Caustic soda (2.2 mol NaOH per mol of bromine) is diluted with water (2.5 kg per kg of bromine in all), the phase-transfer catalyst tetrabutylammonium bromide added (5 g per kg of bromine) and the charge cooled to 278 K. Liquid bromine is dosed into it over 1.7 h and reacts to sodium hypobromite and bromide. The cold hypobromite goes to the haloform reactor, where acetone (5 % above 1 mol per 4 mol of bromine) is dosed over 4.5 h at 278 K and stirred for another 4.1 h: the hypobromite brominates and cleaves it to carbon tetrabromide and sodium acetate, C3H6O + 4 NaOBr -> CBr4 + CH3COONa + 3 NaOH, the aqueous route of CN 101 885 665 A. CBr4 is nearly insoluble in the cold liquor and precipitates. The slurry is filtered, the cake reslurried in about 2 kg of water per kg and filtered again, and dried at 308 K under vacuum in agitated filter-dryers (two units, taking the batches in turn), their jackets on hot water of 318 K at most, below CBr4's polymorph transition at 320 K; a vacuum condenser on cooling water takes the vapour. The product is 99.6 wt% CBr4 with 0.3 wt% dried salts and 0.1 wt% water; the yield is 98.4 % of the CBr4 the bromine can make and 93.7 % on acetone. The mother liquor (14 wt% NaBr, 5 wt% NaOH, 3 wt% sodium acetate, traces of bromate) and the wash go to wastewater treatment: the bromide is not recovered.
The batch is modelled with cheme-as-code's semi-batch reactor (reactor: semibatch, core ADR 0050) for both dosed steps and its batch recipe (process/recipe.yaml, core ADRs 0051 and 0052): the dosing and post-reaction times come from the models, the haloform reactor is the bottleneck (cycle 11.38 h, 696 batches a year), the recipe sizes the three 4 m3 vessels and checks the two reactors' jackets at the mean temperature of the 258/263 K brine (the 4.5 h acetone dosing and the 1.7 h bromine dosing are what the jackets remove), and the flowsheet's flows are the recipe's year averages. The precipitation and the reslurry wash are cheme's crystallizer with the liquor's salts as spectators; the filter-dryer is one vessel over filtration, wash, refiltration and drying, its times and steam from cheme's filter and dryer models (core ADRs 0056, 0057). No gas forms, so no vent stream. The kinetics are ASSUMED (no open data); the heats are Hess's-law estimates (-41 kJ per mol of bromine, -521 kJ per mol of acetone). The acetone accumulates to 12.1 % at most and the cooling-failure temperature stays at 284.8 K against the 329.3 K boiling point of acetone, while the whole batch's adiabatic rise is 68 K; with a 100 times slower reaction the cooling-failure temperature would pass that boiling point. See DESIGN.md for every assumption.
