Constant oxygen flow

A solution of 18.5 mg (0.08 mmol) of (3a, 8a7 ,9a7 )-3a,4,6,7,8,8a,9.9a-octahydro-9,8-dimethyl-3-methylene-naphtho[2,3-h]furan-2(3.ff)-one and 2 mg of methylene blue in 10 mL of ethanol is photooxygenated for 8h at 22 + 2 °C. using a constant oxygen flow and a medium-pressure 400-W mercury lamp with a 1-cm filter width and filtering through a 2% aq sodium nitrite solution. The solvent is then evaporated in vacuo and the residue chromatographed (silica gel, hexane/EtOAc 4 1) to give an oil yield 12 mg (57%) [[Pg.444]

Figure 34 (59) shows an experiment in which the inlet concentration of CO is increased from zero and then lowered again at 200°C and for a constant oxygen flow. This process is called a concentration-programmed... 

Extensive research, performed at Cabot Norit Activated Carbon, has been done to determine the most optimal conditions for the glyphosate process as well as to study the influence of various properties of the activated carbon catalyst on the glyphosate production. The impact of these quantitative and qualitative parameters on the glyphosate reaction is discussed later. These studies were carried out in a 400 ml aqueous 2-3 wt% PMIDA solution containing 1-5 wt% activated carbon at 60-95 C applying a constant oxygen flow of 0-500ml/min. 

ID + ID Model. II. Water Management 6.4.1. Constant Oxygen Flow Rate... 

Constant Stoichiometry versus Constant Oxygen Flow... 

The results of the section Impedance of the Cathode Side of a PEM Fuel Cell, have been obtained assuming constant oxygen stoichiometry X of the flow. However, impedance experiments are usually performed at a constant oxygen flow rate, rather than at a constant X. Indeed, keeping constant X means that the inlet flow rate must be changed in phase with the mean current density perturbation, which is hardly possible. 

FIGURE 5.28 The CCL charge transfer resistivity at a constant oxygen flow rate (the first term on the right-hand side of Equation 5.181). 

Thus, in the constant-flow case, the total charge transfer resistivity is given by the inverse local current at the channel outlet. Clearly, as y o(l) < J, the eell charge transfer resistivity, at a constant flow, always exceeds this resistivity at a constant X (provided that the flow corresponds to X at the mean cell current). In other words, the charge transfer resistivity fromEIS measurements with constant oxygen flow rate is always larger than this resistivity calculated from the A. = const, polarization curve. 

Motor-driven reciprocating compressors are sometimes used in tonnage oxygen plants. To maintain a uniform output, the plant must be supplied with a constant weight flow of air. As ambient conditions change weight flow, a control system as shown in Figure 8-40(f) can be used to keep the plant supplied with the proper quantity of air. The necessary steps in this system are ... 

Piping systems should be designed for an economic flow velocity. For relatively clean fluids, a recommended velocity range where minimum corrosion can be expected is 2 to 10 fps. If piping bores exist, maximum fluid velocities may have a mean velocity of 3 fps for a 3/8-in. bore to 10 fps for an 8-in.-diameter bore. Higher flow velocities are not uncommon in situations that require uniform, constant oxygen supply to form protective films on active/passive metals. 

In this example, a fluidised biofilm sand bed reactor for nitrification, as investigated by Tanaka et al. (1981), is modelled as three tanks-in-series with a recycle loop (Fig. 1). With continuous operation, ammonium ion is fed to the reactor, and the products nitrite and nitrate exit in the effluent. The bed expands in volume because of the constant circulation flow of liquid upwards through the bed. Oxygen is supplied external to the bed in a well-mixed gas-liquid absorber. 

Although the concentric nozzle (see Fig. 1 b) and the twin set of feed autoclaves permitted the simultaneous introduction of two gases into the reaction cell, during the present experiments only one gas was introduced at a time. In most cases this was oxygen into a supercritical water-methane mixture. The oxygen flow was adjusted to constant values between 1 and 6 mm s , determined from the bellows... 

The adsorption of carbon dioxide or oxygen on praseodymium samples was measured by a constant-volume method using a calibrated Pirani vacuum gauge. Praseodymium oxide was heated in oxygen (4 kPa) at 775°C for 1 h, then evacuated at 750°C for 0.5 h just before the measurement. The sample of praseodymium oxychloride was prepared from praseodymium chloride by heating under oxygen flow... 

By varying the temperature of the precursor pot, different partial pressures of [Y(TMHD)3] could be generated, as was reflected by different values of absorbances at 200°C. Comparison of absorbance values at a temperature where decomposition was occurring, such as at 460°C (cf. Fig. 17.12(b)), with the corresponding values at 200°C then allowed determination of the order of reaction with respect to [Y(TMHD)3]. From the data plotted in Fig. 17.13 it can be seen that the reaction is first order. The data is plotted for the C=C stretch at 1571 cm-1, but a similar result was obtained for the other absorbance frequencies. For a fixed precursor partial pressure (i.e., at a constant precursor pot temperature) variation of the oxygen flow rate allowed determination of the reaction order with... 

The combustion train and recording method was developed by R. D. Goodwin (Goodwin, 19), and allows measurements to be made on individual catalyst particles, and quantities of catalyst material of 100 mg. and less. The total amount of CO2 produced at any one time is recorded vs. time on a pen recorder. The total recorder deflection reached supplies the value of initial carbon concentration Cc. The air (or oxygen) flow rate is maintained sufficiently high to provide the known constant oxygen partial pressure Co in the gas stream. The ratio n is found to be close to unity in the case of coke laid down on the porous catalysts by exposure to hydrocarbon vapors at cracking temperatures. The diffusivity is best... 

In other cases, the use of the oxygen pumps carries out in galvano-stalic mode, that is, at the constant current in circuit (4.43). Let us consider the main calculated characteristics of such pumps, which can be represented by the speed and depth of the liquid metal purification from oxygen as well as by the oxygen flow and by the time of the attainment of the set deepness of purification. 

---