We were discussing “Cements and
its types” and “Material
preparation technology in cement manufacturing” in our previous
posts. We have also see the concept of cement
manufacturing process and its selection in our recent post.
Today we are going to start here one very important
topic i.e. Safety requirement in cement manufacturing process. We will
understand the various terminologies and engineering concepts used in cement
technology with the help of this category, but first read this article “Coal grinding and drying in cement industries”.
Further we will go for discussion of firing
technology, clinker cooling and grinding, cement packing and dispatch,
pollution control and much more facts about cement technology in our next post
in this category of cement technology.
Safety Requirements
Special requirements intended to ensure safe
operation of coal grinding plants have to be fulfilled in order to eliminate
explosion hazards.
The potential existence of such hazards is due to the following factors
1.
Presence of combustible material in
finely divided form.
2.
Dust concentration in coal within
explosive range i.e. between the lower and upper limit of flammability.
3.
Oxygen present in concentration that can
sustain explosion.
4.
Sources of ignition may develop.
The explosive range of pulverized coal depends on
its physical properties such as its fineness and moisture content and on its
chemical composition such as its ash content and the amount of volatile matter
present.
In terms of oxygen concentration, the lower limit is
around 14 % by volume of air in which coal particles are suspended. Lowering
the oxygen content in the grinding circuit has the effect of raising this lower
limit. The ignition temperature of the mixture of pulverized coal and air is
also raised.
The most dangerous sources of ignition liable to
initiate explosion are ‘smoldering pockets’ that may develop in coal dust
deposits inside the plant.
In actual practice, the grinding plant normally
operation under inert internal conditions is designed to an explosion resistant
specification in that it is able to with stand pressure surges of a certain
range. Maintenance, repairs and inspection of vital parts should be carried out
only during plant shutdowns.
The principles and precautions applicable to coal
grinding and drying are even more stringently applicable to lignite which is
especially hazardous on account of its higher content of volatile matter.
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We will see other topic i.e. “Burning technology in cement manufacturing process” in our next post in the category of Steel and
cement technology.
I am very thankful to Mr. Subrata Bhaumik,
Independent cement consultant, for providing such beautiful information and
contents about cement technology.
Mr. Subrata Bhaumik has more than 50 (Fifty) Years
(1965 - 2016) of Experience in Cement and other related Industry covering more
than 100 assignments in cement plants with capacities ranging from 100 tpd to
10,000 tpd in India and abroad involving visit to 25 countries overseas in
connection with work.
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Author of this content, please click the Author profile link below.
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