Patent GB-269517-A (GB)
Title: Improvements in distillation systems
IPC: C10C1/04
Filed: 1927-04-01
Abstract: 269,517. Semet-Solvay Co., (Assignees of Keane, A. F.). April 17, 1926, [Convention date]. Liquids, treating with gases. - A distillation apparatus for distilling light oils ' from the benzolized wash oil resulting from the washing of coal gas, comprises a still B connected to a unitary structure A containing a heat-exchanger H to preheat the liquid fed to the still and to cool vapours coming from the still, a condenser K receiving vapours from the heat exchanger, and a separator S which receives the condensate from the condenser and separates it into two layers to permit water and the producb to be separately withdrawn. The wash oil is delivered at a temperature of about 30‹ C. through a pipe 1, and passes through successive banks HI, H2, H3 of heating coils which are heated by hot vapours coming from the still B through piping 70. The oil feed is thus heated to about 95‹ C., while the higher boiling components of. the vapour is thus condensed on the bottom plates P1-P3 and hoods D1-D3 in the heat interchanger. The vapour containing the lower boiling components passes through a. pipe 17 to the condenser where it passes successively over banks of water-cooled tubes K1, K2, K3. The vapour is thus condensed on the bottom plates of each section and flows over collars L from one plate to another until it reaches the separator S. Any non-condensable gas is expelled through a valve V. The water which forms the lower layer in the separator is drawn off through an adjustable overflow J while oil flows through an outlet O to collectors C which constitute the bottom sections of the two columns and are connected by a pipe 60. The water overflow comprises an adjusting member 199 having a stem passing through the cover plate 204 and engaging a slotted pipe 205 which makes a liquid tight joint with a diaphragm 207. By raising the handle 208 of the adjusting member, the height of the slots 206 is increased and thus since the column in the overflow balances the liquid column in the separator, the plane of division between the water and oil layers in the separator is controlled by the adjustment of the overflow. The preheated wash oil is conducted to one of the upper plates P of the still through a pipe 7 and flows downwards over collars L which are diametrically arranged on successive plates as shown in Fig. 1. Steam is introduced at 8 and as the vapours flow upwardly through the liquid seals on the plates P the lower boiling components in the oil are evaporated and the higher boiling components are condensed, the composition of the vapour being so controlled that the vapour passing through the pipe 70 contains all the light oils while the condensate consists substantially of debenzolized wash oil. The construction of the column A is shown in Figs. 2 and 3. The sections of the column are secured together by means of flanges F and gaskets, and the water and oil outlets 12, 10 respectively are cast integrally on the separator S. A collar L1 of the separator forms a passage communicating with a collar L2 on the lowermost condenser section which is itself formed with a second collar L3 arranged diametrically opposite the collar L2 and communicating with the overflow collar of the next section. The collars L2, L3 are connected by a deflector E1 having a plurality of ports M to distribute the vapour through the condenser tubes N. The banks of condenser tubes are supported in housings T1-T6 cast integrally with the body portions of the sections, water connections W4-W6 being made to the housings T4-T6. The condenser is separated from the heat interchanger by a spacer ring Z and a plate Q4 is located above the spacer ring. The lower section Y1 of the heat interchanger is cast integrally with a dephlegmator plate PI supporting the hood D1 by means of bolts and lugs 15. An overflow collar L9 fitted to the next section Y2 co-operates with the collar L8 to form an overflow passage and a similar diametrically opposed passage is constituted by collars L10, L11 on the members Y2, Y3 respectively. Banks of tubes are supported in housings T7-T12 in the sections Y2-Y4 and piping connections 100 and valves 101 are provided to control the flow through the tube banks. The column is fitted with a number of external gauge glasses and with drains to prevent excessive accumulation of liquid. A chain operated valve 19 controls the flow of vapour through the pipe 18. The distillation column B is also built up of bolted sections, Fig. 5, the collector C being surmounted by a spacer ring Z carrying condensate or steam trap section which is provided with an overflow collar L12 and a trap float and discharge mechanism. The distillation column proper comprises rings 26 each having a lower overflow collar 27 and a diametrically opposed upper overflow collar 28 which co-operate to form passages between the rings. Plates P extend between the overflow collars and the walls of the column and support the hoods D by means of spaced lugs 15 cooperating with the hubs 31 of bells 32. The collars forming the overflow passages extend round about a quarter of the periphery, as shown in Fig. 8, and the floor plates have central open projections 30 having upper surfaces. on a level with the overflow collars. Strengthening webs 50 are provided beneath the plates and webs 53, 54 in the overflow passages serve to strengthen the collars at the mid section. The overflow collars are of notched weir form, the notch 82 being flanked by raised portions 84. This allows the gases to escape past the falling stream of liquid through the passages adjacent the portions 84. The hood-supporting lugs 15 are bifurcated at 61 for ease of assembly. Serrations 58 and 57 are provided in the peripheral edges of the hoods and of the bells respectively, thus affording a number of orifices for the upwardly moving vapour. An eye bolt may be inserted in a hole, 59 to enable the hood to be lifted when required.