CN111981506A - Method and system for confirming optimal oxygen content of coal-fired boiler - Google Patents
Method and system for confirming optimal oxygen content of coal-fired boiler Download PDFInfo
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Abstract
The invention discloses a method and a system for confirming the optimal oxygen amount of a coal-fired boiler.
Description
Technical Field
The invention relates to a method and a system for confirming optimal oxygen content of a coal-fired boiler, belonging to the field of thermal power generation.
Background
The oxygen content of the flue gas is an important monitoring parameter for the operation of the coal-fired unit, the quality of combustion in a furnace can be visually reflected, the change of the oxygen content causes the change of boiler efficiency, auxiliary machine power consumption, steam temperature and the like, wherein the influence on the boiler efficiency is the largest, so the reasonable oxygen content has important significance for controlling the combustion process and realizing safe and efficient combustion.
With the gradual normalization of the deep peak shaving of the thermal power generating unit, the thermal power generating unit frequently operates in a medium-low load section, the oxygen amount range accurately controlled by an operator is generally in a rated load and a high load section, and great randomness is provided for controlling the oxygen amount of the medium-low load section.
Generally, the operating oxygen content of the coal-fired boiler is determined through a combustion optimization adjustment test, a plurality of groups of variable oxygen content tests are carried out, the boiler efficiency is calculated, and an optimal oxygen content range is searched according to an oxygen content-boiler efficiency curve. The combustion optimization adjustment test is a conventional method for groping the operation rule of a boiler and improving the operation economy, is adopted by most power plants, but the test determines that the optimal control oxygen amount is generally an oxygen amount interval and is difficult to be accurate to a specific value.
Disclosure of Invention
The invention provides a method and a system for confirming optimal oxygen quantity of a coal-fired boiler, which solve the problem that the optimal oxygen quantity is difficult to be accurate to a specific value by the existing method.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a method for determining the optimal oxygen content in coal-burning boiler includes such steps as determining the optimal oxygen content in coal-burning boiler,
constructing a function expression of boiler efficiency with respect to an oxygen derivative based on a preset simplification rule and actual operation characteristics of the boiler;
calculating a coefficient to be solved in the function expression according to the collected test measurement data;
substituting the calculated coefficient into a function expression to obtain the optimal oxygen amount.
The simplified rule is that,
when the specific heat of the dry flue gas is calculated, only oxygen, carbon dioxide and nitrogen are added;
when the volume of the water vapor in the flue gas is calculated, the flow of the fuel oil atomization steam is ignored;
when the heat loss of the incomplete combustion of the gas is calculated, the incomplete combustion gas is carbon monoxide, and the rest gas is ignored;
ignoring other air mass flow not passing through the air preheater of the boiler system;
when the dry air entering the boiler system carries heat, the weighted temperature of the air entering the boiler system is simplified into
Wherein, ta.p、ta.sThe temperature of primary air and the temperature of secondary air entering a boiler system are respectively; (ii) a
The derivative of specific heat to oxygen of dry flue gas, dry air and water vapor is 0;
the derivative of the quantity of fuel with respect to the quantity of oxygen being 0
The derivative of the primary air quantity at the inlet of the air preheater of the boiler system to the oxygen quantity is 0.
The functional expression of boiler efficiency with respect to the derivative of oxygen is,
wherein, a and N1、N2、N3、N4M is the coefficient to be solved, O2The oxygen content of the boiler furnace outlet.
