Ammonia and coal dual-fuel mixed boiler combustion control method and system

Abstract

The invention provides a combustion control method and system for an ammonia-coal dual-fuel mixed boiler, and belongs to the field of combustion control of ammonia-coal mixed combustion. The combustion control method for the ammonia-coal dual-fuel mixing boiler comprises the following steps that S1, boiler operation parameters in the ammonia-coal dual-fuel mixing process are generated according to the boiler load and the ammonia mixing proportion requirement in the ammonia-coal dual-fuel mixing process; the boiler operation parameters comprise an ammonia feeding amount set value and a coal feeding amount set value. According to the invention, the fuel quantity, the air quantity and the pollutant discharge in the ammonia-coal dual-fuel blending combustion can be automatically adjusted and controlled, the combustion efficiency is improved, the low pollutant discharge is realized, and the blending combustion automation level is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ammonia-coal combustion control, and in particular to a combustion control method and system for an ammonia-coal dual-fuel blended boiler. Background Art

[0002] Ammonia is an efficient carrier of hydrogen and has higher storage and transportation efficiency and safety than hydrogen. The combustion of coal-fired boilers mixed with ammonia can utilize existing power station resources to achieve large-scale carbon reduction, which is of great significance to helping my country's thermal power sector achieve its dual carbon goals. However, the combustion of ammonia as a fuel still needs to overcome two challenges. First, ammonia has poor combustion properties. NH 3 / Laminar flame speed S of air premixed flame Ｌ The peak value is only around 7 cm / s, much lower than CH 4 and H 2 , and ammonia has a narrow flammable limit range, a high self-ignition temperature, and its adiabatic flame temperature at normal pressure is much lower than that of CH 4 and H 2 , which is not conducive to stable combustion; secondly, due to NH 3 It contains nitrogen, and a large amount of fuel-type NOx may be produced during combustion. In addition, since the adiabatic flame temperature of ammonia is lower than that of coal powder, and the composition and radiation characteristics of ammonia combustion products are significantly different from those of coal powder, the combustion of ammonia and coal may cause significant changes in the temperature distribution in the furnace, thereby affecting the heat transfer distribution of the boiler. It can be seen that the boiler combustion control during the ammonia-coal dual-fuel blending process of coal-fired boilers is difficult. First, it is necessary to ensure that the furnace temperature field distribution is not affected, second, it is necessary to ensure that the NOx concentration at the furnace outlet does not exceed the standard, and third, it is necessary to ensure that the ammonia is fully burned. At present, the traditional combustion control system has failed to effectively adapt to the characteristics of ammonia combustion, and it is impossible to realize the monitoring of the furnace temperature field during the ammonia-coal dual-fuel blending process, as well as the automatic control and adjustment of the fuel amount, air amount and pollutant emissions at the furnace outlet according to the ammonia blending ratio, resulting in complex operation of the operating personnel during the ammonia-coal dual-fuel blending process, low combustion efficiency, and excessive pollutants.

[0003] Therefore, there is an urgent need to develop a combustion control method and system for a boiler with dual-fuel ammonia-coal blending. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a combustion control method for a boiler with an ammonia-coal dual-fuel mixture, which realizes automatic adjustment and control of fuel, air and pollutant emissions during the ammonia-coal blending process, improves combustion efficiency and achieves lower pollutant emissions, and improves the level of automation to solve the problems mentioned in the above technical background.

[0005] Correspondingly, the present invention also provides a boiler combustion control system for ammonia-coal dual fuel blending.

[0006] The present invention adopts the following technical solutions:

[0007] A method for controlling combustion of a boiler with dual fuel of ammonia and coal, comprising the following steps:

[0008] S1: generating boiler operating parameters in the process of ammonia-coal dual-fuel blending according to the boiler load and ammonia blending ratio requirement during ammonia-coal dual-fuel blending; the boiler operating parameters include an ammonia feed amount set value and a coal feed amount set value;

[0009] Wherein, step S1 specifically includes the following steps:

[0010] S11: Set the initial ammonia blending ratio k 0 , the initial ammonia blending ratio k 0 Determined according to the boiler fuel calorific value ratio, the calculation formula is k 0 =(m n ×LHV n ) / (m n ×LHV n +m m ×LHV m ), where m n is the mass flow rate of ammonia fuel, m m is the coal fuel mass flow rate, LHV n The lower heating value of ammonia fuel, LHV m It is the low calorific value of coal fuel;

[0011] S12: Set the fuel quantity setting value F generated by the boiler main controller according to the load instruction and the steam pressure deviation total (generated by the PID control algorithm) multiplied by k 0 , get the ammonia dosage setting value F NH3 =k 0 ×F total ;

[0012] S13: Set the ammonia supply amount to a value F NH3 After conversion according to the calorific value, the equivalent converted coal quantity instruction F is formed coal-eq =F NH3 ×(LHV n / LHV m );

[0013] S14: Calculate the coal feed setting value F coal =F total -F coal-eq .

[0014] Wherein, the boiler combustion control method further includes the following steps:

[0015] S2: Real-time monitoring of the NOx concentration C at the furnace outlet _NOx and unburned NH 3 Concentration C_NH3 , dynamically correct the ammonia blending ratio according to the concentration deviation; generate a new ammonia feed amount setting value and a new coal feed amount setting value according to the corrected ammonia blending ratio;

[0016] Among them, the correction of the ammonia blending ratio is specifically as follows:

[0017] When C _NOx >C goal_NOx (furnace outlet NOx concentration target value), according to formula k 1 =k 0 ×[1+0.05×(C _NOx - C goal_NOx ) / 10] to increase the ammonia blending ratio, the correction coefficient range is 1.05-1.15; wherein C goal_Nox is the target value of NOx concentration at the furnace outlet;

[0018] When the unburned NH 3 Concentration C _NH3 >C goal_ NH3 (target value of unburned NH3 concentration at furnace outlet), according to formula k 2 =k 0 ×[1-0.03×(C _NH3 - C goal_ NH3 ) / 10] reduce the ammonia blending ratio, the correction coefficient range is 0.85-0.95; wherein C goal_ NH3 NH for furnace outlet 3 Concentration target value.

