Claims:1. A method for determining temperature distribution profiles of a twin shaft regenerative kiln (103) for calcination process, the method comprising:
receiving, by a temperature determination system (101), a plurality of input data of the twin shaft regenerative kiln (103), wherein the plurality of input data comprises fuel flow rate, fuel calorific values, cooling air flow rate, combustion air flow rate and limestone charging rate;
forming, by the temperature determination system (101), a plurality of grids for each of the twin shafts;
identifying, by the temperature determination system (101), at an instant, total output mass of solid and gases passing through each of the plurality of grids, based on the plurality of input data and the output data; and
determining, by the temperature determination system (101), a temperature profile for each of the twin shafts based on the total output mass of solid and gases identified at respective plurality of grids.

2. The method as claimed in claim 1, wherein the plurality of input data of the twin shaft regenerative kiln (103) further comprises limestone discharging rate, operating mode, and selected calcination cycle time.

3. The method as claimed in claim 1, wherein the twin shafts operate in an alternative interval of firing mode and a non-firing mode.

4. The method ad claimed in claim 2, wherein in the non-firing mode, total output mass of solid and gases passing through each of the plurality of grids is identified based on cooling air flow rate along with rate of fuel gas passing through a shaft operating in the firing mode.

5. The method as claimed in claim 1, wherein forming the plurality of grids comprises determining size of each grid based on period of time required for volumetric flow rate of solid through a predefined cross-sectional area of twin shafts.

6. The method as claimed in claim 5, wherein the determined size of each grid is within 0.5 meters for a calculation time period of one minute.

7. The method as claimed in claim 1 further comprising determining degree of conversation from lime to limestone using total output mass of solid and gases passing through each of the plurality of grids based on the plurality of input data and the output data.

8. The method as claimed in claim 1 further comprising detecting a connection between the twin shafts (103) through a crossover channel on identifying input data to be received from a predefined grid along with a cooling air flow rate.

9. The method as claimed in claim 1, wherein the temperature profile for each of the twin shafts is determined using a predefined temperature profile model (205).

10. The method as claimed in claim 1 further comprising displaying the determined temperature profile for the twin shafts using a Human Machine Interface (HMI) display.

11. A temperature determination system (101) for determining temperature distribution profiles of a twin shaft regenerative kiln (103), the temperature determination system (101) comprising:
a processor (115); and
a memory (113) communicatively coupled to the processor (115), wherein the memory (113) stores processor instructions, which, on execution, causes the processor (115) to:
receive a plurality of input data of the twin shaft regenerative kiln (103), wherein the plurality of input data comprises fuel flow rate, fuel calorific values, cooling air flow rate, combustion air flow rate, limestone charging rate, limestone discharging rate, operating mode, and selected calcination cycle time;
form a plurality of grids for each of the twin shafts;
identify at an instant, total output mass of solid and gases passing through each of the plurality of grids, based on the plurality of input data and the output data; and
determine a temperature profile for each of the twin shafts based on the total output mass of solid and gases identified at respective plurality of grids.

12. The temperature determination system (101) as claimed in claim 11, wherein the twin shaft operates in an alternative interval of firing mode and a non-firing mode.

13. The temperature determination system (101) as claimed in claim 12, wherein in the non-firing mode, the processor identifies a total output mass of solid and gases passing through each of the plurality of grids based on cooling air flow rate along with rate of fuel gas passing through the shaft operating in firing mode.

14. The temperature determination system (101) as claimed in claim 11, wherein the processor determines degree of conversation from lime to limestone conversation from lime to limestone using total output mass of solid and gases passing through each of the plurality of grids based on the plurality of input data and the output data.

15. The temperature determination system (101) as claimed in claim 11, wherein the processor detects a connection between both the twin shafts through a crossover channel on identifying input data to be received from a predefined grid along with a cooling air flow rate.

16. The temperature determination system (101) as claimed in claim 11, wherein the processor determines the temperature profile for each of the twin shafts using a predefined temperature profile model (205).