The coefficient to be calculated is calculated according to the formula,
N3＝21cp.fg.DEN.entfg,DEN.en(0.0333ωS.ar+0.2647ωH.ar-0.0334ωO.ar)+1.8648ωc.bcp.fg.DEN.entfg,DEN.en
wherein, O2AThe oxygen content of an air preheater of a boiler system is calculated, K is the air leakage rate of the air preheater, cp.fg.dIs the dry flue gas at the outlet of the air preheater with constant pressure and specific heat capacity tfg.AH.lvIs the outlet flue gas temperature t of the air preheaterreThe reference temperature is set to a reference temperature,
is the volume fraction of carbon monoxide in dry flue gas, omegaS.arIs the mass fraction of sulfur in the fuel entering the furnace, omegaH.arIs the mass fraction of hydrogen in the fuel charged to the furnace, omegaO.arIs the mass fraction of oxygen in the fuel entering the furnace, omegac.bThe mass fraction of carbon actually burned in the furnace fuel, ha.abAs absolute humidity of air, cp.wvFor the steam entering the boiler system at a constant pressure and specific heat capacity, cp.a.sFor secondary air entering the boiler system, t is the specific heat capacity at constant pressurea.sFor entering the second of the boiler systemWind temperature, pa.sFor secondary air entering the boiler system, constant pressure and specific heat capacity, cp.a.reIs the specific heat capacity at constant pressure of air at a reference temperature, rhoa.reAir density at reference temperature, ta.pPrimary air temperature for entering boiler system, cp.fg.DEN.lvFor the constant pressure specific heat capacity of the flue gas at the outlet of the denitration device of the boiler system, cp.fg.DEN.enFor the inlet flue gas constant pressure specific heat capacity, t, of the denitration device of the boiler systemfg,DEN.lvFor the outlet flue gas temperature, t, of the denitrification devicefg,DEN.enFor the inlet flue gas temperature, omega, of the denitrating apparatusas.arIs the mass fraction of ash in the fuel entering the furnace, omegac.sIs the mass fraction of combustible material in the slag, omegac.asIs the mass fraction of combustible material in the fly ash, omegaN.arMass fraction of nitrogen, omega, in the fuel charged to the furnacem.arIs the mass fraction of the moisture in the fuel entering the furnace.
An optimal oxygen quantity confirmation system of a coal-fired boiler comprises,
the function building module: constructing a function expression of boiler efficiency with respect to an oxygen derivative based on a preset simplification rule and actual operation characteristics of the boiler;
a coefficient solving module: calculating a coefficient to be solved in the function expression according to the collected test measurement data;
an oxygen amount solving module: substituting the calculated coefficient into a function expression to obtain the optimal oxygen amount.
The simplified rule is that,
when the specific heat of the dry flue gas is calculated, only oxygen, carbon dioxide and nitrogen are added;
when the volume of the water vapor in the flue gas is calculated, the flow of the fuel oil atomization steam is ignored;
when the heat loss of the incomplete combustion of the gas is calculated, the incomplete combustion gas is carbon monoxide, and the rest gas is ignored;
ignoring other air mass flow not passing through the air preheater of the boiler system;
when the dry air entering the boiler system carries heat, the weighted temperature of the air entering the boiler system is simplified into
Wherein, ta.p、ta.sThe temperature of primary air and the temperature of secondary air entering a boiler system are respectively; (ii) a
The derivative of specific heat to oxygen of dry flue gas, dry air and water vapor is 0;
the derivative of the quantity of fuel with respect to the quantity of oxygen being 0
The derivative of the primary air quantity at the inlet of the air preheater of the boiler system to the oxygen quantity is 0.
The functional expression of boiler efficiency with respect to the derivative of oxygen is,
wherein, a and N1、N2、N3、N4M is the coefficient to be solved, O2The oxygen content of the boiler furnace outlet.
The coefficient to be calculated is calculated according to the formula,
N3＝21cp.fg.DEN.entfg,DEN.en(0.0333ωS.ar+0.2647ωH.ar-0.0334ωO.ar)+1.8648ωc.bcp.fg.DEN.entfg,DEN.en
wherein, O2AThe oxygen content of an air preheater of a boiler system is calculated, K is the air leakage rate of the air preheater, cp.fg.dIs the dry flue gas at the outlet of the air preheater with constant pressure and specific heat capacity tfg.AH.lvIs the outlet flue gas temperature t of the air preheaterreThe reference temperature is set to a reference temperature,
is the volume fraction of carbon monoxide in dry flue gas, omegaS.arIs the mass fraction of sulfur in the fuel entering the furnace, omegaH.arIs the mass fraction of hydrogen in the fuel charged to the furnace, omegaO.arIs the mass fraction of oxygen in the fuel entering the furnace, omegac.bThe mass fraction of carbon actually burned in the furnace fuel, ha.abAs absolute humidity of air, cp.wvFor the steam entering the boiler system at a constant pressure and specific heat capacity, cp.a.sFor secondary air entering the boiler system, t is the specific heat capacity at constant pressurea.sTemperature of secondary air, rho, for entering the boiler systema.sFor secondary air entering the boiler system, constant pressure and specific heat capacity, cp.a.reIs the specific heat capacity at constant pressure of air at a reference temperature, rhoa.reAir density at reference temperature, ta.pPrimary air temperature for entering boiler system, cp.fg.DEN.lvFor the constant pressure specific heat capacity of the flue gas at the outlet of the denitration device of the boiler system, cp.fg.DEN.enFor the inlet flue gas constant pressure specific heat capacity, t, of the denitration device of the boiler systemfg,DEN.lvFor the outlet flue gas temperature, t, of the denitrification devicefg,DEN.enFor the inlet flue gas temperature, omega, of the denitrating apparatusas.arIs the mass fraction of ash in the fuel entering the furnace, omegac.sIs the mass fraction of combustible material in the slag, omegac.asIs the mass fraction of combustible material in the fly ash, omegaN.arMass fraction of nitrogen, omega, in the fuel charged to the furnacem.arIs the mass fraction of the moisture in the fuel entering the furnace.
