US1961790A - Fluid control system - Google Patents

Description

June 5, 1934. J. L. ROTH El AL FLUID CONTROL SYSTEM Filed Feb. 24. 1931 2 Sheets-Sheet l INVENTORS 1 6% M WITNE 555s June 5, 1934. .1. 1.. ROTH ET AL FLUID CONTROL SYSTEM Filed Feb. 24. 1951 2 Sheets-Sheet 2 INVENTORS WW (P M 9 WITNESSES Ma Patented June 5, 1934 FLUID CONTROL SYSTEM Joseph L. Roth and William R. Paulsen, Pittsburgh, Pa., assignors to American Heat Economy Bureau, Pittsburgh, Pa., a corporation of Delaware Application February 24, 1931, Serial No. 517,863

Claims.

This invention relates to an improved system and apparatus for regulating the operation of a furnace or combustion chamber in which liquid fuels are employed, although it is not necessarily so limited.

The primary object of the invention generally stated is to provide a dependable and comparatively simple system of control for positively regulating the rate of flow of liquid fuels and particularly heavy fuels such as heavy oils, coal tar, and the like to the combustion chamber of an open hearth furnace or similar liquid fuel consumer.

It is also an object to provide for automatically controlling the flow of the combustion air supplied to the furnace in such a way as to maintain it in the proper proportion to that of the fuel at all times.

These and other objects, as well as the various other novel features and advantages of the invention, will be apparent when the following detailed description is read in conjunction with the accompanying drawings, of which Fig. 1 is a diagrammatic illustration of a plurality of liquid fuel burning furnaces, equipped with regulating apparatus constructed in accordance with the invention; Fig. 2 a vertical section taken on the line of flow through the rotary valve or pump arranged in the fuel line leading to each of the furnaces shown in Fig. 1; Fig. 3 a. vertical section of the same taken on the line III-J11 of Fig. 2; and Fig. 4 a vertical section taken through the pressure regulating valve employed for maintaining, the pressure drop across the rotary valve in the line substantially constant.

Heretofore considerable difficulty has been encountered in the regulation of furnaces and burners in which liquid fuels have been employed, and especially so where heavy fuels such as heavy oils, coal tars and the like have been used. This difiiculty has been due to a very considerable extent to the use of simple variable orifice type valves for controlling the flow of the fuel. It has been found that liquids of the nature of these fuels very rapidly foul such valves and otherwise so impair their operation that it is practically impossible to satisfactorily control the flow of such fuels by their use.

In accordance with this invention, to overcome such difficulties, a pressure is exerted on the fuel supply and a positive displacement valve or metering device such as a freely working rotary pump is arranged in the fuel line and rotated at speeds corresponding to the amount of fuel. desired. To render the flow of the fuel positively and directly proportionate to the speed of rotation of the valve, pressure regulating mechanism is arranged in the feed line to maintain a substantially constant differential of pressure on the two sides of the valve so that the valve always operates under substantially the same conditions of operation and is uninfluenced by any variations in pressure which may take place in the fuel supply above the pressure necessary to force the fuel into the furnace.

A further feature of he invention is the provision of means operably coupled with the fuel controlling mechanism for automatically controlling the flow of the air supplied to the furnace to support the combustion of the fuel.

Referring now to the drawings, the invention is illustrated in connection with a pair of furnaces 1 and 2, to which liquid fuel is furnished by a pipe 3 connected to any suitable source of supply. In accordance with the invention a pressure suflicient to force the fuel into the furnaces must be exerted on the fuel in this pipe. Such pressure, however, may be produced in any suitable manner, such for example, as by connecting the pipe to a reservoir having a Sllfilcient elevation or by employing a power driven pump, such as is the pump 4 arranged in the supply line 3 ahead of furnace 2, as indicated in Fig. 1.

