I X D U S T R I B L A N D EXGINEERISG CHEMISTRY
July. 1922
73 1
An Automatic Topler Pump'" By Frank Porter B U R E A U OF
MINES,WASHINGTON, D.
c.
?u' CONSECTION with the work in the Cryogenic Re-
The current to the solenoids is controlled by three relays,
search Laboratory, especially in the many analyses for helium, there is required a vacuum pump that will evacuate the apparatus and deliver the gas into a collection tube. A mercury pump that works automatically has been developed for this purpose and has given satisfactory service for almost two years. The vacuum pumps that can be used for work of this kind requiring delivery of the gas are those of the T6pler and Sprengel types. The pumps of the Sprengel type have several disadvantages, among which are the slow rate of gas delivery and danger of air being carried over with the mercury and thuc, contaminating the gas being pumped off. While the Topler pump is more satisfactory, most of the attempts a t designing a pump of this type that will work automatically and continuously3 have resulted in a very complicated glass apparatus which would require a skilled glass-blower to set up and keep in repair. In the apparatus developed in this laboratory electrical controls have been used and the glass parts are comparatively simple. The pear-shaped chamber, as shown in the diagram, has been found to give better results than the inclined Antrop0ff4 type, as gas is less liable to be trapped on the more nearly vertical sides of the former. A large leveling bulb works very satisfactorily for the chamber of the pump. The remaining parts are made from glass tubing of a size that the chemist with ordinary ability a t glass-blowing can handle. I n this description of an automatic mercury pump, the less important details have been omitted, as these could probably be worked out better from the particular conditions in the laboratory where it is to be used, and no doubt, too, many improvements over the one now in use can be made. The pump requires, for its operation, a supply of compressed air of about 15 pounds pressure, and a reduced pressure such as is given by a small oil pump or a good water-jet pump. The pressure or vacuum is applied to the mercury reservoir. by means of a 4-way valve shown in the diagram. This can easily be made from a 2-way brass cock by soldering in two side tubes and drilling the barrel properly. The cock should then be well ground so as to w7ork easily. To work this valve, a double solenoid is employed. A b o u t 3000 ampere turns in each will be needed, depending, of course, on the ease with which the valve works. One hundred and ten volts D. C. with a lamp in series or storage cells may be used.
A , B, and C, connected as shown. Relays operating with low
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Received February 16, 1924 Published with permission of Director, U S Bureau of Mines 3 Stetle, Chem N e w s , 102, 5/3 (1910), Pizd Mag 19, 863 (1910) 4 Electrochem I: , 28, 270 (1919) 1
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voltage are desirable. Condensers of about 1 microfarad capacity should be connected across the break to prevent arcing. The resistances, TI, r2, r3, are low resistances, 10 to 20 ohms, whose function is that of drop coils to supply a low voltage current to relays, when a current is flowing through to the solenoid. r7 is a similar resistance which may be adjusted so that the voltage across it, when current is flowing, neu- 6 high resistances, tralizes the voltage in battery Bs. 1*4, ~ 5 ~ 7 are about 200 ohms, adjusted so that the current from the batteries will not flow through these branches of the circuit enough to operate the relays other than the one to which they are directly connected. rg and r10 are similar resistances, about 75 ohms, in the battery circuit.
OPERATION Starting with the upstroke of the pump, the current flows through X2, holding the valve over to the position where pressure is applied to the mercury reservoir. When the mercury level reaches the platinum contact c, the battery circuit through B is closed, opening the circuit to solenoid 82. The weight pulls the valve to the middle position, opening the reservoir to the atmosphere and relieving the pressure. This slows up the upward movement of the mercury, preventing its slap against the top of the pump. The release of the pressure in the reservoir opens the circuit through C a t the manometer, and the circuit through 7-7 to the solenoid S2is closed, applying pressure again. The constriction d is adjusted so as to allow time for the mercury to reach nearly the top of the pump, when the system is under high vacuum, before the pressure is applied the second time. The voltage drop across r7 now neutralizes the voltage of Bs so that the solenoid circuit is not again opened until the mercury is forced down the capillary to the dish over which the gas is collected. This closes the battery circuit through A, which operpulling the ates solenoid SI, valve to the position where the vacuum is connected to the reservoir. At the same time the current through the drop coils, rl, r2,r3,holds back all the relay armatures until the mercury reaches the contact, b or a, which breaks t h e c i r c u i t through A , starting the pump on another stroke. The contacts b and a are placed a t points such that the circuit is not broken until the gas has had time to diffuse into the barrel of the pump. A switch is arranged so that either b or a may be used.
732
INDUSTRIAL A N D ENGINEERING CHEMISTRY
It is advisable to make the pump and valve and operate these manually for a time in order to determine where the contacts should be sealed in. The resistances should be wound a t first so that they may be adjusted to the operation of the pump before being made permanent. In general,
Vol. 16, No. 7
where a relay does not throw a t the time it should, the trouble can be remedied by increasing the voltage to that relay. If a relay tends to operate a t the wrong time, increasing the resistance in the lines which connect it to the other circuits will remedy this trouble.
