Valve apparatus

In a valve system for controlling the flow of liquid fuel and steam to a nozzle in a large scale power plant boiler, a pair of valves are operated by rotary pneumatic actuators. Three-position operation is achieved for one of the valves by coupling the valve shafts together through a lost-motion coupling and using an actuator for the other valve which delivers more torque than the actuator which operates the three-position valve. The same actuator and coupling system can be used for straight high pressure mechanical atomization, for mechanical atomization with recirculation, and for steam atomization, with simple substitution of rotary valves.

BRIEF SUMMARY OF THE INVENTION 
This invention relates to valves, and more specifically to a valve 
apparatus for use in controlling the flow of two different fluids 
alternately to a single destination. The valve apparatus of the invention 
has particular utility in large scale oil-fired power plant boilers for 
controlling the flow of liquid fuel and scavenging gas. 
Power plant boilers typically use No. 6 fuel oil, which is solid or nearly 
solid when at room temperatures. The oil is sprayed into the combustion 
chamber of the boiler through nozzles. Each nozzle has at least one feed 
line connected to it for carrying oil heated to approximately 190.degree. 
F. so that it is fluid, and for carrying steam or air. The steam or air is 
used for purging oil from the nozzle and the associated feed line and, in 
some cases also for dispersing the fuel into small droplets as it exits 
from the nozzle. 
There are three basic types of fuel dispersion methods in use in oil-fired 
power plant boilers. In the first method, known as "high pressure 
mechanical atomization", fuel is dispersed simply by spraying it through 
the nozzle. In the second method, known as "wide range mechanical 
atomization", fuel is recirculated through the nozzle, and the rate at 
which fuel is sprayed by the nozzle is controlled by adjusting the back 
pressure in the recirculation path. In the third method known as "steam 
atomization" or "air atomization", fuel is dispersed with the aid of steam 
or air which flows into the combustion chamber along with the fuel. 
Each combustion chabmer may have a large number of nozzles, and provisions 
are made for retracting the nozzles so that, under conditions of maximum 
load, all of the nozzles can be in operation, whereas under conditions of 
less demand, some of the nozzles can be retracted so that the nozzle tips 
are shielded from the flame. When a nozzle assembly is withdrawn, the flow 
of fuel is cut off. 
With all three atomization methods, previsions are made to purge fuel from 
the nozzle passages to prevent it from solidifying and clogging the 
passages when a nozzle is temporarily taken out of service. This is 
accomplished by providing for delivery of a scavenging gas, usually steam 
or air, to the nozzle passages in order to displace the remaining fuel in 
the nozzle passages before it cools and solidifies. For convenience, the 
scavenging gas will be referred to as "steam", as steam is the gas most 
commonly used. 
In the past, fuel and steam were controlled by manually operated valves. 
Steam-atomized systems included a valve in the steam line, a valve in the 
fuel line, and a cross-over valve which allowed steam to flow into the 
fuel line. 
Steam is normally supplied under a pressure higher than that of the fuel. 
Using the manual system, when a nozzle is withdrawn and shut down, oil is 
purged by steam from the portion of the oil feed line between the nozzle 
and the fuel shut-off valve. If the frame goes out as the nozzle is shut 
down, it will not automatically reignite as oil is purged. Consequently, a 
great deal of smoke can be produced. It is very difficult to prevent 
flame-out when shut-down of a nozzle is carried out using 
manually-operated valves. 
Auxiliary, kerosene-fired burners have been provided to insure against 
flame-out. However, a preferred method is to use an automatic valve such 
as a SKOTCH valve sold by Skotch, Inc. of 278 Main Street, Portland, Ct. 
06480. The SKOTCH valve is a linear-actuated valve controlling both steam 
and fuel flow so that steam is gradually fed into the passage between the 
fuel valve and the nozzle opening as fuel flow is shut off. The steam 
pushes the fuel out through the nozzle opening and purges the fuel line 
while the flame is maintained. Thus, when the nozzle assembly is later 
withdrawn, it is clear of fuel, and can cool down without fuel solidifying 
in it. 
The SKOTCH valve is heavy and complex. It includes two linear actuators 
which act in tandem to operate a specially-designed valve steam assembly 
which controls both the steam valve and the fuel valve in the appropriate 
sequence. 
