Method and system for determining flame center in furnace during deep air classification

文档序号：403492 发布日期：2021-12-17 浏览：26次中文

阅读说明：本技术 深度空气分级时炉内火焰中心确定方法与系统 (Method and system for determining flame center in furnace during deep air classification ) 是由赵振宁于 2021-08-31 设计创作，主要内容包括：本发明提供了一种深度空气分级时炉内火焰中心确定方法与系统。该方法包括：获取深度空气分级燃烧中主燃烧区单位量燃煤的实时放热量以及SOFA区单位量燃煤的实时放热量；获取主燃烧区中各燃烧器的给煤量和中心标高,以及,获取SOFA区补齐燃烧风用SOFA喷嘴的中心标高；获取炉膛高度以及深度空气分级燃烧中单位量燃煤的总放热量；基于所述主燃烧区单位量燃煤的实时放热量、SOFA区单位量燃煤的实时放热量、主燃烧区中各燃烧器的给煤量和中心标高、SOFA区补齐燃烧风用SOFA喷嘴的中心标高、炉膛高度以及深度空气分级燃烧中单位量燃煤的总放热量,确定火焰中心的相对高度。(The invention provides a method and a system for determining the flame center in a furnace during deep air classification. The method comprises the following steps: acquiring the real-time heat release of the unit amount of the coal in the main combustion area and the real-time heat release of the unit amount of the coal in the SOFA area in the deep air staged combustion; acquiring the coal feeding amount and the central elevation of each combustor in the main combustion area, and acquiring the central elevation of an SOFA nozzle for supplementing combustion air in the SOFA area; acquiring the total heat release of unit quantity of coal in the height of a hearth and deep air staged combustion; and determining the relative height of the flame center based on the real-time heat release of the unit amount of the fire coal in the main combustion area, the real-time heat release of the unit amount of the fire coal in the SOFA area, the coal feeding amount and the central elevation of each combustor in the main combustion area, the central elevation of the SOFA nozzle for the SOFA area to supplement the combustion air, the height of a hearth and the total heat release of the unit amount of the fire coal in the deep air staged combustion.)

1. A method for determining the flame center in a furnace during deep air classification, wherein the method comprises the following steps:

acquiring the real-time heat release of the unit amount of the coal in the main combustion area and the real-time heat release of the unit amount of the coal in the SOFA area in the deep air staged combustion;

acquiring the coal feeding amount and the central elevation of each combustor in the main combustion area, and acquiring the central elevation of an SOFA nozzle for supplementing combustion air in the SOFA area;

acquiring the total heat release of unit quantity of coal in the height of a hearth and deep air staged combustion;

and determining the relative height of the flame center based on the real-time heat release of the unit amount of the fire coal in the main combustion area, the real-time heat release of the unit amount of the fire coal in the SOFA area, the coal feeding amount and the central elevation of each combustor in the main combustion area, the central elevation of the SOFA nozzle for the SOFA area to supplement the combustion air, the height of a hearth and the total heat release of the unit amount of the fire coal in the deep air staged combustion.

2. The method of determining as claimed in claim 1, wherein the step of determining the relative height of the flame center based on the real-time heat release per unit coal in the main combustion zone, the real-time heat release per unit coal in the SOFA zone, the coal feed and center elevation of each burner in the main combustion zone, the center elevation of the SOFA nozzle for SOFA zone make-up combustion air, the furnace height, and the total heat release per unit coal in deep air staged combustion comprises:

based on the real-time heat release of the unit amount of the coal in the main combustion area, the real-time heat release of the unit amount of the coal in the SOFA area, the coal feeding amount and the central elevation of each combustor in the main combustion area, the central elevation of the SOFA nozzle for the SOFA area compensation combustion air, the height of a hearth and the total heat release of the unit amount of the coal in the deep air staged combustion, and the relative heights of the combustors and the integral combustor formed by the SOFA areas are determined by weighted average of the fuel amount and the heat generation amount in each combustor and the SOFA area;

the relative height of the flame center is determined based on the relative heights of the burners, the overall burner of the SOFA zone.

3. The determination method as claimed in claim 2, wherein the relative height of each burner, the overall burner of the SOFA zone is determined by the following formula:

in the formula, x_bThe relative height of the integral burner formed by each burner and the SOFA area; b is_iThe coal feeding quantity of the ith burner is kg; b is_JThe total coal feeding quantity of the hearth is kg; q_iThe real-time heat release of the unit amount of the coal in the main combustion area is kJ/(kg of coal); h is_biIs the center elevation, m, of the ith burner; q_jThe real-time heat release of the unit amount of fire coal in the SOFA area is kJ/(kg of fire coal); h is_bjThe center elevation m of the SOFA nozzle for the combustion air is supplemented for the SOFA area; h is_bIs the height of the hearth, m;the total heat release per unit coal in the deep air staged combustion is kJ/(kg coal).

4. The determination method according to claim 1, wherein a total heat release per unit amount of coal in the deep air staged combustion is determined using a heat generation amount per unit amount of coal completely burned into carbon dioxide in the deep air staged combustion.

5. The determination method of claim 1, wherein obtaining the real-time heat release for the primary combustion zone unit coal and the SOFA zone unit coal in the deep air staged combustion comprises:

acquiring total heat released by complete combustion of CO obtained by unit-amount coal combustion in a main combustion zone in deep air staged combustion;

obtaining the calorific value of carbon dioxide generated by the complete combustion of a unit amount of coal in deep air staged combustion;

determining the real-time heat release amount of the unit amount of the coal in the main combustion area in the deep air staged combustion based on the total heat released by the complete combustion of CO obtained by the unit amount of the coal in the main combustion area in the deep air staged combustion and the heat generation amount of carbon dioxide formed by the complete combustion of the unit amount of the coal in the deep air staged combustion;

and determining the real-time heat release amount of the coal of the SOFA area in the unit amount based on the total heat released by the complete combustion of CO obtained by the combustion of the coal of the unit amount in the main combustion area in the deep air staged combustion.

6. The determination method according to claim 5,

the real-time heat release of the unit amount of the coal in the main combustion area in the deep air staged combustion is determined based on the following formula:

in the formula, q_COThe total heat released by complete combustion of CO obtained by burning coal with unit amount in a main combustion area in deep air staged combustion is kJ/(kg coal);the calorific value is that the unit amount of the coal is completely combusted into carbon dioxide in deep air staged combustion, kJ/(kg of the coal); q_iIs deepThe real-time heat release of the unit amount of the coal in the main combustion area in the air staged combustion is kJ/(kg of the coal).

7. The determination method of claim 5, wherein the real-time heat release per unit coal fired of the SOFA area is determined based on the following equation:

Q_j＝q_CO

8. The determination method according to claim 5, wherein acquiring the total heat released by complete combustion of CO obtained from combustion of coal fired at a unit amount in the main combustion zone in the deep air staged combustion comprises:

acquiring an excess air coefficient of a main combustion area in deep air staged combustion;

acquiring the content of carbon element actually burnt from the received fire coal base;

and determining the total heat released by CO complete combustion obtained by burning the coal in the unit amount in the main combustion area in the deep air staged combustion based on the excess air coefficient of the main combustion area in the deep air staged combustion and the mass content of carbon elements received from the actual combustion of the coal.

