FIELD OF THE INVENTION
The present invention relates in general to controlling flow-rate of raw material discharged into the blast furnace, and more particularly to controlling material flow-rate by capturing position feedback of lower material gate (LMG) in bell-less top (BLT) charging system of blast furnace.
BACKGROUND OF THE INVENTION
Bell-Less Top™ charging systems have found widespread use in blast furnaces around the world. They commonly comprise a rotary distribution device equipped with a distribution chute, which is rotatable about the vertical central axis of the furnace and pivotable about a horizontal axis perpendicular to the central axis.
Further, for smooth operation of blast furnace, raw material has to be discharged according to required discharge pattern, in concentric rings. Lower Material gate (LMG) plays a vital role in achieving the desired pattern, by controlling the material flow rate. To control material flow rate, LMG has closed loop control system which control its opening. It is known that the closed loop system functions on the accuracy of its feedback system.
The existing state of feedback mechanism in lower material gate (LMG) of BLT is provided by encoders (main and standby). A common shaft, attached to the transmission gear among other components, rotates the two encoders which are attached to LMG. Since, the operating mechanism for both main and standby encoders is same, failure of common shaft causes failure of both the encoders. Thus, the sole purpose of having a standby encoder is defeated. Further, failure of both the encoders causes loss of production. Similar cases of failure have been reported in steel plants, for example, five times in H Blast Furnace at Tata Steel, in the last 3 years. Similarly, in G Blast furnace, such failure occurred twice in one year.
In essence, as also discussed above, the issues associated with driving shaft of the lower material gate (LMG) leads to the failure in the encoders. It was

observed as shown in Fig. 1 that stud 6 is the weakest link in the entire arrangement, since it is a welded portion in the circular disk. Any resistance in movement of transmission gear 7 or jerk due to hydraulic pressure leads to failure of welding joint. Without this, both encoders, main and standby, stop rotating along with LMG. This results in generating error in position feedback of the LMG, thereby holding the charging operation which in turn causes major delays.
To address all of the drawbacks of the prior art, there is therefore a need to develop an improved assembly designed such that the stand-by encoder is retained in the assembly and the need for common shaft is eliminated. The improved assembly implementing alternate feedback mechanism independent of any mechanical support needs to be designed such that the operating mechanism of both main and the standby encoder is made different.
OBJECTS OF THE INVENTION
An object of the invention is to overcome the aforementioned and other drawbacks existing in prior systems related to assembly for controlling flow-rate of the discharge material into the blast furnace through a charging system such as Bell-Less Top™ charging system.
Another object of the present invention is to propose an improved assembly for accurately capturing position feedback of lower material gate (LMG) in Bell-Less Top™ charging system of a blast furnace according to an embodiment of the invention.
Yet another object of the present invention is to propose an improved assembly independent of the mechanical shaft according to an embodiment of the invention.
Still another object of the present invention is to propose an improved assembly designed in order to reduce the mechanical delay occurring due to

wear of coupling between encoder and shaft according to an embodiment of the invention.
Still further object of the present invention is to propose an improved assembly designed in a manner so as to retain the standby encoder.
These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.
SUMMARY OF THE INVENTION
The present application discloses an improved assembly for controlling flow-rate of hopper material discharge in a bell-less top (BLT) charging system of a blast furnace. Further, in aspect, the improved assembly includes a lower material gate (LMG) 3 installed with one or more hoppers. In an embodiment, two hoppers are installed on the LMG 3. Further, the assembly contains a circular disc 4 arranged on surface of the LMG 3 which is operatively connected to an encoder 2. In an embodiment, circular disc 4 is attached to driving mechanism of lower material gate which produces angular movement (due to circular disk) according to gate (LMG) movement. Furthermore, in another aspect the assembly includes a rotating plate attached to the circular disc 4 with an inclinometer 5 mounted on a face end of the rotating plate at an extended angle and adapted for measuring position feedback of the LMG 3. In the improved assembly, alternate feedback mechanism which is independent of any mechanical support is achieved by using the inclinometer 5, thereby also retaining the standby encoder 2 which was becoming redundant in the prior art systems due to failure of the common shaft driving the LMG 3.
The above and additional advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The above brief description, as well as further objects, features and advantages, of the present invention can be fully appreciated by reference to the following detailed description. These features of the present invention will become more apparent upon reference to the drawings, wherein:
Fig. 1: Schematic representation of conventional encoder and shaft assembly attached to the lower material gate (LMG) of bell less top of H Blast Furnace.
Fig. 2a-2b: Illustrates redundant encoder assembly of a prior art feedback system.
Fig. 2c: Illustrates a common shaft/shaft as implemented in a prior art feedback system, failure of which causes failure of both the encoders (main and standby).
Fig. 3: Illustrates Schematic of the position of the inclinometer mounted on the plate attached to the circular disc.
Fig. 4: Illustrates an Inclinometer mounted on an extended angle of circular disc.
Fig. 5a: Illustrates operation performance trend when Encoder is used.
Fig. 5b: Illustrates enhancement in operation performance by implementing Inclinometer according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure. While the preferred embodiment has been described, the

