiller or in the case where more than one chiller is connected to a single paint tank.
11. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 8, wherein said seventh loop further comprises a seventh main collector pipe and a seventh main return pipe in the case where there is

more than one pretreatment process tank is connected to a single second heat exchanger or in the case where more than one second heat exchanger is connected to a single pretreatment process tank, and wherein
said first loop further comprises a first main collector pipe and a first main return pipe in the case where there is more than one paint tank connected to a single chiller or in the case where more than one chiller is connected to a single paint tank.
12. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 3, said system further comprising at least one second heat exchanger, a set of fourth loops, a fifth loop, a second loop, a sixth loop and a set of seventh loops, wherein
- each of said fourth loop comprises a network of fourth secondary collector pipes and fourth secondary return pipes and circulates the paint from said paint tanks through said first heat exchanger and returns it to said paint tanks in a continuous loop,
- said fifth loop comprises a network of fifth secondary collector pipes, and fifth secondary return pipes, a fifth main collector pipe and a fifth main return

pipe, and circulates water from said first heat exchanger to the evaporators of said chillers returns it to said first heat exchangers in a continuous loop,
- said second loop comprises a network of second secondary collector pipes, and second secondary return pipes, a second main collector pipe and a second main return pipe, and circulates water from the condenser of said chillers and the evaporator of said heat pump and returns it to said chillers in a continuous loop,
- said sixth loop comprises sixth secondary collector pipes and sixth secondary return pipes, a sixth main collector pipe and a sixth main return pipe, and circulates water from a set of second heat exchangers through the condenser of said heat pump and returns them to said set of second heat exchangers via said hot water generator in a continuous loop,
- each of said seventh loop comprises seventh secondary collector pipes and seventh secondary return pipes, and circulates the chemicals in the pretreatment process tanks through a corresponding said second heat condenser returns them to said pretreatment process tanks,
13. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 12, wherein said fourth loop further comprises a fourth main collector pipe and a fourth main return pipe in the case where there is more

than one paint tank connected to a single first heat exchanger or in the case where more than one first heat exchanger is connected to a single paint tank.
14. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 12, wherein said seventh loop further comprises a seventh main collector pipe and a seventh main return pipe in the case where there is more than one pretreatment process tank is connected to a single second heat exchanger or in the case where more than one second heat exchanger is connected to a single pretreatment process tank.
15. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 12, wherein said fourth loop further comprises a fourth main collector pipe and a fourth main return pipe in the case where there is more than one paint tank connected to a single first heat exchanger or in the case where more than one first heat exchanger is connected to a single paint tank, and wherein,
said seventh loop further comprises a seventh main collector pipe and a seventh main return pipe in the case where there is more than one pretreatment process tank is connected to a single second heat exchanger or in the case

where more than one second heat exchanger is connected to a single pretreatment process tank.
It is also evident from the foregoing discussion that the present invention offers several advantages over the conventional methods of heat recovery. These are:
- It provides a system of heat recovery whereby the recovered heat may be used in large scale industrial applications, hitherto unknown
- It provides a system whereby recovered heat may be used even during the start up phases of the pretreatment processes (where the recovered heat is used) without halting the operations
The amount of heat recovered is so substantial that it significantly compensates the reduced performance of the chillers.
While the above description contains much specificity, these should not be construed as limitation in the scope of the invention, but rather as an exemplification of the preferred embodiments thereof. It must be realized that modifications and variations are possible based on the disclosure given above without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.

