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Re: level of effort for mass balance?



Given Burt's added detail, I can offer the following:

Over a little more than 600 assessments, ranging from simple targeting
assessments (just find what's worth working on) to detailed opportunity
assessments (not just what is going on, but why, and can anything be
changed) we have averaged 40 hrs per major unit operation. A major unit
operation is one that incurs at least 10% of the product's total production
cost or adds at least 10% of the product's value. Time will be saved when
good info is available (more than just purchase costs) and when working on
unit ops that employees know well (as opposed to ones they just operate).

Time tends to go up for unit ops that are complex (variable; high number of
steps), but 40 hrs has worked well for us for initial bidding purposes and
project development.  BTW, this is more than a materials account.  Included
are what, how, when, and why, which might be a bit more than needed for your
stated purpose, but sure comes in handy when you start looking at
alternatives.

  
--Terry Foecke
Managing Partner
Materials Productivity LLC
6701 Penn Avenue South, Suite 200
Richfield, MN  55423
(p) 612-243-3605
(f) 612-243-3608 


> From: "Burt Hamner" <bhamner@cleanerproduction.com>
> Reply-To: "Burt Hamner" <bhamner@cleanerproduction.com>
> Date: Wed, 8 Jan 2003 12:39:38 -0500
> To: "p2tech" <p2tech@great-lakes.net>
> Subject: level of effort for mass balance?
> 
> I have been asked by person in the environmental agency here to provide
> estimates about what level of effort is needed to do a mass balance for a
> company.  They are considering making a mass balance analysis a requirement
> for a particular environ regulation.
> 
> Obviously this depends on the number of processes being considered.  I have
> not done process mass balances for several years, not being an engineer, and
> would appreciate any insights.  Here are my basic estimates for a "typical"
> production process.  I am making these pretty generous.  Also I am assuming
> there is some data around already.
> 
> Preparation of process flow diagram:  3 hours
> 
> Collection of input-output data for each step:  1 hour per step in the
> process
> 
> If we estimate that a process has about 5 major steps, this would be 5 hours
> 
> Preparation of the mass balance for key factors:  2 hours
> 
> So roughly I would estimate for a "generic" company, that it would take an
> engineer about a day to prepare a mass balance for one production process.
> Another day to summarize results from all the processes, and maybe another
> day to work out the bugs.
> 
> I realize this is grossly simplified and the world is much more complex.  If
> any of you hotshot engineers can comment on these estimates I will be
> grateful, and also I think the regulators will be interested to know your
> ideas too since mass balance for processes is pretty basic for most P2
> analyses.
> 
> and Happy New Year to all!
> 
> Burt Hamner
> Univ de Pacifico
> 
> 
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