Flue Gas Treatment Research Articles

Cost-effective and eco-friendly synthesis of MIL-101(Cr)-CS from chromium-containing sludge waste and its exploration of adsorption anddehumidification performance

In the context of a circular economy, there is an increasing need for more sustainable waste management solutions to recycle and utilize elements in waste. Chromium-containing sludge is a common and difficult to treat industrial waste, but there is currently no effective treatment method to recycle the “chromium resource” in it. On the other hand, the metal-organic framework material MIL-101(Cr) has high specific surface area and large pore volume, good thermal and chemical stability, usually analytically pure Cr(III) is used with the help of hydrofluoric acid (HF) which salt is prepared, and its preparation cost is high, and HF is toxic and harmful to the environment. Here, we report a new method for treating industrial chromium-containing sludge. The method uses the chromium in the chromium-containing sludge as the chromium source, and adopts X-ray diffraction (XRD), scanning electron microscope (SEM), infrared and pore size analysis. The experimental results show that the particle morphology of MIL-101(Cr)-CS synthesized from chromium-containing sludge as chromium source is similar to that of MIL-101(Cr)–HF prepared from analytical pure Cr(III). High specific surface area (2412 ​m2/g), large pore volume (1.83 ​m3/g). Furthermore, adsorption experiments show that MIL-101(Cr)-CS has a higher adsorption capacity for CO, CO2, and gaseous water, which makes it a potential candidate for some dehumidification devices and flue gas treatment. This work provides a new idea for the high-value utilization of “chromium resources” in chromium-containing wastes.

RETRACTED: Optimization scheduling of virtual power plant with carbon capture and waste incineration considering P2G coordination

In order to promote multi-energy complementation and low carbonization, an optimal scheduling model of virtual power plant (VPP) with carbon capture and waste incineration considering power-to-gas coordination is proposed. By introducing the collaborative utilization framework with a carbon capture plant-power to gas (P2G)-gas unit system, the CO 2 in the carbon capture can be used as the raw material of P2G, which produces natural gas to be supplied to the gas unit. In addition, the power consumption of the carbon capture and the flue gas treatment can be transferred through joint dispatching to smooth the fluctuation of renewable energy output, so that the wind power and photovoltaic can be indirectly dispatchable and flexibly utilized. In view of the high dimensional nonlinearity of the proposed optimization model and the difficulty in solving it, a new Gaussian compound differential evolution algorithm is designed to solve the model. The simulation results show that the proposed model and method can provide peak load shifting capacity and improve renewable energy consumption, effectively reducing the cost and carbon emission of VPP.

Co-Benefits of Pollutant Removal, Water, and Heat Recovery from Flue Gas through Phase Transition Enhanced by Corona Discharge.

Pollutant removal and resource recovery from high-humidity flue gas after desulfurization in a thermal power plant are crucial for improving air quality and saving energy. This study developed a flue gas treatment method involving phase transition enhanced by corona discharge based on laboratory research and established a field-scale unit for demonstration. The results indicate that an adequate increase in size will improve the ease of particle capture. A wet electrostatic precipitator is applied before the condensing heat exchangers to enhance the particle growth and capture processes. This results in an increase of 58% in the particle median diameter in the heat exchanger and an emission concentration below 1 mg/m3. Other pollutants, such as SO3 and Hg, can also be removed with emission concentrations of 0.13 mg/m3 and 1.10 μg/m3, respectively. Under the condensation enhancement of the method, it is possible to recover up to 3.26 t/h of water from 200 000 m3/h saturated flue gas (323 K), and the quality of the recovered water meets the standards stipulated in China. Additionally, charge-induced condensation is shown to improve heat recovery, resulting in the recovery of more than 43.34 kJ/h·m3 of heat from the flue gas. This method is expected to save 2628 t of standard coal and reduce carbon dioxide emission by 2% annually, contributing to environmental protection and global-warming mitigation.

