Absorber regenerator system

Figure 11.5 Wash of absorber-regenerator system where accidents can occur (heavy lines denote path of circulating wash liquid).

Figure 12.6 A typical simplified ammonia plant CO2 absorber-regenerator system.

Feedstock impurities, or chemicals left over in the system from a previous operation, are often the cause of undesirable reactions in columns. Should an undesirable reaction be suspected, it may pay to look into the nature and effects of feedstock impurities, and to attempt deriving plant feedstock from an alternative source for a trial period. If the impurity is chemically unstable, or reacts with the column chemicals explosively, a detonation may result some examples were reported (96, 275). In absorber-regenerator systems, contamination of the solvent charge can lead to imdesirable reactions or poor stripping one example has been reported (14a). 

Reclaiming solvent in an absorber-regenerator system is effective for removing degradation products and solids which promote foaming (84, 238, 239). The reclaimer (Fig. 14.13) is a reboiler, often equipped with a packed wash section, which receives a small portion of the lean solution. It boils off water and solvent and returns them to the process. The liquid portion, containing the sol-... 

Figure 14.13 A t fpical reclaimer installation in an absorber-regenerator system.

The absorber/regenerator system shown on the left of the diagram is conventional, but the additional reabsorber, shown on the right, is not commonly used in amine plants. It serves to selectively remove H2S from the C02-rich vapor stream extracted from the regenerator, concentrating the H2S offgas to a level that can be sent to a Oaus plant. Enrichment schemes such as this have usually been limited to pure physical solvent systems. 

In most plant design situations of practical interest, however, the several pieces of equipment interact with each other, the output of one unit being the input to another that in turn may recycle part of its output to the inputter. Common examples are an absorber-stripper combination in which the performance of the absorber depends on the quality of the absorbent being returned from the stripper, or a catalytic cracker-catalyst regenerator system whose two parts interact closely. 

Design of Absorber-Stripper Systems The solute-rich liquor leaving a gas absorber normally is distilled or stripped to regenerate the solvent for recirculation back to the absorber, as depicted in Fig. 14-3. It is apparent that the conditions selected for the absorption step... 

Spent absorbents regenerate the adsorbent 4d. Solid recovery system... 

The absorption system can be physically separated from the regeneration system if there are space limitations within the plant. Gases from more than one unit can be treated by installing separate absorbers for each sulfur dioxide source, with all the absorbers being supplied by a common regeneration system. 

Feeding solutions from the absorber system and the regeneration system through surge tanks enables the entire recovery process to operate smoothly and reliably despite frequent gas flow and concentration fluctuations. In addition, the surge tanks allow the regeneration section to be shut down for up to 3 days without interfering with the sulfur dioxide removal in the absorption section. This is possible because the absorber is the only part of the system that contacts the flue gas and removes the sulfur dioxide. 

The Benfield Process uses wash liquors containing 25-30 % potassium carbonate and a vanadate additive. As in the case of most hot potash processes, several variants were developed to serve different applications. Split flow systems are used in the absorber and regenerator to remove CO2 down to a level of 0.05 vol. % however, in order to remove CO2 from methanol syngas, the simplest process version consisting of an undivided absorber regenerator loop will do. 

Filters and other absorbing components in helium purification system and its regeneration system as well as ventilation system. 

The stripping column diameter can be determined by the same procedures as used for the absorber. Maddox (1985) provides approxiinate diameter (and hei t or loigth) requirements for the stripping column and other regeneration system vessels as a function of the amine solution flow rate. 

Caustic Regeneration System. The caustic regeneration system consists of an oxidizer tower and a settler. Rich caustic solution from the mercaptan absorber containing mercaptide... 

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