A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform a coal fired boiler optimal oxygen determination method.
A computing device comprising one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs comprising instructions for performing a coal fired boiler optimal oxygen determination method.
The invention achieves the following beneficial effects: the invention constructs a function expression of boiler efficiency on oxygen derivative, calculates the coefficient to be solved in the function expression through test measured data to obtain the optimal oxygen, can accurately position the specific value of the optimal oxygen in the full-load operation of the boiler, and improves the operation economy of a unit.
Drawings
FIG. 1 is a schematic diagram of a boiler system;
FIG. 2 is a flow chart of the method of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
As shown in fig. 2, a method for determining an optimal oxygen amount of a coal-fired boiler comprises the following steps:
step 1, constructing a functional expression of boiler efficiency with respect to an oxygen derivative based on a preset simplification rule, actual operation characteristics of a boiler and a boiler performance test procedure GBT 10184-2015.
Fig. 1 is a structural diagram of a current boiler system, wherein an outlet of a boiler furnace is sequentially connected with a denitration device (SCR) and an air preheater; the relationship between oxygen amounts at different positions in the graph is as follows:
defining the oxygen content of the smoke at three positions as follows: oxygen content O at boiler furnace outlet2Oxygen content O at outlet of denitration device (inlet of air preheater)2AOxygen content at outlet of air preheater2BIn which O is2The parameters are controlled for the optimal oxygen amount.
According to the actual operation, O2AAnd O2Can approximately represent:
O2A＝aO2
wherein a is a constant, which can be determined experimentally;
the oxygen quantity of the inlet and the outlet of the air preheater is related through the air leakage rate K of the air preheater:
for a conventional pulverized coal furnace, the following simplification rules are specified here, depending on the actual operation:
1) because the contents of carbon monoxide, sulfur dioxide and nitric oxide are very little, only oxygen, carbon dioxide and nitrogen are counted when the specific heat of the dry flue gas is calculated;
2) when the volume of the water vapor in the flue gas is calculated, the flow of the fuel oil atomization steam is ignored;
3) when the heat loss of the incomplete combustion of the gas is calculated, the incomplete combustion gas is carbon monoxide, and the rest gas is ignored;
4) ignoring other air mass flow not passing through the air preheater of the boiler system;
5) calculating the weighted temperature of the air entering the boiler system when the dry air entering the boiler system carries heat
Simplified to
Wherein, ta.p、ta.s、qm.a.p、qm.a.sThe primary air temperature, the secondary air temperature, the primary air mass flow and the secondary air mass flow entering the boiler system are sequentially measured;
6) the derivative of specific heat to oxygen of dry flue gas, dry air and water vapor is 0;
7) the derivative of the quantity of fuel with respect to the quantity of oxygen being 0
8) The derivative of the primary air quantity at the inlet of the air preheater of the boiler system to the oxygen quantity is 0.
