CarboTech Engineering GmbH Intelligent Utilization of Biogas Upgrading and Adding to the Grid

Transcription

1 CarboTech Engineering GmbH Intelligent Utilization of Biogas Upgrading and Adding to the Grid Dr. Alfons Schulte-Schulze Berndt

2 Content presentation General Guidelines for Sustainable Biogas Utilization Route of Biogas Utilization Why Upgrading Biogas to Natural Gas Quality Conversion Route from Biomass to Heat and Power Specification of Raw Biogas / Upgraded Biogas / Grid Quality Processes for Biogas Upgrading Principle of Biogas Upgrading by Means of Gas Scrubbing Process Scheme Biogas Upgrading by Water Scrubbing System Principle of Biogas Upgrading by Means of Pressure Swing Adsorption Process Scheme Biogas Upgrading using PSA-Process Comparison of Various Biogas Upgrading Systems Principle of ZETECH 4 - Zero Emission Technology Energy Balance Sheet Biogas Upgrading Plant Examples Biogas Upgrading Plants Conclusion

3 General Guidelines for Sustainable Biogas Utilization Minimize energy and utilities input for biogas conversion into biomethane, power and heat. Maximize conversion efficiency factors. Minimize losses of biomass and biogas. Avoid methane emission to atmosphere. Keep transport channels for biomass, biogas and biomethane short. While converting biogas to power and heat utilize both energy streams completely.

4 Route of Biogas Utilization vision biogas future traditional steam reforming H 2 -generation methane enrichment gas motor / cogeneration plant H 2 -purification industrial gas hydrogen stationary fuel cell vehicle fuel natural gas substitute "biomethane" vehicle fuel power / heat feed into natural gas grid (highest efficiency factor) disadvantage: lower heat utilization low electrical effiency factor

5 Why Upgrading Biogas to Natural Gas Quality? Precondition to get access to natural gas grid Grid routes opens access to intelligent biogas utilization: - decentralized cogeneration plants total utilization of power and heat - advantages biomethane versus biogas cogeneration -- higher electrical efficiency -- lower capital cost -- lower service cost -- longer lifetime - industrial heat generation high efficient and low emissions - vehicle fueling station CO 2 -neutral and environmental friendly

6 Conversion Route from Biomass to Heat and Power Biogas-Upgrading Biogas-Generation future biomass Bio-natural gas 5 9 bar biogas feeding station Decentralized Biogas Utilization natural gas grid industry & households CNG-filling station Centralized Biogas Utilization gas engine power (1/3) heat (2/3) Disadvantage: low energy utilization factor, no utilization of heat HPCG-plant power heat Advantage: complete utilization of heat and power

7 Specification of Raw Biogas / Upgraded Biogas / Grid Quality component symbole raw biogas biomethane DVGW260/grid quality methane CH % > 97 % no minimum values carbon dioxide CO % < 1 % < 6 % nitrogen N 2 < 2 % < 2 % no maximum values oxygen O 2 < 0,5 % < 0,5 % < 0,5 % hydrogen sulfide H 2 S < 500 ppm v < 5 mg/nm 3 < 5 mg/nm 3 hydrocarbons C x H y < 100 ppm v < 10 ppm v < condensation point water H 2 O saturated < 0,03 g/m 3 < condensation point calorific value H S,M 6-7,5 kwh/m 3 max. 11 kwh/m 3 8,4-13,1 kwh/m 3 wobbe index W S,M 6-11,5 kwh/m 3 max. 14,5 kwh/m 3 12,8-15,7 kwh/m 3 Note: Biomethane has to match with gas quality in the grid at injection point.

8 Processes for Biogas Upgrading Major target: recover methane, remove impurities CO 2, H 2 S, N 2, O 2, H 2 O and other process gas scrubbing adsorption membrane process CO 2 -liquefaction general description CO 2 is adsorbed by means of washing liquid (e.g. water, amines, glycolethane etc.) CO 2 is bound at internal surfaces of adsorption material (zeolithes, molesieves) CO 2 is separated due to different permeation rates at membrane barriers phase separation of liquid CO 2 and gaseous methane at very low temperatures

