Atmospheric Fluidized Bed Combustion Research Articles

Development of emission reduction measures of trace gas emissions from coal-fired power plants in Indonesia

Most of Indonesia’s electricity demand is supplied by coal fired power plants (CFPPs) which can potentially emit huge amounts of air pollutant gases such as NOx and SO2 gas. The country has committed to reduce Greenhouse Gases (GHGs) emission by 2030 through Nationally Determined Contributions but some emission reduction measures may also reduce air pollutant gases. Flue Gas Desulfurization (FGD) and Atmospheric Fluidized Bed Combustion (AFBC) are the leading control technologies for reducing SO2 and NOx emissions that can be installed in the CFPPs. This study aims to determine the pollution load of SO2 and NOx gases in 2030 generated from CFPPs operation with (reduction scenario) and without FGD and AFCB control technology (business as usual (BAU)). The gas pollution load was calculated using the Atmospheric Brown Clouds- Emissions Inventory Manual (ABC-EIM) procedure. Based on the BAU scenario, the emission load accounted of 1,440,192 tons/year for NOx and 613,121 tons/year for SO2 in 2030. After implementing the control technology scenarios in 2030, the NOx emission load is projected to decrease to 579,610 tons/year, and the SO2 emission load decrease to 77,920 tons/year. The application of AFBC and FGD control technologies can potentially reduce NOx and SO2 emissions load from CFPPs operation in 2030 thus it can help to improve air quality in the future.

Experimental Analysis of CFBC Boiler and AFBC Boiler with Different GCV, Boiler Loads and Excess Air

Abstract: The main motive of this study is to experimental analysis of the Atmospheric fluidized bed combustion boiler and Circulating fluidized bed combustion boiler with different gross calorific value of coal, boiler loads and excess air. For this analysis, use textile waste as a primary fuel and calculate GCV with help of bomb calorimeter. Conduct energy calculation of the overall plant and determine the efficiencies and energy losses of all the major components of the thermal power station. The study was carried out at Thermal power station of Industry Yarns at Mandideep and boiler section of thermal power plant is considered for the purpose of exergy analysis. The boiler of a power plant is the most effective section in eliminating exergy. Calculate the efficiency of CFBC and AFBC Boiler with different GCV of Textile waste and it is clearly shows that efficiency of CFBC boiler is higher than AFBC boiler in same GCV of textile waste. The present investigation show results of 30 mw power plant. Experiments were conducted using 0%, 20 %, 30% and 40% of excess air and 65%,70%,75%,80%,85%,90%,95% ,100% boiler loads. In the present investigation boiler house gives the best results at 0% excess air with maximum boiler load as far as the boiler efficiency (75.2%) are concerned. 65% boiler load With 0% excess air the boiler efficiency is found to be maximum (75.2%), which gives minimum heat loss. Without excess air AFBC boiler is not capable to burn low grade fuels show it is clear that for low grade fuel maximum efficiency of thermal power plant achieved by CFBC boiler because low grade fuel completely burns with 0% excess air.

Optimization of Atmospheric Fluidized Bed Combustion Boiler by Computational Fluid Dynamics

Optimization of Atmospheric Fluidized Bed Combustion Boiler by Computational Fluid Dynamics

Performance assessment of 2×90 tph (afbc) boiler and study of hp heater

TNPL (Tamilnadu Newsprint and papers limited) unit-2 has two boilers; each boiler is 90 Tons per hour capacity. These are single drum, natural circulation water tube, under bed and over bed firing, top supported pressure parts and bed plate design atmospheric fluidized bed combustion (AFBC) boiler. Imported coal is the fuel for these boilers, for better operation, a performance assessment study of these boilers has been made, also HP (high pressure) heater is a special type of heat exchanger designed for recovering of heat from extraction steam to preheat feed water. They provide efficiency gain by increasing the initial water temperature. A study has been made how the HP heater can increase the efficiency of boilers. For HP heater motive steam from turbine extraction is used after generation of power.

