CN115371043A - Combustion optimization control method based on boiler CT technology - Google Patents

Abstract

The invention relates to a combustion optimization control method based on a boiler CT technology, which comprises the following steps: grouping combustors, collecting temperature, comparing temperature, adjusting combustors and the like. The combustion optimization control method based on the boiler CT technology solves the technical problems that the boiler combustion deviation and the temperature deviation generated by the boiler combustion deviation are difficult to control in real time and control automatically in the boiler combustion adjustment process.

Description

Combustion optimization control method based on boiler CT technology

Technical Field

The invention relates to a combustion optimization control method based on a boiler CT technology, and belongs to the technical field of boilers.

Background

At present, automatic operation of boiler combustion control of thermal power generating units in China is mostly realized, and combustion load can be automatically changed according to unit load change in boiler operation. Under the automatic coordination mode of 'boiler and machine', the steam machine controls the power generation load, the boiler combustion system controls the main steam pressure, and when the set value of the main steam pressure deviates from the actual value, the boiler combustion automatic control loop of the DCS system sends out an adjusting instruction to adjust the boiler fuel and corresponding air distribution in time so as to maintain the stability of the boiler load.

For most boilers of thermal power plants, in the case of a certain all-gas fired boiler, there are a plurality of burners. The combustion regulation and air distribution regulation of the plurality of burners are independent of each other. The burners at the same vertical height are same-layer burners; the burners on the same wall surface and at the same vertical height are the same group of burners.

The boiler combustion system is provided with a gas regulating valve and a gas branch pipe regulating valve, and a same-layer valve group receives a regulating instruction sent by an automatic boiler combustion control loop regulator, and transmits the regulating instruction to each branch pipe regulating valve through a regulating valve layer manipulator so as to keep the branch pipe regulating valves at the same opening degree.

The boiler combustion system is also provided with an air volume regulating valve and an air volume branch pipe regulating valve. The blowers are double-row arranged boilers, and the air supply of the boilers is generally realized by changing the output of the two blowers according to the oxygen content of flue gas of a horizontal flue and a proper air-coal ratio, so that the boilers are economical to burn. After the air from two sides is heated by air preheater, it is fed into burner by means of air quantity regulating valve and air quantity branch pipe regulating valve, and its valve group instruction distribution principle is identical to that of gas regulating valve group.

The automatic boiler combustion and the automatic air volume input reduce the operation burden of operators. However, as the operation time of the boiler increases, the amount of fuel, the amount of air, and the structural deviation of the burners among the burners are continuously deteriorated. The minor deviations will increase cumulatively with the increase of the boiler operation time, eventually resulting in the increase of the temperature deviation of the burner area when the boiler is operated, which in turn results in: the flue gas of the boiler generates larger deviation, the deviation of the heating surface of the boiler is increased, the deviation of the radiation convection heating surface is also increased continuously, the deviation of the opening degree of the water spray desuperheaters at two sides of the boiler is increased, the service life loss of the heating surface is increased, and the safe operation of the boiler is influenced in severe cases.

Therefore, for the boiler with the combustion system, the thermal deviation of the heated surface of the boiler needs to be reduced by adopting a targeted measure according to the thermal deviation condition of the boiler, and the thermal deviation is controlled in a controllable range as much as possible, so that the safe operation time and the service life of the boiler are prolonged. Traditionally, operating personnel often carry out manual burning adjustment according to boiler flue gas along in-process rear end flue gas temperature deviation, and the regulating effect is not good. Especially, in the process of the large-scale repeated change of the boiler load, the hysteresis of the above adjusting mode is more obvious, and the aim of timely reducing the thermal deviation of the boiler is difficult to achieve. Theoretically speaking, the thermal deviation adjustment based on the temperature of the combustor area is more timely, and the thermal deviation can be timely controlled from the front end of the flue gas along the way.

Disclosure of Invention

The invention aims to solve the technical problems that: the method overcomes the defects of the prior art, and provides a method for realizing automatic leveling of a boiler combustion, reducing flue gas on-way thermal deviation, reducing thermal deviation of a boiler heating surface and realizing boiler combustion optimization adjustment by utilizing temperature field distribution data obtained by a boiler CT and designing a combustor leveling optimization control strategy, an optimal total air volume control strategy and an air door leveling optimization control strategy to realize automatic leveling of a boiler combustor area temperature field and further realize automatic leveling of boiler combustion.