9. The determination method of claim 5, wherein determining the total heat released by complete combustion of CO obtained from combustion of a single amount of coal in the main combustion zone in the deep air staged combustion based on the excess air factor of the main combustion zone in the deep air staged combustion and the mass content of carbon elements actually burned off based on the coal yield comprises:

when the excess air coefficient is larger than 1, the total heat released by complete combustion of CO obtained by unit-amount coal combustion in the main combustion zone in the deep air staged combustion is 0;

when the excess air ratio is not more than 1, the total heat released by complete combustion of CO obtained by combustion of a unit amount of coal in the main combustion zone in the deep air staged combustion is determined by the following formula:

in the formula, q_COThe total heat released by complete combustion of CO obtained by burning coal with unit amount in a main combustion area in deep air staged combustion is kJ/(kg coal);the mass percentage of carbon element which is actually burnt off is received by the coal; q_COThe calorific value of carbon monoxide per unit mass, kJ/kg; alpha is the excess air coefficient of the main combustion zone; k is a coefficient.

10. The determination method according to claim 9, wherein the value of k is determined by using the mass content of carbon elements actually burned based on the received coal, the excess air coefficient, the combustion rate and the theoretical dry air amount of a main combustion zone in deep air staged combustion; wherein the content of the first and second substances,

in the formula, alpha is the excess air coefficient of a main combustion area in the deep air staged combustion;the mass percentage of carbon element which is actually burnt off is received by the coal; v_a ⁰Theoretical amount of dry air, m³Per kg; λ is a combustion rate.

11. A system for in-furnace flame centering during deep air staging, wherein the system comprises:

a first obtaining module: the system is used for acquiring the real-time heat release of the unit quantity of the coal in the main combustion area and the real-time heat release of the unit quantity of the coal in the SOFA area in the deep air staged combustion;

a second obtaining module: the system is used for acquiring the coal feeding amount and the central elevation of each combustor in the main combustion area and acquiring the central elevation of the SOFA nozzle for the supplementary combustion air of the SOFA area;

a third obtaining module: the device is used for acquiring the total heat release of the unit quantity of the coal in the height of a hearth and the deep air staged combustion;

flame center height determination module: the relative height of the flame center is determined based on the real-time heat release of the unit amount of the fire coal in the main combustion area, the real-time heat release of the unit amount of the fire coal in the SOFA area, the coal feeding amount and the center elevation of each combustor in the main combustion area, the center elevation of the SOFA nozzle for the SOFA area complete combustion air, the height of a hearth and the total heat release of the unit amount of the fire coal in the deep air staged combustion.

12. The system of claim 11, wherein the flame center height determination module comprises:

a first height determination submodule: the system is used for determining the relative height of the whole combustor formed by each combustor and the SOFA area according to the weighted average of the fuel quantity and the heat productivity based on the real-time heat productivity of the single-amount coal in the main combustion area, the real-time heat productivity of the single-amount coal in the SOFA area, the coal feeding quantity and the central elevation of each combustor in the main combustion area, the central elevation of the SOFA nozzle for the SOFA area compensation combustion air, the height of a hearth and the total heat productivity of the single-amount coal in the deep air staged combustion;

a second height determination submodule: for determining the relative height of the flame center based on the relative heights of the burners, the overall burner of SOFA zone.

13. The system of claim 12, wherein the first height determination submodule is operable to determine the relative height of each burner, the overall burner of SOFA zones, by the formula:

14. The system of claim 11, wherein the third capture module is configured to determine a total heat release per unit coal in the deep air staged combustion using the heat generation per unit coal in the deep air staged combustion from complete combustion to carbon dioxide.

15. The system of claim 13, wherein the first acquisition module comprises:

a CO heat acquisition submodule: the device is used for obtaining the total heat released by complete combustion of CO obtained by unit-amount coal combustion in the main combustion zone in deep air staged combustion;

the coal-fired calorific capacity obtains submodule: the device is used for acquiring the calorific value of carbon dioxide generated by the complete combustion of coal in unit amount in deep air staged combustion;

a primary combustion zone heat determination submodule: the method is used for determining the real-time heat release amount of the unit amount of the coal in the main combustion area in the deep air staged combustion based on the total heat released by the complete combustion of CO obtained by the unit amount of the coal in the main combustion area in the deep air staged combustion and the heat generation amount of carbon dioxide formed by the complete combustion of the unit amount of the coal in the deep air staged combustion;

SOFA zone heat determination submodule: the method is used for determining the real-time heat release amount of the unit coal in the SOFA area based on the total heat released by the complete combustion of CO obtained by the unit coal combustion in the main combustion area in the deep air staged combustion.

16. The system of claim 15, wherein the primary combustion zone heat determination submodule is configured to determine a real-time heat release per unit coal charge for the primary combustion zone in deep air staged combustion based on the following equation:

in the formula, q_COThe total heat released by complete combustion of CO obtained by burning coal with unit amount in a main combustion area in deep air staged combustion is kJ/(kg coal);the calorific value is that the unit amount of the coal is completely combusted into carbon dioxide in deep air staged combustion, kJ/(kg of the coal); q_iThe real-time heat release of unit amount of coal in the main combustion area in the deep air staged combustion is kJ/(kg of coal).

17. The system of claim 15, wherein the SOFA zone heat determination sub-module is configured to determine a real-time heat release per unit coal fired by the SOFA zone based on the following equation:

Q_j＝q_CO

18. The system of claim 15, wherein the CO heat harvesting submodule comprises:

an excess air ratio obtaining unit: the system is used for acquiring the excess air coefficient of a main combustion area in the deep air staged combustion;

a burning carbon content acquisition unit: the method is used for acquiring the content of carbon element actually burnt from the received fire coal base;

a CO heat determination unit: the method is used for determining the total heat released by CO complete combustion obtained by burning coal in the unit amount in the main combustion area in the deep air staged combustion based on the excess air coefficient of the main combustion area in the deep air staged combustion and the mass content of carbon elements received from the actual combustion of the coal.

19. The system of claim 18, wherein the CO heat determination unit comprises:

a first CO heat determination subunit: determining the total heat released by complete combustion of CO obtained by unit-amount coal combustion in the main combustion zone in the deep air staged combustion to be 0 when the excess air coefficient is larger than 1;

the second CO heat determination subunit: determining the total heat released by complete combustion of CO obtained by combustion of coal fired at a unit amount in the main combustion zone in the deep air staged combustion by the following formula when the excess air ratio is not more than 1:

in the formula, q_COThe total heat released by complete combustion of CO obtained by burning coal with unit amount in a main combustion area in deep air staged combustion is kJ/(kg coal);the mass percentage of carbon element which is actually burnt off is received by the coal; q_COThe calorific value of carbon monoxide per unit mass, kJ/kg; alpha is the excess air coefficient of the main combustion zone; k is a coefficient.

20. The system of claim 19, wherein the second CO heat determination subunit is configured to determine the value of k using the mass content of carbon elements actually burned off from the coal burn, the excess air factor of the main combustion zone in deep air staged combustion, the combustion rate, and the theoretical dry air amount; wherein the content of the first and second substances,

Technical Field

The invention belongs to the technical field of boiler combustion, and particularly relates to a method and a system for determining the center of flame in a boiler during deep air classification.

