Microbially-Enhanced Redox Solution Reoxidation for Sour Natural Gas Sweetening

Kenneth Brezinsky

关键词: ATMOSPHERIC PRESSURE;    BACTERIA;    BIOMASS;    CATALYSTS;    CHELATES;    DILUTION;    DISTURBANCES;    ECONOMICS;    FEEDBACK;    IRON;    KINETICS;    MICROORGANISMS;    NATURAL GAS;    OXIDATION;    PACKED BEDS;    REGENERATION;    REMOVAL;    SULFUR;    TANKS;    WASHOUT;   

DOI  :  10.2172/972637
RP-ID  :  None
PID  :  OSTI ID: 972637
Others  :  TRN: US201005%%329

美国|英语

来源: SciTech Connect

【 摘 要 】

The specific objective of this project are to advance the technology and improve the economics of the commercial iron-based chelate processes such as LO-CAT II and SulFerox process utilizing biologically enhanced reoxidation of the redox solutions used in these processes. The project is based on the use of chelated ferric iron as the catalyst for the production of elemental sulfur, and then oxidizing bacteria, such as Thiobacillus Ferrooxidans (ATCC 23270) as an oxidizer. The regeneration of Fe{sup 3+} - chelate is accomplished by the use of these same microbes under mild conditions at 25-30 C and at atmospheric pressure to minimize the chelate degradation process. The pH of the redox solution was observed to be a key process parameter. Other parameters such as temperature, total iron concentration, gas to liquid ratio and bacterial cell densities also influence the overall process. The second part of this project includes experimental data and a kinetic model of microbial H{sub 2}S removal from sour natural gas using thiobacillus species. In the experimental part, a series of experiments were conducted with a commercial chelated iron catalyst at pH ranges from 8.7 to 9.2 using a total iron concentration range from 925 ppm to 1050 ppm in the solution. Regeneration of the solution was carried out by passing air through the solution. Iron oxidizing bacteria were used at cell densities of 2.3 x 10{sup 7}cells/ml for optimum effective performance. In the modeling part, oxidation of Fe{sup 2+} ions by the iron oxidizing bacteria - Thiobacillus Ferrooxidans was studied for application to a continuous stirred tank reactor (CSTR). The factors that can directly affect the oxidation rate such as dilution rate, temperature, and pH were analyzed. The growth of the microorganism was assumed to follow Monod type of growth kinetics. Dilution rate had influence on the rate of oxidation of ferrous iron. Higher dilution rates caused washout of the biomass. The oxidation rate was highly pH sensitive. Specific growth is a function of pH of the both. The specific growth rate had a maximum value at around 2.2. A dynamic model for a packed bed fluid reactor is also developed and simulated. A feedback control loop is proposed to control the production under feed disturbances.