Direct Contact (DC) Heaters are an alternative to plate and tubular surface heaters. DC heaters have high heat transfer coefficient (HTC) due to absence of resistances like liquid film resistance, condensing vapor resistance, resistance of scale and tube / plate material resistance. These operate at an approach of around 1°C in contrast to shell & tube / plate type exchangers which normally operate at an approach of around 5–7°C.
General Advantages of DC heaters include:
- Counter current operation with effective utilisation of the latent heat of the vapours used;
- Utilisation of lower grade vapours for heating.
- No requirement of –
- condensate lines;
- standby bodies;
- cleaning during the season;
- Heating surface area requirement of the plant is actually reduced by proper selection of their application;
- Designed for minimum pressure losses.
SED DESIGNED DIRECT CONTACT COUNTER-CURRENT HEATERS
DISTINCTIVE FEATURES:
Design features:
- Light-weight stainless steel structure with corrugated shell and rib supported deflectors.
- High turndown ratio (operational between 30% - 100% of designed flow without compromising its efficiency).
- Effective NCG removal due to compact sizing.
- Inbuilt entrainment separator.
- 0-1°C approach temperature.
- Designed for pressure as well as sub-atmospheric vapour conditions.
Optimized engineering:
- Low piping & valve requirements.
- Light weight structural layout as compared to tubular heaters with low floor space requirement.
Automated control:
- Controlling, monitoring and data logging for process parameters.
- Efficient measurement of temperature, pressure and level.
- Alarming for critical parameters (level and body pressure).
- Default switchover to manual mode.
Trouble free operation:
- No flooding.
- Precise level control ensures no backflow in case of sudden fluctuation.
- Can operate in fluctuating vapour conditions without compromising efficiency.
- No cleaning or maintenance required.
Power economy:
- Low head pumps are required due to negligible pressure loss as compared to tubular / plate type heat exchanger (PHE) thereby reducing power consumption.
Steam economy:
- Utilizes heat content of NCG (otherwise going waste).
- Utilization of low grade vapors improve steam economy of the plant.
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Direct Contact Heaters
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