Background

Deep air staged combustionThe technology is developed only in this century, and the technology can effectively realize NO_xThe method is widely applied in China due to the reduction of emission. At present, more than 90% of boilers in China complete the transformation of the deep air classification technology, and the safe and reliable application of the deep air classification technology is very important. The deep air staged combustion technique is to make the combustion firstly carried out under the condition of deep oxygen deficiency to inhibit NO_xAnd let NO already generated_xReduction to N₂Thereby minimizing NO_xThe concentration of (c); then, oxygen supplementation is carried out, so that the subsequent combustion is finished in an oxygen-enriched environment; since the temperature in this region has decreased, newly generated NO_xThe amount is very limited and therefore NO as a whole_xThe amount of emissions is significantly reduced.

The construction method of the deep air staged combustion technology comprises the following steps:

1) the air is fed in a grading way through a low NOx burner, such as thick-thin separation, air powder coating technology and the like, and a local oxygen-deficient combustion environment is constructed at the outlet of the burner;

2) the air distribution is carried out in a grading way on the vertical height of a hearth by utilizing the matching of different burners, namely, the air distribution is carried out only for 75-100% of the air quantity required for combustion (the excess coefficient is controlled to be about 0.75-1.0) near the area of a main burner (a burner for feeding coal powder), the coal powder is subjected to oxygen-deficient combustion in the area remarkably and widely, then, residual air is introduced above the main burner, and the residual coal powder is subjected to complete combustion in the area under the oxygen-enriched condition. Among these, air fed against the main burner area is referred to as overfire OFA (over fire air), and if the overfire OFA is a significant distance from the main burner area, it is referred to as separated overfire sofa (separated over fire air).

The deep air staging technique generally employs separate overfire SOFA, expands the range to near the entire furnace by staged combustion of air, more closely limits the residence time of fuel in the oxygen deficient zone, and lowers the temperature of the oxygen rich zone to a lower level. A typical burner arrangement is now shown in figure 1.

From a design perspective, deep air staging low NO_xCompared with traditional combustion technology, the combustion technology is coalThe exothermic behavior of the powder in the hearth is significantly different:

1) the oxygen content of the main combustion area of the traditional hearth is sufficient, and the pulverized coal is finely ground; in the traditional combustion technology, about 96% of components of pulverized coal at the outlet of a main combustor can be combusted; slightly higher than 96% when the combustion condition is good, and slightly lower than 96% when the combustion condition is poor; particularly reflecting on the combustible content of fly ash and slag. The height of the flame at the outlet of each burner, i.e. the point in the flame stream torch from which the coal flame is burned at the highest combustion temperature, is usually slightly above the burner outlet;

2) deep air staging low NO_xIn the combustion technology, although pulverized coal is still finely ground, because the components of an oxidant for combustion are seriously lacked, the components for instantly finishing combustion at the outlet of a main combustor are far lower than 96 percent, so the highest point of the flame temperature behind the outlet of each combustor is never slightly higher than the position above the outlet of the combustor;

the boiler furnace is a radiation type heat exchange surface, and the flame temperature is very important for the heat exchange of the furnace. The heat release behavior of the pulverized coal entering the boiler is changed greatly and should be reflected correspondingly in the design of a hearth, and unfortunately, the deep air classification is low in NO_xThe combustion technology is developed too fast, and at present, only the traditional design concept can be applied to carry out corresponding work. To ensure compliance with practice, it is common practice to modify the calculation results by empirical coefficients.

The position of the highest flame temperature point is very important and is the basis of the design of the whole hearth. In the design of boiler furnace, a coefficient M is used to represent the height of flame of furnace, which is related to the combustion mode, burner arrangement and the like, such as the furnace outlet temperature calculation formula in the power station boiler thermodynamic calculation standard (73 rd edition) which has been widely applied in China:

in the formula: theta'_fThe temperature of the outlet of the hearth is required to be solved and calculated; t is_aIs the theoretical combustion temperature of the coal, i.e. combustionAfter the coal is combusted, only the temperature to which the flue gas generated by the coal can be heated is heated without heat transfer, namely the theoretical combustion temperature; f_fThe heating area of the furnace chamber; sigma₀Is the stigman constant; a is_fThe furnace blackness is a comprehensive factor calculated by various parameters such as boiler structure, flame temperature and the like; psi is the ash and dirt coefficient of the hearth, and is found according to the data such as the structure of the hearth; b is_jThe amount of fuel fed into the boiler per unit time minus the amount of fuel discharged out of the boiler in the form of ash;the heat preservation coefficient is the ratio of the part of the flame heat energy transferred to the steam-water working medium to heat and boost the working medium;the average heat capacity of the flue gas generated by unit mass of fuel between the flame temperature in the furnace and the outlet temperature of the hearth; m is the part of the flame center in the hearth.

The furnace outlet temperature in the formula (1) is the calculated heat transfer quantity in the furnace, and is equal to the heat transfer quantity in the furnace in terms of dataThe hearth is a first-stage heating surface of the boiler along a flue gas flow, and the accurate calculation of the hearth is the basis for accurately calculating all other heating surfaces, namely the basis for designing and calculating the whole boiler.

Among the factors of formula (1), the three most primitive determinants are: the fuel, the structure and area of the furnace, and the location of the flame temperature within the furnace. The fuel being present at the theoretical combustion temperature T_aIn the middle, the structure and area of the hearth are embodied in F_fAnd furnace blackness alpha_fThe flame temperature is represented in the furnace at a location in the M value, which is generally related to the location of the burner.

A single burner cannot support a large capacity boiler of a modern power station, typically in a multi-burner arrangement. Burner arrangement form of traditional boiler main burner and current deep air classification low NO_xBurner for combustion technologyThe arrangement mode is shown in fig. 2 (wherein, a is a schematic diagram of equal air distribution mode suitable for inflammable coal types, b is a schematic diagram of deep air classification equal air distribution mode suitable for inflammable coal types, c is a schematic diagram of classification equal air distribution mode suitable for difficult-to-burn coal types, and d is a schematic diagram of deep air classification equal air distribution mode suitable for difficult-to-burn coal types).

As can be seen from FIG. 2, deep air staging low NO_xThe differences in combustion technology from conventional burner arrangements are mainly:

1) the primary air burner nozzle area of the main combustion area is unchanged;

2) the secondary air burner of the main combustion zone has a constant width but a reduced height;

3) the nozzle area of the secondary air burner is reduced, so that the primary air burner is integrally moved downwards.

In the conventional burner arrangement, all secondary air is injected from adjacent primary air burners, so that the whole main combustion area is in an oxygen-enriched condition, the position of a little bit after the outlet of each burner is the position where the flue gas combustion is most vigorous, and the flame height of a hearth can be weighted and averaged by the positions of all the burners in the hearth.

In order to indicate the relative position of a burner at the furnace height by means of a datum, the same height x of the burner is generally used_bTo show that:

in the formula: h is_bIs the elevation of the burner (as shown in fig. 3); h is_FIs the furnace height (as shown in figure 3).

For a plurality of burners, the relative height of the overall burner formed by each burner is weighted and averaged according to the amount of fuel in the burner, i.e.

