DE2402517C3 - Process for the thermal treatment of contaminated salt solutions - Google Patents

Description

The invention relates to a method for the thermal treatment of contaminated salt solutions in a reactor with a fluidized bed and free space above, the solution, the fuel necessary for the thermal treatment and the combustion air being introduced into the fluidized bed and the temperature in the free space being essential is kept higher than in the fluidized bed and the amounts of the substances supplied, including fluidized bed material, are coordinated so that incomplete combustion ^{takes place in the fluidized bed at about 400 0} C and that the combustible components leaving the fluidized bed in the free space above at temperatures of at least 800 ⁰ C are completely burned, the fluidized bed being formed in the course of the process essentially from the solid residues of the salt-containing solution and a predetermined fluidized bed height is maintained by continuous removal of fluidized bed material according to patent 23 54 513.

In such a process, it is advantageous if the fluidized bed reactor is released continuously peeled off granular salt product can be reused. Depending on the intended use, the salt made various high purity requirements. It has been shown that when using the various fuels and if incomplete combustion is maintained in the fluidized bed reactor Soot accumulated on and in the salt. The withdrawn salt is more or less gray in color as a result of the soot inclusions.

According to the invention, the method is improved in that the withdrawn salt product on a Grain size, essentially milled smaller than 150 μ and the salt dust is introduced into the afterburning space above the fluidized bed.

The advantage of the inventive development j of the method is in particular that everything from The salt withdrawn from the process in the separation devices downstream of the fluidized bed reactor in pure Form is regained.

The grinding process exposes the soot stored in the grain of salt ίο and passes through it the hot afterburning zone in the fluidized bed reactor is burned without residue. Appropriately, the Salt dust pneumatically conveyed and blown into the post-combustion chamber. Possibly existing oversized grain falls back into the fluidized bed, d. H. the afterburning chamber with its gas flow acts as a sifter.

A variation of the method within the scope of the invention also consists in the fact that the bottom consists of the fluidized bed reactor withdrawn salt is ground to a fineness of less than 800 μ, the sifted Fine material, smaller than 150 μ, was added to the post-combustion zone and the oversized grain again as Nucleating agent is returned to the fluidized bed.

The invention is explained in more detail by way of example with the aid of the drawing. In the fluidized bed reactor 1 is located above the grate 2 by supplying combustion air via the line 3 in the vortex state held bed 4 of small solid particles. When the bed is first approached, it is usually made of sand a certain grain size. The fuel for the combustion is via line 5 into the fluidized bed guided. There is no complete combustion of the fuel in the fluidized bed area. the Saline solution added via line 6, which is subjected to the thermal treatment, must not by means of special devices, such as. B. nozzles are sprayed. The one in turbulence The fluidized bed provides the necessary distribution. There were some in the fluidized bed, usually more than 50% of the salt contained in the solution on the suspended solid particles even solid particles. The remaining part is with the gas mixture, which consists of residual air, residual fuel and a residue of organic combustible gaseous substances consists of the fluidized bed in the free upper space, the afterburning space 7, of the fluidized bed reactor carried.

Since the combustion reaction is no longer disturbed here, complete combustion takes place here of the still flammable parts and their conversion into pollutant-free gases at temperatures between 800 and 1000 ° instead. The combustion products leave via outlet 8, mixed with the rest Salt part, the fluidized bed reactor.

Solid salt product is continuously withdrawn from a side outlet 9 in the fluidized bed reactor so that the The fluidized bed does not grow beyond its intended height. This salt product is fed to the grinding plant 10 fed and ground to the desired degree of fineness (, o. The ground material is pneumatically using the Device 11 guided into post-combustion chamber 7. The soot is removed via the outlet 8 Salt is carried on and reaches downstream separation devices, from which clean salt is drawn off will.

1 sheet of drawings

Claims (1)

Claim: Process for the thermal treatment of contaminated salt solutions in a reactor with a fluidized bed and free space above, the solution, the fuel necessary for the thermal treatment and the combustion air being introduced into the fluidized bed and the temperature in the free space being kept significantly higher than in that Fluidized bed, the quantities of the substances supplied, including fluidized bed material, are coordinated in such a way that incomplete combustion ^{takes place in the fluidized bed at around 400 °} C., and that the combustible components leaving the fluidized bed are completely burned in the ^{free space above at temperatures of at least 800 ° C.} whereby the V.'irbeibett is essentially formed in the course of the process from the solid residues of the salt-containing solution that are formed and a predetermined fluidized bed height is maintained by continuously withdrawing fluidized bed material according to patent 23 54 513, characterized in that the fluid from the vortex The salt product withdrawn from the bed (4) is ground to a grain size essentially smaller than 150 μm and the salt dust is introduced into the afterburning chamber (7) above the fluidized bed.