Hydrogen separation from gaseous product of the process of high temperature conversion of coke-oven gas
 
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Polityka Energetyczna – Energy Policy Journal 2009;12(2):577–591
 
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ABSTRACT
Industrial gaseous streams produced in various chemical processes are very attractive source of hydrogen. Their composition, temperature and pressure are, however, diversified so that a process of hydrogen separation from these streams has to be developed separately for each specific case. The hydrogen separation is performed very often in the pressure swing adsorption (PSA) process. In the present paper hydrogen recovery from the gaseous product of the process of the high-temperature conversion of coke-oven gas was investigated theoretically. The mathematical model was then developed to study the PSA separation process (Eqs 1-12). Four-bed PSA unit was considered with two adsorbent layers (activated carbon BA-10 Raciborz and zeolite 5A Zeochem). Adsorbent properties was given in Table 1 and the appropriate equilibrium and kinetic data was presented in Tables 2-5. Feed gas to the PSA process consisted of H2: 72.1%, CH4: 2.5%, CO: 19.1% and CO2: 6.3 %. The PSA cycle was presented in Fig. 1. The PSA process efficiency, described by hydrogen purity, recovery (Eq. 13) and productivity (Eq. 14), was checked against feed gas pressure, temperature and flow rate, and LWA/L ratio. In Figs 2-4 exemplary results of simulations were presented for the feed gas flow rate of 7.5 mn3/h and temperature of 303K. The dependence of the process efficiency on temperature is presented in Figs 5-7 for the feed gas flow rate of 7.5 mn3/h and LWA/L=0,5. It was found that if the feed gas flow rate in the adsorption step does not exceed 7,5 mn3/h (v?2 cm/s) and LWA/L=0,5 pure hydrogen with the recovery greater than 66% is produced at the rather low pressure 10 bar. It was also concluded that the hydrogen recovery decreases when pressure in the adsorption step is increased. On the other hand the recovery is greater for lower length of the active carbon bed (LWA). It was also found that at temperature of the feed gas lower than 30oC the hydrogen recovery decreases. At temperature of the feed gas greater that 30oC the feed gas pressure has to be greater than 10 bar in order to obtain pure hydrogen in the adsorption step. The possible way of further processing of the waste gas from the PSA installation was also discussed which includes the water gas shift reaction and the H2/CO2 separation in the hybrid process.
METADATA IN OTHER LANGUAGES:
Polish
Wydzielanie wodoru z mieszanin gazowych powstałych w procesie wysokotemperaturowej konwersji gazu koksowniczego
wytwarzanie wodoru, adsorpcja zmiennociśnieniowa, gaz koksowniczy, reforming
Jednym z bardziej atrakcyjnych, alternatywnych do gazu ziemnego, źródeł wodoru są strumienie gazów przemysłowych generowanych w różnych procesach chemicznych. Biorąc pod uwagę znaczne zróżnicowanie tych strumieni względem stężenia wodoru, temperatury i ciśnienia, proces wydzielania wodoru z takich mieszanin musi być projektowany indywidualnie do każdego przypadku. W niniejszej pracy przedstawiono wyniki wielowariantowych obliczeń symulacyjnych procesu wydzielania wodoru z produktu wysokotemperaturowej konwersji gazu koksowniczego metodą adsorpcji zmiennociśnieniowej. Stwierdzono m.in. że, przy natężeniu przepływu gazu zasilającego w kroku adsorpcji nie wyższym niż 7,5 mn3/h i stosunku LWA/L=0,5 można uzyskać czysty wodór przy stosunkowo niskim ciśnieniu 10 bar ze sprawnością odzysku przekraczającą 66%.
 
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ISSN:1429-6675