US2530073A - Automatic control for steam boilers or tanks - Google Patents

Description

Nov. 14, 1950 c. OLIVER 2,530,073

AUTOMATIC CONTROL FOR STEAM BOILERS 0R TANKS Filed Jan. 9, 1948 2 Sheets-Sheet 2 Jfiiy.

Patented Nov. 14, 1950 AUTOMATIC CONTROL FOR STEAM- BOILERS R TANKS Charles L. Oliver, Portsmouth, Va.

Application January 9, 1948, Serial No. 1,348

Claims.

This invention relates to a system for automatically controlling the steam pressure in a tank or boiler and for automatically replenishing the water therein when the level thereof falls be low a predetermined point.

More particularly, it is an object of the present invention to provide a system of the aforedescribed character wherein an excess of steam pressure in the tank or container will be utilized for pumping a liquid for replenishing a low liquid level in the container thereby dissipating an excess of steam pressure and replenishing the supply of liquid in the container simultaneously for maintaining the container or tank under the most desirable condition.

Another object of the invention is to provide a system of the aforedescribed character wherein a steam pump may be utilized in lieu of an electric pump with considerable saving in installation and maintenance cost and with a maximum saving in operating costdue to the fact that an excess of steam pressure is utilized for operating the steam pump.

Still a further and important object of the invention is to provide a system wherein through an electric circuit and control switches operative in response to conditions within a boiler or container, said system may be automatically utilized for replenishing the supply of liquid in the container and for simultaneously dissipating an excess of steam pressure therein or for merely replenishing the supply of liquid Where an excess of steam pressure does not exist.

Afurther object of the invention is to provide a system of the aforedescribed character of extremely simple construction capable of being economically manufactured and sold and which will function efiiciently for accomplishing its intended purposes and which will require substantially no maintenance or supervision.

Another object of the invention is to provide a system of the aforedescribed character capable of being utilized with steam boilers or tanks where a high voltage supply of electricity, such as is required for operating an electric motor is not available and accordingly where a sysem utilizing an electric motor actuated pump for replenishing the liquids in a tank or boiler could not be employed.

Various other objects and advantages of the invention will hereinafter become more fully apparent from the following description of the drawings, illustrating a presently preferred embodiment thereof, and wherein:

Figure 1 is a diagrammatic view showing the system connected to a steam boiler or tank;

Figure 2 is an enlarged. sectional view, partly in side elevation, of one of the switches utilized in the electric circuit of the system, and

Figure 3 is a similar view of the other switch of said electric circuit.

Referring more specifically to the drawings, and first with reference to Figure 1, the numeral 5 designates generally a conventional steam boiler or tank, only apart of, which is illustrated, and with which the novel control system, designated generally 6 and constituting the invention is adapted to be utilized.

The boiler or tank. 5 is provided with vertically spaced liquid level tubes 1 and 8 having remote ends communicating with the chamber of the boiler or tank 5 and adjacent ends communicating with the housing 9 of an electric switch, designated generally l0 and which is operated by the liquid level in the tank 5. Two conductor II and I2 lead from a suitable source of electric supply, not shown, such as a .110 volt electrical outlet and the conductor II connects with one terminal of the switch I0 and the conductor I2 leads to and connects with a part Of a switch, designated generally I3 and also forming a part of the control system 6. Another conductor I 4 leads from the other side of the switch I0 to another part of the switch I3, as will hereinafter, be described and as illustrated in Figure 2, and'it will be readily obvious that if required a relay may be interposed. in the conductors I2 and I4 between the switch I3 and the liquid level actuated switch I0 and electric source.

The tank or boiler 5 has a steam supply conduit or pipe I5 extending from the dom thereof for supplying steam from said tank or boiler to any suitable mechanism or machinery to be operated thereby, not shown. A steam supply conduit or pip-e I6, forming a part of the automatic control system 6 is connected to the steam line I5 for receiving steam under pressure therefrom and it will be readily apparent that the pressure of the steam in the conduit I6 will be substantially equal to the steam pressure in the pipe l5 .or in the upper part of the boiler 5.