We claim:
1. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat, characterized in that said system comprises
at least one paint tank, a system for heat exchange made up using at least one chiller, a heat pump, a set of loops, and at least one pretreatment process tank containing chemicals, said set of loops connecting said paint tanks, said chillers, said heat pump and said pretreatment tanks such that heat is recovered from the paint from said paint tanks and transferred to the chemicals in said pretreatment process tanks.
2. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 1, wherein
said loops carry fluids as medium of heat transfer, and wherein said set of chillers have individual evaporator and condenser units, said heat pump has its own evaporator and condenser units, and wherein heat is recovered by said chillers from said paint tanks and transferred to the chemicals

contained within said pretreatment process tanks through said system of loops.
3. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claims 1 and 2, wherein said system of heat exchange further comprises a means for hot water generation.
4. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 3, wherein said set of loops comprises a set of first loops, a second loop and a third loop, wherein

- each of said first loop comprises a first secondary collector pipe and first secondary return pipe and circulates the paint from one said paint tanks through the evaporator of one of said chillers and returns it to respective said paint tanks in a continuous loop,
- said second loop comprises a network of second secondary collector pipes, and second secondary return pipes, a second main collector pipe and a second main return pipe, and circulates water from the condenser of said chillers and the evaporator of said heat pump and returns it to said chillers in a continuous loop,

- said third loop comprises third secondary collector pipes and third secondary return pipes, a second main collector pipe and a second main return pipe, and circulates the chemicals in the pretreatment process tanks through the condenser of said heat pump and returns them to said pretreatment process tanks via said hot water generator in a continuous loop, thereby completing the process of recovering heat from said paint tanks and transferring it to said pretreatment process tanks.
5. A system for recovering heat from industrial paint cooling operation and
heating chemicals in pretreatment process tanks using the recovered heat
as claimed in claim 4, wherein said first loop further comprises a first main
collector pipe and a first main return pipe in the case where there is more
than one paint tank connected to a single chiller or in the case where more
than one chiller is connected to a single paint tank.
6. A system for recovering heat from industrial paint cooling operation and
heating chemicals in pretreatment process tanks using the recovered heat as
claimed in claim 3, said system further comprising at least one first heat
exchanger, a second loop, a third loop, a set of fourth loops and a fifth loop,
wherein
- each of said fourth loop comprises a network of fourth secondary collector pipes and fourth secondary return pipes and circulates the paint from said

paint tanks through said first heat exchanger and returns it to said paint tanks in a continuous loop,
- said fifth loop comprises a network of fifth secondary collector pipes, and fifth secondary return pipes, a fifth main collector pipe and a fifth main return pipe, and circulates water from said first heat exchanger to the evaporators of said chillers returns it to said first heat exchangers in a continuous loop,
- said second loop comprises a network of second secondary collector pipes, and second secondary return pipes, a second main collector pipe and a second main return pipe, and circulates water from the condenser of said chillers and the evaporator of said heat pump and returns it to said chillers in a continuous loop,
- said third loop comprises third secondary collector pipes and third secondary return pipes, a second main collector pipe and a second main return pipe, and circulates the chemicals in the pretreatment process tanks through the condenser of said heat pump and returns them to said pretreatment process tanks via said hot water generator in a continuous loop,
thereby completing the process of recovering heat from said paint tanks and transferring it to said pretreatment process tanks.
7. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as

claimed in claim 6, wherein said fourth loop further comprises a fourth main collector pipe and a fourth main return pipe in the case where there is more than one paint tank connected to a single first heat exchanger or in the case where more than one first heat exchanger is connected to a single paint tank.
8. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 3, said system further comprising at least one second heat exchanger, a set of first loops, a second loop, a sixth loop and a set of seventh loops, wherein
- each of said first loop comprises a first secondary collector pipe and first secondary return pipe and circulates the paint from one said paint tanks through the evaporator of a corresponding said chiller and returns it to respective said paint tanks in a continuous loop,
- said second loop comprises a network of second secondary collector pipes, and second secondary return pipes, a second main collector pipe and a second main return pipe, and circulates water from the condenser of said chillers and the evaporator of said heat pump and returns it to said chillers in a continuous loop,
- said sixth loop comprises sixth secondary collector pipes and sixth secondary return pipes, a sixth main collector pipe and a sixth main return pipe, and circulates water from a set of second heat exchangers through the condenser of