In order to solve the technical problems, the technical scheme provided by the invention is as follows: a combustion optimization control method based on a boiler CT technology comprises the following steps:

step 1: the first component formula is as follows: dividing burners which are positioned on the same furnace wall of the boiler and have the same height into a group; the second grouping mode comprises the following steps: dividing the burners into a left burner group and a right burner group by using the central line of the boiler in the front-rear direction as an axis;

step 2: solving the intersection of each group after the first grouping mode and each group after the second grouping mode in the step 1 one by one; acquiring temperature field information and oxygen amount field information of an area where a combustor in the intersection is located through a boiler CT system;

and step 3: leveling gas of the same group of burners; taking a group of burner groups with a first grouping formula; reading the temperature field information; comparing the left temperature characteristic value TiLavg with the right temperature characteristic value TiRavg, if the left temperature characteristic value TiLavg and the right temperature characteristic value TiRavg are consistent, not adjusting, if the TiLavg is larger than the TiRavg, increasing a gas valve of a combustor in the group which is intersected with the left combustor group, and simultaneously decreasing the gas valve of the combustor in the group which is intersected with the right combustor group; if the TiLavg is smaller than the TiRavg, the gas valve of the combustor in the group which is intersected with the left combustor group is adjusted to be small, and the gas valve of the combustor in the group which is intersected with the right combustor group is adjusted to be large; repeating the step until all the burner groups in the first grouping mode are adjusted;

and 4, step 4: leveling coal gas of a same-layer combustor; taking all groups with consistent heights in the first grouping mode; reading the temperature field information of each group; averaging the left temperature characteristic values and the right temperature characteristic values of each group, if the average values of each group are consistent, adjusting the average values, if the average values of each group are inconsistent, adjusting the gas valves of the burner groups with small average values, and simultaneously adjusting the gas valves of the burner groups with large average values; repeating the step until all the groups of the first grouping mode are adjusted;

and 5: leveling the air quantity of the same group of burners; taking a group of burner groups with a first grouping formula; reading the oxygen content field information; comparing the left oxygen quantity characteristic value OiLavg with the right temperature characteristic value OiRavg, if the left oxygen quantity characteristic value OiLavg and the right temperature characteristic value OiRavg are consistent, adjusting the air quantity valve of the combustor which is in the group and is intersected with the left combustor group to be larger, and simultaneously adjusting the air quantity valve of the combustor which is in the group and is intersected with the right combustor group to be smaller; if OiLavg is less than OiRavg, turning down the air volume valve of the burner in the group which is intersected with the left burner group, and simultaneously turning up the air volume valve of the burner in the group which is intersected with the right burner group; repeating the step until all the burner groups in the first grouping mode are adjusted;

and 6: leveling the air quantity of the same-layer combustor; taking all groups with consistent height in the first grouping mode; reading oxygen field information of each group; averaging the left oxygen quantity characteristic value and the right oxygen quantity characteristic value of each group, if the average values of each group are consistent, adjusting the average values, if the average values of each group are inconsistent, adjusting the air quantity valve of the burner group with the smaller average value to be larger, and simultaneously adjusting the gas valve of the burner group with the larger average value to be smaller; repeating the steps until all the groups of the first grouping mode are adjusted.

The scheme is further improved in that: in the step 3, the adjustment amount of the gas valve which is adjusted to be larger is the same as that of the gas valve which is adjusted to be smaller at the same time, and the adjustment directions are opposite.

The scheme is further improved in that: in the step 3, a PID regulator is used for regulating the gas valve; dividing the difference value of the TiLavg and the TiRavg into four sections, wherein the first section is more than 0 and less than or equal to 10 ℃, the second section is more than 10 and less than or equal to 25 ℃, the third section is more than 25 and less than or equal to 40 ℃, and the fourth section is more than 40 ℃; the proportional coefficient, the integral coefficient and the differential coefficient of the PID regulator are set as [ a, b, c ], and when the difference value of TiLavg and TiRavg is in the first segment, [ a, b, c ] = [1,0.8,0]; in the second segment, [ a, b, c ] = [1, 0]; in the third stage, [ a, b, c ] = [ 1.3,1.1,0]; in the fourth paragraph, [ a, b, c ] = [1.4,1.1,0].