Flue Gas Composition and Treatment Potential of a Waste Incineration Plant

Waste-to-energy (WtE) incineration is an important technique in waste management systems and waste hierarchy. It is used to treat approximately 63% of the waste in European countries. The flue gas volumetric rate and its composition are essential to determine and monitor the emissions from waste incineration plants. This paper presents two methodologies used to evaluate the emissions from incinerators during the design phase. The first consists of a set of equations applicable in Excel (calculation model), while the second is the built-in components in Ebsilon 13.2 software which simulates the emissions from a furnace. This paper also proposes a comprehensive flue gas cleaning system for a simulated waste incineration plant in Jordan. According to Ebsilon, the results showed that for a 25 kg/s loading rate, there was 258,514 mg/Nm3, 749.90 mg/Nm3, 890.20 mg/Nm3, and 717 mg/Nm3 of CO2, NO2, SO2, and HCL, respectively. It was noted that these values relate to 1.5 of excess air ratio, where the effect of excess air ratio as the main driver for any combustion process was examined. The calculation method (set of equations) evaluated the flue gas volumetric rate, the CO2 emissions, and N2O and SO2 levels. Ebsilon allows for simulation of the treatment stages and calculates the amount of materials required. Selective non-catalytic reduction (SNCR) (a built-in component in the Ebsilon library) was used to treat the NO2 emissions. For 1.5 of excess air ratio, those emissions were reduced from 749 mg/Nm3 to 180 mg/Nm3, while the Ca(OH)2 injector used to treat the SO2 and HCL emissions reduced emissions from 890.20 mg/Nm3 and 717 mg/Nm3 to 44 mg/Nm3 and 7.16 mg/Nm3, respectively. Regarding the reduction in CO2, the spherical carbon absorption concept was simulated using 9.4 kg/s of carbon which was adequate to verify a 91% reduction rate of CO2. Furthermore, the calculation model was validated and approved as a valuable model to predict the flue gas volume, the oxygen required, and flue gas emissions at the design stage.

Biofixation of Air Emissions and Biomass Valorization-Evaluation of Microalgal Biotechnology.

This research appraised the simultaneous biofixation, that is not quite common in scientific literature, of carbon dioxide (CO2) and nitric oxides (NOx) by microalgae species Chlorella vulgaris, Haematococcus pluvialis, and Scenedesmus subspicatus. The experimental design was established by five treatments with gas concentrations between control-0.04% of CO2, 5 to 15% of CO2, and 30 to 100ppm of NOx. Parameters such as pH, growth, productivity, lipids, protein, carbon/ nitrogen ratio, and astaxanthin were evaluated. For all species, the maximal growth and productivity were achieved with 5% of CO2 and 30ppm of NOx. Regarding protein content, for all the three species, better results were obtained at higher concentrations of CO2 and NOx. These results prove the microalgae capacity for CO2 and NOx biofixation and reuse of biomass as a source of high value-added products, such as lipids, proteins, and astaxanthin. These findings support the indication of these species for flue gas treatment process and use in biorefineries systems.

Photocatalytic NOx mitigation under relevant conditions using carbon nanotube-modified titania

Although a majority of photocatalysts exhibit improved NO conversion to NO2, the performance in the oxidation of NO2, the more toxic form of NOx, to nitrate remains a challenge; in addition, the performance of hybrid photocatalysts under practical conditions is unclear. This study demonstrates the use of carbon nanotube-TiO2 (CNT-TiO2) photocatalyst films for effective transformation of NOx into nitrates. Using the objective figure of merit for NOx abatement, DeNOx index, the catalyst performance in a laminar-flow reactor was evaluated under simulated conditions that are relevant in abating NOx. The conditions probed include relative humidity (RH), initial NOx concentration, reactor geometry (headspace distance), and state of the catalyst (fresh vs. recycled). Our results reveal CNT-TiO2 significantly outperforms P25 despite exhibiting comparable NO conversion at low RH. P25 experiences a 66% reduction in DeNOx at high RH compared to low RH while CNT-TiO2 only incurs a 27% reduction. For recycled photocatalysts, this disparity becomes even more pronounced; CNT-TiO2 experiences a 49% reduction in DeNOx at high RH, whereas P25 experiences a 134% reduction. In addition, mass transfer from the bulk airflow limits NO conversion when the reactor headspace is too large (>3 mm), due to limited diffusion of NOx to the photocatalyst surface. Our findings highlight the importance of headspace distance, a parameter that has mostly been overlooked in reactor design for photocatalytic oxidation of NOx, but which dictates the optimal catalyst configuration for flue gas treatment. The remarkable DeNOx activity of CNT-TiO2 over a wide range of RH levels is rationalized based on the ratio of physisorbed-to-chemisorbed water on the photocatalyst surface.

