[6] Contributed to Power by Thomas Franklin.

The Jet Condenser

The jet condenser illustrated in Fig. [72] is singularly well adapted for the turbine installation. As the type has not been so widely adopted as the more common forms of jet condenser and the surface types, it may prove of interest to describe briefly its general construction and a few of its special features in relation to tests.

FIG. 72

Referring to the figure, C is the main condenser body. Exhaust steam enters at the left-hand side through the pipe E, condensing water issuing through the pipe D at the opposite side. Passing through the short conical pipe P, the condensing water enters the cylindrical chamber W and falls directly upon the spraying cone S. The hight of this spraying cone is determined by the tension upon the spring T, below the piston R, the latter being connected to the cone by a spindle L. An increase of the water pressure inside the chamber W will thus compress the spring, and the spraying cone being consequently lowered increases the aperture between it and the sloping lower wall of the chamber W, allowing a greater volume of water to be sprayed. The piston R incidentally prevents water entering the top vapor chamber V. From the foregoing it can be seen that this condenser is of the contra-flow type, the entering steam coming immediately into contact with the sprayed water. The perforated diaphragm plate F allows the vapor to rise into the chamber V, from which it is drawn through the pipe A to the air pump. A relief valve U prevents an excessive accumulation of pressure in the vapor chamber, this valve being obviously of delicate construction, capable of opening upon a very slight increase of the internal pressure over that of the atmosphere. Condensed steam and circulating water are together carried down the pipe B to the well Z, from which a portion may be carried off as feed water, and the remainder cooled and passed through the condenser again. Under any circumstances, whether the air pump is working or not, a certain percentage of the vapor in the condenser is always carried down the pipe B, and this action alone creates a partial vacuum, thus rendering the work of the air pump easier. As a matter of fact, a fairly high vacuum can be maintained with the air pump closed down, and only the indirect pumping action of the falling water operating to rarify the contents of the condenser body. It is customary to place the condenser forty or more feet above the circulating-water pump, the latter usually being a few feet below the turbine.

Features Demanding Attention

When operating a condenser of this type, the most important features requiring preliminary inspection and regulation while running are:

  1. (a) Circulating-water regulation.
  2. (b) Freedom of all mechanical parts of spraying mechanism.
  3. (c) Relief-valve regulation.
  4. (d) Water-cooling arrangements.