Thermodynamic Modeling of Aqueous Piperazine/N-(2-Aminoethyl) Piperazine for CO2 Capture

AbstractAqueous piperazine (PZ) blended with N-(2-aminoethyl) piperazine (AEP) is an attractive solvent for CO2 capture from coal-fired power plants. A rigorous thermodynamic model was developed in Aspen Plus® to predict properties of PZ/AEP/H2O/CO2, using the electrolyte-Nonrandom Two-Liquid (eNRTL) activity coefficient model. A sequential regression was performed to represent CO2 solubility, speciation, and amine volatility data over operationally significant loading and temperature ranges. The model predicts a CO2 cyclic capacity of 0.86mol/kg (PZ + AEP + water) for 5 m PZ/2 m AEP, compared to 0.50mol/kg for 7 m MEA and 0.86mol/kg for 8 m PZ. The predicted heat of absorption is 75 to 85kJ/mol CO2 in the operating loading range (0.288–0.380mol CO2/mol alkalinity). Speciation for PZ/AEP/H2O at various CO2 loading and temperature was also predicted, from which behavior of CO2 in the amine system was proposed

Process for removing sulfur from sulfur-containing gases

The present disclosure relates to i The government may own certain rights in the present invention pursuant to EPA Cooperative Agreement CR 81-1531. This is a continuation of U.S. Ser. No. 928,337, filed Nov. 7, 1986, now U.S. Pat. No. 4,804,521.Board of Regents, University of Texas Syste

Optimum design and control of amine scrubbing in response to electricity and CO2 prices

AbstractThis paper presents steady state and dynamic modelling of post combustion CO2 capture using 30 wt% MEA integrated with models of CO2 compression and the steam power cycle. It uses multivariable optimization tools to maximize hourly profit of a 100 MWe coal-fired power plant. Steady state optimization for design provided optimum lean loading and CO2 removal as a function of price ratio (CO2 price/electricity price). The results indicated that for price ratio between 2.1 and 7, the plant should be designed at removal between 70% and 98% and lean loading in the range of 0.22–0.25. Dynamic optimization determined the operation of the capture system in response to two partial load scenarios (reboiler steam load reduction and power plant boiler load reduction) and provided optimum set points for steam rate, solvent circulation rate and stripper pressure control loops. Maximum profit is maintained by allowing the stripper pressure to drop and implementing a ratio control between solvent and steam rate (and flue gas rate for partial boiler load operation)

Apparatus for and method of removing acidic gas from a gaseous stream and regenerating an absorbent solution

An apparatus for and method of removing acidic gas from a gaseous stream and regenerating an aqueous solution allows for the recovery of waste heat of stripping steam and more economical regeneration of the aqueous solution. In at least one embodiment, one or more rich solvent bypasses combine with a rich solvent heat exchanger to recover waste heat. In another embodiment, the apparatus and method include one or more rich solvent bypasses and a heater positioned upstream of the stripper to more economically regenerate an aqueous solution.Board of Regents, University of Texas Syste

Blends of amines with piperazine for CO2 capture

Compositions and methods related to the removal of acidic gas. In particular, the present disclosure relates to a composition and method for the removal of acidic gas from a gas mixture using a solvent comprising a blend of piperazine and at least one diamine or triamine.Board of Regents, University of Texas Syste

Catalysts and inhibitors for MEA oxidation

AbstractAqueous monoethanolamine (MEA) was subjected to oxidation by O2/CO2 at 55 ∘C. Hydroxyethyl-formamide (HEF) and hydroxyethylimidazole (HEI) are the major oxidation products of MEA. Dissolved metals catalyze oxidation in the order copper > chromium/nickel > iron > vanadium. Inhibitors A, B and ethylenediaminetetracetic acid (EDTA) are effective degradation inhibitors. The addition of the expected inhibitors formaldehyde, formate or sodium sulfite had unintended effects on MEA losses. Total carbon and nitrogen analysis shows a greater than 90% closure of the material balance

Dynamic operation of amine scrubbing in response to electricity demand and pricing

AbstractThis paper examines dynamic operation of CO2 capture with absorption/stripping using 7 m MEA, where the absorber is operated at full capacity with the stripper at reduced load. Depending on the cost of CO2 emissions, doing so in response to variations in electricity demand could improve annual profits by $10–$100 million or more at facilities with CO2 capture. Dynamic scenarios were simulated with a controlled, constant ratio of heat rate and solvent rate. With an 80% load reduction, scenarios that turn CO2 capture off and on affect stripper performance only slightly and reach the steady state in about 90 and 18 minutes respectively

Processes for removing acid components from gas streams

The present disclosure relates to improved processes for treating acid gases to remove acid gas components therefrom. Processes in accordance with the present invention include preparing a calcium silicate hydrate sorbent in the form of a semi-dry, free-flowing powder, and treating the gas with the powdery sorbent, such as by injecting the sorbent into a stream of the gas. The powdery sorbents may be prepared by slurrying/drying or pressure hydration techniques. Examples disclosed herein demonstrate the utility of these processes in achieving improved acid gas-absorbing capabilities in both lab-scale and pilot plant studies. Additionally, disclosure is provided which illustrates preferred plant design configurations for employing the present processes using conventional dry sorbent injection equipment. Retrofit application to existing plants is also addressed.Board of Regents, University of Texas Syste

Processes for removing sulfur from sulfur-containing gases

The present disclosure relates to improved processes for treating hot sulfur-containing flue gas to remove sulfur therefrom. Processes in accordance with the present invention include preparing an aqueous slurry composed of a calcium alkali source and a source of reactive silica and/or alumina, heating the slurry to above-ambient temperature for a period of time in order to facilitate the formation of sulfur-absorbing calcium silicates or aluminates, and treating the gas with the heat-treated slurry compounds. Examples disclosed herein demonstrate the utility of these processes in achieving improved sulfur-absorbing capabilities. Additionally, disclosure is provided which illustrates preferred configurations for employing the present processes both as a dry sorbent injection and for use in conjunction with a spray dryer and/or bagfilter. Retrofit application to existing systems is also addressed.Board of Regents, University of Texas Syste

CO2 Capture by Absorption with Potassium Carbonate

The objective of this work is to improve the process for CO{sub 2} capture by alkanolamine absorption/stripping by developing an alternative solvent, aqueous K{sub 2}CO{sub 3} promoted by piperazine. The final campaign of the pilot plant was completed in February 2006 with 5m K{sup +}/2.5m PZ and 6.4m K{sup +}/1.6m PZ using Flexipac AQ Style 20. The new cross-exchanger reduced the approach temperature to less than 9 C. Stripper modeling has demonstrated that a configuration with a ''Flashing Feed'' requires 6% less work that a simple stripper. The oxidative degradation of piperazine proceeds more slowly than that of monoethanolamine and produces ethylenediamine and other products. Uninhibited 5 m KHCO{sub 3}/2.5 m PZ corrodes 5 to 6 times faster that 30% MEA with 0.2 mol CO{sub 2}/mol MEA