wei-ping Pan

North China Electric Power University | NCEPU · Institute for energy power and mechanical

The properties of fly ash in coal-fired boilers influence the emission of mercury from power plants into the environment. In this study, seven different bitumous coals were burned in a full-scale 100 MWe pulverized coal combustion boiler and the derived fly ash samples were collected from a mechanical hopper (MH) and an electrostatic precipitator h...

Six mercury continuous emission monitoring (CEM) systems provided by two leading mercury (Hg) CEM system manufacturers were tested at five coal combustion utilities. The linearity, response time, day-today stability, efficiency of the Hg speciation modules, and ease of use were evaluated by following procedures specified in the Code of Federal Regu...

Zeolite-templated carbon (ZTC), a three dimensional ordered carbon material, was synthesized by chemical vapor deposition for use as an efficient adsorbent for the removal of volatile organic compounds (VOCs). A series of ZTC samples with different deposition temperatures and deposition times were evaluated, and the effect of O2, SO2, and H2O on VO...

Traditional activated carbon used to remove elemental mercury (Hg⁰) from coal-fired power plants exhibit an irregular porous structure, showing an adverse effect on the removal of Hg⁰. To obtain carbon materials with a regular porous structure, zeolite-templated carbon samples (ZTC and S-doped ZTC) with a three-dimensional ordered structure were sy...

The combustion and fragmentation characteristics of wet coal slime particle are different from that of dried coal particle. In this paper, an understanding of the combustion process of wet coal slime particle through the combined results of the morphology characteristics, mass changes, and gas release pattern is provided. A tube furnace and high-sp...

Coal fly ash (CFA) has been considered an important alternative resource for rare earth elements (REEs) and other critical metals such as Ge, Ga, U, etc. Concerns regarding the migration and transformation of harmful trace elements (HTEs: Hg, As, Se, Pb, Cd, Cr) from CFA to the environment are of great significance for the technical design of the r...

Coal ash has emerged as an important alternative source for rare earth elements (REEs). The enrichment and occurrence form of REEs among coal combustion products are of great significance for both technical design and economic evaluation of recovering REEs from the coal ash. Here, the enrichment and occurrence form of REEs in the ash were investiga...

Elemental mercury is harmful to humanity and the ecological environment. It is a simple and feasible method to capture elemental mercury by carbon-based adsorbents. The purpose of this work is to develop zeolite-templated carbon with and without sulfur (ZTC and S-doped ZTC) and to explore their mercury adsorption performance. ZTC and S-doped ZTC we...

This work reports a procedure for increasing VOC removal from flue gas using binary oxides (Ce-Mn) supported on fly ash by facile mechanochemical synthetic method in the presence of a solid organic acid ligand (OAL). The presence of OAL during the synthesis process helped produce larger and more accessible particle surface areas, by generating an a...

A simple synthesis of thiophene-functional zeolite-templated carbons (ZTCs) is proposed to remove ionic mercury (Hg²⁺) and organic mercury (Hgorg) from gasoline. Microporous zeolite (Beta) and mesoporous zeolite (MCM-41) were used to prepare porous carbon by impregnating with 2-thiophenemethanol (ThM) to explore the influence of template type on th...

3D hierarchical porous biochar (HPBC) was synthesized by a thermally removable template without post-activation. Zn(NO3)2 decomposition produced gases and ZnO in situ to activate and expand the three-dimensional micro-and mesopores. Compared with pristine biochar (BC), the specific surface area and pore volume of HPBC were increased by 223 and 75 t...

Silver nanoparticles (AgNPs) have attracted considerable attention as promising industrial adsorbents of gaseous mercury. The underlying mechanism of immobilization of Hg⁰ on different AgNP surfaces was investigated in theoretical and experimental approaches. The crystallographic properties of AgNPs obtained by X-ray diffraction and selected area e...

