Claims:WE CLAIM:
1. A system (100) for measuring coking pressure at a fixed wall (6) of a lab/pilot scale coke oven, the system (100) comprising:
a groove (19,24) provided over a heating side of the fixed wall (17,21);
a pressure plate (1) being freely suspended over the groove (19,24) to realize a pressure exerted from a heated coking coal; and
a pressure transmitting assembly (2) coupled to the pressure plate (1) to transmit pressure exerted on the pressure plate (1) to a load cell (3), the load cell (3) being coupled to the pressure transmitting assembly (2), the load cell (3) being further coupled to a data logger (7), the data logger (7) being configured to receive and execute data from the load cell (3).
2. The system as claimed in claim 1, wherein the pressure transmitting assembly (2) comprising:
a long slender hole (18,25) passing through the groove (19,24) and the wall (17,21);
a first flanged bush (8a) being deployed over the groove (19,24) end of the long slender hole (18,25) and a second flanged bush (8b) being deployed over an outer end of the fixed wall (15,20); and
a pressure rod (9) being attached to the pressure plate (1) and a ball bearing assembly (11,12,13) being deployed between the first bush (8a) and the pressure rod (9) and the second bush (8b) and the pressure rod (9).
3. The system as claimed in claim 2, wherein the pressure rod (9) being made up of zirconia.
4. The system as claimed in claim 2, wherein the first flanged bush (8a) and the second flanged bush (8b) being made up of zirconia.
5. The system (19) as claimed in claim 1, wherein the groove (19,24) is cuboidal in shape.
6. The system (24) as claimed in claim 1, wherein the groove (19,24) is circular in shape.
, Description:A SYSTEM FOR MEASURING WALL PRESSURE IN COKE OVEN FURNACE
FIELD OF INVENTION
[001] The present invention relates to the field of coke making, and more specifically relates to the laboratory and pilot scale coke ovens.

BACKGROUND OF THE INVENTION

[002] For producing pig iron in blast furnaces, coke is utilized as a major fuel and reducing agent. The coke making process accounts for majority of the costs involved in a steel plant. Thus, driving various research activities for cost reduction either coal or process research. In coke making process, coal is being converted into coke which is highly porous strong structure with almost 90% of carbon. The coke making process can be written broadly into the following steps-
- Coal sourcing/ Coal beneficiation
- Coal blending
- Coal crushing
- Coal Charging in the oven
- Heating of coal mass in the absence of air
- Pushing and collection of coke
- Quenching the hot coke produced
- Transport to blast furnace for use

[003] The carbonization/ coke making process is done by using the unidirectionally heated coke oven. For larger production needs, the ovens are arranged in series to form coke oven batteries. The coal is charged in these furnaces and heated under the absence of air till the complete mass reaches the temperatures of 1050 deg C. The processing time for coal to coke conversion is termed as coking time. As the coal mass is heated, it starts to release moisture till 150 deg C. Soon as the temperature reaches the temperature of 350 deg C, volatile matter start coming out of the mass. It is at this stage the coal gets into plastic state and re-solidifies around the temperatures of 600 deg C. Since the heating of the coal mass is done unidirectionally, above mentioned process happens in subsequent layers till the thermal front reaches the central layer.

[004] The plastic state of the coal and the generation of the gas creates the expansion of the coal cake or coal mass. These gases also escape the mass from the sides of the coke mass. The gases leaving the cake along with the expansion of the cake gives rise to the swelling pressure. The wall pressure is defined as the pressure experienced by the coke oven walls in order to resist the swelling pressure. The coking pressure is a very important factor for development of coke strength.

[005] But the wall pressure, if in excess, can deflect refractory walls causing serious damage to the coke oven batteries. In other words, the controlled nature of wall pressure is essential for the better operation and longer health of the battery. Cost variations and the availability of same coals leads to change of coal blend proportions. The estimation of the wall pressure data is very important for blend design in order to keep good battery health. Though various characterization techniques are used for designing the coal blend but large-scale interactions can be well understood by measuring the wall pressure data in the laboratory or pilot scale coke ovens.

