Water Tuyere

[Maillemaker]

What is a water tuyere and how does it work?

I recently purchased Practical Blacksmithing by M.T. Richardson, and on page 48, there is a rather confusing diagram of a masonry forge, connected to a barrel of water with pipe.

What is written is about as informative as the diagram: "The water keg rests on a bracket fastened to the wall, and, as shown in the illustration, the pipes extend downward and along the ground to the forge, and then beyond it. The pipes have caps on the ends. I use an angle valve, as shown, for shutting off water from the pipes."

I am baffled. The diagram doesn't show any kind of pump to circulate the water, or any other device. Simply a forge, hand crank blower, and a barrel of water.

[pkrankow]

The picture isn't the greatest

Ever hear of convection? The barrel is located above the tue, The hot water exit is at the top of the tue, and the cold inlet at the bottom. The barrel is plumbed up so the cold water is leaving the bottom of the barrel and the hot is going in the top. While it is not very well shown the hot pipe is above the cold the entire way. As long as the pipes are filled with water there will be a natural pumping action from heat rising and cold settling.

Old cook stoves with add-on water heaters function under this principle.

Phil

[Phil H]

The water cooled tuyere that I have is a cast iron device that takes the shape of a tapering tube 16" long, 6 3/4" dia. at the wide end, and 4 1/4 dia. at the narrow end. It has a hole down the middle that tapers from 2 3/4" to 1 1/4". I would guess that the wall thickness is about 1/4", leaving a water chamber inside it. The large end fits over the bellows nozzle, and I imagine a short bit of 1" waterpipe fits in the other end as a sacrifical nozzle. Viewed end on, the large end has 3 one inch threaded holes for the waterpipes. Only 2 are used. The lower hole is connected to the bottom of the water tank. The uppermost hole is connected higher up the water tank. When the water in the tuyere becomes hot it becomes less dense, and us pushed up by the denser (and therefore slightly heavier) cold water which is pushing down. The hot water rises and the cold water falls. The result is that the water circulates and provides a constant supply of cooler water to the tuyere. This keeps the tuyere from overheating and burning or melting the tip. It's called thermosiphon, and is quite effective if you're not in a hurry. Most solar hot water systems use it, and so did early Model T Fords (no water pump!).