US2442281A - Antisurge means for steam generating apparatus - Google Patents

Description

2 Sheets-Sheet l P. ARANT ANTISURGE MEANS FOR 'STBAM GENERATING APPARATUS Filed Dec.

May 25, 1948.

W/W 7 Wk Z P. ARANT May 25, 1948.

ANTISURGE MEANS FOR STEAM GENERATING APPARATUS Filed Dec. 6, 1943 v 2 Sheets-Sheet 2 Patented May 25, 1948 ANTISURGE MEANS FGR STEAM GENERATING APPARATUS Perry Arant, Alhambra, Califi, assignor to Clayton Manufacturing Company, Alhambra, Califi, a corporation of Nevada Application December 6, 1943, Serial No. 513,093

3 Claims.

The present invention relates to intermittently operated steam generating apparatus of the type comprising a heating coil and a steam separator, and in particular to means for preventing surging between the heating coil and steam separator during the intervals when the steam generating apparatus is shut down or idling.

In steam generating apparatus of the general type referred to, often, after the burner has been cut oil, sufficient radiant heat is given up by the walls of the firebox to cause a portion of the liquid in the lower end of the heating coil to evaporate. Such evaporation produces steam bubbles or slugs of steam which expand and cause liquid and/or vapor to be discharged, from the lower end of the heating coil into the steam separator in a surging manner. In the majority of installations, such surges or pulsations are not objectionable, but in certain cases it is highly desirable to completely eliminate all surging.

One way of overcoming the aforementioned surging comprises the installation of an automatically operating bleeder valve in the line be tween the heating coil and the steam separator, the valve being arranged so that it does not fully close but remains open to a predetermined extent, or else closes fully but allows limited flow through suitable ports, when the pump means supplying liquid to the heating coil is shut down. In one form of the invention, the automatic valve is an electrically operated solenoid valve connected in circuit with the motor that drives the pump.

A further embodiment of the invention for overcoming the aforementioned surging comprises the use of two pumps, one of which continues to operate and circulate the liquid through the steam separator and heating coil so that no opportunity is afforded for the radiant heat to evaporate the liquid in the lower portion of the coil and cause it to surge over into the separator.

Accordingly, the principal object of the invention is to eliminate surging in steam generating apparatus between a heating coi1 (or equivalent means) and a steam separator connected with said heating coil (or equivalent means).

Another object of the invention is to provide automatic means for restricting communication between a steam generating unit and a steam separator to avoid surging during the inactive intervals of said steam generating unit.

A further object of the invention is to provide, in intermittently operated steam generating apparatus, anti-surge means which automatically becomes efiective when the operation of the feed pump is discontinued,

Other objects of the invention will be apparent from the following description taken in conjunction with the accompanying drawings in which:

Fig. 1 diagrammatically illustrates one form of the invention including a solenoid valve for preventing surging between the heating coil and the steam separator;

Fig. 2 is an enlarged elevational view, partly in section, of the solenoid valve shown in Fig. 1;

Fig. 3 is a horizontal sectional View taken on the line 3-3 of Fig. 2;

Fig. 4 is a rear end View, partly inssection, of the solenoid valve shown in Fig. 2;

Fig. 5 is a vertical sectional view through the valve taken on the line '55 of Fig. 2; and

Fig. 6 is a view of a bleeder valve element which will permit the valve of Fig. 5 to completely close and still avoid surging.

Referring now to Fig. 1 of the drawings, the numeral I generally indicates a combined pump means including a feed water supply pump F and a recirculating pump R. The pump means i is driven by a motor 2 through a belt 3. The motor 2 also drives a blower 4 through a belt 5. The blower 4 is connected by a suitable conduit 5 with an air inlet chamber 1 of a steam generating unit generally indicated by the numeral 8. The steam generating unit comprises a suitable burner nozzle 9 to which fuel is supplied through a conduit It. Fuel from the nozzle 9 is sprayed into a firebox 9* contained within a housing H and is ignited by suitable electrodes l2. The housing II contains a heating coi1 l3 of the pancake type through which the liquid to be heated is circulated. A flue i4 is provided at the upper end of the housing II for the escape of the products of combustion.

