The Heating in Direct Contact Heaters (DCH) is far more efficient than in the Tubular Heaters. The advantage of Direct Contact heaters is approach temperature between heating vapour and liquid is minimal and thus utilizes low grade vapour for liquid heating.
- Heating of liquid in DCH removes dissolved gases very efficiently from the melt as heating is done in counter current manner. The counter current operation effectively utilizes the latent heat of vapour in use.
- Melt coming out of DCH is diluted and de-aerated which subsequently enhances the clarification efficiencies.
- Besides its advantage towards the process, DCH does not require standby unit and reduces the pumping requirements.
- Direct contact heaters shall be in Stainless Steel construction.
To sum-up direct contact heater has following major advantages:
- Low temperature approach.
- Consumes low pressure vapour effectively
- SS construction leading to longer life.
- Requirement of lesser space
- Piping system is simple
- Melt entry with specially designed tangential box
- No entrainment by providing vapor and air separator
- Easy installation
- The system does not require any maintenance as well as mechanical cleaning like brushing tube as done for Tubular heater. This in turn reduces manpower.
System is provided with automation and thus does not require any manual interference.
- Temperature of melt outlet is controlled by regulating the vapor control valve
- NCG control valve to maintain the desired vacuum and also recover heat by connecting to low vapor Direct Contact Heater
- Monitoring of Parameters
- Melt temperatures
- Vapor temperature / pressure
- NCG vacuum