Hi Pete, and Colleagues, Sorry for the delay in responding to this post, but other duty calls, and just returned from the UK.(:-)
You ask: Has anyone here had any experience running an engine using the Stak Properties 10K gasifier? >From the responses so far, it looks like few have shared your experience, >except possibly Kevin, but I had a look at the Stak brochure on line, and can >offer a few comments. They tell me that the JXQ-10 gasifier is a forerunner to this machine. I have one of those. I'd like to be able to correspond with others who have this style of machine. The early reports on these types of gasifiers, reported it as a cooking gas system for stoves, not for engine application. While you can run an engine on this gas, it will have limitations imposed by it's intended original purpose. Currently I am having mixed results getting a steady flow of good gas to run my 6.5 KW Onan 1800 rpm genset from it. On Saturday, I got it to deliver about 3.8 kw for about 12 minutes, but then the quality of the gas deteriorated. I checked out the Onan engine specification for the 6.5 kWe model, and see that it has a cylinder volume of 39.8 in3 (653cm), and on producer gas at 1800 rpm, you should be able to generate 3.656 kWe maximum with that engine. this would be with a gas of reasonable gas quality free of tar. Higher outputs will indicate higher levels of CH4 and condensable tars. On Sunday a similar test produced worse results, but over about a one hour period, with gas quality again deteriorating as the test went proceded. Probably a number of factors came together during your tests. 1. The output exceeded the designed standard performance set by the suction fan for cooking quality gas output. 2. Being water cooled and partially cleaned, the water heats up, and humidity is entrained with the gas. This dilutes the calorific value of the gas, so the engine slows down. You will note that Stak suggest you recirculate the water for heat recovery and better cooling. As tar will be present in this cooling water, you will probably find the water will turn green, if you use pumps with bronze bearings or castings, as the copper leaches out of the metal. As is, you will be limited by the rate of heating of the cooling water, and environmental temperatures. I am not writing to waste the time of senior members here by asking them to troubleshoot my problems, without enough info. Just want to show what kind of issues I have for those who might be involved with similar equipment. Time is never wasted on answering questions where clearly a few pointers can save time and $$. There is no profit to anyone, for the less experienced not to get clear answers to their questions, especially for gasification for power generation. My goals are to: 1. See how much power I can squeeze out of the generator for an extended period of time with this gas source, >From the engine specification, you have achieved your first goal, that is if >when you look under your intake throttle butterfly, and find no tar. This will >tell you your gas is not tar free for engine application. You might not start >your seized engine next trial if it's really sticky, but light pyrolysis oils >are less of a problem. The filter suggestions offered by Stak are less than >helpful, in fact misleading. You cannot filter tar out of gas, other than for >a very short period of time. Once the system becomes heat soaked, the tar will >move on down the system. You also must appreciate, that handling tar >contaminated filter materials are carcinogenic through the skin and lungs, >then become a environmental disposal problem. Don't pretend you can get away >with it because it's fun to experiment with producer gas, real health issues >can eventuate, so take note. and 2. To get some actual experience making woodgas. Given you can make producer gas, you are locked into how the gasifier normally works, and you need to first measure the temperatures of your water and gas when it is considered operating normally for a stove application. You might then consider comparing the output suction using a simple manometer fitted before the fan, first on the stove, then the engine. Probably, the engine pulls more gas, and this will upset the parameters of the open core design, pulling down the oxidation bed towards the grate. This then gives you more hot CO2, and can heat the water faster. I noticed the gas stove pulsates at the burners, which may indicate the gas is glugging through the water in the cooler in large bubbles. This does entrain tar to stay in the gas if present, and reduces the efficiency of the cooling water from loss of contact. Looking back over my videos and notes, I can see a dozen or two things that I could do better next time. The good thing, is there can be a next time while we have the support of the National Grid. We do have time to play (:-) Hope this may be of assistance. Doug Williams, Fluidyne Gasification.
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