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 SYSTEM FOR ON-LINE CLEANING OF COOLING AND TOP GAS PACKAGING SCRUBBERS IN COREX

2. APPLICANT (S)

Name: JSW Steel Limited.

Nationality: An Indian Company.

Address: Jindal Mansion, 5-A, Dr. G. Deshmukh Marg, Mumbai – 400 026,
State of Maharashtra, 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 cooling and top gas packing scrubbers in Cores and in particular to a system for online cleaning of cooling and top gas packing scrubbers in Cores. It is possible by way of the present invention to provide an online cleaning mechanism which would favour reducing jamming of scrubbers and frequent plant trips importantly the cleaning and draining system of packing scrubbers of the invention would favour cleaning of this scrubbers when the plant is under operation. Advantageously, since online cooling system and we used without keeping of plants or any loss of production it is possible to avoid any unwanted level fluctuation in this scrubber which in term would favour maintaining required uniformity and stability in the production level. The invention would favour drastically reducing the plant shut down or plant trips and would favour maintaining consistent hot metal quality. Importantly also the only draining system is adapted such as to avoid the laborious and hazardous cleaning of scrubbers making the use of gas packing scrubbers both environment and user friendly.
BACKGROUND ART
It is well known that Cores is a smelting reduction iron making process. It basically involves two reactors i) the reduction shaft and ii) the melter-gasifier. A rich reducing gas is generated in the melter-gasifier which is known as generator gas. The generator gas leaving the melter-gasifier is cooled to 850° C and is divided into two lines after passing through hot cyclone one of them heading for the reduction shaft and the other for cooling gas packing scrubber. The gas leaving the reduction shaft is known as top gas. The gas leaving the cooling gas packing scrubber is further divided in two lines one of them heads towards excess gas scrubbers to control system pressure while the other heads towards cooling gas venturi scrubber. The excess gas and the reduction shaft top gas are mixed prior to the take over point and thereafter this gas is termed as Cores export gas.
Importantly the top gas and the excess gas before being mixed are cleaned of dust in these scrubbers. The excess gas is cleaned in cooling gas packing and venturi scrubbers while the top gas in top gas packing and venturi scrubbers. The packing scrubbers contained the contaminated water, which evolves out after cleaning and cooling of the gas. It is a mixture of cool fines, pore fines etc.
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The existing top gas and packing gas cooling scrubbers usually consists of blind flange and gate valve to remove the sludge periodically. While such conventional top gas and cooling gas scrubbers are well known and in use, the same is known to have some inherent drawbacks/limitations as discussed hereunder.
It is experienced that in the above existing systems of top gas and cooling gas-packing scrubbers, the packing scrubbers get jammed upto weir level very frequently. Moreover the LCR ball valves, which are used to control the level of each scrubber, get frequently chocked. Due to the above problems it is found that frequent level fluctuations take place in this scrubber, which in term lead to plant trips and loss of production. To clean these scrubbers, it is thus required to be attended during shut down such that the scrubbers clean manually because of the excess deposits at the bottom. Such manual cleaning of these scrubbers is highly laborious, hazardous and usually leads to extension of shut down time.
It would thus be apparent from the above existing state of the art that the cleaning and cooling of top gas packing scrubber in Cores essentially require frequent shut down and plant trips which in term lead to complexities in maintaining consistent hot metal quality. Moreover the manual cleaning of shut down is also extremely laborious and hazardous which add to the complexities in maintenance and cleaning of the scrubbers.
OBJECTS OF THE INVENTION
It is thus the basic object of the present invention to provide for a system for online cleaning of cooling and top gas packing scrubbers which would avoid the problems of jamming upto weir level very frequently of the packing scrubbers and related consequences of carrying out efficient Cores process.
Another object of the present invention if directed to a system for online cleaning of cooling and top gas packing scrubbers in Cores which would avoid problems of frequent chocking of the LCR ball valves which are used to control the level of each scrubber.
A further object of the present invention is directed to a system for online cleaning of cooling and top gas packing scrubbers in Cores which would favour effective and efficient online cleaning the this scrubbers and avoid problems of any frequent level fluctuation in this scrubbers which can lead to plant trips and loss of production.
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The further object of the present invention is directed to a system for online cleaning of cooling and top gas packing scrubbers in Cores which would avoid the need for frequent shut down of the scrubbers and also would not require manual cleaning of excess deposit of the bottom which is highly laborious, hazardous and leads to extension of shut down time.
A further object is directed to a system for online cleaning of cooling and top gas packing scrubber sin Cores which would enable drastically reducing the number of shut downs and plant trips and help in maintaining consistent hot metal quality without involving extensive labour and/or hazards in cleaning of scrubbers.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided
a system for on-line cleaning of cooling and top gas packing scrubbers in Corex
comprising:
a packing scrubber having a gate valve at the bottom;
a catch pot operatively connected via valve means to said gate valve and disposed below the packing scrubber to selectively allow collection of the contaminated water in said catch pot;
valve means to selectively disconnect said catch pot after collection of the sludge therein from the system and remove /drain out the collected sludge from the bottom of said catch pot.
