Flue Gas Flow Rate Research Articles

Oxidative removal of NO from flue gas using ultrasound, Mn2+/Fe2+ and heat coactivation of Oxone in an ultrasonic bubble reactor

A novel process about oxidative removal of NO from flue gas using ultrasound, Mn2+/Fe2+ and heat coactivation of Oxone in an ultrasonic bubble reactor was developed. The feasibility, main influencing factors, free radicals, products and mechanism of NO removal were studied. The results show that ultrasound enhances NO removal due to enhancement of mass transfer and chemical reactions (low-frequency ultrasound is more efficient than high-frequency). Removal of NO is enhanced at higher Mn2+/Fe2+ concentration, Oxone concentration, ultrasonic energy density, solution height, solution temperature or oxygen concentration, and is inhibited with the increase of NO concentration or flue gas flow rate. SO2 concentration and solution pH have a double effect on NO removal. Ultrasound, Mn2+/Fe2+ and heat coactivation system of Oxone has the highest free radical yield and NO removal efficiency. NO removal by oxidations of SO4−/OH radicals produced from ultrasound, Mn2+/Fe2+ and heat coactivation of Oxone is the main NO removal route. The effects of inorganic anions and particulate matters on NO removal, and simultaneous removal of SO2 and NO were also investigated.

Metal Scrap Preheating using Flue Gas Waste Heat

The implementation of solid scrap preheating furnaces in the metal industry, powered by waste heat, has been a subject of interest due to the economic and energy saving benefits. Metal holding furnaces, keeping metal in a liquid state before casting, are powered by natural gas burners. Flue gases exit the furnaces at temperatures higher than the melting temperature of the metal, and it carries a significant amount of exergy that is considered as losses. By directing hot flue gases from the holding furnace to a metal scrap preheating furnace, one can heat up solid-scrap profiles, which are to be remelted, before putting them in the melting furnace. Adding a preheating step will reduce the melting time required while saving energy. The aim of this study is to look at the effectiveness of heating sow profiles with hot flue gases and find the optimal design considerations for a preheating furnace. Turbulent fluid flow and heat transfer physics are coupled in a CFD model to predict the sow average and maximum temperature with time for specific flue gas flow rate.

Prospects of using equilibrium-based column models in dynamic process simulation of post-combustion CO2 capture for coal-fired power plant

This paper discusses the limitations and prospects of using equilibrium-based column models for the dynamic simulation of post-combustion CO2 capture processes. Based on their features, one of three available commercial process simulators was chosen for this study. A pilot plant configuration adopted from literature was modeled and simulated using this simulator. Simulation results were compared with plant data and with results using standard rate-based models as available in literature. Temperature profiles in columns and overall mass and energy balances were found to be similar to plant data; however, CO2 capture-rate, reboiler-duty, and rich-loading using the model were overestimated. A method of reduced stage efficiencies in the absorber was used, which improved performance prediction further with a maximum deviation of 5%. Further, this dynamic model was used to analyze the process subjected to variation in flue gas flow-rate with a similar trend of futuristic power plants by controlling either liquid to gas ratio or CO2 capture-rate. Controlling liquid to gas ratio provided more control over the reboiler-duty while controlling the capture-rate focused on maintaining a certain capture ratio. The advantages and disadvantages of both methods are discussed and based on that, the controlling capture ratio was found suitable for using while power plant works flexibly with stringent emission regulations.

