Humidity and Temperature Control in Columns

Frequently Faced Problems

Crude oil is normally stored in tanks, from where it is passed through Columns, i.e Crude Distillation Unit (CDU) and Vacuum Distillation Unit (VDU), Fluid Catalytic Cracking Unit (FCCU), Hydrotreater Catalytic Reforming Unit (HCU) to get end product.

During maintenance in columns,welding, fabrication,riveting job, strip lining, nozzle replacement, trays replacement are carried out. As a result, the air inside the column is hazardous with presence of toxic gases/ fumes and insufficient oxygen.

The temperature & Relative Humidity inside the column increases to high levels (48º – 50ºC) because of welding work & presence of large amount of workers (100-200) at a particular time.

Also, oxygen level decreases drastically & presence of toxic fumes makes it impossible for workers to carry out their work continuously. Frequent interruptions & breaks takes it toll on the overall efficiency. Reduced effeciency further results to delay in completion of the job.

Problems :

• Toxic gases are injurious to the health of workers, engineers & inspection team.
• Productivity of the workers reduces.
• Quality of the work inside the column is severely affected resulting in frequent breakdowns, hence, more shutdowns are required.
• Shutdown period gets extended resulting in huge loss to the refinery.
• Untreated air facilitates condensation at night & humid places. This results to weak & poor welding.
• The time frame for the shutdown of columns is very limited. Hence, Maintaining right temperature & RH levels is necessary to avoid any delays and save organization from huge losses.

General Recommendation

The humidity and the temperature inside the column should be maintained at below 60% RH and temperature between 25º – 26ºC.