REFERENCE TO MAIN APPLICATION
The present application is an application for a patent of addition in respect of Indian Patent Application no. 1061/KOL/2015 entitled “IMPROVED 5.0 M. TALL COKE OVEN BATTERY” filed on 07 October 2016, referred as the main invention in this specification.
FIELD OF THE INVENTION
The present invention relates in general to production of coke in coke oven batteries for steel making in blast furnaces, and in particular to an improved 7.0M tall coke oven battery. The battery is provided with several additional inventive features and produces coke for use in blast furnaces for the purpose of steel making.
BACKGROUND AND PRIOR ART
Coke is produced by high temperature carbonization of pulverized coking coal (-3 mm size). In this process, coal is heated in absence of air up to a temperature of 10000C - 10500C to form lumpy coke. Coke is the most important raw material that is fed into the blast furnace in terms of its effect on blast furnace operation and hot metal quality. The coke making process generates several by-products which may be solid, liquid, gaseous or plastic in nature. Many of these by-products are toxic and dangerous for the environment. They have to be handled with great care and control. A high quality coke should be able to support a smooth decent of the blast furnace burden with as little degradation as possible while providing the lowest amount of impurities, highest thermal energy, highest metal reduction and optimum permeability for the flow of gaseous and molten products.
Coke is produced in batteries, each of which has a plurality of slot type ovens for carbonization of coal. Coal (coming from the coal preparation plant and stored in coal tower) is charged to each oven sequentially and heated in the absence of air for a specific period of time (known as coking period) to drive out the volatile matter present within coal. When the gas evolution and subsequent coal carbonization is complete, coke is pushed out of the oven, quenched and cooled suitably through wet/dry method and finally sent to the blast furnace via coke handling plant. Evolved gases from the ovens are taken to by-product plant for recovery of various valuable chemicals like tar, ammonia, naphthalene, benzene,

sulphur, toluene, xylene etc. The cleaned coke oven gas still has a high calorific value and is supplied back to the coke oven as a heating fuel.
Hence coke oven battery can be operated without any external source of fuel. Surplus coke oven gas is utilized in other units of the plant. However, provision is also generally kept for utilising blast furnace gas (BFG)/ Mixed gas (MG) as alternate fuel.
Following types of machinery are used for the coke oven operation of the prior art:
a) Charging car- it receives coal from coal tower located nearby and charges the same into the individual ovens.
b) Pusher car- it pushes the ready coke out of the oven and also levels the coal inside an oven during charging.
c) Transfer/Guide car- it guides the coke which is pushed out of an oven onto the receiving quenching car/Coke car.
d) Quenching car (in case of wet quenching)- it receives hot coke from the ovens, takes it to the quenching tower for cooling and finally disposes the cold coke to coke wharf.
e) Coke car (in case of dry quenching)- it takes hot coke from oven to the coke dry cooling plant (CDCP). Cooled coke is directly charged to conveyors from CDCP for onward transmission to Blast Furnace via coke handling plant.
In general one coke oven battery is generally operated with the help of one working plus one standby set of such machines. However, presently for a pair of Coke oven batteries, two sets of working plus one set of standby oven machines are used.
A coke oven battery is designed on the target coke output per year. Accordingly, the effective volume of a single oven, number of pushing/charging required per day, total number of ovens in a battery, scheduled carbonization time (coking period) etc. are decided.
Since long, efforts are being made worldwide to make the coke-making process cheaper, more and more user friendly as well as environment friendly. Development of batteries with larger oven volume is a very effective way to achieve the same.

