Steam hydrocarbon reforming reformer

Fired reactors contain tubes or coils in which an endothermic reaction within a stream of reac tants occurs. Examples include steam/ hydrocarbon reformers, catalvst-filled tubes in a combustion chamber pyrolyzers, coils in which alkanes (from ethane to gas oil) are cracked to olefins in both types of reac tor the temperature is maintained up to 1172 K (1650°F). 

Preparation. Many reactions and processes are available for the preparation of hydrogen. Among the large-scale processes, the catalytic steam hydrocarbon reforming process can be mentioned. After de-sulphurization, natural gas (or oil-refinery feedstock) is mixed with steam and, at 700-1000°C, passed over a nickel-based catalyst. The irreversible reaction occurs ... 

In tlie steam-hydrocarbon reforming process, steam at temperatures up to 850°C and pressures up to 30 atmospheres reacts with the desulfurized hydrocarbon feed, in the presence of a nickel catalyst, to produce H2. CO, ( G CH4, and some undecomposed steam. In a second process stage, these product gases are further reformed. Air also is added at this stage to introduce nitrogen into the gas mixture. The exit gases from this stage are further puntied to provide the desired 3 parts H. to 1 part Nj which is the correct empirical ratio for NH3 synthesis. See also Ammonia. 

At present, hydrogen is produced mainly by the steam-hydrocarbon reforming process (Section 14.3). This method can contribute to global warming because it produces C02 as a by-product. It may be possible, however, to capture the C02 and sequester it in depleted gas wells or deep saline aquifers, thus avoiding addition of C02 to the atmosphere. 

The Primary Reformer is a steam-hydrocarbon reforming tubular furnace that is typically externally fired at 25 to 35 bar and 780°C to 820°C on the process side. The reformer tubes function under an external heat flux of 75,000 W/m2 and are subject to carburization, oxidation, over-heating, stress-corrosion cracking (SCC), sulfidation and thermal cycling. Previously SS 304, SS 310 and SS 347 were used as tube materials. However these materials developed cracks that very frequently led to premature tube failures (see Table 5.10)88. 

Thus, although hydrogen is used in methanol production, it can be taken straight from the steam-hydrocarbon reformer and does not require further purification and treatment as in the case of pure hydrogen production or ammonia production. The economics of methanol production are significantly affected by the thermal integration of the reformer (or other gas generation unit) with the rest of the plant. 

The primary reformer is a steam-hydrocarbon reforming tubular furnace that is typically externally fired at 25 to 35 bar and 780°C to 820°C on the process side. From the 1950s through the 1960s SS 304, SS 310, SS 347,... 

Description The catalytic-steam hydrocarbon reforming process produces raw synthesis gas by steam reforming in a heat exchange-based system under pressure based on the Kellogg Brown Root Reforming Exchange System (KRES). 

R.G. Minet and T.T. Tsotsis, Catalytic membrane steam/hydrocarbon reformer. U.S. Patent 4,981,676, January 1,1991. 

Table III. Patents Incorporating Steam-Hydrocarbon Reforming...

The carbon monoxide-hydrogen mixture traditionally was generated from coke, steam, and air by the water-gas method, but this process has been supplanted by steam-hydrocarbon reforming and by the partial oxidation of natural gas. More recently, processes for producing synthesis gas by the partial oxidation of pulverised coal have been introduced. 

Steam-hydrocarbon reforming has become the most frequently used method for synthesis gas preparation, and usually natural gas, treated to remove all com-... 

The steam-hydrocarbon reforming process is highly developed and will operate for months or even years without interruption, except for normal outages scheduled for boiler inspection, routine maintenance, and other attention which is placed on a definable schedule. The heat balance and utilization are well engineered ordinarily so that there is little waste, and what heat is unused on the furnace side of the reformer is subsequently recovered for use to generate steam. 

The steam-carbon dioxide-hydrocarbon conversion is conducted over a catalyst such as nickel (oxide) on alumina. This type of catalyst can be purchased in quite similar composition from a number of catalyst vendors. In the case in which the feed stock is processed over a catalyst as in steam-hydrocarbon reforming, it is essential that the gas be purified, at least to some extent, prior to its passage over the reforming catalyst, particularly if the catalyst is of the typical composition of supported and promoted nickel (oxide). In steam hydrocarbon reforming, the methane (natural gas) is usually detoxified using an adsorbent such as carbon on which is impregnated suitable chemical adsorbents such as elemental iron or copper. There are at least two of these metallized carbon desulfurizers in parallel with one on... 

Unrefined carbon dioxide gas is obtained from the combustion of coal, coke, natural gas, oil, or other carbonaceous fuels from by-product gases from steam-hydrocarbon reformers, lime kilns, and so on from fermentation processes and from gases found in certain wells and natural springs. The gas obtained from these sources is liquefied and... 

Singh, C. P. P. Saraf, D. N., Simulation of Side Fired Steam-Hydrocarbon Reformers,... 

Steam/hydrocarbon reforming Waste water treatment... 

Due to clean-fuel regulations, many refineries are implementing hydrogen recovery/purification projects and/or installing steam/hydrocarbon reformers to generate on-purpose hydrogen. 

Steam is generated by boilers and heat-producing process units. FCC units, Claus units, and steam/hydrocarbon reformers (hydrogen plants) are major sources of refinery steam. 

The feed gas for a steam-hydrocarbon reformer can be natural gas, refinery off-gas, or a mixture of the two. The feed gas is desulfurized, mixed with... 

The most common industrial preparation of hydrogen is the catalytic steam-hydrocarbon reforming process [Equations (10.7) and (10.8)] ... 

Adsorption is a viable option for hydragoi sulfide removal whrai the amount of sulfur is very small and the gas contains heavier sulfur conpounds (such as mercqitans and carbon disulfide) that must also be removed. For adsorption to be the preferred process for carbon dioxide ranoval, there must be a high CO partial pressure in the feed, the need for a very low concentration of carbon dioxide in the product, and the presence of otho- gaseous impurities that can also be removed by the adsorbent Typical examples are the purification of hydrogen fiom steam-hydrocarbon reforming, (he purification of land-fill efftuoit gas, and the purification of ammonia synthesis gas. Adsorption processes are described in detail in Chapter 12. 

Molecular sieves have also found application for desulfurization of natural-gas feed to ammonia plants. Removal of all types of sulfur compounds ahead of these plants is desirable because sulfur acts as a temporary poi.son to steam-hydrocarbon reforming catalysts and a permanent poison to expensive low-temperature shift conversion catalysts. An installation employing a standard dual bed adsorption system has been described by Lee and Collins (1968). The authors also describe comparative tests of a molecular sieve and a commercial grade of impregnated activated carbon in a dual-bed mobile pilot unit. The test results indicated that the molecular sieve could treat 2 to 4 times as much gas per unit volume of adsorbent as the carbon. The commercial plant consistently provided gas to the primary reformer containing less than 0.3 ppm (vol) peak total sulfur from a feed gas averaging about 0.6 ppm... 

High-Temperature Nonregenerative Processes. For many years zinc oxide has been the preferred sorbent for removing traces of hydrogen sulfide from natural gas feed to steam-hydrocarbon reformers producing synthesis gas for the production of ammonia and other petrochemicals. The zinc oxide is typically in the fotm of cylindrical extiudates 3-4 nun in diameter and 4-8 mm in length. Several forms are available for operation at temperatures from about 400° to 750°F. 

---