Mechanochemically induced solid-state CO2 capture during the synthesis of SnO2 nanoparticles

Mechanochemistry offers a versatile method to synthesize metal oxides by the reaction of the corresponding metal salt and Na2CO3, with CO2 as a by-product. It is possible to monitor the progress of the reaction and even calculate conversion values based on the measured pressure increase in the milling equipment. We studied the kinetics of tin oxide formation in the mechanochemical reaction between SnCl2 and Na2CO3. Our systematic experiments revealed unexpected complexity in the temporal pressure function depending on the exact composition of the reactant mixture: the pressure exhibited a clear local maximum, and pressure values even dropped close to their starting value by the end of the reaction when Na2CO3 was present in 100% excess. This anomaly can be explained by realizing that CO2 is captured as NaHCO3 in a process analogous with aqueous flue gas treatment, and it can also be released in the secondary reaction between unreacted SnCl2 and NaHCO3. Here we provide experimental evidence to support this hypothesis and to draw attention to the pitfalls of oversimplifying pressure-based conversion calculations in mechanochemical processing.

An integrated biological system for air pollution control in WtE plants and interaction between NO reduction and toluene oxidation

The abatement of NO and VOCs in the flue gas from WtE plants is of great significance for improving the atmospheric environmental quality at present. In this study, a device of absorption-bioreactor coupling biotrickling-filter (ABR-BTF) was built to realize the simultaneous removal of NO and VOCs, in which the chemical absorption-bioreactor (ABR) was used for reducing NO and the biotrickling-filter (BTF) was employed for eliminating toluene. When the simulated flue gas containing 400 mg m−3 NO and 150 mg m−3 toluene passed through the system for 30 s, the removal efficiency of NO and toluene reached 85% and 90%, respectively. In contrast with the single ABR segment, the loss rate of NO complexing absorber was reduced by 85% in ABR-BTF. Meanwhile, a variety of novel bacterial genera in the field of biological denitrification and VOCs elimination were discovered within the integrated system biome. Thereinto, Candidatus_Cloacamonas and Syntrophomonas produced the hydrogen, which could as electron donors be consumed by the dissolved oxygen species during the process of VOCs degradation, promoting the biological reduction and reducing the loss rate of complexing absorbent in the ABR portion. Meanwhile, Tisierella and Desulfitobacterium could reduce sulfite to S2−, so that part of the complexing absorbent was transformed into FeS and re-entered into the circulation system through the redox reaction with Fe(III). The integrated biological purification system can efficiently remove NO and VOCs simultaneously, and overcome the problems of insufficient microbial reduction rate for poor hydrophobic VOCs, which will provide a fundamental for the optimization and industrial application of the biological technology in WtE plants flue gas treatment.

Technology development and cost analysis of multiple pollutant abatement for ultra-low emission coal-fired power plants in China

The implementation of ultra-low emission (ULE) limits (SO2: 35 mg/m3, NOx: 50 mg/m3, PM: 10 mg/m3) promoted the development of flue gas treatment technologies in China. Pollutant control technology development for Chinese coal-fired power plants was summarized and an analysis of the applicability and cost of pollutant control technologies was conducted. Detailed data were collected from 30 ultra-low emission coal-fired units across China. Based on a cost analysis model, the average unit power generation incremental costs were 0.0144 and 0.0095 CNY/(kW·hr) for SO2 and NOx control technologies, respectively. The unit power generation incremental cost of twin spray tower technology was 7.2% higher than that of dual-loop spray tower technology. The effect of key parameters on operating cost was analyzed. The unit power generation incremental cost increased because of increments in the electricity price for SO2 control technology and the price of the reductant in NOx control technology. With high sulfur content or NOx concentration, the unit power generation incremental cost caused by pollutant control increased, whereas the unit pollutant abatement cost decreased. However, the annual operating hours or load increased, thereby leading to a decline in unit power generation incremental cost and unit pollutant abatement cost.

