FORM-2
THE INDIAN PATENTS ACT, 1970
(39 of 1970) &
THE INDIAN PATENTS RULE, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
A COMPUTER IMPLEMENTED SYSTEM AND METHOD FOR ANALYZING
HEAT EXCHANGER NETWORKS AND FACILITATING SELECTION OF
OPTIMIZED MODIFICATIONS THEREOF
RELIANCE INDUSTRIES LIMITED
an Indian Company of Maker Chambers IV, Nariman Point, Mumbai - 400021, Maharashtra, India
Inventors: l.PAGADEPRADEEP
2. AGRAWAL MANISH
3. PACHORI PARTHSARATHI
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE DISCLOSURE
The present disclosure relates to the field of heat exchanger networks, more particularly, the present disclosure relates to systems and methods that facilitate energy conservation by analyzing and optimizing modifications of the heat exchanger networks.
BACKGROUND
In an industrial facility, heat exchangers are typically used as a part of the heat energy recovery systems. Conventionally, heat exchanger network retrofitting or grass root fitting or modification used to be done purely on a basis of requirement that too on a presumption that such retrofitting or grass root fitting or modification would be suffice for that specific requirement, there was little or no focus on the energy efficiency of the network as a whole. This approach could be tolerated in those days when the energy prices were not skyrocketing. Today, with continuously escalating energy prices there is a need for appropriately and cautiously modifying the existing heat exchanger network (HEN) to meet different requirements, particularly, for improving energy efficiency and performance of the existing heat exchanger network (HEN). The known methods and systems to improve energy efficiency by modifying existing heat exchanger network (HEN) in an industrial facility after analyzing the existing heat exchanger network (HEN) fails to consider the operating constraints of the process heat energy recovery system, of which the existing heat exchanger network (HEN) is a part and therefore fail to suggest potential modifications that are practically implementable.
Further, conventionally known systems and methods for facilitating modifications of the heat exchanger network (HEN) are not cost effective and necessitate large expenditures. Still further, conventionally known systems and methods for facilitating modifications of the heat exchanger network (HEN) are not accurate and reliable. Furthermore, conventionally known systems and methods for facilitating

modifications of the heat exchanger network (HEN) do not suggest all possible HEN modifications and thereby tend to miss some of the most suitable modifications. Furthermore, conventionally known systems and methods for facilitating modifications of the heat exchanger network (HEN) lacks the functionality to assess energy losses due to an increase in the flow path of the heat transfer fluid, pumping costs and other associated costs. Thereby, in existing systems and methods the cost considerations almost does not factor in suggesting potential modifications, hence a proposed modification at a later date may be found to have severe economic infeasibility.
The prior art discloses various HEN modification / retrofit methods which are mostly based on Advanced Mathematics, Pinch Technology, Path Analysis and Engineering Intuition. These methods suffer from certain limitations which are mentioned herein. Conventionally known retrofitting methods based on Advanced Mathematics typically operate as "black boxes", thereby making it difficult to assess the true suitability of the solutions produced by this approach. Conventionally known retrofitting methods based on Pinch Technology are useful for grass-root designs but do not provide clear guidelines for HEN modifications. Conventionally known Path Analysis is widely used as it provides retrofit solution with limited structural changes in the existing HEN, but still the method suffer limitations as it often misses optimal retrofit solutions and also does not take into consideration practical constraints such as pressure drop limitation, process controllability, field space and configuration limitations etc. Other conventionally known retrofitting method based on engineering intuition, such as Retrofitting Thermodynamic Diagram (RTD) captures the engineering intuition in a structured way by making graphically explicit both the loads and driving force in a HEN, but the method suffer limitations as it is purely based on engineering judgment and it alone does not ensure the optimality of retrofit solutions provided thereby.
Additionally, none of the conventionally known methods are able to solve the issue of industrial modifications in an automated procedure, while retaining user interaction and taking care of practical constraints. This leads to the need for new methods to

cater to the retrofit/modification problems in a reliable manner, providing the most optimal solutions with user interaction and simultaneously honoring the practical constraints such as pressure drop limitation, process controllability, field space and configuration limitations etc.
Accordingly, there is felt a need for a system and method that facilitates modification of an existing heat exchanger network (HEN) in a simple and cost effective manner. Furthermore, there is a need for a system and method that considers the operating constraints of the process heat energy recovery system of which the existing heat exchanger network (HEN) is a part of and subsequently provides heat exchanger network re-alignment solutions that are practically implementable. Furthermore, there is a need for a system and method that do not miss the optimal HEN modification. Still further, there is a need for a system and method that minimizes energy losses due to an increase in the flow path of the heat transfer fluid, pumping losses/costs and other associated losses/costs. Furthermore, there is a need for a system and method that enhances process performance and ensures safety.
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 an economical system and method for facilitating modifications of an existing heat exchanger network for improving the performance of the process heat energy recovery system, of which the existing heat exchanger network (HEN) is a part.

An object of the present disclosure is to provide a system and method that improves energy efficiency of the existing heat exchanger network (HEN).
Another object of the present disclosure is to provide a system and method that provides all feasible solutions in user friendly form, particularly in the form of graphical representations that are easy to analyze.
Yet another object of the present disclosure is to provide a system and method that is simple to understand and convenient to implement while still considering operating constraints of the process heat energy recovery systems, of which the existing heat exchanger network (HEN) is a part.
Still another object of the present disclosure is to provide a system and method that caters to the heat exchanger networks of varying levels of complexities.
Another object of the present disclosure is to provide a system and method that effectively suggests different network topologies to effectively resolve implementation related issues faced in the heat exchanger network and facilitates selection of the most efficient and appropriate solution from the suggested solutions.
Yet another object of the present disclosure is to provide a system and method that reduces utility consumption while making only limited changes to the existing heat exchange network.
Yet another object of the present disclosure is to provide a system and method that finds all possible retrofit solutions without missing optimal retrofit solution.
Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure.

