Kellogg’s thousand-ton synthetic ammonia process – what about adding air to the second stage furnace?
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Why does the book often state that undignition can occur when air is added to a two-stage furnace, and that the introduction of oxygen can lead to an explosion in the system? Question: In a two-stage furnace where air and hydrogen burn, what is the ignition temperature? Why doesn’t combustion occur? Such high temperatures? I don’t understand! ! !
1. In the second-stage furnace, air and hydrogen burn together; 650 degrees is the ignition point. 2. How is it non-flammable? Well, it depends on the composition of the material at the furnace outlet; if the water vapor content is high, the ignition point will be higher ； The same is true in reverse. The term \"burning of air and hydrogen\" is a conventional way of putting it; in reality, it is the oxygen in the air that reacts with hydrogen, which is different from combustion in the traditional sense.
I know that. May I ask how to find out the ignition points of hydrogen in process gas and oxygen in air? How to calculate it, (how to account for the impact of water vapor)! Thank you! ! !
The original poster might want to take a look at the physical and chemical properties of hydrogen below:
**Physical and Chemical Properties**
Molecular weight: 2.016
Melting point (101.325 kPa): -259.2°C
Boiling point (101.325 kPa): -252.8°C
Liquid density (-252.766°C, 101.325 kPa): 70.973 kg/m³
Gas density (0°C, 101.325 kPa): 0.0899 kg/m³
Relative density (25°C, 101.325 kPa, air = 1): 0.0695
Specific volume (21.1°C, 101.325 kPa): 11.9674 m³/kg
Compressibility coefficient:
Temperature (°C) | Compressibility coefficient at 101.325 kPa | Compressibility coefficient at 1013.25 kPa | Compressibility coefficient at 10132.5 kPa | Compressibility coefficient at 50662.5 kPa
25 | 1.001 | 1.000 | 1.006 | 1.006
100 | 1.0579 | 1.3244 | 1.3014 |
Critical temperature: -239.9°C
Critical pressure: 1297 kPa
Critical density: 31.0 kg/m³
Enthalpy of fusion (13.8 K): 58.16 kJ/kg
Enthalpy of vaporization (18 K): 457.80 kJ/kg
Heat capacities (101.33 kPa, 273.15 K): Cp = 14190 J/(kg·K), Cv = 10080 J/(kg·K)
Heat capacity ratio (26.8°C, 101.325 kPa): Cp/Cv = 1.405
Vapor pressure (16 K): 21 kPa; (24 K): 260 kPa; (32 K): 1100 kPa
Viscosity (101.325 kPa, 25°C): 0.00886 mPa·S
Surface tension (liquid-gas interface, -258°C): 2.80 mN/m
Thermal conductivity (100 kPa, 270 K): 0.16705 W/(m·K)
Refractive index (20.33 K, 100 kPa, liquid, 4047A): n = 1.11262; (20°C, 101.325 kPa, gas): n = 1.0001297
Flammability range in air (20°C, 101.325 kPa): 4.0–74.5%
Minimum ignition temperature in air (101.325 kPa): 570°C
Flame temperature during equivalent combustion in air: 1430°C
Maximum flame velocity during equivalent combustion in air: 2.65 m/s
Flammability range in oxygen (20°C, 101.325 kPa): 4%–94%
Minimum auto-ignition temperature in oxygen (101.325 kPa): 560°C
Flame temperature during equivalent combustion in oxygen: 2830°C
Maximum flame velocity during equivalent combustion in oxygen: 14.36 m/s
Heat of combustion during equivalent combustion in oxygen: 12761 J/m³ (high); 11506 J/m³ (low)
..................
Additionally, to determine whether air supply to the second stage is successful, first check that the pressure at the compressor outlet is at least 2 kilograms higher than the pressure in the second-stage furnace. After supplying air, observe whether there is a significant increase in the temperature of the mixing chamber in that stage to determine if the air supply was successful. This post was last edited by julius6054 on 2008-10-31 00:42.]
**Physical and Chemical Properties**
Molecular weight: 2.016
Melting point (101.325 kPa): -259.2°C
Boiling point (101.325 kPa): -252.8°C
Liquid density (-252.766°C, 101.325 kPa): 70.973 kg/m³
Gas density (0°C, 101.325 kPa): 0.0899 kg/m³
Relative density (25°C, 101.325 kPa, air = 1): 0.0695
Specific volume (21.1°C, 101.325 kPa): 11.9674 m³/kg
Compressibility coefficient:
Temperature (°C) | Compressibility coefficient at 101.325 kPa | Compressibility coefficient at 1013.25 kPa | Compressibility coefficient at 10132.5 kPa | Compressibility coefficient at 50662.5 kPa
25 | 1.001 | 1.000 | 1.006 | 1.006
100 | 1.0579 | 1.3244 | 1.3014 |
Critical temperature: -239.9°C
Critical pressure: 1297 kPa
Critical density: 31.0 kg/m³
Enthalpy of fusion (13.8 K): 58.16 kJ/kg
Enthalpy of vaporization (18 K): 457.80 kJ/kg
Heat capacities (101.33 kPa, 273.15 K): Cp = 14190 J/(kg·K), Cv = 10080 J/(kg·K)
Heat capacity ratio (26.8°C, 101.325 kPa): Cp/Cv = 1.405
Vapor pressure (16 K): 21 kPa; (24 K): 260 kPa; (32 K): 1100 kPa
Viscosity (101.325 kPa, 25°C): 0.00886 mPa·S
Surface tension (liquid-gas interface, -258°C): 2.80 mN/m
Thermal conductivity (100 kPa, 270 K): 0.16705 W/(m·K)
Refractive index (20.33 K, 100 kPa, liquid, 4047A): n = 1.11262; (20°C, 101.325 kPa, gas): n = 1.0001297
Flammability range in air (20°C, 101.325 kPa): 4.0–74.5%
Minimum ignition temperature in air (101.325 kPa): 570°C
Flame temperature during equivalent combustion in air: 1430°C
Maximum flame velocity during equivalent combustion in air: 2.65 m/s
Flammability range in oxygen (20°C, 101.325 kPa): 4%–94%
Minimum auto-ignition temperature in oxygen (101.325 kPa): 560°C
Flame temperature during equivalent combustion in oxygen: 2830°C
Maximum flame velocity during equivalent combustion in oxygen: 14.36 m/s
Heat of combustion during equivalent combustion in oxygen: 12761 J/m³ (high); 11506 J/m³ (low)
..................
Additionally, to determine whether air supply to the second stage is successful, first check that the pressure at the compressor outlet is at least 2 kilograms higher than the pressure in the second-stage furnace. After supplying air, observe whether there is a significant increase in the temperature of the mixing chamber in that stage to determine if the air supply was successful. This post was last edited by julius6054 on 2008-10-31 00:42.]
No combustion reaction is occurring; it’s possible that too much steam is being supplied to the coil. When adding air, reduce the amount of steam used