Small and highly efficient hydrothermal liquefaction (HTL) units for - - PowerPoint PPT Presentation

Small and highly efficient hydrothermal liquefaction (HTL) units for scalable mass implementation in biomass conversion

Ib Johannsen, V.Milkevych, D.More, B.S.Kielsgaard, K.Anastasakis, P.Biller Bio2Oil IVS and Dept. of Engineering, Aarhus University, Aarhus, Denmark

Overview

• Biorefining - the challenge of decentral and complex ressources
• No single solution - Center for Biorefinery Technologies
• Hydrothermal conversion
• Key technology innovations
• Bio2Oil
• New concepts – small modular units

Biorefining requires innovation

• Biomass do not fit into existing

technology platforms:

• Present chemical and refinery

industry is based of fossil fuels

Need for innovation!!

• Biomass do not fit into existing

technology platforms:

• Present chemical and refinery

industry is based on fossil fuels

• Ressources that are big and

centralized -Biomass is not!!

• Need for EFFICIENT, decentral

solutions

?

50 100 150 200 250 300 350 400 100 200 300 400 500 600 700 Pressure (bar) Temperature (°C)

Liquefaction

(vapour)

Carbonisation Supercritical Gasification

(liquid) Critical point

Hydrothermal conversion (liquefaction) (HTL)

• Biomass feedstock is pressure cooked in hot-compressed water
• No dry feedstock required
• Mimics natural fossil fuel creationà coal, oil, gas

§ HTL can convert any biomass to a high energy density bio-crude § One of the main advantages of HTL is the high flexibility of feedstocks and products.

Water-phase diagram

HTL technology at AU pilot

07/06/201916/01/2018

• Continuous pilot scale Hydrothermal liquefaction reactor, capacity up to 100 L/h, residence time ~15 min
• Wet biomass is processed at 350°C and 200 bar to produce bio-crude, solid residue, process water and CO2
• More than 70% of energy content ends up in crude oil fraction (>35% of mass)
• Xenobiotics and microplastics are converted as well

Biomass feed (sewage sludge) HTL 350°C, 200 bar, 15 min Bio-crude (35 MJ/kg)

Time Position in reactor Local flowrate Average flowrate

How to handle the need for long residence time and thus low flow?

• n Non-newtonian (tixotropic) biomass,

With low heat transfer properties, fouling/sedimentation issues

140 m of 14mm id tube

Strong non-newtonian viscosity of suspended biomass:

16,0 % DM 16,0 % DM 4,4% 8,3 % DM 8,3 % DM 4,4 % DM

∆P

η

Flowrate Shearrate ∆P

Biomass

Example: Milled pine in water Simple flow rheometer

Heat exchange via ‘heat Clamps’

Challenge:

Efficient heat tranfer at high pressure and temperature with no flow constriction (cleanability) Solution: Thermal expansion adapted heat transfer blocks Inconel 625 and special cast iron 12, 6 vs 12,7 x 10-6 K-1 Surprisingly efficinet: 24 m counter current dual tube 25,6 mm Od 13.8 mm Id Delta t 28oC, at 38 l/hr, (280oC) (Comsol model in accord)

Pilot reactor with oscilation – heat recovery

Heat recovery: 79% without oscillation 84% with oscillation Important? Saves more than 20% energy!

07/06/201916/01/2018

Energy analysis – pilotscale

07/06/201916/01/2018

Sludge+ biomass filtration Flow rate (l/h) 60 DM content feedstock 0.25 Time (h) 1 Feedstock consumed (kg, dry) 15 Energy in feedstock (kW, dry) 82.5 Bio-crude yield (wt.%) 41.8 Energy in bio-crude (kW, dry) 62.8 (HHV= 36.1 MJ/kg) nth (%) 76.1 Trim heater energy requirement (kW) 5.4 Reactor energy requirement (kW) 2.5 Main pump energy requirement (kW) 0.7 Sludge filtration unit (kW) 0.6 ntot (%) 68.9 EROI 6.8 (towards 10 in full scale)

And Now it’s ready (Almost)

So pilot scale works – what about full scale

Bio2oil’s mission:

• 1. Produce small standard

size scalable units

• 2. Reduce capex/volume

below that of large scale plant

• 3. Market processes that

are economically feasible without subsidies

?