17. The temperature determination system (101) as claimed in claim 11, wherein the processor (115) displays the determined temperature profile for the twin shafts using a Human Machine Interface (HMI) display.
, Description:TECHNICAL FIELD
The present subject matter relates generally to a field of process control in an industrial production environment, and specifically to calcination process. Particularly, but not exclusively the disclosure relates to a method and system for determining temperature distribution profiles of a twin shaft regenerative kiln for calcination process.
BACKGROUND
Limestone is found widely throughout the world and is essential raw material for many industries. Thermal dissociation is most important characteristics of limestone. All limestone rocks dissociate at high temperatures forming oxides and carbon dioxide gas is an endothermic reaction. Typically, dissociation temperature of commercially attractive limestones starts at about 810 0C with surface calcination and completed at about 920 0C at a partial CO2 pressure of 100 kPa. In order to produce 1 kg of lime, approximately 3180 kJ of energy are required.
Shaft kilns are widely used for the production of lime. For the purpose of process optimization and regulation (producing desired lime quality), the temperature burning profiles in the kilns must be known. However, practical measurements of these parameters are exceedingly difficult due to the movements of solid and high temperatures in the kilns. There are distinct types of shaft kilns. One such shaft kiln for calcination process is, a PFR (parallel flow regenerative shaft kiln) which consists of two vertical shafts and a connecting by crossover channel. Both the shaft of kiln operates in cycles, where fuel flow burning takes place in one shaft during a cycle called firing shaft and limestone charge gets preheated in the other shaft which is working as recuperator called non-firing shaft. The shafts reverse their roles in next cycle. Both the shaft operates parallelly where the limestone in the first shaft is heated by direct fuel flow burning and flue gasses pass to second shaft through a cross over channel.
Currently, the shaft kilns in the industrial plants work on Standard Operating Practice (SOP) which was provided by suppliers. But nowadays the operation process of the shaft kilns has evolved. To optimize the process, it is required to know, what is happening inside the shaft kilns. Currently, temperature profiles of the shaft kilns are unknown and the only temperature which is available is a temperature at the crossover channel between the shafts by help of a thermocouple. To solve this problem, the temperature profile of both the shafts are required at regular intervals of switch-over of firing to non-firing mode.
Computer modelling has grown over years into a scientific discipline on its own. Models are utilized to assess real-world phenomena which may be too complex to be analysed in laboratory or under hypotheses at a fraction of cost of undertaking actual activities. Models in industry shorten design cycles, reduce costs, and enhance knowledge. Currently, there exist many systems which use different models for determining temperature profile in calcination process. However, most of these systems and models are applicable and convenient for furnace where only solid fuel-based calcination occurs, and these systems may not be applicable for gases fuel-based calcination furnaces. Also, the existing systems consider spherical shaped solid particle, where such consideration is well suitable for determining ideal case calcination front of limestone only but may never be suitable for actual determination calcination of limestone. While some other existing approach focuses on kinetic reaction parameters development while calcination inside the kiln and lacks behind with temperature distribution of solid and gas inside the kiln.
The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the disclosure and should not be taken as an acknowledgement or any form of suggestion that this information forms prior art already known to a person skilled in the art.
SUMMARY
One or more shortcomings of the prior art may be overcome, and additional advantages may be provided through the present disclosure. Additional features and advantages may be realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In a non-limiting embodiment of the disclosure, a method for determining temperature distribution profiles of a twin shaft regenerative kiln for calcination process is disclosed. The method includes receiving a plurality of input data of the twin shaft regenerative kiln. The plurality of input data comprises fuel flow rate, fuel calorific values, cooling air flow rate, combustion air flow rate and limestone charging rate. The method includes forming a plurality of grids for each of the twin shafts and identifying at an instant, total output mass of solid and gases passing through each of the plurality of grids, based on the plurality of input data and the output data. Thereafter, the method includes determining a temperature profile for each of the twin shafts based on the total output mass of solid and gases identified at respective plurality of grids.

In an embodiment of the disclosure, the plurality of input data of the twin shaft regenerative kiln further comprises limestone discharging rate, operating mode, and selected calcination cycle time.

In an embodiment of the disclosure, the twin shafts operate in an alternative interval of firing mode and a non-firing mode.

In an embodiment of the disclosure, in the non-firing mode, the total output mass of solid and gases passing through each of the plurality of grids is identified based on cooling air flow rate along with rate of fuel gas passing through a shaft operating in the firing mode.

In an embodiment of the disclosure, forming the plurality of grids comprises determining size of each grid based on period of time required for volumetric flow rate of solid through a predefined cross-sectional area of twin shafts.

In an embodiment of the disclosure, the determined size of each grid is within 0.5 meters for a calculation time period of one minute.

In an embodiment of the disclosure, the degree of conversation from lime to limestone is determined using total output mass of solid and gases passing through each of the plurality of grids is based on the plurality of input data and the output data.

In an embodiment of the disclosure, a connection is detected between the twin shafts through a crossover channel on identifying input data to be received from a predefined grid along with a cooling air flow rate.

In an embodiment of the disclosure, the temperature profile for each of the twin shafts is determined using a predefined temperature profile model.

In an embodiment of the disclosure, the determined temperature profile is displayed for the twin shafts using a Human Machine Interface (HMI) display.

In one non-limiting embodiment of the disclosure, a temperature determination system for determining temperature distribution profiles of a twin shaft regenerative kiln for calcination process is disclosed. The temperature determination system comprises a processor and a memory communicatively coupled to the processor, where the memory stores processor executable instructions, which, on execution, may cause the temperature determination system to receive a plurality of input data of the twin shaft regenerative kiln. The plurality of input data comprises fuel flow rate, fuel calorific values, cooling air flow rate, combustion air flow rate and limestone charging rate. The temperature determination system forms a plurality of grids for each of the twin shafts and identifies at an instant, total output mass of solid and gases passing through each of the plurality of grids, based on the plurality of input data and the output data. Thereafter, the temperature determination system determines a temperature profile for each of the twin shafts based on the total output mass of solid and gases identified at respective plurality of grids.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DIAGRAMS