9 Processes for Biogas Upgrading process description disadvantages advantages 1. gas scrubbing CO 2 and H 2 S is absorbed by means of washing liquid (e.g. water, amines, glycolethane etc.) pre-purifying (H 2 S) and drying process necessary continuous loss of washing liquid continuous disposal of washing liquid use of chemicals or other liquids offgas heavily loaded with H 2 S and washing liquid risk of bacterial contamination of product gas enrichment of O 2 /N 2 in product gas high gas quality in case no O 2 & N 2 in raw biogas for plants (> m 3 /h) specific investment cost lower 2. membrane process CO 2 is separated due to different permeation rates at a membrane complex pre-purifying (H 2 S, water) necessary high process pressures necessary unstable long-term behavior / performance loss low CH 4 -recovery high investment cost high energy demand high CH 4 -emission dry process no chemicals low mechanical wear

10 Processes for Biogas Upgrading process description disadvantages advantages 3. adsorption CO 2, higher C x H y, H 2 S, SI-, Fl-, Cl-compounds, odors will be removed by activated carbon / carbon molecular sieve high H 2 S in raw gas requires pre-cleaning high gas quality dry process no use of chemicals no process water demand no waste water durably and flexibly partial removal of N 2 and O 2 moderate investment cost no bacterial contamination of offgas 4. CO 2 -liquefaction CO 2 is liquified by high pressure and low temperatures and separated by rectification column complex pre-purifying necessary very high power cost high investment cost enrichment of O 2 /N 2 in product gas very high gas quality no chemicals no water

11 Principle of Biogas Upgrading by Means of Gas Scrubbing greengas / biomethan washing liquid washing liquid: - water - glycolethane (Selexol) -amine -other theoretical absorption capacity basis : biogas 55 % CH4, 43 % CO2, 2% N2/O2, H20-saturated, 20 C 14 CO 2 -polyglycol DME biogas CH 4 / CO 2 / N 2 / O 2 / H 2 O / H 2 S washing liquid CO 2 / CH 4 / H 2 O / H 2 S absorbed gas quantity [ltr./kg] CO 2 -water CH 4 -polyglycol DME CH 4 -water pressure [bar a] regeneration absorption

12 Process scheme Biogas Upgrading by Water Scrubbing System dryer biomethane CO 2 + H 2 S scrubbing column 1. stage depressurization waste gas (CO 2, CH 4, H 2 S, O 2, N 2 ) stripping column air biological desulphurization waste gas (H 2 S-free) water nutrients (waste water) biogas compressor Cooler blower 1. stage 2. stage recycle gas (CH 4, CO 2, H 2 S) cooler pump waste water

13 Principle of Biogas Upgrading by Means of Pressure Swing Adsorption gas molecules CH 4 N 2 / O 2 H 2 O / H 2 S CO 2 adsorber greengas / biomethane adsorption: regeneration: gas pressure high gas pressure low Carbon Molecular Sieve P R E S S U R E S W I N G A D S O R P T I O N ("PSA") biogas off gas CH 4 / CO 2 / N 2 / O 2 / H 2 O / H 2 S CO 2 / N 2 / O 2 / H 2 O / H 2 S

14 Process Scheme Biogas Upgrading using PSA-Process CH 4 -rich gas purge gas H 2 S- removal CH 4 - production biogas compression gas conditioning condensate vacuum pump waste gas

15 Comparison of Various Biogas Upgrading Systems (for new biogas injection projects, > 500 m 3 /h, energy crops, remote locations) Priority factor Attribute Water Scrubber Selexol Scrubber Amine Scrubber Pressure Swing Adsorption Membrane process 2 CH 4 -enrichment high ++ high ++ high ++ high ++ low - 1 O 2 -/N 2 -enrichment yes - yes - yes - no + yes - 2 CH 4 -losses medium +/- high -- low ++ medium +/- high -- 1 Product gas dryer required 1 H 2 S-precleaning required 1 Waste gas treatment required 2 Utility demand (power, water, coolingwater, chemicals) Power demand, appr. (stand-alone system) 1 Level of emission (waste water, offgas, waste) yes - (yes -) yes - no + no + yes - yes - yes - yes - yes - yes - yes - yes - no + no + medium +/- high -- high -- medium +/- high -- 0,28 kw 3 0,32 m feedgas kw 3 0,42 m feedgas kw 3 0,21 m feedgas kw 3 0,5 m feedgas m medium +/- low + medium +/- low + low + 1 Capital cost medium +/- medium +/- high - medium +/- high - Final rating kw feedgas

16 Principle of ZETECH 4 - Zero Emission Technology (patented) biogas generation biogas upgrading biomethane biomass H 2 S- removal hot water compressor condensate flue gas boiler CH 4 -containing off gas Advantages - no methane losses - no methane emission / no H 2 S-emission - no energy loss - highest energy conversion efficiency - no cogeneration plant for heat generation at site required