[0019] Among them, the concentration target value C goal_Nox and C goal_ NH3 Determined based on the ammonia-blended combustion test data of units with corresponding power.

[0020] Wherein, the boiler operation parameters also include excess air coefficient; the control method also includes the following steps:

[0021] S3: step of controlling the excess air coefficient within a preset range;

[0022] The specific step S3 includes the following steps:

[0023] S31: Real-time monitoring of the NOx concentration at the furnace outlet C _NOx and unburned NH 3 Concentration C _NH3 , adjust the boiler air supply according to the concentration deviation;

[0024] S32: Control the excess air coefficient within a preset range by graded air distribution according to the adjusted air supply volume; wherein controlling the excess air coefficient within the preset range includes controlling the total excess air coefficient α of the boiler total> 1.1; and control the local excess air coefficient α in the main combustion zone of ammonia-coal co-firing local < 0.8. The staged air distribution method includes adjusting the air supply volume of the secondary air dampers in the main combustion zone and the air supply volume in the burnout zone. The specific adjustments are as follows:

[0025] When C _NOx concentration exceeds the target value C of the NOx concentration of the furnace outlet products goal_NOx , reduce the secondary air volume in the main combustion zone to 40%-50% of the total air volume, and increase the opening of the SOFA dampers in the burnout zone to 70%-80% to achieve oxygen-deficient combustion in the main combustion zone;

[0026] When the unburned NH3 concentration C _NH3 exceeds the target value C of the unburned NH 3 concentration goal_ NH3 , increase the oxygen concentration in the main combustion zone to 23%-25%.

[0027] Among them, the control method further includes the following steps:

[0028] S4: Real-time monitor the furnace temperature field and the furnace outlet flue gas temperature, and correct the ammonia blending ratio k 0 using the furnace temperature field and the furnace outlet flue gas temperature;

[0029] Specifically: When the average value of the temperature gradient deviation at the four corners of the furnace and / or the average value of the flue gas temperature deviation at the furnace outlet ΔT > 50°C is continuously monitored for 30 minutes, trigger the correction of the ammonia blending ratio according to the formula k 3 = k 0 ×(1 - 0.1×ΔT / 50), and the correction coefficient range is 0.9 - 1.1.

[0030] A boiler combustion control system for ammonia-coal dual-fuel blending, the control system includes:

[0031] A central control module, a monitoring module, an execution module, and an alarm module; the central control module is electrically connected or communicatively connected to the monitoring module, the execution module, and the alarm module;

[0032] The central control module is used to generate corresponding control strategies according to the boiler load and ammonia blending ratio requirements during ammonia-coal dual-fuel blending, and adjust the control strategies according to the information of the monitoring module to generate new control strategies, and send the control strategies to the execution module; the central control module includes a fuel quantity calculation unit and an air volume distribution unit. The fuel quantity calculation unit is used to execute the control method described in any one of steps S1 - S4, and the air volume distribution unit is connected to the air distribution system to execute the air distribution control strategy of step S3;

[0033] The execution module is used to adjust the boiler operating parameters in the ammonia-coal dual fuel blending process according to the received control strategy; the execution module includes an ammonia supply regulating valve, a coal feeder speed actuator, an air supply volume regulator, a secondary air door and a SOFA air door actuator;

[0034] The monitoring module is used to monitor the NOx concentration at the furnace outlet and the unburned NH 3 Concentration, three-dimensional temperature field of furnace, and flue gas temperature at furnace outlet;

[0035] The alarm module is used to generate sound, light or vibration alarm when the ammonia escape value at the furnace outlet exceeds a threshold value.

[0036] The monitoring module includes a furnace outlet NOx concentration monitoring unit and a furnace outlet unburned NH 3 Concentration monitoring unit, furnace temperature field monitoring unit, furnace outlet smoke temperature monitoring unit;

[0037] The furnace outlet NOx concentration monitoring unit and the furnace outlet unburned NH 3 The concentration monitoring unit includes an online flue gas analyzer and an ammonia escape laser detector installed in the economizer outlet flue. The online flue gas analyzer is used to monitor the NOx concentration at the furnace outlet, and the ammonia escape laser detector is used to monitor the unburned NH 3 concentration;

[0038] The furnace temperature field monitoring unit includes a first temperature measuring element and a data processing module; the data processing module obtains the three-dimensional temperature field of the furnace according to the measurement result of the first temperature measuring element;

[0039] The furnace outlet smoke temperature monitoring unit measures the furnace outlet smoke temperature value by means of a second temperature measuring element installed at the furnace outlet.

[0040] The first temperature measuring element is an infrared CCD camera with a spectral response range of 3-5um, and the second temperature measuring element is a furnace infrared pyrometer.

[0041] Wherein, the data processing module includes a temperature field algorithm server, a PLC controller, a communication link, a communication network and a power supply module;

[0042] Among them, the first temperature measuring element transmits the measured data to the temperature field algorithm server through optical fiber, the temperature field algorithm server and the PLC controller are connected through a communication network, and data transmission is performed based on the TCP / IP protocol, and the three-dimensional temperature field data of the furnace inverted by the temperature field algorithm server is transmitted to the PLC controller; the PLC controller and the central control module are connected through a communication link, and data transmission is performed based on the Modbus protocol, and the PLC controller transmits the three-dimensional temperature field data of the furnace to the central control module.

[0043] Wherein, first temperature measuring elements are arranged in both the horizontal and vertical directions of the furnace.

[0044] Wherein, two first temperature measuring elements are arranged in the horizontal direction of the furnace; the two first temperature measuring elements are arranged in a relatively staggered manner, and the two first temperature measuring elements are arranged above the burner of the ammonia-coal mixed-firing boiler;

[0045] And / or, two first temperature measuring elements are arranged in the vertical direction of the furnace; the two first temperature measuring elements are arranged on the front wall of the burner of the ammonia-coal mixed firing boiler and are arranged along the height direction.

