4 replies to this topic

[Ali_gholamalian]

Dear all

I'm using Krohne Flow Meters to get flow rate and density of fresh acid and ADA(*). The indicated flows are seem OK to me, but when I want to calculate acid consumption by below equation, mostly it's negative. (I use daily average flows from DCS for this mean)
(*) ADA = Alkylation Discard Acid

Fresh Acid flow (kg/day) * Fresh acid strength (wt%) - ADA flow (kg/day) * ADA strength (wt%)= Acid Consumption (kg/day)

Recently I found an equation in DuPont STRATCO documents, but I don't know how they found this equation.
The equation is : Stage Consumption (lb acid /gal alkylate) = 331.613 - 7.03413*A + 0.037349*A² ; where A is acid strength in each stage (in this document, they had 3 stages), and at last average of stages consumption is an estimate of unit acid consumption.

P.S: I have 2 stages (Propen Side and Butene Side) in my unit.
P.S.S: How Krohne Flow Meters calculate density?

I really appreciate any answer.

[breizh]

Ali,

A mass balance should tell you the consumption , don't take for granted document from others , you need to know the context.

for the post scriptum 2, let us know your technology : Coriolys type ?
PS: You should consider Google to support your query .

hope this helps you .

Breizh

Edited by breizh, 28 October 2012 - 07:42 PM.

[Ali_gholamalian]

Ali,

A mass balance should tell you the consumption , don't take for granted document from others , you need to know the context.

for the post scriptum 2, let us know your technology : Coriolys type ?
PS: You should consider Google to support your query .

hope this helps you .

Breizh

Dear Breizh

First of all, I would like to thank you for your help.

These flowmeters are electromagnetic type "http://krohne.com/en...ow-measurement/"
We're using three of these for inlet acid (*) and one for spent acid. Based on unit data, inlet meters doing well; but I'm not trusting in outlet flowmeter.
Fresh acid flow is continuous but spent acid is not. So I used average daily report and it doesn't work neither average monthly report .

*: One flowmeter for overall inlet acid (5000 kg/h), and one for each reactor (~2500 kg/h).
P.S: Based on unit data, I assumed that outlet flow is correct, so I changed laboratory result for acid strength. It must be 85% not 92% and it's impossible, because excessive corrosion will happen and the effects are visible in production and also in "Fe Content" results.

[Ali_gholamalian]

Dear Breizh

I checked the meters type again, and I realized those are mass type not electromagnetic.
Now is there any way to become sure about meters accuracy?
here's the link of Flowmeter http://krohne.com/en.../optimass-7000/

[breizh]

Ali,
Normally those equipment are accurate and supplied with a calibration certificate . Check when was the last calibration of the equipment and consider to perform it again in house or with a 3rd party .

Breizh

Edited by breizh, 08 November 2012 - 07:40 PM.