US2032674A - High pressure injector - Google Patents

Description

March 3, 1936. F w WALCH 2,932,674

HIGH PRESSURE INJECTOR Filed April 50, 1952 2 Sheets-Sheet l March 3, 1936. F. w. WALCH HIGH PRESSURE INJECTOR Filed April 50, 1932 2 Sheets-Sheet 2 UNITED STATES 'ATENT OFFICE HIGH PRESSURE INJECTOR Frederick W. Walch, So

merville, .Mass., assignor to Consolidated Ashcroft Hancock Company, New York, N. Y., a corporation of Delaware Application April 30, 1932, Serial No. 608,434

4 Claims.

This invention pertains to steam jet pumps of the type commonly known as injectors and wherein the heat energy converted into mechanical of steam is directly energy for the purpose, for example, of forcing feed water into a boiler against a pressure which may be as great as that of the steam jet, the present invention "being particularly useful in (though by no means limited. to) injectors of non-lift type, that is to say, those wherein the water inlet is not substantially above the level of the source of water supply. Injectors are usually employed for delivering feed water to locomotive boilers and for this use are commonly located outside of the locomotive cab and below the level of the water tank in the locomotive tender so that they are not called upon to raise the water to any substantial height from the source of supply.

Injectors may be classified as belonging to the axial flow, and to the non-axial flow type, respectively, and in the latter class are found prior devices capable of automatic regulation. These automatic regulating injectors are double 'tube and nozzle instruments, and are so arranged as, after starting, to deliver steam through a given orifice Water) in direct proportion to the steam delivered through (for entraining feed amount of a second orifice (to force the water into the boiler) and such double tube injectors will continue to operate without spilling, even though the vary between the starting steam pressure may and stopping of the instrument. While such double tube and nozzle injectors are automatic in tion, they are of comp their regulating aolicated construction,

necessitate a large and cumbersome casing, and

are expensive to construct, While the involved passageways through which the fluid must flow greatly reduces the thermal paratus.

efficiency of the apuser of the simpler,

smaller, less expensive and more efiicient axial 'flow injector has previously been obliged to sacriflce the self-regulating non-axial flow type and .to advantages incident to the feature found in the put up with the disuse of spillway holes or intermediate overflow arrangements designed to keep the apparatus in operation at such times as changes in steam pressure occur.

The axial flow type of injector as commonly constructed comprises a vided to form a water inlet casing appropriately dichamber and a water discharge chamber, such casing enclosing a combining tube and .a delivery tube which cooperate to define a passage arranged to receive water from the inlet chamber and to deliver it into the discharge chamber, and it has previously been thought essential to the proper operation of such devices that they be furnished with an outlet or so-called intermediate overflow leading from 5 the water inlet chamber, or from a point intermediate the adjacent ends of the combining and delivery tubes, for the purpose of discharging water and condensed steam before sufficient pressure energy has been built up to force water into the boiler, and it has also been usual to provide an outlet or final overflow leading from the water discharge chamber for a similar purpose. Ordinarily the intermediate and final overflows lead'to a common delivery pipe or pas- 5 sage and usually both overflows are controlled by valves, either automatic or manually actuable, but as valves under such conditions of use often develop leaks, the hot water from the water discharge chamber is enabled to flow back into the inlet chamber, thereby raising the temperature in the latter so as to cause the injector to cease operation or to break as it is known in the art. Moreover, the intermediate overflow provides a secondary outlet for the water inlet chamber so that when the injector is used for forcing water against a high boiler pressure there is a tendency for some at least of the water to escape or dodge out through the intermediate overflow and then through the final overflow, thus not only wasting water and steam, but lessening the efiective pressure at which the injector will operate.

Various proposals have been made for overcoming these defects in axial flow apparatus but all such prior proposals known to me involve a complication of parts with attendant increase in cost of production and upkeep which often more than counterbalances any of their supposed advantages, and so far as I am aware no simple and .practicalsolution of this problem has heretofore been found.