PRIOR ART

[006] Measurement of the wall pressure in the commercial plant is not possible. Some indirect methods are deployed to make an estimate of the expansion of the cake by the use of buckstay spring which cannot be directly linked as wall pressure. Special furnaces are required for the direct measurement of the wall pressure of the coke oven. These ovens are called moving wall furnaces. The moving wall furnaces come at a variety of sizes which are essentially heated by electrode. The moving wall furnace has one fixed and one moving wall which is supported by springs from the outside and maintained on a smooth surface for load detection. The moving wall attached to a load cell for pressure measurement.

[007] The two most followed design for the moving wall sliding mechanism are-
- Moving wall mounted on a car which can move on rails
- Moving wall suspended with the help of the pulleys

[008] Pressure measurement in a moving wall furnace- As the coal mass is heated due to coal swelling and gas generation the moving wall slides by some distance. The translation of the moving wall is due to the force transferred to the moving wall. This force/ pressure is recorded by the load cell in a dynamic manner to give a pressure profile.

[009] The major problems with the moving wall furnaces are as follows-
- High cost of the moving wall furnaces- due to the requirement of mechanization and the criticality of the components, the lab scale moving wall furnaces are generally high in cost compared to the non-moving wall type furnaces.
- Heating Mechanism- all moving wall furnaces are electrically heated. Moving wall furnaces which are gas fired cannot be constructed due to safety concerns. Though electrically heated ovens map a correlation with the plant scale but are incapable of producing similar results and test parameters as the gas fired ovens.
- Improper sealing- Since one of the wall has one degree of freedom for translation. This needs clearance between the fixed and movable parts of the furnace. This clearance indeed is the reason for the gas leakage in the movable wall furnaces. The sealants used to restrict the gas flow fail due to high temperature and impurities present in the raw coke oven gas.
- High capacity moving wall furnaces- Most commercial available moving wall furnaces come in the sizes of 200kg-300kg coke capacity. The tests thus become more expensive and also increases the test time.
- Low capacity moving wall furnaces- Low capacity unconventional type moving wall furnaces require extreme control over the friction in the moving wall mechanism due to lower magnitudes of force generated by lower coal mass. This creates lot of errors in the pressure measurement.

[0010] The need is to develop a mechanism for measuring the coking pressure and at the same time avoiding all the limitations present in the moving wall furnaces.

[0011] Chinese Patent Publication CN202881174 provides - The utility model discloses a seal type environment-friendly type testing coke furnace for measuring 40 kg coking coal swelling pressure. The seal type environment-friendly type testing coke furnace is characterized by comprising a fixed furnace wall, a moving furnace wall, a frame, a sealing system, a raw gas processing system, a coke furnace heating system, an expansive pressure acquisition system, and a briquette longitudinal expansion and shrinkage degree measuring system, wherein a fixed wall is fixed on the bottom of the frame, and a moving wall is installed on a sliding trolley; the sliding trolley is connected with the bottom of the frame in a sliding way, and the fixed wall is connected with the moving wall by the sealing system; and the raw gas processing device is installed on the top of the frame. The seal type environment-friendly type testing coke furnace provided by the utility model has the advantages of being capable of measuring dynamic variation of coking coal expansive pressure and dynamic variation of briquette longitudinal expansion and shrinkage, and being accurate for measuring expansion pressure, tight in furnace body structure, convenient in coke making, long in service life, and suitable for a bulk density condition of a top coaling coke furnace and different cola materials of a tamping coke furnace.

[0012] Korean Patent Publication KR100399235 provides - PURPOSE: A method for measuring force applied to an oven wall when carbonizing in a cokes test furnace is provided to prevent damage of the oven wall by accurately measuring force applied to the oven wall and stabilize an oven work by preventing extrusion resistance. CONSTITUTION: A method for measuring force applied to an oven wall when carbonizing in a cokes test furnace includes the steps of preparing the test furnace under the equal condition of an actual cokes oven by installing a movable wall(5) forming one side wall of an oven, connecting a rope(9) with the center part of the movable wall to change the external force applied to the movable wall, connecting the rope to a counterweight(11), installing a plurality of load cells(6) on one side of the movable wall; measuring actual volume of the external force measured at the load cells with continuously changing only the weight of the counterweight under the equal conditions to make database; calculating the difference between change of actual external applied to the movable force and the applied external force, and making the difference database as resistance loss value of the movable wall; and measuring volume of expansive pressure at each load cell when expansive pressure is generated in carbonizing in the test furnace based on the databased actual external force and resistance loss value, and compensating the resistance loss value.