The feed pump F includes an intake feed manifold l5 the details of which need not be shown herein inasmuch as the pump means per se is not a part of the present invention. The inlet manifold I5 is connected to a feed water tank it by a pipe line H. The pipe line I! has a manually operable shut-01f valve it) connected therein and a strainer [9 associated with a strainer blow-down valve 2% A predetermined minimum water level is maintained in the feed .water tank It by a float mechanism 2| operatively associated with a float-controlled valve 22 and a water supply pipe 23. The feed water tank i5 is vented to the atmosphere by a pipe 24 having a shut-oh. valve 25 connected therein.

The recirculating pump R of the pump means l includes an intake recirculating manifold 39 similar to the manifold l5. The manifold 30 is connected by a pipe 3| with the lower end of a steam separator generally identified by the numeral 32. A manually controlled valve 33 in the line serves to cut off communication between the steam separator 32 and the recirculating pump R. A strainer 34 is connected in the pipe line 3| and serves to prevent the passage of any foreign matter from the steam separator 32 through the pipe 3| into the inlet manifold 36'. A strainer cleanout valve 35 is connected with the strainer 34 as shown.

The feed pump F includes an outlet feed manifold 36 which is connected by a pipe 31 to a mixing device 38. The recirculating pump R includes an outlet recirculating manifold 39 which is connected by a pipe 40 with the mixing chamber 38. The mixing chamber 38 is, in turn, connected by a pipe 4| to the inlet end 42 of the heating coil I3. A manually controlled shut-off valve 43 connected in the pipeline 4! controls the flow of liquid to the heating coiI l3. Hence, it will be clear that feed water supplied through the pipe 31 and recirculating water supplied through the pipe 40 are brought together in the mixing chamber 38 and then delivered to the heating coil l3 through the pipe 4|. A pressure gauge 44 indicates the pressure in the mixing chamber 38 and, hence, in the line 4| going to the heating coil IS. A valve 45 is connected with the mixing chamber 38 for effecting blowing down of the heating coil [3. A pressure relief valve 46 is interposed in a pipe line 4! connecting the mixing chamber 38 with the feed water tank Hi. The pressure relief valve 46 serves as a safety valve for the pump means I and is adapted to open to relieve any excess pressure in the chamber 38 by passing liquid directly to the feed water tank [6.

The outlet end 48 of the heating coil I3 is connected to a thermostat fuel control device 49, which per se forms no part of the present invention, and said device is connected by a pipe 59 with the steam separator 32, so that the heating coil discharges through said pipe into the upper portion of said steam separator. Any of the liquid not flashed into vapor in the steam separator 32 collects in the bottom thereof, and the level of said liquid is indicated by a gauge glass In order to prevent the liquid level in the steam separator 32 from rising above a predetermined height; one end of a pipe 52 is con nected to said separator at a level corresponding to the maximum desired liquid level, and the other end of said pipe is connected with a heat transfer coil 53 in the feed water tank I6. The coil 53 terminates in an ejector 54 which serves to agitate the water in said tank while it is being heated. The pipe 52 has a manually operable shut-oil valve 55 connected therein at a point adjacent the steam separator 22- and on the inlet side of a conventional steam trap 56. A one-way check valve 51 is connected in the pipe 52 between the steam trap 56 and the feed water tank [6. The check valve 5'! is installed to allow flow in the pipe 52 only in a direction away from the steam trap 56.

