INDUSTRIAL A N D ENGINEERING CHEMISTRY
January, 1923
T h e Pumping of Liquids in Chemical Plant
33
s * I 2
By Clark S. Robinson MASSACRUSSTTS INSTITUTE
OF
TECHNOLOGY, CAHBRIDGB, MASS.
pulsating, and it is necesThe problem of transporting liquids in chemical plants is one sary to provide some means of the most frequent with which the chemical engineer has to deal. pumps were the f i s t t o equalize the flow and to Often the liquids to be handled are of the most corrosive character to be used for pumpprevent water hammer. and the wear and tear on pumping equipment cause serious concern ing purposes, and for that This is done by means of to the management. The improvements in equipment for this work. reason have been developed an air chamber which abby manufacturers in recent years haue, howeuer, made it possible and refined to the point of sorbs the shock by the comto handle dificult liquids economically in nearly all cases. I t is Standardization by nearly pression and expansion of the purpose of this article to indicate in so f a r as space is aoailable all manufacturers. In fact, air in it. the several types of pumping apparatus on the market and the uses the most important refineT h e foregoing figure for which they are most suitable. The following is a classification ments inrecent years have shows the essential features of pumping apparatus: been in the direction of conof the single direct-acting venience in repairs and in B-Pumps using compressed A-Mechanical pumps the selection of the best pump. air I-Reciprocating pumps I n this particular pump materials out of which to 11-Centriftigal pumps I-Eggs OY elevators the valve-actuating relay make them. As far as the ( a ) Volute pumps 11-Air lifts is operated by the piston handling of water and other ( b ) Turbine pumps C-Siphons itself, instead of the piston noncorrosive liquids is conIll-Rotary or gear pumps rod as is usually the case. cerned, reciprocating pumps The water valves are clearly are in use at the Dresent time that, have bee; in continuous operation for fifty years shown, the inlet valves below, and the outlet valves diiwith only occasional replacement of worn parts. Such charging into the air chamber above. The chief advantage of the single direct-acting steam pump lies in its extreme simpumps if properly cared for should last indefinitely. Reciprocating pumps comprise several types. The f i s t plicity and reliability. The steam consumption is also low, and perhaps the most common is the direct-acting steam as the piston must travel to the end of its stroke before it pump which is made both single and double. These direct- can reverse. The flow from the pump is, of course, exacting pumps have no flywheel to carry them by dead center, tremely pulsating. I n the case of the but depend on the mechanical operation of the steam valve to reverse the flow of steam to the steam piston, this being ac- double or duplex complished by a suitable device on the piston rod which actuates the steam valve for the piston either directly or through the aid of a steam relay. The pump is therefore side finishes its stroke double acting-that is, it pumps on both strokes of the pis- and waits for its valve q ton. On the single pump the piston actuates its own steam to be moved by the other side of the pump FIG. 2 before it can start on its return stroke. This makes the discharge of the pump nearly continuous and the air chamber is frequently unnecessary. As one or the other of the steam valves is always open, the pump will always start whenever the steam is turned on. This is not the case with a single pump, which must be started by hand. The duplex pump is therefore used where automatic starting is required. Fig. 2 shows a duplex pump of the usual type. Reciprocating pumps have the advantage that they will raise the liquid by suction to the pump, it being unnecessary to prime them. The distance that water can be raised depends upon the temperature and the altitude. Fig. 3 shows the lift possible at sea level for varying water temperature. It will be noted that when the water is at a temperature of 168' F. or more it must flow to the pump from above. Reciprocating pumps are made of a number of materials, for handling various liquids. The table which follows was collected by the Goulds Manufacturing Company and FIG.I-SINGLE DIRECT-ACTIXG PUMP represents the best available practice at the present time. It will be of interest to chemical manufacturers that the valve, while on the double or duplex pump one piston actuates manufacturers of this type of pump do not guarantee the the steam valve on the other cylinder, and vice versa. The life of the pump when handling chemicals, the purchaser asdischarge from a direct-acting pump is therefore decidedly suming the risk. A single direct-acting steam pump constructed of Duriron 1 Received October 25, 1922. * Contribution No. 36 from the Department of Chemical Engineering, is available which has a capacity of 15 gal. per min. at a Massachusetts Institute of Technology, Cambridge, Mass. pressure of 75 lbs. per sq. in. This pump is especially suitable
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TABLEI-MATERIALSFOR SPECIAL SERVICE PUMPS
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LIQUIDTO BE MATERIAL VALVES No. PUMPED USED 1 Acetic acid Lead or Regular (Concentrated) phosphor disk, etc. bronze 2 Acetic acid Enamel Regular (Diluted) 3 Acid mine water Hiah lead Regular 6ronze 4 Alcohol (Crude) All bronze Regular brass, also cast iron 5 Alkaline liquid Enameled Regular Regular 6 Alkaline water All iron 7 Aluminium sulfate Brass fitted Regular 8 Ammonia, All iron Regular ammonia water 9 Aniline water All iron Regular Regular 10 Beer All bronze Regular 11 Beer wort All bronze 12 Beet juice (Thin) Brass fitted Regular 13 Benzine, benzene All iron Regular Regular 14 Bichloride of All iron mercury 15 Cachaza (Sugar Brass fitted Large mill by-product openings, from which rum ball is made) 16 Calcium brine Regular Regular (Pure) Regular 17 Calcium chloride, Bronze adulterated with fitted sodium chloride Regular 18 Calcium acid All bronze sulfate (Concentrated) 19 Calcium acid Brass fitted Regular sulfate (Diluted) 20 Cane juice Brass fitted Regular Regular 21 Carbonate of All iron sodium Regular 22 Carbonic acid gas Regular in water Regular 23 Caustic carbonate All iron of soda (Bojling) Regular 24 Caustic chloride Hard lead of magnesium (Hot) All iron Regular 25 Caustic chloride of sodium Regular 26 Caustic cyanogen All iron Regular All iron 27 Caustic manganese All iron Regular 28 Caustic potash All iron Regular 29 Caustic soda All bronze Large 30 Caustic strontia openings, ball All bronze Regular 31 Caustic sulfide Brass fitted Regular 32 Caustic zinc chloride Regular 33 Cellulose Large fitted openings, ball Rubber or 34 Chlorate of lime Copper is best then bronze bronze and cast iron Enameled 35 Chloride of lime Large openings, ball Regular Enameled. 36 Chlorine and water CopperRegular 37 Chlorine (Dry nickelgas) manganese-alloy Regular Regular 38 Citric acid, All iron Regular 39 Coal-tar oil All iron 40 Copperas Large openings, hall
41 Copper sulfate 42 Creosote oil 43 Cyanide of
All bronze All iron All iron
Re