[0046] Among them, the horizontal and vertical viewing angles of the two first temperature measuring elements arranged in the horizontal direction both form a certain angle with the boiler axis; the horizontal and vertical viewing angles of the two first temperature measuring elements arranged in the height direction both form a certain angle with the boiler axis.

[0047] The horizontal field of view angle of the two first temperature measuring elements arranged in the horizontal direction and the angle between them and the axis of the boiler are 45°, and the vertical field of view angle of the two first temperature measuring elements arranged in the horizontal direction and the angle between them and the axis of the boiler are 45°;

[0048] The horizontal viewing angle of the two first temperature measuring elements arranged in the height direction and the angle between them and the boiler axis are 80°, and the vertical viewing angle of the two first temperature measuring elements arranged in the height direction and the angle between them and the boiler axis are 55°.

[0049] Wherein, the monitoring module also includes:

[0050] Steam parameter monitoring unit, used to monitor the main steam parameter value and reheat steam parameter value of the boiler in the ammonia-coal dual-fuel mixed combustion;

[0051] The desuperheating water monitoring unit is used to monitor the desuperheating water volume of the main steam and reheat steam of the boiler in the ammonia-coal dual-fuel mixed combustion;

[0052] Fuel quantity monitoring unit: used to monitor the coal consumption and ammonia consumption of the boiler during the ammonia-coal dual-fuel mixed combustion;

[0053] The air volume monitoring unit is used to monitor the total air volume and burnout air volume in the ammonia-coal dual-fuel mixed combustion, thereby monitoring the total excess air coefficient value of the boiler combustion and the excess air coefficient value of the main combustion zone.

[0054] Wherein, the central control module includes a control strategy generation unit, an adjustment strategy generation unit and a control strategy adjustment unit;

[0055] The control strategy generation unit is used to generate boiler operating parameters during the ammonia-coal dual fuel blending process according to the boiler load and ammonia blending ratio requirements during the ammonia-coal dual fuel blending process;

[0056] The adjustment strategy generation unit compares the real-time measurement parameters of the monitoring module with the set parameter target value to obtain a deviation result, calculates the required combustion reaction conditions according to the deviation result, and generates a boiler operation parameter adjustment strategy;

[0057] The control strategy adjustment unit is used to update the control strategy according to the adjustment strategy generated by the adjustment strategy generation unit to obtain a new control strategy.

[0058] Among them, the alarm module includes an audible and visual alarm and a vibrator, and the audible and visual alarm and the vibrator are electrically connected to the central control module. When the ammonia escape value at the furnace outlet exceeds the alarm threshold, the central control module outputs an electrical signal to the audible and visual alarm and the vibrator, so that they can emit audible and visual alarms and vibration alarms.

[0059] The beneficial effects of the present invention are as follows:

[0060] (1) The combustion control method of ammonia-coal dual-fuel blended boiler of the present invention can generate a corresponding control strategy according to the boiler load and ammonia blending ratio requirement when ammonia-coal dual-fuel blended boiler is used, and the furnace temperature field, furnace outlet smoke temperature and furnace outlet product NOx / unburned NH 3 Real-time monitoring equipment to obtain furnace temperature field, furnace outlet smoke temperature and furnace outlet product NOx / unburned NH 3 The concentration is measured in real time, and the deviation between the measured value and the target value is compared to calculate the required combustion reaction conditions, generate the boiler fuel quantity and air volume parameter adjustment strategy, and realize the update of the ammonia-coal dual-fuel blended combustion control strategy.

[0061] (2) The present invention can achieve automatic balance of coal and ammonia amounts during the ammonia-coal dual-fuel mixed combustion process, maintain a suitable total excess air coefficient for boiler combustion and excess air coefficient for the main combustion zone, improve the efficiency of ammonia-coal dual-fuel mixed combustion, and reduce pollutant emission concentrations. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1A schematic diagram of a combustion control system for a boiler using dual fuels of ammonia and coal provided by the present invention;

[0063] Figure 2 The invention provides an ammonia-coal dual-fuel blending boiler furnace temperature field, furnace outlet smoke temperature monitoring unit and furnace outlet NOx and unburned NH 3 Schematic diagram of the concentration monitoring unit layout;

[0064] Figure 3 A schematic diagram of the working process of the furnace temperature field monitoring unit provided by the present invention.

[0065] In the figure: 001-furnace; 002-economizer; 003-platen superheater; 004-denitrification SCR device; 005-ammonia-coal mixed combustion boiler burner group; 100-central control module; 110-fuel quantity calculation unit; 120-air volume distribution unit; 130-temperature field algorithm server; 140-PLC controller; 200-monitoring module; 210-furnace temperature field monitoring unit; 220-furnace outlet smoke temperature monitoring unit; 230-furnace outlet NOx concentration monitoring unit; 240-furnace outlet unburned NH 3 Concentration monitoring unit; 250-steam parameter monitoring unit; 260-cooling water monitoring unit; 270-fuel quantity monitoring unit; 280-air volume monitoring unit; 211-first temperature measuring element; 212-second temperature measuring element; 231-online flue gas analyzer; 241-ammonia escape laser detector; 300-execution module; 310-ammonia supply regulating valve; 320-coal feeder speed actuator; 330-air supply volume regulator; 340-secondary air door actuator; 350-SOFA air door actuator; 400-alarm module; 500-power supply module. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0067] The present invention provides a combustion control method for a boiler with dual fuel of ammonia and coal, which comprises the following steps:

[0068] S1: Generate boiler operating parameters during the ammonia-coal dual-fuel blending process according to the boiler load and ammonia blending ratio requirement during ammonia-coal dual-fuel blending; the boiler operating parameters include ammonia feed amount and coal feed amount.

