Psia

Standard conditions of femperature and pressure are commonly defined as 60°F (298K) and one atmosphere (14.7 psia or 101.3 kPa). 

The previous equation is only valid as long as there is no compositional change of the gas between the subsurface and the surface. The value of E is typically in the order of 200, in other words the gas expands by a factor of around 200 from subsurface to surface conditions. The actual value of course depends upon both the gas composition and the reservoir temperature and pressure. Standard conditions of temperature and pressure are commonly defined as 60°F (298K) and one atmosphere (14.7 psia or 101.3 kPa), but may vary from location to location, and between gas sales contracts. 

Below is a typical oil PVT table which is the result of PVT analysis, and which would be used by the reservoir engineer in calculation of reservoir fluid properties with pressure. The initial reservoir pressure is 6000 psia, and the bubble point pressure of the oil Is 980 psia. 

In a normal pressure regime the pressure in a hydrocarbon accumulation is determined by the pressure gradient of the overlying water (dP / dD), which ranges from 0.435 psi/ ft (10 kPa/m) for fresh water to around 0.5 psi/ft (11.5 kPa/m) for salt saturated brine. At any depth (D), the water pressure (PJ can be determined from the following equation, assuming that the pressure at the surface datum is 14.7 psia (1 bara) ... 

To prevent such release, off gases are treated in Charcoal Delay Systems, which delay the release of xenon and krypton, and other radioactive gases, such as iodine and methyl iodide, until sufficient time has elapsed for the short-Hved radioactivity to decay. The delay time is increased by increasing the mass of adsorbent and by lowering the temperature and humidity for a boiling water reactor (BWR), a typical system containing 211 of activated carbon operated at 255 K, at 500 K dewpoint, and 101 kPa (15 psia) would provide about 42 days holdup for xenon and 1.8 days holdup for krypton (88). Humidity reduction is typically provided by a combination of a cooler-condenser and a molecular sieve adsorbent bed. 

Hydroca.rbons. Hydrocarbonsn such as propane, butane, and isobutane, which find use as propellants, are assigned numbers based upon their vapor pressure in psia at 21°C. For example, as shown in Table 2, aerosol-grade propane is known as A-108, / -butane as A-17. Blends of hydrocarbons, eg, A-46, and blends of hydrocarbons and hydrochlorocarbons orHCFCs are also used. The chief problem associated with hydrocarbon propellants is their flammabihty. 

Molten Salt Distillation. Hafnium tetrachloride is slightly more volatile than zirconium tetrachloride, but a separation process based on this volatility difference is impractical at atmospheric pressures because only soHd and vapor phases exist. The triple point for these systems is at about 2.7 MPa (400 psia) and 400°C so that separation of the Hquids by distillation would necessarily require a massive pressurized system (13). 

MPa (300—400 psig), using a Ni-based catalyst. Temperatures up to 1000°C and pressures up to 3.79 MPa (550 psia) are used in an autothermal-type reformer, or secondary reformer, when the hydrogen is used for ammonia, or in some cases methanol, production. 

The key feature of the pressurized water reactor is that the reactor vessel is maintained above the saturation pressure for water and thus the coolant-moderator does not bod. At a vessel pressure of 15.5 MPa (2250 psia), high water temperatures averaging above 300°C can be achieved, leading to acceptable thermal efficiencies of approximately 0.33. 

Courtesy of GE Nuclear Energy. For a more complete Hst, see Refs. 11 and 52. To convert MPa to psia, multiply by 145. 

There are several hundred pressure tubes, each containing bundles of 28 fuel rods, 50 cm long. The coolant is at a pressure of around 10 MPa (1450 psia) and the D2O is at 310°C. Headers on each side of the vessel collect and return coolant from all the tubes. The 4-mm wall-thickness zirconium—4.5%... 

Certain boilers employ forced circulation, whereby a pump helps impart the circulation through the downcomer lines to the waterwaH header, particularly to improve or control circulation at low loads. Forced-circulation pumps are also required in high pressure and supercritical pressure boilers, because once the pressure within a boiler approaches the critical pressure, 22.1 MPa (3208 psia), the densities of the water and steam become similar, limiting or eliminating the potential for natural circulation. 

A 165-MW-class gas turbine/generator has been introduced by another manufacturer. This machine, also developed by scaling up a proven design, features a simple-cycle efficiency of 37.5% a turbine inlet temperature of 1235°C a pressure ratio of 30 1, up from 16 1 on the previous generation and an output of 165 MW for gas fuel firing under International Standards Organization (ISO) conditions (101 kPa, 15°C (14.7 psia, 59°F)). A combined-cycle facihty based around this machine could achieve efficiencies up to 58% or a heat rate of about 6209 kj/kWh (5885 Btu/kWh). 

Ethylbenzene Hydroperoxide Process. Figure 4 shows the process flow sheet for production of propylene oxide and styrene via the use of ethylbenzene hydroperoxide (EBHP). Liquid-phase oxidation of ethylbenzene with air or oxygen occurs at 206—275 kPa (30—40 psia) and 140—150°C, and 2—2.5 h are required for a 10—15% conversion to the hydroperoxide. Recycle of an inert gas, such as nitrogen, is used to control reactor temperature. Impurities ia the ethylbenzene, such as water, are controlled to minimize decomposition of the hydroperoxide product and are sometimes added to enhance product formation. Selectivity to by-products include 8—10% acetophenone, 5—7% 1-phenylethanol, and <1% organic acids. EBHP is concentrated to 30—35% by distillation. The overhead ethylbenzene is recycled back to the oxidation reactor (170—172). 

In dmm boilers sodium hydroxide (caustic), sodium phosphate, or both may be added for pH and scale control. Sodium hydroxide is used more in Europe than in the United States, where sodium phosphate treatment is usually preferred. In boilers operating above 4 MPa (580 psia), caustic concentrations must be carefully controlled to prevent highly corrosive deposits from forming. In the lowest pressure boilers, phosphate treatment may be used to compensate for lower purity feedwater. As the boiler pressure increases, the allowable phosphate concentration decreases, and at 16.5 MPa (2400 psia) or above, equiUbrium phosphate treatment may be used. In this treatment, caustic is added to a low phosphate concentration in the boiler to maintain the proper pH (20). 

In lower pressure boilers a variety of additional treatments may be appropriate, particularly if the steam is used in chemical process or other nonturbine appHcation. Chelants and sludge conditioners are employed to condition scale and enable the use of less pure feedwater. When the dmm pressure is less than 7 MPa (1015 psia), sodium sulfite may be added direcdy to the boiler water as an oxygen scavenger. It has minimal effect on the oxygen concentration in the system before the boiler. 

---