Simulation and Optimization of Pure Oxygen Claus Process
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摘要: 基于Aspen Plus软件建立克劳斯工艺全流程模型,使用工厂数据进行验证,探究了进口酸气组成、氧气浓度及进气流量、氧气预热温度、炉膛压力及第二催化段反应器温度等工艺参数对克劳斯工艺的影响,并以Aspen Plus为优化工具,硫收率为目标函数计算了最佳操作参数。优化结果表明:总硫收率从优化前的98.31%提高到优化后的99.08%,尾气中主要污染物SO2的排放量由优化前的0.350 kmol/h减少至优化后的0.278 kmol/h,降低了20.6%,并节省了酸性气体和空气预热所需的热量9133.38 J/mol。Abstract: The Claus process is effective for acid-gas processing and sulfur recovery. For industrial applications, combustion-supporting gas is needed to ensure flame stability when processing low-concentration acid gases, which can cause problems in terms of the increase in harmful substances such as polycyclic aromatic hydrocarbons and organic sulfur. The use of pure oxygen for combustion can not only increase the temperature in the furnace and improve the removal rate of hydrocarbon impurities, but also overcome the problems caused by the presence of combustion-supporting gas. In this paper, a full Claus-process model was constructed using the Aspen Plus software, and the theoretical result was validated by experimental data. The influences of the inlet acid gas composition, oxygen concentration, oxygen preheating temperature, furnace pressure, oxygen gas intake and the temperature of the second catalytic stage reactor on the Clause process were systematically examined. Optimized Aspen Plus was used to calculate the optimal operating parameters. The results showed that the sulfur recovery efficiency was enhanced from 98.31% to 99.08%, and the emission of SO2, which was the main pollutant in the tail gas, was reduced from 0.350 kmol/h to 0.278 kmol/h; the reduction rate reached 20.6%. In addition, a heat of 9 133.38 J/mol (acid gas) was less consumed for the preheating of the acid gas and air.
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Key words:
- Claus process /
- low concentration acid gas /
- pure oxygen /
- process simulation /
- optimization
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表 1 进料气组成及其参数
Table 1. Composition and parameters of the feed gas
Item x/% q/(kmol·h−1) H2 Ar N2 CO CO2 H2S H2O NH3 O2 CH3OH AG1 0 0 29.00 0 20.00 50.00 0 0 0 1.00 49.107 AG2 0.50 0 20.00 0.50 67.00 2.00 0 0 0 10.00 8.036 AG3 12.40 0.20 0.20 8.00 75.00 1.00 3.00 0.20 0 0 15.625 Air1 0 0.93 78.09 0 0.03 0 0 0 20.95 0 60.902 表 2 RF1内考虑的反应
Table 2. Considered reactions in RF1
No. Reaction 1 $ {\rm{N}}{{\rm{H}}}_{3} \to {\rm{0.5N}}_{{2}}{+1.5}{{\rm{H}}}_{{2}} $ 2 $ {{\rm{H}}_2}{\rm{S + 1}}{\rm{.5}}{{\rm{O}}_2} \to {{\rm{H}}_2}{\rm{O + S}}{{\rm{O}}_2}$ 表 3 RF2内的化学反应及其动力学参数
Table 3. Chemical reactions and kinetic parameters in RF2
