US1316680A - Firing system for steam-boilers - Google Patents

Description

G. A. BRYAN.

FIRING SYSTEM FOR STEAM BOILERS.

APPLICATION FILED MAY29. I918.

Patented Sept. 23, 1919.

INVENTOR.

- I TNESS:

A TTORN E Y5 GEORGE A. BRYAN, OF ALBUQUERQUE, NEW MEXICO.

FIRING SYSTEM FOR STEAMBOILERS.

Specification of Letters Patent.

Patented Sept. 23, 1919.

Application filed May 29, 1918. Serial No. 237,196.

To all whom it may concern:

Be it known that I, Gnoncr. A. BRYAN, a citizen of the United States, residing at Albuquerque, in the county of Bernalillo and State of New Mexico, have invented certain new and useful Improvements in Firing Systems for Steam-Boilers, of which the following is a full, clear, and exact description.

This invention relates to firing systems for steam generators adapted particularly for steam propelled vehicles and in which liquid fuel is utilized. The object of the invention is to provide an automatic system for maintaining and controlling the pressure generated, by igniting and extinguishing the burner as may be required, and in which steam or air used under pressure for vaporizing the fuel at the burner, is maintained at a uniform pressure regardless of the main pressure in the boiler. In carrying out the invention I use in connection with the burner a sparking device and a fuel spraying nozzle with means whereby the fluid supplied under pressure to the nozzle will at the same time serve to actuate an automatic electric switch to supply the ignition spark. I also use a control valve which when the boiler pressure reaches the maximum, will simultaneously cut off the fluid pressure to the burner and restore the automatic switch to position to be again actuated when the burner is to be ignited. There is also used a pressure regulator for maintaining a uniform pressure of the steam supplied to the burner for vaporizing purposes, regardless of the ressure in the boiler and a source of uni orm air pressure for vaporizing the fuel in starting. These features will all be described in detail hereinafter with reference to the accompanying'drawing, in which the figure is a conventional representation of the entire system comprehended by my invention.

Referring. to the drawing, 1 indicates a portion of a steam boiler, of which the lower part 2 is the fire chamber. Attached to the front wall of the fire chamber is a burner 3 of any approved form but comprising a fuel nozzle 4, and a spraying nozzle 5 from which a blast of air or steam is delivered across the outlet of the fuel nozzle 4: in order to draw the fuel from the latter and spray it into the firing chamber 2. The rear end of the burner is provided with air openings 6 affording the necessary oxygen forcombustion. The mixture of sprayed fuel and air is subject to ignition by a spark plug 7 which projects into the mixing chamber of the burner. 8 is a cylinder containing a piston 9 normally held at the lower end of the cyllnder by a spring 10. A pipe 11 leads from nozzle 5 of the burner to a port in the side wall of cylinder 8 to establish communicatlon between said cylinder and the nozzle. The port in the cylinder is normally closed by the plston 9 while in its lowermost position. The piston rod 12 passes through the upper end of the cylinder and engages a pitoted contact lever 13, the free end of which rests upon a segment consisting of two termlnal insulating portions 14 and 15 and an intermediate conducting portion 16, the reciprocation of the piston 9 causing the contact arm to travel from one insulating block to the other and in the transit making temporary electrical connection with the conducting portion 16. 17 is an induction coil having the usual primary and secondary windings and provided with a vibrator of ordinary construction located in the primary circuit, which also includes a battery 18. a switch 19, and whose terminals are respectively connected to a contact shoe on the end of arm 13 and to the conducting segment 16. The terminals of the secondary winding of the induction coil are respectively connected with one of the terminals of the spark plug 7 and with the frame of the burner, as shown, the other terminal of the spark plug being understood as grounded upon the frame of the burner so that high tension currents induced in the secondary winding of the induction coil will produce corresponding sparks at the terminals of the spark plug for igniting the mixture in the burner. At 20 is shown in section what I term a main controlling valve comprising a frame within which is fixed a diaphragm 21, to which is attached a valve stem 22 leading to a valve 23 seated in an inlet port 2 1 in the bottom of the structure. Beneath the diaphragm is located a heavy spring 25, the tension of which is adjustable by means of a nut 26. The port 24: opens into a chamber 27, from which leads a pipe 28 to the bottom of cylinder 8. The pressure of the spring 25 against the under side of the diaphragm 21 is offset by steam pressure on the other side of said diaphragm supplied through a pipe 29 directly from the boiler 1. It will therefore be seen that by adjusting the tension of spring 25 to a given value the valve 23 will be held open by the spring until that value is slightly exceeded by the steam pressure above the diaphragm, at which time the valve 23 will close. At 30 is shown a device similar to that just described but which I term a steam pressure regulator. This device comprises a frame within which is fixed a diaphragm 31 to which is attached a valve rod 32 leading to a valve 33 which controls a port 34 in the lower end of the device. Beneath the diaphragm is a spring 35 considerably lighter than the spring 25 in the main valve and whose tension can be adjusted by means of the nut 36 through which the valve stem freely passes. Port 34 admits steam from pipe 37 into the chamber 38, from which the steam is free to pass out through the pipe 39. From pipe 39 a branch pipe 40 leads to the chamber above diaphragm 31, while another branch leads by pipes 41 and 42 to port 24 in the lower end of the main control valve 20. 43 is a four-way valve to which leads a steam pipe 44 direct from the boiler 1 and an air pipe 45 from an air tank 46. From this four-way valve leads the steam pipe 37 which connects with the port 34 in the steam pressure regulator and the air pipe 47 which connects with the-pipe 42 leading to the port 24 in the lower end of the main control valve, 48 is a float chamber to Which gasolene, kerosene or other suitable liquid fuel is supplied through the pipe 49 leadin from an elevated tank or a supply of fiiel under pressure. From this float chamber a pipe 50 connects with the fuel nozzle 4 within the burner, it being understood that the float maintains the level of the liquid in the chamber on a line with the outlet of the nozzle.

