Synthesis gas composition

Synthesis Gas Preparation Processes. Synthesis gas for ammonia production consists of hydrogen and nitrogen in about a three to one mole ratio, residual methane, argon introduced with the process air, and traces of carbon oxides. There are several processes available for synthesis gas generation and each is characterized by the specific feedstock used. A typical synthesis gas composition by volume is hydrogen, 73.65% nitrogen, 24.55% methane, <1 ppm-0.8% argon, 100 ppm—0.34% carbon oxides, 2—10 ppm and water vapor, 0.1 ppm. 

Table 6. Synthesis Gas Compositions from Gasifiers Operating on Western U.S. Coals...

The effect of synthesis gas composition on conversion, catalyst life, carbon black formation, etc. was determined in numerous tests. Characteristic variables in the synthesis gas composition are the H2/CO ratio, residual C02 content, and content of trace components in the form of higher hydrocarbons and catalyst poisons. 

Table 12-1 Synthesis gas composition (percent yield based on methane feed)...

The need to shift the gas introduces an additional process step, so increasing overall the process complexity. In cases where the required synthesis gas composition can be achieved directly in the gasifier, this may be preferred in the interest of reducing the complexity. 

Typical Synthesis Gas Composition H2/CO (% Molar Concentration) Method of Manufacture Molar Ratio H2 CO C02... 

In a third experiment, 300 p.s.i. (20 atm.) of carbon monoxide was added giving an initial synthesis gas composition of about 7H2 lCO. After heating the reaction mixture for 2 hours at 185° and securing no... 

Future widespread use of anthropogenic C02 in combination with renewable hydrogen as well as the implementation of coal, biomass, and other nonconventional sources of synthesis gas will lead to suboptimal synthesis gas compositions. Efficient incorporation of these synthesis gas mixtures into the current methanol synthesis infrastructure will necessitate the redevelopment of catalysts to perform stably under high concentrations of C02, water, and impurities. To that end, advanced characterization methods must be implemented to discriminate between surface area loss by... 

Description The gas feedstock is compressed (if required), desulfurized (1) and process steam is added. Process steam used is a combination of steam from the process condensate stripper and superheated medium pressure steam from the header. The mixture of natural gas and steam is preheated, prereformed (2) and sent to the tubular reformer (3). The prereformer uses waste heat from the flue-gas section of the tubular reformer for the reforming reaction, thus reducing the total load on the tubular reformer. Due to high outlet temperature, exit gas from the tubular reformer has a low concentration of methane, which is an inert in the synthesis. The synthesis gas obtainable with this technology typically contains surplus hydrogen, which will be used as fuel in the reformer furnace. If C02 is available, the synthesis gas composition can be adjusted, hereby minimizing the hydrogen surplus. Carbon dioxide can preferably be added downstream of the prereformer. 

Fig. 6. Influence of synthesis gas composition on cycle length of zeolite (HZSM-5) catalyst. The cycle length is expressed as the amount of MeOH equivalents (EME = 2 MeOH) processed1 during a cycle by 1 kg of catalyst.

Fig. 7. Influence of synthesis gas composition on oxygenate catalyst volume.

Fig. 8. Influence of synthesis gas composition on recycle flow rate. The production of gasoline is kept constant for all values of the module.

Table 3 Synthesis Gas Composition (in vol. %) in the Steam Methane Reforming Process (Dry Basis)...

The basic requirements to synthesis gas composition for fuel cell test at FCTl are shown in Table 1. 

For low purity hydrogen product (eg, for refinery applications), a methana-tion unit, to convert unreacted methane, may be present as well. In the case of pure CO, the CO is separated from the hydrogen by a cryogenic separation step or a cold box. In addition, a membrane unit may be employed to tune the synthesis gas composition to the required ratio. Various compression steps may also be present to deliver the product at the desired pressure. 

The synthesis gas composition depends on the raw material and on the process used in the synthesis gas preparation. Three examples... 

Final purification by methanation followed by adjustment of synthesis gas composition (removal of excess nitrogen and part of the inerts) in a cryogenic unit (referred to as the Braun purifier). Gas drying upstream of the purifier. 

FIGURE 4.5 Effect of pressure and temperature on synthesis gas composition. 

FIGURE 4.9 Effect of O2/VR on carbon conversion and synthesis gas composition (P = 11... 

At the operating conditions of the model validation (P = 11 bar, T = 1260°C, and OJVR = 1.0637), the effect of H2O/V/ ratio in the range of 0.2-1.0 on synthesis gas composition was studied, and the simulation results are depicted on Figure 4.10. This figure shows that when increasing the H2O/V7 ratio, the excess water that is not reacting increases, while the production of H2 and CO decreases particularly the reduction of CO is significant. 

With the increase in the H20/VP ratio, carbon conversion increases and reaches 100% due to the carbon-steam reaction. In the carbon-steam reaction and the conversion of CO, when the amount of water increases, both reactions proceed in such a direction that the amount of Hj is increased. These two reactions occur on the left-hand side of the dotted vertical line, so after all the solid carbon is depleted, only the CO conversion reaction continues. The changes in the synthesis gas composition... 

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