The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and/or methods in accordance with embodiments of the present subject matter are now described, by way of example only, and with reference to the accompanying figures, in which:

FIG.1 shows an exemplary embodiment for determining temperature distribution profiles of a twin shaft regenerative kiln for calcination process in accordance with some embodiments of the present disclosure;

FIG.2 shows a detailed block diagram of a temperature determination system in accordance with some embodiments of the present disclosure;
FIG.3 is a flowchart illustrating a method for determining temperature distribution profiles of a twin shaft regenerative kiln for calcination process in accordance with some embodiments of the present disclosure;

FIG.4A shows an exemplary graph showcasing determined temperature profiles of gas and solid inside the kiln shafts in accordance with some embodiments of the present disclosure;

FIG.4B shows an exemplary graph showcasing degree of conversion of limestone to lime in both kiln shafts in accordance with some embodiments of the present disclosure;

FIG.5A shows exemplary graphs showcasing predicted temperatures of lime and flue gas at exit of kiln and cross over channel in accordance with some embodiments of the present disclosure;
FIG.5B shows exemplary an HMI screen displaying results of temperature profile, degree of lime conversion, flue gas at cross over channel and exit, and lime for twin shaft lime kiln in accordance with some embodiments of the present disclosure; and
FIG.6 is a block diagram of an exemplary computer system for implementing embodiments consistent with the present disclosure.
It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present subject matter. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer readable medium and executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION

In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
The terms “comprises,” “comprising,” “includes” or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device, or method that includes a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or method.
Disclosed herein is a method and temperature determination system determining temperature distribution profiles of a twin shaft regenerative kiln for calcination process. Calcination process may refer to heating a solid to high temperatures in absence of air or oxygen. A typical calcination process involves conversion of calcium carbonate to calcium oxide. Calcium oxide, which is also known as burnt lime, is an important flux material used in steel making process. It is manufactured by heating limestone (Calcium Carbonate) in presence of oxygen in a kiln where limestone disassociates into lime and gaseous carbon dioxide. Typically, different types of kilns are used for this process such as, rotary kiln, shaft kiln, twin shaft, and the like.
Currently, the shaft kilns in the industrial plants work on Standard Operating Practice (SOP) which was provided by suppliers. But nowadays the operation process of the shaft kilns has evolved. To optimize the process it is required know, what is happening inside the shaft kilns. Currently, temperature profiles of the shaft kilns are unknown and the only temperature which is available is a temperature at the crossover channel between the shafts by help of a thermocouple. To solve this problem, the temperature profile of both the shafts are required at regular intervals of switch-over of firing to non-firing mode. One of the technique to determine the temperature profile at regular intervals is by using models. Currently, there exist many systems which utilise different models for determining temperature profile in calcination process. However, most of these systems and models are applicable and convenient for furnace where only solid fuel-based calcination occurs, and these systems may not be applicable for gases fuel-based calcination furnaces. Also, the existing systems consider spherical shaped solid particle, where such consideration is well suitable for determining ideal case calcination front of limestone only but may never be suitable for actual determination calcination of limestone. While some other existing approach focuses on kinetic reaction parameters development while calcination inside the kiln and lacks behind with temperature distribution of solid and gas inside the kiln.
Therefore, to solve the above problem, the present disclosure determines the temperature profile of solid and gas inside the twin shafts kiln by forming a plurality of grids in each shaft and identifying total output mass of solid and gases passing through each of the plurality of grids using a first principle model. Particularly for real time set point management, the temperature profiles of solid and gas along with degree of lime conversion inside the twin shaft kiln are determined under current operating conditions of input raw material, production rate and fuel properties. Thus, the present disclosure enables real-time set point management for the twin shaft kiln operation and dynamically adopts to operating conditions compared to a scenario wherein a standard operating practice is used. As a result, the temperature profile and degree of conversion helps an operator of industrial plant to manage input parameters for complete calcination thereby optimizing ongoing process.

In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

FIG.1 shows an exemplary embodiment for determining temperature distribution profiles of a twin shaft regenerative kiln for calcination process in accordance with some embodiments of the present disclosure.

FIG.1 shows an environment 100 which includes a temperature determination system 101 connected to a twin shaft regenerative kiln 103 (also referred as twin shaft kiln 103) in an industrial plant through a communication interface 107 and a Programmable Logic Interface (PLI) 109. The industrial plant may be associated with any industry which utilizes the twin shaft kiln 103 such as, steel industry and the like. The communication interface 107 may be an Open Platform Communication (OPC) interface.
The twin shaft kiln 103 may carry out calcination process, in which limestone (which is calcium carbonate) is heated in presence of oxygen, where the limestone disassociates into lime and gaseous carbon dioxide. As shown in Fig.1, the twin shaft kiln 103 consists of two vertical shafts and a connecting by crossover channel. Both the shaft of kiln operates in alternative cycles, where fuel flow burning takes place in one shaft during a cycle called firing shaft and limestone charged preheated in the other shaft which is working as recuperator called non-firing shaft. Both the shafts of twin shaft kiln 103 operate parallelly where the limestone in the first shaft is heated by direct fuel flow burning and flue gasses are passing to second shaft through the cross over channel. Hot flue gasses from first shaft exit from top of second shaft as shown in Fig.1. Further, each shaft of twin shaft kiln 103 is divided into three zones from top to bottom, i.e., preheating zone, combustion zone and cooling zone. The limestone is charged from the top of both the shafts and pre-heated in top one. After preheating, the limestone enters the combustion zone of the shaft in which fuel burning occur and is heated up to temperature at which calcination reaction takes place. The limestone entering the combustion zone of other shaft are preheated and some of limestones get calcined. Calcined solid product is cooled by passing cooling air at room temperature from bottom. The cooling air and combustion gas products are passed through the cross over channel.