The control system 6 includes a steam engine I! for operating a steam pump I8. A steam supply conduit I9 communicates with the steam engine I1 and is adaptedto supply steam thereto for operating the steam engine and pump and is in turn connected, intermediate of its ends, tothe opposite, laterally extending end 20 of the con,- duit I6, The conduit portion 20 is provided with a strainer ZI and, between said strainer and the conduit I9, said conduit portion 20 is provided with a conventional type of shutoff valve 22 which is controlled by a solenoid 23 which may likewise be of any conventional construction. The conduit I6 is provided with a branch passage or pipe 24 which connects with the opposite end of the conduit I9 and between said passage 24 and the valve 22, a manually regulated shutoff valve 25 is provided in the conduit H5. The conduit I9 is also provided with a manually regulated shutoff valve 26 interposed therein between the conduit portion 28 and the passage 24.

A pipe 21, provided with a loop and of a much smaller diameter than the conduits previously referred to communicates with the conduit portions l9 and 24 at their junction and has an opposite end connected to and communicating with a pipe 28 to one end of which is connected a pressure gauge 29 for indicating the steam pressure in the conduit l6" and the portion of the conduit I9 disposed above the valve 26.

The opposite end of the pipe 28, as best illustrated in Figure 2, extends through the housing 29 of the switch l3 and is connected to and communicates with a steam responsive bellows 39, disposed within said housing 29 and forming a part of the switch l3.

The pump I8 is provided with a conduit 3| which opens into the intake side thereof and the opposite end of which, not shown, may be connected to any suitable source of water supply, preferably a condensate tank. The pump |8 is provided with a conduit 32 leading from and communicating with the discharge thereof and having a discharge end opening into the boiler 5. A pipe or conduit 33 leading from a source of water supply under pressure, such as a city water supply connects and communicates with the conduit 32 adjacent the end thereof which discharges into the boiler 5 and said conduit 32 is provided with a check valve 34 disposed between its connection with the pipe 33 and the pump 3 and which is arranged to open only to permit the passage of water from the pump 3 therethrough in a direction toward the boiler 5 and so that water from the water main conduit 33 can not flow through the conduit 32 toward the pump l8. The conduit 33 is provided with a normally closed valve 34a, corresponding to the valve 22 and which is adapted to be opened by a solenoid 35, when energized, and which corresponds to the solenoid 23. A check valve 36 is interposed in the conduit 33 between the valve 34a and its connection to the pipe 32 and is likewise constructed and arranged to prevent flow of water through said conduit toward the valve 3411 but to permit the flow of water therethrough toward the conduit 32.

The liquid level responsive switch l may assume any desired form so long as it will function to assume a circuit closing position when the liquid level in the boiler falls below a predetermined point. As illustrated in Figure 3, said switch l0 may include, in addition to the housing 9, a float 31 having a stem 38 extending upwardly therefrom and which extends reciprocally through a stufling box 39 in a top wall 40 of the float housing 9. It will be readily obvious that the liquid level in the housing 9, as indicated at 4| in Figure 3, will be the same as the liquid level in the boiler 5 and that the level of the float 31 relatively to the housing 9 will vary and be governed by the liquid level 4|. The upper portion of the float stem 38 extends into a chamber defined by a housing 42- which is detachably mounted on the housing 9. and which contains a fixed contact 43 which is shown connected to the conductor l4 and a yieldable contact 44 which is shown connected to the conductor I. The free end of the yieldable contact 44 is disposed above the fixed contact 43 and is ordinarily retained, by its resiliency, out of engagement therewith. The float stem 38 is provided with a transversely extending arm 45 at its upper end having a depending projection 46 which is normally disposed over and out of engagement with the free end of the yieldable conductor 44. Accordingly, as the liquid level 4| falls within the housing 9 the float 37 will move downwardly therein causing the stem 38 to move downwardly through the stufiing box 39 until the projection 46 engages the free end of the yieldable contact 44 and further downward movement of the float 3'5 will cause said free end of the contact 44 to be forced downwardly by the projection 46 and into engagement with the contact 43 for closing the electric circuit of the switch. Similarly, when the liquid level 4| again rises the float 31' will move upwardly thereby causing the projection 46 to move out of engagement with the contact 44 so that the latter may by its resiliency return to its position of Figure 3 for interrupting the circuit between the conductors II and I4.

