Catalytic startup

Most sulfonation plants monitor and control operations by computer. Sulfur-buming catalytic SO -generating equipment may require a 1—2 h stabilization period on startup. The unit can be kept in a standby position by maintaining heat to the unit when it is off-line. Liquid SO -based sulfonation plants do not require such a stabilization period and hence are more flexible to operate than sulfur-buming sulfonation plants. 

These activities may introduce many hazards, such as contaminants, materials of repair corrodible, combustible or catalytic in the given environment, blocked vents, open valves etc. into the restarted plant, while shutdown and startup are, in any event, the most dangerous periods. Many examples of reactive hazards thus introduced are to be found in [1], Mutatis mutandis, this is also true of the laboratory this Handbook contains many incidents consequent upon stopping a reaction and/or its agitation to sample, change cooling bath, etc. 

Considerable research and engineering are being devoted to improving the performance of the automotive catalytic converter to reduce emissions that occur during startup. 

In 1987, the successful startup of a new process was announced for the production of 10,000 tons/year of catechol and hydroquinone by the selective oxidation of phenol with H202 catalyzed by TS-1 at the Enichem plant in Ravenna, Italy (Notari, 1988). Soon thereafter, it was disclosed that another new process for the production of cyclohexanone oxime from cyclohexanone, H202, and NH3 with TS-1 as the catalyst was being developed (Roffia et al., 1990).The fact that a material with unusual catalytic properties had been obtained was then finally recognized, and the interest in titanium-containing catalysts spread rapidly in the scientific community, especially in industrial research laboratories. In the meantime, the synthesis method was studied and described in more detail and when all the necessary precautions were taken, TS-1 was reproduced in other laboratories, as were the highly selective catalytic reactions. The subsequent work confirmed that Ti v can assume the tetrahedral coordination necessary for isomorphous substitution of SiIV and added valuable information about the structure, properties and catalytic performance of the material. New reactions catalyzed by TS-1 have been discovered, and new synthetic methods... 

A tragic explosion and fire occurs in a fluid catalytic cracking unit during a startup after a turnaround when superheated oil is allowed into a vessel that had accidentally accumulated water. 

Multisolids Fluidized Bed Catalytic High Pressure No Oxygen Requi red 2 ODT/D Wood-whole tree-Chips and Residues 1BG (<350 BTU/scf) or Methane Larger units, energy farms (300-1,500 ODT/D) PDU designed startup mid 1980... 

In this case, the stoichiometric and catalytic reactions develop simultaneously. The first ensures startup, and the second subsequently predominates, so that only 20 to 30 per cent of the carbon monoxide consumed is obtained from nickel carbonyl, with the rest supplied by make-up CO. The overall conversion is written ... 

However, the parameter estimates in Figures 9.1 and 9.2 and Equations 9.6 and 9.7 were developed for random packing, and even the boundary condition of Equation 9.4 may be inappropriate for monoliths or structured packing. Also, at least for automotive catalytic converters, the pressure drop and the transient behavior of the reactor during startup is of paramount importance. Transient terms da/dt and dT/dt are easily added to Equations 9.1 and 9.3, but the results will mislead. These... 

From the literature analyzed, it is possible to conclude that on the bifunctional naphtha reforming catalysts, mono or bimetallic, at the startup of the operation there is a lineout period in which coke is rapidly deposited on the metal function. This produces a decrease in metal catalytic activity for reactions kinetically... 

Since the delay found in references [4] and [12] concerned the start-up of the whole oxidation plant that included a multi-pass catalytic reactor, the simulations were carried out using the model of the whole plant comprising not only the reactor itself, but also the installations for the recovery of the heat of reaction. For the assumed values of the startup was simulated from the state in which the installation was thoroughly cooled down. The SO2 concentration transients at the outlet of the reactor are shown in Fig. 3. 

One of the concerns with bulky reactors is the time taken to start up the reactor. Startup involves bringing the temperature of the essential components to the required level to kick off the reaction kinetics, supplying the required fuel to the reactors, and ensuring durable operation where all the reactors work seamlessly. In conventional systems, a large number of units need to be brought up in temperature before activating the reactions. In the case of a membrane reactor-based FPS, the catalytic partial oxidation (CPO) reformer, vaporizers, and membrane reactor need to be brought up in temperature. 

Many fixed-bed industrial reactors operate adiabatically, and the temperature profiles can be used to follow changes in catalytic activity and to optimize reactor performance. The temperature profile for an exothermic reaction is similar to the temperature-time curve for a batch reaction. The energy released by reaction is carried out by the fluid, since, except for startup, there is no accumulation in the catalyst. The conversion at any distance from the inlet can be calculated from the temperature rise relative to that for complete conversion. 

The literature on FLC has been growing rapidly in recent years, making it difficult to present a comprehensive listing of the wide variety of applications that have been made. Among these are an experimental warm-water plant [65], temperature control of stirred tank reactor [66], activated sludge wastewater treatment process [67], cement kiln [68,69], and startup of catalytic reactor [70]. In drying applications, FLC systems have been developed for simulated rotary dryers [71-73], deep-bed grain and food dryers [74-76], fluidized-bed dryers [77,78], and drum dryers [79]. 

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