Micro-pressurized process

The micro-pressurized process. The gas is produced at 8.5 MPa, following desulphurization, steam shift, de-carbonization, reinforcing N2, and is then micro-pressurized to 9.0-10.0 MPa (by the circulation compressor with micro-pressurizing section) and enter converter. 

In the micro-pressurized process at 9-10 MPa, the first section can be omitted. The syngas pressure would be increased to 8.5-10 MPa only through the circulating section. It functions as both compressor and circulator. This is the so-called micro-pressurized process. Table 9.6 shows the outlet concentration and the net value of ammonia for A301 at 8.5 MPa and 10.0 MPa. 

Table 9.6 shows that in the micro-pressurized process, the outlet concentration and net value of ammonia is 16.66% (425°C) and 13% at 8.5 MPa and 6000h /. It is 17.20% (425°C) and 13.57% at lOMPa and 8,000h respectively. Table 9.7 shows the amount of inlet syngas (5jn) and catalyst volume (Foat) needed at micro-pressurized ammonia synthesis plant with capacity of 10001 d at 8.5-10 MPa. 

It is obvious that if A301 catalyst is used, it only needs to increase catalyst volume of converter or to decrease condensing temperature properly to reform synthetic technology of the gasification of dreg oil or pulverized coal at 8.5 MPa-9.0 MPa to the micro-pressurized process at 8.5 MPa or 10 MPa. For the thermal purification process, the inert gas content and condensing temperature should be adjusted appropriately. 

As examples of micro-channel process intensification and the respective equipment, in particular gas/liquid micro reactors and their application to toluene and various other fluorinations and also to carbon dioxide absorption can be mentioned [5]. Generally, reactions may be amenable to process intensification, when performed via high-temperature, high-pressure, and high-concentration routes and also when using aggressive reactants [5]. 

GP 8[ [R 7[ Syngas generation with commercial Pt-Rh gauzes, metal-coated foam monoliths and extruded monoliths has been reported. For similar process pressure, process temperature, and reaction mixture composition, methane conversions are considerably lower in the conventional reactors (CH4/O2 2.0 22 vol.-% methane, 11 vol.-% oxygen, 66 vol.-% inert species 0.14—0.155 MPa 1100 °C) [3]. They amount to about 60%, whereas 90% was reached with the rhodium micro reactor. A much higher H2 selectivity is reached in the micro reactor the CO selectivity was comparable. The micro channels outlet temperatures dropped on increasing the amount of inert gas. 

The use of emerging food technologies such as ultrasound, static high-pressure processing and microfluidisation may provide the platform for the creation of novel micro structured assemblies to meet future needs and provide new processing or preprocessing capabilities for encapsulation systems. 

In micro-process technology, micro-structured process components such as heat exchangers, mixers or reactors are being developed in which very intensive heat and mass transfer can be realized. In many cases, under defined conditions, this allows process intensification with drastically reduced residence times for the reacting components and simultaneously a considerable increase in selectivity and yield. Due to the low degree of hold-up, hazardous components can be handled safely, even under extreme pressure and temperature conditions. 

Hydrophobic membranes, e.g., PTFE, permit the efficient removal of volatile analytes from the sample matrix by diffusion though the micropores [257]. As these membranes have a high diffusion efficiency for many gaseous species, selectivity is usually low. For hydrophilic porous membranes, mass transference usually relies on dialysis, provided differences in donor and acceptor stream pressures are low [258] the chemical species originally in the donor stream migrate through the solvent in the interstitial volume of the membrane. Ionic species are therefore efficiently separated from the macromolecules in the sample matrix. Increasing the difference in pressures of both streams favours the micro-filtration process therefore, filtration and dialysis may occur simultaneously [259,260]. 

Usually the pitot tube is connected with a soft rubber tube to the micro pressure gauge, and calculates the velocity based on a certain formulai i. But in the process of actual usage, the velocity measurement precision is affected by a number of environ-mentd factors. It needs to analyze the influencing factors of measurement results and acquire the measurement uncertainty of instruments. A velocity measurement device based on the principle of pitot tube is proposed in this article. The influence factors of velocity measurement are analyzed, and the measurement uncertainty of the device is calculated afterwards. 

Theoretical knowledge on pressure-driven gas microflows is currently well advanced, especially in the slip-flow regime. However, there is yet a need for accurate experimental data, both for steady or unsteady gas microflows, with or without heat transfer. For example, in order to definitely validate the choice of the best boundary conditions in the slip flow regime, we need to isolate the influence of the accommodation coefficients, as it remains an open issue. Relationships between their values, the nature of the substrate and the micro fabrication processes involved are currently not available. There are also few data about flows of gas mixtures in microchannels. 

In these investigations it was also shown that the Kjeldahl process is suitable for the determination of nitrogen in titanium, both in its conventional form - dissolution in hydrofluoric acid, conventional distillation and photometric determination - if certain experimental conditions are observed, and in the modified form of pressure digestion, micro-Kjeldahl process, circulatory distillation and coulometric determination. These results can also be applied to the analysis of titanium alloys. 

Two-phase flows in micro-channels with an evaporating meniscus, which separates the liquid and vapor regions, have been considered by Khrustalev and Faghri (1996) and Peles et al. (1998, 2000). In the latter a quasi-one-dimensional model was used to analyze the thermohydrodynamic characteristics of the flow in a heated capillary, with a distinct interface. This model takes into account the multi-stage character of the process, as well as the effect of capillary, friction and gravity forces on the flow development. The theoretical and experimental studies of the steady forced flow in a micro-channel with evaporating meniscus were carried out by Peles et al. (2001). These studies revealed the effect of a number of dimensionless parameters such as the Peclet and Jacob numbers, dimensionless heat transfer flux, etc., on the velocity, temperature and pressure distributions in the liquid and vapor regions. The structure of flow in heated micro-channels is determined by a number of factors the physical properties of fluid, its velocity, heat flux on... 

The processes in a cooling system of electronic devices with high power density can be modeled as follows. The coolant with temperature T2.0 and pressure F2.0 enters into the micro-channel from the tank (5) (Fig. 10.2). The mass capacity of the liquid in the tank (5) is large enough, therefore the heat flux from the micro-channel... 

In 1999, Luo and Domfeld [110] proposed that there are two typical contact modes in the CMP process, i.e., the hydro-dynamical contact mode and the solid-solid contact mode [110]. When the down pressure applied on the wafer surface is small and the relative velocity of the wafer is large, a thin fluid film with micro-scale thickness will be formed between the wafer and pad surface. The size of the abrasive particles is much smaller than the thickness of the slurry film, and therefore a lot of abrasive particles are inactive. Almost all material removals are due to three-body abrasion. When the down pressure applied on the wafer surface is large and the relative velocity of the wafer is small, the wafer and pad asperity contact each other and both two-body and three-body abrasion occurs, as is described as solid-solid contact mode in Fig. 44 [110]. In the two-body abrasion, the abrasive particles embedded in the pad asperities move to remove materials. Almost all effective material removals happen due to these abrasions. However, the abrasives not embedded in the pad are either inactive or act in three-body abrasion. Compared with the two-body abrasion happening in the wafer-pad contact area, the material removed by three-body abrasion is negligible. 

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