GB700852A - Improvements in and relating to evaporating plant - Google Patents

Abstract

In an evaporator comprising a plurality of calandria sections in association with a liquid/vapour separator, the liquid-outlet of each calandria section, except the last, is connected directly, or indirectly, through the separator, to the liquid-inlet of the next calandria section so that the liquid flows through the calandria sections in sequence without circulation, except if desired through the last section; and the vapour-outlet of each calandria section leads the vapours evolved in <PICT:0700852/III/1> <PICT:0700852/III/2> <PICT:0700852/III/3> that section, without passage through the tubes of the following sections, to the separator. The calandria sections may be separate, or they may be incorporated in a single housing. The apparatus may be used for concentrating milk and malt extract. In Figs. 1 and 2, the apparatus comprises four steam-heated calandria A, B, C, D, and a separator 1, which may be evacuated through outlet 3. Fresh liquor is introduced through pipe 14 into the lower end-chamber of calandria A, and the liquor is maintained at a level of about two-thirds the height of the calandria. A film of liquor rises in the tubes of the calandria, and a mixture of liquor and vapour flows into separator 1. The base of the separator is divided by two partitions 4 into four compartments, which are open at the top, and have bottom-outlets a, b, c, d. The calandria and separator compartments are connected together by piping so that the upper end-chamber of calandria A leads into the first compartment, outlet a is connected to the lower end-chamber of calandria B, the upper end-chamber of calandria B leads into the second compartment, outlet b is connected to the lower end-chamber of calandria C, and so on. Vapour is drawn off from the liquor each time it passes through the separator. The concentrated liquor is discharged from the last compartment through outlet d and pipe 15. Suspended solids in the vapours rising through the upper portion of the separator are removed by a "save-all" device, which comprises conical ledge 16 and cap 18. The solids collected in the channel formed by ledge 16 are returned through an aperture (not shown) to the first compartment. The partition walls 4 may be curved instead of straight, in order to encourage turbulence in the liquor discharged into the compartments. The calandria may be inclined, instead of being vertical. In Fig 6, three calandria sections are built into a common housing 19, the bottom and upper chambers of which are separated into compartments by partitions 20, 21 respectively. Each compartment of the upper chamber communicates by an outlet 30 with a manifold 31 which leads by condut 24 to separator 1. The fresh liquor is introduced through inlet 22, flows up the tubes of the first calandria section, and then down conduit 23 to the bottom compartment of the second calandria section; it then passes through the second and third calandria sections. Vapour is withdrawn into the separator each time the liquor emerges into an upper calandria compartment. The concentrated liquor is withdrawn through pipe 26.