Condensable Particulate Matter Research Articles

Effect of the temperature control device on the emission character of condensable particulate matter from industrial heating plant

Condensable particulate matter (CPM) is one of the major emissions of primary particles in coal combustion. The removal efficiency of CPM using the temperature control device (TCD) based on the concept of a heat exchanger application with lower capital cost was investigated in an industrial heating plant. TCD operates without water and flue gas interactions and ensures efficient control of CPM emissions, and it also minimizes the potential ion accumulation in recycled WESP water, which could otherwise hinder the removal of CPM. The total mass and chemical speciation were determined by EPA method 202. The total mass of CPM was removed by 25.7–60.6% after the TCD. The CPM captured by CPM filters (CPMspa) was down to around 15–21% and the FPM also was reduced by around 11–26%. The occurrence of vapor gradient forces and thermophoresis forces could enhance the contact between CPM and water film, which was built up on the surface of the cooling tubes during the process of TCD. Then, part of the CPM was removed with a water film. The low capital and operating cost of TCD can be installed in the industrial heating plant or be set up after the WESP in the coal-fired power plant to enhance the CPM removal efficiency.

Study of condensable particulate matter from stationary combustion sources: Source profiles, emissions, and impact on ambient fine particulate matter

Although significant progress has been made in controlling emissions from stationary combustion sources in China over the past decade, understanding of condensable particulate matter (CPM) emissions from these sources and their impact on ambient PM2.5 remains limited. In this study, we established the source profiles and emission inventories of CPM from coal-fired industrial boilers (CFIBs), coal-fired power plants (CFPPs), and iron and steel industry (ISIs) for the Yangtze River Delta (YRD) region of China; furthermore, the air quality model (Community Multiscale Air Quality, CMAQ) was used to evaluate the impact of CPM emissions from these three types of stationary combustion sources on ambient PM2.5 during Feb. 2018, a month characterized by elevated PM2.5 concentrations. The results indicated that CPM emissions from these three sources in the YRD region before and after the implementation of the ultra-low emissions (ULE) policy amounted to 109,839 and 43,338 tons, respectively, with particularly high emission intensity along the Yangtze River. The implementation of CFPPs ULE policy was shown to reduce the impact of CPM emissions from these three stationary sources on monthly PM2.5 concentrations from 0.92 μg/m3 to 0.41 μg/m3 (with a maximum of 5.35 μg/m3). This reduction exceeded the 0.31 μg/m3 decrease in PM2.5 concentrations resulting from the emission reductions of conventional pollutants (FPM, SO2 and NOx). CPM emissions from these three stationary sources were found to increase the PM2.5 by 0.68 μg/m3 during pollution periods. The largest components of PM2.5 contributed by CPM emissions from stationary combustion sources were sulfate, organic carbon, and nitrate, accounting for 21.4 %, 21.1 %, and 18.2 %, respectively. Particularly, contributions from CPM emissions to PM2.5 varied by altitude, with a relatively large impact at altitudes between 220 and 460 m. Attention should be given to CPM emission control, with particular priority placed on implementing ULE measures for ISIs and CFIBs.