The principal object of this invention is to provide a valve apparatus for 
controlling fluids such as liquid fuel and scavenging gas, which is more 
reliable and easier to use than prior manual systems, and which is also 
simpler and less expensive than prior automatic valve systems. It is also 
an object of the invention to provide a valve apparatus which is more 
versatile than prior systems in that it can readily be adapted to any of 
the three basic fuel dispersion methods by the simple substitution of 
readily available parts. 
A still further object of the invention is to provide a valve apparatus 
which is more compact than prior equipment provided for the same purpose, 
which is easily serviced, and which is lighter in weight. It is also an 
object of the invention to provide for control of the speed of operation 
of the valves in a valve system in order to achieve smooth transitions 
between operations and to avoid hammering which results from excessively 
rapid valve operation. 
Finally, it is an object of the invention to provide for visual indication 
of valve positions and to provide for manual operation as an alternative 
to automatic operation. 
The valve apparatus of the invention comprises two rotary valves, one being 
a two-position valve, and the other being a three-position valve. Each 
valve is controlled by an actuator, preferably a rotary, fluid-driven, 
vane-type actuator operated by air delivered to it through a solenoid 
valve. The actuator which operates the two-position valve is designed to 
deliver a higher torque than the actuator which operates the 
three-position valve. The two actuators (and thereby, the two valves) are 
interconnected through a lost-motion coupling which effectively limits 
rotation of the second valve so that, if the actuator for the second valve 
is operated while the first valve is in a first position, the second valve 
stops at its intermediate position. The second valve is allowed to move to 
its ultimate position only when the first valve moves to its second 
position. The lost-motion coupling, therefore, provides a simple means of 
achieving the three stages of operation required in each of the three 
basic atomizing methods. In the first stage, both steam and fuel are shut 
off. In the second stage, steam is delivered to the nozzle tip, thereby 
removing condensate and warming the nozzle to its operating temperature. 
The second stage is also used during shut-down of a nozzle to scavenge 
residual fuel between the fuel valve and the nozzle tip. In the third 
stage, fuel is admitted to the nozzle. In mechanical atomization, steam is 
shut off in the third stage but, in steam atomization, steam is delivered 
to the nozzle through a separate path. 
Details of the apparatus for carrying out these operations, and further 
objects and advantages of the invention will be apparent from the 
following detailed description when read in conjunction with the drawings.

DETAILED DESCRIPTION 
Referring to FIG. 1, the valve apparatus of the invention comprises a 
first, two-position, rotary valve 6 and a second three-positon rotary 
valve 8. Valve 6 has an inlet port 10 connectable to a fuel supply, and a 
movable ball element 12 coupled directly by coupling 14 to a rotary 
actuator 16. 
Valve 8 has an inlet port 18 connectable to a supply of steam or other 
scavenging gas such as air, and a movable ball element 20 connected 
through a coupling 22 to a rotary actuator 24. 
As will become apparent from the following description, the two valves can 
have various numbers of ports and internal passage configurations, 
depending on the application of the valve apparatus. In the preferred 
embodiment of the invention, valve 6 is a two-position valve rotatable 
through an angle of 90.degree., and valve 8 is a three-position valve 
rotatable through an angle of 180.degree.. 
The rotary actuators are preferably pneumatically driven vane-type 
actuators of the kind depicted in U.S. Pat. No. 4,474,105, dated Oct. 2, 
1984 and U.S. Pat. No. 4,475,738, dated Oct. 9, 1984. The disclosures of 
both patents are incorporated by reference. 
Each of the actuators is drivable by air pressure in both directions. 
Actuator 16 is designed to produce a greater torque than actuator 24 for a 
given operating air pressure, so that actuator 16 can establish an 
intermediate position for valve 8. Preferably, actuator 16 has a dual-vane 
rotor, whereas the rotor of actuator 24 has a single vane. 
A cross-over connection 26 is provided from port 28 of valve 8 to port 30 
of valve 6. A one-way check valve 32 may be provided in the cross-over 
connection, depending on the particular application of the valve 
apparatus. The check valve presents fuel from flowing into the steam or 
air supply lines. It is used in high pressure mechanical atomization and 
in steam or air atomization, but not in wide range mechanical atomization, 
because in the latter case fuel and steam flow in opposite directions 
through the cross-over line at different times. 
