Nozzles, injection

The density of heavy fuels is greater than 0.920 kg/1 at 15°C. The marine diesel consumers focus close attention on the fuel density because of having to centrifuge water out of the fuel. Beyond 0.991 kg/1, the density difference between the two phases —aqueous and hydrocarbon— becomes too small for correct operation of conventional centrifuges technical improvements are possible but costly. In extreme cases of fuels being too heavy, it is possible to rely on water-fuel emulsions, which can have some advantages of better atomization in the injection nozzle and a reduction of pollutant emissions such as smoke and nitrogen oxides. 

In drying solutions or slurries of solutions, the location of the feed-injection nozzle (spray nozzle) has a great effecl on the size of particle formed in the bed. Also of importance are the operating temperature, relative humidity of the off gas, and gas velocity. Particle growth can occur as agglomeration or as an onion sldnuing. ... 

This corrosion is most pronounced in locations of high velocity, turbulence, and impingement, such as at elbows, weld reinforcements, pump impellers, steam injection nozzles, and locations where freshly condensed fractions drip upon or run down metal surfaces. 

Flare stack sizing and pressure drop is included with considerations of pressure drop through the safety valve headers, blowdown drums, flare headers, seal drum, etc. Elevated flare tips incorporating various steam injection nozzle configurations are normally sized for a velocity of 120 m/s at maximum flow, as limited by excessive noise and the ability of manufacturers to design tips which will insure flame stability. This velocity is based on the inclusion of steam flow if injected internally, but the steam is not included if added through jets external to the main tip. 

The inlet gas line should have taps for gas sampling, temperature measurement, pressure measurement, and for an injection nozzle for... 

The use of multinozzle injection machines. In general, this type of machine has a horizontal reciprocating screw that feeds four injection nozzles each connected to a single cavity mold thus minimizing waste. However, one concern with this approach is the need to have the mold accurately lined up (the top and bottom surfaces of the mold will be in the vertical plane) to eliminate compound leakage at the nozzle/mold interface. 

Figure 1-5 shows a typical feed preheat configuration. A hydraulic limitation usually manifests itself when increasing fresh feed rate and/ or installing high efficiency feed injection nozzles. 

Where chelant corrosion does occur, attack may take place either at the chelant entry point or at several possible boiler surface locations. At the chelant entry point, rapid thinning of the metal takes place in the immediate vicinity. If the injection point has not been stress-relieved, the attack may be exaggerated and metal gouging may also occur. At the injection point, the available chelant is highly concentrated injection of product should be continuous through a type 304 injection quill (injection nozzle), with the chelant being rapidly dispersed into the body of steam-water. 

Figure 13.4 DSM transonic oxygen injection nozzle. (Courtesy DSM.)...

Figure 9.1. Spatial distribution of the reducing agent depending on the position of the injection nozzle. Distance injection nozzle-catalyst entrance ( ) 85 cm, and (A) 350 cm.

Between the injection nozzle on the end of the extruder and the gate that leads into the mold cavity the polymer flows through a channel known as a runner . It is vital that the polymer does not solidify in the runner before the mold is completely filled. We can prevent premature solidification in the runner in one of two ways we can use a large diameter unheated (cold) runner in which the polymer solidifies after the polymer in the mold cavity, or we can use a heated (hot) runner in which the polymer does not solidify. Moldings that are produced... 

We can feed continuous fibers into the injection nozzle along with the molten polymer. 

As previously mentioned, plant personnel were successful at mitigating the black streaks with the use of static mixers positioned inside the injection nozzle. Since the degraded resin was soft and leathery, it was easily broken into smaller particles as they passed through the mixer. Thus, the particles were not eliminated they were just reduced in size such that they did not create as many black streaks. The additional pressure and time that was required to inject the resin through the static mixers and into the mold, however, increased the cycle time to an unacceptable level. Although static mixers can be used to mitigate these types of problems, they do not eliminate the root cause of the degradation problem. 

When the gas injection nozzle is in an unchoked condition, the pressure in the gas generator is equal to the combustion chamber pressure, i. e., pg = p The gas generation rate is determined by the pressure in the combustion chamber. When the gas injection nozzle is in a choked condition, the burning rate is determined by the gas injection nozzle area, A g, and then the pressure in the gas generator, pg, is determined by... 

The compressed, heated air is supplied to the ramburner through the air injection ports. Two types of air-injection ports, forming a so-called multi-port, are shown in Fig. 15.14 the forward port (two ports) and the rear port (two ports). The multi-port is used to distribute the airflow to the ramburner 34% is introduced via the forward port and the remaining 66 % via the rear port. The combustible gas formed by the combustion of the gas-generating pyrolant is injected through the gas injection nozzle and mixed with the air in the ramburner, and the burned gas is expelled form the ramburner exhaust nozzle. The pressures in the gas generator and the ramburner are measured by means of pressure transducers. The temperatures in the gas generator and the ramburner are measured with Pt-Pt/13%Rh thermocouples. 

Fig. 2. Swirl of air in recess in piston head of high-speed diesel in order to supply air to fuel jet burning on injection nozzle.

These and other improvements have resulted largely from a better understanding of the combustion process. The homogeneity of the gas mixture being burned has been improved by better design of acid gas (H2S, CO2) injection nozzles and, in some instances the introduction of internal furnace structures (checkered walls) to assist in mixing of the air and acid gas feeds. 

PBT resins are very fluid in the melt and sometimes drooling from the injection nozzle can be a problem in machines that do not have melt decompression. A simple free-flow nozzle can be used satisfactorily to minimize drooling if its temperature can be adjusted by a separate heater band. PBT does not drool as badly as nylons. 

It was established experimentally that a jet-type of flow appears when the characteristic size of the stream is less than the minimal gap between the walls of the mold.277 This proves that the cause is related to the ratio between the size of the injection nozzle and the coefficient of swelling of the elastic liquid moving inside the mold rather than to the axial momentum of the moving liquid. This conclusion is also supported by evidence that highly filled polymers, which are less elastic than pure melts, form jet-like patterns at lower flow speeds. 

An analysis of the temperature distribution in a mold (Fig. 4.54) at the final moment of filling for two reactive systems with different values of G shows that the temperature along the central line increases monotonically downstream (at distance x) from the inlet nozzle. At high values of the gelation criterion, the temperature at locations close to the injection nozzle is maximum near the mold wall. Moving down stream, the position of the temperature maximum shifts to the center, except at the frontal zone. Here the temperature is nearly constant, because the major part of the... 

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