A method for controlling the combustion temperature of a pulse-fired furnace burner

Abstract

The application discloses a combustion temperature control method of a pulse heating furnace burner, which realizes the control of the uniformity and stability of pulse combustion from the monitoring and adjustment of two dimensions of whether the pressure parameter of a total pipe before the establishment of the burner is stable and whether the combustion performance of the burner itself is stable. The combustion temperature control method of the pulse heating furnace burner of the application starts from two aspects of whether the pressure parameter of the total pipe before the establishment of the burner is stable and whether the combustion performance of the burner itself is stable, controls the uniformity and stability of pulse combustion, provides replacement basis for the certain replacement of the burner and the valve, and saves the cost.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of industrial thermal engineering, and particularly relates to a method for controlling the combustion temperature of a pulse heating furnace burner. BACKGROUND

[0002] The performance and shape of hot-rolled products are greatly affected by temperature uniformity. As a key quality control element of products, there is no relevant technical material or literature introduced at home and abroad. The key technology of pulse heating mainly reflects in the temperature uniformity, combustion stability, and matching of long and short flame control during pulse combustion. The French Stein Company has a strong research and technical advantage in pulse combustion, but its core technology of pulse combustion adopts black box security technology, so its core technology is rarely known.

[0003] In order to realize the uniformity and stability of combustion in the prior art, a control scheme is established from the combustion process (as listed in the following four prior art), and the influence of the combustion source end on the combustion performance is usually neglected. When the combustion source end has a major impact, the exhaust gas temperature is monitored, and then the sequence of replacing the valve and the burner is performed to exclude the major impact accident. In the existing processing method, when the furnace area is in a low heating load state, a combined control scheme of establishing a low heating load state level division + extending the combustion intermittent time of the pulse burner + controlling the furnace temperature on both sides respectively is usually adopted. In the existing scheme, on the one hand, the service of combustion uniformity and stability is not established from the combustion source end, and on the other hand, the replacement of the combustion source end is an experience-based operation with a certain blindness. Since there is no confirmation basis for specific problem points, this operation method has the problem of not confirming the problem in place at one time and wasting cost.

[0004] The application No. CN201210034821.8 discloses a "heat storage pulse heating furnace combustion control method", which comprises: obtaining the flow set value of the current section and the flow grading threshold table specified by the process, dividing the flow set value by the maximum flow value of the section to obtain the flow set percentage, then comparing it with the flow grading threshold table to determine the current new flow level and the number of burners put into operation; according to the standard exhaust gas flow and the furnace gas temperature corresponding to the new flow level, the exhaust gas temperature curve corresponding to the given heat storage reversing period is calculated by using the heat storage tank model; according to the heat storage tank exhaust gas temperature set by the process, combined with the exhaust gas temperature curve, the heat storage reversing period corresponding to the exhaust gas temperature is determined by interpolation; according to the number of burners put into operation determined by the new flow level, the total number of available burners in the section and the heat storage reversing period, the heat storage pulse period and the grouping rolling method are determined; the heat storage combustion control and heat storage pulse logic control are performed according to the heat storage reversing period, the heat storage pulse period and the grouping rolling method.

[0005] The application number is CN201710292582.9, and a hot rolling pulse heating furnace combustion control method is disclosed. By introducing low heat value combustion control on the basis of pulse combustion, the corresponding coal gas heat value under low load is calculated, and the air-fuel ratio and air-coal gas pipeline pressure required for pulse combustion are established based on this. The calculated coal gas heat value and air-coal gas pipeline pressure are sent to the coal gas heat value adjusting mechanism and the heating furnace basic combustion control mechanism respectively, automatic control of pulse combustion is realized, the pulse burner combustion time is prolonged, the number of burner valve switching is reduced, and the uniformity of the furnace temperature is improved.

[0006] The application number is CN201910786473.1, and a pulse heating furnace system and control method are disclosed. The pulse heating furnace system includes a heating furnace, an air main pipe, and a fuel gas main pipe. At least one furnace temperature control zone is arranged in the heating furnace. Each furnace temperature control zone includes a pulse burner and a furnace temperature detection device. The air main pipe and the pulse burner are connected through an air branch pipe. The fuel gas main pipe and the pulse burner are connected through a fuel gas branch pipe. The control method needs to adjust the air capacity of each pulse burner based on the air main pipe pressure, adjust the fuel gas capacity of each pulse burner based on the fuel gas main pipe pressure, and control the total fuel gas amount and the total air amount.

[0007] The application number is CN202010599813.2, and a pulse control for heating furnace burners and a furnace temperature control method for pulse furnaces are disclosed. The heating furnace is divided into several temperature control zones along the furnace length direction, and a thermocouple is arranged on the left and right sides of the furnace chamber of each temperature control zone. The uniform combustion control of each zone is formed by the heat load demand of each temperature control zone and the temperature difference of the two thermocouples in each zone. The input mode of the burners, the triggering sequence between zones, and the pulse operation mode within each temperature control zone are determined by the heat load demand of each temperature control zone. The uniform combustion control of each burner in time and space is formed by the cooperation of the input mode of the burners, the triggering sequence of each zone, and the pulse operation mode within each zone. The pulse control for heating furnace burners and the furnace temperature control method for pulse furnaces realize the temperature uniformity control of the slabs. SUMMARY

[0008] To solve the above problems, the present application provides a pulse heating furnace burner combustion temperature control method, and the technical scheme is as follows:

[0009] A pulse heating furnace burner combustion temperature control method, characterized by:

[0010] The combustion temperature control method realizes the control of the uniformity and stability of the pulse combustion by monitoring and adjusting from two dimensions of whether the pressure parameter of the total pipe before the burner is stable and whether the combustion performance of the burner itself is stable.

