Baowei Li

Experimental Studies of Magnetic Effect on Methane Laminar Combustion Characteristics

ABSTRACT Influence of magnetic fields on the properties of methane laminar combustion was investigated experimentally. A high downward gradient of the square of the magnetic flux density was applied on methane laminar diffusion flame. The flame surface temperature and NOX concentration were measured by high-precision testing instruments. The flame size was analyzed by specific image raster analysis software. The results show that with the magnetic field intensity increasing, the flame dimensionless length decreases while the dimensionless width and flame temperatures increase. The gradient magnetic field exerts a great effect on the production of thermal NOX in the flame region under 35 mm due to the oxygen paramagnetic force. Compared to one gradient magnetic field, the concentration of NOX at least decreases by up to 60% on average.

PIV Measurements of the Turbulence Integral Length Scale on Cold Combustion Flow Field of Tangential Firing Boiler

The process of the pulverized coal combustion in tangential firing boiler has prominent significance on improving boiler operation efficiency and reducing NOX emission. This paper aims at researching complex turbulent vortex coherent structure formed by the four corners jets in the burner zone, a cold experimental model of tangential firing boiler has been built. And by employing spatial correlation analysis method and PIV (Particle Image Velocimetry) technique, the law of Vortex scale distribution on the three typical horizontal layers of the model based on the turbulent Integral Length Scale (ILS) has been researched. According to the correlation analysis of ILS and the temporal average velocity, it can be seen that the turbulent vortex scale distribution in the burner zone of the model is affected by both jet velocity and the position of wind layers, and is not linear with the variation of jet velocity. The vortex scale distribution of the upper primary air is significantly different from the others. Therefore, studying the ILS of turbulent vortex integral scale is instructive to high efficiency cleaning combustion of pulverized coal in theory.

The theory and expeiment about penetration depth of nozzle jets in the dense phase

Jets moving in the dense phase from the nozzle of circulating fluidized bed boiler is an important research subject. The penetration depth of jets from nozzles of two type, were theoretically calculated and experimentally investigated. Based on laws of momentum and making some suitable simplifying assumptions, a physical model of the oblique jetting flow from a nozzle was established and a cubic equation was derived, with which direct theoretical solutions were obtained. Based on the simulation condition of similar density, an equivalent hydraulic test rig for simulating the jets flow motion was built. At last we compared the penetration depth into the dense-phase zone of circulating fluidized bed boiler by two nozzles of different type. Research results indicate that the theoretical equation can express the penetration depth of arrow-type nozzle but not accurate enough for Γ-type nozzle; The model can guide on the variations of penetration depth of nozzle jets.

Experimental and numerical simulation research on cold aerodynamic field of tangential firing boiler

In order to know about coke phenomena of 130t/h boiler with tangential firing, velocity and valves characteristics of primary and secondary air were measured. Fireworks test and numerical simulation were done at the condition of actual working and uniform air distribution, and the tangential circle diameter of actual working and uniform air distribution were obtained. The results show that the boiler will be satisfied basically with uniform air distribution in four corners on the condition that air velocity is adjusted uniformly in different jet, the ideal aerodynamic field in boiler will be obtained, and it provides reference for hot state run

Research on NOx formation of flat-flame combustion with HTAC Technology

Based on the single swirl burner flat-flame combustion, the technology of High Temperature Air Combustion (HTAC) was adopted. The central combustion speed field under burner was measured by Particle Image Velocimetry (PIV) technique, as the same time, the temperature distribution in the furnace and concentration distribution of NO were measured by sensors. It appeared that with HTAC technology, combustion was stabilization, and fuel completely burnt; temperature distributing got uniformity, NOx formation decreased to 30ppm. Though regenerator, air temperature increased from 20°C to 200°C, smoke temperature decreased from 800°C to 80°C, it achieved the effect of energy conservation and environment protect.

A new hybrid method—combined heat flux method with Monte-Carlo method to analyze thermal radiation

Abstract A new hybrid method, Monte-Carlo-Heat-Flux (MCHF) method, was presented to analyze the radiative heat transfer of participating medium in a three-dimensional rectangular enclosure using combined the Monte-Carlo method with the heat flux method. Its accuracy and reliability was proved by comparing the computational results with exact results from classical “Zone Method”.