Super-Defecation of Cane Juice' By W. D. Home 176 PARKAvE., YONKERS, N. Y
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N THE long struggle to The process here described has been devised to secure the advantages venting the disadvantages develop the raw sugar of complete precipitation of all the impurities that lime will throw of excessive alkalinity and industry1 defecationhas lime salts in the defecated down, without incurring the disadvantages of working u p highly ever Played an important alkalincjuice. This is accomplished, through a patented process, by juice. This combination r o l e . I n s o l u b l e matter, liming to a certain point between al?plinity to litmus and allplinity was finally accomplished earth, and trash, as well as through the expediency of to phenolphthalein, heating, settling, and decanting. The decanted juice is then treated with a specially prepared phosphatic reagent, t w o P r e c i p i t a t i o n s and P r e c i p i t a b l e substances, have had to be eliminated, Separations, as in double which precipitates the lime and other bases; the solution is slightly reheated and settled. The juice, thus raised considerably more than carbonation, but without while Preserving the Sucrose and invert sugar from deusual in purity, and lighter colored and cleaner, yields more abunthe need of such elaborate s t r u c t i v e a g e n c i e s and and expensive plant, or the dant and more readily worked sugars. The phosphafic precipitate use of so much lime-itself is used as cane fertilizer, thus conserving its cost. avoiding increase of color. Causticlime has proved to an expensive item. Treatbe the most suitable reagent ment with sulfurous oxide t o cause precipitation of phosphatic and certain organic con- had also to be avoided on account of dangers of inversion, stituents and to neutralize the acidity natural to all cane nonpermanence of the bleaching effected, and the fatal injuices. The most advisable amount of lime to use is often completeness of the precipitation of lime by this process, difficult to determine, for if too little is used the precipitation with the consequent troubles of cloudy sirup, scaling on heatof impurities is not so complete as might be, and if too much ing coils and tubes, dull looking sugars, and a frequent tendis added there follows a destruction of invert sugar, darkening ency to invert and deteriorate in the finished products. of the color of the solution, and increase of ash. I n this case, Of all the methods of precipitating the very small amount of unfortunately, there is no "happy medium," for the two op- residual lime from the defecated juice that depending upon the posing requirements overlap each other. use of phosphoric oxide proved the best, and in practice it Efforts were made years ago to harmonize these opposite has been found so easy and inexpensive of operation as to tendencies by adding a suitable amount of lime to produce eliminate any serious objections on this which so often proves complete precipitation and, after heating, adding sufficient to be the crucial point in newly proposed methods of operation. other reagents to neutralize the excessive alkalinity. This' PROCEDURE apparently rational procedure, however, has never become The cold, strained juice from the mill is limed to a point established, because it does not yield satisfactory results inasmuch as lime exercises a specifically selective activity about one-third to two-thirds of the way between alkalinity when applied to the juice of the sugar cane-first neutralizing to litmus and alkalinity to phenolphthalein, according to the more highly ionized acid bodies, then those of weaker determination through prior tests of the point of complete ionization, and finally forming insoluble precipitates with a Precipitation. This can be conveniently accomplished by series of mineral and organic substances, producing new treating 100 cc. of juice with successive portions of dilute bodies, some of them highly colored, which are only insoluble milk of lime (made by grinding 1 gram of the lime to be used i n an alkaline menstruum. This is the reason why the in 100 CC. of water), heating to about 90" C., filtering, and testprecipitate partly redissolves on the neutralization of the ing the filtrate with more limewater. In house operation the excess of lime, and for dragging all these impurities through degree of alkalinity can be determined by titrating with the factories in the production of millions of tons of raw sugar 0.1 N hydrochloric acid back to neutrality to litmus or by annually, with all the attendant disadvantages, not only to titrating with 0.1 AT sodium hydroxide to neutrality to phethe raw sugar maker, but to the refiner, who also bears all the nolphthalein and thus checking in a few s ~ o n d sagainst burden of excessive insoluble matter, color, and ash through- the desired alkalinity. The sufficiently limed juice, which now contains 0.01 to out the operations in the refinery. To meet the various exactions of this particular situation 0.02 per cent of lime beyond alkalinity to the most delicate the writer, after considerable work, succeeded a few years litmus Paperl is now heated to Cause Precipitation of the ago in developing a process, now protected by United States various Precipitable matters. and foreign patents, which meets the requirements of the case The temperature required for this step varies in different and should prove of benefit, not only in the fabrication of the juices, LQUisiana juice often giving apparently Complete precipitation a t 40.6" C. (105" I?.), while juice in Cuba raw sugar, but in refining it as well. A comprehensive review of the field indicated the need of needs a higher temperature; but in all cases, with the proper securing the benefits of the full amount of lime and of circum- addition of lime, complete Precipitation may be had a t temperatures far the point* 1 Presented before the Division of Sugar Chemistry at the 67th Meeting After proper liming the juice is heated and settled, the ofthe American Chemical Society, Washington, D C., April 21 to 26, 1924.