[0011] The combustion temperature control method of the pulse heating furnace burner according to the application is characterized in that:

[0012] The monitoring and adjusting of whether the pressure parameter of the total pipe before the burner is stable is completed by monitoring and adjusting two parameters of the monitoring and adjusting of the coal gas pressure and the monitoring and adjusting of the air-fuel ratio.

[0013] The combustion temperature control method of the pulse heating furnace burner according to the application is characterized in that:

[0014] The monitoring and adjusting of whether the combustion performance of the burner itself is stable is realized by comparing the actual preheating air temperature value of the heated medium out of the preheating burner with the set value in real time, and when the absolute value of the difference between the two exceeds the set threshold value, the whole burner or the fin preheater is replaced, otherwise the burner performance is considered stable.

[0015] The combustion temperature control method of the pulse heating furnace burner according to the application is characterized in that:

[0016] The monitoring and adjusting of the coal gas pressure is completed by the two parallel operations of the set combustion timing rhythm and the dynamic correction of the coal gas pressure based on the lambda value.

[0017] The combustion temperature control method of the pulse heating furnace burner according to the application is characterized in that:

[0018] The monitoring and adjusting of the air-fuel ratio is completed by the two parallel operations of the monitoring and adjusting of the air-fuel ratio of the section and the monitoring and adjusting of the pressure difference before the single burner.

[0019] The combustion temperature control method of the pulse heating furnace burner according to the application is characterized in that:

[0020] The "by comparing the actual preheating air temperature value of the heated medium out of the preheating burner with the set value in real time, and when the absolute value of the difference between the two exceeds the set threshold value, the whole burner or the fin preheater is replaced, otherwise the burner performance is considered stable" is specifically:

[0021] S1: calculate the heat absorbed by the air in real time, calculate the flue gas outlet temperature based on the heat balance equation according to the calculation result, and compare the calculation result with the set value, if the difference between the two is less than the set threshold value, it is determined that the burner combustion performance is stable, otherwise step S2 is entered;

[0022] S2: sequentially calculating air average temperature, flue gas average temperature, air side heat release coefficient, flue gas side heat release coefficient, heat transfer coefficient, logarithmic mean temperature difference, heat transfer area of preheating burner, and total length of burner fin preheater required, and replacing the burner fin preheater with corresponding size according to the calculated total length of burner fin preheater.

[0023] The combustion temperature control method of the pulse heating furnace burner according to the present application is characterized in that:

[0024] The monitoring and adjustment of the stability of the combustion performance of the burner itself is based on the monitoring and adjustment of the pressure difference before the single burner.

[0025] The combustion temperature control method of the pulse heating furnace burner according to the present application is characterized in that:

[0026] The established combustion timing beat is specifically:

[0027] I: establishing the combustion of each burner in each zone in a control mode of time stagger of each burner in each zone with the limit of at most 2 burners allowed to be opened and closed at the same time in each zone;

[0028] II: when the situation of simultaneous opening of burners between zones appears in the temperature control zone, whether each zone is allowed to be opened simultaneously and the delay processing of the temperature control zone according to the real-time temperature difference of each zone are determined according to the number of total input zones and the total number of burners opened simultaneously between zones.

[0029] The combustion temperature control method of the pulse heating furnace burner according to the present application is characterized in that:

[0030] The dynamic correction of the coal gas pressure based on the monitoring of the Wobbe value is specifically:

[0031] The coal gas pressure represented by the Wobbe value is taken as the control reference, and the corresponding coal gas pressure value is adjusted according to the real-time Wobbe value change.

[0032] The combustion temperature control method of the pulse heating furnace burner according to the present application is characterized in that:

[0033] The monitoring and adjustment of the air-fuel ratio of the section are specifically:

[0034] SA1: calculating the dynamic set value of the pressure of the coal gas and the total pipe pressure according to the real-time Wobbe value, and calculating the real-time air-fuel ratio according to the calculation result;

[0035] SA2: Establishes a regulation of the air flow set value around the set air-fuel ratio as a reference, to the real-time calculated air-fuel ratio, and the regulation is completed by regulating the opening degree of the air valve.

[0036] According to the pulse heating furnace burner combustion temperature control method of the present application, the features are:

[0037] The "monitoring and adjusting the pressure difference before the single burner" is specifically:

[0038] Under the standard white value working condition, the burner gas hole plate differential pressure and the air hole plate differential pressure are measured and calculated in real time, when the absolute value of the difference between the real-time measurement and calculation result and the factory calibration differential pressure is less than or equal to the set threshold value, it is considered that the hole plate and the ON-OFF valve opening degree work normally, otherwise it is considered as a hole plate differential pressure abnormality determination result processing and hole plate or ON-OFF valve blockage is processed.