[0069] Wherein, step S1 specifically includes the following steps:

[0070] S11: Set the initial ammonia blending ratio k 0 , where the initial ammonia blending ratio k 0 is determined according to the boiler fuel calorific value ratio, and the calculation formula is k 0 =(m n ×LHV n ) / (m n ×LHV n +m m ×LHV m ), where m n is the mass flow rate of ammonia fuel, m m is the mass flow rate of coal fuel, LHV n is the lower heating value of ammonia fuel, LHV m is the lower heating value of coal fuel;

[0071] S12: Multiply the fuel quantity set value F total (generated by the PID control algorithm) generated by the boiler main controller according to the load command and the steam pressure deviation by k 0 to obtain the ammonia supply quantity set value F NH3 =k 0 ×F total ;

[0072] S13: After converting the ammonia supply quantity set value F NH3 by calorific value, form an equivalent converted coal quantity command F coal-eq =F NH3 ×(LHV n / LHV m );

[0073] S14: Calculate the coal supply quantity set value F coal =F total -F coal-eq .

[0074] The boiler combustion control method for ammonia - coal dual - fuel blending of the present invention can achieve automatic reduction or increase of the coal supply quantity with the increase or decrease of the ammonia blending ratio during the ammonia - coal dual - fuel blending process, realizing automatic balance of the fuel quantity.

[0075] As a preferred embodiment, the control method of the present invention further includes a step of correcting the ammonia blending ratio. Specifically, it includes step S2: Real - time monitor the NOx concentration C _NOx at the furnace outlet and the unburned NH 3 concentration C _NH3， . Dynamically correct the ammonia blending ratio according to the concentration deviation, and generate a new ammonia supply quantity set value and a new coal supply quantity set value according to the corrected ammonia blending ratio by the method of steps S12 - S14. Among them, the correction of the ammonia blending ratio is specifically:

[0076] When C _NOx >C goal_NOx When k 1 =k 0 ×[1+0.05×(C _NOx - C goal_NOx ) / 10] to increase the ammonia blending ratio; further, k 1 Correction coefficient range 1.05-1.15;

[0077] When C _NH3 >C goal_ NH3 When k 2 =k 0 ×[1-0.03×(C _NH3 - C goal_ NH3 ) / 10] reduce the ammonia mixing ratio; further, k 2 The correction coefficient range is 0.85-0.95.

[0078] In this embodiment, according to the real-time monitoring of the furnace outlet product NOx concentration, NH 3 The escape concentration value adjusts the boiler operating parameters to ensure that the NOx concentration at the furnace outlet does not exceed the standard and that the ammonia is fully burned.

[0079] The specific implementation is as follows: set the ammonia blending ratio value, multiply the corrected ammonia blending ratio value by the fuel setting value signal output by the boiler main controller to generate a corrected ammonia supply instruction under the corrected ammonia blending ratio, and use the corrected ammonia supply instruction as the ammonia supply setting value; convert the above ammonia supply setting value according to the calorific value to form an equivalent converted coal quantity instruction; the fuel quantity setting value signal from the boiler main controller under different loads and different ammonia blending ratios is logically subtracted from the equivalent converted coal quantity instruction to generate a new coal supply setting value; this new coal supply setting value enters the coal supply control system to replace the original coal supply setting value. In this way, in the process of ammonia-coal dual fuel blending, as the ammonia blending ratio increases, the coal supply is automatically reduced to achieve fuel balance.

[0080] Preferably, the control method of this embodiment further includes the step of controlling the excess air coefficient; the boiler operation parameter also includes the excess air coefficient; the control method further includes the step of controlling the excess air coefficient within a preset range, specifically including the following steps:

[0081] S31: Real-time monitoring of the NOx concentration C at the furnace outlet _NOx and unburned NH 3 Concentration C _NH3 , adjust the boiler air supply according to the concentration deviation; adjust the boiler air supply according to the current furnace outlet product NOx concentration and the furnace outlet product NOx concentration target value and the current unburned NH 3 Real-time concentration and unburned NH 3The air supply volume is adjusted based on the comparison result of the target value;

[0082] S32: Adjust the graded air distribution according to the adjusted air supply volume so that the excess air coefficient is within a preset range.

[0083] Specifically, according to the NOx concentration of the furnace outlet product and the current unburned NH 3 Real-time concentration, and the NOx concentration of the furnace outlet products, unburned NH 3 By comparing with the concentration target value, the product adjustment signal value of the furnace outlet is calculated, and the corresponding combustion reaction adjustment conditions are calculated. The boiler air supply volume set value is adjusted according to the calculated combustion reaction adjustment conditions. This air supply volume set value can also be processed by cross-limiting the total fuel amount to obtain a new air supply volume set value. This new air supply volume set value enters the air supply volume control system and replaces the original air supply volume set value.

[0084] Preferably, the control of the excess air coefficient includes controlling the total excess air coefficient of the boiler within a preset range. total Greater than 1.1; and control the local excess air coefficient α in the main combustion zone of ammonia-coal co-combustion local Less than 0.8.

[0085] Preferably, the method for adjusting the graded air distribution includes adjusting the air supply volume of the secondary air door of the main combustion zone and the air supply volume of the burnout zone. By adjusting the secondary air opening and the burnout air door opening of the main combustion zone, the local excess air coefficient of the main combustion zone of ammonia-coal mixed combustion is adjusted to make the main combustion zone in a relatively low reducing atmosphere, thereby reducing the generation of fuel-type NOx in the ammonia-coal dual fuel blending. The specific steps include:

[0086] When the NOx concentration exceeds the target value C of the furnace outlet product NOx concentration goal_NOx When the secondary air volume in the main combustion zone is reduced to 40%-50% of the total air volume, the SOFA damper opening in the burnout zone is increased to 70%-80% to achieve oxygen-deficient combustion in the main combustion zone.

[0087] When the unburned NH 3 Concentrations exceeding unburned NH 3 Concentration target value C goal_ NH3 When the oxygen concentration in the main combustion zone is increased to 23%-25%.

