High pressure intensifier

Fig. 4.1-14. Double-head high-pressure intensifier metering pump.

Fig. 8.151 Photograph and schematic (inset) of a modern high pressure intensifier pump (courtesy EPSI, Haverhili, MA. USA).

Fig. 6.7-29 Photograph and diagram of a dry-bag CIP system (courtesy Dorst, Kochel am See, Germany). 1, protective enclosure 2, control cabinet 3, hydraulic unit 4, high-pressure intensifier pump 5, loading device 6, hopper 7, dosing device ...

The decarbonization of steel increases the porosity of the metal. The adsorption of gases in the pores may intensify the erosive action since the gases enter the pores at high pressures and temperatures and then expand, they blow up the pores. 

In this part, only brief details are given about corrosive attack, especially that caused or intensified by high pressure. 

In high-pressure applications (70-8,250 bar = 1,000-120,000 psi) and in the capacity range of 3-1,200 kg/d (1-350 scfm), intensifiers are often added to the compressor. In these oil-free, nonlubricated gas pistons/ the pressure of a hydraulic fluid moves the piston as it compresses the GH2 (Figure 1.51). Both the flow and the discharge pressure of the H2 are controlled by the hydraulic drive. This way, the rate at which the electrolyzer generates the H2 is matched to the H2 flow in the compressor. 

Figure 1.51 illustrates the double-ended piston design of the intensifier, which can boost the pressure of the H2 from 5 bar (70 psi) to 1,000 bar (15,000 psi). This pressure increase is standard for filling GH2 storage tanks or transport vehicles. In stage 1 of the intensifier operation, the high-pressure... 

In a similar manner, the ethylene-octene copolymer crystallized directly via the orthorhombic phase without the intervention of the anticipated hexagonal phase as would be anticipated in linear polyethylenes at these high pressures and temperatures (at approximately 3.8 kbar and around 200 °C). At 100 °C, see Fig. 15, the d values for (110) and (200) orthorhombic reflections are 4.08 A and 3.71 A. When the sample is cooled below 100 °C, a new reflection adjacent to the (110) orthorhombic peak appears at 80 °C. The position of the new reflection is found to be 4.19 A and so corresponds to a new phase. No change in the intensity of the existing (110) and (200) reflections is observed, however the intensity of the amorphous halo decreases, which suggests that the appearance of the new reflection (d = 4.19 A) is solely due to the crystallization of a noncrystalline component. On cooling further as the new reflection intensifies, the (110) and (200) orthorhombic reflections shift gradually. However, at 50 °C, the (100) monoclinic reflection appears with a concomitant decrease in the intensity of the (110) orthorhombic reflec-... 

Pyroxenes from extraterrestrial sources provide unequivocal examples of Ti3+ —> Ti4+ IVCT and Fe2+ —> Ti4+ IVCT bands. For example, the iron-free green titanian pyroxene in the Allende meteorite discussed in 4.4.1 is the one irrefutable example of a mineral showing a Ti3+ — > Ti4+ IVCT transition. The position of the band at 666 nm (15,000 cm-1) shown earlier in fig. 4.2 is insensitive to pressure, but it does intensify at high pressures (Mao and Bell, 1974a), consistent with it representing a Ti3+ —> Ti4+IVCT transition between adjacent Ti3+ and Ti4+ ions located in edge-shared Ml octahedra in the pyroxene structure (fig. 5.13). 

Because of the low design temperature of 100°C, an elastomer gasket material, which does not wear down the sealing surfaces too much, could be chosen. For two reasons it was advisable to use a self-intensifying type of gasket (lip seal) Firstly, the high pressure can be safely contained, and secondly, no pretensioning is necessary. 

Constant pressure pumps utilise pneumatics or hydraulics apply the pressure required to force the mobile phase through the column, either directly or indirectly. Two main designs of constant pressure pump exist the pressurised coil pump, and the pneumatic pressure intensifier type. The pressurised coil pump is now all but redundant, but as it represents the most simple means possible of pumping at high pressure through an HPLC column it is described briefly. 

Other problems with pneumatic intensifier pumps include the fact that access to the high pressure seals for inspection and maintenance is usually quite restricted, by nature of their design. Because of the way they operate, the flow they produce is inherently highly pulsatile in nature and they also tend to be extremely noisy in use. For these reasons, pumps of this type are not used in general analytical HPLC. However, pneumatic intensifier pumps have found a niche in the packing of HPLC columns, where the intermittent nature of the function and their ability to deliver very high pressures compensate somewhat for their shortcomings in the analytical field. 

In all cases, the pressure used should be the lowest which will do the work. This saves first cost, power and time. In many instances a part of an operation can be performed at low pressure, the finish only requiring high pressure. This dual system may be provided by a complete duplication of pumps, accumulators and piping, with manual or automatic transfer valves, or intensifiers may be used at points of fluid consumption. These are pumps using the low-pressure fluid as the actuating medium in what corresponds to the steam cylinder, to produce a local excess pressure. 

---