Hot Oil System Auxiliary Tanks
Auxiliary equipment such as reserve, expansion, and deaerator tanks play a critical role in the safe, efficient, and long-lasting operation of hot oil (thermal oil) heating systems. These tanks protect the system's closed-loop structure and ensure operational stability.
Oil Reserve Tank
This is the main tank that stores the total amount of thermal oil required for the process. It is used for initial filling of the system and to compensate for any depletions that may occur during operation. It is equipped with level indicators and filling and drain connection flanges.
Oil Expansion Tank
Thermal oil, like all liquids, expands when heated, meaning its volume increases. In a closed-circuit system, this increase in volume can cause pressure to rise to dangerous levels. The expansion tank safely accommodates this additional volume created by the heated oil, maintaining system pressure. During cooling, it replaces the lost volume of the oil that shrinks. It is typically placed at the highest point of the system and is constantly monitored by level sensors. If the level falls below a critical point, it activates pumps that automatically replenish the system with oil from the reserve tank.
Oil Deaerator
This tank is where air, water vapor, and other volatile gases dissolved in thermal oil are removed from the system. These gases can cause undesirable conditions in the system:
- Cavitation: Gas bubbles formed inside the pump damage the pump's impellers and body, shortening its life.
- Heat Transfer Inefficiency: Gases in the oil accumulate on the heat transfer surfaces, creating an insulation effect and reducing the efficiency of the system.
- Oil Deterioration: Air (oxygen) breaks down the chemical structure of the oil at high temperatures and shortens its life (oxidation).
The deaerator is generally located on the return line to the central heating system. It also contains a filter that traps any coarse contaminants that may have accumulated in the system. This removes gases and keeps the oil clean.