Cost Management of a CFBC Boiler in a Thermal Power Plant

India, being the world's third most noteworthy power maker with all out exhibited purpose of containments of 344.69 GW, contributing 68% of thermal Capacity. Subsequently, Thermal power producing stations are basic. As an electrical architect, exceptional consideration ought to be taken to decrease coal utilization in Thermal power generating stations. In Thermal power producing stations, boilers utilized are Circulating Fluidized Bed Combustion (CFBC) and Atmospheric Fluidized Bed Combustion (AFBC). These boilers utilize bed material to keep up warmth in the boiler. 210MW and under 210 MW generators in the Thermal power producing stations are utilizing CFBC boilers. After a nearby examination of thermal power stations, it is discovered that the bed material including over 5% of engaging parts are open in the bed material which is horrendous. This happens where magnetic separator at the bed material stacking point is missing or far off. From this time forward it is proposed to introduce a magnetic separator at the bed material stacking point. With this establishment of magnetic separator hardware, boiler efficiency can be reached out to 2.1% more, to keep up the required temperature and to maintain a strategic distance from boiler stoppages. An endeavor has been made to perceive the usage required presenting attractive separator and it has been discovered that the reward period is obliged to roughly 1 to 2 years if the engaging sections in the bed material are 5%and 10% respectively. The Proposed issue is endeavored with MATLAB condition and cost examination of thermal power plant is separated and existing synthesis information. The test outcomes displayed that the proposed framework gives an attainable game-plan gigantic theory saves and liberal for consistent assignments.

CHARACTERIZATION OF AN EXPERIMENTAL FACILITY FOR BUBBLING FLUIDIZED BED COMBUSTOR

Fluidized bed technology offers an attractive way for energy production with clean environment by the combustion of even low-grade waste derived fuels (WDF). This paper reports experimental results concerning the characterization of a small-scale bubbling atmospheric fluidized bed combustor with WDF batch feeding. The combustor having 0.215 m inner diameter and 1.88 m height is equipped with a packed-bed sandwich-type fluidizing air distributor. The experimental fluidized bed combustor (EFBC) is provided with facility items necessary for the operation, control, and measurements. Results of the measured fluidized bed pressure drop and temperature were investigated for cold flow, hot flow, and combustion tests during the characterization procedure. The results of these tests clearly indicated the good fluidization characteristics inherent to well-controlled operation of the EFBC facility. The characterization tests also indicated the reproducible and safe operation characteristics of the EFBC facility without appreciable leakage of fluidizing air and exhaust gases. Moreover, the obtained uniformity of the fluidized bed temperature together with the high estimated values of bed-to-immersed cooling coil heat transfer coefficient, added more evidence on the good combustion characteristics of the investigated EFBC facility.

First Efforts in Benchmarking the Stoker/Pulverized Coal Industry

Environmental impact of the coal-fired, electrical power industry has led to increased regulatory requirements. For the industry to remain relevant, it is paramount that it maintains a trajectory of progress towards higher efficiencies and cleaner emissions. Research and development might lead to new technologies, but in the meantime, improvement of existing technology must also be a focus. One method being pursued for this is a benchmark study which can identify best practices and areas where performance might be improved. Over the last decade, the Council of Industrial Boiler Owners and certain faculty at West Virginia University have worked together to collect survey data from atmospheric fluidized bed combustion boiler industry members. However, this accounts for only a small portion of the total coal-fired, electrical power industry (~2%). On the other hand, stoker/pulverized coal boiler operation accounts for most of the industry production (~92%). This report gives the data gathered from stoker/pulverized coal industry members for the operational year 2012. From the applied survey methods, the resulting data pool was small due to a small number of respondents. In the future it is important that the number of survey respondents increases to better reflect the industry and allow more successful benchmarking of the industry. For this initial effort, comparisons are made against recent fluidized bed combustion data to show that, for the given survey responses, stoker/pulverized coal boilers operated at a lower average calcium/sulfur ratio, higher average efficiency, and on average, required more non-management staff per gross MW. This study and comparison serves to provide a good starting point for efforts in benchmarking the stoker/pulverized coal industry.

SINTERING OF JORDANIAN OIL SHALE UNDER SIMILAR CONDITIONS OF FLUIDIZED BED COMBUSTION SYSTEMS

Oil shale in Jordan and elsewhere faces many obstacles that hinder its utilisation. Recent developments of the utilization of Jordanian oil shale include the establishment of power generation companies that depend on the technology of atmospheric fluidized bed combustion systems (FBC). Sintering is believed to have been the main cause of many operational problems of FBC systems. This work investigates the sintering propensity of ash obtained from oil shale from Jordania's largest oil shale deposit El-Lajjun, when combusted at different temperatures, as well as major mineral transformations as a function of temperature. The results obtained by the pressure drop sintering technique showed that the sintering temperature is a strong function of the combustion temperature. Two regions of sintering were found: a low tem- perature sintering region and a high sintering temperature region. The low sintering temperature region starts at around 700 °C where it is believed to be due to the sintering of limestone. On the other hand, the high sintering tem- perature region, which starts at 900 °C, is believed to be due to the sintering of the wollastonite formed. Scanning Electron Microscope (SEM) images and Brunauer-Emmett-Telle (BET) measurements confirm these findings.

