MCS TECHNOLOGY
OPERATING PRINCIPLES

The MCS technology achieves uniform desorption of the target chemicals through the application of vacuum and infrared heat to the solid matrix. The six primary operating principles that combine to desorb the contaminants from a matrix or soil are:

• Infrared heating

• Convective heat transfer

• Conductive heat transfer

• Boiling point reduction

• Air stripping

• Chemical volatilization

Radiant infrared heat raises the temperature of the bottom few inches of the matrix material in the treatment chamber to 200° F - 800° F, while air movement through the treatment chamber performs the following two vital functions:

1) Convecting heat through the matrix in the treatment chamber, and

2) Stripping the volatilized chemicals from the matrix and out of the treatment chamber

After reaching their boiling points or significant vapor pressure, target chemicals are effectively stripped from the matrix. A vacuum is applied to the treatment chamber reducing the effective boiling points of the chemicals.

INFRARED HEATING
The heat source in the MCS is infrared radiation. Propane and other fuels are used to fire the heaters and the flame heats a metal element causing the metal to emit infrared radiation. The radiation heats the bottom few inches of the matrix and creates a temperature gradient in the matrix.

CONVECTIVE HEAT TRANSFER
Without convective heat transfer, the bottom layer of matrix would get hot while the top layer would stay cool. Other thermal units use mechanical mixing to expose all of the matrix to the heat source.

CONDUCTIVE HEATING
This process transfers the energy from higher temperature matrix particles to those matrix particles at lower temperatures and in direct contact with the higher temperature particles.

BOILING POINT REDUCTION
The boiling point of a liquid is the temperature at which the partial pressure of the substance is equal to the system pressure. There is a direct relationship between the final treatment temperature and the system operating pressure. As the system is operating, pressure is reduced and the treatment temperature required for removal of compounds by volatilization is significantly reduced. The MCS system uses this principle of boiling point reduction by reducing the system pressure. The system pressure is reduced from 0" Hg (atmospheric pressure) to as much as 21" Hg.

AIR STRIPPING
Another important parameter that assists the desorption process is air stripping. Air stripping is the process of a carrier gas (in this instance, air) passing through the matrix and physically carrying the volatilized chemical from the matrix into carrier gas for recovery. The rate at which a chemical is stripped from the matrix depends on its vapor pressure and stability in water. Desorption of each chemical takes place throughout the entire process, not just when the boiling point of each of the chemicals is reached.

CHEMICAL VOLATILIZATION
Chemical volatilization consists of a two step chemical reaction. In the first reaction, the temperature of the chemical is increased until the boiling point is reached. The amount of energy required to raise the temperature from the initial temperature to the boiling point depends on the heat capacity (for the liquid phase) and the quantity of the chemical. After the chemical reaches its boiling point, the temperature remains constant while the liquid vaporizes. This is the second reaction. The heat of vaporization is the amount of energy required to produce a phase change from the liquid to the gaseous phase.

There are three primary components in any matrix:

• The contaminants
• water
• the matrix itself

The contaminants are typically present in the parts per million range (ppm), the water in concentrations ranging from 10–20%, and the remaining 80-90% is the matrix.

The contaminants and the water undergo the two step chemical reaction of volatilization while the matrix is only heated.