We are seeking solutions for automatic control of the relative humidity in an enclosed space, irrespective of the variations in weather or process changes.
The winding and packaging of wire coils is the finishing stage in the production of motor tyre bead wires. Winding and packaging are carried out in an enclosed area (Figure 1) of size ~13,000 sq ft. and volume ~1,80,000 cubic ft. Multiple entry/exit pathways are provided for the movement of material and people. Air curtains are provided in these pathways to reduce the outside weather conditions affecting the inside space. The finishing process requires the relative humidity (RH) of the ambient environment to be maintained within a range of 40% to 50% and a temperature of ~25 ºC. Currently, this is achieved using a combination (Figure 2) of chilling compressor, Air handling unit (AHU) of capacity 120 TR (Tons of Refrigeration), and connected heaters placed in the duct. The humidity control process is currently manual, i.e., compressor units and heaters are manually switched on & off by operators, based on the dry & wet bulb temperature reading in the enclosed area.
During monsoon, humidity levels increase drastically, which makes the manual control of RH a challenging task. Relative Humidity in this region (coastal) may shoot up to 90%, and any outage, even for as small as 30 minutes, increases the humidity levels. It takes a lot of time to bring the RH within the permissible range as the control is manual in nature. Productivity goes down if the RH is not controlled as the rework and downtime increases due to the stoppage of machines. Uncontrolled humidity (>50% in a few cases) also results in the rustiness of finished products (Figure 3), which starts appearing only after a few days and therefore goes unnoticed at the time of dispatch.
Over the years, AHU has been upgraded from variable speed, reciprocating compressors to screw compressors. In addition, heaters have been installed. These improvements, however, do not eliminate the manual dependency for control of humidity. Thus, we are seeking solutions for automatic measurement and control of humidity (between 40% – 50%) with temperature maintained around 25 ºC in the enclosed space, irrespective of variations in weather or any internal process changes like unit shut down, power failure, tripping, or any other parameters so that the overall energy efficiency and productivity of the plant is improved.