A pilot study on a 30 t/h biomass gasification-combustion plant

As a renewable energy with zero carbon emission, the utilization of biomass has attracted widely studied. One of the most effective methods is to gasify the biomass into high-quality gas fuel. In the recent years, the majority of research on biomass gasification is conducted in the laboratory. However, it lacks the research in engineering application scale. In this work, a biomass gasification-combustion plant was designed and built to provide the industrial steam with a rate of 30 t/h for a food industrial park. The agricultural and forestry waste biomass was gasified in a gasifier, and then the product gas combusted in a boiler to supply the steam. The characteristics of the product gas from the gasifier were studied. The corrosion and pollutants in the combustion process were investigated. In the gasification process, the main components of the product gas are CO, H2 and CH4. CO and H2 account for 29.55 vol%-30.56 vol% and 11.65 vol%-15.35 vol%, respectively. The calorific value of the product gas is 5.88–6.29 MJ/m3. The tar concentration is 110.58–155.07 g/Nm3. At the outlet of the boiler, the concentration of the filterable particulate matter is 300.25 mg/Nm3, and the particle size is concentrated at 1.00–2.50 μm. The concentration of the condensable particulate matter (CPM) is 157.14 mg/Nm3, and the proportion of water-soluble ions in CPM is 86.36 wt%. The concentration of Cl−, SO42-, NH4+ and Na+ in CPM is relatively high, with the values of 28.83 mg/Nm3, 10.29 mg/Nm3, 7.46 mg/Nm3, and 5.06 mg/Nm3, respectively. During the half-year running, the ash deposition and corrosion were detected in the boiler heating surface and the economizer. The ash deposit in the boiler is mainly composed of the sulfate and silicate, such as CaSO4, Zn2SO4, Na2SO4 and K3Na(SO4)2. The ash deposit in the economizer is primarily composed of the sulfate and a small amount of alkali metal chloride. The flue gas reaches the emission requirement after passing through the pollution control devices and can be discharged into the atmosphere.

Condensable and filterable particulate matter emitted from typical diesel vehicles in steady and transient driving conditions

Condensable particulate matter (CPM) and filterable particulate matter (FPM) emitted from industrial sources have been well studied, but their emissions from vehicles have not yet been covered. This study explores the emission characteristics of CPM and FPM from typical diesel vehicles under various driving conditions. The emission factors (EFs) of CPMs under driving conditions were 5.4–10.4 times higher than those of FPMs, while CPMs EFs under transient driving conditions were about 2.5 times higher than those under steady driving conditions. CPM and FPM are mainly composed of organic matter accounting for 53.3 %−92.9 %, while the intermediate and semi-volatile organic compounds dominate the organic matter accounting for 86.3 %−98.6 %. Similar to industrial sources, alkanes are the predominant organic species emitted by diesel vehicles, comprising 42.0 %−64.0 % of the detected organic components. Inorganic CPM is primarily composed of NH4+ , representing 84.9 %−87.6 % of the total, in contrast to industrial sources where SO42- and Cl- dominate. Interestingly, the air pollution control devices installed on diesel vehicles under steady driving conditions perform better in removing organic CPM and producing higher inorganic CPM emissions than those under transient driving conditions. These findings will enhance the comprehensive understanding of particulate matter emitted from diesel vehicles and provide a scientific foundation for the development of related control technologies.

Study on the phase transformation mechanism and influencing factors of inorganic condensable particulate matter from coal-fired power plants

In this study, the concentration of inorganic ions (SO42−, NH4+, NO3− and NO2−) and morphological characteristics of condensable particulate matter (CPM) were investigated to elucidate the formation mechanism of inorganic CPM from ultra-low emission coal-fired power plants. The concentration of inorganic ions increased with the increase of H2O content and concentration of inorganic gaseous contaminants (SO2, NOX and NH3), and decrease of condensation temperature, indicating the enhancement of heterogenous reaction in the saturated flue gas. Furthermore, NOX and SO2 could undergo redox reactions, leading to an elevation in the concentration of SO42− and NO3−. Additionally, the introduction of NH3 resulted in increased concentrations of SO42−, NO3−, and NO2−, highlighting the significant role of NH3 neutralization in CPM nucleation. The condensation of SO3/sulfuric acid aerosols was enhanced under saturation conditions, and SO2 and SO3/sulfuric acid aerosols could contribute synergistically to the formation of SO42−. Moreover, morphological analysis revealed the presence of both well-aggregated solid CPM and dispersed liquid CPM, confirming the formation of inorganic CPM during fast condensation. Furthermore, the detected CPM were composed of S and O, which identified the significant role of sulfates in the inorganic CPM. These findings provide valuable insights for the control of inorganic CPM in flue gas systems.

