Schematics continuous catalyst regeneration

Periodic catalyst regeneration or carbon burn off is required to maintain the activity of the catalyst. Typical cycle time is reported to be at least 8 hr, with 7 hr of process time and 1 hr of regeneration time. For continuous operation, various furnace modules can be operated such that, for example, seven operate in the process mode while one is in the regeneration mode. Fig. 13 shows a schematic diagram of a STAR process unit. ... 

In a typical fluid catalytic cracker, catalyst particles are continuously circulated from one portion of the operation to another. Figure 9 shows a schematic flow diagram of a typical unit W. Hot gas oil feed (500 -700°F) is mixed with 1250 F catalyst at the base of the riser in which the oil and catalyst residence times (from a few seconds to 1 min.) and the ratio of catalyst to the amount of oil is controlled to obtain the desired level of conversion for the product slate demand. The products are then removed from the separator while the catalyst drops back into the stripper. In the stripper adsorbed liquid hydrocarbons are steam stripped from the catalyst particles before the catalyst particles are transferred to the regenerator. 

A schematic of a monolith catalyst is shown in Fig. 19-18a. In cases where pressure drop is limiting, such as for CO oxidation in cogeneration power plant exhausts, monolith catalyst panels may be stacked to form a thin (3- to 4-in-thick) wall. The other dimensions of the wall can be on the order of 35 x 40 ft. CO conversion is over 90 percent with a pressure drop across the catalyst of 1.5 in of water. Alternatively, the monolith may be used as a catalyst and filter, as is the case for a diesel particulate filter. In this case, monolith channels are blocked and the exhaust gases from a diesel truck are forced through the walls (Fig. 19-18b). The filter is a critical component in a continuous regenerable trap. NO in the exhaust... 

Figure 15.16 Schematic of Reentech continuous regeneration of the catalyst which supplies freshly activated catalyst to the cracker. (Courtesy of Reentech, Korea)...

Figure 7 Simplified schematic diagram of a continuously regenerating trap (CRT). The platinum catalyst oxidizes hydrocarbons and carbon monoxide, and also nitric oxide to nitrogen dioxide, which is used to oxidize soot retained in the filter. In the illustration this is a ceramic-wall flow filter, which has alternate channels blocked at the front inlet and rear outlet faces.

MTO was first scaled up in MRDC s 4 B/D fluid-bed pilot plant in Paulsboro, New Jersey. Following successful completion of the 100 B/D MTG project, the project was extended, and the plant modified to demonstrate MTO (refs. 16, 17). The plant is shown schematically in Fig. 4. Methanol is converted in a turbulent fluid bed reactor with typical conversions exceeding 99.9%. The products are recovered in a simple gas plant. Coked catalyst is continuously withdrawn from the reactor, and the coke is burned in a fluid-bed regenerator. Coke yield and catalyst circulation are an order of magnitude lower than in fluid catalytic cracking. 

Additives must rapidly absorb sulfur dioxide and trioxide as it is produced during catalyst regeneratiom The resulting sulfate is then reduced in the reactor and stripper to regenerate the additive and continue the cycle. The reactions taking place are shown schematically in Table 5.14. 

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