[0088] As a preferred embodiment, the control method of the present invention also includes the step of correcting the ammonia blending ratio by using the furnace temperature field and the furnace outlet smoke temperature. Specifically: the control method also includes the following steps: S4: real-time monitoring of the furnace temperature field and the furnace outlet smoke temperature, using the furnace temperature field and the furnace outlet smoke temperature to correct the ammonia blending ratio, and generating a new ammonia feed setting value and a new coal feed setting value according to the corrected ammonia blending ratio. Specifically including: when the average value of the temperature gradient deviation at the four corners of the furnace and / or the average value of the furnace outlet smoke temperature deviation ΔT is greater than 50°C for 30 consecutive minutes, according to the formula k 3 =k 0 ×(1-0.1×ΔT / 50) triggers the ammonia blending ratio correction, correction coefficient k 3 =0.9-1.1.

[0089] Accordingly, the present invention also provides a boiler combustion control system for ammonia-coal dual fuel blending, comprising: a central control module 100, a monitoring module 200, an execution module 300 and an alarm module 400; the central control module 100 is electrically connected or communicatively connected with the monitoring module 200, the execution module 300 and the alarm module 400;

[0090] The central control module 100 is used to generate a corresponding control strategy according to the boiler load and the ammonia blending ratio requirement when ammonia-coal dual fuel is blended, and to adjust the control strategy according to the information of the monitoring module 200 to generate a new control strategy, and send the control strategy to the execution module 300; the central control module includes a fuel quantity calculation unit 110 and an air volume distribution unit 120, the fuel quantity calculation unit 110 is used to execute any one of the control methods in steps S1-S4 of the claims, and the air volume distribution unit 120 is connected to the air distribution system to execute the air distribution control strategy of step S3 of the claim;

[0091] The execution module 300 is used to adjust the boiler operating parameters during the ammonia-coal dual fuel blending process according to the received control strategy; the execution module includes an ammonia supply regulating valve 310, a coal feeder speed actuator 320, an air supply volume regulator 330, a secondary air door actuator 340 and a SOFA air door actuator 350;

[0092] The monitoring module 200 is used to monitor the three-dimensional temperature field of the furnace, the smoke temperature at the furnace outlet, and the NOx concentration and unburned NH 3 concentration;

[0093] The alarm module 400 is used to generate an audible, visual or vibration alarm when the ammonia escape value at the furnace outlet exceeds a threshold value;

[0094] The information received by the central control module 100 includes the real-time monitoring of the furnace temperature field, furnace outlet smoke temperature, furnace outlet product NOx concentration, NH 3 concentration.

[0095] The execution module 300 is also used to adjust the boiler operating parameters in the ammonia-coal dual-fuel mixed combustion process in real time according to the new control strategy.

[0096] In the embodiment of the present invention, Figure 1 As shown, the monitoring module includes a furnace temperature field monitoring unit 210, a furnace outlet smoke temperature monitoring unit 220, a furnace outlet NOx concentration monitoring unit 230 and a furnace outlet unburned NH 3 Concentration monitoring unit 240.

[0097] like Figure 2 As shown, the ammonia-coal dual-fuel mixed boiler system includes a furnace 001, an economizer 002, a platen superheater 003, a denitrification SCR device 004 and an ammonia-coal burner group 005.

[0098] The furnace temperature field monitoring unit 210 monitors the two-dimensional temperature field of the furnace in the horizontal and vertical directions through the first temperature measuring element 211 installed in the horizontal and vertical directions of the furnace 001, and obtains the three-dimensional temperature field of the furnace through the temperature field inversion reconstruction of the algorithm server. The furnace outlet smoke temperature monitoring unit 220 measures through the second temperature measuring element 212 installed at the furnace outlet to obtain the furnace outlet smoke temperature value;

[0099] The furnace outlet NOx concentration monitoring unit 230 includes an online flue gas analyzer 231 installed in the economizer outlet flue. 3 The concentration monitoring unit 240 includes an ammonia escape laser detector 241 installed in the economizer outlet flue. The online flue gas analyzer 231 is used to monitor the NOx concentration at the furnace outlet. The ammonia escape laser detector 241 is used to monitor the unburned NH 3 concentration.

[0100] In the embodiment of the present invention, the first temperature measuring element 211 is an infrared CCD camera with a spectral response range of 3-5um, and the second temperature measuring element is a furnace infrared pyrometer; see Figure 3 , the first temperature measuring element 211 is also connected to other hardware systems, and the other hardware systems include a temperature field algorithm server 130, a PLC controller 140 and a power module 500;

[0101] Among them, the first temperature measuring element 211 transmits the measured data to the temperature field algorithm server 130 through optical fiber, the temperature field algorithm server 130 and the PLC controller 140 are connected through a communication network, and data transmission is based on the TCP / IP protocol, and the three-dimensional temperature field data of the furnace inverted by the temperature field algorithm server 130 is transmitted to the PLC controller 140; the PLC controller 140 and the central control module 100 are connected through a communication link, and data transmission is based on the Modbus protocol, and the PLC controller 140 transmits the three-dimensional temperature field data of the furnace to the central control module 100.

[0102] Before the formal measurement and installation, the first temperature measuring element 211 needs to be calibrated. The calibration is performed using a black body furnace to obtain the quantitative relationship between image intensity and radiation intensity (1): I = A 1 T g +A 2 T w =AT 0

[0103] Where I is the radiation intensity image matrix received by the first temperature measurement element; T is the actual three-dimensional temperature matrix of the furnace; T g is the fourth-order matrix of the temperature of the spatial discrete unit; Tw is the fourth-order matrix of the temperature of the wall discrete unit; A 1 , A 2 , A is the radiation intensity imaging matrix, which is mainly determined by the radiation characteristics of the medium and the wall, the DRESOR number, the geometric dimensions of the furnace and the camera coordinates.

[0104] During the implementation of the furnace temperature field monitoring unit, in order to ensure that the first temperature measuring element 211 receives the unsaturated thermal radiation signal, a radiation temperature imaging model based on the normalization processing of the above-mentioned radiation intensity imaging matrix is ​​adopted, as shown in formula (2): 1 s T g +A 2 s T w =A s T=T CCD

[0105] Among them, A 1 s , A 2 s , A s is the radiation temperature imaging matrix, which is the matrix A 1 , A 2 , each number in A is divided by the sum of all the numbers in the row where the number is located; T CCDis the fourth - order matrix of the combustion temperature image obtained by the first temperature - measuring element, which can be calculated by the colorimetric method based on the three primary colors of a color CCD.