[0039] According to the pulse heating furnace burner combustion temperature control method of the present application, the features are:

[0040] The opening degree of the regulating valve is within the regulating range composed of the set regulating upper limit and the regulating lower limit,

[0041] The regulating upper limit is 40% of the valve opening degree + gas quantity percentage / 2.0;

[0042] The regulating lower limit is gas quantity percentage / 2.5.

[0043] According to the pulse heating furnace burner combustion temperature control method of the present application, the features are:

[0044] The "control mode of opening time of each burner in each zone is staggered" is specifically staggered according to the interval of 1S-2S.

[0045] According to the pulse heating furnace burner combustion temperature control method of the present application, the features are:

[0046] The "when the temperature control zone appears the situation that the burners in the zones are opened at the same time, then according to the total number of input zones and the total number of burners opened at the same time between the zones, whether to allow each zone to be opened at the same time and the delay processing according to the real-time temperature difference of each zone for the temperature control zone opened at the same time are determined", specifically:

[0047] The total number of input zones is monitored, when the total number of input zones exceeds the set monitoring number threshold, it is determined that each zone is allowed to be opened at the same time, otherwise the delay processing according to the real-time temperature difference of each zone is as follows:

[0048] SS1: determining the difference between the total number of real-time input zones and the set monitoring number threshold, and determining the number of burners allowed in each zone according to the size of the difference;

[0049] SS2: calculating the temperature difference of each zone opened at the same time, and performing the delay sequential input processing of the corresponding zones in descending order according to the calculation results.

[0050] According to the pulse heating furnace burner combustion temperature control method of the present application, the features are:

[0051] The delay sequential input in step SS2 is specifically:

[0052] The sequential input is performed in descending order of temperature difference, the first one is opened in time, and the subsequent ones are sequentially delayed for 1S-2S.

[0053] According to the pulse heating furnace burner combustion temperature control method of the present application, the features are:

[0054] The coal gas pressure represented by the Wobbe value or the calculation of the dynamic set value of the coal gas pressure according to the real-time Wobbe value is specifically:

[0055] P1=P0×(Wu0 / Wu1) 2 ,

[0056] Wherein,

[0057] Wu0: Wobbe index set at standard calorific value 1800kcal / m 3 , 3 ,

[0058] P0: coal gas pressure set at standard calorific value 1800kcal / m 3 ,

[0059] P1: corrected coal gas pressure set, unit: kPa,

[0060] Wu1: actual measured Wobbe index, unit: kWh / m 3 .

[0061] According to the pulse heating furnace burner combustion temperature control method of the present application, the features are:

[0062] The calculation of the dynamic set value of the air main pressure according to the real-time Wobbe value is specifically:

[0063]

[0064] Wherein,

[0065] K: setting coefficient, related to the factors of gas flow, usually set as 1.0-1.2

[0066] P air : dynamic setting value of air main pressure, unit: kPa,

[0067] P air0 : constant, setting value of combustion air main pressure, unit: kPa,

[0068] Wu0: set value of Wu under the standard heat value 1800kcal / m 3 , unit: kWh / m 3 ,

[0069] Wu1: actual measured value of Wu, unit: kWh / m 3 ,

[0070] P gas1 : dynamic setting value of compensated gas main pressure, unit: kPa,

[0071] P gas0 : constant, design value of gas main pressure, unit: kPa.

[0072] The application discloses a combustion temperature control method of a pulse heating furnace burner.

[0073] The adjustment of the air flow setting value is carried out according to the following formula:

[0074] Air flow setting value = actual gas flow * setting air-fuel ratio * air excess coefficient.

[0075] The combustion temperature control method of the pulse heating furnace burner provides replacement basis for the certainty replacement of the burner and the valve according to whether the total pipe pressure parameter before the burner is stable and whether the combustion performance of the burner itself is stable, and cost is saved. The total pipe pressure parameter points to two indexes: one is gas pressure, and the other is air-fuel ratio; the gas pressure points to two aspects of a combustion timing scheme and dynamic correction of the gas pressure itself based on the Wu value; and the air-fuel ratio points to two aspects of monitoring of the air-fuel ratio of a section and monitoring of a pressure difference before a single burner. The air-fuel ratio is dynamically adjusted by adjusting the opening degree of the air valve, and the upper and lower limit adjustment of the regulating valve is set to avoid the influence of the air valve action range on the air-fuel ratio fluctuation. BRIEF DESCRIPTION OF DRAWINGS

[0076] Figure 1A schematic diagram of sequentially triggering the burner in the embodiment of the present application. DETAILED DESCRIPTION

[0077] Hereinafter, a combustion temperature control method of a pulse heating furnace burner of the present application is further specifically described according to the accompanying drawings and the specific embodiments.

[0078] A combustion temperature control method of a pulse heating furnace burner, which realizes the control of the uniformity and stability of pulse combustion from the monitoring and adjustment of two dimensions of whether the pressure parameter of the header before the establishment of the burner is stable and whether the combustion performance of the burner itself is stable.

[0079] In the present application,

[0080] The monitoring and adjustment of whether the pressure parameter of the header before the establishment of the burner is stable is completed by monitoring and adjusting two parameters of the monitoring and adjustment of the gas pressure and the monitoring and adjustment of the air-fuel ratio.

