Safety Of Thermal Power Plants Research Articles

Industrial environmental control of polycyclic aromatic hydrocarbons in organic fuel combustion product

RELEVANCE of this study lies in the computational justification of the choice of the installation location of a multipoint sampling probe in the measuring section of the flue of boiler plants of energy enterprises and thermal power plants that have a significant negative impact of emissions on the environment, in order to increase the reliability and representativeness ofinstrumental measurements during industrial environmental control (PEC) of polluting emissions (PE). PURPOSE. Improving the environmental safety of thermal power plants in the current conditions of the introduction of state principles of technological regulation of emissions is associated with the establishment of technological emission indicators for each source of atmospheric pollution at energy enterprises with a significant negative impact on the environment. In this regard, energy enterprises should carry out round-the-clock monitoring of PE, which requires reliable instrumental control of the content of marker substances in the combustion products of power boilers by determining a representative sampling point on the flue or chimney of an energy boiler installation. METHODS. The paper uses methods of computer simulation of gas dynamics to determine the local fields of concentration of PE and flow velocity and assess their unevenness in the flue of an energy boiler. RESULTS. Using the example of an operating energy boiler plant of a thermal power plant, a control section of the flue was determined to ensure industrial environmental control of marker substances in the combustion products of organic fuels. The average values of the concentration of PE and the flow rate of combustion products of local fields in the calculated sections and their values on the longitudinal axis of the boiler flue are determined, and their uneven distribution is estimated. CONCLUSION. The obtained research results can be used at energy enterprises and thermal power plants to justify the choice of a control representative measuring section for conducting a PEC, and to develop an environmental efficiency improvement program (EEIP).

Methods for reducing nitrogen oxide emissions in steam generators of thermal power plants

Main problem: Ensuring environmental safety of thermal power plants by reducing emissions of harmful substances, in particular nitrogen oxides. When all types of fossil fuel, including solid fuel, are burned, nitrogen oxides are formed in the boilers of TPPs. The sources of their formation are air nitrogen and nitrogen- containing components of the organic matter of the fuel. As you know, they adversely affect the health of humans, plants and animals. Therefore, it became necessary to consider and analyze methods to reduce these emissions. Purpose: To review and analyze various ways to reduce nitrogen oxide emissions and propose a new scheme for reducing these emissions by recirculating flue gases. Methods: This is achieved due to the fact that in the known method for purifying the flue gases of steam generators from nitrogen oxides by lowering the temperature in the furnace of the steam generator by supplying flue gases with a temperature below the temperature in the furnace of the steam generator, it is proposed that the flue gases be fed into the furnace of the steam generator after ash cleaning. At the same time, as a result of the supply of recirculated gas cooled after filtering and passing through the main smoke exhauster into the combustion chamber, having a temperature of 110-170 °C, in comparison with the initial version, a greater decrease in temperature in the furnace of the steam generator occurs, which in turn leads to a decrease in the flue gases of oxides nitrogen, since the chemical reaction of their formation goes with the absorption of heat. Results and their importance: The technical result at the proposed method of cleaning from nitrogen oxides is to reduce the consumption of electricity by eliminating the collateral wear of the recirculation gas duct, due to the cleaning of time gases from ash (a requirement of the rules of technical operation of PTE).

Rough sets-based prediction model for increasing safety of thermal power plants

ABSTRACTThis paper presents a model based on the rough sets theory for the prediction of a feed pump failure on a steam block of thermal power plant. There are many parameters that can cause pump failure, and this model enables extraction of the most significant ones. Model creation is based on the empirical data collected during the operation of thermal power plant, which is a part of the largest system for electricity production in Serbia. The model provided an insight into the parameters that have the greatest influence on the operation of the feed pump, and can be applied to other elements of the thermal power plant and affect the overall increase in the safety of thermal power plant operation. The goal of implementation of a new model is to increase system reliability by reducing the number of failures, thus increasing operational safety of thermal power plants. This is in accordance with the provision of energy security by applying measures of Directive 2005/89/EU. According to the directive, it is necessary to ensure: a reliable, safe, efficient and quality power supply.

