Operating conditions reforming

NOx reformer operating conditions —Condenser maximum temperature —Oxygen feed rate... 

Table 3. Vaporizer and Reformer Operating Conditions and Performance (Adapted from ref 88)...

TABLE 2. The investigated ranges of reformer operating conditions... 

If benzene is the main product desired, a narrow light naphtha fraction boiling over the range 70 to 104°C is fed to the reformer, which contains a noble metal catalyst consisting of, for example, platinum-rhenium on a high-surface-area alumina support. The reformer operating conditions and type of feedstock determine the amount of benzene that can be produced. The benzene product is most often recovered from the reformate by solvent extraction techniques. 

The amount of xylenes contained in the catalytic reformate depends on the fraction and type of crude oil, the reformer operating conditions, and the catalyst used. The amount of xylenes produced can vary widely, typically... 

The Methane Slip (or % Methane that is not converted) has a big influence on the selection of reformer operating conditions. As shown in Figure 5.8, the best operating conditions will be within the following ranges ... 

These reactions are reversible, and there is a dynamic equilibrium between carbon formation and removal. Under typical steam reforming conditions, reactions (46) and (48) are carbon - removing, whilst reaction (47) leads to carbon formation in the upper part of the tube [503]. With naphtha as steam reformer feed, irreversible pyrolysis (as in a steam cracker for ethylene production) with the sequence naphtha —> olefins—> polymers—- coke will occur. The mechanism of carbon formation and the determination of the risk areas in the reformer operating conditions on the basis of relevant equilibrium data are discussed in some detail in various publications [362], [363], [418]-[420]. 

In the usual situation where the C5+ yield is greater for the platinum-rhenium catalyst than for the platinum-iridium catalyst, the debit in C5 + yield for the latter is substantially decreased when part of the catalyst at the front of the system is replaced by platinum-rhenium catalyst. In general, comparison of either catalyst alone with a combined catalyst system will depend on the naphtha being reformed, the reforming operating conditions, and also on the relative amounts of the two catalysts employed in the combined system. 

In indirectly heated reformers operating conditions may vary considerably, but the requirements to the catalyst are similar to those in the tubular reformer. The catalyst activity must be larger for low-temperature adiabatic prereformers, where catalyst effectiveness factors will be outside the strongly diffusion-controlled regime. This implies that a simplified activity expression as in Figure 3.3 is not valid for a prereformer. In an autothermal reformer the requirements to the catalyst includes high temperature stability properties and a good distribution over the catalyst bed of the partly converted gas from the burner. In micro-scale reactors catalyst stability is a major issue. 

The autothermal reformer operating conditions were set to a S/C ratio of 2 and O/C ratio 0.73. The residual hydrogen from the anode was combusted in an afterburner. The thermal and compression energy ofthe hot combustion gases was used for two purposes firstly, to evaporate water similar to the design of Cutillo et al. described above and secondly, to drive an expander turbine directly connected to the compressor shaft and recovering energy for compression. In a practical 5-kW system this is unlikely to work, because pressure drops in the components will leave little space for... 

TABLE 9.9. Steam Reforming Operating Conditions with Natural Gas. 

Naphtha desulfurization is conducted in the vapor phase as described for natural gas. Raw naphtha is preheated and vaporized in a separate furnace. If the sulfur content of the naphtha is very high, after Co—Mo hydrotreating, the naphtha is condensed, H2S is stripped out, and the residual H2S is adsorbed on ZnO. The primary reformer operates at conditions similar to those used with natural gas feed. The nickel catalyst, however, requires a promoter such as potassium in order to avoid carbon deposition at the practical levels of steam-to-carbon ratios of 3.5—5.0. Deposition of carbon from hydrocarbons cracking on the particles of the catalyst reduces the activity of the catalyst for the reforming and results in local uneven heating of the reformer tubes because the firing heat is not removed by the reforming reaction. 

Selection of the high pressure steam conditions is an economic optimisation based on energy savings and equipment costs. Heat recovery iato the high pressure system is usually available from the process ia the secondary reformer and ammonia converter effluents, and the flue gas ia the reformer convection section. Recovery is ia the form of latent, superheat, or high pressure boiler feedwater sensible heat. Low level heat recovery is limited by the operating conditions of the deaerator. 

The predominant feeds for reforming are straight-mn naphthas from cmde stills. Naphthas from catalyst crackers and naphthas from code stills are also used. Typical compositions are summarized in Table 5. Typical operating conditions for catalytic reforming are 1.135—3.548 MPa (150—500 psi),... 

C, 0.356—1.069 m H2/L (2000—6000 fU/bbl) of Hquid feed, and a space velocity (wt feed per wt catalyst) of 1—5 h. Operation of reformers at low pressure, high temperature, and low hydrogen recycle rates favors the kinetics and the thermodynamics for aromatics production and reduces operating costs. However, all three of these factors, which tend to increase coking, increase the deactivation rate of the catalyst therefore, operating conditions are a compromise. More detailed treatment of the catalysis and chemistry of catalytic reforming is available (33—35). Typical reformate compositions are shown in Table 6. 

Proper choice of feedstocks and use of relatively severe operating conditions ia the reformers produce streams high enough ia toluene to be directiy usable for hydrodemethylation to benzene without the need for extraction. 

Most of the benzene in the gasoline pool comes from the reformer unit (reformate). To reduce the reformate s benzene, one must modify the feedstock quality and/or operating conditions. Benzene s precursors in the reformer feed (C, and C ) can be prefractionated and sent to an isomerization unit. The reformer operating pressure can be reduced... 

Fig. 5. Change of the open-circuit potential with time for steam reforming of methanol over the 30 wt% Ni-SDC and 30 wt% Ni-YSZ electrode-catalyst. Upper Ni-SDC lower Ni-YSZ. Operating conditions 800 °C, 1 atm, H20/CH30H = 2, space time = 0.37 s [9].

Where two numbers are given, the first number represents average operating conditions while the second number represents maximum operating conditions. Catalytic reformer service. 

In a petroleum refinery a large number of different products are produced, and the demand for some of these products is seasonal. For instance, there is not much need for residential fuel oil in the summer. The price of products also varies from day to day. To optimize the company s profit, it is therefore necessary periodically to vary the amount of each product produced. This can be done by changing the amounts of material sent to cracking units and reformers and by changing the conditions in these and other process steps. Some petroleum companies provide a computer with the data on market prices, current inventories, and crude oil compositions. The computer output then specifies the operating conditions that will yield the greatest profit for the company. The computer could then make the changes in these conditions directly, or this could be done manually. 

Although considerable research has been conducted with Pd-alloy foils, tubes, and thinner composite membranes, long-term durability and stability need to be further demonstrated, especially in the fuel reforming or WGS operating conditions, for acceptance of this technology in a commercial sector. Furthermore, mass-scale and cost-effective production of industrial-scale Pd-alloy thin-film composite membranes need to be demonstrated to be competitive in the hydrogen production and purification market. 

The CFD calculations of the present work used conditions and compositions from a Johnson Matthey detailed reformer model of a methanol plant steam reformer with upwards flow, at typical operating conditions. Conditions were chosen corresponding to three different axial positions along the tube, to reflect reaction rates typical of those close to the inlet, midway down the tube and close... 

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