Californian Andes Class Development Programme "Linear 1"
test programme for the long awaited MK10 Andes Class gasifier took
place from 5th-22nd November 2011, bringing a significant change to how
the gas is made. Actually, while the basic work platform of coolers,
filters, and condensers of the Andes Class programme was reused, the
gasifier itself is new, and of linear design. We refer to it as "Linear
1" for a working title.
The MK9 Andes Class round hearth design, was during 2011, pushed to the limit of it's gas making capability, just reaching a wood conversion of 270lbs/hr (120kg/hr) which roughly equates with 1.2 million btu's for process heat, or 100 kWe if generating engine powered electricity. In actual fact, this design was more stable around 75% of this output, but provided a capability to study how the fuel behaves, moving at high bed speeds, within changing parameters to maintain a tar free gas making capability. They chipped just over 400 tonnes of logs for these test, which puts real meaning into processing a forest through the small 7" funnel of a gasifier throat.
The new linear gasifier is contained in a flat sided casing, with a fuel feeding auger sticking out of it's rear, heated to around 300C by the exiting gas. This lower output gas temperature has already made redundant the primary gas cooler of the Andes componentry, allowing for a more compact and versatility of assembly options. The feed auger connects to the existing fuel locks and drier/elevator system, and the two gas outlets plug into the Andes component platform with flexibles.
Due to the size of the existing gas cooling/cleaning system, the output from the new gas making hearth was made for the same 1.2 million btu gas production, but with such changed parameters, felt quite nervous as to how this design would perform. As it turned out, the output increased by 6%, waste char reduced to about 2% (down from 4%) and the gas quality only slightly fluctuated right through the range of flows tested. These were measured at 100, 108, 124,147,155, scft/minute. At maximum output, we saw CO 26%, H2 15%, and CO2 11%, but CH4 readings were found to be faulty due to a problem of the sensor calibration. The analyser is to be returned to the manufacturer and reset specifically for CH4, and a second unit ordered as a back-up for the 2012 continuously operating test programme beginning in February, when the heating system is required.
After the first successful test run, an inspection was made of the internal metal and refractory, looking for any distortion to the components, as the oxidation temperatures were higher than previously experienced during this development programme, measured at 1,350C in a safe TC position just out of the oxidation lobes. As almost the whole system is automated, the gasifier was restarted for a continuous 24hr test for the second run, but manual draining of the aqueous condensate was required about every six hours. This amounted to roughly 10 gallons (40 litres) each drain, an increase over previous tests, highlighting how climatic seasonal conditions influence and change a gasifiers performance. It takes no imagination to see how this much water would affect the engine or burner performance, if not removed from the gas stream.
Although set-up in February 2011, the large Cyclomix burner assembly and heat exchanger had not been used for last Winters heating trial, due to other business demands for the time available, but was ready for use for this latest test programme. A refractory felt lining was installed into the combustion chamber, and a pile of refractory brick mounded in front of the blue flame, creating an incandescent radiating mass. It can be said now, that with the gas making quality stabilized, very accurate emission tests could be conducted on the flue gas. All these tests were conducted by Tom Miles, who has patiently waited in the wings for us to bring it all together, and see if we could meet those standards he measures. His written report hasn't reached me yet, but he was pleased at the outcomes, and looking forward to measuring the Tecogen CHP system in 2012 on the new gasifier.
From a personal perspective, these latest trials were in my opinion, some of the best producer gas that I have ever seen during the 35 years of working with this gas. Two years ago, it was established that in this location, producer gas could replace LPG for around 60% cost wise. LPG costs this past year are up 50% over last year, so the economics are swinging well over into credits for producer gas. As a project initiated to replace LPG, bringing stability to the heating costs for this Forestry Nursery, it is very satisfying to see a project reach it's objectives. This coming year of 2012 is when it all comes together, so for us all involved, it's "steady as she goes" !!
Automated engine gas control.
Trials with the Tecogen on producer gas were put on hold, until I returned for these latest tests. Using the old Onan generator, we had to develop an automated starting sequence of gas mixture control, requiring a rather unusual fabricated assembly. Not quite a mixer, but a signal generator for the gas regulating supply valve. After a few false starts to get the programming right, the engine was able to start-up and run quite smoothly. Time ran out for me to swap the system over to the Tecogen, but they assured me it would be fitted in time for the February trials.
