scholarly journals Study on the Preparation and Properties of Talcum-Fly Ash Based Ceramic Membrane Supports

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 207
Author(s):  
Chao Cheng ◽  
Hongming Fu ◽  
Jun Wu ◽  
Heng Zhang ◽  
Haiping Chen
Keyword(s):  
Fly Ash ◽  
Flue Gas ◽  
Power Plants ◽  
Ceramic Membrane ◽  
Low Cost ◽  
Thermal Power ◽  
Water Flux ◽  
Ceramic Membranes ◽  
Operating Conditions ◽  
Water Recovery

Ceramic membrane method for moisture recovery from flue gas of thermal power plants is of considerable interest due to its excellent selection performance and corrosion resistance. However, manufacturing costs of commercial ceramic membranes are still relatively expensive, which promotes the development of new methods for preparing low-cost ceramic membranes. In this study, a method for the preparation of porous ceramic membrane supports is proposed. Low-cost fly ash from power plants is the main material of the membrane supports, and talcum is the additive. The fabrication process of the ceramic membrane supports is described in detail. The properties of the supports were fully characterized, including surface morphology, phase composition, pore diameter distribution, and porosity. The mechanical strength of the supports was measured. The obtained ceramic membrane supports displays a pore size of about 5 μm and porosity of 37.8%. Furthermore, the water recovery performance of the supports under different operating conditions was experimentally studied. The experimental results show that the recovered water flux varies with operating conditions. In the study, the maximum recovered water flux reaches 5.22 kg/(m2·h). The findings provide a guidance for the ceramic membrane supports application of water recovery from flue gas.

scholarly journals Study on the preparation and properties of talcum-fly ash based ceramic membrane supports

2020 ◽  
Author(s):  
Chao Cheng ◽  
Hongming Fu ◽  
Heng Zhang ◽  
Haiping Chen ◽  
Dan Gao
Keyword(s):  
Corrosion Resistance ◽  
Fly Ash ◽  
Flue Gas ◽  
Power Plants ◽  
Ceramic Membrane ◽  
Low Cost ◽  
Water Flux ◽  
Ceramic Membranes ◽  
Operating Conditions ◽  
Water Recovery

Abstract Ceramic membrane method for moisture recovery from flue gas of thermal power plants is of considerable interest due to its excellent selection performance and corrosion resistance. However, manufacturing costs of commercial ceramic membranes are still relatively expensive, which promotes the development of new methods of preparing low-cost ceramic membranes. In this study, a method for the preparation of porous ceramic membrane supports is proposed. Low-cost fly ash from power plants is the main material of the membrane supports, and talcum is the additive. The fabrication process of the ceramic membrane supports is described in detail. The properties of the supports were fully characterized, including surface morphology, phase composition, pore diameter distribution and porosity. Corrosion resistance and mechanical strength of the supports were measured. The obtained ceramic membrane support displays a pore size of about 5 µm and porosity of 37.8%. Furthermore, the water recovery performance of the supports under different operating conditions was experimentally studied. The experimental results show that, the recovered water flux varies with operating conditions. In the study, the maximum recovered water flux reaches 5.22 kg/(m2·h). The findings provide a guidance for the ceramic membrane supports application of water recovery from flue gas.

scholarly journals Enhanced Performance of Fly Ash-Based Supports for Low-Cost Ceramic Membranes with the Addition of Bauxite

Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 711
Author(s):  
Wan Fan ◽  
Dong Zou ◽  
Jingrui Xu ◽  
Xianfu Chen ◽  
Minghui Qiu ◽  
...  
Keyword(s):  
Fly Ash ◽  
High Performance ◽  
Bending Strength ◽  
Ceramic Membrane ◽  
Sintering Temperature ◽  
Low Cost ◽  
Pure Water ◽  
Ceramic Membranes ◽  
Mullite Phase ◽  
Optimum Balance

