Power Plant Waste Research Articles

Strontium adsorption on tantalum-doped hexagonal tungsten oxide

Hexagonal tungsten oxide (hex-WO3) has the potential to separate 137Cs and 90Sr from nuclear power plant or fission 99Mo production waste. This study aims to increase the capacity of hex-WO3 to adsorb Sr2+. Ta-doped hex-WO3 was synthesized by the hydrothermal treatment of sodium tungstate dihydrate and tantalum chloride in concentrated HCl, in the presence of ammonium sulfate. Incorporating Ta into the WO3 framework caused the interlayer spacing to expand, and the band gap to shift to higher energy. The Sr2+ adsorption capacity of Ta-doped hex-WO3 was significantly higher than that of hex-WO3. Sr2+ adsorption reached equilibrium within 2h in acidic solution. Maximum Sr2+ removal occurred at pH 4. Sr2+ uptake by hex-WO3 was described better by the Freundlich model than by the Langmuir model. Sr2+ adsorption on hex-WO3 was spontaneous under the studied conditions.

Design of a flat glass furnace waste heat power generation system

China is the largest glass producer in the world. Although the energy consumption of flat glass production has decreased significantly, from 12.6 MJ/kg in 2006 to 8.5 MJ/kg in 2010 and even lower now, very high energy recovery potential exists. A series of documents encouraging the development of glass furnace waste heat power generation systems have been issued by the Chinese government. There are already several waste heat power plants in China. This paper presents a power generation system using the waste heat from a 1200 t/d glass furnace. Two energy sources, viz. natural gas and petroleum coke, are studied. The system steam output is 23 t/h, and the power output 5.2 MW. The high sulfur content in the petroleum coke requires large heating surface area of deaerator to prevent acid corrosion, leading to high investment cost and long payback period. The annual power supply is about 31 million kWh, which means that a saving of 12,400 tons of coal equivalent and a reduction of 0.84 MJ energy consumption of per kilogram glass. The annual reduction of CO2, SO2, NOx and dust are 28,500 tons, 79 tons, 83 tons and 33 tons, respectively.

Physical-chemical properties and structure of foamed slag glass based on thermal power plant wastes

The possibility of producing heat-insulating composite glass material based on slag wastes from thermal plants (foamed slag glass) is examined. A series of foamed slag glass (FSG) compositions has been developed. The water absorption, density, apparent porosity, compression strength and thermal conductivity have been determined. The microstructure of FSG samples with optimal properties has been studied, and the composition for the production of high-quality heat-insulating material has been determined.

Strength and durability of cement with forest waste bottom ash

Every year more than 1m3 of concrete is produced per person worldwide with cement accounting for 5–8% CO2 emissions and a growing use of mineral additions. Timber processing waste, a sustainable and renewable source for energy production, leads to significant amounts of wood-waste fly ash which has been used in concrete of acceptable strength and durability. Grate operated wood waste power plants produce immense volumes of bottom-ash, not studied to date. This study focused on characterising ground bottom-ash (GWA) with strength and durability assessment as cement replacement in mortar. Durability-related properties tested at 80days generally revealed marginal loss but from around 3months, strength surpassed control attaining 12% higher values at 1year. Although tested nonpozzolanic due to crystallinity, GWA may be used as filler in cement-based materials further contributing to sustainable construction.

Microporous metal organic framework [M2(hfipbb)2(ted)] (M=Zn, Co; H2hfipbb=4,4-(hexafluoroisopropylidene)-bis(benzoic acid); ted=triethylenediamine): Synthesis, structure analysis, pore characterization, small gas adsorption and CO2/N2 separation properties

Carbon dioxide is a greenhouse gas that is a major contributor to global warming. Developing methods that can effectively capture CO2 is the key to reduce its emission to the atmosphere. Recent research shows that microporous metal organic frameworks (MOFs) are emerging as a promising family of adsorbents that may be promising for use in adsorption based capture and separation of CO2 from power plant waste gases. In this work we report the synthesis, crystal structure analysis and pore characterization of two microporous MOF structures, [M2(hfipbb)2(ted)] (M=Zn (1), Co (2); H2hfipbb=4,4-(hexafluoroisopropylidene)-bis(benzoic acid); ted=triethylenediamine). The CO2 and N2 adsorption experiments and IAST calculations are carried out on [Zn2(hfipbb)2(ted)] under conditions that mimic post-combustion flue gas mixtures emitted from power plants. The results show that the framework interacts with CO2 strongly, giving rise to relatively high isosteric heats of adsorption (up to 28kJ/mol), and high adsorption selectivity for CO2 over N2, making it promising for capturing and separating CO2 from CO2/N2 mixtures.

