Fluidyne Gasification Archive

California Linear One


Since the last report on this new gasifier development in December 2011, considerable time has been spent on testing forest chip as available from most supply contractors, mainly due to our own Laimet chipper being out of service. Considerable knowledge was acquired on how heat penetrates the chip mass while moving, and the limitations of dimensions required to completely torrify wood within a packed bed.

Having tested the fuel drying elevator to the point of destruction (it caught fire late at night, much to the delight of the local fire department), a screw auger elevator was installed, which after a few false starts, has proven to be for this situation a very good match. This is fitted with a small charging bin fed from the movable bulk chip wagon, allowing for the wagon to be removed, filled, and returned without interruption of the gasifiers operation.

The other change made, has been to remove the primary heat exchanger, and feed the gas directly into the ceramic filters, so we can continue using this set of componentry until the end of this year, and possibly into the first quarter of 2013. Linear One makes more gas than can be used in the burner/ heat exchanger we built for the greenhouse, so we either have to run at reduced output, or run the Tecogen CHP system at the same time. This has also provided a challenging situation, in that as the heat exchanger overheated, it shut down the gasifier and engine without leaving any signature as to why. One always doubts the gasifier, but a few late nights, and operator attendance quickly picked up the glitch,and the gas flows modified accordingly.

The Laimet Chipper is now repowered with a Cummins engine, and it is a chance to remind ourselves that chippers like alternators need constant speed governing. Not all governors can be adjusted, but this one was thanks to an older mechanic who knew about tweaking these diesel pumps. The chipper now takes the 40' logs to maximum diameter of 280mm through in one go without drooping in RPM, making the chip production faster than previously by double handling 20'logs. The current stock pile of 450 green tons actually delivered to this site, has taken a lot of extra work out of the test programme, but then all infrastructures are being trialed for future applications, and only a few people to do all the work, so good things take time.

After sitting in the corner for two years, the Tecogen CHP system has finally been hooked up appropriately, and currently generating into the grid at 40 kWe/hr, just under the predicted 42 kWe. This output will be lifted again shortly, as we test out the maximum output for the summer conditions on site (30>C), as the gasifier works it's way through the first 1,000 hour continuous operation test. This will be followed by repeated 1,000 hours tests until some thing fails, so by November/December, we should be able to wrap up this project, and move onto the larger outputs being designed for Linear Two.

Probably worth mentioning, is that since June, a policy of pushing the start button and walking away has been the aim of limited operator intervention. Yes it has caused some problems, but usually in the programming or ancillary components of the whole system. It's fair to say that I did not think the day would come to see this eventuate, but now that it has, a future door of opportunity can now be opened.

The late Jane Turnbull who persuaded Tom Jopson at CalForest Nurseries to embark on this five year development programme, always saw gasification as the means to top up rural extended power supply grids. Fully automated gasified stand-by generation has always been possible, but those technologies available, even those of Fluidyne, just do not provide the optimum systems that can be used anywhere, or for every one who has to operate them. Her long term dream of renewable energy independence is a step closer, and now with purpose built engines to support this larger generation need on producer gas, I might live long enough to write the report on it's success.

The following photos were supplied with captions from California, as I have not been able to plan my annual visit due to commitments of myself and others involved. 

September 2012.
Laimet HP25 chipper with new drive: Cummins Big Cam 400 with 1000rpm pto and clutch, then a belt drive reduction to lower rpm to about 700 and to reduce vibration.

Chipper will now run logs up to chipper’s maximum diameter of 280mm.
New fuel feed auger. Problems with a drag chain conveyor and a rubber belt conveyor led to this 300mm diameter auger. The original flat cover was replace with the domed cover to eliminate occasional jamming.
Right, Hearth.
Left, ceramic candle filter
Another view of the hearth
The Tecogen grid connected genset in operation at 40kwe.
The Tecogen grid connected genset in operation at 40kwe.
Sample of data from gasifier operation. The gas peaks at the beginning are calibration gas.