Injection rates

Venturi scmbbers can be operated at 2.5 kPa (19 mm Hg) to coUect many particles coarser than 1 p.m efficiently. Smaller particles often require a pressure drop of 7.5—10 kPa (56—75 mm Hg). When most of the particulates are smaller than 0.5 p.m and are hydrophobic, venturis have been operated at pressure drops from 25 to 32.5 kPa (187—244 mm Hg). Water injection rate is typicaUy 0.67—1.4 m of Hquid per 1000 m of gas, although rates as high as 2.7 are used. Increasing water rates improves coUection efficiency. Many venturis contain louvers to vary throat cross section and pressure drop with changes in system gas flow. Venturi scmbbers can be made in various shapes with reasonably similar characteristics. Any device that causes contact of Hquid and gas at high velocity and pressure drop across an accelerating orifice wiU act much like a venturi scmbber. A flooded-disk scmbber in which the annular orifice created by the disc is equivalent to a venturi throat has been described (296). An irrigated packed fiber bed with performance similar to a... 

At a holdup time longer than 10—15 min at a high temperature, resin degradation is avoided by keeping the rear of the cylinder at a lower temperature than the front. At short holdup times (4—5 min), cylinder temperatures are the same in rear and front. If melt fracture occurs, the injection rate is reduced pressures are in the range of 20.6—55.1 MPa (3000—8000 psi). Low backpressure and screw rotation rates should be used. 

Wettabihty is defined as the tendency of one fluid to spread on or adhere to a soHd surface (rock) in the presence of other immiscible fluids (5). As many as 50% of all sandstone reservoirs and 80% of all carbonate reservoirs are oil-wet (10). Strongly water-wet reservoirs are quite rare (11). Rock wettabihty can affect fluid injection rates, flow patterns of fluids within the reservoir, and oil displacement efficiency (11). Rock wettabihty can strongly affect its relative permeabihty to water and oil (5,12). When rock is water-wet, water occupies most of the small flow channels and is in contact with most of the rock surfaces as a film. Cmde oil does the same in oil-wet rock. Alteration of rock wettabihty by adsorption of polar materials, such as surfactants and corrosion inhibitors, or by the deposition of polar cmde oil components (13), can strongly alter the behavior of the rock (12). 

Injection Well Considerations. Eluid injection rate can have a significant effect on oil recovery economics. Elow is radial from the wellbore into the reservoir. Thus the region near the injection wellbore acts as a choke for the entire reservoir. 

Addition of surfactant to the injection water (14,15) can displace the oil remaining near the well. The lower oil saturation results in an increase in the water relative permeabihty (5). Therefore, a greater water injection rate may be maintained at a given injection pressure. Whereas ultimate oil recovery may not be increased, the higher water injection rate can increase oil production rates improving oil recovery economics. Alternatively, a lower injection pressure can be used. Thus smaller and cheaper injection pumps may be used to maintain a given injection rate. The concentration of surfactant in the injection... 

The substantial decrease of polyacrylamide solution viscosity in mildly saline waters can be uti1i2ed to increase injection rates. A quaternary ammonium salt polymer can be added to the polyacrylamide solution to function as a salt and reduce solution viscosity (144). If the cationic charge is in the polymer backbone and substantially shielded from the polyacrylamide by steric hindrance, formation of an insoluble interpolymer complex can be delayed long enough to complete polyacrylamide injection. Upon contacting formation surfaces, the quaternary ammonium salt polymer is adsorbed reducing... 

In the SCR process, ammonia, usually diluted with air or steam, is injected through a grid system into the flue/exhaust stream upstream of a catalyst bed (37). The effectiveness of the SCR process is also dependent on the NH to NO ratio. The ammonia injection rate and distribution must be controlled to yield an approximately 1 1 molar ratio. At a given temperature and space velocity, as the molar ratio increases to approximately 1 1, the NO reduction increases. At operations above 1 1, however, the amount of ammonia passing through the system increases (38). This ammonia sHp can be caused by catalyst deterioration, by poor velocity distribution, or inhomogeneous ammonia distribution in the bed. 

Effect of water injection rate on heat rate as a function of compressor inlet temperature... 

