Monitor™ economic calculations answer common questions about the cost of fouling, the benefits to be gained from cleaning and help to develop an optimum cleaning strategy.
Cleaning Economics Reports
In addition, one of the standard spreadsheet reports is the Fouling Cost Summary which shows the additional costs that have been incurred over a range of cases for the furnace to make up the duty lost.
Economic Data Required
The Cleaning Economic calculations require the following data:
For each exchanger:
How Cleaning Economics are Calculated
Fouling factors are first calculated for a selected Case. These are used to calculate temperatures for all exchangers and at the furnace inlet.
Cost of removing exchangers for cleaning
The Network is solved and the furnace run-up temperature calculated with each exchanger in turn bypassed. This determines the effect of removing the exchangers for cleaning in terms of lost enthalpy at the furnace inlet, also expressed as $/day. The program also calculates the amount by which the throughput would have to be reduced in order to maintain the furnace inlet temperature at its previous level.
Savings from cleaning
The fouling factor of each exchanger in turn is then set to its clean value and the Network is solved to obtain the increase in duty that this would produce at the furnace inlet. This is shown as extra throughput which could be achieved and $/day.
Optimum cleaning cycles
The above results are then used, along with fixed costs, to calculate the optimum cleaning cycles for each exchanger. The optimum cycle is that which minimises the annualised cost of fouling. By default, each exchanger is cleaned in turn. Combinations of exchangers to be cleaned in addition to individual exchangers are defined in the User Defined Cleaning Economics Combinations Window.
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