US2392300A

US2392300A - Automatic boiler control system

Info

Publication number: US2392300A
Authority: US
Publication date: 1946-01-01
Anticipated expiration: 1963-01-01

Description

Jan. 1, 1946. H. ZIEBOLZ ET AL 2,392,300

' AUTOMATIC BOILER CONTROL SYSTEM Filed June 12, 1942 COUP LING REGULATOR MASTER RmuLAroR COUPLING COOLER Patented Jan. 1, 1946 UNITED ST TE PATENT c rr es 2,392,300 aurom'rrc nomna oorrmor. srsrnu I Herbert Ziebola, James D. McGracken, and Daniel '1. Gundersen, Chicago, 111., assignors to Askania Regulator Company, Chicago, Ill., a corporation of Illinois Application June 12, 1942, SerialNo. 440,150 (or, 60-44) x piston I9 is connected to operate a second cam 3 Claims.

This invention relates to an automatic boiler control system or the type employing a master regulator responsive to the boiler load or steam pressure in the header and a hydraulic coupling controlled thereby to supply the combustion supporting air to support combustion of the fuel in the boiler furnace. One of the main objects of the invention is to provide automatic control means for a hydraulic coupling employing servomotors having cross connected cylinders for controlling t'he valves in the lines or pipes-connected to the coupling, the idea being to prevent the valves from being operated simultaneously and to avoid the usual dead spot in such a control. Furthermore, the idea is to provide a system of this type in which the control valves will close and remain closed so that the coupling can be operated by an ordinary hand control in case of oil failure. Another object is to provide control means for the coup which is not subjected to undue friction and increasing the possibility of a dead spot in the control valves. Still another object is to provide improved control means for such hydraulic couplings adapting them for general use. A further important object of the invention is to so interconnect the valve control means for the hydraulic coupling that the valves will be operated in a specific manner and also to provide a bubbling device as a level indicator of hydraulic fluid which acts as a generator oi control impulses for the operation of the valve control means.-

Other aims and advantages of the invention will appear in the specification, when considered in connection with the accompanying drawing, in which:

23 which acts on a second Jet pipe relay 24 through a. spring 25 in opposition to a diaphragm 26 which. in turn, is subjected to a pressure proportional to the level of oil in the oil sump 21 or a hydraulic coupling later to be described.

The diaphragm 26 is shown as being arranged in a casing 28 to which is connected a pipe 29 having its opposite end '30 extending to a point near the bottom of the sump 21 and submerged in the oil therein. To this pipe is connected an air conduit 3| through which is introduced air at a suitable bubbling rate by means .of a throttle 4 valve 32a and a pressure reducing valve 32. The

\ regulator and is shown as controlling two servo- The figure is a diagrammatic illustration of boiler furnace it. The boiler H is shown as 'having an ordinary steam main or header H to which is connected. a bellows-type pressure air will bubble out of pipe end 33 and maintain the pressure in pipe 23 proportional to the submerged depth or pipe end 30, so that when the oil level in the sump remains constant, the air pressure acting on the diaphragm 26 will likewise remain constant. If the oil level falls in the sump, the air will bubble up through it more readily from the end or opening 30 and thereby reduce the pressure of the air in the line 23 and in the casing 28. The valve 32a is adjusted to bleed air into line 29 at a rate Just suflicient to keep active bubbling at the pipe end 30.

The jet p pe 24 forms a part of the coupling motors or valve control means in the form of cylinders 33 and 34 carrying spring urged istons 35 and 36 respectively. The

fluid pipes

31 and 33 leading from thejet pipe relay 24 are shown as being cross connected to the cylinders 33' and 34, the pipe 31 being connected to the outer end of cylinder 34 and also to the inner end of cylinder 33 by means of branches 33 and respectively; while thepipe 38 is connected to the outer end of cylinder 33 and to the inner end of cylin-' der 34 by means 01' branches 41 and 42 respectively. Piston rods 43 and 44 extend through the outer ends of the cylinders 33 and 34 respectively, each cylinder having an unpacked bearing seal or bailie around the piston rod. The oil which leaks past the bearing seals, is drained through drain pipes 45 and .46 at the outer ends of =the cylinders. The piston rods 43 and 44 are operated diaphragm l3 acting on a pivoted lever 14 carrying the usual weight I! which .is a function 'of the boiler pressure. The pivoted lever 14 acts on an ordinary jet pipe regulator or relay It in opposition to a spring 11, the compression of which is controlled orrggulated by the cam 13 connected to be actuated by a piston 13 in a 1 cylinder 23, the latter communicating with the Jet pipe relay w-throuahpipea' 2| and 22,. The

connected through pivoted levers 41 and 43, re-' I spectively, to operate control valves 43- and 7 coupling 33 through the pipe '52 and a cooler 53 is shown as being connected between the supply and drain pipes 32 and II.