[0081] In the present application,

[0082] The monitoring and adjustment of whether the combustion performance of the burner itself is stable is realized by comparing the actual preheating air temperature value of the heated medium out of the preheating burner with the set value in real time, and when the absolute value of the difference between the two exceeds the set threshold value, the entire burner or the fin preheater is replaced, otherwise it is considered that the performance of the burner is stable.

[0083] In the present application,

[0084] The monitoring and adjustment of the gas pressure is completed by the two parallel operations of the established combustion timing beat and the dynamic correction of the gas pressure based on the lambda value.

[0085] In the present application,

[0086] The monitoring and adjustment of the air-fuel ratio is completed by the two parallel operations of the monitoring and adjustment of the air-fuel ratio of the section and the monitoring and adjustment of the pressure difference before the single burner.

[0087] In the present application,

[0088] The "by comparing the actual preheating air temperature value of the heated medium out of the preheating burner with the set value in real time, and when the absolute value of the difference between the two exceeds the set threshold value, the entire burner or the fin preheater is replaced, otherwise it is considered that the performance of the burner is stable" is specifically:

[0089] S1: real-time calculation of air heat absorption, calculation of flue gas outlet temperature based on heat balance equation according to the calculation results, comparison of the calculation results with the set value, if the difference between the two is less than the set threshold, it is determined that the burner combustion performance is stable, otherwise step S2 is entered;

[0090] S2: sequentially calculate the average temperature of air and flue gas, air-side heat release coefficient, flue gas-side heat release coefficient, heat transfer coefficient, logarithmic mean temperature difference, self-preheating burner heat transfer area, and required total length of burner fin preheater, and replace the corresponding size according to the calculated total length of burner fin preheater.

[0091] wherein,

[0092] The "monitoring and adjusting of the stability of the combustion performance of the burner itself" is based on the monitoring and adjusting of the pressure difference before the single burner.

[0093] wherein,

[0094] The "established combustion timing beat" specifically refers to:

[0095] I: control the opening time of each burner in each zone to stagger, and establish the combustion of each burner;

[0096] II: when there are burners opened simultaneously between zones in the temperature control zone, determine whether to allow each zone to be opened simultaneously and delay the processing of the temperature control zone according to the number of total input zones and the total number of burners opened simultaneously between zones.

[0097] wherein,

[0098] The "dynamic correction of the coal gas pressure based on the monitoring of the Wobbe value" specifically refers to:

[0099] The coal gas pressure represented by the Wobbe value is used as the control reference, and the corresponding coal gas pressure value is adjusted according to the real-time Wobbe value change.

[0100] wherein,

[0101] The "establishment of monitoring and adjusting of the air-fuel ratio of the section" specifically refers to:

[0102] SA1: calculate the dynamic set value of the pressure of the coal gas and the total air pipe pressure according to the real-time Wobbe value, and calculate the real-time air-fuel ratio according to the calculation results;

[0103] SA2: Establishes a regulation of the air flow set value around the reference air-fuel ratio based on the real-time calculated air-fuel ratio, which is completed by adjusting the opening degree of the air valve.

[0104] wherein,

[0105] The "monitoring and adjusting of the pressure difference before the single burner" is specifically:

[0106] Under the standard white value working condition, the burner gas hole plate differential pressure and the air hole plate differential pressure are measured and calculated in real time, and when the absolute value of the difference between the real-time measurement and calculation result and the factory calibration differential pressure is less than or equal to the set threshold value, it is considered that the hole plate and the ON-OFF valve opening degree are working normally, otherwise it is determined that the hole plate differential pressure is abnormal and the hole plate or ON-OFF valve blockage is processed and excluded.

[0107] wherein,

[0108] The opening degree of the regulating valve is within the regulating range consisting of the set upper limit and lower limit of the regulation,

[0109] The upper limit of the regulation is 40% of the valve opening degree + gas quantity percentage / 2.0;

[0110] The lower limit of the regulation is gas quantity percentage / 2.5.

[0111] wherein,

[0112] The "control mode of staggering the opening time of each burner in each zone" is specifically staggered to open at intervals of 1S-2S.

[0113] wherein,

[0114] The "when the temperature control zone appears the situation of simultaneous opening of burners between zones, then according to the total number of input zones and the total number of simultaneously opened burners between zones, respectively determine whether to allow each zone to open simultaneously, and according to the real-time temperature difference of each zone, the temperature control zone is processed with delay", specifically:

[0115] Monitor the total number of input zones, and when the total number of input zones exceeds the set monitoring number threshold, it is determined that each zone is allowed to open simultaneously; otherwise, according to the real-time temperature difference of each zone, the following delay processing is performed:

[0116] SS1: Determine the difference between the total number of real-time input zones and the set monitoring number threshold, and determine the number of simultaneously opened burners in each zone according to the size of the difference;

[0117] SS2: Calculate the temperature difference of each zone that is opened simultaneously, and perform the corresponding delay processing of each zone in the order from large to small according to the calculation result.

[0118] wherein,

[0119] The time delay in step SS2 is specifically as follows:

[0120] According to the order of temperature difference from large to small, the first one is opened in time, and the following ones are sequentially subjected to the time delay of 1S-2S.

