New cement plant at high altitude
Bhutan, situated at the borders of India and Tibet, is a country of superlatives: The 7541 m high mountain Gangkhar Puensum is the worldwide highest mountain which was never mounted by a person. 80 % of the country is above 2000 m height. Two thirds of the country is wooded. All economic interests of the country are subordinated to the environmental and nature protection. Thus there are few industrial companies in Bhutan. Beside the food and wood processing industry the production of cement is significant (Fig. 1). A reason for Bhutan and India, to reactivate the project of Dungsam Cement plant that already had been planned in the 1980s and postponed in 2001 again due to security reasons. However, in 2005, Bhutan and India decided to resume the proposed project work and signed the order on September 9th, 2009 with KHD Humboldt Wedag India Private Limited. The contract agreement comprises the supply of main cement plant and machinery starting from crushing plant to packing plant. The entire plant will be spread over four plots measuring 132.5 acres. By 2012, Dungsam Cement Company will be producing about 1.36 million tons of cement per annum.
Bag filters for the essential positions
The order for the project contained the essential bag filter installations which KHD as prime contractor commissioned to Intensiv-Filter India. The Indian subsidiary of Intensiv-Filter Germany is responsible for engineering and manufacturing, whereat Intensiv-Filter Germany takes care of the quality management. KHD ordered all together six bag filters for different applications and volume flows: kiln/raw mill dedusting, coal mill dedusting, cement mill dedusting and two separator bag filter. The bag filter for kiln/raw mill dedusting is the biggest bag filter with a volume flow of 608 000 m3/h n.c., 8 m bag length and 2880 bags. The material of the filter media will be glass fibre with PTFE membrane. Due to the explosive dust within the coal mill, an explosion protection concept for the bag filter was also supplied by Intensiv-Filter. Rupture discs are stipulated to protect the bag filter in case of explosion. The remaining bag filter installations for the cement mill dedusting are designed for a volume flow of 70 000 m3/h n.c. each and an operating temperature of 115 °C. The two separator bag filters are dimensioned for 160 000 m3/h n.c., 115 °C.
The various activities of the project are in full swing. To keep on track with the time schedule, delivery dated for the bag filters is September 15th, 2011. The entire plant is expected to be operational by the end of 2011. After the plant is commissioned, it is expected to boost the economy of south-east Bhutan besides creating a major export corridor in the north-eastern India.