7.44.Session VI EHa and LTr Process Flow and Steam Gathering System v3

7/25/2019 7.44.Session VI EHa and LTr Process Flow and Steam Gathering System v3

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Process flow and gathering

system

Session VI

Eln Hallgrmsdttir and Lilja TryggvadttirMannvit Strasbourg, Nov.8, 2012


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Presentation overview

Presentations reviewing different work cycles

Main concept of the gathering system

Calculated example showing methods usedwithin geothermal steam gathering system

design


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Geothermal in Iceland


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Process flow

A review of thermodynamic cycles used in

geothermal energy production with emphasis

on electricity generation

Flash steam cycles with single flash and

double flash as well as different binary cycles

as ORC and Kalina Cycle are introduced and

compared


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Back Pressure Steam Power Plant

Steam

separator

Turbine Generator

G

Production wells Reinjection wells

Phigh

Plow

2 phase flow Vapor

Liquid


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Back pressure unit - layoutSeparator

Machine Hall

Electrical cabinets &

Control room

Asphalted area for installation and maintenance purposes


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0

100

200

300

400

500

600

700

00,20,40,60,811,2

TurbinePower[kJ/kg]

Turbine outlet pressure [bara]

Calculated examples

Different turbine outlet pressure


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G

Production wells

Geothermal

fluidSteam

separator

Turbine

Condenser

SteamGenerator

Silencer

Mist

eliminator

Water

Condensate

Condensate

Cooling tower

Reinjection wells

Gas Extraction System

Steam Power Plant with Condenser


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Steam Power PlantDouble Pressure

G

Production wells

Two phaseflow Turbine - generatorHP steam

LP steam

Reinjection wells

Condenser Tcw

Cooling system

Steamseparator

LP Steam

separator

Two

phase

flow


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SvartsengitheOctopus


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Steam Power PlantDouble Flash


G

Steam supply systemTurbine - generator

Primary steam

Secondary steam

Condenser Tcw

Cooling system

G

LP Turbine - generator

Tcw

Cooling system

Steam

separator

LP Steam

separator


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Hellisheiilow pressure unit


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Steam Power Plant w. District Heating

G

Production wells

Steam supply system Turbine - generatorPrimary steam

Reinjection wells

Condenser

Tcw

Cooling system

Steam

separator

District

heating

system

Freshwater wells

To district

heating


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District heating plant


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25. 02. 2008

Production wells

Two phase flow

Steam separators

Geothermal water

Steam

Well head silencers

Re-injection wells

Pressure

regulation

Geothermal water

emergency exhaust

Turbines

Generators

Mist separators

Cooling

towers

Hot water tank

Cold water pump

Condensers

Heat exchangers

De-aerators

De-aerators

Condensers

Process Flow Diagram


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GTsource

Tdischarge

Phigh

Plow

Condenser

Turbine Generator

Circulation pump

Evaporator

Tcw

Cooling system

Binary Cycles


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GTsource

Tdischarge

Phigh

Plow

TcwCondenser

Turbine Generator

Circulation pump

Evaporator

Recuperator

Cooling system

Binary Cycleswith Recuperation


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Binary Plant BerlinEl Salvador

LaGeo


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G

Separator

High temp

recuperator

Low temp

recuperator

Condenser

Evaporator

TurbineGenerator

Tsource

Tdischarge

Tcw

Circulation pump

Cooling system

Binary CyclesKalina


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Hsavik Kalina plant


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20 02 5 03 0 035 040 04 5 05 0 055 0

2 0

4 0

6 0

8 0

1 0 0

1 2 0

1 4 0

Heat transfer

Temper

ature

0 0 , 2 0 , 4 0 , 6 0, 8 1

5 0

6 0

7 0

8 0

9 0

1 0 0

1 1 0

1 2 0

Heat Transfer

Temperature

ORC Kalina


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G

Tsource

Tdischarge

Coolingsystem

Binary CyclesKalex


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Work Cycle Comparison

Specific Power


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0

2

4

6

8

10

12

80 85 90 95 100 105 110 115 120 125 130

/W

Inlet Temperature [C]

