Injection pressures

This property should also be within precise limits. In fact, a too-viscous fuel increases pressure drop in the pump and injectors which then tends to diminish the injection pressure and the degree of atomization as well as affecting the process of combustion. Inversely, insufficient viscosity can cause seizing of the Injection pump. 

Fig. 12. HDR reservoir flow test at Fenton Hill, New Mexico (1992) (39). (a) Injection pressure profile ( ) and a sismic limit (-------) (b) injection ( )...

Process details may be summarized powder sizes are fine (usually < 20 Ilm) low (generally < 69 MPa (10,000 psi)) injection pressure low (ca I49°C) mol ding temperature shrinkage (molded part to finished size) typically 20% final part densities are usually 95—98% + of maximum pore-free density and ductility is exceptionally high, elongation values are > 30%. 

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... 

Because of low injection pressure, some cost savings are possible in mold and press constmction. Mol ding cycles are somewhat longer than for injection molding. The part must be cooled in the mold long enough to be able to resist swelling from internal gas pressure. In stmctural foam parts there is almost a total absence of sink marks, even in the case of unequal section thickness. Stmctural foam has replaced wood, concrete, sohd plastics, and metals in a variety of appHcations. 

In steam stimulation, heat and drive energy are suppHed in the form of steam injected through weUs into the tar sand formation. In most instances, the injection pressure must exceed the formation fracture pressure in order to force the steam into the tar sands and into contact with the oil. When sufficient heating has been achieved, the injection weUs are closed for a soak period of variable length and then allowed to produce, first applying the pressure created by the injection and then using pumps as the weUs cool and production declines. 

PPS resins are chiefly used for injection mol ding. The melt flow of the glass-fiUed resins is very stiff, and high injection pressures are required. Mold surface wear is heavier than for most other engineering plastics. Mol ding melt temperatures are near 330°C for optimum surface gloss and impact strength, mold temperatures of 130°C should be used. The resins are brown to brown-black. 

This standard could be adapted to the fuel compressor for the natural gas to be brought up to the injection pressure required for the gas turbine. Covers the minimum requirements for reciprocating compressors and their drivers used in petroleum, chemical, and gas industry services for handling process air or gas with either lubricated or nonlubricated cylinders. Compressors covered by this standard are of moderate-to-low speed and in critical services. The nonlubricated cylinder types of compressors are used for injecting fuel in gas turbines at the high pressure needed. Also covered are related lubricating systems, controls, instrumentation, intercoolers, after-coolers, pulsation suppression devices, and other auxiliary equipment. 

A decrease of injection pressure (an increase of pressure will cause greater packing of material). 

To produce mouldings from polystyrene with minimum strain it is desirable to inject a melt, homogeneous in its melt viscosity, at a high rate into a hot mould at an injection pressure such that the cavity pressure drops to zero as the melt solidifies. Limitations in the machines available or economic factors may, however, lead to less ideal conditions being employed. 

Mould temperature Injection pressure Screw back pressure Screw speed Curing time... 

Wall sections in foam moulding are thicker than in solid material. Longer cycle times can therefore be expected due to both the wall thickness and the low thermal conductivity of the cellular material. In contrast, however, the injection pressures in foam moulding are low when compared with conventional injection moulding. This means that less clamping force is needed per unit area of moulding and mould costs are less because lower strength mould materials may be used. 

Since the reactants have a low viscosity, the injection pressures are relatively low in the RIM process. Thus, comparing a conventional injection moulding machine with a RIM machine having the same clamp force, the RIM machine could produce a moulding with a much greater projected area (typically about 10 times greater). Therefore the RIM process is particularly suitable for large... 

In ntosl respects the process is similar to the injection moulding of thermoplastics and the sequence of operations in a single cycle is as described earlier. For thermosets a special barrel and screw are used. The screw is of approximately constant depth over its whole length and there is no check value which might cause material blockages (see Fig. 4.50). The barrel is only kept warm (80-110°C) rather than very hot as with thermoplastics because the material must not cure in this section of the machine. Also, the increased viscosity of the thermosetting materials means that higher screw torques and injection pressures (up to 200 MN/m are needed). 

The container shown at the top of p. 341 is injection moulded using a gate at point A. If the injection pressure at the nozzle is 140 MN/m and the pressure loss coefficient, m, is 0.5, estimate (i) the flow ratio and (ii) the clamping force needed. 

Example 5.4 Eight polypropylene mouldings, each weighing 10 g are to be moulded using the runner layout shown in Fig. 5.19. If the injection time is 2 seconds and the melt temperature is 210°C, calculate the pressure at each cavity if the injection pressure at the sprue is 80 MN/m. The density of the pwlypropylene is 909 kg/m3 and the volume of the sprue is 5000 mm. Assume that the flow is isothermal and ignore the pressure losses at comers. 

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. 

Late cylinder injection is typically used for diesel engines. Fuel is admitted to the cylinder as the piston is nearing top center. Very high injection pressures are required for proper fuel atomization and combustion control. Pressures can exceed 20,000 psi for this type of injection. 

Mold temperature = 90°C maximum clamping force = 700 kN maximum injection pressure 225 MPa. 

All diesel fuels tend to contain trace water, expressed in parts per million (ppm). With the veiy high fuel injection pressures now used in electronically controlled diesel engine, fuel-filter/water separators are widely used, since water allowed to circulate freely through the injection system can result in seizure of components and erosion of injector orifice holes, and in extreme cases the high compressibility factor of water can blow the tip off of the fuel injector. 

Knowing the bottomhole pressure, the number of bit orifice openings and the inside diameter of these openings, the pressure inside the drill pipe just above the bit and the surface injection pressure can be found. 

The surface injection pressure P.(lb/ft abs) can be determined if knowing the pressure above the bit. The surface injection pressure is determined from... 

Using the data given below and results from the Example on p. 856, determine the real air volumetric flowrate and the expected surface injection pressure. The... 

The above injection pressure is the expected standpipe pressure when drilling at 10,000 ft of depth. The injection pressure will be somewhat less than the above when drilling the upper portion of the interval (i.e. at 8500 ). 

One area where MWD would be most useful is drilling safety and, particularly, early gas kick detection and monitoring. Conventional kick monitoring is based on pit gain measurements and all other available surface indication such as drilling rate break, injection pressure variation, etc. 

Hesitation continues until no pressure leak-off is observed. A further test of about 500 psi over the final injection pressure will indicate the end of the injection process. Usually, well-cementing perforations will tolerate pressures above the formation fracture pressure, but the risk of fracturing is increased. 

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