Ethylene pipeline system

In Europe and North America most polyethene plants take their feedstocJc from a common ethylene pipeline system that provides ethylene of a quaUty that is suffi-dent for all different polymerization processes. Table 6.20.2 gives the specification for sucdi polymerization-grade ethene. 

The quantity of ethylene transported by international tankers accounts for only 1% of production. The majority of ethylene produced in the United States and Western Europe is moved by integrated pipeline systems. 

Gas-phase process, of ethylene-propylene polymer manufacture, 10 711 Gas-phase reactions flow mixing for, 14 613 pressure and, 14 623 Gas-phase reactor (GPR), 20 533 Gas-phase sedimentation, 18 142 Gas-phase synthesis, in silicon carbide manufacture and processing, 22 533 Gas pipeline systems, 12 366 Gas pretreatment, 13 841 Gas processing, in petroleum refining, 18 663... 

Gas streams with relatively higher natural gas liquid components require the removal of these liquids prior to entering the natural gas pipeline system, but these natural gas liquids require a distribution system in order for particular products to reach a market. For ethylene manufacture, ethane is the important feedstock. Distribution bottlenecks will affect the market price of natural gas liquids. In the United States, for example, the shale gas revolution has provided tremendous growth in the ethane business. Ethane is the preferred feedstock for the petrochemical industry to manufacture... 

Liquid Hazards. Pure liquid ethylene oxide will deflagrate given sufficient initiating energy either at or below the surface, and a propagating flame may be produced (266,267). This requites certain minimum temperatures and pressures sensitive to the mode of initiation and system geometry. Under fire exposure conditions, an ethylene oxide pipeline may undergo internal decomposition either by direct initiation of the Hquid, or by formation and subsequent decomposition of a vapor pocket (190). 

The techniques used in the preparation of a stable oil-in-water emulsion for pipeline transportation are illustrated by the results of a field test in which an Athabasca bitumen was emulsified and pumped through a 3-in. x 4000-ft. pipe-loop system for a total distance of approximately 500 miles. The emulsion in this case comprised 75% by weight of the 8.3 API bitumen and 25% of a synthetic brine containing 1.7% NaCl. (API gravity is defined in the Glossary.) The surfactant used was a mixture of two ethoxylated nonylphenol surfactants the first component contained an average of 40 ethylene oxide units per molecule, and the second component contained 100 units. Approximately 1500 ppm of the surfactant mixture, based on the total... 

In a facility scheme that appears quite complex, only a few formulae suffice to illustrate where in the system the few chemical reactions take place. Often, polymers are produced on the basis of monomers as delivered without further chemical transformations. The monomer is supplied by a large petrochemical plant located many kilometers away near a refinery. Ethylene is transported in Europe in a special pipeline along the Rhine. Propylene and other raw materials for polymerization processes are transported in tanks by road, rail, and ship. 

It is possible that the natural gas can react with water to form solid hydrates in the pipeline. If this happens the pipe will be blocked with solids. For this reason, hydrate inhibitors such as glycol or methanol, are injected into the sub-sea system. The process described here uses ethylene glycol (MEG) as a primary inhibitor and methanol as a backup inhibitor. MEG is recovered from the system in the onshore facilities, but methanol is discharged with the produced water. 

Feed ethylene is normally delivered to the plant by a pipeline grid or directly from a cracker on the same site. As the process is highly sensitive to impurities, sulphin compoimds, acetylene and other impurities are removed from the feed ethylene by purification beds. The cleaned feed ethylene is then compressed to the required reaction pressure and enters the reactor loop at the bottom of the reactor. A metal oxide catalyst, alinniniinn alkyl in hydrocarbon as a cocatalyst, lower olefins as comonomers and other auxihary chemicals are fed directly into tire reactor loop. Typically, different product types can be produced by selecting the catalyst system, the comonomers and the reaction conditions. 

---