Nominal steam requirement

Figure 2. Nominal steam requirement for a typical flare tip.

Recommended nominal steam rates at 60 m/s exit velocity for a typical flare tip are shown in Figure 2. At lower velocities, higher steam ratios are required. Typical steam control consists of a flow ratio controller with adjustable ratio set point, related to flare gas flow. The ratio adjustment, located in the control house, provides for the higher steam ratios necessary at low flaring rates. 

The single-stage, single-valve turbine is the simplest option. Such a machine is suitable for applications requiring powers up to 300 kW, steam conditions up to a nominal 115 bar, 530°C and rotational speeds... 

The operating policy of Case 2 is a radically different policy to the nominal optimum (Case 1) which failed under uncertainty. Case 2 requires less steam and reflux and terminating after a few hours with most charge (88% of the initial charge in the reboiler) unreacted (compared to about 20 hrs and almost complete conversion for the nominal case). 

As a prelude to the design of the tube reactor (10), a kinetic study of the phenolysis procedure as a function of temperature was carried out on a larger scale. The equipment used was a stainless steel pressure reactor (Model 4501, Parr Instrument Company, Moline, Illinois). This reactor is fitted with an internal stirrer, an external electric heater, and a continuous sampling device. A mixture of the commercial ammonium lignin sulfonate (668 g) and molten phenol (1000 mL) was sealed into the reactor and heated to the designated temperatures. Approximately 3 hours were needed to heat the reactor from room temperature to 200 °C. A similar period of time was required to cool the reactor and its contents back to 22 °C after completion of a run. After a reaction period nominally lasting 2 hours, the unreacted phenol was steam distilled from the reaction mixture and the amount measured by comparative UV spectroscopy. The results obtained and summarized in Table IV show that a substantial amount of phenol becomes chemically combined with the renewable resource feedstock. 

The regeneration of activated carbon beds used in gas phase adsorption requires less severe conditions than for liquid phase processes. Regeneration can be conducted in situ by stripping with steam. Newer and more efficient systems use regeneration by hot inert gas, nominally at 350°F, to recover a greater portion of contaminants with their subsequent recovery. This is particularly attractive if the disposal of condensate from steam regeneration becomes a problem [73]. 

The simplest and most economical method of removing volatile oils from plant material is by distillation with a current of steam. This method cannot he used for flavors having oils that are unfavorably affected by the action of steam. Most volatile oils, however, can all be distilled by steam without serious decomposition. The chief advantages of the method are its simplicity, the comparatively brief time required for its operation, and the fact that large quantities of material can be handled at a small cost. It is the only method economically possible for the extraction of the great number of volatile oils of only nominal value, for which the more tedious processes would be impracticable. 

Table 12 shows the typical LRV values obtained using a polymeric and ceramic microfilter. Sterile filtration requires 100% bacteria retention by the membrane, whereas in many industrial bacteria removal applications the presence of a small quantity of bacteria in the filtrate may be acceptable. For example, drinking water obtained by microfiltration may contain nominal counts of bacteria in the filtrate which is then treated with a disinfectant such as chlorine or ozone. The use of ceramic filters may allow the user to combine the sterile filtration with steam sterilization in a single operation. This process can be repeated many times without changing filters due to their long service life (5 years or longer). 

The reference turbine plant design that has been developed for the PIUS plant design, is similar to that of present-day LWR plants, The 4.0 MPa, 270°C steam from the PIUS NSSS is at a lower pressure and temperature compared with the steam supplied from standard present-day LWR plants, and therefore PIUS requires a somewhat larger size turbine than other modern LWR plants. The nominal power output of the turbine unit will be 635-665 MWe depending on the site conditions. 

Another way of reducing the specific mass of lead bismuth coolant is to increase its average flow rate and to diminish the length of circulation circuit. However, this approach has its own constraints caused by the necessity to meet safety requirements. The first requirement is defined by the necessity to provide the power level of the reactor with naturally circulating lead bismuth coolant at the level not less than 5...7% of its nominal power. This makes it possible to eliminate inadmissible temperature increase under a shutdown of main circulation pumps. The second requirement is conditioned by the necessity to secure conditions for the assured surfacing of steam bubbles from lead bismuth coolant to its free surface level under the rupture of steam generator (SG) tubes. This is important to eliminate steam ingress into the core and inadmissible pressure increase in the mono-block vessel. 

Duplex filters are designed for use where an uninterrupted fuel flow is required, or where an immediate standby filter is essential. Fuel oil filters can generally incorporate air vents, drains and tappings for pressure differential instruments. Steam jackets, magnetic elements and interlocking safety devices may also be fitted. Fuel oil cartridges for this type of filter are fitted with media capable of operating up to 160°C, with a 4 am nominal filtration efficiency, and can withstand a 10 bar pressure differential. 

At the entrance and exit of the coil reactor, the temperatures are 326.5°C and 439 C, and the pressure is 2.62 and 0.90MPa (1.72MPa of delta-P), respectively. A typical feed flowrate of 124,300kg/h (about 20,000 barrel per day of nominal feed flowrate) is assumed for simulation purposes. One weight percentage of water steam was also fed to the coil reactor. Delta-P and steam flowrate are typical values reported in the literature (Joshi et al., 2008). Since the coil reactor is modeled as non-isothermal reactor, the required heat transfer rate is 4.33 x lO kJ/h. For the case of the soaker reactor, it is modeled as adiabatic reactor, so that temperature will reduce due to the endothermic nature of the visbreaking reactions. 

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