An assessment of inorganic components in condensable particulate matter as a function of surface aggregation, spatial suspension state and particle size

Experimental studies assessed the removal efficiency and fine-size distribution of CPM coupled with compositional analysis across air pollution control device systems (APCDs) at an ultra-low emission (ULE) power plant. The findings indicated total CPM emissions were reduced to a minimum of 0.418 mg/m3 at the Wet Electrostatic Precipitator (WESP). The Wet Flue Gas Desulfurization (WFGD) showed the highest removal efficiency (98%) across all particle sizes, notably in the ultra-micron range. Selective Catalytic Reduction (SCR) demonstrated a mere 34% overall efficiency, with a negative removal rate in the ultra-fine particle range. The WESP effectively removed CPM only in sub-micron and ultra-micron sizes, but significantly increased water-soluble ions formation in ultra-fine spatially suspended CPM (CPMspa), leading to overall negative efficiency. Thus, the removal efficiency of the ultra-fine particle range was most affected among the three particle size ranges when the flue gas went through the APCDs. Major metal elements and water-soluble ions were more readily removed by APCDs due to their surface aggregation, while the removal of trace elements like Hg and Se was limited. Reducing SO42-/NH4+ formation in SCR, and optimizing WESP spray system operations based on flue gas components are essential steps in controlling CPM concentration in ULE power plants.

Potential Strategy to Control the Organic Components of Condensable Particulate Matter: A Critical Review.

More and more attention has been paid to condensable particulate matter (CPM) since its emissions have surpassed that of filterable particulate matter (FPM) with the large-scale application of ultralow-emission reform. CPM is a gaseous material in the flue stack but instantly turns into particles after leaving the stack. It is composed of inorganic and organic components. Organic components are an important part of CPM, and they are an irritant, teratogenic, and carcinogenic, which triggers photochemical smog, urban haze, and acid deposition. CPM organic components can aggravate air pollution and climate change; therefore, consideration should be given to them. Based on existing methods for removing atmospheric organic pollutants and combined with the characteristics of CPM organic components, we provide a critical overview from the aspects of (i) fundamental cognition of CPM, (ii) common methods to control CPM organic components, and (iii) catalytic oxidation of CPM organic components. As one of the most encouraging methods, catalytic oxidation is discussed in detail, especially in combination with selective catalytic reduction (SCR) technology, to meet the growing demands for multipollutant control (MPC). We believe that this review is inspiring for a fuller understanding and deeper exploration of promising approaches to control CPM organic components.

Composition, characteristics, and treatment technologies of condensable particulate matter present in flue gas emitted by coking plants in China

To study the total particulate matter (TPM) in flue gas emitted by coking plants, a sampling system that could be used to collect filterable particulate matter (FPM) and condensable particulate matter (CPM) was designed and developed based on Method 202 recommended by the U.S. Environmental Protection Agency in 2017 and HJ 836-2017 issued by China. Using this system, FPM and CPM in flue gas emitted by four coking furnaces named A, B, C, and D were tested in China. Further, 9 water-soluble ions, 20 elements, and organic matter present in the CPM were simultaneously examined to determine their formation mechanisms. Statistical data suggested that the FPM emission level in the coking flue gas was low and the average mass concentration was less than 10 mg/m3. However, with high CPM and TPM emission levels, the TPM mass concentrations of A, B, C, and D were 130 ± 11.1, 84.4 ± 6.36, 35.1 ± 17.0, and 63.8 ± 13.0 mg/m3, respectively. The main component of TPM was CPM, and the average mass concentration of CPM accounted for 98%, 95%, 68%, and 95% of TPM in furnaces A, B, C, and D, respectively. Water-soluble ions were the important components of CPM, and the total concentration of water-soluble ions accounted for 70%, 87%, 42%, and 66% of CPM in furnaces A, B, C, and D, respectively. Toxic and harmful heavy metals, such as Mn, Cr, Ni, Cu, Zn, As, Cd, and Pb, were detected in CPM. The formation mechanism of CPM was analyzed in combination with flue-gas treatment. It was shown that the treatment process “activated carbon– flue-gas countercurrent-integrated purification technology + ammonia spraying” used in furnaces A and B was less effective in removing CPM, water-soluble ions, metals, and compounds than that of “selective catalytic reduction denitrification + limestone–gypsum wet desulfurization (spraying NaOH solution)” in furnaces C and D. Hence, different flue-gas treatment technologies and operation levels played vital roles in the formation, transformation, and removal of CPM from flue-gas. Organic components in CPM discharged from furnace A were determined via gas chromatography–mass spectrometry, and the top 15 organic components in CPM were obtained using the area normalization method. N-alkanes accounted for the highest proportion, followed by esters and phenols, and most of them were toxic and harmful to humans and ecosystems. Therefore, advanced CPM treatment technologies should be developed to reduce atmospheric PM2.5 and its precursors to improve ambient air quality in China.

