Original situation
A tower of eight drying cylinders was fed from a pressure-reduced header at 3 bar g, each cylinder draining through its own steam trap. Six cylinders reached 150 °C; the seventh ran at 100 °C and the eighth, at the bottom of the tower, at 80 °C.
Technical enhancement
- A recirculating Jetomat® steam ejector (Baelz), driven by 8 bar g steam taken ahead of the pressure-reducing valve, discharges into the cylinder header.
- The eight cylinder traps came out. Every cylinder drains untrapped into one separator.
- The separator’s vapour is the Jetomat’s suction: a closed recirculation loop. Condensate leaves through a single trap.
- Installed in 2022.
The result
All eight cylinders now run at 150 °C. Fabric by fabric, as reported by the plant:
| Fabric | Before | After | Speed | Steam |
|---|---|---|---|---|
| Fabric 1 | 3 bar g · 12 m/min | 3 bar g · 23 m/min | +92% | same |
| Fabric 2 | 3 bar g · 12 m/min | 2 bar g · 12 m/min | same | −24% |
| Fabric 3 | 3 bar g · 25 m/min | 3 bar g · 50 m/min | +100% | same |
| Fabric 3 | 3 bar g · 25 m/min | 2.5 bar g · 50 m/min | +100% | −13% |
- ~Twice the fabric speed on the same steam, or the same speed on 13–24% less steam
- One trap instead of eight
Why it works
In a trapped cylinder, condensate builds up until the trap opens, and a film of water on the shell becomes a thermal barrier. In a tall tower the lowest cylinders suffer most, which is why the bottom two ran cold. With recirculation, steam blows through every cylinder and sweeps the condensate out, so all eight heat at full temperature. The variable nozzle holds the header at the pressure each fabric needs.
Takeaway
When the bottom cylinders of a tower run cold, the dryer is not short of steam; it is full of condensate. Recirculation puts the whole tower to work.
