Flue Gas Treatment Process Research Articles

Erosion and intergranular corrosion induced failure of S31254 stainless steel – Case study on Venturi scrubber in a natural gas purification plant

The flue gases such as SO2, SO3, and CO2 generated during the purification process of sulfur-containing natural gas need to be treated to a certain concentration before they can be discharged into the atmosphere. The flue gas unit of a purification plant in Sichuan adopts the new Cansolv flue gas treatment process. After running for a period of time, the Venturi scrubber experienced severe corrosion failure, resulting in equipment shutdown and significant economic losses. This paper utilizes an actual failed device as a case study to analyze the corrosion environment of the Venturi scrubber. It conducts a comprehensive failure analysis, encompassing material mechanical properties, metallographic analysis, and failure microstructure analysis, aiming to elucidate the reasons behind the Venturi scrubber failure. Systematic analysis shows that the manufacturing materials used in this scrubber meet all design requirements. However, flue gas at temperatures reaching 280 °C enters the scrubber tower at a flow rate exceeding 10 m/s. The dissolution of acidic gases leads to a significant drop in the pH of the cooling water to 1, manifesting evident signs of erosion corrosion and intergranular corrosion on the material surface. These observations suggest that erosion and intergranular corrosion in high-temperature acidic environments are the predominant factors contributing to the corrosion failure of the Venturi scrubber.

Specific resistance and adsorption performance of acid-modified fly ash for escaped ammonia in flue gas

Escaped ammonia emission following Selective Catalytic Reduction denitrification significantly influences subsequent flue gas treatment processes. This study investigates the adsorption capabilities of acid-modified fly ash concerning escaped ammonia (NH3) and its consequential impact on specific resistance. Furthermore, the adsorption mechanism of acid-modified fly ash on NH3 was explained. Acid activation facilitated the dissolution of a portion of Fe and Al constituents within the fly ash, the contents of Fe and Al in SFA decrease by 4.91% and 5.64%, respectively. In addition, the specific surface area and porosity of fly ash are obviously improved. The specific surface areas of HFA and SFA increased from 1.83 (OFA) to 4.69 and 7.71 m2/g, respectively. Adsorption kinetics adhered to the pseudo-first-order model. SFA showed the best adsorption performance, with NH3 adsorption up to 10.65 mg/g, which was 4.27 times higher than OFA. The creation of a surface liquid film during NH3 adsorption led to decreased specific resistance values across all fly ash samples after-adsorption. The highest specific resistance values recorded for original fly ash (OFA), hydrochloric acid-modified fly ash (HFA) and sulfuric acid-modified fly ash (SFA) were 6.21 × 1012, 3.37 × 1011 and 5.02 × 1010 Ω·cm, respectively. Sulfuric acid activation makes fly ash have stronger adsorption capacity for escaping ammonia, and SFA maintains good specific resistance characteristics, which has good application prospects in electrostatic precipitation and air pollution control.

Valorization of wipe wastes for the synthesis of microporous carbons and their application in CO2 capture, gas separation and H2-storage

Wipe wastes have been used as a cellulosic source to synthesize biochars. Prior to the synthesis of the adsorbents by the pyrolysis of wipes wastes, this waste was treated to remove the pathogenic agents. Then, the wipe wastes were pyrolyzed between 500 and 900 °C to obtain biochars, whose microporosity increased proportionally to the pyrolysis temperature, achieving a maximum CO2-adsorption uptake of 2.53 mmol/g at a pressure of 760 mm of Hg and 25 °C for the biochar pyrolized at 900 °C. The synthesized biochars are also highly selective towards CO2-adsorption in CO2/N2 or CO2/H2 mixtures. Hence, these adsorbents have shown a great potential to be used in flue gas treatment and H2-purification processes. Biochar treatment with KOH further improves microporosity due to chemical activation although the addition of a large amount of KOH leads to excessive microporosity causing a collapse in the pore structure and decreasing CO2-adsorption capacity.