Bio2oil standard unit

30 x scale-up from Pilot unit in twice the volume Capacity 4000 ton DM/yr - (feed 3 m3/hr) Price tag 2M€ - same or lower than large scale plants Consists of two 40’ containers containing:

• 1. Novel pumping and depressurization units + separation
• 2. Multitube heat-exchanger, heater and reactor

Heat recovery 90%, up to 20% drymatter feed, fully automated IPR on key technologies

Scalablity

• 4000 ton DM/yr
• 15000 ton DM/yr

So pilot scale works – what about full scale

Bio2oil’s mission:

• 1. Produce small standard

size scalable units

• 2. Reduce capex/volume

below that of large scale plant

• 3. Market processes that

are economically feasible without subsidies

?

80€/ton

How to get a feedstock k that warrant a HTL business in Europe

In a no subsidy environment its hard to make a viable HTL business Biomass costs in Europe approaching 80€/ton Feedstock cost >200 €/ton crude oil - no room for processing costs Negative cost feedstocks seem attractive § Waste water treatment sludges have negative cost § But are often available with low DM content (1-5%) § We noticed that our usual HTL feedstocks like wood chips are fibrous after extrusion § What if we could use this material for filtration – a filter aid? § The filter medium adds organic material for the HTL process to produce additional fuel

Sludge filtration using biomass

§ Filtration times reduced form ~ 20 mins to 1 min § Cake resistance reduced by orders of magnitude § 1 filter aid unit required per 4 units of dry sludge § Batch filtration studies used to calculate scaled up continuous operation on continuous filter systems. § WWTP of 200,000 PE requires 3 tons of waste biomass per day for all the sludge filtration on a 8m2 drum

07/06/201916/01/2018

Using biomass filter aid Without biomass filter aid

Bio-crude from sludge

07/06/201923/05/2018

C H N S O HHV (MJ/k g) Energy Recovery (%) With K2CO3 Sludge 72.8 9.7 2.3 0.8 14.4 36.1 55.5 Miscanthus 74.4 7.1 0.6 0.1 17.9 32.1 48.4 Pine 74.2 7.7 0.3 0.0 17.9 33.0 40.3 No catalyst Sludge 74.6 10.1 2.5 0.7 12.2 37.7 66.8 Miscanthus 72.9 6.4 0.5 0.1 20.1 30.3 40.2 Pine 71.1 6.9 0.2 0.0 21.8 30.2 50.7 Sludge Co-liquefaction with biomass filter aid with Miscanthus 74.3 9.3 2.4 0.5 13.6 36.1 80.5 Pine 73.8 9.3 2.2 0.5 14.2 35.9 79.7

Co-liquefaction of biomass filter aid and sewage sludge has synergistic beneficial effects: Higher bio-crude yields than the separate counter parts Higher energy recovery Lower oxygen content use of alkali catalysts for HTL of lignocellulosics is avoided ✘A part of nitrogen ends up in the bio-crude during co- liquefaction Initially we are aiming to make low grade fuel and bitumen

Bio-crude yield Bio-crude composition

Carbon flow in a modern, fully y optimized WWT plant

12% carbon into fuel - CH4

Integration in WWT – what industry wants

• Solve our sludge problem

(digestate)

• Posible but not optimal

solution

• High ash feedstock

Integration in WWT – the simple way

• Fits within normal plant design
• Solves the problem of

pathogens, plastics and drug residues

• Significant reduction of aeration

costs

Carbon-balance

Phosphor recovery – ongoing research

§ At 350°C and 200 bar phosphates and other high valance salts are insoluble in water § Phosphate precipitates and is filtered out continuously § Phosphorous recovery in concentrated solid residue is >95% § We can combine the HTL process water rich in NH4 with PO4 in residue to produce struvite § Efficiencies recovery of ~90% P from incoming HTL feedstock § P is bioavailable

07/06/201916/01/2018

Much wider application

Other negative value feedstocs

• Industrial waste streams
• Municipal solid waste - organic fraction
• Waste wood

Once biocrude get accepted as a key ressource in the refinery industry the economy will be fine for agricultural sidestreams if credtis are taken into account

Summary

• It makes sense to go decentral
• Innovation is needed and it makes sense to take an engineering

approach to bridge the gap between research and production

• Bio2Oil’s modular units are prone to become a game changer –

also in an European market

Big is beautiful

Small

Thank you for your kind attention

Support acknowledged with grattitude from The Danish Innovation Fund - BioValue Horizon 2020 – HyFlexFuel Contact Info Ib Johannsen ibj@bio2oil.dk /ibj@eng.au.dk www.bio2oil.dk