阅读说明：本技术 燃煤火电厂入炉煤热值在线实时检测方法、系统及装置 (On-line real-time detection method, system and device for heat value of coal as fired in coal-fired thermal power plant ) 是由 王玉龙 于 2021-07-29 设计创作，主要内容包括：本发明涉及一种燃煤火电厂入炉煤热值在线实时检测方法、系统及装置,其中,该方法包括：在给煤机供煤过程中获取机组的实时主蒸汽流量和总给煤量；在机组控制系统中导入入炉煤热值计算公式,并实时计算入炉煤热值；根据设定的机组负荷调整配煤方案以将所述入炉煤热值调整至最低值。通过实时获取的主蒸汽流量和总给煤量计算入炉煤热值,无需通过采样、制样和化验等环节即可实时获得入炉煤热值,避免了化验检测的滞后性,并可通过该入炉煤热值及时调整配煤方案,使入炉煤热值调整至满足带负荷的最低值,从而实现低价低热值煤的高比例掺烧,降低了发电成本。(The invention relates to a method, a system and a device for online real-time detection of a heat value of fired coal in a coal-fired thermal power plant, wherein the method comprises the following steps: acquiring real-time main steam flow and total coal supply quantity of a unit in the coal supply process of a coal supply machine; introducing a fired coal heat value calculation formula into a unit control system, and calculating the fired coal heat value in real time; and adjusting a coal blending scheme according to the set unit load so as to adjust the heat value of the coal as fired to the lowest value. The heat value of the coal as fired is calculated through the main steam flow and the total coal supply quantity which are obtained in real time, the heat value of the coal as fired can be obtained in real time without sampling, sample preparation, chemical examination and other links, the hysteresis of chemical examination detection is avoided, and the coal blending scheme can be adjusted in time through the heat value of the coal as fired, so that the heat value of the coal as fired is adjusted to the lowest value meeting the load, high-proportion blending combustion of low-price and low-heat value coal is realized, and the power generation cost is reduced.)

1. An online real-time detection method for a heat value of fired coal in a coal-fired thermal power plant is characterized by comprising the following steps:

acquiring real-time main steam flow and total coal supply quantity of a unit in the coal supply process of a coal supply machine;

introducing a fired coal heat value calculation formula into a unit control system, and calculating the fired coal heat value in real time;

and adjusting a coal blending scheme according to the set unit load so as to adjust the heat value of the coal as fired to the lowest value.

2. The on-line real-time detection method for the calorific value of the fired coal of the coal-fired thermal power plant according to claim 1, wherein the calculation formula of the calorific value of the fired coal is specifically as follows:

the heat value of coal as fired is the steam production standard coal consumption value and the main steam flow rate 7/total coal supply amount;

and determining the steam production standard coal consumption value as {100+ (rated main steam flow-main steam flow) × coefficient }, wherein the coefficient is determined by corresponding to the current main steam flow in historical data stored in the unit control system.

3. The method for detecting the calorific value of the fired coal of the coal-fired thermal power plant in real time according to claim 2, wherein the step of adjusting the coal blending scheme according to the set unit load to adjust the calorific value of the fired coal to the minimum value specifically comprises the steps of:

obtaining a real-time calculated heat value of coal as fired and a current coal blending scheme;

according to the heat value of the coal as fired, the supply amount of the low heat value fire coal is increased and the supply amount of the high heat value fire coal is reduced in the current coal blending scheme to obtain a new coal blending scheme;

controlling a coal feeder to feed coal according to the new coal blending scheme, and recalculating the heat value of the coal as fired;

and repeating the steps until the calculated heat value of the coal as fired reaches the minimum value corresponding to the set unit load, and generating a corresponding coal blending scheme.

4. The on-line real-time detection method for the calorific value of the fired coal of the coal-fired thermal power plant according to claim 3, further comprising: after the heat value of the coal as fired is obtained through a test method, the calculated heat value of the coal as fired is verified and tested to obtain the heat value of the coal as fired.

