US1732796A - Steam-boiler-control system - Google Patents

Description

Ot. 22, 1929. w. DOBLE STEAM BOILER CONTROL SYSTEM Filed Nov. 19. 1924- 3 mount 01,

FIB-3 llll Warren Do/e lllll 4 I 2:- .Z: WW 0 0| Patented Oct. 22, 1929 UNITED STATES PATENT OFFICE WARREN DOBLE, OF BERKELEY, CALIFORNIA, ASSIGNOR TO DOBLE STEAM MOTORS CORPORATION, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE STEAM-BOILER-CONTROL SYSTEM Application filed November 19, 1924. Serial No. 750,892.

The invention relates to a system for controlling the rate at which Water is introduced into a steam boiler.

An object of the invention is to provide a system for varying the rate at which water is introduced into the boiler, in accordance with the rate of steam consumption.

Another object of the invention is to provide a system for controlling the amount of water introduced into the boiler in accordance with boiler steam temperature conditions.

A further object of the invention is to provide a system for controlling the amount of heat added to the boiler in accordance with boiler steam temperature conditions.

A further objectof the invention is to provide a boiler control system in which an increase in temperature of the steam in the boiler causes an increase in the amount of water introduced into the boiler, and a further increase in temperature causes a decrease in the amount of heat added to the boiler.

A further object of the invention is to provide an adjustable apparatus which operates automatically to control the rate at which water is' introduced into the boiler in accordance with the rate of steam consumption.

The invention possesses other advantageous features, some of which, with the foregoing, will be set forth at length in the following description, where I shall outline in full that form of my invention which I have selected for illustration in the drawings aecompanying and forming part of the present specification. In said drawings I have shown one form of apparatus embodying my invention, but it is to be understood that I do not limit myself to such form, since the invention, as set forth in the claims, may be embodied in a plurality of forms.

Referring to said drawings:

Figure 1 is a diagrammatic representation of the system of my invention.

Figure 2 is a section through the device for controlling the introduction of feed water into the boiler, in accordance with the rate of steam consumption and in accordance so with boiler steam temperature.

Figure 3 is a vertical section through the pum inlet.

The system of my invention comprises means for controlling the rate of introduction of feed water into the boiler in accordance with the rate of discharge of steam from the boiler. By such control, as the rate of steam consumption increases, the rate of introduction of feed water increases and vice versa, so that under normal conditions, the amount of water in the boiler remains substantially constant. Other factors being equal, this control system operates to maintain a substantially constant temperature within the boiler.

The invention also contemplates the provision of means whereby an increase in boiler steam temperature, causes water to be intro duced into the boiler at a different rate, said rate being partially controlled by said first mentioned control means. The invention further contemplates the provision of means whereby a further increase in boiler steam temperature to a predetermined maximum temperature will interrupt the supply of heat to the boiler. These various control devices are associated with each other to pre vent the production of abnormal conditions of temperature Within the boiler. The feed water is introduced into the boiler by a pump, which is preferably connected to the engine, which is driven by steam from the boiler, so that the plunger of the pump is working when the engine is in operation and means are provided whereby variations in temperature within the boiler and variations in the rate at which the water pumped passes through an orifice control the operativeness of the pump to deliver water into the boiler. To control the amount of water introduced into the boiler, the pump is preferably disabled by controlling or preventing the operation of the pump inlet valve, so that re ciprocation of the pump piston will not operate to pump water, as shown in my c0 vending application, Serial No. 740,641, filed ept. 29, 1924, or by lay-passing a portion of the water pumped back to the supply tank.

The rate at which water is introduced into the boiler is controlled by the rate of the steam consumption and, by rate, I mean the number of pounds of steam per minute or other time interval. The system is particularly applicable to steam generating plants for use on steam automobiles, conveyances or other vehicles in which the rate of steam consumption is variable, due to varying opening of the throttle valve. In accordance with my invention the rate at which water is introduced into the boiler varies in accordance with the rate at which steam is discharged from the boiler and this rate is variable, due to conditions of operation of the vehicle. The rate of steam consumption is measured by passing the steam through a Venturi tube wherein the flow of steam produces a high pressure zone and a low pressure zone, and the difierential in pressure between the zones is employed to control the rate at which water is introduced into the boiler. In steam propelled vehicle practice, the steam engine constitutes practically the entire load on the boiler, so that the rate at which water is introduced into the boiler depends upon the rate at which the engine consumes steam.