Support is a necessary foundation for ceramic membranes to achieve high performance. Finding the optimum balance between high performance and low cost is still a significant challenge in the fabrication of ceramic supports. In this study, low-cost fly ash-based ceramic supports with enhanced performance were prepared by the addition of bauxite. The pore structure, mechanical strength, and shrinkage of fly ash/bauxite supports could be tuned by optimizing the bauxite content and sintering temperature. When the sintering temperature and bauxite content were controlled at 1300 °C and 40 wt%, respectively, the obtained membrane supports exhibited a high pure water permeance of approximately 5.36 m3·m−2·h−1·bar−1 and a high bending strength of approximately 69.6 MPa. At the same time, the optimized ceramic supports presented a typical mullite phase and excellent resistance to acid and alkali. This work provides a potential route for the preparation of ceramic membrane supports with characteristics of low cost and high performance.

scholarly journals Preparation and Properties of Coal Ash Ceramic Membranes for Water and Heat Recovery from Flue Gas

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Haiping Chen ◽  
Xiangsheng Li ◽  
Jiadi Wei ◽  
Yijun Feng ◽  
Dan Gao
Keyword(s):  
Heat Transfer ◽  
Flue Gas ◽  
Heat Recovery ◽  
Ceramic Membrane ◽  
Sintering Temperature ◽  
Coal Ash ◽  
Ceramic Membranes ◽  
Transfer Performance ◽  
Water Recovery ◽  
Recovery Performance

In this paper, the manufacturing process of microceramic membrane is summarized. The main material of this membrane is fly ash which can reduce the sintering temperature and save the costs. The coal ash ceramic membrane (CACM) was characterized by XRD, SEM, and mercury intrusion method. The results show that the mullite phase formed by CACM at the sintering temperature of 1250°C has morphology and structural characteristics similar to the commercial microceramic membrane. The membrane surface is uniform and dense, without cracks; the pore diameter is 1–4 μm, and the porosity is 26.6%. Furthermore, the CACM and CMCM were compared at the aspects of water and heat recovery performance using flue gas. The experiment indicated that when the flue gas temperature was 50–85°C, the water recovery performance of these two kinds of membrane was similar. Also, the heat transfer capability of the coal ash ceramic membrane was close to that of the commercial microceramic membrane when the temperature range of flue gas was controlled between 50°C and 70°C. When the temperature of flue gas reaches 80°C, the heat transfer performance of the commercial ceramic membrane is better, and the difference of heat recovery between these two kinds of membranes is 19.3%. In general, the CACM and CMCM have similar mass transfer performance, and the heat transfer efficiency of CACM is lower than that of CMCM, but the costs of CACM is much lower than that of CMCM which has a good research prospect in the future.

scholarly journals Application of Electro kinetic technique to remediate fly ash for its sustainable use

2020 ◽  
Vol 12 (4) ◽  
pp. 682-687
Author(s):  
Shristi Choudhary ◽  
N. Srinivas
Keyword(s):  
Fly Ash ◽  
Coal Combustion ◽  
Power Plants ◽  
Low Cost ◽  
Thermal Power ◽  
Sustainable Use ◽  
Voltage Gradient ◽  
Ph Values ◽  
Cost Treatment ◽  
Remediation Process

Fly ash is a by-product of coal combustion in thermal power plants which is classified as hazardous waste and a serious threat to environment. The study was conducted to determine the potential and examine the efficacy of electro kinetic technique (EKT) using variables like pH, total dissolved solids (TDS), e concentration of chlorides (Cl-), sodium (Na+),magnesium (Mg2+), potassium (K+), ammonia (NH3+) and calcium (Ca2+) on fly ash as a low-cost treatment for enhancing the use of fly ash in a more sustainable manner. The probability of removing heavy metals and chlorides from fly ash suspended in water using electro dialysis was studied as they are highly dependent on pH and conductivity of the fly ash. The voltage gradient and duration indicated significant effect in the change of pH values showing a range from 4.6 to 7.7 at cathode and anode respectively, while the Total dissolves solids (TDS) varying from 72.33±5.6 to 146±5.4 showed the enhanced availability of ions post electro dialysis. In terms of chlorides, Cl- the content was observed to be 265.06 mg/l which was high enough to cause corrosion problems in later stages of reuse of fly ash. The concentration of cations like Na+, K+, NH3+, Mg2+, Ca2+ were observed to be notably influenced by the duration of study and pH in electro dialysis. The experimental results of the study showed that the proposed technique based on the fundamentals of electro kinetics and dialysis could efficiently improve the remediation process which would remove metals by converting them to available form in fly ash.

