Principal Modernization Solutions for a 300 MW Power Unit to be Converted to Operate at Ultra-Supercritical Steam Parameters

This paper analyses the state of power engineering in Ukraine and the main trends in the development of the world market in the field of converting high-capacity powerful power units of thermal power plants into ultra-supercritical (USC) ones. It is shown that the energy sector of Ukraine requires special attention and the introduction of new modern technical solutions. Worldwide trends indicate that the emphasis is now on increasing the steam parameters before a turbine to ultra-supercritical ones. This allows one both to increase the efficiency of power units and to reduce thermal emissions, fighting the global environmental problem of climate warming. The implementation of this approach is proposed taking into account the realities of the Ukrainian economy and the available technical capabilities of the power engineering industry. This paper presents the results of variational computational studies of the thermal scheme of the 300 MW power unit of the K-300-23.5 turbine to be converted into a USC one. The problem was solved under the condition of maximizing the preservation of the thermal scheme, increasing the efficiency of the power unit and minimizing capital investments during the modernization of the turbine. It was chosen to preserve the regeneration system, as well as the medium-pressure (MP) and low-pressure (LP) cylinders. Considered and calculated were variants with the addition to the existing turbine of a USC cylinder and the creation of a new high-pressure cylinder (HPC) with insignificant changes in its overall characteristics. The results of computational studies showed that the most rational variant for modernizing the 300 MW turbine plant is the creation of a new HPC designed for operation at USC steam parameters as well as the addition to the IPC of a new cylinder with the purpose of increasing the reheat steam parameters while preserving the regeneration system.

FACTOR ANALYSIS OF THE THERMAL SCHEME OF CHP WITH SUPER CRITICAL STEAM CYCLE ON THE BASIS OF EXERGY METHOD

The most promising direction of CHP modernization is the introduction of power units on supercritical steam parameters. Increasing steam parameters is one of the most effective ways to increase the efficiency of a CHP plant. Thus, the development of the concept of thermal schemes turbines for supercritical steam parameters, taking into account the characteristics of their operation at the existing CHP Ukraine is an actual scientific problem. The solution to this problem will make it possible to replace or modernize the power generating equipment that has exhausted its resource with modern power units that meet world economic and environmental standards. The method of exergy analysis is adapted to the study of thermal schemes of CHP plants with supercritical steam cycle. As an example of application of a method the exergy analysis of the power plant working on the one-stage thermal scheme is carried out. Within the framework of the proposed method, a thermodynamic and topology-exergetic model of the power plant is created. Based on the topology-exergetic model the indicators of thermodynamic efficiency of the power plant operating on supercritical parameters of steam are determined. It is proposed to apply the theory of experiment planning in exergy analysis of the thermal circuit of a CHP. With the involvement of this theory, a multifactor numerical experiment was conducted to determine the impact on the exergetic efficiency of the thermal scheme of CHP of the main determining variable factors, such as adiabatic and thermal efficiency of the plant, as well as the operating parameters. The generalized equation of functional interrelation of exergetic efficiency of system and exergetic efficiency of elements of thermal scheme of CHP is received. The proposed equation can be used as a tool for further training of neural networks and their application both in the design and in the diagnosis of energy efficiency of CHP. According to the results of the factor analysis, a rather high conservatism of the considered one-stage scheme of CHP to the change of the varied parameters was revealed. This indicates the presence of more rigid structural links between the elements, which is generally a positive aspect of the reconstruction.

Optimization of the Initial Parameters of the Utilization Circuit of Cogeneration Combined Sycle Plant of Two Pressure Levels

This article is devoted to optimization of parameters and structure of the industrial-heating vapor-gas facilities (HVGF). The aim of the study is determination of the optimal initial parameters of two-circuit utilization HVGF. The set goal is achieved based on the methods of the mathematical modeling of the thermal schemes, using the elements of thermodynamic economic analysis. As the optimization criterion, the index of a relative fuel economy is used upon the combined generation of the energy and heat. The most significant result of the research consists in revealing a tendency to an increase in the optimal vapor pressure of the HVGF high pressure circuit, compared to a similar parameter of the condensation vapor gas device (VGD CEPP). For the two-circuit HVGF, the optimal initial pressure is 9.8—10 MPa (for the CEPP it is 8 MPa). The tendency is revealed for an increase of the relative fuel economy upon the complication of the HVGF thermal scheme. It was established that for the identic HVGF located in different energy systems, the relative fuel economy differ greatly. The relative fuel economy for the HVGF under consideration compared to analogous VGD CEPP is 27.35 %, and compared to the vapor turbine CEPP, the relative fuel economy will increase by 8.8 %. The importance of the results obtained consists in that their application will make it possible to increase the energy efficiency of the HVGF being constructed, and optimize the structure of the energy systems of separate regions and states.

Modeling the Heat Scheme of the Combined Heat and Power Plants Using the Software Product “Boiler Designer”

This article describes the rationale for the development of a mathematical model of the thermal scheme of Vladivostok thermal power plant. Four types of turbines are installed at this plant, boiler units operate on coal and natural gas. This makes it difficult to effective load distribution between the turbine units. Application of simplified dependencies, built on the basis of the reporting data, allows to analyse the correctness of the load distribution between the units. The article provides an example of comparing the actual parameters of the plant and calculating based on the simplified characteristics of turbines. This example showing the loss of fuel equivalent from non-optimal load distribution. However, the use of such simplified characteristics has several shortcomings. These shortcomings do not allow using this as a universal method. There is a need to create a full-fledged mathematical model of thermal power plants. The model is developing on the basis of the Boiler Designer software package. The program has a modular structure and allows you to create mathematical models of each unit of equipment, and then, through the purpose of connections, assemble the thermal scheme of the station. This approach is actual for cross-linked heat and power plants, since it allows us to evaluate the efficiency of thermal scheme connections, and not just the operation of the equipment itself. The article provides a simplified model of the station, its advantages and disadvantages

Study of the work and efficiency improvement of combined-cycle gas turbine plants

The purpose of the paper is to study and analyze the possibility of increasing the power output of a combined-cycle gas turbine (CCGT) unit during the period of positive ambient temperatures. The first task is to analyze the operation of a 110 MW combined-cycle power unit at various ambient temperatures and to obtain alterations in the main CCGT characteristics when the ambient temperature changes. The other task is to study the usage of an absorption refrigeration machine in a CCGT cycle to increase its energy efficiency. Calculations of the thermal scheme of a gas turbine were carried out using mathematical modeling, the steam turbine was calculated based on guidelines. The conducted studies allow to conclude that the use of an absorption refrigeration machine in the cycle of a combined-cycle plant can improve the efficiency of the unit, increasing profits from power generation, and reducing penalties for non-compliance with the load schedule.