The scheme is further improved in that: in the step 4, the adjustment amount of the gas valve which is adjusted to be larger is the same as that of the gas valve which is adjusted to be smaller at the same time, and the adjustment directions are opposite.

The scheme is further improved in that: in the step 4, a PID regulator is used for regulating the gas valve; dividing the difference value of the average values into four sections, wherein the first section is more than 0 and less than or equal to 10 ℃, the second section is more than 10 and less than or equal to 25 ℃, the third section is more than 25 and less than or equal to 40 ℃, and the fourth section is more than 40 ℃; proportional coefficients, integral coefficients and differential coefficients of the PID controller are set to [ a, b, c ], and when a difference of the average values is in a first section, [ a, b, c ] = [1,0.9,0]; in the second segment, [ a, b, c ] = [1.1,1,0]; in the third stage, [ a, b, c ] = [ 1.3,1.2,0]; in the fourth paragraph, [ a, b, c ] = [1.4,1.2,0].

The scheme is further improved in that: and obtaining the optimal temperature field data corresponding to the boiler in different load sections according to the boiler performance data analysis and the boiler combustion adjustment test. When the boiler can burn in the optimum temperature field working condition, the air distribution is in the optimum matching state. Measuring and recording the total air volume of the blowers on two sides of the boiler, and replacing an oxygen volume correction model with an optimal total air volume model in the actual operation of the boiler; inputting the boiler load into the optimal total air volume model, automatically outputting the corresponding optimal total air volume in a linear broken line function mode, and taking the optimal total air volume as a target value for controlling the output of the blower, thereby obtaining a more accurate air distribution instruction than oxygen correction and further giving a basic opening instruction for adjusting the air volume of each layer of combustor; meanwhile, the air supply PID regulator introduces main steam pressure as a feedforward signal, so that the air supply quantity is adjusted in time when the working condition of the boiler changes, and the stability of the ratio of the air supply quantity to the coal gas quantity is maintained.

The scheme is further improved in that: the air supply PID feedforward setting is specifically to obtain main steam pressure in real time, and the change rate of the main steam pressure per minute is calculated by adopting a numerical analysis algorithm; judging whether the preset value a0 is exceeded or the preset value a1 is undershot; if the feedforward gain coefficient is higher than a preset value a0, the feedforward gain coefficient K = Kmax, if the feedforward gain coefficient is lower than a preset value a1, the feedforward gain coefficient K = Kmin, otherwise, the feedforward gain coefficient K = Knor; and multiplying the main steam pressure by a feedforward gain coefficient K to be used as a PID feedforward signal to jointly act on the control output of the frequency converter of the air feeder.

The scheme is further improved in that: a0=0.6,a1=0.2, and the feedforward gain coefficient K varies by [0.1,0.2]; k = Kmax =0.2 when the main steam pressure rate of change per minute is greater than 0.6Mpa, K = Kmin =0.1 when the main steam pressure rate of change per minute is less than 0.2Mpa, and K = Knor =0.15 otherwise.

The combustion optimization control method based on the boiler CT technology solves the technical problems that the combustion deviation of the boiler and the temperature deviation generated by the combustion deviation are difficult to control in real time and automatically control in the combustion adjustment process of the boiler, directly controls the thermal deviation from the front end of the flue gas along the way, and responds timely. The traditional boiler combustion automatic control can only send out a burner co-operation instruction according to the unit requirement, but can not carry out independent fuel accurate matching and air supply accurate matching on each branch burner. Different from the traditional control method, the invention firstly proposes that the temperature field signal and the oxygen content signal of the boiler combustor area measured by the boiler CT are taken as signals for controlling the combustion deviation of the boiler, and the control leveling of the corresponding valve group is carried out when the combustion of the boiler has smaller deviation, so that the combustion deviation of the boiler can be slowed down or eliminated and the large deviation of the oxygen content can be ensured, thereby ensuring that the fuel of the boiler can be economically combusted.

