Industrial visit is an efficient learning strategy that nullifies the distance between academia and industry. Students and faculty of the Department of Electrical and Electronics Engineering visited Dr Narla Thatharao Thermal Power Station (NTTPS) on November 21, 2022. The objective of the visit was to give an overview of the Thermal Power plant, which is a coal-based power plant where coal is transported from coal mines to the power plant by railway in wagons or a merry-go-round system.
The state-of-the-art construction and technologies amazed the students as they experienced an insightful industrial visit that exposed them to the actual working of a thermal power plant while enforcing their theoretical knowledge of Power Systems, Control Systems and Electrical Machines. Students from semesters one to four participated in the industry visit. Dr Somesh Vinayak Tewari, Dr Shubh Lakshmi, Dr Bhamidi Lokeshgupta, Dr Ramanjaneya Reddy U, and Dr Venkata Ramireddy Y were the faculty who accompanied the students.
A Detailed Account of the Industry Visit
Coal is unloaded from the wagons using wagon tippler units to a moving underground conveyor belt. This coal from the mines is of no uniform size. So, it is taken to the Crusher house and crushed to a size of 20 mm. From the crusher house, the coal is either stored in dead storage, which serves as coal supply in case of coal supply bottleneck or to live storage in the raw coal bunker in the boiler house. Raw coal from the raw coal bunker is supplied to the Coal Mills by a Raw Coal Feeder. The Coal Mills or pulverizer pulverizes the coal. The powdered coal from the coal mills is carried to the boiler in coal pipes by high-pressure hot air. The pulverized coal air mixture is burnt in the boiler in the combustion zone.
Generally, in modern boilers, a tangential firing system is used where the coal nozzles/guns form a tangent to a circle. The temperature in the fireball is of the order of 1300˚C. The boiler is a water tube boiler hanging from the top. Water is converted to steam in the boiler, and steam is separated from water in the boiler Drum. The saturated steam from the boiler drum is taken to the Low-Temperature Superheater, Platen Superheater and Final Superheater, respectively, for superheating. The superheated steam from the final superheater is taken to the High-Pressure Steam Turbine (HPT). In the HPT, the steam pressure is utilised to rotate the turbine, and the resultant is rotational energy. From the HPT, the outcoming steam is taken to the Reheater in the boiler to increase its temperature as the steam becomes wet at the HPT outlet. After reheating, this steam is taken to the Intermediate Pressure Turbine (IPT) and then to the Low-Pressure Turbine (LPT). The outlet of the LPT is sent to the condenser for condensing back to water by a cooling water system. This condensed water is collected in the Hot well and sent to the boiler in a closed cycle. The rotational energy imparted to the turbine by high-pressure steam is converted to electrical energy in the Generator.