Ignition Dynamic Parameters for Coke in Cement Calciners

The mathematical ignition model was established and researches ofignition dynamic parameters for coke in some typical coal samplesfrom cement plants was carried out according to circumstances of coalcom- busted in cement plants. In order to get the ignitionintemperature T_pi of carbon particles more accurately, the tem-perature rising experimental method was used and the actual heatingcircumstances for pulverized coal in calciners (in cement plants)werealso considered.

Study on the ignition process of a segmented plasma torch

Direct current plasma torches have been applied to generate unique sources of thermal energy in many industrial applications. Nevertheless, the successful ignition of a plasma torch is the key process to generate the unique source （plasma jet）. However, there has been tittle study on the underlying mechanism of this key process. A thorough understanding of the ignition process of a plasma torch will be helpful for optimizing the design of the plasma torch structure and selection of the ignition parameters to prolong the service life of the ignition module. Thus, in this paper, the ignition process of a segmented plasma torch （SPT） is theoretically and experimentally modeled and analyzed. Corresponding electrical models of different stages of the ignition process axe set up and used to derive the electrical parameters, e.g. the variations of the arc voltage and arc current between the cathode and anode. In addition, the experiments with different ignition parameters on a home-made SPT have been conducted. At the same time, the variations of the arc voltage and arc current have been measured, and used to verify the ones derived in theory and to determine the optimal ignition parameters for a particular SPT.

STUDY ON MATHEMATICAL MODEL OF GAS EXPLOSION IN COAL MINE

Based on the principle of gas explosion in underground coal mine, mutation theory and mathematic method were adopted to establish" Mathematical model of coal mine gas explosion"and advanced some new concepts and ideas. The model can simply and precisely indicates underground air status and conforms to part of experimental data, provided a new method for research and experiment of explosion disaster theory.

Experimental simulation and numerical analysis of coal spontaneous combustion process at low temperature

The characteristic of coal spontaneous combustion includes oxidative property and exothermic capacity. It can really simulate the process of coal spontaneous combustion to use the large scale experimental unit loading coal 1 000 kg. According to the field change of gas concentration and coal temperature determined through experiment of coal self ignite at low temperature stage, and on the basis of hydromechanics and heat transfer theory, some parameters can be calculated at different low temperature stage, such as, oxygen consumption rate, heat liberation intensity. It offers a theoretic criterion for quantitatively analyzing characteristic of coal self ignite and forecasting coal spontaneous combustion. According to coal exothermic capability and its thermal storage surroundings, thermal equilibrium is applied to deduce the computational method of limit parameter of coal self ignite. It offers a quantitative theoretic criterion for coal self ignite forecasting and preventing. According to the measurement and test of spontaneous combustion of Haibei coal, some token parameter of Haibei coal spontaneous combustion is quantitatively analyzed, such as, spontaneous combustion period of coal, critical temperature, oxygen consumption rate, heat liberation intensity, and limit parameter of coal self ignite.

Discharge Characteristics of Large-Area High-Power RF Ion Source for Positive and Negative Neutral Beam Injectors

A large-area high-power radio-frequency（RF） driven ion source was developed for positive and negative neutral beam injectors at the Korea Atomic Energy Research Institute（KAERI）. The RF ion source consists of a driver region, including a helical antenna and a discharge chamber, and an expansion region. RF power can be transferred at up to 10 kW with a fixed frequency of 2 MHz through an optimized RF matching system. An actively water-cooled Faraday shield is located inside the driver region of the ion source for the stable and steady-state operations of high-power RF discharge. Plasma ignition of the ion source is initiated by the injection of argongas without a starter-filament heating, and the argon-gas is then slowly exchanged by the injection of hydrogen-gas to produce pure hydrogen plasmas. The uniformities of the plasma parameter,such as a plasma density and an electron temperature, are measured at the lowest area of the driver region using two RF-compensated electrostatic probes along the direction of the shortand long-dimensions of the driver region. The plasma parameters will be compared with those obtained at the lowest area of the expansion bucket to analyze the plasma expansion properties from the driver region to the expansion region.