How are the abrasives introduced into the machine With air compressors, the abrasive can be thrown into the open suction. If the suction or point of injection is pressurized, the abrasives can be introduced with a blow pot. An eductor should be used to put the abrasive leaving the blow pot into a fluidized state before introducing it to the main gas stream. A good starting point for the injection rate is 0.1 weight percent of gas flow. 

Displacement or Slow Rinse - After brine injection, the salt solution remaining inside the vessel is displaced slowly, at the same rate as the brine injection rate. The slow rinsing should be continued for at least 15 minutes and the slow rinse volume should not be less than 10 gallons/cu ft of the resin. The actual duration of the slow rinse should be based on the greater of these two parameters. 

Similar expressions may also be derived for a circular section channel and for the situation where the injecdon rate is held constant rather than the pressure (see quesdons at the end of the chapter). In pracdcal injecdon moulding situations the injection rate would probably be held constant until a pre-selected value of pressure is reached. After this point, the pressure would be held constant and the injection rate would decrease. 

Example 5.14 A power law fluid with constants i]q= 1.2 x lO Ns/m and n = 0.35 is injected through a centre gate into a disc cavity which has a depth of 2 mm and a diameter of 200 mm. If the injection rate is constant at 6 X 10 m /s, estimate the time taken to fill the cavity and the minimum injecdon pressure necessary at the gate for (a) Isothermal and (b) Non-isothermal conditions. 

Fig. 5.27 shows the variation of MEP with flow ratio (R/H) for spreading flow in discs of different depths. The material is polypropylene and the constant injection rate is 3.4 x 10 m /s. This is a high injection rate but has been chosen because the clamp forces predicted by this diagram are representative of those occurring in real moulding situations (even though it is based... 

Fig. 5.28 shows a comparison of the isothermal and non-isothermal situations for polypropylene. When pressure is plotted as a function of injection rate, it... 

Fig. 5.28 Variation of Cavity Pressure Loss with Injection Rate...

However, in the non-isothermal case the pressure is also high at low injection rates. This is because slow injection gives time for significant solidification of the melt and this leads to high pressures. It is clear therefore that in the non-isothermal case there is an optimum injection rate to give minimum pressure. In Fig. 5.28 this is seen to be about 3.0 x 10 m /s for the situation considered here. This will of course change with melt temperature and mould temperature since these affect the freeze-off time, //, in the above equations. 

A power law fluid with the constants rjo = 10 Ns/m and n = 0.3 is injected into a circular section channel of diameter 10 mm. Show how the injection rate and injection pressure vary with time if. 

For this case it is impractical to lower the dew point with methanol. A more practical solution would be to separate the condensate first. At 1,000 psia the dew point is 68.4°F (see example in Chapter 5). Assuming a separator temperature of 75°F the amount of methanol needed to lower the dew point of gas to 65°F is 9.7 Ib/MMscf. Using a surge factor of 1.4, the required injection rate is only 13.6 Ib/MMscf or 2.0 gal/MMscf. 

To determine the appropriate injection rate, a field test should first be performed at one of the industry-sponsored full-scale loop test facilities. The optimum mixture, its injection rate, and location of injcciioii points will be a function of flow geometry, fluid properties, pressure leinpcrature relationships, etc., that will be encountered in the actual field application. The appropriate injection rate and location of injection jii iiiis can be determined from this test by observing pressure increases, which indicate that hydrate plugs are forming. 

Initial treatment should range from about 300 mg/L of scavenger, and injection rates should be as high as the pump will allow. Treatment has to be adjusted to achieve from 100 to 300 mg/L sulfite residual at the flowline. 

Where it is available the source can be a separate boiler plant, but common practice is to employ purpose-made electrode boilers within or adjacent to the plant. The latter reduces sensible gains to the plant but, being essentially saturated steam, condensate return pipes are required. In addition to the rise in moisture content of the air (kg/kg) being dependent on airflow and steam-injection rates, there is a very small increase in dry bulb temperature by the cooling of the vapor to the air temperature. The rise in total heat is total heat of steam (kJ/kg) x quantity supplied per kg air. 

Ammonia Injection rate controlled on pH of condensate in accumulator... 

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