Air Separation Units

Chemical Conversion. In both on-site and merchant air separation plants, special provisions must be made to remove certain impurities. The main impurity of this type is carbon monoxide, CO, which is difficult to separate from nitrogen using distiHation alone. The most common approach for CO removal is chemical conversion to CO2 using an oxidation catalyst in the feed air to the air separation unit. The additional CO2 which results, along with the CO2 from the atmosphere, is then removed by a prepuritication unit in the air separation unit. 

X 10 m (l.9x lO " /t ) of heHum in each cubic meter (35 ft ) of air entering the air separation process, the small quantities of cmde coUected in even a large air separation unit may be easily appreciated. It is sometimes desirable, therefore, to combine cmdes coUected from several air plants and to process them at a centralized location in specialized equipment. 

Minimum water velocities should be maintained in the upper floors of high-rise buildings where air may tend to come out of solution because of reduced pressures. High velocities should be used in down-return mains feeding into air-separation units located at a low level in the system. Table 27.10 can be taken as a guide. Water velocities shown in Tables 27.9 and 27.10 are indicative parameters only on the one hand, to limit noise problems and... 

They used a Ni-containing catalyst. In contrast to steam reforming of methane, methane partial oxidation is exothermic. However, the partial oxidation requires pure oxygen, which is produced in expensive air separation units that are responsible for up to 40% of the cost of a synthesis gas plant (2) (in contrast, the steam reforming process does not require pure oxygen). Therefore, the catalytic partial oxidation of methane did not attract much interest for nearly half a century, and steam reforming of methane remained the main commercial process for synthesis gas manufacture. 

Air separation industry, U.S., 27 754 Air-separation plants, 27 359, 750-751 Air-separation units, krypton and xenon recovery from, 2 7 362 Air-slaked lime, 15 26 Air slaking, 25 43 Air sparging... 

Siemens Power Generation is a partner with ConocoPhillips and Air Products and Chemicals, Inc., (APCI) to develop large-scale fuel cell systems based upon their gas turbine and SECA SOFC technologies. The design will use an ion transport membrane (ITM) oxygen air separation unit (ASU) from APCI with improved system efficiency. 

Oxygen-blown gasifiers yield a moderate heating value product gas (approximately 9MJ/m3) and can operate at very high temperatures, but suffer from the significant cost of producing oxygen with an air-separation unit. 

Steam generated in the bottoming cycle is utilized in a reheat turbine to produce 118 MWe, as well as to supply the steam required by the air separation unit (ASU) and the gasifier coal slurry heater. The cycle exhaust exits the heat recovery steam generator at 126°C (259°F) and 0.98 atmospheres. 

Dehydration is applied to natural gas, air for feed to air separation units, cracked gas (e.g., ethylene), various other hydrocarbon streams just to name a few. Zeolite molecular sieves play a major role in dehydration because of their abihty to reduce moisture content to very low levels attaining dew points of —100°C or lower. 

Practical concerns, specifically mass transfer, Umit the recovery to values in the high 70% range. All this said, the vast majority of operating air separation units are the small capacity medical oxygen concentrators. These operate under either PSA or VSA or trans-atmospheric process cycles. The key objective for medical O2 is small unit size and power consumption prior to the push for portability was a secondary consideration. There are many such PSA air separation units that operate at recoveries as low as 35%. 

Even in more conventional PSA dehydration zeolites including types A, X and Y have aU been employed in pressure swing drying. Compound beds of alumina and zeoUtes X or Y have been employed for PSA dehydration and CO2 removal for pre-purification of feed to air separation units. 

Recent studies have addressed the combustion of natural gas with pure oxygen, highly diluted with exhaust gases (CO2 and H2O) in order to mitigate both NO and CO2 emissions from power plants. The so-called oxy-fuel combustion includes an air separation unit, which delivers O2 to the catalytic stage, where it is mixed with natural gas and the exhaust recycle stream. An example is the Advanced Zero Emission GT, first jointly studied by Norsk Hydro and ABB Alstom Power [28-31]. 

Although a number of air separation units, other than as shown by Fig. 1, were reported by our client to be available and trialled, none were reported as being able to adequately remove the entwined synthetic fibre from the steel fibre to release the rubber product, and separate the synthetic fibre from the steel fibre. 

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