The system comprises a boiler 2 which is supplied with heat by the burner 3, which is preferably a liquid fuel burner, operated by the electric motor 4:. Usually the motor drives a blower 4 which produces in the burner a spray of fuel and air. This combustible mixture is ignited, preferably by an electric spark, and the resultant flame is projected into the combustion space of the boiler. Means arecprovided for opening and closing the motor circuit in accordance with variations in the temperature of steam in the boiler above and below a predetermined maximum value. Steam from the boiler is conducted through the pipe 5, which is provided with a throttle valve 5 to the steam engine 6, which serves to drive the vehicle. Water is supplied to the boiler from the supply tank 7 by a pumping mechanism 8 which usually comprises a reciprocating pump having one or more cylinders. The pump is preferably directly connected to the steam engine by the shaft 12, so that when the steam engine is in operation, the pump is driven. The water is discharged from the pump and passes'through the pipe 13 to the control device 14, which will be described hereafter, and which controls the rate at which water in introduced into the boiler and the operativeness of the pump to deliver water to the boiler. From the control device 14 the water passes through the pipe 15 to the boiler.

The control device 14 is provided with means for controlling the rate at which water is introduced into the boiler in accordance with the rate at which steam is discharged from the boiler, with means operative by an increase in boiler steam temperature to a predetermined value for varying the rate to permit water to be introduced into the boiler at a greater rate and with means operated by variations in the rate at which the Water passes through an orifice to control the operativeness of the pump. The device comprises a casing having passages or conduits therein through which the water passes and having control devices for controlling the passage of such water through said conduit and having displacement operated devices for con trolling the operativeness of the pump. The water discharged by the pump passes through the pipe 13 to the inlet conduit 17 in the device 14 and the water discharges from the de vice through the outlet conduit 18 into the pipe 15, which is connected to the boiler. The conduit 17 is connected to the conduit 18 bv the passage 19 and means are provided for controlling the rate at which water passes through the conduit 19. The passage of water through this conduit is controlled by the valve 21, secured to the valve stem 22 which is attached to the piston 23 disposed in the cylinder 24. The opening movement of the valve 21 is opposed by a spring 25 disposed in the cylinder above the piston, the spring being light and being inactive when the valve 21 is closed on its seat. The area of the opening between the valve 21 and its seat is less than the area of the passageway 19, so that such opening constitutes an orifice or restricted passage through which the water nor mally passes to the pump. In order to force water through the orifice, the pressure in the passage 19 must be greater than the pressure in the passage 18, and, with an orifice of constant area, the greater the diiiercntial pressure on opposite sides of the orifice, the greater will be the rate at which water will fiow through the orifice. It is also manifest that, the pressure remaining substantially constant, a variation in the area of the orifice will cause a variation in the rate at which water flows through the orifice.

Means are provided for varying the position of the piston 23 in accordance with the rate at which steam is discharged from the boiler. Arranged in the conduit 5 through which the steam discharges, is a Venturi tube 26 in which high pressure and low pressure zones are produced by the difierent velocities of the steam at diiferent parts of the tube. The high pressure zone of the Venturi tube 26 is connected to the cylinder 24 below the piston 23 therein by the conduit 27, so that the high pressure is effective on the under Side of the piston. The low pressure zone of the Venturi tube is connected to the cylinder 24 above the piston 23 therein by the conduit 28, so that the low pressure is effective on the upper side of the piston. The piston is therefore subjected to a diiferential pressure, the magnitude of which varies with the velocity of steam through the tube 26 and this varying differential pressure causes a variation in the position of the piston 23 and consequently a variation in the position of thev Valve 21 and a variation in the size of the orifice. As the velocity of the steam increases, this diiferential increases and causes the valve 21 to be moved to increase the area of the orifice and conse uently increase the rate at which water is introduced into the boiler. Conversel a decrease in the velocity of the discharging steam causes a decrease in the rate at which water is introduced into the boiler.

Since the pump is directly connected to the engineand since the speed of the engine is variable and since the speed of the engine is not dependent upon the rate of steam consumption, due to varying loads on the engine, means are provided for controlling the amount of water pumped in accordance with the requirements of the boiler. This means preferably comprises means .for enabling or disabling the pump to deliver water to the boiler so that the amount of water pumped may be varied regardless of the speed of the engine. The control of the quantity of water delivered by the pump mechanism is preferably accomplished by controlling one of the pump valves and since the inlet valve operates under less pressure than the discharge 'valve, I prefer to control the operation of the inlet valve. The pump is provided with an inlet valve 31, which is preferably guided in' the pump inlet 32 by vanes on the underside of the valve which extend into the inlet conduit. If this valve is held unseated, the reciprocation of the piston in the pump will not operate to pump water. Means are provided for holding the valve unseated when it is (18 sired to disable the pump. Arranged below the inlet conduit is a housing 33 in which there is disposed a solenoid 34. Disposed within the solenoid is a core 35 having a stem 36 extending into the inlet conduit and terminating adjacent the under side of the valve 31. The core 35 is provided on its under side with a stem 37 which is surrounded by a spring 38 which tends to move the core 35 upward to hold the valve 21 from its seat,

