Lifts power station of steam power suralaya is operating since the year 1984 for example of case study. power station of steam power suralaya is designed similar to apply coal fuel Bukit Asam at level quality of average and worst.
Until the year 1988 hill coals Bukit Asam still be not able yet to fulfill requirement that is increasing out of 156000 tons in the year 1985, 936000 tons, and 1.500.000 tons in year the next year and in the year the 1987 requirement had reached 2,055 million its tons must will increase again.
Quality of the substitution coal has been laboured as possible fulfills quality of Bukit Asam hill coal. Things required to considered in usage of coal at power station of steam power is :
1. Performance
2. Availability, reliability
3. Environmental impact
4. Constraint and operation characteristic, and the impact to level of keeping
Review to the aspect is upper solely considers equipments is attached as according to the similar design and hereinafter the experience becomes base in completion of period to come.
1. Recognition of Public Quality Of Coal
The coal is marketing element of the quality at least consisted :
a. High heating value (kgcal/ka)
b. Total moisture (%)
c. Inherent moisture (%)
d. Volatile matter (%)
e. Ash content (%)
f. Sulfur content (%)
g. Coal size ; 3 mm, 40 mm, 50 mm h. Hard grove grindability index Other elements is required according to requirement having the character of public and also special. To complement data is upper usually is required unsure quality of like :
* Fixed carbon (%)
* Phosphorous/Chlorine (%)
* Ultimate analysis : Carbon, hydrogen, oxygen, nitrogen, sulfur and ash, sometime is required
* Ash fusion Einstein characteristic temperature
2. Influence Quality Of Coal
a. High Heating Value (HHV) HHV hardly having an effect on to operation of aspect : + Pulverize + Coal pipe, wind box + Burner Excelsior HHV hence coal stream every hour is increasingly low, so that speed of coal feeder must be accommodated, for coal with moisture content and the same HGI, with high HHV hence mill will operate under nominal capacity (according to design) or equally operating the ratio becomes lower.
b. Moisture Content Content moisture influences number of usages of the primary air. At coal with high moisture content will require primary air more to dry the coal at permanent mill exit temperature.
c. Volatile Matter Volatile content matter influences perfection of combustion and fire intensity Fuel Ratio = Fixed Carbon / Volatile Matter Excelsior fuel ratio hence carbon that is is combustible not more and more.
d. Ash Content Ash content will brought with combustion gas through combustion chamber and conversion area in the form of fly ash and elementary ash. Around 20% in the form of elementary ash and 80% in the form of fly ash. Ash content excelsior and depends on the composition influencing level of defilement (fouling), abrasion and equipments corrosion passed by.
e. Sulfur Content Sulfuric content had an effect on to level of cool side corrosion happened at element of air heater, especially if activity temperature lower than dew point sulfur, beside influential to dusty arrest effective at equipments of electrostatic precipitous
f. Coal Size Coal grain size limited at granule spread and harsh item. Softest item for measure; 3 mm, while harshest grain size up to 50 mm. Softest item limited by level of dustness and level of amenity controlled the flight of wind causing defiles area. Level of dustness and amenity flies that there are still be determined also by content moisture coal.
g. Hard Grove Grindability Index (HGI) Capacities mill (pulverize) designed at certain HGI. For lower HGI of the capacities, lower than the measurement value to yield the same fineness.
h. Ash Fusion Einstein characteristic Temperature Ash fusion Einstein characteristic temperature will influence level of fouling, slagging and operation soot blower.
3. Specification Of According To Design Power Station of Steam Power
a. Specification Of Coal Power station of steam power is designed similar for productive solvent of continue at burden 4000 MW by utilizing coal fuel, average/worst, with 4 fruit of mill operates and one fruit of reserve. Spread quality of coal according to the similar design is visible at tables : Clauses of Coal permitted to operate for power station of steam power Table :
b. Activity Short Exchange Data BoilerActivity short exchange data boiler shown to tables :
Table :
Medium number of fly ash is visible at tables :Table :
As for data about capacities pulverize is visible at tables :Table :
From table seen that pulverize design in capacities that is big enough. Capacities for HGI 50 = 630 ton/jam, with 70% fineness 200 mesh.From the description is inferential that replacement of coal fuel supplier for Power station of steam power, from coal mining area that one with coal from other mining area must be done specification of the coal is beforehand. This thing meant to avoid equipments damage of Power station of steam power.
Sources : Batubara dan Gambut, Ir. Sukandarrumidi, MSc, Phd. Gajah Mada University Press