Method of calculation of energy characteristics heat turbines taking into account the economy of the low pressure flow part

Thermal power plants require regular review of regulatory energy performance. Data sources for this can be the results of thermal tests or typical energy characteristics of units. The first way is costly, the second only partially allows taking into account the technical condition of the equipment. An urgent task is to develop a methodology for constructing energy characteristics that would make it possible to solve this problem with reasonable accuracy and using minimal resources. Such conditions are met by the existing methodology for determining the energy characteristics of turbines which is based on the methodology of matrix formalization of the calculation of energy-mass-exchange plants. The technique has been tested in relation to turbines with one-stage heat recovery. The aim of this study is to increase the accuracy of the calculation using the developed methodology for the energy characteristics of turbines with two-stage heat recovery. The turbine installation is simulated within the framework of the matrix formalization methodology using the equations of mass and energy balances solved by mathematical programming methods. The energy charac-teristics of the equipment are determined in accordance with the existing regulatory approach. The methodology for determining the energy characteristics of turbine plants developed in the framework of the matrix formalization meth-odology has been extended to the case of calculating steam turbines with two-stage heating selection by taking into account the dependence of the efficiency indicators of the low-pressure flow part on the position of the control diaphragm for different modes of heating network water. The results of test calculations with reasonable accuracy coincided with the energy characteristics of the operating turbine. For modes with one- and two-stage heating of network water, it is advisable to use different methods of accounting for the efficiency indicators of the low-pressure flow part. In this case, the introduction of the dependence of the internal relative efficiency of the low pressure part on the relative volumetric steam flow into the model for the regime with two-stage heating of network water allows achieving accuracy acceptable for solving practical problems.

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Optimisation of power generation cycles using saturated liquid expansion to maximise heat recovery

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1177/0954408916679202 ◽

2016 ◽

Vol 231 (1) ◽

pp. 57-69 ◽

Cited By ~ 7

Author(s):

MG Read ◽

IK Smith ◽

N Stosic

Keyword(s):

Power Generation ◽

High Pressure ◽

Heat Recovery ◽

Volume Ratio ◽

Low Pressure ◽

Working Fluid ◽

Two Stage ◽

Low Pressure Turbine ◽

Screw Machine ◽

Temperature Heat

The use of two-phase screw expanders in power generation cycles can achieve an increase in the utilisation of available energy from a low-temperature heat source when compared with more conventional single-phase turbines. The efficiency of screw expander machines is sensitive to expansion volume ratio, which, for given inlet and discharge pressures, increases as the expander inlet vapour dryness fraction decreases. For single-stage screw machines with low inlet dryness, this can lead to underexpansion of the working fluid and low isentropic efficiency. The cycle efficiency can potentially be improved by using a two-stage expander, consisting of a machine for low-pressure expansion and a smaller high-pressure machine connected in series. By expanding the working fluid over two stages, the built-in volume ratios of the two machines can be selected to provide a better match with the overall expansion process, thereby increasing the efficiency. The mass flow rate though both stages must be matched, and the compromise between increasing efficiency and maximising power output must also be considered. This study is based on the use of a rigorous thermodynamic screw machine model to compare the performance of single- and two-stage expanders. The model allows optimisation of the required intermediate pressure in the two-stage expander, along with the built-in volume ratio of both screw machine stages. The results allow specification of a two-stage machine, using either two screw machines or a combination of high-pressure screw and low-pressure turbine, in order to achieve maximum efficiency for a particular power output. For the low-temperature heat recovery application considered in this paper, the trilateral flash cycle using a two-stage expander and the Smith cycle using a high-pressure screw and low-pressure turbine are both predicted to achieve a similar overall conversion efficiency to that of a conventional saturated vapour organic Rankine cycle.

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Taking into account the efficiency of turbine plant flow path compartments in design calculations of their energy characteristics

Vestnik IGEU ◽

10.17588/2072-2672.2019.3.062-068 ◽

2019 ◽

pp. 62-68

Author(s):

K.N. Bubnov ◽

A.E. Barochkin ◽

V.P. Zhukov ◽

G.V. Ledukhovsky

Keyword(s):

