Conispherical Magma Crystallizer
Conispherical Magma Crystallizer
Conispherical Magma CrystallizerFlash EvaporatorA flash evaporator unit for a multistage flash evaporation plant wherein successive evaporation stages are operated at successively decreasing temperatures and pressures to evaporate water from a brine solution, said evaporator unit comprising:an elongated enclosure having opposed end walls; a tube bundle extending between said end walls to provide at least one upper condenser chamber to which vapor is directed from a lower evaporation chamber through which brine flows in the cross-direction; means including a tray for collecting distillate from said tube bundle; duct means extending in the cross-direction through successive evaporator units in said plant and disposed to collect distillate from said tray means; means for holding the traydistillate in a space isolated from said duct means prior to its entry into said duct means; means for detecting the conduction of the duct distillate outflow from said evaporator unit; and means for bypassing distillate from said holding space to anevaporation chamber in the same or a subsequent stage so that contaminated distillate can be withheld from the accumulating distillate flow in said duct means when said detecting means indicates said evaporator unit is producing contaminated distillate.Oslo CrystallizerOslo type crystallizer also called classified-suspension crystallizer is the oldest design developed for the production of large, coarse crystals.The basic design criteria are twofold:
The classifying crystallization chamber is the lower part of the unit. The upper part is the liquor-vapor separation area where supersaturation is developed by the removal of the solvent (water for most applications). The slightly supersaturated liquor flows down through a central pipe and the supersaturation is relieved by contact with the fluidized bed of crystals.Conispherical Magma CrystallizerCrystals are grown in many shapes, which are dependent upon downstream processing or final product requirements. Crystal shapes can include cubic, tetragonal, orthorhombic, hexagonal, monoclinic, triclinic, and trigonal. In order for crystallization to take place a solution must be "supersaturated". Supersaturation refers to a state in which the liquid (solvent) contains more dissolved solids (solute) than can ordinarily be accomodated at that temperature.As with any separation method, equilibrium plays an important role. Below is a general solubility curve for a solid that forms hydrate (a compound that has one or more water molecules attached) as it cools.On an industrial scale, a large supersaturation driving force is necessary to initiate primary nucleation. The initiation of primary nucleation via this driving force is not fully understood which makes it difficult to model (experiments are the best guide). Usually, the instantaneous formation of many nuclei can be observed "crashing out" of the solution. You can think of the supersaturation driving force as being created by a combination of high solute concentration and rapid cooling. In the salt example, cooling will be gradual so we need to provide a "seed" for the crystals to grow on. In continuous crystallization, once primary nucleation has begun, the crystal size distribution begins to take shape. Think about our salty water, as you look at Figure 2 describing the progression of crystallization.
- Desupersaturation of the mother liquor by contact with the largest crystals present in the crystallization chamber.
- Keeping most of the crystals in suspension without contact by a stirring device, thus enabling the production of large crystals of narrow size distribution.