drum boilers for thermal oil recovery process

[vesselguy]

I am researching on the subject of boilers for SAGD application. I am familiar with OTSG but have no experience with drum boilers. Can anyone here tell me what type of drum boiler is used for a thermal enhanced recovery (SAGD) application and who makes them? Is it the same type of dual drum boilers you see in large building steam plant? i.e., the direct fired type with a mud drum and a steam drum with raisers and downcomer tubes connecting the two.

 

[rmw]

Vesselguy, I have worked with boilers most of my career which spans over 3 decades and the only thing I understood about your post was steam drum, mud drum and downcomers. Can you repeat this without the acronym soup? (I did understand once through, however.)

Now from what little I did understand, the steam generators that I have seen used in recovery operations weren't constructed like those that were designed to have firing equipment and the incumbent furnaces. But, the did have drums, and tubes, so they were similar in that way.

Thermal oil heaters, on the other hand, whether direct fired or heat recovery, did not resemble boilers in any way other than they both had tubes.

rmw

 

[davefitz]

See attached link for the economic interplay between boiler configuration and wastewater/ water reclamation process. It assumes nat gas is the fuel source.

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http://www.ptac.org/env/dl/envf0802p12.pdf>

The Original 3 arch-fired boilers at Suncor were drum boilers, natural circulation, but pre-dated the SAGD process as practiced today. I am not sure how the water reclamation processes now used would impact the design of the boiler, but certainly a drum style boiler , using fluidized bed combustion of the mined bitumen, could generate the required steam while mitigating the SO2 emissions which damned the original arch-fired units.

The older once thru units for enhanced oil recovery were of a Sulzer design, with a high blowdown rate ( about 5% blowdown) to remove excess disolved solids and salts - The IST OTU seems to incorporate a similar philosphy. It is essential that no tube "dries out" entirely prior to passing through the salt rmeoving blowdwon stage, or else acumulation of solds and/or acclerated corrosion may occur. The IST use of 100% incolnel may address corosion, and allows "dry firing" in some instances.

A gas fired OTU is also able to be constructed on a small footprint with minimal construction time, and may also be desinged for eventual relocation to other sites, while a large stick built drum boiler is meant to stay put and has a longer construction lead time.

 

[vesselguy]

davefitz,
Thanks for your reply.
Yes, fuel is natural gas and produced gas.
I have worked on 2 OTSG projects before but never a drum boiler. I just wanted to confirm if this is the type of drum boilers people are using in SAGD

http://www.energymanagertraining.com/equipment_all/boiler/img/boiler_1.jpg

You would think a stick built drum boiler would cost more than an OTSG due to expensive site labour. I understand that it is infact opposite. Any insight into why? Thanks.

 

[davefitz]

I am not familiar with the pricing of the IST OTU , but if it is made of 100% incolnel and the drum boiler ( sat steam) is 100% carbon steel, then the cost difference is likely the material cost difference of CS vs incolnel.

If it was my decision, the nat gas firing would occur in a combustion gas turbine, the lectricity would be sold to Calgary, and the exhuast gases would flow over a HRSG whose sat steam would be used for the SAGD. If the gas turbine is an aeroderivative, its exhuast gas temp is below 1000F so evan a dry-fired OTU can be made of ferritic T23 , and not incolnel.

 

[rmw]

Here is a view of several CCGT plants as described by Davefitz whose steam production is used for enhanced recovery in California. I think that the majority of these are drum type if I remember correctly.

rmw