Reduction In Duty Research Articles

Catalytic regeneration of amine-based absorbents for CO2 capture: The effect of acidic sites and accessibility

The high regeneration energy consumption is the bottleneck problem for the large-scale application of organic amine absorption method. Catalytic regeneration has received a lot of attention because it can be done at low temperatures using solid acid catalysts. Although the catalytic activity of the catalysts presently reported is exceptional, the exorbitant cost renders this technology unsuitable for industrial implementation.The present work uses a composite metal oxide solid acid catalysts for the catalytic regeneration of a CO2-rich 5 M MEA solution at 90 °C. The findings indicate that the inclusion of SO42-/ZrTiOx catalyst resulted in a 99% increase in CO2 desorption rate, a 43% improvement in cyclic capacity, and a 29.09% reduction in relative heat duty when compared to the blank experiment. The catalyst underwent characterization through BET, NH3-TPD, and Py-IR techniques, revealing that its superior catalytic performance can be attributed to its substantial mesoporous specific surface area and significant concentration of acid sites. The catalytic effect and catalytic mechanism of SO42-/ZrTiOx were confirmed using 13C NMR spectroscopy. The stability of the SO42-/ZrTiOx catalyst during regeneration was investigated in five cycles and the cause of catalyst deactivation was investigated by FT-IR. The results show that the SO42-/ZrTiOx catalyst has high catalytic activity and low cost, and has potential for large-scale industrial applications.

Application of the Calcium Looping Process for Thermochemical Storage of Variable Energy

The calcium looping (CaL) process, which exploits the reversible calcination of calcium carbonate, has been proposed as a solution to the challenges facing deployment of concentrated solar power (CSP). As an extension of the work undertaken to date, this project proposes a novel configuration of the CSP-CaL process which may offer advantages over other proposed configurations, including a reduction in process equipment requirements, elimination of pressure differentials between vessels, and a reduction in compression duty during the energy discharge period. The results obtained through process simulation indicate that the proposed process can achieve round-trip efficiencies in the range of 32–46% and energy storage densities in the range of 0.3–1.0 GJ/m3. These parameters are strongly dependent on the residual conversion of the CaO sorbent as well as the efficiency of the power cycles used to remove heat on the carbonator side of the process.

The State’s Attitude and Response to the Threat Posed by Tobacco Smuggling in Ireland 1780–1850

Tobacco as one of the ‘old reliables’ has presented governments with a steady and lucrative revenue stream that continues to this day. The enormous difference between tobacco’s prime cost and that paid by the consumer is due to the imposition of government duties. This revenue was particularly threatened in the period in question by smugglers and their land-based accomplices who were attracted by the considerable profit to be made because of such a differential in price. The state response to this threat included largely ineffectual legislation and the expensive establishment of state agencies to combat this threat. This approach was maintained despite ongoing appeals from economic commentators and members of the tobacco trade for a reduction in duty which they felt would make it uneconomical for smuggling to continue.

Inter-integration reactive distillation with vapor permeation for ethyl levulinate production: Modeling, process analysis and design

The reactive-vapor permeation-distillation (R-VP-D) hybrid configuration is a newly designed inter-integration concept firstly proposed for the production of ethyl levulinate (EL) by esterification of ethanol and levulinic acid in this paper. In the R-VP-D configuration, the VP membrane module is inserted to the reaction section of the reactive distillation (RD) column, of which the product water is in-situ removed by the vapor permeation (VP) to promote the performance of esterification RD process. The proposed R-VP-D configuration is modeled by Aspen Plus V8.4 using the two-dimensional VP model built in ACM®, and the inserting position of single or double VP modules is found by contrast trials, where both the conversion rate and purity of product can reach the industrial production standards. As a result, the proposed novel R-VP-D configuration is feasible, with over 21.6% and 31.4% reduction in TAC and total duty as compared to the configuration which only applies an extra distillation column to separation and recycle the excess ethanol without azeotrope separation, and with 13.5% and 21.5% reduction in TAC and total duty as compared to the hybrid configuration where the vapor permeation is coupled outside the RD column. The result also shows the advantage of the proposed R-VP-D process for potentially leading to the development of new integration processes and applications.

