Low-quality Fuels Research Articles

Investigation of the effect of V2O5 and Na2SO4 melted salts on thermal barrier coatings under cyclic conditions

Purpose Thermal barrier coatings (TBCs), which are used in high temperature applications of gas turbines, are damaged due to fuels and airborne minerals under working conditions. Stable zirconia coatings, which are usually used as topcoat materials in TBCs, are damaged by interacting at high temperatures with elements such as vanadium and sulfur from low quality fuels. The purpose of this paper is to see the failure mechanism of TBC systems after hot corrosion damages. Design/methodology/approach CoNiCrAlY metallic bond coatings of TBC samples were produced by cold gas dynamic spray method which is a new trend production method and stabilized zirconia ceramic top coating was produced by atmospheric plasma spray method. In total, 50% by weight of V2O5 and 50% Na2SO4 salt mixtures were placed on TBC samples and subjected to hot corrosion test at 1000°C. Findings Hot corrosion behaviors of TBC samples were examined by scanning electron microscopy, elemental mapping analysis, energy dispersive X-ray spectrometry analysis and X-ray diffraction analysis. TBC samples were damaged at the end of 12-h cycles. Originality/value The paper provides to understand the mechanism of hot corrosion of TBCs with cold sprayed metallic bond coat.

Enhancement of Gasification Performance for Palm Oil Byproduct by Removal of Alkali and Alkaline Earth Metallic Compounds and Ash

One of the problems commonly encountered during the gasification process for biomass is the agglomeration of residue associated with low efficiency, which occurs due to the use of low-quality fuels containing ash and alkali and alkaline earth metallic (AAEM) compounds. In this study, the empty fruit bunch (EFB), which is a byproduct of the palm oil industry that could potentially be used as fuel, was pretreated by washing with both tap water and a nitric acid solution (0.1 wt %) for different washing times to try to resolve this problem. The washing process decreased the ash content from 5.9 wt % to 1.5 wt % when all the washing pretreatments were employed, and over 80 wt % of the AAEM compounds, such as potassium (K), magnesium (Mg), calcium (Ca), and sodium (Na), were removed. Additionally, scanning electron microscopy (SEM) with X-ray diffraction (XRD) was used to identify the composition and surface characteristics of the agglomerations produced during gasification. The proportion of agglomeration mea...

Thermal-hydraulic calculation and analysis on evaporator system of a 660 MWe ultra-supercritical CFB boiler

Ultra-supercritical circulating fluidized bed (CFB) boilers have great commercial potential in large-scale clean utilization of low-quality fuels. Evaporator system is one of the keys in the combination of ultra-supercritical steam cycle with CFB combustion technology. Aiming at examining the thermal-hydraulic characteristic of the evaporator system of the conceptual design of a 660 MWe ultra-supercritical CFB boiler, a mathematical model was developed in this paper. A semi-empirical bed-to-wall heat flux model and a set of empirical correlations available for heat transfer and hydraulic resistance calculation were embedded in the thermal-hydraulic model. By iteratively solving the model, the thermal-hydraulic parameters of the evaporator system at different operating loads, including total pressure drops, mass flux distribution, and metal temperature were obtained. The results exhibit good flow distribution characteristic and low temperature deviations in the evaporator system. The outlet fluid temperature deviation and metal temperature in the evaporator system are both permissible, implying that the conceptual design of the evaporator system of the 660 MWe ultra-supercritical CFB boiler is acceptable.

Integrated Gas – Electricity Network - Combined Heat and Power Optimization with Associated Petroleum and Wet Gas Utilization Constraint

Aside from liquid hydrocarbon, oil exploration also produces associated petroleum gas and wet gas. The use of associated petroleum and wet gas adversely affects gas turbine performance and gas line operation in several ways such as low gas quality, unstable heating value, and high H2S content. This research develops an integrated gas - combined heat and power optimal power flow with associated petroleum and wet gas utilization constraint. Thermodynamic equations are used to model gas turbine and gas network operation when subjected to low-quality fuels. To meet the fuel quality standard, additional constraints are considered. These constraints include the Modified Wobbe Index, a critical parameter for gas turbines, and H2S content, a critical parameter for pipelines. The results show that the proposed model can optimize combined heat and power cost by determining the most efficient power - steam dispatch, optimal fuel mixture and gas line pressure settings, while still meeting operational constraints.