thereby disabling the pump. The solenoid circuitis normall closed and the solenoid thus normally ho ds the core 35 in its depressed position, holding the stem 35 from engagement with the valve31 so that the valve is free to operate, thus enabling the pump. When the solenoid circuit is opened, the spring 38 moves the stem 36 upward and holds the inlet valve 31 from its seat so that :the pump is then disabled and rendered inopdetermined magnitude, the solenoid circuit is opened and the pump disabled; the reverse subsequently occurring when the pressure difference decreases to a predetermined magnitude. Connected in series with the solenoid 34 is a source of electrical energy such as the storage battery 43 and a main switch 44. The solenoid circuit is also provided with a differential pressure actuated switch which is opened when the difl'erential pressure on opposite sides of the orifice reaches a predetermined magnitude. Arranged in the casing 14 is a cylinder 46 in which is disposed a piston 47 which is loaded on its upper side with a spring 48, the pressure of which is adjustable by the screw 49. The inlet eonduit 17 opens into the cylinder 46 on the under side of the piston, so that the piston is subjected on its under side to the pressure in the conduit 17 and the outlet conduit 18 is connected to the cylinder 46 on the upper side of the piston, so that the piston is subjected on its upper side to the pressure in the conduit 18, plus the pressure of the spring 48. The piston 47 is thus moved to variable positions, depending upon the magnitude of the diiferential pressure at opposite sides of the orifice or depending upon the difference between the rate at which water is pumped and the rate at which it passes the orifice. Connected to the piston 47 is a lever 51 which extends to the outside of the casing and which has its outer movable end disposed in close relation to one end of the switch lever 52. Upward movement of the piston 47 due to an increase in the diiierential pressure to a predetermined magnitude, causes the lever 51 to rock the switch lever 52 and open the solenoid circuit at the switch 53, thus disabling the pump 8. Conversely, when the differential pressure decreases to a predetermined minimum, due to the disabling of the pump, the switch 53 is' again closed and the pump 8 enabled to deliver water under pressure to the casing 14. Durin the operation of the pump, the pressure of the water pulsates, due to the reciprocation of the pump plunger, and the pi ten 47 moves to compensate for the pulsations. The cylinder 46 has suflicient volume to act as a pressure storage chamber, into and out of which water flows as the dili'erential pressure at the orifice varies.

The control device 14 also embodies means for controlling the introduction of water into the boiler in accordance with boiler steam temperature conditions. The conduit 17 is connected to the conduit 18 by a second passage 55 which constitutes a by-pass of the conduit 19. The inlet to the conduit 55 isnormally closed by the valve 56 in contact with the inlet end of the conduit 55. The amount of water which may the conduit 55 is controlled by the-adjustable valve 57 associated with the discharge end of the conduit 55. The stem of the valve valve 21 lies in the cinduit 18 and the valve 57 extends into the conduit 18 but the sizes of the stems of these valves are such as not to interfere with the passage of water through the conduits 17 and 18, so that the presence of these valves does not interfere with the passage of water to the cylinder 46.

Means are provided for controlling the position of the valve 56 in accordance with temperature conditions within the boiler and these means are so arranged that when the temperature within the boiler reaches a certain predetermined magnitude, for instance, 750 F., the valve 56 is operated to open the conduit 55 and thereby permit the feed water to pass from the conduit 17 to the conduit 18. Secured to the stem of the valve 56 is a core 54 which is normally pressed upwardby a spring 58 to seat the valve. Surrounding the core 54 is a solenoid 59 which, when energized, draws the core 54 downward and opens the conduit 55. The circuit of the solenoid 59 is connected across the battery 43 and the main switch 44 and includes a switch which is actuated when the predetermined temperature is reached in the boiler, to close the solenoid circuit. Normally, the solenoid circuit is open. The switch in the circuit of the solenoid 59 is operated by a suitable thermal responsive device suchas the quartz rod 61 which is disposed within a metallic tube fixed at one end to the shell of the boiler and extending into the steam space in the boiler. As the temperature of the steam in the boiler increases, the metallic tube is elongated and the quartz rod recedes and efiects the closing of the switch. The switch comprises a switch arm or lever 62 fulcrumed at one end to a suitable bracket and pivoted to the quartz rod 61. This lever carriesa contact 63 which, as the lever moves downwardly due to the expansion of the metallic tube, contacts with the yieldingly mounted contact 64, thus closing the solenoid circuit and opening the valve 56. The switch arm 62 is adjusted to cause the circuit to be closed at a definite predetermined temperature, for instance, 7 50 F.

