Gasification Project, Waipa (Windsor Kilns)

For a complete overview and indepth information please download the pdf below -

Windsor Kilns Gasification Project Overview 

This project is to build a gasification plant in front of the existing boiler for the kilns at Waipa campus, to make gas from sawmill wood waste and commission the existing kilns with no external gas cost. The plant is illustrated below. The gasification unit sits immediately in front of the existing boiler. The project will include fuel bins and feed systems. The financials include provision for a tutor or researcher.

Explanation.

The plant will consist of the gasifier, a green sawdust and a dry shavings fuel bin, a transfer screw from the bins to the gasifier unit, and a link to the existing natural gas boiler.

A mixed fuel to a moisture content of 35% wet basis will initially be burned. It is proposed to trial other fuels in the future, firstly to determine the fuel maximum moisture content for satisfactory operation, and then to introduce high ash fuels such as bark.

The heatplant is automatic in operation, including start-up.  The gasifier includes an indexing rotary grate that discharges incombustibles and ash automatically to a waste hopper. Wood fuel is added from the top of the gasifier chamber, via a small surge hopper and twin regulating feed screws. The fuel pile level is maintained automatically in the gasifier by twin level probes.

Primary combustion air is metered via a small air fan to the fuel from below the grate, both cooling the grate and adding preheat to the combustion air. Secondary or overfire air is added to the gasifier chamber only during the start up phase.  The gasifier chamber has a safety vent that provides protection from an uncontrolled gas buildup and sudden combustion.

The gases released in the gasifier chamber (at approximately 450 degC) are then drawn to a secondary burner by an induced draft fan fitted at the discharge of the boiler heat exchanger.

The secondary burner has a recirculation system comprising centrifugal fan and a highly developed nozzle system that provides correct air quantities at the secondary burner, while also ensuring good gas and oxygen mixing, and efficient combustion.

A small pilot gas burner utilising bottled butane is used to provide a combustion source for the secondary burner during start up. Pilot operation is intermittent ie, once stable combustion is proven at the secondary burner, the pilot flame is turned off. Gas usage for the pilot flame

is very low.  In the secondary combustion chamber flame temperatures are high (over 1200 degC) and excess oxygen levels are low (around 5%).

Benefits

1. Re-establish Timber Drying curricula at Waiariki Centre of Excellence
2. Establish new courses in Gasification and Bio-energy for all industries with boiler fuel requirements
3. Establish courses in Boiler Operation
4. Dry timber for existing machining courses and new glued product courses.
5. Dry timber for customers of the sawmill
6. Increased utilisation of the Waiariki Institute of Technology sawmill
7. Partnership with Industry at leading edge of new technology
8. Integration and collaboration with SCION
9. Establish related research programmes (drying and biotechnology)
10. Research facility for the Centre (in association with University of Auckland)
11. EECA (Government) will contribute to the conversion costs of the energy plant.
12. On site saw mill waste will be used for energy generation.
13. New technology for converting the biogas produced by the system to liquid fuels is being developed and the plant will be suited as a research vehicle with industry partners.
14. Ongoing support of and commitment from industry.

• Higher efficiency than fixed bed combustors
• Reasonable levels of fuel moisture and high ash fuels tolerated
• Good control of combustion
• Minimal particulate discharged to atmosphere (no downstream filtration required)
• Suitable for relatively small plant
• Automatic operation

Project Progress - 

8th February 2011	The seperate components of the gasifier have been completed and are being prepared to ship from Norway in the next week or so.
18th March 2011	The boiler survey is under way.  The boiler is being given a complete overhaul and check over.  By the end of the day we expect it to pass it's Warrant of Fitness.
28th March 2011	The beginning of the hill excavation, which took an entire week and 350 tonnes of dirt was removed.
11th May 2011	Gasifier equipment arrived; concrete pad being laid for gasification plant.
20th June 2011	Work started on civil foundations
1st July 2011	The gasification unit is set in place.  Having arrived from Norway it is still wrapped nice and warmly with the onset of winter.
1st July 2011	The foundations are laid for the construction of the feed bins to begin.
1st July 2011	The hill between the Sawmill and the kilns has been removed.  Construction now begins on the feed bins for the wood waste.
1st August	The gasfication unit sits atop the concrete pad.  The feed bins (on the right) store the wet and dry wood waste.
1st August	The inside of the wood waste bins.  There are hydraulic rams in the floor which force the chip forward.
1st August	This is the approach to the gasification unit from around the Windsor kiln units.
5th August 2011	The view to the feed bins and gasification unit from the Sawmill.
5th August 2011	South side view of gasification unit and feed bins.
5th August 2011	The view from the feed bins down on to the gasification unit.
12th August 2011	The view from the south.  Note the feed bins are nearly complete.
12th August 2011	The view towards the feed bins from the sawmill.
12th August 2011	The initial pipework is put in that connects the wood waste gasification unit through to the timber drying kilns.
19th August 2011	The view from the south.  Note the conveyor is now in place.
19th August 2011	The view towards the feed bins from the north.
22nd August 2011	The project is coming along nicely
26th August 2011	Nearly ready for take off....
5th September 2011	Official opening of the new gasification plant. Left to right - Maurice Davies (CEO - Windsor Engineering Group), Hon Todd McCVlay (MP for Rotorua), Jeremy Christmas (Director, School of Forestry and Primary Industries)
9th September 2011	The view from the South
9th September 2011	The first ever delivery of wood chips are placed into the feed bins
9th September 2011	The feed bins are loaded and ready to go with wood shavings