Emission of greenhouse gases from waste incineration in Korea

Greenhouse gas (GHG) emission factors previously reported from various waste incineration plants have shown significant variations according to country-specific, plant-specific, and operational conditions. The purpose of this study is to estimate GHG emissions and emission factors at nine incineration facilities in Korea by measuring the GHG concentrations in the flue gas samples. The selected incineration plants had different operation systems (i.e., stoker, fluidized bed, moving grate, rotary kiln, and kiln & stoker), and different nitrogen oxide (NOx) removal systems (i.e., selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR)) to treat municipal solid waste (MSW), commercial solid waste (CSW), and specified waste (SW). The total mean emission factors for A and B facilities for MSW incineration were found to be 134 ± 17 kg CO2 ton−1, 88 ± 36 g CH4 ton−1, and 69 ± 16 g N2O ton−1, while those for CSW incineration were 22.56 g CH4 ton−1 and 259.76 g N2O ton−1, and for SW incineration emission factors were 2959 kg CO2 ton−1, 43.44 g CH4 ton−1 and 401.21 g N2O ton−1, respectively. Total emissions calculated using annual incineration for MSW were 3587 ton CO2-eq yr−1 for A facility and 11,082 ton CO2-eq yr−1 for B facility, while those of IPCC default values were 13,167 ton CO2-eq yr−1 for A facility and 32,916 ton CO2-eq yr−1, indicating that the emissions of IPCC default values were estimated higher than those of the plant-specific emission factors. The emission of CSW for C facility was 1403 ton CO2-eq yr−1, while those of SW for D to I facilities was 28,830 ton CO2-eq yr−1. The sensitivity analysis using a Monte Carlo simulation for GHG emission factors in MSW showed that the GHG concentrations have a greater impact than the incineration amount and flow rate of flue gas. For MSW incineration plants using the same stoker type in operation, the estimated emissions and emission factors of CH4 showed the opposite trend with those of NO2 when the NOx removal system was used, whereas there was no difference in CO2 emissions.

Postcombustion CO2 capture using diethylenetriamine (DETA) solvent in a pilot‐plant test bed compared to monoethanolamine (MEA) solvent

The performance of CO2 absorption into diethylenetriamine (DETA) solvent and CO2 desorption from rich DETA solvent were experimentally investigated in a lab‐scale CO2 capture test bed. And the results were compared with monoethanolamine (MEA) solvent, which is a standard solvent for CO2 capture in industry. Also, effects of solvent concentration, lean CO2 loading, lean solvent temperature, solvent flow rate and flue gas flow rate on the absorption performance of DETA and MEA solvent, and effects of lean CO2 loading and solvent flow rate on the regeneration performance of DETA and MEA solvent were studied. The results showed that DETA had a faster CO2 absorption rate and a higher CO2 cyclic capacity than MEA solvent. And to strip the same amount of CO2, DETA needed less regeneration energy than MEA solvent. In addition, the results also showed that key operating parameters of absorber and stripper had large effects on the performance of CO2 absorption and desorption. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1131–1138, 2017

Performance of 1,8-Diazabicyclo[5.4.0]undec-7-ene-Modified SBA-15 for Selective Adsorption of CO2

In this work, SBA-15-(DBU-X) was prepared by dipping 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) into the mesoporous channels of SBA-15 in an attempt to improve the CO2 adsorption. The synthesized SBA-15-(DBU-X) was characterized with scanning electron microscopy, thermogravimetric analysis, Brunauer–Emmett–Teller adsorption analysis, and other methods. Then the CO2 adsorption/desorption properties were investigated using a self-designed fixed-bed adsorption system. The results indicated that DBU could be loaded on the SBA-15 mesoporous molecular sieves effectively and that SBA-15-(DBU-X) had good adsorption capacity toward CO2. SBA-15-(DBU-X) had good thermal stability at temperatures below 140 °C. At room temperature, with increasing loading of DBU and total flow rate of simulated flue gas, the adsorption of CO2 on SBA-15-(DBU-X) had an increasing trend followed by a decrease. When the volume fraction ratio of CO2 and H2O was 1:1 in the simulated flue gas, SBA-15-(DBU-X) had an optimum capacity of CO2 adso...

Mercury emission characteristics of flue gases from two coal-fired power plants in Xinjiang, China

ABSTRACTThe forms of mercury in the wet flue gas desulfurization outlet flue gases from two generating units of coal-fired power plants in Xinjiang, using the standard Ontario Hydro Method Calculations of the mercury Ef and the estimation of mercury emissions were performed based on the monitoring results, flue gas flow rates, coal consumption, and lower heating values (LHVs). The concentrations of HgP, Hg2+, Hg°, total gaseous mercury, and total mercury in the flue gases were 0.07–0.20, 0.13–0.65, 1.16–1.19, 1.29–1.84, and 1.49–1.91 μg/Nm3, respectively, all of which were far below the emission limit of 30 μg/Nm3 specified in the national standard. The emission factors for HgP, Hg2+, Hg°, the total gaseous mercury, and the total mercury were 0.03–0.12, 0.08–0.23, 0.42–0.69, 0.65–0.76, and 0.68–0.89 mg/GJ, respectively. Mercury emissions were estimated by using the aforesaid data, and the results showed that the total mercury emissions from flue gases of power plants No. 1 and 2 were 14.5 and 19.4 kg/a, respectively. The total mercury concentrations in the flue gases from the coal-fired power plants in Xinjiang were much lower than those of coal-fired power plants in other regions of China, the United States, and Europe.

