FORM 2
THE PATENT ACT 1970
(39 OF 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
1 TITLE OF THE INVENTION :
A THERMOCOUPLE ASSEMBLY FOR MEASUREMENT OF RAW GAS TEMPERATURE IN VERTICAL STRAND OF COKE OVEN.
2 APPLICANT (S)
Name : STEEL AUTHORITY OF INDIA LIMITED.
Nationality : A Govt, of India Enterprise;
Address: Bhilai Steel Plant, Bhilai-490001, State of Chattisgarh,India.
3 PREAMBLE TO THE DESCRIPTION
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to a system of Ascension pipe thermocouple assembly to measure raw gas temperature in Coke oven battery. More particularly, the present invention relates to a thermocouple assembly for measurement of temperature of coke oven gas coming out of battery in vertical strand (goose neck) in a reliable manner wherein thermocouple is attached to the housing assembly with an intermediate coupling device such that thermocouple can be inserted into assembly as per requirement and then tightened it, so that immersion length becomes fixed. Thermocouple according to the present invention is terminated in junction box located at least 5 meter away from hot zone enabling checking healthiness of thermocouple in a very simple, safe manner and can be done any time. In case of non working and damage of thermocouple it can be checked safely at distance 5-6 meter away from original location which is too hot. Removal and installation of thermocouple is safe as it can be done just by loosening and tightening the male connector from intermediate coupling, keeping one selves a meter away from thermocouple end.
BACKGROUND OF THE INVENTION
It is well known in the coke making process in coke oven that temperature of raw gas is an essential parameter to measure and monitor for desired coke quality. The progress of carbonization inside an oven can be monitored by observing the temperature profile of the evolving raw gases in the ascension pipe (AP) also called vertical strand or goose neck. The coking index is estimated by measuring the raw gas temperature at the base of the AP. It is observed that the temperature of the raw gas rises with the progress of carbonization to reach a maximum Tmax and then drops abruptly. The temperature of the raw gas has been measured by placing thermocouple in the AP.
Coke oven is important raw materials production unit in such trades as metallurgy industry and chemical industry and so on. It produces coke and coke oven gas mainly, and the quality and output of the coke oven units are concern for the stability of follow-up unit. The instrumentation system of coke oven batteries has

been under continuous development from the very beginning of coke production in batteries. The traditional heating control system is simple in operation but does not consider the real time changes in process variables for each oven. Further, there is no way to determine the progress of carbonization inside the ovens and no indication regarding the condition of the refractory, brickwork.
Coking index affect coke quality parameter (M10) which is given by:
Coking index (CI) = carbonization period(X)/coking period(y);
Optimum coking index should be within range (1.4-1.45). Feedback of coking index
help to optimize heat consumption during coal to coke conversion in coke oven
batteries. Heating flow gas can be corrected using this feedback of coking index (CI).
In the conventional system for raw gas temperature measurement in coke oven, installation, removal and checking of the thermocouples were the major practical problems. Existing thermocouple used to measure vertical strand temperature, was head mounted type, conventional cable termination on thermocouple head. Any malfunctioning of thermocouple could not be checked due to very high temperature near thermocouple head. Due to excessive heat in the surrounding area where thermocouple is installed, man cannot work for more than few seconds. Due to this problem, as long as newly installed thermocouples work without any problem, the system uses to guide operator about the coke making process. But if any problem comes, it was totally impossible for instrumentation person to go and rectify the problem at site resulting in unsafe working condition and failing to provide full benefit of the temperature measurement system.
There has been therefore a persistent need in the related art to providing a system of Ascension pipe thermocouple to measure raw gas temperature in Coke oven battery adapted to measure the raw gas temperature during coking process in a reliable manner to ensure desired coke quality by eliminating the above problem of prior art systems by designing and developing an improved thermocouple assembly so that thermocouple checking point can be shifted substantially away from the hot zone, where condition of thermocouples can be checked any time. Also installation of thermocouple as well as repair and replacement in case of damage would also be done very easily and quickly, away from vertical strand, without actually replacing the total thermocouple assembly.

OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to providing a thermocouple assembly for measurement of temperature in high atmospheric temperature in vertical strand of coke oven and a method of reliable temperature measurement of raw gas temperature, adapted to overcome the disadvantages/drawbacks of the conventional apparatus in respect of installation and maintenance/replacement of associated instruments.
Another object of the present invention is to provide a thermocouple assembly for measurement of raw gas temperature in vertical strand of coke oven battery having high atmospheric temperature with convenience of checking of thermocouple, ensuring reduced chances of human injury.
Yet another object of the present invention is directed to provide a thermocouple assembly for measurement of raw gas temperature in vertical strand in high atmospheric temperature, which would be simple and safe to install and would at the same time be effective and reliable in ascertaining the gas temperature measurement.
A further object of the present invention is directed to a thermocouple assembly for measurement of raw gas temperature in vertical strand in high atmospheric temperature, which is a simple and cost effective system for temperature measurement and can be easily obtained cost effectively and readily installed without involving technical complexities and avoiding safety hazards during installation or use.
A further objective of the present invention is directed to a thermocouple assembly for measurement of raw gas temperature in vertical strand in high atmospheric temperature wherein gas leakage even in case of damage of top metallic layer of ascension pipe is eliminated, involving 99.7% high alumina porcelain tube put inside the metallic tube that remain unaffected by high process temperature, thus minimizing malfunctioning of temperature measurement.

A still further object of the present invention is directed to provide a reliable but accurate thermocouple assembly for measurement of raw gas temperature in vertical strand in high atmospheric temperature condition involving an improved intermediated interconnecting device which not only take care of safety of human being but at the same time ensures its reliability in measurement.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is thus directed to a thermocouple assembly for measurement of raw gas temperature in vertical strand of coke oven comprising:
a thermocouple protection housing having an open top ;
a thermocouple means adapted to measure raw gas temperature of coke oven of sufficient length adapted to at one end atleast partly insert into said thermocouple protection housing at its open top with its other end extending to suitable locations for measuring the temperature sensed by said thermocouple in said housing;
an intermediate coupling device adapted for releasable connection with the said thermocouple protection housing and maintain said thermocouple end extending into said thermocouple protection housing for on spot temperature sensing at site and its measurement at the other end free of said thermocouple means located far from said site of sensing of the temperature.
A further aspect of the present invention is directed to said thermocouple assembly wherein said intermediate coupling device at one end is adapted such that it provides a releasable connection to said thermocouple protection housing and at its other end provide means for effective releasable locking of said thermocouple in position being inserted at its one end into said thermocouple protection housing and at its other free end adapted to extend to suitable locations for measuring the temperature sensed by said thermocouple in said housing.
A still further aspect of the present invention is directed to said thermocouple assembly wherein said thermocouple protection housing is tubular in shape and

comprise a male externally threaded thermocouple protection tube which provides for releasable connection with a corresponding internally threaded female connecting portion at one end of said intermediate coupling device while at its other end the said intermediate coupling device is adapted such that the thermocouple means passes through it and gets locked with ferrule means when tightened to provide for a rigid positioning of the end of the thermocouple means inside the thermocouple protection tube on one end and enable the free extended end of the thermocouple to be extended to remote locations for measurement purposes without disturbing its sensing end disposition in said thermocouple protection housing.
A still further aspect of the present invention is directed to said thermocouple assembly wherein the free end of the thermocouple is terminated in junction box located far away from the site of sensing of the temperature.
Yet another aspect of the present invention is directed to said thermocouple assembly wherein the thermocouple protection housing is further covered atleast partially by damage /leak resistant cover preferably porcelain tube.
A further aspect of the present invention is directed to said thermocouple assembly wherein said thermocouple means comprises of 3.2 mm to 5.0 mm diameter preferably about 3.2 mm diameter and length 5.0 meter to 8.5 meter preferably about 6.4 meter mineral insulated thermocouple adapted to withstand temperatures of up to about 1000°C
The objects and advantages of the present invention is described in greater details with reference to the following accompanying non-limiting illustrative drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: is the screen shot of graphical presentation of plot of raw gas temperature measured at goose neck by placing thermocouple in the ascension pipe (AP) during carbonization of coal in coke oven.

