b1_rolf_strenziok

THE MICRO GAS TURBINE IN FIELD TRIALS WITH FERMENTER BIOGAS

A project funded by the Federal Republic of Germany.

Dr.- Ing. R. Strenziok rolf.strenziok@uni-rostock.de

CONTENTS 1.

2.

3.

4.

5.

6.

Introduction Biogas production Micro Gas Turbine (MGT) with biogas Aims of the project, Field trials Results Summary of key points

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1. Introduction

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Electricity supply from biomass in Germany 2010 Biogenic liquid fuels: 6.1 %

Biogenic solid fuels: 36.2 %

Biogenic share of waste: 14.2 %

Landfill gas: 2.0 %

Biogas: 38.3 % Sewage gas: 3.3 %

Source: BMU-KI III 1 according to Working Group on Renewable Energy Sources-Statistics (AGEE-Stat); 1 TWh = 1 Bill. kWh; deviations in the totals are due to rounding; as at: March 2011; all figures provisional

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Use of renewable energy to create jobs About one third share of each Spread of the approx. 367,400 jobs in the renewable energy sources sector in Germany 2010

Biomass: 33.2 %

Solar energy: 32.9 %

Hydropower: 2.1 % Geothermal energy: 3.6 % public aided research/administration: 2.0 %

Wind energy: 26.2 %

Figures for 2010 are provisional estimate; deviations in totals are due to rounding; Source: O’Sullivan/Edler/van Mark/Nieder/Lehr: "Bruttobeschäftigung durch erneuerbare Energien im Jahr 20010 – eine erste Abschätzung", as at: March 2011; interim report of research project „Kurzund langfristige Auswirkungen des Ausbaus erneuerbarer Energien auf den deutschen Arbeitsmarkt“

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Number of biogas plants with their total installed electrical capacity in Germany EEG - renewable energy law

The German Renewable Energy Act was designed to encourage cost reductions based on improved energy efficiency from economies of scale over time. The Act came into force in the year 6 2000 and was the initial spark of a tremendous boost of renewable energies in Germany.

Payments for electricity from biomass according to the Renewable Energy Act

Plant capicity Tariff

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2. Biogas production Where does biogas come from ?

Fig. A typical biogas plant in Germany

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Components: - 1 hall for biodegradable waste[G]: 18 m × 18 m -1 Mix tank [E]: 800 m³ - 2 Pasteurization tank [B]: je 30 m³ - 1 Fermenter [A]: 4000 m³ - 1 combined Biomass-/Biogas basin [D]: 2000 m³ / 500 m³ - 2 CHP- module [F]: 346 kWel, 515 kWth, 520 kWel, 775 kWth 9

Biogas production and origin: – Methane gas produced from organic substances containing water by fermentation under anaerobic conditions.

– Produced from agricultural waste, manure, fatty residues – 2 – 3 kg maize silage => 1 Nm³ biogas.

– Energy content: 1 Nm³ biogas = 0.65 Nm³ natural gas.

– Biogas: 60% methane, 40% CO2, ~ 6.6 kWh/Nm³ upgraded biogas: 98% methane, 2% CO2, ~ 11 kWh/Nm³.

– By-products: residues as fertilizer or for improvement of land.

Applicability – Presently biogas is used in peripheral CHPs

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Biogas plant capacity (Germany)

Typical coferments are fats, market waste, crop residues, residues in the food industry 11 and many similar substances.

Methane- and H2S- Content Biogas data data January 2006 Biogas 250

hydrogen sulfide

200 150 100 50 0 1

3

5

7

9

11

13

15

17

19

21

23

25

27

29

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Day Methane vol%

H2S gas (Raw gas) ppm

H2S gas (Cleangas) ppm

H2S depends on input material, slaughterhouse waste 12

Gas conditioning and cleaning First enemy: Sulphur H2S

Decrease life time of lube oil Increase wear of metal components Indirectly affects availability To optimize profitability of power plants, GE producer established a standard guideline of 250ppm maximum H2S at 50% CH4, for GT 7000 ppm

First enemy: Sulphur H2S These are not my own results.

corrosion

Damages by H2S

Leaky pipes

damages

Measured Biogas methane content over one year Depends on input material, fatty waste yields to an increasing of CH4- content.

Biogas data CH4 Vol % 90 85

Vol % CH4

80 75 70 65 60 55 50 1

19

37

55

73

91 109 127 145 163 181 199 217 235 253 271 289 307 325 343

Day CH4 Vol %

unstable turbine operation regime 15

29000

1,1

28000 1,08 27000 26000

1,06

25000

1,04

24000 1,02 23000 22000

Density

Hu, Ho, Wobbe Index

Biogas characteristics

1 1

2

3

4

5

100 Hour Operation Test Hu kJ/Nm3

Ho kJ/Nm3

Wobbe Index kJ/Nm3

Density kg/Nm3

The Wobbe Index is used to compare the combustion energy output of different composition fuel gases in an appliance.