Although batteries have been in operation for several decades, the batteries of the prior art suffer from several drawbacks. Mostly, they fail to meet the increased demand of coke. A coke oven battery, apart from the ovens, has several other components like heating walls, regenerators, gas supply system, waste gas system including tunnels and chimney, gas off¬take system, reversing mechanism, oven machines etc. The design and size of each and every such component of the battery is dependent on the number of ovens, dimensions and capacity of each oven directly or indirectly. For example, the capacity of the oven decides the amount of coal to be charged in it which in turn stipulates the amount of gas evolved and the gas off-take system of the battery is designed accordingly. It also decides the amount of coke to be pushed from an oven which decides the details of the oven machine design as well as or coke cooling/quenching system. Again, the oven width decides the coal carbonization time and thereby the heating system.
The main invention contained in the patent application number 1061/KOL/2015 dated 07 October 2015 discloses an “IMPROVED 5.0 M. TALL COKE OVEN BATTERY” for production of coke in coke oven batteries for steel making in blast furnaces in a more environment friendly, efficient and economic way.
After the main patent application was filed, the continuous research has developed some additional features, which have been incorporated without any changes in the basic design of the equipment disclosed in the main invention, only to make the coke oven batteries more efficient and cost effective. These additional features are the subject of the present application for a patent of addition to the main invention.
Some of the salient features which are related to the additional features are as follows:
a) Stainless steel sheet (0.2 mm thick) in oven decking:
• Better sealing against gas leakage
• Acts as heat shield to reduce operating temperature at oven top.
b) Stainless steel sheet (0.2 mm thick) in regenerator face wall:
• Better sealing against gas leakage.
• Acts as heat shield to minimize heat loss.
c) Sliding Joint at Oven Roof:
• Allow free expansion for oven roof silica layers
• Restricts cracks and open joints at oven top during heating up.

d) Oven roof thickness increased:
• Enhances structural stability of brick work at oven roof.
• Reduces operating temperature at oven top yielding better working condition
e) Provision of water sealing in the Ascension pipe
• Better sealing resulting less pollution.
• Reliable operation
f) Use of the U-type GC Main with mounted Valve Box:
• For better operation advantage like less jamming of isolation valve.
• Provision of running seal in spigot joint resulting less pollution
• Easier fabrication and erection
g) Complete elimination of gas leakage in the interface of Gooseneck and Valve Box
i.e. spigot joint by providing water seal
h) Automatic Bleeder with modified Overflow system with double water seal
• Quicker release of raw CO gas during exhauster failure and thus avoids
over pressurization of oven and G.C. mains during that period.
i) Modified Cross Over and Suction Main Without Bridge
• Better pressure control
• Reduced cost/Tonnage
j) Service Bench Independent of Buckstays:
• Shifting of DE car track along with expansion of the battery during heating up is avoided.
• Less maintenance and regulation
k) Auxiliary Anchorage at Oven Roof Sliding Joint
• Eliminate dragging of fireclay along with expanding silica (which has higher coefficient of thermal expansion than that of fireclay) during the heating up.
• Eliminating the probability for any damage to oven roof brick work during heating up.
l) Modified Anchorage System with improved small anchorage
• Proper loading of brick work of regenerator mid fraser wall.
• Elimination of cross leakage at the joint between fireclay and silica at bus
flue top course and regenerator bottom course.

The present patent of addition application entitled “IMPROVED 7.0 M. TALL COKE OVEN BATTERY” has the following common features with the main invention, which are fully disclosed in both applications.
1. Even though there is a size difference in the waste gas tunnels, common tunnels of exhaust flues connected to chimney, layout of these tunnels are similar. The height of the chimney for 5M tall coke oven battery is 100 M and for 7M tall it is 120M.
2. Basic heating system of under firing with coke oven gas is same, although there is a difference in the number of flues of heating wall due to difference of capacity of coke oven batteries. In 5M tall battery 30 numbers of flues and in case of 7M tall battery 32 flues have been used in the heating system.
3. Number of charging holes for both the batteries is 3.
4. Both the batteries are provided with fire clay bus flues and full Silica Regenerators.
5. Anchorage system is similar with different loads due to difference in length and height.
6. Both are provided with underground cellars.
7. Both the batteries are provided with both side (P/s and C/s) Coke oven and Mixed gas heating headers and gas collecting main.
8. Both the batteries are provided with SS foil arrangement at Regenerator face wall and at oven roof brick work.
OBJECTS OF THE INVENTION
The primary objective of the invention is to provide a coke oven battery which is more cost effective, efficient and environment-friendly.
Another object of the invention is to provide a coke oven battery which operates at a reduced temperature during the heating up process, thus resulting in better working condition at the oven top and offers structural stability of brick work at oven roof by increasing the thickness of the oven roof.
Another object of the invention is to provide water sealing in the Ascension pipe resulting in less pollution and reliable operation and U type gas collecting mains with built in valve box

