The Process module is used to conduct a Pinch Analysis of a single processing unit. Any process stream in this unit can directly exchange heat with any other process stream in this same unit, subject only to thermodynamic feasibility.

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Process uses the LinnView application framework that has been developed by Linnhoff March specifically for complex engineering tasks. This includes a multiple document interface, flexible units of measure, a comprehensive online manual, context sensitive help, and guidance wizards. High levels of automation minimise the time taken for data entry and heat exchanger network design.

Data entry methods

The following data entry methods are available in Process:

	Interfaces to process simulators
	An intelligent data extraction system (see below) is used to convert simulator data into the Pinch data required by Process. This can now be initiated directly from within some process simulators.
	Heat exchanger summary table
	In this method the user types in some simple data describing the heat exchangers in the existing design or the existing plant. Process then derives the stream data, utility data and heat exchanger network from this input.
	Intelligent data extraction
	Both the methods described above require an intelligent system to turn process data into the data needed by a Pinch study. This system is provided by the Process module. The data extraction can either be automatic or the user can have some involvement. One of the key features of the system is that it extracts the existing heat exchanger network, as well as the stream data. This gives a good check on the stream data and highlights the inefficiencies in the existing design.
	Manual data entry and modification
	In this method the user types stream data and utility data directly into a spreadsheet editor. The heat exchanger network is then entered interactively, by clicking the mouse on the Grid Diagram. These methods can be used from scratch but are most useful for modifying data that has been initialised by a different method, such as importing data from a process simulator.

Targeting

Targeting provides a fundamental insight into the heat recovery options in a process. It does this by giving a system-wide view of the heating and cooling requirements at different temperature levels. Process allows you to do the following targeting tasks:

	Calculate the maximum heat recovery possible in the process
	Estimate the utility and capital cost at a given heat recovery
	Explore the capital/energy trade-off for both new design and retrofit projects
	See all these results graphically, using the composite curves, grand composite curve and numerous other plots
	Look for process modifications to improve the scope for heat recovery
	Use the targeting to set the basis for designing the heat exchanger network
	Calculate energy loss at a given heat recovery

Heat exchanger network (HEN) design

In the design view the user will typically be working with an incomplete network and trying to follow the pinch design rules. This means that it must be possible to place a match anywhere on a stream; for example, at the pinch. To do this the user must specify or select three match variables; for example, the two inlet temperatures and one outlet temperature. Process can then calculate the match duty, area, number of shells and so on.

Process provides the following design features:

	Compare the existing design against an established base case determined during targeting or taken from an existing design
	Retrofit a design to achieve the targets by identifying what causes the HEN network to exceed the targets and modifying just those parts
	Construct a new design from scratch using the pinch design rules
	Automatic new design for the HEN or just a selected sub-section
	Semi-automatic HEN retrofit for refinery and petrochemical processes

In the simulation view the situation is different from design because it is now assumed that there are no holes in the network. This means that the inlet temperature to the first exchanger on a stream is the stream source temperature. Thereafter, the inlet temperature to an exchanger is taken to be the outlet temperature of its upstream neighbour. Typically this will mean that the user is simulating an existing network or a completed design.

Process provides the following simulation features:

	Test the behaviour of a network under process disturbances. For example, you can evaluate the effect on the network temperatures if a stream source temperature is increased by 1° C or if an exchanger is taken out of service
	Evolve a completed network by "relaxation". This usually means allowing some cross-pinch heat transfer in order to remove some small exchangers
	Optimise a completed network automatically. This means optimising the match sizes to minimise the total cost (energy + capital). This feature does not change the structure of the network, only the size of the matches
	Calculate the adjustments needed to bring selected temperatures back to specified control points. These adjustments will either be a by-pass around some exchangers or additional area on some exchangers (or a mixture of these two). After calculation you can accept the result and modify the network permanently

All these features can be controlled and displayed from the interactive network grid diagram, described in the previous section

	Heat Exchanger Summary Table
	In this method the user types in some simple data describing the heat exchangers in the existing design or the existing plant. Process then derives the stream data, utility data and heat exchanger network from this input.
	Intelligent Data Extraction
	Both the methods described above require an intelligent system to turn process data into the data needed by a Pinch study. This system is provided by the Process module. The data extraction can either be automatic or the user can have some involvement. One of the key features of the system is that it extracts the existing heat exchanger network, as well as the stream data. This gives a good check on the stream data and highlights the inefficiencies in the existing design.
	Manual data entry and modification
	In this method the user types stream data and utility data directly into a spreadsheet editor. The heat exchanger network is then entered interactively, by clicking the mouse on the grid diagram. These methods can be used from scratch but are most useful for modifying data that has been initialised by a different method, such as importing data from a process simulator.