In the formula: b is_iIs the ith burner (i.e. FIG. 2)The primary air burners with the number 1 on the middle and left) are started; h is_biIs the ith burner center elevation, m;

the combustion amount of each burner outlet is weighted and averaged, namely the real-time heat release amount of each burner outlet is actually weighted and averaged by considering the heat release amount of the fed combustion and the immediate combustion.

The relative height of the burner is reflected to the height of the flame center:

x_flm＝x_b+ Δ x type (4)

In the formula: x is the number of_flmThe relative height of the flame center; x is the number of_bThe relative height of the burner is the ratio of the central elevation of the burner to the height of the hearth, and is calculated by the formula (2) and the formula (3); Δ x is the correction that the burner type and operating mode causes to the flame center. Δ x is related to the combustion mode and the temperature regulation mode of the boiler; when the boiler adopts the tangential firing mode, adjust reheat steam temperature with the pendulum combustor usually, the furnace export arranges screen reheater, high temperature reheater and high temperature superheater (high temperature reheater or wall reheater are preceding) usually in proper order, has arranged low temperature superheater and economizer in afterbody shaft flue top-down, and delta x is relevant with the swing angle this moment:

1) Δ x is 0 at burner level;

2) when the burner swings upwards, the delta x increases by 0.1 every time the burner swings 20 degrees;

3) when the burner swings downwards, the delta x is reduced by 0.1 every time the burner swings 20 degrees;

4) when the burner swings up and down at other angles, the inserted value of deltax is taken.

If adopt the front wall to arrange or the hedging combustion mode, the combustor can't swing usually, can adjust the reheat steam temperature with the flue gas baffle of afterbody, the furnace export arranges screen formula high temperature over heater, medium temperature re-heater and high temperature over heater in proper order (high temperature re-heater is back), and the tangent circle burning arranges low temperature over heater and low temperature re-heater side by side in afterbody shaft flue, but arrange low temperature re-heater and economizer side by side, the flame center at this moment is fixed relatively, mainly depend on the evaporation capacity, promptly:

1) when D is less than or equal to 116kg/s or 420t/h, Delta x is 0.1;

2) when D is larger than 116kg/s or 420t/h, Delta x is 0.05.

After the flame center height is obtained according to the structural parameters of the burner, the M value can be obtained, and then the outlet temperature of the hearth is calculated through the formula (1). The method for determining the M value in 73 years edition of Standard for thermodynamic engineering of utility boilers comprises the following steps:

in the formula: v_dafIs a dry ashless based volatile component of the fuel;

from the formula (5), when V of the fuel is_dafAfter more than 20%, the flame length is long, the combustion center is at the higher position of the outlet of the burner nozzle, so the M value is reduced by 0.59, and the calculated M value is larger; on the contrary, when the V of the fuel_dafAfter less than 20%, the flame is short and thick, the combustion center of the flame is at the lower position of the outlet of the nozzle of the combustor, so that the M value is reduced by 0.56, and the calculated M value is smaller; the M value reflects the relative position of the flame center in the furnace.

From the above description, it can be seen that in the thermodynamic calculation of the utility boiler, the obtaining of the variable of the furnace flame center height needs to be considered carefully, and factors such as swinging an angle and the like which have small differences in practical application are fully considered. However, all implicit assumptions in the above process are that coal is combusted under oxygen-rich conditions, i.e., the amount of heat released at each burner outlet is related only to its fuel quantity. In the case of oxygen deficient combustion, when the air at the burner outlet is insufficient, the combustion actually taking place varies greatly, although the combustion quantity is still so much that it is fed: 1kg of carbon element is burnt into CO₂The heat quantity is 33727kJ, the heat quantity of CO formed by combustion is only 4635kJ and is only 7.3 times of that of complete combustion, and the influence of the heat quantity on the flame center is subversive and influenced by applying a model which is supposed to finish the one-time complete combustion of fuel in the prior art. If the outlet of the burner is pure carbon powder, the burner can burn under the condition that the excess air coefficient is more than 1The heat release is 33727 kJ; when the excess air coefficient is 0.8, the heat release quantity at a point of the outlet of the burner is 0.6 multiplied by 33727 plus 0.4 multiplied by 4635 which is 22090kJ, and only 65 percent of the heat release quantity is released under the oxygen-enriched condition.

Disclosure of Invention

The invention aims to provide a method and a system for determining the flame center in a furnace during deep air classification so as to determine that fuel is in low NO_xUnder the condition of oxygen-deficient combustion (at the moment, the combustion heat release of the combustor is greatly reduced), the flame height in the hearth.

In order to achieve the above object, in a first aspect, the present invention provides a method for determining a flame center in a furnace during deep air classification, wherein the method comprises:

acquiring the real-time heat release of the unit amount of the coal in the main combustion area and the real-time heat release of the unit amount of the coal in the SOFA area (separated fire upwind area) in the deep air staged combustion;

acquiring the total heat release of unit quantity of coal in the height of a hearth and deep air staged combustion;

and determining the relative height of the flame center (the elevation of the flame center relative to the height of the hearth) based on the real-time heat release of the unit amount of the fire coal in the main combustion area, the real-time heat release of the unit amount of the fire coal in the SOFA area, the coal feeding amount and the central elevation of each combustor in the main combustion area, the central elevation of the SOFA nozzle for the SOFA area compensation combustion air, the height of the hearth and the total heat release of the unit amount of the fire coal in the deep air staged combustion.

In a second aspect, the present invention also provides a system for determining the flame center in a furnace during deep air staging, wherein the system comprises:

a third obtaining module: the device is used for acquiring the total heat release of the unit quantity of the coal in the height of a hearth and the deep air staged combustion;

flame center height determination module: the method is used for determining the relative height of the flame center (the elevation of the flame center relative to the height of a hearth) based on the real-time heat release of the unit amount of fire coal in the main combustion area, the real-time heat release of the unit amount of fire coal in the SOFA area, the coal feeding amount and the center elevation of each combustor in the main combustion area, the center elevation of the SOFA nozzle for SOFA area compensation combustion air, the height of the hearth and the total heat release of the unit amount of fire coal in the deep air staged combustion.

The technical scheme provided by the invention can well realize the determination of low NO of the fuel_xThe flame height in the furnace under the condition of oxygen-deficient combustion is used for the design calculation and the operation control of the deep air staged combustion furnace.

Drawings

FIG. 1 shows deep air staged burner arrangement in a furnace with NO_xSchematic diagram of concentration distribution.

FIG. 2 is a diagram of a conventional burner arrangement with deep air staging for low NO_xThe combustion technology arrangement is compared with a schematic diagram.

FIG. 3 is a schematic view of relative elevation of the combustor.

FIG. 4 is a flow chart illustrating a method for determining the flame center in a furnace during deep air staging according to an embodiment of the present invention.

Fig. 5 is a schematic diagram of an optimized flow of a method for determining a flame center in a furnace during deep air classification according to an embodiment of the present invention.

FIG. 6 is a schematic diagram of the structure of a system for determining the flame center in a furnace during deep air staging according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in detail and completely with reference to the drawings in the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all 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.

In the invention, the elevation refers to the height relative to the central line of the hearth ash cooling bucket, namely, the reference surfaces of the elevation are the central lines of the hearth ash cooling bucket.