to avoid jamming of valve box. It also reduces eccentric load on buck stay and improves working space on gas collecting main.
Yet another object of the invention is to provide a coke oven battery which prevents any gas leakages from oven roof zone to the atmosphere.
Another object of the invention is to provide a coke oven battery having cantilever type service platforms and independent of buck stays, thereby reducing load on buck stays to increase their life.
Yet another object of the invention is to provide a coke oven battery that totally eliminates the chances of gas leakage in the interface of Gooseneck and Valve Box i.e. Spigot joint by providing water seal.
Another object of the invention is to provide a coke oven battery having automatic bleeder and modified overflow system with double water seal for quicker release of raw CO gas during exhauster failure and thus avoids over pressurization of oven and G.C. mains during that period.
How the foregoing objects are achieved will be clear from the following description. In this context it is clarified that the description provided is non-limiting and is only by way of explanation.
SUMMARY OF THE INVENTION
An improved 7.0M tall coke oven battery of compound, regenerative and under jet type ovens is provided with partial recirculation of waste gases and twin flue. The battery has 67 ovens in a single block. It comprises of two gas collecting mains, one each positioned on pusher side and coke side. Three charging holes and two gas off-take openings are provided in each oven on the oven roof. Two buckstays are provided on either side of the heating wall. The battery has two waste heat tunnels, one each being positioned at pusher side and coke side.
A common tunnel leads to a chimney located on pusher side in the middle of the battery.

Two U type gas collecting mains with built in valve box are provided, one each on pusher side and coke side. There are two cantilever type service platforms.
The valve box is provided to facilitate disconnection of the gas collecting main from the coke ovens during the pushing process to avoid jamming of the valve box, reduce eccentric load on the buckstay and improve working space on the gas collecting main.
The service platforms are provided on both pusher side and coke side to facilitate movement of operating personnel to attend to the operation and maintenance. Their cantilever portions extend up to the buckstays but are not supported on them to reduce load on buck stays and thereby increase the life of the buckstays.
The ovens are provided with increased thickness of the oven roofs to enhance Suga index/structural stability of brickwork at the oven roof to reduce the operating temperature of the oven top resulting in better working condition for personnel at the oven top.
The battery is provided with re-drawn pusher side return ammonia liquor line from the end of each gas collecting main to avoid placing the tar box in the line of suction main. This reduces deposition in the pipe lines and preserves their cross sectional area while allowing a natural flow by gravity with no energy being required for the liquor to flow.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The nature and scope of the present invention will be better understood from the accompanying drawings, which are by way of illustration of a preferred embodiment and not by way of any sort of limitation. In the accompanying drawings:-Figure 1 is the cross sectional view of the coke oven battery according to the present invention.
Figure 2 is the enlarged view of the “Detail A” of figure 1 showing the cross–sectional view of oven, including the oven roof.
Figure 3A is the enlarged view of the “Detail D” of figure 2 showing the oven roof refractory.

Figure 3B is a similar view of “Detail D” in a conventional coke oven battery.
Figure 4 is the enlarged view of the “Detail B” of figure 1 showing the gas off-take system, in particular the general arrangement of the “U” shaped gas collecting main.
Figure 5 is the enlarged view of the “Detail C” of figure 1 showing the general arrangement of the coke side service platform for waste heat box over LG main.
Figure 6 is the plan view of the return ammonia liquor line.
DETAILED DESCRIPTION OF THE INVENTION
Having described the main features of the invention above, a more detailed and non-limiting description of a preferred embodiment will be given in the following paragraphs with reference to the accompanying drawings.
In all the figures, like reference numerals represent like features. Further, the shape, size and number of the devices shown are by way of example only and it is within the scope of the present invention to change their shape, size and number without departing from the basic principle of the invention.
Further, when in the following it is referred to “top”, “bottom”, “upward”, “downward”, “above” or “below” , “right hand side”, “left hand side” and similar terms , this is strictly referring to an orientation with reference to the apparatus , where the base of the apparatus is horizontal and is at the bottom portion of the figures. The number of components shown is exemplary and not restrictive and it is within the scope of the invention to vary the shape and size of the apparatus as well as the number of its components, without departing from the principle of the present invention.
All through the specification including the claims, the technical terms and abbreviations are to be interpreted in the broadest sense of the respective terms, and include all similar items in the field known by other terms, as may be clear to persons skilled in art. Restriction or

