High mercury emission (both forms: Hg0 and Hg2+) from the wet scrubber in a full-scale lignite-fired power plant

The paper describes and discusses the results of research on mercury behaviour, especially its high emission, in both forms: elemental (Hg-0) and oxidised (Hg2+) from the wet flue gas desulphurisation scrubber (WFGD) in a lignite-fired power plant located in central Europe. The presented results involve the collection of lignite power plant samples (liquid, solid, gas) and different laboratory chemical analyses to try to understand the mechanism of mercury re-emission from the wet flue gas desulfurization system. It was noted that 67-80% of the total inlet mercury concentration left the WFGD scrubber. Moreover, the oxidised form of mercury was the main emitted form (about 60-70% of the total mercury concentration). The results show that mercury was found in very high concentration (10 mu g/g) (range: ppm) in the WFGD solid by-products, whereas the liquid phase contained only 1 mu g//l (range: ppb). Considering literature reports and presented data from the investigated power station, we believe that iron (Fe), which occurs in very high concentrations in solid WFGD samples (1.81% wt. Fe) and lignite (up to 20 g/kg Fe) is mainly responsible for disrupting the mercury absorption in the scrubber, the partitioning of the mercury between phases and leads to its reemission. Moreover, we believe also that a relatively high iodine ion concentration (130 mg/l) in the limestone slurry leads to mercury emission in its oxidised form, mainly as Hgl(2), which is highly volatile. Other minor components from limestone dissolution such as Mn, Al and Mg may additionally enhance that "complex" mercury behaviour.Web of Science270art. no. 11749

Current status of carbon capture, utilization, and storage technologies in the global economy: A survey of technical assessment

The latest tremendously rapid expansion of the energy and industrial sector has led to a sharp increase in stationary sources of CO2. Consequently, a lot of concerns have been raised about the prevention of global warming and the achievement of climate mitigation strategies by 2050 with a low-carbon and sustainable future. In view of this, the current state of various aspects of carbon capture, utilization, and storage (CCUS) technologies in general technical assessment were concisely reviewed and discussed. We concentrated on precisely identifying the technology readiness level (TRL), which is beneficial to specifically defining the maturity for each key element of the CCUS system with a commercialization direction paths. In addition, we especially presented and emphasized the importance of CO2\ua0capture types from flue gases and CO2\ua0separation methods. Then, we determined valuable data from the largest R&D projects at various scales. This paper provides a critical review of the literature related to challenges of the CCUS system that must be overcome to raise many low TRL technologies and facilitate their implementation on a commercial scale. Finally, our work aims to guide the further scaling up and establishment of worldwide CO2\ua0emission reduction projects

CFD model of SNCR with shifting effect of CO

The paper deals with CFD simulation of SNCR technology with implemented CO temperature shift. The influence of CO on the SNCR process is described by empirical adjustment of kinetics parameters of chemical reactions. Results of CFD simulation were compared with results of experimental measurements. Although the proposed kinetics model of SNCR technology is simplified, it is able to describe reduction of NOx and other phenomena of SNCR with good precision. The model can be used to verify of injection levels and injection lances arrangement at design phase.Web of Science2012210

Influence of ammonia on wet-limestone flue gas desulfurization process from coal-based power plant

The paper presents data concerning the influence of ammonia on wet flue gas desulfurization (WFGD) absorber. Paper presents preliminary results of an industrial scale study on WFGD absorber, that collects flue gases from four boilers with total flue gas flow capacity of the WFGD equal to 1 500 000 Nm3/h. Each boiler is equipped with selective non-catalytic reduction (SNCR) with urea injection. It was shown, that ammonia present in the flue gas upstream the WFGD increases the pH of absorption slurry, impacting the desulphurization process. In addition, analysis of particulate matter upstream and downstream the absorber shows an increase of the concentration of ammonium species in the particulate matter about 14 times, as average. Moreover, a non-optimized denitrification process can cause a high NH4+ concentration in the absorption slurry (up to 768 mg/L) and raw wastewater (up to 891 mg/L)