Crown Nanopores in Graphene for CO2 Capture and Filtration

With growing concerns about global warming, it has become urgent and critical to capture carbon from various emission sources (such as power plants) and even directly from air. Recent advances in materials research permit the design of various efficient approaches for capturing CO2 with high selectivity over other gases. Here, we show that crown nanopores (resembling crown ethers) embedded in graphene can efficaciously allow CO2 to pass and block other flue gas components (such as N2 and O2). We carried out extensive density functional theory-based calculations as well as classical and ab initio molecular dynamics simulations to reveal the energetics and dynamics of gas transport through crown nanopores. Our results highlight that the designed crown nanopores in graphene possess not only an excellent selectivity for CO2 separation/capture but also fast transport (flow) rates, which are ideal for the treatment of flue gas in power plants.

A novel strategy to reduce carbon emissions of heavy oil thermal recovery: Condensation heat transfer performance of flue gas-assisted steam flooding

• Flue gas-assisted steam flooding was investigated to reduce carbon emissions. • Flue gas-assisted steam flooding improved the oil recovery factor by 20.02%. • Flue gas treatment and injection processes for steam injection wells were designed. • Site application showed that the underground CO 2 storage rate was 74.5%. • The novel strategy is suitable for a small-scale steam generator used in oilfields. In this paper, the flue gas-assisted steam flooding process from a novel perspective of condensation heat transfer performance was investigated to reduce carbon emissions of heavy oil thermal recovery. More specifically, steam condensation heat transfer coefficients with and without flue gas were tested, and heat transfer and oil recovery for steam flooding assisted by flue gas in a sandpack were studied. The experimental results indicate that the existence of the gas film on the condensation block increased the heat transfer resistance and decreased the condensation heat transfer coefficient. The gas channeling of flue gas provided a flow path for the steam and promoted heat transfer deep into the sandpack. Flue gas-assisted steam flooding improved the oil recovery factor by 20.02% compared with steam flooding, and 46.4% of the injected flue gas could be stored in the sandpack. The storage of flue gas could be divided into two parts: the flue gas dissolved in the residual heavy oil and the flue gas trapped in the porous media. Flue gas treatment and injection processes for steam injection wells were designed. Site application of flue gas-assisted steam injection showed that the oil production increased by 28.3%, and the underground CO 2 storage rate was 74.5%. The novel strategy of flue gas treatment and injection with steam greatly reduces the carbon emissions of heavy oil thermal recovery, which is very applicable for small-scale steam generator used in oilfields.

CO2 mineralization of carbide slag for the production of light calcium carbonates

The production of polyvinyl chloride by calcium carbide method is a typical chemical process with high coal consumption, leading to massive flue gas and carbide slag emissions. Currently, the carbide slag with high CaO content is usually stacked in residue field, easily draining away with the rain and corroding the soil. In this work, we coupled the treatment of flue gas and carbide slag to propose a facile CO2 mineralization route to prepare light calcium carbonate. And the route feasibility was comprehensively evaluated via experiments and simulation. Through experimental investigation, the Ca2+ leaching and mineralization reaction parameters were determined. Based on the experiment, a process was built and optimized through Aspen Plus, and the energy was integrated to obtain the overall process energy and material consumption. Finally, the net CO2 emission reduction rate of the entire process through the life-cycle assessment method was analyzed. Moreover, the relationship between the parameters and the CO2 emission life-cycle assessment was established. The final optimization results showed that the mineralization process required 1154.69 kW·h·(t CO2)−1 of energy (including heat energy of 979.32 kW·h·(t CO2)−1 and electrical energy of 175.37 kW·h·(t CO2)−1), and the net CO2 emission reduction rate was 35.8%. The light CaCO3 product can be sold as a high value-added product. According to preliminary economic analysis, the profit of mineralizing can reach more than 2,100 CNY·(t CO2)−1.

