scholarly journals Techno-Economic Design of Flue Gas Condensers for Medium-Scale Biomass Combustion Plants: Impact of Heat Demand and Return Temperature Variations

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2337 ◽  
Author(s):  
Thibault Coppieters ◽  
Julien Blondeau
Keyword(s):  
Flue Gas ◽  
Energy Savings ◽  
Economic Feasibility ◽  
Dew Point ◽  
Pollutant Emissions ◽  
Economic Viability ◽  
Biomass Combustion ◽  
Process Data ◽  
Medium Scale ◽  
Heat Demand

Despite their obvious benefit in terms of energy efficiency and their potential benefit on pollutant emissions, Flue Gas Condensers (FGCs) are still not widely spread in biomass combustion plants. Although their costs have significantly decreased during the last decade, the economic viability of FGC retrofits is not straightforward and their return on investments is mainly dependent on the temperature of the available heat sink and the moisture content of the fuel. Based on a new techno-economic model of a FGC validated with recent industrial data, this paper presents a methodology to assess the economic viability of an FGC retrofitting in a medium-scale biomass combustion plant. The proposed methodology is applied to the case of a typical District Heating plant for which real data was collected. For the first time, the usual assumptions of constant process data generally used are challenged by considering the variability of the return temperature and heat demand over the year. Furthermore, a new concept of optimal configurations in terms of energy savings is introduced in this paper and compared to a strictly economic optimum. The economic feasibility is mainly evaluated by means of the Net Present Value (NPV), Discounted Payback Period (DPP), and the Modified Internal Rate of Return (MIRR). As expected, results show that the higher the humidity level and the lower the return temperature, the higher the economic profitability of a project. The NPV is, however, increased when considering variable inputs: Even with an average return temperature of 60 °C, a mixed operation of the FGC as a condenser and an economizer along the year is predicted, which results in an increased profitability assessment. Considering a constant return temperature over the year can lead to a 20% underestimation of the project NPV. An alternative averaging method is proposed, where two distinct temperature zones are considered: above and below the flue gas dew point. The discrepancy with a detailed temperature variation is reduced to a few percents. Our results also show that increasing the FGC surface beyond the highest NPV can lead to substantial energy savings at a reasonable cost, up to a certain level. The energetic optimum we defined can lead to an increase in energy savings by 17% for the same relative decrease of the NPV.

Waste / Low Quality Heat Recovery and Utilization With Low Temperature Economizers

2013 ◽  
Author(s):  
John M. Preston ◽  
W. Reid Watson ◽  
Charles B. Jones
Keyword(s):  
Sulfuric Acid ◽  
Fly Ash ◽  
Low Temperature ◽  
Flue Gas ◽  
Heat Recovery ◽  
Heat Rate ◽  
Economic Feasibility ◽  
Dew Point ◽  
Plant Performance ◽  
Acid Mist

Modern combustion steam-electric plants are designed to recover as much heat as economically feasible from the combustion products. As a part of the continuing effort by utilities to increase plant efficiency, extracting low quality heat from the flue gas stream prior to discharge through the stack to the environment has become economically attractive. “Economic feasibility” is strongly dependent on the cost of the fuel as well as quality of the heat recovered. The economic feasibility of deploying low-temperature economizers to cool flue gas from coal-fired steam-electric plants to a temperature well below the sulfuric acid mist dew point is not commonly practiced but could have a number of salutary effects on unit operations including reduction in fuel use, reduction in water, reduction in fly ash resistivity upstream of cold-side electrostatic precipitators and enhanced mercury oxidation/capture. Using a theoretical 600 MW (nominal) coal fired facility an additional 30.8 MW of electrical output is available with the installation of a Low Temperature Economizer. This represents a 1% improvement in the plant heat rate with an attractive payback period. The components required for this heat recovery sub-system are readily available and the technology has matured to a point where uncertainties are minimized. In addition to improving the operation of the plant, Low Temperature Economizer can reduce emissions of SOx, NOx, Hg, PM and CO2. In a difficult regulatory environment reducing emissions while increasing plant performance is extremely beneficial. Furthermore Low Temperature Economizer lowers the volume of scrubber water required. Cooling the flue gas leaving the air heater below the acid mist dew point is not commonly practiced. The corrosion potential of the condensed sulfuric acid is a major materials selection/maintenance challenge as is the potential for gas-side fouling of the heat exchange surface with fly ash.

scholarly journals Greenhouse Energy Conservation: Analysis of Alternative Glass Systems

1983 ◽  
Vol 12 (1) ◽  
pp. 27-31
Author(s):  
John W. White ◽  
James G. Beierlein ◽  
Peter A. Dalke
Keyword(s):  
Energy Conservation ◽  
Energy Savings ◽  
Minimum Energy ◽  
Economic Feasibility ◽  
Rate Of Return ◽  
Economic Viability ◽  
Internal Rate Of Return ◽  
Conservation Analysis ◽  
Internal Rate ◽  
Need To Evaluate

The economic viability of nine representative energy conservation options for Pennsylvania greenhouse operators is examined. The analysis is done using an Internal Rate of Return procedure for four major fuels under three price escalator assumptions. The minimum energy savings per square foot per year is also calculated for each option. Wide variation is found in the economic feasibility of these options with the ones with the lowest installation costs generally providing the greatest IRR and the lowest required minimum savings per year. The results clearly indicate the need to evaluate carefully the econcmic viability of such investments beforehand.