SUMMARY
The present disclosure envisages an interactive computer implemented system for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN).The computer implemented system for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) includes a first receiving module configured to receive the at least one input value and operating data, a first processing module configured to process at least one input value and operating data, a generator module configured to generate a representative topology corresponding to the heat exchanger network, at least one input module configured to input at least one value corresponding to a predetermined driving force value corresponding to each heat exchanger located within the heat exchanger network, a second receiver module configured to receive the values corresponding to the desired driving force value, a second repository configured to store the values corresponding to the predetermined driving force value, a second processing module configured to process the values corresponding to the predetermined driving force value and generate processed values and a selection module configured to select an optimal heat exchanger topology. The first processing module includes a first calculator module and a first repository. The first calculator module is configured to calculate the values corresponding to at least a load and a driving force value associated with at least one heat exchanger located within the heat exchanger network and the first repository is configured to store the values pertaining to the load and the driving force value associated with at least one heat exchanger located within the heat exchanger network. The second processing module includes an optimizer, a second calculating module and an adjusting module. The optimizer is configured to optimize at least one heat exchanger network based on the processed values. The second calculating module is configured to calculate at least the load and driving force value associated with each heat exchanger located within the plurality of heat exchanger network topologies. The adjusting module is configured to adjust at least the relative position of at least one heat exchanger with respect to at least one heat exchanger located within the plurality of heat exchanger network topologies. The

adjusting module further configured to calculate the load and driving force value, corresponding to each heat exchanger whose positioning has been adjusted.
A computer implemented method for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) in accordance with another embodiment includes the step of receiving at least one input value and operating data corresponding to at least one heat exchanger located within at least one heat exchanger network, processing the at least one input value and operating data, calculating, based on the input value and operating data, at least a load and a driving force value associated with at least one heat exchanger located within the heat exchanger network, storing in a first repository, the load and driving force value associated with at least one heat exchanger located within the heat exchanger network, generating a representative topology corresponding to the heat exchanger network associated with each heat exchanger located within the heat exchanger network, displaying the representative topology in combination with the load, EMAT, bypass fraction, inlet temperature, outlet temperature, heat transfer area etc. associated with at least one heat exchanger located within the heat exchanger network, inputting the values corresponding to the desired predetermined driving force value corresponding to each heat exchanger located within the heat exchanger network, storing the values corresponding to the predetermined driving force value in a second repository, processing the values corresponding to the predetermined driving force value and generate processed values, optimizing the at least one heat exchanger network based on the processed values and generating a plurality of heat exchanger networks that adhere to processed values, calculating at least the load and driving force value associated with each heat exchanger located within the plurality of heat exchanger network topologies, adjusting the positioning of at least one heat exchanger located within said plurality of heat exchanger network topologies and calculating heat exchanger load and driving force within the heat exchanger network topologies for which position of heat exchanger(s) is adjusted, selecting an optimal heat exchanger topology by comparing savings in utility cost, required capital cost of modification and payback period for the plurality of heat exchanger network topologies obtained

from optimization step and plurality of heat exchanger network topologies for which position of heat exchangers) is adjusted and finally displaying the selected heat exchanger network topology along with at least the corresponding load, EMAT, bypass fraction, inlet temperature, outlet temperature, heat transfer area etc. associated with each heat exchanger located within the selected heat exchanger network topology.
DETAILED DESCRIPTION
The computer implemented system and method for analyzing heat exchanger networks and facilitating selection of optimized modifications of the heat exchanger networks will now be described with reference to the embodiments which do 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 system and method for analyzing heat exchanger networks and facilitating selection of optimized modifications of the heat exchanger networks (HEN) used in an industrial facility. The system of the present disclosure is used for analyzing heat exchanger networks, for facilitating selection of optimized and energy efficient heat exchanger network. More particularly, the present disclosure relates to a system for use with a heat exchanger network (HEN), of process heat energy recovery system, that can be used for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN), thereby improving energy efficiency and performance of the process heat energy recovery system of which the heat exchanger network (HEN) is a part. The system and method for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) considers the operating constraints of the process heat energy recovery systems in which the existing heat exchanger networks (HEN) are installed. Therefore, the system and method for retrofitting a heat exchanger network is simple, convenient and practically implementable. The system and method for analyzing heat exchanger networks and facilitating selection of optimized heat

exchanger network (HEN) involves introducing a heat exchanger or changing heat exchange area of any existing exchanger or changing bypass fraction of a heat exchanger or deleting an existing exchanger or relocating an existing exchanger in order to reduce the waste heat to atmosphere and thereby enhance the efficiency of the heat exchanger network (HEN). The system for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) may suggest changes in the heat exchanger network (HEN) such as replacing at least one heat exchanger of the heat exchanger network with at least one heat exchanger.
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 present disclosure envisages a system and method for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) for improving the energy efficiency and performance of the process heat energy recovery systems, of which the heat exchanger network (HEN) is a part. The method for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) is also referred to as the Feasible Exchange Trajectory Analysis (FETA). FETA is a modification and improvement over the concept of Path Analysis known in the prior art. The prior art Path Analysis is widely used method. The path (or trajectory) in Path Analysis, as available in prior art, is defined as a connection between the hot stream having cold utility (cooler) and the cold stream having hot utility (heater) via at least one process - process heat exchanger. The significance of a path is that it reduces the duty of utility exchangers by changing area and increasing duties of process - process exchangers by the same amount along the