Zeolite-templated carbon (ZTC) can be prepared by chemical vapor deposition (CVD), which involves the coupled mass transport and chemical reaction of carbon precursors. Combining theoretical and experimental approaches, this work demonstrated that reducing the particle size of the template enhanced both the inward and outward mass transport during...

Sulphur-doped, β-zeolite-templated carbons (S-β-ZTCs) were synthesized by chemical vapor co-deposition of hydrogen sulfide (H2S) and acetylene (C2H2) to remove ionic (Hg²⁺) and organic mercury (Hgorg) from gasoline. In situ doping of sulphur introduced aromatic thiols and thiophenes into the ZTC's framework that removed the mercury by forming Hg–S...

One-step pyrolysis of biomass/zinc salts composites was investigated to clarify the effects of zinc salts on the pore structure of biochar and its performance for removing heavy metals from wastewater. The characterization results indicated that zinc salts not only promoted the pyrolysis of biomass but also decomposed to generate volatile gas and t...

The interaction of gaseous elemental mercury with the sorbent surface is generally related to the adsorption temperature. Our adsorption–desorption experiments at various temperatures have proved that the adsorption temperature has a direct impact on the location of the desorption peak. By studying the desorption activation energy (Ed) of Hg⁰ on co...

The wet flue gas desulfurization of sludge samples used in the study were taken from four different coal-fired power plants. The total amounts and speciation of 10 trace elements in the sludge were determined. Studies showed that the content of Hg (1.53–11.4 μg/g) and Cd (0.39–0.81 μg/g) in sludge were relatively low, while those of other trace ele...

In this work, the modification of fly ash with mechanochemical coupled MnO2 was presented by balling milling to enhance its activity for volatile organic compounds (VOCs) oxidation. This simple processing significantly improved the toluene conversion, from 5% (untreated fly ash) to over 90% with the carbon balance efficiency over 94%. Microscopic c...

This study examines the impact of adding a mercury removal system which uses modified fly ash on particulate matter (PM) emissions from a coal-fired power plant. The modified fly ash injection technology has been demonstrated and was installed in a commercial power plant and reached 91.9% mercury removal efficiency. An important consideration was t...

The process of synthesizing a zeolite/carbon composite (ZCP) is the first chemical event for preparing a zeolite-templated carbon (ZTC) via the chemical vapor deposition (CVD) process. The purpose of this work was to investigate the effect of CVD time duration (up to 446 min) at 600 °C and then heat treatment at 800 °C on the structure of the pyrol...

A novel N-doped porous carbon (NC) adsorbent with uniformly distributed Cobalt nanoparticles (Co/NC) for vapor elemental mercury removal was synthesized by direct pyrolysis of zeolitic imidazolate framework 67 (ZIF-67). Doped N atoms and uniformly distributed cobalt nanoparticles in the carbon framework of Co/NC provided both physisorption and chem...

Primary particles emitted from fuel combustion mainly involve filterable particulate matter (FPM) and condensable particulate matter (CPM). Particularly, CPM has emerged as a subject for further emission control. This study investigated the effects of the sampling temperature and excess air coefficient (EAC) on the total mass, chemical speciation,...

The combustion and emissions characteristics of wheat, rice, millet, and tobacco straw are thermally evaluated to overcome the challenges related to their usage in heating plants. Wheat straw exhibits the highest volatile matter, fixed carbon content, and heating value (18.0 MJ/kg). The burning processes of biomass are divided into the vaporisation...

Particle-bound mercury discharged with fine particulate matter from coal-fired power plants causes atmospheric pollution that impacts human health. In this study, the speciation and size-specific distribution of particle-bound mercury in filterable particulate matter (FPM) from an ultra-low emission power plant and condensable particulate matter (C...

Due to its low cost, rich resource reserve, and high affinity for gas-phase mercury, zinc selenide has been investigated as a promising sorbent to control mercury emission. In order to gain molecular level insights into the adsorption mechanism, density functional theory (DFT) calculations were applied to the process of mercury adsorption on the (1...