[0106] Therefore, according to the combustion temperature image detected by the first temperature - measuring element, the actual temperature distribution T in the furnace can be solved by using the inversion algorithm through Equation (2).

[0107] In one of the embodiments, referring to Figure 2 , first temperature - measuring elements 211 are arranged both in the horizontal and vertical directions of the furnace 001.

[0108] Furthermore, the two first temperature - measuring elements 211 arranged in the horizontal direction of the boiler are respectively set on the left and right walls of the furnace 001 of the tangentially - fired ammonia - coal co - firing boiler at the four corners, and are both 8 m above the burner group 005 of the ammonia - coal co - firing boiler in the height direction. Further, the direction of the first temperature - measuring element in the horizontal direction forms a certain angle with the boiler axis, with a horizontal field of view angle of 55° and a vertical field of view angle of 45°. The two are arranged in a staggered manner, and the size of the transverse field - of - view projection cross - section that can be covered is 15717 m×11790 m (width×depth).

[0109] Furthermore, the two first temperature - measuring elements 211 arranged in the vertical direction of the boiler are set at two observation holes along the height direction of the front wall of the furnace 001 of the tangentially - fired ammonia - coal co - firing boiler. In the height direction, it is ensured that the vertical - direction fields of view of the two first temperature - measuring elements can cover the entire burner area of the furnace. The direction of the first temperature - measuring element in the vertical direction forms a certain angle with the boiler axis, with a horizontal field of view angle of 80° and a vertical field of view angle of 55°. The size of the longitudinal field - of - view projection cross - section that can be covered is 11790 m×14628 (depth×height).

[0110] In this embodiment, the second temperature - measuring element 212 is arranged at the furnace outlet to measure the flue gas temperature at the furnace outlet and feedback the change of the heat absorption distribution in the furnace. When the furnace outlet temperature rises, it indicates that the radiant heat absorption in the furnace decreases. When the flue gas temperature at the upper furnace outlet decreases, it indicates that the radiant heat absorption in the furnace increases.

[0111] According to the ammonia combustion characteristics (the adiabatic flame temperature of ammonia is relatively low, and ammonia combustion will compete with pulverized coal for oxygen, resulting in a delay in pulverized coal ignition) and the combustion product characteristics (complete combustion generates N 2 and H 2O, only gas radiation, no solid particulate matter radiation such as soot and fly ash), may cause the center temperature of the furnace flame to drop, or the center of the furnace flame to move upward, thereby causing changes in the heat flux distribution in the furnace and affecting the boiler steam parameter adjustment. Combined with the three-dimensional temperature field measurement of the furnace and the flue gas temperature measurement at the furnace outlet of this embodiment, the changes in the furnace temperature field and the flue gas temperature at the furnace outlet during the ammonia-coal dual-fuel mixed combustion can be monitored in real time, and the changes in the heat flux distribution in the furnace during the ammonia-coal dual-fuel mixed combustion can be judged, and then the corresponding boiler "boiler" side steam-water parameters and "furnace" side combustion parameters are adjusted to ensure the boiler combustion stability during the ammonia-coal dual-fuel mixed combustion process.

[0112] In the embodiments of the present invention, see Figure 1 , the monitoring module 200 further includes:

[0113] The steam parameter monitoring unit 250 is used to monitor the main steam parameter value and the reheat steam parameter value of the boiler in the ammonia-coal dual-fuel mixed combustion;

[0114] The desuperheating water monitoring unit 260 is used to monitor the desuperheating water volume of the main steam and reheat steam of the boiler in the ammonia-coal dual-fuel mixed combustion;

[0115] Fuel quantity monitoring unit 270: used to monitor the boiler coal consumption and ammonia consumption in the ammonia-coal dual-fuel mixed combustion;

[0116] The air volume monitoring unit 280 is used to monitor the total air volume and burnout air volume in the ammonia-coal dual-fuel mixed combustion, thereby monitoring the total excess air coefficient value of the boiler combustion and the excess air coefficient value of the main combustion zone.

[0117] In this embodiment, the central control module monitors the boiler furnace temperature field value, furnace outlet smoke temperature value, furnace outlet product NOx concentration, unburned NH 3 The concentration value, boiler total fuel and air volume value, boiler total excess air coefficient value and boiler main combustion zone excess air coefficient value generate adjustment strategy.

[0118] In this embodiment, the central control module 100 includes a control strategy generation unit, an adjustment strategy generation unit and a control strategy adjustment unit;

[0119] The control strategy generation unit is used to generate boiler operating parameters during the ammonia-coal dual fuel blending process according to the boiler load and ammonia blending ratio requirements during the ammonia-coal dual fuel blending process;

[0120] The adjustment strategy generation unit measures the boiler furnace temperature field, furnace outlet smoke temperature, furnace outlet product NOx concentration, and unburned NH 3 The concentration value is related to the set boiler furnace temperature field, furnace outlet smoke temperature, furnace outlet product NOx concentration, unburned NH 3The boiler operation parameters are adjusted based on the calculated combustion reaction conditions.

[0121] The control strategy adjustment unit is used to update the control strategy according to the adjustment strategy generated by the adjustment strategy generation unit to obtain a new control strategy.

[0122] The control strategy generated by the control strategy generation unit is based on the original coal-fired boiler combustion optimization, focusing on achieving automatic balance control of coal and ammonia in the process of ammonia-coal dual fuel blending. The control strategy includes adjustment methods and control parameters corresponding to different loads and different ammonia-coal blending ratios;

[0123] The adjustment strategy generation unit is based on the furnace outlet products NOx and unburned NH 3 Optimize the total excess air coefficient and local excess air coefficient (main combustion zone) according to the specific situation.

