Flue Gas Treatment Technology Research Articles

Application of a microalga, Tetradesmus obliquus PF3, for NO and CO2 removal from actual flue gas via cultivating in wastewater.

Greenhouse gas (GHG) emissions, particularly anthropogenic emissions, are the primary drivers of climate change. The cultivation of microalgae represents a highly promising strategy for mitigating atmospheric GHG levels. The growth characteristics and GHG mitigation capabilities of Tetradesmus obliquus PF3 were investigated in domestic wastewater at a thermal power plant. The maximum cell density and productivity were 1.52 ± 0.01 g L-1 and 0.33 ± 0.01 g L-1 day-1, respectively. Utilizing a serial configuration of two reactors, the elimination efficiency of NO and CO2 attained values of 78 ± 4% and 14 ± 4%, respectively. NO concentration at the outlet was less than 24.6 ± 2.9 mg m-3, meeting the latest Chinese discharge limits. Besides, the recovery efficiency of NO and CO2 increased to 77 ± 8% and 2.24 ± 0.04%, respectively, compared to that of the single reactor (40 ± 3%, 0.9 ± 0.0%). A removal efficiency of over 90% was achieved for TN and TP in domestic wastewater. The concentrations of COD (76.5 mg L-1), NH4+-N (0.9 mg L-1), TN(6.31 mg L-1), and TP (0.35 mg L-1) in effluent were below the thresholds of 100 mg L-1, 25 mg L-1, none data, and 3 mg L-1, respectively, complying with the Chinese Discharge Standard (Class II criteria set forth) for Municipal Wastewater Treatment Plants Pollutants. The harvested biomass exhibited a high content of carbohydrates and proteins, making it a viable feedstock for biofuels and bio-fertilizers. Our results demonstrate that Tetradesmus obliquus PF3-based flue gas treatment technology can simultaneously realize GHG removal, wastewater bio-remediation, and biomass recovery.

Composition, characteristics, and treatment technologies of condensable particulate matter present in flue gas emitted by coking plants in China

To study the total particulate matter (TPM) in flue gas emitted by coking plants, a sampling system that could be used to collect filterable particulate matter (FPM) and condensable particulate matter (CPM) was designed and developed based on Method 202 recommended by the U.S. Environmental Protection Agency in 2017 and HJ 836-2017 issued by China. Using this system, FPM and CPM in flue gas emitted by four coking furnaces named A, B, C, and D were tested in China. Further, 9 water-soluble ions, 20 elements, and organic matter present in the CPM were simultaneously examined to determine their formation mechanisms. Statistical data suggested that the FPM emission level in the coking flue gas was low and the average mass concentration was less than 10 mg/m3. However, with high CPM and TPM emission levels, the TPM mass concentrations of A, B, C, and D were 130 ± 11.1, 84.4 ± 6.36, 35.1 ± 17.0, and 63.8 ± 13.0 mg/m3, respectively. The main component of TPM was CPM, and the average mass concentration of CPM accounted for 98%, 95%, 68%, and 95% of TPM in furnaces A, B, C, and D, respectively. Water-soluble ions were the important components of CPM, and the total concentration of water-soluble ions accounted for 70%, 87%, 42%, and 66% of CPM in furnaces A, B, C, and D, respectively. Toxic and harmful heavy metals, such as Mn, Cr, Ni, Cu, Zn, As, Cd, and Pb, were detected in CPM. The formation mechanism of CPM was analyzed in combination with flue-gas treatment. It was shown that the treatment process “activated carbon– flue-gas countercurrent-integrated purification technology + ammonia spraying” used in furnaces A and B was less effective in removing CPM, water-soluble ions, metals, and compounds than that of “selective catalytic reduction denitrification + limestone–gypsum wet desulfurization (spraying NaOH solution)” in furnaces C and D. Hence, different flue-gas treatment technologies and operation levels played vital roles in the formation, transformation, and removal of CPM from flue-gas. Organic components in CPM discharged from furnace A were determined via gas chromatography–mass spectrometry, and the top 15 organic components in CPM were obtained using the area normalization method. N-alkanes accounted for the highest proportion, followed by esters and phenols, and most of them were toxic and harmful to humans and ecosystems. Therefore, advanced CPM treatment technologies should be developed to reduce atmospheric PM2.5 and its precursors to improve ambient air quality in China.

