Monsanto injection facility

FIGURE 20.12 Monsanto Injection Facility hydrogeologic cross-section. (From U.S. EPA, Assessing the Geochemical Fate of Deep-Well-Injected Hazardous Waste A Reference Guide, EPA/625/6-89/025a, U.S. EPA, Cincinnati, OH, June 1990.)... 

When calcium carbonate goes into solution, it releases basic carbonate ions (COf ), which react with hydrogen ions to form carbon dioxide (which will normally remain in solution at deep-well-injection pressures) and water. Removal of hydrogen ions raises the pH of the solution. However, aqueous carbon dioxide serves to buffer the solution (i.e., re-forms carbonic acid in reaction with water to add H+ ions to solution). Consequently, the buffering capacity of the solution must be exceeded before complete neutralization will take place. Nitric acid can react with certain alcohols and ketones under increased pressure to increase the pH of the solution, and this reaction was proposed by Goolsby41 to explain the lower-than-expected level of calcium ions in backflowed waste at the Monsanto waste injection facility in Florida. 

Figure 1.8. An example of a deep-well injection facility. Monsanto s facility near Pensacola, Florida, injects acidic waste streams more than 1000 ft deep into the Lower Limestone of the Floridian Aquifer. Observed reactions include dissolution of limestone, reactions among the wastes under higher pressure and temperature, and suppression of microbial activities (Boulding, 1990).

The first conunercial scale membrane installation used with CO2 flood EOR was the Sacroc project in West Texas. Injection of CO2 into the field at volumes up to 200 MM.scfd began in 1972. To handle the anticipated increase in the associated gas CO2 concentration, Sacroc installed three C02-removal facilities. The plants were installed in conjunction with three existing processing facilities operated by Sun Exploration Production Co., Chevron U.S.A., and Monsanto. The Sun and Chevron facilities use the Benfield hot potassium carbonate process, and the Monsanto facility uses the monoethanolamine (MEA) process. The Sun hot potassium carbonate plant was designed to reduce the CO2 content of 160 MMscfd of associated gas from 24 to 0.5% CO2, while the Chevron plant was designed to reduce the CO2 concentration of 46 MMscfd of associated gas from 24 to 1.0% CO2. The Monsanto MEA plant was designed to treat 16.5 MMscfd of the 24% CO2 feed gas, reducing its CO2 concentration to 0.01% (Parro, 1984). 

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See also in sourсe #XX -- [ ]

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