From: "Robertson, Dougie (Houston)" <Dougie.Robertson@deepwater.com> 

To: Melanie King/RTP/USEPA/US@EPA 

Cc: "Pelley, Darrel (Houston)" <Darrel.Pelley@deepwater.com>, "Hayes, Dennis (Houston)" 

<Dennis.Hayes@deepwater.com>, Kelly 

Fortin/R4/USEPA/US@EPA, Jessica Montanez/RTP/USEPA/US@EPA 

Date: 05/25/2012 12:01 PM 

Subject: RE: Quad Z CO emissions paper.

Melanie, 

Further to our discussion this morning, here’s a quick synopsis on low load operations of our main engines. 

Regards 

Dougie 

Douglas A Robertson 

Senior Engineering Specialist 

Room 741 

4 Greenway Plaza 

Houston TX 77046 

Direct Line 1(713)232-7120 

dougie.robertson@deepwater.com 

80% Preparation, 20% Application... 

From: Melanie King [mailto:King.Melanie@epamail.epa.gov] 

Sent: Thursday, May 24, 2012 15:17 

To: Robertson, Dougie (Houston) 

Cc: Pelley, Darrel (Houston); Hayes, Dennis (Houston); Kelly Fortin; Jessica Montanez 

Subject: Re: Quad Z CO emissions paper.

Question, this analysis seems to focus on the main power engines on the vessels. So am I 

understanding correctly that those engines are your main concern, and not other engines on the vessels 

that would also be subject to subpart ZZZZ, crane engines for example? 

Melanie King 

Energy Strategies Group 

Sector Policies and Programs Division 

Office of Air Quality Planning and Standards 

U.S. Environmental Protection Agency 

Mail Code D243-01 

RTP, NC 27711 

Phone: (919) 541-2469 

Fax: (919) 541-5450 

king.melanie@epa.gov 

 "Robertson, Dougie (Houston)" ---05/18/2012 11:51:04 AM---Melanie, Rather than delay further with 

gathering further input, here's our concerns with introducin 

From: "Robertson, Dougie (Houston)" <Dougie.Robertson@deepwater.com> 

To: Melanie King/RTP/USEPA/US@EPA 
Cc: "Pelley, Darrel (Houston)" <Darrel.Pelley@deepwater.com>, Kelly Fortin/R4/USEPA/US@EPA, "Hayes, Dennis 

(Houston)" 

<Dennis.Hayes@deepwater.com> 

Date: 05/18/2012 11:51 AM 

Subject: Quad Z CO emissions paper.

Melanie, 

Rather than delay further with gathering further input, here’s our concerns with introducing CO regulations to 

offshore regulations. Can you take this into consideration when instigating CO regulations next year. 

Regards 

Dougie 

Douglas A Robertson 

Senior Engineering Specialist 

Room 741 

4 Greenway Plaza 

Houston TX 77046 

Direct Line 1(713)232-7120 

dougie.robertson@deepwater.com 

80% Preparation, 20% Application... 

CONFIDENTIALITY NOTICE: The information contained in this email and any attachments 

may be privileged, confidential, or proprietary to Transocean. If you are not the intended 

recipient, you are prohibited from using, copying, relying upon, or disseminating the information, 

and the sender disclaims any liability for such unauthorized use. Further, if you are not the 

intended recipient, please notify the sender immediately and delete the message from your 

computer. Thank you. [attachment "40 CFR 63 Subpart ZZZZ discussion.docx" deleted by 

Melanie King/RTP/USEPA/US] [attachment "Emissions comparison.xlsx" deleted by Melanie 

King/RTP/USEPA/US] [attachment "proposed_toxics_rule_appendices.pdf" deleted by Melanie 

King/RTP/USEPA/US] [attachment "Region 4 drilling limit print.pdf" deleted by Melanie 

King/RTP/USEPA/US] [attachment "Topgrahical G of M print.pdf" deleted by Melanie 

King/RTP/USEPA/US] [attachment "IOXI drawing.pdf" deleted by Melanie 

King/RTP/USEPA/US] [attachment "NOR with integrated Oxi W32 dimensions.pdf" deleted by 

Melanie King/RTP/USEPA/US] [attachment "toioxycat2 doc.pdf" deleted by Melanie 

King/RTP/USEPA/US] 

CONFIDENTIALITY NOTICE: The information contained in this email and any attachments 

may be privileged, confidential, or proprietary to Transocean. If you are not the intended 

recipient, you are prohibited from using, copying, relying upon, or disseminating the information, 

and the sender disclaims any liability for such unauthorized use. Further, if you are not the 

intended recipient, please notify the sender immediately and delete the message from your 

computer. Thank you. (See attached file: Marine Engine Low load operations.docx)(See attached 

file: operational compressor map.pdf)(See attached file: Test bed charge air pressure.pdf)
 

Transocean Offshore Deepwater Drilling, Inc. 

Engineering and Technical Support 

Corporate Engineering 

Marine	Engine	Low	load	operations	

Modern marine diesel engines are designed with high thermal efficiency, now over 60%, 

where smaller, higher speed diesels are in the 40-45% range. The major difference in the 

design is in the combustion space design. 

In smaller, higher speed diesels, they use a high swirl piston or prechamber design that is 

highly efficient in mixing the air and fuel to achieve combustion closer to stoichiometric 

combustion. However, in designing these complicated chambers, this reduces the strength 

of either the piston or the cylinder head. In larger diesel engines, a quiescent combustion 

system is used, in this the combustion space is much simpler and as such has inherent 

strength built in. 

 

The reason that the marine diesel engine 

gets such high efficiency is that as the combustion space is designed with inherent 

strength, the air that is fed into the cylinder can then be much greater. This is 

accomplished with high gain modern turbochargers that are capable of raising the charge 

air pressure to historically high values. For example, the Vasa 12 V 32 charge air 

pressure rises from 1.8 Bar (26 PSI) to 2.65 Bar ( 38 psi) when the load rises from 75 % 

to 100%. This air pressure and volume allows the engine designers to obtain these high 

thermal efficiency figures. 

However, to get the turbocharger to get up to sufficient speed to generate the required air 

flow, the engine needs to be loaded up to allow sufficient gas flow to spin the 

turbocharger; the attached turbocharger map shows the great difference between the 

designed running position of 85% and a MODU’s 25%. This leads to a much reduced air 

flow. 
[Recipient Name] 

May 25, 2012 

Page 2 

This reduced air flow then lowers the actual air/fuel mixing in cylinder and leads to 

additional partially unburned hydrocarbon’s passing into the exhaust stream. This then 

leads to fouling of any obstruction in the gas path.