EFFICIENCY IMPROVEMENT IN HEAT-SUPPLY STEAM TURBINE

1

Perica Jukic a, Zvonimir Guzovic b

a Croatian Electric Power Utility Company (HEP), Zagreb, Croatia b University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Zagreb, Croatia

EFFICIENCY IMPROVEMENT IN HEAT-SUPPLY STEAM TURBINE

ABSTRTACT: Efficient use of energy is important for sustainable development, primarily from an

ecological aspect, but also economic and social. Combine heat and power (CHP) plants with installed heat-

supply steam turbines are facilities for achieving high efficiency of the utilization of heat energy generated

by combustion of fossil fuels. In this paper, the common characteristics of the heat-supply steam turbines

are systematized, the basic indicators of their efficiency are defined, and the paths of increase in the specific

conditions of simultaneous production of heat and electricity. The basic features of heat-supply extraction

and heat-supply in general also presented. In addition, the work has indicated the possibility of further

improvement of the operating regimes the heat-supply turbines by introducing a stage-wise heating of

District heating (DH) system water. In concrete example of the heat-supply steam turbine T-100/120-130-

3 located in CHP Power plant TE-TO Zagreb, introducing a stage-wise heating of DH system water and

shown how to utilize the waste heat of the steam in low pressure part of turbine, due to increase its

efficiency. For the purpose of this analysis, has been developed an original computer program with output

operating regimes, which can also be used for other heat-supply steam turbines in the range of 25 to 250

MW.

Keywords: Sustainable development, CHP plant, DH system, Stage-wise heating, Heat-supply steam

turbine, Efficiency, Diagram of operating regimes Nomenclature:

wc kJ/(kgK) specific heat of DH water

wq t/h flow rate of DH water

ww 12 , 0C DH water temperature at the outputs from DH exchanger ZVV1 and ZVV2

pov 0C DH network return temperature

pol 0C DH network supply temperature

1zvvh , 2zvvh , kJ/kg enthalpy of condensate of the lower and upper Heat exchanger

01th , 02th , kJ/kg extraction steam enthalpy upper and lower

t

turD t/h Live steam heat-supply flow rate

k

turD t/h Live steam condensing flow rate

turD t/h Live steam flow rate

01tD t/h flow rate upper extractions of steam to ZVV2

02tD t/h flow rate lower extractions of steam to ZVV1

t

eP MW heat-supply electric power

14. savjetovanje HRO CIGRÉ

Šibenik, 10. − 13. studenoga 2019.

HRVATSKI OGRANAK MEĐUNARODNOG VIJEĆA ZA VELIKE ELEKTROENERGETSKE SUSTAVE – CIGRÉ

X-XX

2

k

eP MW condensing electric power

eP MW generator electric power

tp bar extractions heat-supply pressure

turQ MW steam turbine heat load

toQ MW extractions heat-supply heat load

t

turQ MW heat-supply steam turbine heat load

k

turQ MW condensing steam turbine heat load

eQ MW heat consumption for electricity generation

TE

toQ MW heat load of CHP plant

eQ kJ/kWh specific heat rate for electricity generation

E kWhe/kWht specific generation of electricity by heat-supply flow rate

konQ MW waste heat of steam in condenser

mgzQ MW mechanical, electric generator and radiation losses

1. Introduction

Integration into the DH system of renewable energy sources (RES), the use of waste heat, cogeneration

heat, is one of the key points of Directive 2012/27/ EU on energy efficiency [1]. Increasing energy

efficiency contributes to the approach "total energy use", which is available in the system, and includes the

use of the overall thermal energy at different temperature levels. Highly efficient cogeneration and DH

systems [2] have a significant potential for saving primary energy that is still insufficiently used in the

European Union. They also represent a very important factor in planning future energy systems to increase

flexibility and enable a higher level of exploitation of intermittent renewable energy sources such as wind

and photovoltaic systems [3]. Renewable Energy (OIE) plays an increasingly important role in reducing

the fossil fuel consumption in the DH system and mitigating the environmental impact. CHP systems with

RES and energy storage system (ESS) are being investigated. Modelling and optimization methods are

being developed for planning and managing such CHP-DH systems [4].

