April 1G, 7.933
INDUSTRIAL
AND ENGINEERING
CHEMISTRY
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Gas-Circulating Pumps for High-Pressure Service C. H. S. TUPHOLMB, 32 Russell Hill, Purley, Surrey, England I N THE CLAUDE PROCESS for the manufacture of synthetic
ammonia, the gases enter the synthesizing apparatus at a pressure in the region of 1000 atm., and this process, using one catalytic tube, gives a yield of approximately 50 per cent. By arranging four such tubes in a series, it is possible to convert all but a comparatively insignificant amount of the gas coming from the
FIGURE 1.
equalized. In consequence of this, the only effective power required for operating the plungers is that necessary for overcoming the difference in pressure between 850 and 1050 atm., so that the frame and driving gear can be made lighter to correspond with the lower stresses to which they are subject. The plungers are driven by oil columns, which transmit to them the
SECTIONS THROUGH A 1000 ATM. (14,200 L B . P E R S Q . I N . ) GAS-CIRCULATING P U M P WITH HYDRAULIC D R I V E FOR HYPERCOMPREBBOR PLANT MANUFACTURING SYNTHETIC AMMONIA
compressors into ammonia. In the Claude process, as formerly operated, the gas left over from the fourth catalyzer tube, still at a pressure of some 850 atm., was allowed to expand down to 25 atm. and was then added to the fresh mixture for synthesizing. Obviously, this procedure involved a loss of a certain amount of energy, which was thought to be compensated for by the simplicity of the plant. The efficiency of the Claude process was already pretty high, but, in order to raise that efficiency still further, certain European synthetic plants now collect the gas left over from the catalyzer tubes by means of a circulating pump, which is compressed from 850 up to 1050 atm. and then converted as far as possible into ammonia in an additional catalyzer tube. An entirely new type of circulating pump has been developed by a Swiss firm for this service (Sulzer Bros., Winterthur), the design of which is based to some extent on that of the supercompressor for high pressures used in the synthetic ammonia industry. Details of the design of this pump are shown in Figure 1, from which it will be seen that it has two single-acting vertical cylinders, the pistons of which are operated hydraulically. This design is claimed to give good pressure distribution; it can, in this respect, be compared with that of double-acting •sing) *vlinder pumps. Another feature of this pump is the mus jm shape of the cylinders, adopted from the hypercompressor (Figure 2). This is designed to compensate for any weakness caused by the holes for the valves and offers greater security against breakage. The cylinders of the double-acting horizontal machines, in contrast with this method of construction, have two stuffing boxes and various passages for valves which greatly reduce the strength of the material. The oil pistons for driving the two plungers are connected by a U-shaped tube, through which the pressure on the two sides is
motion of the horizontal primary pistons. The other constructional parts—stuffing boxes, valves, auxiliary pumps for the oil drive, safety devices, etc.—were also taken over from the hypercompressors. T ^ oil delivered under pressure for cylinder lubrication (the sealing oil for the stuffing boxes and the make-up oil for the hydraulic drive) is supplied by an independent electrically driven pump. The electric motor driving this pump is electrically coupled with the motor driving the gas-circulating pump, and is blocked by a relay in such a manner that the motor driving the gas-circulating pump can be switched in only when the oil pump is working. A gear-wheel oil pump, coupled to the main shaft, supplies lubricating oil under pressure to the mechanical parts, such as main bearings, cross head bearings, slippers, etc. At the same time it supplies oil under pressure to the auxiliary pump of the hydraulic drive. A circulating pump of this type has been in service in the nitrogen works of the Gewerkschaft Victor, Rauxel, since January, 1931. It was built for a suction volume of about 8000 cu. m. and an end pressure of 1000 atm., the power required being 150 B. h. p. As a matter of fact, the pump is working today between pressures of 880 and 1100 atm. The pump is driven by an electric motor through a belt with a belt-tightening device. Since the circulating pump has to take up all the gas left over from the catalyzer tubes, it is necessary to be able to regulate the speed within very wide limits, corresponding to the quantity of gas available at the moment. At first, the installation of a 3-phase generator, driven by a d. c. motor, was considered. The gas-circulating pump would then have been driven through a short-circuited runner and the speed would have been regulated by altering the periodicity. The periodicity could easily be varied with the described method of connections, by regulating the shunt of the d. c. motor. This
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E D I T I O N
solution, however, was found t o be too costly, and the machines would also have taken u p too much room. Regulation b y the brushes could also n o t c o m e into question since the motor is installed in a room where explosions might occur and has consequently to be totally inclosed. Finally, it was decided to install a 3-phase motor with adjustable pole windings and regulation of the rotor through resistances. T h e stipulated output was 145 kw. at 1465 r. p. m. and 100 kw. at 980 r. p . m. T h e torque is the same at both speeds. T h e supply i s 380 volts, 50 periods. T h e motor w a s provided with t w o stator windings and t w o rotor windings (6-pole and 4-pole) in an air-tight casing with t h e slip rings outside. T h e starter is of the open type.
Vol. 11, N o . 7
T h e plant w a s put into service without a n y trouble and could immediately b e used for producing ammonia. The savings anticipated from t h e plant have, i t is stated, also been realized.