Removal of nitric oxide from flue gas using sulfate/hydroxyl radicals from activation of oxone with cobalt and high temperature

A simple and efficient method for removing NO from flue gas using sulfate and hydroxyl free radicals from activation of Oxone with cobalt and high temperature has been developed. A comparison of NO removal efficiencies and the yields of sulfate and hydroxyl free radicals in several reaction systems were carried out. Co2+ concentration, Oxone concentration, solution pH, flue gas flow rate, stirring rate, solution temperature, and NO inlet concentration were evaluated as the key factors impacting on NO removal efficiency. The highest removal efficiency of 94.9% for NO was achieved under optimal conditions. The sulfate and hydroxyl radicals as the major reactive species which are responsible for removing NO were determined using ESR spectrometer. The NO is finally oxidized to nitric acid through a series of redox reactions. The chemical reaction mechanism of NO removal has also been proposed. These results prove the feasibility of this new NO removal technology. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1013–1021, 2017

Selection and design of post-combustion CO2 capture process for 600 MW natural gas fueled thermal power plant based on operability

Post-combustion CO2 capture (PCC) plant for a typical 600 MW natural gas fueled thermal power plant was designed as a trade-off between operability and mitigation of the efficiency penalty. Two modified PCC plant configurations with low efficiency penalty were selected. The methodology for designing PCC plants was adapted by incorporating design constraints based on operability and the construction of absorbers. This was applied in sizing the equipment of the plants. Two configurations of absorbers were analyzed based on flue gas flow rate at full-load condition and at time-average of an assumed load variation of a power plant operating flexibly. It was found that the absorber designed at time-average load provided a reduction of approximately 4% in the purchased cost of absorbers. The performance of the designed plants under power plant load variation, flow maldistribution and variable capture ratio was analyzed using off-design condition simulations. The absorber designed at full-load condition was found to lead to lower reboiler duty in order to maintain a similar capture rate to that of the other absorber during part-load operation. Dynamic simulations of the plants with the existing control structure were performed under similar power plant load variations to confirm their operability, and suggestions for selecting one of them were presented.

Evaluation of lower heating value and elemental composition of bamboo using near infrared spectroscopy

This study was to optimize models using near infrared spectroscopy for evaluation of lower heating value, carbon, hydrogen, nitrogen, sulfur and oxygen content of bamboo. Partial least squares regression was performed using 80 samples of bamboo where 64 samples was randomly assigned for calibration and 16 samples for validation. The result was that lower heating value and element composition did not depend on circumference size. The models showed the coefficient of determination of validation set and ratio of standard error of prediction to standard deviation of reference value of 0.934 and 3.96 for lower heating value, 0.803 and 2.31 for carbon; 0.856 and 2.65 for hydrogen; 0.973 and 6.6 for nitrogen; 0.785 and 2.19 for sulfur and 0.522 and 1.46 for oxygen, respectively. Models for lower heating value, nitrogen and hydrogen content prediction provided the highest performance, which could be used for most application. The carbon and sulfur models were fair and oxygen model was poor. The result could be a guide for applying in bamboo trading as biomass, in design and operation control of energy conversion and in predicting flue gas flow rate, air requirement, and flue gas compositions in combustion, gasification or pyrolysis.

Power by waste heat recovery from low temperature industrial flue gas by Organic Flash Cycle (OFC) and transcritical-CO2 power cycle: A comparative study through combined thermodynamic and economic analysis

Both Organic flash cycle and transcritical CO2 power cycle (T-CO2 power cycle) allow cooling of hot flue gas stream to an appreciably lower temperature due to the absence of pinch limitation. In the present study, a combined thermodynamic and economic comparison is conducted between a T-CO2 power cycle and Organic flash cycles using R-245fa and R600 as the working fluids. It is observed that work output per kg of flue gas flow rate is slightly higher for the T-CO2 power cycle if the flue gas is allowed to cool to the corresponding lowest possible temperature in the Heat Recovery Unit (HRU). It is also observed that with maximum possible cooling of flue gas, minimum bare module costs (BMCs) for each kW power output of OFCs are somewhat higher compared to that of T-CO2 power cycle. Minimum BMCs for each kW output of OFCs can be reduced substantially by increasing terminal temperature difference at the low temperature end of the HRU. However, the increasing terminal temperature difference at the low temperature end of the HRU is having negligible effect on BMC ($/kW) of T-CO2 power cycle.

