Study Of Preparation And Properties Of Slurry Fuel Based On Petroleum Coke

Preparation of petroleum-coke-water-slurry (PCWS) can broaden scope of raw materials of fuel of oil substitute and gasification, and settle problem of tension supply of bituminous coal. PCWS, which has high solid concentration, high heat value and low ash content, can burn instead of oil, gas and coal, also can provide raw materials of large-scale efficient clean coal gasification technology. The production of fuel type petroleum coke increases year by year in China. The technology of PCWS can achieve high efficient and clean utilization of petroleum coke, but the bad stability restricts development and application of PCWS. It’s important to improve stability of PCWS.In order to improve the quality of PCWS, this paper studies properties of PCWS and its influencing factors, and puts forward methods of improving the stability. The main work is carried out as follows:Many types of petroleum cokes and additives are used for PCWS whose slurryability, rheological characteristics and stability are investigated. Results show that petroleum cokes have good slurryability with solid concentration being about70%generally. The slurryability is enhanced with increasing particle size distribution range and average particle size, and with decreasing specific surface area and pore volume. The solid concentration is inversely proportional to inherent moisture content and ash content of the petroleum coke, and the inherent moisture content is more adverse. Surface characteristic of petroleum coke is strong hydrophobicity, which is in favor of enhancing the concentration and makes PCWS be dilatant and unstable fluid easily.The effect of various kinds of ash on the stability of PCWS is researched. Results show that the stability can be improved effectively by adding a small amount of CaO. When the adding quality of CaO is0.3%of dry basis petroleum coke, PCWS has high performance, whose concentration is68.0%, flow characteristic index is0.78, and drainage rate is3.4%at fixed viscosity.The influence of ratio of coal and coke (or sludge content) on surface characteristic of slurries prepared with petroleum coke and lignite or sludge is studied. Results show that surface tension and Zeta potential absolute value increase, and stability and pseudoplasticity enhance, but slurryability goes worse, with increasing ratio of coal and coke (or sludge content). The stability is positively related to the pseudoplasticity and negatively related to the slurryability. When the ratio of coal and coke is1:4, lignite coke slurry has high performance, whose concentration is above65%, flow characteristic index is about0.9, and drainage rate is about4%at fixed viscosity. When the sludge content is6%, sludge coke slurry also has high performance, whose concentration is about64%, flow characteristic index is less than0.8, and drainage rate is about5%at fixed viscosity.Bubble-petroleum-coke-water-slurry (BPCWS) is prepared to improve stability of PCWS. The influence of various factors in the preparation process on the stability is studied by single factor analysis and multiple factors orthogonal method respectively. Results show that the effects of blowing time, foaming agent dosage and solid concentration on the stability are very significant, while the effects of foaming agent type and ventilation panel aperture size are slight. The operating conditions of obtaining the best stability are blowing for30min, concentration being65%, foaming agent dosage being0.030%,2～5μm aperture size and AOS. Under the optimal conditions, pouring rate of BPCWS is more than96%, which increases by about80percentage points compared with pure PCWS (no bubbles). The BPCWS has good stability and obvious pseudoplasticity with flow characteristic index being about0.8.On the basis of experimental research, the microscopic mechanism of BPCWS is analysed. Results show that bubble formation depends mainly on the foaming agent which has an optimum dosage. The most stable form of bubbles in slurry is gas-solid-union forming through collision, adhesion and desorption. The collision probability between particles and bubbles is enhanced with decreasing bubble diameter, and with increasing microturbulence intensity. The stronger the hydrophobicity of particle surface, the larger the contact angle, the more easily the particles adhere to the bubbles.