In accordance with a preferred aspect the system for on-line cleaning of cooling and top gas packing scrubbers in Corex comprises:
a packing scrubber having a gate valve at the bottom;
a catch pot operatively connected through knife gate valve to said gate valve and disposed below the packing scrubber to selectively allow collection of the contaminated water in said catch pot;
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said gate valve at the bottom of the scrubber and said knife gate valve adapted to selectively close to disconnect said catch pot from the system after collection of the sludge therein and remove /drain out the collected sludge from a valve opening at the bottom of said catch pot.
Advantageously, in the above system of the invention, the said catch pot is provided with an air vent adapted to remove air when contaminated water gets filled under pressure in the catch pot. Also, the said catch pot is provided with an inspection nozzle for emergency situation.
The catch pot is operatively connected to an open launder pump house through a butterfly valve provided below the catch pot.
Preferably, the online system comprises a pneumatic system adapted to operate the knife gate valve.
In accordance with another aspect of the present invention there is provided a method for on-line cleaning of cooling and top gas packing scrubbers in Corex using the system as above comprising:
collecting contaminated water from said packing scrubber passing through said gate valve and said knife gate valve into said catch pot disposed below the packing scrubber to thereby selectively allow collection of the contaminated water in said catch pot; and
using valve means to selectively disconnect said catch pot after collection of the sludge therein from the system and removing /draining out the collected sludge from the bottom of said catch pot.
In accordance with a preferred aspect the above method for on-line cleaning of cooling and top gas packing scrubbers in Corex using the system comprises :
collecting in said catch pot the contaminated water via said knife gate valve and said gate valve disposed below the packing scrubber to selectively allow collection of the contaminated water in said catch pot;
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using the gate valve and said knife gate valve to selectively close to disconnect said catch pot from the system after collection of the sludge therein; and
removing /draining out the collected sludge from a valve opening provided at the bottom of said catch pot.
In accordance with a further preferred aspect the above method for on-line cleaning of cooling and top gas packing scrubbers in Corex using the system comprises:
(i) opening said gate valve immediately below said packing scrubber keeping the knife gate valve and valve vent in open position and said butterfly valve at the outlet of the catch pot closed whereby some amount of the sludge is taken into the catch pot;
(ii) closing the vent valve once the sludge is released from the scrubber;
(iii) disconnecting the catch pot from the system by closing said gate valve and said knife gate valve;
(iv) draining out the sludge /contaminated water in the catch pot through the opening in said butterfly valve; and
(v) repeating the above steps (i) to (iv) for clearing all contaminated water out of the system; and
(v) finally after the draining process is over closing all said valves comprising gate valve, knife gate valve, vent valve and said butterfly valve.
It is thus possible by way of the above online cleaning of cooling and top gas packing scrubbers in Cores to reduce plant trips importantly the catch pot introduced in the scrubber would favour collection of the contaminated water.
In accordance with a preferred aspect of the invention the catch pot is provided with an air vain to remove the air when contaminated water gets field under pressure in the catch pot. The catch pot is also provided with an inspection nozzle for any emergency situation.
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The get valve below the scrubber is connected to the scrubber to the knife get valve. The collected sludge from catch pot is removed/drained to an open launder pump house with the help of a butter fly valve provided below the catch pot. Preferably a pneumatic system is arrange in order to operate the knife gate valve.
The modified draining system is adapted to favour provision to clean the scrubbers even when the plant is under operation. The cleaning is preferably attended ones in eight hours (3 times a day) to keep the gas cleaning system healthy. This keeps the scrubbers and the cone drains clean.
Importantly, in the above system a catch pot has been introduced below the packing scrubbers to collect the contaminated water. An air vent is provided to remove the air when the contaminated water gets filled under pressure in the catch pot. An inspection nozzle further favours for attending to any emergency situations.
The collected sludge from the catch pot is removed /drained to an open launder pump house with the help of butterfly valve provided below the catch pot.
Advantageously the above online cleaning system facilitates the cleaning of the scrubbers even when the plant is under operation. Thus the system of the invention favours maintaining the scrubbers and the cone drains-clean.
The details of the invention, its objects and advantages are explained hereunder in greater detail in relation to non-limiting exemplary illustrations as per the following accompanying figures:
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES:
Figure 1: is a schematic illustration of a presently available conventional packing scrubber system; and
Figure 2: is a schematic illustration of an online system for cleaning of cooling and top gas packing scrubbers in Corex in accordance with the present invention.