The principles and spirit of the present invention are explained in detail below with reference to several representative embodiments of the invention.

Referring to fig. 4, the present invention provides a method for determining a flame center in a furnace during deep air classification, wherein the method comprises:

step S1: acquiring the real-time heat release of the unit amount of the coal in the main combustion area and the real-time heat release of the unit amount of the coal in the SOFA area (separated fire upwind area) in the deep air staged combustion;

step S2: acquiring the coal feeding amount and the central elevation of each combustor in the main combustion area, and acquiring the central elevation of an SOFA nozzle for supplementing combustion air in the SOFA area;

step S3: acquiring the total heat release of unit quantity of coal in the height of a hearth and deep air staged combustion;

step S4: and determining the relative height of the flame center (the elevation of the flame center relative to the height of the hearth) based on the real-time heat release of the unit amount of the coal in the main combustion area, the real-time heat release of the unit amount of the coal in the SOFA area, the coal feeding amount and the central elevation of each combustor in the main combustion area, the central elevation of the SOFA nozzle for the SOFA area compensation combustion air, the height of the hearth and the total heat release of the unit amount of the coal in the deep air staged combustion.

During deep air staged combustion, the SOFA area is used as a virtual burner taking CO as fuel, the rapidity of CO combustion is far greater than that of pulverized coal, and the center of a flame of CO combustion is positioned near the SOFA nozzle for supplementing combustion air of the SOFA area.

The SOFA nozzle for supplementing combustion wind in the SOFA region refers to a SOFA nozzle for supplementing combustion wind, and does not include a SOFA nozzle for supplying excessive fuel wind used after the combustion wind is supplemented.

In one embodiment, if there is more than one SOFA nozzle for the SOFA area supplementary combustion air, the SOFA nozzles for the SOFA area supplementary combustion air may be regarded as a whole, and the center elevation thereof may be determined.

In one embodiment, step S4 includes:

step S41: determining the relative height of the integral combustor formed by each combustor and the SOFA area based on the real-time heat release of the unit amount of the coal in the main combustion area, the real-time heat release of the unit amount of the coal in the SOFA area, the coal feeding amount and the central elevation of each combustor in the main combustion area, the central elevation of the SOFA nozzle for the SOFA area to supplement combustion air, the height of a hearth and the total heat release of the unit amount of the coal in the deep air staged combustion;

step S42: determining the relative height of the flame center based on the relative heights of the burners and the overall burner formed by the SOFA area;

further, step S41 includes:

further, the relative height of each burner, the overall burner of the SOFA zone, is determined by the following equation:

in the formula, x_bThe relative height of the integral burner formed by each burner and the SOFA area; b is_iThe coal feeding quantity of the ith burner is kg; b is_JThe total coal feeding amount of the hearth (namely the sum of the coal feeding amounts of all the burners) is kg; q_iThe real-time heat release of the unit amount of the coal in the main combustion area is kJ/(kg of coal); h is_biIs the center elevation, m, of the ith burner; q_jThe real-time heat release of the unit amount of fire coal in the SOFA area is kJ/(kg of fire coal); h is_bjThe center elevation m of the SOFA nozzle for the combustion air is supplemented for the SOFA area; h is_bIs the height of the hearth, m;the total heat release of each unit amount of fire coal in the deep air staged combustion is kJ/(kg of fire coal);

further, in step S42, the relative height of the flame center is determined by the following formula:

x_flm＝x_b+Δx

in the formula, x_flmThe relative height of the flame center; x is the number of_bThe relative height of the integral burner formed by each burner and the SOFA area; Δ x is the correction of the relative height of the flame center;

further, Δ x is related to the swing angle:

1) Δ x is 0 at burner level;

2) when the burner swings upwards, the delta x increases by 0.1 every time the burner swings 20 degrees;

3) when the burner swings downwards, the delta x is reduced by 0.1 every time the burner swings 20 degrees;

4) when the burner swings up and down at other angles, the inserted value of deltax is taken.

In one embodiment, the total heat release per unit amount of coal in the deep air staged combustion is determined by the heat generation per unit amount of coal in the deep air staged combustion completely burned into carbon dioxide;

further, the total heat release per unit amount of coal in the deep air staged combustion is determined using the following formula:

In one embodiment, step S1 includes:

step S11: acquiring total heat released by complete combustion of CO obtained by unit-amount coal combustion in a main combustion zone in deep air staged combustion;

step S12: obtaining the calorific value of carbon dioxide generated by the complete combustion of a unit amount of coal in deep air staged combustion;

step S13: determining the real-time heat release amount of the unit amount of the coal in the main combustion area in the deep air staged combustion based on the total heat released by the complete combustion of CO obtained by the combustion of the unit amount of the coal in the main combustion area in the deep air staged combustion and the heat generation amount of carbon dioxide obtained by the complete combustion of the unit amount of the coal in the deep air staged combustion;

step S14: determining the real-time heat release amount of the unit amount of coal in the SOFA area based on the total heat released by the complete combustion of CO obtained by the unit amount of coal in the main combustion area in the deep air staged combustion;

further, the real-time heat release per unit coal charge of the main combustion zone in the deep air staged combustion is determined based on the following formula:

in the formula, q_COThe total heat released by complete combustion of CO obtained by burning coal with unit amount in a main combustion area in deep air staged combustion is kJ/(kg coal);the calorific value of carbon dioxide obtained by completely burning coal per unit amount in deep air staged combustion is kJ/(kg coal);Q_ithe real-time heat release of unit amount of coal in a main combustion area in deep air staged combustion is kJ/(kg of coal);

further, the real-time heat release per unit coal fired of the SOFA area is determined based on the following equation:

Q_j＝q_CO

Referring to fig. 5, in a specific embodiment, step S11 includes:

step S111: acquiring an excess air coefficient of a main combustion area in deep air staged combustion;

step S112: acquiring the content of carbon element actually burnt from the received fire coal base;

step S113: determining the total heat released by complete combustion of CO obtained by burning coal with unit amount in the main combustion area in the deep air staged combustion based on the excess air coefficient of the main combustion area in the deep air staged combustion and the mass content of carbon element received from the coal and actually burnt;

further, step S113 includes:

step S1131: when the excess air coefficient is greater than 1, the total heat released by complete combustion of CO obtained by burning coal of unit amount in the main combustion zone in deep air staged combustion is 0;

step S1132: when the excess air coefficient is not more than 1, the total heat released by complete combustion of CO obtained by burning coal at the unit amount in the main combustion zone in the deep air staged combustion is determined by the following formula:

in the formula, q_COThe total heat released by complete combustion of CO obtained by burning coal with unit amount in a main combustion area in deep air staged combustion is kJ/(kg coal);the percentage of the carbon element which is actually burnt off is received by the fire coal; q_COThe calorific value of carbon monoxide per unit mass, kJ/kg; alpha is the excess air coefficient of the main combustion zone; k is a coefficient;

furthermore, the value of k is determined by utilizing the mass content of carbon elements actually burnt by the received fire coal, the excess air coefficient, the combustion rate and the theoretical dry air amount of a main combustion zone in deep air staged combustion; for example,

in the formula, alpha is the excess air coefficient of a main combustion area in the deep air staged combustion;the mass percentage of carbon element which is actually burnt and is obtained from the coal;theoretical amount of dry air, m³Per kg; λ is the combustion rate (e.g., 96%).