limitation if any referred to in the specification, is solely by way of example and understanding the present invention.
As mentioned earlier, the present application is one for a patent of addition to the main invention disclosed in Indian Patent Application no. 1061/KOL/2015 entitled “IMPROVED 5.0 M TALL COKE OVEN BATTERY” filed on 07 October 2016.
At the outset we present below the crux of the main invention:
“An improved 5.0 m. tall coke oven battery of compound, twin flue, under jet, regenerative type with partial recirculation of waste gases has 69 ovens in single block. It has double gas collecting mains, one each on pusher side and coke side, its oven roofing consisting of two layers of silica, four layers of fireclay and one layer of high CCS fireclay. The fireclay bricks are placed over silica bricks for reducing heat transfer rate towards oven top to maintain oven top temperature in working range. A sliding joint arrangement is provided between 59th and 60th course at the oven roofing and SS foil is provided between 11th and 12th layers of filling bricks at oven roofing zone between 62nd and 63rd course of fireclay to further reduce heat loss and prevent raw coke oven gas leakage from oven top.
A layer of SS foil is provided between mica and fireclay brickwork at regenerator face wall to prevent ingress of cold air inside regenerators. The SS foil is 0.2 mm thick and conforms to IS 316L/AISI316.
Two pairs of auxiliary springs are provided on the face of oven roof fireclay brick zone on both pusher and coke sides to avoid dragging in the horizontal direction and prevent opening of brick joints in the fireclay zone.
The sliding joint arrangement is made between adjacent layers of silica and fireclay by providing graphite powder, industrial glycerin and water between the topmost layer of silica and bottom most layer of fireclay at oven roof zone to facilitate smooth sliding of silica over fireclay brick with the aid of a pair of auxiliary springs through auxiliary 5 anchorage, Buckstay and coil springs, channel and a face wall cover plate to prevent any gas leakage. Solid bricks are provided in every heating wall across the length of heating wall of every oven for providing necessary support for charging car track.

The catenaries for charging car power lines are laid along the centre line of the battery so that they normally do not come in contact with flames from ascension pipes. Catenaries for DE cars are not supported from individual buckstay (as is the normal practice without catenary). This avoids sagging of DE car power line with expanding/deflecting buckstays during operation.”
Now, in accordance with the present addition, there is provided an improved 7.0M tall coke oven battery which incorporates several new and inventive features. A non-limiting list of these features is as under:
1. U Type Gas collecting mains with built in valve box to avoid jamming of valve box. It also reduces eccentric load on buckstay and also improves working space on gas collecting main.
2. Service platforms have been made cantilever type and independent of buck stays, thereby reducing load on buck stays for longer life.
3. Oven roof thickness increased to enhance Suga index/ structural stability of bricks at the oven roof. This also reduces operating temperature resulting in better working condition at the oven top.
4. Pusher Side return ammonia liquor line is drawn from the end of each gas collecting main (like Coke Side) to avoid Tar box in the inline of suction main.
We now refer to the accompanying drawings.
Figure 1 is the cross section of the coke oven battery according to the present invention in the elevation view.
The 7M tall battery is of compound, regenerative type with partial recirculation of waste gases, twin flue, under jet type. The battery is of 67 ovens in single block. The battery consists of double gas collecting mains (1), one each on pusher side and coke side. There are 3 numbers of charging holes (10) and two gas off-take openings (12) in each oven provided on the oven roof (11). Two buckstays (9) are provided on either side of the heating wall. There are two waste heat tunnels, one at pusher side and the other at coke side, with a common tunnel leading to chimney located on pusher side in the middle of the battery. Oven pushing per day is 100.