The temperature determination system 101 may receive a plurality of input data of the twin shaft kiln 103 through the PLI 109. In some embodiments, the temperature determination system 101 may be configured in a remote location. In some other embodiments, the temperature determination system 101 may be locally configured. The temperature determination system 101 may include an Input/Output (I/O) interface 111, a memory 113 and a processor 115 as shown in the FIG.1. The I/O interface 111 may receive the plurality of input data of the twin shaft kiln 103 in operation. The temperature determination system 101 may be connected with a database 105, which is used for storing the details and plurality of input data of the twin shaft kiln 103.
In an embodiment, the temperature determination system 101 may include a Human Machine Interface (HMI) (not shown explicitly in FIG.1) to provide a visual indication. As an example, the HMI may display the temperature profile of the twin shaft kiln 103 to operators and the like. In an embodiment, the temperature determination system 101 may be any computing device such as, desktop computer, server, and the like.

The plurality of inputs data may be recorded by the PLI 109 from the twin shaft kiln 103 which is in operation. The temperature determination system 101 receives the plurality of input data through the interface of the communication interface 107 and the PLI 109. The plurality of input data may include fuel flow rate, fuel calorific values, cooling air flow rate, combustion air flow rate and limestone charging rate, limestone discharging rate, operating mode, and selected calcination cycle time. In an embodiment, input data capturing cycle may be defined for a predefined time period such as, ten seconds.
On receiving the plurality of input data, the temperature determination system 101 may form a plurality of grids for each of the shaft of the twin shaft kiln 103. In an embodiment, the twin shaft kiln 103 is cylindrical in shape and to form the plurality of grids, the twin shaft kiln 103 is discretised horizontally along height of twin shaft kiln 103 into the plurality of rectangular grids. The plurality of grids is determined by determining size of each grid based on period of time required for volumetric flow rate of solid through a predefined cross-sectional area of associated shaft. In an embodiment, the determined size of each grid may be within 0.5 meters for a calculation time period of one minute.
Further, the temperature determination system 101 identifies at an instant, total output mass of solid and gases passing through each of the plurality of grids, based on the plurality of input data and the output data. In an embodiment, the solid may be the limestone and lime and the gases may be multiple fuel gases used during burning. Typically, output of heat and mass balance for gases and solids in a first grid of the plurality of grids of the shaft operating in firing mode is used as input for subsequent grids in the shaft. Once the input data is received from a predefined grid along with a cooling air flow rate, the temperature determination system 101 detects a connection between the twin shaft through the crossover channel. For instance, the predefined grid is the grid which is located near the crossover channel. On detecting the connection, the temperature determination system 101 identifies the total output mass of solid and gases passing through each of the plurality of grids in the non-firing shaft of the twin shaft kiln 103 based on the cooling air flow rate along with rate of fuel gas passing through the shaft operating in the firing mode. Thereafter, the temperature determination system 101 determines the temperature profile for each of the twin shafts based on the total output mass of solid and gases identified at respective plurality of grids by using a predefined temperature profile model (as shown in Fig.2). Further, the temperature determination system 101 determines degree of conversation from lime to limestone using total output mass of solid and gases passing through each of the plurality of grids based on the plurality of input data and the output data. The determined temperature profile for the twin shaft kiln 103 is displayed to the operator using the HMI display.
A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary a variety of optional components are described to illustrate the wide variety of possible embodiments of the invention.

FIG.2 shows a detailed block diagram of a temperature determination system in accordance with some embodiments of the present disclosure.

In some implementations, the temperature determination system 101 may include data 200 and modules 213. As an example, the data 200 is stored in the memory 113 associated with the temperature determination system 101. In some embodiments, the data 200 may include input data 201, grid data 203, temperature profile model 205, temperature data 207 and other data 209. In some embodiments, the data 200 may be stored in the memory 113 in form of various data structures.

The input data 201 may include the plurality of input data from the twin shaft kiln 103 while performing calcination process for obtaining the lime. In an embodiment, the plurality of input data may be received for every predefined time, for example, at every ten seconds. The plurality of input data includes fuel flow rate, fuel calorific values, cooling air flow rate, combustion air flow rate and limestone charging rate, limestone discharging rate, operating mode, and selected calcination cycle time.