In accordance with the present invention, I provide an injector having all .of the advantages inherent in the axial flow type such as simplicity, low cost, small size, and direct unimpeded fluid flow through an uninterrupted forcer tube, but having combined therewith the automatic regulating action found heretofore only in the double tube type and without recourse to the provision of expensive and troublesome overflow arrangements common to prior apparatus.

In the course of a long series of experiments with and tests of injectors I have discovered that inefficient operation, frequent breaking and refusal to start is often caused by wear at that portion of the delivery tube which lies just beyond its inlet end or point of minimum diameter. While I am unable to advance a wholly satisfactory theory to account for the observed phenomena, I have found that at this point in the delivery tube microscopic pits in the surface of the metal appear after a relatively short period of use and that these pits rapidly increase in depth and size until, in some instances I have found them completely to perforate the wall of the tube. Evidently the presence of these pits resulting from the peculiar conditions of pressure and velocity in this point causes a serious disturbance in the flow of fluid so that apparently the norm-a1 law of action of the injector is wholly or in part nullified with consequent failure of the injector to operate or at least to operate certainly and efliciently.

Among the objects of the present invention are to provide a simple and inexpensive injector useful, for example, for delivering feed water to a locomotive boiler and capable of operating more efficiently, more certainly, and at a higher pressure than injectors of usual type, this object being accomplished in part at least by omitting the usual intermediate overflow so that there is no passage through which water may lead so as to disturb the intended operation or to reduce the theoretical delivery pressure. Another object is to provide an injector having a delivery tube so constructed as to prevent abnormal wear adjacent to its receiving end, and in its more specific aspects to provide a replaceable wear resistant liner at this part of the tube.

A further object is to provide an injector of very simple construction of the axial flow type which can be manufactured readily and at low ,cost, which is reliable and eflicient in action, and which will deliver the feed water against a high pressure head, and which is self-regulating, that is to say, varies in volume of water delivered in accordance with variations in steam pressure throughout a wide range of pressures without necessitating the manual actuation of valves or other control devices and without substantial tendency to break.

With the above objects in view I have devised an injector of the axial flow or single tube type wherein the combining and delivery tube are fixedly united at their smaller ends (omitting the intermediate overflow space sometimes provided at this or other points) and at the same time associate with the steam forcer nozzle a priming nozzle so arranged that the control of this single forcer nozzle determines the amount of water delivered by the injector. Furthermore, I preferably provide the delivery tube, adjacent to its smaller end, with a Wear resistant lining, which maybe removable and replaceable, if desired, so as to ensure a constant high eificiency of operation. By these arrangements I find it possible as a practical matter to deliver hot water to a boiler against a pressure of the order of 500 lbs. per square inch.

In the accompanying drawings, wherein I have illustrated one desirable embodiment of the invention, but without thereby intending to limit the invention to the specific construction so shown,

Fig. 1 is a vertical section lengthwise of the improved injector showing the control valve for the lifter nozzle partly open, but with the boiler checl; valve closed; 7

Fig. 2 is a top plan view of the improved injector; and

Fig. 3 is an end elevation looking from the lefthand side of Fig. l.

Referring to the drawings, and particularly to Fig. l, the improved injector preferably comprises a casing comprising the independent casing members I and 2 provided respectively with flanges I a and 2 which are united by means of bolts 3 in such a way that the casings I and 2 are disposed in substantial alignment.

The rear part I of the casing is furnished with a connection for a steam inlet or supply pipe 4 leading from the boiler or other source of steam, such pipe delivering steam into the steam inlet chamber 5 in the casing member I. The casing member I is also furnished with connections 6 for a water supply pipe leading from the locomotive tender or other source of water, it being understood that in the preferred arrangement the water level at the supply will be above the water inlet chamber I of the injector so that water will tend to flow freely into said chamber so long as the supply level is maintained.

