Carbon dioxide removal in indirect gasification - SGC

ܭெ ஽ா஺ = ௘ቀమయభ.రషభమబవమ ೅ షయల.ళఴ∙ౢ౤(೅)ቁ
௘ ቀషవ.రభలఱషరమయర.వఴ
೅
ቁ
SGC Rapport 2013:277
Eq. I
The calculations for the stripper column are executed in the same manner as
those for the absorption column, with integral balances solved first, followed by the
differential calculations. Because of the difficulties associated with solving the differential
balances for the stripper, [34], a second method was also applied for the
determination of the stripper height. The second calculation method is a short-cutmethod
that was developed to simplify stripper height calculations [80]. For this
method, equilibrium data for the system is required, which was taken from the literature
[81]. Data from the literature have also been used for the differential calculations
for the stripper [63, 82-87]. The final stripper height was chosen to be the
highest value obtained from the two methods applied. The reboiler duty for the
stripper is determined from the integral balances and the dimensions of the
reboiler can be determined from that data. This is also the case for the cooling effect
for the condenser. The dimensions of the heat exchangers are determined
using conventional theory.
In order to determine the amount of higher hydrocarbons that will be absorbed in
the amine solution an investigation of the solubility was carried out. The Henry´s
constant for the gases H2, CO, CH4, C2H4 and C6H6 were collected from the NIST
database, which include the results of several studies. Mean estimates of all the
values reported in the NIST database were used for evaluation of the solubility of
the gases H2, CO, CH4, C2H4 and C6H6 in the amine solution. The Henry´s constant
used are summarized in Table 4.
Table 4. Summary of Henry´s constant used for evaluation of solubility from the
NIST database.
Component ࢑ ࡴ ,ࢉ࢖൫ࢀ ⊝ ൯((mol bar)/kg) ࡯ (K)
H2 0.00078 543
CO 0.00096 1400
CH4 0.00135 1750
C2H4 0.0047 1800
C6H6 0.177 3950
The Henry´s constant, ݇ ு ,௖௣, describes the relationship between the concentration
of soluted gas in the liquid, ܿ ௔௤, and the partial pressure of the gas, ݌, according to
Equation J. It is also dependent on the temperature according to Equation K, were
݇ ு ,௖௣൫ܶ ⊝ ൯denotes the value at the reference temperature, ܶ ⊝ 25°C, and ܥ is a
constant given in Table 3.
݇ ு ,௖௣ = ௖ೌ೜
௣
݇ ு ,௖௣ (ܶ) = ݇ ு ,௖௣൫ܶ ⊝ ൯݁ݔ݌൬ܥ ቀ ଵ
்
− ଵ
் ⊝ቁ൰
Eq. J
Eq. K
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