Drawings

Fig. 1 is a schematic diagram of an application scenario of a preferred embodiment of the present invention.

Fig. 2 is a schematic view of the upper burner structure of fig. 1.

FIG. 3 is a schematic view of the lower burner structure of FIG. 1.

Fig. 4 is a schematic view of an automatic control manner of the boiler of fig. 1.

Detailed Description

Examples

In the combustion optimization control method based on the boiler CT technology, NXN measurement grids are configured on a hearth section channel, N pairs of measurement probes are arranged on a boiler water-cooled wall, holes are formed in fins of the water-cooled wall to serve as laser measurement channels, the average temperature of N measurement paths is obtained, the values of corresponding channel intersections are calculated by adopting a CT imaging technology inversion algorithm, hearth distribution reappearance of a temperature field is achieved through the algorithm, and finally hearth temperature field data and images are obtained.

The following description will be made by taking a "mei steel 4# boiler" as an example. As shown in fig. 1, 2 and 3, the boiler is provided with 6 burners on the front wall and the rear wall respectively, and each burner is provided with a corresponding gas branch pipe regulating valve and air branch pipe regulating valve, thereby realizing independent regulation of each burner; meanwhile, 3 burners positioned at the same height of the same furnace wall are synchronously controlled by a gas regulating valve and an air volume regulating valve. The boiler is controlled by a DCS system, and a coal gas branch pipe regulating valve, an air volume branch pipe regulating valve, a coal gas regulating valve and an air volume regulating valve are controlled by a PID regulator.

The method specifically comprises the following steps:

step 1: the first component formula is as follows: the burners which are positioned on the same furnace wall of the boiler and have the same height are divided into one group, namely, the burners in the embodiment are divided into four groups, namely, the front upper group, the front lower group, the rear upper group and the rear lower group, and each group is 3 burners; the second grouping mode comprises the following steps: the burners are divided into a left burner group and a right burner group with the center line of the boiler in the front-rear direction as an axis, and the burners in the middle are disposed just at the center line, so that they are excluded.

Step 2: each group after the first grouping mode in the step 1 and each group after the second grouping mode are grouped are subjected to one-to-one intersection; thus obtaining a front upper burner 1, a front upper burner 3, a rear upper burner 1, a rear upper burner 3, a front lower burner 1, a front lower burner 3, a rear lower burner 1 and a rear lower burner 3; acquiring temperature field information and oxygen amount field information of the areas where the combustors are located in the obtained intersection through a boiler CT system; communicating to a DCS (distributed control System) in a 485 communication mode; the design of the communication monitoring function has the advantages that when communication is abnormal, the temperature field signal and the oxygen field signal transmitted to the DCS through the CT system of the boiler can automatically keep the numerical value before the communication is abnormal, and a communication abnormality alarm prompt is sent.

And step 3: leveling coal gas of the same group of burners; taking a group of burner groups with a first grouping formula; reading the temperature field information; after data obviously deviating from the design process are removed, clustering analysis is carried out on the residual data by adopting a clustering analysis method, and the temperature at the same side is subjected to clustering data analysis to obtain a temperature signal which can represent the combustion condition of the side combustion area most; performing Kalman filtering processing on the data to eliminate signal jump, avoiding the influence of the signal jump on leveling combustion optimization, mastering the change condition of the temperature field in the area and realizing the prejudgment of the temperature field change; comparing the left temperature characteristic value TiLavg with the right temperature characteristic value TiRavg, if the left temperature characteristic value TiLavg and the right temperature characteristic value TiRavg are consistent, not adjusting, if the TiLavg is larger than the TiRavg, increasing a gas valve of a combustor in the group which is intersected with the left combustor group, and simultaneously decreasing the gas valve of the combustor in the group which is intersected with the right combustor group; if the TiLavg is smaller than the TiRavg, the gas valve of the combustor in the group which is intersected with the left combustor group is adjusted to be small, and the gas valve of the combustor in the group which is intersected with the right combustor group is adjusted to be large; repeating the steps until all the burner groups in the first grouping mode are adjusted.

