Claims:We Claim:
1. A system for Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner from ground level comprising

a pilot burner located at top of the blast furnace gas bleeder stack;

a GI strip with top end located within a bracket housing an arcing arrangement near burner tip and said strip extending vertically downward with its lower end reaching upto the bottom of said bleeder stack;

an earth pipe adapted to carry mixed gas supply therethrough, with its top end located near the top end of said GI strip with selected gap defining a sparking spot and extending vertically downward with its lower end reaching upto the bottom of said bleeder stack;

a welding machine located in a chamber at ground level operatively connected to the bottom end of said GI strip and said earthing pipe for required power supply to strike an arc;

a sling attached to the top end of said GI strip and extending vertically downward with its lower end reaching upto the bottom of said bleeder stack such that on pulling the sling at bottom by an operator makes contact of the top ends of said GI strip and earth pipe thus creating an arc at the sparking spot near the burner tip for initial lighting up of the pilot burner whenever the flame is extinguished.

2. The system as claimed in claim 1 wherein said GI Strip is of 50mmX4mm section used as the conductor carrying phase of welding machine up to the arc striking point.

3. The system as claimed in claim 1 wherein said GI Strip is mounted with Porcelain insulators to insulate the GI strip from bleeder stack body in order to avoid short circuits between phase and earth conductors of welding machine.

4. The system as claimed in claim 1 wherein said earth pipe is SS pipe of NB50mm used for carrying the mixed gas and also as conductor carrying earth of welding machine up to the arc striking point.

5. The system as claimed in claim 1 wherein said mixed gas supply is connected to earth pipe for initial light up of pilot burner of bleeder stack.

6. The system as claimed in claim 1 wherein said mixed gas supply line is connected to a mixed gas drain pot at bottom of bleeder stack to knock out the moisture and condensate from the gas to avoid the extinction of pilot burner flame.

7. The system as claimed in claim 1 wherein said welding machine is connected with two number of welding cables to GI strip(Phase) & SS earth pipe line carrying Mixed Gas (Earth).

8. The system as claimed in claim 1 wherein said welding machine is connected to main electrical supply line involving MCB located in the secondary side of welding machine(Transformer) and in primary side 1 phase Isolator is provided.

9. A method of Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner from ground level using the system as claimed in claims 1 to 8 comprising

connecting phase electrode of welding machine to the insulated GI strip and neutral electrode to the SS pipe carrying mixed gas and switching on the welding machine;

opening the mixed gas line valve to supply fuel to pilot burner; and

pulling the sling attached to the sparking arrangement at the top of bleeder stack from ground level and thus generating spark to light up the pilot burner at top of stack.

10. The method as claimed in claim 9 comprising pulling the sling from the ground level, so that both the GI strip and the SS pipe get in touch with each other at the top of the bleeder stack, thus completing the electrical circuit through welding machine and on releasing the sling thereafter, the contact point get separated on load (Electrical circuit) and arc takes place in between the two strips which results in ignition of pilot gas i.e. Mixed gas to light up the burner.

Dated this the 29th day of March, 2018
Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)
IN/PA-199
, Description:FIELD OF THE INVENTION

The present invention relates to a system for Safe Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner with reduced time. More particularly, the present invention provides an automated system for lighting up of extinguished bleeder stack pilot burner through spark generation involving a welding machine operated from the ground level without involving any manual intervention climbing the ladder to top of stack and specially during night time with low visibility, in a fast, safe and reliable manner.

BACKGROUND OF THE INVENTION

The entire gas grid of applicant’s Rourkela Steel Plant is maintained by Energy Management Department. BF gas is generated from Furnace top (also known as Top gas). This is called Raw gas containing impurities mainly dust particles. This Raw gas is filtered at Gas Cleaning Plant. The final gas evolved at the end of GCP is called Clean gas. This Clean gas is distributed through BF gas grid.

In normal condition, the total gas generated is fully utilized. The safety range of grid BF gas pressure is 250 MMWG to 400 MMWG.

If the grid pressure falls below 250 MMWG (millimetre water gauge), there is a chance of Burners of Furnaces getting extinguished as the lower limit of Burner tip pressure is 250 MMWG.

If grid pressure rises beyond 400 MMWG, it may cause gas leaking at weak areas leading to gas poisoning. The grid is designed to handle up to 500 MMWG pressure and the safe operating limit of grid pressure is 400 MMWG.

When consumption of BF gas is less than generation due to break down/sudden failure of one or more gas consuming units, the grid pressure rises suddenly.