The part I of the casing is furnished with a wall or septum (comprising the spaced vertical web members 8 and 9) dividing the steam chamber 5 from the water inlet chamber I. The web member 8 is furnished with an internally screwthreaded opening for the reception of the threaded butt end I0 of the forcer nozzle II, the latter passing through an opening of larger size in the Web 9. This opening in the web 9 is also screwthreaded for the reception of the threaded butt end I2 of the priming nozzle I 2, the latter oooperating with the outer surface of the forcer nozzle II to provide an annular steam delivery orifice I3 concentric with the nozzle I I and which receives steam from the chamber I4 between the webs 8 and 9, said chamber I4 having a steam inlet port I l controlled by the manually actuable valve I5. The valve I5 is provided with an actuating stem I6 which leads up through a gland I1 secured to the casing I, such stem being provided at its upper end with a part I8 adapted to receive one end of suitable actuating connections leading to the locomotive cab or other point of control.

The main or forcer nozzle II projects into the wide flaring rear end of the imperforate combining tube I9. The combining tube has an external annular enlargement or flange 20 provided with substantially parallel radial contact faces 20 and 20* which are directed rearwardly toward the inlet end of the casing and forwardly toward the discharge end of the casing respectively. The contact face 20 is clamped firmly against an annular radial seat surface I b of the flange I of the casing while the contact face 20 bears against an annular seat surface 2 of the flange 2 of the casing. Said flange 20 constitutes septum separating the water inlet chamber 1 from the water discharge chamber 24 in the casingmember 2. At its smaller end the combining tube I9 is provided with a screwthreaded nipple 2| which receives a screw-threaded socket 22 at the smaller end of the delivery tube 23, the latter extending into the discharge chamber 24 of the casing 2. The inner surfaces of the combining and delivery tubes I9 and 23 are substantially smooth and continuous and form an uninterrupted passage without any appreciable break or aperture in its walls or at the point of union of parts I9 and 23, the combining tube and delivery tube being in axial alignment with its the opening of this valve. During the correct itsv entrance end, which. is in the water inlet,

chamber 1, to. a. point M adjacent its junction with. the delivery tube, and the latter gradually increases in diameter from its junction with the.

combining tube to its delivery end E. The passage thus formed is thus in the nature of av Venturi-tube, and just beyond its point of minimum diameter, cavitation in the rapidly flowing fluid, takes place. The delivery end E of the delivery tube 23 is disposed opposite to the, boiler check valve 25 which has a stem 26 suitably supported in a guide 21 carried by a cap or gland 28'having threaded engagement with an opening in the right-hand end of the casing 2. The check valve 25 opens into a chamber 29 which communicates with a connection, 3!) adapted to receive a pipe leading to the water space in the boiler. Since the check valve gland 28 is axially aligned with the tube structure and is removable, thereby giving free access to the discharge chamber, it is readily possible, by the use of an appropriate tool, to unscrew the delivery tube 23 and withdraw it through the opening left by removal of the gland 28 without disturbing the combining tube l9. This is convenient when it is desired to renew the wear-resistant portion of the tube structure, since the operation may be performed without disturbing any of the pipe connections.

The check valve 3! cooperates with a seat 32 and is arranged to prevent a full flow of steam from the chamber 1 toward the source of water supply when the injector breaks. A stop 33 limoperation of the device, the only possible path of escape of water from the inlet chamber 1 is through the combining tube l9,-the inlet chamber being devoid of any overflow orifice or aperture. On the other hand, a priming overflow orifice 34 leads from the water discharge chamber 24, such orifice being controlled by a valve in a casing 34 the valve being actuable manually by means of a connection 36.

As shown at 31, the inner surface of the delivery tube 23 is recessed circumferentially near the smaller or entrance end of the tube, and this recess receives a tubular lining 38 of wear resistant material whose inner surface defines the fluid passage at this point. The delivery tube 23 may be of bronze as is usual, but while this material is desirable for the body of the tube, it will not withstand the peculiar abrasive action of the flowing fluid in the region of cavitation just beyond the point of minimum diameter of the fluid passage, and the lining is designed to take the wear at this point. For this purpose the lining should be of a wear resistant material (not subject to rust when subjected to hot water) and while various alloys for example stainless steel, may be used for the purpose, I have found that nitrided steel is highly desirable by reason of its extreme hardness and the relative ease with which the sleeve may be prepared from this material. This wear resistant lining may be formed in any desired manner and may be fixed in position, or, if preferred it may be removable for replacement, being confined in operative position in the recess so long as the tubes 19 and 23 are in assembled relation.