Kalina

Kalex

ORC

Work Cycle Cost Comparison


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G

G

G

Steam supply system Turbine - generator

Primary binary

turbine - generator

Evaporator

Secondary binaryturbine - generator

Cooling system

Cooling system



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Demonstration of model

Turboden ORC model:

http://www.turboden.eu/en/rankine/rankine-

calculator.php
http://www.turboden.eu/en/rankine/rankine-calculator.phphttp://www.turboden.eu/en/rankine/rankine-calculator.phphttp://www.turboden.eu/en/rankine/rankine-calculator.phphttp://www.turboden.eu/en/rankine/rankine-calculator.phphttp://www.turboden.eu/en/rankine/rankine-calculator.phphttp://www.turboden.eu/en/rankine/rankine-calculator.phphttp://www.turboden.eu/en/rankine/rankine-calculator.phphttp://www.turboden.eu/en/rankine/rankine-calculator.phphttp://www.turboden.eu/en/rankine/rankine-calculator.phphttp://www.turboden.eu/en/rankine/rankine-calculator.phphttp://www.turboden.eu/en/rankine/rankine-calculator.php


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Gathering System

This session will present an overview of the

design process of a geothermal gathering

system with emphasis on particularities of the

geothermal fluid.


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Two phase flowSteam separators

Geothermal

water

Steam

Re-injection wells

Pressure

reliefProduction wells

Turbines

GeneratorsMist separators

Cooling

towers

Condensers

Steam Supply - Preliminary P&ID

emergency exhaust


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Nesjavellir Power Plant

Separation

station

Steam vent

station

Steam

pipelines

Two phase

flow

PowerPlant

Production

Well

Cooling towers


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Gathering system- Design

Design standards

Standards i.e.

Pressure directive

97/23/EC Pressureselection

Chemical constraints

Power generation

Productivity curves

0

200

400

600

800

1000

1200

1400

1.00 10.00 100.00

SiO2(m

g/kg)

Pressure (bar-a)

quartz solubility (F&P82)

amorphous silica solubility (F77)

330 C

300 C

270 C

240 C


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Chemical constraints

Scaling

Corrosivity

Radioactivity

Mitigation:

Pressure control / closed loop system

cleaning of the steam

Inhibitors


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h = 1600 kJ/kg

h = 1800 kJ/kg

h = 2000 kJ/kg

h = 2200 kJ/kg

0

50

100

150

200

250

300

350

400

450

500

0 2 4 6 8 10 12 14 16 18 20

Turbinep

ower[kJ/kg]

Separator pressure [bara]

Assumptions:

Total turbine efficiency: 0,8

Power generation


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Typical productivity curves


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Well PumpLow Enthalpy

Type

Submersible pump

Line shaft pump

Selection and operation Depth

Temperature

Scaling

Bubble point


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Gathering SystemDesign load

Constant load Weight

Pressure

Variable load (depending on location) Wind load

Snow load

Earthquake

Frictional load Thermal expansion

Friction


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Gathering System - Pipelines

Pipe laying

Under ground

Above ground

Material selection

Pipe size

Pressure/temperature


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Steam Supply SystemPipelines

300

400

500

600

700

800

900

1000

0 20 40 60 80 100 120 140 160

Pipediamete

r[mm]

Flow [kg/s]

7 bar-a

20 bar-a


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Gathering systemroute selection

Public safety

Environmental impact

Restriction on land

Cost efficiency


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Steam pipelines


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Steam Supply - Layout

Central separation station Satellite separation stations

Individual separators

Central Satellite Individual


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Power plant layout


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Steam Supply - Separators

Cyclone separators

Gravity separators

Efficiency

Steam separator and moisture separator

should together achieve 99,99 % bw.liquid removal or better


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Calculated example

The presenter will go through a calculated

example to show methods used for basic

engineering within steam gathering system

design. The example taken will be connectedto the special conditions encountered in

geothermal energy.


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Example

Example for 1200 kJ/kg well enthalpy 40-50C condensing temperature

Back pressure

Objective

Maximize the power production


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Assumptions

We know the reservoir enthalpy

We know the condenser temperature

Separation pressure does not influence the well

flow


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Example, condensing unit


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Example, condensing unit

The maximum power will be 12,4 MW

Entalpy = 1200 kJ/kg

Condensing pressure 0,075 bara / temperature

40C

Separation pressure 6 bara

Flow 100 kg/s

What if we selected backpressure instead?


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Example, back pressure


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Example, back pressure

The maximum power will be 6,4 MW

Entalpy = 1200 kJ/kg

Separation pressure 12 bara

Flow 100 kg/s


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Example

Optimum separation pressure is 6 bara, is thatok?

Saturation temperature for 1200 kJ/kg is 273C

0

200

400

600

800

1000

1200

1400

1.00 10.00 100.00

SiO2

(mg/kg)

Pressure (bar-a)

quartz solubility (F&P82)

amorphous silica solubility (F77)

330 C

300 C

270 C

240 C


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Thank You!

VISIT GEOELEC.EU

Documents

7.44.Session VI EHa and LTr Process Flow and Steam Gathering System v3