Thanks Doug. I was imagining the challenge of trying to start the two engines including the gas distribution but had not given the harmonics a thought at all. Good point. Really where I am coming from is to have a common generator. The challenge of getting two generators to run in sync is fine on the MW level but a huge challenge down at small scale. As it is, speed control is already somewhat of an art as the speed is a function of load on the generator and a change in speed has an effect on the load of the gasifier where the gas CV changes until the new equilibrium is established. Just not as simple as adjusting the throttle as one would with petrol/diesel.
The clutch you mention: I am assuming that you would put a stripped down gearbox on the end of the motor and use a normal car clutch. If there is a simpler method, I would most welcome it. We frequently want to be able to offer a system that can both drive a generator or a mechanical devices such as a maize mill. A belt drive clutch would allow us to choose run the generator all the time and to pull in the maize mill when required. Do you know of any system that has this? Possibly I could look at an electric clutch similar to that used with air conditioners. Any advice would be appreciated. Kind regards Rex Zietsman Principal Consultant -----Original Message----- From: Doug Williams [mailto:[email protected]] Sent: 01 April 2015 11:17 PM To: Discussion of biomass pyrolysis and gasification Cc: Rex Zietsman; [email protected] Subject: Re: [Gasification] Two Engines One Gasifier Hi Rex, The Multi engine project was done without my input except after the fact! They could start one but it ended there, plus the concept was flawed due to how the engines were connected to the central shaft. What they did not resolve was how to couple the generator and keep the two separate assembles in line. The other main factor that worked against the engines all mounted on the same skid, was that the engine harmonics would have begun to destroy the fabrication of the structure. I had long talks with Marine engineers about this after the multi engine inventor left the project. Two separated engines driving a common shaft clutched to allow separated starts and stops, would simplify the switch from peak power to the less than half output that would require only one engine. You also need separate air/gas mixers, as the gas piping will always affect the gas flow in a way that is difficult to instrumentally measure. I usually tune the engine by ear first, then have a fixed mark on the valves for a basic system, and the engine will start with only a few cranks every time. Hope this helps, but let me know if you have any problems. Doug Williams, Fluidyne. > Doug, > > > > I have seen photos on your website of multi-engine operation driving a > central shaft to a single generator. So I know you have done it. We have a > small design that goes nominally up to 40kW as this is the largest petrol > engine we can reasonably find - 7 litre V8. I guess putting two of them in > parallel would be manageable as well. I would be squeamish about the start > up though. --- This email has been checked for viruses by Avast antivirus software. http://www.avast.com _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/