The heat losses of the boiler comprise: heat loss from exhaust Q2Heat loss Q due to incomplete combustion of gas3To cure and cureHeat loss due to incomplete combustion Q4Because the influence of the change of oxygen on the heat dissipation loss of the boiler, the physical sensible heat loss of ash and other heat losses can be ignored, the sum of all heat losses QlostThe expression is as follows: qlost＝Q2+Q3+Q4。
The external heat of the boiler comprises: heat Q carried by dry air entering the system boundary (without air preheater)adWater vapor heat Q in the air entering the system boundarywvAnd the external heat Q of the denitration devicefg,DENBecause the change of oxygen amount has negligible influence on the physical sensible heat of fuel, the physical sensible heat of desulfurizer, the heat brought in by auxiliary equipment and the heat brought in by atomized steam, the sum Q of the external heat of the boilerexThe expression is as follows:
Qex＝Qad+Qwv+Qfg,DEN。
in actual operation, other operation parameters are kept unchanged, the boiler efficiency shows a trend of increasing and then decreasing along with the oxygen content from low to high, and when the derivative of the boiler efficiency on the oxygen content is 0, the corresponding oxygen content is the optimal control oxygen content under the current load:
the expression of the boiler efficiency is as follows,
wherein Q isnet,arIs the low heating value of the fuel;
the expression for the optimum amount of oxygen controlled may therefore become:
bringing into particular QlostAnd QexThe functional expression of boiler efficiency with respect to oxygen derivative is available:
wherein, a and N1、N2、N3、N4And M is a coefficient to be solved.
The formula of the coefficient to be solved is as follows:
N3＝21cp.fg.DEN.entfg,DEN.en(0.0333ωS.ar+0.2647ωH.ar-0.0334ωO.ar)+1.8648ωc.bcp.fg.DEN.entfg,DEN.en
wherein, O2AThe oxygen content of an air preheater of a boiler system is calculated, K is the air leakage rate of the air preheater, cp.fg.dIs the dry flue gas at the outlet of the air preheater with constant pressure and specific heat capacity tfg.AH.lvIs the outlet flue gas temperature t of the air preheaterreThe reference temperature is set to a reference temperature,
is the volume fraction of carbon monoxide in dry flue gas, omegaS.arIs the mass fraction of sulfur in the fuel entering the furnaceNumber, omegaH.arIs the mass fraction of hydrogen in the fuel charged to the furnace, omegaO.arIs the mass fraction of oxygen in the fuel entering the furnace, omegac.bThe mass fraction of carbon actually burned in the furnace fuel, ha.abAs absolute humidity of air, cp.wvFor the steam entering the boiler system at a constant pressure and specific heat capacity, cp.a.sFor secondary air entering the boiler system, t is the specific heat capacity at constant pressurea.sTemperature of secondary air, rho, for entering the boiler systema.sFor secondary air entering the boiler system, constant pressure and specific heat capacity, cp.a.reIs the specific heat capacity at constant pressure of air at a reference temperature, rhoa.reAir density at reference temperature, ta.pPrimary air temperature for entering boiler system, cp.fg.DEN.lvFor the constant pressure specific heat capacity of the flue gas at the outlet of the denitration device of the boiler system, cp.fg.DEN.enFor the inlet flue gas constant pressure specific heat capacity, t, of the denitration device of the boiler systemfg,DEN.lvFor the outlet flue gas temperature, t, of the denitrification devicefg,DEN.enFor the inlet flue gas temperature, omega, of the denitrating apparatusas.arIs the mass fraction of ash in the fuel entering the furnace, omegac.sIs the mass fraction of combustible material in the slag, omegac.asIs the mass fraction of combustible material in the fly ash, omegaN.arMass fraction of nitrogen, omega, in the fuel charged to the furnacem.arIs the mass fraction of the moisture in the fuel entering the furnace.
And 2, calculating a coefficient to be solved in the function expression according to the collected test measurement data.
Under the condition of stable load, three working conditions of tests are carried out, namely a reference working condition, a variable oxygen content working condition I and a variable oxygen content working condition II. The oxygen content under the reference working condition is an operation habit value, other operation parameters are kept unchanged, the oxygen content is respectively increased by 10% and 20%, an oxygen changing working condition I and an oxygen changing working condition II are carried out, and the acquisition modes of all parameters are shown in a table 1;
TABLE 1 acquisition of parameters
Note: the test can be obtained by adopting field test or dial data (needing to be provided with online measuring points).
Wherein
Etc. by using a linear ratio method. The above parameters are substituted into the coefficient formula, and the specific coefficient value can be obtained.