The assessment of the feasibility of power technological plants on the territory of the Russian Federation

To improve the environmental safety of thermal power plants, the use of an industrial complex for the preliminary preparation of the initial solid fuel – an power technological plant has been proposed. The basis of the functioning of this complex is the consistent application of processes of power technological processing of solid fuels, such as gasification, pyrolysis, enrichment, briquetting, the production of artificial composite fuels. The fuels obtained at an power technological plant have improved energy and environmental performance. In the future, the fuel from the power technological plant is distributed to the energy facilities of the region. In the present work, a selection of regions for the development power technological plants were developed, the calculated characteristics of the resulting fuels were presented: the net calorific value of the working and dry ash-free mass, the elemental composition, the amount of emissions generated by burning the resulting fuels. An assessment is made of the possibility of functioning of power technological plants in the construction region.

Анализ влияния характеристик и условий сжигания мазутных топлив на выход пентаоксида ванадия

An approach to elaborating a computation method for determining the content of vanadium pentoxide in the combustion products from gas- and-oil-fired boilers is considered within the framework of clarifying the contribution this substance introduces in the overall toxicity of flue gases. The need of such assessment is stemming from the fact that vanadium pentoxide is a substance related to the first class of hazard along with carcinogenic polycyclic aromatic hydrocarbons. To justify the extent to which the vanadium pentoxide emission must be reduced, it is necessary to determine the contribution of individual fuel components and the fuel oil combustion conditions in the environment pollution intensity. Calculation dependences that make it possible to consider the important energy and performance characteristics of thermal power boilers and the fuel used in them are proposed. Fuel oils of various grades and relating to different classes of sulfur content are selected as fuels under study to analyze the effect the component composition of fuel oil has on the amount of vanadium compounds generated in the combustion products. It has been found that the content of vanadium pentoxide in the boiler smoke gases depends directly on the vanadium concentration in the source fuel. No additional amount of vanadium is generated in the combustion products in the course of alternative chemical reactions and transformations. It has also been found that a significant effect of reducing vanadium emissions into the environment during the operation of fuel combusting installations is achieved through the use of expensive catalytic gas purification systems. It is pointed out that, in order to achieve more efficient reduction of vanadium pentoxide emissions into the atmosphere, is necessary to decrease the emission of sulfur-containing components of flue gases. Data on the content of sulfur in the source fuel allows, to a considerable extent, a conclusion to be drawn on the possibility of vanadium pentoxide to be produced at the fuel combustion stage and in the flue gases. The levels of vanadium pentoxide emissions have been determined for certain designs of gas-and-oil-fired boilers taking into account the effect of incomplete combustion, the fraction of unburned carbon, and fuel burnout degree in the combustion device. In the nearest future, improvements in the environmental safety of thermal power plants in Russia will be connected with introduction of best available technologies that will make it possible to standardize the emissions of harmful substances into the atmosphere from the standpoint of sanitary-hygienic requirements, process parameters and characteristics of domestically produced boiler units.

Thermal Stress Development in Steam-Side Oxide Scales in High Temperature Components of Boilers under Thermal Shock

Failure of steam-side oxide scales in high temperature components of boilers such as superheater and reheater tubes has significant effect on the safety of thermal power plants. Finite element analysis is carried out to investigate the failure issues of steam-side oxide scales in boiler tubes during thermal shock processes. The effects of different steam temperature variation durations on oxide scale failure issues have been analyzed. According to the results, appropriately lengthening variation duration can contribute to relieving oxide scale failure issues, and are subsequently proposed.

On the failure of steam-side oxide scales in high temperature components of boilers during unsteady thermal processes

Failure of steam-side oxide scales in high temperature components of boilers such as superheater and reheater tubes has significant effect on the safety of thermal power plants. Taking into account the influence that temperature has on physical properties of metal substrate and oxide scale, transient heat transfer model as well as multi-layered hollow cylinder stress model is successively developed in this work. Employing the Advanced Oxide Scale Failure Diagram (AOSFD) as failure criterion, a systematic analysis model for the failure behavior of steam-side oxide scales in T92 superheater tubes during unsteady thermal processes is established. Focusing on different steam temperature variation processes, the effects of steam-side oxide scale thickness as well as different steam temperature variation modes and variation durations on oxide scale failure issues have been analyzed. Besides, critical steam temperature drops leading to failure of oxide scales when steam temperature decreases linearly have also been investigated. Based on the analysis results, feasible measures such as selecting reasonable steam temperature variation mode and appropriately lengthening variation duration are subsequently proposed. The analysis results as well as the suggested measures in this work can provide valuable guidance for the solution of steam-side oxide scale failure issues in thermal power plants.