As an inorganic phase change material (PCM), CaCl2·6H2O is an effective energy storage material because its energy can be transformed around 30 °C through the melting and crystallization. The different compositions of PCM were prepared in order to decrease the phase transition temperature to 20–25 °C and to improve its capability of heat storage an...

Mercury (Hg) removal from natural gas condensates is a hot topic due to its importance in petroleum refineries. Unfortunately, though much attention has been paid to the adsorption efficiency of sorbents in industry, mercury adsorption mechanisms are rarely addressed. This paper studies the adsorption mechanisms of zeolite 13X impregnated with pota...

Distribution of rare earth elements (REEs) in six speciations extracted from coal and coal gangue and their combustion products (slag and fly ash) generated by three different power plants in China were determined by sequential extraction procedure combined with inductively coupled plasma mass spectrometry method. The results show that the REEs mai...

In the power plants, the particle size of fly ash was gradually decreased from the front row to the last row of the hopper. The high mercury captured rate was shown with the high unburned carbon content in the front row of the hopper. 80% of mercury captured in the front hopper was in the residual fraction and the rest was in the oxidizable fractio...

Three kinds of biochar, tobacco, rice and wheat, were treated with H2S to remove Hg(II) from hydrocarbons. The removal efficiency of the three biochars without H2S treatment was less than 12%. The removal efficiency of H2S treated tobacco had the best performance, and the removal efficiency increased by more than 87%. The characteristics of H2S tre...

Mercury is harmful to the human body and to the ecological environment. Mercury emission from coal-fired power plants is one of the main sources of anthropogenic mercury emissions. Adsorbents and catalysts are popular materials developed to capture mercury from flue gas. Sulphur oxides (SO2, SO3) are the main components of flue gas; their concentra...

Biochar was subjected to N2-plasma treatment after adsorbing water or oxygen. The mercury removal efficiency of the obtained samples was tested. The results of H2O-thermogravimetric and O2-temperature programmed desorption show that biochar had adsorption capacity for both water and oxygen during storage. The adsorbed water exhibited an inhibitory...

The purpose of this research was to improve the sorption ability of Pb and Cd by promoting the ion exchange and precipitation capacity of biochar. The adsorption performance and mechanisms of Pb and Cd in wastewater using coconut shell biochar modified with magnesium were investigated. After modification, the total adsorption capacity (Qt) of Pb an...

The performance of a supercapacitor (SCs) fabricated from coal-based activated carbon was studied in terms of its specific capacitance (C), life cycle and rate performance. In this work, a low cost modified nitrogen-doped coal-based activated carbon (MACN) was prepared by KOH/H2O co-activation from lignite. Experimental results and density function...

The current drawback in supercapacitor (SCs) performance is mainly due to their low energy density. Increased specific capacitance (C) is not only related to the specific surface area (SBET) but also to the inner surface of the micropores that are wetted by electrolyte. In this paper, water vapor assisted trace KOH (alkali to carbon ratio of 0.02)...

Abundantly available low-grade coal is used to prepare activated carbon (AC) for supercapacitor (SCs) electrode materials. Aiming to transform low-grade coal into pore structure, microcrystalline, and surface chemistry multi-scale coordinated AC, a new ultrasound-assisted bimetallic activation strategy is proposed. The introduction of ultrasonic wa...

The Cu/ZSM-5 was used to study the effects of SO3 on mercury removal. The addition of SO2 decreased the Hg⁰ removal efficiency but the efficiency increased from 82% to 95% after 21 ppm SO3 was introduced at 200 °C. The inhibition effect of SO2 on mercury removal was weakened at 400 °C and the promotion effect of SO3 on mercury removal was enhanced...

To reduce the volatile organic compounds (VOCs) emission and to achieve an ultra-low emission in coal-fired power plant, it is essential to understand the effect of air pollution control device system (APCD) on the emission of VOCs. In this study, the mass concentration of speciated VOCs in the flue gas on the nine sampling locations from the coal-...