Numerical Simulation of Low Grade Heat and Water Recovery Using Nanoporous Transport Membrane Condensers Bundle Tubes

2015 ◽  
Author(s):  
Soheil Soleimanikutanaei ◽  
Cheng-Xian Lin ◽  
Dexin Wang
Keyword(s):  
Heat Exchanger ◽  
Flue Gas ◽  
Power Plants ◽  
Ceramic Membrane ◽  
Transport Model ◽  
Waste Heat ◽  
Numerical Study ◽  
Tube Bundle ◽  
Low Grade ◽  
Water Recovery

Low grade waste heat and water recovery using ceramic membrane, is an emerging technology which helps to increase the efficiency of boilers and gas or coal combustors in various industrial processes and conventional power plants. The tube wall of a Transport Membrane Condenser (TMC) based heat exchanger is made of a nano-porous material with high membrane selectivity which is able to extract condensate water from the flue gas in the presence of other non-condensable gases (i.e. CO2, O2 and N2). In this work, a numerical study has been carried out to investigate the effects of transversal pitches of the TMC bundle tubes on the performance of a TMC based cross flow heat exchanger. A simplified multi-species transport model is used to investigate the heat and mass transfer characteristics of a condensing combustion flue gas in a crossflow transport membrane tube bundle. Various transversal (0.4”–0.6”) and longitudinal (0.4”–0.8”) pitches were used. The numerical results revealed that the effect of transversal pitches on the outlet parameters are more pronounced.

The removal of As(V) ions by lime-modified fly ash and reuse of the exhausted adsorbent as an additive for construction material

2020 ◽  
Author(s):  
Milica Karanac ◽  
Maja Đolić ◽  
Vladimir Pavićević ◽  
Aleksandar Marinković
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Low Cost ◽  
Construction Material ◽  
Thermal Power ◽  
Construction Materials ◽  
Practical Applications ◽  
The Impact ◽  
By Products ◽  
Modified Fly Ash

<p>Coal thermal power plants (TPP) actively generate numerous solid combustion by-products, including fly ash and bottom ash. These TPP by-products have already found use in a variety of civil engineering applications, such as a substitute for sand and gravel in structures, as well as a binding component in certain types of cement (generally, concrete and masonry). Furthermore, such by-products have become a subject of increasing interest in environmental engineering as a low-cost and effective adsorbent for the removal of organic pollutants and heavy metals from wastewaters.</p><p>In order to minimize the impact of material cost, novel solutions for the development of a high capacity and long-term adsorbent have provided a high performance adsorbent for practical applications. This study is focused on the use of modified fly ash (MFA) activated by lime (Ca(OH)<sub>2</sub>) as an effective and low-cost adsorbent for the removal of As(V) ions. The adsorption capacity of the MFA adsorbent was found to be 35.40 mg g<sup>-1</sup>, while the kinetic and thermodynamic parameters indicated a spontaneous and endothermic process. Due to the low desorption potential of the exhausted adsorbent (MFA/As(V), their effective further material reuse was established to be feasible. The reuse of the exhausted adsorbent was obtained through pozzolanic MFA particles and Ca(OH)<sub>2, </sub>thereby formulating a construction material of a cementitious calcium-silicate hydrate. The toxicity leaching test (TCLP) and mechanical properties of the new construction material containing exhausted MFA (CM-MFA/As(V)) confirm its safe use in the laboratory as well as its semi-industrial application.</p><p>The specific objectives of this study have been: (i) to improve the adsorption performance of the MFA; (ii) to evaluate the material’s equilibrium, as well as the process’ kinetic and thermodynamic aspects, including  estimating its limiting step; and (iii) to investigate the possible reuse of the exhausted adsorbent in the production of construction materials. The kinetic data were successfully fitted by a pseudo-second-order equation and the Weber-Morris model. The metal-desorption experiments performed on the exhausted FA and MFA indicate a low recovery of the selected pollutants.</p><p>The major outcome of this study, indicates that double-valorization of fly ash opens new directions for waste management toward reuse in effective practical applications; i.e., for actual water –purification systems, as well as in the production of construction material.</p>

