Hydrogen flowrate

Gas Oil Recycle Rate A Make-up Hydrogen Flowrate A Recycle Gas Flowrate A ... 

Gas Oil Recycle Rate B Make-up Hydrogen Flowrate B Recycle Gas Flowrate B ... 

The more rapid initial drying obtained with the higher hydrogen flowrate resulted in a more rapid temperature rise and vaporization of liquid and subsequent pore emptying. Similar results were reported by Watson and Harold (1993). However, the heat transfer coefiBcient is also enhanced, allowing the bed to remove heat more efficiently. Maximum temperatures differ in less than 20 C. 

For maximum FID seusitivity, set the air flowrate 10 times higher than the hydrogen flowrate. The ratio of hydrogen flowrate to the combined carrier-gas and makeup-gas flowrates should be approximately unity. 

Hydrogen is pumped from a reservoir at 2 MN/m2 pressure through a clean horizontal mild steel pipe 50 nun diameter and 500 m long. The downstream pressure is also 2 MN/m2 and the pressure of this gas is raised to 2,6 MN/m2 by a pump at the upstream end of the pipe. The conditions of flow are isothermal and die temperature of the gas is 293 K. What is the flowrate and what is the effective rate of working of the pump ... 

Figure 8.57. Effect of catalyst potential on the rates of formation of C2H6, C2H4) HzCO, CH3OH and CH3CHO during CO hydrogenation on Pd/YSZ. The rate of CH4 formation is of the order 10 9 mol/s and is only weakly affected by UWr Single pellet design P=12.5 bar, T=350°C. pH2/pco= -8, flowrate 85 cm3 STP/min.5 59...

Figure 10.1. NEMCA in aqueous media (0.1 M KOH) Transient effect of applied positive and negative currents (1=15 and -10 mA) on the rates of consumption of hydrogen (rH2) and oxygen (ro) on Pt/graphite pH2=0-75 kPa, pQ2=1.06 kPa gas flowrate Fy=280 cmVmin at STP. Reprinted with permission from Nature, ref. 3, McMillan Magazines Ltd.

Example 13.5 A recycle gas stream containing 88% hydrogen and 12% methane is to be increased in pressure from 81 bar to 98 bar. The inlet temperature is 40°C and the flowrate is 170,000 Nm3 h 1 (Nm3 = normal m3). Estimate the power requirements for a centrifugal compressor for this duty. 

Figure 3 Hydrogenation of recycled Nylon-6 and Nylon-6,6 ammonolysis feed in the presence of 5 g of Raney Co 2724 catalyst at a total pressure of 500 psig, and temperature of 85 to 90°C, at a feed flowrate of 12 ml/h. Hexamethylenediamine ( ), caprolactam (A), adiponitrile ( ), 6-...

FIGURE 13.6 Calibration plot for hydrogen peroxide detection in flow-injection mode with nano-struc-tured Prussian blue as a detector Prussian blue electrodeposited through sol template based on the vinyltri-ethoxysilane, operating potential 50 mV, phosphate buffer pH 6.0 + 0.1M KC1, flowrate 0.7ml/min. 

FIGURE 1.10 Comparison of enantiomer separations of DNB-Leu on quinine (QN) based and 0-9-(terf-butylcarbamoyl)quinine (tBuCQN) based CSPs. 1, ionic interaction 2, jt-7T-interaction 3, hydrogen bonding 4, steric interaction. Experimental conditions Eluent, methanol-0.1 M ammonium acetate (80 20 v/v) (pHa = 6.0) flowrate, 1 mLmin temperature, 25°C column dimension, 150 x 4 mm ID detection, UV 250 nm. Selector loadings, 0.37 and 0.30 mmol g l for QN- and tBuCQN-based CSPs, respectively. (Reproduced from A. Mandl et ah, J. Chromatogr. A, 858 1 (1999). With permission.)... 

The performance of a three-phase fluidised-bed is to be assessed in relation to a model reaction, the hydrogenation of a-methyl styrene at 50°C. The same catalyst will be used as in Example 4.6, excepting that the diameter of the spherical particles will be 2.0 mm. The liquid and gas flowrates will be such that the volume fraction of particles in the bed will be 0.50 and the volume fraction of gas 0.20 i.e. the relationship shown in Fig. 4.21 will apply, from which the estimated bubble size is 5.0 mm. 

An initial assumption is made that the tail-gas stream is composed of nitrogen only. By an elemental nitrogen balance, the first estimate for the flowrate of the tail-gas stream is made. This enables the mass (and then moles) of hydrogen in the tail-gasstream to bedetermined. A mole balance on elemental hydrogen determines the moles of hydrogen added in the make-up water. This figure is used to determine the unknown feed stream of make-up water. Hence, all feed streams are defined. 

Hydrogenation reactions are frequently run in fed-batch reactors. The chemical component to be hydrogenated is charged to the reactor vessel. The hydrogen is then fed into the vessel on pressure control. The temperature of the reactor is controlled by manipulating the flowrate of coolant to the jacket, coil, or external heat exchanger. Thus this system has two manipulated variables (the flowrate of hydrogen and the flowrate of coolant) and two controlled variables (pressure and temperature). 

Since hydrogenation reactions are very exothermic, the situation often arises where the heat removal capacity cannot maintain the desired temperature with the normal operating hydrogen pressure. This usually occurs early in the batch when the concentration of the other reactant is high because it has not yet been diluted by the formation of the product compound. This situation requires that the flowrate of hydrogen be restricted so that temperature control is maintained. Thus pressure control should be temporarily abandoned. 

The flowsheet is based on a Stanford Research Institute report for the production of methanol (SRI 43C, March 2000). The flowrate of the fresh feed of synthesis gas is 11,450 kmol/h at a pressure of 51.2 bar and a temperature of 38°C. The composition is 67.4 mol% hydrogen, 23 mol% carbon monoxide, 6.9 mol% carbon dioxide, 2.2 mol% methane, and small amounts of nitrogen and water. Table 6.11 gives information on the... 

In general, the experimental apparatus is similar to the system that has been described previously (Liu, et al. 1998). The feed gases consisted of a combination of methane, oxygen, hydrogen, and helium. Helium was only used in initial experiments and for characterization studies of the catalyst. The feed gas flowrates were controlled by Porter mass flow controllers, model 201. The feed gases flowed axially down the reactor tube. The reactor was a quartz tube with a 9.0 mm O.D. and an I.D. of either 4.5 mm or 7.0 mm. The configuration of the reactor can be seen in Figure 1. 

In Figure 10.3a the flowrates of the fresh feed streams of hydrogen and toluene are shown. An 18°F decrease in reactor inlet temperature is made at time equals 10 minutes, and then the temperature is returned to its normal value at time equals 125 minutes. The drop in temperature reduces reaction rates, so the flowrates of the fresh reactant feed streams are reduced. After a fairly short time lag, the benzene product rate also drops as shown in Figure 10.36. The lower inlet temperature produces a lower reactor exit temperature, so less quench flow is required to maintain quench temperature (1150°F). Less heat-exchanger bypassing is required to maintain the furnace inlet temperature (1082°F) because the flowrate of the hot stream entering the FEHE has dropped. 

Note that the changes in production rate occur more quickly when the toluene recycle flowrate handle is used, compared to the reactor inlet temperature handle. Fresh feed rates of toluene and hydrogen change more quickly, as does benzene product flowrate. So if rapid transitions in production rate are important, toluene recycle flowrate manipulation is better than reactor inlet temperature manipulation. If tight product quality control is more important, the opposite is true. 

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