MEMBRANE GAS ABSORBERS FOR H₂S REMOVAL – DESIGN, OPERATION AND TECHNOLOGY INTEGRATION INTO EXISTING ODOUR TREATMENT STRATEGIES

Abstract

A hollow fibre (HF) polypropylene membrane gas absorber was investigated for the removal of hydrogen sulphide (H 2 S) from gas streams. Gas concentrations between 25-2010 ppmV were fed into the shell side of a membrane module whilst water-NaOH solutions flowed counter-currently in the fibre lumens. The process was effective at removing the H 2 S (96% at G:L ratios up to 50 and pH 13) from the gas phase in a single pass through the membrane at all the concentrations of H 2 S investigated. Analysis of the mass transfer process revealed the rate of transfer to be controlled by the gas phase transfer coefficient with a value between 1 and 25x10-4 m.s-1. The possible integration of a membrane absorber system into existing odour treatment strategies was assessed by comparing the membrane system, based on the experimentally determined mass transfer coefficient, with existing full scale biofiltration plants. The membrane system became economically favourable at gas flow rates lower than 1630 m 3 .h-1 .

Membrane Gas Absorbers for H2S Removal – Design, Operation and Technology Integration into Existing Odour Treatment Strategies

“…Actual hollow fibre membrane costs can vary but normally remain within the range £30-50.m 2 , based on UK location in 2001 . Lang factors for membrane plants of this type are reported in the literature to vary between 1.66 and 2 and combining the two ranges generates a likely range for the cost factor for a membrane absorber plant which lies between 50 and 100 [20]. The membrane option was assessed to be economically favorable when the available cost factor fell below this level.…”

Quantifying the loss of methane through secondary gas mass transport (or ‘slip’) from a micro-porous membrane contactor applied to biogas upgrading

“…The significance of slip to process operation is application specific. For example, in the case of dilute hydrogen sulfide (H 2 S) absorption 51 from air for odour treatment (Jefferson et al, 2005;Esquiroz-Molina et al, In Press), the co-52 solubilisation of the ternary gases nitrogen and oxygen (and low concentration CO 2 ) are not 53 quantified, or considered. However, for biogas upgrading the significance of methane 'slip' is considerable since methane possesses the intrinsic value as the product gas.…”