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The DELTA Trap works by combining venturi technology with the orifice, so:
- part of the capacity of the DELTA Trap is related to the size of the orifice
- part is also related to the back pressure that is generated inside the venturi
It is a combination of the pressure drop across the orifice and the back pressure generated in the venturi that gives the DELTA Trap its overall capacity.
As the condensate passes through the orifice of the DELTA Trap there is a pressure drop. On the upstream side of the orifice the condensate is at the same pressure as the steam and it has a high energy content. As the pressure drops across the orifice, the temperature and pressure of the condensate reduces, so it contains less energy.
However, energy cannot be destroyed, so the transfer of energy between the HP upstream side and the LP downstream side causes some of the condensate to be converted into ‘flash’ steam. The higher the pressure difference across a trap, the more condensate has to be converted into ‘flash’ steam.
The DELTA trap uses this flash steam to create a back pressure inside the venturi
As the condensate is forced through the orifice of the DELTA Trap by the upstream pressure, the resultant pressure drop generates flash steam. This flash steam is about 1000 times the volume of the condensate, so the sudden expansion results in the condensate being accelerated in the venturi of the DELTA Trap. This sudden acceleration creates an equal and opposite force or back pressure inside the venturi, which restricts the flow of less dense steam through the orifice, while allowing the denser condensate to be ejected.
Because the amount of flash steam changes depending upon the operating conditions then the resultant back pressure also changes. This is then regulating the flow of condensate through the trap and hence gives it its variable capacity characteristics.
As less condensate arrives at the trap there is less pressure forcing it through the orifice, but because the temperature of the condensate has reduced, there is less flash steam generated. The percentage of flash steam drops and the mass flow reduces.
The capacity of the DELTA Trap is a function of the orifice size and the dimensions of the venturi section. By utilising the natural laws of physics, i.e. the change in the amount flash steam with change in pressure, the capacity of the DELTA Trap can vary with the changes in process conditions. The internal dimensions of the DELTA Trap are designed in such a way that the capacity of the DELTA Trap changes with the changing capacity of the application.
Hence the DELTA Trap works on varying loads from minimum through to maximum capacity!
CONVENTIONAL TRAPS VS DELTA VENTURI ORIFICE STEAM TRAPS
A steam trap keeps steam in the system and allows condensate to be discharged at certain points as it forms.
There are various types of conventional steam traps such as:
– float and thermostatic (ball float type)
– inverted bucket
– thermodynamic (flat disc type)
The majority of industry has always used conventional mechanical steam traps that have bulky moving parts such as buckets or floats and have oversized orifices that when they start to leak or fail, pass excessive amounts of steam back into the condensate return system thereby wasting boiler fuel to generate that steam. These traps require continuous maintenance as they are prone to failure due to their mechanical nature and also require expensive spare parts that need to be fitted when these traps fail resulting in costly loss of production and additional labour costs.
MECHANICAL TRAPS open in the presence of condensate and close in the presence of steam. The open/close mechanism is activated by internal floats, buckets, bi-metals, bellows or discs. They cycle several times a minute and a couple of million times a year, resulting in wear and failure. They have a 3-5 year lifetime.
With the new Delta DSV™ Steam Trap this excessive steam loss is eliminated through the unique orifice venturi design which has no working parts and therefore requires no maintenance or spare parts and eliminates loss of production through failed steam traps. The Delta Steam Trap is a fit and forget type trap that allows the plant uninterrupted production and improved heat transfer. Delta Venturi Orifice Steam Traps have an expected lifespan in excess of 30 years.
CONVENTIONAL TRAPS VS DELTA STEAM TRAPS
1. Fail open and waste steam
2. Mechanical parts requiring maintenance
3. Oversized orifice
4. Spare parts required
5. Large heat loss off big body of trap
6. Backs up condensate between cycles
7. Fair to medium resistance to wear
8. Fair to medium resistance to water hammer
9. Ongoing specialised testing required
10. 1 Year guarantee
1. Cannot fail open and waste steam
2. No moving parts = no maintenance
3. Precisely sized orifice
4. No spare parts required
5. Minimal heat loss off very small body
6. Continuous discharge – does not back up condensate
7. Excellent resistance to wear
8. Excellent resistance to water hammer
9. No specialised testing required
10. 10 Year guarantee