Taking the front upper burner group as an example, the T1Lavg of the front upper burner 1 is compared with the T1Ravg of the front upper burner 3; if the two are not consistent, the PID regulator outputs a regulation instruction OP1z, and the instruction only represents the regulation amount and has no direction; if T1Lavg > T1Ravg; then the adjustment optimization command OP1zL = OP1z (-1) for the upper gas branch regulating valve 1 is expressed by a negative value, i.e. reduced, while the adjustment optimization command OP1zR = OP1z 1 for the upper gas branch regulating valve 3 is expressed by a positive value, i.e. reduced; if T1Lavg is less than T1Ravg; the regulation optimization command OP1zL = OP1z x 1 for the front upper gas branch regulating valve 1, while the regulation optimization command OP1zR = OP1z (-1) for the front upper gas branch regulating valve 3.

In order to realize faster and more accurate adjustment, the difference value between T1Lavg and T1Ravg is divided into four sections, the first section is more than 0 and less than or equal to 10 ℃, the second section is more than 10 and less than or equal to 25 ℃, the third section is more than 25 and less than or equal to 40 ℃, and the fourth section is more than 40 ℃; proportional coefficients, integral coefficients and differential coefficients of the PID controller are set to [ a, b, c ], and when a difference between T1Lavg and T1Ravg is in a first segment, [ a, b, c ] = [1,0.8,0]; in the second segment, [ a, b, c ] = [1, 0]; in the third stage, [ a, b, c ] = [ 1.3,1.1,0]; in the fourth paragraph, [ a, b, c ] = [1.4,1.1,0]; thereby acquiring different adjustment instructions OP1z, i.e., different adjustment amounts.

The adjustment modes of the other three groups of combustors are consistent, and the detailed description is omitted.

The gas leveling of the same group of burners is based on the automatic combustion regulation shown in fig. 4 and needs to be put into use under the condition that the boiler combustion is automatically put into use. The results after the coal gas leveling combustion optimization of the same group of burners are superposed on the automatic instructions of the gas branch pipe regulating valves of the corresponding burners as offsets, and finally participate in a combustion regulation large closed loop control loop taking the main steam pressure as a regulation object.

And 4, step 4: leveling coal gas of the same-layer combustor; taking all groups with consistent height in the first grouping mode; reading the temperature field information of each group; averaging the left temperature characteristic value and the right temperature characteristic value of each group, if the average values of each group are consistent, adjusting no, if the average values of each group are inconsistent, adjusting a gas valve of a burner group with a small average value to be large, and simultaneously adjusting a gas valve of a burner group with a large average value to be small; repeating the steps until all the groups of the first grouping mode are adjusted.

In the present application, the upper front and the upper rear are the same height group, and the lower front and the lower rear are the same height group. The front upper part and the rear upper part comprise 6 burners, namely a front upper burner 1, a front upper burner 2, a front upper burner 3, a rear upper burner 1, a rear upper burner 2 and a rear upper burner 3.

Averaging temperature characteristic values of the front upper combustor 1, the front upper combustor 2 and the front upper combustor 3 to obtain T1avg, and averaging temperature characteristic values of the rear upper combustor 1, the rear upper combustor 2 and the rear upper combustor 3 to obtain T2avg. Comparing the T1avg with the T2avg, if the two are not consistent, the PID regulator outputs a regulation instruction OPC, and the instruction only represents the regulation amount and has no direction; if T1avg > T2avg; then, for the adjustment optimization instruction OPC1= OPC (-1) of the front upper gas regulating valve, the adjustment direction is expressed by a negative value, that is, the adjustment is small, and for the adjustment optimization instruction OPC2= OPC1 of the rear upper gas regulating valve, the adjustment direction is expressed by a positive value, that is, the adjustment is large; if T1avg is less than T2avg; then the regulation optimization command OPC1= OPC1 for the front upper gas regulating valve, while the regulation optimization command OPC2= OPC (-1) for the rear upper gas regulating valve.

