Developing of an Info-communication Technology for the Operating and Controlling of a Saturated Steam Network

Lajos Szakonyi – Péter Iványi – Zoltán Sári

University of Pécs, Pollack Mihály Faculty of Engineering, Department of Information Technology

Goals: Presenting the measurement and simulation techniques developed for a two-phase flow to quantify and qualify a steam network and to determine the flow regime in the network connected to the tasks of an EU-supported project (GVOP-3.1.1.-2004-05-0125/3.0.)

The technological basis of the research 13 km long citywide steam network with pipe diameters between DN50 and DN450, the network distributes approximately 130 thousand tonnes of steam to different parts of the city

The info-communication system of the applied research:The monitoring system of the steam network completed with the planned new measuring sites (denoted by M).

The monitoring system and the installed measuring devices

Data

DISZPÉCSERKözpont Modem

ETHERNET

Felügyeleti Központ

GSM Hálózat

GSM MODEM

GSM MODEM

Kézi adatbevitel

Mérőállomások

GSM MODEM

INTERNET

GSM Hálózat

Kondenzátum Mérés

PTE ROUTER

Akusztikus mérőrendszer

GSM MODEM

Operátori állomások

The established experimental info-communication system

Supervisory Center

Operator Stations

Manual data input

Dispatcher Center

Acoustic measuring

system

Measuring Sites

GSM Network

GSM Network

Condensate measureme

nt

The goals and main tasks of the project work

The investigation, modelling and simulation of the network justified the establishment and application of a geographic information system. In order to accomplish the development goals, our department aimed to develop

an info-communication system for the experimental identification and supervision of energy distribution,

a simulation framework which is capable of modelling the system with variable sources, resistances and consumption,

an operational software package for varying topologies and operational states, an expert system connected to the operational software based on mathematical models.

The reasons behind the development of the intelligent monitoring system

The identification measurements of the steam network indicated a two-phase flow (wet steam) under working conditions. Furthermore in a reduced operating mode of the distribution steam network the output of the power plant and the measured consumption of the consumers showed a large difference, which indicated the limitations of the current monitoring system, the lack of the measurements of the condensation and the inaccuracy of the measurements of the steam flow. The following tasks have been performed in the research :

the geometry, topology and the data corresponding to the junctions and branches of the network have been recorded, visualized and archived;

tracing and characterization of the two-phase flow and condensation; determination of material properties (thickness of the film, thermal conductivity, heat transfer

coefficient, shear stress etc.), properties of state of operation (velocity distribution, vapor/liquid volume fraction, critical velocity of steam, etc.), state of flow (layered, annular, spray);

development of evaluation methods for the signals of the special sensors (volume flow meter operating as a condensator, flow meter based on dynamic pressure measurement, mass flow meter based on an acoustic approach).

The design and building instructions of the special flow sensors

The installation of the special flow meter

Placement of the measurement sensors for the intelligent monitoring system

The installation and schematics of the measuring sites

Installation of the acoustic condensate measuring device

The devices of the dispatcher center

Evaluation of the measurement results assuming a “homogenous model” (a) and a „slip model” (b)

In order to describe the separate flow of the two phases, the volume occupied by both phases and the measurement based value of the volume fractions , and (1- ) has to be known. The Pitot-tube-type flow meters are eligible for obtaining the volume fractions and the occupied volumes

(a) (b)

Meas. series

Velocities assuming „slip model” Geometric constants corresponding to the volume

occupied by the condensate

1. 0,005 0,8223 0,1030 1,2364 0,8305 0,4030 0,8214 0,0215557 169 0,11290

2. 0,007 0,9102 0,2112 1,3439 0,9299 0,4569 0,9083 0,0189496 160 0,10318

3. 0,008 1,0751 0,1996 1,6127 1,0751 0,5376 1,0728 0,0200816 165 0,10852

4. 0,016 1,5874 0,5225 2,7885 1,1194 0,7042 1,5340 0,0163171 149 0,09148

5. 0,016 1,5575 0,5170 2,8490 1,1194 0,7042 1,5541 0,0165091 150 0,09253

6. 0,017 1,9082 0,5173 3,7140 1,1759 0,8346 1,9040 0,0179959 155 0,09784

7. 0,022 2,2172 0,7285 4,1910 1,5912 0,8695 2,2124 0,0165921 150 0,09253

8. 0,024 3,1442 0,6303 4,6256 3,8032 1,0039 3,1374 0,0197200 163 0,10639

9. 0,025 3,5193 0,5955 5,3020 4,2520 1,0039 3,5116 0,0204824 166 0,10960

10. 0,017 1,6402 0,3941 3,7430 0,8504 0,3271 1,6366 0,0187895 160 0,10318

11. 0,022 1,5185 0,4290 3,9546 0,4487 0,1521 1,5152 0,0178155 155 0,09784

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Conclusion

The requirements of the investigation of the two-phase flow in order to ensure the correct scoring of energy are the followings:

development and operating of special flow meters (Pitot-pipe-type, capable of following the local velocity distribution),

developing of computational methods for the processing and evaluation of the data provided by the above devices,

calculation methods, in order to obtain information about the flow regime, and for the estimation of the characteristic values of the flow.

The construction and development of the above devices and methods have provided the strategic background for the establishment of an intelligent monitoring and expert system which ensures that:

by the execution of the computational model the different states of the network can be simulated; by using the principal of the local dynamic pressure measurement the distribution of the velocity in

the cross-section of the pipes near the measurement points can be determined; the mass transfer in the condense vessels can be determined in the backbone pipes; by using mobile communication the measured data can be transferred immediately to the

monitoring system; and algorithms and formulas can be created to determine the quality of the two-phase flow.