Referring to Figure 2, the switch I 3 includes a platform or support 4! which is journaled by a bearing 48 on a shaft 49 which extends horizontally through and is supported by the housing 29. A mercury switch 50 is fixedly supported on the platform 41. The switch 50 may be of any conventional construction including an elongated closed container 5| which is partially filled with mercury, as indicated at 52 and which is provided at each end thereof with two electrical contacts including the contacts 53 and 54 which extend into one end of said container 5| and the contacts 55 and 56 that extend into the opposite end thereof. The contacts 53 and 54, and 55 and 55 are disposed out of engagement and a circuit therebetween is closed by the mercury 52 when in engagement with both of the contacts of either pair of contacts. A contractile coiled spring 51 is connected at one end thereof by fastening means 58 to one end of the platform 41 and extends upwardly therefrom and is attached at its opposite end to an adjusting screw 59 which extends. through a threaded opening 60 in the top wall of the housing 29 and by means of which the tension on the spring 51 can be varied. The spring 51 functions to normally hold the support or platform 41 tilted as illustrated in Figure 2 and so that the end thereof which is connected to the spring 51 will be held in an elevated position. The bellows 30 has a stem 6| projecting from its upper end and which bears against the under side of the support 41 adjacent the opposite end thereof and on the opposite side of the pivot 49 so that when said bellows. 3B is expanded by steam pressure it will cause the support or platform 4'! to rock counterclockwise, as seen in Figure 2 sufficiently so that the mercury 52 will flow to the opposite end of the container 5| for completing an electrical connection between the contacts 53 and 54.

The conductor wire l4 extends from the switch contact 43 into the housing 29 and has separate branch portions 62 and 63 which connect with the contacts 54 and 55, respectively. The conductor l2 likewise extends into the housing 29 and connects with one contact post 64 of a conductor strip 65 and has a branch conductor element66 which connects with a similar contact post 54 of a second conductor strip 51 which is insulated from the conductor strip 65. Each of the conductor strips 65 and 61 is provided with two contact posts 64 and said strips form electrical'connections between the posts 64 thereof. A conductor 68 extends from the other post 64 of the strip 65 and connects with one of the contacts of the solenoid 23 and a conductor 69 extends from the other post 64 of the contact strip 61 and connects with one contact or terminal of the solenoid 35. A conductor connects the mercury switch contact 53 with the other terminal or contact of the solenoid 23 and a conductorH connects the contact 55 with the other contact of the solenoid 35.

" From theforegoing it will be readily apparent that when the switch It is in an open position the electric circuit from the electric source connected to the conductors l I and I2 will be inoperative so that the solenoids 23 and 35 will be deenergized so that valves 22 and 340. will remain in closed positions. If the steam pressure in the boiler or tank 5 is below a predetermined point, for example, thirty pounds, said steam pressure will be insufficient to expand the bellows 35 sufiiciently for rocking the mercury switch 50 from its position of Figure 2 and into a position so that the mercury 52 will close the connections between the contacts 53 and 54, due to the strength of the spring 51 Accordingly, with the system in this condition and if the water level drops suificiently in the boiler 5 and switch housing 9 to cause the contact 44 to engage the contact 3, as previously described, a circuit will be closed to the solenoid 35 due to the fact that the contacts 55 ad 55, as seen in Figure 2, will be electrically connected by the mercury 52 so that the current will flow from the conductor ll through the contacts 44 and 43 and conductor 14, through conductor 63 and the contacts 56 and 55 connected by the mercury 52 to and through the conductor H to the solenoid 35 and back through the conductor 69, conductor strip 51 and conductor 55 to the negative conductor 12 Which is grounded at the electric source. This will energize the solenoid 35 to open the valve 34a so that water from the conduit 33 can fiow through the valve 34, past the check valve 35 and through a portion of the conduit 32 into the boiler 5 for. replenishing the supply of water therein and raising the water level until the switch It is returned to an open position, as previously described.