For conducting the fuel to the furnaces from the pipe or header 3, feed or flow lines 6 and 7 are employed and in them positive displacement rotary pumpsor valves 8 and 9 are arranged to separately control the flow of the fuel to each of the furnaces. These devices may be of any suitable type or form having positive displacement characteristics, but are illustrated here, as shown, more particularly in Figs. 2 and 3, as comprising a well known form of construc tion, the details of which are described more clearly hereinafter.

For controlling the operation of pump 8 a motor 11 is utilized, and to provide for varying the speed of the pump a speed-changing device 12 is arranged between it and this motor. While to render the rate of flow of the fuel in line 6 directly and positively proportional to the speed of rotation of pump 8 a pressure regulating valve 13 is provided in line 6 at some suitable point such as between the pump and the feeder line 3 and adapted to maintain a substantially constant difference in pressure across the pump independently of pressure variations in the header 3 This valve, as shown in detail in Fig. 4, comprises a casing 5 having in it an inlet and an outlet chamber separated by a valve opening in which a valve 18 is arranged to seat. At the top of the casing there are located a pair of pressure chambers 14 and 15 divided by a flexible diaphragm 16 to, which a valve 18 is connected by a valve stem 17. As shown, the pressure chamber 14 is connected to feed line 6 between valve 13 and pump 8 by a pipe 19, and pressure chamber 15 connected to line 6 between the pump and the furnace by a pipe 21. By reason of this arrangement the diaphragm 16 and valve 18 are rendered responsive to the difference in pressures on the two sides of the pump 8. Consequently, it is adapted to automatically determine and maintain a substantially constant difference in pressure drop across the pump, whereby the pump is caused to operate under uniform conditions at all times, thereby making the volume displacement of the pump dependent directly upon its speed of rotation. Hence, the device 8 does not function as a pump but merely as a valve or metering device, and in addition is in no way effected by variations in pressure in the feeder line 3 or line 6. To provide for varying the defference in pressure drop across the pump a spring 10 may be mounted on diaphragm l6 and a screw 10a employed to determine the pressure the spring exerts upon the diaphragm.

For supplying air to furnace 1 a motor actuated fan 22 is provided and connected to the combustion chamber of the furnace by a suitable conduit 24. To control the flow of air through this fan its inlet 25 is provided with an. orifice 26 and equipped with a butterfly valve 27. This latter valve is in turn connected to a pressure responsive regulator 28. While any suitable regulator may be used for this purpose, a well known form is shown which comprises a pair of bells 29 and 31 supported on a pivotally mounted lever 33, with their lower ends immersed in a suitable fluid contained in a tank 32. For actuating valve 27, a connecting link 34 is connected between a crank 27a, attached to it and lever 33. To those well versed in the art it will be understood that this method of measuring air is one of several types, the use of any one of which is equally applicable to the practice of this invention.

To render the regulator 23 responsive to the flow of fuel in line 6 a positive displacement blower 35 is connected to shaft 36 either directly as shown or by means of gears to which the pump 8 is connected and is accordingly rotated at a speed that is proportional to the speed of the pump. On the inlet of this blower there is connected a negative pressure tube 37 having an orifice 38 in its outer end for aiding in building up a negative pressure in the tube. With such an arrangement a negative pressure is developed in tube 37 which varies with the speed of pump 8, or in other words with the flow of fuel in line 6 and in exactly the same manner as the pressure is varied in the inlet 25 of the fan 22 by the flow of air through the fan. From the tube 37 a pipe 39 is extended upwardly through tank 32 into hell 29, whereby that bell is constantly under the influence of the pressure produced by blower 35 and the bell thereby rendered responsive to the speed of pump 8 or flow of fuel in line 6. In a similar manner, a pipe ll is extended from a point in the inlet 25 of fan 22 between the orifice 26 and valve 27 through the container 32 into bell 31, placing the latter constantly under the influence of the pressures obtaining in the fan inlet and thereby rendering regulator 28 responsive to the differential of the pressures obtaining in the tube 37 and the fan inlet 25. Consequently, any variation of pressure on either bell which may be due to a change in speed of the pump 8 or fan 22 will result in a shifting of valve 27 toward a position tending to maintain the flow of air to the furnace in a definite proportion to that of the fuel.

