Air, liquefied

Colorless gas pungent suffocating odor density 2.975 g/L fumes in moist air liquefies at -101°C sohdifies at -126.8° vapor pressure at -128°C is 57.8 torr critical temperature -12.2°C critical pressure 49.15 atm critical volume 115 cm3/mol soluble in water with partial hydrolysis solubdity in water at 0°C 332 g/lOOg also soluble in benzene, toluene, hexane, chloroform and methylene chloride soluble in anhydrous concentrated sulfuric acid. 

Colorless, odorless gas density 6.41 g/L about five times heavier than air liquefies at -50.7°C (triple point) density of liquid 1.88 g/mL at -50.7°C sublimes at -63.8°C critical temperature 45.54°C critical pressure 37.13 atm critical volume 199 cm /mol slightly soluble in water soluble in ethanol. 

The process of compression followed by expansion is repeated until the air reaches a temperature below -200 °C. At this temperature the majority of the air liquefies (Table 11.3). 

The cooled, compressed air passes through a nozzle into a chamber of larger diameter called an expansion valve. As the air passes through the valve, it expands and cools. (This cooling effect was first described by James joule and William Thomson and is called the joule-Thomson effect.) The temperature difference is so great that the air liquefies. 

Colorless gas with an odor of rotten eggs sweetish taste fumes in air liquefies at -60.2°C (-76.36°F) freezes at -85.5°C (—121.9 F) slightly soluble in water (0.4% at 20°C/68°F) pH of a saturated aqueous solution is 4.5 aqueous solution unstable, absorbs oxygen, decomposes to sulfur, and the solution turns turbid. 

Colorless gas fuming strongly in air liquefies at —85°C (—121°F) solidifies at —95°C (—139°F) density of gas 5.8 g/L reacts with water, soluble in carbon disulfide and carbon tetrachloride. 

Colorless gas with a pungent suffocating odor at high concentrations sweet odor of moldy hay at low concentrations in air liquefies at 8°C (46.4°F) density 1.432 at 0°C (32°F) solidifies at 118°C (244.4 F) slightly soluble in water, reacting slowly soluble in hexane, isooctane, benzene, toluene, and glacial acetic acid. 

With both Air Liquide and Gesellschaft fur Linde s Eismaschinen s air liquefiers well established, the European cryogenic industry was launched. Further, their competition stimulated intense technical development that rapidly improved the state of cryogenic technology. However, attempts to produce high-purity oxygen took longer to reach fruition. 

An even more important step from today s perspective was the liquefaction of air by Carl von Linde, marking the birth of an entirely new industry. C. v. Linde employed the Joule-Thomson effect, decreasing the temperature of the gas by adiabatic expansion. In 1895, he achieved continuous generation of Uquid air at a yield of three litres per hour using a laboratory plant [1.1], The following years saw the construction and delivery of the first small commercial air liquefaction plants. Figure 1.1 shows a typical early air liquefier (ca. 1899). 

The specific energy requirement for the liquefaction is typically 0.6-0.7 kWh m[], and is significantly lower than the 2.7 kWh of the first air liquefiers built... 

In adopting the Norelco air liquefier for recondensing flash gases, it was necessary to make a number of modifications... 

The early concepts of Kirk and Stirling in which a reciprocating-flow thermal regenerator is used in place of a countercurrent heat exchanger have recently been refined and developed effectively into an air liquefier by the Philips Company [10]. The system is characterized by the use of two articulated pistons which provide a compression space and an expansion space, interconnected through a thermal regenerator. Unlike the Kapitza or Collins system, there are... 

In the past, temperatures below -100 C have been produced primarily via the liquefaction of gases with a low boiling point. Recently the available arsenal of liquefaction apparatus has been augmented by the introduction by the Philips Company of the gas refrigerating machine employing the Stirling cycle, in its first version of an air liquefier [1]. 

The Philips air liquefier, based on the Stirling cycle, is an attempt to provide a very simple and small installation. This simplification is obtained by removing all the heat at the lowest temperature only, in contrast with conventional tech-... 

Determine the fraction of air liquefied in a simple Linde cycle if the inlet conditions on the warm side of the two-channel heat exchanger are 310 K and 20.2 MPa while the exit conditions are 303 K and 0.101 MPa. Repeat the calculations for inlet conditions of 208 K and 20.2 MPa with exit conditions of 200 K and 0.101 MPa. 

MPa and 288 K. The low pressure air stream leaves this same heat exchanger at 0.101 MPa and 288 K. All the heat leak into this liquefaction system may be considered to be intercepted by the reservoir containing liquid air at the intermediate pressure. The heat leak is 7.25 kJ/kg of high pressure air. Determine the fraction of air liquefied per unit mass of gas compressed at 20.2 MPa when 80 % of the gas compressed is returned in the intermediate pressure air stream. Also determine the work required to liquefy a kilogram of air assuming the air, initially at 0.101 MPa and 293 K, is compressed polytropically to... 

Example 5.6. A countercurrent flow heat exchanger in a simple Linde air liquefier cools a high-pressure 20.2-MPa gas stream from 300 K to an exit temperature of The low-pressure 0.101 MPa gas stream is warmed from 82 K to a temperature of 7. The mass flow rate of the warm stream is 1.0 kg/s, while the mass flow rate of the cold stream is 0.95 kg/s. The average heat capacity of the hot fluid and the cold fluid may be assumed to be constant over the temperature ranges encountered and are 1,599 kJ/kg K and 1.013 kJ/kg K, respectively. If the overall heat transfer coefficient for this 50-m heat exchanger is assumed constant at 110 W/m K, determine the effectiveness of the heat exchanger, exit temperatures for the two fluids, and the heat-transfer rate for this exchanger. 

Example 5,16. Consider the Claude air liquefier described in Example 4.11. Derive a general expression to obtain the liquid yield if the heat exchangers have an effectiveness less than 100%, the expander has a thermodynamic efficiency less than 100%, and the compressor has an efficiency less than 100%. Evaluate what that liquid yield... 

Solution. Figure 4.12a can be used to represent the Claude air liquefier by replacing the refrigeration term with an exit stream oi rhf from the liquid reservoir. An energy balance around the cycle excluding the compressor results in... 

Determine whether the Claude air liquefier described in Example 5.16 is operable if the inlet temperature to the expander with an efficiency of 70% is at 190 K rather than at the original 233 K. All other conditions are to be kept the same. If the system is operable, determine the fraction liquefied and the net work requirement of the compressor per unit mass of air liquefied assuming that the expander work is utilized in the compression. 

Compare the liquid yield for the Claude air liquefier in Example 5.16 with that for a cycle with identical equipment components if the system operates between 0.101 and 4.04 MPa and the inlet to the 70% efficient expander is fixed at 190 K. Compare the inlet and exit temperatures for the three heat exchangers and evaluate the increase in compression work that is attributable to the 5 % loss in effectiveness of the heat exchangers. 

Air liquefied 23 0-360 6 Limited resistance - changes in mass dimensions properties ULTRADUR BASF... 

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