[0121] wherein,

[0122] The coal gas pressure represented by the Wobbe value or the calculation of the dynamic set value of the coal gas pressure according to the real-time Wobbe value is specifically as follows:

[0123] P1 = P0 x (Wu0 / Wu1) 2 ,

[0124] wherein,

[0125] Wu0: Wobbe index set at the standard calorific value of 1800kcal / m 3 , 3 ,

[0126] P0: coal gas pressure set at the standard calorific value of 1800kcal / m 3 ,

[0127] P1: corrected coal gas pressure set, unit: kPa,

[0128] Wu1: actual measured Wobbe index, unit: kWh / m 3 .

[0129] wherein,

[0130] The calculation of the dynamic set value of the air main pressure according to the real-time Wobbe value is specifically as follows:

[0131]

[0132] wherein,

[0133] K: set coefficient, related to the factors of coal gas flow, usually set to 1.0-1.2

[0134] P air : dynamic set value of the air main pressure, unit: kPa,

[0135] P air0 : constant, set value of the combustion air main pressure, unit: kPa,

[0136] Wu0: Wobbe index set at the standard calorific value of 1800kcal / m 3Wu0: the calorific value index set at the standard calorific value of 1800kcal / m 3 ,

[0137] Wu1: the actual calorific value index, unit: kWh / m 3 ,

[0138] P gas1 : the dynamic set value of the total gas pipe pressure after compensation, unit: kPa,

[0139] P gas0 : a constant, the design value of the total gas pipe pressure, unit: kPa.

[0140] Wherein,

[0141] The adjustment of the air flow set value is made according to the following formula:

[0142] Air flow set value = actual gas flow × set air-fuel ratio × air excess coefficient.

[0143] Working process, principle

[0144] Regarding the gas pressure and air-fuel ratio part of dynamic correction of the gas calorific value

[0145] Wu, the calorific value index = low calorific value / square root of relative density

[0146] Wu = Hu / (d r ) 1 / 2 , wherein d r is the relative density of the gas, and the relative density is the ratio of the density of the gas to the density of air under the standard state (0℃, 101.325kPa).

[0147] Gas pressure control P1 = P0 * (Wu0 / Wu1)2

[0148] Wu0 is the calorific value index set at the standard calorific value of 1800kcal / m 3 , unit: kWh / m 3

[0149] P0 is the gas pressure set at the standard calorific value of 1800kcal / m 3 , unit: kPa

[0150] P1 is the corrected set gas pressure, unit: kPa

[0151] Wu1 is the actual calorific value index, unit: kWh / m 3

[0152] Wob calorific value decreases, and the gas pressure value increases, Wob calorific value increases, and the gas pressure value decreases, so as to ensure the constant value of the air-coal ratio to meet the requirement of temperature control.

[0153] Combustion air pressure set value is calculated according to coal gas pressure set value, and combustion air temperature measured value participates in pressure set value correction. Air pressure changes according to coal gas pressure change, and air pressure set value considers coal gas pressure, coal gas quantity and correction factor influence:

[0154]

[0155] Wherein K is coal gas flow correlation factor, and set coefficient is 1.0-1.2 respectively. Specific adjustment corresponding table is as follows.

[0156] Serial number Percentage of gas quantity (thousands of m 3 )]]> Coefficient K 1 1％～25％ 1.0 2 26％～45％ 1.1 3 46％～70％ 1.15 4 71％～110％ 1.2

[0157] According to air and coal gas total pipe pressure, calculate and calibrate burner coal gas orifice plate differential pressure KPa and air orifice plate differential pressure KPa.

[0158] Burner air and coal gas orifice plate calculated differential pressure ΔP (KPa) = (burner rated flow / temperature and pressure correction coefficient / (orifice flow formula coefficient*pipe diameter^2*dilatation coefficient*flow coefficient)^2*operation density.

[0159] Calibrate through actual measurement and calculation pressure differential comparison. Wherein temperature and pressure correction coefficient is calculated according to temperature and pressure correction formula: ((P+101.6) / (P b +101.6)×(T b +273.15) / (T+273.15)) 0.5 ,

[0160] P: pressure measured value KPa; Pb: reference pressure KPa;

[0161] T: temperature measured value ℃; Tb: reference temperature ℃

[0162] Dilatation coefficient ε = 0.998; orifice flow formula coefficient is according to orifice calculation book flow formula coefficient; air flow coefficient = 0.764; coal gas flow coefficient = 0.730; air operation density ρ = 0.4676 kg / m3; coal gas density operation ρ = 1.0651 kg / m3;

[0163] In pulse control, air and coal gas flow do not participate in temperature control, and air and coal gas regulating valves in upper and lower zones are only used for controlling air-fuel ratio. In normal production process, zone coal gas regulating valve is manually fully opened, air flow set value = actual coal gas flow × set air-fuel ratio × air excess coefficient, and air valve is automatically adjusted according to air flow set value, so that actual air-fuel ratio is stably kept near set value.

[0164] The output signal of the temperature regulator of each zone in the furnace determines the opening time of the pulse burner, determines the gas flow, and determines the air flow set value. The proportional, integral, and differential control is continuously carried out through the deviation between the measured value and the set value of the air flow, and the PID proportional coefficient is small to avoid the large oscillation of the air valve and the large fluctuation of the air-fuel ratio. The upper and lower limit control is set for the air regulating valve.