In order to realize faster and more accurate adjustment, the difference value between the T1avg and the T2avg is divided into four sections, wherein the first section is more than 0 and less than or equal to 10 ℃, the second section is more than 10 and less than or equal to 25 ℃, the third section is more than 25 and less than or equal to 40 ℃, and the fourth section is more than 40 ℃; proportional coefficients, integral coefficients and differential coefficients of the PID controller are set to [ a, b, c ], and when a difference between T1avg and T2avg is in a first segment, [ a, b, c ] = [1,0.9,0]; in the second segment, [ a, b, c ] = [1.1,1,0]; in the third stage, [ a, b, c ] = [ 1.3,1.2,0]; in the fourth paragraph, [ a, b, c ] = [1.4,1.2,0]; thereby obtaining different adjustment instructions OPC, i.e. different adjustment amounts.

Therefore, the adjusting modes of the front lower combustor and the rear lower combustor are consistent and are not described again.

And 5: leveling the air quantity of the same group of burners; taking a group of burner groups with a first grouping formula; reading the oxygen content field information; comparing the left oxygen quantity characteristic value OiLavg with the right temperature characteristic value OiRavg, if the left oxygen quantity characteristic value OiLavg and the right temperature characteristic value OiRavg are consistent, adjusting the air quantity valve of the combustor which is in the group and is intersected with the left combustor group to be larger, and simultaneously adjusting the air quantity valve of the combustor which is in the group and is intersected with the right combustor group to be smaller; if OiLavg is less than OiRavg, turning down the air volume valve of the combustor in the group which is intersected with the left combustor group, and simultaneously turning up the air volume valve of the combustor in the group which is intersected with the right combustor group; repeating the step until all the burner groups in the first grouping mode are adjusted; this step is similar to step 4, changes the gas valve into the blast gate valve, and will not be repeated.

The same-layer burner gas leveling is also based on the automatic combustion regulation shown in fig. 4 and needs to be put into use in the case of automatic boiler combustion. The result after the leveling combustion optimization of the same-floor combustor is superposed on an automatic instruction of a same-floor manipulator operator as offset and is redistributed to corresponding branch pipe regulating valves to finally participate in a combustion regulation large closed loop control loop taking main steam pressure as a regulation object.

And 6: leveling the air quantity of the same-layer combustor; taking all groups with consistent heights in the first grouping mode; reading oxygen field information of each group; averaging the left oxygen quantity characteristic value and the right oxygen quantity characteristic value of each group, if the average values of each group are consistent, adjusting the average values, if the average values of each group are inconsistent, adjusting the air quantity valve of the burner group with small average value to be larger, and simultaneously adjusting the gas valve of the burner group with large average value to be smaller; repeating the step until all the groups of the first grouping mode are adjusted; this step is similar to step 5, changes the gas valve into the blast volume valve, no longer describes.

And obtaining the optimal temperature field data corresponding to the boiler in different load sections according to the boiler performance data analysis and the boiler combustion adjustment test. When the boiler can burn in the optimum temperature field working condition, the air distribution is in the optimum matching state. Measuring and recording the total air quantity of the blowers on the two sides of the boiler, and replacing an oxygen quantity correction model with an optimal total air quantity model in the actual operation of the boiler; the optimal total air volume model inputs boiler load, automatically outputs corresponding optimal total air volume in a linear broken line function mode, and takes the optimal total air volume as a target value for controlling the output of a blower, so that an air distribution instruction more accurate than oxygen volume correction is obtained, and a basic opening instruction for adjusting the air volume of each layer of combustor is given; meanwhile, the air supply PID regulator introduces main steam pressure as a feedforward signal, so that the air supply quantity is adjusted in time when the working condition of the boiler changes, and the stability of the ratio of the air supply quantity to the coal gas quantity is maintained.

The air supply PID feedforward setting is specifically to obtain main steam pressure in real time, and the change rate of the main steam pressure per minute is calculated by adopting a numerical analysis algorithm; judging whether the preset value a0 is exceeded or not or whether the preset value a1 is lower or not; if the feedforward gain coefficient exceeds a preset value a0, the feedforward gain coefficient K = Kmax, if the feedforward gain coefficient K = Kmin is lower than a preset value a1, otherwise, the feedforward gain coefficient K = Knor; and multiplying the main steam pressure by a feedforward gain coefficient K to be used as a PID feedforward signal and jointly acting on the control output of the frequency converter of the air feeder.

