A mathematical model of the water decarbonization processes in atmospheric deaerators is proposed to calculate the thermal decomposition degree of hydrocarbonates in a deaerator, pH of a deaerated water sample, and the mass concentration of free carbonic acid in it on a carbon dioxide basis. The mathematical description of these processes is based on the deaeration tank water flow model implemented in the specialized software suite for the calculation of three-dimensional liquid flows, where a real water flow is a set of parallel small plug-flow reactors, and the rate constant of the reaction representing a generalized model of the thermal decomposition of hydrocarbonates with consideration for its chemical and diffusion stages is identified by experimental data. Based on the results of experimental studies performed on deaerators of different designs with and without steam bubbling in their tanks, an empirical support of this model has been developed in the form of recommended reaction order and rate constant values selected depending on the overall alkalinity of water fed into a deaerator. A self-contained mathematical description of the water decarbonization processes in deaerators has been obtained. The proposed model precision has been proven to agree with the specified metrological characteristics of the potentiometric and alkalimetric methods for measuring pH and the free carbonic acid concentration in water. This allows us to recommend the obtained model for the solution of practical problems of forming a specified amount of deaerated water via the selection of the structural and regime parameters of deaerators during their design and regime adjustment.

Modeling the water decarbonization processes in atmospheric deaerators

The effect of the vapor of thermal deaerators on the energy efficiency of these heat-and-mass transfer apparatus and the thermal power plant as a whole is considered. Problems of reducing the vapor flow rate and its use in design and operation of Russian thermal power plants are neglected. Unjustified fuel losses in thermal deaerators of poor design and the lack of control over the vapor and its recovery are exemplified. The theoretical vapor flow rates necessary for different flow patterns of deaerated water and desorbing agent in deaerators are determined. A significant advantage in the energy efficiency of the countercurrent design over the once-through design is demonstrated. It is shown that the standardized specific vapor flow rates for thermal deaerators of different types are justified inadequately. The possibility of effective deaeration of water at a specific vapor flow rate that is substantially lower than the standard one and very close to the theoretically necessary value is proved based on experimental data. It is demonstrated that there is a wide margin to improve the energy efficiency of thermal power plants by rationally using the vapor heat of thermal deaerators. A necessary condition for increasing the energy efficiency of thermal power plants is shown to be the recovery of the vapor heat and mass of thermal deaerators. To this end, the vapor coolers should be made of corrosion-resistant materials and the vapor condensate should be used in the water-steam cycle of the power plant. Another important way to improve the efficiency is to maintain the vapor flow rate consistent with the operating mode of the deaerator, which can most effectively be done by monitoring the residual content of corrosive gases in the deaerated water. A schematic of a deaeration plant with the vapor flow rate controlled by monitoring the residual oxygen content in the deaerated water is proposed. The vapor flow rate in such a plant is kept necessary and sufficient to maintain the rated desorption efficiency of dissolved oxygen in all thermohydraulic deaeration modes, thus preventing the operation of the deaerators at insufficient or excessive vapor flow rate.

The Vapor of Thermal Deaerators as a Factor of their Energy Efficiency

The lack of reliable information on the status of fixed assets of medical institutions located in rural areas complicates the development of management systems for the material and technical resources of rural health care. Given that modern information technologies are widely used in health care, a topical solution of this problem is the automatic collection, processing, storage and analysis of data on material and technical equipment of rural health care. The aim of the research is to develop an automated information system that provides the collection of indicators of the material and technical equipment of rural health care for monitoring purposes. To achieve this goal, methods to collect, process and analyze information on the equipment of feldsher-midwife stations and outpatient clinics were used. Automated system "Monitoring of material and RESUMEN: La falta de información confiable sobre el estado de los activos fijos de las instituciones médicas ubicadas en áreas rurales complica el desarrollo de sistemas de gestión de los recursos materiales y técnicos de la atención de salud rural. Dado que las modernas tecnologías de la información son ampliamente utilizadas en el cuidado de la salud, una solución tópica de este problema es la recolección, procesamiento, almacenamiento y análisis automáticos de datos sobre el material y el equipo técnico de la atención médica rural. El objetivo de la investigación es desarrollar un sistema de información automatizado que proporcione la recopilación de indicadores del material y el equipo técnico de la atención de salud rural para fines de monitoreo. Para lograr este objetivo, se utilizaron métodos para recopilar, procesar y analizar información technical management of rural health care" was developed as a result of the study.

Modernization of accounting of material and technical management of rural health care through information technology

A mathematical model of mass transfer in an atmospheric bubbling deaerator storage tank at thermal power stations (TPS) to calculate the removal efficiency of dissolved gases from water is considered. For mathematical simulation and calculation of the deaerator efficiency, a system of differential equations of mass and heat transfer is written in a local form for the liquid phase of the layer with volume interphase sources of mass and heat. Mass transfer of the dissolved gases from water to the vapor phase is taken into account using volume interphase sources and the balance equations. Parameters of the interphase sources and correlations for calculating the eddy viscosity of the liquid phase depending on bubbling conditions are given. Results from the system of equations' numerical solution are presented and compared with the available experimental data on the final concentration of dissolved oxygen at the deaerator outlet. Curves of the efficiency of dissolved oxygen removal depending on the operating conditions and design characteristics of the bubbling process are presented, and scientific-and-engineering solutions have been developed to upgrade the bubbling storage tank. It has been found that an increase in gas velocity sharply raises the deaeration efficiency to a certain value (depending on the specified initial parameters), and the efficiency growth is then retarded. Similarly, increasing the length of a bubbling device improves the efficiency in removal of dissolved oxygen from water. One of the causes of a decrease in the water deaeration efficiency is likely to be back mixing of the flow. Upgrading of the deaerator tank is in the installation of perforated baffles across the flow to considerably reduce back mixing of the liquid phase. This increases the driving force of mass transfer, and its efficiency improves by five to 20% depending on the steam velocity. The presented mathematical model can be generalized to a wide range of bubbling apparatuses with a high two-phase layer.