Emission characteristics of condensable particulate matter during the production of solid waste-based sulfoaluminate cement: Compositions, heavy metals, and preparation impacts

Recycling solid waste for preparing sulfoaluminate cementitious materials (SACM) represents a promising approach for low-carbon development. There are drastic physical-chemical reactions during SACM calcination. However, there is a lack of research on the flue gas pollutants emissions from this process. Condensable particulate matter (CPM) has been found to constitute the majority of the primary PM emitted from various fuel combustion. In this study, the emission characteristics of CPM during the calcination of SACM were determined using tests in both a real-operated kiln and laboratory experiments. The mass concentration of CPM reached 96.6 mg/Nm3 and occupied 87% of total PM emission from the SACM kiln. Additionally, the mass proportion of SO42− in the CPM reached 93.8%, thus indicating that large quantities of sulfuric acid mist or SO3 were emitted. CaSO4 was one key component for the formation of main mineral ye'elimite (3CaO·3Al2O3·CaSO4), and its decomposition probably led to the high SO42− emission. Furthermore, the use of CaSO4 as a calcium source led to SO42− emission factor much higher than conventional calcium sources. Higher calcination temperature and more residence time also increased SO42− emission. The most abundant heavy metal in kiln flue gas and CPM was Zn. However, the total condensation ratio of heavy metals detected was only 40.5%. CPM particles with diameters below 2.5 μm and 4–20 μm were both clearly observed, and components such as Na2SO4 and NaCl were conformed. This work contributes to the understanding of CPM emissions and the establishment of pollutant reduction strategies for waste collaborative disposal in cement industry.

Migration and distribution characteristics of typical organic pollutants in condensable particulate matter of coal-fired flue gas and by-products of wet flue gas desulfurization system.

The wet flue gas desulfurization (WFGD) system of coal-fired power plants shows a good removal effect on condensable particulate matter (CPM), reducing the dust removal pressure for the downstream flue gas purification devices. In this work, the removal effect of a WFGD system on CPM and its organic pollutants from a coal-fired power plant was studied. By analyzing the organic components of the by-products emitted from the desulfurization tower, the migration characteristics of organic pollutants in gas, liquid, and solid phases, as well as the impact of desulfurization towers on organic pollutants in CPM, were discussed. Results show that more CPM in the flue gas was generated by coal-fired units at ultra-low load, and the WFGD system had a removal efficiency nearly 8% higher than that at full load. The WFGD system had significant removal effect on two typical esters, especially phthalate esters (PAEs), with the highest removal efficiency of 49.56%. In addition, the WFGD system was better at removing these two esters when the unit was operating at full load. However, it had a negative effect on n-alkanes, which increased the concentration of n-alkanes by 8.91 to 19.72%. Furthermore, it is concluded that the concentration distribution of the same type of organic pollutants in desulfurization wastewater was similar to that in desulfurization slurry, but quite different from that in coal-fired flue gas. The exchange of three organic pollutants between flue gas and desulfurization slurry was not significant, while the concentration distribution of organic matters in gypsum was affected by coal-fired flue gas.

