Accounting for the variable nature of heat loads in optimizing cogeneration combined heat and power plants

Abstract

550For cogeneration thermal power plants (CHP) with combined generation of electrical and thermal energy, variations of the heat load during the year (with the change of the ambient air temperature) are typical. Clearly, this fact should be taken into account in selecting their flow diagrams and parameters.Over the last 20 years the problems of mathematical modeling and optimization of parameters of CHP plants with account for the variable operating condi tions have been discussed in works [2][3][4][5][6]. The analysis of these problems showed that for such CHP plants the following calculations should be carried out: design calculation for the operating mode with maximum loads and checking calculation for several characteris tic operating modes with various heat loads of con sumers, ambient air temperatures, and the duration of their operation. In doing so, it is possible to single out independent optimized parameters of two kinds. The parameters belonging to the first kind (design opti mized ones) determine the design characteristics of a plant. Among these are the pressures of live steam, of reheat steam under the design operation mode, etc. Parameters of the second kind (operating optimized ones) determine the operation of a plant in character istic modes (for example, steam pressure in the extrac tion line of the steam turbine). As this takes place, the change in the parameters of the first kind has an effect, through the design characteristics of components, on the operation in all modes, whereas the change in the parameters of the second kind has an influence only on the operating mode to which these parameters relate. The results of both the design calculations, on the basis of which design characteristics and invest ments are established, and of checking calculation, by means of which fuel consumption, electric power pro duction, and heat supply over the calculation based period are determined, affect the value of the goal function, with one possible criteria of the economical or energy efficiency serving as this function.In work [1] the mathematical model used for opti mizing was reduced to carrying out one detailed design calculation at maximum loads and several checking calculations at partial loads. Such approach, typical for the computer technology of the early 1990s, required excessive consumption of machine time and memory. Besides, poor convergence of the process of nonlinear optimization became evident, which was caused by application of errors occurring on solving the systems of non linear algebraic and transcendental equations of the design and checking calculations by means of iteration methods. In this connection the development of simplified methods of optimization and mathematical models became necessary.The first approach to such simplification consisted in separating the problems for optimization of design and operating parameters [2]. At the first stage the problem of optimization of a CHP plant at maximum loads must be solved. In doing so, annual fuel con sumption, electric power, and...

A technique for determining a relationship between the prices of heat and electricity generated by CHP

“…Characteristic operating modes can have heating and ventilation nominal heat loads and heat partial loads corresponding to different outdoor temperatures. The annual duration of the CHPP operation in these modes is determined on the basis of the graphs of the duration of the standing outside air temperatures in the area in which the CHPP will operate [9]. The methodological approach was developed by ISEM SB RAS for single-product CHPPs that produce only electricity.…”

“…, (9) under the conditions (2)- (10), where h year E .-the amount of exergy in the annual heat release. The range of heat prices (obtained as a result of solving the two specified optimization problems) will cover the heat prices of all competitive single-product CHPPs.…”

Information and Analytical Platform for Evaluating the Effectiveness and Choosing Directions for Improving the Energy and Water Supply Systems of Oil and Gas Chemical Complexes

“…ВВЕДЕНИЕ Системы обеспечения топливом, электрической и тепловой энергией и технологической водой действующих нефтегазохимических комплексов (НГХК) формировались в условиях начала разработки соответствующих месторождений углеводородного сырья (УВС) без учета динамики их развития и взаимосвязей с внешними системами энергообеспечения (ВСЭ). В настоящее время концепция построения перспективных систем энерговодообеспечения (СЭВО) НГХК базируется на принципах генерации энергоносителей (ЭН) в автономных установках с тепловыми двигателями различного типа [1][2][3][4][5] и использовании потенциала горючих низконапорных газов технологических производств и возобновляемых источников энергии [6][7][8][9]. Для решения задач анализа и синтеза СЭВО, высокоэффективных на всех этапах жизненного цикла НГХК, требуется создание специализированного информационно-аналитического обеспечения, позволяющего учесть следующие требования к технологическим и энергетическим элементам в динамике их развития:…”

“…Проведенный анализ разработанных моделей и информационно-аналитических систем энергетических комплексов промышленных предприятий (технологических аналогов НГХК) показал, что их применение ограничивается как аппаратурным оформлением СЭВО, так и комплексом решаемых задач: логистического обеспечения технического обслуживания оборудования химических производств [10]; управления энергосбережением электро-и теплоэнергетического оборудования [11]; оптимизации режимов работы теплофикационных энергетических установок [2]. Разработаны также другие информационные системы [12,13], программные комплексы [14,15] и имитационные модели [4,16,17], которые, к сожалению, не могут быть использованы (полностью или поэлементно) для решения задач расчета энерготехнологических и конструктивных параметров, научно-исследовательских и конструкторских разработок оборудования, единичных установок и синтезируемых из них автономных СЭВО и ЭТМ НГХК в связи с перечисленными специфическими требованиями к изучаемому объекту.…”

Technical-economic evaluation of medium-power gas turbine plant with air bottoming cycle

“…The methodology for assessing the economic efficiency through solving the non-linear optimization problem is described in [12]. Studying power plants, the authors of [13] propose the optimization problems of several types. Here, for the considered power plant, such problems include: Problem 1.…”