Start Up and Performance of the Durham AWWTF Brown Grease Receiving and Cogeneration Facilities. Dan Garbely WSA FOG Forum 2016

Transcription

1 Start Up and Performance of the Durham AWWTF Brown Grease Receiving and Cogeneration Facilities Dan Garbely WSA FOG Forum 2016

2 Agenda Project Background Systems Overview Brown Grease Facility Cogeneration Systems (Engines) Digester Gas System Gas Storage Gas Purification Startup challenges System performance

3 Project Background

4 2008 Facilities Plan Move active digestion to Digester Complex 2 Use Digester Complex 1 as storage Construct new Cogeneration Facility Deteriorating condition of existing engine Policy to increase utilization of digester gas to reduce power and heat costs at the plant

5 Increasing Gas Production Digestion of Municipal Sludge had limited gas production District interested in find new waste resources to recover How much grease is out there?

6 Brown Grease Study 2010 Study by Kennedy Jenks evaluated grease production in Washington County Focused on restaurant grease production using sampling and statistical analysis Determined up to 22,700 GPD of Grease Available

7 Project Development Contracted with CH2M to design new facilities in 2012 District staff and CH visited similar facilities to develop concepts and learn lessons. Pre-selection of Engine and Gas Treatment vendors JW Fowler selected as construction contractor

8 Systems Overview

9 Digester and FOG Feed Systems DC 2 DF BGRF COGEN FF SOLIDS BLDG TREATMENT DC 1

10 Gas Systems DC 2 NG BGRF 8 IN and 18 IN pipes COGEN FACILITY Power GAS STORAGE TREATMENT

11 Brown Grease Receiving Facility

12 High Strength Waste Sources FOG from Haulers Individual haulers are pre-certified Haulers under contract High strength COD waste Waste sugar from expired beverages Food Processing Waste Waste goes through a dissolve air flotation thickener prior to hauling Waste was removed from the collection system to prevent overflows

13 Brown Grease/High Strength Waste Processing and Feeding - Receiving - Rock Trap - Grinder - Pumping - Heating - Storage - Digester Feed

14

15

16

17

18 Cogeneration Facility

19 Cogeneration Facility - Fuel Supply - Engine & Auxiliaries - Hot Water Interface - Lube Oil Systems - Engine Room Ventilation - Engine Room Cranes

20 Cogeneration Facility

21

22 Digester Gas System

23 Gas System DC 2 NG BGRF 8 IN and 18 IN pipes COGEN FACILITY Power GAS STORAGE TREATMENT

24 Gas Storage Westech 25,000 cubic feet Provides approx. 50 minutes of storage Improves operation (wide spot) On top of existing digester and tank is still usable

25

26 Gas Purification Unison System H2S, Moisture, and Siloxane Removal Compresses gas to 5 psi Sulfatreat Media for H2S Activated Carbon for Siloxane

27

28 Startup & Operational Challenges

29 If you build it, they will dump CWS contracted with 4 different FOG haulers Haulers were very anxious to use the facility Training every driver presented challenges Metering calibration

30 Vibration, seals, and leaks Rotary lobe pumps are a different animal Get the right lobes! Vibration can be significant Double mech seals needed for FOG application

31 The FOG Fountain! Rock trap worked very well at removing rocks, but messy to clean Does not remove grit well Hot water added to facilitate cleaning Not pressure rated!!

32 FOG Stinks! FOG is a challenging odor source Switched to passive odor control system for FOG tank

33 FOG is very Aggressive FOG varies greatly, but typically has a ph of ~4 FOG is also heated and kept at ~90F Tank coating completely failed in less than a year

34 FOG has True Grit Grit is inevitable but challenging to manage Caused damage to pumps Filled up the tank Packed the digester feed lines

35 System Performance

36 System Performance to date FOG Receiving works well Grit accumulation Increase in gas production from codigestion aligns well literature values Gas treatment media effective Engines are workhorses, but require attention Hot water system provides most of demand Plant upsets can limit production

37 300,000 Durham Digester Gas Production Methane Generation 250, ,000 CH4 Generated, scfd 150, ,000 50, /13/15 2/23/15 3/5/15 3/15/15 3/25/15 4/4/15 4/14/15 4/24/15 Digester #1 Digester #2 (FOG Addition)

38 Is it worth it?

39 30 Gas Generation Based on VS Applied CH4/VS, scf/lbs VS fed & CH4/gal FOG Food Processing Indigenous Methane per lb VS applied Methane per gallon

40 Economic Benefit FOG Food Processing Waste CH 4 scfm/gal % CH 4 in biogas 65% 65% Biogas scfm / gal $/cubic ft of biogas $ $ Tipping Fee $0.074 /gal Gas Benefit $0.103 /gal $0.042 /gal Total Benefit $0.177 /gal $0.177 /gal Required Tipping Fee $0.135 /gal

41 Economic Benefit At 7gpm per digester the annual net benefit to the district is approximately $1M

42 Questions?