Should the steam pressure in the dome of the boiler 5 be above the desired pressure, thirty pounds, at the time that the switch It is closed the mercury switch 50 will have been previously tilted so that the mercury therein will be out of engagement with the contacts 55 and 55 and electrically connecting the contacts 53 and 54. This results because the pressure in the conduits l5 and i6 is substantially equal to the pressure in the boiler 5 causing a corresponding pressure in the pipes 21 and 2B and accordingly in the bellows 30 and which is sufficient to overcome the resistance of the spring 51 to rock the support 41 and mercury switch 50 to the position, just previously mentioned. Accordingly, when the switch it is closed by falling of the water level in the boiler 5 the electric circuit from the conductor l4 Will be through the conductor 62, contact 54, mercury 52 to contact 53 and from said contact 53 to the solenoid 23 through conductor l5. Likewise, the solenoid 23 will be rounded through the conductor 68, conductor strip 65 back to the conductor 12 so that the solenoid 23 will be energized for opening the valve 22. When this o'cc'urs,"and assuming'thevalve-25 t'obe' in' an open position and the valve 26 to be closed,

steam from the conduit 16 will pass through conduit is to operate the steam engine I! which in turn operates the pump [8. This will cause water to be pumped from the condensate tank or other source, not shown, connected to the conduit 3!, through pump 18 and conduit 32 into the boiler 5 thus replenishing the liquid in the boiler and at the same time dissipating an excess steam pressure. It'will be readily apparent that the mercury switch might reverse the circuit from one solenoid to the other while the boiler or tank 5 is being refilled in the event that the steam pressure diminishes below or increases to above thepredetermined point.

The valve 25 can be shut off to prevent operation of the steam engine H, as for the purpose of cleaning the strainer 2! and said steam engine may be controlled manually by opening the nor mally closed valve 26 to allow the steam from conduit IE to pass'through the by-pass 24 into and through the conduit [9 to the steam engine.

Various modifications and changes are con templated and may obviously be resorted to, without departing from the spirit or scope of the inventionas hereinafter defined by the appended claims.

I claim as my invention:

1. An automatic control system for steam boilers comprising an electric circuit connected to a source of electric current, a liquid level responsive switch adapted to be actuated by the liquid level in a steam boiler or tank for closing the switch when'the liquid level falls below a predetermined point and for opening the switch when the liquid level rises to above said point, said switch being interposed in the electric circuit, a steam pump adapted to be connected to a source of liquid supply and to said boiler for pumping the liquid from said source of supply into the boiler, a steam engine for operating said pump, a steam line connected to the boiler and to said steam engine, a first normally closed solenoid valve for closing said steam line to prevent operation of the steam engine and pump, a conduit leading from a source of water supply under pressure and connected to the boiler or tank, a second normally closed solenoid valve interposed in said last mentioned conduit, a multiple switch connecting each of said solenoid valves independently to said electric circuit, said multiple switch being normally disposed in a position for closing a circuit to the second solenoid valve when said circuit is energized, and a pressure responsive means operatively connected to said multiple switch and to said steam line by a portion thereof which by-passes the first solenoid valve for actuating said multiple switch when the steam pressure is above a predetermined point for interrupting the circuit to the second solenoid valve and for electrically connecting the first mentioned solenoid valve to said electric circuit.