Figure 2(a): shows the schematic view of the improved thermocouple based raw gas temperature measurement system along with thermocouple according to the present invention involving a detachable intermediate connector.
Figure 2(b): shows the photographic image of the complete thermocouple based raw gas temperature measurement system according to the present invention along with thermocouple.
Figure 3(a) & (b): show an sub-assembly/component of thermocouple based temperature measurement system used in coke oven [used in the embodiment of Figure 2(a) & 2(b)] wherein (a) is the porcelain housing for installing the thermocouple, (b) thermo couple assembly without head used in the system according to the present invention.
Figure 4(a): is the schematic view of the interconnecting device used in the thermocouple based temperature measurement system according to the present invention.
Figure 4(b): is the photographic image of the interconnecting device fixed with thermocouple housing assembly of figure 3(b).
Figure 5: show a 3.2 mm diameter and 6.4 meter long thermocouple used to measure burden temperature in coke oven by inserting into the probe assembly.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
The present invention is directed to providing a thermocouple assembly for measurement of raw gas temperature in high atmospheric temperature zone in vertical strand of coke oven involving installing thermocouple in ascension pipe with the help of an intermediate connection device favoring reliable temperature measurement of raw gas temperature to ensure desired coke quality and easy and faster installation/maintenance of thermocouple element as and when needed.

The progress of carbonization inside coke oven can be monitored by observing the temperature profile of the evolving raw gases in the ascension pipe (AP) also called vertical strand or goose neck. The coking index is estimated by measuring the raw gas temperature at the base of the AP.
Accompanying Figure 1 screen shot of graphical presentation of plot of raw gas temperature measured at goose neck by placing thermocouple in the ascension pipe (AP) during carbonization of coal in coke oven.
It is observed that the temperature of the raw gas rises with the progress of carbonization to reach a maximum Tmax and then drops abruptly. The temperature of the raw gas is measured over time by placing thermocouple in the AP and based thereon coking index is computed as:
Coking index(CI) = carbonization period(X)/coking period(y),
This Coking index affect coke quality parameter (M10). Optimum coking index should be maintained within the range of 1.4-1.45. Feedback of coking index help to optimize heat consumption during coal to coke conversion in coke oven batteries. Heating flow gas can be corrected using this feedback (CI).
Existing thermocouples used to measure vertical strand temperature/ was head mounted type, conventional cable termination on thermocouple head. Any malfunctioning of thermocouple couid not be checked due to very high temperature near thermocouple head.
Measurement of vertical strand raw gas temperature is very important if low cost coke production is desired, because with the help of raw gas temperature variation coke making timing can be known. Based on true temperature of other vertical strand coke making timing for all other ovens can be predicted, hence utilization of optimum energy for converting coal into coke can be achieved.
There has been thus a need to developing a reliable system for continuous monitoring and measurement of the raw gas temperature in coke oven to ensure desired coke quality by estimating related coking index for efficient operation of coke oven.

The present invention take care of the requirements of the existing coke making process by designing and developing an improved system for raw gas temperature measurement in coke oven in a reliable manner involving a thermocouple assembly so that thermocouple checking point can be shifted up six (6) meter away from the hot zone, where thermocouple healthiness can be checked any time. Also in case of damage of thermocouple, replacement can also be done very easily in less than 30 sec, one meter away from vertical strand, without actually replacing the total thermocouple assembly.
Accompanying Figure 2(a) shows the schematic view of the improved thermocouple based raw gas temperature measurement system along with thermocouple according to the present invention involving a detachable intermediate connector device.
Accompanying Figure 2(b) shows the photographic image of the complete thermocouple based raw gas temperature measurement system according to the present invention along with thermocouple.
An innovative solution is provided by designing a new thermocouple (T/C) based temperature measurement system as illustrated in Figure 2(a) and (b) consists of three parts described as below:
Part I: A thermocouple assembly with outer metallic housing and an inner porcelain tube for installing thermocouple without the head.
Part II: A 3.2 mm diameter and 6.4 meter long thermocouple normally used to measure burden temperature in blastfurnace inserting into the probe assembly.
Part III: An intermediate coupling device fabricated in-house such that part-2 can be inserted into part-1 as per requirement and then tightened it, so that immersion length becomes fixed. In case of thermocouple getting damaged its replacement become very simple just by removing male connector along with thermocouple from intermediate device.