Finally, the large IHC engine used for the Laimet Chipper threw a con rod, just a few days before I left on 22nd November. A replacement engine has been located, and in the fullness of time, be built into a new transportable trailerized assembly. In the mean time, testing has commenced on using a wide range of standard wood chips available from local contractors. The new linear hearth is fully and easily adjusted, so these tests will be to establish a clear boundary for fuel quality, and changed to suit local chip supplies. Having had a chance to see these chips, it is clear that quality control is not a factor for many of these suppliers, and fines make up a large proportion of these piles.
|This is the new "Linear One" gasifier on the scales for weight check. It came in at 850 kg, just for the gas making section. The input flange from the fuel locks is on the left hand end feeding the fuel auger, heated by the hot gas which exits through the two 6" pipes seen on the under side.|
|The old component platform of the Andes Class, was fitted with a connecting flange to allow the new hearth module to be connected with SS flexibles.|
|Now seen connected with the SS flexibles, the original fuel locks and fuel elevator drier are just bolted in place and ready for the first test.|
|Seen from another angle, the fuel elevator /drier and fuel locks, connect at the original height to the new hearth module.|
With the only two access panels closed, the sealed unit is ready for ignition.
|Ignition of the pre-filled char bed was instantaneous, and gas was ignitable at the flare in just over a minute. This familiar Sun like oxidation colour stayed the same right through all testing and operational time. Previous tests showed a lot of colour variation, resulting with cyclic gas quality, and test flare colour variation.|
|Shown here is the new overhead pipe line from the gasifier to the cyclomix burner in a near-by greenhouse. Both the blue CHP Tecogen, and the green Onan engines can be seen in their test positions.|
|Now in place in the greenhouse, the cyclomix burner and heat exchanger is ready to test. The gas pipeline comes in from the left over my head.|
|Located at the far end, the Cyclomix burner will replace five of these LPG burners currently being used to heat this section of the Tree Nursery.|
|Seen just after ignition, the blue flame of the cyclomix burner impinges onto the black refractory brick piled in front, to enable radiating heat to be created from the none luminous blue flame of the producer gas|
|After the system heats up, the refractory glow red hot, but the flame remains blue out of the burner nozzle.|
|With all gas going to the flare stack, this flow of 147 scft/min made an impressive flare roughly 2m high. In this mode, considerable information is obtained from the flare, especially the presence of carbon blacks, or tars, which contaminate the feathery ends of the outer edges.|
|Tom Miles with some of his amazing range of equipment used to test the boilers and gasification systems of many manufacturers, and companies. Information collected is observed, but stored for later retrieval and analytical interpretation.|
|Flue gas flow and temperatures are measured for the first time, with this specifically designed heat exchanger built to be heated from clean, none luminous producer gas. We expect that the design parameters will be modified, once the operational data is obtained beginning in February 2012.|
|Looks like Tom Miles, and Tom Jopson, owner of CalForest Tree Nurseries are swallowing a bitter pill. Not so as it turned out, just a blip with the instrument calibrating cycle.|
|Fabricated in a span of an hour, this venturi type device was used to provide a flow differential signal to the engines gas control valve, seen mounted under the Dwyer vacuum gauge with a black motor housing. This critically important component enables the engine gas ratios to be set for automated starting, and adjustment for controlled exhaust emissions.|
|Set to the side for the time being, the round Andes Class hearth module takes a rest after gasifying over 400 tonnes of chips. This test programme has allowed us to test the limits of this design for our type of gas making, and set parameters to start from with the new linear hearth series.|
|Not a shiny WOW factor at first look, but this practical low cost solution using scrapped equipment, gave us a simply way to have a 24 hour fuel bin set up in a confined area to feed the fuel elevator drier. It was originally filled with bins from a forklift, but now found easier to just tow down and fill directly from the Laemet chipper.|
|Disaster at the chipper. The old IHC engine threw a con-rod and knocked an oil gallery component out of the engine while unattended during a slow cold start-up. The low oil pressure signal shut it down quickly, but it stopped any further 24 hr testing for the last three days.|
|Looking for a source of standard mill chips, we visited the Roseburg's veneer log peeling operation at Weed, in California. www.Roseburg.com where Arnie Hultgren, Resource Manager, gave us a tour of the facility. This was a real lesson of watching tree into product at extraordinary high speeds. As a Boilermaker, I found their boiler installation and wood fuelling system set up to meet exacting standards of operation.|
|Boiler chips are transported into the Roseburg Mill, where 50-60,000 tonnes are fired into the boiler each year. This is one example of how forestry wastes can be utilised, and reduce the hazard of annual forest fires. Surplus steam for the log peeling operation, is supplied into a 10 MWe turbine generator, which at the time of our visit amounted to around 3 MWe.|