[0165] According to the measured total zone gas flow, the air flow adjustment set value is obtained by multiplying the air-fuel ratio coefficient, and the air flow is always kept at the set air-fuel ratio by adjusting the opening of the zone air total pipe regulating valve.

[0166] The upper and lower limit control of the air regulating valve: the upper limit is 40% + gas quantity percentage / 2.0, and the lower limit is gas quantity percentage / 2.5.

[0167] Regarding the part of whether the combustion performance of the burner itself is stable

[0168] A. Calculate the outlet flue gas temperature of the self-preheating burner;

[0169] B. Then compare the temperature efficiency of the self-preheating burner with the actually measured inlet and outlet flue gas temperature and inlet and outlet air temperature, and calculate the heat exchange efficiency for comparison;

[0170] C. If the comparison result is inconsistent, check the equipment state of the self-preheating burner and the conditions of dust accumulation or leakage, and handle them; recalibrate the air and gas pressures of the burner.

[0171] D. Repeat steps A and B until the comparison result is consistent.

[0172] The monitoring of whether the self-preheating burner has stable combustion performance is conducive to checking whether the heat exchange efficiency of the self-preheating burner is reasonable; by finding the factors affecting the efficiency of the self-preheating burner, the efficiency can be optimized accordingly. Through the calculation of the self-preheating burner design, it is verified whether the self-preheating burner meets the requirements.

[0173] The specific calculation process of the metal tubular self-preheating burner is as follows:

[0174] 1. Calculate the heat absorbed by air Q = G2Cp2(t2-t1); 2. Calculate the flue gas outlet temperature T2 using the heat balance equation Q = G1Cp1(T1-T2) = G2Cp2(t2-t1); 3. Calculate the average temperature of air and flue gas; 4. Calculate the air side heat release coefficient 5. Calculate the flue gas side heat release coefficient 6. Calculate the heat transfer coefficient 7. Calculate the logarithmic mean temperature difference Δt p= (Δt1-Δt2) / ln(Δt1 / Δt2), where Δt1 = T1-t1, Δt2 = t2-T2;8. Calculate the heat transfer area of the preheating burner F = Q / (K·Δt p );9. Calculate the total length of the burner required L = F / (π·d) where λ - thermal conductivity of the fluid, W / m·℃; d - inner diameter of the tube, mm; p - fluid density kg / m 3 ; u - fluid flow rate, m / s; μ fluid viscosity, N·s / m 2 ; Cp - specific heat of the fluid, J / kg·℃; n is the coefficient of different finned preheaters (0.85-1.0).

[0175] where Q is the heat exchanged per unit time from the preheating burner, kcal / h;

[0176] G1 - hot fluid weight flow rate, kg / h;

[0177] G2 - cold fluid weight flow rate, kg / h;

[0178] Cp1 - constant pressure specific heat of the hot fluid, kcal / (kg·℃);

[0179] Cp2 - constant pressure specific heat of the cold fluid, kcal / (kg·℃);

[0180] T1, T2 - temperature of the heating medium (flue gas) entering and leaving the preheating burner;

[0181] t1, t2 - temperature of the heated medium (air) entering and leaving the preheating burner;

[0182] The heat balance equation is a relationship between the heat absorbed by the cold fluid and the heat released by the hot fluid in the preheating burner;

[0183] The heat transfer area of the preheating burner is determined by the heat load of the preheating burner, the heat transfer coefficient, and the average logarithmic temperature difference of the cold and hot media of the preheating burner. After the heat transfer area is determined, the structural size of the preheating burner can be preliminarily determined. The heat transfer area calculation formula of the preheating burner is as follows: F = Q / (K·Δt p );

[0184] where F is the heat transfer area of the preheating burner, m 2 ;

[0185] Q is the heat exchanged per unit time from the preheating burner, kcal / h;

[0186] K is the heat transfer coefficient of the preheating burner, kcal / (m 2 ·h·℃); Δt p is the average logarithmic temperature difference between the cold and hot fluids, ℃;

[0187] Since the efficiency of the self-preheating burner is affected by the heat exchange area, the efficiency of the self-preheating burner can be checked by checking the preheated air temperature of the self-preheating burner, and the heat exchange area of the self-preheating burner is calculated by inputting the flue gas inlet, flow, and air inlet, outlet temperature and flow, etc. By comparing with the actual heat exchange efficiency, the self-preheating burner is adjusted by comparing the heat exchange efficiency. The calibration is carried out by comparing the actual measurement and the calculation pressure difference.

[0188] Regarding the combustion timing part

[0189] As shown in Figure 1 , the burner combustion timing of each temperature control zone is optimized to avoid simultaneous opening and closing of the burners to reduce gas pressure fluctuations.

[0190] Each temperature control zone has 4 burners and 2 thermocouples, and the trigger sequence is staggered in the left and right zones and staggered in the upper and lower zones.

[0191] If the temperature control Z01 zone is triggered clockwise, and the temperature control Z02 zone and the temperature control Z03 zone are triggered counterclockwise, that is, the adjacent temperature control zones are staggered clockwise and counterclockwise.

[0192] The main control idea of the pulse control scheme is that the opening time of each burner in a zone is staggered, and the time interval is 1 second. The number of burners that can be opened and closed simultaneously between zones is 2. If all temperature control zones are opened simultaneously, the zones that are opened simultaneously are delayed by 2 seconds according to the temperature difference e = PV-SP at that time.