The grid data 203 may include details about the size of each grid associated with the twin shaft kiln 103. The grid data 203 may include information about volumetric flow rate of the solid through the predefined cross-sectional area of twin shafts. Further, the grid data 203 may include the total output mass of solid and gases passing through each of the plurality of grids of each shaft of the twin shaft kiln 103.

The temperature profile model 205 includes a predefined model used for identifying the temperature profile of the twin shaft kiln 103. In an embodiment, the temperature profile model 205 is a first principal model and utilizes finite difference technique.

The temperature data 207 may include the temperature profile determined for each shaft of the twin shaft kiln 103. The temperature data 207 also include details about the degree of conversation from lime to limestone.

The other data 209 may be stored data, including temporary data and temporary files, generated by the modules 213 for performing the various functions of the temperature determination system 101.

In an embodiment, the data 200 in the memory 113 are processed by the one or more modules 213 present within the memory 113 of the temperature determination system 101. In an embodiment, the one or more modules 213 may be implemented as dedicated units. As used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a field-programmable gate arrays (FPGA), Programmable System-on-Chip (PSoC), a combinational logic circuit, and/or other suitable components that provide the described functionality. In some implementations, the one or more modules 213 may be communicatively coupled to the processor 115 for performing one or more functions of the temperature determination system 101. The said modules 213 when configured with the functionality defined in the present disclosure will result in a novel hardware.

In one implementation, the one or more modules 213 may include, but are not limited to a receiving module 215, a grid formation module 217, an identification module 219 and a temperature profile determination module 221. The one or more modules 213 may also include other modules 223 to perform various miscellaneous functionalities of the temperature determination system 101.

The receiving module 215 may receive the plurality of input data from the twin shaft kiln 103 during calcination operation.

The grid formation module 217 may form the plurality of grids for each of the shaft of the twin shaft kiln 103. Particularly, the twin shaft kiln 103 is cylindrical in shape and to form the plurality of grids, the twin shaft kiln 103 is discretised horizontally along height of twin shaft kiln 103 into the plurality of rectangular grids. The grid formation module 217 determines the plurality of grids by determining size of each grid based on period of time required for volumetric flow rate of solid through the predefined cross-sectional area of associated shaft. In an embodiment, the determined size of each grid may be within 0.5 meters for a calculation time period of one minute.

The identification module 219 may identify at any instant the total output mass of solid and gases passing through each of the plurality of grids. Typically, output of heat and mass balance for gases and solids in a first grid of the plurality of grids of the shaft operating in firing mode is used as input for subsequent grids in the shaft. Once the input data is received from a predefined grid along with a cooling air flow rate, the identification module 219 may detect a connection between the twin shaft through the crossover channel. For instance, the predefined grid is the grid which is located near the crossover channel. On detecting the connection, the identification module 219 may identify the total output mass of solid and gases passing through each of the plurality of grids in the non-firing shaft of the twin shaft kiln 103 based on the cooling air flow rate along with rate of fuel gas passing through the shaft operating in the firing mode.

The temperature profile determination module 221 may determine the temperature profile for each of the twin shaft based on the total output mass of solid and gases identified at respective plurality of grids. The temperature profile determination module 221 utilises the temperature profile model 205 for determining the temperature profile at each shaft. The temperature profile may be determined based on below equations.

Conservation of mass of solid:
d/dt (?V)= Q_in ?_in- Q_out ?_out- R_g …………………………………………………. (1)
Discretized equation:
(V(?_i^(t+?t)-?_i^t))/?t= Q(?_(i-1)^(t+?t)- ?_i^(t+?t) )- R_g ………………………………………………….. (2)

Where, ‘Rg’is the rate of dissociation of Limestone:
R_g=K*?_(?CaCO3?_i)^t*V………………………………………………………………… (3)

Where,
?_(?CaCO3?_i)^t = Bulk density of limestone
K is the 1st order rate constant of dissociation of limestone = K0*Exp(-E/RT)
K0= Pre-exponential factor; E = activation energy (180 kJ/mole),
R = Universal gas constant (8.314 kJ/(K*mole))

Conservation of mass of gas:
d/dt(M_g)= ?_g^in- ?_g^out+ R_g……………………………………………………………. (4)
Discretized equation:
(?Mg?_i^(t+?t)- ?Mg?_i^t)/?t= ??g?_(i-1)^(t+?t)- ??g?_i^(t+?t)+ R_g ……………………………………………… (5)

Conservation of enthalpy of solid:
d/dt(?VTsC_s)= Q_in ?_in C_s T_in- Q_out ?_out C_s T_out+ Ah(T_g-T_s)- H_rxn…………… (6)
Discretized equation:
((V?_i^(t+?t) T_i^(t+?t) C_s- ?V??_i^t T_i^t C_s ))/?t
= ?_(i-1)^(t+?t) T_(i-1)^(t+?t) C_s Q- ?_i^(t+?t) T_i^(t+?t) C_s Q+ Ah(?Tg?_i^(t+?t)-?Ts?_i^(t+?t) )-H_rxn……………… (7)