A multi-criteria group decision making framework for sustainability evaluation of sintering flue gas treatment technologies in the iron and steel industry

The iron and steel industry (ISI) is at a critical stage of upgrading to ultra-low emission technologies in China. It is imperative to construct a life cycle sustainability evaluation framework as a guide for the selection of ultra-low emission technologies for the ISI. This research developed a novel multi-criteria group decision making framework. Four mature treatment technologies for sintering flue gas (SFG) were selected for analysis from an environmental, economic, and technological multi-dimensional perspective. The results of the life cycle assessment and life cycle costing are incorporated into the evaluation framework. The sustainability of ultra-low emission technologies was evaluated by combining Bayesian and hesitant fuzzy set theories for the first time. The results revealed that of the four alternatives considered, the most sustainable technology consists of semi-dry flue gas desulfurization, bag filter, and selective catalytic reduction denitrification. Triple sensitivity analysis and comparative analysis verified the consistency, robustness, and superiority of the proposed methodology. The interrelationship among criteria showed that technical maturity is key to enhancing the sustainability of ultra-low emission technologies, as it has a significant impact on costs and improves the environmental impact of the system. The conclusions provide optimization suggestions for further improving the sustainability of ultra-low emission technologies for SFG of ISI.

Technology development and cost analysis of multiple pollutant abatement for ultra-low emission coal-fired power plants in China

The implementation of ultra-low emission (ULE) limits (SO2: 35 mg/m3, NOx: 50 mg/m3, PM: 10 mg/m3) promoted the development of flue gas treatment technologies in China. Pollutant control technology development for Chinese coal-fired power plants was summarized and an analysis of the applicability and cost of pollutant control technologies was conducted. Detailed data were collected from 30 ultra-low emission coal-fired units across China. Based on a cost analysis model, the average unit power generation incremental costs were 0.0144 and 0.0095 CNY/(kW·hr) for SO2 and NOx control technologies, respectively. The unit power generation incremental cost of twin spray tower technology was 7.2% higher than that of dual-loop spray tower technology. The effect of key parameters on operating cost was analyzed. The unit power generation incremental cost increased because of increments in the electricity price for SO2 control technology and the price of the reductant in NOx control technology. With high sulfur content or NOx concentration, the unit power generation incremental cost caused by pollutant control increased, whereas the unit pollutant abatement cost decreased. However, the annual operating hours or load increased, thereby leading to a decline in unit power generation incremental cost and unit pollutant abatement cost.

Selective Catalytic Reduction System Ammonia Injection Control Based on Deep Deterministic Policy Reinforcement Learning

The control of flue gas emission in thermal power plants has been a topic of concern. Selective catalytic reduction technology has been widely used as an effective flue gas treatment technology. However, precisely controlling the amount of ammonia injected remains a challenge. Too much ammonia not only causes secondary pollution but also corrodes the reactor equipment, while too little ammonia does not effectively reduce the NOx content. In recent years, deep reinforcement learning has achieved better results than traditional methods in decision making and control, which provides new methods for better control of selective catalytic reduction systems. The purpose of this research is to design an intelligent controller using reinforcement learning technology, which can accurately control ammonia injection, and achieve higher denitrification effect and less secondary pollution. To train the deep reinforcement learning controller, a high-precision virtual denitration environment is first constructed. In order to make the virtual environment more realistic, this virtual environment was designed as a special structure with two decoders and a unique approach was used in fitting the virtual environment. A deep deterministic policy agent is used as an intelligent controller to control the amount of injected ammonia. To make the intelligent controller more stable, the actor-critic framework and the experience pool approach were adopted. The results show that the intelligent controller can control the emissions of nitrogen oxides and ammonia at the outlet of the reactor after training in virtual environment.