If desired, as shown in connection with the control for furnace i, a by-pass line 43 may be connected in shunt relation with valve 13 and pump 8 so that in case either of these mechanisms fail, or for any reason it is desired to cut them out of the system, the fuel may be passed around them through the line 43. For controlling the fiow of fuel when so directed, a hand valve 44 is provided in the by-pass line.

In the control apparatus employed for con trolling the flow of fuel to furnace 2, and which is designated by the same corresponding characters as those used with furnace l, a modification of the invention is shown wherein instead of operating pump 8 by a motor, such as done in connection with furnace 1, a sufficient pressure drop is maintained across the pump, by adjusting the spring in valve 13, to drive the pump as a motor. With such an arrangement in order to insure positive control of the pump, a positive displacement blower 46, which may have the same details of construction as the pump 8 and blower 35, is connected to shaft 36 to function as a fluid brake. In order to operate this latter blower in such a capacity a valve 47 is arranged in its inlet and this operated by a lever 48. This lever is in turn connected to a piston disposed in a pressure cylinder 49 connected by a pipe 51 to the pressure tube 37. Consequently, any variations in pressure in tube 37 such as may be produced by variation in speed of pump 8 and blower 35 are transmitted to the piston of the cylinder 49 and thence to the valve 47 with the result that the speed of the pump is prevented from exceeding a selected value and relieved of braking effort to permit it to regain its speed in case it attempts to fall below the value selected. Various ways of increasing or decreasing the flow of fuel can be employed such, for example, as by changing the fulcrum on lever 48 or by arranging a sliding weight 48a on the tail end of lever 48.

Another feature of the system resides in the provision of a meter 42 connected to the tube 37 to indicate at all times the pressures produced by the blower 35. For this purpose a meter adapted to make a graphic record of the pressures obtaining in the pressure tube at each 1 instant is employed and so calibrated that it reads the amount of fuel delivered to the furnace per unit of time. It is also provided with well known means for indicating the total amount of fuel supplied to the furnace during a period of operation. It is not believed necessary to show or define the construction and details of such a meter as such are so well known in the ar'.

For the details of construction of the pumps and blowers referred to hereinabove, reference is to be had to Figs. 2 and 3, wherein a construction is shown suitable for use as either the pumps 8 or blowers 35 and 46 and as illustrated comprises a cylinder casing 51 having therein suction and discharge openings 52 and 53 which communicate with inlet and outlet chambers 54 and 55 respectively. These latter chambers are divided by a center plate 56 into two compartments and communicating with each of the latter are a pair of pump chambers 57 and 58 of cylindrical form. Through the center of these chambers drive shaft 36 is passed and suitably supported. Upon such shaft a pair of annular plungers 59 are eccentrically keyed, the two being diametrically opposed to each other on opposits sides of partition 56 and adapted to contact with the walls of the pump chamber as the shaft rotates. Attached to the upper sides of plungers 59 are a pair of hollow extensions 63 having openings 64 near their lower ends and openings 65 in their upper, the latter oommun icating with the pump outlet chamber 55 and the former with the compression chambers on the outlet sides of the rotating plungers. These extensions are arranged to move in ball and socket guides 66 and to connect the pump compression chambers with the pump outlet chambers 55.

In practicing the invention as shown, motor operated pump 4 is first started to place the fuel in the header line 3 under pressure. To oper ate furnace 1 pump motor 11 and the motor of fan 22 are excited, and the hand valve 67 in pipe line 6 then opened. When this is done the liquid fuel flows into pipe line 6, thence through the pressure regulating valve 13 and rotary pump 8 to the furnace. At first valve 13 acts under the influence of the inlet pressure only, but as soon as the fuel passes valve 8 a pressure is set up in pipe 21. and valve 13 adjusts itself to permit the passage of only sufificient fuel to maintain a pro-selected pressure differential across the rotary valve.

