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Design and development of high-speed burner

Writer: admin Time:2021-07-27 00:00 Browse:

Gas burners are relatively high in industrial production in industrial production. It is thus so that the gas burner is sought after, then the design and development of high-speed burner
	Design and development of high-speed burner

Design and development of high-speed burner
Abstract: Introduction to the technical characteristics, design points and specific design methods of high-speed gas burners, and uses liquid rocket engines combustion technology to develop a new high-speed gas burner for industrial heating furnaces. Filling a blank of civil burner technology in my country, has been successfully applied in oil fields, steel, ceramics and other industries. Key words: liquid rocket engine, burner, combustion test. 1 Preface High Speed ​​Gas Burner is a modern combustion technology in an industrial combustion equipment industry, and its ejection speed of high temperature combustion products can reach 100 m / s ~ 300 m / s, which has energy saving, efficient, flame movable control. Advantages, in developed countries have been widely used in various heating furnaces in aviation, steel, chemical, light industry and other industries. my country introduces this technology in the 1980s and some imitation products into the market, but due to its high cost, refractory, the lining is very bad, the service life is short, which affects promotion. High-speed burner (burner) is a device that converts the chemical energy and kinetic energy of the fuel into a combustion product, and a liquid rocket engine is a device that converts the chemical energy and kinetic energy of the propellant into a combustion product, two There are similar situations in the principle of working. Using the extensive experience in liquid rocket engine development, a full metal structure is developed, and a high-performance high-speed gas burner using regenerated cooling. 1.1 Technical Features of High Speed ​​Gas Burner A) Accurate Tissue Combustion, Combustion Efficiency 99.9%; b) Wide Direction Status: Thermal load adjustment ratio 1:20, air coefficient 0.5 ~ 10; c) Using grade combustion, harmful gases (NOX Emissions meet the national environmental standards; D) has flue gas to introduction reflow function, can lead the waste flue gas to re-input the furnace; e) all metal structure, continuous service life for 3 years. 1.2 High-speed burner improves the mechanism of heat exchange efficiency In conventional industrial furnace design, the flame speed of the burner is approximately a few meters per second, and when the temperature of the combustion product is 600 ° C to 800 ° C, the fire is converted to the heat and radiation in the furnace. When the heat exchange is 50%; when the temperature of the combustion product is 800 ° C, the radiation heat exchange is mainly; when the temperature of the combustion product reaches 1 400 ° C, the radiation heat exchange is 10 times the heat exchange heat, so most of the furnace kiln In design, it is based on radiation heat exchange. However, after using a high-speed gas burner, even in the high temperature zone, the reunion of the furnace is reinforced to change the proportion in combined heat transfer in combined heat exchange, and details are specifically described below. When using ordinary burners, the flame speed is low, the flow of the combustion product is laminar flow in the surface of the heated object, the laminar flow exchange heat transfer coefficient is H1-Nu * λ / D systain Nu te Nu = 0.332Pr1 / 3 * RE1 / 2; PR is the number of Pronke; RE is the number of Reno; λ is the thermal conductivity of the gas; D is the flow path equivalent diameter. High-speed gas burner, flame injection speed (100 m / s ~ 300 m / s), the surface of the heated body is mainly turbulent, and the topical exotherm coefficient of turbulence is H2 = Nu * λ / D Nu = Pr1 / 3 (0.036 RE0.8-836) The lumen of the heating furnace was 6.45 m × 2.3 m × 2.9 m, and the temperature of the combustion product was 1 790 ° C, and the heated body temperature was 900 ° C. When a common burner is used, when the combustion product flow rate is 5 m / s, the convection heat transfer between the combustion product and the heated surface is Q1 = H1 (Tg-Tg-TW) = 2671x4.18kj / h * m2 adopts high-speed gas. When the burner, the combustion product flow rate is 150 m / s, the convection heat transfer between the combustion product and the surface of the heated body is Q2 = H2 (TG-TG-TW) = 10685x4.18kj / h * m2 Q2 is Q1 4 Multiplier. In foreign countries, there was a comparative trial on the radiation heating furnace and the high-speed convection heating furnace. During the heating of 0 ° C ~ 1 200 ° C, the heating time required for the radiant heating furnace is 6 times that of the high-speed convection heating furnace, at 750 ° C ~ 1 200. During the heating of ° C, the heating time required for the radiant heating furnace is 10 times the high speed convection heating furnace. In 1980, domestic introduction of high-speed gas burners were technically transformed on well-type heating furnace. The original radiant heating furnace required 24 h from 0 ° C ~ 650 ° C, and the heating furnace using a high-speed gas burner from 0 ° C ~ 650 ° C temperature rise is only 4 h, and the fuel consumption can also save 25% to 30% due to the high-speed gas burner. In the oil field, it is transformed into a three-in-one