Stainless steel cooler for EGRd-m-s.dk/wp-content/uploads/Jesper-Vejlø-Carstensen-MDT_Stainless... · MAN B&W two-stroke diesel engines Engine type . 5S30ME-B EGR . 6S60ME-C EGR

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Stainless steel cooler for EGR

Jesper Vejlø Carstensen Senior Research Engineer Material Technology & Research MAN Diesel & Turbo Copenhagen


MAN B&W two-stroke diesel engines

Engine type 5S30ME-B EGR

6S60ME-C EGR

12G95ME-C EGR

Weight (ton) 61 350 2.400

Length (m) 4.1 7.7 23.1

Height (m) 6.3 11.3 17.5

Output (MW) 3.2 14.3 82.4

SFOC (g/kWh) 176 168 165

SFOC (ton/d) 13 58 326


Typical exhaust gas composition


Why worry about emissions?

NOx, CO, HC and SOx/PM cause respitory health problems NOx and HC cause ground level ozone NOx and SOx contribute to acid rain NOx cause euthrofication (nutrient pollution)


Basic EGR principle

Exhaust gas loop

O2 in the scavenge air is replaced with CO2.

CO2 has a higher heat capacity thus reducing the peak temperatures.

Reduced O2 content in the scavenge air reduce the combustion speed thus reducing the peak tempera-tures.

Decreased peak temperatures reduces the formation of NOx

EGR = Exhaust Gas Recirculation


EGR unit

EGR inlet pipe & pre-spray (not seen)

EGR coolers

EGR blower

Distribution chamber

Mixing chamber

EGR outlet pipe

EGR scrubber

Water mist catcher


Section of EGR-unit

Section of EGR-unit

Scrubber inserts AISI 316L

WMC AISI 316L

TC cut-out valve

Turbocharger

Prescrubber AISI 904L

EGR-Blower

EGR Drain pipes AISI 316L

EGR-coolers Stainless

Shutdown valve

Reversing Chamfer AISI 316L

H2O +

NaOH


Exhaust gas flow (with EGR)

PRE-SCRUBBER Cools the exhaust gas from approximately 450 to 90°C. Interface for particle and SO2 trapping from the combustion process.

EGR-COOLER Cools EGR gas from approximately 90°C to 31°C. Interface for particle and SO2 trapping from the combustion process.


Exhaust gas flow (No EGR)

EGR-COOLER Cools compressed air from approximately 250°C to 31°C (Operated as normal air cooler).

SCRUBBER No water supplied. Acts as a water mist catcher


Finned tube cooler

Herringbone Wavy Fin

Standard air cooler materials: Tubes CuNi Fins Cu Tube sheet CuZn


EGR cooler function

Exhaust gas: 𝑂𝑂2,𝐶𝐶𝑂𝑂2,𝐶𝐶𝑂𝑂, 𝑆𝑆𝑂𝑂𝑥𝑥,𝑁𝑁𝑂𝑂𝑥𝑥,𝐻𝐻𝐶𝐶, PM (ash, soot

unburned lube/fuel)

Scrubber water: 𝑂𝑂𝐻𝐻−,𝑁𝑁𝑎𝑎+,𝐻𝐻+,

𝑆𝑆𝑂𝑂32−, 𝑆𝑆𝑂𝑂42− ,𝐶𝐶𝑂𝑂23−, Suspended solids from exhaust PM

Cooling water: 𝐶𝐶𝑙𝑙−

(For Sea water cooling

application)

T/C cut-out: Air


EGR cooler environment

Sulphuric acid: H2SO4 (e.g. 46 l/h at 61% load) Other acids: HNO3 – HCl – (CO2) Chlorides: Cl- (e.g. 10-70 ppm)

pitting

stress corrosion cracking

Addition of NaOH to scrubber water: 2NaOH + H2SO4 → Na2SO4 + 2H2O (neutralisation) Presence of Na2SO4 in scrubber water: sulphate inhibition

R. Mellström and S. Bernhardsson 9th Scandinavian Corrosion Congress Copenhagen, 1983.

316L


Stainless steel for EGR cooler

Crystal structure Composition (wt%) C Cr Ni Mo Other Austenite <0.08 16-30 8-35 0-7 N, Cu, Ti, Nb Ferrite <0.08 12-19 0-5 <5 Ti Martensite >0.10 11-14 0-1 - V Duplex <0.05 18-27 4-7 1-4 N,W

Pitting Resistance Equivalent Number

(PREN) = %Cr + 3.3 % Mo + 16 % N

High Cr, Ni and Mo provides best resistance in sulphuric acid

Austenitic stainless steel Nickel Institute1983


Stainless steel for EGR cooler

C.Vogel, C.Juhl & E.Maahn: Metallurgi for ineniørerg

Good formability for tubes in tube plates

Austenitic stainless steel


Stress corrosion cracking

C.Vogel, C.Juhl & E.Maahn: Metallurgi for ingeniører

EGR-COOLER (No EGR) Cools compressed air from approximately 250°C to 31°C

EGR-COOLER (EGR) Cools EGR gas from approximately 90°C to 31°C..


Salt deposits on EGR cooler

Salt deposits (Na2SO4 ) on cooler (the salt will be dissolved by the scrubber water when EGR is running)


Cooler corrosion

Malfunctioning NaOH feeding in scrubber water pH = 1-3 + no inhibition


Cooler corrosion


EGR cooler with seawater

316L

904L

654SMO

Tverberg et al. 2005 Stainless Steel World

Seawater ≈ 3% Cl-


Acknowledgments

For contributions to this presentation I would like to thank: Jannik B Pedersen Research Engineer MAN Diesel & Turbo Copenhagen Claus H Ibsen R&D Manager VP Industries/Vestas Aircoil


Thank you for your attention


Jesper Vejlø Carstensen MAN Diesel & Turbo Teglholmsgade 41 DK-2450 Copenhagen SV Denmark Phone +45 51290572 E-mail [email protected]

Contact


All data provided in this document is non-binding. This data serves informational purposes only and is especially not guaranteed in any way. Depending on the subsequent specific individual projects, the relevant data may be subject to changes and will be assessed and determined individually for each project. This will depend on the particular characteristics of each individual project, especially specific site and operational conditions.

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Stainless steel cooler for EGRd-m-s.dk/wp-content/uploads/Jesper-Vejlø-Carstensen-MDT_Stainless... · MAN B&W two-stroke diesel engines Engine type . 5S30ME-B EGR . 6S60ME-C EGR