One Indian petrochemical was facing problems with its cooling tower. The required cooling water temperature was maintained easily during the winter months but during the summer months, the cooling water temperature often increased beyond 95°F (35°C).
Haldia Petrochemicals Ltd. (HPL) is a petrochemical complex located in Haldia, West Bengal, India. A refinery, a petrochemical plant and a central power plant have been operating at the complex since 2000.
In the petrochemical plant, HPL was facing problems with its cooling tower. The required cooling water temperature of 90°F (32°C) was maintained easily during the winter months. However, during the peak summer months (mid-May to mid-September), when the average wet-bulb temperature rose to 88°F (31°C), the cooling water temperature often increased beyond 95°F (35°C). The increased water temperature was putting a strain on the plant’s pyrolysis gasoline hydrogenation unit (PGHU), butadiene extraction unit (BDEU), benzene extraction unit (BEU) and C4 hydrogenation unit (CHU). Production losses were costing the plant Rs. 4 lakhs (nearly US$10,000) per day.
Additionally, a huge amount of power was being consumed by the CT fans. The cooling tower used nine fans, each with a 90 kW motor, for a total circulation capacity of 7.1 million gal/hr. The supply temperature of 1.9 million gal/hr of circulation water was deemed critical, as it catered to the exchangers of the main units. The company decided that it either needed to add three additional cooling towers or find an alternate solution.
After visiting two other plants with mist cooling technology, HPL decided to divert the water from three cells of its cooling tower to a mist cooling system. The system was designed, manufactured, installed and commissioned by Mist Ressonance Engineering Pvt. Ltd. in 2005.
After nearly three years of operation, the mist cooling system is still meeting HPL’s expectations. The system maintains a constant cold water temperature of 90°F at a WBT of 88°F, even during the summer and monsoon months, when the humidity often reaches 95 percent. The plant also has saved 270 kW/hr on fan power. The company was able to achieve a payback on the mist cooling system in less than one year.
Case Study: Haldia Petrochemicals Ltd.
May 1, 2008