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Hydrocarbon steam reforming is one of the most important processes of heavy chemical synthesis. High volume velocities and heat loads are used in modern reformers and working parameters of catalytic tubes are very hard. Life time of tubes depends on maximal wall temperature which is influenced mainly by: the catalyst activity, the gas purity and a non-uniformities in the gas flow. The effect of a non-uniform gas flow through catalytic tubes on reformer performance are presented. Catalysts used nowadays have very good and stable mechanical properties. Nevertheless, gas flow resistance grows gradually during the operation of the reformer. Most often the catalyst is damaged during shut-down operation when it undergoes the influence of strong forces caused by tube dilatation. We have made statistical analysis of resistance changes in individual tubes assuming that they are random and a total resistance of the reformer is calculated as an equivalent resistance of a system the tubes connected parallely. We calculated wall temperature increase caused by reduced gas flow using an appropriately modified program for reformer simulations. An analysis of operational data and of results of the simulations indicates that the differences in gas flow can cause wall temperature increase by about 20 degrees centigrade. In extreme cases, it can shorten tube life-time by a half.
Two basis types of synthesis gas obtainment units are found in the major part of domestic ammonia production plants. One of the systems includes primary reformer, secondary reformer and a heat recovery subsystem (ZAT, ZCh Police, ZAW, Puławy II). The other one consists of natural gas cracker and heat recovery subsytem (ZAK, Puławy I). The main controllable parameter at the inlet of the above mentioned units is C/H2O ratio. Entire cost of the synthesis gas obtainment is also influenced by prices of the raw materials (natural gas, steam, oxygen), as well as by the equipment design. Following computer implementation, mathematical models of the above mentioned equipment arising from our own investigations have been included to the "TAWAS" package [1], which enabled to analyse performance of the sections by computer simulation. The results obtained have provided both the guidelines to offers for modernization of the synthesis gas obtainment sections and the data to operate the existing.
A proper selection of steam reforming catalyst geometry has a direct effect on the efficiency and economy of hydrogen production from natural gas and is a very important technological and engineering issue in terms of process optimisation. This paper determines the influence of widely used seven-hole grain diameter (ranging from 11 to 21 mm), h/d (height/diameter) ratio of catalyst grain and Sh/St (hole surface/total cylinder surface in cross-section) ratio (ranging from 0.13 to 0.37) on the gas load of catalyst bed, gas flow resistance, maximum wall temperature and the risk of catalyst coking. Calculations were based on the one-dimensional pseudo-homogeneous model of a steam reforming tubular reactor, with catalyst parameters derived from our investigations. The process analysis shows that it is advantageous, along the whole reformer tube length, to apply catalyst forms of h/d = 1 ratio, relatively large dimensions, possibly high bed porosity and Sh/St ≈ 0.30-0.37 ratio. It enables a considerable process intensification and the processing of more natural gas at the same flow resistance, despite lower bed activity, without catalyst coking risk. Alternatively, plant pressure drop can be reduced maintaining the same gas load, which translates directly into diminishing the operating costs as a result of lowering power consumption for gas compression.
Dokonano oceny zmniejszenia zużycia energii w wytwórni gazu do syntezy amoniaku w wyniku zastosowania nowego aktywatora roztworu węglanu potasu w procesie wymywania C02 z gazu procesowego (proces Benfield). Proces ten polega na absorpcji C02 z gazu w gorącym (80-100°C) wodnym roztworze węglanów potasu z dodatkiem aktywatora (najczęściej dieta-noloaminy). Absorpcja prowadzona jest pod ciśnieniem 2-3 MPa, natomiast regeneracja roztworu (desorpcja CO2) przebiega w temp. 110-125°C pod zmniejszonym ciśnieniem 0,12-0,18 MPa oraz z użyciem pary stripingowej. Proces zużywa duże ilości ciepła do regeneracji roztworu oraz energii do napędu pomp utrzymujących cyrkulację roztworu pomiędzy absorberem i regeneratorem.
Use of a new activator of K2C03/KHC03 soin. in absorption of C02 (Binczak et ai., 2014) resulted in a decrease of natural gas consumption in NH3 prodn. (ca. 22 t/h) by 5 m3/t of NH3.
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