Gas system requirements

The vacuum plate drwer is provided as pari of a closed system. The vacuum dryer has a cylindrical housing and is rated for fiill-vacuum operation (typical pressure range 3-27 kPa absolute). The exhaust vapor is evacuated try a vacuum pump and is passed through a condenser for solvent recovery. There is no purge-gas system required for operation under vacuum. Of special note in the vacuum-drying system... 

Example 4.3 represents the simplest possible example of a variable-density CSTR. The reaction is isothermal, first-order, irreversible, and the density is a linear function of reactant concentration. This simplest system is about the most complicated one for which an analytical solution is possible. Realistic variable-density problems, whether in liquid or gas systems, require numerical solutions. These numerical solutions use the method of false transients and involve sets of first-order ODEs with various auxiliary functions. The solution methodology is similar to but simpler than that used for piston flow reactors in Chapter 3. Temperature is known and constant in the reactors described in this chapter. An ODE for temperature wiU be added in Chapter 5. Its addition does not change the basic methodology. 

According to the vendor, this project could provide a compact, low-cost reactor to treat aqueous mixed waste streams containing nitrates or nitrites, eliminate the need for chemical reagents, and minimize or eliminate secondary wastes such as nitrous oxide and secondary products such as ammonia, H2, and O2 that are prevalent with other nitrate destruction processes. By removing nitrates and nitrites from waste streams before they are sent to high-temperature thermal destruction and vitrification, production of NO can be decreased with the attendant decrease in off-gas system requirements. Biocatalytic nitrate destruction is applicable to a wide range of aqueous wastes with a highly variable composition. All information is from the vendor and has not been independently verified. 

Automotive Exhaust-Gas System Requirements for Oxygen Sensors... 

There are additional changes to the cooling and exhaust gas system required when integrating the powertrain into the vehicle body. A safety system is also installed to monitor aU components and thus to ensure the highest possible safety standards. 

Purging Carrier and Makeup Gases Carrier-gas and makeup-gas systems require a static purge, followed by a dynamic purge, to ensure the desired purity levels. 

While the electrochemical sensor used in this study is sensitive to oxygen, a different probe would be required for use with other gases. Ternary gas systems require the use of several electrochemical sensors as opposed to one. 

Terminal Velocity. The single-particle terminal velocity, U, is the gas velocity required to maintain a single particle suspended in an upwardly flowing gas stream. A knowledge of terminal velocity is important in fluidized beds because it relates to how long particles are retained in the system. If the operating superficial gas velocity in the fluidized bed far exceeds the terminal velocity of the bed particles, the particles are quickly removed. 

Off-Gas Treatment. Before the advent of the shear, the gases released from the spent fuel were mixed with the entire dissolver off-gas flow. Newer shear designs contain the fission gases and provide the opportunity for more efficient treatment. The gaseous fission products krypton and xenon are chemically inert and are released into the off-gas system as soon as the fuel cladding is breached. Efficient recovery of these isotopes requires capture at the point of release, before dilution with large quantities of air. Two processes have been developed, a cryogenic distillation and a Freon absorption. 

In the reprocessing environment there are many mthenium compounds, some of which are gaseous. Some reprocessing approaches, notably the REDOX process, require a mthenium removal step in the off-gas system. The PUREX process maintains mthenium in one of its nonvolatile states. 

As in the case of the salt complexation processes, the cryogenic systems require prepuriftcation of the feed gas. Bulk water, hydrogen sulfide, and carbon dioxide are removed by standard techniques. Final removal of these materials is accompHshed by adsorption. After prepuriftcation, the gases are ready for cryogenic processing. 

The theoretical requirement for use of Eq. (14-190) is that the microscale of turbulence This is satisfied in most gas systems. For example, in three cases,... 

The gas system did not inelude any storage other than pipeline paek and one relatively small high-pressure pipe-type holder. Therefore, pressures and flows in all areas of the system varied widely on a daily and seasonal basis. Several years of operating data were reviewed and analyzed to seleet a loeation that met the flow and pressure drop requirements for installation of an expander. Site seleetion also gave eonsideration to the requirements for eonneetion to the gas system, eonneetion to the eleetrie system, and sound attenuation measures neeessary to eliminate any impaet on the surrounding area. 

The installed eost is primarily determined by the size of the unit. However, other faetors may have a signifieant impaet on this eost. The eonneetion to the gas system eould be expensive if speeial hot tap fittings are required. If sound attenuation is neeessary for the ehosen loeation, this ean also have an impaet on the overall eost. The eonneetion to the eleetrieal system ean add signifieant eost if distanees are far or high-voltage switehgear is neeessary. Equipment manufaeturers are able to provide eost estimates for major equipment. The installation eosts are site speeifie and require individual studies and estimates. 

Suppose a gaseous process effluent of 30 m min is at 200°C and 50% relative humidity. It is cooled to 65°C by spraying with water that was initially at 20°C. What volume of saturated gas would you have to design for at 65 C How much water per cubic meter would the system require How much water per cubic meter would you have to retimve from the system ... 

Storage tanks and surge vessels for MEA must have inert blanket-gas systems. Sweet natural gas or nitrogen can be used as the blanket gas. This is required because MEA will oxidize when exposed to the oxygen in air. 

This process uses propylene carbonate as a physical solvent to remove CO2 and H2S. Propylene carbonate also removes C2+ hydrocarbons, COS, SO2, CS2, and H2O from the natural gas stream. Thus, in one step the natural gas can be sweetened and dehydrated to pipeline quality. In general, this process is used for bulk removal of CO2 and is not used to treat to less than 3% CO2, as may be required for pipeline quality gas. The system requires special design features, larger absorbers, and higher circulation rates to obtain pipeline quality and usually is not economically applicable for these outlet requirements. 

The pump gas can be used to fuel the reboiler. The amount of pump gas is normally close to balancing the reboiler fuel gas requirements. The pump gas can also be routed to the facility fuel gas system or to a low-pressure system for compression and sales. If it is not recovered in one of these ways and is just vented locally, the cost of using this type of pump can be very high. 

---