Heuristic Engineering Inc.
Heuristic Engineering is a privately owned, BC company, founded in 1978 by Dr. Malcolm Lefcort. The company specializes in both the two-stage gasification and the two-stage combustion of wet, solid waste.
Two-Stage Gasifier:
Heuristic's two-stage gasifier - a first stage of gentle updraft gasification followed by a second stage of downdraft char gasification was developed by Dr. Lefcort during the 1980's with support from the Science Council of BC and Natural Resources Canada. Additional development is needed to bring this gasifier to market. Enquiries are welcome.
Two-Stage Combustor:
The Heuristic EnvirOcycler is a two-stage combustor, the precursor to which was developed by Dr. Lefcort in the late 1970's. The EnvirOcycler gasifies wet wood waste (or any other biomass) in a very large first stage of gentle updraft gasification. The 'producer gas', so formed, is vigorously burned in the EnvirOcycler's second stage, cyclonic, double vortex, combustion chamber located immediately above its first stage.
Particulate levels in the EnvirOcycler's discharge - the temperature of which is typically about 2000F (1100C) - do not exceed 120 mg/Nm 3 (0.052 grains/dry standard cubic foot) at 12% CO 2 by volume. These particulate levels are also well within the US EPA guidelines.
The EnvirOcycler forms the heart of a variety of waste-disposal/energy-recovery systems. Typical systems are described below.
Wood Waste / Sawmills:
In larger sawmills (> 100 Million board feet per year) heat recovered from EnvirOcycler used to dispose of the sawmill's wood waste, can be used to dry the sawmill's lumber (40 10 Million Btu/h or 11.7 2.9 MWt) and to generate its power (3 to 5 MWe). In smaller sawmills (< 100 Million board feet per year) the EnvirOcycler's products of combustion can be used to direct fire the sawmill's dry kilns.
Because of strict Boiler Branch staffing rules, Canadian sawmillers shy away from generating power with steam. Heuristic Engineering is actively promoting using an indirectly heated gas turbine generator set to produce between 3 and 5 MWe.
Wood Waste / Board Plants:
Earlier versions of the EnvirOcycler have been in continuous service in the forest products industry for over 18 years. Two 45 Million Btu/h (13.2 MWt) units have each been direct firing rotary dryers in a waferboard plant in the US Midwest. A 27.5 Million Btu/h (8 MWt) unit direct fired two dry kilns in a pole treating plant in the US Southeast for 14 years before being shut down because the low cost of natural gas made the wood waste operation uneconomic. After 15 years of continuous service, a steam plant in a hospital in Newfoundland shut down its 10 Million Btu/h (2.9 MWt) unit when its long time, whole tree, chip supplier retired.
Wood Waste / Pulp Mill Lime Kilns:
In the early 1980's the Canadian government sponsored a demonstration project in a pulp mill on Vancouver Island in which a 60 Million Btu/h (17.6 MWt) unit direct fired a lime kiln with the 2200F (1204C) products of combustion of 55% moisture content (wet basis) wood waste. The project demonstrated that it was possible to replace at least 85% of the lime kiln's fossil fuel with wood waste products of combustion. The project ended before it was able to demonstrate that burning hot first stage producer gas in the firing hood of the lime kiln could replace 95% 'plus' of the fossil fuel.
Wood Waste / Utility and Pulp Mill Power Boilers:
A better way is to burn wood waste is in an EnvirOcycler and to duct the up to 2200F (1204C) products of combustion, in a breeching into the existing boiler's furnace section. In this 'external co-firing' mode 99% + of the wood ash stays in the EnvirOcycler's first stage and only hot 'flue gas' enters the boiler.
In response to a Request For Proposal from a large utility in the USA, Heuristic proposed installing three 75 Million Btu/h (22 MWt) EnvirOcyclers on a 270 MWe pulverized coal boiler. The three EnvirOcyclers produce enough products of combustion to raise sufficient steam to generate 10% of the power plant rating. The installed cost of the system is estimated to be under US $370/kWe.
