Delayed coker system

There is little danger, in injecting a controlled amount of water into a furnace inlet, when using a properly designed metering pump. Such pumps typically have a capacity of 1 to 10 GPM and provide a set flow, regardless of the discharge pressure. The injected water flashes immediately to steam inside the furnace tubes. Vfe have retrofitted several vacuum and delayed coker heaters with condensate injection systems, with no adverse downstream effects. Water from the hot well of a vacuum ejector system is our normal source of condensate for this environmentally friendly modification. 

The complexity of formation of mesophase must not be underestimated. With the exception of a few model compounds, it is the industrial pitch which is the source of mesophase. Such materials contain thousands of reactive molecules and there is an interdependence in the carbonization system which currently is known to us but not analyzed in depth. This is an area for further research. Formation of mesophase is further complicated because it involves chemistry within a fluid/plastic system of increasing viscosity. And in the delayed coker, volatile release and liquid turbulence are yet additional factors in influencing final structure in mesophase. 

According to the chemical safety alert Hazards of Delayed Coker Unit (DCU) Operations (US EPA, 2003), some actions have been reported as beneficial to diminish the occurrence of incidents associated with incorrect valve activation due to mistaken coke drum or module identification. Some of the actions Usted in the referred safety alert are provide interlocks for valves that are manually operated as part of the switching/decoking cycle to avoid unanticipated valve movement provide interlocks for automated or remotely activated valve switching systems . These recommended actions can be achieved with the definition of set of permissive logics to prevent inadvertent valve operations. This set of logics can serve as an automated decision support system for the coke drum cycle. 

A delayed coker consists of a furnace to heat the feedstock to around 500 °C, two pressure vessels (coke drums) with a diameter of 4 to 7 m and 20 to 30 m high, together with a distillation system to separate the volatile components. Figure 13.8 shows the flow diagram for the delayed coking process. 

Vacuum distillate. This stream was directed to the refinery s recovered oil system (i.e., slop) and eventually reprocessed at the delayed coker. 

Heat-stable salts have several sources. In tefineiies, FCCU gases may contain traces of formic, oxalic, and acetic acids. Traces of oxygen in various refinery gas streams (e.g., FCCU, delayed coker, vacuum unit, vapor recovery system), air leaking into gas gathering systems which are operated at subatmospheric pressure, and oxygen in unblanketed amine storage tanks and sumps can react with the amine to form carboxylic acids and with H2S to form elemental sulfur and thiosulfate. In refinery systems, elemental sulfur can then react with cyanide to form thiocyanate. 

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