Failure Analysis of Bed Coil Tube in an Atmospheric Fluidized Bed Combustion Boiler

The Atmospheric Fluidized Bed Combustion Boilers have advantages as compared to conventional coal fired boilers in respect of heat transfer, SOx, NOx, emissions and efficiency. In the present study, the failure analysis of bed coil tube, used in atmospheric fluidized bed combustor was studied. The failure studies included physical, chemical and metallurgical analysis and the results analyzed reveal that the failure is typically due to caustic gouging. The cause of failure has further been substantiated using scanning electron microscopy with energy dispersive X-ray analysis as well as X-ray diffraction analysis.

Minesoil Response to Reclamation by Using a Flue Gas Desulfurization Product

Mine lands are an environmental concern worldwide because of their potential strong negative impact on water and soil quality. A field study was conducted to assess the use of a dry flue gas desulfurization (FGD) product for reclamation of an abandoned surface coal mine in Ohio. The FGD product was an atmospheric fluidized bed combustion residue and was applied to the graded mine site at 280 Mg ha-1, both alone and in combination with 112 Mg ha-1 yard waste compost, and was compared with conventional reclamation with 20 cm of borrow soil plus 157 Mg ha-1 of agricultural limestone. A grass-legume sward was planted, and soil physical and chemical properties and β-glucosidase activity were measured over both short- (1–4 yr) and long-term (15–17 yr) periods following reclamation. Soil pH at 0- to 20-cm depth increased from 3.1 to approximately neutral and was sustained at this level for 15 yr. Compared with the conventional reclamation, extractable Ca, S, B, and Zn concentrations at 0- to 20-cm depth were generally increased by the treatments with FGD product, while other extractable trace metals measured were generally not increased in short- or long-term measurements. Seventeen years after reclamation, β-glucosidase activity had increased in all three treatments at 0- to 5- and 5- to 10-cm depths compared with an adjacent untreated area. Furthermore, β-glucosidase activity more than doubled in the treatments with FGD product compared with the conventional soil treatment at 0- to 5-cm depth. These results suggest that the use of high lime FGD products for reclamation of acid coal mine lands can provide effective long-term reclamation.

Organic atmospheric pollutants: polycyclic hydrocarbons from coal atmospheric fluidised bed combustion (AFBC)

The work deals with coal combustion in a pilot-plant fluidised bed (7 cm i.d.) under atmospheric conditions. The aims are to capture and analyse qualitatively as well as quantitatively the volatile polycyclic hydrocarbons emitted by using coal as energy source under various combustion conditions. After establishing the sampling procedure, the emissions are caught in five different traps (two cyclones, nylon and teflon filters, and XAD-2). The contribution of each of the sixteen polycyclic aromatic hydrocarbons (PAH) listed by the US Environmental Protection Agency (EPA) as priority pollutants is analysed, and their emissions as a function of the combustion variables (combustion temperature, percentage of excess oxygen, air flow and fluidising agent) are reported. Synchronous Fluorescence Spectroscopy is the analytical tool used for identification and quantification of the PAH emissions.

Techno-economic comparison between different technologies for a CCS power generation plant integrated with a sub-bituminous coal mine in Italy

The increasing interest in the development of carbon capture and storage (CCS) technologies requires a great effort to reduce capital and operating costs and to demonstrate the potential application of these kind of systems on the commercial power generation plants.This paper shortly describes the main results of a technical and economical comparison between different CO2-free power generation plant configurations, with a particular reference to ultra supercritical (USC) pulverised coal combustion plant, atmospheric fluidized bed combustion (AFBC), integrated gasification combined cycle (IGCC) and a potential projection for the application of oxy-combustion technologies. The comparative analysis is based on the typical economic indicators such as net present value, internal rate of return, payback time and cost of electricity; all these parameters have been calculated on the basis of the annual cash flow during the plant operating life. Due to the impossibility to estimate with accuracy the future trend of some parameters, a sensitivity analysis has been also carried out in order to evaluate the effects of these assumptions, with a subsequent risk reduction for the potential investment.As reference case, a 660MWe (referred to the hypothetical “basis” configuration, without CCS system) operating in close integration with the Sulcis coal mine (South–West Sardinia island, Italy) has been considered. As a matter of fact, the Sulcis sub-bituminous coal basin, in which the only Italian coal mine is located, represents a key point for the increasing of the Sardinian energy security, by raising the power generation capacity and partially releasing energy production from imported primary sources; in parallel, the economy in the Sulcis area has to be re-launched through the strengthening of the local industry.