The actuators are operated by solenoid pilot valves 34 and 36. Each of 
these pilot valves is of a duel-coil design, requiring a momentary signal 
to actuate it. As each coil in a pilot valve is energized, the valve is 
shifted, and maintained in the shifted position without the need for 
further coil energization. Adjustable restrictors 35 and 37 are provided 
in the air passages to control the rate of operation of the actuators. 
Each actuator has its shaft extending through both of its ends, and the 
shafts of the two actuators are connected together through a lost-motion 
coupling 38. Coupling 38 comprises a first part 40 connected to the rotor 
of actuator 24, and having a generally rectangular projection 42. The 
coupling also comprises a second part 44 connected to the rotor of 
actuator 16. Rotor 44 has a hollow space receiving projection 42. As shown 
in FIG. 2, the hollow space of part 44 has a first pair of surfaces 46 and 
47, engageable by projection 42 to limit rotation of projection 42 in one 
direction, and a second pair of surfaces 48 and 49 arranged to limit 
rotation of projection 42 in the opposite direction. These surfaces are 
preferably so arranged as to allow projection 42 to rotate through an 
angle of 90.degree., assuming that part 44 of the coupling is held 
stationary. By limiting rotation of projection 42 these surfaces limit 
rotation of actuator 42 and the movable element 20 of valve 8. 
As shown in FIG. 1, coupling part 40 is provided a lever 50 and coupling 
part 44 is provided with a similar lever 52. These levers enable the valve 
to be operated manually for example in the event that the actuator air 
supply fails. 
Magnets 54 and 56 on the respective coupling parts actuate proximity 
switches 58 and 60. These proximity switches provide signals indicating 
the positions of the valves. The signals can be used simply to operate 
visual indicating devices, or can be delivered through wiring to automatic 
valve control apparatus. 
The lower part of FIG. 3 shows the three stages of operation of the 
actuators, and also the corresponding positions of coupling 38. At the 
left of FIG. 3, the rotor of actuator 24 is positioned fully 
counterclockwise, with its single vane 62 against a stop. The rotor of 
actuator 16 is also fully counterclockwise, with its two vanes 64 and 66 
resting against stops. Projection 42 of the coupling rests against 
surfaces 46 and 47 of coupling part 44. 
In the second stage of operation, depicted in the vertically aligned 
diagrams midway between the left and right sides of FIG. 3, the rotor of 
actuator 16 is in the same position as in the first stage of the 
operation. Likewise, coupling part 44 is in the same position. The rotor 
of actuator 24 is rotated clockwise by air pressure, but its clockwise 
rotation is limited to 90.degree. by the engagement of coupling projection 
42 with surfaces 48 and 49 of coupling part 44. 
In the third stage of operation, depicted at the right side of FIG. 3, the 
rotor of actuator 16 is rotated pneumatically 90.degree. clockwise. This 
causes part 44 of the coupling to rotate 90.degree. clockwise, allowing 
projection 42, and the rotor of actuator 24 to rotate clockwise, so that 
the latter is in its fully clockwise position, 180.degree. away from its 
initial position. 
Thus, as will be apparent from the lower portion of FIG. 3, the lost-motion 
coupling 38, and the counterclockwise torque exerted on the rotor of 
actuator 16 in the second stage of operation, permit actuator 24 to serve 
effectively as a three-position actuator. The three-position operation of 
actuator 24 is not essential when the mode of operation is simple high 
pressure mechanical atomization. However, three-position operation of 
actuator 24 is significant in the case of wide range mechanical 
atomization and in the case of steam atomization. 
The upper part of FIG. 3 depicts the three stages of valve positions for 
high-pressure mechanical atomization. Valve parts in FIG. 3 which 
correspond to valve parts in FIG. 1 are correspondingly numbered, but 
followed by the letter "A". 
In the first stage of operation, as depicted at the left of FIG. 3, both 
the steam supply and the fuel supply are cut off. In the second stage, 
movable element 20A of valve 8A rotates 90.degree. clockwise while movable 
element 12A of valve 6A remains in its initial position. Steam flows 
through valve 8A, through cross-over connection 26A, and through passage 
70A and port 68A of valve 6A to the nozzle. The steam clears the passages 
between valve 6A and the nozzle of condensate, and warms the nozzle to 
operating temperature. The application of steam to the nozzle can be under 
timer control. 