Conservation of enthalpy of gas:
d/dt (MgC_g Tg)= ??g?_in ?Tg?_in C_g- ??g?_out ?Tg?_out C_g- Ah(Tg-Ts)+ Heat_source
(?(Mg?_i^(t+?t) C_g ?Tg?_i^(t+?t)- ?Mg?_i^t C_g ?Tg?_i^t))/?t= ??g?_(i-1)^(t+?t) ?Tg?_(i-1)^(t+?t) C_g- ??g?_i^(t+?t) ?Tg?_i^(t+?t) C_g- Ah(?Tg?_i^(t+?t)-?Ts?_i^(t+?t) )+Heat_source………………………………………………………… (8)
Heat_source = fuel flow rate (Qfuel) * Calorific value of fuel (CV)
Generally, lime kilns are packed bed reactors. The flow of hot gases flows co-currently and counter-currently with the solid in both the shafts. A void fraction may include a significant effect on the heat and mass transfer. The void fraction ? of a packed bed is defined using below equation.
?=(Bed volume - Packing volume)/(Bed volume) …………………………………………………… (9)
In an embodiment, for infinitely extended, regular packing of equally sized large spherical particles, the void fraction is ( ?) between 0.3 and 0.5 typically. For random packing of equally sized, large spheres, the void fraction is 0.4 - 0.42 for loose packing and 0.36 - 0.38 for dense packing.
A surface area required for the heat transfer depends on the particle size, shape, and void fraction. The fraction of charge that is packed in the shaft is calculated by using below equation.
(1- ?)= N* (p*D_p^3)/6………………………………………………………………………….. (10)
From the above equation, number of particles ‘N’ per unit volume of packed bed reactor and total bed surface area ‘A’ per unit volume is calculated as:
N=(6*(1-?))/(p D_p^3 ) and A=(6*(1-?))/D_p ……………………………………………. (11)
In an embodiment, the heat transfer in a shaft (packed bed) is dominated by convection. The convective heat transfer coefficient (h) in a packed bed is calculated from following correlation between Reynold number, Prandtl number, Nusselt number and void fraction.
?Nu?_bed= 2+1.12?Re?^(1/2) ?Pr?^(1/3) ((1-?)/?)^(1/2)+0.005Re…………………………………. (12)
Where,
Nubed = (h? * D?_p)/K_g , Re= (w * d)/(? * ?) and Pr=(? ? Cg)/K_g
FIG.4A shows an exemplary graph showcasing determined temperature profiles of gas and solid inside the kiln shafts in accordance with some embodiments of the present disclosure. FIG.5A show exemplary graphs showcasing predicted temperatures of lime and flue gas at exit of kiln and cross over channel in accordance with some embodiments of the present disclosure. Returning to FIG.2, the temperature profile determination module 221 may also determine the degree of conversation from lime to limestone using the total output mass of solid and gases passing through each of the plurality of grids based on the plurality of input data and the output data. FIG.4B shows an exemplary graph showcasing degree of conversion of limestone to lime in both kiln shafts in accordance with some embodiments of the present disclosure.

FIG.3 is a flowchart illustrating a method for determining temperature distribution profiles of a twin shaft regenerative kiln for calcination process in accordance with some embodiments of the present disclosure.

As illustrated in FIG.3, the method 300 comprises one or more blocks illustrating a method of determining temperature distribution profiles of a twin shaft regenerative kiln in accordance with some embodiments of the present disclosure. The method 300 may be described in the general context of computer-executable instructions. Generally, computer-executable instructions can include routines, programs, objects, components, data structures, procedures, modules, and functions, which perform functions or implement abstract data types.

The order in which the method 300 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method 300. Additionally, individual blocks may be deleted from the methods without departing from scope of the subject matter described herein. Furthermore, the method 300 can be implemented in any suitable hardware, software, firmware, or combination thereof.

At block 301, the method 300 may include receiving, by the receiving module 215, the plurality of input data of the twin shaft regenerative kiln. The plurality of input data includes, but not limited to, fuel flow rate, fuel calorific values, cooling air flow rate, combustion air flow rate and limestone charging rate.
At block 303, the method 300 may include forming, by the grid formation module 217, the plurality of grids for each of the twin shafts. The forming the plurality of grids comprises determining size of each of the grid based on the period of time required for volumetric flow rate of solid through the predefined cross-sectional area of twin shafts.

At block 305, the method 300 may include identifying, by the identification module 219, at any instant, the total output mass of solid and gases passing through each of the plurality of grids, based on the plurality of input data and the output data.

At block 305, the method 300 may include determining, by the temperature profile determination module 221, the temperature profile for each of the twin shafts based on the total output mass of solid and gases identified at respective plurality of grids. In view of the determination, the operator is provided with the temperature profile of each shaft of the twin shaft kiln 103 in the HMI display. FIG.5B shows exemplary an HMI screen displaying results of temperature profile, degree of lime conversion, flue gas at cross over channel and exit, and lime for twin shaft lime kiln in accordance with some embodiments of the present disclosure. As shown, the HMI display displays the determined gas and solid temperature profiles to the operator through an overview screen of the HMI.