[0193] It is to avoid all burners in each zone being opened simultaneously to reduce the fluctuation of the total gas pipe pressure.

[0194] The holding furnace has 8 temperature control zones, and each control zone has 4 burners.

[0195] The simultaneous closing strategy of the burners evenly distributes the heat load in each temperature control zone to each burner in the zone, which can avoid the overlap of the closing time of the burners in the same temperature control zone. As mentioned above, the opening time of each burner is staggered, and the time interval is 1 second. Since the heat load is evenly distributed to each burner in the zone, the closing time of each burner should also be staggered by 1 second. For example, the time interval between the trigger time Tstart1 of the first burner and the trigger time Tstart2 of the second burner in the temperature control 1 zone is 1 second, and the closing time Tstop1 of the first burner and the closing time Tstop2 of the second burner are as follows:

[0196] Tstop1 = Tstart1 + T*CV% (T: pulse control period; CV%: heat load)

[0197] Tstop2 = Tstart2 + T*CV%

[0198] T: pulse control period; CV%: heat load

[0199] When the heat load is evenly distributed to two burners, the burner closing time is also staggered.

[0200] This allows the number of simultaneously opened and closed burners to be 2, avoiding the fluctuation of gas caused by the large number of simultaneously closed burners.

[0201] The present application is a kind of pulse heating furnace burner combustion temperature control method, from two aspects of whether the total pipe pressure parameter before the burner is stable and whether the combustion performance of the burner itself is stable, establish the control of the uniformity and stability of pulse combustion, and also provide replacement basis for the certainty of burner and valve replacement, save the cost.The total pipe pressure parameter points to two indexes: one is gas pressure, and one is air-fuel ratio;The gas pressure points to two aspects of the combustion timing scheme and the dynamic correction of the gas pressure itself based on the lambda value;The air-fuel ratio points to two aspects of monitoring the air-fuel ratio of the section (adjusting the air gas pressure to ensure dynamic adjustment of air-fuel ratio according to the lambda value) and monitoring the pressure difference before the single burner.The above-mentioned adjustment of air gas pressure to ensure dynamic adjustment of air-fuel ratio according to the lambda value is finally adjusted by adjusting the opening degree of the air valve, and in order to avoid the influence of air valve action amplitude on air-fuel ratio fluctuation, the upper and lower limit adjustment of the regulating valve is set.

[0202] In summary, the present application is a kind of pulse heating furnace burner combustion temperature control method, which overcomes the instability of steel plate temperature control in the process of steel plate pulse heating, maximizes the stability of furnace temperature control, reduces the fluctuation of furnace temperature, and effectively improves the heating quality.

[0203] It is beneficial to check whether the design of the burner is reasonable, and through the check and optimization of the self-preheating burner, the required heat exchange effect of the process is realized, the stability of the heating furnace thermal efficiency is ensured, the fuel consumption is reduced, and the temperature control flexibility is ensured.

Claims

1. A method for controlling the combustion temperature of a pulse heating furnace burner, characterized in that: the combustion temperature control method realizes the control of the uniformity and stability of pulse combustion from the monitoring and adjustment of two dimensions, namely whether the pressure parameter of the total pipe before the establishment of the burner is stable and whether the combustion performance of the burner itself is stable, the monitoring and adjustment of whether the pressure parameter of the total pipe before the establishment of the burner is stable is completed through the monitoring and adjustment of two parameters, namely the monitoring and adjustment of the gas pressure and the monitoring and adjustment of the air-fuel ratio, the monitoring and adjustment of the gas pressure is completed through two parallel operations of the established combustion timing rhythm and the dynamic correction of the gas pressure formed based on the monitoring of the Wobbe value, the monitoring and adjustment of whether the combustion performance of the burner itself is stable is realized by comparing the actual preheating air temperature value of the heated medium out of the preheating burner with the set value through real-time monitoring, when the absolute value of the difference between the two exceeds the set threshold, the entire burner or the finned preheater is replaced, otherwise it is considered that the performance of the burner is stable, the monitoring and adjustment of the air-fuel ratio is completed through two parallel operations of the monitoring and adjustment of the air-fuel ratio of the section and the monitoring and adjustment of the pressure difference before the single burner, the "established combustion timing rhythm" is specifically: I: the combustion of each burner is established in a control mode in which the opening time of each burner in each zone is staggered within the limit that the number of burners allowed to be opened and closed simultaneously in each zone is at most 2; II: when there are burners opened simultaneously between zones in the temperature control zone, whether each zone is allowed to be opened simultaneously and the delay processing of the temperature control zone according to the real-time temperature difference of each zone are determined according to the number of total input zones and the total number of burners opened simultaneously between zones, the "dynamic correction of the gas pressure formed based on the monitoring of the Wobbe value" is specifically: the gas pressure represented by the Wobbe value is taken as the control reference, and the corresponding gas pressure value is adjusted according to the real-time change of the Wobbe value, the "monitoring and adjustment of the air-fuel ratio of the section" is specifically: SA1: the dynamic set values of the pressure of the gas and the total air pipe are calculated according to the real-time Wobbe value, and the real-time air-fuel ratio is calculated according to the calculation result; SA2: the set value of the air flow around the reference is adjusted according to the set air-fuel ratio, and the adjustment is completed by adjusting the opening degree of the air valve, the "monitoring and adjustment of the pressure difference before the single burner" is specifically: under the working condition of the standard Wobbe value, the real-time measurement and calculation of the differential pressure of the burner gas orifice plate and the differential pressure of the air orifice plate are performed, when the absolute value of the difference between the real-time measurement and calculation result and the factory calibration differential pressure is less than or equal to the set threshold, it is considered that the orifice plate and the ON-OFF valve opening degree are working normally, otherwise it is considered that the differential pressure of the orifice plate is abnormal and the differential pressure of the orifice plate or the ON-OFF valve blockage is processed and eliminated.