Benchmarking the North American Atmospheric Fluidized Bed Industry

Benchmarking the North American Atmospheric Fluidized Bed Industry (abstract) Atmospheric fluidized bed combustion (AFBC) boilers are a mature, well established, and valuable technology. Their fuel flexibility, combustion efficiency, and relatively low emission levels have seen them attract new interest in recent times. In order to ensure plant sustainability it is important for AFBC plant operators to maintain a high level of operational performance and plant efficiency. Benchmarking is a tool that can aid the attainment of superior performance and efficiency levels. It has widespread use throughout many industries and allows managers to gauge how their company performs relative to similar firms and identify areas that are in need of improvement. Sponsored by Council of Industrial Boiler Owners (CIBO), this paper presents a set of North American AFBC industry benchmarks for the year of 2009. Focusing on both circulating and bubbling bed boilers, the benchmarks are intended to enhance the industry’s overall efficiency and sustainability.

Performance Benchmarking: A Literature Review And Analysis For Atmospheric Fluidized Bed Combustion Plants

Gaining and maintaining a competitive edge is the key to success in all walks of life, both on the athletic field and in the boardroom.This research paper will: (1) provide a background on the concept of benchmarking; and (2) present some examples of performance benchmarks for AFBC (atmospheric fluidized bed combustor) steam and power plants resulting from data collected during 1999.

Some Environmental Bottlenecks to Coal Utilization for Power Generation in Nigeria and Their Corrective Actions

Given the magnitude of the Nigerian coal reserves, the industrialization role coal played in the pre-petroleum era, and the resources conservation consideration dictating that some local resources be used so as to conserve and extend the depletion years of oil and gas, Enugu coal offers a promising alternative solution to Nigeria's power generation. Unfortunately, emissions from coal combination chiefly impose some environmental bottlenecks to coal utilization for power generation. This article reviews the roles of nitrogen oxides and sulfur dioxide emissions as acid gas, as well as the activities of carbon dioxide as both acid gas and greenhouse gas. The article also examines the impact of environmental concern and legislation on the control of combustion emissions. To ensure compliance with legislation and environmental concerns, this paper proposed fluidized bed combustion as the remedy for combustion emissions control. In this regard, two categories of FBC, namely bubbling fluidized bed and circulating fluidized bed combustors, were reviewed in conjunction with their modes of operation in the forms of: • atmospheric fluidized bed combustion and • pressurized fluidized bed combustion. The review showed that the bubbling fluidized beds are more viable for retrofit applications, while the circulating fluidized bed units are more applicable in new plants. Owing to the non inclusion of carbon dioxide parameters in the operating credentials of bubbling fluidized bed and circulating fluidized bed units, some of the known technologies for carbon dioxide scrubbing/removal were suggested as this article will show.

Design assessment of a 150 kWt CFBC Test Unit

For clean and efficient energy generation from coal, the most suitable technology known to date is ‘Fluidized Bed Combustion’ technology. Applications of circulating fluidized bed (CFB) combustion technology have been steadily increasing in both capacity and number over the past decade. Designs of these units have been based on the combustion tests carried out in pilot scale facilities to determine the combustion and desulfurization characteristics of coal and limestone reserves in CFB conditions. Similarly, utilization of Turkish lignites in CFB boilers necessitates adaptation of CFB combustion technology to these resources. However, the design of these test units are not based on firing coals with high ash, volatile matter and sulfur contents like Turkish lignites. For this purpose, a 150 kWt CFB combustor test unit is designed and constructed in Chemical Engineering Department of Middle East Technical University, based on the extensive experience acquired at the existing 0.3 MWt Bubbling Atmospheric Fluidized Bed Combustor (AFBC) Test Rig. Following the commissioning tests, a combustion test is carried out for investigation of combustion characteristics of Çan lignite in CFB conditions and for assessment of the design of test unit. Comparison of the design outputs with experimental results reveals that most of the predictions and assumptions have acceptable agreement with the operating conditions. In conclusion, the performance of 150 kWt CFBC Test Unit is found to be satisfactory to be utilized for the long term research studies on combustion and desulfurization characteristics of indigenous lignite reserves in circulating fluidized bed combustors.

