Process design for CO2 absorption from syngas using physical solvent DMEPEG

作者：Dave Ashok^*; Dave Medha; Huang Ye; Rezvani Sina; Hewitt Neil

来源：International Journal of Greenhouse Gas Control, 2016, 49: 436-448.

DOI：10.1016/j.ijggc.2016.03.015

• Acid gas removal
• Carbon capture and storage
• Carbon dioxide absorption
• Dmepeg
• Hydrogen recovery
• Process simulation
• Rate-based mass transfer simulation
• Selective Absorption/Desorption

Pre-combustion IGCC is one of the leading technologies having potential for effective control of greenhouse gas emission. Process design for CO2 Capture from power plant is becoming increasingly important in the past decades in view of the need for optimization of Capital Cost and Utility consumption. In this article, a configuration of the process design for CO2 absorption using physical solvent DMEPEG is proposed, which is described using the process flow diagram (PFD) and the Flowsheet. CO2 absorption performance of DMEPEG solvent is assessed based on a rate based mass transfer model using ProTreat simulation software. The rate based mass transfer simulation by ProTreat software adds to the reliability of the simulation result (as evident by its acceptance within industry). The trade-off between H-2 recovery (by syngas recycle) and CO2 re-absorption is described which reveals that more than 55% H-2 recovery may significantly increase the load on the system (in terms of syngas processing and CO2 re-absorption).
Objective of this research is to develop a detailed process model for CO2 absorption by DMEPEG solvent (to enable detailed techno-economic assessment by bottom up approach). In the second section of this article, the process of CO2 capture by physical solvent DMEPEG is explained. In the fourth section, the boundary conditions such as the inlet pressure, temperature and composition of syngas and solvent feed are defined. In the fourth and fifth section, the design and performance of the packed tower is described and the utility consumption is estimated. Moreover, the outlet condition of the solvent is described and its saturation (by CO2) is estimated. In the fourth section, the strategy of solvent heating to recycle the syngas to CO2 absorber (for H-2 recovery) is described. Importance of CO2 absorption in solvent (at high concentration) for minimization of equipment size and utility consumption for CO2 capture is explained.
Using RSR packing (6.4 m Dia., 16 m Ht. (9 + 6 + 1)) results in 90.7% CO2 absorption and 89% saturation of CO2 dissolved in DMEPEG solvent. Out of 3.34 kmol/s H-2 fed to the CO2 Absorber (as part of syngas), 1.464% (equivalent 5.9 MW power generation by Gas Turbine in open cycle) is co-absorbed (along with CO2) in DMEPEG solvent. Out of this co-absorbed H-2, 55.7% is recovered which is equivalent to 3.267 MW Power Generation.
In terms of hydraulic design, the CO2 Absorber using RSR packing operating at 72.5% flood condition results in packing pressure drop of 87.5 Palm (1.4 kPa). Packed section diameter and height is suggested for various random packing materials (tower internal) to achieve almost comparable gas absorption performance.

• 出版日期2016-6