Unburnt Carbon From Oxygen-Enriched Combustion of Low-Quality Fuels at Low Temperatures

This paper investigates the effectiveness of oxygen-enriched combustion process at low temperatures to avoid the unburnt carbon that remains in ash during conventional burning process. For this, thermal treatment of low-quality fuels such as olive pomace and Turkish lignite (Afsin-Elbistan) under oxygen-enriched conditions was tested in a tube furnace at temperatures between 400 and 700 °C under O2/N2 mixtures containing O2 ratios in the range of 25–50 vol %. The calorific value and the unburnt carbon content of the residues from these tests were used to investigate the combined effects of temperature and O2 concentration on unusable part of fuels. Thermal reactivity of untreated parent samples and the residues obtained from oxygen-enriched combustion was also compared based on differential thermal analysis (DTA) and derivative thermogravimetry (DTG) profiles. It was determined that oxygen-enriched conditions are able to remove the organic part of the fuels at low temperatures easily as O2 concentration increases and the oxygen-enriched conditions shifted complete burning temperature to lower values.

Quo Vadis Power Engineering? A Slow Transition from Centralised Power Generation to Distributed Power Generation And what about Poland?

Abstract Is the world's power engineering at a crossroads? Does the rapid development of new emerging fields such as the Internet of Things, smart city or e-mobility make us take a completely different point of view on the world's energy future? What are our visions and development forecasts related to this? Who is right, Exxon Mobil Corporation or the visionary investor Elon Musk? The author of this article is trying to find answers to these and many other questions. In the long-term perspective, a transition from centralised power generation to distributed power generation seems to be inevitable, and that is the central message of this article. The article also presents the situation of the Polish power engineering against the background of global trends, as well as proposals for solving the smog problem using anti-smog technologies developed at the Institute of Fluid-Flow Machinery of the Polish Academy of Sciences in Gdańsk and by launching a pilot project that will cover 1,000 households equipped with these technologies. The author and his closest co-workers recommend equipping boilers, including both older and newer ones, with low-power electrostatic precipitators. In this way, one can burn low-quality fuels while keeping the emission of airborne dust at a low level. It is a quick and not pricey solution to the smog problem.

Experimental Validation of a Three-Component Surrogate for Sasol-Isoparaffinic Kerosene in Single Cylinder Diesel Engine and Ignition Quality Tester

Surrogates development is important to extensively investigate the combustion behavior of fuels. Development of comprehensive surrogates has been focusing on matching chemical and physical properties of their target fuel to mimic its atomization, evaporation, mixing, and auto-ignition behavior. More focus has been given to matching the derived cetane number (DCN) as a measure of the auto-ignition quality. In this investigation, we carried out experimental validation of a three-component surrogate for Sasol-Isoparaffinic Kerosene (IPK) in ignition quality tester (IQT) and in an actual diesel engine. The surrogate fuel is composed of three components (46% iso-cetane, 44% decalin, and 10% n-nonane on a volume basis). The IQT experiments were conducted as per ASTM D6890-10a. The engine experiments were conducted at 1500 rpm, two engine loads, and two injection timings. Analysis of ignition delay (ID), peak pressure, peak rate of heat release (RHR), and other combustion phasing parameters showed a closer match in the IQT than in the diesel engine. Comparison between the surrogate combustion behavior in the diesel engine and IQT revealed that matching the DCN of the surrogate to its respective target fuel did not result in the same negative temperature coefficient (NTC) profile—which led to unmatched combustion characteristics in the high temperature combustion (HTC) regimes, despite the same auto-ignition and low temperature combustion (LTC) profiles. Moreover, a comparison between the combustion behaviors of the two fuels in the IQT is not consistent with the comparison in the diesel engine, which suggests that the surrogate validation in a single-cylinder diesel engine should be part of the surrogate development methodology, particularly for low ignition quality fuels.