Simulation and experimental research on trace detection of ammonia escape based on TDLAS

With the raising of NOX emission control standards, selective catalytic reduction (SCR) denitrification technology has been widely used in thermal power units·NH3 as a kind of important reducing agent, can reduce NOX to N2·NH3 escaped from the flue gas treatment process is directly discharged into the atmosphere, which will not only cause environmental pollution, but also block the catalyst and affect the performance of thermal power units. Therefore, the online monitoring technology for concentration of ammonia is significant. Considering the actual situations, absorption spectrum line around 970.9 cm−1 located in the mid-infrared for NH3 was selected for measurement simulation and experimental research based on TDLAS. The results show that the measuring system has good linear response, repeatability and stability, and the detection limit reached 8.3 and 30 ppbv (10–9), when the integral time was 30 and 1 s respectively, which is suitable for online monitoring of the concentration of ammonia.

Synergetic removal characteristics of mercury for ultra-low emission coal-fired power plant

The synergetic mercury removal by flue gas treatment process in coal-fired power plants is widely accepted, but there is a lack of a corresponding model to describe mercury transformations. In this work, a model for mercury transformations is established in a flue gas treatment process model using Aspen Plus. The concentrations, mass flow rates, and normalized emission factors of mercury, NOX, particulate matters (PM), and SO2 are investigated in a 660 MW coal-fired power plant. The mercury oxidation efficiency of the selective catalytic reduction (SCR) unit is 56.9 %. The mercury removal efficiency of the electrostatic precipitator (ESP) and wet flue gas desulphurization (WFGD) units are 53.5 % and 34.4 %, respectively. The ultra-low emission system achieves 63.3 % removal of mercury. Approximately 53.5 % of mercury is retained in the fly ash. The emission factor of mercury is 0.0131 mg/kWh and increases to 0.0265 mg/kWh when the load decreases from 100 % to 50 %. The emission factors of PM, SO2 and NOX are 7.1, 97.1, and 142.9 mg/kWh at full load, and 10.9, 97.4, 150.0 mg/kWh at 50 % load, respectively. The proposed flue gas treatment process model is considered a feasible approach for quantitative evaluation of multi-pollutants emissions at plant level.

Thermodynamics performance analysis of flue gas treatment process using ceramic membranes

Transport membrane condenser is a device for recovering water and heat from flue gas. Porous nature of ceramic membrane makes properties of water vapor condensation and fluid flow different from those in traditional heat exchangers. Therefore, irreversible losses caused by heat transfer and flow resistance of transport membrane condenser is also unique and worthy of studying. This paper uses entransy and entropy analysis methods to calculate irreversible losses of transport membrane condenser, and analyzes effects of fluid temperature on entransy dissipation and entropy generation rates. With the goal of reducing irreversible losses, operation mode and structure size of transport membrane condenser are optimized under designed conditions. Based on specific application cases, this paper finds that entropy analysis method has a certain limitations when studying irreversible losses of transport membrane condenser. The limitation is embodied in the analysis of heat transfer problems under the condition that fluid temperature changes significantly. Furthermore, an optimization method suitable for engineering design is proposed. According to theoretical results, flue gas inlet temperature is preferably in the temperature range of 52 °C–55 °C; under the condition that water balance of power plant is not destroyed, increasing flowrate of cooling water as much as possible.

Biofixation of Air Emissions and Biomass Valorization-Evaluation of Microalgal Biotechnology.

This research appraised the simultaneous biofixation, that is not quite common in scientific literature, of carbon dioxide (CO2) and nitric oxides (NOx) by microalgae species Chlorella vulgaris, Haematococcus pluvialis, and Scenedesmus subspicatus. The experimental design was established by five treatments with gas concentrations between control-0.04% of CO2, 5 to 15% of CO2, and 30 to 100ppm of NOx. Parameters such as pH, growth, productivity, lipids, protein, carbon/ nitrogen ratio, and astaxanthin were evaluated. For all species, the maximal growth and productivity were achieved with 5% of CO2 and 30ppm of NOx. Regarding protein content, for all the three species, better results were obtained at higher concentrations of CO2 and NOx. These results prove the microalgae capacity for CO2 and NOx biofixation and reuse of biomass as a source of high value-added products, such as lipids, proteins, and astaxanthin. These findings support the indication of these species for flue gas treatment process and use in biorefineries systems.

