PT.GH EMM INDONESIA

ModificationProject of Rotary Coal Bunker of Wet Coal Bunker and Raw Coal Bunker in the PT.GH EMM INDONESIA

  Overview:after two units of PT.GH EMM INDONESIA are put into operation, main and auxiliary equipment are basically under stable operating state, but safe, economical and stable unit operation is adversely affected by coal blockage at the wet coal bunker and raw coal bunker.

  Coal used by PT.GH EMM INDONESIA for combustion is quite special and it is of high water contents and low caloric value lignite, which has high viscosity and disrupts argillization when meeting with water, causing coal blockage at the wet coal bunker. Due to this, 4 sets of coal drying systems are designed and built during the infrastructure construction to dry the wet coal while dried coal is featured by high water contents and temperature and large proportion of fine powder and tends to harden and block raw coal bunker easily. Although a series of relevant measures, such as adding coal poking hole, pickfront, electric vibrating device, electric heat tracing device and implementing system of pulling empty bunker regularly, have been taken, the problem of coal blockage remained unsolved radically. Due to serious blockage in the wet coal bunker and raw coal bunker, coal drying and pulverization system had to be started and stopped frequently to clean the bunker, which not only consumes large quantities of manpower, purchased coal and fuel, but also poses safety hazard of pulverized coal system explosion.

  By combining with existing products, our Company has formulated a set of dredging scheme suitable for special conditions on site, and we have made innovation in the following two aspects:

(1) Dredging effects brought by modification method of traditional single rotary dredging bunker at site are quite limited and any dead zone for dredging will be fully blocked again after operating for a certain period of time. Based on this, our Company has designed the modification method combining rotary dredging bunker of stock bin with rotary dredging bunker of scraper and dredged the section easily blocked comprehensively and innovatively.

(2) Control system uses PLC as controller to become a perfect control system that combines remote DCS control with several automatic operation methods and changes control method at long distance based on site condition without the necessity of local operation.

  In September 2012, 12 sets of activated dredging devices provided by our Company were installed properly at site and have kept stable operation after being put into use, thereby making site free from such problems as adhesion to wall and hardening, eliminating the need to clean bunkers regularly and saving large quantities of manpower and material resources. Successful modification of this project meant that our Company has reached a new level in dredging technology used for processing fire coal bunker with high viscosity and water contents and strengthened our product competitiveness in the market significantly.

  After implementing anti-blocking modification of raw coal bunker and wet coal bunker in the whole plant and undergoing rainy season in Indonesia (from October to March of the following year), 100% of coal used for combustion is supplied by PT.GH EMM INDONESIA itself wholly without purchasing coal in the past half year. Meanwhile, four sets of coal drying systems have not been shut down because of dredging the blocked wet coal bunker or pulling empty bunker; continuous operation of coal drying system has made it possible to pile and store coal in the dry coal shed and changed the previous practice of sending dried high-temperature coal into raw coal bunker directly. Dried coal can be cooled and delivered to raw coal bunker through material-taking machine, thus avoiding high-temperature explosion and combustion risks in the raw coal bunker; at the same time, after the successful application of anti-blocking modification of raw coal bunker, moisture contents of dried coal were increased to 53% from 51% and original dust problem existing in the coal handling system was also solved radically; Continuous and stable coal supply of raw coal bunker has realized the target of zero oil refueling rate in normal unit operation and considerably enhanced the safe, stable and economical operation level of unit.

Curve of coal supply quantity before modification	Curve of coal supply quantity affer modification