Upgrade residues to lighter hydrocarbon fractions using the Selective Yield Delayed Coking (SYDEC) process.
Charge is fed directly to the fractionator (1) where it combines with recycle and is pumped to the coker heater. The mixture is heated to coking temperature, causing partial vaporization and mild cracking. The vapor-liquid mix enters a coke drum (2 or 3) for further cracking. Drum overhead enters the fractionator (1) to be separated into gas, naphtha, and light and heavy gas oils. Gas and naphtha enter the vapor recovery unit (VRU)(4). There are at least two coking drums, one coking while the other is decoked using high-pressure water jets. The coking unit also includes a coke handling, coke cutting, water recovery and blowdown system. Vent gas from the blowdown system is recovered in the VRU.
Operating conditions: Typical ranges are:
Heater outlet temperature, ºF 900 – 950
Coke drum pressure, psig 15 – 100
Recycle ratio, equiv. fresh feed 0 – 1.0
Increased coking temperature decreases coke production; increases liquid yield and gas oil end point. Increasing pressure and/or recycle ratio increases gas and coke make, decreases liquid yield and gas oil end point.
Products, wt% Max dist. Anode coke Needle coke
Gas 8.7 8.4 9.8
Naphtha 14.0 21.6 8.4
Gas oil 48.3 43.8 41.6
Coke 29.3 26.2 40.2
Licensor: Foster Wheeler USA Corp./UOP.