Energy and environmental assessment of on-site power and cooling for data centers

High density data centers consume mega watts of electricity for both computing and cooling. Because of the fast paced growth of data center energy demand, effective energy conservation measures must be implemented. The use of on-site combined power generation and cooling systems for data centers that are located on campuses is discussed and compared to grid-powered data centers. The placement of the power plant on site not only reduces transmission losses, but also allows the utilization of the power plant waste heat to generate cooling for the data center and both heating and cooling for adjacent campus buildings. This is why on-site power generation for data centers is an appealing option. Further, with on-site power generation, it is possible to supply the data center with direct current (DC)power, thus, avoiding the cascade of waste in the multiple AC/DC conversions typical of conventional data centers. This article presents a detailed modeling effort to assess the efficiency and environmental and energy cost benefits of such on-site co-generation systems for campus-embedded data centers by utilizing a primary energy analysis.

Source Fingerprints of Volatile Organic Compounds Emitted from A Municipal Solid Waste Incineration Power Plant in Guangzhou, China

Air samples of a municipal solid waste power plant were collected for the investigation from chimney, discharge workshop, boundary site and downwind receptor sites during regular operational period as well as overhaul period. In the regular operational period, 29 VOC species were detected from the discharge workshop and 25 VOC species from the plume of chimney. Average total VOC concentration at the discharge workshop site was 57.70±19.55 μg/m3 which was primarily composed of aromatic compounds and alkanes, but it was up to 270.63±2.84 μg/m3 in the plume of chimney which mainly included aromatic compounds and halohydrocarbons. In the overhaul period, average total VOC concentration was 59.70±0.91 μg/m3 in the discharge workshop and 326.35±151.68 μg/m3 in the chimney. Aromatics, halohydrocarbons and alkanes were indentified as the significant VOC fingerprints among which chlorobenzene and tetrachloroethylene were two unique VOC molecular markers of the power plant. Moreover, the VOC emission inventory of Chinese MSWI power plant was estimated approximately, it indicated that annual emission amount of the VOCs from the nationwide MSWI power plants reached 38.6tons in 2005 and would rise to 81.80 tons in the end of 2010.

Alternative heat rejection methods for power plants

Process waste heat in large power generation plants is commonly rejected to lakes or rivers, or through the use of cooling towers. Although these waste heat rejection methods are effective, they may not be feasible in every application due to cost considerations or geographic location. Moreover, it is desirable to put some of the waste heat to good use, both from the standpoint of improved plant efficiency as well as reduced environmental impact. An analysis of alternative methods of power plant waste heat rejection is presented here as applied to a coal-fired power generation facility in the Midwestern United States. Five approaches for rejecting or recovering the waste heat are considered: cooling canals, open-water algae bioreactors, wintertime greenhouse heating, spray ponds, and modified solar updraft towers. Each of the five technologies can be sized for the needs and operating conditions of a given power plant. The quantitative analysis tools developed in this work are validated by benchmarking against published results. Three of the alternative methods generate secondary benefits: the algae bioreactor, greenhouse heating, and the modified solar updraft tower produce biodiesel, extended periods for horticulture, and electric power, respectively. The land area required to reject 1.16 GW of heat (the condenser heat rejection from a 500 MW plant operating at 30% thermal efficiency) using each of the alternative technologies is compared. The sensitivity of the sizing of the different technologies to changes in the environmental and geometric parameters is quantified. Finally, the net water use for each technology is estimated and compared against a typical cooling tower solution for the same 500 MW plant.

Optimization of the complex recycling of ash and slag from thermal power plants

A physical-chemical model is suggested for the utilization of thermal power plant waste for obtaining of useful products.

Competition of different methods for recovering energy from waste

Waste-to-energy (WtE) facilities have been established worldwide as a sustainable method for the disposal of residual waste. In the present study the following competing WtE systems were compared: (1) municipal solid waste incinerators (MSWIs) with energy recovery; (2) co-incineration of waste in old lignite or coal-fired power plants; (3) substitute [refuse-derived fuel (RDF)] incinerators with energy recovery; and (4) co-incineration of defined waste fractions in cement kilns. In general the municipal solid waste incinerators in Europe are designed for a broad range of municipal and commercial waste without a pre-treatment of the waste. All other WtE processes including the cement kilns require a pre-treatment and are more limited in terms of RDF composition; namely particle size, chlorine content, calorific value. As to Germany, the emission limit values for all facilities are similar. A sensitivity analysis of the economics of boilers using RDF and municipal solid waste leads to the conclusion that the feasibility of RDF incinerators might partially recover if the prices for primary energy increase again. On the other hand, pre-treatment of waste leads to higher costs for RDF. Incineration and recycling capacities are large enough in middle Europe to avoid landfilling of organic waste. The steep decline of gate fees observed in some national spot markets is a clear indicator of an already existing overcapacity. Considering the enormous amount of greenhouse gas emissions saved by WtE facilities in comparison with landfilling, free capacities of WtE installations should be used to incinerate waste from EU member states where waste disposal is still predominantly based on landfilling.