The effect of multiple factors on changes in organic-inorganic fractions of condensable particulate matter during coal combustion

Condensable particulate matter (CPM) from coal combustion is the focus of current pollutant emission studies, and CPM can be divided into inorganic and organic fractions according to the component characteristics. At present, the effects of different factors in the combustion process on the organic and inorganic components of CPM have not been discussed systematically. Here, we conducted combustion experiments collected the generated CPM on a well-controlled drip tube furnace, and investigated the effects of different factors on the generation of organic and inorganic components of CPM by varying the furnace wall insulation temperature, the ratio of gas supply components and the water vapor content in the flue gas. The results showed that the increase in combustion temperature (1300–1500 °C) and oxygen concentration (15–25%) reduced the total CPM generation by 9.8% and 19.98%, respectively, and the intervention of water vapor increased the ability of the whole CPM sampling device to capture ultrafine condensable particles. The generation of CPM organic components decreased with the enhancement of combustion temperature and oxygen content on combustion characteristics, and alkanes shifted to low carbon content. The amount of CPM inorganic components increased with the increase of water vapor content in the flue gas, and this change was dominated by SO42−. The above results provide a feasible idea for the next step of the precise reduction of CPM components.

The Behavior and Removal of Condensable Particulate Matter in Flue Gas in a Multi-Field Force: A Modeling and Experimental Study

Condensable particulate matter (CPM) is different from filterable particulate matter (FPM), which could escape from air pollution control devices (APCDs) and pose a great threat to the environment and human health. Thus, modeling and experimental studies were conducted on CPM particle behavior and removal, in a cold electrode electrostatic precipitator (CE−ESP) coupled with a electric field, temperature field and concentration field. A multi−field force coupling model was then established that was based on the mechanical behavior of particles inside the CE−ESP. The results showed that temperature field was beneficial to depositing small size particles and that, the greater the temperature gradient, the higher CPM’s removal efficiency. While the electric field tended to gather larger size particles, the greater the voltage provided, the higher the removal efficiency for CPM and FPM. In the multi−field, the augmented coagulation and the removal efficiencies of both CPM and FPM increased significantly, reaching 89% and 98%, respectively. Subsequently, experiments were conducted by a self−made CE−ESP device, which showed the removal efficiencies of CE−ESP of a CPM in a multi−field were 91% and 81% for a coal−fired power plant and a waste incineration plant, respectively. This research could make a great contribution to CPM condensation, aggregation and removal.

Emission characteristics and removal of heavy metals in flue gas: a case study in waste incineration and coal-fired power plants.

Heavy metal pollutants such as Hg, As, Pb, Cr, and Cd emitted from coal and waste combustion have received widespread attention. In this study, we systematically investigated the emission characteristics of heavy metals in waste incineration and coal-fired flue gases, focused on testing the removal effect of self-made cold electrode electrostatic precipitator (CE-ESP) on heavy metals in flue gas, and made a comparative analysis with the existing air pollution control devices (APCDs). Test results from waste incineration power plant showed that each APCD showed a certain effect on the removal of heavy metals in condensable particulate matter (CPM), with an average removal efficiency of bag filter was 86%, but its effect on Hg removal was slightly worse. Under the coupled field with electrified cold electrode plate operation mode, the average removal efficiency of CE-ESP on heavy metals in CPM was as high as 93%, including 76% for Hg. The removal efficiency of heavy metals (especially Hg) in CPM increased with the increase of flue gas temperature difference between inlet and outlet of CE-ESP. Test results from this coal-fired power plant showed that heavy metals were enriched in fly ash to a higher degree than in slag, the synergistic control of heavy metals in submicron particulate matter by the dust remover was not obvious, and there was a significant correlation between each heavy metal emission factor and its content in coal. Under the temperature field with non-electric cold electrode plate operation mode, the overall effect of CE-ESP on the removal of gaseous heavy metals was better than that of particulate heavy metals. Under the conventional electric field operation mode, CE-ESP was less effective in removing particulate Cr and gaseous Hg0. Under the coupled field with electrified cold electrode plate operation mode, the average removal efficiencies of CE-ESP for particulate and gaseous heavy metals were 82.37% and 76.16%, respectively.

