FORM 2THE PATENT ACT 1970(39 OF 1970)&The Patent Rules, 2003COMPLETE SPECIFICATION(See Section 10 and Rule 13)
1 TITLE OF THE INVENTION :
A level sensor system for measuring level of horizontally moving solids at high temperatures
2 APPLICANT (S)
Name : STEEL AUTHORITY OF INDIA LIMITED
Nationality : A Govt, of India Enterprise
Address : Bhilai Steel Plant, Bhilai, State of Chattisgarh, India
3 PREAMBLE TO THE DESCRIPTION
COMPLETE
The following specification particularly descibes the invention and the manner inbe performed. which it is to


FIELD OF THE INVENTION
The present invention relates to a high temperature moving solid level sensor system and ,in particular, to a unidirectional electro-kinematics level sensor system for critical use at high temperature moving solid level measuring application. The system would enable effective level measurement at high temperature locations for solid moving material without problems of damage to the measuring device due to such high temperature location. Moreover, the system is reliable, safe and more advantageously, is also cost effective. The system can thus be advantageously used in measuring the hot sinter level discharge on coolers and further facilitate increasing the sinter production by maximizing the sinter strength and reducing the sinter return.
BACKGROUND ART
Level measurement of solids especially in case of solid material, which is moving continuously at high temperature is extremely difficult since all conventional level measuring devices have the inherent problem of getting damaged when exposed to such high temperature and consequential erroneous results. Accordingly, although the measurement of solid level of such high temperature moving solid materials such as hot sinter discharged on cooler, which have a temperature of more than about 150°C is extremely difficult due to the problems of high temperature in and around the moving hot solid material. Therefore, there is no such device / instrument which can measure level of material in an environment where a target material is solid and moving continuously at a very high temperature and instrument is also continuously exposed to high temperature such as more than about 150°C.
Usually, the conventional varieties of level measurement devices can be categorized under I) non-contact type, such as, the ultrasonic level or radar type level measurement devices or II) contract type measuring units such as the Capacitance or Radio frequency type instruments, which are known to be used to measure solid levels in bunkers, hoppers etc. or the liquid level in water tanks/vessels. However, importantly, all such level measurement devices both the non-contract type and the contact type are suitable for level measurement of solid level or the liquid level where the measurement location is at atmospheric temperature which is same as the ambient temperature. However, in case such level measurement is required to be carried out in respect of high temperature moving solids or environments which are too hot and at high temperature, such conventional type of measuring instruments/systems can not be used since the devices when exposed to such high temperature get damaged and finally get burnt and stop
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working. Thus, it is extremely difficult and not at all possible to utilize the conventional known varieties of measuring instruments/systems for measuring the high temperature solid level in such high temperature zones /regions since either the device is rendered non-effective and the process of measurement becomes abnormal or the device gets totally damaged and completely stops functioning.
OBJECTS OF THE INVENTION
It is thus the basic object of the invention to provide a high temperature moving solid level sensor system which would enable carrying out safely and reliable the level measurement of such high temperature moving solids without problem of abnormal measurement and /or damage or burning out of the measuring device due to exposure to such high temperature environments of the moving solid.
Another object of the present invention is directed to a high temperature moving solid level measurement system, which would be adapted such that it can be effectively installed even at locations where the temperature can be very high and / or the human approach is not directly possible.
Yet further object of the present invention is directed to a high temperature moving solid level measurement system which would be safe and free of accidental hazards involved in measuring at high temperature locations and also which would be adapted for effective and advantageous selective installation in and around high temperature zone for measuring hot solids and importantly, would not encounter problems of abnormal measurement and / or instrument failure / burning due to such high temperature exposure of the measuring device.
A further object of the present invention is directed to avoid the problems or limitations of conventional non-contact type or contact type measurement devices which are not capable of measuring hot solid level by way of a unidirectional electro-kinematics level sensor system for critical use and high temperature moving solid level measuring applications.
Yet further object of the present invention is directed to level sensor system for critical use at high temperature moving solid level measuring applications, which would be adapted to measure material height with same accuracy and reliability as required of any level measuring type instrument.
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A further object of the present invention is directed to provide a unidirectional electro-kinematics level sensor system for critical use at high temperature moving solid level measuring wherein it would be possible to install the measuring device such as an angle to current converter horizontally far away from the hot zone and yet favour obtaining very effective and reliable level measurement.
