STANDARD BIOGAS PLANT

Transcription

1 CLASSIFICATION OF EXPLOSIVE AREAS STANDARD BIOGAS PLANT Classification of explosive areas Page 1/8 S:\Bigadan\1_PROJEKTER\2163 Fonroche\ICPE and Basic design documents (non project specific)\3. Atex Plan (text)\classification of explosive areas - Standard Biogas Plant.docx

2 Biogas: The most biogas plants produce a biogas with the following composition: - Methane (CH 4 ): % - Carbon dioxide (CO 2 ) % - Hydrogen sulphide (H 2 S) % ( ppm.) - Hydrogen (H 2 ) 0-1 % - Oxygen (O 2 ) 0-1 % - Nitrogen (CN 2 ) 1-3 % Variations can occur. So the primarily consistent in the biogas is methane (CH 4 ) which is combustible and carbon dioxide (CO 2 ) which is incombustible. Biogas properties: Ignition temperature: 595 C Minimum ignition energy: 0.29 mj Lower explosion limit, LEL: 4.4 % CH4 Upper explosion limit, UEL: 17 % CH4 Relative density (air 1): 0.9 (biogas) Relative density (air 1): 0.6 (CH 4 -andelen) SEK Handbok 426, 3. edition, page 203 Classification: See drawing no The explosive areas are classified according to: - IEC :2008 The extent of the explosive areas is classified according to: - SEK HANDBOK 426, Udgave 3 IEC classifies the explosive areas as the following: Zone 0: Areas where explosive atmosphere, consisting of combustible substances in the form of gas, fumes or vapour mixed with air occurs constantly, in long periods or often. Zone 1: Areas where explosive atmosphere, consisting of combustible substances in the form of gas, fumes or vapour mixed with air is likely to occur occasionally in normal operation. : Areas where explosive atmosphere, consisting of combustible substances in the form of gas, fumes or vapour mixed with air aren t likely to occur in normal operation, but only for a short period if it does occur. Explosive gas will over a short period, normally max. 1 day, during the commissioning of the biological process occur in the digesters. Classification of explosive areas Page 2

3 Digester ID-Code: 40-TK-001: Zone no.: K1 Safety valves on top of the digester and water seal 40-SV-001 Safety valve and water seal / 3.0 meter radius s and ventilation factors Automatic safety valve Zone no.: K2 Agitator shaft seal Agitator shaft seal / 3 meter radius s and ventilation factors Water seal around the shaft Classification of explosive areas Page 3

4 Zone no.: K3 Inside tank Gas phase in tank above the surface / no radius s and ventilation factors Biomass surface Continuous - Degree: - - Pasteurisation tanks ID-Code: 31-TK-001 and 32-TK-001: Zone no.: K4 Safety valve on top of the pasteurisation tanks 31-SV-001 and 32-SV-001 Safety valve / 3.0 meter radius s and ventilation factors Automatic safety valve Classification of explosive areas Page 4

5 Zone no.: K5 Agitator shaft seal Agitator shaft seal / 3 meter radius s and ventilation factors Water seal around the shaft Zone no.: K6 Inside tank Gas phase in tank / no radius s and ventilation factors Biomass surface Primary - Degree: - - Classification of explosive areas Page 5

6 Desulphurisation unit ID-Code: 50-TK-001: Zone no.: K7 Safety valve on top of the desulphurisation unit 50-SV-001 Safety valve / 3.0 meter radius s and ventilation factors Automatic safety valve Zone no.: K8 Inside tank 50-SV-001 Inside the tank / no radius s and ventilation factors Degree: - - Classification of explosive areas Page 6

7 Gas storages ID-Code: 71-TK TK-002: Zone no.: K9 Safety valve on the gas storages 71-SV-001 and 71-SV-002 Safety valve / 3.0 meter radius s and ventilation factors Automatic safety valve Zone no.: K10 Inside tank (inside inner membrane) 71-SV-001 and 71-SV-002 Gas phase in tank above the surface / no radius s and ventilation factors Biomass surface Primary - Degree: - - Classification of explosive areas Page 7

8 Condensate wells ID-Code: 70-TK-001 Zone no.: K11 Condensate wells Zone 0 Inside the well / no radius s and ventilation factors Condensate liquid surface Continuous Degree: Low (V L ) Poor Zone no.: K12 Condensate wells Zone 1 Around the ventilation opening / 3.0 meter radius s and ventilation factors opening Primary Degree: Low (V L ) Poor Classification of explosive areas Page 8