[0013] Chinese Patent Publication CN104807817 provides - The invention provides an apparatus and method for detecting characteristics of coal in coking process in a coke oven. The apparatus comprises a coal heating system and a characteristics detection system; the heating system comprises a heating furnace; a high temperature furnace tube is in the heating furnace; one end of the high temperature furnace tube is provided with an observation window; a sample substrate is arranged in a constant-temperature area of the high temperature furnace tube; a sample box is arranged above the substrate; a temperature measurement end of a temperature thermocouple contacts with the sample substrate, and the measurement value is output to a temperature control device of the heating furnace; and the characteristics detection system comprises an expansion pressure gauge connected with sample box, and also includes a camera for photographing on one end of the coal heating system and a computer for recording and calculations. The apparatus and method for detecting characteristics of coal in coking process in the coke oven can observe the changes taking place in the coking process, and have certain guiding effect for the temperature control in coking process, coke quality control in coal pyrolysis coking process and the control of colloid formation volume.

[0014] Chinese Patent Publication CN105203583 provides - The invention discloses a device for testing a coal pyrolysis coking process. The device comprises a furnace with a rectangular furnace bottom, vertical sidewalls and an arched top, and is characterized in that the front and left sidewalls of the furnace are furnace walls, the right and rear sidewalls of the furnace are quartz glass sidewalls, the right quartz glass sidewall is a mobilizable quartz glass sidewall (11) which is arranged on a slide rail and can move forward and backward, and the top of the furnace forms a sight hole (5). According to the device and method, process characteristics can be reproduced by real-time image acquisition and process visualization is realized so that coal coking expansion can be observed visually and vividly and coal expansion process pressure is obtained and thus understanding of coal expansion characteristics and coal coke form change in coal heating coking is improved.

OBJECTIVE
[0015] The primary objectives of the present invention are to: To measure coke oven pressure in a lab scale and pilot scale, electrically or gas fired coke ovens; To ensure battery health monitoring and improvement; Coal blend optimization; Hot metal cost reduction.

SUMMARY OF THE INVENTION

[0016] The present disclosure relates to a system (100) for measuring coking pressure at a fixed wall (6) of a lab/pilot scale coke oven, the system (100) includes a groove (19,24) provided over a heating side of the fixed wall (17,21); a pressure plate (1) being freely suspended over the groove (19,24) to realize a pressure exerted from a heated coking coal; and a pressure transmitting assembly (2) coupled to the pressure plate (1) to transmit pressure exerted on the pressure plate (1) to a load cell (3), the load cell (3) being coupled to the pressure transmitting assembly (2), the load cell (3) being further coupled to a data logger (7), the data logger (7) being configured to receive and execute data from the load cell (3).

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0017] Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings of the exemplary embodiments and wherein:
Fig. 1: a general assembly of a system (100) for measuring coking pressure at a fixed wall (6) of a lab/pilot scale coke oven in accordance with an embodiment of the present disclosure
Figs. 2a and 2b: respectively provides an isometric view and a side view associated with a general assembly of the pressure plate (1) and the pressure transmitting assembly (2) in accordance with an embodiment of the present disclosure
Fig 3: an isometric view of the pressure transmitting rod (9)
Fig 4: an exploded view of the system (100) showing various components in accordance with an embodiment of the present disclosure
Fig 5,6,7: respectively illustrates enlarged views of the flanged bush (8), the linear bushing (11), and the O-ring (13) as shown in Fig. 4
Fig. 8a: illustrates a traditional arrangement of Electrically heated small fixed wall type coke oven
Fig. 8b: illustrates a core modification for pressure measurement setup associated with the system (100) for Electrically heated small fixed wall type coke oven in accordance with an embodiment of the present disclosure
Fig. 9a: illustrates a traditional arrangement of Gas heated pilot scale fixed wall type coke oven
Fig. 9b: illustrates a core modification for pressure measurement setup associated with the system (100) for Gas heated pilot scale fixed wall type coke oven in accordance with an embodiment of the present disclosure

[0018] The figure(s) depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

[0019] The present invention, now be described more specifically with reference to the following specification.