In this embodiment, a0=0.6, a1=0.2, and the feedforward gain coefficient K varies in the range of [0.1,0.2]; k = Kmax =0.2 when the main steam pressure rate of change per minute is greater than 0.6Mpa, K = Kmin =0.1 when the main steam pressure rate of change per minute is less than 0.2Mpa, otherwise K = Knor =0.15.

The present invention is not limited to the above-described embodiments. All technical solutions formed by equivalent substitutions fall within the protection scope of the claims of the present invention.

Claims (8)

1. A combustion optimization control method based on a boiler CT technology is characterized by comprising the following steps:

step 1: the first component formula is as follows: dividing burners which are positioned on the same furnace wall of the boiler and have the same height into a group; the second grouping mode comprises the following steps: dividing the burners into a left burner group and a right burner group by using the central line of the boiler in the front-rear direction as an axis;

step 2: each group after the first grouping mode in the step 1 and each group after the second grouping mode are grouped are subjected to one-to-one intersection; acquiring temperature field information and oxygen amount field information of an area where a combustor in the intersection is located through a boiler CT system;

and step 3: leveling gas of the same group of burners; taking a group of burner groups with a first grouping formula; reading the temperature field information; comparing the left temperature characteristic value TiLavg with the right temperature characteristic value TiRavg, if the left temperature characteristic value TiLavg and the right temperature characteristic value TiRavg are consistent, not adjusting, if the TiLavg is larger than the TiRavg, increasing a gas valve of a combustor in the group which is intersected with the left combustor group, and simultaneously decreasing the gas valve of the combustor in the group which is intersected with the right combustor group; if the TiLavg is smaller than the TiRavg, the gas valve of the combustor in the group which is intersected with the left combustor group is adjusted to be small, and the gas valve of the combustor in the group which is intersected with the right combustor group is adjusted to be large; repeating the step until all the burner groups in the first grouping mode are adjusted;

and 4, step 4: leveling coal gas of a same-layer combustor; taking all groups with consistent height in the first grouping mode; reading the temperature field information of each group; averaging the left temperature characteristic values and the right temperature characteristic values of each group, if the average values of each group are consistent, adjusting the average values, if the average values of each group are inconsistent, adjusting the gas valves of the burner groups with small average values, and simultaneously adjusting the gas valves of the burner groups with large average values; repeating the step until all the groups of the first grouping mode are adjusted;

and 5: leveling the air quantity of the same group of burners; taking a group of burner groups with a first grouping formula; reading the oxygen field information; comparing the left oxygen quantity characteristic value OiLavg with the right temperature characteristic value OiRavg, if the left oxygen quantity characteristic value OiLavg and the right temperature characteristic value OiRavg are consistent, adjusting the air quantity valve of the combustor which is in the group and is intersected with the left combustor group to be larger, and simultaneously adjusting the air quantity valve of the combustor which is in the group and is intersected with the right combustor group to be smaller; if OiLavg is less than OiRavg, turning down the air volume valve of the combustor in the group which is intersected with the left combustor group, and simultaneously turning up the air volume valve of the combustor in the group which is intersected with the right combustor group; repeating the step until all the burner groups in the first grouping mode are adjusted;

step 6: leveling the air quantity of the same-layer combustor; taking all groups with consistent heights in the first grouping mode; reading oxygen field information of each group; averaging the left oxygen quantity characteristic value and the right oxygen quantity characteristic value of each group, if the average values of each group are consistent, adjusting the average values, if the average values of each group are inconsistent, adjusting the air quantity valve of the burner group with small average value to be larger, and simultaneously adjusting the gas valve of the burner group with large average value to be smaller; repeating the steps until all the groups of the first grouping mode are adjusted.

2. The boiler CT technology-based combustion optimization control method according to claim 1, characterized in that: in the step 3, the adjustment amount of the gas valve which is adjusted to be larger is the same as that of the gas valve which is adjusted to be smaller at the same time, and the adjustment directions are opposite.