2. Characterictics of CHP plants and Heat-supply steam turbines

One of the best ways to improving the efficiency of a CHP plants (Fig. 1) is to temperature reduction of the

DH system water with simultaneously utilization the waste heat in the steam turbine condenser [5]. District

heating system should be revitalized to achive the higher level of generations (today is a developed system

of fourth generation) [6] based on a low-temperature regime. The CHP plant can be very efficient if uses

the waste heat of steam in the steam condenser, and if on the CHP plant [7] and on the DH system installed

heat pumps of the corresponding design and capacity [8], and even if the whole system is working combined

with heat storage tanks [4]. Power plant characteristics should ensure the safety of turbine and generator,

especially low pressure turbine blades [9]. Safety operation of the condenser at high cooling water

temperatures can be provided by lowering and switching to low temperature heating system [10]. The

experience acquired in exploitation confirms the possibility of increasing the thermal efficiency with

turbines power higher than 25 MW when using steam heat that goes into the condenser. CHP plants and

associated heat-supply turbines of higher than 50 MW have two heat-supply steam extractions, upper and

lower, intended for stage-wise heating of the DH water system [11] which significantly reduces the loss of

exergy. For turbines with a power greater than 50 MW, possible to use low pressure steam ventilation for

preheating return DH water [8]. This increases the economy and efficiency of the CHP plant [2]. The

construction of the condenser with an additional tube bundle which having an independent water chamber

and a common steam surface area of the base, allows the change the normal mode of operating to the mode

3

of operation using steam ventilation heat, and inversely during the operation of the turbine without its

stopping and limiting power [12].

Fig. 1. Scheme of CHP plant and DH system Fig 2. Heat distribution of heat-supply steam turbine

by utilizing vent. steam heat into condenser

Full recovery of waste heat [13] is an effective approach to increasing heating capacity and reducing

emissions of pollutants in the cogeneration plant. Turbines with two heat-supply extractions have an

extended range of regulated pressure in upper heat-supply extraction ranging from 0.6 to 2.5 bar, which

allows the supply temperature of the DH system from 70 to 125 0C [14]. Specific heat consumption is

defined by the equation e

toture

P

QQQ

, where is turQ -turbine heat consumption, toQ - heat load of heat-

supply extractions. Value of eQ is determined with sufficient accuracy in the turbine test, where is eP the

electric power generated by steam flows through the turbine. For heat-supply steam turbines specific heat

consumption depends on the relationship between the heating and electrical loads and the turbine's

perfection. Referring to Fig. 2, taking into account the general energy equation, can be written:

konmgztoetur QQQPQ (1)

3. Energy characterictics of heat-supply steam turbines

The energy characteristics of the heat-supply steam turbines express the same functional dependence as the

operating mode diagrams, but not in graphic but in analytical form. The operation regimes of the heat-

supply turbines are divided into two groups: condensing and heat-supply. The condensation regimes of the

heat-supply turbines, which include zero-heat load regimes, have independent energy characteristics. At

the heat-supply regime, electrical power and heat distribution are conditional in two flows:

Heat-supply electrical power and heat-supply turbine heat load t

eP , t

turQ

Condensing electrical power and condensing turbine heat load k

eP , k

turQ

Depending on the relationship between thermal and the electric load, the heat-supply regime can be either

a flow or only one heat-supply flow. The condensation power of the heat-supply regime is determined as

the difference between the total and heat-supply power turbo aggregate:

4

k

eP eP t

eP (2)

The condensation heat flow at the heat-supply regimes is determined as the difference between the total

and the heat-supply heat flow:

t

turtur

k

tur QQQ (3)

ZVV2

VVK

3

4

hto1

S

pol 2w 1w pov

ZVV1

3 3

to2h

pt1

to1 D

to2

p

D

t2

2

1 1

The most important facts related to heat-supply extractions and heat-supply are heat load, stage-wise

heating of the DH water (Fig. 3), reduction of the steam pressure extraction and use of waste steam heat

that goes into the condenser [8]. Heat-supply turbines are designed for stage-wise heating and work on a

heat diagram with nominal heat load to provide additional electricity generation during the heating period.