Review of flue gas acid dew-point and related low temperature corrosion

2020 ◽  
Vol 93 (4) ◽  
pp. 1666-1677 ◽  
Author(s):  
Wujun Zuo ◽  
Xiaoyu Zhang ◽  
Yuzhong Li
Keyword(s):  
Low Temperature ◽  
Flue Gas ◽  
Dew Point

Reduction of Pollutant Emissions From Industrial Boilers by Combustion Modification

1977 ◽  
Vol 99 (3) ◽  
pp. 320-328 ◽  
Author(s):  
G. A. Cato ◽  
R. E. Hall ◽  
L. J. Muzio
Keyword(s):  
Flue Gas ◽  
Pollutant Emissions ◽  
Particulate Emissions ◽  
Test Program ◽  
Utility Boilers ◽  
Boiler Efficiency ◽  
Before And After ◽  
Particulate Size ◽  
Oil And Natural Gas ◽  
Industrial Boilers

The use of combustion modification has enabled many utility boilers to meet the emission standards for NOx. Its usefulness in reducing NOx emissions from industrial boilers (ranging from 11 GJ/hr to 528 GJ/hr) has been investigated during a recently completed field test program. The gaseous and particulate emissions from coal, oil, and natural-gas fuels were measured both before and after the combustion modification. Data were taken on particulate size as well as concentration. The principal combustion modification methods that were investigated included reduced excess combustion air, staged combustion air, recirculated flue gas, tuned burners, and reset burner registers. Staging was implemented by the use of overfire air ports or by turning off the fuel to some burners and increasing the fuel to others, thus creating zones of fuel-rich combustion. All of the combustion modification methods were effective to varying degrees in reducing the nitrogen oxides emissions, and reductions of as much as 50 percent were obtained with several of the modifications. In most instances the boiler efficiency was not degraded, although the particulate emissions increased by up to 50 percent in some cases. There was no substantive effect on the other pollutant emissions that were measured.

Flue-Gas Versus Fuel-Injection Recirculation: Effects on Structure and Pollutant Emissions

2005 ◽  
Author(s):  
Ala R. Qubbaj
Keyword(s):  
Flue Gas ◽  
Fuel Injection ◽  
No Reduction ◽  
The Other ◽  
Pollutant Emissions ◽  
Air Stream ◽  
Baseline Case ◽  
Co Reduction ◽  
Air Diffusion ◽  
Fuel Stream

In this study, a co-flow methane/air diffusion flame at Reynolds number of 6000 was numerically simulated. The co-flow air and fuel streams were diluted with Nitrogen in the range of 0% to 20%. The thermal and composition fields in the far-burner reaction zone (close to the exhaust) were computed, and the effects of diluent’s addition to the air stream (simulating FGR) and to the fuel stream (simulating FIR) were investigated. The results show that air-side dilution is very effective up to 5% diluent’s addition. For which, 95% and 65% drops in NO and CO emissions, respectively, along with a 16% increase in temperature, are predicted compared to the baseline case (0% dilution). However, beyond 5% dilution, no effect (reaction) has been predicted. On the other hand, the fuel-side dilution has shown an effect for all simulated diluent’s addition (i.e. 0%–20%). However, that effect is not systematic neither on temperature, CO or NO concentrations. For a similar 5% dilution to the fuel-side, a 14% increase in NO and a 97% decrease in CO are predicted, along with a 5.6% increase in temperature. The simulated results revealed that air-side dilution (simulating FGR) has a dramatic greater effectiveness in NO reduction, whereas, fuel-side dilution (simulating FIR) has a greater effectiveness in CO reduction. Besides, the results suggest an important role for Prompt-NO Fenimore mechanism.

scholarly journals Evaluating the Potential for Combustion of Biofuels in Grate Furnaces

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1951 ◽  
Author(s):  
Małgorzata Wzorek
Keyword(s):  
Sewage Sludge ◽  
Combustion Process ◽  
Pollutant Emissions ◽  
Biomass Combustion ◽  
Municipal Sewage Sludge ◽  
Hard Coal ◽  
Meat And Bone Meal ◽  
Bone Meal ◽  
Coal Slime ◽  
The Impact