The actual combustion heat release of coal under the condition of oxygen deficiency has a great relationship with the excess air coefficient for the coal; the meaning of the excess air ratio is the ratio of the air actually involved in the combustion to the air required for complete combustion, with deep air staging to low NO_xIt is the basis when designing combustion technology, it is an important means of operational control in operational control, also a control target, and it is therefore feasible to determine the actual heat release by the excess air factor at the burner outlet; when the optimal technical scheme is used, the k value of the same coal can be taken as a fixed value, and after the k value is determined, the heat release of the main combustion area and the SOFA area can be determined according to the optimal technical scheme, so that the flame center of the hearth can be better determined.

Wherein the carbon element content actually burned off from the coal receiving base is preferably determined based on the following formula:

in the formula, C_arThe mass percentage of the carbon element received by the fire coal is percent; c_f,asIs the mass percentage of carbon element in the fly ash; c_s,asThe mass percentage of carbon element in the large slag is percent; r is_f,asThe mass percentage of the ash in the fly ash to the total ash of the fire coal is percent; r is_s,asThe mass percentage of the ash in the large slag to the total ash of the fire coal is percent; a. the_arThe mass content percentage of the base ash obtained by the coal is percent;the mass percentage of carbon element actually burnt for receiving the base coal is percent.

Among them, the theoretical dry air amount is preferably determined based on the following formula:

wherein the content of the first and second substances,

in the formula (I), the compound is shown in the specification,m is theoretical dry air amount (theoretical dry air amount required per kg of coal combustion)³/kg；H_arThe mass percentage of the basic hydrogen element received by the fire coal is percent; o is_arThe mass percentage of the oxygen-based element received by the fire coal is percent; s_arThe mass percentage of the basic sulfur element received by the fire coal is percent;mass percentage of carbon element actually burned for coal receiving base，％；C_arThe mass percentage of the carbon element received by the fire coal is percent; c_f,asIs the mass percentage of carbon element in the fly ash; c_s,asThe mass percentage of carbon element in the large slag is percent; r is_f,asThe mass percentage of the ash in the fly ash to the total ash of the fire coal is percent; r is_s,asThe mass percentage of the ash in the large slag to the total ash of the fire coal is percent; a. the_arThe percentage of the mass content of the received base ash of the fire coal is percent;

the preferred embodiment requires an on-line instrument for coal quality elemental analysis to be set up in operation, or elemental analysis data results for the design coal type at the design stage.

Wherein the theoretical dry air quantity is preferably determined by the low-level calorific value of coal according to a DL/904-2015 economic and technical index calculation method of the thermal power plant; the method is specifically carried out based on the following formula:

in the formula (I), the compound is shown in the specification,m is theoretical dry air amount (theoretical dry air amount required per kg of coal combustion)³Per kg; k is a coefficient related to coal types, and the value of K refers to the standard DL/T904-2015 of the power industry; q_net.arThe coal receives a base low heating value kJ/kg.

Among them, the calorific value per unit amount of coal completely combusted into carbon dioxide in the deep air staged combustion is preferably determined based on the following formula:

in the formula (I), the compound is shown in the specification,the calorific value of carbon dioxide generated by the complete combustion of unit amount of coal is kJ/(kg of coal); q_net.arFor coal burningLow calorific value, kJ/(kg coal); c_f,asIs the mass percentage of carbon element in the fly ash; c_s,asThe mass percentage of carbon element in the large slag is percent; r is_f,asThe mass portion percentage of the ash in the fly ash to the total ash of the fire coal is percent; r is_s,asThe mass percentage of the ash in the large slag to the total ash of the fire coal is percent; a. the_arThe mass percentage of the received basic ash of the fire coal is percent.

In one embodiment, the excess air ratio of each burner in the main combustion zone in deep air staged combustion is uniform, typically between 0.8 and 0.95. The air excess factor means the ratio of the air actually involved in combustion to the air required for complete combustion, with deep air staging to low NO_xThe combustion technology is the basis when it is designed, and it is an important means of operation control and a control target when the operation control is performed.

In a specific embodiment, the mass percentage of the base hydrogen element received by the fire coal, the mass percentage of the base oxygen element received by the fire coal, the mass percentage of the base sulfur element received by the fire coal, the mass percentage of the base carbon element received by the fire coal, the mass percentage of the base nitrogen element received by the fire coal, the mass percentage of the base ash received by the fire coal and the mass percentage of the base ash received by the fire coal are obtained through coal sampling and testing.

In one embodiment, the mass percentage of carbon in fly ash, the mass percentage of carbon in slag, the mass fraction of ash in fly ash to the total ash content of the coal, and the mass fraction of ash in slag to the total ash content of the coal are measured by a loss on ignition method.

In one embodiment, the heating value per unit mass of carbon monoxide is 10108 kJ/kg.

The embodiment of the invention also provides a system for determining the flame center in the furnace during deep air classification, and the system is preferably used for realizing the method embodiment.

FIG. 6 is a block diagram showing the structure of a system for determining the flame center in a furnace during deep air classification according to an embodiment of the present invention, as shown in FIG. 6, the system comprising:

the first acquisition module 51: the system is used for acquiring the real-time heat release quantity of the unit quantity of the coal in the main combustion area and the real-time heat release quantity of the unit quantity of the coal in the SOFA area (separation fire upwind area) in the deep air staged combustion;

the second obtaining module 52: the system is used for acquiring the coal feeding amount and the central elevation of each combustor in the main combustion area and acquiring the central elevation of the SOFA nozzle for the supplementary combustion air of the SOFA area;

the third obtaining module 53: the device is used for acquiring the total heat release of the unit quantity of the coal in the height of a hearth and the deep air staged combustion;

flame center height determination module 54: the method is used for determining the relative height of the flame center (the elevation of the flame center relative to the height of a hearth) based on the real-time heat release of the unit amount of the fire coal in the main combustion area, the real-time heat release of the unit amount of the fire coal in the SOFA area, the coal feeding amount and the center elevation of each combustor in the main combustion area, the center elevation of the SOFA nozzle for the SOFA area compensation combustion air, the height of the hearth and the total heat release of the unit amount of the fire coal in the deep air staged combustion.

