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Development of preliminary design of the energy
system of the Ningdong, Ningxia thermal power
plant
Zhenyu Yang1
*
, Liyuan Zhang1 and Zhou Gao2
1Institute of Energy, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, 195251,
Russian
2Changchun Institute of Technology, School of Energy and Power Engineering, Changchun, 130012,
China
Abstract. The purpose of this design is to master the basic steps, calculation
methods, and equipment selection methods of the thermal power system of
the thermal power plant, and to familiarize with the composition,
connection, and operation characteristics of the thermal power system
through the preliminary design of 600MW thermal power plant thermal
power plant. This paper is divided into five parts, selecting the principle
thermal system formulation, calculating the principle thermal system, the
selection of unit auxiliary equipment, steam pipeline calculation, and
selection after and after successful calibration. The preliminary design of the
thermal system is completed by drawing the comprehensive thermal system
diagram and the local system diagram using the above calculation data.
1 Introduction
At present, in China's power structure, thermal power generation accounts for 75.6%,
hydroelectric power generation accounts for 23.5%, nuclear power generation accounts for
0.9%, and a small amount of the use of wind energy, solar energy, geothermal energy and
ocean energy and other new energy to the area of renewable energy generation. For a long
time, China's thermal power generation industry generated a unit capacity of 300MW units
and low parameter units below the main, average coal consumption rate. Low efficiency,
high emissions, and high coal consumption, the resulting environmental problems are
becoming more and more serious, the national haze phenomenon has intensified, and people's
lives are affected [1-11].
The 600MW unit is a supercritical unit with high efficiency, low coal consumption, a
high degree of automation, fewer operators, etc. It also has the advantages of a short
construction period, a small footprint of unit capacity, etc., which are suitable for China's
national conditions. For this reason, Ningxia Nindong Power Plant N600MW is selected as
the design topic to carry out the preliminary design of the thermal system of the 600MW unit.
*
Corresponding author: zhenyu99@bk.ru
E3S Web of Conferences 458, 01018 (2023)
EMMFT-2023
https://doi.org/10.1051/e3sconf/202345801018
© The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative
Commons Attribution License 4.0 (https://creativecommons.org/licenses/by/4.0/).
2 Formulation of the principle thermal system
The principle thermal system is a detailed representation of the nature of the thermal process,
the use of heat and energy conversion by the mass in the thermal system, and the influence
of the thermal economy. The first step in the preliminary design of a thermal system is the
appropriate formulation of the principle thermal system.
2.1 Development of feedwater reheat heating systems
In the drawing up of the feedwater reheat system, the choice for this design is three high-
pressure heaters, three low-pressure heaters, and one deaerator, with one shaft seal heater
installed between the low-pressure heater and the condenser.
2.2 Preparation of the hydrophobic method for the heat recovery system
The hydrophobic method is divided into hydrophobic pumps and step-by-step self-flow, the
design of hydrophobic selection of step-by-step self-flow method, the use of adjacent heaters
on the steam side of the pressure difference so that the hydrophobic flow to the lower pressure
heater. Select the step-by-step self-flow method, which has the advantages of spending less,
the system is relatively simple, stable, and so on, the disadvantage is that the poor thermal
economy, to reduce the disadvantages of the poor thermal economy of the step by step self-
flow needs to be set up the steam cooler and hydrophobic cooler. The heater chosen is a
surface heater, three high-pressure heaters are equipped with a steam cooler and hydrophobic
cooler, and three low-pressure heaters are set up with a hydrophobic cooler.
2.3 Development of feedwater deoxygenation systems
The deaerator operation is divided into two ways: sliding pressure and fixed pressure, In this
design the deaerator is selected to work under sliding pressure, and the deaerator sliding
pressure operation has the advantage of improving the economy of operation. This is because
the throttling loss of steam in the pump is avoided, and when the load is low, there is no need
to switch the pump to higher pressure to pump out the steam, saving investment. At the same
time, the turbine pumping points can be reasonably distributed, and with the slip-pressure
operation, the high-pressure cylinder at all levels, including the high-pressure cylinder
exhaust steam temperature will increase, which ensures the reheat steam temperature and
helps to improve the efficiency of the heat cycle.
2.4 Supplementary water system development
Supplementary water can be supplemented to the deaerator and condenser in two places, In
this design, the pressure of the deaerator is higher, and supplemental water to the condenser
can improve the efficiency of the heat return system, so the choice of supplemental to the
condenser as a better choice.
3 Calculation of the principle thermal system of a power plant
3.1 Known data
(1) Turbine type and parameters
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The CLNJK600-24.2/566/566 unit produced by Harbin Turbine Works is a supercritical,
primary intermediate reheat, single-shaft, three-cylinder, four-discharge, high and medium-
pressure combined-cylinder, indirectly air-cooled condensing steam turbine.