Heat Loss and Energy Use in Pilot Plant Testing of Piperazine With the Advanced Stripper

Piperazine with the Advanced Stripper (PZAS™) was tested at the National Carbon Capture Center (NCCC) at coal and NGCC conditions and its energy performance and heat loss were measured. The net heat duty was found to be 2.45 GJ/tonne at 4% and 12% CO2 at 90% removal. The average measured heat loss was 0.38 GJ/tonne and represented 30% of the gross heat rate. Carbon treating increased the NTU of the cold and hot exchangers by 1.8% and 1.5%, respectively, by removing viscous solvent degradation products. The Independence™ model was validated using 112 steady-state pilot plant runs and predicted average net heat duty with an error of 9% and lean loading within 10% of the measurements. The model captured the effect of carbon treating on heat exchanger performance and predicted a reduction in heat duty of 1.2% but failed to predict the step decrease of 8% seen in measured heat duty data. In PZAS™, the warm rich pipe before the control valve is deemed the most important for heat loss due to its high surface area and its ability to increase flashing across the valve and decrease the total rich bypass temperature. Heat duty is corrected for 80% of the heat loss value, corresponding to the sensitivity of heat duty to heat loss at the same location. In the simple stripper, a large topside pinch makes heat duty most sensitive to heat loss in the column. Water condensation by heat loss increases the L/G and causes reabsorption at low heat loss values (~0.02 GJ/hr). Overdesigning strippers must therefore be avoided to mitigate this effect. Reabsorption in PZAS™ is not as sensitive to heat loss and occurs only at high values (~0.14 GJ/hr) due to the even temperature pinch in the column. 7 m MEA with the simple stripper has a lower measured heat duty than 5 m PZ due to the insignificant effect of heat loss in the column on with 7 m MEA. Unlike 5 m PZ, 7 m MEA has a bottom-side pinch that mitigates the effect of heat loss by water condensation.

Process analysis of improved process modifications for ammonia-based post-combustion CO2 capture

Carbon-based fuels contribute majorly towards global energy demand; however, it results in global warming. The increasing energy demand and climate change highlights the need to develop cost-effective carbon sequestration schemes. Amine-based CO2 scrubbing have been widely used for their high selectivity and production of pure CO2. However, a challenge in implementing amine-based technology is high energy consumption with a low capture ratio. The energy penalty can be reduced either by introducing new solvents, optimizing parameters, or through process modifications. Recently, ammonia has tempted attraction in place of amines. In this present work, a Radfrac model in Aspen Plus is developed involving heat integration and absorption enhancement to overcome the barriers. The heat integration is performed with a rich solvent split and absorption enhancement is done with split flow arrangement. Further, the model is evaluated at different split ratios by performing heat integration between different streams of the flowsheet. Moreover, the process configurations used in this system is compared with MEA based process modifications concerning energy reduction. A competitive reduction in regeneration duty was observed which was 36% less than the reference NH3 and 47% less than the MEA process. This evaluated modification will result in maximum efficiency, a maximum level of CO2 capture, and a reduction in the reboiler duty. The rich solvent split and split flow process reduced the reboiler duty by 15.8% and 32.8%, respectively. The split flow process also indicated an increase of 17.2% in rich loading to recover 90% CO2.

Development of aqueous-based phase change amino acid solvents for energy-efficient CO2 capture: The role of antisolvent

The energy penalty is a primary limitation for the implementation of the aqueous solvents for large-scale post-combustion CO2 capture processes. In this study, a novel aqueous-based phase change solvent, composed of potassium glycinate (GlyK, reactive species), water (H2O, solvent) and dimethylformamide (DMF, antisolvent) was developed to improve the energy efficiency of CO2 capture. To examine the role of the antisolvent, a series of aqueous-based amino acid solvents (GlyK-X) with different DMF:H2O (X) volume ratios was prepared, fully characterized and assessed. It was observed that a CO2-free phase appeared at the top of the aqueous-based amino acid GlyK-X solvents after CO2 absorption which can be easily separated and recycled to the absorption column and save energy. The results showed that the GlyK-60 solvent with DMF:H2O volume ratio of 60:40 had a very high CO2-free phase volume (63%). Moreover, the GlyK-60 solvent exhibited 26.1% (0.433–0.546 mol CO2/mol GlyK) enhancement in CO2 absorption capacity, 38.5% (130–80 min) decrease in regeneration time and 59.1% reduction in relative heat duty compared to the conventional aqueous GlyK solvent. Overall, the outcomes confirmed that the aqueous-based phase change GlyK-60 solvent is a viable solvent option for large-scale CO2 capture with extra-low energy consumption and a key to the success of Paris Climate Accord.

