For larger plants, larger wells are installed and submerged centrifugal pumps or compressed air is used, the latter always as a last resort from a cost of pumping standpoint, although its simplicity and reliability appeals to many.
Submerged centrifugal pumps can be operated with steam turbine or motor set on top of shaft above ground. The motor operated set is the more economical, particularly if the current be generated at low cost.
Water Distribution Systems.
—The intelligent laying out of water systems and the pressure pumped against is a factor worth great attention. It is far better to have pumps of proper proportions for the service intended, even though it involves the use of a separated piping system.
Taking advantage of water once raised to a high level in its return to service is a power saving. For example: It is usual to locate ammonia condensers at a point where there is a good circulation of air. This is done to permit the winds to carry away the moist air from about the condensers, together with the heat delivered up through it and to the air by the discharged gas from the ammonia compressors. From the catch pan beneath the ammonia condenser the water can be diverted through the steam condenser and if the shell be bought sufficiently strong in the case of a closed condenser, the water can be delivered to the suction side of a pump which in turn will deliver it for house use for cleansing purposes. If a barometric condenser is used, the water is delivered to a hot well from whence it can be pumped or flow to sewer.
Pumps For Boiler Feeding.
—Dependent upon the size of plant and the pressure carried pumps are usually provided as follows:
- Small boiler plant up to 500 H. P. low pressures. Steam 80 to 125 lbs. simplex or duplex piston packed reciprocating pumps.
- Medium Boiler Plant up to 1,000 to 1,500 H. P. steam 125 to 150 pounds simplex or duplex outside piston packed reciprocating pumps.
- Over 1,500 H. P. the same or centrifugal type multi-stage pump motor or steam driven.
Heating Boiler Feed Water.
—Every plant, large or small, should be equipped with boiler water heating devices. These are so common and the practice so usual that it is scarcely necessary to mention it but the writer has seen plants where the exhaust steam from pumps and engines was being thrown to the air and feed water pumped into boilers at low temperatures. There are two types: closed and open. In the first named the water is circulated through tubes enclosed in a vessel, the tubes surrounded by steam. In the open type the steam is brought in direct contact with the water and performs the heating in this manner. The closed types are used on the principle that no oil carried in the steam is passed to the boilers, but the latter type are usually equipped with an oil separator that eliminates the oil and prevents danger from this source.