Primary parameters：
Reheating parameters：
MPa.=P 224
0
cold section pressure, cold section temperature
℃
.=Cin
rh 5303
; hot section pressure
Mpa.=Pout
rh 6483
, hot section temperature
℃
=Cout
rh 566
;
Exhaust steam parameters：
MPa.P= 00460
,
kJ/kg.=hc61131
;
Feed water parameters: temperature283.8℃;
(2) boiler type furnace and parameters
Boiler type is the boiler manufactured by Harbin Boiler Works for supercritical
parameters of pressure-variable operation spiral tube ring plus vertical tube DC furnace,
single hearth, a middle reheat, using the cut-circle combustion mode, balanced ventilation,
solid slagging, all-steel suspension structure Π-type boiler, indoor arrangement of coal-fired
boilers, boilers are tightly closed body. Boiler model: HG-2210/25.4-YM16.
Boiler parameters: superheated steam pressure 25.4MPa, superheated steam outlet
temperature 571℃;
Rated evaporation capacity: 2115t/h;
Reheat steam inlet/outlet pressure: 4.368/4.158MPa, temperature 314/569℃;
Final feed water temperature:280.1℃;
Boiler efficiency: 93.5%;
(3) Parameters of return heat system
This unit adopts 7-section non-adjustable steam extraction, corresponding to three high-
pressure heaters, one deaerator, and three low-pressure heaters, The deaerator adopts sliding-
pressure operation mode, and the parameters at rated working condition are shown in Table
3-1.
Table 1. Rated working condition parameters
Item
Unit
Parameters of reheat extraction steam
1
2
3
4
5
6
7
Heater number
GJ1
GJ2
GJ3
CY
DJ1
DJ2
DJ3
Pumping
pressure
MPa
5.88
4.17
2.10
1.065
0.379
0.187
0.098
Pumping
temperature
℃
353.1
307.3
476.6
374.4
250.8
182.8
119.0
Pressure loss
coefficient of
pumping
pipeline
％
4.3
4.2
4.1
4
3.9
3
2.7
Heater end
difference
℃
-1.7
0
0
0
2.8
2.8
2.8
Differences at
the inlet end of
the hydrophobic
cooler
℃
5.6
5.6
5.6
5.6
5.6
5.6
(4) Other parameters
The efficiency of the heater
980.=ηh
, the mechanical efficiency of the turbine
980.=ηm
, the
efficiency of the generator
990.=ηg
, the coefficient of leakage loss of the whole plant work
material
b
α.=α010
1
, the steam of the shaft seal
020.=αsg
, the inlet temperature of the
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supplemental water
℃
=tma 20
, the specific enthalpy of the supplemental water is
kJ/kg.=hw
，，m
8683
, the inlet pressure of the feed pump is
MPa.=Pin
pu
，u，
252
, the outlet pressure is
MPa.=Pout
pu
，u，
7429
, the efficiency of the feed pump is
0.84=
fwpu，
. Condensate pump inlet
pressure is
KPa=Pin
pu
，u，
11
, outlet pressure is
MPa.=Pout
pu
，u，
33
, small turbine steam coefficient is
0480
1.=αt
, and deaerator arrangement height is 26 m. Shaft seal parameters are shown in
Table 3-2.
Table 2. Shaft seal vapor volume and parameters
Item
Unit
Volume of vapor
kg/h
910.8
Vapor Enthalpy
kJ/kg
3193.2
Destination
SG
4 Comprehensive thermal system development
The N600MW unit of Ningxia Ningdong Power Plant is equipped with a HG-2210/25.4-
YM16 supercritical primary intermediate reheat natural circulation boiler and a CLNJK600-
24.2/566/566 turbine with a rated output of 600MW.
4.1 Preparation of main and reheat steam systems
The main reheat steam system is divided into the single master control system, switching
master control system, and unit system. For equipped with an intermediate reheat condensing
steam unit according to the requirements of the choice of the unit system, the unit system not
only has a relatively simple system, short piping, but valves can also save a lot of high-grade
heat-resistant alloy steel and other characteristics, and accidents are limited to this unit, high
safety and reliability.
The reheat unit of the main steam, reheat steam system has a total of four types; dual-pipe
system, single pipe - dual-pipe system, the main steam dual-pipe - single pipe - dual-pipe,
reheat steam dual-pipe system, and the main steam and reheat steam are dual-pipe - single
pipe - dual-pipe system. In this design, both are selected in the form of "double tube - single
tube - double tube", which has the effect of cost savings to reduce the pressure drop and the
cylinder temperature difference between the stress and friction of the shaft seal.