The effect of different process configurations on the performance and cost of potassium taurate solvent absorption

The main method of capture of CO2 in industry is the use of solvents for CO2 absorption in post-combustion capture and the benchmark solvent is monoethanolamine (MEA). However, it presents a few disadvantages such as having a high energy requirement while also being corrosive and toxic. Potassium taurate (K-Tau) is a solvent with the potential to replace MEA because it has similar reaction rates, high cyclic loading, degradation resistant and most importantly, low energy requirement.The objective of this study was to compare and evaluate the effect of different process configurations on the reboiler duty for the precipitating potassium solvent absorption process. Utilising a baseline potassium taurate process, different process configurations were developed in Aspen Plus. These include a cold rich bypass (CRB) of the rich solvent stream to the stripper and a solid-liquid separator. The results show that the modified configurations reduce the reboiler duty of the potassium taurate process by approximately 12% through the reduction in sensible heat and vaporization duty.

Mechanism Investigation of Advanced Metal-Ion-Mediated Amine Regeneration: A Novel Pathway to Reducing CO2 Reaction Enthalpy in Amine-Based CO2 Capture.

The high energy consumption of CO2 and absorbent regeneration is one of the most critical challenges facing commercial application of amine-based postcombustion CO2 capture. Here, we report a novel approach of metal-ion-mediated amine regeneration (MMAR) to advance the process of amine regeneration. MMAR uses the dual ability of amine to reversibly react with CO2 and reversibly complex with metal ions to reduce the enthalpy of the CO2 reaction, thus decrease the overall heat requirement for amine regeneration. To elucidate the mechanistic effects behind MMAR's ability to reduce CO2 reaction enthalpy, we developed a comprehensive chemical model describing the chemistry of Me(II)-monoethanolamine(MEA)-CO2-H2O system. The model was then validated using experimentally determined CO2 partial pressures via vapor-liquid equilibrium (VLE) measurements. We used the validated chemical model to gain insight into VLE behavior and solution chemistry, and to identify the specific changes in CO2 reaction enthalpy with and without metal ions. Two metals and five amines were evaluated in detail, which revealed that metal-ions with high complexation enthalpy and amines with large carbamate stability constant are preferred in MMAR, owing to their large reduction in reaction enthalpy and regeneration duty. We anticipate that MMAR could provide an alternative pathway to reducing the energy consumption of absorbent regeneration, ultimately making amine-based processes more technically and economically viable.

Energy saving in acetic acid process using an azeotropic distillation column with a side stripper

ABSTRACTDilute acetic acid is obtained primarily from fermentation and synthesis processes and cannot be produced by simple distillation due to relatively low volatility of acetic acid compared to water. Instead, an azeotropic distillation is applied to increase the concentration of dilute acetic acid. When acetic acid is extracted from a dilute aqueous solution using a solvent mixture of ester and alcohol, its recovery requires an energy-intensive azeotropic distillation. In the water stripping process that follows azeotropic distillation, two distillation columns handle the acetic acid and water mixture in similar composition. Therefore, the two columns can be combined as a side stripper connected to the azeotropic distillation column. The energy-saving effect is examined with the HYSYS (Aspentech Corporation) evaluation of the process. Compared to the conventional process, the modified process suggests 39% reduction in heating duty and 24% coolant savings. The economic analysis shows 32% decrease in investment and 36% utility savings. Based on heat utilization analysis, the thermodynamic efficiency is enhanced by 11%.