The oven parameters of the battery are given below:

Increase in output per oven:
With the above parameters, the output of coke per oven increases appreciably. For the 5 M Tall Coke Oven Battery, the gross coke output per oven is 15.415 Ton, which translates into a gross coke output per annum of 0.5 Million Tons. With the increase of height of the oven as per the present invention, the 7 M Tall Coke Oven Battery has a gross coke output per oven of 24.03 Ton, which amounts to a gross coke output per annum of 0.88 Million Tons. Thus there is an increase of 66% in the gross annual output of coke due to the new features of the invention.
It may be clearly understood that the above figures are illustrative in nature and may vary in actual performance of the invention. The invention is equally applicable to batteries having other specifications as well.

1. U Type Gas collecting mains with built in valve box:
Reference is made to figure 4 which shows the enlarged view of the “Detail B” of figure 1 showing the general arrangement of the “U” shaped gas collecting main (1). It is a fabricated pipe for collecting the gas generated from coke ovens and acts as a buffer vessel with a pressure of about 15-20 mmwc. The rest of the gas is transferred to coal chemical plant through an exhauster. The gas collecting main is located at the oven top of the coke oven battery, on both the pusher side and the coke side. The gas collecting main is connected to the coke oven through the series of stand pipe (2), goose neck (3) and valve box (4). Basically this equipment is to facilitate smooth gas transfer without any leakage of coke oven gas to the atmosphere. A stand pipe (2) top is provided with a T pipe (5). This T pipe (5) is connected on one side with the goose neck (3) and the other side is connected with the water sealed stand pipe (Ascension pipe). The stand pipe (2) is provided with base casting (8) at its bottom, resting on oven top. The water seal comprises of an A.P.Cap (6) and an A.P.Lid (7). This cap is opened during coke pushing and for the rest of the time, i.e. during and after charging of ovens, this cap remains closed and a water seal is maintained to stop gas leakage.
The valve box (4) is provided to facilitate disconnection of the gas collecting main (1) from the coke ovens during the pushing process. For the rest of the time, the valve box is in opened condition to connect the coke ovens to gas collecting main for smooth transfer of coke oven gas produced in the coke ovens.
Mode of operation:
All valve boxes are manually operated. However gas transfer from gas collecting main/cross over main to suction main shall be controlled through butterfly valves, which are operated either hydraulically or pneumatically. They are fabricated from MS plate as per IS: 2062.
Benefits:
i) It avoids jamming of the valve box (4).
ii) It reduces eccentric load on buck stay (9) and improves working space on the gas collecting main.

2. Provision of cantilever type Service platforms independent of buck stays:
Figure 5 is the enlarged view of the “Detail C” of figure 1 showing the general arrangement of the service platform (13) for waste heat box (14) over Blast Furnace gas main (18). This figure shows the location of coke car loco power rail (17), Blast Furnace gas main (18) and waste gas flue (19) of the battery.
Service platforms (13) are provided on both pusher side and coke side to facilitate movement of operating personnel to attend to the operation and maintenance. In the prior art, the service platform is supported on Buckstays on the battery side and on the structural/civil columns on the other side. Due to expansion of coke oven battery during operation, in the prior art, there used to be movement of the service platform which in turn affected the alignment of guide car track etc. Further, due to loading on Buckstays, the life of the Buckstays also got reduced. The platforms are located on both pusher side and coke side of the coke oven battery along the length of the battery, at about 1m below the oven sole level.
The service platform (13) is a concrete static structure of cantilever design with its supporting columns away from the ovens. Its cantilever portion extends up to the buckstays (9) but is not supported on them. It is made from reinforced cement concrete (RCC) structure.
Benefits :
i) It reduces load on buck stays (9).
ii) It increases the life of the buck stays as well as battery.
3. Increase of oven roof thickness to enhance Suga index/structural stability of brickwork at oven roof:
Figure 3A shows an enlarged view of the “Detail D” of figure 2 showing the cross section of the oven roof refractory according to the present invention and Figure 3B is a similar view in a coke oven battery of the prior art.
This improvement is a part of the coke oven refractory, which is the main body of the coke oven. It is located above the vertical flue of coke oven battery. Oven roof is the top most

