- Steam Theory
- 1. Basics of Steam
- 2. Steam Heating
- 3. Basics of Steam Traps
- 4. Steam Trap Selection
- Steam Trap Selection: How Application Affects Selection
- Steam Trap Selection: Understanding Specifications
- Steam Trap Selection: Safety Factor and Life Cycle Cost
- Traps and Orifices Part 1
- Traps and Orifices Part 2
- Casting vs. Forging
- Don't Get Steamed : Selecting Steam Trap Design
- Understanding Steam Traps
- 5. Steam Trap Problems
- 6. Steam Trap Management
- 7. Water Hammer
- 8. Steam Quality
- 9. Steam Distribution
- 10. Condensate Recovery
- 11. Energy Efficiency
- 12. Compressed Air / Gas
- 13. Other Valves
Methods of Preventing Stall
The following article will discuss Methods of Preventing Stall in heat exchangers. For a detailed discussion on the causes of Stall and its consequences, please visit the article: What is Stall?
How to Prevent Stall
Stall occurs if the inlet (primary) pressure is smaller than the outlet (secondary) pressure across a drainage device such as a steam trap, which prevents condensate from being discharged and can cause condensate to pool inside the equipment. To prevent this condition and allow condensate to discharge, the primary (inlet) pressure must be made larger than the secondary (outlet) pressure.
Theoretically, there are two ways to resolve Stall:
- A. Raising the primary (inlet) pressure, or
- B. Lowering the secondary (outlet) pressure
Effect of Trap Operating Differential Pressure
Raising the Inlet Pressure
Raising the inlet pressure can be achieved by changing system configuration to include one of the following:
- Mechanical pump/trap (e.g., PowerTrap® GT)
- Trap discharging in flash receiver with mechanical pump (e.g., PowerTrap® GP)
- Trap discharging in flash receiver with motorized pump
When using a mechanical pump or combined mechanical pump/trap, steam or air pressure is applied to the pooled condensate to raise the trap primary (inlet) pressure so that it is higher than the trap secondary (outlet) pressure. This forces the discharge of condensate before it pools into the equipment.
Lowering the Outlet Pressure
Lowering the outlet pressure requires the use of a vacuum pump. When using a vacuum pump, the pressure in the trap outlet piping (condensate return line) is reduced to below atmospheric pressure, thereby maintaining the differential pressure required for the trap to operate.
Selecting the most appropriate solution for preventing Stall requires careful investigation of various factors such as operating conditions, the configuration of the equipment, and the number of pieces of equipment installed. It is strongly recommended that a qualified technician evaluate the site before any decisions are made on which method to use.
|What is Stall?||Cavitation in Condensate Pumps|