Steam reforming secondary reformer

Steam-Reforming Natural Gas. Natural gas is the single most common raw material for the manufacture of ammonia. A typical flow sheet for a high capacity single-train ammonia plant is iadicated ia Figure 12. The important process steps are feedstock purification, primary and secondary reforming, shift conversion, carbon dioxide removal, synthesis gas purification, ammonia synthesis, and recovery. 

Primely and Secondary Reforming . The conversion of natural gas to synthesis gas in the reforming operation is represented by steam reforming ... 

Figure 8.3.1 is a typical process diagram for tlie production of ammonia by steam reforming. Tlie first step in tlie preparation of tlie synthesis gas is desulfurization of the hydrocarbon feed. Tliis is necessary because sulfur poisons tlie nickel catalyst (albeit reversibly) in tlie reformers, even at very low concentrations. Steam reforming of hydrocarbon feedstock is carried out in tlie priiiiiiry and secondary reformers. 

Figure 8.21 shows the scheme for producing ammonia. First, the natural gas is desulfurized and then steam-reformed in the primary reformer into a mixture of unreacted methane (10-13 %), CO, CO2, and FI2 that is then combined with air, which contains the necessary nitrogen for the ammonia process, to react in a secondary reformer. Here the oxygen reacts with hydrogen and methane in strongly... 

Steam reforming needs a secondary fuel to provide the energy supply necessary for the reaction that occurs and a catalysts to improve the kinetic of this process. In Equation (3), the primary fuel is partially oxidised by a limited amount of oxygen. Partial oxidation produces less H2 per fuel unit than stream reforming, but the kinetic reaction is faster, it requires smaller reactors and neither catalyst nor energy supply from a secondary fuel. 

Composition of Some Industrial Steam Reforming Catalysts (NG = natural gas, HC = hydrocarbon, PR = prereforming, LPG = liquefied petroleum gas, SEC = secondary reforming)... 

Here we shall briefly summarize the effects of individual poisons on various catalytic reactions taking place on automotive catalysts. There are three main catalytic processes oxidation of carbon monoxide and hydrocarbons and reduction of nitric oxide. Among secondary reactions there are undesirable ones which may produce small amounts of unregulated emissions, such as NH3, S03 (6), HCN (76, 77), or H2S under certain operating conditions. Among other secondary processes which are important for overall performance, in particular of three-way catalysts, there are water-gas shift, hydrocarbon-steam reforming, and oxygen transfer reactions. Specific information on the effect of poisons on these secondary processes is scarce. 

If the hydrogen is made by steam reforming, air is introduced at the secondary reformer stage to provide nitrogen for the ammonia reaction. The... 

For fuel cells operating at low (<100°C) and intermediate temperatures (up to 200°C), Fl2 and H2/ C02 (with minimal amounts of CO) are the ideal fuels the F12/C02 gas mixture is produced by steam-reforming/water-gas shift conversion, or partial oxidation/shift conversion of the primary or secondary organic fuels. Flydrogen is a secondary fuel and, like electricity, is an energy carrier. On a large scale, hydrogen is produced from the primary sources—natural gas, coal, or oil. For... 

Conventional steam reforming with a fired primary reformer and stoichiometric air secondary reforming (stoichiometric H/N ratio). 

Heat exchange autothermal reforming, with a process gas heated steam reformer (heat exchange reformer) and a separate secondary reformer, or in a combined autothermal reformer, using excess or enriched air (under-stoichiometric or stoichiometric H/N ratio)... 

Steam reforming refers to the endothermic, catalytic conversion of light hydrocarbons (methane to gasoline) in the presence of steam [see Eq. (5.1)]. The reforming reaction takes place across a nickel catalyst that is packed in tubes in an externally-fired, tubular furnace (the Primary Reformer). The lined chamber reactor is called the secondary reformer , and this is where hot process air is added to introduce nitrogen into the process. Typical reaction conditions in the Primary Reformer are 700°C to 830°C and 15 to 40 bar46. 

In the primary and secondary reformer the following steam reforming reaction takes place CH4 + H20 CO + 3H2... 

The mixed feed stream is given a final preheating to 430°C, and fed to the gas-heated reformer, where the feedstock is partially converted to synthesis gas by conventional membrane steam reforming (paragraph 5.1). The partially reformed gas leaves the gas-heated reformer and is fed to the secondary reformer together with enriched air and hence partially combusted. 

Ammonia manufacture from natural gas by the steam reforming process is well documented. Briefly, raw synthesis gas consisting mainly of H2, N2, and C02 is produced by primary and secondary steam reforming and CO shift conversion this is followed by bulk C02 removal, elimination of residual CO and CO2 through methanation, and ammonia synthesis. These basic steps... 

Partial oxidation, although a major source of synthesis gas in the 1940Ts, has gone out of favor in recent years due to a shortage of heavy feedstocks and the lower cost of steam reforming. However, due to its feedstock flexibility it will continue to play a growing although secondary role in synthesis gas production in the future. 

Description Natural gas or another hydrocarbon feedstock is compressed (if required), desulfurized, mixed with steam and then converted into synthesis gas. The reforming section comprises a prereformer (optional, but gives particular benefits when the feedstock is higher hydrocarbons or naphtha), a fired tubular reformer and a secondary reformer, where process air is added. The amount of air is adjusted to obtain an H2/N2 ratio of 3.0 as required by the ammonia synthesis reaction. The tubular steam reformer is Topsoe s proprietary side-wall-fired design. After the reforming section, the synthesis gas undergoes high- and low-temperature shift conversion, carbon dioxide removal and methanation. 

Description Syngas preparation section. The feedstock is first preheated and sulfur compounds are removed in a desulfurizer (1). Steam is added, and the feedstock-steam mixture is preheated again. A part of the feed is reformed adiabatically in pre-reformer (2). The half of feedstock-steam mixture is distributed into catalyst tubes of the steam reformer (3) and the rest is sent to TEC s proprietary heat exchanger reformer, "TAF-X" (4), installed in parallel with (3) as the primary reforming. The heat required for TAF-X is supplied by the effluent stream of secondary reformer (5). Depending on plant capacity, the TAF-X (4) and/or the secondary reformer (5) can be eliminated. 

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