A further object of the present invention is directed to a safe and reliable electro-kinematics level sensor system which can be readily and effectively used for measuring the hot sinter level cost effectively by way of increasing the sinter production by maximizing the sinter strength and reducing the sinter return.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided a high temperature moving solid level sensor system comprising:
a freely suspended high temperature resistant rod/pipe adapted such that at its lower end it is in contact with the hot solid material of which level is to be sensed and its top end secured with respect to a shaft which is mounted on a bearing arrangement such that the said shaft can be rotated freely on said bearing by said freely suspended rod/pipe depending on the hot material bed height;
an angle to current conversion device operatively linked at one end of said shaft and disposed such that the device does not come in direct contact with the said immediate hot region in and around the said hot solid;
said freely suspended rod/pipe adapted to move in a circular direction as the solid
material height changes with said operatively connected device adapted to measure the
angle (9) based on the deviation of the position of the rod/pipe along said circular path
and obtaining there from the moving solid bed height based on the trigonometric
equations y1 = H cos (0) and h= H(1-cos (0)) {H=y1+h} wherein
said H= length of freely suspended rod/pipe;
h= Solid Hot material bed height;
yl= Empty Distance and
0= Angle made by the freely suspended rod/pipe.
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In accordance with a preferred aspect of the present invention there is provided a high temperature moving solid level sensor system for measuring the hot sinter height in coolers comprising:
a freely suspended high temperature resistant rod/pipe adapted such that at its lower end it is in contact with the hot solid sinter material of which level is to be sensed and its top end secured with respect to a shaft which is mounted on a bearing arrangement such that the said shaft can be rotated freely on said bearing by said freely suspended rod/pipe depending on the sinter bed height;
an angle to current conversion device operatively linked at one end of said shaft and disposed such that the device does not come in direct contact with the said immediate hot region in and around the said hot sinter solid material;
said freely suspended rod/pipe adapted to move in a circular direction as the solid sinter
material height changes with said operatively connected device adapted to measure the
angle (9) based on the deviation of the position of the rod/pipe along said circular path
and obtaining there from the sinter bed height based on the trigonometric equations
y1=H cos (9) and h= H(1-cos (9)) {H= yx+h} wherein
said H= length of freely suspended rod/pipe;
h= Solid Hot material bed height;
y1= Empty Distance and
9= Angle made by the freely suspended rod/pipe.
In the above disclosed high temperature moving solid level sensor system the said freely suspended pipe comprises a freely suspended stainless steel rod/pipe.
The said current conversion device is installed at one end of the shaft with selective coupling means adapted for required flexibility and also for preventing the heat transfer to instrument through shaft. Preferably, the said coupling means comprise Teflon couplings.
Importantly, by way of the system of the present invention it is possible to locate the said device far away from direct contact of hot air coming out of the sinter cooler. In accordance with another preferred aspect the said device is kept inside a water -cooling jacket in the temperature range of 30-40°C.
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It is thus possible by way of the above system of the invention to achieve a unidirectional electro-kinematics level sensing.
In accordance with another aspect of the invention, the same provides for safe and effective method of unidirectional electro-kinematics level sensing for critical high temperature moving solid level measuring using the above said high temperature moving solid level sensor system of this invention.
It is thus possible by way of the above disclosed electro-kinematic level sensor system for critical use at high temperature measuring application. Importantly, the unidirectional electro-kinematic sensor is adapted to avoid the complexities and problems of measuring level of material in and environment where target material is solid and moving continuously at very high temperature and the instrument does not get damaged due to the exposure to high temperature such as more than 150°C.
Accordingly, the present sensor system of the invention would enable safe and reliable measurement of levels in environment such as where hot sinter is discharged on coolers at around 800°C and is then cooled by blowing atmospheric air from the bottom of the cooler and the cold sinter at around 80°C is then discharged from the cooler to the conveyor belt. Normally, in such cases, the outlet air before the discharge point is around 60-70°C but many times due to process abnormality the outlet temperature even reaches to a level of 200°C. It is thus possible by way of the present invention to carry out effectively and safely the hot material level sensing which was not possible using the conventional level measurement devices such as the non-contact type units, ultrasonic level /radar type or the contact type such as capacitance / radio frequency type instruments.
Thus, using the level measuring system of the invention the level of hot solid on horizontally moving conveyors etc. can be advantageously measured without any problem of damage burning out of the measuring system/ device.
Advantageously, the level measuring system of the invention on one hand ensures safety of the measuring unit as well as the human safety and on the other hand achieves the much required accuracy and reliability of a sensor system especially, for critical use at high temperature moving solid level measuring application.
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In the system of the invention the temperature resistant freely suspended rod/pipe can be preferably obtained of stainless steel pipe and fixed to the shaft which is mounted on bearing arrangement to enable the shaft to rotate freely on the bearing by the freely suspended pipe depending on the sinter bed height.
Importantly, the suspended pipe and its operative connection to the shaft supported on bearings enable disposition of the angle to current conversion device located far away from direct contact of the hot air coming out of the sinter cooler. Preferably, selective coupling means is used to operatively connect the shaft to the device which would provide to require the flexibility as well as prevent any heat transfer to the device through shaft. Thus advantageously, the current conversion device can be so installed at one end of the shaft with the help of Teflon coupling.