Mass Exchange ◽

Power Plants ◽

Thermal Power ◽

Combined Cycle ◽

Thermal Power Plants ◽

Technological Systems ◽

Energy Characteristics ◽

Turbine Plant ◽

The Matrix ◽

Efficiency Indicators

Development of regulatory energy characteristics of TPP equipment is a mandatory and resource-intensive proce-dure. A mathematical model of the turbine plant (the turbine plant itself and its regenerative feed water heating system) was developed earlier based on the matrix formalization of calculations of the energy and mass exchange installations. The analysis of the modeling results has shown that the model adequately de-scribes the real characteristics of a turbine plant only at low bleeding load. At higher load, the accuracy of description is much lower and the model cannot be used for practical analysis of real equipment. All this means that the turbine model needs to be refined by introducing stage-dependent efficiency indicators for more accurate determination of the equipment energy characteristics and, based on them, developing of computer aided methods for optimizing regimes of technological systems and sub-systems of thermal power plants. Methods of mathematical programming were used to investigate the multi-flow heat and mass exchange systems and sub-systems of thermal power plants on the basis of heat and mass balance equations. The energy characteristics and efficiency indicators of TPP equipment were determined in accordance with the existing normative approach. The turbine plant model has been refined by the matrix formalization method by introducing stage-dependent efficiency indicators. Model solutions have been obtained and analysed in order to calculate energy characteristics of the combined cycle turbine plant. The calculaiton results have been compared with the energy characteristics of a turbine unit in operation. It has been shown that the proposed approach is reliable and reasonable. The obtained results can be used for increasing the validity degree of equipment energy characteristics calculation, creating computer simulators and software tools for optimizing modes of technological systems and subsystems of heat power plants.

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The influence of instability of the sensitivity of the matrix receiver on the measurement error of the space-energy characteristics of a laser beam

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2018-10-31-34 ◽

2018 ◽

pp. 31-34

Author(s):

A. M. Raitsin ◽

◽

M. V. Ulanovskii ◽

Keyword(s):

Measurement Error ◽

Laser Beam ◽

Energy Characteristics ◽

The Matrix

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Laser Flash Photolysis in a O3 / Cl2 Mixture in a Very Low Pressure Flow System

Photochemistry and Photobiology ◽

10.1562/2004-12-06-ra-395 ◽

2005 ◽

Author(s):

Jorge Codnia ◽

Francisco Manzano ◽

María Laura Azcárate

Keyword(s):

Flash Photolysis ◽

Laser Flash Photolysis ◽

Flow System ◽

Laser Flash ◽

Low Pressure ◽

Pressure Flow

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Physics-Based Modeling and MPC for the Air Path of a Two-Stage Turbocharged SI Engine with Low Pressure EGR

2020 European Control Conference (ECC) ◽

10.23919/ecc51009.2020.9143971 ◽

2020 ◽

Author(s):

Martin Keller ◽

Severin Geiger ◽

Dirk Abel ◽

Thivaharan Albin

Keyword(s):

Low Pressure ◽

Si Engine ◽

Two Stage

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Efficiency of two-stage heating of water on CHP plant with turbines of type T-250/300-240

Safety and Reliability of Power Industry ◽

10.24223/1999-5555-2019-12-3-213-219 ◽

2019 ◽

Vol 12 (3) ◽

pp. 213-219

Author(s):

E. T. Ilin ◽

S. P. Pechenkin ◽

A. V. Svetushkov ◽

J. A. Kozlova

Keyword(s):

Transition Period ◽

Steam Pressure ◽

Low Pressure ◽

Heat Extraction ◽

Two Stage ◽

Permissible Level ◽

Lower Heat ◽

Operational Modes ◽

Extraction Section ◽

Supply Water

During non-heating and transition period, most of cogeneration turbines operate with a lower heat extraction section actuated only due to a number of restrictions on the maximum and minimum pressure levels in the upper and lower heat extraction sections at operation of the turbine. For turbines of model T-250/300-240, the minimum permissible level of steam pressure in the upper heat extraction section, according to manufacturer data, is set to 0.06 MPa. During the non-heating and transition period, the supply water temperature is usually set in the range of 70–75°С. In order to maintain that temperature of supply water, the steam pressure in the upper heat extraction section should be below the minimum permissible level. As a result, the turbine operates with only the low-pressure heat extraction section actuated, which ensures operation without restrictions, but with a lower efficiency. The authors have introduced a set of measures, which enable to avoid those restrictions and implement two-stage heating of supply water. In this case, on connection of the upper heating extraction section, the pressure in the same is maintained at the minimum permissible level. Heat output characteristics are provided by having some of supply water delivered bypassing the group of network heaters. This operational mode enables to increase the turbine actual heat drop, to reduce the cooling steam flow into the low-pressure section and, accordingly, into the condenser, and to reduce temperature drops in network water heaters. Results of the research of operational modes for turbines of type T-250/300-240 in the non-heating and transition period with one and two-stage heating are provided. The economic efficiency of proposed operational modes was researched, which shows the effectiveness of those modes during non-heating and transition period. The limits of the efficiency of using these modes are determined.

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