Removal of multiple pollutants in air pollution control devices of a coal-fired boiler installed with a flue gas condensation scrubber

This work was conducted through field tests on a coal-fired circulating fluidized bed boiler with a condensation scrubber (CS) for flue gas waste heat recovery installed behind the wet flue gas desulfurization (WFGD) scrubber. Levels of multiple pollutants were investigated along various flue gas devices of the boiler, with the CS being the main focus. The CS demonstrated an excellent effect in removing filterable particulate matter (FPM), reducing it from 10.63–14.00 mg/Nm3 to less than 1 mg/Nm3, providing an alternative solution for ultra-low emission. The CS had the ability to remove SO2, reducing it from 211.8–272.0 mg/Nm3 to 11.1–13.0 mg/Nm3, which could be an aid to the WFGD scrubber. The CS showed an effect on SO3 removal, reducing it from 17.49–17.53 mg/Nm3 to 1.07–1.13 mg/Nm3, which might address the discharge of sulphate aerosols. The CS exhibited an effect in removing condensable particulate matter (CPM), reducing it from 29.68–38.48 mg/Nm3 to 12.18–22.80 mg/Nm3, providing a potential solution for CPM emission control. In addition, the escape of fine desulfurization slurry droplets from the WFGD scrubber could also be mitigated by the CS with the reduction efficiency of 88.30–90.51%. Overall, the synergistic removal of multiple pollutants including FPM, SO2, SO3, and CPM by the CS was verified in this case study. Considering its original function of waste heat recovery, the adoption of the CS is a promising measure for energy conservation and environmental protection.

Exploration on the source of NH4+ in condensable particulate matter

Condensed particulate matter (CPM) is a type of pollutant that has attracted much attention due to its small emission size and complex composition. CPM consists of both inorganic and organic components, and exploring their sources is beneficial for understanding the emission characteristic and the control strategy of CPM. Among the inorganic components, NH4+ is one of the dominant cations contained in previous work's CPM samples, whose sources are still unclear. In this work, experiments were performed in two scales to investigate the potential sources of NH4+ contained in the CPM samples, one was based on a simulated flue gas experimental system, and the other was based on a real flue gas one. In both cases, ammonium-containing substances, gases or solutions with known concentrations, were intentionally added into the flue gas, and the changes of NH4+ and other concerned components in the CPM samples collected from the flue gas were compared to judge the source of it. The results showed that NH3 in the flue gas was the dominant source of NH4+ in the CPM samples. The presence of NH3, SO2, chlorine containing substances, ammonium sulfate and ammonium sulfite in the flue gas can affect the contents of both NH4+ and SO42− in the CPM samples.

Unrecognized pollution by inorganic condensable particulate matter in the atmosphere

Unrecognized pollution by inorganic condensable particulate matter in the atmosphere

Formation and migration of soluble ions in condensable particulate matter in limestone-gypsum wet flue gas desulfurization system

In this work, the emission characteristics of condensable particulate matter (CPM) and soluble ions in the inorganic components after wet flue gas desulfurization (WFGD) were investigated by adjusting the operating parameters of the limestone-gypsum WFGD system. Using a combination of US Method 202 and US EPA Method 5 as the primary measurement method, the study is an experimental study and analysis of the properties of CPM emitted from a limestone-gypsum WFGD system. Based on the measurement results, the influence of some important WFGD operating parameters on CPM emissions was evaluated. The results showed that CPM accounts for 84% of total particulate matter (TPM) emissions in desulfurized flue gas. The composition of CPM is primarily inorganic, comprising 96% of the components, with only a small portion being organic at 4%. The CPM that condensed to a solid state was generally less than 1 μm in diameter and mostly came from WFGD process. The analysis of soluble ions showed that Ca2+ and SO42- were the main ionic components in CPM. By adjusting the desulfurization operating parameters (inlet flue gas temperature, desulfurization solution temperature, desulfurization solution concentration), the concentration of soluble ions can be reduced to different degrees, so as to achieve the purpose of reducing CPM emission. This demonstrated that the CPM emission problem of limestone-gypsum WFGD system could be relieved by operating parameter optimization.