5. The method for detecting the heat value of the fired coal in the coal-fired thermal power plant in real time according to claim 4, wherein the calculated heat value of the fired coal obtained by the fired coal heat value verification test specifically comprises:

selecting a plurality of groups of corresponding coal feeders to calculate the heat value of the coal as fired in real time in the testing time period and taking an average value;

comparing the average value with the heat value of the coal as fired obtained by testing to judge whether the average value exceeds the range of a preset deviation threshold value;

if yes, the checking result is judged to be qualified, and if not, the checking result is judged to be unqualified.

6. The on-line real-time detection method for the calorific value of fired coal of a coal-fired thermal power plant according to claim 5, wherein the predetermined deviation threshold range is 70Kcal/kg or less.

7. The method for detecting the calorific value of the fired coal of the coal-fired thermal power plant in real time according to claim 5 or 6, wherein if the verification result is judged to be unqualified, a weighing system of a coal feeder is calibrated or the fired coal is checked.

8. The on-line real-time detection method for the calorific value of the fired coal of the coal-fired thermal power plant according to claim 3, further comprising: after the heat value of coal entering and exiting the boiler is calculated, calculating the standard coal consumption of power generation according to the heat value of the coal entering the boiler and a standard mathematical model, taking the load rate and the temperature of the unit as boundary conditions, searching historical data stored in a unit control system to obtain the optimal working condition corresponding to the standard coal consumption of power generation, and adjusting the actual working condition to the optimal working condition.

9. The utility model provides an online real-time detection system of coal as fired thermal power plant calorific value of coal as fired which characterized in that includes:

the parameter acquisition unit is used for acquiring the real-time main steam flow and the total coal supply quantity of the unit in the coal supply process of the coal feeder;

the import calculation unit is used for importing a coal as fired heat value calculation formula into the unit control system and calculating the coal as fired heat value in real time;

the control adjusting unit is used for adjusting a coal blending scheme according to a set unit load so as to adjust the heat value of the coal as fired to a minimum value;

the checking unit is used for checking the heat value of the coal as fired obtained by testing through the calculated heat value of the coal as fired after the heat value of the coal as fired is obtained by testing; and the number of the first and second groups,

and the optimizing unit is used for calculating the standard coal consumption of power generation according to the heat value of coal as fired and a standard mathematical model after calculating the heat value of coal as fired, acquiring the optimal working condition corresponding to the standard coal consumption of power generation by searching historical data stored in the unit control system by taking the load rate and the temperature of the unit as boundary conditions, and adjusting the actual working condition to the optimal working condition.

10. A computer apparatus comprising a memory and a processor, the memory having stored therein computer readable instructions which, when executed by the processor, cause the processor to perform the steps of the on-line real-time detection method of coal as fired calorific value as claimed in any one of claims 1 to 8.

Technical Field

The invention relates to the technical field of coal-fired power generation detection, in particular to a method, a system and a device for detecting the heat value of fired coal in a coal-fired thermal power plant on line in real time.

Background

The procurement cost of the fire coal is the most important operation cost of the thermal power plant and accounts for about 75 percent of the total power generation cost, so the selection and analysis of the type and the cost of the fire coal are very important, and the economic benefit of the thermal power plant is directly related. The selection of the type of the fire coal and the generation of the coal blending scheme need to be determined according to the heat value of the fire coal as fired, the heat value of the current fire coal as fired needs to be detected through links such as sampling, sample preparation, assay and the like, generally more than 8 hours are needed for one-time detection, and the fire coal of a corresponding batch is generally used up after the detection is finished, so the obtained heat value of the fire coal as fired is difficult to be timely applied to the design and adjustment of the coal blending scheme, and the fire coal cost is difficult to be reasonably and effectively controlled.

Disclosure of Invention

In order to solve the technical problems, the invention provides a method, a system and a device for detecting the heat value of coal as fired in a coal-fired thermal power plant on line in real time, which have the advantages of obtaining the heat value of the coal as fired in real time, realizing high proportion co-combustion of low-price low-heat value coal and reducing the cost.

In order to achieve the purpose, the technical scheme of the invention is as follows:

an online real-time detection method for a heat value of fired coal in a coal-fired thermal power plant comprises the following steps:

acquiring real-time main steam flow and total coal supply quantity of a unit in the coal supply process of a coal supply machine;

introducing a fired coal heat value calculation formula into a unit control system, and calculating the fired coal heat value in real time;

and adjusting a coal blending scheme according to the set unit load so as to adjust the heat value of the coal as fired to the lowest value.