DEATILED DESCRIPTION OF THE INVENTION:
Reference is first invited to accompanying figure 1 which shows the arrangement in a convention packing scrubber in Corex. As discussed herein before, Corex is a smelting
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reduction iron making process. It basically includes two reactors; (i) the reduction shaft, and (ii) the melter-gasifier. A rich reducing gas is generated in the melter-gasifier, known as generator gas. Generator gas leaving the melter-gasifier is cooled to 850°C and is divided into two lines after passing through hot cyclones, one of them heads for the reduction shaft, and the other for cooling gas packing scrubber. The gas leaving the reduction shaft is the top gas. The gas leaving the cooling gas packing scrubber is further divided into two lines, one of them heads towards excess gas scrubber to control system pressure, and the other towards cooling gas venturi scrubber. This excess gas and the reduction shaft top gas are mixed prior to the take over point. Thereafter this gas is termed as COREX export gas.
It is conventionally followed that the top gas and excess gas before being mixed are cleaned of dust in the scrubbers. The excess gas is cleaned in cooling gas packing and venturi scrubbers, while the top gas in top gas packing and venturi scrubbers. The packing scrubbers contain the contaminated water which has evolved out after cleaning & cooling the gas. It is a mixture of coal fines, ore fines etc.
The top gas and cooling gas packing scrubbers are as shown in Fig.l and basically comprises of blind flange and gate valve to remove the sludge periodically. However, in such conventional packing scrubbers it is often found that the packing scrubber gets jammed up to weir level very frequently. The LRC ball valves which are used to control the level of each scrubber also gets frequently choked. Due to above problems there frequent level fluctuations in the scrubbers which leads to plant trips & loss of production.
Thus in the conventional systems the scrubbers are cleaned manually during shutdowns because of excess deposits at the bottom, which is highly laborious, hazardous and leads to extension of shutdown time.
The online cleaning of cooling and top gas packing scrubbers in Corex in accordance with the present invention is directed to take care of the above discussed problems and limitations of the conventional packing scrubber systems.
Reference is now invited to accompanying Figure 2 which schematically illustrates the online cleaning system in accordance with the present invention. While the basic arrangement of the gas packing scrubber is the same as that of the conventional, system
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as shown in Figure 1, in the present system to facilitate the online cleaning a catch pot has been introduced below the packing scrubbers to collect the contaminated water. Preferably, the catch pot is provided with an air vent to remove the air when contaminated water gets filled under pressure in the catch pot. The catch pot is also provided with an inspection nozzle for any emergency. The gate valve (VI) below the scrubber is connected to the catch pot through a knife gate valve (V2).The collected sludge from the catch pot is removed/drained to an open launder pump house with the help of a butterfly valve (V4) provided below the catch pot. A pneumatic system has been provided in order to operate the knife gate valve (V2).
The above illustrated draining system of packing scrubbers of the invention shown in Figure 2 provides for provision to clean the scrubbers when plant is under operation. The cleaning is preferably being done once in 8 hours (three times a day) to keep the gas cleaning system healthy. This keeps the scrubber & the cone drains clean.
The draining procedure for the scrubber system and ,in particular, the online cleaning thereof can be preferably attended using the system of the invention as hereunder:
i) The bottom valve (VI) is opened keeping the valves (V2), (V3) in open
position and (V4) in closed position. By this some amount of sludge is taken
into the catch pot.
ii) Next, the vent valve V3 is closed once the sludge has come out.
iii) Thereafter, the catch pot is disconnected from the system by closing the
valves (VI) & (V2).
iv) The sludge/contaminated water in the catch pot is then drained by opening
the valve (V4).
The above procedure stages (i) to (iv) are repeated till all the water clears out of the system. Once the draining process is over (which takes about 5 minutes) all the valves (VI), (V2), (V3), & (V4) are closed.
The efficacy of the on-line cleaning system of the invention as shown in Figure 2 vis-avis the conventional system of Figure 1 was further tested in the plant and the results obtained were as noted hereunder in Table 1:
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Conventional System Total Shut Down In Hours
Months Tried Unit -1 Unit-2 Total
First Month 7.4 16.4 23.8
Second Month 0.0 0.0 0.0
Third Month 12.3 34.0 46.3

System Of The Invention Total Shut Down In Hours
Months Tried Unit-1 Unit-2 Total
First Month 5.9 0 5.9
Second Month 1.05 0.9 1.9
Third Month 0.12 0 0.1
Fourth Month 0.23 0 0.2
TABLE :1
It would be clearly apparent from the above results that the number of shut downs per year could be drastically reduced using the online cleaning system of the invention. Also, the plant trips have been reduced, which has helped in maintaining consistent hot metal quality. Advantageously also the system of the invention has avoided the laborious and hazardous cleaning of gas scrubbers.
