Background
Tata Steel Limited, is an Indian multinational steel-making company based at Jamshedpur, Jharkhand. In steel plants, furnace is mainly used for heating raw materials such as scraps, pig iron, molten iron etc. These are fed into the furnace for melting, as a result of which temperature inside a furnace always remains very high.
Problems
At TATA Steel plant, during the annual shutdown, the maintenance work was planned inside the furnace. The temperature of the furnace was more than 1160°C when it was operational. After the shutdown, the temperature of the furnace has to be bough down to ambient temperature to enable workers to start maintenance jobs inside it.
Initially, the temperature of the furnace was 1160°C, from that temperature to 200-250°C, the cooling rate was very fast due to high temperature difference. But from 200°C to ambient temperature, it takes a long time due to low temperature difference as the heat from the brick lines slowly comes to the surface. The workers have to wait for the temperature level to come down. Till then maintenance activities cannot be carried out. Thus, precious man-hour gets wasted and the shutdown process gets delayed, leading to an increase in cost.
Also, it would have been difficult for works to do maintenance works inside the furnace (confined area). The reason being, the air inside the furnace is always very toxic and harmful.
Our Solution
The main solution was to cool down the furnace in a faster way to save time, decrease shutdown time. Also, remove toxic gases from the furnace and provide fresh air inside it to enable workers to do maintenance jobs without causing any harm to them.
TDS installed best-in-class dehumidifiers, condensing units and blowers to provide dehumidified cool conditioned air. The supply was being done from inspection doors in the soaking zone.
The conditioned air created a positive pressure in the furnace and removed the contaminated air; and supplied fresh, dry, and cool air inside the furnace. During the entire job, the relative humidity was maintained between 50% to 60% and the temperature was kept under control, maintaining the comfortable environment inside the furnace.
This supply of cool air helped the furnace to cool down faster, from 200°C to ambient temperature. Which was not possible with the natural cooling of the furnace.
The TDS Dehumidification system also helped in eliminating toxic gases from the furnace and provided fresh air for workers. Thus, helped the workers to breathe fresh air and work continuously without any break. This helped the workers to increase their productivity.
Benefits
Feedback was taken from workers of different agencies who worked inside the furnace during maintenance. All were very happy and satisfied with the installed TDS system. They informed that during previous shutdowns the condition inside the furnace was never so friendly.
The effect of the dehumidification system on the productivity of the workers can easily be judged from the fact that all the maintenance jobs were completed before time and the furnace was lighted 12 hours before schedule.
Frequently Asked Questions
The furnace required significant time to cool from high operating temperatures to ambient conditions after shutdown, which could delay maintenance and affect the overall turnaround schedule.
Technical Drying Services used dehumidifiers, condensing units and blowers to supply cool, dry, conditioned air into the furnace, accelerating the cooling process.
Faster cooling allowed maintenance activities to begin earlier, helping TATA Steel complete the required work ahead of schedule and restart the furnace sooner.
The cooling process focused particularly on reducing the furnace temperature from around 200°C to ambient temperature, where natural cooling becomes slower.
The conditioned-air system helped remove contaminated air and continuously supplied fresh air, creating more suitable conditions for workers carrying out maintenance inside the furnace.
The solution used dehumidifiers, condensing units and high-capacity blowers to deliver controlled, cool and dry air into the furnace.
The furnace reached ambient conditions faster, maintenance work was completed ahead of schedule, and the furnace was lighted 12 hours earlier than scheduled.
