Grandville CWP Egg Shaped Anaerobic Digester and Bio-gas - - PowerPoint PPT Presentation

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grandville cwp egg shaped anaerobic digester and bio gas
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Grandville CWP Egg Shaped Anaerobic Digester and Bio-gas - - PowerPoint PPT Presentation

Apr 29, 2023 180 likes •581 views

Grandville CWP Egg Shaped Anaerobic Digester and Bio-gas Cogeneration Presented by : Brian Hannon, P.E., Moore & Bruggink Outline Brief Project Background Why ESD ESD Startup Cogeneration System Energy Management

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Grandville CWP Egg Shaped Anaerobic Digester and Bio-gas Cogeneration

Presented by: Brian Hannon, P.E., Moore & Bruggink

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Outline

  • Brief Project Background
  • Why ESD
  • ESD Startup
  • Cogeneration System
  • Energy Management
  • Current Performance vs. Design
  • Lessons Learned
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City of Grandville Overview

Grandville

Grand Rapids US 196 131

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Customer Community Overview

  • Ottawa County
  • Georgetown
  • Hudsonville
  • Jamestown
  • Jenison
  • Blendon
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Grandville Clean Water Plant

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Grandville Clean Water Plant

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Why Egg Shaped Anaerobic Digester (ESD)?

  • Process
  • Footprint
  • Cost (life cycle)

– Cleaning – Efficiency

  • Client Comfort
  • Ability to go to Class A
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ESD Pipe Gallery

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Anaerobic Digestion

  • Relatively Simple
  • Known

Technology

  • Produces two

beneficial products w/ low energy input

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How the ESD Works:

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How the ESD Works:

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How the ESD Works:

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How the ESD Works:

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  • Good Seed Sludge starts the process
  • Complete Control
  • Process Allowed to Acclimatize
  • No loss of Bio-Mass
  • Steady State Operation Quickly
  • Alkalinity Builds Quickly
  • Temperature Control

Micro-Digestion Style Startup

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Complete Mixing = Better Digestion = More Biogas!

(and no periodic cleaning!)

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Grandville’s Biogas Components

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Why Biogas Cleaning?

  • Biogas Impurities

– Moisture – H2S – Siloxanes

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Siloxane Damage to Boiler

Silica Layer ½” to 1” Thick Pitting of Boiler Tubes

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Siloxane Damaged Valve

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Cogeneration System

  • Dual Fuel (bio-gas and natural

gas)

  • 280 kW using Bio-gas,
  • 360 kW using Nat Gas
  • Internal exchangers to capture

heat from engine cooling jacket and exhaust

  • Efficiency of 86%
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Power

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Heat

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Integrated Energy Management System (IEMS)

  • ESD – Biogas Supply
  • ESD – Heat Demand
  • CHP – Biogas Demand
  • CHP – Heat Supply
  • CHP – Power Supply
  • System – Power Demand
  • Lab/Ops – Heat Demand
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Biogas Production

  • Biogas Quantities

– Currently producing ~120,000 cuft/day – Distribute between cogen, flare, and boiler

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Power & Heat Production

  • 70,000 CF/day Biogas to CHP

– Biogas Energy Content ~ 640 BTU/CF – Average Energy Demand ~ 175 kW

  • ~ $100,000 / year (@ $0.065/kWhr)

– Electrical Efficiency 32%

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Power & Heat Production

  • 70,000 CF/day Biogas to CHP

– Biogas Energy Content ~ 640 BTU/CF – Average Heat Production: ~ 1.0 MMBTU/hr

  • Other than coldest periods of winter, heat

production exceeds demand

  • Load Dump Radiator eliminates excess heat

– Fuel to Heat Efficiency 54% – Overall Efficiency 86%

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Power & Heat Production

  • (+) Producing sufficient heat to satisfy

demand of ESD and Lab Ops during coldest periods

  • (-) Connected load is frequently not large

enough to use all of the biogas being produced

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Optimization

  • Optimization of ESD Gas Production

– Balancing gas production with feeding times and quantities – Maintaining cleansing velocity in line – Look at potential co-feed feedstocks – Storage

  • Optimization of Power Production

– Not using all the biogas – still flaring – Add loads

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Costs and Payback

  • Elements of Capital Costs for Payback

Analysis

– Gas Cleaning Skid – Cogen Unit – Hot Water Pumps for Cogen – IEMS system – PEX lines to Lab/Ops Total “Additional” Capital = $850,000

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Estimated Savings

  • Projected Energy Savings at Startup

Rates

– $95,000/yr

  • Projected Gas Savings at Startup Rates

– $47,000/yr

  • Projected Payback

– 6 years simple, 7.8 discounted

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Actual Savings

  • Actual Energy Savings

– Approx $98,000/year

  • Actual Gas Savings

– Approx $22,000/year – Nat Gas is ½ price Utility bills have been lowered even with expanded plant! Approximately 25% of plant power is produced with CHP generator.

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Where are we at today?

  • Consistently producing between 170-200 kW

power.

  • Providing all heat necessary for digester and

Lab/Ops.

  • Balancing sludge feed rates to optimize gas

production.

  • Balancing heat draw from digester to better

match production from cogen.

  • Reviewing feasibility of another transfer switch.
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Going Forward

  • Dial in Feed Rates
  • Review and

Optimize Load Usage vs. Energy Production

– Consider additional transfer switch

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Going Forward

  • Review Heat Usage
  • vs. Production from

Cogen

– Consider removing tubes from ESD HX

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Lessons Learned

  • Micro-digestion
  • Startup support
  • Power Connection to Turbo-blowers
  • Gas holder cover on old tank
  • 3-way Valve Plug Coating Material vs. Temp
  • Excessive Moisture in Bio-gas
  • Improved primary efficiencies
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Questions?

Brian Hannon, P.E. Moore & Bruggink (616) 363-9801 bhannon@mbce.com Todd Wibright City of Grandville CWP (616) 457-0720 wibrightt@cityofgrandville.com