Environmental and economic impact assessment of three sintering flue gas treatment technologies in the iron and steel industry

Increasingly stringent pollutant emission standards pose a new challenge to the control of air pollutants in China's iron and steel industry (ISI). This study quantified and compared the environmental and economic effects of three typical sintering flue gas ultra-low emission treatment technologies in China's ISI, namely, semi-dry flue gas desulfurization + semi-dry flue gas denitration with O3 + bag filter (SSOB), wet flue gas desulfurization + wet electrostatic precipitator + selective catalytic reduction denitration (WWS), and semi-dry flue gas desulfurization + bag filter + selective catalytic reduction denitration (SBS) by conducting a life cycle assessment coupled with life cycle costing method. Using 1 ton of sinter as the functional unit and “cradle to gate” as the system boundary, the environmental impact of the three treatment technologies is 0.1822, 0.1298, and 0.117, respectively and the total economic cost is 11.622, 10.353, and 10.435 RMB, respectively. The ozone oxidation, semi-dry flue gas desulfurization (FGD), and semi-dry flue gas denitration processes are the key processes of SSOB with electricity, liquid oxygen, and sodium sulfite as key substances. Wet flue gas desulfurization process and selective catalytic reduction (SCR) denitration process are the key processes in WWS while electricity is the key substance. Semi-dry FGD and SCR denitration are the key processes in SBS, with electricity and lime as the key substances. SBS has optimal environmental performance, while WWS has lowest economic costs. Optimization suggestions for each technology are presented based on the influence degree of key processes. The research findings will be valuable for the selection and optimization of ultra-low emission technologies of ISI.

Treatment of Particulate Matter Pollution: People’s Attitude and Readiness to Act

Abstract The paper displays results of the questionnaire called “Particulate matter pollution in air”, which serves as a tool to determine level of public awareness of the health risks related to pollution from small capacity heating equipment in households. Barriers for installation of the innovative flue gas treatment technology called a fog unit in households and possible mechanisms to decrease or prevent these barriers were defined. The first part of the questionnaire included overall information about participants: age, gender, education level, place of residence, activities to protect the environment and motives behind performing these activities. The remaining questions were divided in four groups: “Environmental views”, “Knowledge on air pollution”, “Willingness to pay”, “Choice of flue gas treatment technologies”. The results of questionnaire correspond with raised problem situations. Over 80 % of respondents lack information on pollution and possible consequences deriving from it, and on potential solutions to prevent pollution. Residents of households are willing to pay for installation of flue gas treatment equipment (capital investments).

Innovative scrubber technology model for domestic boiler application

Many treatment technologies exist for particulate matter capture from the flue gas. Heat recovery from flue gases is a significant advantage of scrubber technology, which promotes energy efficiency increase of the combustion unit. The amount of recovered heat depends on heat and mass transfer in the scrubber. This paper presents the investigation of innovative small-scale flue gas treatment technology—fog unit. Households produce significant share of particulate matter in Europe. Therefore, there is a need to provide flue gas treatment technologies for domestic boilers in agreement with EU directive 2009/125/EC. Experimental research was done to identify the performance of proposed technology depending on inlet water flow rate, gas flow rate, water temperature, droplets diameter and water–gas flow ratio. The regression equations were developed based on performed data analysis. Equations can be used to predict the capacity of fog unit, outlet water temperature and outlet gas temperature.

Summary of Flue Gas Purification and Treatment Technology for Domestic Waste Incineration

Incineration technology is widely used in the world as a domestic waste treatment technology. The reason is that the incineration technology can reduce the weight of the treated domestic waste by 80% and the capacity by more than 90%, which is of great significance to the realization of the management goal of domestic waste treatment. However, the problem of flue gas pollution will occur when the waste incineration technology is used to treat the waste. The main harmful substances in the flue gas generated by waste incineration include: smoke, dioxin, SO2, NOx, heavy metal and other pollutants. Therefore, the flue gas can only be discharged into the atmosphere after proper technical treatment and meeting the national emission standards. This paper summarizes the domestic and foreign technologies of waste incineration flue gas purification and treatment, and puts forward suggestions for the development of domestic waste incineration flue gas purification and treatment technology.

