Semi-regenerative units

The design frequency of regeneration is normally from three to six months for semi-regenerative units, and one reactor every 24 hours in cyclic units. For either case, an increase in regeneration frequency would result in a reduction in average catalyst coke level. Thus, gasoline yields would increase and catalyst requirements decrease. 

A low pressure semi-regenerative unit provides yields that approach those obtained in cyclic Powerforming but with savings in investment. For smaller units and moderate severities, the low pressure semi-regenerative unit would likely be the most attractive alternative if selectivity improvement credits are sufficiently high. 

Hydroprocessing extensive use of extrudates and occasionally of spheres Reforming use of extrudates (semi-regenerative units) and spheres (CCR types of units)... 

Process temperature and pressure data for each transfer line and their variation with time, particularly start and end of run on semi-regenerative units. 

Aside from the above reforming reactions, a small amount of feed components are converted to polymeric hydrogen deficient products which deposit on the catalyst as "coke." A coke buildup results in activity and selectivity loss which ultimately requires catalyst regeneration. In semi-regenerative operation, the coking rate is maintained at a low level to provide cycles of at least three to six months. In cyclic units, coking conditions are inherently much more severe so that frequent regenerations are required. 

Powerforming is a version of the platinum reforming process. Basically there are two types of unit semi-regenerative and cyclic. The choice of unit and the exact process conditions used will depend to a large extent on the particular application. However, certain generalizations regarding each of the two types can be made. 

In many processes, regeneration occurs by shutting down the unit and regenerating the catalyst (Semi-regenerative). Figure 3-5 shows a Chevron Rheiniforming semiregenerative fixed three-bed process. 

In March 1937, a 15,000 barrel per day Houdry unit shown in Figure 4 was started up in Paulsboro, New Jersey using Houdry s semi-regenerative process. This process incorporated innovations new for his day including a molten salt heat control technique as well as motor control operated valves with timers. By 1943, 24 Houdry units were on stream or under constmction charging a total of 330,000 barrels per stream day (//). 

After choosing a representative kinetic model, we must decide how to represent the remaining units for a truly integrated model. Researchers have applied many of the kinetic networks described in the previous section in integrated process models. Figure 5.8 is an overview the key features of an integrated process model for a three-section reformer. This overview applies to both semi-regenerative fixed bed and CCR reformers. 

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