Wastewater management in a closed cooling system of professional power plant

The paper presents a mathematical model describing the changes in SO42- concentration in a closed system of cooling water in a professional power plant. The analyzed installation consists of condensers and cooling towers connected by a system of channels. The main mechanism of heat transfer in the cooling tower bases on partial evaporation of water, resulting in the increase of concentration of SO42- ions in the circulating liquid. The only mechanism to decrease concentration of undesirable chemicals in the circulating water is its periodic discharge to a wastewater treatment. According to the latest Polish Government Regulations (Regulation of the Ministry of Environment dated 18 November 2014) and the Directive of the European Parliament and of the Council (2010/75/EU of 24 November 2010 on industrial emissions) from the beginning of 2016 the new limits on the chemical components of a wastewater led to the natural tanks has been accepted, what forced planned and cost-effective wastewater treatment in a professional power plants. Presented mathematical model has an analytical solution which allows not only to predict daily changes of SO42- concentration in circulating water but also to indicate asymptotic concentration of sulphate ions under given working parameters of the system and to calculate minimal volumetric flow rate of wastewater required to keep the SO42- concentration below legal value.W pracy przedstawiono model matematyczny opisujący zmianę stężenia jonów siarczanowych SO42- w zamkniętym obiegu wody chłodzącej bloku energetycznego. Analizowana instalacja obejmuje: skraplacze bloków energetycznych oraz chłodnie kominowe połączone systemem kanałów ssących i kolektorów tłocznych. Głównym mechanizmem wymiany ciepła w chłodni jest częściowe odparowanie przepływającej przez nią wody, co powoduje jednak wzrost stężeń związków chemicznych w cyrkulującej cieczy i wymusza okresowy zrzut części wody do przyzakładowej oczyszczalni ścieków. Zgodnie z najnowszymi rozporządzeniami prawnymi: Rozporządzeniem Ministra Środowiska z dnia 18 listopada 2014 roku oraz dyrektywą Parlamentu Europejskiego i Rady 2010/75/UE z dnia 24 listopada 2010 r. w sprawie emisji przemysłowych, od początku roku 2016 obowiązują nowe limity dotyczące składu chemicznego ścieków technologicznych kierowanych do zbiorników naturalnych, które wymuszają planową i oszczędną gospodarkę wodnościekową elektrowni. Prezentowany model matematyczny posiada analityczne rozwiązanie pozwalające nie tylko przewidzieć dobowe zmiany stężeń siarczanów w cyrkulującej wodzie, ale również określić graniczne stężenie jonów siarczanowych dla bieżących parametrów pracy układu oraz wyznaczyć minimalny strumień odprowadzanych ścieków zapewniający spełnienie norm emisji ścieków przemysłowych.Web of Science19645

Syngas Quality as a Key Factor in the Design of an Energy-Efficient Pyrolysis Plant for Scrap Tyres

In 2016 4.94 million tonnes of tyres were produced. Each tyre eventually become waste and pyrolysis has been considered an effective way of utilizing scrap tyres for several decades. However, pyrolysis has failed many times because the process has a great energy demand and the quality of products is unstable or insufficient for commercial use. Usually plants are focused on the production of pyrolytic oil or char and the gaseous phase is only a by-product. In this paper the importance of composition and quality of pyrolytic gas is emphasized. The main chemical properties make this gas a valuable biofuel that may satisfy energy requirements of the whole process (except for the start-up phase). Available data from literature concerning composition and other features of the pyrolytic gas from scrap tyres obtained at temperatures up to 1000 °C are compared with experimental results. The quality of evolved gases is discussed in the context of the Industrial Emissions Directive (IED), too. Finally, an analysis of the mass balances obtained allows a decision about the business profile and profitability

Experimental investigation of waste tyres pyrolysis gas desulfurization through absorption in alkanolamines solutions

