7 Thermodynamic Balance and Analysis of a Synthesis Gas and Ammonia Plant
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H E L M U T CREMER Fichtner Consulting Engineers, Boxgraben 79, 5100 Aachen, Federal Republic of Germany
It is not intended to discuss the specific problems of the synthetic ammonia production but to localize those areas of an industrial chemical process which cause consumptions. The analysis comprises the synthesis gas plant using methane in a reforming process and the ammonia production. The use of methane is an arbitrary choice. The analysis of the coupled processes is necessary to give a r e a l i s t i c impression and to allow a qualified judging of the units and systems. The t o t a l plant discussed in this paper is not self-sufficient whereas independent operation is preferred in practice; this is rather influenced by service requirements than by thermodynamic considerations. The Process The simplified flowsheet of the coupled synthesis gas and ammonia plant is shown in Fig. 1. The streams are numbered from 1 to 44 and are l i s t e d in Table I and Table II;Table I refers to the reactant and product streams especially. The units of the process may be identified by Table III. The flowsheet and data refer to a plant with an ammonia production of 1,000 tons per day and can be found in detail in chemi c a l engineering textbooks. A l l data are conservative. Some minor discrepancies in the mass streams result from the data cards but do not influence the results significantly. The upper part of Fig. 1 shows the synthesis gas plant which is fed from the right-hand side with methane (stream l ) and a i r (stream 2) for a combustion process to match the heat requirements of the synthesis gas process. The combustion process delivers the exhaust gas (stream 3 ) . The synthesis gas is produced by methane, water vapor and a i r (streams 5 , 6 ) in a primary and secondary reformer and a converter (units REF1, REF2 and CON). The raw gas (stream 2 8 ) passes the gas conditioning (SEPl) which has been detailed in Fig. 3 and the synthesis gas (stream 2 9 ) enters the ammonia plant shown in the lower part of Fig. 1. The ammonia
0-8412-0541-8/80/47-122-lll$05.00/0 © 1980 American Chemical Society In Thermodynamics: Second Law Analysis; Gaggioli, R.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
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112
THERMODYNAMICS: SECOND LAW ANALYSIS
Figure 1.
Synthesis gas and ammonia plant (simplified flowsheet)
In Thermodynamics: Second Law Analysis; Gaggioli, R.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
Downloaded by UNIV OF PITTSBURGH on May 3, 2015 | http://pubs.acs.org Publication Date: May 28, 1980 | doi: 10.1021/bk-1980-0122.ch007
7.
CREMER
Synthesis
Figure 2.
Gas and Ammonia
113
Fiant
T/Q diagram (temperature/heat flow) cooling of combustion gas
TEA
A "
fC2
synthesis gas ;Q
