Patent GB-778238-A (GB)
Title: Process and apparatus for separating coal hydrogenation products
IPC: C10G1/06
Filed: 1954-11-10
Abstract: In a process for the hydrogenation of coal, the product-mixture discharged from the hydrogenator is subjected to gravity separation whereby vapours and gases separate from heavy oils, ash and unreacted coal, the three latter being collected as a slurry in a sump; the vapours are condensed and condensate is added to the slurry whereby the light oils are revaporized and the slurry is simultaneously cooled; the light oil vapours are cooled so that the less volatile components thereof are condensed and flow back to the sump <PICT:0778238/III/1> <PICT:0778238/III/2> as reflux; the uncondensed vapours and gases are withdrawn from the system as one of the separation-products, the other being slurry withdrawn from the sump. The process permits the cooling of the slurry without the use, and consequent fouling, of a heat-exchanger; and enables a light product to be obtained which is free from heavy polymer-forming contaminants. Figs. 1 and 2 show top and bottom portions respectively of a suitable apparatus.  The product-mixture from the hydrogenator (not shown), at a temperature of 425 DEG -525 DEG C. and a pressure of 2500-6000 p.s.i.g., enters the top portion of the separator through pipe 11. The mixture flows down pipe 12, and is released through lateral exit ports 14 into chamber 13, where there is a large reduction in velocity so that primary separation of the mixture occurs by gravity. The slurry flows down pipe 15 into a sump 16 (Fig. 2) into which it is delivered through port 29, which is below the liquid-level in the sump.  The vapours and gases leave the top of chamber 13 through annulus 17, and then flow down over coils 20 which are cooled by compressed hydrogen flowing upwardly through them.  This hydrogen is introduced into the apparatus through pipe 55, and leaves it through pipe 56.  The condensate, at about 300 DEG C., together with the uncondensed vapours and gases, flows down annulus 22 and then through ports 24 into cone 25.  From this cone, the condensate, vapours and gases leave the top of chamand emerge into sump 16 through exit 28. The condensate flows down into the sump where flash vaporization of the light oils takes place.  The flashed vapours, together with the vapours and gases emerging from exit 28, flow upwards and pass over coils 31, which are cooled by water flowing through them. This water is introduced through pipe 57; and the steam generated in the coils leaves through pipe 60.  Some of the vapours are condensed on the outside of coils 31, and the condensate refluxes back into the sump. The temperature of the liquid in the sump is normally between 320 DEG and 400 DEG C.  The uncondensed vapours and gases are deflected by cone 25, and flow down pipe 38 into annular space 39; they then flow through annulus 43, which surrounds pipe 33, to discharge pipe 46. Sump-product is continuously withdrawn through pipe 33.  The level of the liquid within the sump is determined by the pressure-differential within the apparatus, which is measured at nozzles 34 and 35 which are connected through tubes to an external recorder.  The flowrate and temperature of the water supplied to coils 31 are used to control the composition of the products removed from the separator.  Coils 20 may, in certain circumstances, also be used to control the separation.  In order to counter the corrosive action of hydrogen, there is inserted, within the outer vessel, a removal unit 62 comprising a thin inner shell 23 of highly corrosion-resistant metal wrapped with an insulation composed of laminated glass cloth and metal foil encased in a metal cover.  Hydrogen, introduced through conduit 64, continuously sweeps through the surrounding space 63 and prevents condensation therein.