As a preferred scheme of the invention, the fired coal calorific value calculation formula is specifically as follows:

the heat value of coal as fired is the steam production standard coal consumption value and the main steam flow rate 7/total coal supply amount;

and determining the steam production standard coal consumption value as {100+ (rated main steam flow-main steam flow) × coefficient }, wherein the coefficient is determined by corresponding to the current main steam flow in historical data stored in the unit control system.

As a preferred aspect of the present invention, the adjusting a coal blending plan according to a set unit load to adjust the calorific value of the coal as fired to a minimum value specifically includes:

obtaining a real-time calculated heat value of coal as fired and a current coal blending scheme;

according to the heat value of the coal as fired, the supply amount of the low heat value fire coal is increased and the supply amount of the high heat value fire coal is reduced in the current coal blending scheme to obtain a new coal blending scheme;

controlling a coal feeder to feed coal according to the new coal blending scheme, and recalculating the heat value of the coal as fired;

and repeating the steps until the calculated heat value of the coal as fired reaches the minimum value corresponding to the set unit load, and generating a corresponding coal blending scheme.

As a preferable aspect of the present invention, the present invention further includes: after the heat value of the coal as fired is obtained through a test method, the calculated heat value of the coal as fired is verified and tested to obtain the heat value of the coal as fired.

As a preferred aspect of the present invention, the coal as fired heat value obtained by the calculated coal as fired heat value verification test specifically includes:

selecting a plurality of groups of corresponding coal feeders to calculate the heat value of the coal as fired in real time in the testing time period and taking an average value;

comparing the average value with the heat value of the coal as fired obtained by testing to judge whether the average value exceeds the range of a preset deviation threshold value;

if yes, the checking result is judged to be qualified, and if not, the checking result is judged to be unqualified.

As a preferable aspect of the present invention, the predetermined deviation threshold range is 70Kcal/kg or less.

As a preferred scheme of the invention, if the result of the judgment and the verification is unqualified, a weighing system of the coal feeder is calibrated or the fire coal entering the furnace is checked.

As a preferable aspect of the present invention, the present invention further includes: after the heat value of coal entering and exiting the boiler is calculated, calculating the standard coal consumption of power generation according to the heat value of the coal entering the boiler and a standard mathematical model, taking the load rate and the temperature of the unit as boundary conditions, searching historical data stored in a unit control system to obtain the optimal working condition corresponding to the standard coal consumption of power generation, and adjusting the actual working condition to the optimal working condition.

In order to solve the above technical problem, an embodiment of the present invention further provides an online real-time detection system for a heat value of coal as fired in a coal-fired thermal power plant, including:

the parameter acquisition unit is used for acquiring the real-time main steam flow and the total coal supply quantity of the unit in the coal supply process of the coal feeder;

the import calculation unit is used for importing a coal as fired heat value calculation formula into the unit control system and calculating the coal as fired heat value in real time;

the control adjusting unit is used for adjusting a coal blending scheme according to a set unit load so as to adjust the heat value of the coal as fired to a minimum value;

the checking unit is used for checking the heat value of the coal as fired obtained by testing through the calculated heat value of the coal as fired after the heat value of the coal as fired is obtained by testing; and the number of the first and second groups,

and the optimizing unit is used for calculating the standard coal consumption of power generation according to the heat value of coal as fired and a standard mathematical model after calculating the heat value of coal as fired, acquiring the optimal working condition corresponding to the standard coal consumption of power generation by searching historical data stored in the unit control system by taking the load rate and the temperature of the unit as boundary conditions, and adjusting the actual working condition to the optimal working condition.

In order to solve the above technical problem, an embodiment of the present invention further provides a computer device, which includes a memory and a processor, where the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the processor executes the steps of the online real-time detection method for calorific value of coal as fired according to the above technical solution.