Smog - Poland’s pressing problem. Anti-smog technologies

The article also presents the situation of the Polish power engineering against the background of global trends, as well as proposals for solving the smog problem using anti-smog technologies developed at the Institute of Fluid-Flow Machinery of the Polish Academy of Sciences in Gdańsk (IMP PAN) and by launching a pilot project that will cover 1,000 households equipped with these technologies. The author and his closest coworkers recommend equipping boilers, including both older and newer ones, with low-power electrostatic precipitators. In this way, one can burn lowquality fuels while keeping the emission of airborne dust at a low level. It is a quick and not pricey solution to the smog problem.

Influence of KCl and SO2 on NO Formation in C3H8 Flames

The use of low-quality fuels in power generation plants is typically motivated by the potential for reducing fuel costs or CO2 emissions, the latter in the case of a fuel based on biomass. These features make low-quality fuels attractive, although their use for power generation is usually problematic due to their composition. One of the main issues is high-temperature corrosion (HTC), which is caused by alkali-containing chlorides. The alkali chlorides, which are formed from alkali metals and chlorine released from the fuel during the combustion process, are a particular problem. HTC is often related to the combustion of fuels with a low sulfur-to-potassium ratio, such as biomass, and it has a significant effect on the thermal efficiency and/or the maintenance cost of the power plant. Sulfuric and alkali species not only influence the formation of highly corrosive salts but also affect other aspects of combustion chemistry. While the present work relates to HTC chemistry, it focuses on how potassium chlor...

Suitability of selected bioindicators of atmospheric pollution in the industrialised region of Ostrava, Upper Silesia, Czech Republic.

This study is a continuation of our preceding research identifying suitable environmental samples for the tracing of atmospheric pollution in industrial areas. Three additional types of environmental samples were used to characterise contamination sources in the industrial area of Ostrava city, Czech Republic. The region is known for its extensive metallurgical and mining activities. Fingerprinting of stable Pb isotopes was applied to distinguish individual sources of anthropogenic Pb. A wide range of 206Pb/207Pb ratios was observed in the investigated samples: 206Pb/207Pb=1.168-1.198 in mosses; 206Pb/207Pb=1.167-1.215 in soils and 206Pb/207Pb=1.158-1.184 in tree cores. Black and brown coal combustion, as well as metallurgical activities, is the two main sources of pollution in the area. Fossil fuel burning in industry and households seems to be a stronger source of Pb emissions than from the metallurgical industry. Concentration analyses of tree rings showed that a significant increase in As concentrations occurred between 1999 and 2016 (from 0.38mgkg-1 to 13.8mgkg-1). This shift corresponds to the use of brown coal from Bílina, Czech Republic, with an increased As concentration. The burning of low-quality fuels in households remains a problem in the area, as small ground sources have a greater influence on the air quality than do industrial sources.

Development of the system of automatic control of steam boilers at electric power plants during combustion of low quality fuel

A general principle of energy saving control of a steam boiler at thermal power stations is presented, which implies the formation and subsequent minimization of function of energy losses. This provides the possibility to ensure minimum losses of energy (maximum efficiency) under all basic modes of normal work of equipment. Parameters of the combustion activator are included in functional dependences and initial models of a boiler unit as the object of control, which makes it possible to form reference models of a steam boiler, necessary for solving the problem of energy saving control during the combustion of low quality fuels. A method for increasing the accuracy of measurement and the control of feeding solid fuel to the furnace of a boiler at thermal power stations is proposed. This makes it possible to regulate fuel consumption more accurately and to have more precise information for determining technical and economic indices of work of the power unit. A new system of automated control of feeding additives, which activate the process of combustion, was proposed. The system of automated control of additives makes it possible to accurately regulate consumption of additives depending on the quality and amount of fuel supplied to the furnace. This provides for the possibility to maximally use the potential of activators of combustion for different grades of solid fuel. The proposed system may be used at thermal power plants that operate on the low quality fuel. The implementation of the proposed solutions will make it possible to increase efficiency of the power units of coal-dust TPP at the combustion of low quality fuels by the magnitude of up to 4 %, as well as to completely eliminate the addition of natural gas.