Step 3, substituting the calculated coefficient into a function expression to obtain the optimal oxygen amount; i.e., the one-dimensional multiple equation of oxygen available after the coefficients are substituted, and solving this equation to obtain the optimum oxygen.
The method comprises the steps of firstly constructing a function expression of boiler efficiency on an oxygen derivative, calculating a coefficient to be solved in the function expression through test measured data to obtain the optimal oxygen, accurately positioning the specific value of the optimal oxygen in the full-load operation of the boiler, and improving the operation economy of a unit.
An optimal oxygen quantity confirmation system of a coal-fired boiler comprises,
the function building module: and constructing a functional expression of the boiler efficiency relative to the derivative of the oxygen quantity based on a preset simplified rule and the actual operation characteristic of the boiler.
The simplified rule is that,
when the specific heat of the dry flue gas is calculated, only oxygen, carbon dioxide and nitrogen are added;
when the volume of the water vapor in the flue gas is calculated, the flow of the fuel oil atomization steam is ignored;
when the heat loss of the incomplete combustion of the gas is calculated, the incomplete combustion gas is carbon monoxide, and the rest gas is ignored;
ignoring other air mass flow not passing through the air preheater of the boiler system;
when the dry air entering the boiler system carries heat, the weighted temperature of the air entering the boiler system is simplified into
The derivative of specific heat to oxygen of dry flue gas, dry air and water vapor is 0;
the derivative of the quantity of fuel with respect to the quantity of oxygen being 0
The derivative of the primary air quantity at the inlet of the air preheater of the boiler system to the oxygen quantity is 0.
The functional expression of boiler efficiency with respect to the derivative of oxygen is,
wherein, a and N1、N2、N3、N4M is the coefficient to be solved, O2The oxygen content of the boiler furnace outlet.
The coefficient to be calculated is calculated according to the formula,
N3＝21cp.fg.DEN.entfg,DEN.en(0.0333ωS.ar+0.2647ωH.ar-0.0334ωO.ar)+1.8648ωc.bcp.fg.DEN.entfg,DEN.en
wherein, O2AThe oxygen content of an air preheater of a boiler system is calculated, K is the air leakage rate of the air preheater, cp.fg.dIs the dry flue gas at the outlet of the air preheater with constant pressure and specific heat capacity tfg.AH.lvIs the outlet flue gas temperature t of the air preheaterreThe reference temperature is set to a reference temperature,
is the volume fraction of carbon monoxide in dry flue gas, omegaS.arIs the mass fraction of sulfur in the fuel entering the furnace, omegaH.arIs the mass fraction of hydrogen in the fuel charged to the furnace, omegaO.arIs the mass fraction of oxygen in the fuel entering the furnace, omegac.bThe mass fraction of carbon actually burned in the furnace fuel, ha.abAs absolute humidity of air, cp.wvFor the steam entering the boiler system at a constant pressure and specific heat capacity, cp.a.sFor secondary air entering the boiler system, t is the specific heat capacity at constant pressurea.sTemperature of secondary air, rho, for entering the boiler systema.sFor secondary air entering the boiler system, constant pressure and specific heat capacity, cp.a.reIs the specific heat capacity at constant pressure of air at a reference temperature, rhoa.reAir density at reference temperature, ta.pPrimary air temperature for entering boiler system, cp.fg.DEN.lvIs a boilerFlue gas at constant pressure and specific heat capacity at outlet of system denitration device, cp.fg.DEN.enFor the inlet flue gas constant pressure specific heat capacity, t, of the denitration device of the boiler systemfg,DEN.lvFor the outlet flue gas temperature, t, of the denitrification devicefg,DEN.enFor the inlet flue gas temperature, omega, of the denitrating apparatusas.arIs the mass fraction of ash in the fuel entering the furnace, omegac.sIs the mass fraction of combustible material in the slag, omegac.asIs the mass fraction of combustible material in the fly ash, omegaN.arMass fraction of nitrogen, omega, in the fuel charged to the furnacem.arIs the mass fraction of the moisture in the fuel entering the furnace.
A coefficient solving module: and calculating the coefficient to be solved in the function expression according to the collected test determination data.
An oxygen amount solving module: substituting the calculated coefficient into a function expression to obtain the optimal oxygen amount.
A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform a coal fired boiler optimal oxygen determination method.
