tip Calculating Boiling/Distillation Percentage of a Stream for a given Temperature based on Lab Samples using the Splice Operator

[Patrick]

In some processes our users want to calculate how much of a product stream will boil based on a stream temperature and laboratory distillation tests, such as ASTM D86, which quantify at what temperature a certain percentage of a fluid will boil.

This can be achieved in Seeq using the splice operator.  We will calculate the percentage of range between the lab samples for any given stream temperature, and splice in that value based on where the stream temperature falls in the respective range. 

Following is a simplified example for 5 lab signals at 0%, 25%, 50%, 75%, and 100% boiling points – it can be expanded for more percentages by adjusting the range offsets.  

In the below formula, we take the five lab signals and calculate where the stream temperature falls within each range, expressed as a percentage:

Formula text for copy/pasting:

//Splice in the value for each range
//Adjust the range offsets (0, .25, .50, etc) to reflect the number of lab signals
0.splice(0+($temp-$_0p)/($_25p-$_0p)*.25,$temp>$_0p)
.splice(.25+($temp-$_25p)/($_50p-$_25p)*.25,$temp>$_25p)
.splice(.50+($temp-$_50p)/($_75p-$_50p)*.25,$temp>$_50p)
.splice(.75+($temp-$_75p)/($_100p-$_75p)*.25,$temp>$_75p)
.splice(1,$temp>$_100p)
 
//Optionally show as integer %
.convertUnits('%')

The resulting signal will be a representation of the boil % of the stream for a given stream temperature:

Edited June 4 by Patrick