The Heat load of CHP plant and the parameters of the DH water are connected by the equation:

)( povpolww

TE

to cqQ (4)

Where are: TE

toQ - Heat load of CHP plant; pol and pov - temperature supply and return DH network

water. The ratio of the extractions heat-supply heat load and the total heat load of CHP plant at the minimum

ambient air temperature is called the heat-supply coefficient TE . Temperature diagram of DH system and

accepted heat-supply coefficient, determine the DH water temperature w2 behind the basic DH heaters,

which are supplied by steam from the heat extractions. At the minimum ambient air temperature w2 is

determined directly from the known relationship for TE :

w2 )( povpolpov TE (5)

For any ambient air temperature it is worth it:

w2ww

topov

cq

Q (6)

For part of DH period, when the peak boiler is turned off and all of the heat load for CHP plant and district

heating covers with turbine heat-supply extractions, follows that w2 pol . The additional power,

obtained by two-stage of heating (compared to a single-stage of heating) with steam flow, which goes into

lower heat-supply extraction, is:

mgtototoII hhDP .212 )( (7)

where: 2toD - extraction steam rate to a DH heater (the numbering of the heat-supply extractions are in the

direction of the steam flow through the turbine, while the heaters numbering are in the direction of the DH

Fig 3. The principle P&D stage-wise heating

t01-upper heat-supply extraction;

t02-lower heat-supply extraction;

----------- DH water ;

- - - - - - - condensate;

------------ steam extractions

1- DH heaters ZVV1,2;

2-pick hot water boiler;

3-regenerative heaters; 4-turbine

5

water flow). In the afterwards heating in the Regenerative Low Pressure Heater (ZNT) enthalpy the

condensate of DH heater ZVV1 increases from 1zvvh to 2zvvh , for which it is necessary to consume the heat:

)( 1221 zvvzvvto hhDQ (8)

in the form of additional, over the network of DH water required, extraction of steam from upper heat-

supply extractions. With the steam of additional extractions the power is obtained:

11 QEPI (9)

where: 1E - specific generation of electricity by heat-supply flow rate at single-stage of heating. In this

way, when switching from single to two-stage of heating with unchanged heating load, provides additional

electrical power:

PIP IIP

and additional specific generation of electricity by heat-supply flow rate:

toQ

PE

2

(10)

4. Heat-supply steam turbine T-100-110/130-3 operating regimes

4.1. Design of the regime diagram

Turbine T-100-130 operation diagram based on actual operating data, normative data and other

measurements at CHP Power Plants Zagreb (TE-TO Zagreb), also on the basis of project materials obtained

from UTMZ turbine manufacturers. Heat-supply regime with single-stage of heating is used when heat load

up to 120 MW and when pressure in upper stage of heating begins to increase significantly. Then it goes to

work with a one heater a lower stage due to stop the increase specific heat consumption and significantly

reduce the additional electricity generation on the basis of heat demand. The two-stage heating mode is

used when the need heat load at least 120 MW. Based on the algorithm, a program is written by which all

possible modes of operation are calculated and displayed in the form of an output text file. On the basis of

the results it can be concluded that the heat-supply regimes of operation on the heat diagram is most

economical, as the specific heat consumption is the smallest, or the largest power plant efficiency.

4.2. Single-stage of heating

The dependence of the heat-supply steam flow and heat-supply electrical power on the heat load and the

pressure in lower heat-supply steam extraction, are shown in Fig. 4.2.a, b.