A computing device comprising one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs comprising instructions for performing a coal fired boiler optimal oxygen determination method.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention which are filed as the application.
Claims (10)
1. A method for confirming the optimal oxygen content of a coal-fired boiler is characterized by comprising the following steps: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
constructing a function expression of boiler efficiency with respect to an oxygen derivative based on a preset simplification rule and actual operation characteristics of the boiler;
calculating a coefficient to be solved in the function expression according to the collected test measurement data;
substituting the calculated coefficient into a function expression to obtain the optimal oxygen amount.
2. The method for determining optimal oxygen amount of a coal-fired boiler according to claim 1, wherein: the simplified rule is that,
when the specific heat of the dry flue gas is calculated, only oxygen, carbon dioxide and nitrogen are added;
when the volume of the water vapor in the flue gas is calculated, the flow of the fuel oil atomization steam is ignored;
when the heat loss of the incomplete combustion of the gas is calculated, the incomplete combustion gas is carbon monoxide, and the rest gas is ignored;
ignoring other air mass flow not passing through the air preheater of the boiler system;
when the dry air entering the boiler system carries heat, the weighted temperature of the air entering the boiler system is simplified into
Wherein, ta.p、ta.sThe temperature of primary air and the temperature of secondary air entering a boiler system are respectively;
the derivative of specific heat to oxygen of dry flue gas, dry air and water vapor is 0;
the derivative of the quantity of fuel with respect to the quantity of oxygen being 0
The derivative of the primary air quantity at the inlet of the air preheater of the boiler system to the oxygen quantity is 0.
3. The method for determining optimal oxygen amount of a coal-fired boiler according to claim 1, wherein: the functional expression of boiler efficiency with respect to the derivative of oxygen is,
wherein, a and N1、N2、N3、N4M is the coefficient to be solved, O2The oxygen content of the boiler furnace outlet.
4. The method for determining optimal oxygen amount of a coal-fired boiler according to claim 3, wherein: the coefficient to be calculated is calculated according to the formula,
N3＝21cp.fg.DEN.entfg,DEN.en(0.0333ωS.ar+0.2647ωH.ar-0.0334ωO.ar)+1.8648ωc.bcp.fg.DEN.entfg,DEN.en
wherein, O2AThe oxygen content of an air preheater of a boiler system is calculated, K is the air leakage rate of the air preheater, cp.fg.dIs dry flue gas at the outlet of the air preheaterSpecific heat capacity at constant pressure, tfg.AH.lvIs the outlet flue gas temperature t of the air preheaterreThe reference temperature is set to a reference temperature,
is the volume fraction of carbon monoxide in dry flue gas, omegaS.arIs the mass fraction of sulfur in the fuel entering the furnace, omegaH.arIs the mass fraction of hydrogen in the fuel charged to the furnace, omegaO.arIs the mass fraction of oxygen in the fuel entering the furnace, omegac.bThe mass fraction of carbon actually burned in the furnace fuel, ha.abAs absolute humidity of air, cp.wvFor the steam entering the boiler system at a constant pressure and specific heat capacity, cp.a.sFor secondary air entering the boiler system, t is the specific heat capacity at constant pressurea.sTemperature of secondary air, rho, for entering the boiler systema.sFor secondary air entering the boiler system, constant pressure and specific heat capacity, cp.a.reIs the specific heat capacity at constant pressure of air at a reference temperature, rhoa.reAir density at reference temperature, ta.pPrimary air temperature for entering boiler system, cp.fg.DEN.lvFor the constant pressure specific heat capacity of the flue gas at the outlet of the denitration device of the boiler system, cp.fg.DEN.enFor the inlet flue gas constant pressure specific heat capacity, t, of the denitration device of the boiler systemfg,DEN.lvFor the outlet flue gas temperature, t, of the denitrification devicefg,DEN.enFor the inlet flue gas temperature, omega, of the denitrating apparatusas.arIs the mass fraction of ash in the fuel entering the furnace, omegac.sIs the mass fraction of combustible material in the slag, omegac.asIs the mass fraction of combustible material in the fly ash, omegaN.arMass fraction of nitrogen, omega, in the fuel charged to the furnacem.arIs the mass fraction of the moisture in the fuel entering the furnace.