CO2 capture efficiency and heat duty of solid acid catalyst-aided CO2 desorption using blends of primary-tertiary amines

This study evaluated improvements in the CO2 capture process in terms of cyclic capacity, absorption efficiency and heat duty caused by using a primary amine (5 M MEA) blended with a tertiary amine (2 M MDEA or 1.25 M DEAB) and a catalyst-aided desorber loaded with two different solid acid catalysts (γ-Al2O3 or HZSM-5) in a bench scale full cycle CO2 capture plant. The absorber and desorber were stainless steel pipes with inside diameter of 0.05 m and height of 1.50 m. The desorber was loaded with varying amounts of solid acid catalyst at an average bed temperature of 85 °C. The two mixed amine solvents tested, were compared with 5 M MEA each with a circulation rate of 0.06 L/min. Simulated flue gas, 15% CO2 in N2, was used at a total flow rate of 15 SLPM. The results showed that in 5 M MEA system, cyclic capacity and absorption efficiency increased while heat duty decreased when the catalyst amount was increased. In the case of mixed primary and tertiary amines, catalysts contribute to slight improvements. The increase in absorption efficiency was found to be in the order of 5 M MEA: γ-Al2O3 < 5 M MEA: HZSM–5 < 5 M MEA: 2 M MDEA: γ-Al2O3 < 5 M MEA: 2 M MDEA: HZSM–5 < 5 M MEA: 1.25 M DEAB: γ-Al2O3 < 5 M MEA: 1.25 M DEAB: HZSM-5. The relative reduction in heat duty of the system was found to be in the order of 5 M MEA: 1.25 M DEAB: HZSM–5 < 5 M MEA: 2 M MDEA: HZSM–5 < 5 M MEA: 1.25 M DEAB: γ-Al2O3 < 5 M MEA: 2 M MDEA: γ-Al2O3 < 5 M MEA: HZSM-5 < 5 M MEA: γ-Al2O3.

Carbon dioxide (CO2) capture: Absorption-desorption capabilities of 2-amino-2-methyl-1-propanol (AMP), piperazine (PZ) and monoethanolamine (MEA) tri-solvent blends

In this study, highly concentrated tri-solvent blends containing 2-amino-2-methyl-1-propanol (AMP), piperazine (PZ) and monoethanolamine (MEA) were experimentally investigated for their potential capabilities in carbon dioxide (CO2) capture. The concentration of both AMP and PZ were varied but their combined concentration (AMP + PZ) was kept at 3 kmol/m3 to limit the possibility of precipitation, the maximum PZ concentration (1.5 kmol/m3), and the total aqueous amine solution concentration (6 kmol/m3). At atmospheric pressure condition, the absorption process was carried out at 313 K and 15.1%v/v CO2 while 363 K was used for the desorption analysis. Experimental results indicated that all the AMP – PZ – MEA tri-solvent blends possessed higher cyclic capacities, initial desorption rates, and lower heat duties (50–54.5%) compared to the standard 5 kmol/m3 MEA. For the initial absorption rates, only the tri-solvent blends with AMP/PZ molar ratios of 1 and 2 were higher than 5 kmol/m3 MEA. These findings, most especially the significant reduction in heat duty by halve reveal the prospects of AMP – PZ – MEA tri-solvent blends for CO2 capture applications.

The Impact of Bakery Industry Supply Chain on the Pricing of Bread in Zimbabwe

The paper sets out to carry an exploratory study for improving supply chain activities in an effort to reduce the bread retail price. The price of bread in Zimbabwe is more than that of most African countries such as Zambia, Namibia and Malawi whose prices range from US$0.50 to US$0.75 per loaf of bread. The major problem with the bread industry today is that there seems to be a hiking of raw materials prices, labour and production costs. The major question then is why bread costs 30 cents more in Zimbabwe than in other African countries. Data was collected using100 consumer questionnaires, 100 bakery/retailer and 5 in-depth interviews. Convenience, judgemental, quota and stratified random sampling methods were used to select the respondents. Purchasing side findings were that 59% to 65% of the bakeries stated the shortage of flour in the country as the major cause behind the high price of bread Most of the flour being used by bakeries is import flour. The second purchasing side problem is that of expensive suppliers of flour. Electricity shortages and untimely stoppages of power were sited by 76% of the production side players as the major impediment to the efficient production of bread. Their assertion was that the power cuts led to low production which inturn led to high inefficiencies in the production line. Fortytwo percent (42%) of customers said that bread needed improvement in quality issues such as packaging and ingredients used. They agreed that if the quality improved they would pay more for it. The paper therefore concluded that the high price of bread in Zimbabwe as compared to other countries is a result of the use of expensive suppliers along the line coupled with low capacity machinery that has led to lowered output. In the long run the lowered output has resulted in sub-optimal operations in bread factories. The researchers recommended a Government intervention through policy change in terms of reduction in duty and tariffs levels on imported raw materials. Government could also intervene through capital injection into the supply chain. Other recommendations include business to business (B2B) collaboration and partnerships between wheat suppliers, marketing boards, millers, bakeries and retailers. Backward integration and rationalisation of the supplier base by bakeries is likely to lower the price of producing bread and hence its retail price.