Simultaneously with the starting of motor 11 and fan 22 a negative pressure is built up in the tube 37 and in fan inlet 25. These pressures are communicated by pipes 353 and 41 to bells 29 and 31 of the regulator 28 and as a result the butterfly valve 2? is operated to control the amount of air passing through the fan to the furnace according to the flow of fuel. Furthermore, meter 42 also starts to operate and makes a definite record of the amount of fuel flowing into the furnace at all times, so that the fuel consumption of the furnace may be constantly checked.

To set furnace 2 in operation its fan 22 is set in motion and the valve 67, provided at the inlet end of feed line 7, opened. With the opening of valve 67 pump 8 blowers 35 and 46 begin to move, due to the influence of the head pressure in the fuel line. they rotate a pressure is established in tube 3". and the air supply control is set in operation in the same manner as described in connection with furnace 1; also brake 46 is caused to func ion automatically in the manner previously described.

Among the chief advantages of this invention, as pointed out above, is that the fuel is positively and effectively regulated independently of any variations in pressures which may occur in the fuel supply. Another important advantage is that the air supply employed to support the combustion of the fuel is effectively and positively varied automatically in proportion to the fuel supply whereby the furnace is caused to operate at its highest efficiency at all times.

According to the provisions of the Patent Statutes, we have explained the principle and mode of operation of our invention, and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. The combination with a furnace of a supply of liquid fuel under pressure, a feed line connecting said furnace with said fuel supply, a rotary valve disposed in said feed line, means for maintaining the pressure differential on the two sides of said valve at a substantially constant predetermined value, means for supplying air to said furnace and means for automatically maintaining the amount of air supplied to the furnace proportionate to the flow of fuel.

2. The combination with a furnace of a supply of liquid fuel under pressure, a feed line connecting said fuel supply with the furnace, means for supplying air to the furnace to support the combustion of the fuel, a positive displacement rotary valve disposed in said feed line for controlling the flow of fuel, means for maintaining the pressure difierential on the two sides of said valve at a substantially constant value, means for controlling the speed of operation of said valve, means for producing a force bearing a definite relation to the speed of said valve and means arranged to be responsive to the force so produced for controlling the amount of air supplied to the furnace.

3. A liquid fuel regulating system comprising a furnace, a supply of liquid fuel under pressure, a feed line connecting said fuel supply with said furnace, meansfor supplying air to the furnace to support the combustion of the fuel, a positive displacement pump arranged in said feed line, means for driving said pump at a predetermined speed, means for maintaining a pressure differential between the two sides of the pump at a substantially predetermined constant value, a blower operably coupled to the pump and adapted to produce a force bearing a definite relation to the speed of the pump, and means responsive to the force produced by said blower for automatically controlling the air supply.

4. A liquid fuel re ulating system comprising a supply of liquid fuel under pressure, a feed line connecting said fuel supply with a furnace, means for supplying air to the furnace to support the combustion of the fuel, a positive displacement pump arranged in said fuel. line, means for driving said pump at a predetermined speed, a pressure regulating valve in the feed line, means for operating said valve in accordance with difference in pressure on the two sides of said pump, a blower coupl d to the pump for producing a force varying with the speed of the pump, means for producing a force varying with the flow of air through the air supplying means, and balancing means responsive to the differential of said forces for controlling the air supply.

5. In combination with a plurality of combustion chambers, a source of liquid fuel, means for supplying said fuel to said combustion chambers under pressure, a plurality of separate fuel lines connecting sai fuel supply with each of said combustion chambers, a positive displacement rotary valve arranged in each of said fuel lines, means for maintaining the pressure differential across each of said valves at a substantially constant predetermined value, means for controlling the speed of rotation of each of said valves, means for supplying air to each of the combustion chambers, and means operated in accordance with the speed of operation of each of said valves for automatically controlling the air supply to the combustion chambers associated therewith.

' JOSEPH L. ROTH.

WILLIAM R. PAULSEN.

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