Pond Ash: An Alternative Material as Fine Aggregate in Concrete for Sustainable Construction

Consequent upon increased generation of electricity through thermal route involving combustion of pulverized coal/ignite, concurrent generation of fly ash/pond ash in bulk quantities is a matter of serious concern not only because of issues associated with its disposal and utilization, but also because of its threat to public health and ecology. Though a lot of research has been carried out for the effective utilization of flyash like its use in construction industry etc, little literature is available on pond ash utilization particularly its use as a constituent material for concrete in construction industry. Hence pond ash - a waste material, if supplements shortage of fine aggregate (river sand) in mortar and concrete, reduces the demand for disposal of thermal power plant waste, reduces its environmental impact with proper utilization of huge quantity of waste in construction industry. Researches are being carried out worldwide which shows the suitability of Pond Ash as FA. This paper summerises various characteristics of Pond Ash as fine aggregate in concrete with its engineering properties such as its shape, gradation, texture, physical, chemical and also morphological aspects when used in concrete

Performance Analysis of Coupled System of CO<sub>2</sub> Transcritical Heat Pump and Rankine Cycle

Based on thermodynamic principles, the coupled systems performance of the Rankine cycle and the transcritical CO2compression cycles with a throttle valve and the cycle with an expander were analyzed, respectively. The results show that the corresponding maximum performance in transcritical CO2heat pump, there is an optimal efficiency of the coupled system. With the temperature increasing of boiler feed water, the efficiency of the two coupled system showed an increasing trend; with increasing of discharge pressure of condenser or outlet temperature of gas cooler, both of the two kinds coupled system efficiency showed a downward trend. Under the same conditions, the efficiency of the coupled system with an expander is better than the system with a throttle valve. This paper can provide the fundamental datum for the power plant waste heat recovery.

Energetic valorization of wood waste: Estimation of the reduction in CO 2 emissions

This paper investigates the potential CO 2 emission reductions related to a partial switch from fossil fuel-based heat and electricity generation to renewable wood waste-based systems in Flanders. The results show that valorization in large-scale CHP (combined heat and power) systems and co-firing in coal plants have the largest CO 2 reduction per TJ wood waste. However, at current co-firing rates of 10%, the CO 2 reduction per GWh of electricity that can be achieved by co-firing in coal plants is five times lower than the CO 2 reduction per GWh of large-scale CHP. Moreover, analysis of the effect of government support for co-firing of wood waste in coal-fired power plants on the marginal costs of electricity generation plants reveals that the effect of the European Emission Trading Scheme (EU ETS) is effectively counterbalanced. This is due to the fact that biomass integrated gasification combined cycles (BIGCC) are not yet commercially available. An increase of the fraction of coal-based electricity in the total electricity generation from 8 to 10% at the expense of the fraction of gas-based electricity due to the government support for co-firing wood waste, would compensate entirely for the CO 2 reduction by substitution of coal by wood waste. This clearly illustrates the possibility of a ‘rebound’ effect on the CO 2 reduction due to government support for co-combustion of wood waste in an electricity generation system with large installed capacity of coal- and gas-based power plants, such as the Belgian one.

Nuclear Energy: A Perspective on Recent Results on the Removal of Strontium from Waste

Nuclear Energy: A Perspective on Recent Results on the Removal of Strontium from Waste

Recognising interdependencies in design of nuclear fuel cycle and transportation of SNF and HLW

Spent nuclear fuel (SNF) discharged from a nuclear power plant and high level radioactive waste (HLW) generated during reprocessing SNF are typically stored at the sites where they are generated, often for prolonged periods of time. Eventually, however, these materials must be transported off-site to an interim storage facility, a reprocessing plant, or directly to a deep geologic repository. This paper considers the interdependencies between nuclear fuel cycle options and the transportation system, and argues that both must be addressed as part of an integrated system. Two examples are presented to illustrate why this is important. The first draws from experience gained during development of the US Department of Energy’s (DOE) program for disposing of SNF and HLW in a proposed repository. In particular, decisions DOE made with regard to waste package design had profound implications on the viability of the transportation system. The second example relates to operational changes now underway at nuclear po...

