MEL Heat recovery Project

INNERS PROJECT

FINAL EVENT

Leuven Belgium – june 11

th

2015

Heat recovery studies on sewers

-Heat exchanger at the OVILLEO

new wastewater treatment plant

European Metropole of Lille in a few words

o Public organisation of intermunicipal cooperation gathering 85 cities located around Lille (~« Greater Lille ») = 1,2 Million of inhabitants,

oWastewater treatment of European Metropole of Lille territory is

mainly ensured by:

- 1 constructed wetland located in Deûlémont, - 3 WWTP managed by Belgian authorities,

- 9 WWTP managed by European Metropole of Lille

o 4 722 kms of sewerage network with:

• 1873 kms of separate sewerage system

Study realised by Cabinet Merlin Office in 3 phases: (november 2011 to september 2012)

Phase 1: Completion of the mapping of urban heating potential by using the

thermal energy of the sewerage system and target research,

Phase 2: Technical and legal study on heat recovery systems of sewage

networks for urban heating,

Phase 3: Feasibility study on 5 different indentified sites.

At the end of the study, MEL planned to chose a site and to implement a device to heat a building

Mains and goals of the heat

recovery study in sewer systems

Sewers

according to the model of MIKE URBAN MEL Feasibility thresholds selection

of the elegible sewer and

heating potential via recovery on wastewater sewerage systems

Creation of a Google Earth data base

Phase1:

Mapping of eligible

discharge systems

Phase 1: Study of potential of urban

heating

Potential heat depends on 4 parameters:

- Heat capacity of the effluent water with constant value, - The difference of

temperature upstream an downstream the device, - The flow of sewage, - The COP (Coefficient of

performance) of the device

LILLE Average

flow rate – dry weather

Heat recovery potential from MEL’s wasterwater

around LILLE

MEL headquarter

Potential conclusions

There is not always a perfect balance between heating

requirements and the resource:

• The highest resource is located near wastewater treatment

plants, often in rural areas

• The demand of heat is located in urban, dense areas

The higher potential in MEL is concentated on two sewer

networks :

• Lille and Roubaix cities have the highest heating demands,

and the most available thermal resource,

Heating resource capacity from wasterwater

City Dry weather

flow (l/s) available power Eligible sewerage systems km Halluin 120 351 kW _1.3 Armentières 120 351 kW _6.4 Tourcoing 208 609 kW _3.1 Villeneuve d’Ascq 250 732 kW _8.5 Faches 254 744 kW _22.9 Roubaix 1440 4219 kW _31.5 Lille 1750 5127 kW _41.5 overall / 12,13 MW

Phase 2: Technical inventory

General working principle of heat recovery for sewage

Heating pump Evaporator Condenser R e h e a ti n g b a si n s circulation pump Heat-transfer Network return Waste water (10 L/s – 16°C) Cool down form 3 to 4°C

Cool down form 3 to 4°C

Pipe bottom Heat-transfer

Network going

going

Forced circulation inside of the exchanger

Production mode

Heating :

• Production of monovalent energy : energy is exclusively provided by the heat pump, the

building heating is then likely to be in low temperature (<50°C).

• Production of bivalent energy : the heat pump is linked to another heat production mode,

(boiler, …), for the maintenance periods or extreme cold-weather seasons.

The Performance Energy Ratio (recovered heat/ consumed energy) is close to 3.5 little high émission temperatures (max 45 to 50 °C).

Cooling:

The heat pump can also be used for cooling. It is called the reversible heat pump. The COP (Coefficient of Performance) is nearly 3 in the cooling mode.

Domestic hot water:

The heat pump cannot guarantee a minimum temperature of Domestic Hot Water (55 to 65 °C). A background heater is required (boiler, electrical water heater).

Technical inventory of heat exchangers

A- Integrated heat exchangers:

• Integrated heat exchangers in existing sewerage systems • Integrated heat exchangers in new sewerage systems • Integrated heat exchangers with lining

B- Remote heat exchangers: • Spiral heat exchangers • Coaxial heat exchangers • Plate heat exchangers

A- Integrating heat exchangers example existing sewage system: « Degré bleu » Lyonnaise des eaux process

B - Remote heat exchangers example

Phase 3: feasibility studies

European Metropole of Lille realized feasibility studies on 5 followings sites:

Municipal Greenhouses in Roubaix city, MEL headquarter in Lille city,

« Site Niquet » sport complex in Marcq-en-Baroeul city, Fives swimming-pool in Lille city,