path, thus the overall heat balance is maintained. Figure 1 illustrates a Path Analysis diagram as available from prior art; by changing area of process-process exchangers PI and P2, the remaining part of the network viz. process-process exchangers P3 and P4 remains unaffected. A path therefore represents an opportunity to save energy whilst only making limited changes to the network. Despite this ability of the Path Analysis of the prior art, the Path Analysis system suffers many limitations as describe herein. In Path Analysis heat exchange area of an existing exchanger is changed or new exchanger is added by finding path only between streams which contain heaters (H) and coolers (C). It does not include the streams which do not have heater (H) and cooler (C) but their end temperature is controlled by means of a bypass through Temperature Controller (TC). In such streams, the bypass provides a buffer to control the duty of exchangers present in the stream and thus total duty of the stream. Thus bypass provides an opportunity to find additional options to add new exchanger and/ or change heat exchange area of an existing exchanger, yet making only limited changes in the network. In Path Analysis, all these solutions are missed, that results into missing many superior and optimal retrofit solutions. Also, Path Analysis does not provide sufficient user interaction; thus it ignores practical constraints such as hydraulic constraints, process control constraints, field space and configuration constraints etc.
In case of the interactive computer implemented system for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) of the present disclosure, the aforementioned limitations of Path Analysis are eliminated by introducing a new method named as "Feasible Exchange Trajectory Analysis ( hereinafter referred to as FETA)". FETA is more general and exhaustive as compared to the Path Analysis and provides more number of possible retrofit solutions as compared to the Path Analysis. FETA retains the strengths of Path analysis while overcoming its limitations. Similar to Path Analysis, FETA adds new exchanger and / or changes the heat exchange area of existing exchanger between hot stream having single or multiple coolers and cold stream having single or multiple heaters. Further, unlike Path Analysis, FETA adds new exchanger and / or changes the heat exchange

area of existing exchanger between hot stream having single or multiple coolers and cold streams having an end temperature controller with bypass. Still Further, unlike Path Analysis, FETA adds new exchanger and / or change heat exchange area of existing exchanger between cold streams having single or multiple having heaters and hot streams having an end temperature controller. Still Further, unlike Path Analysis, FETA adds new exchanger and / or changes heat exchange area of existing exchanger between hot and cold streams both having end temperature controllers.
The method and system for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) supports a unique mathematical cum graphical form of representation. The mathematical cum graphical representation depicts the information regarding the existing heat exchanger network and facilitates the selection or deletion of any retrofit solution. The graphical presentation makes it user interactive, thereby enabling the operator to consider the practical constraints of the process heat energy recovery system of which the heat exchanger network is a part of. With the mathematical presentation, FETA finds out optimum solution amongst many feasible solutions.
In accordance with another embodiment of present disclosure, the method and system for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) can include the integration of FETA with a known prior art tool called "Retrofit Thermodynamic Diagram (RTD)". Figure 2 illustrates RTD as available from prior art. RTD is used to capture the engineering intuition in a visual and structured way; it makes graphically explicit both the loads and efficiency in a HEN by applying first and second laws of thermodynamics. In present disclosure, the unique integration of FETA and RTD combine mathematical analysis with engineering intuition, which produces more practical retrofitting solutions. RTD can be used to screen out uneconomical or infeasible solutions obtained from FETA, just by applying thermodynamics, engineering intuition and common sense. The RTD is used to further confirm that no conspicuous solutions are missed by FETA.

Yet another embodiment of the disclosure can include a computer program with a user friendly graphic interface and a set of computer instructions which are executable to receive solutions related to the heat exchanger network (HEN) by using FETA and RTD.
Referring to Figure 3, the system 100 for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) in accordance with an embodiment of the present disclosure includes a first receiving module 10, a first processing module 20, a generator module 30, a second receiver module 40, a second repository 60, a second processing module 50 and a selection module 70.
The first receiving module 10 is configured to receive at least one input value and operating data corresponding to each heat exchanger located within a heat exchanger network. The first processing module 20 is configured to process the at least one input value and operating data. The first processing module 20 includes a first calculator module 22 and a first repository 24. The first calculator module 22 is configured to calculate the values corresponding to at least a load and a driving force value associated with at least one heat exchanger located within the heat exchanger network and the first repository 24 is configured to store the values pertaining to the load and the driving force value associated with at least one heat exchanger located within the heat exchanger network. More specifically, the first calculator module 22 is configured to calculate at least the load and the Exchanger Minimum Approach Temperature (EMAT) associated with each heat exchanger located within the heat exchanger network, based on the least one input value and operating data received by the first receiving module 10. The first repository 24 is configured to store data pertaining to the load and the Exchanger Minimum Approach Temperature (EMAT) associated with each heat exchanger located within the heat exchanger network.
The first receiving module 10 further receives additional parameters that define constrains associated with the heat exchanger network. The at least one input value and operating data corresponding to the heat exchanger network received by the first