2. The method for controlling the combustion temperature of a pulse heating furnace burner according to claim 1, characterized in that: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The "comparison of the actual preheating air temperature value of the heating medium out of the preheating burner with the set value is achieved by real-time monitoring, and when the absolute value of the difference between the two exceeds the set threshold value, the entire burner or fin preheater is replaced, otherwise it is considered that the burner performance is stable", specifically: S1: Real-time calculation of air heat absorption, calculation of flue gas outlet temperature based on heat balance equation according to the calculation result, and comparison of the calculation result, i.e. the actual preheating air temperature value of the heating medium out of the preheating burner, with the set value, real-time monitoring of the comparison of the actual preheating air temperature value with the set value, if the difference between the two is less than the set threshold value, it is determined that the burner combustion performance is stable, otherwise step S2 is entered; S2: Calculate air average temperature, flue gas average temperature, air side heat release coefficient, flue gas side heat release coefficient, heat transfer coefficient, logarithmic mean temperature difference, preheating burner heat transfer area, and required total length of burner fin preheater, and replace the corresponding size according to the calculated total length of the burner fin preheater.

3. The combustion temperature control method of the pulse heating furnace burner according to claim 1, characterized in that: The "monitoring and adjustment of whether the combustion performance of the burner itself is stable" is based on the monitoring and adjustment of the pressure difference before the single burner.

4. The combustion temperature control method of the pulse heating furnace burner according to claim 1, characterized in that: The opening degree of the air valve is within the adjustment range consisting of the set upper limit and lower limit of adjustment, The upper limit of adjustment is: 40% of the valve opening degree + gas quantity percentage / 2.0; The lower limit of adjustment is: gas quantity percentage / 2.

5.

5. The combustion temperature control method of the pulse heating furnace burner according to claim 1, characterized in that: The "control method of staggering the opening time of each burner in each zone" specifically staggers the opening by 1S-2S.

6. The combustion temperature control method of the pulse heating furnace burner according to claim 1, characterized in that: The "when the temperature control zone appears the situation that burners in different zones are opened at the same time, then according to the total number of zones and the total number of burners opened at the same time in different zones, respectively determine whether to allow each zone to be opened at the same time, and delay processing according to the real-time temperature difference of each zone for the temperature control zone opened at the same time", specifically: Monitor the total number of zones, if the total number of zones exceeds the set monitoring number threshold, it is determined that each zone is allowed to be opened at the same time; otherwise, delay processing according to the real-time temperature difference of each zone: SS1: Determine the difference between the total number of real-time zones and the set monitoring number threshold, and determine the number of burners allowed to be opened at the same time in each zone according to the size of the difference; SS2: Calculate the temperature difference of each zone opened at the same time, and perform the corresponding delay sequential input processing of each zone in the order from large to small according to the calculation result.

7. The combustion temperature control method of the pulse heating furnace burner according to claim 6, characterized in that: The delay sequential input in step SS2 is specifically: ​ According to the order of temperature difference from large to small, the first one is opened in time, and the rest are sequentially processed with 1S-2S delay.

8. The combustion temperature control method of a pulse heating furnace burner according to claim 1, characterized in that: The gas pressure is represented by the Wobbe value, or the dynamic set value of the gas pressure is calculated according to the real-time Wobbe value, specifically: P1= P0x (Wu0 / Wu1) 2 , Wherein, Wu0: Set the white index under the standard heat value 1800kcal / m 3 , unit: kWh / m 3 , P0: set at the standard heating value 1800kcal / m 3 under the coal gas pressure, unit: kPa, P1: the set gas pressure after correction, unit: kPa, Wul: actual measured white-to- brown index, unit: kWh / m 3 .

9. The combustion temperature control method of a pulse heating furnace burner according to claim 1, characterized in that: According to the real-time white value, the calculation of the air main pressure dynamic setting value is performed, specifically as follows: , Wherein, K: set coefficient, related to gas flow, usually set to 1.0-1.2, P air : total air pipe pressure dynamic setting value, unit: kPa, P air0 : constant, total combustion air manifold pressure set value, units: kPa, Wu0: Set the calorific value of 1800kcal / m 3 under the standard, unit: kWh / m 3 , Wul: actual measured white-to-black index, in kWh / m 3 , P gas1 : compensated pressure dynamic set value of the gas main, unit: kPa, P gas0 : Constant, design value of total gas main pressure, unit: kPa.

10. The combustion temperature control method of a pulse heating furnace burner according to claim 1, characterized in that: The adjustment of the air flow set value is carried out according to the following formula: Air flow set value = actual gas flow × set air-fuel ratio × air excess coefficient.

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