The operation of the system is as follows:

In order to start the burner into operation the hand switch 19 in the primary circuit is first closed, then the four-way valve 43 is turned so as to connect the air supply from tank 46 with the ipe 47. From this pipe the pressure leads t rough pipe 42 into chamber 27 of the main control valve. From this chamber the air passes freely through pipe 28 into the lower end of the cylinder 8, where it forces the piston 9 upward and uncovers the port leading to pipe 11; from ipe 11 air escapes through the nozzle 5 1nto the burner, thereby drawing fuel from the nozzle 4 and spraying it, together with air from the ports 6, into the fire chamber 2.

When the piston 9 rises the contact arm 13 is carried onto the conducting segment 16 and closes the primary circuit of the induction coil, which causes an interrupted current to flow in the primary, due to the action of the vibrator, and a corresponding secondary vibratory current to bridge the contacts at the spark plug, creating a series of sparks which lgnites the mixture. The sparking continues at the plug to insure the ignition of the mixture while the contact arm 13 traverses the conducting segment 16, and this period is determined by the rapidity of movement of the piston 9, which, during the first part of its stroke is rapid, but upon the release of the pressure throu h the pipe 11, is delayed slightly until finally the piston is at the end of its stroke, when the contact arm has passed on to the insulating block 15. The piston 9 remains in its upper position because of the fact that the outlet from the cylinder 8 through pipe 11 is more restricted than the inlet thereto through the pipe 28, thus insuring an accumulation of pressure in the cylinder, which holds the pistonin its elevated position. This condition continues until the pressure in the boiler has been raised sutficiently to enable it to be used for atomizing at the burner, Whereupon, in order to conserve air pressure, the four-way valve 43 is turned to cut off the air and connect pipe 44 with pipe 37. Steam at boiler pressure will then flow through pipe 37 to the chamber 38 in the steam pressure regulator, when it will pass out through the pi e 39 to the u per side of diaphragm 31 an to the cham er 27 in the main control valve. From the latter chamber the steam will lead through pipe 28 to the cylinder 8 and thence to the burner, where it will serve to atomize the fuel in the same manner as previously done by the air. This is the normal operatin condition of the system. Should the boiler pressure rise to an excessive oint where the pressure direct from the oiler above diaphragm 21 will close the valve 23, the pressure at the burner will be out 01f and the flame extinguished. At the same time piston 9 will drop to its lowest position, returning the arm 13 to the upper end of its stroke. This condition will continue until the pressure falls so that spring 25 in'the main control valve again opens valve 23, whereupon piston 9' rises to again admit pressure to the burner and to supply the igniting spark, whereupon steam is again generated in the boiler. In this way the main control valve not only serves as a safety valve but conserves fuel by avoiding a blow off. The pressure necessary to supply the atomizing blast at the burner is considerably less than main boiler pressure and it is desirable that this burner pressure should be maintained uniform under all conditions. This is the function of the steam pressure regulator 30. It will be seen that the boiler pressure which enters the lower chamber 38 in this device has access also to the chamber on the upper side of diaphragm 31, and by setting the tension of spring 35 so that it will yield to the pressure desired at the burner the valve 33 will close orthrottle the ort 34 sufficiently to maintain the desired pressure of steam in that part of the system beyond the regulator. The air pressure used for starting the system is of substantially the same pressure as the steam which is used under running conditions and this air pressure may be maintained in any desired and well known manner, as for instance by a pump which either starts and stops automatically or which runs continuously with a provision for escape of air above the required pressure. It is of course evident that the system can be operated upon the air alone but for economic reasons it is desirable to use the steam for atomizing purposes whenever it is available.