[0020] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.

[0021] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.

[0022] Fig. 1 illustrates a general assembly of a system (100) for measuring coking pressure at a fixed wall (6) of a lab/pilot scale coke oven in accordance with an embodiment of the present disclosure.

[0023] In an example, Reference will be made to the following components associated with the system (100) in the foregoing description and figures –

S. No Name
1 Pressure Plate
2 Pressure transmitting assembly
3 Load cell
4 coke oven fixed wall
5 coal mass in the coke oven
6 coke oven fixed wall
7 Data acquisition system
8 Flanged Bush (8a, 8b)
9 Pressure rod
10 Grooves for O rings
11 Linear Bearing
12 Bearing Ball
13 O-ring
14 heating element zone
15 Outer Wall of electrical furnace
16 Coke chamber
17 Heating wall of electrically heated furnace
18 Hole for pressure rod
19 Groove for pressure plate
20 Outer wall of gas fired oven
21 Heating wall of the gas fired oven
22 Combustion chamber slots
23 Bricks between the combustion chambers
24 Grooves for pressure plate in gas fired oven
25 Holes for pressure rod in gas fired oven

[0024] Figs. 2a and 2b respectively provides an isometric view and a side view associated with a general assembly of the pressure plate (1) and the pressure transmitting assembly (2) in accordance with an embodiment of the present disclosure.
[0025] Fig. 3 illustrates an isometric view of the pressure transmitting rod (9). As shown, the pressure transmitting rod (9) includes a plurality of grooves (10) for O-rings. Fig. 4 illustrates an exploded view of the system (100) showing various components in accordance with an embodiment of the present disclosure. As shown, the system (100) further includes a plurality of flanged bushes (8a, 8b); the pressure transmitting rod (9) with the plurality of grooves (10) for O-rings; a linear bushing (11); bearing ball (12); and the O-rings (13).

[0026] Figs. 5, 6, and 7 respectively illustrates enlarged views of the flanged bush (8), the linear bushing (11), and the O-ring (13) as shown in Fig. 4.

[0027] Fig. 8a illustrates a traditional arrangement of Electrically heated small fixed wall type coke oven. As shown, the traditional arrangement includes heating element zone (14), outer wall of electrical furnace (15), and coke chamber (16). Fig. 8b illustrates a core modification for pressure measurement setup associated with the system (100) for Electrically heated small fixed wall type coke oven in accordance with an embodiment of the present disclosure. The pressure measurement setup provides Heating wall of electrically heated furnace (17), Hole (18) for the pressure rod (9), and Groove (19) for the pressure plate (1).

[0028] Fig. 9a illustrates a traditional arrangement of Gas heated pilot scale fixed wall type coke oven. As shown, the traditional arrangement includes the coke chamber (16), Outer wall of gas fired oven (20), Heating wall of the gas fired oven (21), Combustion chamber slots (22), and Bricks between the combustion chambers (23). Fig. 9b illustrates a core modification for pressure measurement setup associated with the system (100) for Gas heated pilot scale fixed wall type coke oven in accordance with an embodiment of the present disclosure. The pressure measurement setup provides Heating wall of the gas fired oven (21), Grooves (24) for the pressure plate (1) in gas fired oven, and Holes (25) for the pressure rod (8) in gas fired oven.

[0029] The presented invention provides a mechanism which can measure coking pressure or wall pressure inside a coke oven without the use of a moving wall furnace. Despite of using a moving wall furnace, in the present invention a portion of the fixed wall (4, 6) is stimulated as moving which transmits the load from the oven to the load cell (3) outside, which ultimately records the pressure. The system (100) comprises of three main components - Pressure plate (1), Pressure transmitting assembly (2), Load cell (3).

[0030] During the carbonization process the gases and the swelling start exerting the pressure on to the walls (4, 6) of the furnace. The pressure is opposed by the fixed nature of the wall (4,6) by an opposite reaction force. The present invention allows to transmit this pressure by letting the pressure transmit to the load cell (3) which is outside the furnace. In the present invention, a portion of the wall (4, 6) is replaced by the pressure plate (1) which has been provided translational degree of freedom. This in general makes that portion of the wall (4, 6) as moving wall.