heating furnace with a high-speed gas burner, and the heating efficiency is 1 fold, while the fuel consumption is 20%. The combustion product of the high-speed gas burner is rushing into the heating furnace at a high speed, and the gas in the furnace is stirred with a mixture, which can greatly increase the uniformity of temperature in the furnace. After the foreign plant has modified the heating furnace with a high-speed gas burner, the temperature uniformity in the furnace can be increased from ± 15 ° C to ± 2 ° C. After the domestic well-type heating furnace is used with a high-speed gas burner, the homogeneity of the furnace reaches ± 7 ° C. 2 High-speed gas burner design points 2.1 Precisely organized newly developed high-speed gas burners, in order to achieve complete combustion, the gas and air enter the combustion chamber through numerous spray holes, and the gas jet is impacted and uniformly mixed. The synthetic range of radials should be parallel to the spindle of the combustion chamber, avoiding an incident flow to the other jet, causing mixed unevenness. In order to reduce the generation of NOx, take the partition combustion, the front zone combustion temperature is lower than the back region combustion temperature, and the combustion temperature is the highest in the combustion chamber outlet. The front area is a hydraulic combustion, and the rear area increases oxygen, and the exit of the combustion chamber reaches the excess air coefficient α = 1. In this design, it can be reasonably equipped, ensuring complete combustion, preventing CO production, and maintains a lower combustion temperature, reducing the harmful gas NOx generation. 2.2 Combustion chamber wall cooling combustion chamber filled with high temperature combustion products, the metal chamber wall must have sufficient cooling to work safely. The regeneration cooling of the liquid rocket engine is imitated, in the design of the high-speed gas burner, using air flows in the combustion chamber, absorbs the heat of the chamber wall, ensuring that the chamber wall operates within the safe temperature range. At the same time, air preheating can promote complete combustion and improve the theoretical combustion temperature. At the partial high temperature zone of the combustion chamber spray, air film protective metal wall is designed. Since the above design is taken, the high-speed gas burner can reach 3 years, while the combustion chamber of the high-speed gas burner of other units is designed by refractory, life is a few months, and even products It is cracking in the fire-resistant lining in less than 3 months. 2.3 Flow Grinding In the design of high-speed gas burner, in order to make the combustion product have sufficient momentum, the combustion chamber should have a certain pressure. According to the gas physical chemical parameters and speed requirements provided by the user, the pressure of the combustion product is determined after determining the various thermal parameters of the combustion product, that is, PC = PA / [1- (k-1) W2 / 2KRT ] The PC is a combustion chamber pressure in the K / (k-1) formula; the PA is ambient pressure; K is the thermal insulation index of the combustion product; R is the combustion product gas constant; T is the combustion temperature; W is the flow rate of the combustion product at the spout. Air and gas enters the burner, flow through the respective channels, pass through the spray hole into the combustion chamber, and there is a certain flow resistance along the way. Figure 1 shows the relationship between the combustor air flow Qk and the air pressure drop ΔPk; Figure 2 shows the relationship between the combustor gas flow qr and the gas pressure drop ΔPr. Figure 1 Relationship between burner air flow path flow and voltage drop (20 ° C) Figure 2 The relationship between the burner natural gas flow path flow and the pressure drop (20 ° C) The air inlet pressure Pk of the burner is a combustion chamber pressure PC and an air pressure drop. The sum of ΔPk, the gas inlet pressure Pr, the combustion, the combustion chamber pressure Pc and the gas pressure drop ΔPr. That is: PK = PC + ΔPK PR = PC + ΔPr PK and PR cannot be too high, and the user provided by the user should be met. When a high-speed gas burner is used as a gas using natural gas, the combustion product is 100 m / s, and the natural gas inlet pressure is 2 500 PA, and the air inlet pressure is 2 100 Pa. 3 Design Calculation 3.1 Combustion Calculation When calculating the air requirements of the gas combustion by combustion, the gas-burning air requirement L0, the combustion product amount Vα, the combustion product density ρ, the gas constant R, the heat insulating index k, and the theoretical combustion temperature T. a) Determine the volume of the lower thermal value qyd and composition ingredients according to the selected gas. b) Determine the theoretical air volume of 1M3 gas required to be L0 = 4.672 / 100 * [1/2 * CO + 1/2 * H2 + (N + m / 4) CNHM + 3/2 * H2S-O2] Co, H2, and CNHM are the percentage of gas components. c) Determine the combustion product amount of combustion 1M3 gas generated to VY = αL0 + 0.38 + 0.075 QYD / 1000 E) Determine the theoretical combustion temperature T is T = (qyd + CRTR + CKTKLα) / (α & gt; 1) t = (QY + CRTR + CKTKLα) / (α & lt; 1) CR, CK, CY is gas, air, and combustion products, respectively; Tr, Tk is the starting temperature of gas and air, respectively; QY is the effective heat of the gas. QY = qyd-qvy q is the heat contained in the combustion product. Q = 3022XCO + 2581XH2 XCO, XH2 is a percentage content of burning CO, H2). f) Determine the density of the combustion product is α = 1 ρY = (44xCO2 + 18xH2O + 28XN2) /22.4 α & lt; 1 ρY = (44xCO2 + 28xCO + 18XH22O + 2XH20 + 28XN2) / 22.4 x 中 中 2 2 2 2 2 2, 中The amount of volume content of XN2 is CO2, CO, H2O, H2, and N2 in the combustion product, respectively. g) Determine the amount of MEQ of the combustion product gas constant R to R = 8.314 / MEQ formula into the combustion product. The amount of volume in the formula is the first component in the combustion product; the molecular weight of the Mi is the first component. h) Determine the specific heat of the CPI in the thermal insulation index formula of the combustion product into the combustion product. 3.2 Combustion chamber structure design calculation a) The heat load Q0 of the selected burner. b) Determine the gas consumption VR (volume), Gr (mass) is ρr is a gas density. c) Determine the air consumption VK (volume), GK (mass) is VK = L0VR GK = vkρk type ρk is the air density. d) Determining the amount of combustion product generating Gy Gy = Gr + GK E) The speed of the combustion product is selected in the spout based on the conditions of use. f) Determine the cross-sectional area of ​​the combustion chamber, diameter DE is Fe = GyWE / ρY (1 + T / 273) g) determines the combustion chamber cylindrical section cross-sectional area F1, diameter D1 is h) determines the combustion chamber cylindrical section length L1 For L1 = (1 ~ 1.4) D1 3.3 Combustion chamber spray hole design calculation A) The gas injection speed WRJ is selected. The selected principle is that after the gas jet is hit by the corresponding air jet, the synthetic jet direction is parallel to the combustion chamber axis. b) Determining the total area FRJ of the gas spray hole to FRJ = Vr / WRJ C) Determine the percentage distribution of gas injective flow along the length of gas nozzle. 3. The gas flow is distributed in the percentage of combustion chamber flameout zone to determine the percentage distribution of gas injection flow along the length of gas nozzle. 3 Distribution D of the combustion indoor air gas flow rate D) Determine the distribution of the length of the gas nozzle along the gas nozzle. The N-group gas spray holes are copied in the longitudinal direction of the gas nozzle, with a spacing of about 20 mm; along the circumferential direction of the gas nozzle, each group has a common M spray hole, m = 12 to 24. e) Determine the diameter of the gas spray holes in each group. Depending on the percentage of gas flow along the length of the tube length, it is possible to know the area percentage distribution of the spray hole, know the total area of ​​each set of discharge holes, and the same set of female diameters can be obtained. 3.3.2 Calculation of air inlet design A) The air injection speed WKJ is selected. 3.3.1, in the rated design state, WKJ ≈ 15m / s is recommended. b) Determining the total area of ​​air spray hole is fkj = vk / wkj C) Determine the distribution of air injection flow in the combustion chamber wall. 3 Determine the air flow, in the rated design state, it is recommended to have an air excess in the ignition zone α≈0.6; at the end α≈0.8 of the mixed zone; at the end of the tail chamber, the end alpha α≈1.4 is a combustion indoor gas flow chart. 4 Combustion Indoor Gas Flowchart D) The air spray selection of the flammable area. 8 Determine the air spray packet according to the fuel nozzle packet, and the number of air spray holes per group is m. e) Determination of air spray holes in tail zone. The air flow rate of the tail retardation area accounts for about 20% to 30% of the total air flow, and the air spray hole should be small in diameter, large, and a uniform air cooling film is formed in the inner wall of the tail combustion zone. 4 Combustion Test High-speed gas burner passes through natural gas combustion test, which proves reliably and easy to operate. 4.1 The ignition method combustion test uses two electric ignition mode, one is the high energy igniter DHZ-103, the ignition frequency is 1.5 times / s, the storage can be 12J / time; the other is the flame monitoring ignitioner HJ-1, ignition voltage 15 000 V, the ignition mouth is the car spark plug. 4.2 ignition procedures a) 1/4 of the total air volume required by the rated load; B) Electric igniter power-on; c) Open the natural gas switch, and you can successfully ignite when α≈0.6. 4.3 Heat load adjustment of a burner having a rated heat loss of 30 m3 / h, in the test, natural gas is reduced to 1.6 m3 / h, still maintains combustion (α≈14). 4.4 In the air coefficient adjustment test, the air coefficient adjustment of the heat storage combustor ranges from 0.5 to 20, and the combustion can be maintained. 4.5 Gas Temperature Adjustment 9 Test, the measured temperature variation of the burner outlet is 90 ° C to 1 300 ° C (α ≥ 2). 10 Conclusion The high-speed gas burner is an efficient, energy-saving, low-polluting burner developed by the combustion technique of liquid rocket engines for industrial heating furnaces. After natural gas combustion test, it demonstrates its work reliably, simple operation, high heat load adjustment, and the air excess coefficient and gas temperature adjustment range are large. The burner is currently successfully applied to the heating furnace in oil fields, ceramics, steel and other industries.