results in polymerization and bigger molecules.These reactions are kept to minimum and some of these compounds tend to go with Acid soluble oil(conjunct polymer).
C 8 H 18 +C 4 H 8 +H 2 C 12 H 28
Alkylation Chemistry Secondary Reactions Cracking Reactions Larger isoalkyl compounds crack to form smaller compounds and olefins, which than can get into earlier mentioned reactions. i-C 12 H 26 i- C 5 H 12 +i-C 7 H 14 or i-C 12 H 26 i-C 6 H 14 + i-C 6 H 12
Hydrocarbon/ Acid mixing is major variable in the alkylation reaction so that all the acid interfacial area is available to olefin and isobutane to react. The eductor device provides this function very efficiently.The OSV is kept in 0.2 to 0.4 1/hr range.
Temperature is another variable which is very important and present RHT configuration, provides the best results due to essentially isothermal conditions (25 -27 F) in the reactor. Higher reaction temperature favors polymerization reactions, which reduces the acid concentration, increases acid consumption, corrosion and reduces the Product Quality/Octane.
Isobutane concentration is kept at the optimum condition I/O ratio of 6 to 15 to provide good product quality and selectivity and still not increasing de-isobutanizer loads. Lower I/O ratio enhances the olefin polymerization, which is not good for quality and increases the acid consumption. Isobutane in Reactor effluent 53 to 75 % by Vol.
Acid concentration is very important for alkylation reaction. At lower acid concentration ASO make increases, product quality goes down. Normal acid concentrations are kept in the range of 89 to 95 %. Concentration below 86 % Acid concentration, activity is decreased, enhancing polymerization, this condition is known as close to acid run away as acid concentration is difficult to control.
Olefin Space Velocity is a Measure of Olefin Volume compared to Acid volume in the reactor. Higher Space velocity enhances the acid consumption and lower product quality. The Volume of acid is optimized in relation to olefin to provide optimum results.
Acid hydrocarbon separation is very important issue. RHT uses Coalescer, so as to remove traces of acid from hydrocarbon. RHT has patented the higher temperature separation/acid settling from the hydrocarbon, which favors the acid settling from the hydrocarbon. Vertical or horizontal coalescers can be used.
OPERATING VARIABLES RHT process reduces all the equipment which is used for neutralization and wash and produces Caustic waste stream. This provides major savings to Capex and also Opex for deleting the requirements for treating the waste stream.
OPERATING VARIABLES RHT The conventional processes use the settling together with neutralization (wet system), which dilutes the acid , produces caustic waste and corrosion problems. Conventional process have reduced acid carry over from settlers by using coalescers. RHT has enhanced that concept to the ultimate with patented temperature for coalescer operation.