Full name : Dương Văn Đại
Class : K4
ID Student : CTTT13210111
ADECH04 – HOMEWORK 2
Advanced processes for MEG manufacturing
Ethylene glycol production by ethylene oxide hydration
Industrial plants carry out this conversion according to the following scheme :
The ethylene oxide feed is first diluted by a quantity of water such that the water per oxide molar ratio is 20-25/1 in order to favor the production of monoethylene glycol and to minimize that of its higher homologues.
The mixture obtained is initially raised to 150°C by heat exchange with the condensate from the final stage of a series of evaporators used further downstream, and then by means of stream, and is then introduced into the reactor.
The aqueous solution of crude glycols thus produced is then concentrated in a series of four evaporators operating at a pressure which decreases progressively. The steam leaving the top of a stage preheats the next stage. The condensate from the last evaporator , after being used to raise the feed to temperature, feeds the circulation of process water for the unit.
The mixture of glycols produced by this operation undergoes final dehydration, achieved by vacuum distillation , followed by fractionation in a series of three columns also operating under vacuum. Separated in succession at the top of these columns are monoethylene glycol, diethylene glycol and triethylene glycol.
Draw an out outline flow scheme for a balanced chlorination and oxychlorination vinyl chloride plant. Remember to show recycle streams. Presentation of the scheme of VC processing by combination ( figure 2.23).
Block diagram for balanced chlorination – oxychlorination vinyl chloride plant :
O2
Oxychlorination HCl recycle
C2H4 EDC purification EDC pyrolysis VC purification C2H3Cl
Direct chlorination
Cl2
EDC mode
The process chosen for vinyl chloride production is a combination of 2 process direct chlorination and oxychlorination. This process is referred to as the balanced process. Direct chlorination itself is a process that operate at lower temperature and produces fewer by – products when compared with oxychlorination. Oxychlorination is used in vinyl chloride production because it consumes the HCl. Currently, ≈ 95% of the world’s supply is produced using the balanced process.
The main reactions in this process are :
Direct chlorination : 𝐶
𝐻
2
𝐶
𝐻
2 + 𝐶
𝑙
2→ 𝐶𝑙𝐶
𝐻
2
𝐶
𝐻
2
𝐶𝑙
Oxychlorination : 𝐶
𝐻
2
𝐶
𝐻
2+2𝐻𝐶𝑙
1
2
𝑂
2→𝐶𝑙𝐶
𝐻
2
𝐶
𝐻
2
𝐶𝑙
𝐻
2
𝑂
EDC pyrolysis : 2𝐶𝑙𝐶
𝐻
2
𝐶
𝐻
2
𝐶𝑙→2𝐶
𝐻
2
𝐶𝐻𝐶𝑙+2𝐻𝐶𝑙
Overall reaction : 2𝐶
𝐻
2
𝐶
𝐻
2+𝐶
𝑙
2
1
2
𝑂
2→2𝐶
𝐻
2
𝐶𝐻𝐶𝑙
𝐻
2
𝑂