Steam is taken from the upper end of the steam separator 32 through a pipe line 69 containing a manually operable shut-oif valve 6|. The pipe line 69 is connected with a load diagrammatically indicated at 62. A condensate pipe 63 conducts condensate from the load 62 to the feed water tank l6. A conventional steam trap 64 is connected in the line 63 to prevent the return of any substantial quantities of steam from the load 62 to the feed water tank IS. The steam separator 32 is also provided with a pressure gauge 65, a safety valve 66 and a blow-off or drain valve 61.

An electromagnetically operated valve 79 is connected in the line 59 between the outlet end 48 of the heating coil l3 and the steam separator 32. The valve 19 is shown in detail in Figs. 2 to 5, inclusive, to which reference will now be made.

As will be apparent from Fig. 5, the valve 19 comprises a body 1| having an inlet chamber 72 and an outlet chamber 13. The flow of fluid between the chambers 12 and I3 is controlled by a movable valve element 14, of the double poppet type. The element 14 includes spaced heads 76 adapted to cooperate with seating surfaces 16 to restrict the flow through the valve 19. One of the features of the valve 19, which is attained by structure which will be described more fully hereinafter, is that the element 14 is limited in its closing movement to prevent complete closure of the valve in order to provide communication at all times between the heating coil l3 and the steam separator 32. Hence, the head portions T5 are not intended to seat and form a seal with the heating surfaces 16 as they would normally do.

The valve body 70 is provided with a threaded opening in which a plug 1'! is inserted after the valve element 14 has been passed therethrough. A threaded opening 18 in the body 10 is aligned with the plug 11 and a cap member 19 is threaded into said opening. The cap member 19 is externally shouldered at 80 and said shoulder is adapted to seat upon a horizontal flange 8| (Fig. 2) projecting from a bracket 82. The cap 19 includes a threaded portion 83 which projects through an opening 84 in the flange BI and a lock nut 85 threaded onto the portion 83 and jammed against the underside of the flange 8| serves to mount the valve 19 upon the bracket 82. A valve stem 86 projects through the cap 19 and has its upper end provided with a flanged sleeve 81 which provides a. detachable connection between said stem and the valve element H. A fluid-tight seal is maintained around the valve stem 86 by a stufllng box structure generally indicated by the numeral 88 assooi ated with the cap 19. A spring 89 surrounds the stem 86 and one end thereof engages said stuffing box and its opposite end engages a Washer 99. A nut 9| is threaded upon the stem 86 and engages the washer 90. The nut 9| is adjustable on the stem 86 to vary the tension of the spring 89 urging the valve element 14 toward closed position.

The bracket 82 previously referred to is secured to a casing 92 (Fig. 2) by screws 92*. The casing 92 houses a conventional electromagnet 93 having a movable armature or core 94. The core 94 has depending arms 94 to which a lever 96 is pivotally connected at one end by a pin 96. The lever is fulcrumed intermediate its length upon a pin 9'! carried by an arm 98 depending from the bracket 82. The free end of the lever 96 is provided with a slot 99 adapted to receive the lower end of the valve stem 86. The slotted end of the lever 95 is provided with curved bosses engaged with the lower side of an adjusting nut l9l carried by the valve stem 86 and held against rotation by the cotter pin I02. A stop member I03 (Fig. 2) in the form of a bolt is threaded into an opening H34 in the bracket 82 and the head thereof is engaged by the lever 95 at a point intermediate the pins 95 and 91. A look nut I05 maintains the stop H33 in any desired position of adjustment.

The electromagnet $53 is arranged so that when it is energized the core 94 is forced downwardly causing the lever 95 to fulcrum about the pin 91 and efiect an upward movement of the valve stem 88 and the element I l through the engagement of the curved bosses I00 with the nut I0l. Upward movement of the element is, of course, opens the valve 79 to its wide open position. On the other hand, when the electromagnet 93 is :deenergized, the spring 89 willmove the valve stem 86 downwardly and tend to close the valve, but by suitably adjusting the stop member I03 it is possible to limit the extent of closing of the valve to any degree desired. Normally the stop IE3 is so adjusted that it will prevent the spring 89 from completely closing the valve 10. The object of this arrangement is to restrict communication between the heating coil I3 and the steam separator 32, to prevent surging as will be explained hereinafter.