In one embodiment, the flame center height determination module 54 includes:

first height determination submodule 541: the relative height of the integral combustor formed by each combustor and the SOFA area is determined based on the real-time heat release of the unit amount of the coal in the main combustion area, the real-time heat release of the unit amount of the coal in the SOFA area, the coal feeding amount and the central elevation of each combustor in the main combustion area, the central elevation of the SOFA nozzle for the SOFA area complete combustion wind, the height of a hearth and the total heat release of the unit amount of the coal in the deep air staged combustion;

the second height determination submodule 542: the relative height of the flame center is determined based on the relative heights of the burners and the overall burner formed by the SOFA area;

further, the first height determining submodule 541 is configured to determine, based on the real-time heat release amount per unit amount of coal in the main combustion area, the real-time heat release amount per unit amount of coal in the SOFA area, the coal feed amount and the center elevation of each combustor in the main combustion area, the center elevation of the SOFA nozzle for SOFA area complementary combustion air, the height of the furnace, and the total heat release amount per unit amount of coal in deep air staged combustion, the relative heights of the combustors and the overall combustor formed by the SOFA areas in each combustor and the SOFA area are weighted and averaged according to the fuel amount and the heat generation amount;

further, the first height determination submodule 541 is configured to determine the relative height of each burner, the overall burner of the SOFA zone, by the following equation:

in the formula, x_bThe relative height of the integral burner formed by each burner and the SOFA area; b is_iThe coal feeding quantity of the ith burner is kg; b is_JThe total coal feeding amount of the hearth (namely the sum of the coal feeding amounts of all the burners) is kg; q_iThe real-time heat release of the unit amount of the coal in the main combustion area is kJ/(kg of coal); h is_biIs the center elevation, m, of the ith burner; q_jThe real-time heat release of the unit amount of fire coal in the SOFA area is kJ/(kg of fire coal); h is_bjThe center elevation m of the SOFA nozzle for the combustion air is supplemented for the SOFA area; h is_bIs the height of the hearth, m;the total heat release of each unit amount of fire coal in the deep air staged combustion is kJ/(kg of fire coal);

further, the second height determination submodule 542 is operable to determine the relative height of the flame center by:

x_flm＝x_b+Δx

further, Δ x is related to the swing angle:

1) Δ x is 0 at burner level;

2) when the burner swings upwards, the delta x increases by 0.1 every time the burner swings 20 degrees;

3) when the burner swings downwards, the delta x is reduced by 0.1 every time the burner swings 20 degrees;

4) when the burner swings up and down at other angles, the inserted value of deltax is taken.

In one embodiment, the third obtaining module 53 is configured to determine a total heat release per unit coal in the deep air staged combustion by using a heat generation amount per unit coal in the deep air staged combustion when the unit coal is completely combusted into carbon dioxide;

further, the third obtaining module 53 is configured to determine a total heat release per unit coal in the deep air staged combustion using the following formula:

In a specific embodiment, the first obtaining module 51 includes:

CO heat harvesting submodule 511: the device is used for obtaining the total heat released by complete combustion of CO obtained by the combustion of coal with unit quantity in the main combustion area in the deep air staged combustion;

coal-fired calorific power acquisition submodule 512: the device is used for acquiring the calorific value of carbon dioxide generated by the complete combustion of coal in unit amount in deep air staged combustion;

the primary combustion zone heat determination submodule 513: the method is used for determining the real-time heat release amount of the main combustion area single-amount coal in the deep air staged combustion based on the total heat released by the complete combustion of CO obtained by the combustion of the main combustion area single-amount coal in the deep air staged combustion and the heat generation amount of carbon dioxide formed by the complete combustion of the single-amount coal in the deep air staged combustion;

SOFA zone heat determination submodule 514: the system is used for determining the real-time heat release amount of the unit amount of coal in the SOFA area based on the total heat released by the complete combustion of CO obtained by the unit amount of coal in the main combustion area in the deep air staged combustion;

further, the primary combustion zone heat determination submodule 513 is operable to determine a real-time heat release per unit coal charge for the primary combustion zone in deep air staged combustion based on the following equation:

in the formula, q_COThe total heat released by complete combustion of CO obtained by burning coal with unit amount in a main combustion area in deep air staged combustion is kJ/(kg coal);the calorific value of carbon dioxide obtained by completely burning coal per unit amount in deep air staged combustion is kJ/(kg coal); q_iThe real-time heat release of unit amount of coal in a main combustion area in deep air staged combustion is kJ/(kg of coal);

further, the SOFA zone heat determination submodule 514 is operable to determine a real-time heat release per unit coal fired for the SOFA zone based on the following equation:

Q_j＝q_CO

In one embodiment, the CO heat harvesting submodule 511 includes:

excess air ratio acquisition unit 5111: the method is used for acquiring the excess air coefficient of a main combustion area in the deep air staged combustion;

the burned carbon content acquisition unit 5112: the method is used for acquiring the content of carbon element actually burnt from the received fire coal base;

CO heat amount determination unit 5113: the method is used for determining the total heat released by complete combustion of CO obtained by burning the main combustion area unit amount of fire coal in the deep air staged combustion based on the excess air coefficient of the main combustion area in the deep air staged combustion and the mass content of carbon elements received by the fire coal and actually burnt;

further, the CO heat amount determination unit 5113 includes:

first CO heat determination subunit 51131: determining the total heat released by complete combustion of CO obtained by unit-amount coal combustion in the main combustion zone in the deep air staged combustion to be 0 when the excess air coefficient is larger than 1;

second CO heat determination subunit 51132: and (c) determining the total heat released by complete combustion of CO obtained by combustion of coal fired at a unit amount in the main combustion zone in the deep air staged combustion by the following formula when the excess air ratio is not more than 1:

in the formula, q_COThe total heat released by complete combustion of CO obtained by burning coal with unit amount in a main combustion area in deep air staged combustion is kJ/(kg coal);the percentage of the carbon element which is actually burnt off is received by the fire coal; q_COThe calorific value of carbon monoxide per unit mass, kJ/kg; alpha is the excess air coefficient of the main combustion zone; k is a coefficient;

further, the second CO heat determination subunit 51132 is configured to determine a value of k using the mass content of carbon element actually burned from the received coal, the excess air coefficient of the main combustion zone in the deep air staged combustion, the combustion rate, and the theoretical dry air amount; for example,

wherein alpha is deep air staged combustionExcess air ratio of the intermediate main combustion zone;the mass percentage of carbon element which is actually burnt and is obtained from the coal;theoretical amount of dry air, m³Per kg; λ is the combustion rate (e.g., 96%).

Wherein the carbon element content actually burned off from the coal receiving base is preferably determined based on the following formula:

Among them, the theoretical dry air amount is preferably determined based on the following formula:

wherein the content of the first and second substances,

in the formula (I), the compound is shown in the specification,m is theoretical dry air amount (theoretical dry air amount required per kg of coal combustion)³/kg；H_arThe mass percentage of the basic hydrogen element received by the fire coal is percent; o is_arThe mass percentage of the oxygen-based element received by the fire coal is percent; s_arThe mass percentage of the basic sulfur element received by the fire coal is percent;the mass percentage of carbon element which is actually burnt off is received by the coal; c_arThe mass percentage of the carbon element received by the fire coal is percent; c_f,asIs the mass percentage of carbon element in the fly ash; c_s,asThe mass percentage of carbon element in the large slag is percent; r is_f,asThe mass percentage of the ash in the fly ash to the total ash of the fire coal is percent; r is_s,asThe mass percentage of the ash in the large slag to the total ash of the fire coal is percent; a. the_arThe percentage of the mass content of the received base ash of the fire coal is percent;

the preferred embodiment requires an on-line instrument for coal quality elemental analysis to be set up in operation, or elemental analysis data results for the design coal type at the design stage.

