Particle size brown coal

In the case of carbonized lignite, Kreusing and Franke (1979) achieved a maximum weight concentration of 34%, and with brown coal they achieved a maximum weight concentration of 41-46%, depending on the solid particle size. Brown coal is often a low-... 

Aluminium and Precipitator Ash. In some Victorian brown coals significant quantities of acid-soluble aluminium are found. This is believed to be present as aluminium hydroxide which is dispersed throughout the water phase of the coal. During combustion of this coal, the refractory aluminium oxide formed takes the shape of the relics of the plant material present in the coal, thus forming an extremely low density ash (approximately 100 kg/m ). Whilst the collection of these particles by electrostatic precipitation is possible, the problem of reentrainment on rapping has necessitated the use of larger sized units than would otherwise be required. It is therefore important to determine the acid soluble aluminium fraction in the coal to determine if precipitation of fly ash is likely to be a problem. 

Particle size analysis of alkali-digested brown coal provides a useful insight into coal structure. 

Use of the Field tube for determining the performance of coals is limited by the short residence time of 0.3 seconds (2.1 m) and the inability to use particles larger than 0.14 mm. This limits the extent of particle size changes and the structure of the mineral substance relative to pulverized fuels or coarse-crushed brown coals used in utility boilers. This difference probably has an effect on the formation of deposits. 

Coldry is a recently proposed method that is mainly an evaporative drying process based on brown coal densification. In the process, the coal is sheared and attritioned, which results in particle size reduction and releasing water naturally in the porous coal structure (Moore, 2012). This dispersal of surface and/or physically bound water is then evaporated at or near ambient temperature. The extra benefit of brown coal densification is that some chemically bound water is also removed without the need of high tanperature/pressure. The new structure of a dried coal by this method also reduces the tendency to self-heat. 

The shredded PVC waste (20 - 30 mm particle size) is burnt continuously together with brown coal dust, sand and calcium-chloride solution. Brown coal dust and sand improve the burn-out and the recovery of chlorine sand also bonds with heavy metals etc. in the slag. The third additive is a 30% calcium chloride solution, recirculated from the waste water unit. Under incineration conditions calcium chloride is converted to calcium silicate and HCl. 

Since the form of the deposits produced and their adhesive properties are determined by different factors (ash composition, particle size, temperature, state of the surface being cleaned, etc.), the best means of cleaning must be considered separately in each specific case. The ash from different fuels may in fact differ considerably. Whereas the m mum size of the ash from coal-dust furnaces is no greater than 120 n, that from shale furnaces reaches 300 M, while the mean diameter of the ash particles from Pechorsk coal [459] fluctuates between 3.5 and 125 p. On the other hand, the light-brown deposits of aluminosilicates are fine and easily blown away, while the dark Fe304 and Fe203 are very hard and the boiler has to be put out of service in order to remove them [457] the deposits formed in the combustion of fuel oil are also extremely hard to remove. 

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