Sprayed Water Flowrate, Temperature and Drop Size Effects on Small Capacity Flue Gas Condenser’s Performance

Abstract One of the main pollution types is air pollution, which has a significant impact on the surrounding environment and on living beings. Major source of air pollution is combustion processes. There are many flue gas treatment technologies around the world. In this paper a new, innovative flue gas treatment technology – fog unit – is introduced. The goal of the fog unit is to treat flue gases that are emitted from households. In the European Union, including Latvia, at the beginning of 2020, a directive will come into effect that will set limits for emissions and the effectiveness for incinerators in households. The main focus of this study was to determine the most optimal operating mode for the fog unit by changing different operating parameters: sprayed water temperature, sprayed water flowrate and types of nozzles (drop diameters). Results show that the most optimal operating mode in terms of flue gas treatment efficiency and recovered energy is at water temperature: 20 °C, sprayed water flowrate: 250 l/h and nozzle: MPL1.12 M. However, electrical consumption of water circulation pump leaves negative effect on this operating mode.

Optimal Flue Gas Treatment for Oxy-Combustion-Based Pulverized Coal Power Plants

Oxy-combustion is recognized as the cleanest technology which uses coal as an energy source. Flue gas clean-up is essential for sustainable operation. In this work, the optimal selection of the flue gas treatment technologies in oxy-combustion power plants is determined. A two-stage procedure combining heuristics and mathematical programming is used to evaluate the technologies involved including the boiler, denitrification, electrostatic precipitation, sulfur dioxide removal, and carbon capture. For plant operation, the coal feed has to be selected. An extended blending problem is solved to evaluate the coal type to be purchased based on its cost and composition. The optimal flue gas processing consists of electrostatic precipitation, followed by dry SO2 removal, and CO2 purification using zeolites. No specific denitrification method is required due to the low concentration levels of NOx generated in oxy-combustion. This flowsheet is used to select one among a mixture of three different types of coal: national, imported, and crude coal tar. However, no mixture is recommended as crude coal tar was the one selected. Even though the processing costs are higher, it is outweighed by the lower cost of the raw material.

The economics of numbering up a chemical process enterprise

Chemical‐processing plants that can be numbered up by installing and operating many replicate facilities are economically and technically well suited for the conversion of geographically distributed sources of renewable or waste carbon into fuels or chemicals. Examples from the manufacture of chemicals and the installation of flue gas treatment technology suggest that the relative cost diminution should correlate through a power law (Cost/Cost1 ∝ E −a) with E, a measure of the experience of operating those facilities and/or the number of units that are mass manufactured and installed. The exponent, a, can be related to the complexity of the process and the characteristics of the products.

Flue Gas Treatment Technology that Contribute to the Reduction of LCC of Municipal Solid Waste Incineration

Flue Gas Treatment Technology that Contribute to the Reduction of LCC of Municipal Solid Waste Incineration

Experimental and analytical study of the flue gas condenser – fog unit

Abstract International organisations, unions and countries are taking part in reduction of pollutants from different sources by setting emission limits and boundary values for pollutants such as carbon dioxide, carbon monoxide, sulfur oxides, nitrogen oxides and particulate matter. According to EU Eco-design Directive each solid fuel household boiler technology has to include electric precipitator. A fog unit is a novel flue gas treatment technology made for small capacity combustion units. First experiments have been carried out in the fog unit experimental stand and results are analysed in detail. The capacity of the fog unit reached during experiments was between 1.02kW and 3.11kW, showing increase in efficiency from 5 to 15%. Data of experiments were used in a simulation (calculation) model, made for determination of fog unit capacity. Results of the model and experiments were compared and showed strong compatibility.

Example Application of LGGH High-efficiency Coal-fired Flue Gas Treatment Technology in Yudian Dabu Power Plant

This paper describes the severe air pollution and ultra-low emission process route in China today, based on which it studies and analyzes the LGGH high-efficiency coal-fired flue gas treatment technology applicable to the upgrading of the ultra-low emission with respect to its origin, composition, characteristics and advantages. Then this paper gives a case study on the application of this technology in Yudian Dabu Power Plant where ultra-low emission is required, in particular the project profile of Yudian Dabu Power Plant, and specific proposal, process layout, main design parameters, technical features and operating result of the technology in the power plant. According to the testing, after this technology is put into use in the plant, the dust and SO₃ emissions of Unit 2# chimney drop to 2.3mg/m³ and 2.4 mg/m³ respectively, much lower than the national ultra-low emission limits. All these can demonstrate that the large-scale coal-fired power units can achieve a significant result by adopting the optimized LGGH high-efficiency coal-fired flue gas treatment technology, this technology provides higher precipitation efficiency, energy conservation and emission reduction, and high-efficiency SO₃ removal, solves the problem of "Gypsum rain" and visual pollution, and realizes dry chimney discharge, indicating that this technology deserves promotion and has great potential to become a popular post-combustion flue gas treatment technology.

