Chile Gasification Testing

 
When it becomes necessary for producer gas to replace LPG or natural gas in the commercial sector of any country, locally manufactured gasifiers of appropriate design is a major first step. Surprisingly, there are considerable variations in designs of ancillary systems needed from place to place, where the gases are used for a multitude of process heat applications. There is also the need to manufacture with materials that each country can supply and service.
 
When Douglas Diaz of Creapor SA. in Santiago Chile requested my assistance to assess gasification in April 2007 ( See, Gasification comes to Chile), I agreed to provide Fluidyne Technology to explore the potential market applications using larger gasifiers. The following photos show some of the activity during my visit April 2008 to test the larger gasifier, which has been given the identification of the "Andes Class", in keeping with the regions for which it has been designed. The gasifier was constructed within a three week period, prior to my arrival.
In the test situation, none of the automation was fitted, although the internal mechanisms were in place, and could be, and were operated manually. This allowed an evaluation to be made to adapt locally available technology to these systems, and to provide operating experience as to why systems can be both beneficial or detrimental to a gasifiers operational reliability. It also enables a manufacturer to be tested on the level of understanding to each modal of technology transfer.

When conducting operator training programmes with the gasifier, first the manufacturer, then key company staff, are given a written and practical test, again in modular format, providing a capability to then work without direct supervision regarding the gasification process. Previous experience has proven that gasifiers supplied without training support, is a waste of time and investment to all concerned. 
 
In providing this project profile, I have taken the opportunity to show how fast wood can turn into charcoal reducing in size, only as it begins to enter the oxidation zone, which in this blown gasifier, is slightly above the air nozzles.  No raw wood should be seen in the oxidation zone, as the amount of endothermic heat needed to drive the gas making process, can only be achieved from a packed charcoal bed.  Many incorrect descriptions exist of this process from wood to charcoal in a downdraft gasifier of this type, so take a minute to appreciate how critical this is to making a tar free gas. At full output of about 300kWt, the flow rate of fuel through this zone is 2kg/minute.  

Also tested for the first time (by ourselves), was a ceramic combustion chamber concept of the "Cyclomix Burner", we developed for producer gas application. It was sized at only 25% of the gas output, so use your imagination to see four of these blocks all burning at the same time. The ceramic component concept is not new, but is an area of expertise that this company can add, providing a wider application for producer gas heating. This was only a test of concept, which considering the gas had no dust cleaning systems, burnt very cleanly without odour or smoke during the testing. Smoke does appear when producer gas is combusted, where high levels of CO2 are in the gas before combustion.

Of special mention, the fuel wood preparation. It was an excellent use of my time to cut the wood blocks for these tests, having manually cut many tonnes during the last 32 years. It is not a waste of time where rural jobs are few, and incomes are desperately needed, where cut dry wood becomes a valuable local resource for gasified installations. Fuel wood chips specifically appropriate for gasifiers do not exist in the wider context of wood chipping, and is an ongoing priority in the work that I am associated.  

The company Creapor SA. also manufacture hot water boiler heating systems, for which  they have an active development programme, as well as an assembly line for popular sizes. They have allowed me to show you a couple of photos during factory testing, which was interesting for me to see a real gasifying type combustion process in application.

Doug Williams.
May 2008.

IMG_0189.jpg   1.  When there is no prior experience of preparing gasifier fuel, there is only one way to begin, using basic manual labour, mine in this case.
IMG_0188.jpg   2.  After the logs are axe split into billets, a tungsten blade tip saw cut the blocks to a mixture of sizes.
IMG_0076.jpg   3.  The finished fuel had a bulk density of about 350kg/m3, average for block Eucalyptus fuel dry, ready for gasification.
IMG_0043.jpg    4.  Checking the gasifier components before final assembly. This workshop works to ISO 2000.
IMG_0064.jpg    5.  Final assembly checks before painting and testing.
IMG_0253.jpg    6.  Ready for testing with temporary removable start-up hose.
IMG_0256.jpg    7.  New design of ceramic combustion chambers were also being tested for this development programme. The hanging ball is the weight to hold the fuel lock closed during manually operated test programme.
IMG_0211.jpg    8.  First start-up was in cold foggy conditions (10C), Ignition was 7 seconds, and first gas within 1.5 minutes.
IMG_0219.jpg    9.  First test is to check colour of oxidation zone, which shows desired colour like the sun.
IMG_0216.jpg   10. First gas billowing out, and undergoing "sniff" test for odours. This is not a joke comment.
IMG_0205.jpg   11. Looking directly down the central combustion nozzle after combustion air added.
IMG_0208.jpg   12. Douglas Diaz on the left, Doug Williams on the right, obviously happy with first test.
IMG_0227.jpg    13. This is the fuel 150mm above air nozzles. Note char outer ring, and raw wood centrally. At full output, the fuel consumption is 2kg/minute.
IMG_0228.jpg    14. At 75mm above the air nozzles, the outer char ring increases,while the central raw, or torrified wood area shrinking.
IMG_0229.jpg     15. At 50mm above the air nozzles, the raw wood has almost completely turned to char.
IMG_0231.jpg     16.  At 24mm above the air nozzles the central bed was almost complete charcoal, and at the air nozzle level, all 20mm beads of charcoal. This photo was missed due to flat camera batteries.
IMG_0240.jpg      17. This is the first view of the waste char, which is low grade activated carbon. the amount depends on how the system is set to serve the end function of the gasifier.
IMG_0244.jpg      18. With fines sieved out, it can be used as start-up char after any servicing that requires bed clean-out. Correctly sized char is important for first start-ups.
IMG_0091.jpg      20. The company also designs and builds a variety of hot water heating boilers. 
 IMG_0068.jpg     21. Two sizes of domestic heating boilers being tested during my visit.