5 replies to this topic

[CHEMSTRONG]

Dear Sir,

 

I wish to develop empirical correlation using hysys. i ahve 6 months data for the plant for dependent and independent variables . i want to develop empirical correlation using hysys.

[PaoloPemi]

can you provide some additiona detail ?

If it is for purposes of control maybe a DCS can offer some language or a predefined procedure (data regression analysis etc.)

[CHEMSTRONG]

Dear Sir,

 

I have 6 months data for compressor like k value( CP/ Cv ratio) vs Mol wt of compressor inlet stream .on other side, I also have compressor mol wt , flow , suction pressure and zompressibility factor data for 6 months, I want to develop empirical correlation for evaluating polytropic efficiency of compressor machine here. how can I relate diff varibales in one equation using simulator or a excel 

 

Thanks.

 

Best Regards,

Chetan Chavan 

[PaoloPemi]

which kind of empirical model ?

properties as cp/cv are, in most cases, are calculated (or estimated), not measured, also you do not mention compositions, which is probably the most important thing when working with simulators,

could it be you have data calculated with some software ?

If that is true ,  you could utilize a tool as Excel for data analysis / regression,

for additional details you should provide more information...

[CHEMSTRONG]

Dear Sir,

 

My case:

I have Ethylene compressor Cracked Gas Compressor (CGC) for which there is a wash water and wash oil addition happens at the dishcrage of compressor. Normally polytropic efficiency is calculated as a fucntion of k value(CP/CV) , Temp ratio and Pressure Ratio and also . but if we want to calculate wash water flow impact on efficiency, then we need to have delta T term in denominator of this efficiency equation. So I want to evaluate this delta T using empirical data here. Delta T can be function of wash water flow, mol wt and compressor flow etc. How to fit all this in one empirical equation.

 

Regards,

Chetan Chavan 

[PaoloPemi]

I am not sure to understand the point, if you add or subtract heat (for example from water evaporation) after compression cycle that doen;t impact compressor efficiency, compressor efficiency is determined on the basis of temperatures at compressor inlet / outlet, 

in the same way, if you include, for example a intercooler after frist stage, that doesn't impact efficiency of first stage,

differently, if you add water (or oil or ...) at compressor inlet that can modify temperatures,

but some compressor models (for example the polytropic model with phase equilibria in Prode Properties) keep in account phase equilibria, if that is what you are looking for.... unfortunately the efficiency calculated including some evaporating liquid cannot be easily compared with that of vapor phase only. If you wish to estimate the impact of some chemical mitigation technique or monitor compressor performance for different  wash-water or wash-oil injection rates you can define some specific, arbitrary function.

Edited by PaoloPemi, 02 July 2020 - 01:23 PM.