In conclusion, the invention has the following beneficial effects:

the embodiment of the invention provides a method, a system and a device for detecting the heat value of the coal as fired in a coal-fired thermal power plant on line in real time, the heat value of the coal as fired is calculated through the main steam flow and the total coal supply quantity which are obtained in real time, the heat value of the coal as fired can be obtained in real time without links such as sampling, sample preparation, chemical examination and the like, the hysteresis of chemical examination and detection is avoided, and the coal blending scheme can be adjusted in time through the heat value of the coal as fired, so that the heat value of the coal as fired is adjusted to the lowest value meeting the load, high-proportion blending combustion of low-price low-heat-value coal is realized, and the power generation cost is reduced; the deviation between the heat value of the coal as fired calculated in real time and the heat value of the coal as fired obtained by testing can be compared in the checking process, so that the accuracy of the two can be checked, a weighing system of the coal feeder can be calibrated in time or the coal as fired can be checked according to the checking result, the accuracy of the detection result and the unit can be kept in a good working state, and meanwhile, the on-site supervision effect can be achieved; meanwhile, the power generation standard coal consumption can be calculated according to the heat value of the coal as fired, so that the optimal working condition of the power generation standard coal quantity can be found out in time through optimization, and the long-term optimal operation of the unit is realized.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a basic flow chart of an online real-time detection method for a heat value of coal as fired according to an embodiment of the invention;

FIG. 2 is a schematic flow chart of adjusting a coal blending scheme according to an embodiment of the present invention;

FIG. 3 is a flow chart illustrating a verification process according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of the basic structure of an on-line real-time detection device for the calorific value of coal as fired according to an embodiment of the present invention;

FIG. 5 is a block diagram of a basic structure of a computer device according to an embodiment of the present invention.

The corresponding part names indicated by the numbers and letters in the drawings:

601. a parameter acquisition unit; 602. importing a computing unit; 603. a control adjustment unit; 604. a verification unit; 605. and an optimizing unit.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.

In some of the flows described in the present specification and claims and in the above figures, a number of operations are included that occur in a particular order, but it should be clearly understood that these operations may be performed out of order or in parallel as they occur herein, with the order of the operations being indicated as 101, 102, etc. merely to distinguish between the various operations, and the order of the operations by themselves does not represent any order of performance. Additionally, the flows may include more or fewer operations, and the operations may be performed sequentially or in parallel. It should be noted that, the descriptions of "first", "second", etc. in this document are used for distinguishing different messages, devices, modules, etc., and do not represent a sequential order, nor limit the types of "first" and "second" to be different.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, fig. 1 is a schematic view of a basic flow chart of the online real-time detection method for the calorific value of the coal as fired according to the present embodiment.

A method for detecting the heat value of coal as fired in a coal-fired thermal power plant on line in real time is shown in figure 1 and comprises the following steps:

s100, acquiring real-time main steam flow and total coal supply quantity of the unit in the coal supply process of the coal supply machine.

When the unit normally works, the coal feeders take coal from the coal bunker and supply the coal to the boiler for combustion, the total coal supply amount is the sum of the real-time coal supply amounts of the coal feeders, and the main steam flow can be acquired in real time by a unit control system.

S200, introducing a heat value calculation formula of the coal as fired into the unit control system, and calculating the heat value of the coal as fired in real time.

The heat value calculation formula of the coal as fired is specifically as follows: the method comprises the following steps that (1) as-fired coal heat value is steam production standard coal consumption value and main steam flow 7/total coal supply quantity, wherein the steam production standard coal consumption value is {100+ (rated main steam flow-main steam flow) coefficient }, the coefficient is determined by corresponding to the current main steam flow in historical data stored in a unit control system, and the rated main steam flow is a main steam flow value recorded on a unit rated nameplate; the standard coal is coal with a basic low heat value of 29.27 Megajoules (MJ) (equivalent to 7000 kilocalories), the quantity of the standard coal consumed by the thermal power plant for producing electric energy of 1 degree (kWh) is standard coal consumption, the unit is g/(kWh), and after unit accounting, the value 7 in the formula can be obtained.

Taking a set of units as an example, if the rated main steam flow of the set is 1000, the coefficient obtained from the historical data is 0.03, and the corresponding heat value of the coal as fired is {100+ (1000-main steam flow) × 0.03}, main steam flow × 7/total coal supply.

