Minnesota Ethanol Plant Finds Unexpected $60/day Savings by Reusing Their Caustic
Ask Filter Man
self-cleaning filter on their caustic based CIP (clean in place)
system.
Due to an increase in production, the customer saw soaring caustic
usage costs.
To make matters worse, in late 2005 caustic costs had increased 60 -
70% over what they were when the system was installed.
Clearly, the customer had to find a way to reuse the caustic to bring
their costs down to a manageable level.
Ethanol process:
As part of the ethanol production process, water, enzymes and corn are
cooked and then combined in large fermentation tanks.
When the fermentation part of the process is complete, these tanks are
pumped out to the distillation system to separate the ethanol from the
stillage, or by-product.
Because ethanol plants typically have many fermentation tanks the
process is essentially continuous. The systems are optimized so that
one tank is offline for cleaning every 1 - 4 hours. This allows the
other tanks to be cleaned at some point along in the fermentation
process.
This clean up is extremely important as it must take place in a very
short time period -- typically less than one hour.
It also must be done very efficiently to ensure a clean tank prior to
refilling. If this is not done in the proper manner, costs escalate and
product quality/safety are compromised.
Important: once contamination occurs, it is then necessary to stop the
production line to determine where the infraction has occurred.
Situation:
To begin, the actual cleaning up of a fermentation tank is a three step
process.
1. The tank is first drained prior to flushing. After the initial
flushing, a drain is opened to allow the bulk of the solids to exit the
tank.
2. The drain is then closed, and the wash water is recycled to
completely flush the fermentation tank.
3. The final step is to flush the entire tank out with a 6-10%
caustic stream to remove any leftover spent corn particles.
As the corn particles are collected in the caustic stream, they absorb
a portion of the caustic so it becomes necessary for the ethanol plant
to continuously monitor the strength of the caustic.
Periodically, caustic is added through a caustic control valve to
maintain peak cleaning efficiency.
Unfortunately, the spent particles in the system increased in
proportions relative to the Ethanol plant's production increased.
As the plant increased production, the consumption of the caustic was
not accounted for, making the caustic addition rates fluctuate widely.
This resulted in additional costs without necessarily benefiting the
cleaning.
Ronningen-Petter Solution:
The Ethanol plant installed a Ronningen-Petter DCF-1600 Twin
Self-Cleaning Industrial Filter on a recirculation loop off of the
caustic make-down tank.
Note: the filter could also have been sized to take the full flow from
the make-down tank prior to the fermentation tanks if necessary.
The DCF filter was designed to run continuously, while the caustic
solution was used intermittently when the fermentation tanks were
flushed. Temperatures were typically in the 180° F range.
Interestingly, this particular Ethanol application can see high amounts
of solids depending on the flushing loop and human error.
The filter was able to handle the spikes of solids seen shortly after
start-up of the caustic rinse loop, and was able to make it through
upset conditions caused by improper valve sequencing.
Results:
Within the first week after the installation of the DCF-1600 Twin
Self-Cleaning filter, caustic usage was stabilized and immediate
savings were realized.
After the first 60-days of operation the customer saw an average
savings of $ 60.00 per day.
-- by Ask Filter Man
For questions about industrial filtration, please visit the Ask Filter
Man forum at http://www.rpaprocess.com/Ask-Filter-Man-Blog.asp.
If you would like to discuss this filtration solution with one of our
highly trained Applications Specialists, please Contact Us at
http://www.rpaprocess.com/ContactUs/Contact-Us.asp.
If you would like to read more published real-world documented case
studies about how our industrial filters have helped customers improve
their bottom line, please visit the Where in the World is Ask Filter
Man forum at
http://www.rpaprocess.com/Where-In-The-World-Is-Ask-Filter-Man.asp.