Improvement the role of coal as feeder energy alternative always is done, this thing has pushed does of research with main material of coal that is initially in the form of solid becomes liquid material. The engineering has yielded coal oil mixture (COM) coal water fuel (CWF) and coal liquefaction technology.
1. Coal Oil Mixture (COM)
At the time of oil crisis happened, the experts tries finds fuel which can change bunker c oil or fuel no. 6. This invention not only based on ability of just technology but burden of proof economically that this substitution fuel of course economic cheaper than bunker C. oil. One of this invention is coal oil mixture (COM). Some processes is done as follows :
a. Ultrasonic Process
This process developed by Coal liquid international of USA with elementary principle as follows :
Coal grind in pulverizes until measure 2000 mesh. With composition of pulverized coal 50%, bunker C oil 40% and freshwater 10%, input in mixing drawing and swirled. utilized water because water to have combustion ability (combustion capability). Informs Against this COM has not is stable, on that account flown through ultrasonic device developed. Ultrasonic functions to release water molecule from coal then blanketed by bunker C oil. In equipment ultrasonic, very small prilled, so that not happened aggression at prilled of that. After through process ultrasonic, COM yielded to become stable and can be kept storage in the tank equipped with by warm-up automatics (automatic heating) with tee Einstein characteristic temperature = 60C. Stabilization process done by equipment of this ultrasonic the cost is hardly minimum, less than one dollar cents per million BTU.
This can solve problem fuel leading to static stability and dynamic stability. Statics stability is ability of the mixture (COM) homogeneity to, either when transported and or when in moth-balls until required. Dynamic stability is rule of retention of fuel (COM) when flowing through burner pipe.
b. Common Process
At this process coal which have been grind, Bunker C Oil, water and additive (adder matter) swirled mechanically is in the tank mix (mixing drawing) by the way of agitation. Informs against completed and have been stable poured into storage tank.
this Additive in the form of dilution (surface active agent = SAA). molecule surface active this agent by one sides haves the character of hydrophotic. this SAA Character like soap, one the side of soap molecule can clean oil from surface, but also earns is foamy with water, both this characters works at the same. Soap of course has character hydropholic and hydrophotic. Molecule SAA operates on interface between grease and water molecules, between oils and coal. Without SAA the interface will not be stable after with SAA the interface becomes stable.
c. Wet Milling Process
In process of this coal is not necessarily be grind, but raw coal, together bunker C oil, water is added additive active agent (SAA) milled in ball mill. COM which have been stable poured into storage tank. Fundamental difference between COM boiler and B/C oil boiler is :
*) Fuel feeding the equipment differs in
*) Burner structure (burner) also differs in
Boiler must be added equipments of filter sack; bag to accommodate ash yielded by coal in COM. At attempt with this COM still be got inter Alia problems :
*) Ash formed result of combustion COM
*) Nozzle the burner is quickly abrasion, the hole is quickly big
In tip of holes always there is crust having black, also is in pipe burner always matter having white, anticipated SiO2, nozzle this burner is seven and must be cleaned every day once.
COM doesn't cause pollution, ash result of combustion in boiler is accommodated under boiler, while fly the ash covered with gas flute to filter sack. COM demonstration plant which in Incon Korea prefers bituminous coal which high of the caloric value, low of the ash content; 4% and volatile matter (VM) admits of tolerated until 45%. When the VM height, so whenever happened coal grinder, flown free air of O2 in water heater. Economic value of usage of this COM depend on the price of oil.