The electromagnetically operated valve Iii is connected in a circuit in parallel with a conventional pressure-responsive switch, generally indicated by the numeral IIli (Fig. 1), for automatically controlling the motor 2 which drives the pump means I and the blower i. The pressure-responsive switch IIll includes a diaphragm III and a linkage IE2 for separating contacts H3 and N4 of said switch when a given steam pressure is attained in the steam separator 32. The details of the pressure-responsive switch are unimportant inasmuch as an suitable or conventional presure-responsive switch can be used.

Current for operating the motor 2 is supplied through lines H5 and H6 connected with a manually operable switch Ii'i. When the switch Ill is closed, a lead IE8 connects the line H5 with the contact H3 and a lead IISi, including a relay coil IZI], connects the line HQ with the other contact N4 of the switch Hi). The relay coil I20 controls a switch l2! arranged in the circuit between the electromagnetically operated valve ii) and the manually operated switch I W. The electromagnet 93 of the valve I0 is connected to the line H5 by a lead 22 and to the line He by a lead E23. It will, therefore, be apparent that the electromagnet 93 and the motor 2 are connected in the circuit in parallel.

Normally, the contacts I I3 and Ild of the pressure switch I Ill are closed. and when the manually operated switch I ii is closed the relay I20 will be energized, closing the switch IZI so that the electromagnetically operated valve 19 and the motor 2 simultaneously receive operating current. As a result, the motor 2 starts to drive the pump means I and the blower i, and the valve it! opens wide. However, the pressure-responsive switch III] is arranged so that when a predetermined steam pressure is developed in the steam separator 32 it can interrupt the flow of current to the motor 2 and efiect incomplete closing of the valve I0 through the lines H5 and M6 by deenergizing the relay are, thereby opening the switch I2I, not withstanding the fact that the manually 0perated switch I ii is closed.

When the steam generating unit 8 is shut down manually by opening the switch I i'!, or as a result of the automatic operation of the pressure-responsive switch M0, the solenoid operated valve '10 will tend. to close simultaneously with the stopping of the motor 2, inasmuch as they are connected in parallel, as previously pointed out. The stopping of the pump means I, of course, interrupts forced circulation of liquid through the heating coil II. The burner 9 is automatically shut off by the thermally responsive control means 49. Usually, sufiicient radiant heat remains in the firebox 9 after the burner 9 has been shut down to cause a portion of the liquid in the lower end of the heating coil I3 to be vaporized thereby. The vapor thus formed normally tends to leave the heating coil I3 causing intermittent surging of liquid over into the steam separator 32, which is highly undesirable in certain installations. Any tendency for such surging is overcome by the present system due to the fact that the valve 10 is permitted to remain slightly open after the steam generating unit 8 has been shut down. Such slight opening of the valve ll] provides a bleeding action which definitely restricts the flow of liquid and/or vapor into the steam separator 32 to such extent that all surging is eliminated. At the same time the bleeding action also prevents any possibility of a substantial amount of steam being generated and remaining in the heating coil I3, any such steam tending to pass over into the steam separator 32 because said separator is under a lower pressure than said heating coil.

The rate at which vapor and/or liquid is permitted to pass from the heating coil I3 to the steam separator 32 (when the unit 8 is shut down) is determined by the extent of opening of the valve I0, and this can be varied to suit the requirements of individual steam generating units by suitably adjusting the stop I03.

It will be understood that any excess liquid accumulating in the steam separator 32 will be removed through the steam trap 56 and returned to the feed water tank I6 through the pipe 52. It will also be understood that the circulating pump R withdraws water from the separator 32 and recirculates it through the heating coil I3.

