1. THE OLD CONCEPT OF STEAM "TRAP"
Steam trap traditionally has been considered as a "trap" for steam only. It means that steam trap had the only competence of discharging condensate water as soon as it is formed upstream of the trap.
That restricted point of view has firmly been fixed in our mind as consequence of the slow evolution of steam traps.
In fact, during decades the STEAM TRAP has been admitted as an ON-OFF VALVE unable to control energy, but only differentiate between water and steam (float and inverted bucket traps). The arrival of thermodynamic steam traps did not change that panorama but it contributed to waste energy reinforcing the old idea of "trapping".
Although the CONDENSATE CONTROL VALVE (thermostatic steam trap) was developed to improve and replace to old steam trap idea, most of the people had followed associating the on-off operation principle (trap concept) to the thermostatic steam trap.
Presently, manufacturers and users defend their positions according to their interest, experience or any other reason, without analyzing technically the consequences of using any of these concepts.
2. THE MODERN CONCEPT OF ENERGY CONTROL VALVES
Now a day the concept of steam trap additionally involves the idea of controlling the energy discharged though the valve, as well.
Then, we should to say steam traps when we talk about mechanical or thermodynamic steam traps reserving a new name, condensate controllers or condensate purgeurs for example, when we refer to thermostatic and bimetallic steam traps.
3. TRAPPING versus CONTROLLING CONDENSATE ENERGY
Concepts are easier understand when we analyze global problems (the tree does not allow seeing the forest).
Let us consider the simplified steam installation. The steam producer (boiler) is connected to energy consumers though the steam distribution line (high energy level) and the condensate return collector (low energy level).
Trapping steam exactly means create a physical barrier between the steam zone and the condensate region (the old "trap" concept). The trap discharge condensate at the saturation temperature (maximal remaining energy) producing the strongest flash steam generation in the return collector. That way, back pressure increases downstream of the trap and thermal water hammer very often appear. Excess of remaining energy is lost along the return collector or discharged to the atmosphere at the recovery condensate tank.
Controlling condensate energy means not only establish the boundary between two zones at very different levels of energy, but controlling the transition between both zones (the condensate "control" valve concept). Discharge of condensate is controlled thermostatically, which means that remaining energy is efficiently controlled up to required low level reducing flash steam generation and water hammering. Remaining energy is often 15 % reduced, steam consumption is saved at the same proportion and air contamination is reduced, as well.
The trap effect is only necessary in few applications whiles controlled discharge of condensate can be applied on the majority of situations. It should be clarified that most of typical "trapping" examples must be considered as "controlling" applications.
4. WHEN TRAPPING AND WHEN CONTROLLING CONDENSATE ENERGY
Conventionally "trapping" was suggested when we need to be sure that no condensate is upstream of the trap and "controlling" is used when we need to save energy.
Condensate return collector at large installations (oil refineries, petrochemical plants, etc) are very sensitive to endure persistent problems caused by pack pressure and water hammering. It is strongly recommended "controlling" condensate energy to solve that situations without widen installations.
The condensate energy controllers evolution (thermostatic steam traps) makes difficult to find applications where they can not be successfully applied.
5. CHECKING "TRAPS" OR "CONDENSATE ENERGY COTROLLERS"
No matter the type of steam trap we use it is necessary check them periodically. Obviously, the check method depends on the type of steam trap.
To check "traps" we only need to know whether the trap leaks live steam or not.
To check "condensate energy controllers" we need to know not only what is inside the thermostatic steam trap but the condition of that fluid. Said in other manner we need to measure its energetic efficiency.
6. INTELLIGENT CONDENSATE ENERGY CONTROL SYSTEMS
These systems combine condensate controllers with continuous monitoring devices.
The genuine of those systems, known as SteamWatch™ or SmartWatch™ (international patents), combines one Bi-Thermostatic Bimetallic Steam Trap with an electronic device capable of monitoring up to 4 independent parameters That way, it continuously measure whether energetic system efficiency or any kind of failure. The systems add the characteristic of setting and reparation on line without stopping its operation. That performance converts it in one formidable tool to solve very different problems (back pressure or water hammering in return collectors, improving energy efficiency, reducing maintenance costs, reducing energy consumption and atmospheric pollution, etc).
Monitoring system applied to the concept of "trap" have reduced interest due to the following reasons:
7. CONCLUSION
Along decades steam traps has slowly been mechanically developed.
At the present, the incorporation of electronics put on the hands of users intelligent condensate energy controllers (the newest and powerful steam traps of the 21 century), which solve satisfactorily most important problems derived from the growing of the size of installations and the continuous energy price increment. Intelligent condensate energy controllers easily reduce up to 15% energy consumption on steam installations.
Last modification: January-2003