In the third stage, valve element 12A is rotated 90.degree. clockwise. This 
allows valve element 20A to rotate through another 90.degree., shutting 
off the steam supply. Fuel passes through port 10A, passage 70A and port 
68A of valve 6A to the nozzle. 
When the nozzle is to be shut down, actuator 16 is pneumatically returned 
to the condition depicted in the middle diagram at the bottom of FIG. 3. 
This causes valve 6A to shut off the fuel supply to the nozzle, and at the 
same time opens valve 8A to admit steam to the nozzle. Opening of valve 8A 
occurs because the higher torque of actuator 16 overrides the torque 
urging the rotor of actuator 24 clockwise. As the movable element 12A of 
valve 6A is rotated counterclockwise to cut off fuel flow, valve 8A is 
cracked open, and gradually admits steam pressure (which is greater than 
the fuel pressure), through cross-over connection 26A, to the feed line 
between valve 6A and the nozzle. The steam pressure behind the fuel in 
this line maintains fuel pressure at the tip of the nozzle until all of 
the fuel is scavenged and burned. Thus, flame-out is avoided. Here again, 
the duration of the scavenging operation can be timer controlled. 
Upon completion of the scavenging operation, actuator 24 is operated 
counterclockwise to shut off valve 8A, thereby returning the apparatus to 
the condition depicted at the left of FIG. 3. 
FIG. 4 illustrates the diagrammatically a pair of valves, and three stages 
of valve positions for wide range mechanical atomization. The very same 
actuators and couplings are used as are used in the case of simple 
high-pressure mechanical atomization. The corresponding actuator and 
coupler conditions are as shown in FIG. 3, and are not duplicated in FIG. 
4. 
Valve 6B in FIG. 4 is a four-port, two-position valve having a fuel inlet 
port 10B, a recirculation port 72B, a cross-over port 30B, and a port 68B 
connectable to the return line of the nozzle. Valve 6B has two separate 
internal passages 78B and 82B. 
Valve 8B is a three-position, three-port valve having a steam inlet port 
18B, a cross-over port 28B, and a port 74B connectable to the feed line 
which carries fuel to the nozzle. A separate steam shut-off valve 76 is 
connected in series with port 18B. The valve element has a T-shaped 
passage 80B. 
The nozzle used in connection with the valving of FIG. 4 is a nozzle having 
a fuel feed line connected to port 74B of valve 8B and a fuel return line, 
connected to port 68B of valve 6B. The rate at which fuel is delivered 
from the nozzle is controlled by controlling back pressure by means of a 
control valve (not shown) connected to port 72B. 
In the initial stage, the valves 6B and 8B are in the conditions shown at 
the left of FIG. 4, and auxiliary steam valve 76 is shut off. Fuel from 
the fuel supply is recirculated through port 10B, valve passage 78B and 
port 72B. 
Before proceeding to the second stage of operation, auxiliary steam valve 
76 is opened to admit steam to the fuel feed line between port 74B and the 
nozzle. Thereafter, in the second stage of operation, valve 8B is rotated 
90.degree. clockwise, while valve 6B remains in its initial condition. 
Steam is delivered through port 18B, valve passage 80B, port 28B, 
cross-over connection 26B, port 30B, valve passage 82B and port 68B to the 
nozzle through the fuel return line. Thus, steam is admitted to the nozzle 
both through the fuel delivery line, and through the fuel return line in 
separate steps. 
In the third stage of operation, depicted at the right side of FIG. 4, 
valve 6B is rotated 90.degree. clockwise. At this time, the coupling 
allows valve 8B to rotate clockwise under the urging of actuator 24, 
through a further 90.degree. angle. Steam is shut off by valve 8B. Fuel is 
delivered through port 10B, passage 82B, port 30B, cross-over line 26B, 
port 28B, passage 80B, and port 74B to the nozzle. Fuel is returned from 
the nozzle through port 68B, valve passage 82B and port 72B. 
When the nozzle is to be shut down, valve 6B is rotated counterclockwise 
while air pressure continues to urge valve 8B clockwise. However, the air 
pressure urging valve 6B counterclockwise overrides the air pressure 
urging valve 8B clockwise, and accordingly, both valves 6B and 8B return 
to the condition depicted midway between the left and right sides of FIG. 