receiving module 10 facilitates in specifying at least the topology and defining the heat exchanger network. The first receiving module 10 receives at least one input value and operating data selected from the group consisting of the*name of the stream, type of the stream hot or cold, exchanger bypass fraction, name of heat exchangers, heat exchanger inlet temperature, heat exchanger outlet temperature, effective mass specific heat of stream, existing utility loads, utility type, utility cost, equipment cost, details of temperature controllers and interrelation among streams if any. The first receiving module 10 may be selected from a group consisting of a key pad, a touch screen device and the like. The first repository 24 is configured to store values pertaining to the load and the driving force value associated with at least one heat exchanger located within the heat exchanger network that are fed by an operator of the system 100 and received by the first receiving module 10 for facilitating specifying at least the topology and defining the heat exchanger network.
The system 100, in accordance with present disclosure further includes a generator module 30 to generate a representative topology corresponding to the heat exchanger network based on least one input value and operating data received by the first receiving module 10, the load and the Exchanger Minimum Approach Temperature (EMAT) associated with each heat exchanger located within the heat exchanger network.
The system 100, in accordance with the present disclosure includes an input module 26 configured to input at least one value corresponding to a predetermined driving force value corresponding to each heat exchanger located within the heat exchanger network. More specifically, the input module 26 is configured to input desired Exchanger Minimum Approach Temperature (EMAT) corresponding to each heat exchanger located within the heat exchanger network. The second receiver module 40 is configured to receive the values corresponding to the predetermined driving force value. More specifically, the second receiver module 40 cooperates with the input module 26 to receive the values corresponding to at least the desired Exchanger Minimum Approach Temperature (EMAT) corresponding to each heat exchanger located within the heat exchanger network. The second repository 60 is configured to

store the values corresponding to the predetermined driving force value. More specifically, the second repository 60 is configured to store the values corresponding to the desired Exchanger Minimum Approach Temperature (EMAT).
The second processing module 50 is configured to process the values corresponding to the predetermined driving force value and generate processed values. More specifically, the second processing module 50 is configured to process the values corresponding to the desired Exchanger Minimum Approach Temperature (EMAT) and generate the processed values. The second processing module 50 further includes an optimizer 62, a second calculating module 64 and an adjusting module 66. The optimizer 62 is configured to optimize the heat exchanger network based on the processed values. The optimizer 62 is further configured to generate a plurality of heat exchanger network topologies that adheres to the processed values. The optimizer 62 is configured to optimize the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network. The optimizer 62 is configured to optimize the heat exchanger network by changing the by-pass fraction of at least one heat exchanger located within the heat exchanger network. The optimizer 62 is configured to optimize the heat exchanger network by changing the heat exchange area of at least one heat exchanger located within the heat exchanger network. The optimizer 62 is configured to optimize the heat exchanger network by deleting at least one heat exchanger located within the heat exchanger network.
The optimizer 62 optimizes the heat exchanger network by using Feasible Exchange Trajectory Analysis (FETA) along with "Retrofit Thermodynamic Diagram (RTD)", wherein FETA finds heat exchanger retrofit solutions with limited changes to existing heat exchanger network and does not miss the optimal retrofit solution and supports a unique graphical cum mathematical form of representation that depicts the information regarding the existing heat exchanger network and facilitates the selection or deletion of any retrofit solution, thereby making the selection of optimized heat exchanger network (HEN) user interactive and enabling the operator to consider the practical constraints of the process heat energy recovery system of which the heat exchanger network is a part of. More specifically, the optimizer 62 optimizes the heat

exchanger network by integrating all heat exchange network topologies obtained from FETA with and "Retrofit Thermodynamic Diagram (RTD)", wherein FETA and RTD together synergistically combine mathematical analysis with engineering intuition, to produces more optimal yet practical retrofitting solutions. The optimizer 62 is configured to optimize the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network, wherein the new heat exchanger is added between a hot stream having a cooler and a cold stream having a heater. The optimizer 62 is configured to optimize the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network, wherein the new heat exchanger is added between a hot stream having a cooler and a plurality of cold streams having an end temperature controller. The optimizer 62 is configured to optimize the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network, wherein the new heat exchanger is added between a cold stream having a heater and a plurality of hot streams having an end temperature controller. The optimizer 62 optimizes the heat exchanger network by changing by-pass fraction of at least one heat exchanger located within the heat exchanger network. The optimizer 62 is configured to optimize the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network, wherein the new heat exchanger is added between a plurality of hot streams having an end temperature controller and a plurality of cold streams having an end temperature controller. The optimizer 62 optimizes the heat exchanger network by changing the heat exchange area of at least one heat exchanger located within the heat exchanger network. The optimizer 62 optimizes the heat exchanger network by deleting at least one heat exchanger located within the heat exchanger network. The optimizer 62 is configured to optimize the heat exchanger network by integrating all heat exchange network topologies with prior art RTD. The optimizer 62 optimizes the heat exchanger network by integrating all heat exchange network topologies obtained from FETA with Retrofit Thermodynamic Diagram (RTD), thereby enabling filtering out uneconomical solution just by engineering judgment and also preventing missing of any conspicuous solutions.