S300, adjusting a coal blending scheme according to the set unit load so as to adjust the heat value of the coal as fired to the lowest value.

As shown in fig. 2, step S300 specifically includes:

s301, acquiring a coal as fired calorific value calculated in real time and a current coal blending scheme;

s302, according to the heat value of coal as fired, increasing the supply amount of low heat value coal and reducing the supply amount of high heat value coal in the current coal blending scheme to obtain a new coal blending scheme, wherein the supply amount of coal can be controlled by controlling the opening degree of a valve of a coal feeder, when the coal blending scheme is adjusted, a group of gradient parameters can be preset according to experience, for example, the low heat value coal and the high heat value coal can be sequentially increased and reduced from low heat value to high heat value coal, and a new coal blending scheme is formed after one-time adjustment;

s303, controlling a coal feeder to feed coal according to the new coal blending scheme, and recalculating the heat value of the coal as fired; when a new coal blending direction is generated every time, correspondingly changing the coal supply amount of the coal feeder once, in the actual working process, setting to continuously work for a period according to a new coal blending scheme, wherein the period time can be 1-10min, and simultaneously selecting a group of coal as fired heat values within the period time to obtain an average value, and comparing the average value with a set lowest value corresponding to the unit load;

s304, repeating the steps until the calculated heat value of the coal as fired reaches the lowest value corresponding to the set unit load, and generating a corresponding coal blending scheme; and correspondingly adjusting a coal blending scheme according to the result obtained by comparing the steps, determining that the coal blending scheme is a final coal blending scheme when the heat value of the coal as fired generated by coal feeding according to the coal blending scheme reaches a minimum value corresponding to the set unit load or is basically close to the minimum value, and continuously adopting the coal blending scheme for coal feeding under the current unit load state.

And S400, after the heat value of the coal as fired is obtained through a testing method, the heat value of the coal as fired is obtained through calculation and verification testing.

As shown in fig. 3, the coal as fired heat value obtained by the calculated coal as fired heat value verification test specifically includes:

s401, selecting a plurality of groups of corresponding coal feeders to calculate the heat value of coal as fired in real time in a testing time period to obtain an average value;

s402, comparing the average value with the heat value of the coal as fired obtained by the test to judge whether the average value exceeds a preset deviation threshold range, wherein the preset deviation threshold range can be set to be less than or equal to 70 Kcal/kg; if so, judging that the checking result is qualified, otherwise, judging that the checking result is unqualified, and simultaneously calibrating a weighing system of the coal feeder or checking the coal entering the furnace.

S500, after the heat value of coal entering and exiting the boiler is calculated, calculating the standard coal consumption of power generation according to the heat value of the coal entering the boiler and a standard mathematical model, searching historical data stored in a unit control system to obtain the optimal working condition corresponding to the standard coal consumption of power generation by taking the load rate and the temperature of the unit as boundary conditions, and adjusting the actual working condition to the optimal working condition.

The standard mathematical model is specifically as follows:

the standard coal consumption for power generation is (total standard coal amount-heat supply standard coal amount)/power generation amount;

total standard coal amount (kg/kwh) is raw coal amount entering the furnace and coal calorific value entering the furnace/7000;

heating target coal quantity is equal to heating enthalpy value and heating target coal consumption;

the heat supply standard coal consumption (kg/T) is the heat supply raw coal consumption/7000, the heat value is the raw coal heat value entering the furnace, unit: kCal/kg;

the raw coal consumption for heating (coal consumption × 1000/steam production of boiler) × 1.0807274, the coal consumption means the raw coal consumption actually charged into the boiler, unit: ton (T), boiler steam production to actual boiler steam flow, unit: ton (T).