17 Energy Balance Sheet Biogas Upgrading raw biogas flow: 400 Nm 3 /h pressure: 1,05 bar a CH 4 : 65 % CO 2 : 32 % O 2 /N 2 : < 3 % H 2 S: 300 mg/nm 3 H S,n : 7,15 kwh/nm 3 electrical energy 87 kw (incl. cool water re-cooling) utilizable waste heat 30 kw therm waste gas flow: 140 Nm 3 /h pressure: 1 bar a CH 4 : 7,5 % CO 2 : > 88 % O 2 /N 2 : < 4 % H 2 S: < 5 mg/nm 3 green gas flow: 260 Nm 3 /h pressure: 5 bar a CH 4 : > 96 % CO 2 : < 2 % O 2 /N 2 : < 2 % H 2 S: < 5 mg/nm 3 H S,n : 10,56 kwh/nm 3 energy input 7,15 kwh/nm Nm 3 /h + 87 kw kw energetic efficiency I : energy output 10,56 kwh/nm Nm 3 /h + 30 kw kw 94,2 % (without using waste gas) combustion of waste gas in hot water boilers for pasteurization & fermentation additional energy output : 99 kw energetic efficiency II : 97,5 %

18 Plant Examples - Biogas Upgrading Plants Year Location Raw gas input [Nm 3 /h] Raw gas source Upgrading system Utilization fig Stockholm / Sweden 600 sewage gas water scrubber vehicle fuel fig Stockholm / Sweden 2 x 350 sewage gas PSA vehicle fuel fig Frederikstad / Norway 150 sewage gas PSA vehicle fuel fig Braunschweig / Germany 2 manure / bio waste reformer / PSA H 2 -generation for fuel cell fig Galgenen / Switherland 70 bio waste Selexol scrubber vehicle fuel fig Luzern / Switzerland 140 sewage gas PSA gas grid / vehicle fuel fig Aachen / Germany energy crops PSA feed to natural gas grid

19 Plant Example - Biogas Upgrading Plants (fig. 1) Stockholm / Sweden 600 Nm 3 /h raw gas 400 Nm 3 /h product gas purity: vol.-% CH 4

20 Plant Example - Biogas Upgrading Plants (fig. 2) Stockholm / Sweden 2 x 350 Nm 3 /h biogas 2 x 200 Nm 3 /h product gas purity: vol.-% CH 4

21 Plant Example - Biogas Upgrading Plants (fig. 3) Frederikstad / Norway 150 Nm 3 /h biogas 100 Nm 3 /h product gas purity: vol.-% CH 4

22 Plant Example - Biogas Upgrading Plants (fig. 4) Braunschweig / Germany 2 Nm 3 /h biogas 2 Nm 3 /h product gas purity: 99,999 vol.-% H 2

23 Plant Example - Biogas Upgrading Plants (fig. 5) Galgenen / Switzerland 70 Nm 3 /h raw gas 40 Nm 3 /h product gas purity: vol.-% CH 4

24 References - Biogas Upgrading Plants (fig. 6) Luzern / Switzerland 140 Nm 3 /h biogas 87 Nm 3 /h product gas purity: vol.-% CH 4

25 References - Biogas Upgrading Plants (fig. 7) Ventilator Biomass: energy crops Entschwefelung Speicherbehälter Produktgas Tür Öl- Adsorber Ventilator Vakuumpumpe 1 PSA-Ventilskid WT - Skid Vakuumpumpe 2 CTOP 1 Biogas: Nm 3 /h / 53 % CH 4 Biomethane: 530 m3/h / 96 % CH 4 Utilization: feed to natural gas grid Location: Kerpen / Germany Customer: Aachen Municipality Commissioning: End of 2006 Speicher Kabeltrasse zum Kühlerskid - 400mm oder 250mm E E SPS 400x400 FU's Steuerl.- komp. Trockner 3 2 Biogasverdichter 1 Tür Ventilator Tür Tür

26 Conclusion Efficient biogas utilization requires transport via natural gas grid. Biogas upgrading is a must for accessing natural gas grid. Decentralized cogeneration plant fired with biomethane enables nearly 100 % utilization of the energy of biogas. Biogas upgrading technology is well known, proven, efficient and requires low energy input. Combined with Zero Emission Technology (ZETECH 4 ) zero methane losses and zero methane emission can be ensured. Biomethane injection to natural gas grid is well proven technology, so far since more than 10 years only positive experiences.

27 Am Technologiepark 1 D Essen, Germany Tel. +49 (0) Fax +49 (0) an.info@carbotech.de