Dynamic modelling and analysis of a coal-fired power plant integrated with a novel split-flow configuration post-combustion CO2 capture process

We present a model of a coal-fired power plant integrated with a dynamic model of a monoethanolamine (MEA)-based post-combustion CO2 capture process. We evaluate base- and part-load operating modes of the integrated power and CO2 capture plant. We propose a simple modification to the base-process which exploits the tradeoff between thermodynamic and rate or kinetic driving forces for mass transfer. This modification returns a portion of the regenerated solvent to the middle of the absorption column at an elevated temperature. Under base-load operation of the power plant, this modification was observed to increase the degree of CO2 capture by 9.9% and reduce the reboiler duty by 8.3%, improving the net electrical efficiency of the decarbonised power plant from 28.27% to 29.15% – a relative increase of 2.8%. Under part-load operation, the degree of CO2 capture increased by 1% with a concurrent reduction in reboiler duty of 16.7% and an increase in overall process efficiency of 3.25%.

Pilot of a novel intervention for postconcussive symptoms in active duty, veterans, and civilians.

The authors present a study aimed at pilot testing a novel delivery method, namely a computer intervention, for postconcussive symptom reduction in active duty, veteran, and civilian patients with acute and chronic complaints. Following a concussion/mild traumatic brain injury (MTBI), most individuals recover completely, but a significant proportion report postconcussive symptoms months to years following the injury. Psychoeducational intervention has shown to be effective in reducing postconcussive symptoms in studies done with acute civilian samples, but the efficacy of psychoeducational interventions with individuals who served in combat or have chronic complaints remains unclear. Twenty-five active duty, veteran, and civilian participants took part in this study. At baseline, each participant completed a self-run psychoeducational computer-based treatment. Participants were reassessed 1-month postintervention via phone to evaluate postconconcussive symptom severity. Participants reported significantly fewer postconcussive symptoms at follow-up than baseline (d = .99). Intervention satisfaction was reported, with feedback related to ease of use and quality. Extending previous studies, current findings demonstrated that psychoeducational intervention following MTBI was associated with postconcussive symptom complaint reduction in both acute and chronic patients. These data also confirm the feasibility of using computerized psychoeducation and speak to the importance of providing education to both acute and chronic patients across settings. Feedback from participants was generally positive. Further investigation with a control group is warranted.

Process configuration studies of the amine capture process for coal-fired power plants

This study reports the detailed evaluation of ten different configurations of amine capture processes using 30wt% aqueous monoethanolamine (MEA) solvent to capture 90% CO2 from an exemplary sub-critical PC-fired boiler power plant. The process configurations are compared with respect to total energy consumption, including thermal and electrical energy used. The comparison includes known configurations available in the literature and in patents. Additional configurations which lead to improved amine capture processes are presented, which result in further reduction in the reboiler heat duty. The use of detailed process flowsheet simulations enables the quantification of the effect of using multiple strategies in achieving greater reduction in the energy required for the integrated carbon capture and compression units. The simulations are also constrained to limit temperatures below conditions that lead to amine thermal degradation. Compared to the simple absorber/stripper configuration, which reduced the efficiency of the power plant by 9–12%, the multiple alteration system proposed in this study achieves the same capture rate with a 0.9% gain of net plant efficiency only by an advanced amine process configuration and a reduction in steam consumption of up to 37%.

Process Simulation of Aqueous MEA Plants for Post-combustion Capture from Coal-fired Power Plants

This study evaluated different configurations of post-combustion amine processes using 30wt% aqueous MEA solvent. The configurations were compared with respect to total energy consumption including thermal and electrical energy involved in its operation to capture 90% CO2 from an exemplary sub-critical PC-boiler power plant The improved amine processes reported in the literature were analysed and simulated using the Honeywell UniSim process simulator to evaluate their performance and it was suggested that they could be further improved by appropriate modifications. Simultaneous implementation of several improvement methods has been explored in order to reduce further the reboiler heat duty. Several alterations to the base configuration can achieve greater reduction in reboiler duty (or equivalent work) compared to simple modifications based on a single variation. The extent of energy saving must be evaluated carefully through the implementation of appropriate process simulations since we have shown that the overall effect is different from a simple sum of the saving effects estimated individually.

Model verification and evaluation of the rich‐split process modification at an Australian‐based post combustion CO2 capture pilot plant

AbstractThe CSIRO is involved in three CO2 capture pilot plants operating at different coal‐fired power stations throughout Australia. The most recently completed of these is the Tarong CO2 capture pilot plant located at Tarong power station, Nanango, Queensland. The first phase of the experimental program with this pilot plant included operation with monoethanolamine (MEA). This involved parametric studies, process modifications, and finally implementation of 24 h operation. Operation of the pilot plant has shown MEA to be effective in capturing CO2 from the flue gas from Tarong Power Station. CO2 capture efficiencies of up to 94%, and regeneration energies as low as 3.6 MJ/kgCO2 have been achieved. The design of the pilot plant was completed using a commercially available process modeling software tool. Results obtained from the pilot plant were then compared to the model predictions including temperature, solvent CO2 loading, and CO2 gas concentration profiles through the absorber column. A good match has been obtained between the modeling and pilot plant data, verifying the software can be used to predict the performance of the pilot plant when operating on MEA. During this project, the rich‐split process modification was also evaluated. The results suggest that the rich‐split modification can achieve some reduction in reboiler duty and a considerable reduction in the condenser duty. The amount of reduction is dependent on plant design, particularly the efficiency of the lean/rich heat exchanger. © 2012 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

A New Chemical System Solution for Acid Gas Removal

AbstractAn energy‐efficient absorbent formulation for separating acid gases (e.g. CO2, H2S) from gas streams such as natural gas, syngas or flue gas is important for a number of industrial applications. In many cases, a substantial share of their costs is driven by the operational expenditure (OPEX) of the CO2 separation unit. One possible strategy for reducing OPEX is the improvement of the absorbent performance. Although a number of absorbents for the separation of CO2 from gas streams exist, there is still a need to develop CO2 absorbents with an improved absorption performance, less corrosion and foaming, no nitrosamine formation, lower energy requirement and therefore less OPEX. Selected performance results of a new family of amine‐based CO2 absorbents are summarized. High cyclic capacities in the range of 2.9 to 3.2 mol CO2 kg–1 absorbent and low absorption enthalpies of about –30 kJ mol–1 allow for significant savings in the regeneration energy of the absorbent. Calculations with the modified Kremser model indicated a reduction in the specific reboiler heat duty of 45 %. Furthermore, the absorbents developed show much lower corrosion rates than state‐of‐the‐art solutions that are currently employed.

Investigation of the dynamic behavior of different stripper configurations for post-combustion CO2 capture

The dynamic behavior of three process configurations proposed for CO2 capture from flue gas is investigated. In the previous paper (Karimi et al., 2011) the different configurations were investigated with respect to energy requirement and capital costs and the best configurations were defined based on CO2 avoided cost and total capture cost. In addition to the economy, the dynamic behavior is important when operation of the plant is considered. In this study the transient behavior of the vapor recompression and the split-stream configurations are investigated when different disturbances happen, and the results are compared with the conventional configuration as a benchmark. All process configurations are operationally feasible with the proposed control configuration. The results show that the conventional configuration is the most inherently resilient to disturbances, and that the vapor recompression configuration can handle disturbances better than split-stream configuration. The same relative reduction in reboiler duty has more negative effect (more reduction in capture ratio) for split-stream configuration than two other configurations.The control structure generated is able to control the plant for all configurations except the situation where the reboiler duty is an active constraint. In this situation the energy loss will increase and it is better to find another control variable to pair with reboiler duty. This will be done in future studies.