Butanol or DEE blends with either straight vegetable oil or biodiesel excluding fossil fuel: Comparative effects on diesel engine combustion attributes, cyclic variability and regulated emissions trade-off

This work investigates comparatively the effects of using as base fuels straight vegetable oil (SVO) and its biodiesel in blends with 10% or 20% of either n-butanol or DEE as supplements, excluding fossil fuel. The combustion attributes, cyclic variability, and all regulated emission trade-offs are examined in an experimental, ‘Hydra’ diesel engine at three loads. Cylinder pressure diagrams and related heat release rate analysis disclose and aid the interpretation of the differences observed in combustion attributes among all bio-fuels blends. Since low ignition quality fuels, such as the present bio-fuel supplements, may give rise to unstable engine operation and so detrimental performance, this work focuses also on the comparative examination of the strength of cyclic combustion variations as reflected in the cylinder pressure diagrams, by analyzing for maximum pressure and rate, indicated mean effective pressure, and ignition delay, using statistical analysis tools for averages and coefficients of variation (COV). The above results and the different physical and chemical properties of bio-fuels are used to aid the interpretation of engine stability differences observed among all bio-fuels examined, as well as the balance of all four exhaust emissions. The latter reveal defeat of smoke-NOx trade-off and interesting CO-HC adverse trade-off.

Comparative Evaluation of Ethanol, n-Butanol, and Diethyl Ether Effects as Biofuel Supplements on Combustion Characteristics, Cyclic Variations, and Emissions Balance in Light-Duty Diesel Engine

AbstractThis work evaluates experimentally on a comparative basis the effects of using three customary biofuels on the cyclic variability (irregularity) of combustion and emissions balance in a single-cylinder, light-duty, direct-injection diesel engine run at three loads. Blends of fossil diesel with up to 15% (by volume) ethanol and 24% n-butanol or diethyl ether (DEE) are investigated. Related experimental study including heat release diagrams reported by the authors for these blends in the same engine disclosed the differentiation in performance and emissions of these biofuel blends from running the engine with neat fossil diesel. Given that low ignition quality fuels, as the present biofuels, mainly at high blending ratios may give rise to unstable engine functioning and hence detrimental performance, this work examines on a comparative basis the strength of combustion cycle-to-cycle variations as revealed in the measured cylinder pressure diagrams. The latter are analyzed with respect to maximum pre...

High-Pressure Electronic Fuel Injection for Small-Displacement Single-Cylinder Diesel Engines

Small-displacement single-cylinder diesel engines employ mechanically actuated fuel injection systems. These mechanically governed systems, while robust and low cost, lack the ability to fully vary injection parameters, such as timing, pulse duration, and injection pressure. The ability of a particular injection system to vary these injection parameters impacts engine efficiency, power, noise, and emissions. Modern, multicylinder automotive engines employ some form of electronically controlled injection to take advantage of the benefits of fully variable injection, including advanced strategies such as multipulse injections and rate shaping. Modern diesel electronic fuel injection (EFI) systems also operate at considerably higher injection pressures than mechanical fuel systems used in small-bore industrial engines. As the cost of electronic fuel systems continues to decrease and the demand for high-efficiency engines increases, EFI becomes a more viable option for incorporation into small industrial diesel engines. In particular, this technology may be well-suited for demanding and critical applications, such as military power generation. In this study, a small-bore single-cylinder diesel was retrofit with a custom high-pressure EFI system. Compared to the mechanical injector, the electronic, common-rail injector had a 50% smaller orifice diameter and was designed for a fourfold higher injection pressure. The mechanical governor was also replaced with an electronic speed controller. The baseline and modified engines were installed on a dynamometer, and measurements of exhaust emissions, fuel consumption, brake torque, and in-cylinder pressure were made. The electronic injector leads to lower smoke opacity and NOx emissions, while CO and hydrocarbon emissions were observed to increase slightly, likely due to some wall wetting of fuel with the initial prototype injector. Testing with low ignition quality fuels was also performed, and the electronic fuel system enabled the engine to operate with fuel having a cetane number as low as 30.