Laboratory research of the flue gas condenser – fog unit

International organizations, European Union, as well as countries on governmental levels are taking part in reduction of pollutants from different sources, including combustion equipment, by setting emission limits and boundary values for different pollutants such as carbon dioxide, carbon monoxide, sulfur oxides, nitrogen oxides and particulate matter. Each solid fuel household boiler technology has to include electric precipitator according to EU Eco-design Directive. A fog unit is a novel flue gas treatment technology made for small capacity combustion units. First experiments have been made in the fog unit experimental stand and results are analyzed in detail. The capacity of the fog unit reached during experiments was between 1.02 kW and 3.11 kW, showing efficiency from 5 % to 15 %.

Biological Sulfur Reduction To Generate H2S As a Reducing Agent To Achieve Simultaneous Catalytic Removal of SO2 and NO and Sulfur Recovery from Flue Gas.

The conventional flue gas treatment technologies require high capital investments and chemical costs, which limit their application in industrial sectors. This study developed a sulfur-cycling technology to integrate sulfide production by biological sulfur reduction and simultaneous catalytic desulfurization and denitrification with H2S (H2S-SCDD) for flue gas treatment and sulfur recovery. In a packed bed reactor, high-rate sulfide production (1.63 ± 0.16 kg S/m3-d) from biological sulfur reduction was achieved using organics in wastewater as electron donors at pH around 5.8. 93% of sulfide in wastewater was stripped out as H2Sg, which can be a low-cost reducing agent in the H2S-SCDD process. Over 90% of both SO2 and NO were removed by the H2S-SCDD process under the test conditions, resulting in the formation of sulfur. 88% of the input S (H2Sg and SO2) were recovered as octasulfur with high purity. Besides partial recycling to produce biogenic sulfide, excessive sulfur can be obtained as a sellable product. The integrated sulfur-cycling technology is a chemical-saving and even profitable solution to the flue gas treatment in industrial sectors with wastewater available.

Solid Particles as Nuclei for Aerosol Formation and Cause of Emissions – Results from the Post-combustion Capture Pilot Plant at Niederaussem

BASF, Linde and RWE Generation have continued the investigations on the formation mechanism of aerosol-based emissions as a part of their ongoing joint development programme at the post-combustion capture pilot plant at Niederaussem. This paper summarises the results of the testing programme under real power plant operating conditions regarding the impact of solid particles in the flue gas on the formation of emissions, the effects of a wet electrostatic precipitator and other flue gas treatment technologies.

A Review on Petroleum Refining and Petrochemical Processes with Special Emphasis on Catalysts and Flue Gas Treatment Technology

A Review on Petroleum Refining and Petrochemical Processes with Special Emphasis on Catalysts and Flue Gas Treatment Technology

Electron beam treatment of simulated marine diesel exhaust gases

Abstract The exhaust gases from marine diesel engines contain high SO2 and NOx concentration. The applicability of the electron beam flue gas treatment technology for purification of marine diesel exhaust gases containing high SO2 and NOx concentration gases was the main goal of this paper. The study was performed in the laboratory plant with NOx concentration up to 1700 ppmv and SO2 concentration up to 1000 ppmv. Such high NOx and SO2 concentrations were observed in the exhaust gases from marine high-power diesel engines fuelled with different heavy fuel oils. In the first part of study the simulated exhaust gases were irradiated by the electron beam from accelerator. The simultaneous removal of SO2 and NOx were obtained and their removal efficiencies strongly depend on irradiation dose and inlet NOx concentration. For NOx concentrations above 800 ppmv low removal efficiencies were obtained even if applied high doses. In the second part of study the irradiated gases were directed to the seawater scrubber for further purification. The scrubbing process enhances removal efficiencies of both pollutants. The SO2 removal efficiencies above 98.5% were obtained with irradiation dose greater than 5.3 kGy. For inlet NOx concentrations of 1700 ppmv the NOx removal efficiency about 51% was obtained with dose greater than 8.8 kGy. Methods for further increase of NOx removal efficiency are presented in the paper.