The second calculating module 64 is configured to calculate at least the load and driving force value associated with each heat exchanger located within the plurality of heat exchanger network topologies. More specifically, the second calculating module 64 is configured to calculate at least the load and the Exchanger Minimum Approach Temperature (EMAT) associated with each heat exchanger located within the plurality of heat exchanger network topologies. The second calculating module 64 further calculates savings in utility cost, required capital cost of modification and payback period for said plurality of heat exchanger network topologies.
The adjusting module 66 is configured to adjust at least the positioning of at least one heat exchanger located within the plurality of heat exchanger network topologies. The adjusting module 66 is further configured to calculate the load and driving force value, corresponding to each heat exchanger whose positioning has been adjusted. More specifically, the adjusting module 66 is further configured to calculate the load and Exchanger Minimum Approach Temperature (EMAT) corresponding to each of the heat exchangers whose position has been previously adjusted. The adjusting module 66 is further configured to calculate the savings in utility cost, required capital cost of modification and payback period for the heat exchanger network topologies for which position of heat exchanger(s) is adjusted. The adjusting module 66 is further configured to adjust positioning of at least one heat exchanger located within the plurality of heat exchanger network topologies, by replacing one heat exchanger with other heat exchanger.
The selection module 70 is configured to select an optimal heat exchanger topology out of the plurality of heat exchanger network topologies obtained from the optimizer 62 and plurality of heat exchanger network topologies for which position of heat exchangers) is adjusted as obtained from adjusting module 66. The optimal heat exchanger network is selected by comparing savings in utility cost, required capital cost of modification and payback period for each of these heat exchanger network topologies.

The system 100 for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) in accordance with the present embodiment further includes a display module 80, also referred as Graphical User Interface (GUI), configured to display generated representative topology of the heat exchanger network in combination with the corresponding load, Exchanger Minimum Approach Temperature (EMAT), bypass fraction, inlet temperature, outlet temperature etc. associated with each heat exchanger located within the heat exchanger network. The display module is further configured to display selected heat exchanger network topology along with at least the corresponding load, EMAT bypass fraction, inlet temperature, outlet temperature, heat exchange area etc. associated with each heat exchanger located within the selected heat exchanger network topology
The system 100 for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) utilizes FETA and RTD. The overall procedure for using FETA and RTD includes the step of entering the data for existing heat exchanger network in the input sheet, deciding a value for EMAT (Exchanger Minimum Approach Temperature), studying the effect of different values of EMAT to get an economically best solution, running a program to generate a mathematical cum graphical form of FETA along with RTD for the network and graphically displaying the possible combinations of heat exchange network based on and resulting from the possible variations in the heat exchanger network by adding a new exchanger and / or changing the heat exchange area of the heat exchanger and/or bypassing a heat exchanger and/or deleting a heat exchanger and/or by replacing one heat exchanger with another. The user can manually delete any solution or possible variations in the heat exchanger network, if there is any practical constraint such as hydraulic constrains, process control related constraints, field space and configuration constraints or the heat transfer between two streams is forbidden due to safety concerns. Further, the RTD is used to screen out uneconomical solutions simply based on engineering intuition and judgment. Additionally, RTD can be used to study each solution separately and also ensure that no conspicuous solution is missed. For the final selected solutions, the energy saving, required capital expenditure and payback period is calculated to decide the most optimum solution.

The method FETA overcomes the limitations of Path analysis and provides more retrofit solutions without missing optimal solution, while making only limited changes to the Heat Exchangers Network (HEN). The unique integration of the FETA and the RTD combine mathematical analysis with engineering intuition, which produces more practically implementable retrofitting solutions. The methods allow sufficient user interaction, thereby honoring practical and other field constraints. The methods are supported by a graphical user interface which is easy to use and is very flexible. In addition to retrofit problems, the methods can also be applied for grass-root designs, where various preliminary designs can be scrutinized to achieve the optimal final design. The methods can be used for broad range of Heat Exchanger Networks (HENs).
Referring to FIGURE 4 and FIGURE 5 there is shown a computer implemented method for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN). The method, in accordance with the present disclosure includes the following steps:
• receiving at least one input value and operating data corresponding to at least one heat exchanger located within a heat exchanger network 110;
• processing the at least one input value and operating data 120;
• calculating, based on input value and operating data, at least a load and a driving force value associated with at least one heat exchanger located within the heat exchanger network 130;
• storing in a first repository, the load and driving force value associated with at least one heat exchanger located within the heat exchanger network 140;
• generating a representative topology corresponding to the heat exchanger network based on input values and operating data associated with each heat exchanger located within said heat exchanger network 150;

• displaying the representative topology in combination with the load, EMAT, bypass fraction, inlet temperature, outlet temperature etc. associated with at least one heat exchanger located within said heat exchanger network 160;
• inputting the values corresponding to the desired EMAT corresponding to each heat exchanger located within said heat exchanger network 170;
• storing said values corresponding to the desired EMAT in a second repository 180;
• processing said values corresponding to the desired EMAT 190;
• optimizing the heat exchanger network using method of the present disclosure referred as FETA and by integration of FETA with RTD based on said processed values and generating a plurality of heat exchanger network topologies that adhere to the processed values 200;
• calculating at least the load and EMAT associated with each heat exchanger located within said plurality of heat exchanger network topologies; calculating savings in utility cost, required capital cost of modification and payback period for said plurality of heat exchanger network topologies; adjusting the positioning of at least one heat exchanger located within said plurality of heat exchanger network topologies and calculating heat exchanger load, heat exchanger EMAT, the savings in utility cost, required capital cost of modification and payback period for said heat exchanger network topologies for which position of heat exchanger(s) is adjusted 210;
• selecting an optimal heat exchanger topology by comparing savings in utility cost, required capital cost of modification and payback period for said plurality of heat exchanger network topologies obtained from optimization step and plurality of heat exchanger network topologies for which position of heat exchangers) is adjusted 220; and