.VVhen this temperature is reached the solenoid circuit isvclosed and the water is bypassed around the rate controlling device and when the temperature within the boiler again drops the switch is opened and the valve 56 again closed.

Means are also provided for interrupting the supply of heat to the boiler in accordance with boiler steam temperature. Arranged in series with the circuit of the motor 4 which drives the blower, is a switch comprising the switch arm 62. and the contact 65. The contact 63 on the switch armis normally in engagement with the contact 65 so that the circuit through the motor is closed when the main switch 44 is closed. When the temperature within the boiler reaches a predetermined maximum which may be between 900 and 1200 F. the contact 63 moves from engagementwith the fixed contact 65, thus opening the motor circuit and interrupting the supply of heat to the boiler. As the temperature subsequently drops and the arm 62 is moved upward, the motor circuit is again closed and heat is again supplied to the boiler.

I claim:

1. The combination with a steam boiler of a continuously operated pump for introducing water into the boiler, a valve for controlling the flow of water into the boiler, means controlled by the volume of steam discharging from the boiler for controlling the area of the valve opening and means actuated by an increase in differential pressure at opposite sides of the valve opening to a predetermined magnitude for controlling the water pressure on the pump side of the valve.

2. The combination with a steam boiler of a pump for introducing water into said boiler, means controlled by the passage of steam from the boiler for controlling the rate at which water is introduced into the boiler and means operated by the difference in pressure on opposite sides of said controlling means for controlling the introduction of water into the boiler.

3. The combinationwith a steam boiler of a pump for introducing water into said boiler, means controlled by the passage of steam from the boiler for controlling the rate at which water is introduced into the boiler and means operated by variations in the dill'ercnce in pressure on opposite sides of the control means for enabling and disabling the pump.

4. The combination with a steam boiler of a pump for introducing water into said boiler. means controlled by the rate of discharge of steam from the boiler for controlling the rate at which water is introduced into the boiler and coacting means connected in parallel with said first means and controlled by the temperature of the steam in the boiler for controlling the introduction of water into the boiler.

5. The combination with a steam boiler of a pump for introducing water into said boiler, means controlled by the rate of discharge of steam from the boiler for controlling the rate at which water is introduced into the boiler and coacting means connected in parallel with said first means and controlled by an increase in the temperature of the steam in the boiler to a predetermined magnitude, for increasing the rate at which water is introduced into the boiler.

6. The combination with a steam boiler of a pump for introducing water into said boiler. means controlled by the rate of discharge of steam from the boiler for controlling the rate at which water is introduced into the boiler and means controlled by an increase in the tem erature of the steam in the boiler to a pre etermined temperature for augmenting 4 said first named control means in controlling the rate at which water is introduced into the boiler.

7. The combination with a steam boiler of a pump for introducingwater into said boiler,

. means controlled by therate of discharge of water around'said first named control means.

8. The combination with a steam boiler of a pum for introducing water intosaid boiler, a con uit connecting said pump and boiler, a valve in said conduit, means controlled by the passage of steam'from the boiler for varying the position of said valve and coacting means connected in parallel with said first means and controlled by the temperature of the steam in the boiler for controlling the introduction of water into the boiler.

9. The combination with a steam boiler of a pump for introducing water into said boiler, a conduit connecting said pump and boiler, a valve in said conduit, means controlled by the passage of steam from the boiler for varying the position of said .valve and means controlled by an increase in the temperature of the steam in the boiler to a pre determined temperature for augmenting said valve in controlling the rate at which water is introduced into the boiler.

10. The combination with a steam boiler of a pump for introducing water into said boiler, a conduit connecting said pump and boiler, a valve in said conduit, means controlled by the passage of steam from the boiler for varying the position of said valve and means controlled by an increase in the temperature of the steam in the boiler to a predetermined temperature for by-passing the water around said valve.

11. The combination with a steam boiler of a pump-for introducing water into said boiler, a conduit connecting said pump and boiler, a valve in said conduit, means controlled by the passage of steam from the boiler for varying the position of said valve and means controlled by the difference in pressure on opposite sides of the valve for controlling the introduction of water into the boiler.