5. An optimal oxygen quantity confirmation system of a coal-fired boiler is characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
the function building module: constructing a function expression of boiler efficiency with respect to an oxygen derivative based on a preset simplification rule and actual operation characteristics of the boiler;
a coefficient solving module: calculating a coefficient to be solved in the function expression according to the collected test measurement data;
an oxygen amount solving module: substituting the calculated coefficient into a function expression to obtain the optimal oxygen amount.
6. The system for determining optimal oxygen content of a coal-fired boiler according to claim 5, wherein: the simplified rule is that,
when the specific heat of the dry flue gas is calculated, only oxygen, carbon dioxide and nitrogen are added;
when the volume of the water vapor in the flue gas is calculated, the flow of the fuel oil atomization steam is ignored;
when the heat loss of the incomplete combustion of the gas is calculated, the incomplete combustion gas is carbon monoxide, and the rest gas is ignored;
ignoring other air mass flow not passing through the air preheater of the boiler system;
when the dry air entering the boiler system carries heat, the weighted temperature of the air entering the boiler system is simplified into
Wherein, ta.p、ta.sThe temperature of primary air and the temperature of secondary air entering a boiler system are respectively; (ii) a
The derivative of specific heat to oxygen of dry flue gas, dry air and water vapor is 0;
the derivative of the quantity of fuel with respect to the quantity of oxygen being 0
The derivative of the primary air quantity at the inlet of the air preheater of the boiler system to the oxygen quantity is 0.
7. The system for determining optimal oxygen content of a coal-fired boiler according to claim 5, wherein: the functional expression of boiler efficiency with respect to the derivative of oxygen is,
wherein, a and N1、N2、N3、N4M is the coefficient to be solved, O2The oxygen content of the boiler furnace outlet.
8. The system for determining optimal oxygen content of a coal-fired boiler according to claim 7, wherein: the coefficient to be calculated is calculated according to the formula,
N3＝21cp.fg.DEN.entfg,DEN.en(0.0333ωS.ar+0.2647ωH.ar-0.0334ωO.ar)+1.8648ωc.bcp.fg.DEN.entfg,DEN.en
wherein, O2AThe oxygen content of an air preheater of a boiler system is calculated, K is the air leakage rate of the air preheater, cp.fg.dIs the dry flue gas at the outlet of the air preheater with constant pressure and specific heat capacity tfg.AH.lvIs the outlet flue gas temperature t of the air preheaterreThe reference temperature is set to a reference temperature,
is the volume fraction of carbon monoxide in dry flue gas, omegaS.arIs the mass fraction of sulfur in the fuel entering the furnace, omegaH.arIs the mass fraction of hydrogen in the fuel charged to the furnace, omegaO.arIs the mass fraction of oxygen in the fuel entering the furnace, omegac.bThe mass fraction of carbon actually burned in the furnace fuel, ha.abAs absolute humidity of air, cp.wvFor the steam entering the boiler system at a constant pressure and specific heat capacity, cp.a.sFor secondary air entering the boiler system, t is the specific heat capacity at constant pressurea.sTemperature of secondary air, rho, for entering the boiler systema.sFor secondary air entering the boiler system, constant pressure and specific heat capacity, cp.a.reIs the specific heat capacity at constant pressure of air at a reference temperature, rhoa.reAir density at reference temperature, ta.pPrimary air temperature for entering boiler system, cp.fg.DEN.lvFor the constant pressure specific heat capacity of the flue gas at the outlet of the denitration device of the boiler system, cp.fg.DEN.enFor the inlet flue gas constant pressure specific heat capacity, t, of the denitration device of the boiler systemfg,DEN.lvFor the outlet flue gas temperature, t, of the denitrification devicefg,DEN.enFor the inlet flue gas temperature, omega, of the denitrating apparatusas.arIs the mass fraction of ash in the fuel entering the furnace, omegac.sIs the mass fraction of combustible material in the slag, omegac.asIs the mass fraction of combustible material in the fly ash, omegaN.arMass fraction of nitrogen, omega, in the fuel charged to the furnacem.arIs the mass fraction of the moisture in the fuel entering the furnace.
9. A computer readable storage medium storing one or more programs, characterized in that: the one or more programs include instructions that, when executed by a computing device, cause the computing device to perform any of the methods of claims 1-4.
10. A computing device, characterized by: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods of claims 1-4.
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