Regeneration Processes

Regeneration. The regeneration process is the oldest of the film-forming processes and was used exclusively for the manufacture of... 

Absorber oil units offer the advantage that Hquids can be removed at the expense of only a small (34—69 kPa (4.9—10.0 psi)) pressure loss in the absorption column. If the feed gas is available at pipeline pressure, then Httle if any recompression is required to introduce the processed natural gas into the transmission system. However, the absorption and subsequent absorber-oil regeneration process tends to be complex, favoring the simpler, more efficient expander plants. Separations using soHd desiccants are energy-intensive because of the bed regeneration requirements. This process option is generally considered only in special situations such as hydrocarbon dew point control in remote locations. 

A problem common to produced water appHcations is the tendency for oil fouling of the resin. If weak acid or chelate resins are used, a two-step regeneration process is required which uses acid to remove calcium and magnesium from the resin, foUowed by a dilute NaOH solution to convert the resin to the sodium form. 

Seed Regeneration. The objectives of the seed regeneration program were to provide experimental verification of the feasibiUty of one of the seed regeneration processes which have been selected for first commercial use. The specific process under evaluation was the Econoseed process (Fig. 11) (61). A 5 MW POC facihty was in operation in Capistrano, California, and produced over 6 t of potassium formate seed, which was regenerated from spent seed, ie, K SO, obtained from CFFF tests. 

Regenerable absorption processes have also been developed. In these processes, the solvent releases the sulfur dioxide in a regenerator and then is reused in the absorber. The WelLman-Lord process is typical of a regenerable process. Figure 11 illustrates the process flow scheme. Sulfur dioxide removal efficiency is from 95—98%. The gas is prescmbbed with water, then contacts a sodium sulfite solution in an absorber. The sulfur dioxide is absorbed into solution by the following reaction ... 

Reactions tend to deposit carbon on the catalyst, which ultimately leads to loss of activity. At this stage reactions are stopped, the catalyst purged and regenerated by a controlled oxygenating vapor. AH the vapors from the regeneration process are also passed to the incinerator. A catalyst can undergo many regenerations before replacement becomes necessary. 

Many models have been proposed for adsorption and ion exchange equilibria. The most important factor in selecting a model from an engineering standpoint is to have an accurate mathematical description over the entire range of process conditions. It is usually fairly easy to obtain correcl capacities at selected points, but isotherm shape over the entire range is often a critical concern for a regenerable process. 

A turbine-driven screw compressor might be applied to a catalyst regeneration process. The nature of the process then will require constant volume control to maintain a required output temperature in the regenerator. The arrangement is shown in Figure 8-40(b) and would occur as follows ... 

Liquid Sorption. If a moist gas is passed through sprays of a liquid sorbent, such as lithium chloride or an ethylene glycol solution, moisture is removed from the air at a rate depending on the vapor pressure difference. This is a function of the absorbent concentration and is maintained at the required level by a regeneration cycle. The regeneration process is continuous and is achieved by allowing a percentage of the chemical into the exhaust-heated air. 

I he intermittent operation used in the above method is time-consuming the undesirable effects are overcome by rhe use of a continuous regeneration process, as shown in Fig, 9.19. 

NOTE Periodic cleaning of softener resin with an iron stripping formulation based on phosphonate or a terpolymer is useful. The cleaner is introduced into the resin bed, perhaps via the brine draw during resin regeneration, at a level of, say, 1 to 2 U.S. pints/cuft (16-32 ml/l) of resin. The regeneration process is temporarily halted for several hours and the resin is allowed to soak the process is then restarted and the stripped iron goes to drain. 

Part of a softener regeneration process whereby the cation ion exchange resin is converted to the sodium form by the application of a, typically, 10 to 15% W/V strength of brine (sodium chloride). 

Figure 2 summarizes the individual steps in the proposed hybrid system showing the obtained reduction in normalized concentration (MF, UV, and NF) effluent. Figure 2 illustrates the concept of customized regeneration process according to the reuser needs. 

Figure 261 shows the absorption and the regeneration process schematically. During Absorption the concentrated salt solution is distributed over an exchange surface, which is in contact with an air stream. The air will be dehumidified and the salt solution will be diluted by the absorbed water vapour. During regeneration the diluted solution becomes concentrated again by desorption from a hot air stream. 

Recovery techniques are treatment methods used for the purpose of recovering or regenerating process constituents, which would otherwise be discarded. Included in this group are5-7... 

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