Experimental study on drying biomass particles in flue gas flow

This combination of high temperature exhaust gas generator, using straight flue gas drying experiment of biomass straw particle flow drying technology, which aent of the particles, flue gas temperature, flue gas flow rate and particle flow rate were obtained by controlling variables. The experimental results show that the effect of flue gas temperature and initial moisture content of the particles on drying efficiency is linear, and the optimal gas/solid ratio exist between the flue gas flow rate and the particle flow rate. The size of the impact is: particle flow rate> flue gas flow rate> flue gas temperature> initial moisture content of the particles.

Removal of arsenic from flue gas by using NaClO solution

An inexpensive process has been developed to remove arsenic from flue gas using NaClO solution. The various influencing factors, such as NaClO concentration, initial solution pH, reaction temperature, concentrations of O2, CO2, SO2 and NO in flue gas on the removal of arsenic were investigated experimentally at a self-made bubbling reactor, from which, the optimal experimental conditions were obtained with 1.0L/min of flue gas flow rate, 100mmol/L of NaClO solution, 6.0 of the solution pH and 60°C of reaction temperature. And the average removal efficiency was achieved at about 97.5%. HPLC-HG-AFS analyses of products proved that the main reaction product was AsO43−. Combined with the analysis of the electrode potentials, the mechanism of As2O3 reaction with NaClO solution was proposed.

Orthogonal test design to optimize the operating parameters of a hybrid solvent MEA–Methanol in an absorber column packed with three different packing: Sulzer BX500, Mellapale Y500 and Pall rings 16 × 16 for post-combustion CO2 capture

Effects of three important operating conditions (liquid flow rate, gas flow rate and regeneration temperature) on the CO2 capture and mass transfer performance of the absorption of CO2 into a hybrid solvent MEA–Methanol were studied in a pilot-plant absorber packed with three different packings consisting of Sulzer BX500, Mellapale Y500 and Pall rings 16 × 16 through orthogonal tests. CO2 absorption experiment was conducted under the optimal operating parameters of three packings achieved from the orthogonal experiments (liquid flow rate 30l/h, flue gas flow rate 3m3/h and regeneration temperature 74°C for Mellapale packing 500Y, liquid flow rate 40l/h, flue gas flow rate 3m3/h and regeneration temperature 74°C for Pall rings packing 16 × 16 and liquid flow rate 40l/h, flue gas flow rate 5m3/h and regeneration temperature 74°C for Sulzer packing BX500). The results showed that regeneration temperature was the most important factor affecting the CO2 capture efficiency and gas flow rate had little effect on the CO2 capture efficiency. In addition, the optimal operating conditions of the three packings were achieved in this study and Sulzer BX500 packing had the best mass transfer performance.

Effects of sintering flue gas properties on simultaneous removal of SO2 and NO by ammonia-Fe(II)EDTA absorption

The simultaneous removal of SO2 and NO from sintering flue gases can be realized by ammonia-Fe(II)EDTA absorption, which has become a hotspot for research. In order to get useful data for further industrialization, the practical operating conditions of the sintering plant were simulated and the experiments were performed to explore the effects of sintering flue gas flow rate, flue gas temperature, compulsory oxidation, SO2 and NO concentrations on the combined elimination of SO2 and NO in a pilot-scale reactor. According to the experimental results, it was not conducive to the absorption of NO when the flue gas flow rate, the oxidation air flow rate and the NO concentration increased. The impact of flue gas temperature on the removal of SO2 and NO was not obvious when the slurry temperature was constant. In addition, the SO2 concentration had little effect on the absorption of SO2 and NO.

Pilot plant study of aqueous solution of piperazine activated 2-amino-2-methyl-1-propanol for post combustion carbon dioxide capture

Piperazine (PIP) activated 2-amino-2-methyl-1-propanol (AMP) (28/17wt% AMP/PIP) was investigated in a PCC test facility on the power plant in Dürnrohr, Austria. Through the use of real power plant flue gas and the well-conceived dimensions of the test facility, industry-related conditions for full-scale applications can be assured. The specific energy consumption for solvent regeneration can be reduced to 3.15GJ/tCO2 (without absorber intercooler and multi-stage flash), resulting in an energy saving of 10% in comparison to 30wt% monoethanolamine (MEA). The optimal solvent flow rate is 38% lower in comparison to that of 30wt% MEA, resulting in less pumping demand. 28/17wt% AMP/PIP shows a good performance especially at high flue gas flow rates because of piperazinés fast kinetics. The fast kinetics also have a positive effect in the reduction of the absorber height. Halving the absorber height still allows a performance similar to that of 30wt% MEA. In contrast to the MEA-process, the energy demand remains constant when varying the desorber pressure.