[0124] Among them, the main adjustment measures for fuel balance are based on the boiler coordinated control system and the coal feed control system, and are specifically implemented as follows: set the ammonia blending ratio value, multiply the set ammonia blending ratio value by the fuel set value signal output by the boiler main controller to generate an ammonia feed instruction under the set ammonia blending ratio, and use the furnace outlet product furnace outlet product and unburned NH 3 The above-mentioned ammonia supply instruction is corrected by the concentration, and the corrected ammonia supply instruction is used as the ammonia supply setting value; the above-mentioned ammonia supply setting value is converted according to the calorific value to form an equivalent converted coal quantity instruction; the fuel quantity setting value signal from the boiler main controller under different loads and different ammonia blending ratios is logically subtracted from the equivalent converted coal quantity instruction to generate a new coal supply setting value; this new coal supply setting value enters the coal supply control system to replace the original coal supply setting value. In this way, during the ammonia-coal dual fuel blending process, as the ammonia blending ratio increases, the coal supply is automatically reduced to achieve fuel balance;

[0125] Secondly, the optimization configuration measures of the excess air coefficient are based on the boiler air supply control system and the graded air distribution control system. The specific description is as follows: according to the NOx concentration of the furnace outlet product, the unburned NH 3 Real-time concentration and furnace outlet product NOx / O 2 concentration, unburned NH 3By comparing with the target concentration value, the product adjustment signal value at the furnace outlet is calculated, and the corresponding combustion reaction adjustment conditions are calculated. The boiler air supply volume set value is adjusted according to the calculated combustion reaction adjustment conditions. This air supply volume set value can also be processed by cross-limiting the total fuel amount to obtain a new air supply volume set value. This new air supply volume set value enters the air supply volume control system and replaces the original air supply volume set value, thereby adjusting the total excess air coefficient of the boiler (generally greater than 1.1); by adjusting the secondary air opening and the burnout damper opening in the main combustion zone, the local excess air coefficient of the main combustion zone of ammonia-coal co-firing is adjusted (generally less than 0.8), so that the main combustion zone is in a lower reducing atmosphere, thereby reducing the generation of fuel-type NOx in the ammonia-coal dual-fuel blending.

[0126] In an embodiment of the present invention, the central control module further includes a user interface for inputting the ammonia blending ratio, main steam pressure, furnace outlet flue gas temperature, furnace outlet product NOx / unburned NH 3 Target value of concentration.

[0127] In an embodiment of the present invention, the alarm module 400 includes an audible and visual alarm and a vibrator, which are electrically connected to the central control unit 100. When the ammonia escape concentration value at the furnace outlet exceeds the alarm threshold, the central control unit 100 outputs an electrical signal to the audible and visual alarm and the vibrator, causing them to emit audible and visual alarms and vibration alarms.

[0128] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0129] The parts not elaborated in detail in the description of the present invention belong to the known technology in the art. The above embodiments are provided only for the purpose of describing the present invention, and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. Various equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A combustion control method for a boiler with dual fuel of ammonia and coal, characterized in that: The steps include: S1: generating boiler operating parameters in the process of ammonia-coal dual-fuel blending according to the boiler load and ammonia blending ratio requirement during ammonia-coal dual-fuel blending; the boiler operating parameters include an ammonia feed amount set value and a coal feed amount set value; Wherein step S1 specifically comprises the following steps: S11: Setting the initial ammonia blending ratio k0, which is determined according to the boiler fuel calorific value ratio, and the calculation formula is k0=(m n ×LHV n ) / (m n ×LHV n +m m ×LHV m ), where m n is the mass flow rate of ammonia fuel, m m is the coal fuel mass flow rate, LHV n The lower heating value of ammonia fuel, LHV m It is the low calorific value of coal fuel; S12: Set the fuel quantity setting value F generated by the boiler main controller according to the load instruction and the steam pressure deviation total Multiply by k0 to get the ammonia setting value F NH3 =k0×F total ; S13: Set the ammonia supply amount to a value F NH3 After conversion according to the calorific value, the equivalent converted coal quantity instruction F is formed coal-eq =F NH3 ×(LHV n / LHV m ); S14: Calculate the coal feed setting value F coal =F total -F coal-eq .

2. The method for controlling combustion of a boiler using dual fuel of ammonia and coal as claimed in claim 1, characterized in that: The boiler combustion control method further comprises the following steps: S2: Real-time monitoring of the NOx concentration C at the furnace outlet _NOx and the unburned NH3 concentration C _NH3 , dynamically correct the ammonia blending ratio according to the concentration deviation; generate a new ammonia feed amount setting value and a new coal feed amount setting value according to the corrected ammonia blending ratio; The specific correction of the ammonia blending ratio is as follows: When C _NOx >C goal_NOx According to the formula k1=k0×[1+0.05×(C _NOx -C goal_NOx ) / 10] increase the ammonia blending ratio, the correction coefficient range is 1.05-1.15; When the unburned NH3 concentration C _NH3 >C goal_ NH3 According to the formula k2=k0×[1-0.03×(C _NH3 - C goal_ NH3 ) / 10] reduce the ammonia blending ratio, and the correction coefficient range is 0.85-0.

95.

3. The combustion control method of ammonia-coal dual fuel blended boiler according to claim 1, characterized in that: The boiler operating parameters also include excess air coefficient; the control method also includes the following steps: S3: step of controlling the excess air coefficient within a preset range; Specifically, step S3 includes the following steps: S31: Real-time monitoring of the NOx concentration C at the furnace outlet _NOx and the unburned NH3 concentration C _NH3 , adjust the boiler air supply according to the concentration deviation; S32: Control the excess air coefficient within a preset range by graded air distribution according to the adjusted air supply volume; wherein, the control of the excess air coefficient within the preset range includes controlling the total excess air coefficient of the boiler α total >1.1; and control the local excess air coefficient α in the main combustion zone of ammonia-coal co-combustion local <0.8, the graded air distribution method includes adjusting the air supply volume of the secondary air door in the main combustion zone and the air supply volume in the burnout zone. The specific adjustments include the following: When C _NOx The concentration exceeds the target value C of the NOx concentration of the furnace outlet product goal_NOx When the secondary air volume in the main combustion zone is reduced to 40%-50% of the total air volume, the SOFA damper opening in the burnout zone is increased to 70%-80%; When the unburned NH3 concentration C _NH3 Exceeding the target value C of unburned NH3 concentration goal_ NH3 When the oxygen concentration in the main combustion zone is increased to 23%-25%.