Agricultural waste:
With the EnvirOcycler's large grate and low grate temperature, potassium or sodium in agricultural waste ash do not vapourize and enter whatever heat exchanger the EnvirOcycler fires. Rather, these alkalies stay in the EnvirOcycler's first stage as potash and soda and are removed by the first stage's built-in ash removal system. Therefore, the EnvirOcycler is suitable for the disposal of all forms of agricultural waste.
One such waste is rice husks. One unit operated in a parboil rice plant in the US Southeast for about 13 years. It direct fired a waste heat boiler as well as a parboil rice dryer. A major problem with rice husk combustors is the very high silica content of its ash (about 22%). When the grate temperature exceeds 1600F (870C), the naturally very porous, absorbent silica in the rice husk converts to the crystalline form known as tridymite. If inhaled for prolonged periods, tridymite can lead to silicosis. Since the temperature of the EnvirOcycler's grate is only about 1200F (650C), the porous form of silica in the ash does not convert to the crystalline tridymite form. The porous form, in addition to not being a health hazard, also has economic uses - such as absorbing oil in automobile repair shops, etc.
Poultry Litter:
Another use of the EnvirOcycler is the waste disposal of, and the energy recovery from, poultry litter.
Using EnvirOcyclers to externally co-fire boilers in the Delmarva region's many poultry processing plants will dispose of the litter and displace some, or all, of the fuel oil used to fire the boilers. Furthermore, the ash can be sold as fertilizer to farmers.
Garbage / Landfill Reduction:
The amount of Municipal Solid Waste (MSW) cities can landfill is being restricted in many jurisdictions. In California by the end of 2000, cities will have to reduce the amount of waste they landfill to 50% of the amount they landfilled in 1990. A solution is to install a combination 'dirty' Material Recycling Facility (dirty MRF) and a Waste to Energy (WTE) plant featuring the EnvirOcycler, on landfills. Dr. Lefcort showed that a dirty MRF/WTE installed on a California landfill processing MSW has a return on investment of 25% over 10 years.
Other Wastes:
Finally, in addition to the above, the EnvirOcycler is also suitable for the disposal of other solid wastes such as: mixtures of RDF and municipal sewage sludge; shredded tires; mixtures of shredded tires and municipal sewage sludge; shredded industrial waste such as carpet waste, auto fluff, etc.; and recovering process heat/power from the sensible heat in their products of combustion.
The EnvirOcycler is manufactured by select manufacturers licensed by Heuristic Engineering. Heuristic Engineering personnel supervise the installations and commission the EnvirOcyclers.
SNC-Lavalin Inc, Canada's largest EPC (Engineering, Procurement and Construction Company), and Heuristic Engineering Inc are developing a 3.5 MWe Wood Waste to Energy plant featuring a 50 Million Btu/h EnvirOcycler near Squamish, BC. The plant will be owned and operated by SNC-Lavalin. The plant is expected to be operational early in 2003. An agreement is in place to sell the power produced to the British Columbia Power Authority.
The plant will charge a tipping fee to dispose of land clearing debris, construction and demolition debris, dry land sort debris, river debris, etc.
Company Details
Company Information
Malcolm D. Lefcort
Title:
Manager
Area of Responsibility:
Management Executive
Telephone:
(604) 263-8005
Fax:
(604) 263-0786
Email:
Click Here
Products
Environmental Products And Services
Sawmill Energy Displacement Plant.
Using an EnvirOcycler two-stage, combustor to dispose of the sawmill's wood waste, the Sawmill Energy Displacement Plant (EDP) generates power and recovers process heat from the EnvirOcycler's discharge. In addition to the EnvirOcycler, the EDP comprises one or more 'recuperated' gas turbines, each driving a 3-5 MW electrical generator, along with waste heat recovery equipment in the form of hot oil, hot water or steam generators for dry kiln and building heat. A 'recuperator' is a high temperature gas - to - air heat exchanger which replaces the normal gas turbine combustion chamber.
