Film reactors

Model Reactions. Independent measurements of interfacial areas are difficult to obtain in Hquid—gas, Hquid—Hquid, and Hquid—soHd—gas systems. Correlations developed from studies of nonreacting systems maybe satisfactory. Comparisons of reaction rates in reactors of known small interfacial areas, such as falling-film reactors, with the reaction rates in reactors of large but undefined areas can provide an effective measure of such surface areas. Another method is substitution of a model reaction whose kinetics are well estabUshed and where the physical and chemical properties of reactants are similar and limiting mechanisms are comparable. The main advantage of employing a model reaction is the use of easily processed reactants, less severe operating conditions, and simpler equipment. 

M. BaUestia and G. Moietti, High Quality Surfactants from SO Sulphonation with Mu/ti-tuhe Film Reactors, Chimicaoggi, LugHo, Italy, 1984, p. 41. 

In the fixed-film reactor, the organisms grow on an inert surface that is maintained in the reactor. The inert surface can be gramJar material, proprietary plastic packing, rotating discs, wood slats, mass-transfer packing, or even a sponge-type material. The reacior can be flooded or have a mixed gas-hquid space (Fig. 25-52). The biomass level on the... 

An illustration of a fixed-film reactor system is presented in Figure 24. 

Residuals Produced The residuals produced in a fixed-film reactor are normally small when compared to the residuals produced in a suspended growth system. There can be some sloughing of biomass during system ojjerations, and this may need to be separated from the effluent. The residuals, depending on site-specific requirements, may require additional treatment prior to ultimate disposal. 

Technology Description Hybrid reactors, as the name implies, are a combination of suspended growth and fixed-film reactor principles. In these systems, the fixed film is submerged and the reactor contents are continuously stirred. A large amount of biomass is maintained in the system. 

Gas-liquid contactors may be operated either by way of gas bubble dispersion into liquid or droplet dispersion in gas phase, while thin film reactors, i.e. packed columns and trickle beds are not suitable for solid formation due... 

With a reaction enthalpy of A RH = -170 kJ/g mol the sulfonation with S03 is strongly exothermic. As the color of the acid is dependent not only on the residence time but also to a considerable extent on the reaction temperature, it is necessary to have an effective thermal dissipation. This applies to all of the reactors listed in Table 13. The falling film reactors, of which there are various designs, have the advantage that a very short residence time can be realized [152]. 

As a rule, sulfonation takes place continually in a cascade or a falling film reactor (Table 14) at about 50-70°C. The S03 is steadily diluted to a concentration of 5-10 vol % with air or an inert gas. The LAB conversion reaches a value between 92% and 98% [156,157]. Mixing of the already formed alkyl-benzenes with fresh S03 leads to undesired highly sulfonated byproducts. In order to prevent these side reactions, all processes operate concurrently. 

The process is shown schematically in Fig. 1. During the first stage of the process, a-olefins are sulfonated with diluted S03 gas in a falling film reactor. The optimum molar ratio of S03/olefin varies from 1.0 to 1.2. As the sulfonation reaction is very rapid and exothermic, the reaction temperature can rise to... 

In summary, mild sulfonation of detergent range 10 in a falling film reactor followed by direct neutralization and hydrolysis leads to an IOS system rich in sodium p-hydroxysulfonates and having low concentrations of residual sul-tones, inorganic sulfate, and free oil. 

The thin film reactor for the continuous sulfonation of fatty acid esters was introduced by the Witco Technical Center in Oakland, New Jersey [46]. Hurl-bert et al. designed this type of reactor for small-scale sulfonation with S03 [47,48]. The reaction partners could be filled into the reactor through three inlets. One was for the carrier gas (air or nitrogen), one for the liquefied ester that is picked up from the carrier gas, and the last one was for the vaporized S03. The ester and the S03 reacted in a turbulent liquid film. Details of this reactor are given by Kapur et al. [46]. 

Reaction time (short residence time falling film reactors are required to attain top quality anionic surfactants)... 

The Ballestra Sulfurex multitube falling film reactor (MTFFR)... 

The Meccaniche Moderne monotube falling film reactor... 

Neutralization of organic acid within 1 min after sulfonation reactor. A separate aging step is not needed under commercial reactor conditions Short residence time falling film reactor required to avoid thermal breakdown of R0S03H... 

Falling film reactor system Mole ratio S03/Me-ester 1.2 1... 

Reaction temperature in short residence time reactor 90°C, cooling water — 80-85°C in lower part and 40-50°C in upper part Aging reactor post-falling film reactor required residence time 0.5 h at 90-95°C, plug flow conditions... 

Sulfonation of the common feedstocks proceeds with a highly exothermic instantaneous initial reaction, followed by a fast but not instant step that is also highly exothermic. The second reaction does not always proceed to completion (e.g., LAB, FAME) in the lower zone of a short residence time falling film reactor (FFR). For these organic feedstocks aging under well-defined conditions of temperature and reaction time is required. 

The detergent industry requires process equipment having high operation flexibility, low energy demand, low operation cost, consistent production yield, and, of course, ecological optimization with respect to effluents and air pollution control. To comply with these requirements, the continuous S03/gas sulfonation and double-step neutralization are the basic principles applied in multitube falling film reactor and Neutrex neutralization (Fig. 5). 

The gaseous S03 stream (previously diluted with dry air to a concentration ranging from 7% to 2.5% volume) is then fed to the sulfonation/sulfation section which is based on a multitube falling film reactor having a number of tubes proportional to the plant production capacity (Figs. 8 and 9). The S03 gas is fed to the upper part of the reactor and distributed equally to each reaction tube. 

The mass flow of organic feedstock to the film reactor is detected and adjusted by a mass flow meter, which automatically controls the speed of the gear pump feeding the organic to the reactor. 

Henriksen HV, S Larsen, BK Ahring (1991) Anaerobic degradation of PCP and phenol in fixed-film reactors the influence of an additional substrate. Water Sci Technol 24 431 36. 

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