No. Reaction Reaction rate expressions Reference 3 ${{\rm{H}}_{\rm{2}}}{{\rm{S}}} \leftrightarrow {{\rm{H}}_{\rm{2}}}{\rm{ + 0}}{\rm{.5}}{{\rm{S}}_{\rm{2}}}$ $-{r_{ {\rm{ {H} }_2S} } }=1.63\times{10^{-1} }{ {\rm{e} }^{{\frac{ {45.1} }{ {RT} } } } }{p_{_ { {\rm{H} }_{2}{\rm{S} } } } }p_{\rm{S_2} }^{0.5}-1.36\times{10^{-6} }{ {\rm{e} }^{{\frac{ {23.4} }{ {RT} } } } }{p_{_{\rm{H_2} }} }{p_{_{\rm{S_2}} } }$ [19] 4 ${\rm{CO} } + 0.5{{\rm{S}}_2} \leftrightarrow {\rm{COS}}$ $- {r_{ {\rm{CO} } } } = 3.18\times {10^5}{ {\rm{e} }^{{\frac{ {15.3} }{ {RT } } } }}\left( { {c_{\rm{CO} } }{c_{ { {\rm{S} }_2} } } - \dfrac{1}{ { {k_{\rm{eq2} } } } }{c_{\rm{COS} } }c_{ { {\rm{S} }_2} }^{0.5} } \right)$ [20] 5 $ {\rm{C}}{{\rm{O}}_{\rm{2}}}{\rm{ + }}{{\rm{H}}_{\rm{2}}} \leftrightarrow {\rm{CO + }}{{\rm{H}}_{\rm{2}}}{\rm{O}}$ $-{r_{\rm{C{O_2} } } }=8.59\times{10^{10} }{ {\rm{e} }^{{\frac{ {64.7} }{ {RT} } } } }\left( { {c_{\rm{C{O_2} } } }c_{ {\rm{ {H} }_2} }^{0.5}-\dfrac{1}{ { {k_{{\rm{eq}}3} } } }\dfrac{ { {c_{\rm{CO} } }{c_{ {\rm{ {H} }_2O} } } } }{ {c_{ {\rm{ {H} }_2} }^{0.5} } } } \right)$ [21] 6 $ {\rm{CO + }}{{\rm{H}}_{\rm{2}}}{\rm{S}} \leftrightarrow {\rm{COS + }}{{\rm{H}}_{\rm{2}}} $ $-r{\rm{_{CO} } }=1.59\times{10^5}{ {\rm{e} }^{{\frac{ {26.5} }{ {RT} } } } }\left({ {c_{\rm{CO} } }c_{ {\rm{ {H} }_2S} }^{0.5}-\dfrac{1}{ { {k_{{\rm{eq}}4} } } }\dfrac{ { {c_{\rm{COS} } }{c_{ {\rm{ {H} }_2} } } } }{ {c_{ {\rm{ {H} }_2S} }^{0.5} } } }\right)$ [22] 7 $ {{\rm{H}}_{\rm{2}}}{\rm{S + 0}}{\rm{.5S}}{{\rm{O}}_{\rm{2}}} \leftrightarrow {\rm{0}}{\rm{.75}}{{\rm{S}}_{\rm{2}}}{\rm{ + }}{{\rm{H}}_{\rm{2}}}{\rm{O}}$ $-{r_{ {\rm{ {H} }_2S} } } =3.18\times{10^3}{ {\rm{e} }^{{\frac{ {14.3} }{ {RT} } } } }{c_{ {\rm{ {H} }_2S} } }c_{\rm{S{O_2} } }^{0.5}-3.11\times{10^1}{ {\rm{e} }^{{\frac{ {8.5} }{ { {RT} } } }} }{c_{\rm{ { { {H} }_2}O} } }c_{ {\rm{S_2} } }^{0.75}$ [23] 表 4 炉膛出口气流量模拟结果与工厂数据比较
Table 4. Simulated results versus plant data for flow rate of gas from furnace
Gas q/(kmol·h−1) Absolute
error/%Plant date Simulated results H2 1.636 1.698 3.81 Ar 0.600 0.600 0.01 N2 63.453 63.448 0.01 CO 1.038 1.233 18.77 CO2 27.079 26.868 0.78 H2S 9.155 9.175 0.22 COS 0.119 0.133 12.13 SO2 4.637 4.789 3.27 H2O 17.930 17.836 0.53 S2 5.458 5.387 1.31 表 5 重要参数优化前后结果比较
Table 5. Important parameters contrast of the optimization results
Item x(O2)/% Split ratio qAir/(kmol·h−1) T0/℃ Ta/℃ TS/℃ Tf/℃ YS/% n(H2S)/n(SO2) of
the first catalysis stage${q}_{_{\rm{{SO_{2}}}, {\rm{outlet}}}}$/
(kmol·h−1)Before optimization 20.95 0.80 60.90 80 240 218 1019.39 98.31 1.99 0.350 After optimization 99.60 1.00 14.09 25 25 180 1314.11 99.08 2.00 0.278 -
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