The current generated from the instrument (angle to current converter) is linear with respect to angle formed by the rod but the sinter bed height is not linear with respect to current generated by the instrument. The freely suspended pipe is adapted to move in a circular path as the material height changes and the instrument installed on the shaft measures angle (0) and correspondingly the sinter bed height can be calculated in a the computer means by applying simple trigonometric equation (h = H(l-cos(9)).
It is thus possible using the above disclosed level measurement sensor system to carry out effectively and safely the level measurement of hot solid without complexities of damaged to the instruments and / or installing of the device. Moreover, the system apart from being safe and reliable is also cost effective by way of favouring productivity in processes involving hot solid moving material and height determination.
The details of the invention, its object and advantages are explained hereunder in greater detail in relation to non-limiting exemplary illustration of the unidirectional electro-kinematic level sensor system in accordance with the present invention as per the following accompanying figure:
Figure 1 : is an illustration of the mounting arrangement for the electro-kinematic type level measuring instrument of the level measuring system in accordance with the system of the invention.
Figure 2: is an illustration revealing the circular path motion of the suspended rod/pipe on the hot solid due to the height change in the hot solid used in the sensor system of
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the invention and its application in the trigonometric equation for determining the height of the hot moving solid.
Reference is first invited to accompanying figure 1 which clearly illustrate the sensor system and its mounting an arrangement and the components involved. As represented in the said figure the system of the invention basically involves the freely suspended rod/pipe (SR) which is preferably a stainless steel rod which is suspended from the shaft (SH) which in turn is mounted on bearing arrangement (BR) as also shown in the figure. The rod (SR) is supported with respect to the shaft (SH) through the mounting frame (MF) and accompanying mounting bolt (MB). At its lower end, the suspended rod is adapted to be in contact with the surface of the hot solid material (SM).
In order to measure the change in path of the suspended rod (SR) due to the change in the solid material level, the shaft is operatively connected at one end to the angle to current converter instrument (IN) through couplings (CO) preferably, Teflon couplings. The Teflon coupling is used for the flexibility as well as for stopping the heat transfer to instrument through shaft since the Teflon is bad conductor of heat.
Moreover to protect the instrument further from any damage due to heat in the adjoining hot location, a water cooling jacket (CJ) is provided and the instrument is preferably kept inside the water cooling jacket in the temperature of about 30-40°C.
The current generator from the instrument (angle to current converter) is linear with respect to angle formed by the rod, but the sinter bed height is not linear with respect to the current generated by the instrument. As clearly illustrated in Figure 2, the freely suspended pipe is adapted to move in a circular path as the material height changes and the instrument installed on the shaft measures angle (6) as also shown in said figure 2. The corresponding sinter bed height can be obtained by applying the simple trigonometric equation and preferably calculated using computer means.
In order to confirm the reliability and accuracy of the level measurement of hot moving solid involving the sensor system of the invention, test measurements was carried out involving the above present system and compared with actual sinter bed height measured physically with measuring tape. The results obtained are shown in Table 1 hereunder.
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Table - 1

mA(I/P) Angle Cos(Thita) yi(mm) h(mm) Calculated I/P (X)% O/P (h)% MA (O/P) H (mm) Actual H (%) Error (%)
Calculate Actual
4 0 1 4000 0 0 0 4 0 0 0
5.6 5.34 0.9956 3982.4 17.6 10 0.88 4.1408 17 0.85 -0.03
7.2 10.68 0.9827 3930.8 69.2 20 3.46 4.5536 70 3.5 0.04
8.8 16.02 0.9612 3844.8 155.2 30 7.76 5.2416 156 7.8 0.04
10.4 21.36 0.9313 3725.2 274.8 40 13.74 6.1984 275 13.75 0.01
12 26.7 0.8934 3573.6 426.4 50 21.32 7.4112 426 21.3 -0.02
13.6 32.04 0.8477 3390.8 609.2 60 30.46 8.8736 609 30.45 -0.01
15.2 37.38 0.7946 3178.4 821.6 70 41.08 10.5728 821 41.05 -0.03
16 40.04 0.7655 3062 938 75 46.9 11.504 938 46.9 0
16.8 42.72 0.7347 2938.8 1061.2 80 53.06 12.4896 1061 53.05 -0.01
18 46.725 0.6855 2742 1258 87.5 62.9 14.064 1258 62.9 0
19.2 50.73 0.633 2532 1468 95 73.4 15.744 1468 73.4 0
20 53.4 0.5962 2384.8 1615.2 100 80.76 16.9216 1615 80.75 -0.01
21.975 59.99 0.5 2000 2000 112 100 20
Y1 = 4000*Cos (Thita) h = (4000 - y0 1 mA 3.3375 deg Range = 0-2000mm
As would be apparent from the above Table 1 the measurements confirmed that the sensor system for measuring high temperature moving solid level is accurate and reliable and importantly also safe both for the operator and also for the protection of the measuring device from damage due to high temperature.