The co-adsorption of Hg0 and SO3 on pure and Cu/Mn doped CeO2(110) surface were investigated using the Density Functional Theory (DFT) method. A p (2×2) super-cell periodic slab model with seven atomic layers was constructed to represent the CeO2(110) surface. The results indicated that Hg0 physically adsorbed on the CeO2(110) surface, while Hg0 ch...

TiO2-BiOIO3 heterostructures were prepared to study the photocatalytic removal of elemental mercury, sulphur tolerance and SO2/SO3 conversion under UV irradiation. TiO2-BiOIO3 produced excellent photocatalytic performance with highest Hg⁰ adsorption and oxidation efficiencies of 58.5% and 36.5%. SO2 exhibited a negative effect on elemental mercury...

The mercury removal performance of chlorine plasma-modified biochar was tested under NH3 and NH3 combined with a NO/SO2 atmosphere. The addition of NH3 promotes the mercury removal process of modified biochar, and the mercury removal efficiency can be increased by up to 17.5%. NH3 can induce the conversion of chloride to C–Cl, making it easier to b...

A simple solution-based method was used to prepare high value-added, coal-based carbon films, which were prepared by spin coating a centrifugal ball-milled coal suspension. The prepared carbon films retained abundant carbon chemical properties from the raw coal and did not change the order and bonding mode of the carbon atoms. By annealing the prep...

As one of the technologies for the improvement in coal quality, biological enzyme technology has received much attention. The enzyme product named 3EC was shown to enhance the power plant performance in our previous full-scale test. In this work, its effect on coal was explored. The results indicated that the enzyme product was beneficial in the re...

The mercury removal capacity of biochar can be improved by plasma modification and the functional group is an important factor affecting the mercury removal. This paper examines factors such as discharge voltages, gas flow rates, chlorine concentrations and discharge times that may affect functional groups on the surface of biochar. The mercury rem...

After the co-combustion of tobacco stem/black bean straw/wheat straw/millet straw/corn stalk/rice straw and coal, it was found that all tested biomass in this study could inhibit arsenic release, but only rice straw promoted arsenic release. When the acid washed biomass was mixed with coal during combustion, the release of arsenic increased. When m...

Having a history of nearly 150 years, coal-fired power generation has supported the development of human civilization. Up to now, coal-based power remains as one major source of electricity, even more than 50% of the electricity is produced by coal-fired power plants in some countries. However, the enormous utilization of coal brings forth serious...

A series of Mn-Ce/SAPO-34 catalysts were prepared to study the catalytic oxidisation of elemental mercury (Hg0). Sulphur tolerance and SO3 formation over the catalyst were studied further. Hg0 was transported by compressed air from PSA Cavkit. NO, SO2, and NH3 are standard gases, and H2O is produced by gas carrying. Mn could incorporate into the ce...

Modified fly ash injection was installed at the outlet of selective catalytic reduction (SCR) systems in a 1000 MW coal-fired power plant, reaching 94% mercury capture rate. Due to chemical and mechanical treatment of raw fly ash, the modified fly ash has a higher oxidation capability, finer particle size, and more active sites. The co-benefit of t...

The adsorption mechanisms of Pb(II) and Cd(II) in aqueous solution using camellia seed husk biochars pyrolyzed at different temperatures were studied. The adsorption of Pb(II) and Cd(II) on biochars are mainly controlled by ion exchange, oxygen functional groups (OFGs) complexation, Pb(II)/Cd(II)–π interactions, and precipitation with minerals. Com...

The distributions of organic compounds such as methane, non-methane hydrocarbon (NMHC) and polyaromatic hydrocarbon (PAH) in the effluent from an ultra-low emission power plant were investigated. The methane and NMHC in the flue gas were analyzed using a modified portable volatile organic hydrocarbon analyzer according to US EPA method 25A, and a l...

OMAI: on-line modified fly ash sorbent injection Modified fly ash for mercury removal at a 1000 MW coal-fired power plant. A R T I C L E I N F O Keywords: Mercury Fly ash Bromide On-line modified Coal-fired power plant A B S T R A C T Modified fly ash is a potential competitive sorbent for flue gas mercury remove in coal-fired power plant. The adso...