Generally, the heat-supply steam flow at single-stage of heating can be represented by the following

equation:

jed

D

jed

to

jed

D

jed

to

jed

D

t

tur cQbQaDjed

2)( (4.2)

Parameters jed

D

jed

D

jed

D cba ,, are changed depending on the lower extraction pressure and can be

displayed in graphic form and interpolated with the fourth and third degree polynomials. Final analytic

expressions have the form:

6

Fig. 4.2.a,b. Turbine T-100-130 heat-supply performance curves for single-stage heating DH water:

Functional dependence of the heat-supply steam flow (a) and the heat-supply electrical power (b)

on the heat load and the lower extraction pressure

005222.0001496.0001757.000419.0001516.0 2

2

2

3

2

4

2 ttptt

jed

D ppppa (4.3)

896051.0619656.1721814.1522868.0 2

2

2

3

2 ttpt

jed

D pppb (4.4)

119.1938273.2648524.5096528.15 2

2

2

3

2 ttt

jed

D pppc (4.5)

Generally, the heat-supply electrical power at single-stage of heating can be represented by the following

equation:

jed

P

jed

to

jed

P

jed

to

jed

P

t

e cQbQaPjed

2)( (4.6)

Parameters jed

P

jed

P

jed

P cba ,, are changed depending on the extraction pressure and can be displayed in

graphic form and interpolated with the fourth and fifth degree polynomials:

002922.0012352.0026297.0023971.0009869.0001515.0 2

2

2

3

2

4

2

5

2 ttttt

jed

P pppppa (4.7)

359488.0433281.0082952.178443.0177584.0 2

2

2

3

2

4

2 tttt

jed

P ppppb (4.8)

9265.2781365.11171874.19104701.17039322.759778.12 2

2

2

3

2

4

2

5

2 ttttt

jed

P pppppc (4.9)

4.3. Two-stage of heating


pressure in upper heat-supply steam extraction, are shown in Fig. 4.3.a,b.

The heat-supply steam flow at two-stage of heating can be represented by the following equation:

dvo

D

dvo

to

dvo

D

dvo

to

dvo

D

t

tur cQbQaDdvo

2)( (4.10)

Parameters dvo

D

dvo

D

dvo

D cba ,, are changed depending on the upper extraction pressure and can be displayed

in graphic form and interpolated with fifth degree polynomials:

Jednostupanjsko zagrijavanje

DNT zatvorena

Dttur = 0.004464Qto

2 + 1.340714Qto + 16.60

Dttur = 0.004643Qto

2 + 1.317143Qto + 27.00

Dttur = 0.005357Qto

2 + 1.222857Qto + 37.80

Dttur = 0.005357Qto

2 + 1.282857Qto + 41.60

Dttur = 0.004464Qto

2 + 1.430714Qto + 40.80

60.0

70.0

80.0

90.0

100.0

110.0

120.0

130.0

140.0

150.0

160.0

170.0

180.0

190.0

200.0

210.0

220.0

230.0

240.0

250.0

260.0

270.0

280.0

290.0

40.0 50.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0

Toplinska snaga Qto [MW]

To

plif

ika

cijs

ki p

roto

k D

t tur

[t/h

]

Dttur(0,5)

Dttur(1,0)

Dttur(1,4)

Dttur(1,8)

Dttur(2,0)

Poly.

Poly.

(Dttur(0,5)

)Poly.

(Dttur(1,0)

)Poly.

(Dttur(1,4)

)Poly.

(Dttur(1,8)

)Poly.

(Dttur(2,0)

)

Jednostupanjsko zagrijavanje

DNT zatvorena

Pte = 0.000982Qto

2 + 0.385357Qto - 2.90

Pte = 0.001179Qto

2 + 0.328429Qto - 0.80

Pte = 0.001161Qto

2 + 0.314786Qto - 0.38

Pte = 0.001071Qto

2 + 0.340571Qto - 2.34

Pte = 0.001071Qto

2 + 0.328571Qto - 1.80

Pte = 0.001143Qto

2 + 0.343143Qto - 0.74

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

55.0

60.0

40.0 50.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0


To

plif

ika

cijs

ka

ele

ktr

ičn

a s

na

ga

Pt e

[M

W]

Pte(0,5)

Pte(1,0)

Pte(1,4)

Pte(1,8)

Pte(2,0)

Pte(0,8)

Poly.

