KR810001783B1 - Conttollable distribution system for rotary kiln - Google Patents

Abstract

A rotary kiln includes an elongated ore reductionchamber and a nozzle which communicates with the chamber. Respective gas and fuel valves are associated with the nozzle and respective conduits supported on the kiln. Axially spaced cams are supported on the kiln for selective operation of the respective valves as they are rotated. Both the fuel and air flow through the same fluid distribution nozzle. Separate shut-off valves are provided for both the air and fuel supplies.

Description

Fuel and air supply controls for rotary kilns

1 is a side view of a portion of a rotary kiln showing a device according to the invention.

2 is a cross-sectional view of a representative valve that may be used in the present invention, in which the valve is shown in a closed, ie off state.

3 is a cross-sectional view of the FIG. 2 valve showing an open, ie on state.

4 is a view showing an operation sequence of an operation cam for controlling a fuel valve.

5 is a partially developed view showing a cam trip sequence.

The present invention relates to an apparatus for controlling the supply of air and fuel to a nozzle of a rotary kin used for the purpose of reducing iron ore in a low oxidation state. The nozzle is mounted on the outer surface of the kiln so as to radially project through the shell of the kiln, and has control means arranged to inject air or fuel into the kiln selectively through each nozzle and the same nozzle, In particular, the present invention allows the control means to be adjustable to vary the time interval at which air or fuel is injected through the nozzle during rotation of the rotary kiln.

Conventionally, rotary kilns are known, in which a plurality of fluid supply nozzles are installed through the body of the kiln to inject air and fuel into the rotary kiln or into the ore reduction chamber. The ore is charged into a reduction chamber and reduced to high reduced iron. Examples of such conventional kilns are described in US Pat. Nos. 1, 216, 667, 2, 091, 850 and 3, 182, 980.

In a conventional rotary kiln, fuel and air are injected through the nozzle by a pipe supported outside or inside the kiln. The pipe is connected to a nozzle for injecting fuel and air into the reduction chamber. In a recent prior patent, a mixture of fuel and air was injected at the same time through a nozzle, or fuel was injected through one nozzle and air was injected through another nozzle.

In some cases, it is desirable to inject only one fluid through the nozzle when the nozzle is under the charge, and to inject another fluid when the nozzle is over the charge.

As an example, it may be desirable to inject fuel through the nozzle into the reduction chamber when the nozzle passes just below the charge bed so that the fuel flows directly into the charge. When this nozzle is moved past the charge bed, it cuts off the fuel, preventing the fuel from passing through the nozzle, while simultaneously injecting air over the charge in the reduction chamber through another nozzle. Before these air nozzles pass under the charge layer, the air is disconnected to prevent fluid from passing through these nozzles as the nozzle passes under the charge layer. Such a structure is shown in the above mentioned U.S. Patent Nos. 3,182,980.

In the description of the known art, it can be seen that a very large number of nozzles are required. It is common for 300 nozzles to be installed in a rotary kiln of 150 feet in length. Furthermore, these nozzles receive extremely high heat of 1093 degrees Celsius (2,000 degrees Fahrenheit). The fluid itself tends to cool the nozzle while the fluid flows through the nozzle. However, the fluid does not pass through the nozzle When not cooled down, the nozzle temperature is close to the temperature of the reducing room, reducing the useful life of the nozzle.

Thus, it would be desirable to provide a facility for dispensing fluid to a nozzle of a kilon where air and fuel are injected through the same nozzle at different points of rotation of the kiln. Such facilities are described in US Pat. Nos. 3, 794, 483 and 3, 847, 538.

When the rotary kiln is heated to the desired temperature, it is advantageous to inject air through all nozzles at the maximum rotation of the kiln. This flow of air helps to cool the nozzle and keep the nozzle clean.

An apparatus for operating the kiln in this way is described in US Pat. No. 3,945,624.

Thus, (1) injecting only air through the kiln through all the nozzles, (2) injecting fuel only through all the nozzles, and (3) applying the same nozzle at several rotational positions of the nozzle relative to the ore bed position in the kiln. To alternately supply air and fuel through the air, and to provide a more flexible device than the known control method for controlling the distribution of air and fuel to the nozzles of the rotary kiln to perform their combined operation. desirable.

