Coal the solid fuel one of the energy source known to us. When heated at high temperatures in a forex binary breaker system system by resisting the contact with air or oxygen it turns into a substance called coke. During the heating process, valuable chemical compounds escape from coal as vapour and eventually, solid coke is formed. Benzene, toluene and xylene are some of the components present in the gases.
The mixture of these components recovered from coke oven gas in benzol section of a coal chemical process plant. Extractive distillation technology provides effective separation of these compounds in pure liquid form. Initially, xylene is separated from the mixture by distillation than the left out benzene and toluene mixture is subjected to extractive distillation. The process requires the following distillation and separation unit operation. The BTX solvents raffinate is pumped to the feed surge drum and from it, the mixture continuously pumped to pressure distillation column through four heat exchangers. General distillation column used in most industries designed with 50 bubble cap trays is sufficient to perform the distillation operation. The BT excess is pumped from the vessel via heat exchangers and fed to the extractive distillation column.
The engineering model separation column has 60 trays and feed is introduced in the middle of the column. The solvent NFM temperature directly affects the separation of aromatics from non-aromatics. Extractive distillation column makes it possible to separate non-aromatics contained in the feed, which is not possible under normal distillation conditions. The solvent changes the boiling points of non-aromatics from higher to lower and makes it easy to withdraw at the top of the extractive distillation column. Aromatics dissolve in the NFM solvent and removed from the bottom of the extractive distillation column. The LP Steam reboiler and partially vapour heated reboiler supplies heat to the extractive distillation column. Top pressure 0.
Bottom pressure 0. To separate non-aromatics and residual carried over solvent contents, solvent recovery column is used. Top vapours of the extractive distillation column injected to the location below pall rings packing of the solvent recovery column. NFM recovered at the bottom of the column is returned to the extractive distillation column. The purpose of the solvent recovery column is to eliminate the loss of NFM losses. Bottom pressure 0.
NFM and the dissolved aromatic solution obtained from the bottom of the extractive distillation column are fed to stripping column to recovery NFM for recycling. The column is operated along with aromatic column which operates at a vacuum, pure aromatics are separated from the top and the NFM from the bottom. The heat of NFM is used to for the preheating the stream in heat exchanger system and returned to the extractive distillation column. NFM is cooled by the trim cooler using solvent stream.