Comparative studies on fly ash coated low heat rejection diesel engine on performance and emission characteristics fueled by rice bran and pongamia methyl ester and their blend with diesel

In this study, for the first time, fly ash was used as a thermal barrier coating material in a diesel engine. The study consists of three phases. In first phase, biodiesel was prepared in a laboratory scale setup by single step base catalyzed transesterification method. In the second phase, engine combustion chamber elements such as cylinder head, cylinder liner, valves and piston crown face were coated with fly ash, which is a thermal power plant waste, to a thickness of 200 μm by using plasma spray coating method. In third phase, experiments were carried out on fly ash coated single cylinder diesel engine fueled by methyl ester of rice bran, pongamia oil and its blend (20% by volume) with diesel. The test run was repeated on uncoated engine under the same running conditions and the results were compared. An increase in engine power and decrease in specific fuel consumption, as well as significant improvements in exhaust gas emissions (except NOx) were observed for all test fuels used in the fly ash coated engine compared with that of the uncoated engine.

Utilization of Slovak bentonites in deposition of high-level radioactive waste and spent nuclear fuel

The basic strategic aims in the field of managing high-level radioactive waste and liquidation of nuclear power plants are all contained in the Energy policy of the Slovak Republic. Its aim is to resolve the concept of the backside of the nuclear energetics fuel cycle—long-term deposition of high-level radioactive waste and spent nuclear fuel (SNF). The most important form of high-level radioactive waste and SNF long-term deposition is their deposition in deep geological formations created by natural as well as engineering barriers used to isolate the long-lived radionuclides from the biosphere. The basic components of these barriers are clays, of which bentonite is generally referred to as the most suitable clay material. There are a few significant bentonite deposits in the Slovak Republic: Jelsový potok, Kopernica, Lastovce, Lieskovec, Dolna Ves. The review article summarizes the information on geotechnical properties of Slovak bentonites published up-to-date, which is inevitable to know for the intention of their use. It highlights the advantages and shows drawbacks of five Slovak deposits. It suggests further research direction, to draw a thorough hydraulical, microbial and radiation profile of Slovak bentonites.

Abrasive Wear Behavior of LDPE Filled with Silane Treated Flyash Cenospheres

Lightweight, high mechanical strength insulating materials exhibiting high resistance to corrosion, solvents and abrasive wear are desired for wire and cable insulation as well as protection. Polyethylenes are generally used for such applications owing to their good electrical insulation properties and being inert to solvents at room temperature. However, their abrasion resistance is quite poor. Hence, in the present work, an attempt has been made to improve the abrasive wear resistance of low-density polyethylene (LDPE) by incorporating hollow microspheres, known as cenospheres, in the base polymer to form composites. These cenospheres are obtained from flyash particles, a thermal power plant waste, and do not tend to increase the weight of the polymer composite when used as a filler. The composites were developed by changing the weight fraction of untreated as well as silane treated cenospheres to the extent of 5 wt%. Tribological characterization of these composites was done in abrasive wear mode by varying the operating parameters, such as speed and sliding distance against silicon carbide paper. It was found that 10 wt% silane treated cenosphere filled LDPE composite showed the maximum wear resistance (∼×10−11 m3/N m) among the six composites. However, a further increase in filler concentration decreased the wear resistance. The improvement in wear resistance was supported by scanning electron microscopy and attributed to the strong interaction between silane treated cenosphere and LDPE molecules which resisted the elongation and shearing of polymer chains by the abrasive grits.

Determination of 93Zr and 237Np in nuclear power plant wastes

A combined radioanalytical method for determination of 93Zr and 237Np (as well as other actinoids) in radioactive wastes has been developed. Analytes were co-precipitated on iron(II)-hydroxide, separated and purified on UTEVA columns, and detected by inductively coupled plasma mass spectrometry. According to Zr and Np, 65 and 75% yields were achieved, respectively.

Removal and recovery of Chrysoidine Y from aqueous solutions by waste materials

This article describes the use of bottom ash [a power plant waste] and de-oiled soya [an agricultural waste] as effective adsorbents for the removal of a hazardous azo dye [Chrysoidine Y] from its aqueous solutions. This paper presents an experimental study and discussion of the adsorption characteristics of this dye on the two adsorbents. The adsorbents have been characterized, and also the effects of time, temperature, concentration, pH, and sieve size on the extent of adsorption have been evaluated. Batch adsorption measurements, kinetic studies, and column operations have been performed to elucidate the dye uptake capacity of the adsorbents. The monolayer adsorption capacities at 30 °C have been found from Langmuir analysis to be 7.27 × 10 −5 mol g −1 and 3.35 × 10 −5 mol g −1 for bottom ash and de-oiled soya, respectively. Adsorption kinetics experimental data are indicative of pseudo-second order kinetics during these processes. Column experiments indicate practical utility of the adsorbents for eradicating hazardous dyes from effluents. The recovery of the adsorbed dye from bottom ash and de-oiled soya, have been found to be 85% and 99%, respectively.