(Pte(0,5))Poly.

(Pte(1,0))Poly.

(Pte(1,4))Poly.

(Pte(1,8))Poly.

(Pte(2,0))Poly.

(Pte(0,8))

a

)

)

b

)

)

7

Fig. 4.3.a,b. Turbine T-100-130 heat-supply curves for two-stage heating DH water: Functional dependence of the

heat-supply steam flow (a) and the heat-supply electrical power (b) on the heat load and the upper extraction

pressure

008073.0015333.0051103.005743.0025966.0004119.0 1

2

1

3

1

4

1

5

1 ttttt

dvo

D pppppa (4.11)

917671.0186251.4060567.15222733.17872131.7259133.1 1

2

1

3

1

4

1

5

1 ttttt

dvo

D pppppb (4.12)

73158.1277944.27377346.107244892.12371809.57254839.92 1

2

1

3

1

4

1

5

1 ttttt

dvo

D pppppc (4.13)

The heat-supply electrical power at single-stage of heating can be represented by the following equation:

dvo

P

dvo

to

dvo

P

dvo

to

dvo

P

t

e cQbQaPdvo

2)( (4.14)

Parameters dvo

P

dvo

P

dvo

P cba ,, are changed depending on the upper extraction pressure and in the graphical

form are interpolated with the polynomials of the second degree in the range of 0.6 to 1.4 bar and fifth

degree polynomials in the pressure range of 1.4 to 2.5 bar:

001499.0001145.0000428.0 1

2

1 tt

dvo

P ppa (4.15a)

444287.0208139.1287444.1673167.0172862.001746.0 1

2

1

3

1

4

1

5

1 ttttt

dvo

P pppppa (4.15b)

386902.0212762.0100437.0 1

2

1 tt

dvo

P ppb (4.16a)

85117.15614618.42201589.44857253.233848.5903471.6 1

2

1

3

1

4

1

5

1 ttttt

dvo

P pppppb (4.16b)

5197.79851.84641.4 1

2

1 tt

dvo

P ppc (4.17a)

43274.105600162.2845754742.3015788113.1568605631.40061153.402 1

2

1

3

1

4

1

5

1 ttttt

dvo

P pppppc (4.17b)

4.4. Three stage of heating – utilize the steam waste heat in low pressure part of turbine


pressure in upper heat-supply steam extraction, are shown in Fig. 4.4.a,b.

Generally, the heat-supply steam flow of a three-stage heating can be represented by a first degree

polynomial or straight line equation:

tro

D

tro

to

tro

D

t

tur bQaDtro

(4.18)

Parameters tro

D

tro

D ba , are changed depending on the upper extraction pressure and can be displayed in

graphic form and interpolated with fifth degree polynomials:

Dvostupanjsko zagrijavanje

DNT zatvorena

Dttur = 0.00617Qto

2 + 1.10361Qto + 60.36201

Dttur = 0.00587Qto

2 + 1.25335Qto + 36.67407

Dttur = 0.00678Qto

2 + 1.04923Qto + 36.85924

Dttur = 0.00826Qto

2 + 0.65309Qto + 53.90920

Dttur = 0.00791Qto

2 + 0.80541Qto + 34.33148

Dttur = 0.00387Qto

2 + 1.81701Qto + 10.86598

220

240

260

280

300

320

340

360

380

400

420

440

460

480

500

120 130 140 150 160 170 180 190


Topl

ifika

cijs

ki p

roto

k D

t tur [

t/h] Dttur(0,6)

Dttur(1,0)

Dttur(1,4)

Dttur(1,8)

Dttur(2,2)

Dttur(2,5)

Poly.

(Dttur(2,2

))Poly.

