Trombe: hydraulic compressor systems

The basic principle of a trombe: Water falling through a Venturi system sucks in air and compresses the air-bubbles, which are extracted at the lowest point of the system. Water pressure will drive the water up again to the height of the working head.

Referring to the figure at the right, water enters the system from the reservoir through the flume, D. It flows up to C, then pours down to B through small tubes (3/8" to 112" diameter), entraining air. The velocity down column E is such that the air remains entrained until it reaches the separating chamber, G. The water returns up column H to be discharged and the air is available via pipe K. The air pressure available is determined by distance G to L and working head of the water is determined by distance M to L. Not shown, a vent pipe may be installed into the separation vessel and extended to the water line. If the air overfills, the water level drops exposing the end of the vent pipe and venting air until the water again rises to submerge the entrance to the vent pipe.



Shown above is the compressor built by Taylor at Ragged Chute, near Cobalt, Ontario, similar to that constructed at Victoria. In the specific case at Victoria Mine, a concrete dam measuring 300 feet long and 10 feet high was built across the river that diverted water flow to a 6,000 foot long canal having a sectional area of 350 square feet. At the end of the canal, the water entered three vertical shafts 342 feet deep leading to an underground air storage chamber 282 feet long, varying in width from 57 feet to 18 feet, and measuring between 22 and 25 feet in height. This underground air chamber had a total capacity of 80,264 cubic feet. On the end of the chamber opposite the entrance pipes, a tunnel, 18 feet by 10 feet by 40 feet long, led to an inclined shaft which carried the water back to the river, a point 71 feet below the entrance point, thus giving the plant an effective hydraulic head of 71 feet. Two pipes lead from the underground chamber, a 24 inch air pipe carrying the compressed air to the mine, and a 12 inch blow-off pipe which served as an automatic governor for the plant. The 12 inch blow-off pipe served as a governor because when the air pressure in the chamber was too low, the water level rose and closed the blow-off pipe, thus preventing any escape of air. On the other hand, when the air pressure in the chamber was too high, i.e. above 117 psi, the water level was forced down, exposing the end of the blow-off pipe, and sending a mixture of compressed air and water to the surface, where it created a geyser effect.

The design production of the unit was 34,000 to 36,000 cubic feet per minute or free air. The performance was measured with the results below:

Air				Water
free air	suction	compressed	horsepower	flow	Head	horsepower	Eff.
cfm	psia	psia	HP	cfm	ft	HP	%
10,580	14	128	1,430	13,057	70.5	1,741	82.2
11,930	14	128	1,623	14.820	70	1,961	82.3
8,238	14	128	1,248	12.710	70.6	1.700	73.5