AUTOCLAVE HISTORY

The benefits of using pressurized steam has been known to men since ancient time. Its usage dates back to various cultures over 6000 years ago. The high-pressure steam autoclave was invented by a French scientist in 1879 to sterilize and disinfect medical instruments. Autoclaves are now commonly used in healthcare, laboratories, and commercial food preparation. Now, high-pressure steam and mechanical forces are used in a rotating vessel to significantly alter the weight of the municipal solid waste while also sterilizing it.

 

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HOW IT WORKS

During the process...

- Glass products are broken into small pieces 
- Plastic products shrink and ball-up 
- Metals are cleaned

- Aluminum cans are cleaned, sterilized, labels are stripped off
- Fibers from food, paper stocks, vegetable wastes, and small wood chips are thermo-mechanically pulped
- Wastes containing meats are stripped from bone, and the residual meat is reduced to connective tissue fibers.

- Many common household chemicals are hydrolyzed and detoxified.

 

With water, fiber, and metals removal, the residual waste weight is typically less than 20% of the original weight. The remainder is sterile and inert -- free of pathogens, litter, and decaying material that attract vermin and insects.

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A 'Typical' Plant...

Estech™’s commercially proven and proprietary Fibrecycle® autoclave process is an elegantly simple and robust system that sterilizes, reduces, and sorts municipal waste. The technology is scaleable and modular thus able to meet almost any application requirements.

 

Through this process, at least 80% of the waste stream is separated as dry fiber and water. Processed wastes can be safely sorted. With fiber, water, and metals removed, less than 20% of the original weight remains to be land filled.

During the process cycle, 100% of the waste is tested  for undesirable chemical content.

 

A Fibrecycle® plant contains:
- An inbound waste-tipping floor
- A main processing area with 2 steam autoclaves and pre- and post-treatment equipment
- And a product separations/recycled materials shipping area, in addition to an office area and a central control room.

The Fibrecycle® process begins when waste (with large items removed) is fed from a conveyor into one of the autoclave vessels, and is then evenly distributed in the vessel. The door is closed and sealed, and vessel rotation begins.

While the vessel rotates, steam is introduced and raised up to 7 atmospheres pressure at about 330 degrees Fahrenheit for a variable processing period of up to 45 minutes. As the cycle proceeds, the vessel contents are dried. Processed sterilized materials are then discharged onto an output conveyor.

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The sterilized material that emerges is without pathogens and has very little odor. This allows for easy sorting and handling of the processed material without the health and safety risks associated with raw municipal waste.

The sterilized waste is next fed into a trommel screen where the dry bulk fiber is separated. Valuable products, such as plastics and metals, are extracted for recycling. Iron and aluminum are easily extracted using magnets and eddy current separators. In the European Fibrecycle® model, glass is separated and recycled.

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This separated cellulose fiber typically represents more than 30% of the municipal solid waste stream weight, and well over 60% of the treated volume – representing an enormous reduction in waste volume. With the metal removal process, municipal waste weight is reduced by more than 80%.

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Dry cellulose fiber has many beneficial uses. After a detailed examination of its beneficial uses during its developmental period, Estech™ concluded that the best use for dry fiber was as a solid fuel, thus providing renewable energy from a domestic source.

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The typical Mod-3 Fibrecycle system includes a regenerated Brayton cycle engine, outfitted for staged solid fuel combustion. A standard plant (150,000 tons per year MSW processed; see the process specification) can generate 10 Mw of electricity from recovered biomass  and 10 Mw from recovered plastics for sale, as well as steam to power the autoclaves.