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Thermal Process Intergration

◈ Petrochemical Process

Process integration between Stripper & Column

There are two adjacent unit operations, distillation and stripping column, consuming 34 ton/h steam and circulating 1,650 ㎥/h cooling water. Distillation consumes 12 ton/h steam for reboiler and 740 ㎥/h cooling water is used for condenser. Stripping consumes 22 ton/h steam for reboiler and 480 ㎥/h cooling water is used for condenser and 430 ㎥/h cooling water is used for 159 ton/h residue cooling down to 80℃, while the overhead vapor is partially utilized to heat up demineralized water and to preheat feed to the stripping column.

We are inquired by customer to find the optimal integration of two operations for energy regeneration.

100% of the stripping column overhead vapor mainly consisted of water is compressed by 2-stage turbo fan type MVR to elevate temperature from 105℃ to 122℃, 19 ton/h after spraying 1 ton/h desuper heating condensate, which is short in temperature and flow rate required by reboiler that TVR is added to compress to the pressure of 2.4 ㎏/㎠G with an aid of 3 ton/h motive steam.

Since we have used all the overhead vapor which was used for heating the demi-water (35 ton/h) and preheating of the stripper feed (177 ton/h), we have to find an alternative heat source of 4.8 Mcal/h. By installing one condensing evaporator to utilize the distillation column overhead vapor, 3 ton/h of 105℃ low pressure steam shall be produced, which however is good for heating the demi-water. For preheating the stripping column feed, new cooler/preheater shall be installed having heat duty of 3.2 Mcal/h by cooling the residue down to 78℃.

Now, the process is well balanced that we have regenerated 19 ton/h steam and saved 1,100 ㎥/h cooling water circulation, instead MVR motor power of approximately 530 KWh is consumed.