scholarly journals AN ALTERNATIVE SOLUTION TO ESP RECONSTRUCTION FOR THE COAL FIRING THERMAL POWER PLANTS

2017 ◽  
pp. 49-55
Author(s):  
I.A. Volchyn ◽  
O.M. Kolomiets ◽  
V.A. Raschepkin
Keyword(s):  
Fly Ash ◽  
Flue Gas ◽  
Power Plants ◽  
Electrostatic Precipitator ◽  
Thermal Power ◽  
Distribution Functions ◽  
Thermal Power Plants ◽  
Particle Size Distributions ◽  
Gas Cleaning ◽  
Battery Cyclone

The mathematical modeling is performed of the efficiency of flue gas cleaning from fly ash particles of coal-fired thermal power plants, upon installation of a preliminary flue gas cleaning system that consists of a louvered dust concentrator and a battery cyclone, with the recirculation of flue gas from the battery cyclone outlet to the electrostatic precipitator pre-chamber. Based on the available experimental data for the fractional composition of fly ash downstream the boilers of coal-fired TPPs, the size distribution functions were calculated, of fly ash particles at each stage of the preliminary dust-cleaning process, as well as concentrations and modified particle size distributions, to be further used as the input data for designing options and scope of the reconstruction of existing electrostatic precipitators. Bibl. 13, Fig. 3.

Design and Computational Validation of In-Line Bare Tube Economizer for a 210 MW Pulverized Coal Fired Boiler

2013 ◽  
Author(s):  
P. R. Dhamangaonkar ◽  
Abhishek Deshmukh ◽  
Santosh Pansare ◽  
M. R. Nandgaonkar
Keyword(s):  
Fly Ash ◽  
Flue Gas ◽  
Power Plants ◽  
Gas Flow ◽  
Tube Bundle ◽  
Thermal Power ◽  
Pulverized Coal ◽  
Root Cause ◽  
Economizer Tube ◽  
Bare Tube

One of the pulverized coal fired thermal power plants in India intended to find the root cause of frequent boiler tube failures in three 210 MW units. Operation & Maintenance history and feedback from plant O&M team revealed that economizer tube failure was a frequent cause of forced outage. The plant under study used CFS (continuous fin surface) economizer with staggered tube arrangement in the 210 MW units. CFS staggered tube economizers originally appealed to many plant designers because the tortuous path created for the flue gas, enhanced heat absorption and the fins could capture heat and transfer it to the tubing. This made the CFS economizer less costly and easy for installation in a relatively small space. There is increasing use of lower quality high ash coals over the past few decades. Due to this fact an advantage of the CFS economizer design became a disadvantage. The narrow spacing in the tubes proved more susceptible to plugging and fly ash erosion. Literature study and the root cause analysis suggested that CFS staggered arrangement of economizer could be one of the prominent reason of failure of economizer tube bundle due to fly ash erosion. Flue gas flow simulation also highlighted that there is increase in velocity of flue gases across the economizer. A bare tube in-line configuration in place of existing CFS economizer was an alternative. To recommend an alternate economizer as solution, the merits of an in-line bare tube economizer were studied. Bare tubes arranged in-line are most conservative in hostile environments with high ash content, are least likely to plug, and have the lowest gas-side resistance per unit of heat transfer. A bare tube in-line economizer that can replace the existing finned tube economizer in the available space while meeting the existing design & performance parameters is recommended. An attempt was made to model & analyze the new economizer using computational fluid dynamics (CFD) tools in order to get firsthand experience and validate the results obtained using manual calculations. With limited computational resources and not so fine meshing, the performed CFD model analysis showed the expected trend but did not completely match the results.

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