said heat pump and returns them to said set of second heat exchangers via said hot water generator in a continuous loop,
- each of said seventh loop comprises seventh secondary collector pipes and seventh secondary return pipes, and circulates the chemicals in the pretreatment process tanks through a corresponding said second heat condenser returns them to said pretreatment process tanks,
thereby completing the process of recovering heat from said paint tanks and transferring it to said pretreatment process tanks.
9. A system for recovering heat from industrial paint cooling operation and
heating chemicals in pretreatment process tanks using the recovered heat as
claimed in claim 8, wherein said seventh loop further comprises a seventh
main collector pipe and a seventh main return pipe in the case where there is
more than one pretreatment process tank is connected to a single second heat
exchanger or in the case where more than one second heat exchanger is
connected to a single pretreatment process tank.
10. A system for recovering heat from industrial paint cooling operation and
heating chemicals in pretreatment process tanks using the recovered heat as
claimed in claim 8, wherein said first loop further comprises a first main
collector pipe and a first main return pipe in the case where there is more than

one paint tank connected to a single chiller or in the case where more than one chiller is connected to a single paint tank.
11. A system for recovering heat from industrial paint cooling operation and
heating chemicals in pretreatment process tanks using the recovered heat as
claimed in claim 8, wherein said seventh loop further comprises a seventh
main collector pipe and a seventh main return pipe in the case where there is
more than one pretreatment process tank is connected to a single second heat
exchanger or in the case where more than one second heat exchanger is
connected to a single pretreatment process tank, and wherein
said first loop further comprises a first main collector pipe and a first main return pipe in the case where there is more than one paint tank connected to a single chiller or in the case where more than one chiller is connected to a single paint tank.
12. A system for recovering heat from industrial paint cooling operation and
heating chemicals in pretreatment process tanks using the recovered heat as
claimed in claim 3, said system further comprising at least one second heat
exchanger, a set of fourth loops, a fifth loop, a second loop, a sixth loop and a
set of seventh loops, wherein

- each of said fourth loop comprises a network of fourth secondary collector pipes and fourth secondary return pipes and circulates the paint from said paint tanks through said first heat exchanger and returns it to said paint tanks in a continuous loop,
- said fifth loop comprises a network of fifth secondary collector pipes, and fifth secondary return pipes, a fifth main collector pipe and a fifth main return pipe, and circulates water from said first heat exchanger to the evaporators of said chillers returns it to said first heat exchangers in a continuous loop,
- said second loop comprises a network of second secondary collector pipes, and second secondary return pipes, a second main collector pipe and a second main return pipe, and circulates water from the condenser of said chillers and the evaporator of said heat pump and returns it to said chillers in a continuous loop,
- said sixth loop comprises sixth secondary collector pipes and sixth secondary return pipes, a sixth main collector pipe and a sixth main return pipe, and circulates water from a set of second heat exchangers through the condenser of said heat pump and returns them to said set of second heat exchangers via said hot water generator in a continuous loop,
- each of said seventh loop comprises seventh secondary collector pipes and seventh secondary return pipes, and circulates the chemicals in the pretreatment process tanks through a corresponding said second heat condenser returns them to said pretreatment process tanks,

13. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 12, wherein said fourth loop further comprises a fourth main collector pipe and a fourth main return pipe in the case where there is more than one paint tank connected to a single first heat exchanger or in the case where more than one first heat exchanger is connected to a single paint tank.
14. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 12, wherein said seventh loop further comprises a seventh main collector pipe and a seventh main return pipe in the case where there is more than one pretreatment process tank is connected to a single second heat exchanger or in the case where more than one second heat exchanger is connected to a single pretreatment process tank.
15. A system for recovering heat from industrial paint cooling operation and heating chemicals in pretreatment process tanks using the recovered heat as claimed in claim 12, wherein said fourth loop further comprises a fourth main collector pipe and a fourth main return pipe in the case where there is more than one paint tank connected to a single first heat exchanger or in the case

where more than one first heat exchanger is connected to a single paint tank, and wherein,
said seventh loop further comprises a seventh main collector pipe and a seventh main return pipe in the case where there is more than one pretreatment process tank is connected to a single second heat exchanger or in the case where more than one second heat exchanger is connected to a single pretreatment process tank.