Jawaharlal Nehru Technological University Hyderabad B.Tech III PETROLEUM REFINERY ENGINEERING Previous Question Paper (August/September - 2021 - R18)

The Indian oil refining industry has evolved from a small-scale operation to one of the largest in the world. The journey began in 1901 with the establishment of the Digboi refinery in Assam by the Assam Oil Company, which remained the sole refinery for several decades. Post-independence, the government prioritized energy security, leading to the establishment of refineries at Mumbai (Burmah Shell and Esso) and Visakhapatnam (Caltex) in the 1950s.

The creation of the Indian Oil Corporation (IOC) in 1964 marked a turning point, leading to the commissioning of public sector refineries at Guwahati, Barauni, and Koyali. The 1970s saw the nationalization of foreign oil companies, consolidating the industry under public sector enterprises like IOC, BPCL, and HPCL. The 1990s liberalization era opened the sector to private players, resulting in the establishment of world-class, high-complexity refineries such as Reliance Industries' Jamnagar complex and Nayara Energy's Vadinar refinery.

Today, India is a global refining hub with a total installed capacity exceeding 250 million metric tonnes per annum (MMTPA). The growth is characterized by a shift toward high-complexity refineries capable of processing heavy and sour crude oils, integration with petrochemical production, and a transition toward meeting stringent BS-VI emission standards.

Salt content in crude oil, primarily in the form of chlorides of calcium, magnesium, and sodium, poses significant operational challenges in refinery units. The primary effects include:

1. Corrosion: At high temperatures in the atmospheric distillation unit, magnesium and calcium chlorides hydrolyze to produce hydrochloric acid (HCl), which causes severe corrosion in overhead condensers and piping.
2. Fouling: Salt deposits accumulate on heat exchanger surfaces and furnace tubes, significantly reducing heat transfer efficiency and increasing fuel consumption.
3. Catalyst Poisoning: In downstream units like hydrotreaters and catalytic reformers, residual salts can act as poisons, deactivating expensive catalysts and reducing product yields.
4. Operational Instability: Salt accumulation can lead to plugging of equipment, necessitating frequent shutdowns for maintenance and cleaning.

To mitigate these effects, refineries employ desalting units, where crude is washed with water and treated with demulsifiers in an electrostatic field to remove salts before the oil enters the distillation train.