Coal is solid fuel containing ash, therefore exploiting of coal will entangle expense of height for equipment required for handling (coal handling) and coal firing. That is of all aim to insulation dirt ash and. Handling of coal requires security, because there are some handling internal issue of inter Alia coal :
a. Coal can be combustible x'self
b. Coal can generate explosion
c. Coal can generate contamination, if there are the dirt high wind scattering everywhere
COMBUSTIBLE X'SELF
Coal can be combustible x'self after experiencing process that is in phases that is :
1. First phase : originally coal will permeate oxygen from the air inch by inch and then coal Einstein characteristic temperature will go up
2. Second phase : as speed rising Einstein characteristic temperature effect of coal permeates oxygen from the air increases and Einstein characteristic temperature then will reach 100-140 0C
3. Third phase : after reaching Einstein characteristic temperature 140 0C, vapour and CO2 will be formed
4. Fourth phase : until Einstein characteristic temperature 230 0C, insulation CO2 will continue
5. Fifth phase : if Einstein characteristic temperature has resided in to 350 0C, this means coal has reached its flash point and would quickly combustible
COMBUSTIBLE CAUSES X'SELF
Coal is fuel organic and if direct contact with air in a state of high Einstein characteristic temperature (for example endless dry season) will be combustible x'self.
This situation will be quickened by :
a. Reaction of thermal (vapour and oxygen is air), this thing which very often happened
b. Bacteria
c. action of Catalyst from inorganic objects
While possibility that the happening of combustible x'self especially inter Alia :
a. Low carbonization
b. Its sulfur content height (> 2%). Sulfur content boundary threshold is better if 1,2%
SOLUTION of COMBUSTIBLE COAL X'SELF
When coal is piled up place of accumulation closed (indoor storage) hence having to be made regulation that the storage warehouse clear of coal dirt sediments, especially found surface equipments. Thereby hence its needs treatment that is continuous and constant. If place of this open accumulation (outdoor storage) hence better be selected plane place and not damp, this thing to avoid infiltration of dirt (impurities).
For coal having matter flies high need to be utilized sprinkler. Storage of coal which too old also endangers, at longest is better if 1 month.
PILE HEIGHT
Height of coal heap pile of course difficult to be determined because each place of accumulation has condition x'self for example climates, dampness, irradiating.
CHECKING EARLY TO COMBUSTIBLE SYMPTOM
a. Temperature Checking
To know maximum Einstein characteristic temperature from determinable coal pile of 1-2 m under surface from heap. Its way : hole create vertical is assisted with perforation pipe. Usefulness of pipe that hole was not piled up coal again medium usefulness of perforation that Einstein characteristic temperature in hole equal to Einstein characteristic temperature in pile.
b. Coal can generate explosion
Coal dust explosion is because :
1. Dirt particle size : and 20 mesh (= 0,833 mm) 2. There is relation between matter flies and degree of detonation Volatile Ratio = Volatile (%) / Volatile (%) + Fixed Carbon (%) If volatile ratio and; 0,12 hence possibility that the happening of coal dust explosion always is exist. If dusty component in coal dirt and; 70-80% hence not necessarily fear danger of explosion. Condition to burst there will be when smooth particles enough the floating time. Also existence of burner gas in air can assist the happening of detonation.
c. Way of operation of explosion
1. Applies inert gas (N2). This gas enough expensive in price, besides also quickly evaporates so that always must be investigated valve the pressure. Places this N2 gasometer in grind coal storage (pulverized coal bin), also is part of filter (B/F)
2. Done sweeping periodically to avoid forming of sediment of coal dirt
3. Eliminates possibility that source to reach of ignition point in installation
4. Pays attention to, searched and found source of burning early possibly
5. In the case of coal hoard is closed over with plastic to labor that concentration of O2 less than 12%. At open hoard, usage by using sprinkler system automatic would hardly assists in business is preventing coal burning.
Its way : control panel operator (CPO) in pipe put in coal hoard then stele at certain Einstein characteristic temperature. If coal hoard Einstein characteristic temperature increases and exceeds Einstein characteristic temperature stele in COP, hence automatic sprinkler will work x'self sprinkles the coal hoard.
Treatment of coal dirt
Sheet plastic coal hoard cover conclusion is best, labored not to apply plastic is having colour dark. Hoard is compacted with bulldozer to lessen presents it oxygen in in between coal. At open coal hoard of surface of hoard better be sprayed with dilution granulating. This dilution is additional product from oil miller.
Sources : Batubara and Gambut, Ir. Sukandarrumidi, MSc, Ph.D. Gajah Mada University Press