4.2 Formulation of the bypass system
The bypass system is divided into a three-stage bypass system, a two-stage bypass series
system, a two-stage bypass parallel system, and a one-stage bypass system. In this design,
the bypass system adopts a two-stage bypass series system, which can satisfy various
requirements during startup through the coordination of a two-stage bypass system. The
whole bypass system can also coordinate the startup parameters and flow, shorten the startup
time, prolong the turbine's life, protect the work quality, reduce the noise, prevent the boiler
from overpressure, and balance the steam balance between the boiler and the turbine.
sg
D
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4.3 Preparation of steam extraction and heat recovery system for steam
turbine
According to the design requirements, the unit adopts a 7-stage heat return system, which
consists of 3-stage high-pressure heaters, a 1-stage deaerator, and 3-stage low-pressure
heaters. All the heaters are hydrophobic under normal working conditions by adopting self -
flow mode step by step. High-pressure cylinder pumping and high-pressure cylinder exhaust
steam for No. 1 and No. 2 high-pressure heater respectively; medium-pressure cylinder
pumping and medium-pressure cylinder exhaust steam for No. 3 high-pressure heater and
deaerator; low-pressure cylinder pumping for No. 5~7 low-pressure heater. There is also a
shaft seal heater between the condenser and the No. 7 low-pressure heater. The deaerator
adopts sliding pressure operation mode.
4.4 Preparation of water supply systems
The water supply system is divided into a single master control system, a switching master
control system, unit system. As the design of the 600MW unit of the main steam piping is a
unitary system, the choice of water supply system is also a unitary system, The advantages
and disadvantages of the same with the main steam piping system, the system is relatively
simple, short piping, fewer valves, the cost of spending less money to facilitate the centralized
control of the machine and furnace and management and maintenance.
4.5 Preparation of the condensate system
The condensate system selected is the main condensate system, The main role of the
condensate system is to send condensate from the condenser hot well to the deaerator,
charging the vapor loss in the process of thermal cycle.
The 600MW unit operation feed pump is equipped with two sets of steam feed pumps
with 50% capacity of maximum feed water and one set of speed-regulated electric feed
pumps with 25%-30% capacity of maximum feed water as the startup and backup feed pump.
This design uses a 50% capacity of the main steam feed pump and a 30% capacity of the
electric feed pump; the main feed pump front pump is driven by the motor, the electric
standby feed pump front pump and the electric pump is driven by the same motor; the electric
feed pump is usually used in the start-up or low load conditions, the pump is also used as a
standby pump.
5 Selection of auxiliary equipment for the unit
5.1 Configuration and selection of feed pumps
According to the design specifications, the Ningxia Ningdong Power Plant N600MW unit is
suitable for the configuration of two capacities of 50% of the maximum water supply steam
feed pump and a capacity of 25% -30% of the maximum water supply speed control electric
feed pumps for the start there is a standby feed pump.
The total DC feed pump outlet flow rate is 110% of the maximum continuous evaporation
of the boiler.
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5.2 Configuration and selection of condensate pumps
Ningxia Ningdong Power Plant shall have 2 condensate pumps. The capacity of each
condensate pump shall be 100% of the maximum amount of condensate, and one of them
shall be standby.
5.3 Configuration options for deaerator and feedwater tanks
Deaerator-rated output depends mainly on the unit's maximum feed water consumption, In
the system heat balance calculation is generally taken as 105% of the maximum feed water,
an intermediate reheat condensing unit should be used as a high-pressure deaerator.
6 Conclusion
This design mainly completed the following parts and calculations.
(1) Calculation and checking of the principle system of the power plant, calculation and
checking of each power as well as economic indexes, the thermal efficiency of the
whole plant, of which the standard coal consumption rate is
)]/([2881.0 hkwkgbs
cp
,
the thermal consumption rate of the whole plant is, the thermal efficiency of the whole
plant is
427.0
cp
.
(2) Selection of unit equipment, calculation of outlet flow and head, power, and then
consult the information on the relevant equipment for more appropriate selection.
(3) Calculation and selection of the main steam pipeline, the pressure, temperature, inner
diameter, and wall thickness of the calculation and selection of the appropriate
materials, and then the flow rate calibration.
(4) Comprehensive thermal system development.
In the process of the preliminary design of a thermal system of the N600MW unit of
Ningxia Ningdong Power Plant, some problems with its design have been found, such as the
choice of the hydrophobic method selected for this selection of the step-by-step self-flowing
method, although the system is relatively simple, stable, etc., the disadvantage lies in the poor
thermal economy, which is reflected in the later calculations, and we hope that the design of
the future design will be selected for the hydrophobic pumps to achieve the improvement of
the plant's economy. It is hoped that the hydrophobic pump will be selected in the future
design of the hydrophobic design to achieve the purpose of improving the economy of the
power plant.
Thanks to the other two authors for their contributions to this project.
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