2. Coal Water Fuel (CWF)
Like known kerosene, obtainable diesel fuel and gasoline with coal liquefaction conversion process. Obtainable gas fuel with coal gasification process. One of process that is simple is modification of coal becomes a coal mixture having the character of liquid that is coal water fuel can replace burning oil which is one of petroleum product.
a. Raw Material CWF As component of standard utilized by coal having high caloric value (more or less 7000 kcal/kg) as compensation of usage of water so that caloric value CWF obtained enough heights also. Bitumen type coal raw material with high caloric value and wafting water content (inherent moisture) low is suggested so that constraint the low of caloric value CWF obtained able to be overcome. Actually earns also is utilized bitumen sub and or lignite, But both types of the has high wafting water content so that CWF yielded will have low caloric value. To overcome the thing must be done draining at temperature and high pressure. Clauses of raw material CWF is ;
1. Low ash content
2. Matter content flies bigger than 20%
3. Number HGI height must
4. Fouling and slagging low index
5. Sulfur content less than 1 %.
Beside doesn't contaminate air, ash content must be low to lessen modification fare of stove at dismissal of base ash (bottom ash). Matter content flies > 20 % to water down en kindling. In making of CWF utilizes smooth coal (- 75 microns) hence required hulling. On that account number HGI height must to lessen grind fare. Height ash melting point must obviates precipitation to of ash which is easy melts at stove interior (boiler). The happening of fouling and slagging can stop operation, on that account fouling and slagging need to be cleaned to return high temperature switching. Index fouling and slagging influenced by alkalies content and brimstone in ash. Side that is sulfur content must be low to prevent environmental contamination and interior corrosion boiler.
b. Additive
Additive is material added into mixture CWF and functioning to add the stability, mean prilled of the coal doesn't during old (2 month or more). There is also functioning additive dispersion to prilled of the coal. Additive addition ranged from 0,1 to 1,5 depends on kinds of the additive. From result of research it is concluded that good additive in the form of surfactant (surface activator reagent item) what can be consisted of surfactant ionic (anionic or cationic) and surfactant non-ionic. There is also other additive which the function to make mixture having the character of emulsion and stable. Because this surfactant type many variation, hence is required research specially suited for coal is being used to raw material CWF. Clauses of good additive is must be effective, be combustible in process of combustion and cheap.
c. Making CWF
Making technology of CWF is including simple especially if using coal raw material having high caloric value (more or less 7000 kcal/kg). Coal having low ash content (10%) grind to become 10 mm and then is milled with ball mill. Hulling is done with concentration of high solid (more or less 70% coal). Result of grind is done at one particular size separation (size classifier) at winnow measure 75 microns. Big oversize 75 microns distribute to equipment of reduction of water (dewatering) if required. The biggest particle size of coal doesn't fetch up all standing by 75 microns only, earns also bigger or smooth depended from its(the coal type. Level of concentration of mixture at squealer (mixing) determined when optimization of laboratory scale before all. For coal with quality of height, process of CWF earns more simple. After hulling earns direct is done squealer where at this additive phase is added. At low level coal with high wafting water content need to be done draining in advance at high temperature. Squealer taken place only during few minutes with high rotation (6000) and yields high stability (> 2 month).
3. Liquefaction Technology OF Embers Stone
At one time requirement cannot base on gas and oil, because its reserve tends to declines, if is not found new reserve. To economize the fuel consumption is improved usage of embers stone as one of alternative energy source. For the thing is tried to does liquefaction of embers stone. Coal liquefaction process is selected hydrogenation process (coal liquefaction directly) by choosing coal having low ash content (< 10 %). Attempt done at embers stone coming from sumatera south (banjarsari and kungkilan) in an autoclave having capacities 250 cc.
a. Coal Activity Principle Coal + 40 grams, catalyst + 0,40 grams (CoMo) added 60 grams tar oil fraction, packed into autoclave. Hydrogen gas poured into in autoclave with pressure 150 bars, then is heated be joggled so is reached constant temperature where gas pressure will go down. Gas yielded analyzed to calculate coal conversion becomes condensation considered from condensation yielded.
b. Result obtained : Coal conversion banjarsari 98,50% Kungkilan 92,50%. Gas yielded from this research got kinds and percentage of different volume from coal liquefaction result coming from banjarsari and kungkilan. Result of this initial research gives possibility hope is doing coal liquefaction in industrial scale.
Sources : Batubara and Gambut, Ir. Sukandarrumidi, MSc, Ph.D. Gajah Mada University Press