Understanding and improving the modular properties of high-performance SSZ-13 membranes for effective flue gas treatment

High-performance tube-supported standard oil synthetic zeolite-13 (SSZ-13) membranes were prepared using low-temperature ozone calcination and modularized in different-sized permeation cells. The hydrophobic SSZ-13 membrane exhibited robust, marked CO2/N2 separation performances at a H2O vapor partial pressure of 10 kPa at 50 °C (CO2 permeance of 1.3 × 10−7 mol∙m−2 s−1∙Pa−1 and CO2/N2 separation factor (SF) of ca. 31.5). However, these intrinsic values were obtained at high feed flow rates, where the optimal recovery of CO2 molecules cannot be obtained. Thus, we correlated membrane (permeance and SF) and feed stream (Reynolds number) properties, finding that convective mass transfer from feed to outer membrane surface (Sherwood number) was described by the Reynolds number and cell dimensions. This further accounted for the CO2 molar flux and CO2/N2 SF. Based on this, we proposed critical parameters (comprising total feed flow rate and pressure, and characteristic module dimension) to describe the representative module properties of the recovery, purity, and process efficiency (PE) for CO2. Finally, the PE of the membrane unit was improved in double-stage configuration, yielding noticeable improvements in CO2 purity and PE at the slight expense of CO2 recovery. Crucially, the process-based module properties were well understood and predicted using the feed stream properties.

Ecological and economic efficiency of the use of alternative energy technologies including hydrogen to reduce of the anthropogenic load in the central ecological area of the Baikal natural territory

The central ecological area of the Baikal natural territory covers some districts of the Irkutsk oblast and the Republic of Buryatia, located on the coast of the Lake Baikal. Due to the natural uniqueness and special status of doing economic activity, the assessment of the impact on the environment in this territory is very importance. An analysis of the functioning of energy objects showed that a significant part of the territory is provided with a centralized electricity supply with developed electric grid infrastructure. There are only a few remote settlements with autonomous electricity supply from diesel power plants. The main sources of pollution are numerous boiler houses that provide heat to the population, social and administrative institutions. In all, there are 98 heat energy sources in the territory, of which 66 (or 70%) use coal. The problems of environmental pollution are mainly caused by the use of coal in a small boiler house, worn-out equipment, and the lack of an appropriate level of flue gas treatment. The total estimated emission of pollutants into the atmosphere from heat energy sources is estimated at 20–25 thousand tons per year. In order to reduce the anthropogenic impact from energy objects, it is advisable to use renewable energy sources, hydrogen technologies, coal substitution with environmentally friendly fuels, use of electricity for heat energy supply, installation of environmental protection equipment and the implementation of energy-saving measures. The methodological approach and simulation models developed at MESI SB RAS were used to determine the competitiveness conditions of alternative technologies and energy carriers. The studies evaluated the environmental and economic efficiency of energy production technologies by using specific indicators: the capital intensity of reducing 1 ton of emissions and environmental capital return by 1 million rubles for the conditions of the central ecological area. The potential for reducing emissions into the atmosphere by use of renewable energy sources in autonomous energy supply areas is less than 1% of the current level of total emissions from energy objects. The potential for reducing emissions by replacing boiler houses with a capacity of less than 0,2 Gcal/h by a heat pump units is no more than 12%. The biggest environmental effect can be achieved by using alternative energy carriers including hydrogen instead of coal. Moreover, the potential for reducing emissions is 60% of the total emissions. In addition to these activities are the least capital intensive. The most effectively is the replacement of coal with natural gas. Rational gas consumption in the coastal areas of Lake Baikal is estimated at 175–190 thousand tons of equivalent fuel. The real possibility of transferring small boiler houses to gas arises during the construction of an export gas pipeline from Russia (through the territory of the Irkutsk oblast) to China via Mongolia, or by the small-scale production of liquefied natural gas. The most currently implemented direction is the use of electricity for heat energy supply. The potential volume of electricity to replace coal in boiler houses of the central ecological area is 1,3 TWh per year, however, the competitive electricity tariff is estimated less than 2 US c/kWh, which is several times lower than current tariffs. Hydrogen technology is currently very capital-intensive, but using it in a way similar to using electricity for heat eliminates pollutant and greenhouse gas emissions. Now days, there are no effective financial mechanisms aimed at stimulating the reduction of the anthropogenic pressure on the environment from existing energy sources, including for the use of alternative technologies. As the result, significant financial support is required in the form of special cost compensation mechanisms for energy producers and/or consumers.