(Dttur(1,8

))Poly.

(Dttur(1,4

))Poly.

(Dttur(1,0

))Poly.

(Dttur(0,6

))Poly.

(Dttur(2,5

))

Dvostupanjsko zagrijavanje

DNT zatvorena

Pte = 0.000966Qto

2 + 0.478402Qto - 11.303727

Pte = 0.000782Qto

2 + 0.499227Qto - 12.040761

Pte = 0.000735Qto

2 + 0.487912Qto - 11.349286

Pte = 0.000226Qto

2 + 0.602088Qto - 18.585329

Pte = 0.000730Qto

2 + 0.410979Qto - 3.866574

Pte = 0.000431Qto

2 + 0.498144Qto - 12.399366

50

60

70

80

90

100

110

120

120 130 140 150 160 170 180 190


Topl

ifika

cijs

ka e

lekt

ričn

a sn

aga

Pt e M

W

Pte(0,6)

Pte(1,0)

Pte(1,4)

Pte(1,8)

Pte(2,2)

Pte(2,5)

Poly.

(Pte(0,6)

)Poly.

(Pte(1,0)

)Poly.

(Pte(1,4)

)Poly.

(Pte(1,8)

)Poly.

(Pte(2,2)

)Poly.

(Pte(2,5)

)

a

)

)

b

)

)

8

Fig. 4.4.a,b.: Turbine T-100-130 heat-supply performance curves for three-stage heating DH water:

Functional dependence of the heat-supply steam flow (a) and the heat-supply electrical power (b)

on the heat load and the upper extraction pressure

62826.209535.380659.457742.329262.11781.0 1

2

1

3

1

4

1

5

1 ttttt

tro

D pppppa (4.19)

25737.3098336.61541964.89818853.67213565.24464469.33 1

2

1

3

1

4

1

5

1 ttttt

tro

D pppppb (4.20)

The heat-supply electric power of a three-stage heating can be shown similarly to single-stage and two-

stage of heating, with the following equation:

tro

P

tro

to

tro

P

tro

to

tro

P

t

e cQbQaPtro

2)( (4.21)

Parameters tro

P

tro

P

tro

P cba ,, are changed depending on the upper extraction pressure and in the graphical

form are interpolated with the polynomials of the second degree in the range of 0.6 to 1.4 bar and third

degree polynomials in the pressure range of 1.4 to 2.5 bar:

004115.0005452.0002008.0 1

2

1 tt

tro

P ppa (4.22a)

042543.0062717.0029495.0004538.0 1

2

1

3

1 ttt

tro

P pppa (4.22b)

332762.2115294.2789906.0 1

2

1 tt

tro

P ppb (4.23a)

75521.1215688.2055476.947381.1 1

2

1

3

1 ttt

tro

P pppb (4.23b)

9911.1619443.1572774.62 1

2

1 tt

tro

P ppc (4.24a)

9814.13166956.20202470.9530893.147 1

2

1

3

1 ttt

tro

P pppc (4.24b)

5. The results; single-stage, two-stage and three-stage DH system heating

5.1. Results single stage of heating

pt2 Qjed Dtjed Ptjed Dkjed Djed Pjed Q1tur qjedn

[bar] [MWt] [t/h] [MWe] [t/h] [t/h] [MWe] [MWt] [kJ/kWh]

.500 .4000E+02 .7733E+02 .1412E+02 .1000E+02 .8733E+02 .1705E+02 .6149E+02 .4539E+04

.500 .4000E+02 .7733E+02 .1412E+02 .2000E+02 .9733E+02 .1997E+02 .6853E+02 .5144E+04

.500 .4000E+02 .7733E+02 .1412E+02 .3000E+02 .1073E+03 .2289E+02 .7558E+02 .5595E+04

Trostupanjsko zagrijavanje, DNT zatvorena

Dttur = 3.3750Qto - 192.75

Dttur = 3.3850Qto - 210.55

Dttur = 3.3450Qto - 218.35

Dttur = 3.2900Qto - 222.20

Dttur = 3.1600Qto - 208.30

Dttur = 3.1200Qto - 206.60

160.0

180.0

200.0

220.0

240.0

260.0

280.0

300.0

320.0

340.0

360.0

380.0

400.0

420.0

440.0

460.0

480.0

500.0

520.0

150.0 160.0 170.0 180.0 190.0 200.0 210.0


To

plifi

ka

cijs

ki p

roto

k D

t tur [t

/h]

