Indian Washed coal dryer system_News

Indian Washed coal dryer system

Time : 2019-01-03 Writer : ddjx

The demand for washed coal in India has led to the planning of washeries:

Due to the geology; India depends primarily on open cast mining (85%) to meet growing demand. These mines are characterized by low stripping ratio (typically less than 1:1) with the mining zones

comprised of several seams banded together that are typically 30 to 70 meters (100 to 200 feet) in total thickness. Indian coals are predominantly high in ash. Run of mine (ROM) product ash quality is

generally greater than 30% ash on an ‘as-mined’ basis with the current average being 36-38%.

Coal Washing

Mined coal is of variable quality and is frequently associated with mineral and chemical material including clay, sand, sulphur and trace elements. Coal cleaning by washing and beneficiation removes this associated material,

prepares the coal to customer specifications and is an important step in reducing emissions from coal use. While coal preparation is standard practice in many countries, greater uptake in developing countries is needed as

a low-cost way to improve the environmental performance of coal.

In India, the coal beneficiation process generally consists of several steps. Washing plants are typically preceded by single or two-stage crushing to reduce the raw coal to a top size of 100, 75 or 50 mm.

The smaller fraction of raw coal (-13, -10 or -6.5 mm) that typically contains low ash (20-30%) is usually not washed. The specific size selected for washing or direct consumption would depend upon

the ash content and effectiveness of screening.

ADVANTAGES OF USING BENEFICIATED COAL

The advantages of using beneficiated (washed) coal have been proven through their increasing use in thermal power stations throughout the USA, Europe and other countries. These advantages are

numerous, ranging from purely economic savings to environmental benefits. Within India, the use of washed coals is gaining momentum as the impact of poor quality fuels is becoming apparent.21 The

general impacts and benefits of using washed coal (both direct and indirect) within the power generation process are given here:

a. Plant efficiency effects

b. Equipment system capacity

c. Auxiliary power equipment requirements

d. Propensity for slagging or fouling

e. NOx, SOx, particulate and opacity emissions

f. CO2 emissions

g. Maintenance costs

h. Emission Fees or taxes

i. Replacement power costs resulting from unit availability and capability

j. Fuels and transportation costs

Clean coal after washing need to be dried to put in use, usually will choose rotary drum dryer to dry it.