Reformate flow rate

A reformate flow rate of 25-175 Ndm3 min-1, simulating methanol steam reformer product gases, and 2.5-17.5 Ndm3 min-1 air were fed to the reactors. The simulated reformate was composed of 68.9% H2, 0.6% CO, 22.4% C02, 6.9% H20 and 0.4% CH3OH, the last to simulate incomplete conversion. The carbon monoxide output of the single reactors and of both switched in series is shown in Figure 2.72. The CO output of the two reactors switched in series was <10 ppm and the optimum air volume split between the first and second reactors was determined as 70/30. 

For reformate flow rates up to 400 Ndm3 min-1, the CO output was determined as < 12 ppm for simulated methanol. The reactors were operated at full load (20 kW equivalent power output) for -100 h without deactivation. In connection with the 20 kW methanol reformer, the CO output of the two final reactors was < 10 ppm for more than 2 h at a feed concentration of 1.6% carbon monoxide. Because the reformer was realized as a combination of steam reformer and catalytic burner in the plate and fin design as well, this may be regarded as an impressive demonstration of the capabilities of the integrated heat exchanger design for fuel processors in the kilowatt range. 

Figure 2.87 PrOx reactor CO output vs. reformate flow rate for three reactor heat exchanger (HEX) designs [88] (by courtesy of Elsevier Ltd.).

Figure 14.25 (a) Cocurrently operated microreactor for preferential oxidation cooled by water evaporation, (b) CO concentration in the off-gas of the reactor at different total reformate flow rates, CO inlet concentrations and O/CO values [167],... 

Figure 5.34 Hydrogen partial pressure along the length axis of a membrane tubular reactor operated in parallel (a) and counter-flow (b) arrangements solid lines, retenate partial pressure dashed lines, permeate partial pressure reformate flow rate, 162cm min reformate pressure, 1.36 bar sweep gas flow rate, 40cm min permeate pressure, 1.01 bar left, reaction temperature 300°C right, reaction temperature 500°C [411].

Figure 5.66 Feedback control strategy for a small-scale methanol fuel processor the reformate flow rate is measured and used for system control [453].

Table 7.2 summarises some of the results generated for various fuels. Load changes of the liquid feed flow rate from 100 to 10% changed the reformate flow rate within 5 to 10 s. 

The catalytic reforming of CH4 by CO2 was carried out in a conventional fixed bed reactor system. Flow rates of reactants were controlled by mass flow controllers [Bronkhorst HI-TEC Co.]. The reactor, with an inner diameter of 0.007 m, was heated in an electric furnace. The reaction temperatoe was controlled by a PID temperature controller and was monitored by a separated thermocouple placed in the catalyst bed. The effluent gases were analyzed by an online GC [Hewlett Packard Co., HP-6890 Series II] equipped with a thermal conductivity detector (TCD) and carbosphere column (0.0032 m O.D. and 2.5 m length, 80/100 meshes), and identified by a GC/MS [Hewlett Packard Co., 5890/5971] equipped with an HP-1 capillary column (0.0002 m O.D. and 50 m length). 

Fig. 6. The effects of total flow rate of tiiels (CH4/CO2 = 1) on the inpedance in the internal reforming of CH4 by CO2 over ESC (NiO-YSZ-Ce02 I YSZ I (LaSrlMnOs) of SOFC system.

The catalyst (0.15 g) was loaded into a quartz tube reactor (internal diameter = 4 mm). The catalyst was pretreated in nitrogen at 400°C. Simulated gasoline reformate was used for the activity test of the catalyst. The composition of the simulated reformate was 36 wt% H2, 17 wt% CO2, 28 wt% N2, 17 wt% H2O, 1 wt% CO, and air was added additionally as the oxidant. The total flow rate was maintained at 100 ml/min. The test was performed over the temperature range of 120 280°C at various flow rates of inlet air. 

In the model equations, A represents the cross sectional area of reactor, a is the mole fraction of combustor fuel gas, C is the molar concentration of component gas, Cp the heat capacity of insulation and F is the molar flow rate of feed. The AH denotes the heat of reaction, L is the reactor length, P is the reactor pressure, R is the gas constant, T represents the temperature of gas, U is the overall heat transfer coefficient, v represents velocity of gas, W is the reactor width, and z denotes the reactor distance from the inlet. The Greek letters, e is the void fraction of catalyst bed, p the molar density of gas, and rj is the stoichiometric coefficient of reaction. The subscript, c, cat, r, b and a represent the combustor, catalyst, reformer, the insulation, and ambient, respectively. The obtained PDE model is solved using Finite Difference Method (FDM). 

A PAFC, operating on reformed natural gas (900 Ib/hr) and air, has a fuel and oxidant utilization of 86% and 70% respectively. With the fuel and oxidant composition and molecular weights listed below, (a) How much hydrogen will be consumed in lb mol/hr (b) How much oxygen is consumed in lb mol/hr (c) What is the required air flow rate in lb mol/hr and Ib/hr (d) How much water is generated (e) What is the composition of the effluent (spent) fuel and air streams in mol % ... 

Microreactors with the thin film catalyst deposited as described were repetitively tested across a wide temperature range. The feed was composed of 1.7% CO, 68% H2, and 21% CO2 with N2 as the balance. The flow rate was maintained at 5 Ncm3/min ( 0.6 Wt) which the researchers believed would be enough for a 0.5 Wg fuel cell. However, using the DOE assumptions (45% for reformer systems), this would translate into approximately 0.27 W.7 After each... 

Note Typically in reformer design, liquid hourly space velocity (LHSV) is defined as fresh liquid charge volumetric flow rate divided by catalyst volume. Catalyst volume includes the void fraction and is defined by WJpp( — e).]... 

Here iii " and mout denote the mass flow rate of the mixture entering from the inlet and leaving from the outlet respectively. Rate of consumption and rate of production of each species A is denoted by m sed and mv d. These rates include the flux of reactants, which take part in electrochemical reactions, across the chan-nel/electrode interfaces and also the consumption and production of species due to methane reforming reaction on the anode side. Both hydrogen and carbon monoxide electrochemistry was considered and it was assumed that n2, the fraction of the current that is produced from H2 oxidation, is known. Thus the specie consump-... 

An example of a system transient is shown in Figure 9.3. The figure shows a 20 amp load increase on a nominal 3 kW SOFC system using a stream-reformed methane fuel. Stack load current, stack voltage, and input fuel flow rate are shown. Here, the system is pre-warmed to the conditions shown (ca. 20 amps), following which the controller permits exporting more power to a load at the ramp rate shown. As the transition occurs, numerous other system variables also adjust, some in direct response to the increase in load, and others imposed by the control system in order to keep all system components within their design limits. 

The experiments were carried out at a pressure of 1.5 bar and a flow rate of 80-270 Ncm3 min-1. At 200 °C no deactivation of the catalyst was observed. As the rate of reaction was found to show a linear dependence on the residence time, differential conditions were assumed for the measurements. Because of the determined high activation energy of 5 6 kj mol-1, mass transport limitations were excluded. A power law kinetic expression of the following form was determined for methanol steam reforming ... 

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