Among them, the calorific value per unit amount of coal completely combusted into carbon dioxide in the deep air staged combustion is preferably determined based on the following formula:

in the formula (I), the compound is shown in the specification,the calorific value of carbon dioxide generated by the complete combustion of unit amount of coal is kJ/(kg of coal); q_net.arThe coal receives basic low-level heating value kJ/(kg coal); c_f,asIs the mass percentage of carbon element in the fly ash; c_s,asThe mass percentage of carbon element in the large slag is percent; r is_f,asThe mass portion percentage of the ash in the fly ash to the total ash of the fire coal is percent; r is_s,asThe mass percentage of the ash in the large slag to the total ash of the fire coal is percent; a. the_arThe mass percentage of the received basic ash of the fire coal is percent.

In one embodiment, the heating value per unit mass of carbon monoxide is 10108 kJ/kg.

Example 1

The present embodiment provides a method for determining a flame center in a furnace during deep air classification, in which the furnace during deep air classification is shown in (b) of fig. 2, wherein the method includes:

1. acquiring the real-time heat release of the unit amount of the coal in the main combustion area and the real-time heat release of the unit amount of the coal in the SOFA area (separated fire upwind area) in the deep air staged combustion;

the real-time heat release of the unit amount of the fire coal in the main combustion area and the real-time heat release of the unit amount of the fire coal in the SOFA area (separation fire upwind area) in the deep air staged combustion are determined by the following methods:

in the formula, C_f,asIs the mass percentage of carbon element in the fly ash; c_s,asThe mass percentage of carbon element in the large slag is percent; r is_f,asThe mass percentage of the ash in the fly ash to the total ash of the fire coal is percent; r is_s,asThe mass percentage of the ash in the large slag to the total ash of the burning coal is percent; a. the_arThe percentage of the mass content of the received base ash of the fire coal is percent;the mass percentage of carbon element which is actually burnt and is the base of coal recovery is percent; q_iThe real-time heat release of the unit amount of the fire coal in the main combustion area in the deep air staged combustion is kJ/(kg of the fire coal); q_COThe calorific value of carbon monoxide per unit mass, kJ/kg; alpha is the excess air coefficient of the main combustion zone; k is a coefficient; q_net.arReceiving a base low-grade heating value kJ/kg for the fire coal;

wherein the content of carbon element actually burned from the received coal base is determined based on the following formula:

in the formula, C_arThe mass percentage of the carbon element received by the fire coal is percent; c_f,asIs the mass percentage of carbon element in the fly ash; c_s,asThe mass percentage of carbon element in the large slag is percent; r is_f,asThe mass percentage of the ash in the fly ash to the total ash of the fire coal is percent; r is_s,asThe mass percentage of the ash in the large slag to the total ash of the fire coal is percent; a. the_arThe mass content percentage of the base ash obtained by the coal is percent;the percentage of the carbon element which is actually burnt off is received by the fire coal;

wherein, the value of k is determined by utilizing the mass content of carbon element actually burnt by the received fire coal, the excess air coefficient, the combustion rate and the theoretical dry air amount of the main combustion area in the deep air staged combustion, and specifically:

wherein the theoretical dry air amount is determined based on the following formula:

the data are shown in table 1.

2. Acquiring the coal feeding amount and the central elevation of each combustor in the main combustion area, and acquiring the central elevation of an SOFA nozzle for supplementing combustion air in the SOFA area;

the results are shown in Table 1.

3. Acquiring the total heat release of unit quantity of coal in the height of a hearth and deep air staged combustion;

wherein the total heat release per unit quantity of coal in the deep air staged combustion is determined by using the following formula:

in the formula (I), the compound is shown in the specification,the calorific value of carbon dioxide generated by completely burning coal per unit amount in deep air staged combustion is kJ/(kg coal);the total heat release of each unit amount of fire coal in the deep air staged combustion is kJ/(kg of fire coal); q_net.arThe coal receives basic low-level heating value kJ/(kg coal); c_f,asThe mass percentage of carbon element in the fly ash is percent; c_s,asThe mass percentage of carbon element in the large slag is percent; r is_f,asThe mass percentage of the ash in the fly ash to the total ash of the fire coal is percent; r is_s,asThe mass percentage of the ash in the large slag to the total ash of the fire coal is percent; a. the_arThe percentage of the received base ash mass content of the fire coal is percent.

4. Determining the relative height of the center of the flame (the elevation of the flame center relative to the height of a hearth) based on the real-time heat release of the unit amount of the coal in the main combustion area, the real-time heat release of the unit amount of the coal in the SOFA area, the coal feeding amount and the central elevation of each combustor in the main combustion area, the central elevation of the SOFA nozzle for the SOFA area to supplement the combustion air, the height of the hearth and the total heat release of the unit amount of the coal in the deep air staged combustion; specifically, the method comprises the following steps:

4.1, based on the real-time heat release amount of the unit amount of the coal in the main combustion area, the real-time heat release amount of the unit amount of the coal in the SOFA area, the coal feeding amount and the center elevation of each combustor in the main combustion area, the center elevation of the SOFA nozzle for the SOFA area compensation combustion air, the height of a hearth and the total heat release amount of the unit amount of the coal in the deep air staged combustion, and the relative heights of the combustors and the whole combustor formed by the SOFA areas are determined by weighted average of the fuel amount and the heat productivity in each combustor and the SOFA area; wherein, the relative height of the integral burner formed by each burner and the SOFA area is determined by the following formula:

in the formula, x_bThe relative height of the integral burner formed by each burner and the SOFA area; b is_iThe coal feeding quantity of the ith burner is kg; b is_JThe total coal feeding amount of the hearth (namely the sum of the coal feeding amounts of all the burners) is kg; q_iThe real-time heat release of the unit amount of the coal in the main combustion area is kJ/(kg of coal); h is_biIs the center elevation, m, of the ith burner; q_jThe real-time heat release of the unit amount of fire coal in the SOFA area is kJ/(kg of fire coal); h is_bjThe center elevation m of the SOFA nozzle for the combustion air is supplemented for the SOFA area; h is_bIs the height of the hearth, m;the total heat release of each unit amount of fire coal in the deep air staged combustion is kJ/(kg of fire coal);

4.2, determining the relative height of the flame center based on the relative heights of the burners and the overall burner formed by the SOFA area; wherein the relative height of the flame center is determined by the following formula:

x_flm＝x_b+Δx

Δ x is related to the swing angle:

1) Δ x is 0 at burner level;

2) when the burner swings upwards, the delta x increases by 0.1 every time the burner swings 20 degrees;

3) when the burner swings downwards, the delta x is reduced by 0.1 every time the burner swings 20 degrees;

4) when the burner swings up and down at other angles, the inserted value of deltax is taken.

The results are shown in Table 1.

The relative height of the flame center determined using this embodiment determination 4 determines a coefficient M representing the furnace flame height:

in the formula: vdaf is a dry ash-free base volatile component of the fuel; x is the number of_flmThe relative height of the flame center;

the results are shown in Table 1.

If calculated conventionally, the relative height of the flame center is 0.275, and the corresponding coefficient M representing the furnace flame height is 0.56.

TABLE 1

The principle and the implementation mode of the invention are explained by applying specific embodiments in the invention, and the description of the embodiments is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

25页详细技术资料下载

上一篇：一种医用注射器针头装配设备

下一篇：一种节能循环流化床锅炉风机

Method and system for determining flame center in furnace during deep air classification

相关技术

网友询问留言