To keep the grid pressure within its normal range, a BF gas holder provided to act as a buffer vessel. The capacity of BF gas holder is 150,000 m3. The safe operating limit of this holder is 60,000m3 to 120,000m3. The holder operates by raising and lowering of a piston by gas pressure. Below and beyond this safe operating limit of the holder, there is a chance of the moving piston getting stuck up. When grid pressure is low, gas from gas holder flows to the grid to maintain the pressure. When grid pressure is high, gas to the gas holder flows from grid to maintain the pressure.

Here, following three situations may arise:

A. If BF gas holder level is at 60,000 m3 and still grid pressure is low, more gas from gas holder cannot be supplied to grid. In this case BF gas holder is isolated manually by closing gas holder main valve.

B. If BF gas holder level is at 120,000 m3 and still grid pressure is high, more gas to gas holder cannot be supplied. In this case, grid pressure rises beyond 400mmwg creating unsafe condition for the gas grid. In this situation, BF gas needs to bleed out to the atmosphere. To bleed out the gas to atmosphere, there is a risk as BF gas is heavier than air, highly poisonous contains Carbon Monoxide.

C. Direct bleeding of the gas to the atmosphere will settle down the gas, as it is heavier than air and will harm the life and health of the people in the vicinity.

The Raw gas from BF is filtered in filter at gas cleaning plant(GCP) and the Clean gas is distributed through BF Grid. The safety range of grid BF gas pressure is 250 to 400 MMWG.

A bleeder stack with a pilot burner at the top burns the bled BF gas24x7, before releasing to the atmosphere. This gas contains highly poisonous carbon Monoxide which needs to be burnt before releasing to the atmospheres. It is very essential to burn the bled BF gas containing carbon monoxide before releasing it to the atmosphere. To perform this job safely, there is a bleeder stack through which the bled gas is burnt. The bleeder stack is 35meters height. A pilot burner is at the top of the stack which burns throughout the year and 24x7. If the pilot burner extinguishes due to any reason, if needs to be lighted up immediately for safety and the process involves manual light up in a very unsafe condition.

If the pilot Burner extinguishes for any reason this needs to be immediately lighted up manually for safety reason which was a very difficult and unsafe due to its height of 35 meter needing climbing up the ladder. This manual lighting up becomes all the more unsafe during night time due to low visibility.

Hence, this invention has been developed to eliminate the unsafe practice of manual light up and introduce automated lighting up through spark generation from the ground level without involving climbing the ladder and specially during night time with low visibility.

OBJECTS OF THE INVENTION
The basic object of the present invention is directed to provide a system for Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner from ground level in a fast, safe and reliable manner in case the flame is extinguished in regular operation and a method of such lighting up of the pilot burner.

A further object of the present invention is directed to provide a system for Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner involving an electrical system of spark generation at the top of the bleeder stack so as to safely light up the Pilot Burner from the ground level by any person with reduced time lag.

A still further object of the present invention is directed to provide a system for Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner from ground level which is actuated by arc striking in presence of a mixed fuel gas at the burner tip involving an arc welding transformer located in a chamber at the ground level.

A still further object of the present invention is directed to provide a system for Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner from ground level which can quickly light up the pilot burner whenever extinguished without allowing harmful BF gas to be released to atmosphere without burning.

A still further object of the present invention is directed to provide a system for Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner from ground level which is operator friendly not needing the operator to climbing up on ladder to top of bleeder stack for lighting the pilot burner.

A still further object of the present invention is directed to provide a system for Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner from ground level which can be safely operated even visibility is poor particularly during night time.

SUMMARY OF THE INVENTION

The basic aspect of the present invention is directed to provide a system for Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner from ground level comprising

a pilot burner located at top of the blast furnace gas bleeder stack;

a GI strip with top end located within a bracket housing an arcing arrangement near burner tip and said strip extending vertically downward with its lower end reaching upto the bottom of said bleeder stack;

an earth pipe adapted to carry mixed gas supply therethrough, with its top end located near the top end of said GI strip with selected gap defining a sparking spot and extending vertically downward with its lower end reaching upto the bottom of said bleeder stack;

a welding machine located in a chamber at ground level operatively connected to the bottom end of said GI strip and said earthing pipe for required power supply to strike an arc;