Patents A G R E E M E N T O N CRACKING PATENTS P A T E N T RIGHTS in t h e cracking field have been further established and denned through a settlement which has recently been made b y the Sinclair Refining C o . , t h e Universal Oil Products Co., and the Gasoline Products Co. B y t h e terms of t h e settlement, Universal Oil Products Co. and Gasoline Products C o . give t h e Sinclair Refining Co. rights under their cracking patents for Sinclair's own use, while Sinclair gives t h e t w o licensing companies t h e right t o extend immunities t o their licensees against infringement litigation under Sinclair patents. T h e settlement also involves t h e payment of substantial sums b y Sinclair t o t h e Universal Oil Products Co. and t h e Gasoline Products Co., and t h e assignment b y Sinclair of a group of its cracking patents to the Universal Oil Products Co. T E X A S C O . SUES FOR INFRINGEMENT OF PATENTS SUIT
ALLEGING I N F R I N G E M E N T of
cracking p a t e n t s and
in-
volving what is understood t o be a Winkler-Koch cracking unit, has been brought b y T h e Texas Co. against the Republic Oil Refining Co. The suit, which has recently been filed in t h e United States District Court at Houston, Tex., alleges infringement of four patents of William A . Hall: N o s . 1,175,909, 1,239,099, 1,239,100, and 1,242,795; and t w o patents of Otto Behimer: N o s . 1,840,012 and 1,883,850. T h e suit is brought b y T h e Texas Co. a s owner and assignee of t h e Behimer and Hall patents. T h e cracking operations in question are located a t t h e Republic Oil Refining Co.'s plant a t Texas City, Tex. STAINLESS IRON S U I T APPEALED THE
AMERICAN S T A I N L E S S S T E E L C O . , Pittsburgh,
and
the
Electro Metallurgical Co., N e w York, are filing a n appeal with the United States Circuit Court of Appeals at Baltimore in their infringement suit against t h e Rustless Iron Corp. of America. The lower court recently, held the Clement patent o n stainless iron, under which the suit was brought, invalid because of a n earlier patent on similar material granted t o Elwood Haynes. UNIVERSAL O I L FILES INFRINGEMENT SUIT T H E U N I V E R S A L O I L PRODUCTS C O . , Chicago, 111., o n March 9 FIGURE 2. SECTION THROUGH CYLINDER OF A. HIGH-PRESSURE GAS-CIRCULATING P U M P FOR 1000 ATM., WITH STUFFING B O X E S AND VALVES
The speed of the gas-circulating pump has t o be regulated between 125 and 32 r. p. m.; it is therefore necessary for the speed of the motor also to be adjustable down t o 2 5 per cent of its maximum. With the 4-pole winding, t h e motor with adjustable pole windings and resistances in the rotor circuit, can be regulated between 125 r. p. m. and 86 r. p. m. F o r the 6-pole winding, the regulation available is from 8 6 t o 32 r. p. m. Since, however, complete electric regulation of the 3-phase motor could only be obtained by means of very large resistances, and then would be rather unreliable, a speed-reduction gear with the ratio of 1:2 was fitted. T h e range of regulation w a s divided up in such a w a y that, when driving direct with the 6-pole winding, the speed could be regulated down to 62.5 r. p. m., i. e., t o 50 per cent of the maximum. For obtaining lower speeds, the motor must work through t h e reduction gear. T h e motor is therefore regulated in t w o groups with 4-pole and 6-pole winding. T h e groups themselves are subdivided into various stages, the 4-pole into twelve stages a n d the 6-pole into six. T h e gradual changes in speed thus made possible are sufficient for working t h e gas-circulating pump in compliance with t h e different conditions arising in service. The motor is installed in the main machine room, where there is a risk of gas explosion. In t h e same room is the control board on which are mounted voltmeters, ammeters, recording tachometers, meters for each winding, signal lamps, and remote switches. T h e controller is operated electrically through push buttons. T h e stator i s controlled at a distance through relays, being also operated by means of push buttons. T h e change-over from 4-pole t o 6-pole winding, and vice versa, is effected through t w o 3-pole switches, which are set so t h a t t h e y can switch off t h e 4-pole winding and switch in the 6-pole, or t h e contrary.
filed suit in t h e Federal Court in Wilmington, Del., against the Octane Oil & Refining Co., alleging infringement of the clean circulation Patent N o . 1,392,629 and also of Patent N o . 1,890,974. The Octane company's refinery, where it is alleged the infringement is being carried on, is a t Baird, Tex. PATENT QUESTIONS AND ANSWERS A SERIES O F QUESTIONS and answers concerning patents, of particular interest t o the inventor of limited resources, has been prepared in mimeographed form b y R a y Belmont Whitman, 277 Park A v e . , N e w York, N . Y . , and is available from M r . Whitman on request. T h e information is prepared particularly for the inventor without finances.
T R E N D TOWARDS SMALLER AND SPEEDIER TRACTORS C. G. KRIEGER, engineer of t h e Detroit Laboratories of t h e Ethyl Gasoline Corp., in a survey of developments in tractor engineering, states that t h e trend is towards a smaller, speedier, and more economically operated tractor to replace the unwieldy, creeping, a n d costly machine as it has been known. The depression is forcing radical changes in tractor engine design and . the lessons learned b y engineers in t h e manufacture of automobile and airplane engines are being applied t o t h e farm. T H E R E H A S B E E N a considerable demand for some other salt of cerium t h a n eerie nitrate for use, particularly in analytical chemistry. W e are pleased t o announce, therefore, that O. T . Coffelt of Jackson, Mich., is prepared t o supply a readily soluble ammonium eerie sulfate.