FIG.6 is a block diagram of an exemplary computer system for implementing embodiments consistent with the present disclosure.
In some embodiments, FIG.6 illustrates a block diagram of an exemplary computer system 600 for implementing embodiments consistent with the present disclosure. In some embodiments, the computer system 600 can be the temperature determination system 101 that comprises a processor (also referred as a processor 602 in this FIG.6) that is used for determining temperature distribution profiles of a twin shaft regenerative kiln for calcination process.
The processor 602 may include at least one data processor for executing program components for executing user or system-generated business processes. The processor 602 may include specialized processing units such as integrated system (bus) controllers, memory management control units, floating point units, graphics processing units, digital signal processing units, etc.
The processor 602 may be disposed in communication with input devices 611 and output devices 612 via I/O interface 601. The I/O interface 601 may employ communication protocols/methods such as, without limitation, audio, analog, digital, stereo, IEEE-1394, serial bus, Universal Serial Bus (USB), infrared, PS/2, BNC, coaxial, component, composite, Digital Visual Interface (DVI), high-definition multimedia interface (HDMI), Radio Frequency (RF) antennas, S-Video, Video Graphics Array (VGA), IEEE 802.n /b/g/n/x, Bluetooth, cellular (e.g., Code-Division Multiple Access (CDMA), High-Speed Packet Access (HSPA+), Global System For Mobile Communications (GSM), Long-Term Evolution (LTE), WiMax, or the like), etc.
Using the I/O interface 601, computer system 600 may communicate with input devices 611 and output devices 612.
In some embodiments, the processor 602 may be disposed in communication with a communication network 609 via a network interface 603. The network interface 603 may communicate with the communication network 609. The network interface 603 may employ connection protocols including, without limitation, direct connect, Ethernet (e.g., twisted pair 10/100/1000 Base T), Transmission Control Protocol/Internet Protocol (TCP/IP), token ring, IEEE 802.11a/b/g/n/x, etc. Using the network interface 603 and the communication network 609, the computer system 600 may communicate with the twin shaft kiln 103.
The communication network 609 can be implemented as one of the different types of networks, such as intranet or Local Area Network (LAN) and such within the organization. The communication network 609 may either be a dedicated network or a shared network, which represents an association of the different types of networks that use a variety of protocols, for example, Hypertext Transfer Protocol (HTTP), Transmission Control Protocol/Internet Protocol (TCP/IP), Wireless Application Protocol (WAP), etc., to communicate with each other.
Further, the communication network 609 may include a variety of network devices, including routers, bridges, servers, computing devices, storage devices, etc. In some embodiments, the processor 602 may be disposed in communication with a memory 605 (e.g., RAM, ROM, etc. not shown in FIG.6) via a storage interface 604. The storage interface 604 may connect to memory 605 including, without limitation, memory drives, removable disc drives, etc., employing connection protocols such as Serial Advanced Technology Attachment (SATA), Integrated Drive Electronics (IDE), IEEE-1394, Universal Serial Bus (USB), fibre channel, Small Computer Systems Interface (SCSI), etc. The memory drives may further include a drum, magnetic disc drive, magneto-optical drive, optical drive, Redundant Array of Independent Discs (RAID), solid-state memory devices, solid-state drives, etc.
The memory 605 may store a collection of program or database components, including, without limitation, a user interface 606, an operating system 607, a web browser 608 etc. In some embodiments, the computer system 600 may store user/application data, such as the data, variables, records, etc. as described in this invention. Such databases may be implemented as fault-tolerant, relational, scalable, secure databases such as Oracle or Sybase.
Operating system 607 may facilitate resource management and operation of computer system 600. Examples of operating systems include, without limitation, APPLE® MACINTOSH® OS X®, UNIX®, UNIX-like system distributions (E.G., BERKELEY SOFTWARE DISTRIBUTION® (BSD), FREEBSD®, NETBSD®, OPENBSD, etc.), LINUX® DISTRIBUTIONS (E.G., RED HAT®, UBUNTU®, KUBUNTU®, etc.), IBM®OS/2®, MICROSOFT® WINDOWS® (XP®, VISTA®/7/8, 10 etc.), APPLE® IOS®, GOOGLETM ANDROIDTM, BLACKBERRY® OS, or the like. User interface 606 may facilitate display, execution, interaction, manipulation, or operation of program components through textual or graphical facilities. For example, user interfaces may provide computer interaction interface elements on a display system operatively connected to computer system 600, such as cursors, icons, check boxes, menus, scrollers, windows, widgets, etc. Graphical User Interfaces (GUIs) may be employed, including, without limitation, Apple® Macintosh® operating systems’ Aqua®, IBM® OS/2®, Microsoft® Windows® (e.g., Aero, Metro, etc.), web interface libraries (e.g., ActiveX®, Java®, Javascript®, AJAX, HTML, Adobe® Flash®, etc.), or the like.
Computer system 600 may implement web browser 608 stored program components. Web browser 608 may be a hypertext viewing application, such as MICROSOFT® INTERNET EXPLORER®, GOOGLETM CHROMETM, MOZILLA® FIREFOX®, APPLE® SAFARI®, etc. Secure web browsing may be provided using Secure Hypertext Transport Protocol (HTTPS), Secure Sockets Layer (SSL), Transport Layer Security (TLS), etc. Web browsers 608 may utilize facilities such as AJAX, DHTML, ADOBE® FLASH®, JAVASCRIPT®, JAVA®, Application Programming Interfaces (APIs), etc. Computer system 600 may implement a mail server stored program component. The mail server may be an Internet mail server such as Microsoft Exchange, or the like. The mail server may utilize facilities such as ASP, ACTIVEX®, ANSI® C++/C#, MICROSOFT®,. NET, CGI SCRIPTS, JAVA®, JAVASCRIPT®, PERL®, PHP, PYTHON®, WEBOBJECTS®, etc. The mail server may utilize communication protocols such as Internet Message Access Protocol (IMAP), Messaging Application Programming Interface (MAPI), MICROSOFT® exchange, Post Office Protocol (POP), Simple Mail Transfer Protocol (SMTP), or the like. In some embodiments, the computer system 600 may implement a mail client stored program component. The mail client may be a mail viewing application, such as APPLE® MAIL, MICROSOFT® ENTOURAGE®, MICROSOFT® OUTLOOK®, MOZILLA® THUNDERBIRD®, etc.
Furthermore, one or more computer-readable storage media may be utilized in implementing embodiments consistent with the present invention. A computer-readable storage medium refers to any type of physical memory on which information or data readable by a processor may be stored. Thus, a computer-readable storage medium may store instructions for execution by one or more processors, including instructions for causing the processor(s) to perform steps or stages consistent with the embodiments described herein. The term “computer-readable medium” should be understood to include tangible items and exclude carrier waves and transient signals, i.e., non-transitory. Examples include Random Access Memory (RAM), Read-Only Memory (ROM), volatile memory, non-volatile memory, hard drives, Compact Disc (CD) ROMs, Digital Video Disc (DVDs), flash drives, disks, and any other known physical storage media.
Advantages of the present disclosure:
An embodiment of the present disclosure enables real-time set point management for the twin shaft kiln operation and dynamically adopts to operating conditions compared to a scenario wherein a standard operating practice is used. As a result, the temperature profile and degree of conversion helps an operator of industrial plant to manage input parameters for complete calcination thereby optimizing ongoing process.
An embodiment of the present disclosure shows real time degree of conversion of limestone into lime and temperature profiles of solid and gas along the length of kiln shaft.
An embodiment of the present disclosure fixes a real-time set point for the operator to manage fuel properties and production rates.
An embodiment of the present disclosure shows predicted flue gas exit temperature, solid lime exit temperature, cross-over channel temperature in a regular time interval to the operator through an HMI overview screens.
Equivalents:
A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary a variety of optional components are described to illustrate the wide variety of possible embodiments of the invention. When a single device or article is described herein, it will be apparent that more than one device/article (whether or not they cooperate) may be used in place of a single device/article. Similarly, where more than one device or article is described herein (whether or not they cooperate), it will be apparent that a single device/article may be used in place of the more than one device or article, or a different number of devices/articles may be used instead of the shown number of devices or programs. The functionality and/or the features of a device may be alternatively embodied by one or more other devices which are not explicitly described as having such functionality/features. Thus, other embodiments of the invention need not include the device itself.