A novel strategy to reduce carbon emissions of heavy oil thermal recovery: Condensation heat transfer performance of flue gas-assisted steam flooding

• Flue gas-assisted steam flooding was investigated to reduce carbon emissions. • Flue gas-assisted steam flooding improved the oil recovery factor by 20.02%. • Flue gas treatment and injection processes for steam injection wells were designed. • Site application showed that the underground CO 2 storage rate was 74.5%. • The novel strategy is suitable for a small-scale steam generator used in oilfields. In this paper, the flue gas-assisted steam flooding process from a novel perspective of condensation heat transfer performance was investigated to reduce carbon emissions of heavy oil thermal recovery. More specifically, steam condensation heat transfer coefficients with and without flue gas were tested, and heat transfer and oil recovery for steam flooding assisted by flue gas in a sandpack were studied. The experimental results indicate that the existence of the gas film on the condensation block increased the heat transfer resistance and decreased the condensation heat transfer coefficient. The gas channeling of flue gas provided a flow path for the steam and promoted heat transfer deep into the sandpack. Flue gas-assisted steam flooding improved the oil recovery factor by 20.02% compared with steam flooding, and 46.4% of the injected flue gas could be stored in the sandpack. The storage of flue gas could be divided into two parts: the flue gas dissolved in the residual heavy oil and the flue gas trapped in the porous media. Flue gas treatment and injection processes for steam injection wells were designed. Site application of flue gas-assisted steam injection showed that the oil production increased by 28.3%, and the underground CO 2 storage rate was 74.5%. The novel strategy of flue gas treatment and injection with steam greatly reduces the carbon emissions of heavy oil thermal recovery, which is very applicable for small-scale steam generator used in oilfields.

Plasma technology to remove NOx from off-gases

Abstract Operation of marine diesel engines causes significant emission of sulphur and nitrogen oxides. It was noticed worldwide and the regulations concerning harmful emissions were introduced. There were several solutions elaborated; however, emission control for both SOx and NOx requires two distinctive processes realized in separated devices, which is problematic due to limited space on ship board and high overall costs. Therefore, the electron beam flue gas treatment (EBFGT) process was adopted to ensure the abatement of the problem of marine diesel off-gases. This novel solution combines two main processes: first the flue gas is irradiated with electron beam where NO and SO2 are oxidized; the second stage is wet scrubbing to remove both pollutants with high efficiency. Laboratory tests showed that this process could be effectively applied to remove SO2 and NOx from diesel engine off-gases. Different compositions of absorbing solution with three different oxidants (NaClO, NaClO2 and NaClO3) were tested. The highest NOx removal efficiency (>96%) was obtained when seawater-NaClO2-NaOH was used as scrubber solution at 10.9 kGy dose. The process was further tested in real maritime conditions at Riga shipyard, Latvia. More than 45% NOx was removed at a 5.5 kGy dose, corresponding to 4800 Nm3/h off-gases arising from ship emission. The operation of the plant was the first case of examination of the hybrid electron beam technology in real conditions. Taking into account the experiment conditions, good agreement was obtained with laboratory tests. The results obtained in Riga shipyard provided valuable information for the application of this technology for control of large cargo ship emission.

Oxygen transport membrane unit applied to oxy-combustion coal power plants: A thermodynamic assessment

The oxy-combustion process is one of the alternatives which have been evaluated to counteract the increase in CO2 emissions over recent years. This technology consists of a combustion process with oxygen instead of air, which facilitates the capture of CO2 after the flue gas treatment process. Nowadays, oxy-combustion has not been implemented full-scale because of the high energy and economic requirements of the air separation unit to provide oxygen to the process. This paper proposes to ion transport membranes as a replacement for the air separation unit in order to minimize their high energy penalty of the overall system power. In particular, this work presents four processes based on the oxygen-fired plant with an oxygen transport membrane unit. As benchmark cases used to quantify the energy penalties for CO2 capture, the correspondent air combustion process without CO2 capture and a cryogenic oxygen-fired process (Case1) were considered. The thermodynamic comparison between the proposal alternatives has been conducted through simulation models based on Aspen Plus tools. The net electric power and the net efficiency of electricity production have been used as key parameters, which have allowed achieving an optimal system design that provides reduces the power consumption related to separate oxygen from the air. As the results show, the oxygen transport membranes concept exhibits better net electrical efficiency (35.7% vs. 30.6%), lower efficiency drop (2.5% vs. 7.6%) and lower specific captured CO2 (986 gCO2/hkWnet vs. 1140 gCO2/hkWnet) compared to the cryogenic oxygen-fired process.