Accordingly, a primary object of the present invention is to provide a rotary kiln with an improved device for controlling the distribution of air and fuel to the fluid supply nozzles of the rotary kiln, which control device is more operational in operation than known control schemes. It is flexible and satisfactorily overcomes the problems and disadvantages of the prior art.

According to the invention there is provided a plurality of nozzles mounted thereon for rotation with an elongated cylindrical ore reduction chamber kiln for injecting fluid into the ore reduction chamber; Fuel and air conduits rotatably installed therewith with a kiln; An air valve connected with each nozzle and air conduit and selectively operable between an open and a closed position to allow and block the flow of air from the air conduit through each nozzle into the ore reduction chamber; For rotary kilns with fuel valves connected to each nozzle and fuel conduit and selectively operable between open and closed positions to allow and inhibit the flow of fuel from the fuel conduit through each nozzle into the ore chamber: air A pair of axially spaced and rotatable air cams connected to each other and to each air valve and selectively supported by a kiln to selectively perform “air injection” and “air disconnection” operations when the cam is rotated; A pair of axially spaced and rotatable materials supported by the kiln away from the air cam and connected to each other and to each fuel valve to selectively perform “fuel injection” and “fuel disconnect” operations when the fuel cam is rotated. One fuel cam; Adjacent to and supported by the kiln on an axially spaced plane coincident with the faces of the fuel cam and the air cam so as to selectively engage the cam on the same plane upon rotation of the kiln, each cam of the pair of connected cams associated therewith Four trips disposed in relationship with the cams to engage the trip and select its other connected cam to engage the trip associated therewith; Selectively move each trip between a first position in which the trip engages the associated cam to operate the valve and a second position in which the trip departs from engagement with the associated cam and leaves each valve in an inoperative state. A fuel and air supply control device for a rotary kiln is provided which comprises a trip actuating device which is operable and which is connected to each trip.

Each trip operation device is preferably a servomotor-actuated rocker arm having one end rotatably connected to the fixed frame and the other end having a cam engagement roller. Is operated by a control valve operated by an electrical relay.

Each cam is preferably a longitudinally extending plate member having a tripping surface disposed opposite one end, and each pair of air cams or fuel cams has their longitudinal axes disposed at 90 ° relative to each other. It is mounted on the cam shaft.

The present invention will be described in detail below as an embodiment with reference to the accompanying drawings.

In the figure, a rotary kiln is illustrated having a long cylindrical body 5 which forms a cylindrical reduction chamber, ie a combustion chamber 6. The body or inner wall of the kiln can be made of a suitable refractory material such as a firebrick. Any known means for supporting and rotating the kiln may be installed. Since such means do not form part of the invention and are well known, they are not described and illustrated here.

A plurality of nozzles 7 arranged axially at regular intervals on the circumference are installed on the surface of the kiln with opening into the kiln reduction chamber. These nozzles may be constructed in accordance with the present US Patent Nos. 3,784,107. These nozzles are provided in the kiln by outer plates as shown in the patent.

In addition, fuel and air conduits and 9 are respectively provided at regular intervals on the outer surface circumference of the kiln. Manifolds 10 for supplying fuel and air to conduits 8 and 9 are respectively installed in a conventional manner. The fuel supply means 11 connects the conduit 8 and the air conduit 9 to the nozzle 7 and has a plurality of valves 12 for air control and a plurality of valves 13 for fuel control. These valves are selectively operable between the open and closed positions to allow and prevent the flow of respective fluids, ie fuel and air, through the conduits to nozzle 7.

Specific valves 12 and 13, shown for purposes of illustration, are shown in greater detail in FIGS. 2 and 3. Each valve consists of a valve body 14 having an inlet 16 and an outlet 17. Rotating plug 18 with passage 19 is supported by the rotor body with rotating material. A valve stem 20 extending to the outside of the valve body is attached to the valve 12, and a valve stem 21 extending to the outside of the valve body is attached to the valve 13. Plug 18 is located between the off position shown in FIG. 2 to block the flow of fluid through the valve and the on position shown in FIG. 3 to allow fluid to flow through the valve. Rotatable.