« Les Bateliers » geriatric hospital in Lille city,

The conclusions of the feasibility were about: • The operational cost,

• The return on investment time,

Payback time

The return on investment is almost impossible in the case of a competition with an urban high-temperature network,

The return on investment is shorter on the bigger devices ( 10 -15 years) than for the smaller ones (20 in 25 years),

The interest is better ( 3 - 10 years) for buildings with a constant need of heat (as swimming pool or to a lesser extend

Carbon balance

Site Niquet Sport complex in Marcq-en-baroeul Fives swimming-pool in Lille « Les Bateliers » geriatric hospital in Lille GHG emission decrease 56 % 56 % 65 % 69 % 55%

« la vie n’est pas un long fleuve

tranquille »

The location of the demo project was proposed on the MEL

headquarter due to legal purpose.

The board decided not to realize the demo project because :

-

Overcosts (depth of the sewer network, the complicated

existing boiler room, …)

-

Building linked to an high temperature network

-

To important payback time (16 years)

So MEL proposed to INNERS partners to change the project

(ovilleo WWTP heat exchanger) and they agreed

1 – Marquette-lez-Lille (620 000 PE) [37 cities waste water treatment area]

2 – Wattrelos (417 000 PE)

3 – Houplin Ancoisne (172 000 PE) 4 – Villeneuve d’Ascq (170 000 PE) 5 – Neuville en Ferrain (65 000 PE) 6 – Armentières (65 000 PE)

7 – Salomé (15 700 PE) 8 – Herlies (8 200 PE)

9 – Ennetières en Weppes (4 500 PE)

Nota :

*) PE = Population Equivalent Habitant, unit used to show the WWTP capacity,

*) the capacities are those mentioned in State decree of each WWTP.

9 WWTP locations

OVILLEO location

Works amounts:

Several external ways of funding for the project

91 M€ (VAT-excluding) of funding from « Agence de l’Eau Artois Picardie » 125 k€ (VAT-excluding) of ERDF

381 k€ (VAT-excluding) of INTERREG 4B (INNERS)

Different specific frontages

Architectural Integration

… and green walls

Sludge storage building, spheric gas tank Digester covered with steel clading

Sludge to 165°C and 8 bars between 2 digest stages

Sludge treatment: EXELYS system

• Decrease of produced sludge • Getting healthy/hygienic sludge • Increase of produced biogas, • No smell

Sewage treatment: HYBAS system

• Density of work,

• Improvement of treatment performances • Decrease of temperature sensitivity

Effluents arriving (Waste water and rain water) 1.a

2 3

The river « Marque »

4 1.b Wastewater line (arriving flow < 2,8 m3/s) Rainwater line (2.8 m3/s < arriving flow < 8.1 m3/s)

2 circuits for the water treatment

End: sludge pellets

Start: liquid and smelly sludge

1/ Decrease sludge volumes to drain off : of 85 %

2/ Getting a sludge pellets without smell, healthy and easy to manipulate

Electricity production with cogeneration

GREEN ENERGY PRODUCTION : biogas used on site

Sludge drying

Biogas

THERMAL ENERGY OF OVILLEO

94 % PROVIDED BY BIOGAS PRODUCED ON SITE

6% PROVIDED BY NATURAL GAS

Heaters of the sludge

line Cogeneration

engines

facilities heating Flare (rescue)

= equipments with heat recovery loop

Exported Electric Energy production 58 % 38 % 3 % 1 %

Thermal drying of sludge Exelys system

Digestion Priority 1 biogas Priority 2 biogas Priority 3 biogas Natural gas Natural gas Steam Steam Heated sludge Dryers Exelys Premises heating Water pre-heating Exact amount of vapor Existing safety heater Vapor heater Biogas/natural gas Co-generation

Main heat recovery

devices

The heat of exhaust gases of the cogeneration is used

for the production of vapor

( INNERS) Exhaust fumes Heat exchanger (Boiler) Water

Some pictures

Co-generation exchanger of the vapor heater

Heat exchanger OVILLEO

performances

INNERS heater production estimation: 4 000 tons/year Heat energy : 666 kWh/ton

LHV (lower heating value) of natural gas saved: 10 kWh/Nm3

Heater productivity: 90%

Quantity of natural gas saved per year: 296 000 Nm3 Cost saving of functioning estimation: 128,4 k€/year

At the beginning of putting into service of INNERS devices to may 25th _{2015 :}

INNERS heater production : 600 tons Heat energy: 400 000 kWh

LHV of natural gas saved: 10 kWh/Nm3

Heater productivity : 90%

Quantity of natural gas saved: 44 400 Nm3