The arrangement of the control means for the

valves

49 and 50 is such that only one valve is operated at any time and the other has to wait until said one valve is closed to be actuated. For normal variations in the condition under 'regulation', the pistons 35 and 35 will actually wait upon each other to return by spring action to their normal positions. For example. if piston 35 is displaced from normaland piston 35 is required to move, the piston 36 will have to wait upon piston 35 to return to its normal position before it can move. This surprising operation is due to the orifice action of the two orifices in the jet pipe relay 24. When one piston is moving, oil flows into one orifice and out the other through

pipes

31 and 33. There is a positive drop in the pressure in the line where oil fiows in and a rise or negative drop in pressure in the line through which the oil flows out. If the pistons are held fixed and the jet of the relay 24- is moved a certain distance to the left, the pressure in the branches 39 and 40 will increase; while the pressure in branches 4| and 42 will be somewhat less, say about 55# and 45#, respectively. If the jet is displaced in the opposite direction or to the right of the center, the pressure in the branches 4| andv 42 will increase and the pressure will decrease in branches 39 and 40. If, with the jet pipe displaced to the left and pressures of, say 55# and 45# respectively present in the branches 39-40 and 4l-42 respectively, the pistons are released, the piston 35 will move and the piston 35 will remain stationary,

31 and out of pipe 38. Then the pressure in the pipe 31, due to' the oil flow, will drop to, say 52# and the pressure in pipe 38 will rise slightly to, say 48#. Now, if the Jet pipe of relay 24 is' displaced the same distance to the right of center, piston 33 will reverse its movement and hasten back to its normal or valve closing position. Oil will then flow rapidly through the branch 4| and pipe 33 and keep the pressure in the branches 38 and 40 actually less than 50# and the pressure in 4| and 42 will be more than 50#, thus preventing the piston 35 from moving. As soon as the piston 35 stops moving, the pressures immediately change to about, say 55# and 45# in the conduits 38 and 31 respectively and as soon as movement begins, it will almost immediately change to about 52# and 48# respectively, due to the flow of oil caused by the positive and negative drops across the'orifices in the Jet pipe relay 24. In this way, one valve waits to start until the other has returned to normal waiting position,

It will be understood that the hydraulic coupling 53 is driven by an ordinary motor M and is connected to operate the fan 53 at variable speeds depending upon the air requirements for the boiler furnace and controlled by the amount asoasoo and the drawing. The bubbling device 30 measures the oil level in the sump 21 and this level determines the oil level in the coupling 53. In most instances, the level in the coupling is inversely proportional to that in the sump. The bubbling device 30 has a further function in that it acts as a generator of control impulses for the.

diaphragm 25 which acts on the jet pipe relay 24 to actuate'thevalves 49 and 50 through the servo-motors or valve control means 35 and 35. Thus, the pressure maintained in the line is proportional to the depth of the submerged end 30 and is a function of the oil level in the coupling.

011 would then be flowing into pipe I The system according to the invention has many advantages and particularly the diiferen tial operation of the piston motors 35 and3 eliminates the necessity of a packing and with the drain lines and 45 the motors are practically friction free. The springs in the motors are just sufficient to keep the valves closed or drag and results in a practically friction free motor.

The cross connections 33 and 4| result in the operation of the pistons or servo-motors 35 and 35 in such a way that they will actually wait upon each other to return to normal position; that is if one is returning to normal-l position, the other will not move until the first one reaches normal.

' In other words, if piston 35 is displaced from normal and piston 38 is required to move, piston 35 will wait for piston 35 to return to normal 1 before starting to move. This, as has been exof oil fed to the coupling. The fan 55 delivers air to the boiler furnace through a conduit 51.

In this instance, fluid fuel is delivered to the furnace through a conduit 53 and its supply is controlled by an ordinary Jet pipe regulator 53 connected to be operated by differential furnace pressure through the usual diaphragm 50 plained. is due to the orifice action of the two orifices in the relay 24, since when a piston 35 or 35 is moving, oil is flowing in its respective orifice and out of the other orifice. There is a positive drop'in the pressure in the line when the oil flows in and a negative drop or rise in pressure in the line when the oil flows out of the orifice. In this way, one valve waits to start until the other has returned to normal waiting position.

ventlon utilizes thefull sensitivit of the control and reduces the dead or insensitive spot in a control -to a minimum to thereby improve the stability of the control and eliminate hunting.

It is of course obvious that all features shown and described need not be used conjointly. Also, the invention is not limited to the exact embodiment shown and it is not indispensable that all the features of the invention be used conjointly, since they may be employed advantageously in various combinations and sub-combinations.

We claim as our invention:

1. In an-automatic control system of the class described including a hydraulic coupling and embodying a pair of valve controlled conduits for the coupling fluid and a regulator tor the coupling including a jet pipe relay responsive to. a controlled condition aflected by the coupling, a device for operating the valves in said conduits comprising a pair of double-acting servo-motors tive outlet pipes of the jet pipe relay, and said cross-connections preventing simultaneous operation of the valves.

2. An automatic control system, as set forth in claim 1, in which the system is provided with an oil sump to; the hydraulic fluid and an air bubbling device is associated with the oil sump and connected to create control impulses-acting on the jet pipe relay in response to changes in level of the coupling fluid in the sump. 4

3. An automatic control system, as set forth in claim 1, wherein the servo-motors havepiston rods projecting through oil baiiles near one end 01' each cylinder to prevent friction and wherein an oil drain is connected-to each cylinder beyond said haiiies. v

HERBERT ZIEBOLZ. JAMES D. McCRACKEN DANIEL T. GUNDERSF