Before starting the reduction process and fuel injection into the reduction chamber, it is necessary to preheat the kiln to the operating temperature, in accordance with conventional kiln operation. This is accomplished by rotating the kiln while the main burner (not shown) heats the reduction chamber. In this preheating operation, it is advantageous to inject air through all the nozzles 7, which can be used to clean and cool the nozzles and also to assist the main burners during the preheating of the kiln.

After the kiln has been preheated to the appropriate operating temperature, it is desirable to inject fuel only through the nozzles below the ore charge from fuel conduit 8 and to inject air only through the nozzles above the ore charge from air conduit 9. For this purpose, cams and cam trips are provided to provide variable actuation of valves 12 and 13 as described below.

4 and 5, the frame 22 is arranged around the kiln and four cam trips 23, 24, 26 and 27 are installed on the frame. Trips 23 and 24 are operable to air as described below, and trips 26 and 27 are operable to fuel as described below.

Each of these trips is configurable to move between the cam engagement position and the cam release position. The adjustment of the trip is achieved by a separate hydraulic sub motor 22 connected to each trip 23, 24, 26 and 27. Each submotor has a casing rotatably connected to frame 22, and the servo motor piston rod is connected to the rocker arm 25.

The locker arm 25 of each servo motor has a two-armed lever arm 30, one end of which is pivotally connected to the frame 22 and the cam roller members of the cam trips 23, 24, 26 and 27 supported by the rotating material at the ends. Is firmly connected to Each servo motor is operated by control valve V (FIG. 4), which is operated by an electrical relay R which is controlled from a remote control. Pump P is installed to pressurize the servo motor fluid from sump 29.

Each fuel valve stem 21 is connected to a pair of axially spaced cams 32 and 33 rotatably therewith to a fuel cam shaft 31 rotatably mounted to the outer side of the kiln.

Each cam 32 and 33 is in fact a longitudinally extending plate as shown in FIG. 4 with trip-engaging pores. The two plate cams 32 and 33 are mounted on the cam shaft 32 with their longitudinal axes disposed at 90 ° relative to each other as shown.

Cam 32 is an open cam for opening fuel valve 13 for fuel injection, i.e. a fuel injection cam, while another cam 33 is a closing cam for closing valve 13 for fuel cutting operation, i.e. It is a “fuel cut” cam. Each open and closed cam 32 and 33 has two trip-engagement surfaces for engaging trips 26 and 27, respectively. Such operation is described in more detail in the operation of the instrument described below.

Each air valve stem 20 is connected to an air camshaft 34 which is rotationally mounted on the outer side of the kiln by a support bracket 36. In addition, a pair of axially spaced longitudinally extending air cams 37 and 38, similar to fuel cams 32 and 33, have their longitudinal axes disposed at 90 ° relative to each other in a manner similar to that of fuel cams 32 and 33. It is attached to 34.

Cam 37 is an open cam for opening the air valve 12 for “air injection” operation, ie an “air injection” cam, cam 38 is a closing cam for closing to close valve 12 for “air disconnection” operation, That is, the “air disconnection” cam.

As with the fuel cam, each air cam 37 and 38 also has a pair of trip-engagement surfaces for engaging trips 23 and 24. Each of the four cams (air) 32, 33 and (fuel) 37, 38 is located on an axially spaced plane.

The operation of the apparatus will be described in detail below with reference to FIG. 4, which shows only the fuel cam.

Open the outer valve (not shown) for supply of air and fuel so that air enters conduit 9 and fuel enters conduit 8. The main burner (not shown) is ignited inside the reduction chamber to preheat the kiln. The relay R for fuel injection trip 27 is activated to bring the trip to the position where the engagement with the cam is out of position. In such a position, the piston rod of the “fuel injection” servo motor 28 moves into the servo motor cylinder to rotate each “fuel injection” lever arm 30. The fuel injection trip 27 is thus withdrawn from the rotary passage of the fuel injection cam 32. The fuel cut trip 26 engages the cam so that when the kiln rotates the fuel cut trip 33 moves the fuel cut cam 33 to the valve closing position so that fuel does not pass through the fuel valve 13 and into the nozzle 7. In position (shown in FIG. 4). A suitable relay R operates to move the “air disconnection” trip 23 to the cam-off position away from the cam while simultaneously moving the “air injection trip 24” to the position that engages the cam. Thus, as the kiln rotates, the “air injection” cam moves the air valve 12 to the open position so that air flows into the reduction chamber.