part of the refractory portion of coke ovens on which oven top equipment (gas off-take system and charging car track) is located. Oven top temperature is a major concern for the personnel operating on the oven top.
In earlier designs, oven roof (silica plus fireclay refractory) refractory height (h) was 1060mm. In the modified design, the height (H) of the same has been increased (H>h) to 1340 mm by increasing two courses of fireclay refractory. Fire clay refractory is located on top of silica refractory there for reducing the heat loss from the battery, which in turn reduces the oven top temperature. It is a static structure and only expansion of refractory takes place due to temperature.
The material of construction is silica refractory, silica mortar, fireclay refractory and fireclay mortar.
Benefits :
i) It reduces the operating temperature of the oven top resulting in better working
condition for personnel at the oven top. ii) Increases the SUGA index of the battery and thereby stability.
4. Re-drawing of pusher side return ammonia liquor line from the end of each gas collecting main (like coke side) to avoid tar box in the line of suction main:
Figure 6 shows the plan view of the return ammonia liquor line (15).
In earlier batteries, hot gases evolved from coke ovens pass through stand pipe (2), goose neck (3), gas collecting main (1), tar boxes (16), cross over main and suction main before being transferred to the coal chemical plant. The temperature of the hot gases is cooled to below 80°C in the goose neck (3) and gas collecting main (1) by spraying ammonia liquor. This liquor along with the condensed chemicals like tar etc. is called return ammonia liquor. Earlier, this liquor used to move along the suction main and foul gas main on the pusher side of coke oven battery and used to get separated at downcomers near the primary gas coolers to flow into decanters. Due to this, there used to be deposition in the pipe lines and their cross sectional area used to reduce.

The return ammonia line is a pipe line starting from the coke oven top to the decanter of coal chemical plant. Due to above problem, on pusher side also the return ammonia liquor line has been separated from the gas mains and the withdrawal of the liquor is done from the gas collecting main ends though a separate line. This line in turn connects with the return ammonia liquor line of coke side near the stockade located in front of coke oven battery, thereby excluding the tar box (16) from the line. With the re-drawn return ammonia liquor line, this problem has been reduced.
It has a natural flow by gravity and no energy is required for the liquor to flow. The line is made from mild steel pipes and mild steel plate (IS-2062) and provided with isolation valves.
Benefits:
It reduces deposition in the pipe lines and preserves their cross sectional area.
The present invention has been described with reference to some drawings and a preferred embodiment purely for the sake of understanding and not by way of any limitation and the present invention includes all legitimate developments within the scope of what has been described herein before and claimed in the appended claims.

We claim:
1. An improved 7.0M tall coke oven battery of compound, regenerative and under jet type ovens provided with partial recirculation of waste gases and twin flue, the battery having 67 ovens in a single block and comprising of two gas collecting mains (1), one each positioned on pusher side and coke side, three charging holes (10) and two gas off-take openings (12) provided in each oven on the oven roof (11), two buckstays (9) provided on either side of the heating wall, the battery having two waste heat tunnels, one each being positioned at pusher side and coke side, a common tunnel leading to a chimney located on pusher side in the middle of the battery, two U type gas collecting mains (1) with built in valve box (4), one each being provided on pusher side and coke side and two cantilever type service platforms (13).
2. The improved 7.0M tall coke oven battery as claimed in claim 1, wherein said valve box (4) is provided to facilitate disconnection of the gas collecting main (1) from the coke ovens during the pushing process to avoid jamming of the valve box (4) and to reduce eccentric load on said buckstay (9) and improve working space on the gas collecting main (1).
3. The improved 7.0M tall coke oven battery as claimed in claim 1, wherein said service platforms (13) are provided on both pusher side and coke side to facilitate movement of operating personnel to attend to the operation and maintenance, their cantilever portions extending up to the buckstays (9) but are not supported on them to reduce load on buck stays (9) and thereby increase the life of the buckstays.
4. The improved 7.0M tall coke oven battery as claimed in claim 1, wherein said ovens are provided with increased thickness of the oven roofs (11) to enhance Suga index/structural stability of brickwork at the oven roof to reduce the operating temperature of the oven top resulting in better working condition for personnel at the oven top.

5. The improved 7.0M tall coke oven battery as claimed in claim 1, wherein said battery is provided with re-drawn pusher side return ammonia liquor line (15) from the end of each gas collecting main to avoid tar box (16) in the line of suction main which reduces deposition in the pipe lines and preserves their cross sectional area while allowing a natural flow by gravity with no energy being required for the liquor to flow.