Limestone fragmentation and attrition during fluidized bed oxyfiring

Attrition/fragmentation of limestone under simulated fluidized bed oxyfiring conditions was investigated by means of an experimental protocol that had been previously developed for characterization of attrition/fragmentation of sorbents in air-blown atmospheric fluidized bed combustors. The protocol was based on the use of different and mutually complementary techniques. The extent and pattern of attrition by surface wear in the dense phase of a fluidized bed were assessed in experiments carried out with a bench scale fluidized bed combustor under simulated oxyfiring conditions. Sorbent samples generated during simulated oxyfiring tests were further characterized from the standpoint of fragmentation upon high velocity impact by means of a purposely designed particle impactor. Results showed that under calcination-hindered conditions attrition and fragmentation patterns are much different from those occurring under air-blown atmospheric combustion conditions. Noteworthy, attrition/fragmentation enhanced particle sulfation by continuously regenerating the exposed particle surface.

Flue gas desulfurization under simulated oxyfiring fluidized bed combustion conditions: The influence of limestone attrition and fragmentation

Flue gas desulfurization by means of limestone injection under simulated fluidized bed oxyfiring conditions was investigated, with a particular focus on particle attrition and fragmentation phenomena. An experimental protocol was applied, based on the use of complementary techniques that had been previously developed for the characterization of attrition of sorbents in air-blown atmospheric fluidized bed combustors. The extent and pattern of limestone attrition by surface wear in the dense phase of a fluidized bed were assessed in bench scale fluidized bed experiments under simulated oxyfiring conditions. Sorbent samples generated during the oxyfiring tests were further characterized from the standpoint of fragmentation upon high velocity impact by means of a particle impactor. The experimental results were compared with those previously obtained with the same limestone under air-blown atmospheric fluidized bed combustion conditions. The profound differences in the attrition and fragmentation extents and patterns associated with oxyfiring as compared to air-blown atmospheric combustion and the role played by the different attrition/fragmentation paths were highlighted. In particular, it was noted that attrition could effectively enhance particle sulfation under oxyfiring conditions by continuously disclosing unconverted calcium to the sulfur-bearing atmosphere.

Limestone Attrition under Simulated Oxyfiring Fluidized‐Bed Combustion Conditions

AbstractLimestone attrition by surface wear was studied during the flue gas desulfurization under simulated fluidized‐bed (FB) oxyfiring conditions and hindered calcination. Bench‐scale experimental tests were carried out using well‐established techniques previously developed for the characterization of sulfation and attrition of sorbents in air‐blown atmospheric FB combustors. The experimental limestone conversion and attrition results were compared with those previously obtained with the same limestone under simulated air‐blown combustion conditions. The differences in the conversion and attrition extents and patterns associated with oxyfiring as compared to air‐blown atmospheric combustion were highlighted and related to the different particle morphologies and thicknesses of the sulfate layer. It was noted that attrition could play an important role in practical circulating FB combustor operation, by effectively enhancing particle sulfation under both oxyfiring and air‐blown combustion conditions.

Devolatilization of coals of North-Eastern India under fluidized bed conditions in oxygen-enriched air

Oxygen-enriched air can increase the combustion efficiency, boiler efficiency, and sulfur absorption efficiency of atmospheric fluidized bed combustion (AFBC) boilers which use high-sulfur coal, and other combustion systems that use coal. Devolatilization is the first step in the gasification or combustion of coal. In this work, devolatilization characteristics of five run-of-mine (ROM) coals of North-Eastern India having particle-size between 4 mm and 9 mm are reported. The experiments were performed under fluidized bed conditions at 1123 K in enriched air containing 30% oxygen. The devolatilization time was correlated with the particle diameter by a power law correlation. The variation of mass with time was correlated by an exponential correlation. It was observed that the average ratio of yield of volatile matter to the proximate volatile matter decreased with the increase in volatile-content of the coals. A shrinking-core model was used to determine the role of film-diffusion, ash-diffusion and chemical reaction. The experimental results indicate the likelihood of film-diffusion to be the rate-controlling mechanism in presence of oxygen-enriched air. A cost-analysis was carried out to study the economy of the process.