Copyright © 2022 The Authors. Pyrolysis of waste tyres produces harmful hydrogen sulfide and other mercaptan compounds as by-products. The current study is concerned with the purification of hydrogen-rich pyrolysis gas from hydrogen sulfide gas that is present in a great amount (up to 5.1% mol at 420 °C), and mercaptans that are also problematic impurities. The method proposed is absorption by alkanolamines which is one of the most economical methods applied in natural gas sweetening. However, it has not been adopted in waste tyre pyrolysis gas purification yet. Two organic absorbents were tested, diethanolamine (DEA), N-methyldiethanolamine (MDEA) as well as theirs blends, at various concentrations. The application of 30 wt% DEA in water reduced H2S emission by 98%. In turn, 40 wt% MDEA aqueous solutions reduced H2S emission by 97%. The best results were produced when 30 wt% DEA was mixed with 40 wt% of MDEA (1:1 vol ratio) which allowed a removal of 99% of H2S from the pyrolysis gas. Moreover, the maximum H2S emission was 7 ppm, and a level below 5 ppm was kept for 99% of experiments duration. Finally, the application of this mixture also reduced significantly the concentrations of other sulfur-containing compounds such as methyl mercaptan and carbonyl sulfide (a minimum of 98%), ethyl mercaptan (∼90%), and carbon disulphide (by more than 99%). Thus, aqueous solvent mixture of 30 wt% DEA with 40 wt% of MDEA (1:1 v/v) can be recommended as a potential desulfurization method for waste tyres pyrolysis gas.Department of Air Conditioning, Heating, Gas Engineering and Air Protection; Wroclaw University of Science and Technology (No. 8211204601 - N_RRB_PODST_BAD_ EXP_BAM)

Hydrothermal carbonisation of sewage sludge and resulting biofuels as a sustainable energy source

Sewage sludge is nowadays a permanent element of our lives. One promising idea is to turn these wastes into fuels. Special scientific attention is given to the possibility of applying the low temperature thermochemical method commonly referred to as hydrothermal carbonisation (HTC) in the context of sewage sludge (SS) utilisation. While many scientist suggest the use of HTC products in agriculture, this review focuses on the energetic use of HTC products as solid fuels and co-substrates in the anaerobic digestion (AD) process of a biogas plant. HTC is a very promising technology, however, a potential barrier to its implementation may be the lack of authoritative data on long-term economic and environmental benefits and the legal restrictions associated with the further use of the products. In addition, incomplete knowledge in the field of subcritical water effects on the complex and irregular structure of SS may not provide a guarantee for the appropriate application of this method. This article attempts to systematise the information, insights and research deficiencies related to the HTC process of various forms of sludge towards the energetic possibilities of using the products obtained

Mercury removal and its fate in oxidant enhanced wet flue gas desulphurization slurry

Mercury is a toxic heavy metal that, once emitted or released, persists in the environment and circulates between air, water, sediments, soil and living creatures. Therefore, international governments and other authorities are taking measures to control mercury emissions from various sources. Despite many efforts, mercury remains a problematic pollutant in coal-fired installations in regards to differentiation of existing forms and their behavior in flue gas stream and purification units. Scientists try to understand its behavior in the flue gas and to capture it in one place, employing processes of adsorption, absorption, membranes or different catalysis. At the same time, researchers are also developing efficient and economically feasible technologies for mercury control. One such technology involves the capture of mercury in flue gases via gas-cleaning units through co-benefit application. Examples include, for instance, carbon injection in ESP, catalytic conversion in SCR unit, and absorption in a wet desulfurization scrubber. This paper outlines a mercury capture method developed in American and Polish laboratories and will present the pilot-scale research with emphasize on the mercury behavior in the slurry with and without any added reagents.Web of Science21188287

Characteristic of mercury on the surface of ash originating from electrostatic precipitators of lignite and bituminous coal-fired power plants

Mercury concentrations in ash taken from electrostatic precipitations (ESPs) installed in bituminous coal and lignite power plants have been analyzed by the X-ray fluorescence (XRF) method and leaching test supported by detailed coal and ash compositions' analyses, surface scans and particles size distribution studies. The results showed that mercury was present on the surface of ash particles. Its concentration decreased upon increasing size of ash particles. Leaching tests showed that only small part of mercury was removed with water which suggests the fact that it occurred mostly in the form of insoluble compounds such as Hg, HgO, HgS and Hg2Cl2. There existed ash particles of the diameters from 50 to 60 gm, characterizing by the maximum capability to adsorb mercury and its compounds. The authors suggest that metals like copper and lead formed ash active centers that were preferably occupied by molecules containing atoms of mercury. It was highly possible to expect that content of these elements in ash would have a significant effect on sorption of mercury from combustion gases.Web of Science454594