In starting the injector, the operator opens the overflow valve orifice 34 and the regulating valve l5 and then slightly opens the steam supply valve in the locomotive cab. Steam now flows through. the. pipe dttothe chamberg5, and thence out throughthe nozzle H. and; nozzle. l2 into the combining tube l9. Asthe steam enters the contracted passage. in the combining tube, its velocity is. greatly increased and. water is entrained with the. flowing steam andv carried into the combining tubewhere the steam is condensed by the cold. water, thus building up pressure in the chamber 24. As, soon. as water appearsv at, the priming overflow, the, operator further opens the main steam supply valve,. admitting boiler pressure steam to flow through the nozzle l2 and nozzle II, and; by: reason of the spacing of the delivery end of the orifice 13 from the re,- ceiving end of the tube I9, water in substantial quantity is deliveredv into the combining tube, thus completely condensing the steam from both steam nozzles and greatly increasing the pressure in the chamber 24. The overflow valve is now closed andwater under high pressure in the chamber 24 unseats the check valvev 25 and flows into the boiler. The main steam supply valve having been opened wide, the amount of water delivered by the injector is regulated by manipulation of the valve l5 and, after starting, the device. willcontinue to operate, even though the steam pressure may vary. If the injector breaks, the check valve 3! partially closes and prevents steam from blowing back into the water supply. At the same time steam is caused to flow out through a passage in the wall of the chamber 1, and by means of a pipe 39 this steam is led to a telltale device in the cab above the tank water level whereby to notify the engineer that the injector has broken and that the steam should be shut off.

Since in this improved device there is no way for water to leave the chamber 1 during operation of the injector except through the tube l9, substantially all of the pressure developed is available for opening the check valve25 and for forcing water against the boiler pressure, and thus the injector will. operate against higher pressures than those in which an intermediate overflow is employed. Moreover, as there is no passage. except through the tubes l9 and 23 from the chamber 24 to the chamber 1, it is impossible for hot Water to dodge back into the inlet chamber, and thus cause the. injector to break, as is often the case when an. intermediate overflow is employed.

The device. is simple to construct and the twopart tube structure comprising the members l9 and 23 is. easier to make than a unitary device of the same general character, while the flange 2B interposed betweenthe flanges l and 2 forms a convenient and ready means of fixing the tube structure in place and at the same time furnishes the desired separating wall or partition between the chambers and 24. When the flanges l and 2 are drawn together by means of the bolts 3, the enlargement. 20 of. the combining tube is so firmly held as fixedly to support the tube structure so that even though the application of considerable force may be necessary in unscrewing the delivery tube 23' or in screwing it back onto the combining tube, the latter is not disturbed and no loosening of the flange 20, with consequent development of a leak, can take place. However, by removing the bolts 3 the delivery end of the casing may be separated from the inlet end I, whereupon the entire tube structure may be drawn out of the casing member I by moving it forwardly and away from the steam nozzle ll without disturbing the latter.

In use it is found that the wear resistant member, by preventing wear at the entrance to the delivery tube, causes the device to function more eificiently over a longer period than usual arrangements, and by using av removable and replaceable wear resisting sleeve the delivery tube may be made to last indefinitely.

While I have herein disclosed one desirable embodiment of the invention by way of example, I wish it to be understood that various changes in size, proportion and shape of parts, as well as the substitution of materials and of equivalents,

may be made without departing fromthe spirit of.

the invention.

