Potential Applications of High Temperature Air Combustion Technology to Other Systems - High Temperature Air Combustion: From Energy Conservation to Pollution Reduction - page 352

• Optimization on the amount of lime as antiseptic and the relationship
between the amounts of lime as antiseptic and as desalination agent

• Determination of the optimum shape of RDF (dimensions, density,

strength, etc.)

In addition to the problems listed above, some combustion problems related to
the manufacturing of RDF also remain to be solved. RDF contains lime to control
the generation of toxic substances such as hydrogen chloride gas and dioxin. How-
ever, the quantitative database related to desalination, including the optimum desali-
nation temperature and temperature dependency of desalination speed, etc. is not
satisfactory. The problems related to RDF combustion process are as follows:

•Development of the control technology to suppress the formation of pol-
lutants in a furnace (NO x , SO x , particulate, chlorine substances, toxic
metals, etc.)
• Monitoring technology for pollutants (particulate, chlorine substances,
toxic metals, etc.)
• RDF supplying method (stability of supply, feeding positions in the case
of an air bubble fluidized-bed, etc.)
• Selection of the optimum combustion furnace (stoker, air bubble, or cir-
culating fluidized-bed, rotary kiln, etc.)
• Combustion method (simple combustion, partial-combustion gasification,
thermal cracking/combustion, thermal cracking/melt combustion, etc.)

• Measures for corrosion of heat exchanger tube

The problem of municipal waste is becoming more and more serious and the
scope of the issue has expanded far beyond the range of RDF production and
combustion technologies. Regarding RDF production technology, energy saving and
environment protection measures must be developed. Combustion technology for
RDF must be developed to achieve higher efficiency and more environmentally
benign characteristics.

6.3 BURNING OF COALS AND LOWGRADE COALS

The traditional methods for the conversion of coal to energy are given in Reference
11. The developments of advanced methods for burning coal are under way at many
institutions and laboratories, including International Flame Research Foundation
(IFRF), Toyohashi University, Shizuoka University, University of Utah, Ohio State
University, Pennsylvania State University, and MIT. An attractive feature of using
high temperature air, in place of low or room temperature air, is to convert coal
(including low grade coals and solid wastes) into clean gas of uniform gas compo-
sition and to eliminate the ash, particulates, and vapors that are formed during normal
burning of the coal. The heating value of the gases evolved from coal gasification
is around 2000 kcal/ . The slag is molten and can be vitrified. The issue here is
either to increase the heating value of the gases evolved or to develop an efficient
method for burning low calorific value gas. If these gases are burned using high

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