Patent GB-665921-A (GB)
Title: Improved method of and apparatus for carrying out physical and/or chemical operations involving treatment of a liquid with another liquid immiscible therewith
IPC: B01D11/04
Filed: 1949-02-03
Abstract: <PICT:0665921/IV (b)/1> <PICT:0665921/IV (b)/2> In a method of treating one liquid with a second liquid immiscible therewith by stirring them together in a treatment vessel from which they pass to a gravitational separator, one of the liquids separated in the separator is returned to the treatment vessel by utilizing the difference in level of the liquid in the treatment vessel at the periphery and centre thereof caused by stirring action.  The apparatus may comprise a treatment vessel a, Fig. 1, provided with a stirrer c, and a gravitational separator b connected to the treatment vessel at d and provided with top and bottom outlets g, h, designed as overflows, the overflows being arranged at such a mutual difference of level determined by the difference in specific gravity of the two liquids that equilibrium exists between the columns of lighter and heavier liquid between g and d and between h and d respectively, the overflow h being provided with a pipe e extending so far within the vessel a that it discharges within the vortex k formed by the stirring of the liquids.  The arrangement of Fig. 1 is adapted for the continuous washingout of an impurity from one liquid (the heavier) by a lighter liquid, which is continuously supplied at an inlet j of the vessel a and continuously withdrawn from the separator b at g.  A fixed quantity of heavier liquid is introduced into the vessel a at the beginning of the operation and is continuously circulated through pipe d, separator b, pipe f, overflow h and pipe e.  Alternatively the upper outlet g from the separator may be connected into the space above the vortex k so that the lighter liquid is recirculated, the heavier liquid being continuously supplied to the vessel a and withdrawn from the overflow h, which in this case does not lead back into the vessel a.  For countercurrent treatment of one liquid by another in a series of steps (e.g. the successive nitration of toluene to trinitrotoluene), a number of units, for example three, each consisting of treatment vessel and separator, may be connected together in the manner shown in Fig. 3, where the bottom overflows of the separators b2, b3 are connected to the treatment vessels a1 and a2 respectively and the top overflows of the separators b1, b2 are connected to the treatment vessels a2 and a3 respectively.  The nitrating acid, the heavier liquid, is continuously fed into a3 and withdrawn at h1, while the toluene is continuously fed into a1 and withdrawn at g3.  Each unit is a little higher than that to the left of it to ensure that the necessary differences in level are maintained.ALSO:In a method of treating one liquid with a second liquid immiscible therewith by stirring them together in a treatment vessel from which they pass to a gravitational separator, one of the liquids separated in the separator is returned to the treatment vessel by utilizing the difference in level of the liquid in the treatment vessel at the <PICT:0665921/III/1> <PICT:0665921/III/2> periphery and centre thereof caused by the stirring action.  The apparatus may comprise a treatment vessel a, Fig. 1, provided with a stirrer c, and a gravitational separator b connected to the treatment vessel at d and provided with top and bottom outlets g, h, designed as overflows, the overflows being arranged at such a mutual difference of level determined by the difference in specific gravity of the two liquids that equilibrium exists between the columns of lighter and heavier liquid between g and d and between h and d respectively, the overflow h being provided with a pipe e extending so far within the vessel a that it discharges within the vortex k formed by the stirring of the liquids.  The arrangement of Fig. 1 is adapted for the continuous washing-out of an impurity from one liquid (the heavier) by a lighter liquid, which is continuously supplied at an inlet j of the vessel a and continuously withdrawn from the separator b at g.  A fixed quantity of heavier liquid is introduced into the vessel a at the beginning of the operation and is continuously circulated through pipe d, separator b, pipe f, overflow h and pipe e.  Alternatively the upper outlet g from the separator may be connected into the space above the vortex k so that the lighter liquid is recirculated, the heavier liquid being continuously supplied to the vessel a and withdrawn from the overflow h, which in this case does not lead back into the vessel a.  For countercurrent treatment of one liquid by another in a series of steps (e.g. the successive nitration of toluene to trinitrotoluene), a number of units, for example three, each consisting of treatment vessel and separator, may be connected together in the manner shown in Fig. 3, where the bottom overflows of the separator b2, b3, are connected to the treatment vessels a1 and a2 respectively and the top overflows of the separators b1, b2 are connected to the treatment vessels a2 and a3 respectively.  The nitrating acid, the heavier liquid, is continuously fed into a3 and withdrawn at h1, while the toluene is continuously fed into a1 and withdrawn at g3.  Each unit is a little higher than that to the left of it to ensure that the necessary differences in level are maintained.