The heat source for the Sawmill Energy Displacement Plant is the 2000F (1100C) EnvirOcycler products of combustion 'flue gas'. The flue gas travels through the gas side of the recuperator while compressor discharge air travels through the recuperator's air side. The pressurized hot air leaving the recuperator is ducted to the turbine's first stage.
When using a nominal 3 MWe Solar Centaur gas turbine generator set - which can be retrofitted with a set of specially designed castings leading 'cold' air out from the compressor and 'hot' air back into the turbine - the 2000F (1100C), atmospheric pressure, EnvirOcycler products of combustion transfer heat (across the recuperator's walls) to the 143 psia (9.9 bara), 610F (321C) compressor discharge air to raise the temperature of the air up to the turbine inlet temperature of 1660F (904C). 819F (437C) waste heat - from the discharges of both the turbine and the recuperator - is recovered by heat transfer fluid(s) and used to dry the sawmill's lumber and to heat the sawmill during the winter months.
A nominal 5 MWe GE/Nuovo Pignone PGT5 gas turbine generator set can also be used for this purpose. ASME paper 98-GT-62 describes some applications of the PGT5.
Envirocycler Two-stage Wood Waste Combustor.
The two-stage Heuristic EnvirOcycler gasifies wet (typically) solid waste in a first stage of gentle updraft gasification. The producer gas formed is burned in a second stage of vigorous cyclonic combustion. The second stage is located immediately above the first stage.
The Heuristic two-stage EnvirOcycler is a proven, forest products wood waste combustor with a 22 year track record. The EnvirOcycler gasifies wet wood in a large first stage of gentle updraft gasification and then immediately burns the 'producer gas', so formed, vigorously, in a second stage, double vortex, cyclonic combustion chamber.
The second stage is located immediately above the first stage. A built-in, automatic, ash removal system removes ash from the first stage. Particulate matter in the EnvirOcycler's 2000F (1,10C) products of combustion is typically about 90 mg/Nm3 (0.037 grains/dry standard cubic foot) at 12% CO2 by volume. CO and NOx levels, measured in March 1999 were 1 ppm and 130 ppm by volume, respectively, at 2100F (1150C).
Stand alone EnvirOcyclers in the 10-130 Million Btu/h (2.9 to 29.3 MWt) range are available to dispose of 30-65% moisture content wood waste, on a wet basis. At 45% moisture content, the corresponding range of wood waste disposal rates is 1.2-15.5 wet tonnes/h.
Combined Veneer Plant Voc Afterburner Energy Recovery System Fired By Products Of Combustion From A Wood Waste Burning Heuristic Envirocycler.
Veneer dryer emissions are destroyed in a combined afterburner/insulated-duct which is fired by 2,000F (1,093C) products of combustion from a wood waste burning, 60 Million Btu/h (17.6 MWt) (typically), Heuristic EnvirOcycler. Up to 45 Million Btu/h (13.2 MWt) of hot oil heat can be recovered from the 1650F (900C) gases and used to displace natural gas in the veneer dryer.
The 350F (177C) veneer dryer emissions are drawn from the dryer stack by a small fan and blown over to the afterburner. The afterburner injects the dryer gases radially inward into the 2000F (1,100C) products of combustion stream discharged by a 60 Million Btu/h EnvirOcycler.
The combined gas stream, cooled to about 1650 F during the mixing/blending, is retained for slightly longer than one second in a horizontal insulated duct. At the end of the duct the blended gases are drawn down through a 45 Million Btu/h hot oil generator, under the action of an induced draft fan on the heat exchanger's discharge.
The hot oil is used to displace natural gas presently direct firing the veneer dryer. The dryer requires retrofitting with hot oil heating coils. Steam can be used instead of hot oil but, in Canada at least, the use of a steam generator usually involves a higher category operator than a hot oil generator.
Services