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Monitor is a trademark of Nalco Company, Naperville, Illinois, U.S.A.

Features

 

This page summarises the features of the Monitor computer program. To read more about any feature, click on the More detail link.

Graphical PFD drawing

As with any simulation program,all Monitor operations work from a drawing of the Process Flow Diagram (PFD) which displays the units in the Network and the streams that connect them. The PFD is created graphically using point and click, drag and drop. It is visible at all times and data can be entered and results examined by right clicking on a unit or stream.

Flexible Input Data

Data are entered in data entry windows or in bulk from a spreadsheet.  Data are subject to rigorous checking for realism and consistency. Obvious errors such as negative pressures are not allowed. Warnings are issued for data items that appear to be unreasonable for example, too few baffles, too tight tube spacing. Data may be entered in a wide range of dimensional units.

Different types of  fluid

Monitor property calcualtins handle several types of fluid:

  • Single Phase Hydrocarbon

  • Assay Stream with or without Lightend components

  • Defined Composition, Water and/or Steam

Rigorous thermodynamics

Monitor thermodynamic methods simulate fluid behaviour rigorously.  

Flash calculations predict the separation of a two-phase fluid into liquid and vapour and include handling of water as a separate phase.

Data reconciliation

A powerful Monitor feature is its ability to identify inconsistencies in input data and produce a consistent set of data for the fouling calculation. Data reconciliation minimizes errors between hot and cold side exchanger duties by adjusting given variables. At the same time, it minimizes the difference between calculated and target exit temperatures for mixers.

Fouling Calculations

The reconciled data are used to calculate actual and clean heat transfer coefficients. These "U" values are then used to calculate fouling factors. 

Results normalisation

An important Monitor strength lies in its ability to identify trends that are due only to changing fouling resistances and not caused by other factors, such as changing crudes and product slates and varying ambient conditions which all conspire to mask the real trends.

Economic analysis

The Monitor range of economic calculations answers common questions about the cost of fouling, the benefits to be gained from cleaning and help to develop an optimum cleaning strategy. Calculations  include: cost of removing exchangers for cleaning; savings to be made by cleaning selected exchangers; and optimum cleaning cycles for each exchanger and for groups of exchangers.

Optimize splitter ratios

Monitor splitter optimisation determines the splitter product ratios required to  maximise the heat recovery of a Network: when the  enthalpy of the furnace inlet stream(s) is a maximum. 

This, in effect, minimises the required furnace duty for the Network.

Database storage

Monitor input data and results are maintained in a database used for generating reports and plotting fouling trends over time.

There is no limit on the number of cases that can be held in a Monitor database.

 

Plant data import 

Process data can be imported directly from a spreadsheet. Plant information systems can transfer data into a Monitor model day by day via a spreadsheet. Instrument tags are used to identify process parameters and allocate values. Typically tags are assigned to the exit temperatures on each exchanger, stream flow rates and temperatures and splitter ratios or rates.

Flexible output

Monitor case results are exported to an Excel spreadsheet which automatically plots the temperatures, flows, U-values and fouling resistances, along with other important diagnostic parameters such as tube and shell velocities.

Automated running

At the single click of a mouse, this Monitor faclity will import Case data, perform Network calculations and generate spreadsheet output for all your networks in one operation - you do not have to select the networks separately.