In order to solve the above technical problem, an embodiment of the present invention further provides an online real-time detection system for a calorific value of coal as fired in a coal-fired thermal power plant, as shown in fig. 4, including: the parameter obtaining unit 601 is used for obtaining the real-time main steam flow and the total coal supply quantity of the unit in the coal supply process of the coal supply machine; the import calculation unit 602 is used for importing a coal as fired heat value calculation formula into the unit control system and calculating the coal as fired heat value in real time; a control adjustment unit 603, configured to adjust a coal blending scheme according to a set unit load to adjust the heat value of the coal as fired to a minimum value; the checking unit 604 is used for checking the heat value of the coal as fired obtained by the assay through the calculated heat value of the coal as fired after the heat value of the coal as fired is obtained by the assay method; and the optimizing unit 605 is configured to calculate the standard coal consumption for power generation according to the standard mathematical model based on the heat value of the coal as fired after calculating the heat value of the coal as fired, obtain an optimal working condition corresponding to the standard coal consumption for power generation by searching historical data stored in the unit control system using the load rate and the temperature of the unit as boundary conditions, and adjust the actual working condition to the optimal working condition.

The method calculates the heat value of the coal as fired through the main steam flow and the total coal feeding amount which are obtained in real time, can obtain the heat value of the coal as fired in real time without links such as sampling, sample preparation, chemical examination and the like, avoids the hysteresis of chemical examination detection, and can adjust the coal blending scheme in time through the heat value of the coal as fired to ensure that the heat value of the coal as fired is adjusted to the lowest value meeting the load, thereby realizing the high-proportion blending combustion of low-price low-heat value coal and reducing the power generation cost; the deviation between the heat value of the coal as fired calculated in real time and the heat value of the coal as fired obtained by testing can be compared in the checking process, so that the accuracy of the two can be checked, a weighing system of the coal feeder can be calibrated in time or the coal as fired can be checked according to the checking result, the accuracy of the detection result and the unit can be kept in a good working state, and meanwhile, the on-site supervision effect can be achieved; meanwhile, the power generation standard coal consumption can be calculated according to the heat value of the coal as fired, so that the optimal working condition of the power generation standard coal quantity can be found out in time through optimization, and the long-term optimal operation of the unit is realized.

To solve the above technical problem, an embodiment of the present invention further provides a computer apparatus. Referring to fig. 5, fig. 5 is a block diagram of a basic structure of the computer device according to the present embodiment.

As shown in fig. 5, the internal structure of the computer device is schematically illustrated. The computer apparatus includes a processor, a non-volatile storage medium, a memory, and a network interface connected by a system bus. The non-volatile storage medium of the computer device stores an operating system, a database and computer readable instructions, the database can store control information sequences, and the computer readable instructions can enable the processor to realize an online real-time detection method for the calorific value of the coal as fired when being executed by the processor. The processor of the computer device is used to provide computing and control capabilities, supporting the operation of the entire computer device. The memory of the computer device can be stored with computer readable instructions, and the computer readable instructions can be executed by the processor to enable the processor to execute a method for detecting the calorific value of the coal as fired on line in real time. The network interface of the computer device is used for connecting and communicating with the terminal. Those skilled in the art will appreciate that the configuration shown in fig. 5 is a block diagram of only a portion of the configuration associated with the present application and is not intended to limit the computing device to which the present application may be applied, and that a particular computing device may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.

In this embodiment, the processor is configured to execute specific functions of the parameter obtaining unit 601, the import calculating unit 602, the control adjusting unit 603, the verifying unit 604, and the optimizing unit 605 in fig. 4, and the memory stores program codes and various data required for executing the above modules. The network interface is used for data transmission to and from a user terminal or a server. The memory in this embodiment stores program codes and data required for executing all the sub-modules in the face image key point detection device, and the server can call the program codes and data of the server to execute the functions of all the sub-modules.

The invention also provides a storage medium storing computer readable instructions, and the computer readable instructions, when executed by one or more processors, cause the one or more processors to execute the steps of the online real-time detection method for the calorific value of the coal as fired according to any one of the above embodiments.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and can include the processes of the embodiments of the methods described above when the computer program is executed. The storage medium may be a non-volatile storage medium such as a magnetic disk, an optical disk, a Read-Only Memory (ROM), or a Random Access Memory (RAM).

It should be understood that, although the steps in the flowcharts of the figures are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and may be performed in other orders unless explicitly stated herein. Moreover, at least a portion of the steps in the flow chart of the figure may include multiple sub-steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed alternately or alternately with other steps or at least a portion of the sub-steps or stages of other steps.