Objective
To achieve energy saving in the distillation sequence of furnace cracking products in the vinyl chloride (VCM) production. Recovering the heat content in the vinyl chloride produced uncracked dichlorethane (DCE) and by-products in a perfectionating quench tower. The heat is transferred in subsequent heat cascades according to a thermodynamic optimisation of the separation process. The stream temperatures are maintained low enough to permit optimum heat exchange and decrease the fouling of the equipment by carbon deposition.
It has been carried out a heat recovery balance by means of the evaluation of the lower specific steam consumption referred to the vinylchloride production and it has been confirmed the attainment of the objectives : reduction of the steam consumption to one third corresponding to a saving of 10,500 TOE/year.
The vinyl chloride monomer is obtained by thermal cracking in furnaces of dichlorethane (DCE), the stream containing vinyl chloride (VCM), uncracked dichlorethane (DCE) and by-products is processed through various distillation steps to separate the components. The distillation sequence of the process will be adjusted to make it similar to the thermodynamically optimal configuration. To effect this the separation key components of the stream are selected as those the maximum difference in volatility. The separation streams thus obtained have maximum boiling point differences, in the sequential rectification steps the thermal levels created can be used as heat transfer cascades. The existing process with a nominal capacity of 170,000 ton/year is modified utilising in part the existing equipment, (distilling columns and exchangers) and adding a new column (diam=1.2 m, 38 trays) for the final separation of chloric acid. An in-line screw compressor will permit the use of the actual propylene refrigeration cycle (three steps temperatures : 0 deg. C, -20 deg. C and -35 deg. C). The steam consumed by the distillation reboilers is reduced to one third of the conventional process.
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
20097 San Donato Milanese
Italy