Hi Gasification Colleagues,
Having returned from a visit to our gasification development project in California at CalForest Forestry Nursery, some may find it interesting to see how the " Shasta Class 1" (this is the new designated name for this series of linear hearth gasifiers) gasifier project has progressed since my last visit 18 months ago. With the new "Shasta 2" now finally in existence, the alternative of the blown mode of gasification will be investigated. The photos can be seen on the Fluidyne Archive www.fluidynenz.250x.com The photos are larger than normal so you will need to slide left to read the text. Shasta 1 was put to work these last two Northern Winters to heat the green house as shown in the last project report, and other than what could be called normal unexpected stoppages due to shear bolts breaking and chips in the wrong moving place, proved to be more than adequate for the heating requirement. The heat exchanger that was built, proved a little small to test the upper gas outputs, but as a complete system, provided a test bed for the automation allowing unattended operation. Operation of Shasta 1 over the annual seasonal changes while hooked up to a online gas analyzer, highlighted the variations that can be experienced by the gas making process, some of which are almost impossible to detect, let alone control. The stability and natural evolution of the packed bed oxidation and reduction chars has always been considered the most important aspect to our gas making philosophy, so a new design feature of Shasta Class, is adjustment of the bed during operation in responce to gas quality changes. Char extraction is not used in any way to maintain the process, but some char does exit the reduction zone naturally with soot's entrained in the gas, and the dropped larger fraction augured out the bottom. The cyclone then removes most of the char entrained in the gas stream. We are interested in two options for using producer gas to heat greenhouses; gas/air or water/air heat exchangers. Shasta 1 has been using a gas/air exchanger. Shasta 2 will be tested firing a hot water boiler, with the gasifier operating in the blown mode. Drawing from experience of operating the Pacific Class gasifiers in the blown mode with hot gas cleaning using a four cluster cyclone, particulates down to about 10 micron (talcum powder) are removed before gas combustion. The test flare after cycloning was without angry red feathers or sparks and had very nice colors without any stinging radiation to indicate the presence of uncracked hydrocarbons. Flare colors are still an instant insight to indicate gas quality, and my hope in the future is to see these colors matched in real time to the gas analysis. Although Shasta 2 was designed around the original 100 kWe ( 320Nm3/hr) gas output, converting approximately 140 kg/hr fuel, the gas making will be pushed to it maximum, now that weights can be more accurately established using scales under the trailer fuel bin. To facilitate easier management of the fuel chip supply for this test programme, the gasifier, fuel feeders, walking floor trailer storage, and chipper, are together next to the log storage area. With something like 600 tons on site, one begins to appreciate how much wood you need to supply a 1-150 kWe gasifier, which clearly illustrates the concept of feeding a forest through a funnel. Bearing in mind that when a gasifier is placed in a location that is not ideal, the installation lay-outs lack ergonomics due to reusing and recycling of quite expensive components. The gasifier remains a bare bones model without mounting skids or service decks, as we fully expect to have a need to modify the fuel input componentry. Waste char from the gasifiers at CalForests, which everyone now calls biochar, completed first stage composing trials last season with excellent results. These bin trials were to establish how the various temperature profiles develop, plus of course how the seedlings respond to these blends. The next phase is to conduct trial of windrow piles, as there is now substantial stored char, opening up another exciting activity associated with this Nursery business. With the 2013 season the busiest yet, when some 20 million trees will be shipped out to Forestry operators, they still find time to provide continued support to research institutions, and remain privately funded from this commercial activity. I can only take my hat off to Tom Jopson and his dedicated staff, to show you a tiny portion of what I experience during my visits. My work on site is now less than necessary, but still rewarding to see as it provides capability for sustainable activity in a rural economically depressed area. Doug Williams, Fluidyne Gasification.
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