The valve shown in Fig. 5 is, in efiect, a bleeder valve because it does not completely close. It will be apparent that the results accomplished by this valve can also be achieved by a valve which does completely close, provided that the valve is constructed to permit the liquid to bleed therethrough to avoid surging when the valve is in its fully closed position. Thus, Figure 6 discloses a modified valve element 14 similar to the valve element 14 shown in Figure 5, except that the valve element I l has the head portions 15 thereof pierced by a plurality of bleeder ports I60. It will be apparent that when a solenoid valve utilizing the element I l is used, in lieu of the valve 10, such valve can be completely closed and surging will be avoided by the restricted flow afforded by the ports I60. Any number of ports I60 may be employed and their size may be varied in accordance with the requirements of an individual steam generating unit. Maniiestly, if the element I4 is substituted in the valve ill the means employed for limiting the closing movement of said valve may be dispensed with to permit engagement of the heads I5 with the seats I6.

It will be understood that various changes may be made in the means and system disclosed herein to eliminate surging without departing from the spirit of the invention or the scope of the annexed claims.

I claim:

1. Steam generating apparatus comprising: a

steam generating unit including conduit means having an inlet for liquid to be heated and an outlet for said liquid; pump means for supplying liquidto said inlet; an electric motor driving said pump means; a steam separator; a pipe line conmeeting the outlet of said conduit means with said steam separator; an electrically operated valve connected in said pipe line, said valve being connected in a circuit in parallel with said pumpdriving motor and arranged to close to a predetermined extent upon stopping of said motor to thereby restrict flow through said pipe line and thus prevent surging of liquid and/or vapor from said conduit means over into said steam separator,

2. Steam generating apparatus comprising: a steam generating unit including conduit means having an inlet for liquid to be heated and an outlet for said liquid; pump means for supplying liquid to said inlet; an electric motor driving said pump means; a steam separator; a pressure-responsive switch having its pressure-responsive portion connected with said steam separator and arranged to open upon attainment of a predetermined pressure in said steam separator; a pipe line connecting the outlet of said conduit means with said steam separator; an electrically operated valveconnected in said pipe line, said valve being connected in a, circuit in parallel with said pump-driving motor, said pressure-responsive switch being connected in said circuit to interrupt the flow of current to said motor and electricallyoperated valve upon attainment of said predetermined pressure, and said electrically-operated valve being arranged to restrict flow through said pipe line upon said interruption of flow of current, to thus prevent surging of liquid and/or vapor from said conduit means over into said steam separator.

3. Steam generating apparatus comprising: a steam generating unit including conduit means having an inlet for liquid to be heated and an outlet for said liquid; pump means for supplying liquid to said inlet; an electric motor driving said pump means; a steam separator; a pipe line connecting the outlet of said conduit means with said steam separator; an electrically operated valve connected in said pipe line, said valve being connected in a circuit in parallel with said pumpdriving motor; a relay controlling the supply of current to said motor and electrically operated valves; a switch connected with said relay controlling the actuation thereof; and 'a pressure-responsive means connected to said steam separator and arranged to open said switch in response to a predetermined steam pressure in said steam separator, said relay and switch being so connected that opening of the switch causes the relay to interrupt flow of current to said valve and pump, said electrically operated valve being arranged to restrict flow through said pipe line upon interruption of the circuit to said relay and thus prevent surging of liquid and/or vapor from said conduit means over into said steam separator.

PERRY ARANT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,559,763 Nicholson Nov. 3, 1925 1,883,293 Jacobus Oct. 18, 1932 1,898,196 Lucke Feb. 21, 1933 2,142,984 Thurman Jan. 3, 1939 2,199,214 Vorkauf Apr. 30, 1940 2,201,618 La Mont May 21, 1940 2,210,822 Stilwe1l Aug. 6, 1940 2,217,635 Bailey et al Oct. 8, 1940 2,227,349 Kerrick Dec. 31, 1940 FOREIGN PATENTS Number Country Date 28,099 Great Britain Dec. 6, '1913

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