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Heating tower heat pumps are increasingly used in subtropical areas due to their frost-free characteristics. The spray heating tower (SHT) solves the fouling problem suffered by the packing heating tower and ensures thermal performance. However, the heat and mass transfer characteristics of SHT have not been fully revealed and the power consumption of SHT is higher than that of packing heating towers. In the present study, the effects of tower height, air temperature, solution concentration/type, and liquid to gas ratio on the thermal performance of SHT were analyzed using a mathematical model. The heat and mass transfer characteristics of SHT with 100% thermal efficiency and/or 100% tower effectiveness were investigated. The results showed that when thermal efficiency approached 100% and liquid to gas mass ratio was 0.28, evaporation and condensation occurred at the bottom and top of the tower, respectively. Based on the parametric analysis results, a parameter design strategy to reduce pump power consumption while ensuring thermal performance was determined, which reconciled the contradiction between power consumption and thermal performance of SHT. The results of this investigation may provide a reference for the design and operation of SHT.

The Fluid Catalytic Cracking Unit process converts heavy vacuum gas oil into more valuable products in the presence of zeolite catalyst at 520 °C and 2.5 bar. The coke is burned off with air in the regenerator tower at 700 °C and 230 ton / h of flue gases are produced. The flue gases consist of CO2 (12.7% mole), N2 (66.2% mole), H2O (19.2% mole), O2 (1.7% mole), and SO2 (0.2% mole). In this study, the chemical absorption of CO2 in an absorption and desorption pilot plant was investigated and this process was simulated by Aspen Hysys. The pilot plant used has an absorber tower of 15 cm in diameter and a stripper tower of 10 cm. The towers were filled up to 1.5 m with 3-mm Raschig ring packing. A concentration of 30 wt% diethanolamine (DEA) solvent is used for CO2 absorption. Absorption was carried out at 1.1 bar, solvent temperature of 40 °C, flue gas temperature of 60 °C, and liquid to gas ratio (L/G = 3.7). Amine regeneration was carried out at 125 °C and 1.9 bar. The CO2 absorption efficiency in the pilot plant was obtained 96% and in Aspen Hysys simulation its 95%. The CO2 recovery efficiency in the stripper tower obtained 95% and CO2 purity is 94.6%. The overall efficiency of the chemical absorption with this process is 92%, and the regeneration energy in the stripper tower is 2.52 GJ/ton-co2. With this method, 1003 ton/day CO2 is captured from the FCCU flue gases and preventing emission to the atmosphere.

In this work, we report the performance of a lab scale wet packed-bed scrubber using woodchips as a packing material. Wood chips were wetted by waste cooking oil which acted as a scrubber medium. Residence time of 8.5 s was comparable to the packed-bed filter used in a pilot scale gasifier. We studied the effects of oil/gas ratio (4.7 and 7 m3/s/m3/s × 103), oil temperature (ambient, ~23 °C and 50 °C) and woodchips size (coarse = ~0.02–0.045 m, 0.003–0.03 m and 0.002–0.007 m and fine = (0.015–0.04 m) × (0.002–0.005 m) × (0.001–0.003 m)) to remove tar model compounds from producer gas. The results demonstrate liquid to gas ratio has significant effect (p-value = 0.002) on removing toluene as tar model compound; next important parameter is bed configuration (p-value = 0.014), impacting toluene removal efficiency. For naphthalene, oil flow rate (p-value = 0.022) and bed configuration (p-value = 0.024) have almost similar effects. Oil temperature has relatively lower impact on removing tar.

In this work, an air-blast atomizing column was used to study the CO2 capture performance with aqueous MEA (mono-ethanol-amine) and NaOH solutions. The effects of gas flow rate, the liquid to gas ratio (L/G), the CO2 concentration on the CO2 removal efficiency (η) and the volumetric overall mass transfer coefficient (KGav) were investigated. The air-blast atomizing column was also compared with the pressure spray tower on the studies of the CO2 capture performance. For the aqueous MEA and NaOH solutions, the experimental results show that the η decreases with increasing gas flow rate and CO2 concentration while it increases with increasing L/G. The effects on KGav are more complicated than those for η. When the CO2 concentration is low (3 vol%), KGav increases with increasing gas flow rate while decreases with increasing L/G. However, when the CO2 concentration is high (9.5 vol%), as the gas flow rate and L/G increases, KGav increases first and then decreases. The aqueous MEA solution achieves higher η and KGav than the aqueous NaOH solution. The air-blast atomizing column shows a good performance on CO2 capture.

Biomass gasification is the thermo-chemical conversion of biomass into producer gas. The latter can be then integrated in a combined heat and power unit or chemically converted into biofuels. Tar formation during biomass gasification is the main process disadvantage. Tar leads to fouling and clogging problems in the process, in addition to catalyst deactivation when production of chemicals is envisaged. Eliminating tar from the producer gas forms the trigger point for any further valorization. This work hence evaluates the efficiency of wet scrubbers on tar removal from producer gas, based on simulations conducted using Aspen Plus. Wet scrubbers are highly efficient tar removal methods suitable for small scale gasifiers and having a low cost. Two scrubbers are placed in series to increase the tar removal efficiency. The tar reduction efficiency is assessed function of the scrubbing liquid: rapeseed methyl ester and water. Sensitivity studies handling the variation of the liquid to gas ratio and the scrubbing liquid temperature were conducted to study their impact on the tar removal efficiency. Results showed that increasing the liquid to gas ratio and decreasing the scrubbing liquid temperature leads to higher tar removal efficiencies. However, the conducted economic analysis indicated that the operational cost increases as well. A balance between the non-aqueous scrubbing liquid higher tar removal efficiencies with lower utilities cost and the actual liquid cost makes water an alternative scrubbing liquid choice. Finally, the selection of the optimal conditions depends mainly on the required tar limit set for the producer gas application.

The growth in productions of liquid hydrocarbons from tight formations (shales) has been phenomenal in recent years. During the production of liquids (oil and condensate), large amounts of associated gas are also produced. The economic viability of a producing well depends on maintaining a reasonable proportion of liquid. The compositions and state of reservoir fluid play an important role in producing liquids from tight formations or shales in the USA such as Eagle Ford in Texas, Niobrara in Wyoming-Colorado, and Bakken in North Dakota. Small deviation in reservoir temperature around the critical point changes the state of the fluid (volatile oil or condensate) and as a result, the production of liquid is affected. Impacts of the state of the fluid (volatile oil or condensate), reservoir permeability and operating conditions on ultimate recoveries and produced gas liquid ratio are studied here. Five different reservoir fluids representing low to high liquid hydrocarbon contents are considered. Around 2% increment in condensate recovery after 10 years of production is observed from 100 nD permeability reservoir filled with the richest fluid (fluid 5) when the well is operated at 3000 psia compared to 1000 psia. At the same conditions, 9.3% more condensate is recovered for the leanest fluid (fluid 1). Therefore, operating the well at higher flowing bottom hole pressure (BHP) maximized the liquid recoveries of volatile oils and condensates in case of low permeability reservoirs (100 nD). However, in case of higher permeability (1000 nD) reservoir, lower operating pressure was preferable to increase the recovery. Conclusively, bottom hole pressure has less impact on the richer fluids and higher permeability reservoir. Operating well at higher BHP (3000 psia) also suppresses the production of gas and relatively enhances the production of liquid. Liquid to gas ratio (LGR) declines more rapidly for 100 nD permeability reservoirs compared to 1000 nD at BHP of 1000 psia. High fracture permeability (1000mD and above) appeared to negatively affect liquid recoveries at higher BHP resulting in reduction of recovery by around 2%. An optimum fracture permeability may be necessary based on reservoir permeability, operating pressure and type of fluid. Cited as : Panja, P., Pathak, M., Deo, M. Productions of volatile oil and gas-condensate from liquid rich shales. Advances in Geo-Energy Research, 2019, 3(1): 29-42, doi: 10.26804/ager.2019.01.02

The industrial world and vehicles that currently exist make the pollution level increase. Often we see thick smoke rising out of the factory chimney, the thick smoke is a waste of gas released by the environmental factory. The scrubber system is a collection of various air pollution control devices that can be used for particles and / or gases from industrial output gas streams. The term scrubber is also used to describe a system that injects or enters a dry active ingredient or liquid into a dirty gas stream to clean acid gas. The design of the venturi scrubber aims to design a venturi scrubber to reduce soot emissions on direct injection diesel engines, get a standard venturi scrubber design and reduce soot levels. This design begins with determining the alternative design, determining the venturi dimensions and the material that will be used to build the venturi scrubber. The result of this step is a working drawing that is ready to be realized through machining. Next is to make the components based on the design results in the previous step. These components are then assembled into a tool. The final step is to do the venturi design test according to the venturi type standard and the size requirements that are in the ISO 5167-4 standard. Making a venturi scrubber design program using Delphi-7 software with pressure drop data, liquid to gas ratio, diameter ratio, pipe diameter, throat diameter, renold number and type of flow that occurs and design using Solidworks 2010.

Flexible operation of combined cycle thermal power plants with chemical absorption post combustion CO2 capture is a key aspect for the development of the technology. Several studies have assessed the performance of decentralized control structures applied to the post combustion CO2 capture process via dynamic process simulation, however there is a lack of published data from demonstration or pilot plants. In this work, experiments on transient testing were conducted at the amine plant at Technology Centre Mongstad, for flue gas from a combined cycle combined heat and power plant (3.7–4.1 CO2 vol%). The experiments include six tests on open-loop responses and eight tests on transient performance of decentralized control structures for fast power plant load change scenarios. The transient response of key process variables to changes in flue gas volumetric flow rate, solvent flow rate and reboiler duty were analyzed. In general the process stabilizes within 1 h for 20% step changes in process inputs, being the absorber column absorption rates the slowest process variable to stabilize to changes in reboiler duty and solvent flow rate. Tests on fast load changes (10%/min) in flue gas flow rate representing realistic load changes in an upstream power plant showed that decentralized control structures could be employed in order to bring the process to desired off-design steady-state operating conditions within (

This paper discusses the limitations and prospects of using equilibrium-based column models for the dynamic simulation of post-combustion CO2 capture processes. Based on their features, one of three available commercial process simulators was chosen for this study. A pilot plant configuration adopted from literature was modeled and simulated using this simulator. Simulation results were compared with plant data and with results using standard rate-based models as available in literature. Temperature profiles in columns and overall mass and energy balances were found to be similar to plant data; however, CO2 capture-rate, reboiler-duty, and rich-loading using the model were overestimated. A method of reduced stage efficiencies in the absorber was used, which improved performance prediction further with a maximum deviation of 5%. Further, this dynamic model was used to analyze the process subjected to variation in flue gas flow-rate with a similar trend of futuristic power plants by controlling either liquid to gas ratio or CO2 capture-rate. Controlling liquid to gas ratio provided more control over the reboiler-duty while controlling the capture-rate focused on maintaining a certain capture ratio. The advantages and disadvantages of both methods are discussed and based on that, the controlling capture ratio was found suitable for using while power plant works flexibly with stringent emission regulations. This is the authors' manuscript to the article (preprint).

The application of spray towers for CO 2 capture is a development trend in recent years. However, most of the previous jobs were conducted in a cylindrical tower by using a single spray nozzle, whose configuration and performance is not good enough for industrial application. To solve this problem, the present work proposed a diameter-varying spray tower and a new spray mode of dual-nozzle opposed impinging spray to enhance the heat and mass transfer of CO 2 absorption process. Experiments were performed to investigate the mass transfer performance (in terms of the CO 2 removal rate ( η ) and the overall mass transfer coefficient ( K G a e )) of the improved spray tower under various operating conditions. Experimental results showed that the liquid to gas ratio and mole ratio of MEA to CO 2 are major factors, which affect the absorption performance and the maximums of η and K G a e that are 94.0% and 0.574 kmol·m − 3 ·h − 1 ·kPa − 1 , respectively, under the experimental conditions. Furthermore, new correlations to predict the mass transfer coefficient of the proposed spray tower are developed in various CO 2 concentrations with a Pearson Correlation Coefficient over 90%.

The application of spray towers for CO 2 capture is a development trend in recent years. However, most of the previous jobs were conducted in a cylindrical tower by using a single spray nozzle, whose configuration and performance is not good enough for industrial application. To solve this problem, the present work proposed a diameter-varying spray tower and a new spray mode of dual-nozzle opposed impinging spray to enhance the absorption performance of CO 2 spray absorption process. Experiments were conducted to investigate the effects of varies operating parameters on the overall mass transfer coefficient in various operating conditions. Experimental results showed that liquid to gas ratio and mole ratio of MEA to CO 2 are key factors which affect the performance of CO 2 absorption process and the maximum overall mass transfer coefficient for the diameter-varying dual-nozzle opposed impinging spray tower is 0.4773 kmol·m -3 ·h -1 ·kPa -1 .

Concentrated 5 molal (m) piperazine (30 wt% PZ) is a novel solvent being developed by the University of Texas at Austin for CO2 capture from coal-fired power plants. In March 2015, a campaign at the UT Austin Separation Research Program (SRP) pilot plant evaluated the advanced flash stripper configuration with 5 and 8 m PZ. The absorber was operated with two gas rates: 350 and 500 acfm. The liquid to gas ratio (L/G) was varied from 2.3 to 5.0 lb/lb. The in-and-out and pump around spray recycle intercooling were operated at 40 °C. Seventeen runs were operated with 5 m PZ and four runs were completed with 8 m PZ. The lean solvent CO2 concentration was varied from 0.18 to 0.26 mol CO2/mol PZ equivalent. The CO2 removal rate in the absorber was varied from 69 to 97%. The advanced flash stripper was operated at temperatures and pressures that varied from 135 to 149 °C and 4.2 to 7 bar, respectively. The cold rich bypass was varied from 0 to 13% and the warm rich bypass was varied from 17 to 41%. 5 m PZ gives 20% better heat transfer performance than 8 m PZ on the LP cross exchanger and resulted in a lower process heat duty because of lower viscosity. Seventeen runs with optimized rich solvent bypass rates achieved process heat duties from 2.1–2.5 GJ/tonne CO2. This campaign demonstrated that using the advanced flash stripper reduced the energy requirement by 25% compared to the previous two SRP campaigns with the two-stage flash configuration.

The Containment Filtered Venting System (CFVS) is used to scrub the Particle matter & gaseous pollutants that are liberated during the severe accidents in nuclear power plants (NPP). This research work aims to an experimental study of the fluid dynamics of gas-liquid interaction of the circular cross-sectional self- priming VS at different experimental inputs. The performance of self-priming VS is indicated by the Pressure drop, Liquid to gas ratio & Collection efficiency. The effect of Scrubbing liquid height on these performance indicators is studied at different gas flow rates. The experimental result shows that the scrubbing liquid height greatly influences the performance of self-priming VS. It improves the Liquid to Gas ratio which is helpful to improve the collection efficiency.

There is wide application of venturi scrubber in Containment Filtered Venting System (CFVS) of Nuclear Power Plants (NPP) in order to eliminate the gaseous contaminants from polluted gas in Reactor Core of nuclear power plant. The different orientations of orifice at particular angle are used in same and reverse direction of flow respectively. Computational Fluid Dynamics (CFD) results of these arrangements are compared with the orifice pipe which is normal to the direction of gas flow. The pressure drop and velocity at throat affect the performance of venturi. A saleable software “ANSYS WORKBENCH” tool has been used for this investigation effort. Velocity field of gas flow is obtained by using K-Є turbulence model. The momentum conservation principle is used to calculate Gas velocity distribution. Euler-Euler approach is used to recognize performance of fluid dynamics inside the venturi. Pressure drop and liquid to gas ratio for various mass flow rate of gas is determined by CFD analysis of Self priming Venturi Scrubber.

This study investigates the recovery of ammonia from drying fumes during thermal drying of sewage sludge with packed bed acid scrubbers to recover ammonia and to produce ammonium sulfate. The process is modelled for two concentrations, 75 and 100 ppm, and 1000m3/h inlet flowrate of drying fumes containing air and ammonia gas. It results in finding optimal parameters for scale-up of drying fumes during thermal drying of 7700t/a sewage sludge of Lappeenranta city. It is found that a single scrubber, with a 24000 m3/h of inlet gas and an ammonia concentration of 75 ppm, liquid to gas ratio of 1.5, temperature and pH of liquid acid as 100°C and 3 respectively, gives the efficiency of more than 99%, and reduces ammonia concentration in the outlet stream to 0.2 ppm. The capital cost is 290 k€, operating cost is 113k€/a, removal cost with and without revenue of ammonium sulfate is 20 €/t and 18 €/t of sludge. The packed bed acid scrubber would be suitable to remove ammonia in the drying fumes to recover ammonia from the drying fumes, but the initial economic analysis highlights that the production of commercial grade ammonium sulfate fertilizer would be an expensive option.

The International Maritime Organization (IMO) has issued a long-term sustainable strategy to gradually phase out the major ship-related sources of greenhouse gas emissions. While the post-combustion carbon capture has been well investigated for onshore plants, the maritime carbon capture system is still in an early stage due to its unique characteristics and design limitations. Aiming at providing a holistic way to find the most efficient and sustainable PCC solution for an LNG tanker, this work proposed a system of the tank to propeller post-combustion carbon capture which integrates ship engine process modeling with chemical absorption/desorption process modeling techniques. A rate-based aqueous monoethanolamine (MEA) process model was developed and validated, then scaled up and modified to capture CO2 from the flue gas. To increase the carbon capture efficiency and decrease the energy penalty, this work provided detailed steps for process model development covering innovative absorber/stripper design under variation of solvents, packed type, and liquid to gas ratio. This work also included a thorough sustainability evaluation based on emission reduction efficiency, energy penalty, and carbon cyclic capacity among two single aqueous amines, MEA and diisopropanolamine (DIPA), and one blended amine with a promoter, methyldiethanolamine (MDEA) with piperazine (PZ). Although DIPA presented a better performance on energy requirement for solvent regeneration, the blended amine was the optimal solvent to meet the requirement of the IMO carbon abatement strategy. Compared to the seven molality MEA, the MDEA-PZ option could capture more than 57 % CO2 while around 25 % specific reboiler duty can be saved.

Chemical absorption using aqueous amine is one of the most feasible options for post-combustion CO2 capture. One of the main challenges of this technology is its high energy requirements. Absorber intercooling was considered as a viable method to offer benefits in terms of solvent absorption capacity and mass transfer efficiency in CO2 absorption processes. However, the effectiveness of absorber intercooling on overall energy requirements depends on other factors such as lean loading and liquid to gas ratio. This study evaluates the benefits of using two different configurations of absorber intercooling, i.e. “in-and-out” and “recycled” intercooling when using 30 wt% aqueous monoethanolamine (MEA) to capture 90% CO2 from a natural gas fired turbine with 4 mol% CO2. The Lean CO2 loading was varied from 0.15 to 0.42 (mol CO2/mol MEA) to determine the lean loading at which the application of intercooling is most significant. Absorber intercooling provides the most benefit at lean loading from 0.30 to 0.34. The use of in-and-out and recycle intercooling at 0.34 lean loading, provided 15.6 and 15.8% reduction in the total equivalent work associated with 32.0% and 36.6% reduction in required packing area when using 1.2 times the minimum liquid flow rate. At lean loading greater than 0.34, the benefit of absorber intercooling is a trade-off between reduction of solvent flow rate and total energy requirement and the drawback of greater packing area in the absorber. The greatest saving in total equivalent work, 17%, was observed at the 0.36 lean loading associated with nearly 60% more packing area when using 1.2 times the minimum solvent flow rate. At very low lean loading and very high lean loading absorber intercooling does not offer significant benefit.

In industrial scale, removal of CO2 by chemical absorption from raw biogas represents an imperative treatment and the cutting-edge technology towards improvement of its quality and heat value. In this work, CO2 absorption studies were conducted in an absorption column packed with Sulzer metal gauze packing with simulated biogas absorbed using 30 wt. % of monoethanolamine (MEA) solution. Experimental works were conducted to determine the influence of different CO2 concentrations in feed gas (30 % and 40 %) and L/G ratio (0.6 and 0.7) and subsequently assessed in terms of CO2 absorption efficiency along the column. The results showed that 30 % CO2 in feed gas has higher removal efficiency as compared to 40 % CO2 with the ability to remove 94 % CO2 during the process. In addition, the CO2 absorption studied on the L/G ratio proved that CO2 removal was improved at higher L/G ratio of 0.7.

A large amount of water and energy can be recovered in the flue gas after wet desulfurization. In order to explore the performance of the packed tower as a direct contact heat exchanger between flue gas and water, we measured the resistance and temperature field distribution of packed tower through on site pilot scale experiments, filled the gap in previous studies that lacked field trials and high humidity flue gas temperature data. The experimental results show that using packed tower as the heat exchanger can achieve low resistance and high heat exchange efficiency, indicating that packed tower is suitable for cooling the flue gas after wet desulfurization to achieve the purpose of energy and water recovery. The research results can guide the design and operation of the packed tower, liquid to gas ratio of 4.0 L/Nm3 and packing layer thickness of 1.20 m are optimal design parameters for packed tower. The selection of packing type and gas velocity, and the adjustment of operating parameters under variable load conditions can also refer to the experimental data in this article.

Post combustion CO2 capture using amines is one of the most well understood processes. The most widely used and studied solvent for this purpose is 30 % Monoethanolamine (MEA). The main issue with the process is the use of energy for stripping CO2 out of the solvent. It is anticipated that higher concentrations of MEA can capture a higher amount of CO2 and thus reduce energy consumption but may also result in a worsening of the environmental emissions due to potential increase in corrosion and solvent degradation. In order to study the impact of 40 % MEA (as opposed to 30 % MEA) on the capture plant performance, a test campaign was carried out at the Pilot Scale Advanced Capture Technology (PACT) facilities of the UK Carbon Capture and Storage Research Centre (UKCCSRC) using 30 % and 40 % MEA. The absorber (9 m height ×0.3 m dia.) is packed with 28 sections (6.5 m) of Mellapak CC3 structured packing. The absorption column temperature profile is measured by 10 RTDs installed around 48 cm apart along the column length. The performance of the capture plant in terms of reboiler duty, capture efficiency, loading capacity and liquid to gas ratio is evaluated at different operating conditions. It has been found that specific reboiler duty using 40 % MEA drops by up to 14 % as compared to that with 30 % MEA under similar test conditions. It has also been observed that the process is very sensitive to reboiler temperature and slight changes in reboiler temperature can have a significant impact on the plant performance. Moreover, similar energy and capture performance can be achieved at different reboiler temperatures with right combination of temperature and pressure in the reboiler/stripper. Corrosion rate was found to be higher with 40 % MEA than 30 % MEA. Solvent degradation rate and solvent carry over has also indicated slightly higher levels for 40 %. Water wash was shown to be effective in recovering most of the MEA from the flue gas.

Design of the preheat venturi scrubber has been performed using the process tool ASPEN Venturi by ASPEN Process Tool V 8.0- aspen one. Venturi scrubbers can be design using either the flowrate of gas at inlet conditions or the saturated gas flowrate. Various input parameter introduced in this research to be specified for sizing which included, Liquid to Gas ratio is kept 3.339 Litre/m 3 , Gas pressure drop is 4.9835 kPa, Entering gas temperature at standard conditions is 371.1°C and Liquid (water) volumetric flowrate is 0.000794 m 3 /sec. It is observed that higher values of Liquid to Gas ratio gives a higher pressure drop. As most commonly, Liquid and gas enters at converging section, or liquid can also be introduced from throat. As area decreases, gas velocity increases and pressure drop becomes higher which in accordance to Bernoulli's Equation. By keeping all the parameter constant likewise Liquid to Gas ratio and Gas pressure drop for all the process. At gas flowrate 0.2 m 3 /sec and 1.4 m 3 /sec, we get Throat Velocity 43.94 m/sec and 106.3 m/sec, Throat Diameter 0.07613 m and 0.13 m and Throat Length 1.6 m and 0.205 m, respectively. From graphical trend, it is proved that Gas flowrate is directly proportional to Throat velocity and diameter and inversely proportional to Throat length.

Carbon capture and storage (CCS) has attracted worldwide attention as a near-term technology to decelerate global warming. Postcombustion CO2 capture utilizes existing coal-fired power plants, and aqueous monoethanolamine (MEA) scrubbing is the most common capture technology. However, the heat and energy requirements of solvent regeneration and CO2 liquefaction cause a 30% decrease in net power output. This power de-rate is a major obstacle to implementing CCS. In this study, simulation-based parametric optimization was performed to minimize the power de-rate. Postcombustion CO2 capture with aqueous MEA scrubbing (85%, 90%, and 95% removals) and CO2 liquefaction integrated with a 550 MWe supercritical coal-fired power plant was simulated. The liquid to gas ratio and stripper operating pressure of the CO2 capture process were the manipulated variables with steam extracted from the intermediate pressure–low pressure crossover pipe and the first low pressure turbine as possible heat sources. The power de-rat...

Coal power plants are used extensively worldwide for electricity production due to its cheap rate. The major demerit is its adverse affect on the environment through emissions. The particulates and pollutant gases are the major ones, emitted by coal power plants. Venturi scrubber is one of those technologies that assist in simultaneous removal of particulates and toxic gases. To correctly understand and design these equipments, it is necessary to visualize the fluid dynamics inside these devices. In this regard, a numerical simulation is performed in ANSYS-CFX by using Eulerian-Lagrangian method to estimate particulate collection efficiency in the venturi scrubber. The collection efficiency is investigated at different gas and water mass flow rates. The potassium oxide (K2O) particles of one micron size with 2.35 g/cm3 density is used in simulation. Droplet diameter is also calculated in simulation by means of Cascade Atomization Breakup (CAB) model. Proper selection of breakup regime for droplet deformation in CAB model is determined by calculation of gas Weber and Ohnesorge number. Grade efficiency is calculated for throat gas velocity of 32 m/s with liquid to gas ratio of 7 l/m3. The affect of liquid to gas ratio at specific throat gas velocities on particulates removal efficiency and droplets diameter are also examined. The results shows that the increase in particulates removal efficiency occurred by increasing gas mass flow rate and liquid to gas ratio at particular gas velocities. The decrease in droplet size is observed during accession in liquid to gas ratio. Particulate removal efficiency of 99 % can be achieved at higher gas mass flow rates due to high inertial impaction parameter.

A wet packed bed scrubber combined with dry oxidation by indirect DBD plasma for conversion of NO to NO 2 and wet reduction with two reduction agents of Na 2 S and Na 2 SO 3 to remove NO 2 was developed at room temperature for semiconductor manufacturing industries. The design and operation parameter for the wet scrubber such as gas concentration, liquid to gas ratio, reducing agent concentration, residence time and pressure drop were investigated at 2 m3/min and 200 ppm of pure NO gas. Na 2 S solution was more suitable than Na 2 SO 3 with less chemical consumption and liquid to gas ratio. Removal efficiency over 80% was achieved with liquid to gas ratio of 10 L/m3, reduction agent solution of 0.1% w/w which corresponds to ORP of −310 mV and pH of 12.3, residence time of 2 sec, and pressure drop of 25 mmAq/m, respectively. Finally, a demonstration test of the wet scrubber was conducted for 1 month with exhaust gas from perfluorinated compounds (PFCs) gas scrubber at the rooftop of a semiconductor manufacturing plant in Korea. In order to suppress H 2 S as byproducts of the wet scrubber, pH over 12 was carefully controlled with NaOH solution because commonly highly acid gases such as HF and HCl were fed from the manufacturing process. The NOx removal efficiency was average 83.8% which was very similar to those obtained from the lab tests. These results indicate that the combination of the dry oxidation and wet reduction method could be a promising solution to remove NOx from semiconductor manufacturing industries.

Post combustion CO2 capture (PCC) through reactive absorption is a promising technology to tackle climate change. The application of new solvents enables a reduction in energy demand. This research work discusses the suitability of aqueous sodium glycinate (NaGly) as a CO2 absorption solvent. Laboratory studies show slow absorption kinetics and moderate CO2 absorption capacities of aqueous NaGly. Results from pilot plant tests at the coal-fired power plant in Durnrohr, Austria, with 15, 25 and 40 wt% NaGly are presented and discussed. Realistic industry conditions were achieved through the use of flue gas from the power plant and the well-conceived dimensions of the test facility. Low energy consumption of aqueous NaGly was mainly predicted by simulations in literature ( ∼ 3 GJ / t CO 2 ) . The measured energy consumption in the present work is much higher ( > 5 GJ / t CO 2 ) . This represents an increase of 40% with respect to 30 wt% monoethanolamine (MEA), not combined with enhanced system extensions. The low predicted optimal solvent flow rate could not be confirmed in the present work. The optimal liquid to gas ratio is in the range of 7–8 l/m3.

A modeling study was performed to investigate the direct impact of amine CO2 scrubbing on the efficiency of a coal-fired power plant. The full scope of the capture process was simulated with 8 m PZ (piperazine) to estimate the steam, electricity, and cooling water requirements. The steam cycle was simulated for applications of the capture technology to both retrofit and greenfield (optimized new build) coal-fired power plants. The reboiler duty of the stripping column had an optimal molar L/G (liquid to gas ratio) of 4.9 in the absorber and the maximum reboiler temperature of 150 °C. Integration of this CO2 capture with a greenfield coal plant yielded an identical optimal L/G, but the optimal reboiler temperature was 140 °C, and the decrease in power plant efficiency was 7.3%. The retrofit case resulted in an optimum case with an L/G of 5.9, a reboiler temperature of 120 °C, and a decrease in plant efficiency of 7.0%. When running at the optimal L/G, the optimization sensitivity to the reboiler temperature was low.

Post combustion CO2 capture (PCC) by reactive absorption is a promising technology to tackle climate change. The application of new solvents enables a reduction in energy demand. The present work describes the testing of a 32 wt% solution of ethylenediamine (EDA) in a pilot plant at the power plant in Durnrohr, Austria. Through the use of the power plant’ flue gas and the well-conceived dimensions of the test facility, industry-related conditions for full scale applications can be provided. The measurements are compared with results of an aqueous solution with 30 wt% of monoethanolamine (MEA) as well as other measurements from literature. The high reaction rate of EDA has especially positive effects at high flue gas flow rates. A reduction of up to 11.5% of the required regeneration energy is possible. This property allows higher flow rates in the same column and therefore leads to a reduction in investment costs. The optimal liquid to gas ratio is 2.5 l/m3 and is thus lower than when using MEA. As a result, fewer pumping and cooling demands are necessary for approaching the optimum operating point.

In this study, we developed a prediction model for desulphurization efficiency of onboard magnesium-base seawater scrubber. The effect of various parameters, including liquid to gas ratio (VL/VG), pH value and empty container velocity (ve), on desulphurization efficiency of magnesium-base seawater scrubber was studied using the MiniTab 15 software. Specifically, central composite design coupled with response surface method was used in this model. A prediction model for desulphurization efficiency of magnesium-base seawater scrubber was presented. Analysis of variance of the quadratic model indicates that the model could be used to navigate the design space. The parameters of VL/VG and pH are most effective factors affecting the desulphurization efficiency. Within the variation range, ve has limited influence on desulphurization. The scrubber can be handled at the flow rate of more than 1×104 m3/h. We observed that desulphurization efficiency is more than 90% under the optimized conditions of VL/VG at 10.39 L/m3, pH at 7.66 and ve between 0.66 and 0.75 m/s.

Droplet size is a fundamental parameter for Venturi scrubber performance. For many years, the correlations proposed by Nukiyama and Tanasawa (1938) and Boll et al. (1974) were used for calculating mean droplet size in Venturi scrubbers with limited operating parameters. This study proposes an alternative approach on the basis of artificial neural networks (ANNs) to determine the mean droplet size in Venturi scrubbers, in a wide range of operating parameters. Experimental data were used to design the ANNs. A neural network was trained based on the liquid to gas ratio (L/G) and throat gas velocity (Vgth), as input parameters, and the Sauter mean diameter (D32) as the desired parameter. The back-propagation learning algorithms were used in the network and the best approach was found. A new formula for the prediction of D32 using the weights of the network was then generated. This formula predicts mean droplet size in Venturi scrubbers more accurately than the correlations of Boll et al. (1974) and Nukiyama and Tanasawa (1938). The Average Absolute Percent Deviation (AAPD) of our formula and the Boll et al. and Nukiyama and Tanasawa correlations for the full ranges of experimental data are 26.04%, 40.19% and 32.99%, respectively.

Carbon dioxide (CO2) emissions reduction from combustion fossil fuel power plants is a key aspect in the stabilization of global climate change. Post-combustion CO2 capture from fossil fuel power plants using amine-based solvents, typically monoethanolamine (MEA), is one of the most promising technologies for the abatement of CO2 gas. In this work, a dynamic MEA absorption process model has been developed to predict the dynamic behaviour of the CO2 capture process. The resulting dynamic model was used to study the transient response of the MEA absorption process to changes in the flue gas flow rate and the reboiler heat duty. The changes in flue gas flow rate and reboiler heat duty are key process variables that affect the lean loading, liquid to gas ratio and percentage of CO2 removal. To represent the actual operation of a power plant, the dynamic response of the MEA absorption process to a sinusoidal change in the flue gas flow rate was also considered in the present analysis. The results show that the changes between the reboiler heat duty and CO2 removal follows a ratio of approximately 1:1.4. Also, the lean loading stream entering the absorber unit is key to maintain the feasible operation of the system. Moreover, the energy performance of the process (Joules per mole of CO2 captured) is directly affected by the operation of the reboiler. The outcomes from this study provide insights regarding the dynamic behaviour of this process and can be used as the basis to develop other aspects related to the dynamic operation of this plant, e.g., to develop control strategies for this system.

This paper presents the hydrodynamics of the wet scrubber coupled to a pilot CFB incineration facility. The scrubber was operated using tap water as a scrubbing liquid. The outlet liquid flow rate, Qo, and accumulation rate, Qa, strongly depend on the inlet liquid flow rate, Qin, with different profiles. At higher Qin values, Qo stabilizes, leading to higher Qa and finally flooding. The values of Qa were higher than Qo except for Qin ranging between 0.53 and 0.72 L/s (safe operating range) in which Qa ≌ Qo and Qa = Qin/2. The outlet-to-inlet liquid flow rate ratio, Qo/Qin decreased for Qin > 0.53 L/s. The increase in the accumulation-to-inlet liquid flow rate ratio, Qa/Qin, at higher Qin indicates a change in flow regime towards flooding, accompanied by an abrupt increase in the height of accumulating liquid, Ha. The difference between Qa/Qin and Qo/Qin (denoted as, ΔQao/Qin), shows a minimum close to zero in the safe operating range. The gas flow rate towards the wet scrubber had slight effect on Qo and Qa when Qin was maintained constant. The ratio Qo/Qin decreased slightly with Ha/Ht irrespective of gas velocity. Changing the liquid-to-gas ratio, L/G and Qin strongly affects the maximum and minimum values of Qo/Qin and Qa/Qin.

There have been a number of efforts to satisfy national emission regulations and reduce the amount of emitted air pollutants. There are several air pollution control devices, however, only wet scrubber is efficiently used to remove particulate matters and gaseous pollutants, even if it has minimum collection efficiency in the particle size range of . This study aimed to improve the collection efficiency of a spray tower type scrubber by introducing an electrospray system with two-flow nozzle. We found that the collection efficiency of a spray tower type scrubber was similar to that of a conventional wet scrubber. However, installation of an electrospray system in the scrubber resulted in drastic further improvement of collection efficiency comparing to that of a conventional scrubber, which is 26%, 35.2%, and 45.1% at the liquid to gas ratio of 0.26 and 19.9%, 35.1%, and 42.5% at 0.34 for the applied voltage of -30 kV, -35 kV, and -40 kV, respectively. Therefore, we found that the introduction of an electrospray system is very effective to improve the collection efficiency of a spray tower type scrubber.

A novel process to remove fine particles with high efficiency by heterogeneous condensation in a wet flue gas desulfurization (WFGD) system is presented. A supersaturated vapor phase, necessary for condensational growth of fine particles, was achieved in the SO2 absorption zone and at the top of the wet FGD scrubber by adding steam in the gas inlet and above the scrubbing liquid inlet of the scrubber, respectively. The condensational grown droplets were then removed by the scrubbing liquid and a high-efficiency demister. The results show that the effectiveness of the WFGD system for removal of fine particles is related to the SO2 absorbent employed. When using CaCO3 and NH3·H2O to remove SO2 from flue gas, the fine particle removal efficiencies are lower than those for Na2CO3 and water, and the morphology and elemental composition of fine particles are changed. This effect can be attributed to the formation of aerosol particles in the limestone and ammonia-based FGD processes. The performance of the WFGD system for removal of fine particles can be significantly improved for both steam addition cases, for which the removal efficiency increases with increasing amount of added steam. A high liquid to gas ratio is beneficial for efficient removal of fine particles by heterogeneous condensation of water vapor.

Rate-based process modeling technology has matured and is increasingly gaining acceptance over traditional equilibrium-stage modeling approaches. [Taylor et al. Chem. Eng. Prog. 2003, 99, 28−39] Recently comprehensive pilot plant data for carbon dioxide (CO2) capture with aqueous monoethanolamine (MEA) solution have become available from the University of Texas at Austin. The pilot plant data cover key process variables including CO2 concentration in the gas stream, CO2 loading in lean MEA solution, liquid to gas ratio, and packing type. In this study, we model the pilot plant operation with Aspen RateSep, a second generation rate-based multistage separation unit operation model in Aspen Plus. After a brief review on rate-based modeling, thermodynamic and kinetic models for CO2 absorption with the MEA solution, and transport property models, we show excellent match of the rate-based model predictions against the comprehensive pilot plant data and we validate the superiority of the rate-based models over t...

Cooling towers are one of the largest heat and mass transfer devices that are in common use. A novel type of cooling tower has been proposed in which air flow rate into the tower is drawn by ejector action of sprays instead of fans as is done in conventional mechanical forced or induced draft cooling towers. This novel design offers the potential of savingthe energy cost for driving the fan. The paper presents mathematical models for momentum transfer which is the driving force causing the entrainment of air. Also the heat transfer model for co-current flow of liquid and gas in the tower has been presented. The liquid to gas ratio tend to decrease as liquid rate increases. The ratio attained in the experimentallaboratory tower was 3.3, correspondingly the Momentum transfer efficiency for the tower was 60% and was the highest. Experiments for cooling water initially at 45 o C to final water temperature 27 o C showed that the cooling tower efficiency was 54% and number of transfer unit 0.8.

An efficient venturi scrubber system combining a particle growth device and a traditional venturi scrubber was designed and tested in the laboratory. Before the venturi scrubber, saturated steam at 100°C was mixed with normal temperature waste stream to achieve supersaturation conditions allowing submicron particles to grow into micron sizes. Hence the control efficiency of submicron particles was greatly enhanced at a reasonably low pressure drop as compared to that found in the literature. At a flow rate of 250 L∕min and a liquid to gas ratio of 2.5 L∕ m3 , the control efficiency of the present venturi scrubber system for NaCl particles greater than 100 nm is greater than 90%, and pressure drop is only about 44 cm H2 O (4.3 kPa) . In comparison, to remove only 50% of 0.6 μm particles at the same liquid to gas ratio, the pressure drop needed will be greater than 200 cm H2 O (or 19.6 kPa ). Theoretical calculation has also been conducted to simulate particle growth process and the control efficiency of th...

Enzyme based sensor for detection of urea in milk was constructed using a piezo-electric sensor, which measures the pressure of the gas, evolved in the sample. The sensor showed linear behavior for varying concentrations of urea in the samples. The time response of the sensor was evaluated and liquid to gas ratio of 1:2.5 was found to give satisfactory output by the sensor. The results indicate that this technique can be effectively used to detect urea levels in milk.

Post-combustion carbon dioxide (CO2) capture using aqueous monoethanolamine (MEA) has been the most widely implicated method utilizing existing coal-fired power plants. However, the heat and energy requirement of the solvent regeneration and CO2 liquefaction results in a 30% decrease in net power output, which is called “power de-rate”. In this study, optimum operating conditions of the integrated CCS process are proposed by simulation-based parametric optimization to reduce the power de-rate. Post-combustion CO2 capture with aqueous MEA and CO2 liquefaction integrated with a 550 MWe supercritical coal-fired power plant was simulated base on the data of a 0.1 MW pilot plant in South Korea. The stripper operating pressure and liquid to gas ratio were chosen as the manipulated variables based on the variable evaluation. The power de-rate was reduced to 17.4% when operating at optimum conditions.

The classical theory of the cooling tower does not include a suitable mathematical solution for a direct and quick calculation of gas/liquid temperature profiles. This forces in most of practical cases, for example in case of industrial spray absorbers, to simplify the problem and to assume a complete cooling of exit gases down to the adiabatic saturation temperature of the incoming gases. In the present paper, a new method is described to develop an acceptable mathematical solution for cooling towers, taking into account the main influencing parameters, especially the liquid to gas ratio (L/G) and the actual liquid and gas interface. Calculations with the new solution show, that the exit gas temperature is strongly influenced by the liquid inlet temperature. In case of closed loop and counter current systems, this liquid inlet temperature is more or less close to the adiabatic saturation temperature of the incoming gases. In these cases, the exit gas temperature is only slightly higher than the currently assumed adiabatic saturation temperature of the inlet gases. This is completely different to the open loop systems, where the liquid inlet temperature is not influenced by the incoming gases at all. In these cases, the gas outlet temperature is mostly far from the adiabatic saturation temperature of the inlet gases, so that the current assumption can initiate great errors.

Liquid film characteristics in the prediction of pressure drop in a Venturi scrubber was examined by measuring the film flowrate, film thickness, and pressure drop by varying the injection orifice diameter, the throat gas velocity, and the liquid loading in a pilot-scale unit. The liquid mass flowrate flowing on the Venturi walls was found to be relatively independent of orifice diameter and decreased with throat gas velocities. The effect of increased liquid loading decreased the film flow on the orifice side and increased the same on adjacent walls. The average thickness of the liquid film on the walls was found to increase with orifice diameter on the orifice side, and with axial distance and decrease with orifice diameter on the adjacent-side walls, and throat gas velocity. The film velocities calculated were found to increase with throat gas velocity and liquid loading and continuously decrease along the axial direction. The distribution of the injected liquid flowing on the scrubber walls was found to depend on the liquid to gas ratio, throat gas velocity, liquid film thickness, axial pressure drop and relative velocity between the liquid film and the adjoining gas stream. An annular flow model, modified to include the variation in liquid film thickness using correlation developed during this work accurately predicted pressure drops for a wide range of operating conditions compared to the most commonly used models.

An empirical design correlation has been developed to predict the fraction of liquid flowing on the wall as a film in a Venturi scrubber. This correlation takes into account primary operating variables such as Liquid to Gas Ratio, and Throat Gas Velocity and design variables such as nozzle diameter and Venturi throat width in the direction of liquid injection. Data for the design correlation were obtained on a pilot plant scale Venturi scrubber using operating variables ranges that are normally encountered with industrial size units.

The purpose of this project was to evaluate the performance of ION’s lead solvent and determine if ION’s solvent candidate could potentially meet DOE’s target of achieving 90% CO{sub 2} Capture from a 550 MWe Pulverized Coal Plant without resulting in an increase in COE greater than 35%. In this project, ION’s lead solvent demonstrated a 65% reduction in regeneration energy and a simultaneous 35% reduction in liquid to gas ratio (L/G) in comparison to aqMEA at 90% CO{sub 2} capture using actual flue gas at 0.2 MWe. Results have clearly demonstrated that the ION technology is in line with DOE performance expectations and has the potential to meet DOE’s performance targets in larger scale testing environments.

The link between the collection efficiency of a Venturi scrubber and its operating pressure drop was first established by Semrau in 1958. Friedrich Loffler used it as a starting point for the predictive model for which he won the Filtration Society Gold Metal in 1980. The approach taken in that study was not widely followed by subsequent modellers but, in conjunction with previous work, it does lay the foundation for a useful design approximation which allows grade efficiency curves to be predicted from empirical data determined at other operating condition. In this paper, a range of detailed grade efficiency measurements conducted on a full-scale plant are reported. The curves are shown to depend only upon pressure drop across the scrubber, there being no independent effect of gas velocity, liquid to gas ratio, or dust size distribution. The implications of this for design are discussed and the grade efficiency prediction technique is demonstrated.

Heterogeneous condensation of water vapor as a preconditioning technique for the removal of fine particles from flue gas was investigated experimentally in a wet flue gas desulfurization (WFGD) system. A supersaturated vapor phase, necessary for condensational growth of fine particles, was achieved in the SO2 absorption zone and at the top of the wet FGD scrubber by adding steam in the gas inlet and above the scrubbing liquid inlet of the scrubber, respectively. The condensational grown droplets were then removed by the scrubbing liquid and a high-efficiency demister. The results show that the effectiveness of the WFGD system for removal of fine particles is related to the SO2 absorbent and the types of scrubber employed. Despite a little better effectiveness for the removal of fine particles in the rotating-stream-tray scrubber at the same liquid-to-gas ratio, The similar trends are obtained between the spray scrubber and rotating-stream-tray scrubber. Due to the formation of aerosol particles in the limestone and ammonia-based FGD processes, the fine particle removal efficiencies are lower than those for Na2CO3 and water. The performance of the WFGD system for removal of fine particles can be significantly improved for both steam addition cases, for which the removal efficiency increases with increasing amount of added steam. A high liquid to gas ratio is beneficial for efficient removal of fine particles by heterogeneous condensation of water vapor.