Polycyclic aromatic hydrocarbons and normal alkanes in condensable particulate matter of coal combustion

Currently, there is relatively limited research on the organic components of condensable particulate matter (CPMo). This work quantitatively investigated two typical CPMo: high-toxic polycyclic aromatic hydrocarbons (PAHs) and high-content normal alkanes (n-alkanes). The effects of oxygen content (OC) and exhaust temperature (ET) on their emission concentrations were explored. The results showed that the percentage of CPMo in this work were relatively large, averaging 81.22% in different operating conditions. CPMo were greatly affected by the OC. Under different OC and ET conditions, PAHs in CPMo were mainly concentrated in 4- and 5-ring, with a relatively small proportion in others. The minimum amount of PAHs was generated under the high OC and the low ET condition. After analyzing the toxic equivalent quantity (TEQ), it was found that 5-ring PAHs were the largest contributors to TEQ, followed by 4- and 6-ring PAHs. PAHs with higher concentrations do not necessarily have higher toxicity. In addition, the emission concentration of n-alkanes showed a unimodal distribution under different conditions, with the highest concentration of n-alkanes between C22 and C32. The concentration of n-alkanes gradually increased as the ET decreased and the OC increased.

Effect of ammonia co-firing ratio on the formation of condensable particulate matter in pollutants during coal/ammonia co-combustion

In this paper, the influence of zero-carbon ammonia co-firing ratio during coal/ammonia combustion on the generation of condensable particulate matter(CPM) was investigated. 0%, 10%, 20%, 30% and 50% ammonia were mixed into the coal combustion according to the energy input ratio to collect the discharged CPM and FPM in laboratory and the composition of flue gas was tested. The results show that mixing ammonia into coal combustion had little impact on the total concentration of CPM. The main reason is that the ammonia co-firing into coal can promote the formation of inorganic matter of CPM, and the concentration of organic matter decreased. The mass of FPM decreased when the proportion of ammonia is increased. In addition, co-combustion of ammonia inhibited the formation of SO2 that discharge to the atmosphere. The main reason is that the mass of coal decreased with the increasing of calorific value of ammonia. In addition, the co-firing of ammonia can promote the conversion of S to FPM and CPM. The reason is that H came from NH3 burned to produce water vapor, then water vapor can combine with sulfur dioxide. Peak areas of some organic substances are drawn with the variety of ammonia co-firing ratio. Most of the substances in alkanes are N-alkanes. The conclusions in this paper are of great significance to the further understanding of migration and transformation of pollutants under the influence of ammonia co-combustion. In addition, the research in this paper provides a theoretical basis for achieving the goal of carbon neutrality.

Improvement of the reduction of condensable particulate matter in flue gas scrubbing process

Condensable particulate matter (CPM) is characterized by complex composition, non-negligible emission concentration, and fine or ultrafine in size after conversion to particles, which is difficult to remove. Current methods to control CPM are not fully developed and mainly focus on synergistic removal of CPM in existing air pollution control devices, such as CPM reduction through scrubbing processes in wet flue gas desulfurization (WFGD) systems. In this work, an experimental system including a simulated WFGD scrubber, also referred to as the primary scrubber (PS), and a secondary scrubber (SS) was built to explore measures to improve the CPM reduction performance during scrubbing. The operating parameters of the liquid-to-gas (L/G) ratio and the spray temperature in the two scrubbers were tuned in the experiments. The results indicated that CPM could be reduced in the PS by conversion to filterable particulate matter (FPM), and captured by the spray droplets through the effects of dissolution and condensation, but the reduction was not very efficient. In the SS, the reduction performance of CPM could be further improved due to increased dissolution of CPM caused by increased opportunities for gas-liquid contact, and increased condensation of CPM due to lower spray temperature. The FPM transformed from the CPM in the PS could also be reduced in the SS by the effects of diffusiophoresis and thermophoresis contributed by water vapor condensation. An increase in the L/G ratio could improve the CPM reduction.