Experimental Study Of High Pressure Water Jet Technology Used In Black Smoke Pollution Control Of Small And Medium Coal Stove

The development of water jet technology is gaining rapid momentum in recent decades. Water jet technology can be used for engineering situations like surface cleaning, descaling, cutting, rock breaking and dust removal, etc. As a wet dust removal method, water jet technology is widely used for its outstanding features including environmentally friendliness, concentrated energy, high efficiency, cost-effectiveness, safe and convenient operation, etc. Though to some extent the secondary pollution caused by water jet dust removal restricts its application, the dry dedusting method is not preferred by small and medium enterprise for its low efficiency and high operation and maintenance cost. From the perspective of China's national conditions, the water jet dust removal method has great potential in black smoke control of small and medium coal stove.Based on the literature survey of wet dust removal techniques, its advantages and disadvantages are reviewed. In order to reduce energy consumption, enhance dedusting efficiency and lower operation and maintenance cost, the dedusting media and dedusting equipment are optimised in this paper. The tensiometric property of dust particle is firstly studied and the mechanism of surfactant is analyzed. Aiming to change the wetting property of dust particle, the traditional dedusting media, water, is transferred to the surfactant solution. Dust removal experiments are conducted using surfactant solutions with the lowest surface tension and the best surfactant solution for dust removal is determined. The best solution has 2.9mmol/L of sodium dodecyl sulfate, 20mmol/L of sodium silicate, 50mg/L of flocculating agent B and 7.1mmol/L tributyl phosphate. The dedusting experiment using this solution can result in up to 93.67% of dust removal rate.The structure of dedusting equipment is modified. The subpressure values under different structural parameters of Venturi air funnel are experimentally measured in order to optimize the structure of Venturi air funnel. The spraying nozzle that has the best performance of dust removal is determined by comparing the dust removal rate of cylindrical jet nozzles with 12 different values of outlet diameter and slenderness ratio and hollow tapered spraying nozzle. The experiments results show that the best dedusting performance can be obtained using hollow tapered spraying nozzle. The subpressure value and the quantity of inhaled dust can reach maximum using the dedusting equipment which has 80mm of Venturi throat diameter, 400mm of Venturi throat length, 10o taper of diffusion tube and 1.25mm of nozzle diameter. Besides, the effect of dust velocity and dust concentration on the optimal pump pressure and dust removal rate is studied experimentally. It's found that the optimal pressure is a function of dust velocity and dust concentration. The expression of the optimal pressure with varing dust velocity and dust concentration is obtained, which offers theoretical guide for different engineering scenarios. The experiment results demonstrate that the maximum value of the optimal pressure is 10.4 MPa and the increase of both dust velocity and dust concentration leads to the enhancement of dust removal rate which all exceed 88.5%. This type of Venturi dedusting equipment shows great prospect in industrial applications of dust removal as it can dramatically reduce energy consumption, save cash inputs, enhance dedusting efficiency and work steadily.