Dttur(0,6)

Dttur(1,0)

Dttur(1,4)

Dttur(1,8)

Dttur(2,2)

Dttur(2,5)

Linear

(Dttur(0,6

))Linear

(Dttur(1,0

))Linear

(Dttur(1,4

))Linear

(Dttur(1,8

))Linear

(Dttur(2,2

))Linear

(Dttur(2,5

))

Trostupanjsko zagrijvanje, DNT zatvorena

Pte = -0.001562Qto

2 + 1.345000Qto - 89.568750

Pte = -0.000688Qto

2 + 1.018000Qto - 66.596250

Pte = -0.000375Qto

2 + 0.893000Qto - 62.2525

Pte = -0.001250Qto

2 + 1.165000Qto - 89.5750

Pte = -0.001000Qto

2 + 1.038000Qto - 81.0400

Pte = -0.000813Qto

2 + 0.9480Qto - 75.233750

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

110.0

120.0

130.0

150.0 160.0 170.0 180.0 190.0 200.0 210.0


To

plifi

ka

cijs

ka

el. s

na

ga

Pt e

[M

W]

Pte(0,6)

Pte(1,0)

Pte(1,4)

Pte(1,8)

Pte(2,2)

Pte(2,5)

Poly.

(Pte(0,6

))Poly.

(Pte(1,0

))Poly.

(Pte(1,4

))Poly.

(Pte(1,8

))Poly.

(Pte(2,2

))Poly.

(Pte(2,5

))

a

)

)

b

)

)

9

.500 .1200E+03 .2417E+03 .5695E+02 .2300E+03 .4717E+03 .1155E+03 .3322E+03 .6610E+04

.500 .1200E+03 .2417E+03 .5695E+02 .2400E+03 .4817E+03 .1178E+03 .3392E+03 .6699E+04

.500 .1200E+03 .2417E+03 .5695E+02 .2500E+03 .4917E+03 .1201E+03 .3463E+03 .6784E+04

.

2.000 .4000E+02 .1050E+03 .1303E+02 .1000E+02 .1150E+03 .2563E+02 .8095E+02 .5752E+04

2.000 .4000E+02 .1050E+03 .1303E+02 .2000E+02 .1250E+03 .2812E+02 .8799E+02 .6144E+04

2.000 .4000E+02 .1050E+03 .1303E+02 .3000E+02 .1350E+03 .3062E+02 .9503E+02 .6471E+04

.

2.000 .1200E+03 .2766E+03 .5289E+02 .2000E+03 .4766E+03 .1055E+03 .3356E+03 .7359E+04

2.000 .1200E+03 .2766E+03 .5289E+02 .2100E+03 .4866E+03 .1080E+03 .3427E+03 .7423E+04

2.000 .1200E+03 .2766E+03 .5289E+02 .2200E+03 .4966E+03 .1105E+03 .3497E+03 .7485E+04

5.2. Results two-stage of heating

pt1 Qdvo Dtdvo Ptdvo Dkdvo Ddvo Pdvo Q2tur qdvos

[bar] [MWt] [t/h] [MWe] [t/h] [t/h] [MWe] [MWt] [kJ/kWh]

.600 .1200E+03 .2449E+03 .6002E+02 .1000E+02 .2549E+03 .6294E+02 .1795E+03 .3615E+04

.600 .1200E+03 .2449E+03 .6002E+02 .2000E+02 .2649E+03 .6586E+02 .1865E+03 .3636E+04

.600 .1200E+03 .2449E+03 .6002E+02 .3000E+02 .2749E+03 .6879E+02 .1936E+03 .3850E+04

.