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How can we use the biogas for electricity production?

3. Micro gas turbine with biogas The MGT is a compact, turbine generator that delivers electricity onsite.

Derived through advanced engineering based on proven turbine design, C 30 MicroTurbines are the preeminent energy management solution.

Features including maintenance-free air bearings, the lowest emissions of any non-catalyzed fossil fuel combustion, and digital power conversion combine to produce the optimal small-scale generator.

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Conventional GT Combustion Chamber

Micro GT

Recuperator Combustion Chamber

G

G Compressor

Turbine

Compressor

Turbine

The new MGT with electr. Output from 30 – 200 kW is a very interesting development. With a heat exchanger (recuperator) the efficiency is doubled to about 18 30%.

We used the C30 Micro Gas Turbine (MGT) in the project Power unit

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C30 Micro Gas Turbine Source: capstone

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MGT noise level

Run on a variety of fuels: •Low or High Pressure Natural Gas •Biogas •Flare gas •Diesel •Propane •Kerosene

~ 70 dB

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Why MGT and not Gas engine?

Spark Plugs

Pistons

Impressions of biogas engines 22

4. Aims of the project, Field Trials Test the operation characteristics of C 30 MGT with biogas and compressor tests

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Two Field trials with two different compressor types Trial (Biogas plant)

Compressor

Trial period

Rotary Vane

1st year

Membrane

2nd year

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Why are compressors needed?

The gas turbine cannot suck in the bio gas.

Rotary Vane

VO7G

Power consumption

7.5 kW

Gas volume flow 73 m続/h Compression pressure

Normal 5.5 bar Max. 10 bar

Membrane

E-ML 130.45

Power consumption

1.3 x 2 = 2.6 kW

Gas volume flow

14 x 2 = 28 m続/h

Compression pressure

Normal 5 bar

Fig. Two Compressor systems

Max. 6 bar

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Layout of the compressor systems CWD 2000

TUmg

H2S

Hi, Hs, Wi, ρ

TvK

TvV

TnK

Frequenzumrichter

Schaltschrank

TÖ

pnV TnV

Flow meter

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5. Results As produced, biogas also contains saturated water vapor. The fractional volume of water vapor is a function of biogas temperature; Condensate removal is necessary! • Biogas temperature in summer too high • Large amounts of condensate behind the compressor

The cooler was ineffective.

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p Compr., T beforeTurbine, V Biogas, p beforeTurbine, Pel., Engine speed x 1000 rpm., Turbine Exit Temp. x10

GT operation data MGT Data 90 80 70 60 50 40 30 20 10 0

100 Hour Operation Test

p Compr. bar

T before Turbine 째C

Pel kW

Turbine Exit Temp. X 10

Engine speed x 1000 rpm

Vgas Nm3/h

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MGT at 26 kW MGT at 26 kW

[rpm, 째C, kW]

100 80 60 40 20 0 13:26

13:27

13:27 time

Engine Speed (rpm*1000)

Turbine Exit Temp (째C*10)

Output Power (kW)

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Starting behaviour of Temperatures and gas flow

7 minutes

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A Problem: Sulphur crystals in Rotary Vane compressor oil • Sulphur content in biogas 1000 ppm hydrogen sulfide

• Frequent oil change necessary • Corrosion problems • Gas cooler blockages

H2S- Measurement device

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Compressor Membrane damage caused by water in the biogas

• High water content in biogas • Compressor pressure swinging • Damage to compressor membranes

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6. Summary of key points • The raw fermenter biogas had a H2S content of up to 7000 ppm.

• For the operation of the oil lubricated and cooled Rotary Vane compressor a low sulphur content in the biogas is recommended.

• No desulphurization was necessary for the operation of the Membrane compressor or Capstone MGT. • For the Membrane compressor an active dewatering system is recommended.

• A frequency converter is recommended for the parallel operation of the membrane compressors.

• A lower auxiliary power consumption was achieved with the Membrane compressors but they are less resistent to mechanical wear.

• An on-line measurement of the biogas calorific value with a relay to the MGT fuel index control is recommended for a stabilization of the MGT operation.

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Thank you for your attention Dr.- Ing. R. Strenziok rolf.strenziok@uni-rostock.de

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Refueling of “Biogas” after upgrading and grid injection

Source: Petersson, Swedisch Gas Center, Sweden.