In this study, the partitioning of trace elements (TEs) in an ultra-low emission coal-fired electric power plant (EPP) was investigated. TEs distribution, partitioning concentration, balance rate, and removal efficiency were evaluated. Results include determination of the TEs in flue gas, coal, fly ash, bottom ash, gypsum, limestone, makeup water,...

This work evaluated three activation methods, physical activation, chemical activation and combined physical–chemical activation, for preparing activated carbon (AC) from rock asphalt. A high carbon content and the low cost of rock asphalt makes it a good possible raw material for the preparation of activated carbon. The objective of this research...

A series of biochars were prepared from rice(RI), tobacco(TO), corn(CO), wheat(WH), millet(MI), and black bean straw(BB). These biochars were used to study the mechanism of elemental mercury(Hg⁰) adsorption by hydrochloric acid modified biochars. The biochars were modified by 1 M hydrochloric acid (HCl) and then used in a fixed-bed Hg⁰ adsorption e...

Coal-fired power plants produce flue gas desulfurization gypsum as a by-product of the sulfur removal process. This gypsum is contaminated with trace elements. Knowing the occurrence and release characteristics of trace elements from the FGD gypsum is very important if the gypsum is to be safely used in different applications. The sequential extrac...

Biochar, known as a byproduct of biomass pyrolysis, was prepared from rice straw (R6), tobacco straw (T6), corn straw (C6), wheat straw (W6), millet straw (M6), and black bean straw (B6) in high purity nitrogen at 600 °C. Chlorine (Cl) non-thermal plasma was used to increase Cl active sites on biochar to promote the mercury removal efficiency. The...

Power plant coal fly ash was modified for mercury adsorption. The fly ash was subjected to mechanochemical ball milling and bromide compounds were added. The results show that mercury capture capacity increased with increasing grinding time, up to 50 min. Grinding over 50 min did not lead to further improvements. Results from the mercury adsorption...

An arsenic emission study was performed at nine coal-fired power plants in China and the US that are equipped with various air-pollution-control devices (APCDs). On average over 90% of the arsenic in the flue gas is captured by the dry particulate matter collection system. Less than 3% of the arsenic remains in the boiler slag and 3% is captured by...

The simultaneous use of thermogravimetric (TG) analysis, Fourier-transform infrared (FTIR) spectroscopy, and gas chromatography/mass spectrometry (GC/MS) provides a new method for studying coal pyrolysis. About 124 volatile organic compounds (VOCs) were identified by TG-FTIR-GC/MS during coal pyrolysis based on the characteristic fragments or Kovat...

The oxidation of the elemental mercury (Hg⁰) by non-thermal plasma (NTP) coupled with a wet process has been studied. Effects of oxygen content, supplied voltage, gas temperature, wet process and NO/SO2 concentration on Hg⁰ oxidation were investigated using a dielectric barrier discharge reactor. Results indicate that both O and O3 generated by O2...

This research focuses on the effects of NaCl and Na2CO3 sodium additives on fine particulate emission and size distribution. The experiment was conducted in a drop tube furnace under typical power plant conditions. Particulate emissions were measured by an electrical low pressure impactor (ELPI+). NOX emissions were studied using a Testo350 flue ga...

Using waste fly ash for mercury capture applications is an attractive, low-cost option for power plants. In this paper, the influence of nitric oxide (NO) on the mercury adsorption characteristics of HBr modified fly ash in an entrained-flow reactor was investigated using continuous monitoring and thermal decomposition methods. The results show tha...

The volatilization characteristics of arsenic in different coals at 600-1500 °C were studied on an isothermal reaction system. Through thermogravimetric analysis similar to that used for coal analysis, the mass loss and mass loss rate of arsenic for coal samples were determined. Sequential chemical extraction method was used to measure the mode of...