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WE CLAIM:
1. A system for on-line cleaning of cooling and top gas packing scrubbers in Corex
comprising:
a packing scrubber having a gate valve at the bottom;
a catch pot operatively connected via valve means to said gate valve and disposed below the packing scrubber to selectively allow collection of the contaminated water in said catch pot;
valve means to selectively disconnect said catch pot after collection of the sludge therein from the system and remove /drain out the collected sludge from the bottom of said catch pot.
2. A system for on-line cleaning of cooling and top gas packing scrubbers in Corex
comprising:
a packing scrubber having a gate valve at the bottom;
a catch pot operatively connected through knife gate valve to said gate valve and disposed below the packing scrubber to selectively allow collection of the contaminated water in said catch pot;
said gate valve at the bottom of the scrubber and said knife gate valve adapted to selectively close to disconnect said catch pot from the system after collection of the sludge therein and remove /drain out the collected sludge from a valve opening at the bottom of said catch pot.
3. A system for on-line cleaning of cooling and top gas packing scrubbers in Corex as claimed in anyone of claims 1 or 2 wherein the said catch pot is provided with an air vent adapted to remove air when contaminated water gets filled under pressure in the catch pot.
4. A system for on-line cleaning of cooling and top gas packing scrubbers in Corex as claimed in anyone of claims 1 to 3 wherein said catch pot is provided with an inspection nozzle for emergency situation.
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5. A system for on-line cleaning of cooling and top gas packing scrubbers in Corex as claimed in anyone of claims 1 to 4 wherein wherein said catch pot is operatively connected to an open launder pump house through a butterfly valve provided below the catch pot.
6. A system for on-line cleaning of cooling and top gas packing scrubbers in Corex as claimed in anyone of claims 1 to 5 comprising a pneumatic system adapted to operate the knife gate valve.
7. A method for on-line cleaning of cooling and top gas packing scrubbers in Corex using the system as claimed in anyone of claims 1 to 6 comprising:
collecting contaminated water from said packing scrubber passing through said gate valve and said knife gate valve into said catch pot disposed below the packing scrubber to thereby selectively allow collection of the contaminated water-in said catch pot; and
using valve means to selectively disconnect said catch pot after collection of the sludge therein from the system and removing /draining out the collected sludge from the bottom of said catch pot.
8. A method for on-line cleaning of cooling and top gas packing scrubbers in Corex using the system as claimed in claim 7 comprising:
collecting in said catch pot the contaminated water via said knife gate valve and said gate valve disposed below the packing scrubber to selectively allow collection of the contaminated water in said catch pot;
using the gate valve and said knife gate valve to selectively close to disconnect said catch pot from the system after collection of the sludge therein; and
removing /draining out the collected sludge from a valve opening provided at the bottom of said catch pot.
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9.A method for on-line cleaning of cooling and top gas packing scrubbers in Corex using the system as claimed in anyone of claims 7 to 8 comprising;
(i) opening said gate valve immediately below said packing scrubber keeping the knife gate valve and valve vent in open position and said butterfly valve at the outlet of the catch pot closed whereby some amount of the sludge is taken into the catch pot;
(ii) closing the vent valve once the sludge is released from the scrubber;
(iii) disconnecting the catch pot from the system by closing said gate valve and said knife gate valve;
(iv) draining out the sludge /contaminated water in the catch pot through the opening in said butterfly valve; and
(v) repeating the above steps (i) to (iv) for clearing all contaminated water out of the system; and
(vi) finally after the draining process is over closing all said valves comprising gate valve, knife gate valve, vent valve and said butterfly valve.
10. A system for on-line cleaning of cooling and top gas packing scrubbers in Corex and a method for using said system for said on-line cleaning of cooling and top gas packing scrubbers in Corex substantially as herein described and illustrated with reference to the accompanying Figure 2.
Dated this 30th day of January, 2007. Anjan Sen
Of Anjan Sen & Associates (Applicants Agent)
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ABSTRACT
A SYSTEM FOR ON-LINE CLEANING OF COOLING AND TOP GAS PACKING SCRUBBERS IN COREX.
A system for online cleaning of cooling and top gas packing scrubbers in Corex directed to provide an online cleaning mechanism which would favour reducing jamming of scrubbers and frequent plant trips. Importantly the cleaning and draining system of packing scrubbers of the invention would favour cleaning of the scrubbers when the plant is under operation^ Advantageously, since online cleaning of cooling system can be effected without any loss of production and also importantly it would be possible to avoid any unwanted level fluctuation in the scrubber which in turn would favour maintaining required uniformity and stability in the production level. The invention would favour drastically reducing the plant shut down or plant trips and would favour maintaining consistent hot metal quality. Importantly also the draining system is adapted such as to avoid the laborious and hazardous cleaning of scrubbers making the use of gas packing scrubbers both environment and user friendly. Figure 2.
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