12. The combination with a steam boiler of a pump for introducing water into said boiler, a conduit connecting said pump and boiler, a valve in said conduit, means controlled by the passage of steam from the boiler for varying the position of said valve and means controlled by the diiierence in pressure on opposite sides of the valve for controlling the operation of the pump.

13. The combination with a steam boiler of a pump for introducing water into sa1d boiler, a conduit connecting said pump and boiler, a valve in said conduit, means controlled by the passage of steam from the boiler for varying the position of'said valveand means controlled by the difference in pressure on opposite sides of the valve for enabling and disabling the ump.

14:. The combination wit a steam boilerv of a pump having a valve for introducing water into said boiler, a conduit connecting said pump and boiler, a valve in said conduit, means controlled by the passage of steam from the boiler for varying the position of said valve and means controlled by the difference in pressure on opposite sides of the valve for controlling the operation of said pump valve.

15. The combination with a steam boiler of a pump for introducing water into the boiler, a conduit connecting said pump and boiler, a valve in said-conduit, means controlled by the passage of steam from the boiler for varying the position of said valve,

a by-pass conduit connecting the pump to the boiler around said valve, a second valve nor mally closing the by-pass conduit and means actuated by an increase in boiler steam temperatureto a predetermined temperature for unseating said second valve to open the bypass conduit.

16. The combination with a steam boiler of a pump for introducing Water into the boiler, a conduit connecting said pump and boiler, a valve in said conduit, means controlled by the passage of steam from the boiler for varying the position of said valve, a. by-pass conduit connecting the pump to the boiler around said valve, a second valve normally closing the by-pass conduit, a solenoid for moving said second valve to open the by-pass conduit, a circuit for said sole noid and means actuated by an increase in boiler steam temperature to a predetermined temperature for closing said solenoid circuit.

17! The combination with a steam boiler, an engine connected thereto and constituting substantially the entire load on said boiler, a feed water pump connected to said engine, means controlled by the rate at which steam flows to the engine for controlling the rate at which the feed water is introduced into the boiler and means controlled by the steam temperature within the boiler for augmenting said first control means in controlling the rate at which water is introduced into the boiler.

18. The combination with a steam boiler, an engine connected thereto and constituting substantially the entire load on said boiler, a feed water pump connected to said engine, means controlled by the rate at which steam flows to the engine for controlling the rate at which the feed water is introduced into the boiler and means actuated by the difference in pressure on opposite sides of the control means for controlling the operation of the pump.

19. The combination with a steam boiler,

an engine connected thereto and constituting substantially the entire'load on said boiler, a feed water, pump connected to said engine, means controlled by the rate at which steam flows to the engine for controlling the rate at which the feed water is'introduced into the boiler, means controlled by the steam temperature'within the boiler for augmenting said first control means in controlling the rate at which water-is introduced into the boiler and means actuated by the difference in pressure on opposite sides of said first control means for controlling the operation of the pump.

20. The combination with a steam boiler and an engine connected thereto, of a feed water pump connected to the engine, a conduit connecting the pump with the boiler,

means for controlling the rate of fiowof water through the conduit in accordance with the rate atwhich steam discharges from the boiler and means controlled by boiler steam temperature for by-passing water arou'nd'said control means.

21. The combination with a steam boiler and an engine connected thereto, of a feed water pump connected to the engine, a conduit connecting the pump with the boiler, means for controlling the rate of flow of water through the conduit inaccordance with 'thetrate at which steam discharges from the boiler, means controlled by boiler steam temperature for by-passing water around said control means and means for controlling the rate at which water passes through said by-pass.

22. The combination with a steam boiler of a pump for introducing water into said boiler, a conduit having a restricted passage therein interposed between the pump and the boiler, means controlled by the difference between the rate at which Water is pumped and the rate at which it passes through the passage for controlling the operation of the pump and means controlled by variations in the rate of discharge of steam from the boiler for varying the area of the passage.

23. Regulating means for a steam boiler comprising a casing having an inlet passage,

an outlet passage, two conduits connecting said inlet and outlet passages, means connecting said inlet and outlet passages, means responsive to the velocity of steam discharged from said boiler for obstructing one of said conduits, means responsive to the my hand.

WARREN DOBLE.

temperature of the steam in said boiler for obstructing the other of-said conduits, and

means responsive to differential pressure in said inlet and outlet passages for regulating the pressure in said inlet passage.

24. The combination of a steam boiler, a pump for introducing Water into said

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