I claim:

1. The combination of an atomizing fuel burner, a source of fluid pressure and an ignition device connected therewith, an electric switch controlling said ignition device and means whereby the fluid pressure flowing to the burner will temporarily close the switch and then hold the switch open as long as the pressure flows to the burner.

2. The combination of a boiler, an atomizing fuel burner therefor, a source of fluid pressure, an ignition device connected with the burner, an automatic controlling valve and a fluid pressure actuated switch, said controlling valve being subject to fluid pressure from the boiler and varying the flow of fluid pressure to the switch and burner.

3. The combination of a boiler, a fuel burner therefor comprising an atomizer, a duct for fluid pressure leading to the atomizer, a main controlling valve subject to boiler pressure and controlling the flow of fluid in said duct. two sources of fluid pressure, one of which is constant and the other boiler pressure, an automatic controlling valve for maintaining the boiler pressure at any desired uniform value, and means for admitting either of said two sources of pressure to said duct at will.

4. The combination of a boiler, a fuel burner therefor, comprising an atomizer, a duct for fluid pressure leading to the atomizer, a main controlling valve subject to boiler pressure and controlling the flow of fluid in said duct, two sources of fluid pressure, one of which is constant and the other boiler pressure, an automatic controlling valve for maintaining the boiler pressure at any desired uniform value, means for admitting either of said two sources of pressure to said duct at will, an electric igniter associated with said burner, and means for rendering the same active upon the passage of pressure in said duct.

5. The combination of an atomizing burner, a duct for fluid pressure leading thereto, an electric igniter associated therewith, a switch controlling the igniter circuit and comprising a reciprocating contact adapted to move from one open circuit position to another, and having an intermediate fixed contact with which the reciprocating contact engages in its excursions, and a piston connected with the reciprocatin contact, and subjected to the fluid pressure 1n said duct.

6. The combination with a boiler of an atomizing fuel burner for heating said boiler, means for conducting pressure from said boiler to said burner, an ignition device for said burner, an electric switch controlling said ignition device, and means whereby this pressure flowing from said boiler to the burner will control said switch.

7. In a firing system for steam boilers, the combination with a burner, of means for supplying pressure from said boiler to the burner for atomizing purposes, an ignition device for said burner, an electric switch controlling said ignition device, means whereby the pressure flowing from said boiler to the burner will control said switch, and means for automatically cutting off said pressure supply when the boiler pressure reaches a predetermined maximum.

8. The combination with an atomizing fuel burner, of a source of fluid pressure and an ignition device connected therewith, an electric switch controlling said ignition device, and means whereby fluid pressure flowing to the burner will close the switch.

In witness whereof I subscribe my signature.

GEORGE A. BRYAN.

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