A Mathematical Model and Design Calculation of a Thermal Deaerator with a Bubbling Storage Tank

The process of removing corrosive gases from water at TPPs in packed columns of calciners and in columns of thermal deaerators with a storage tank in film mode is considered and a mathematical model is presented for calculating the efficiency of the desorption process A cell model of the flow structure and an equation for calculating the mass transfer coefficient for a wave flow of a water film over the surface of a packing with artificial roughness are used The value of the required height of the packing layer is obtained for the given density of irrigation with water and the efficiency of extracting gases dissolved in water Formulas are given for calculating the parameters of a mathematical model: the coefficient of mass transfer in the wave film, the average velocity of water in the film, the dynamic retention of the liquid in the packing layer and the number of cells for complete mixing of the liquid phase The possibility of using metal chaotic and regular packings is considered, and the results of calculations of the efficiency of mass transfer and the required height of the packing layer at various operating parameters of the desorption process are presented The graphs of the required layer height for the given efficiency of mass transfer and the power spent on air supply to the desorber when using various nozzles of domestic and foreign production are presented The article describes the operation of a thermal deaerator with a storage tank and outdated contact devices in a deaerator column at a TPP The main mass transfer and hydraulic characteristics of modern nozzles for thermal deaerators are presented Technical solutions have been developed that can be used when choosing a highly efficient metal chaotic packing with a rough surface, which provides an increase in the mass transfer coefficient in a liquid wave film and, accordingly, the efficiency of mass transfer A variant for modernization of the deaeration column of the DSA-300 deaerator at the Kazan CHPP-3 by replacing outdated contact devices with a modern chaotic packing is shown As a result of its application, compliance with the standards of water purification from dissolved oxygen is ensured at various loads on water and steam

Determining the Efficiency of Desorption of Corrosive-Active Gases in Columns with Chaotic and Regular Nozzles

The results obtained from combined numerical and experimental investigations of the water decarbonization process carried out in atmospheric-pressure deaerators without subjecting water to steam bubbling in the deaerator tank are presented. More exact values of the hydrocarbonate thermal decomposition rate have been obtained, and the hypothesis about a change of the process governing mechanism in shifting to low total alkalinity values of deaerated water has been proven in the course of these investigations. A procedure for predicting the indicators characterizing the water decarbonization efficiency in using deaerators is proposed based on the obtained study results. The developed procedure features the maximally possible accuracy that can be achieved at the metrological characteristics of the standard alkalinity measurement methods.

Predicting the indicators characterizing the water decarbonization efficiency when using atmospheric-pressure thermal deaerators without subjecting water to steam bubbling in the deaerator tank

The problem of striking material and energy balances from the data received by thermal power plant computerized automation systems from the technical accounting systems with the accuracy determined by the metrological characteristics of serviceable calibrated instruments is formulated using the mathematical apparatus of ridge regression method. A graph theory based matrix model of material and energy flows in systems having an intricate structure is proposed, using which it is possible to formalize the solution of a particular practical problem at the stage of constructing the system model. The problem of striking material and energy balances is formulated taking into account different degrees of trustworthiness with which the initial flow rates of coolants and their thermophysical parameters were determined, as well as process constraints expressed in terms of balance correlations on mass and energy for individual system nodes or for any combination thereof. Analytic and numerical solutions of the problem are proposed in different versions of its statement differing from each other in the adopted assumptions and considered constraints. It is shown how the procedure for striking material and energy balances from the results of measuring the flows of feed water and steam in the thermal process circuit of a combined heat and power plant affects the calculation accuracy of specific fuel rates for supplying heat and electricity. It has been revealed that the nominal values of indicators and the fuel saving or overexpenditure values associated with these indicators are the most dependent parameters. In calculating these quantities using different balance striking procedures, an error may arise the value of which is commensurable with the power plant thermal efficiency margin stipulated by the regulatory-technical documents on using fuel. The study results were used for substantiating the choice of stating the problem of striking material and fuel balances, as well as the method for solving it. With the problem statement and the solution method implemented in the real thermal power plant computerized automation systems, less biased calculation of actual thermal efficiency indicators of equipment is obtained.

Algorithms for striking material and energy balances in calculating the technical-and-economic indicators of thermal power plant equipment based on the ill-posed problem regularization method

G. V. Leduhovsky

Papers

Modeling the water decarbonization processes in atmospheric deaerators

Predicting the indicators characterizing the water decarbonization efficiency when using atmospheric-pressure thermal deaerators without subjecting water to steam bubbling in the deaerator tank

Algorithms for striking material and energy balances in calculating the technical-and-economic indicators of thermal power plant equipment based on the ill-posed problem regularization method