a sling attached to the top end of said GI strip and extending vertically downward with its lower end reaching upto the bottom of said bleeder stack such that on pulling the sling at bottom by an operator makes contact of the top ends of said GI strip and earth pipe thus creating an arc at the sparking spot near the burner tip for initial lighting up of the pilot burner whenever the flame is extinguished.
A further aspect of the present invention is directed to said system wherein said GI Strip is of 50mmX4mm section used as the conductor carrying phase of welding machine up to the arc striking point.
A still further aspect of the present invention is directed to said system wherein said GI Strip is mounted with Porcelain insulators to insulate the GI strip from bleeder stack body in order to avoid short circuits between phase and earth conductors of welding machine.
A still further aspect of the present invention is directed to said system wherein said earth pipe is SS pipe of size NB50mm used for carrying the mixed gas and also as conductor carrying earth of welding machine up to the arc striking point.
Another aspect of the present invention is directed to said system wherein said mixed gas supply is connected to earth pipe for initial light up of pilot burner of bleeder stack.
Yet another aspect of the present invention is directed to said system wherein said mixed gas supply line is connected to a mixed gas drain pot at bottom of bleeder stack to knock out the moisture and condensate from the gas to avoid the extinction of pilot burner flame.
A further aspect of the present invention is directed to said system wherein said welding machine is connected with two number of welding cables to GI strip(Phase) & SS earth pipe line carrying Mixed Gas (Earth).
A still further aspect of the present invention is directed to said system wherein said welding machine is connected to main electrical supply line involving MCB located in the secondary side of welding machine(Transformer) and in primary side 1phase Isolator is provided.
A further aspect of the present invention is directed to a method of Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner from ground level using the system as described above comprising

connecting phase electrode of welding machine to the insulated GI strip and neutral electrode to the SS pipe carrying mixed gas and switching on the welding machine;

opening the mixed gas line valve to supply fuel to pilot burner; and

pulling the sling attached to the sparking arrangement at the top of bleeder stack from ground level and thus generating spark to light up the pilot burner at top of stack.

A still further aspect of the present invention is directed to said method comprising pulling the sling from the ground level, so that both the GI strip and the SS pipe get in touch with each other at the top of the bleeder stack, thus completing the electrical circuit through welding machine and on releasing the sling thereafter, the contact point get separated on load (Electrical circuit) and arc takes place in between the two strips which results in ignition of pilot gas i.e. Mixed gas to lit up the burner.

The above and other objects and advantages of the present invention are described hereunder in greater details with reference to the following accompanying non limiting illustrative drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure 1: Shows the Flow Chart of Blast Furnace Gas generation and distribution system in a steel plant.
Figure 2: shows the photographic image of Blast Furnace Gas Bleeder Stack with Pilot burner before implementation of the lighting up system of the invention.
Figure 3: shows a schematic view of the Bleeder Stack before implementation of the inventive burner light up system.
Figure 4: shows the schematic view of the Bleeder Stack after implementation of the pilot burner light up system according to present invention.
Figure 5: shows the photographic image of welding machine located in installation chamber and used to light up the pilot burner by arc striking at top of bleeder stack from ground level.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO ACCOMPANYING DRAWINGS

The present invention is directed to provide a system for Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner from ground level in a fast, safe and reliable manner in case the flame is extinguished in regular operation and a method of such lighting up of the pilot burner.

This is a new inventive concept of lighting up of flare stack from ground level by electrical spark using welding machine, which avoids the hazards viz. working at height and poisonous gas exposure. It also saves production losses if flare stack pilot gets extinguished. This will be of immense benefit to industries requiring lighting up at a height and 24x7 in safe condition.

It is well known that in any large integrated steel plant, BF gas is generated from Furnace top (also known as Top gas). This is called Raw gas containing impurities mainly dust particles. This Raw gas is filtered at Gas Cleaning Plant. The final gas evolved at the end of GCP is called Clean gas. This Clean gas is distributed through BF gas grid. Accompanying Figure 1 shows the Flow Chart of Blast Furnace Gas generation and distribution system.

In normal condition, the total gas generated is fully utilized. The safety range of grid BF gas pressure is 250 MMWG to 400 MMWG. A Pilot Burner located at the top of the Blast Furnace Gas Bleeder Stack of 35 meters height burning throughout the year and 24x7, burns the bled Blast Furnace Gas before releasing to the atmosphere. This is very essential to avoid any safety hazard. The Pilot Burner used to get extinguished due to high wind, heavy rain or/and low mixed gas pressure. Immediate lighting up of Pilot Burner is necessary to ensure continuity in burning the bled Blast Furnace Gas.

Accompanying Figure 2 shows the photographic image and Figure 3 shows a schematic view, of the existing Blast Furnace Gas Bleeder Stack with Pilot burner before implementation of the lighting up system of the invention. In existing practice, if the pilot Burner extinguishes for any reason this needs to be immediately lighted up manually for safety reason which was a very difficult and unsafe task due to its height of 35 meter needing climbing up the ladder. This manual lighting up becomes all the more unsafe during night time due to low visibility. Figure 2 & 3 shows the position of pilot burner at the top of bleeder stack and the staging at a height of about 35 meters where the operator would have to climb up to light up the burner, if and when it is extinguished, which is an unsafe practice consuming much time during which unburned harmful BF gas is released in atmosphere causing health hazard.