I claim:

1. A high-pressure, self-regulating, boilerfeeding injector comprising axially aligned combining and delivery tubes, said tubes being fixed in position and directly united and having imperforate walls defining a passage devoid of lateral outlets, a steam supply pipe, a water supply pipe, a priming nozzle receiving steam from the supply pipe, said priming nozzle being fixed in position with its delivery end spaced from the end of the combining tube and so arranged as to induce the flow of water from the water supply pipe into the combining tube, a forcer nozzle also receiving steam from the supply pipe and delivering it to the combining tube, said forcer nozzle also being fixed in position with its delivery end disposed within the combining tube and so arranged that steam delivered from said forcer nozzle positively forces water to enter said tube, and a regulating valve for controlling the inlet of steam thereby to govern the capacity of the injector.

2. A high-pressure, self-regulating, boiler-feeding injector having a casing providing a water inlet chamber, a water discharge chamber and a steam inlet chamber,--axially aligned combining and delivery tubes within the casing, the receiving end of the combining tube being within the water inlet chamber, the combining and delivery tubes being fixed in position and defining a passage devoid of lateral outlets and which constitutes the sole path for fluid flow between the water inlet chamber and the water. discharge chamber, a forcer nozzle receiving steam from the steam inlet chamber, said nozzle being fixed in position with its delivery end disposed within the combining tube in such a way that steam discharged from said forcer nozzle will force water into said tube, a priming nozzle fixed in concentric relation to the forcer nozzle, the delivery end of said priming nozzle being within the.

water inlet chamber and spaced from the end of the combining tube in such a position that steam delivered from said priming nozzle induces water from the inlet chamber to enter said tube, and a valve for controlling the flow of steam from the steam inlet chamber to said priming nozzle whereby to vary the capacity of the injector.

3. In a device of the class described having a tube structure including a combining tube member having a bore which gradually decreases in diameter from its entrance end and a delivery tube member having a bore which gradually increases in diameter toward its discharge end, said bores collectively defining a substantially straight longitudinal passage devoid of lateral outlets and which is smallest in diameter adj acent. to the junction of the tube members, the inner surface of one of the tube members at least, adjacent to the point at which the diameter of the longitudinal passage is smallest, being of hard;

non-corrosive and wear-resistant material, screw threaded means normally fixedly but detachably uniting the smaller end of the delivery tube member in end-to-end axial alignment with the smaller end of the combining tube member, and a casing in which the tube structure is mounted, said casing having a water inlet chamber, a water discharge chamber and a steam nozzle fixed within the Water inlet chamber, in combination, supporting means for removably holding the tube structure in operative position within the casing, said supporting means comprisng an external annular flange on the combining tube member, and an annular forwardly facing seat surface, constituting a part of and intermediate the ends of the casing, for engagement by said flange on the combining tube member, and securing means operative releasably to. hold said flange against turning and in contact with said seat surface of the casing so that the combining tube member will remain fixed in position in the casing while the delivery tube member is being separated from or attached to the combining tube member, said supporting means for the tube structure being designed and arranged to permit the entire tube structure to be released and removed by forward movement of the tube structure away from the steam nozzle.

4. A tube structure for use in an injector, said tube structure comprising a combining tube bers being axially aligned and having screw threaded connections one to the other, said tube structure defining a bore including a combining portion which gradually decreases in diameter from its entrance end to a point of minimum diameter and a delivery portion which gradually increases in diameter toward the discharge end of the tube structure, said bore providing a substantially straight longitudinal passage devoid of lateral outlets, a lining sleeve of hard, noncorrosive and wear-resistant material whose in.- ner surface constitutes a part of the wall of'the bore, said sleeve being removable from the tube structure by axial separation of the combining and delivery tube members, and means for removably supporting the tube structure in an injector casing having a. forwardly facing annular seat surface intermediate its ends, said supporting means comprising an external annular flange on the combining portion of the tube structure, said flange having a contact face directed rearwardly toward the entrance end of the tube structure and designed and arranged to make contact with the seat surface of the casing, and retaining means operative firmly to hold said flange against turning and in contact with said seat surface of the casing regardless of the application of force to screw constituent members of the tube structure, said supporting means for the tube structure being designed and arranged to permit the entire tube structure to be released and removed by forward movement of the tube structure away from the steam nozzle.

FREDERICK W. WALCH.

together or unscrew the

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