Study on the effect of supercritical CFB boiler air preheater and flue gas treatment facilities on sulfur trioxide emission characteristics

The current situation of air pollution in China is very serious, and the control of non-conventional pollutants in addition to conventional air pollutants has received more and more attention. The emission of SO3 in flue gas has attracted widespread attention due to the environmental hazards and equipment problems caused by it, and the study of its emission characteristics and control strategies is the basis for national, local and industry to formulate relevant policies and implement emission control work. The SO3 monitoring and emission control study of a supercritical circulating fluidized bed boiler was carried out based on the controlled condensation method of on-site flue gas sampling, laboratory testing, and instrumental analysis of coal and ash samples, and the synergistic SO3 removal capability of the air preheater and flue gas treatment facilities was explored and summarized. The results showed that the SO3 co-removal rate of the four operating conditions of the test unit ranged from 74.34% to 88.51%, and the highest SO3 co-removal rate (88.51%) was achieved when the SNCR ammonia to nitrogen molar ratio was 1.2 and the slurry pH of the desulfurization system was 5.45 (primary tower) and 6.28 (secondary tower). During the test period, the differential pressure of the air preheater basically fluctuated between 1.245 kPa–1.326 kPa under the operating conditions of working condition 2, with no significant increase. For the same type of unit, the ammonia to nitrogen molar ratio and wet FGD slurry pH can be adjusted to reduce SO3 emissions.

Preparation of Porous Porcelain with Treated Flue Gas Desulfurization (FGD) Sludges the Foaming Agent

The potential of treated FGD sludge as foaming agent in ceramic porcelain were studied. The effect of treated FGD sludge content on phase composition, porosity and mechanical strength of porous ceramic were investigated. The result showed that the addition of treated FGD sludge improve the porosity. However, the increased porosity significantly reduced the flexural strength in sample after sintering at 1200°C for 3 hours. The porous of ceramic porcelain produced in this study can be used for insulation in high temperature application.

High efficiency desulfurization behavior by the sustainable low carbon utilization of carbide slag

For the purpose of the gradual decrease of calcium carbonate resources and reduction of carbon emissions in wet flue gas desulfurization process, the utilization process of carbide slag to replace limestone is systematically analyzed. The properties of carbide slag and limestone have been analyzed, and the mass transfer and reaction behaviors in desulfurization process have been calculated and comprehensively evaluated. Desulfurization performances have been also compared through response surface analysis method. The results show that the calcium content and specific surface area of carbide slag are higher than limestone, which is conducive to the dissolution and mass transfer rate. Therefore, carbide slag is suitable for the treatment of flue gas with high SO2 concentration. Desulfurization efficiencies of the two desulfurization agents of carbide slag and limestone under the optimal process are 99.15% and 96.53%, respectively. In conclusion, carbide slag can be used in desulfurization process to replace limestone. The consumption of carbide slag slurry in the desulfurization process is about half of limestone slurry at the same conditions, and the higher desulfurization efficiency of carbide slag is attributed to the higher mass transfer and dissolution rate. Utilization of carbide slag also reduces the carbon emission in desulfurization process and economic cost. The reduction amount of CO2 emission can reach to about 0.76 t /t carbide slag. This work provides a basis for the industrial application and desulfurization efficiency improvement of carbide slag as the desulfurizer.