• displaying the selected heat exchanger network topology along with at least the corresponding load, EMAT, bypass fraction, inlet temperature, outlet temperature etc. associated with each heat exchanger located within the selected heat exchanger network topology 230.
In accordance with the present disclosure, the step of optimizing the heat exchanger network further includes the step of optimizing the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network using method invented in present disclosure referred as FETA.
In accordance with the present disclosure, the step of optimizing the heat exchanger network further includes the step of optimizing the heat exchanger network by changing by-pass fraction of at least one heat exchanger located within the heat exchanger network using method invented in present disclosure referred as FETA.
In accordance with the present disclosure, the step of optimizing the heat exchanger network further includes the step of optimizing the heat exchanger network by changing the heat exchange area of at least one heat exchanger located within the heat exchanger network using method invented in present disclosure referred as FETA. In accordance with the present disclosure, the step of optimizing the heat exchanger network further includes the step of optimizing the heat exchanger network by deleting at least one heat exchanger located within the heat exchanger network using method invented in present disclosure referred as FETA.
In accordance with the present disclosure, the step of optimizing the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network further includes the step of adding at least one new heat exchanger between a hot stream having a cooler and a cold stream having a heater using method invented in present disclosure referred as FETA.
In accordance with the present disclosure, the step of optimizing the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network further includes the step of adding at least one new heat exchanger between a hot

stream having a cooler and a plurality of cold streams having an end temperature controller using method invented in present disclosure referred as FETA.
In accordance with the present disclosure, the step of optimizing the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network further includes the step of adding at least one new heat exchanger between a cold stream having a heater and a plurality of hot streams having an end temperature controller using method invented in present disclosure referred as FETA.
In accordance with the present disclosure, the step of optimizing the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network further includes the step of adding at least one new heat exchanger between a plurality of hot streams having an end temperature controller and a plurality of cold streams having an end temperature controller using method invented in present disclosure referred as FETA.
The step of optimizing the heat exchanger network uses the Feasible Exchange Trajectory Analysis (FETA) referred to as FETA which is a modification and improvement over the concept of Path Analysis known in the prior art. The step of optimizing iurther uses the integration of FETA with known prior art tool Retrofit Thermodynamic Diagram (RTD). The FETA and RTD together synergistically combine mathematical analysis with engineering intuition, which produces more optimal yet practical retrofitting solutions. Further, the integrating of all heat exchange network topologies on Retrofit Thermodynamic Diagram (RTD) enables filtering out uneconomical solution just by engineering judgment and also ensures that no conspicuous solutions are missed.
In accordance with the present disclosure, the step of adjusting the positioning of at least one heat exchanger located within said plurality of heat exchanger network topologies further includes the step of replacing one exchanger with other exchanger within said plurality of heat exchanger network topologies.

In accordance with the present disclosure, the step of inputting desired EMAT further includes the changing desired EMAT value iteratively to get the optimum solution.
In accordance with the present disclosure, the method for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) includes the step of feeding input parameters and operating data corresponding to the existing heat exchanger network, wherein the parameters specify and facilitate generation of a representative topology corresponding to the existing heat exchanger network, the parameters and operating data corresponding to the existing heat exchanger network is fed into a data input sheet. More specifically, the input sheet facilitates presenting the data for existing heat exchanger network. The design of the input sheet is flexible, easy to understand and caters to any level of complexity of the heat exchanger network that includes multiple by-pass or parallel streams. The basic information related to the existing heat exchanger network such as name of the stream, stream type, split fraction, exchanger and utilities, duty, inlet and outlet temperatures are fed into the input sheet.
The foregoing description of the specific embodiments will 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.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE
The computer implemented system for analyzing heat exchanger networks and facilitating modifications thereof has several technical advantages including but not limited to the realization of:
• an economical system and method for analyzing and modifying an existing heat exchanger network;
• a system and method that improves energy efficiency of the existing heat exchanger networks (HEN);
• a system and method that provides heat exchanger network topologies in the form of graphical representations that are easy to understand, analyze and implement;
• a system and method that combine mathematical analysis with engineering intuition, which produces better and more practical retrofitting solutions.
• a system and method that is simple to understand and convenient to implement while considering observed operating constraints of the existing heat exchanger networks (HEN);
• a system and method that caters to heat exchanger networks of varying levels of complexity;
• a system and method that effectively suggests different solutions to issues faced in the heat exchanger network and facilitates the selection of the most efficient and appropriate solution from the suggested solutions; and
• a system and method that reduces utility consumption in a heat exchanger network while making only limited changes to the network.
• a system and method that does not miss the optimum solution in a heat exchanger network retrofit.
• a system and method that can be used for grass-root designs of heat exchanger network in addition to retrofitting.
• a system and method that can be used for heat exchanger network with single phase streams, multiple phase stream and streams with phase change.

• a system and method that can be used for single plant as well as site level energy optimizations.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
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 also 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 specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment 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 thereof

We Claim:
1. A computer implemented system for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN), said system comprising:
• a first receiving module configured to receive at least one input value and operating data corresponding to at least one heat exchanger located within at least one heat exchanger network;
• a first processing module configured to process said at least one input value and operating data, said processing module comprising:
o a first calculator module configured to calculate the values corresponding to at least a load and a driving force value associated with at least one heat exchanger located within said heat exchanger network, based on said at least one input parameter and operating data; and
o a first repository configured to store the values pertaining to the load and the driving force value associated with at least one heat exchanger located within said heat exchanger network;
• a generator module configured to generate a representative topology corresponding to said heat exchanger network associated with each heat exchanger located within said heat exchanger network;
• at least one input module configured to input at least one value corresponding to a predetermined driving force value corresponding to each heat exchanger located within said heat exchanger network;
• a second receiver module configured to receive the values corresponding to the desired driving force value;