The specification has described a system and a method for determining and operating caster at an optimum casting speed in real-time. The illustrated steps are set out to explain the exemplary embodiments shown, and it should be anticipated that on-going technological development will change the manner in which particular functions are performed. These examples are presented herein for purposes of illustration, and not limitation. Further, the boundaries of the functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternative boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed. Alternatives (including equivalents, extensions, variations, deviations, etc., of those described herein) will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein. Such alternatives fall within the scope and spirit of the disclosed embodiments. Also, the words "comprising," "having," "containing," and "including," and other similar forms are intended to be equivalent in meaning and be open-ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.
Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the embodiments of the present invention are intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.

Referral numerals

Reference Number Description
100 Environment
101 Temperature determination system
103 Twin shaft kiln
105 Database
107 Communication interface
109 Programmable logic interface
111 I/O interface
113 Memory
115 Processor
200 Data
201 Input data
203 Grid data
205 Temperature profile model
207 Temperature data
209 Other data
213 Modules
215 Receiving module
217 Grid formation module
219 Identification module
221 Temperature profile determination module
223 Other modules
600 Exemplary computer system
601 I/O Interface of the exemplary computer system
602 Processor of the exemplary computer system
603 Network interface
604 Storage interface
605 Memory of the exemplary computer system
606 User interface
607 Operating system
608 Web browser
609 Communication network
611 Input devices
612 Output devices