[0031] The pressure plate (1) is a zirconium oxide plate which aligns with the heating wall surface. The alignment is facilitated by making groove (19) on the surface of the wall (4, 6). The groove depth is selected according to the thickness of the wall (4, 6). The provision of the groove (19) in the wall (4, 6) is important since it allows space for the pressure plate (1) to displace a small amount which is essential for the load cell (3) measurement. The pressure plate (1) is attached to a transmitting assembly (2). The transmitting assembly (2) is low friction section which allows the pressure to transmit to the load cell (3) with minimal resistance. The transmitting assembly (2) consists of a pressure rod (9) which slides on to a ceramic sleeve (8) with the help of a ceramic bearing (11) & balls. Solid lubrication preferably graphite is used for reducing the friction to a lower value. The transmitting assembly (2) is inserted into a furnace with the help of holes (17,24). Bearings are designed to support the load and to the maintain the alignment of the pressure rod even at higher temperatures.

[0032] The load cell (3) is selected with appropriate sensitivity to measure the pressure generated in the oven. The generated signals from the load cell (3) are then recorded in a data logging device (7) for display and post processing. The system (100) is provided with a general cleaning system which cleans any residual gas or tars between the pressure plate (1) and the groove (19) in the wall (4, 6). The cleaning system has a nozzle mounted on a flexible hose which uses pressurized nitrogen to clean the gap. The transmitting assembly (2) can be easily removed and reinserted during no load conditions of the oven. The flexibility of the system (100) thus facilitates in better maintenance and installations.

[0033] The system (100) can be deployed to either an electrically heated oven and to a gas heated oven. The complete assembly of the device essentially remains the same with adjustment in the length of the pressure rod (9). As shown in Figs. 8a-8b & Figs. 9a-9b., the system (100) can be installed in an electrically heated or a gas fired furnace by modifying the brick/ refractory. The modification in the refractory consists of two important steps. Firstly, making groove (19) on the heating wall (17,21): The groove (19) on the wall (17, 21) of the oven is a rectangular groove of 15mm-20mm depth. The cross section for this groove (19) is +2mm higher than the pressure plate (1) on each side. For a smaller size oven like 7kg, 25kg or 40 kg carbonization furnace a single pressure plate (1) is sufficient. For the ovens with higher size which are generally gas fired type, the selection of the groove (19) positioning is important. The grooves (19) in the gas fired furnace are carefully placed on the walls (17, 21) which are besides the direct combustion chamber zone. Two combustion chambers (22) are separated by bricks (23), these bricks (23) provide the strategic positions for the groove (19). Many such plates can be installed depending on the capacity of the furnace and the type of bricks (23).

[0034] Secondly, making holes through the refractory (18,25): The hole should be through all the surfaces behind the groove (17,21). The hole should be of at least 3 mm higher diameter than the pressure rod. The flanged bush (8) is installed on the front and back end of the hole. The O-rings (13) support and hold the bearing (11) with balls (12). After positioning the bearings (11) and the O-rings (13), the rod (9) is inserted through the hole such that the bearings (11) align inside the flanged bush (8). The slots (10) on the pressure rod (9) are machined according to the thickness of the oven wall to ensure the bearings (11) land inside the bush (8). To prevent the gas movement in the bush (8) a wool cloth cut to diameter of the bush (8) is covered on to the pressure rod (9). The pressure rod (9) is connected to the pressure plate (1) and the pressure plate (1) is aligned to the oven wall surface. This is the zero position of the device. A load cell (3) is mounted on the back of the pressure rod (9) outside of the oven. The load cell (3) structure mounting is so constructed so that the measuring surface of the load cell (3) just touches the pressure rod (9) end. The load cell (3) is calibrated in this position. When coal mass is heated, coking pressure is created crated and tries to push the pressure plate (1). The pressure plate (1) transmits the load to the pressure rod (9) which transmits the load to the load cell (3).

[0035] Present invention takes into account all the limitations and provides a solution which can be retrofitted to any size fixed wall oven even to gas fired furnaces. Present invention does not require a complete wall to be moved and offers a solution to measure multipoint pressure measurement system. The invention offers a low-cost system which simulates only a portion of the wall as moving and records pressure. Due to the smaller size and the construction of the device, the gas leakage is limited to a minimum.

[0036] It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims.