Water Wash System Research Articles

CO2 solubility and amine volatility data for low-concentration solutions of MEA, AMP, PZ and CESAR-1 blend (AMP/PZ)

Water-wash section(s) effectively reduce amine compound emissions in amine-based carbon capture processes. Reliable predictions of the behavior of these emission control technologies depend on detailed understanding of the vapor-liquid equilibrium (VLE) of water wash system. However, existing vapor-liquid equilibrium data in the literature focus primarily on solvent-like amine concentrations in amine–CO2–H2O systems; hence, new low-concentration VLE data are needed. In this work, the CO2 solubility in low-concentration solutions of monoethanolamine (MEA), piperazine (PZ), 2-amino-2-methyl-1-propanol (AMP), and AMP/PZ blend (CESAR-1) was investigated for temperatures between 303 and 353 K at atmospheric pressure. Additionally, amine volatility measurements for CO2-loaded low-concentration solutions of MEA, PZ, AMP and CESAR-1 were performed in the range of 313–373 K and 8–96 kPa. Overall, the data show that the CO2 partial pressure increases with increasing CO2 loading and temperature. Similarly, the amine partial pressure increases with increasing pressure and temperature. The new experimental data were compared with two existing VLE models using electrolyte non-random two-liquid activity coefficient models to evaluate the ability of the latter to predict vapor-liquid equilibrium behavior. Both CO2 solubility and amine volatility predictions by the models tend to show significant deviations. The comparison highlight the need for such low-concentration data for all systems studied. This data shall serve to improve existing water-wash modeling tools.

Targeted electrochemical reduction of carcinogenic N-nitrosamines from emission control systems within CO2 capture plants

N-Nitrosamines are one of the environmentally significant byproducts from aqueous amine-based post-combustion carbon capture systems (CCS) due to their potential risk to human health. Safely mitigating nitrosamines before they are emitted from these CO2 capture systems is therefore a key concern before widescale deployment of CCS can be used to address worldwide decarbonization goals. Electrochemical decomposition is one viable route to neutralize these harmful compounds. The circulating emission control waterwash system, commonly installed at the end of the flue gas treatment trains to minimize amine solvent emissions, plays an important role to capture N-nitrosamines and control their emission into the environment. The waterwash solution is the last point where these compounds can be properly neutralized before becoming an environmental hazard. In this study, the decomposition mechanisms of N-nitrosamines in a simulated CCS waterwash with residual alkanolamines was investigated using several laboratory-scale electrolyzers utilizing carbon xerogel (CX) electrodes. H-cell experiments revealed that N-nitrosamines were decomposed through a reduction reaction and are converted into their corresponding secondary amines thereby neutralizing their environmental impact. Batch-cell experiments statistically examined the kinetic models of N-nitrosamine removal by a combined adsorption and decomposition processes. The cathodic reduction of the N-nitrosamines statistically obeyed the first-order reaction model. Finally, a prototype flow-through reactor using an authentic waterwash was used to successfully target and decompose N-nitrosamines to below the detectable level without degrading the amine solvent compounds allowing them to be return to the CCS and lower the system operating costs. The developed electrolyzer was able to efficiently remove greater than 98% of N-nitrosamines from the waterwash solution without producing any additional environmentally harmful compounds and offers an effective and safe route to mitigate these compounds from CO2 capture systems.

Predicting aerosol size distribution development in absorption columns

There are two main mechanisms for amine emissions from absorption columns. The first is connected to the volatility of amine, determining the gaseous concentration. The second mechanism is via aerosol droplets containing amine. Recently, aerosol based emissions in g/Nm3 were identified from typical PCCC plants (Khakharia et al., 2013). Mechanisms for aerosol formation, aerosol growth, emissions related to aerosol formation and in particular the development and testing of aerosol emission reducing systems for amine based post-combustion, are presently under study. However, there is still limited information available in the open literature.In some recent studies, the effect of water wash and demisting equipment was studied and results indicate that aerosol droplets still pass through these equipment sections. On the other hand, water wash systems help in increasing the droplet size as well as reducing both gas phase and aerosol based emission. However, this does not completely solve the problem (da Silva et al., 2013). Recently, modeling studies for mono-disperse droplet swarms are published (Majeed et al., 2017a, 2017b; Majeed and Svendsen, 2018a, 2018b). However, results for multi-sized droplet swarms and for droplet size distributions are missing.Droplets can be described by their size, temperature and composition. All droplet populations will have a size distribution, being just as important as any other parameter. Performing a distribution analysis is the best way to determine the sizes of droplets in a particular stream at any point in an absorber.In this work, both a multi-droplet size model and a size distribution model are implemented. The multi-droplet size model is used for validation and results are in line with findings from the mono-disperse model by (Majeed et al., 2017b; Majeed and Svendsen, 2018a). Droplet distribution model results are compared with experimental data from Toshiba (Fujita, 2017) and reasonable agreement is found. The development of inlet droplet distributions through an absorber and water-wash system is modelled for several flue gas sources. It is found that the outlet distribution mean size increases with inlet gas CO2 concentration. Similarly, the outlet mean droplet size decreases and the size distribution width increases with incoming droplet number concentration.

Effect of water wash on mist and aerosol formation in absorption column

Environmental issues regarding solvent emissions can hamper the realization of state of the art post combustion CO2 capture (PCCC). These emissions stem from the emitted flue gas from which CO2 has been recovered and are due to volatile solvent in gas form and solvent carrying aerosols, either formed in the absorption column or carried over from an up-stream unit and contaminated by solvent in the absorber. The issue of aerosol-based emissions has only recently been reported for a PCCC process and very little information is available in this area. It is therefore important to understand and characterize the mechanisms of aerosol formation and growth so that appropriate actions can be taken in reducing the total amine emissions. From the literature and common practice, it is known that the use of a water wash section in a CO2 capture column can reduce the total amine emissions from these plants. This is mainly a reduction in gaseous solvent content whereas emissions caused by aerosols may not be removed. Moreover, typical demisting equipment has low efficiency when the droplets or particles are in the range 0.1–3µ. It is thus very important to be able to predict the behavior of these aerosols passing through a water wash section.In this study, we focus on the effect of water wash on aerosol composition and growth. It is found that water wash systems help in reducing both gaseous and aerosol-born amine emission. Aerosol droplets grow extensively in the water wash section because of water condensation and this may simplify subsequent removal in a demister. Droplet growth is found to be highly sensitive to gas phase amine depletion or content increase caused by high droplet number concentrations. Variations in operating parameters of the absorber and water wash columns were found to have effect on droplet growth and emission levels.

Selective Removal of Nitrosamines from a Model Amine Carbon-Capture Waterwash Using Low-Cost Activated-Carbon Sorbents.

Nitrosamines generated in the amine solvent loop of postcombustion carbon capture systems are potent carcinogens, and their emission could pose a serious threat to the environment or human health. Nitrosamine emission control strategies are critical for the success of amine-based carbon capture as the technology approaches industrial-scale deployment. Waterwash systems have been used to control volatile and aerosol emissions, including nitrosamines, from carbon-capture plants, but it is still necessary to remove or destroy nitrosamines in the circulating waterwash to prevent their subsequent emission into the environment. In this study, a cost-effective method for selectively removing nitrosamines from the absorber waterwash effluent with activated-carbon sorbents was developed to reduce the environmental impact associated with amine-based carbon capture. The results show that the commercial activated-carbon sorbents tested have a high capacity and selectivity for nitrosamines over the parent solvent amines, with capacities up to 190 mg/g carbon, under simulated amine waterwash conditions. To further reduce costs, an aerobic thermal sorbent regeneration step was also examined due to the low thermal stability of nitrosamines. To model the effect of oxidation on the sorbent performance, thermal- and acid-oxidized sorbents were also prepared from the commercial sorbents and analyzed. The chemical and physical properties of nitrosamines, the parent amine, and the influence of the physical properties of the carbon sorbents on nitrosamine adsorption was examined. Key sorbent properties included the sorbent hydrophilicity and hydrophobicity, surface pKa of the sorbent, and chemical structure of the parent amine and nitrosamine.

Field Measurement of Amine Aerosol by FTIR and Phase Doppler Interferometry

The emission of volatile compounds is an environmental and economic concern for CO2 capture by amine scrubbing. The condensation of amine species into aerosol is the main cause of volatile amine emissions. Current mitigation methods, including water wash, are not effective at preventing the atmospheric release of aerosol. This study focuses on the observation of aerosol at three amine scrubbing pilot plants.Fourier Transform Infrared Spectrometry (FTIR) sampling was performed in a pilot plant at the University of Texas at Austin. SO2 injection increased the emission of PZ solvent at a 1:1 molar ratio, and the injection of vaporized sulfuric acid increased amine emissions at a rate of 3 mols PZ/mol H2SO4. The slipstream pilot plant operated by the University of Kentucky utilized MEA to scrub CO2 from the flue gas stream of a coal-fired power plant. Bypassing caustic pretreatment and allowing SO2 to enter the absorber column increased MEA emissions. A 4% increase in the outlet CO2 resulted in a 10% reduction of amine emissions. A simplified water wash system was found to be ineffective at curtailing aerosol emissions.Phase Doppler Interferometry (PDI) and FTIR sampling were performed simultaneously at the National Carbon Capture Center. Using a blower between the water wash and absorber column instead of upstream of the absorber column resulted in a decrease in MEA emissions. The use of the intermediate blower instead of the upstream blower resulted in fewer, smaller aerosol drops. Decreasing the CO2 removal resulted in reduced amine aerosol emissions. Lower CO2 correlated with a lower aerosol concentration in the treated flue gas, but the aerosol sizes were significantly larger and resulted in overall increased amine emissions. Increasing the water wash temperature was found to increase average aerosol size and the amine concentration within the aerosol phase, resulting in an overall increase in amine emissions. By using the particle size distribution and aerosol concentration observed by PDI, the total liquid volume in the aerosol phase was calculated. Comparing this calculated quantity with the amine emissions observed using the FTIR allowed the approximate amine concentration in the aerosol phase to be determined.

Reliability evaluation of a Gas Turbine Water Wash System – A case study

In this article, a reliability analysis was carried out on a Gas Turbine Water Wash System used for washing the compressors of three (3) GE Frame 7 EA Gas Turbines using Weibull Distribution. Note that availability of this system is crucial to recovering compressor efficiency and by extension generation capability that has been lost due to contaminants on the compressor blades. This system therefore, helps maintain and improve the reliability of the turbine and of plant-wide generation. The reliability analysis covered two failure modes for each piece of equipment and took into account the reliability of the system in two operational modes, off-line washing cycle and online washing cycle for a 300 h operational time. Based on the results obtained it can be concluded that the entire water wash system can be taken as 76% reliable based on a 300 h running time. It is more reliable to perform an online water wash than an off-line water wash by at least 4% based on a 300 h operating time. This increased reliability of the water wash system to perform an online water wash is due to an off-line water wash requiring additional equipment which must be run in series.In addition to the aforementioned analysis fault trees were created to model two scenarios which relate directly to the efficiency of the gas turbine compressors and the generation capability of the turbine: (1) the likelihood of no water being present when conducting a water wash; and (2) the likelihood of cold water being sent to the water wash manifold. Based on the estimated reliabilities, the likelihood of no water being present when conducting a water wash was found to be 3.7% and the likelihood of cold water being sent to the water wash manifold is 1.6%.

CO2 Removal from Biogas by Water Washing System

CO2 removal from biogas by water washing system was investigated with various parameters, including liquid/gas ratio, pressure, temperature, and CO2 content. The results indicate that CO2 removal ratio could reach 34.6%–94.2% as liquid/gas ratio increased from 0.14 to 0.50. Increasing pressure (from 0.8 to 1.2MPa) could improve gas purification with a constant inflow rate of gas. Temperature played a key role in the process and lower temperature in absorption tower was beneficial for reducing CO2 content. CO2 removal ratio could reach 24.4%–83.2% when CO2 content in the simulated gas was 25%–45%. The lowest CO2 content after absorption was 2.6% at 1.2MPa with 400L·h-1 gas flow and 200L·h-1 water flow, which meets the requirement of CO2 content in natural gas for vehicle fuel.

Application of electrostatic precipitator in collection of smoke particles from hospital wastes combustion

The paper reports the development and implementation of a cost-effective electrostatic precipitator (ESP) prototype for the medical wastes incinerator of university hospital centre (CHU) of Sidi-Bel-Abbes, using a water washing system for cleaning electrodes. The impact of medical waste incineration on human health is a topical debate. The incineration process is a safe mode of disposal [OK] of such waste, but it is not an effective solution and needs a pollution control system. Generally, in Africa, cost is the major constraint for manufacturers and users. A half-scale ESP model was initially used for an experimental study in the laboratory. Thereafter, a full-scale model was produced and installed for the incinerator based on the optimal values obtained from this preliminary study.

Evaluation of amine emissions from the post-combustion CO2 capture pilot plant

In this work, we evaluated amine emissions from 10ton-CO2/day scale pilot plant in Mikawa Power Plant of Sigma Power Co. Ltd. within TS-1 solvent. Firstly, we investigated that how sampling gas flow rate affects measured value of amine concentration in flue gas by using on-line sampling method with PTR-MS analyzer. It was found that the error from an iso-kinetic sampling rises sharply for lower sampling velocities and in the range of higher sample stream velocities, however the error is lower. Secondly, we compared between beginning of operation and 2,800hours operation in terms of amine emissions at Mikawa pilot plant under one set of conditions. At beginning of operation, there were no degraded amines in TS-1 solution. Thus, there were no amine emissions of degraded amines. However, at 2,800hours operating, in addition to TS-1 emissions, some quantity of emissions of degraded amines were detected even though degraded amines were much less than TS-1 main amine in TS-1 solution. Toshiba improved operating conditions such as plant system, water wash system to reduce the amount of amine emissions. As a result, the latest tests showed lower emissions of less than 1 ppm(v/v) at 2,800hours operation. A concentration of degraded amine [D] in TS-1 solution at 2,800hours operation, which was nearly detection limit, was lower than other degraded amines. Nevertheless, degraded amine [D] accounted for the greater part of amine emissions after water wash was improved. This result suggested that it is crucial to reduce the volatility of emitted degraded amines in order to improve performance of suppression amine emissions further. Then, finally we evaluated effect of addition acid to reduce the volatility of degraded amine [D]. The results in diluted aqueous amines at 40°C showed that effectiveness of acid for reducing amine volatility is in the order: sulfuric acid > oxalic acid carbonic acid produced by 10%CO2 > boric acid.

CFD Prediction and Experimental Measurement of Blade Water Coverage in a Diesel Turbocharger

A turbocharger unit for diesel engine is often equipped with a built-in online water washing system and its performance is not always satisfactory because of efficiency declination due to deposit accumulated on blade surfaces not being washed away. In this study, a systematic approach of using experimental measurements and computational fluid dynamics (CFD) is adopted to analyse liquid/gas two-phase flow associated with a turbocharger water washing system, in order to understand the underlying flow physics. A medium-sized diesel engine turbocharger configuration is chosen for this purpose. Experiments are focussed on blade surface temperature measurements, while CFD modelling with a coupled Eulerian/Lagrangian method is used for capturing the complex gas/liquid two-phase flow behaviours inside the induction duct and the blade passage. It was found that numerical predictions are in a good agreement with experimental data in terms of temperature distributions of the blade leading edge region and water coverage over the blade ring. Other flow features such as the water droplet trajectories and the particle size distributions are also explored and analysed in further details, and they are useful for understanding the deposit removal mechanism.

STUDIES RELATING BROWNING AT THE CALYX SURFACE TO HANDLING OF 'ROYAL GALA' APPLES IN WATER DUMPS

In the past five years, browning symptoms at the calyx end of 'Braeburn', 'Royal Gala' and 'SciEarly'/Pacific Beauty™ apples have been observed during storage following packing. The symptoms appear as a continuous or discontinuous dark brown ring within the surface of the calyx cavity, and appear to have developed in response to the collection of liquid within the cavity. Observations also suggest that the symptoms develop mostly in response to the process of packing, although symptoms may develop in storage before packing, and that fruit from some orchards may be more prone than fruit from other orchards. The symptoms were very similar to chlorine burn. However, the appearance of symptoms before packing suggests that a preharvest predisposition factor may be involved. In this study, the effect of time in a chlorine-based water wash and dump system on the development of calyx browning symptoms in controlled atmosphere (CA)-stored 'Royal Gala' apples was studied. Fruit from CA storage were passed through the water dump and wash system and packed into cartons with or without polyliners, and then stored for 8 weeks in air before being evaluated for calyx browning symptoms. In addition, spray diaries of those orchards affected by calyx browning symptoms were examined for relationships between pesticide, fungicide and calcium use and the incidence of calyx browning symptoms. The findings indicate that the time fruit spend in chlorinated water following brushing affects the incidence of the calyx damage and that a final rinse with potable water reduced the incidence. Predisposition to developing symptoms was not related to fungicide or pesticide use, but was related to the number of early and late calcium sprays used. It is concluded that the calyx browning symptoms are probably associated with fruit that sustained some surface growth stress in the calyx, with the expression accelerated by the use of chlorinated water.

Pilot study of Japanese cedar pollen exposure using a novel artificial exposure chamber (OHIO Chamber)

SummaryFor basic and clinical studies of Japanese cedar (JC) pollinosis and its treatment, experimental facilities for exposure to pollen under stable environmental conditions are becoming increasingly desirable. We developed an artificial exposure chamber (OHIO Chamber) that allows the dispersal of fixed concentrations of JC pollen in stable environments with a unique pollen supply system, air flow system for fixing the concentration of JC pollen, system for monitoring the number of pollen grains, and automated pure water washing and drying system. In the chamber, temperature and relative humidity (RH) could be successfully maintained at 22±1.1 °C and 45±5%, respectively. The spatial distribution of pollen concentrations in the chamber was within 10% of target, including when subjects were present. Only a few or no pollen grains were detected in the chamber after automatic washing and drying. We conducted a pilot tolerability and safety study in 15 JC pollinosis patients who were exposed to 15 000 pollen grains/m3 for 2 h. Symptoms manifested on average 33 min after start of exposure. The subjects experienced no serious side‐effects, and pollen exposure at 15 000 grains/m3 was confirmed safe. After exposure, the number of intranasal and intraocular pollen grains was 469 and 602, respectively. The lower number of pollen grains in the nose than in the eyes was considered due to sneezing and nasal discharge. Further studies are needed to clarify the number of pollen grains required for the occurrence of symptoms in the OHIO Chamber.

Charcoal-Adsorption, Water-Washing, and Air-Dilution Systems to Reduce Diesel Emissions With Special Emphasis on Odor Reduction

Direct injection (DI) diesel engines emit a far more disagreeable exhaust odor than gasoline engines, especially at low temperatures and at idling. There is no proper system of odor reduction in these conditions in DI diesel engines. This study investigated a charcoal-adsorption system to reduce exhaust emissions including odor in a DI diesel engine at idling under no load operations, where exhaust temperatures are low. Low temperature exhaust gas is passed through a charcoal adsorber. Charcoal has the property of adsorbing odorous gas components. Here odor is reduced more than 0.5 points, a significant odor reduction depending on the engine and adsorber conditions. Exhaust noise, nitrogen oxides (NOx), and eye irritation are also significantly reduced with the system. This study further investigated water-washing system for odor reduction in DI diesel engines at low exhaust temperature conditions. Exhaust gas is passed through the water in the water tank of the system. Aldehydes, organic acids, and other oxygenated components, which are the main odorous components in exhaust gases, are dissolved in water reducing exhaust odor significantly. Eye irritation of exhaust gases is also significantly reduced. The water-washing system not only reduces the odor and eye irritation but also carbon dioxide (CO2), carbon monoxide (CO), NOx, and smoke are reduced more than 20–30%. The sound level of exhaust gases is also reduced 10–15dB with this system. Air dilution is also attempted in this study for odor reduction where a large amount of fresh air is mixed with exhaust gases. Here dilution ratio of 5 is used. Air dilution alone can reduce odor about 0.5 points. However, odor about 1.5–1.6 points (about 60–65%) can be reduced when air dilution is used in combination with charcoal-adsorber and water-washing system, and odor level is lowered below level 2, which is acceptable for all human beings.

The design of strong electrolysis water washing system which used quality engineering

The design of strong electrolysis water washing system which used quality engineering

DURABILITY OF WOOD‐BASED versus COAL‐BASED GAC

Wood‐based granular activated carbon (GAC) has been used successfully both in pilot applications and in full‐scale filter applications, but its durability during backwashing has not been evaluated in a side‐by‐side study with bituminous coal‐based GAC. The objective of this study was to compare the durability of these two types of GAC when subjected to 500 cycles of backwashing with an air–water wash system. GAC durability was evaluated by measuring the change in carbon bed height, pressure drop, filter effluent water quality, and particle characteristics as a function of backwashing. The results showed that the durability of the wood‐based and the coal‐based GAC was similar throughout the duration of the study.

最近のアーク炉設備の動向

An electric arc furnace itself has made a few drastic developments and improvements for the past few years. However, eccentric bottom tapping used in different steel plants in Europe coupled with operational know-how has shown good results which has also been introduced into this country and same good results are expected.Electrode regulating system by VVVF (variable voltage variable frequecy) or hydraulic pressure type electrode controller with hydraulic pressure servovalve is in a practical use.Power consumption has been saved by 3 to 10 percent by computer control equipped with arc furnaces.Scrap preheater has been popular as energy saving facility. Recent trend is to adopt such a system to pass waste gas in series in order to have better efficiency of the scrap preheater.At present, as solution of white fume and bad odor water washing system and simple after burning type will be most practical.Superiority of DC arc furnace is to reduce electrode consumption DC power source which occupies the large portion of equipment investment cost is getting relatively low, thus inviting an attention of people who are interested in the facility.

A Taro Cleaner for Wetland Paddy Culture

ABSTRACT A portable taro cleaning unit for wetland field condi-tions was developed. Modified corn-husking rollers were combined with a water-wash system and removed the hair-roots from the taro corms. Time trials compar-ing hand-harvest rates with two harvest methods utilizing the cleaning unit showed that harvesting rates of field workers increased when using the cleaner.

Continuous deionized water washing system for semiconductor devices

Designed for use on a batch production basis, the apparatus provides for the recirculating water to pass through an ion exchange resin after washing the devices. Two conductivity cells, one on either side of the washing point, measure the specific resistivity of the circulating water; this is 20 × 106 Ω cm at 18° C in water about to pass over the devices, i.e. deionized water. The apparatus is constructed mainly of polythene and P.V.C. to avoid contamination of the water.

The Value of the Roentgenogram in Edentulous Mouths

In this work, we evaluated amine emissions from 10ton-CO2/day scale pilot plant in Mikawa Power Plant of Sigma Power Co. Ltd. within TS-1 solvent. Firstly, we investigated that how sampling gas flow rate affects measured value of amine concentration in flue gas by using on-line sampling method with PTR-MS analyzer. It was found that the error from an iso-kinetic sampling rises sharply for lower sampling velocities and in the range of higher sample stream velocities, however the error is lower. Secondly, we compared between beginning of operation and 2,800 hours operation in terms of amine emissions at Mikawa pilot plant under one set of conditions. At beginning of operation, there were no degraded amines in TS-1 solution. Thus, there were no amine emissions of degraded amines. However, at 2,800 hours operating, in addition to TS-1 emissions, some quantity of emissions of degraded amines were detected even though degraded amines were much less than TS-1 main amine in TS-1 solution. Toshiba improved operating conditions such as plant system, water wash system to reduce the amount of amine emissions. As a result, the latest tests showed lower emissions of less than 1 ppm(v/v) at 2,800 hours operation. A concentration of degraded amine [D] in TS-1 solution at 2,800 hours operation, which was nearly detection limit, was lower than other degraded amines. Nevertheless, degraded amine [D] accounted for the greater part of amine emissions after water wash was improved. This result suggested that it is crucial to reduce the volatility of emitted degraded amines in order to improve performance of suppression amine emissions further. Then, finally we evaluated effect of addition acid to reduce the volatility of degraded amine [D]. The results in diluted aqueous amines at 40 °C showed that effectiveness of acid for reducing amine volatility is in the order: sulfuric acid > oxalic acid carbonic acid produced by 10%CO2 > boric acid.