Turn off the main burner (not shown) when the kiln is heated to the desired temperature. Next, the appropriate relay R is activated so that all trips 23, 24, 26 and 27 are in the cam engagement position. In FIG. 4 (using fuel injection and cam fuel cut cams 32 and 33 as an example), the fuel cut cam 33 contacts the fuel cut trip 26 as the kiln rotates. If the kiln continues to rotate, the “fuel disconnected” cam 33 is rotated to the upper position indicated by the dashed line in FIG. 4, so that the “fuel injection” cam (connected to the same cam shaft 31) engages with it when the kiln rotates. Make sure to engage properly with the associated trip. The cam and trip are located relative to each other so that only fuel flows through nozzle 7 under the ore charge (not shown) in the reduction chamber and only air flows through nozzle 7 above the mineral charge.

If further heating of the reduction chamber is required, only fuel is supplied through all nozzles 7 in the full rotation of the kiln. This can be accomplished by actuating relay R such that the “air injection” trip 24 is withdrawn to the position that engages the cam. At the same time, the relay R is operated to withdraw the fuel cut trip 26 away from the cam. Thus, when the kiln rotates, the “air disconnection” trip 23 activates the associated cam 38 to rotate the air valve 12 to its closed position.

When the air valve is closed, the “air injection” cam 37 engages with the “air injection” trip 24, but because the air injection trip 24 is withdrawn, the air valve engages the “air injection” trip with the cam. It remains in the closed position until it is moved back to the position. At the same time, because the “fuel disconnect” trip 26 is moved away from the cam, the “fuel injection” cam 32 engages with the “fuel injection” trip 27 to move the fuel valve 13 to the open position, Let it flow The fuel valve remains in the open position until the “fuel disconnection” trip 26 is moved back to the engaged position with the cam.

In addition, it is possible to allow fuel and air to flow through all the nozzles 7 or to block air and fuel from flowing through all the nozzles by proper operation of the relay R and proper arrangement of the cam trips 23, 24, 26 and 27.

When it is desired to reactivate the kiln in the desired manner by allowing fuel to flow through the nozzle under the charge and air through the nozzle above the charge, all trips 23, 24, 26, 27 Move to the position to engage the cam. As the kiln rotates, the cams are appropriately selected to open and close valves 12 and 13, respectively, to alternately flow air and fuel through the nozzle as desired.

From the above description, it can be seen that a wide variety of mechanisms are provided for regulating the distribution of air and fuel to the fluid supply nozzles of the rotary kiln having nozzles installed on the outer surface of the kiln to radially project through the body of the kiln. . By this mechanism, a wide variety of control operations and special control schemes can be achieved.

Claims (1)

Cylindrical ore reduction chamber, multiple nozzles for injecting fluid into the reduction chamber, fuel and air conduits rotatably installed with a kiln, air valves connected to each nozzle and air conduit, and fuel valves connected to each nozzle and fuel conduit In a rotary kiln, a pair of axially rotatable air cams (37, 38) are connected to each other and to each air valve and supported by the kiln, and at the same time, a pair of rotatablely axially separated. Fuel cams 32 and 33 are connected to each other and to each fuel valve and are supported by a kiln away from the air cam, and four trips 23, 24, 26 and 27 are provided for each cam of the fuel cam and the air cam. The kiln is supported and installed at an axially distant face corresponding to the face of the cams, associated with each of these trips, the first position and the trips of which the trips engage the associated cam and actuate the valve. A rotary actuating device (28) connected to each trip, characterized in that a trip operating device (28) is adapted to selectively move each trip between a second position that causes each valve to be inoperative by disengaging from the associated cam. A device for controlling the distribution of fuel and air to the nozzle of the kiln.

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