The superhydrophobic coating with low‐temperature dew point corrosion resistance on an acid‐resistant steel substrate prepared by the electrodeposition method

AbstractThe acid‐resistant steel represented by 09CrCuSb (ND) steel that is widely used in flue gas treatment systems is easily prone to mixed‐acid dew point corrosion in the low‐temperature flue gas environment. To improve the corrosion resistance of ND steel in a low‐temperature dew point corrosion environment, here, a chromium–myristate hybrid (CMH) superhydrophobic coating is proposed as a low‐temperature dew point corrosion protective coating for the ND steel substrate. This superhydrophobic coating is deposited on the ND steel substrate (preplated dark nickel as a transition layer) by one‐step direct current electrodeposition. The electrochemical analysis from potentiodynamic polarization and electrochemical impedance spectroscopy and the immersion test show that the CMH superhydrophobic coating can significantly improve the corrosion resistance of the ND substrate. Therefore, the present study provides a feasible strategy for preventing the mixed‐acid dew point corrosion of ND steel in the low‐temperature zone.

Construction of Cu-BTC by carboxylic acid organic ligand and its application in low temperature SCR denitration

The removal of NO has always been a hot issue in the treatment of coal-fired flue gas. In this paper, a hydrothermal synthesis method was used to prepare porous denitration catalysts with polycarboxyl organic isomers (trimellitic acid, phthalic acid, and benzoic acid). And then developed as the NO removing catalysts for low temperature selective catalytic reduction (SCR) with NH3. XRD, BET, SEM, FTIR, XPS, Raman, H2-TPR, NH3-TPD and TG were used to analyze the crystallinity, microscopic morphology, surface functional groups and metal content. The results showed that: (1) From the crystal structure analysis, the catalyst prepared with 1,3,5 and 1,2,4-benzenetricarboxylic acid as ligands (1,3,5-A and 1,2,4-B) was Cu-BTC. (2) 1,3,5-A catalyst had a huge specific surface area, up to 1421.32 m2/g, and a pore volume up to 0.5798 cm3/g. (3) The prepared catalysts were applied to NH3-SCR denitration, and the catalyst with Cu-BTC structure had relatively high catalytic performance, and the overall catalytic capacity showed an increasing trend with the temperature. (4) 1,3,5-A catalyst had stability and catalytic activity. When the temperature was 270 °C, the denitration efficiency reached 83.87%. And within 8 h, the denitration efficiency was stable up to 82%.

Retention of trace elements in coal-fired flue gas by a novel heterogeneous agglomeration technology

Heterogeneous agglomeration (HA) is a very potential technology for coal-fired flue gas treatment. In this paper, the distribution and migration mechanisms of trace elements (TEs) such as Se, As and Pb in CFPPs were studied on a 30,000 m3/hr pilot-scale experimental platform. The influences of HA on the removal efficiency of gaseous and particulate TEs were well analyzed. The results showed that Se, As and Pb were enriched in fly ash, and their sensitivity to particle size is quite different. The content of Se was the highest in PM1, reaching 193.04 mg/kg at the electrostatic precipitator (ESP) outlet. The average particle size of the total dust before ESP increased significantly from 21.686 to 62.612 µm after injecting the heterogeneous agglomeration adsorbent, conducive to its further removal by ESP. In addition, the concentrations of gaseous Se, As and Pb in the flue gas decreased after adsorbent spray, and accordingly, their contents in the hierarchical particles increased, indicating that the adsorbent could effectively promote the adsorption of gaseous trace elements in fly ash and reduce the possibility of their escape to the atmosphere. Total concentrations of Se, As and Pb emitted by wet flue gas desulfurization (WFGD) are 0.223, 0.668 and 0.076 µg/m3, which decreased by 59.98%, 47.69% and 90.71%, respectively. Finally, a possible HA mechanism model was proposed, where chemical adsorption, physical condensation and collision agglomeration of gaseous TEs and fine particles with adsorbent droplets occurred to form larger agglomerates.