Carbon dioxide solubility pump

A cylindrical extractor, 1-m long, is filled with crushed-vegetable-oil seeds. The oil is to be extracted with pumping supercritical carbon dioxide at a density of 500 kg/m3 through the packed bed. The estimated solubility of the oil in the dense gas at this density is 3.425 kg/m3. The superficial velocity of the carbon dioxide in the bed will be 1 mra/s. This fluid velocity is sufficiently small for the fluid to become saturated with oil. We are required to estimate the minimum time of operation for complete extraction of the oil from the bed. The initial oil fraction is 12% (wt/wt) based on wet seeds, the void fraction of the bed is 40%, and the density of the particles is 900 kg/m3. 

For cross country lines containing oil or gas, the corrosive constituents such as water, carbon dioxide, and hydrogen sulfide are usually reduced to a very low level before the fluid enters the line. The lost efficiency required to pump the unwanted constituents and the extra wall thickness required for corrosion allowance usually cannot be economically justified. Even with cleanup systems, some water will get into pipelines. In oil lines, oil soluble corrosion inhibitors usually prevent attack by water settling in low spots, etc. Gas lines are usually dehydrated to 60% of saturation to avoid corrosion from condensing water containing dissolved carbon dioxide. Molecular sieves that reduce water to 5 ppm have proved necessary in lines containing 100% carbon dioxide. 

For flow through porous media studies, the sandpacks used as porous media were flushed vertically with carbon dioxide for an hour to replace interstitial air. Distilled water was pumped and the pore volume (PV) of the porous medium was determined. By this procedure, the trapped gas bubbles in the porous media can be easily eliminated because carbon dioxide is soluble in water. For determining the absolute permeability of the porous medium, the water was pumped at various flow rates and the pressure drop across the sandpack as a function of flow rate was recorded. After the porous medium was characterized, the mixed surfactant solutions of known surface properties were injected. This was followed by air injection to determine the effect of chain length compatibility on fluid displacement efficiency, breakthrough time and air mobility in porous media. 

Characterization of Porous Media Several sandpacks and sandstones (1 ft. long) were used as a porous medium for displacement experiments. The porous medium was flushed with carbon dioxide to replace interstitial air. To determine the pore volume of the porous media, several pore volumes of distilled water were pumped through it. By this method, the trapped gas bubbles in the porous media could be eliminated because carbon dioxide being soluble in water. The water retained in the porous medium was calculated for determining the pore volume. Moreover, water was also pumped through the porous medium at several flow rates to determine the absolute permeability of the porous medium... 

This is not to imply that he finished his religious activity. Soon he got a post in a congregation in Leeds. There his house happened to be next door to a big brewery. He had carbon dioxide gas, fixed air, within easy reach. He started to carry out experiments with gases and found that some have greater solubility in water than others. If he were to measure the volume of a soluble gas, he could not collect it over water. Instead, as he had learnt from Henry Cavendish, he had to collect it over mercury. Carbon dioxide in contact with water was interesting for another reason. At high pressure (as mentioned, he owned an air pump) the gas dissolved considerably in water. The water got a refreshing taste and he recommended the drink to his friends. 

In a can of soda pop and at the bottom of Lake Nyos, carbon dioxide is maintained in solution by high pressure. In soda pop, the pressure is provided by a large amount of carbon dioxide gas that is pumped into the can before sealing it. When the can is opened, the presstrre is released and the solubility of carbon dioxide decreases, resulting in bubbling (T Figure 13.6). The bubbles are formed by the carbon dioxide gas as it escapes. In Lake Nyos, the pressure is provided by the mass of the lake... 

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