Numerical Simulation of Combustion Characteristics in High Temperature Air Combustion Furnace

The influences of air preheating temperature, oxygen concentration, and fuel inlet temperature on flame properties, and NOx formation and emission in the furnace were studied with numerical simulation. The turbulence behavior was modeled using the standard k-ε model with wall function, and radiation was handled using discrete ordinate radiation model. The PDF （probability density function） /mixture fraction combustion model was used to simulate the propane combustion. Additionally, computations of NOx formation rates and NOx concentration were carried out using a post-processor on the basis of previously calculated velocities, turbulence, temperature, and chemical composition fields. The results showed that high temperature air combustion （HiTAC） is spread over a much larger volume than traditional combustion, flame volume increases with a reduction of oxygen concentration, and this trend is clearer if oxygen concentration in the preheated air is below 10%. The temperature profile becomes more uniform when oxygen concentration in preheated air decreases, especially at low oxygen levels. Increase in fuel inlet tempera- ture lessens the mixing of the fuel and air in primary combustion zone, creates more uniform distribution of reactants inside the flame, decreases the maximum temperature in furnace, and reduces NOx emission greatly.

Lowering the cost of large-scale energy storage:High temperature adiabatic compressed air energy storage

Compressed air energy storage is an energy storage technology with strong potential to play a significant role in balancing energy on transmission networks,owing to its use of mature technologies and low cost per unit of storage capacity.Adiabatic compressed air energy storage(A-CAES)systems typically compress air from ambient temperature in the charge phase and expand the air back to ambient temperature in the discharge phase.This papers explores the use of an innovative operating scheme for an A-CAES system aimed at lowering the total cost of the system for a given exergy storage capacity.The configuration proposed considers preheating of the air before compression which increases the fraction of the total exergy that is stored in the fom of high-grade heat in comparison to existing designs in which the main exergy storage medium is the compressed air itself.Storing a high fraction of the total exergy as heat allows reducing the capacity of costly pressure stores in the system and replacing it with cheaper thermal energy stores.Additionally,a configuration that integrates a system based on the aforementioned concept with solar thermal power or low-medium grade waste heat is introduced and thoroughly discussed.

Dome Combustion Hot Blast Stove for Huge Blast Furnace

In Shougang Jingtang 5 500m 3 huge blast furnace ( BF ) design , dome combustion hot blast stove ( DCHBS ) technology is developed.DCHBS process is optimized and integrated , and reasonable hot blast stove ( HBS ) technical parameters are determined.Mathematic model is established and adopted by computational fluid dynamics ( CFD ) .The transmission theory is studied for hot blast stove combustion and gas flow , and distribution results of HBS velocity field , CO density field and temperature field are achieved.Physical test model and hot trail unit are established , and the numeral calculation result is verified through test and investigation.3-D simulation design is adopted.HBS process flow and process layout are optimized and designed.Combustion air two-stage high temperature preheating technology is designed and developed.Two sets of small size DCHBSs are adopted to preheat the combustion air to 520-600℃.With the precondition of BF gas combustion , the hot blast stove dome temperature can exceed 1 420 ℃. According to DCHBS technical features , reasonable refractory structure is designed.Effective technical measures are adopted to prevent hot blast stove shell intercrystalline stress corrosion.Hot blast stove hot pipe and lining system are optimized and designed.After blowing in , the blast temperature keeps increasing , and the monthly average blast temperature reaches 1 300℃ when burning single BF gas.