• a second repository configured to store said values corresponding to the predetermined driving force value;
• a second processing module configured to process the values corresponding to said predetermined driving force value and generate processed values, said second processing module further comprising:
oan optimizer configured to optimize at least one heat exchanger network based on said processed values to generate a plurality of heat exchanger network topologies that adhere to processed values;
oa second calculating module configured to calculate at least the load and driving force value associated with each heat exchanger located within said plurality of heat exchanger network topologies;
oan adjusting module configured to adjust at least the relative position of at least one heat exchanger with respect to at least one heat exchanger located within said plurality of heat exchanger network topologies, said adjusting module further configured to calculate the load and driving force value, corresponding to each heat exchanger whose positioning has been adjusted; and
• a selection module configured to select an optimal heat exchanger
topology out of said plurality of heat exchanger network topologies
obtained from optimizer and plurality of heat exchanger network
topologies for which position of heat exchanger(s) is adjusted as
obtained from adjusting module, wherein the optimal heat exchanger
network is selected by comparing savings in utility cost, required capital
cost of modification and payback period for each of these heat
exchanger network topologies.

2. The computer implemented system for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) as claimed in claim 1, wherein said first receiving module is configured to receive name of stream, type of the stream - hot or cold, name of heat exchangers, heat exchanger inlet temperature, heat exchanger outlet temperature, exchanger bypass fraction, effective mass specific heat of stream, existing utility loads, utility type, utility cost, details of temperature controllers, interrelation among streams, operating constraints, equipment cost data etc.
3. The computer implemented system for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) as claimed in claim 1, wherein said first calculator module is configured to calculate an Exchanger Minimum Approach Temperature (EMAT) value associated with at least one heat exchanger located within said heat exchanger network.
4. The computer implemented system for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) as claimed in claim 1, wherein said second calculating module further calculates savings in utility cost, required capital cost of modification and payback period for said plurality of heat exchanger network topologies.
5. The computer implemented system for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) as claimed in claim 1, wherein said adjusting module further configured to calculate the savings in utility cost, required capital cost of modification and payback period for said heat exchanger network topologies for which position of heat exchanger(s) is adjusted.
6. The computer implemented system as claimed in claim 1, wherein said optimizer is configured to optimize the heat exchanger network by using Feasible Exchange Trajectory Analysis (FETA) along with "Retrofit Thermodynamic Diagram (RTD)", wherein FETA finds heat exchanger retrofit solutions with limited changes to existing heat exchanger network and does not miss the optimal retrofit

solution and supports a unique graphical cum mathematical form of representation that depicts the information regarding the existing heat exchanger network and facilitates the selection or deletion of any retrofit solution, thereby making the selection of optimized heat exchanger network (HEN) user interactive and enabling the operator to consider the practical constraints of the process heat energy recovery system of which the heat exchanger network is a part of
7. The computer implemented system as claimed in claim 1, wherein said optimizer is configured to optimize the heat exchanger network by integrating all heat exchange network topologies obtained from FETA with and "Retrofit Thermodynamic Diagram (RTD)", wherein FETA and RTD together synergistically combine mathematical analysis with engineering intuition, to produces more optimal yet practical retrofitting solutions.
8. The computer implemented system as claimed in claim 1, wherein said system further includes a Graphical User Interface (GUI) configured to:

• display generated representative topology of the heat exchanger network in combination with the load, EMAT, bypass fraction, inlet temperature, outlet temperature, heat exchange area etc. associated with each heat exchanger located within said heat exchanger network;
• display the selected heat exchanger network topology along with at least the corresponding load, EMAT bypass fraction, inlet temperature, outlet temperature, heat exchange area etc. associated with each heat exchanger located within the selected heat exchanger network topology.
9. The computer implemented system as claimed in claim 1, wherein said optimizer
is configured to optimize the heat exchanger network by adding at least one new
heat exchanger into the heat exchanger network.

10. The computer implemented system as claimed in claim 1, wherein said optimizer is configured to optimize the heat exchanger network by changing by-pass fraction of at least one heat exchanger located within the heat exchanger network.
11. The computer implemented system as claimed in claim 1, wherein said optimizer is configured to optimize the heat exchanger network by deleting at least one heat exchanger located within the heat exchanger network using Feasible Exchange Trajectory Analysis (FETA).
12. The computer implemented system as claimed in claim 1, wherein said optimizer is configured to optimize the heat exchanger network by changing the heat exchange area of at least one heat exchanger located within the heat exchanger network using Feasible Exchange Trajectory Analysis (FETA).
13. The computer implemented system as claimed in claim 9, wherein said optimizer is configured to optimize the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network, wherein said new heat exchanger is added between a hot stream having a cooler and a cold stream having a heater.
14. The computer implemented system as claimed in claim 9, wherein said optimizer is configured to optimize the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network, wherein said new heat exchanger is added between a hot stream having a cooler and a plurality of cold streams having an end temperature controller.
15.The computer implemented system as claimed in claim 9, wherein said optimizer is configured to optimize the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network, wherein said new heat exchanger is added between a cold stream having a heater and a plurality of hot streams having an end temperature controller.
16. The computer implemented system as claimed in claim 9, wherein said optimizer is configured to optimize the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network, wherein said new heat exchanger

is added between a plurality of hot streams having an end temperature controller and a plurality of cold streams having an end temperature controller.
17. The computer Implemented system as claimed in claim 1, wherein said adjusting module is configured to adjust positioning of at least one heat exchanger located within said plurality of heat exchanger network topologies, by replacing said exchanger with another exchanger.
18. The computer implemented system as claimed in claim 3, wherein said optimizer is configured to optimize the heat exchanger network by integrating all heat exchange network topologies obtained from FETA with Retrofit Thermodynamic Diagram (RTD), thereby enabling filtering out uneconomical solution just by engineering judgment and also preventing missing of any conspicuous solutions.
19. A computer implemented method for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN), said method comprising the following steps:

• receiving at least one input value and operating data corresponding to at least one heat exchanger located within at least one heat exchanger network;
• processing said at least one input value and operating data;
• calculating, based on said input value and operating data, at least a load and a driving force value associated with at least one heat exchanger located within said heat exchanger network;
• storing in a first repository, said load and driving force value associated with at least one heat exchanger located within said heat exchanger network;
• generating a representative topology corresponding to said heat exchanger network associated with each heat exchanger located within said heat exchanger network;

• displaying said representative topology in combination with the load, EMAT, bypass fraction, inlet temperature, outlet temperature, heat transfer area etc. associated with at least one heat exchanger located within said heat exchanger network;
• inputting the values corresponding to the desired predetermined driving force value corresponding to each heat exchanger located within said heat exchanger network;
• storing said values corresponding to the predetermined driving force value in a second repository;
• processing said values corresponding to the predetermined driving force value and generate processed values;
• optimizing said at least one heat exchanger network based on said processed values and generating a plurality of heat exchanger networks that adhere to processed values;
• calculating at least the load and driving force value associated with each heat exchanger located within said plurality of heat exchanger network topologies;
• adjusting the positioning of at least one heat exchanger located within said plurality of heat exchanger network topologies and calculating heat exchanger load and driving force within the said heat exchanger network topologies for which position of heat exchanger(s) is adjusted.
• selecting an optimal heat exchanger topology by comparing savings in utility cost, required capital cost of modification and payback period for said plurality of heat exchanger network topologies obtained from optimization step and plurality of heat exchanger network topologies for which position of heat exchanger(s) is adjusted ; and

• displaying the selected heat exchanger network topology along with at least the corresponding load, EMAT, bypass fraction, inlet temperature, outlet temperature, heat transfer area etc. associated with each heat exchanger located within the selected heat exchanger network topology.
20. A computer implemented method for analyzing heat exchanger networks and facilitating selection of optimized heat exchanger network (HEN) as claimed in claim 19 further comprising the step of calculating savings in utility cost, required capital cost of modification and payback period for said plurality of heat exchanger network topologies obtained from optimization step and plurality of heat exchanger network topologies for which position of heat exchanger(s) is adjusted;
21. The computer implemented method as claimed in claim 19, wherein the step of optimizing the heat exchanger network uses the Feasible Exchange Trajectory Analysis (FETA).
22. The computer implemented method as claimed in claim 19, wherein the step of optimizing the heat exchanger network further uses the integration of FETA with Retrofit Thermodynamic Diagram (RTD).
23. The computer implemented method as claimed in claim 19, wherein the step of optimizing the heat exchanger network further includes the step of optimizing the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network using the Feasible Exchange Trajectory Analysis (FETA).
24. The computer implemented method as claimed in claim 19, wherein the step of optimizing the heat exchanger network further includes the step of optimizing the heat exchanger network by changing by-pass fraction of at least one heat exchanger located within the heat exchanger network using Feasible Exchange Trajectory Analysis (FETA).

25.The computer implemented method as claimed in claim 19, wherein the step of optimizing the heat exchanger network further includes the step of optimizing the heat exchanger network by deleting at least one heat exchanger located within the heat exchanger network using Feasible Exchange Trajectory Analysis (FETA).
26. The computer implemented method as claimed in claim 23, wherein the step of optimizing the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network further comprises the step of adding at least one new heat exchanger between a hot stream having a cooler and a cold stream having a heater.
27. The computer implemented method as claimed in claim 23, wherein the step of optimizing the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network further includes the step of adding at least one new heat exchanger between a hot stream having a cooler and a plurality of cold streams having an end temperature controller.
28. The computer implemented method as claimed in claim 23, wherein the step of optimizing the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network further includes the step of adding at least one new heat exchanger between a cold stream having a heater and a plurality of hot streams having an end temperature controller.
29. The computer implemented method as claimed in claim 23, wherein the step of optimizing the heat exchanger network by adding at least one new heat exchanger into the heat exchanger network further includes the step of adding at least one new heat exchanger between a plurality of hot streams having an end temperature controller and a plurality of cold streams having an end temperature controller.
30. The computer implemented method as claimed in claim 19, wherein the step of optimizing the heat exchanger network further comprises integrating all heat exchange network topologies on Retrofit Thermodynamic Diagram (RTD) which enables filtering out uneconomical solution just by engineering judgment and also ensures that no conspicuous solutions are missed.

31. The computer implemented method as claimed in claim 19, wherein the step of adjusting the positioning of at least one heat exchanger located within said plurality of heat exchanger network topologies further includes the step of replacing at least one heat exchanger with another heat exchanger located within said plurality of heat exchanger network topologies.
32. The computer implemented system as claimed in claim 1 and the computer implemented method as claimed in claim 19 can also be applied for grass-root designs in addition to retrofit design, where various preliminary designs can be scrutinized to achieve the optimal final design applicable for grass-root designs in addition to retrofit design.
33.The computer implemented system as claimed in claim 1 and the computer implemented method as claimed in claim 19 are applicable for single phase flow, multiple phase flow and flow with phase changes.
34. The computer implemented system as claimed in claim 1 and the computer implemented method as claimed in claim 19 are applicable for single plant as well as site level utility and energy optimization.