High-temperature steam

In this accident, the steam was isolated from the reactor containing the unfinished batch and the agitator was switched ofiF. The steam used to heat the reactor was the exhaust from a steam turbine at 190 C but which rose to about 300°C when the plant was shutdown. The reactor walls below the liquid level fell to the same temperature as the liquid, around 160°C. The reactor walls above the liquid level remained hotter because of the high-temperature steam at shutdown (but now isolated). Heat then passed by conduction and radiation from the walls to the top layer of the stagnant liquid, which became hot enough for a runaway reaction to start (see Fig. 9.3). Once started in the upper layer, the reaction then propagated throughout the reactor. If the steam had been cooler, say, 180 C, the runaway could not have occurred. ... 

High temperature steam reforming of natural gas accounts for 97% of the hydrogen used for ammonia synthesis in the United States. Hydrogen requirement for ammonia synthesis is about 336 m /t of ammonia produced for a typical 1000 t/d ammonia plant. The near-term demand for ammonia remains stagnant. Methanol production requires 560 m of hydrogen for each ton produced, based on a 2500-t/d methanol plant. Methanol demand is expected to increase in response to an increased use of the fuel—oxygenate methyl /-butyl ether (MTBE). 

High temperature steam (qv) is also used for recovery of viscous cmde oils (28). Heat from the steam thins the oil, reducing viscosity and increasing mobihty. The mobilized oil is produced at offset production wells. In heavy oil fields, water flooding is often omitted and steam injection begun immediately after primary production. Steam injection temperature is typically 175—230°C in California oil fields. Injection temperature can reach 300°C in Canadian and Venezuelan EOR projects. 

High temperature steam cools and eventually condenses as it propagates through the oil reservoir. To maintain foam strength as the steam cools, a noncondensible gas, usually nitrogen or methane, is often added to the injectant composition (196). Methods of calculating the optimum amount of noncondensible gas to use are available (197). 

Thermal stabihty of the foaming agent in the presence of high temperature steam is essential. Alkylaromatic sulfonates possess superior chemical stabihty at elevated temperatures (205,206). However, alpha-olefin sulfonates have sufficient chemical stabihty to justify their use at steam temperatures characteristic of most U.S. steamflood operations. Decomposition is a desulfonation process which is first order in both surfactant and acid concentrations (206). Because acid is generated in the decomposition, the process is autocatalytic. However, reservoir rock has a substantial buffering effect. 

In theory, whole-tree-energy plants have the potential to be more efficient than existing wood-fired generators, which are fueled by chipped wood with a relatively high moisture content (45%). The dried whole trees have a moisture content below 25%, and whole-tree plants potentially can be built to have a greater capacity and to employ high pressure, high temperature steam. 

A good summary of the behavior of steels in high temperature steam is available (45). Calculated scale thickness for 10 years of exposure of ferritic steels in 593°C and 13.8 MPa (2000 psi) superheated steam is about 0.64 mm for 5 Cr—0.5 Mo steels, and 1 mm for 2.25 Cr—1 Mo steels. Steam pressure does not seem to have much influence. The steels form duplex layer scales of a uniform thickness. Scales on austenitic steels in the same test also form two layers but were irregular. Generally, the higher the alloy content, the thinner the oxide scale. Excessively thick oxide scale can exfoHate and be prone to under-the-scale concentration of corrodents and corrosion. ExfoHated scale can cause soHd particle erosion of the downstream equipment and clogging. Thick scale on boiler tubes impairs heat transfer and causes an increase in metal temperature. 

Its physical properties are very similar to those of water for instance, its melting point is f.5°C and its boiling point is 113°C. However, its chemical properties are very different. It is dangerously explosive and is normally stored and used in aqueous solution. Hydrazine is used as a rocket fuel and to eliminate dissolved, corrosive oxygen from the water used in high-pressure, high-temperature steam furnaces ... 

J. K. Borchardt and A. R. Strycker. Olefin sulfonates for high temperature steam mobility control Structure-property correlations. 

Care ill choosing the particular polymer to be employed in a frac-turing treatment is needed because some polymers can interfere with the function of the crosslinker. Some of these polymers are also stable to high temperature steam and have been successfully used to treat high temperature steam injection wells. Recent developments in organic polymer formation damage control polymers are discussed in chapter 10 of this book. 

Somewhat related is a process proposed and demonstrated on labscale by the University of Siegen (Germany). The process is called the (Herhof)-Integrierte Pyrolyse und Verbren-nung (IPV) process and is decribed in detail by Hamel et al.60 In this process, biomass is converted with high-temperature steam to pyrolysis gas in a fixed-bed reactor. The generated carbon from this reactor is led to a stationary FB combustor from which the hot ash is returned to the first-mentioned reactor. The ash works catalytically to reduce the tar content of the gas produced. The gas is further cleaned and conditioned using a scrubber and electrostatic filter from which the catch is returned to the FB combustor. 

The steam reformer process involves the reaction of methane and high temperature steam in the presence of a nickel catalyst. The reactions are... 

Butadiene is made by the gas phase catalytic deydrogenation of 1-butene. In order to suppress side reactions and to maintain the temperature level, high temperature steam is added to the feed. The reactor pressure is 2 atm and the feed consists of 12 mol of steam per mol of butene. The equilibrium constant as a function of temperature is K = exp(14.3417 - 13997/T)... 

J.E. O Brien, J.S. Herring, P.A. Lessing, and C.M. Stoots, High Temperature Steam Electrolysis from Advanced Nuclear Reactors using Solid Oxide Fuel Cells, presented at the First International Conference on Fuel Cell Science, Engineering, and Technology, Rochester, NY, April 21-23, 2003. 

Table 4 Selected best performing catalysts for the middle-, and high-temperature steam reforming of ethanol (SRE) reaction"...

High temperature short time (HTST) continuous sterilization, in fermentation, 11 35-36, 45 High temperature steam electrolysis, 13 784... 

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