2. An automatic control for steam boilers or tanks comprising an electric circuit connected to a source of electric current, a liquid level responsive switch for controlling said circuit and connected to and adapted to be actuated by the liquid level in a boiler or tank for closing the electric circuit when the liquid level falls below a predetermined point and for opening said circuit when the liquid level rises to above said point, a conduit connected to a source of water supply and to said boiler, and a normally closed solenoid valve interposed in said conduit and connected to said electric circuit to be energized thereby when the switch is closed for automatically supplying water to the boiler or tank, means adapted to be connected to the boiler or tank and to a second source of water supply for pumping from said second water supply source to refill the boiler or tank, a steam line connecting said means to the boiler or tank, a normally closed solenoid valve interposed in said steam line, and a steam pressure responsive switch interposed in said electric circuit and connected to the steam line .and to each of said solenoids for interrupting a circuit to the first mentioned solenoid and for energizing the last mentioned solenoid when said liquid level switch is closed and. when the steam pressure in the tank or boiler is above a predeztermined, point.

3. An automatic control for steam boilers or tan-ks comprising an electric circuit connected to :a source of electric current, a liquid level responi-sive switch for controlling said circuit and connected to and adapted to be actuated by the liquid level in a boiler or tank for closing the electric circuit when the liquid level falls below :a predetermined point and for opening said circuit when the liquid level rises to above said point, a conduit connected to a source of water supply and to said boiler, and a normally closed solenoid valve interposed in said conduit and connected to said electric circuit to be energized thereby when the switch is closed for automatically supplying water to the boiler or tank, means adapted to be connected to the boiler or tank and to a second source of water supply for pumping from said second water supply source to refill the boiler or tank, a steam line connecting said means to the boiler or tank, a normally closed solenoid valve interposed in said steam line, and a steam pressure responsive switch interposed in said electric circuit and connected to the steam line and to each of said solenoids for interrupting a circuit to the first mentioned solenoid and for energizing the last mentioned solenoid when said liquid level switch is closed and when the steam pressure in the tank or boiler is above a predetermined point, and adjustable means associated with said steam pressure responsive switch for varying the amount of steam pressure required for interrupting the circuit to the first mentioned solenoid valve and for closing the circuit to the last mentioned solenoid valve.

4. An automatic control for steam boilers comprising an electric circuit adapted to be connected to an electric source, a liquid level responsive switch interposed in said circuit and adapted to be actuated by the liquid level in a boiler for energizing said circuit when the liquid level falls below a predetermined point, a conduit.

for supplying water under pressure to the boiler, a first solenoid valve interposed in and normally closing said conduit, means for pumping water from a source of supply to the boiler or tank, said means being steam operated, a second conduit connected to the boiler and to said means for supplying steam thereto, a second normally closed solenoid valve in said second conduit, and a steam pressure responsive switch connected to said second conduit and interposed in the electric circuit and normally positioned for closing a circuit to said first solenoid valve when the liquid level responsive switch is closed and adapted to be actuated by an eXcess steam pressure for deenergizing said first solenoid valve and for energizing the second solenoid valve.

5. An automatic control as in claim 4, and manually controlled means for regulating said steam pressure responsive switch to vary the steam pressure required to cause said switch to de-energize the first solenoid valve and to energize the second solenoid valve.

CHARLES L. OLIVER.

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

UNITED STATES PATENTS Number Name Date Re. 17,718 Bowen July 1, 1930 391,415 Kieley -r--- Oct. 23, 1883 403,972 Sturtevant May 28, 1889 672,427 Bullard Apr. 16, 1901 690,445 Leadbeater Jan. 7, 1902 974,085 Lindgren Oct. 25, 1910 1,415,952 Rogillio May 16, 1922 1,440,521 Andrews Jan. 2, 1923 2,002,254 Treloar May 21, 1935 2,131,335 Sullivan Sept. 27, 1938 2,385,161 Pinkerton Sept. 18, 1945

Images