Carbon dioxide removal in indirect gasification - SGC

SGC Rapport 2013:277
Figure 2. Single-pass throughwall cooled methanation process [1].
2.2.3 Fluidized-bed reactor
Methanation as well as other highly exothermic processes can favorably be carried
out in a fluidized reactor. The main advantages with fluidized bed reactors are;
evenly dispersed catalyst and reactant gases, low thermal gradients and thus better
temperature control and easy catalyst replacement.
Two processes were found in the literature that uses a fluidized-bed – developed
at Thyssen and Paul Scherrer Institute. The Comflux methanation was operated
1980-1985, for about 8,000 h and was developed by Thyssengas. The process
was run at 60 bar and with a H2/CO of 2.7-4. This has several advantages such as
minimizing the carbon dioxide formation from the water-gas shift reaction [8]. In
addition to this, further work has been performed in recent years at Paul Scherrer
Institute [9-11].
2.3 Gas quality
There are significant differences in gas quality within Europeing. Describing the
differences in the various gas qualities is outside the scope of this report. For more
information on the various gas qualities the webpage of Swedish Gas Technology
Centre, www.sgc.se, is recommended. In this report the Swedish standard for vehicle
gas has been used as a target quality [12], more specific the type A quality.
The major properties are summarized in Table 1. The motor octane number is determined
using calculations as per ISO 15403 [13]. The problem with using this
definition in this case is the hydrogen content. The standard does not take into
account any hydrogen content in the gas. An alternative method is to use the definition
in SAE 922359 [14]. However, also this expression has been developed
without hydrogen in the gas and even though it may be used for determining the
motor octane number in this case, its validity may be questioned for the gas mixture
at hand. Therefore, the motor octane number has not been reported for the
case study although they are within range of that specified in ISO 15403.
16 Svenskt Gastekniskt Center AB, Malmö – www.sgc.se