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Optimizing Municipal Waste to Energy.

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Thermal Gasifier
An unwavering commitment to clean energy was the driving force behind the development of the Thermal Gasifier™ nearly a quarter century ago. Today, we're working harder than ever to ensure that the world's business and government leaders no longer have to choose between economic growth and a healthy environment.
Thermal Gasifier™ evolved to extract chemical energy from materials, commonly treated as waste, and transform it into valuable, usable energy and by-products. The Thermal Gasifier™ has proven to be the most economical and efficient method of extracting all available energy from the waste stream. This process accommodates the use of many different solid wastes without any alteration to the unique Thermal Gasifier™ design. This means that Vista International Technologies Inc. can maximize the energy generated from the waste conversion process while still exceeding the most stringent EPA and European Union regulations.
Vista International Technology's five United States patents enable it to engineer solutions to global waste problems by harnessing the untapped potential of waste for conversion into low-cost, clean electrical and thermal energy. There is one U.S. patent pending, as well as an international patent for European Economic Countries (EEC).

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Thermal Gasifier: How it works...

The Thermal Gasifier plays a pivotal role in helping Vista International Technologies, Inc. (VITI) accomplish its core objective to maximum resource recovery with minimal environmental impact. The proprietary patented technology is based on a two-stage gasification process. The Thermal Gasifier efficiently converts the chemical energy contained within waste, biomass, tires and virtually any solid carbon based processed fuel, into electricity and thermal energy, while capturing the pollutants and turning them into useful products.

The Thermal Gasifier reflects the recognition of the inherent value of many materials that are typically considered waste. The energy produced has multiple uses in commercial, industrial and municipal applications and unlimited potential as a low-cost, stable energy alternative with an economic and environmental benefit.

The Thermal Gasifier efficiently turns processed fuel converted from feedstock such as waste, biomass, tires and virtually any solid carbon based material into useful energy without harming the environment. It does so by extracting chemical energy from within solid waste and converts into a clean usable energy.

In the Thermal Gasifier, gasification and partial oxidation take place in separate gasification and oxidation areas of a single chamber, and final complete combustion takes place in the fire tube before entering the boiler.

Within the Thermal Gasifier, these separate areas are established by carefully controlling air content and temperature along the length of the Thermal Gasifier. Controlling the areas environment controls the degree of oxidation, permitting final total combustion to occur within the boiler instead of within the Thermal Gasifier, delivering maximum heat.

Once the feedstock has been processed into a fuel, most fuel still contains considerable water that must be removed before gasification. To accomplish this dewatering, the fuel first drops onto fire belt 1 into a low temperature region, about 800 - 1000ºF. As the belt advances, reflected radiant heat from ongoing downstream reactions increases the temperature to about 1200 - 1500 ºF, extracting as much water as possible from the fuel.

The heat used to dehydrate the processed fuel is virtually the only energy expended throughout the entire process that does not produce value - either heat or reclaimed materials for reuse. To minimize this lost energy, VITI strives to use processed fuel having a water content of about 10 - 15%, although the Thermal Gasifier can accept water content up to 50%.     

  

Gasification Process

STAGE 1a C GASIFICATION

As the moving fire belt 1 carries the processed fuel into the gasification area, the fuel temperature increases and it begins to decompose, or gasify. (Eventually, the fuel totally decomposes into gas and a solid residue that gradually cools to about 250ºF as it is conveyed by the fire belts to an ash pit.) Oxygen in air flowing upward through moving fire belt 1 reacts with the gases from the gradually decomposing fuel. The components of the fuel having high volatility begin to break apart, and some of these volatile components break apart into their constituents, such as hydrogen and carbon. Fans are placed near the beginning and at the end of the entire process, keeping the gas moving through the Thermal Gasifier. As the belt advances, the energy released by partial oxidation continuously increases the temperature within the gasification area to about 1200 - 1500ºF, at which point gasification is complete. The resulting gas and suspended particulates then move into the combustion area.

 

STAGE 1b - PARTIAL OXIDATION

The remaining solid fuel then enters the oxidation area, where it is partially oxidized with controlled air entering the oxidation area along the length of the moving fire belt 2. This oxidation releases additional energy in the flowing gas, gradually increasing the temperature along the length of the combustion area. Some of that heat energy radiates back into the gasification area to help support the self-sustaining nature of the gasification process, once again minimizing the need for external energy to perpetuate the process. The peak temperature in the oxidation area is around 2000 - 2500ºF, the temperature at which the gas moves into Stage 2.

At the end of the combustion area, all of the energy resides in the hot, partially combusted gas that moves into the fire tube.

 

STAGE 2 - THE FIRE TUBE AND BOILER (COMPLETE COMBUSTION)

To get to the boiler, the producer gas enters the fire tube, a passageway between the Thermal Gasifier and the boiler.

There, just enough oxygen is added to the flow of gas in the fire tube to cause complete combustion before entering the boiler, where the gas releases its remaining energy and raises the boiler temperature to about 2200 - 2800º F. As the gas leaves the boiler, all of the energy in the fuel has been extracted.

This complete combustion of the fuel in the fire tube makes the Thermal Gasifier so efficient and environmentally benign. Complete combustion extracts virtually all of the chemical energy that was within the fuel. Any small amount of heat that may be conducted through the equipment only minimally warms the immediately surrounding air. The unique design of the Thermal Gasifier causes the gas to retain practically all the energy from the fuel. The remaining particulates in the gas are stable, chemically non-hazardous oxides and in the case of used tires, carbon black.

The high temperature produced within the fire tube has destroyed such dangerous materials as dioxins and PCBs, a unique result of the two-stage design of the Thermal Gasifier.

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Prior Installations



To see a list of Thermal Gasifier installations prior to 2004, please click here .

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New Designs



The first of the new Thermal Gasifier models will be the MFG-8, set to debut in our Italian Demonstration project in 2010. The "MFG" stand for Multi-Fuel Gasifier. We want to make sure our potential customers know that our units are capable of processing almost any kind of hydrocarbon based waste stream. We fell that this capability of the unit is unmatched in the gasification industry. The "8" represents that the unit is rated to produce 8 million BTU per hour. This amount of energy corresponds to roughly 1/2 MW of power if the syngas is converted exclusively to electricity. The company is always concerned with safeguarding its technology, so we cannot give a detailed view of the unit at this time. Below is a rough drawing of the unit.