NEURAL NETWORK MODELING OF THE SULFUR DIOXIDE REMOVAL BY ACTIVATED CARBON SORBENT

An artificial neural network (ANN) model of three-layers was advanced to predict the efficiency of the sulfur dioxide (SO2) removal from the flue gas stream (SO2+air) in a fixed bed reactor using granulated activated carbon sorbent. The experimental data were collected from varying six process variables, namely, initial SO2 concentration, reaction temperature, flue gas flow rate, sorbent particle size, bed height and reaction time. The data were used to create input-base information to train and test the NN strategy.  Back propagation algorithm with two hidden layers was used for training and tests the NN. The neural network predictions of SO2 removal efficiency agree with experimental data with the minimum mean squared error (MSE) for training and testing with values of 0.112*10-4 and 0.817*10-3, respectively.

Integration study of a hybrid solvent MEA-Methanol for post combustion carbon dioxide capture in packed bed absorption and regeneration columns

Abstract The present work reported tests of a new solvent 30 wt% MEA-Methanol compared to aqueous 30 wt% MEA solvent in a pilot-plant test bed, which comprises the complete absorption/desorption. The two solvents were studied in the same way in the test bed and detailed results were reported for both solvents. The measurements were carried out at a constant CO2 removal rate of 90% by an adjustment of the regeneration energy in the desorber for systematically varied L/G ratios, flue gas flow rate and absorber height. Results from these studies indicated that MEA-Methanol solvent had a faster CO2 absorption rate and a lower regeneration energy consumption compared to aqueous MEA solvent. Regeneration heat duty (Qreg) of MEA-Methanol solvent at optimum operating conditions was obviously lower than that of aqueous MEA solvent (3.22 MJ/kg CO2 and 4.04 MJ/kg CO2, respectively), which showed that MEA-Methanol had a potential to replace aqueous MEA solvent in industrial CO2 pilot plant.

Enhancement of microalgal biomass production and dissolved inorganic C fixation from actual coal flue gas by exogenous salicylic acid and 1-triacontanol growth promoters

Microalgae based bioenergy is a remarkable topic in renewable energy studies. Capturing and utilization of CO2 from actual coal emissions by bio-stimulated Chlorella sp. for energy conversion was investigated by enhancement of its growth and resistance to the stressful conditions by exogenous salicylic acid and 1-triacontanol growth promoters. The pH, flue gas flow rates, photoperiod and chlorophyll (a + b) concentrations were systematically studied. Actual coal combustion emissions were produced in a lab-scale combustor system. The increasing flue gas flow rates were examined from 2.4 vvm to 4.8 vvm and the highest biomass rates were obtained in the presence of highly toxic levels of coal emissions. Different photoperiod regimes were tested for flue gas utilization by autotrophic cultivation under flue gas stress. Chlorella sp. produced 0.86 g/L biomass at 2.4 vvm flow rate at 24:0 light:dark photoperiod. Chlorophyll (a + b) concentration was 1.054 μg/mL, Pmax was 0.047 g/L/d and μ was 0.112/d at these conditions. The study proved to be beneficial in understanding microalgae flue gas utilization process with growth stimulators in order to provide biomass production strategies.

Experimental study of a hybrid solvent MEA-Methanol for post-combustion CO 2 absorption in an absorber packed with three different packing: Sulzer BX500, Mellapale Y500, Pall rings 16 × 16

Abstract Effects of different operating conditions on the CO 2 capture and mass transfer performance of the absorption of CO 2 into a hybrid solvent MEA-Methanol were studied in a pilot-plant absorber packed with three different packing consist of Sulzer BX500, Mellapale Y500 and Pall rings 16 × 16. The results showed that the structured packing had an obvious advantage in the mass transfer performance. And Sulzer BX500 was better than Mellapale Y500 for it had a more uniform gas–liquid distribution on the packing surface. In addition, CO 2 lean loading, lean solvent temperature, lean solvent flow rate and flue gas flow rate all had great effects on the absorption performance of the MEA-Methanol absorption system.