Potential copper plant Vanyukov furnace gas desulphurization capacity

To enable maximum disposal of Vanyukov furnace flue gas, the authors of this paper examined the spare capacity of the Elemental Sulphur Site at the Copper Plant of Nornickel’s Polar Division. Thus, the paper considers an optimized three-stage flue gas treatment process (which also includes a thermal reduction stage) and the possibility to skip the stage of preliminary condensation of sulphur from reduced gas. To estimate how it will affect the overall recovery of sulphur (desulphurization factor), a series of calculations was carried out to compare the Elemental Sulphur Site’s performance during two different treatment processes: a complete process that includes preliminary condensation of sulphur from thermally reduced gas; and a short process, i.e. without preliminary condensation of sulphur. In both cases, the concentration of sulphur dioxide in the Vanyukov furnace gas was [SO2] = 28 vol %. The results of the calculations were verified through experiments conducted on a pilot unit owned by Gipronikel Institute with the gas flow reaching ~1.2 nm3/h, and they confirm the possibility of implementing the three-stage treatment process using the available plant space and reaching the capacity of 40,000 nm3/h and the sulphur recovery of ~89 %. The obtained data on the specific consumption rates of natural gas, oxygen and boiler water can be used for a feasibility study to justify the adoption of the short treatment process at the Elemental Sulphur Site of the Copper Plant of Nornickel’s Polar Division.

New insights on mercury abatement and modeling in a full-scale municipal solid waste incineration flue gas treatment unit

Modeling approaches are generally used to describe mercury transformations in a single step of flue gas treatment processes. However, less attention has been given to the interactions between the different process stages. Accordingly, the mercury removal performance of a full-scale solid waste incineration plant, equipped with a dry flue gas treatment line was investigated using two complementary modeling strategies: a thermochemical equilibrium approach to study the mercury transformation mechanisms and speciation in the flue gas, and a kinetic approach to describe the mercury adsorption process. The modeling observations were then compared to real-operation full-scale data. Considering the typical flue gas composition of waste incineration facilities (high concentrations of HCl compared to Hg), it was found that a process temperature decrease results in better mercury removal efficiencies, associated with a higher oxidation extent of Hg in HgCl2, and the enhancement of the sorbent capacity. Improvements can also be attained by increasing the sorbent injection rate to the process, or the solid/gas separation cycles. An empirical correlation to predict the mercury removal efficiency from the main operating parameters of dry flue gas treatment units was proposed, representing a useful tool for waste incineration facilities. The presented modeling approach proved to be suitable to evaluate the behavior of full-scale gas treatment units, and properly select the most adequate adjustments in operating parameters, in order to respect the increasingly constraining mercury emissions regulations.

Experimental and Numerical Simulation Study on Co-Incineration of Solid and Liquid Wastes for Green Production of Pesticides

A large amount of solid and liquid waste is produced in pesticide production. It is necessary to adopt appropriate disposal processes to reduce pollutant emissions. A co-incineration scheme for mixing multi-component wastes in a rotary kiln was proposed for waste disposal from pesticide production. According to the daily output of solid and liquid wastes, the proportion of mixing was determined. An experiment of the co-incineration of solid and liquid wastes was established. Experimental results showed that the mixed waste could be completely disposed at 850 °C, and the residence time in the kiln exceeded 1 h. A model method for mixture and diesel oil-assisted combustion was proposed. Numerical simulation was performed to predict the granular motion and reveal the combustion interactions of the co-incineration of mixed wastes in the rotary kiln. Simulation results reproduced movements, such as rolling and cascading, and obtained the optimum rotational speed and diesel oil flow for the rotary kiln incineration operation. The simulation showed that the temperature in the kiln was maintained at 850 °C, and the mass fraction of CO and O2 at the outlet reached the standard for the complete combustion of the waste. Finally, the rotary kiln incineration and flue gas treatment processes were successfully applied in engineering for green production of pesticides.