details may be changed without departing from the invention, which is defined by the claims.
It will be apparent, however, to one of ordinary skill in the art that the present invention may be practiced without specific details of the well known components/ assembly and techniques. Further specific numeric references should not be interpreted as a literal sequential order. Thus, the specific details set forth are merely exemplary. The specific details may be varied from and still be contemplated to be within the scope of the present invention. The features discussed in an embodiment may be implemented in another embodiment.
Moreover, occasional references to the conventional assemblies are made in order to better distinguish the present inventive disclosure discussed later in greater detail. Few of the details pertaining to said assemblies are well known in the art and therefore, are described herein only in the detail required to fully disclose the present invention while unnecessarily obscuring the present invention.
Improving upon and addressing the problems discussed at length above (background), in the present disclosure an improved assembly for controlling material flow-rate in bell-less top (BLT) charging system of blast furnace as illustrated in the Figures clearly makes the proposed improved assembly advantageous over the existing designs as would also become clearer to the knowledgeable in the art with the particulars of the aforesaid unique configuration/assembly being described below in greater details. The present invention will be described in detail below with reference to embodiments as shown in the drawings.
In an embodiment, for capturing position feedback of lower material gate (LMG) in Bell less top (BLT) inclinometer 5 is implemented. Inclinometer produces output according to the inclination of object, on which it is mounted, which in the present invention is LMG 3. It detects change in

capacitance which varies according to inclination. It generates output of 4 to 20 mA, corresponding to 0 to 180 degree angle of rotation of any rotating object. In a preferred embodiment, the inclinometer 5 is found suitable for mounting and properly aligning on the plate attached to the circular disc 4 and capturing/ measuring the angle of rotation of the LMG 3.
In an embodiment of the present invention (Fig. 3 and Fig 4) with the improved assembly implementing the inclinometer 5 on the LMG 3, the stand-by encoder 2 is retained in the assembly. Further, the inclinometer 5 provides current proportional to the rotating circular disc 4. Inclinometer 5 is mounted on one extended angle of a circular disc. Inclinometer is mounted on an extended angle due to space constraint since it can’t fit dimensionally in the disc. Extended angle is a plate/extended strip attached to the circular disc on which the inclinometer is attached which serves as the sensing plate of the proximity switch to produce open and close feedback of the lower material Gate. The inclinometer is mounted on the extended angle since mounting it on the circular disc is difficult due to space constraint. Output signal of inclinometer 5 is connected to DCS (Distributed Control System, not shown in the figure) and the data is processed for achieving the desired flow-rate via LMG 3.
Further, in Fig. 5a-5b shows Performance of LMG 3 with inclinometer 5 attached to it vis-a vis when the encoders provided the position feedback. Figures clearly illustrate the improved trends in case the inclinometer 5 is used according to an embodiment of the invention. The trends are obtained by matching the signal patterns in the linear portion by eliminating the errors.
Further, since the output of the inclinometer 5 are slightly non-linear so linearization block used as per data given by supplier and mounted in a manner that it functions in linear zone. Linearization may be achieved using a block-by-block linearization model.

The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.

We claim:
1. An assembly for controlling flow-rate of hopper material discharge in a Bell-Less Top (BLT) charging system of a blast furnace comprising:
a lower material gate (LMG, 3) installed with at least one hopper;
a circular disc (4) arranged on surface of the LMG (3), and operatively connected to an encoder (2); and
a rotating plate attached to the circular disc (4) with an inclinometer (5) mounted on a face end of the rotating plate at an extended angle, and adapted for measuring position feedback of the LMG (3).
2. The assembly as claimed in claim 1, wherein the inclinometer (5) output is connected to the distributed control system (DCS) which is configured to control the flow-rate of the hopper discharge material through the LMG (3).
3. The assembly as claimed in claim 1, wherein the inclinometer (5) provides current in range of 4-20 mA when angle of inclination is between 0- 180°.
4. The assembly as claimed in claims 1 and 3, wherein the angle of inclination is proportional to angle of rotation of the circular disc (4).
5. The assembly as claimed in claim 1, wherein the encoder is a standby encoder (2).
6. The assembly as claimed in claim 1, wherein output of the inclinometer (5) is linearized using a block-by-block linearization model.