4. The combustion control method of ammonia-coal dual fuel blended boiler according to claim 1, characterized in that: The control method further comprises the following steps: S4: Real-time monitoring of the furnace temperature field and the furnace outlet smoke temperature, and correction of the ammonia blending ratio k0 using the furnace temperature field and the furnace outlet smoke temperature; Specifically: when the average temperature gradient deviation of the four corners of the furnace and / or the average flue gas temperature deviation of the furnace outlet is monitored for 30 consecutive minutes and is greater than 50°C, the ammonia blending ratio correction is triggered according to the formula k3=k0×(1-0.1×ΔT / 50), and the correction coefficient ranges from 0.9 to 1.

1.

5. A combustion control system for a boiler with dual fuel of ammonia and coal, characterized in that: The control system comprises: A central control module, a monitoring module, an execution module and an alarm module; the central control module is electrically or communicatively connected with the monitoring module, the execution module and the alarm module; The central control module is used to generate a corresponding control strategy according to the boiler load and the ammonia blending ratio requirement when ammonia-coal dual fuel is blended, and to adjust the control strategy according to the information of the monitoring module to generate a new control strategy, and send the new control strategy to the execution module; the central control module includes a fuel quantity calculation unit and an air volume distribution unit, the fuel quantity calculation unit is used to execute any one of the control methods in steps S1-S4, and the air volume distribution unit is connected to the air distribution system to execute the air distribution control strategy of step S3; The execution module is used to adjust the boiler operating parameters in the ammonia-coal dual fuel blending process according to the received control strategy; the execution module includes an ammonia supply regulating valve, a coal feeder speed actuator, an air supply volume regulator, a secondary air door and a SOFA air door actuator; The monitoring module is used to monitor in real time the NOx concentration and unburned NH3 concentration at the furnace outlet during the ammonia-coal dual-fuel mixed combustion process, as well as the three-dimensional temperature field of the furnace and the smoke temperature at the furnace outlet; The alarm module is used to generate sound, light or vibration alarm when the ammonia escape value at the furnace outlet exceeds a threshold value.

6. The ammonia-coal dual fuel blended boiler combustion control system according to claim 5 is characterized in that: The monitoring module includes a furnace outlet NOx concentration monitoring unit, a furnace outlet unburned NH3 concentration monitoring unit, a furnace temperature field monitoring unit, and a furnace outlet smoke temperature monitoring unit; The furnace outlet NOx concentration monitoring unit and the furnace outlet unburned NH3 concentration monitoring unit include an online flue gas analyzer and an ammonia escape laser detector installed in the economizer outlet flue, wherein the online flue gas analyzer is used to monitor the furnace outlet NOx concentration, and the ammonia escape laser detector is used to monitor the furnace outlet unburned NH3 concentration; The furnace temperature field monitoring unit includes a first temperature measuring element and a data processing module; the data processing module obtains the three-dimensional temperature field of the furnace according to the measurement result of the first temperature measuring element; The furnace outlet smoke temperature monitoring unit measures the furnace outlet smoke temperature value by means of a second temperature measuring element installed at the furnace outlet.

7. The ammonia-coal dual fuel blended boiler combustion control system according to claim 6 is characterized in that: The first temperature measuring element is an infrared CCD camera; the second temperature measuring element is a furnace infrared pyrometer.

8. The ammonia-coal dual fuel blended boiler combustion control system according to claim 6 is characterized in that: The data processing module includes a temperature field algorithm server, a PLC controller, a communication link, a communication network and a power supply module; Among them, the first temperature measuring element transmits the measured data to the temperature field algorithm server through optical fiber, the temperature field algorithm server and the PLC controller are connected through a communication network, and data transmission is performed based on the TCP / IP protocol, and the three-dimensional temperature field data of the furnace inverted by the temperature field algorithm server is transmitted to the PLC controller; the PLC controller and the central control module are connected through a communication link, and data transmission is performed based on the Modbus protocol, and the PLC controller transmits the three-dimensional temperature field data of the furnace to the central control module.

9. The ammonia-coal dual fuel blended boiler combustion control system according to claim 6, characterized in that: First temperature measuring elements are arranged in both the horizontal and vertical directions of the furnace.

10. The ammonia-coal dual fuel blended boiler combustion control system according to claim 9, characterized in that: Two first temperature measuring elements are arranged in the horizontal direction of the furnace; the two first temperature measuring elements are arranged in a relatively staggered manner, and the two first temperature measuring elements are arranged above the burner of the ammonia-coal mixed-firing boiler; And / or, two first temperature measuring elements are arranged in the vertical direction of the furnace; the two first temperature measuring elements are arranged on the front wall of the burner of the ammonia-coal mixed firing boiler and are arranged along the height direction.

11. The ammonia-coal dual fuel blended boiler combustion control system according to claim 10, characterized in that: The horizontal and vertical viewing angles of the two first temperature measuring elements arranged in the horizontal direction both form a certain angle with the boiler axis; the horizontal and vertical viewing angles of the two first temperature measuring elements arranged in the height direction both form a certain angle with the boiler axis.

12. The ammonia-coal dual fuel blended boiler combustion control system according to claim 11, characterized in that: The horizontal viewing angle of the two first temperature measuring elements arranged in the horizontal direction and the angle between them and the axis of the boiler are 45°, and the vertical viewing angle of the two first temperature measuring elements arranged in the horizontal direction and the angle between them and the axis of the boiler are 45°; The horizontal viewing angle of the two first temperature measuring elements arranged in the height direction and the angle between them and the axis of the boiler are 80°, and the vertical viewing angle of the two first temperature measuring elements arranged in the height direction and the angle between them and the axis of the boiler are 55°; The viewing angle ensures that the furnace cross-section coverage is greater than 95%.

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