Guidelines and requirements for report number three.
The details of the design are beginning to be worked out. The task over the next two
weeks is to continue research all the options for the various steps in the process –
especially in the ethanol group - begin to assemble a rough process flow diagram, and
begin to look into environmental issues. The following outlines some of the questions
that need to be addressed in the design.
Requirements for both groups:
The red liquor composition and approximate flow rate needs to be well-established.
Typical compositions of softwood red liquors produced by a magnesium acid sulfite
pulping can be found in the literature. This composition can then be modified -improved -- by comparing the composition of hemlock (species used at Cosmopolis)
and the composition of the species in the literature report. For report #3, we want the
groups to settle on a red liquor flow and composition. This will serve as the design
basis for both groups.
The second requirement for both groups is to develop a rudimentary process flow
diagram. This will show the flows, compositions, temperatures, and pressures of all the
major streams. It will also show the reaction conditions. Highlight those parts of the
process where you need more information on and those you are uncertain about. We
will use this flow diagram to develop a rough capital and operating cost estimate so it
needs to reasonably complete.
Finally, we would like to have both groups begin to look into air and water quality issues
for the biorefineries. Air permits will be the biggest issue, so please start there.
Consider what air emissions that your design will have and look into the state and
federal regulations for those emissions.
Ethanol production group:
1. Fermentation process Several items were brought up in our discussion last
week regarding fermentation organisms and fermenters. Basically we want to
make sure you have covered the literature well and present viable options to the
class. Choosing one organism or one reactor configuration is insufficient.
2. Ethanol recovery. This was covered reasonably well except for a few minor
questions.
3. Sludge to ethanol. This needs to be developed much more. You can think of
sludge as being pretreated biomass. As such, it is ready for hydrolysis and
fermentation. Look at the NREL report on how they made ethanol following the
pretreatment step. The questions here are if hydrolysis and fermentation should
be done separately or together, and how will the sludge process be integrated
into the red liquor process; you could go everywhere from directly adding the
sludge to the red liquor to only combining the final ethanol products. We would
like to see some integration options and the pros and cons of each.
Glycol production group:
1. Separation of lignin from sugars. This was covered very well. The challenge
will be to find reasonable operating and cost data for the two separation
methods. At some point we will need to make a choice.
2. Production of sugar alcohols and glycols. The reactor designs are coming
together thanks in part to John Orth. More details are coming from John so we
can begin to make decisions on catalyst, reactor type and reactor conditions.
Potential impurities in the reactor feed streams still needs to be addressed. How
clean does the feed stream need to be?
3. Separation of products. The separation of the products will be done by
distillation. The details of the distillation trains need to be worked out. One
member of your group needs to develop some expertise on distillation. New
material from John Orth may help with the distillation train design.
4. Sources of hydrogen. A number of process options were raised. At this point I
would recommend trying to narrow that done either on the basis of economics
(could be very rough) or environmental considerations. In the end we will develop
the design with one option but I think you could do a preliminary analysis of 4 – 6
options.
For Wednesday 23 February we will want a written and oral report that addresses the
issues raised above. We are still looking for a clear presentation of the different
process options, the pros and cons of each, and something about how you are going to
make a decision on which to adopt. In addition, we want to see a preliminary process
flow diagram and discussion on air emissions. We will also want to see (as we do every
with report) updated timeline and milestones; which will be updated on the 23rd to map
out the rest of the quarter.
If you have questions please contact me or Dr. McKean.