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We Claim:
1. A high temperature moving solid level sensor system comprising:
a freely suspended high temperature resistant rod/pipe adapted such that at its lower end it is in contact with the hot solid material of which level is to be sensed and its top end secured with respect to a shaft which is mounted on a bearing arrangement such that the said shaft can be rotated freely on said bearing by said freely suspended rod/pipe depending on the hot material bed height;
an angle to current conversion device operatively linked at one end of said shaft and disposed such that the device does not come in direct contact with the said immediate hot region in and around the said hot solid;
said freely suspended rod/pipe adapted to move in a circular direction as the solid
material height changes with said operatively connected device adapted to
measure the angle (6) based on the deviation of the position of the rod/pipe
along said circular path and obtaining there from the moving solid bed height
based on the trigonometric equations y1 = H cos (6) and h= H(l-cos (6)) {H= y1
+h} wherein
said H= length of freely suspended rod/pipe;
h= Solid Hot material bed height;
y1= Empty Distance and
0= Angle made by the freely suspended rod/pipe.
2. A high temperature moving solid level sensor system for measuring the hot sinter
height in coolers comprising:
a freely suspended high temperature resistant rod/pipe adapted such that at its lower end it is in contact with the hot solid sinter material of which level is to be sensed and its top end secured with respect to a shaft which is mounted on a bearing arrangement such that the said shaft can be rotated freely on said bearing by said freely suspended rod/pipe depending on the sinter bed height;
an angle to current conversion device operatively linked at one end of said shaft and disposed such that the device does not come in direct contact with the said immediate hot region in and around the said hot sinter solid material;
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said freely suspended rod/pipe adapted to move in a circular direction as the solid
sinter material height changes with said operatively connected device adapted to
measure the angle (8) based on the deviation of the position of the rod/pipe
along said circular path and obtaining there from the sinter bed height based on
the trigonometric equations y1 = H cos (8) and h= H(1-cos (8)) {H= yx +h}
wherein
said H= length of freely suspended rod/pipe;
h= Solid Hot material bed height;
yl= Empty Distance and
8= Angle made by the freely suspended rod/pipe.
3. A high temperature moving solid level sensor system as claimed in anyone of claims 1 or 2 wherein said freely suspended pipe comprises a freely suspended stainless steel rod/pipe.
4. A high temperature moving solid level sensor system as claimed in anyone of claims 1 to 3 wherein the said current conversion device is installed at one end of the shaft with selective coupling means adapted for required flexibility and also for preventing the heat transfer to instrument through shaft.
5. A high temperature moving solid level sensor system as claimed in anyone of claims 1 to 4 wherein the said coupling means comprise Teflon couplings.
6. A high temperature moving solid level sensor system as claimed in anyone of claims 1 to 5 wherein the said device, which is an angle to current conversion device, is located far away from direct contact of hot air coming out of the sinter cooler.
7. A high temperature moving solid level sensor system as claimed in anyone of claims 1 to 6 wherein the said device is kept inside a water -cooling jacket in the temperature range of 30-40°C.
8. A high temperature moving solid level sensor system as claimed in anyone of claims 1 to 7 comprising a unidirectional electro-kinematics level sensing.
9. A high temperature moving solid level sensor system as claimed in anyone of claims 1 to 8 wherein the means to carry out the said height measurement using the said trigonometric equation comprises operative computer means.
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10. A method of unidirectional electro-kinematics level sensing for critical high temperature moving solid level measuring in particular hot sinter bed height measurements comprising the steps of using the said high temperature moving solid level sensor system as claimed in anyone of claims 1 to 9.
11. A high temperature moving solid level sensor system and its method of measurement substantially as herein described and illustrated with reference to the accompanying figures.
Date: this 24th day of May, 2006
Anjan Sen
Anjan Sen & Associates
Applicant's Agent
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ABSTRACT
A level sensor system for measuring level of horizontally moving solids at
high temperatures
A high temperature moving solid level sensor system and ,in particular, to a unidirectional electro-kinematics level sensor system for critical use at high temperature moving solid level measuring application. The system would enable effective level measurement at high temperature locations for solid moving material without problems of damage to the measuring device due to such high temperature location. Moreover, the system is reliable, safe and more advantageously, is also cost effective. The system can thus be advantageously used in measuring the hot sinter level discharge on coolers and further facilitate increasing the sinter production by maximizing the sinter strength and reducing the sinter return.
(Figurel)