3. The boiler CT technology-based combustion optimization control method according to claim 2, characterized in that: in the step 3, a PID regulator is used for regulating the gas valve; dividing the difference value of the TiLavg and the TiRavg into four sections, wherein the first section is more than 0 and less than or equal to 10 ℃, the second section is more than 10 and less than or equal to 25 ℃, the third section is more than 25 and less than or equal to 40 ℃, and the fourth section is more than 40 ℃; the proportional coefficient, the integral coefficient and the differential coefficient of the PID regulator are set to be [ a, b, c ], and when the difference value of TiLavg and TiRavg is in the first segment, [ a, b, c ] = [1,0.8,0]; in the second segment, [ a, b, c ] = [1, 0]; in the third stage, [ a, b, c ] = [ 1.3,1.1,0]; in the fourth paragraph, [ a, b, c ] = [1.4,1.1,0].

4. The boiler CT technology-based combustion optimization control method according to claim 1, characterized in that: in the step 4, the adjustment amount of the gas valve which is adjusted to be larger is the same as that of the gas valve which is adjusted to be smaller at the same time, and the adjustment directions are opposite.

5. The boiler CT technology-based combustion optimization control method according to claim 4, wherein the method comprises the following steps: in the step 4, a PID regulator is used for regulating the gas valve; dividing the difference value of the average values into four sections, wherein the first section is more than 0 and less than or equal to 10 ℃, the second section is more than 10 and less than or equal to 25 ℃, the third section is more than 25 and less than or equal to 40 ℃, and the fourth section is more than 40 ℃; proportional coefficients, integral coefficients and differential coefficients of the PID controller are set to [ a, b, c ], and when a difference of the average values is in a first section, [ a, b, c ] = [1,0.9,0]; in the second segment, [ a, b, c ] = [1.1,1,0]; in the third segment, [ a, b, c ] = [ 1.3,1.2,0]; in the fourth paragraph, [ a, b, c ] = [1.4,1.2,0].

6. The boiler CT technology-based combustion optimization control method according to claim 1, characterized in that: according to the boiler performance data analysis and the boiler combustion adjustment test, obtaining optimal temperature field data corresponding to the boiler in different load sections; when the boiler can be burnt in the working condition of the optimal temperature field, the air distribution of the boiler is also in the optimal matching state; measuring and recording the total air volume of the blowers on two sides of the boiler, and replacing an oxygen volume correction model with an optimal total air volume model in the actual operation of the boiler; inputting the boiler load into the optimal total air volume model, automatically outputting the corresponding optimal total air volume in a linear broken line function mode, and taking the optimal total air volume as a target value for controlling the output of the blower, thereby obtaining a more accurate air distribution instruction than oxygen correction and further giving a basic opening instruction for adjusting the air volume of each layer of combustor; meanwhile, the air supply PID regulator introduces main steam pressure as a feedforward signal, so that the air supply quantity is adjusted in time when the working condition of the boiler changes, and the stability of the ratio of the air supply quantity to the coal gas quantity is maintained.

7. The boiler CT technology-based combustion optimization control method according to claim 6, wherein: the air supply PID feed-forward setting is to obtain the main steam pressure in real time, and calculate the change rate of the main steam pressure per minute by adopting a numerical analysis algorithm; judging whether the preset value a0 is exceeded or the preset value a1 is undershot; if the feedforward gain coefficient exceeds a preset value a0, the feedforward gain coefficient K = Kmax, if the feedforward gain coefficient K = Kmin is lower than a preset value a1, otherwise, the feedforward gain coefficient K = Knor; and multiplying the main steam pressure by a feedforward gain coefficient K to be used as a PID feedforward signal and jointly acting on the control output of the frequency converter of the air feeder.

8. The boiler CT technology-based combustion optimization control method according to claim 7, wherein: a0=0.6,a1=0.2, and the feedforward gain coefficient K varies by [0.1,0.2]; k = Kmax =0.2 when the main steam pressure rate of change per minute is greater than 0.6Mpa, K = Kmin =0.1 when the main steam pressure rate of change per minute is less than 0.2Mpa, otherwise K = Knor =0.15.

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