Accompanying Figure 3(a) & (b) show an assembly of thermocouple based temperature measurement system used in coke oven [used in the embodiment of Figure 2(a) & 2(b)] wherein (a) is the porcelain housing for installing the thermocouple, (b) thermo couple assembly without head used in the system according to the present invention.
Accompanying Figure 4(a) shows the schematic view of the interconnecting device involving male and female connector with a socket used in the thermocouple based temperature measurement system according to the present invention and Figure 4(b) shows the photographic image of the interconnecting device fixed with thermocouple assembly of figure 3(b).
Accompanying Figure 5 shows a 3.2 mm diameter and 6.4 meter long thermocouple used to measure raw gas temperature in coke oven by inserting into the probe assembly according to the present invention as described above.
The raw gas temperature measurement system according to the present invention to monitor and measure raw gas temperature in vertical strand coke oven to achieve desired coke quality involves an intermediate device developed in such a way that its one end is connected to male threaded thermocouple protection tube and other end is designed in such a way that a 3.2 mm mineral insulated thermocouple passes through it and gets locked with the'help of a ferrule when it is tightened.
A 3.2 mm diameter and 6.4 meter long mineral insulated thermocouple is used in the system to withstand temperature even up to 1000 °C. So there is no possibility of malfunctioning of measurement due to cable burning as it was happing earlier with conventional type thermocouple.
Thermocouple is terminated in a junction box located at least 5 meter away from hot zone compared to conventional thermocouple assembly, wherein termination was done on thermocouple head located in the hot zone. Hence, healthiness checking of thermocouple is now very simple, safe and can be done any time. Replacement of thermocouple in case of damage/non working is also very simple and fast, removal and installation can be performed in less than 30 sec for each case as compared to earlier one where removal and checking was not at all possible at site when battery is in operation. Removal and installation of thermocouple is safe as it can be done

just by loosening and tightening the male connector from intermediate coupling, keeping one selves a meter away from thermocouple end. A 6 mm thick porcelain tube takes care of leakage in case of outer protection sheet of thermocouple element gets damage due to excess heat.
It is thus possible by way of the present invention to providing a thermocouple assembly for measurement of raw gas temperature in vertical strand of coke oven battery which would ensure precise and reliable on line temperature measurement for achieving desired coke quality by monitoring and optimizing the time of carbonization and attaining maximum temperature. The system allow measurement and monitoring of temperature during carbonization safely away from high temperature zone and also favour faster and safe installation, maintenance/replacement of damaged/non working thermocouple as and when needed.

We Claim:
1- A thermocouple assembly for measurement of raw gas temperature in vertical strand of coke oven comprising:
a thermocouple protection housing having an open top ;
a thermocouple means adapted to measure raw gas temperature of coke oven of sufficient length adapted to at one end atleast partly insert into said thermocouple protection housing at its open top with its other end extending to suitable locations for measuring the temperature sensed by said thermocouple in said housing;
an intermediate coupling device adapted for releasable connection with the said thermocouple protection housing and maintain said thermocouple end extending into said thermocouple protection housing for on spot temperature sensing at site and its measurement at the other end free of said thermocouple means located far from said site of sensing of the temperature.
2. A thermocouple assembly as claimed in claim 1 wherein said intermediate coupling device at one end is adapted such that it provides a releasable connection to said thermocouple protection housing and at its other end provide means for effective releasable locking of said thermocouple in position being inserted at its one end into said thermocouple protection housing and at its other free end adapted to extend to suitable locations for measuring the temperature sensed by said thermocouple in said housing.
3. A thermocouple assembly as claimed in anyone of claims 1 or 2 wherein said thermocouple protection housing is tubular in shape and comprise a male externally threaded thermocouple protection tube which provides for releasable connection with a corresponding internally threaded female connecting portion at one end of said intermediate coupling device while at its other end the said intermediate coupling device is adapted such that the thermocouple means passes through it and gets locked with ferrule means when tightened to provide for a rigid positioning of the end of the thermocouple means inside the thermocouple protection tube on one end and enable the free extended end of the thermocouple to be extended to remote

locations for measurement purposes without disturbing its sensing end disposition in said thermocouple protection housing.
4. A thermocouple assembly as claimed in anyone of claims 1 to 3 wherein the free end of the thermocouple is terminated in junction box located far away from the site of sensing of the temperature.
5. A thermocouple assembly as claimed in anyone of claims 1 to 4 wherein the thermocouple protection housing is further covered atleast partially by damage /leak resistant cover preferably porcelain tube.
6. A thermocouple assembly as claimed in anyone of claims 1 to 5 wherein said thermocouple means comprises of 3.2 mm to 5.0 mm diameter preferably about 3.2 mm diameter and length 5.0 meter to 8.5 meter, preferably about 6.4 meter mineral insulated thermocouple adapted to withstand temperatures of up to about 1000°C.