Accompanying Figure 4 shows the schematic view of the Bleeder Stack after implementation of the pilot burner light up system according to present invention. Advantageously, the system of the invention enable lighting up the pilot burner from ground level by striking arc with the help of a welding machine and its operative connection to the electrode placed at the top near the burner tip with simultaneous supply of a mixed fuel gas so that mannual operation or climbing up to the stack top is avoided. Following are the features/components of the bleeder stack pilot burner light up system of the present invention as illustrated in Figure 4:

1. Pilot Burner: This is the burner that burns the mixed gas located at top of Bleeder stack(1A) which is 35 meter high.
2. Bracket: The enclosure used for housing the arcing arrangement.
3. Sparking Spot: The gap between two strips where physically the arc takes place .
4. Insulated Block: Porcelain insulators are used to insulate the GI strip from bleeder stack body in order to avoid short circuits between phase and earth conductors of welding machine.
5. GI Strip: GI Strip (34000X50X4mm) used as the conductor carrying phase of welding machine up to the arc point.
6. Earth Pipe: SS Earth pipe (NB50mm ) is used for carrying the mixed gas and also as conductor carrying earth of welding machine up to the arc point.
7. Mixed Gas to pilot burner: It is used for initial light up of pilot burner of bleeder stack. Pilot burner is always(24X7) kept in lit up condition to facilitate the burning of BF gas during bleeding.
8. Mixed Gas Drain Pot: It is used to knock out the moisture and condensate from the gas to avoid the extinction of pilot burner flame.
9. Main Mixed gas supply line: It is the main supply of mixed BF and other gas which is being continuously burned before releasing in atmosphere.
10. Sling: It is connected to the end of GI strip at top near bracket.

A welding machine is installed in a well ventilated chamber nearer to the bleeder stack at ground level as illustrated in Figure 5. Two number of welding cables are connected to GI strip(Phase) & SS earth pipe line carrying Mixed Gas (Earth) In application it is MCB instead of ELCB, which is located in the secondary side of welding machine(Transformer) and in primary side 1phase Isolator is provided.

A non conducting sling is attached to the GI strip at top end near bracket and the other end of the sling hang down to a point that is approachable by an operator standing at ground level.

While operating by pulling the sling from the ground level, both the GI strip and the SS pipe get in touch with each other at the top of the bleeder stack, thus completing the electrical circuit through welding machine. When the sling is released, the contact point get separated on load (Electrical circuit) and arc takes place in between the two strips and which results in ignition of pilot gas i.e. Mixed gas. Thus the burner is lit up.

It is thus apparent that the step by step procedure for present bleeder stack pilot burner light up system comprise:

a. The door of welding machine chamber is opened.
b. The two electrodes i.e. GI strip(+) and SS pipe(-) are extended up to the bottom of the Bleeder stack so that they are in a approachable distance from the welding machine.
c. The phase electrode of welding machine is connected to the insulated GI strip and neutral electrode to the SS pipe carrying mixed gas (connection points are fabricated earlier).
d. Then valve of newly erected mixed gas line is opened to supply fuel to pilot burner.
e. Then the welding machine is switched on and the sling attached to the sparking arrangement at the top of bleeder stack is pulled and thus spark is generated.

Once the sling is released the arcing electrode goes to its normal position on its own weight maintaining sufficient gap between the two electrodes so that arc exists no more. As the conductors used are GI & SS strips, their replacement may be required once in a 4 to 5 years depending upon usage.

The system is designed in such a fashion that the flame(Mixed gas flame is incandescent colour) is visible from the ground level at a distant place from the bleeder stack. Main Pilot mixed gas supply line is different from light up system mixed gas and to differentiate that it is shown in Figure 4 in detached condition.

It is thus possible by way of the present invention to provide a system for Lighting up of Blast Furnace Gas Bleeder Stack Pilot Burner from ground level in a fast, safe and reliable manner in case the flame is extinguished in regular operation such that the following advantages are achieved in regular operations:
• Lighting up of pilot burner done now within 15 minutes as against more than three(3) hours before.
• Pressure drop in Coke Oven Battery eliminated.
• Pushing in Coke Oven Battery significantly enhanced.
• Ensured sufficient availability of Mixed Gas for the Mills area.
• This has resulted in substantial financial savings to the tune of crores.
• Potential safety hazards like Gas poisoning, Fire hazard, working at 35 meter height in unsafe condition eliminated.
• Any employee can now light up the Pilot Burner safely from ground zero.
• Lighting up can be done in night shift also without any fear.
• The entire process now takes less than 15 minutes.
• Saving of precious man hours.
• Employee morale and motivation heightened significantly.