A Circular Economy Approach to Military Munitions: Valorization of Energetic Material from Ammunition Disposal through Incorporation in Civil Explosives

Ammunition that has reached its end of life or become obsolete is considered hazardous waste due to the energetic material content that must be decommissioned. One of the technologies to dispose of ammunition involves the use of incinerators with sophisticated gas treatment systems; however, this disposal process has important limitations in terms of incinerator capacity, energy requirements and high costs. This article assesses the potential primary energy avoided and environmental benefits arising from the valorization of energetic material from military ammunition by incorporating it into civil emulsion explosives, as an alternative to destructive disposal. This approach follows the circular economy principle, as articulated inter alia in BS 8001:2007, by giving a new service to a residue through its incorporation into a new product. A prospective life-cycle model is implemented based on primary data from previous studies on the conventional disposal process and on the production of emulsion explosive. The model applies system expansion to calculate the environmental burdens avoided when energetic material from ammunition is incorporated into civil explosives. The results show that re-using ammunition through valorization of energetic material greatly reduces the environmental impacts in all categories compared to the conventional disposal process. The benefits arise mainly from avoiding the incineration and flue gas treatment processes in ammunition disposal, and displacing production of civil explosive components with the energetic material from ammunition.

Integrated assessment of the environmental and economic effects of an ultra-clean flue gas treatment process in coal-fired power plant

China’s coal production and consumption levels rank first in the world. Coal-fired power plants currently account for 65.5% of the total electricity output of China’s power grid. Coal-fired thermal power is the main industry consuming coal in China and the main source of atmospheric pollutants. To alleviate environmental pollution, the Chinese government recently released stringent flue gas emission standards for coal-fired power units. These standards require that the emission of dust, sulfur dioxide, and nitrogen oxides does not exceed 10 mg/m³, 35 mg/m³, and 50 mg/m³, respectively, to achieve ultra-clean emissions. Life-cycle assessment and life cycle costing methods are combined to analyze and compare the environmental and economic effects before and after ultra-clean emission retrofit in a 315 MW unit. The environmental impact of flue gas processing for 1000 kWh power plants decreased from 0.1529 to 0.1295 after ultra-clean emission retrofit. Desulfurization and discharged flue gas after treatment are the key processes examined in this case study, while power consumption during desulfurization and residual mercury in flue gas are key substances. Therefore, looking ahead, decreasing power consumption in desulfurization and using mercury removal technology are important aspects for decreasing the environmental impact of flue gas treatment systems in coal power units.

Influence of Air Pollution Control (APC) Systems and Furnace Type on the Characteristics of APC Residues from Municipal Solid Waste Incinerators

The characteristics of air pollution control (APC) residues are influenced by the furnace type, APC system, and waste composition. In this study, the characteristics of APC residues from nine municipal solid waste incineration plants (the compositions of incinerated solid waste are similar) with different furnace types and APC systems were compared.APC residues contain a great amount of Ca and Cl, and the contents of Al, Si, and Fe in the APC residues from fluidized bed incinerators are higher. The mineral compositions of APC residues are not influenced by the flue gas treatment process, but their contents vary. The contents of Cd, Pb, and Zn in the APC residues from fluidized bed incinerators are lower, while those of Cr, Ba, Cu, and Ni are greatly influenced by the APC systems, with the "grate+dry scrubber" APC residues having the lowest values. The differences in the heavy metal contents in the APC residues from two incinerators before and after the upgrading of the APC systems are not significant. The leaching toxicity of Pb in the APC residues from grate incinerators is higher than that from fluidized bed incinerators, while some elements with low contents in fluidized bed APC residues can be leached more in acetic acid buffer solution. The acid neutralization capacity of the APC residues is related to Ca content. The leaching concentrations of most heavy metals are significantly increased under strong acidity (Cd, Ni, and Zn:leachate pH < 8; Pb, Cu, and Cr:leachate pH < 4). The maximum leaching concentrations of As, Ba, Cu, Ni, and Pb in the APC residues from grate incinerators are mainly controlled by their total content. The leaching concentrations of As, Ba, Cu, Ni, and Pb in the APC residues from fluidized bed incinerators are lower than those from grate incinerators with similar metal contents, which may be due to their different chemical speciation influenced by furnace types and the complexation with Al and Fe compounds.