The paper assesses the impact of combustion of biofuels produced based on municipal sewage sludge in stoker-fired boilers on the amount of pollutant emissions and examines the tendency of ash deposition of biofuels formed during the combustion process. The combustion tests were performed in a laboratory system enabling simulation of a combustion process present in stoker-fired boilers. The study was conducted for three types of biofuels; i.e., fuel from sewage sludge and coal slime (PBS fuel), sewage sludge and meat and bone meal (PBM fuel) and fuel based on sewage sludge and sawdust (PBT) with particle size of 35 mm and 15 mm. This paper describes and compares the combustion process of biofuels with different granulation and composition and presents the results of changes in emission values of NOx, SO2, CO, and CO2. The emission results were compared with the corresponding results obtained during combustion of hard coal. The results showed that biofuels with lower particle sizes were ignited faster and the shortest ignition time is achieved for fuel based on sewage sludge and coal slime-PBS fuel. Also, the highest NO and SO2 emissions were obtained for PBS fuel. During the combustion of fuel based on sewage sludge and meat and bone meal (PBM), on the other hand, the highest CO2 emissions were observed for both granulations. Biofuels from sludge show a combustion process that is different compared to the one for hard coal. The problems of ash fouling, slagging, and deposition during biofuels combustion were also identified. The tendency for ash slagging and fouling is observed, especially for fuel from sewage sludge and meat and bone meal (PBM) and fuel based on sewage sludge and sawdust (PBT) ashes which consist of meat and bone meal and sawdust which is typical for biomass combustion.

Design Study of Part-Flow Evaporative Gas Turbine Cycles: Performance and Equipment Sizing—Part II: Industrial Core

2002 ◽  
Vol 125 (1) ◽  
pp. 216-227 ◽  
Author(s):  
N. D. A˚gren ◽  
M. O. J. Westermark
Keyword(s):  
Interest Rates ◽  
Gas Turbine ◽  
Flue Gas ◽  
High Efficiency ◽  
Compressed Air ◽  
Column Height ◽  
Process Data ◽  
Detailed Model ◽  
Testing Stage ◽  
Calculation Results

This is Part II of a two-part paper and presents calculation results of a part-flow EvGT cycle based on gas turbine data for the ABB GTX100 (modified for intercooling). The evaporative gas turbine cycle is a new high-efficiency cycle that has reached the pilot testing stage. This paper presents calculation results of a new humidification strategy based on part-flow humidification. This strategy involves using only a fraction of the compressed air for humidification. Thermodynamically, it can be shown that not all the air needs to be passed through the humidification system to attain the intrinsic good flue gas heat recovery of an EvGT cycle. The presented system also includes live steam production and superheating, by heat from the hottest flue gas region, for injection. The humidifier then only uses the lower temperature levels, where it is best suited. The analyzed system is based on data for the ABB GTX100.gas turbine in intercooled mode. Part I of this two-part paper presents the results based on data for the aeroderovative Rolls Royce Trent. Simulation results include electric efficiency and other process data as function of degree of part flow. A detailed model of the humidifier is used, which produces sizing results both for column height and diameter. Paper I includes detailed description of the modeling. For the GTX100 system, full-flow humidification generates an electric efficiency of 52.6% (simple cycle 36.2%). The efficiency is virtually unaffected if the air portion to humidification is cut to 60% of accessible compressor air (represents 48% of compressor intake). If 30% of air from the compressor after cooling bleed (24% of intake) is led to the humidifier, the efficiency is reduced to 52.2%. On the other hand is the total heat exchanger area reduced by 20% and column volume by 50%. This calls for a recommendation not to use all the compressed air for humidification. It is recommended to use 15–30% of compressor intake air. The exact economic optimum depends on local fuel prices, CO2 taxes, interest rates, etc.

Cost comparison of seismic damage resisting systems for modules in multi-storey buildings

2019 ◽  
Vol 17 (2) ◽  
pp. 330-346
Author(s):  
Danielle Ashcroft ◽  
Temitope Egbelakin ◽  
John Jing ◽  
Eziaku Onyeizu Rasheed
Keyword(s):  
New Zealand ◽  
Modular Design ◽  
Base Isolation ◽  
Seismic Damage ◽  
Economic Feasibility ◽  
Cost Comparison ◽  
Economic Viability ◽  
Friction Damper ◽  
Content Type ◽  
Study Approach

Purpose The purpose of this paper is to examine the economic viability of a new and innovative seismic damage resisting system (SDRS) device by conducting a feasibility study. The SDRS device has been patented and specifically designed to be implemented in multi-storey modular buildings in seismic regions such as New Zealand. Design/methodology/approach Using a case study approach, two sample modular multi-storey buildings were purposively selected for the study. A cost-comparison analysis was conducted using the SDRS device in the two buildings, by carrying out a measure and price exercise of the construction elements. Findings The research results showed that the SDRS device is an economically viable option for mitigating seismic damage in modular multi-storey buildings in New Zealand. There is an average of 7.34 per cent of cost reduction when SDRS is used in modular multi-storey buildings when compared to other seismic resistance systems such as base isolation, moment resisting frames and friction damper systems. Practical implications The economic viability of the SDRS presents an opportunity for its usage in modular design and construction of multi-storey buildings. SDRS system is also applicable to other building typologies and construction methods. The use of SDRS also aligns with the current national objective to provide more affordable and resilient housing within a limited time; the opportunity is considered significant in New Zealand, including for export and manufacturing. Originality/value The confirmation of the SDRS device’s economic feasibility is the original contribution of the authors.

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