.600 .1800E+03 .4356E+03 .1061E+03 .6000E+02 .4956E+03 .1211E+03 .3490E+03 .5025E+04

.600 .1900E+03 .4729E+03 .1145E+03 .1000E+02 .4829E+03 .1170E+03 .3401E+03 .4619E+04

.600 .1900E+03 .4729E+03 .1145E+03 .2000E+02 .4929E+03 .1195E+03 .3471E+03 .4734E+04

.

2.500 .1200E+03 .2842E+03 .5355E+02 .1000E+02 .2942E+03 .5844E+02 .2072E+03 .5371E+04

2.500 .1200E+03 .2842E+03 .5355E+02 .2000E+02 .3042E+03 .6093E+02 .2142E+03 .5567E+04

2.500 .1200E+03 .2842E+03 .5355E+02 .3000E+02 .3142E+03 .6343E+02 .2213E+03 .5748E+04

.

2.500 .1800E+03 .4624E+03 .9120E+02 .1000E+02 .4724E+03 .9370E+02 .3326E+03 .5865E+04

2.500 .1800E+03 .4624E+03 .9120E+02 .2000E+02 .4824E+03 .9619E+02 .3397E+03 .5976E+04

2.500 .1800E+03 .4624E+03 .9120E+02 .3000E+02 .4924E+03 .9868E+02 .3467E+03 .6082E+04

5.3. Results three-stage of heating

pt1 Qtro Dttro Pttro Q3tur qtros

[bar] [MWt] [t/h] [MWe] [MWt] [kJ/kWh]

.600 .1800E+03 .4148E+03 .1022E+03 .2921E+03 .3946E+04

.600 .1900E+03 .4485E+03 .1099E+03 .3158E+03 .4121E+04

.600 .2000E+03 .4822E+03 .1173E+03 .3396E+03 .4285E+04

.600 .2100E+03 .5160E+03 .1243E+03 .3633E+03 .4440E+04

.

2.500 .1800E+03 .3549E+03 .6910E+02 .2499E+03 .3642E+04

2.500 .1900E+03 .3861E+03 .7558E+02 .2719E+03 .3901E+04

2.500 .2000E+03 .4173E+03 .8189E+02 .2939E+03 .4127E+04

2.500 .2100E+03 .4486E+03 .8804E+02 .3159E+03 .4329E+04

6. Conclusion

Considering this techno-economic area, most of the different operational targets, district heating systems

(DHs) and Combine Heat and Power plants (CHPs) in the future must find a way to cover costs and to work

efficiently. For a T-100/120-130-3 type turbine based on actual data, normative data, other measurements

data, and on the basis of theoretical knowledge, a uniform diagram the mode of operation in the graphic

form was prepared, from which all possible operating modes can be read. A complete diagram is translated

and described by analytical dependencies in the form of energy characteristics. Based on the algorithm, a

program is written by which all possible modes of operation are calculated and displayed in the form of an

10

output text file. From the output data it can be concluded that the heat-supply operating regimes of the heat

diagram are most economical, as the specific heat consumption is the smallest, or the largest power plant

efficiency. Also, the algorithm derived from the operating regime diagram of heat-supply steam turbine T-

100/120-130-3 can be used to construct diagram of the operating regime for other heat-supply steam

turbines in range of 25 to 250 MW. The average specific heat consumption at mode of operation when

utilize steam waste heat in the condenser is 3850 kJ/kWh or 94% efficiency. For the steam turbine T-100-

130, which operates at TETO Zagreb beginning of November to the end of February, possible to save about

3x106 m3 of natural gas, and reduce 6x103 tons of CO2, compared to the operating regime without the use

the steam waste heat in the turbine condenser.

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Documents

EFFICIENCY IMPROVEMENT IN HEAT-SUPPLY STEAM TURBINE