Charles,
As I understand it, the new pumps are "centrifigal pumps" manufactured with more temperature resistant metal in the housings. As Paul explained it to several months ago, the temperature range of the final fuel product created a possibility of expansion in the metal pump housings which would reduce efficiencies and could increase wear on the pump bearings. That is, if I understood him correctly.
Anyhoo, the new pumps were a "nice to have" option that will lessen the possibility of having to do a "hot swap" of primary pumping units every year or so. The intention seems to be to make the Charleston unit as advanced and maintenance free as possible in order to attract customers who may not have a logistic infrastructure such as we possess here in the US. ie... Idiot proofing...:0)
The stirring system has been in the works since June and as I last understood it, is being installed by a local Charleston company. The process here is that GRNO will utilize several 20,000 gallons feedstock tanks, alternating between each one as the primary feedstock tank.
Real quickly, this is how I understand the scenario. A load of feedstock arrives at GRNO LP #1 "Green Machine" and is pumped into Tank "A" (assuming Tank "B" is now the primary feedstock tank) and allowed to sit for 24 hours to allow for stratification of waters, anti-freeze(which are then drained into collection/"slop" tanks), and the results of the analysis of the waste oil. It is then "stirred" using a straightforward mixing blade (propeller? you pick the euphemism... :0) Now assuming that Tank B is empty (roughly 825 gph x 24 hours), Tank "A" becomes the primary feedstock tank and we begin the cycle once again. (Tank "B" also has a stirring system)
Given the vagaries of feedstock quality in less developed parts of the world, it is imperative to incorporate stirring/blending mechanisms in those processors to insure proper consistency of feedstock, avoiding "burps" in the process as lighter or heavier feedstock is drawn into the T-1 cracking vessel. Lighter feedstocks (including diesel that may be entrained or comingled in the feedstock) can cause increases in stack temperatures as less heat it required to vaporize and redistill as #2 fuel. This, in turn, requires the automated process system to alter operating parameters (decreasing the amount of exhaust heat passing through the HRU-heat exchanger). The reverse would occur as heavier feedstocks hit the system, requiring more heat to pass into the HRU.)
Basically, as I understand it, the Automated Control System can handle switching process parameters to a large degree, but why stress the system, dampers, pumps, and other parts if you don't have to.
They system worked before, but with these new components, it will be more efficient and require less maintenance. It level of redundancy on major components and redundant monitoring and safety controls should enhance its appeal to customers not having access to Phds in Chemical/Process engineering... :0) Each pump is redundant as well as major sensors/thermocouples facilitating replacement "on the fly" with no disruption of operation.
Hope this answer Suzy-Q's question.
Take care.
Regards,
Ron |