Source apportionment with uncertainty estimates of fine particulate matter in Ostrava, Czech Republic using Positive Matrix Factorization

A 14-week investigation during a warm and cold seasons was conducted to improve understanding of air pollution sources that might be impacting air quality in Ostrava, the Czech Republic. Fine particulate matter (PM2.5) samples were collected in consecutive 12-h day and night increments during spring and fall 2012 sampling campaigns. Sampling sites were strategically located to evaluate conditions in close proximity of a large steel works industrial complex, as well as away from direct influence of the industrial complex. These samples were analyzed for metals and other elements, organic and elemental (black) carbon, and polycyclic aromatic hydrocarbons (PAHs). The PM2.5 samples were supplemented with pollutant gases and meteorological parameters. We applied the EPA PMF v5.1 model with uncertainty estimate features to the Ostrava data set. Using the model's bootstrapping procedure and other considerations, six factors were determined to provide the optimum solution. Each model run consisted of 100 iterations to ensure that the solution represents a global minimum. The resulting factors were identified as representing coal (power plants), mixed Cl, crustal, industrial 1 (alkali metals and PAHs), industrial 2 (transition metals), and home heat/transportation. The home heating source is thought to be largely domestic boilers burning low quality fuels such as lignite, wood, and domestic waste. Transportation-related combustion emissions could not be resolved as a separate factor. Uncertainty estimates support the general conclusion that the factors identified as representing coal power and home heat/transportation dominate the percent contribution to fine mass. Apportionment of regulated individual species is also presented.

Air pollution: 6.6million premature deaths in 2050!

Air pollution: 6.6million premature deaths in 2050!

Biomass Gasification Plant and Syngas Clean-up System

Gasification is recognized as one of the most promising technologies to convert low quality fuels into more valuable ones. The principal problem related with the use of biomass in gasification processes is the high amount of tar released during the pyrolysis step. It is thus necessary to recover tar and to transform it in lighter combustible gas species such as CH4, CO and H2. In this work the experimental results of a medium industrial scale plant fed with olive husk and having a capacity of 250 kWt are presented. The gasifier is composed by a up-draft reactor which is followed by a secondary fixed bed reactor filled with alluminium oxide spheres having high porosity dedicated to the tar conversion reactions. The syngas is then used to feed an internal combustion engine with a production of 60 kWe.

Olive oil residue gasification and syngas integrated clean up system

Gasification is one of the most promising technologies to convert low quality fuels into more valuable ones. The main problem in the use of biomass in gasification processes is the high amount of tar released in the pyrolysis step. It is thus necessary to recover the tar and to transform it in lighter combustible gas species such as CH4, CO and H2 by means of catalytic processes. In this work the gasification of olive husk is performed in order to produce a high quality syngas, composed mainly of carbon monoxide and hydrogen, using an innovative laboratory scale plant composed of a unique reactor divided into three sections. The first section is dedicated to the pyrolysis, the second to the gasification of char produced during pyrolysis and the third to the catalytic reforming of tar. In the reformer two catalysts were tested: a CeO2 promoted bimetallic Ni–Co catalyst and a Ni catalyst, both supported on γ-Al2O3. This plant design allows one to minimize the heat dispersion enhancing the energy efficiency of the unit.

Low-Quality Fuels for Small-Scale Combustion Boilers: An Experimental Study

This work focuses on the combustion performance of cheap low-quality fuels as an alternative to existing pellets and chips for small-scale combustion. The market is keen on using locally available fuels, but a lack of information on their performance in boilers and legislation has prevented wider use. The approval of the regulation that implements Directive 2009/125/EC regarding ecodesign requirements for solid fuel boilers proposes even tighter requirements beyond 2018, as compared to class 5 in EN303-5:2012, and mainly gives more relative importance to the partial loads. Our study analyzes woody chip industry residues, agricultural residues, logging forest residues, agricultural pellet residues, and shells and stones from agricultural industry residues at nominal and especially at partial load. Two commercial boilers have been representatively chosen for the state-of-the-art top-fed and bottom-fed boilers.

A Stirling engine for use with lower quality fuels

A Stirling engine for use with lower quality fuels was designed. The design is a derivative of the GPU-3 (ground power unit-3), modified to be used with a lower combustion gas temperature (900 °C). It is to be used in a generator set producing 5 kWe. The engine model used is based off of the ideal adiabatic model with decoupled loss mechanisms. Single-cylinder and two-cylinder engines were analyzed using a preheater and CGR (combustion gas recirculation). The analysis shows that the external surface area of the heater plays a very important role in determining the system performance. Maximum system efficiency was found by significantly increasing the surface area at the expense of increased dead volume. A single-cylinder configuration was found to offer the best combination of system efficiency (23.6%) and manufacturing cost.