Effects of characteristics of waste incinerator on emission rate of halogenated polycyclic aromatic hydrocarbon into environments

We determined the concentrations of halogenated polycyclic aromatic hydrocarbons (XPAHs), some of which are carcinogenic and/or mutagenic compounds, in fly and bottom ashes and stack gas collected from waste incinerators in Japan. The dominant XPAHs in stack gas were consistent with those in the urban atmosphere. The dioxin-like toxic equivalent (TEQ) concentration ranges of the XPAHs in stack gas, fly ash, and bottom ash were 0.00497–20.5ng-TEQm−3, 0.0541–101ng-TEQg−1, and 0.000914–2.00ng-TEQg−1, respectively. The TEQ concentrations of the XPAHs targeted in this study were higher than those of polychlorinated dibenzo-p-dioxins/dibenzofurans and polychlorinated biphenyls reported in the literature. The annual amounts of XPAHs produced in the waste incinerators ranged from 25.1 to 881g. The mass balance of XPAHs in each waste incinerator was calculated to evaluate the emission rate of XPAHs from waste incinerators. Less than 6.7% of the XPAHs produced in the waste incinerators were emitted into the atmosphere from the facilities in which the flue gas was treated by using a combination of bag filter and activated carbon. In contrast, from the facility using a bag filter only, approximately 50% of the XPAHs produced were emitted into the atmosphere. Thus, the flue gas treatment process appears to be a key determinant of the emission rate of XPAHs produced during waste incineration.

Transport and transformation of mercury during wet flue gas cleaning process of nonferrous metal smelting.

Reducing mercury emission is hot topic for international society. The first step for controlling mercury in fuel gas is to investigate mercury distribution and during the flue gas treatment process. The mercury transport and transformation in wet flue gas cleaning process of nonferrous smelting industry was studied in the paper with critical important parameters, such as the solution temperature, Hg0 concentration, SO2 concentration, and Hg2+ concentration at the laboratory scale. The mass ratio of the mercury distribution in the solution, flue gas, sludge, and acid fog from the simulated flue gas containing Hg2+ and Hg0 was 49.12~65.54, 18.34~35.42, 11.89~14.47, and 1.74~3.54%, respectively. The primary mercury species in the flue gas and acid fog were gaseous Hg0 and dissolved Hg2+. The mercury species in the cleaning solution were dissolved Hg2+ and colloidal mercury, which accounted for 56.56 and 7.34% of the total mercury, respectively. Various mercury compounds, including Hg2Cl2, HgS, HgCl2, HgSO4, and HgO, existed in the sludge. These results for mercury distribution and speciation are highly useful in understanding mercury transport and transformation during the wet flue gas cleaning process. This research is conducive for controlling mercury emissions from nonferrous smelting flue gas and by-products.

INCINERATION FOR MUNICIPAL SOLID WASTE TREATMENT

In order to reduce the accumulation of waste in landfill, incineration technology could becomes one of the solutions. In addition to reduce the volume of waste, the energy generated by incineration process can also be utilized. Plant Incineration consists of four categories process, namely pre-treatment process, combustion process, energy recovery process and flue gas treatment process (Air Pollution Control system). Pre-treatment process is used to increase the average calorific value of waste. Pre-treatment process depends on the type of incinerator used. Combustion process in an incinerator must accommodate the principles of 3 T (temperature, turbulence, time). Process conditions for the type of incinerator grate in accordance with the principle of 3 Tare the waste residence time in the grate less than 60 minutes, gas residence time more than 2 seconds and the gas temperature over 850 C. In the combustion process will produce heat carried by flue gas. The heat will flow into energy recovery process to be utilized. From energy recovery process, flue gas will enter into the APC system to reduce air pollution caused by combustion process.keywords : incinerator, waste, energy recovery

Analysis of mixing conditions and multistage irradiation impact on NOx removal efficiency in the electron beam flue gas treatment process

ABSTRACTIn the process of electron beam flue gas treatment (EBFGT), most energy is spent on NOx removal. The dose distribution in the reactor is not uniform and the flue gas flow pattern plays an important role in the process efficiency. It was found that proper construction of the reactor may increase the energy efficiency of the process. The impact of the number of irradiation stages and mixing conditions on NOx removal efficiency was investigated for an ideal case and a practical solution was presented and compared with previously known EBFGT reactor constructions. The research was performed by means of computational fluid dynamics methods in combination with empirical Wittig formula. Two versions of dose distribution were taken for calculations. The results of the research show that for an ideal case, application of multistage irradiation and interstage mixing may reduce the energy consumption in the process by up to 39%. On the other side, simulation of reactor construction modification for two-stage irradiation results in 25% energy consumption reduction. The results of presented case study may be applied for improving the existing reactors and proper design of future installations.