This research studies the release of bromine species from HBr-modified fly ash and the subsequent homogeneous oxidation of gaseous elemental mercury (Hg0) by active gaseous bromine species during heating. Tests utilize an innovative bench-scale experimental system specialized for the homogeneous Hg0 oxidation reaction and confirm that the released...

Two new 2D metal–organic framework materials, [Cu(Br2BDC)2](HTEA)2 (1) and [Co2(Br2BDC)(HCOO)2(DMF)2] (2) (Br2BDC = 2,5-dibromoterephthalate, DMF =dimethylformamide, TEA = triethylamine), have been synthesized through solvothermal reactions. Compound 1 consists of anionic layered networks balanced with HTEA+ cations located between the layers. The...

More than 50% of the mercury emissions in China come from coal-fired power plants. Coal-fired power plants also consume more than 50% of the coal used in China, and this proportion is expected to increase according to Chinese energy planning agencies, despite recent actions aiming at more stringent environmental constrains. This study reports mercu...

The blending of coal with biomass can lead to synergistic combustion behaviors. The combustion profile of two biomass sources, two coals and subsequent blends was studied using thermogravimetric analysis (TG). Ignition and burnout performances were identified and calculated from thermal curves. The comprehensive combustion performance index S was c...

In order to provide better understanding of mercury sorption properties on HBr-modified fly ash, fixed bed experiments using two different bituminous coal fly ashes were designed and conducted under air-simulated flue gas atmosphere. Temperature-programmed desorption method was used to analyze the mercury speciation during the adsorption process in...

This research studies the adsorption of gas-phase As2O3 by CaO, Fe2O3 and Al2O3, using a fixed-bed reactor with an arsenic continuous generation device. The adsorption of gas-phase arsenic on CaO and Fe2O3 is mainly chemical adsorption at 600–900 °C. The adsorption quantity and efficiency decreases as the temperature increases. Iron(III) oxide has...

Ultrasound-assisted wet impregnation method was used to prepare the Fe2O3/γ-Al2O3 sorbent. The effects of the precursor solution content, carrier size, adsorption temperature and atmosphere on the arsenic capture efficiency in a fixed-bed reactor were investigated. The results show that the precursor solution concentration and the size of carrier c...

Activated carbon (AC) is an effective adsorbent that is used in a wide range of applications. This is due to its high adsorption capacity and fast removal rate. This study evaluated processing conditions for synthesizing AC from coal pitch. The objective was to establish what processing conditions produced AC with the best adsorption performance. F...

The contamination of agricultural ground with estrogen compounds through application of animal wastes is a present concern. At the same time, current uses for waste fly ash having high carbon content are limited. To help mitigate these problems, we examine using waste fly ash as a useful adsorbent for Estradiol in pig waste digests. In this study,...

The char-CO2 gasification reactions in isothermal and pressurized conditions were studied kinetically by high-pressure thermo-gravimetric analyzer, and the primary objective of this paper was to study the effects of pressure, temperature and char rank on the intrinsic reaction kinetics of the char-CO2 gasification by the Langmuir-Hinshelwood model....

In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were HgCl2, HgS and Hg...

The adsorption of gas-phase As2O3 by metal oxides like CaO, Fe2O3 and Al2O3 was investigated in a fixed bed reactor with an arsenic continuous generation facility. The results indicated that the adsorption of As2O3 on metal oxides is dominated by chemical adsorption at a temperature between 600 and 900 ℃; the adsorption quantity and efficiency are...

For gypsum slurry samples taken from wet flue gas desulfurization (WFGD) systems, a mercury partitioning effect was observed between the solid and liquid components. This partitioning effect, which appears to be pseudo-second-order, is a function of time which results in an increase in mercury content for the solid portion of the gypsum slurry as t...

Coal-fired power plants are significant contributors to the anthropogenic emission of mercury. This study focus on evaluated the methods for modification and preparation of fly ash adsorbent which can be applied to adsorb mercury from power plants. Comparing with isometric impregnation and ion exchange method, it was found that the cost and prepara...