4. During this operation, steam is gradually admitted through port 68B to 
the nozzle, thereby purging fuel from the fuel return line. When purging 
of the fuel return line is complete, preferably under timer control, the 
actuator which operates valve 8B is operated to cause valve 8B to rotate 
counterclockwise through a further 90.degree. angle so that both valves 
are in their initial condition as depicted at the left of FIG. 4. 
Auxiliary steam valve 76 is then allowed to remain open for a period of 
time under timer control to purge oil from the feed line which delivers 
fuel from port 74B to the nozzle. 
FIG. 5 depicts the three principal stages of operation of the valve 
apparatus, when used in a steam atomization burner system. Valve 6C is a 
three-port, two-position valve having an L-shaped passage 82C in its 
movable element. Valve 8C is a three-port, three-position valve having a 
T-shaped passage 84C in its movable element. 
In the initial condition of the valves, as depicted at the left of FIG. 5, 
ports 10C and 18C are both closed, thereby cutting off the flow of fuel 
and steam. 
In the case of steam atomization, the nozzle is designed with separate 
steam and fuel lines. The steam line is connected to port 86C of valve 8C, 
and the fuel line is connected to port 88C of valve 6C. Ports 28C and 30C 
are connected by cross-over connected 26C. 
In the second stage of operation, valve 8C is rotated 90.degree. clockwise, 
while valve 6C remains in its initial condition. Steam is admitted through 
passage 84C and port 86C to the nozzle through the steam line, and is 
simultaneously admitted through valve passage 84C, port 28C, cross-over 
connection 26C, port 30C, valve passage 82C and port 88C to the nozzle 
through the fuel line. Thus, steam is simultaneously admitted to the 
nozzle through two lines. Admission of steam is carried out in this stage 
for a timer-controlled interval to warm the nozzle to its proper operating 
temperature. 
Thereafter, valve 6C is rotated 90.degree. clockwise by its actuator to the 
condition depicted at the right of FIG. 5. At this time, the lost-motion 
coupling allows valve 8C to rotate clockwise through a further 90.degree. 
angle to the condition depicted at the right of FIG. 5. Steam is admitted 
to the nozzle through valve 8C, and fuel is simultaneously admitted to the 
nozzle through valve 6C. The steam is used to effect atomization of the 
fuel at the nozzle tip. 
When the nozzle is to be shut down, the actuator which operates valve 6C is 
operated to cause valve 6C to rotate 90.degree. counterclockwise. Valve 8C 
is simultaneously forced to rotate 90.degree. counterclockwise to its 
intermediate position. At this time, steam is gradually admitted through 
port 88C to the fuel feed line leading from port 88C to the nozzle, 
thereby purging fuel from this line and from the nozzle while avoiding 
flame-out. After an appropriate timer-controlled purging interval, the 
actuator which controls valve 8C is operated to rotate valve 8C 
counterclockwise, thereby shutting off the flow of steam. 
As will be apparent from the foregoing, the valve system can be adapted to 
all three principal atomization methods simply by substituting valves, the 
other parts of the valve system being the same for all three cases. The 
valve system is structurally simple, inexpensive, and easily maintained 
because substantially all of its parts are readily available, 
off-the-shelf items. 
Modifications can be made to the apparatus described. For example, whereas 
in the specific embodiment shown in FIG. 1, the lost-motion coupling is 
connected directly to actuator shafts, if valves having shafts extending 
in both directions are used, the positions of the actuators and valves can 
be reversed, and the lost-motion coupling can be connected directly to the 
valves. 
Whereas, for simplicity, the valves rotate in 90.degree. steps, it is 
possible to use rotary valves which rotate through angular displacements 
other than 90.degree. in each step. 
While the valve apparatus has been described as an apparatus for 
controlling the flow of liquid fuel and scavenging gas in a power plant 
boiler, the valve apparatus can also be used in other applications where 
it is desired to control the flow of two different fluids alternately to a 
single destination. The valve apparatus can be used, for example in 
chemical processing where mixing or atomization is required, or in a 
cleaning apparatus, where two different fluids are applied to a surface to 
be cleaned. 
Further modifications and uses of the apparatus may be made without 
departing from the scope of the invention as defined in the following 
claims.