Increasing OTSG Steam Quality While Operating on Conventionally Treated BFW Albert Mansour, MBA, PMP, B.A.Sc.

Transcription

1 Increasing OTSG Steam Quality While Operating on Conventionally Treated BFW Albert Mansour, MBA, PMP, B.A.Sc.

2 Once Through Steam Generator (OTSG) Boiler eedwater (BFW) Radiant Section Convective Section Dry Steam 75% - 80% Wet Steam Quality (Typical) Separator (SAGD) Blowdown (Wet Steam Water Content)

3 Limits to Higher Steam Quality Typical OTSG radiant section piping is smooth Radiant pipe operates under annular flow regime Annular flow is a dispersion of water on the pipe surface with entrained droplets in the core steam flow Annular flow regime

4 Limits to Higher Steam Quality Traditional OTSG steam quality limits are between 75% and 80% BFW impurities concentrate in remaining water before exiting OTSG At higher steam qualities, smooth pipes have low water quantity on the pipe surface Operation above 80% may lead to scale deposit formation due to dry spots Deposits can lead to pipe overheating and failure

5 Annular at 80% Steam Quality Pipe Wall Higher Concentration Impurities (Thicker Bottom Film) Lower Concentrated Entrained Droplets (Non-Uniform Impurity Concentrations) Surface Water Film Layer

6 Solutions to Achieving Higher Steam Quality SQ90 TM Utilizing modified (rifled) piping in select radiant section pipes to allow OTSG to operate at 90% steam quality Centrifugal force moves all remaining water to the pipe surface All water is now located on the pipe surface

7 Fully Developed at 90% Steam Quality Using SQ90 TM Rifled pipe wall Lower Concentrated Entrained Droplets (Non-Uniform Impurity Concentrations) Higher Concentration Impurities Surface Water Film Layer (Thicker Bottom Film)

8 90% Steam Quality Benefits Constant Fuel Input Quality BFW BFW Temp Operating Parameters Fuel Heat Input Blow- Down Rate Dry Steam Rate Blow- Down Dry Steam % Change BFW % m 3 /hr Deg C MW (LHV) m 3 /hr m 3 /hr % % % % Fuel Typical 64.5 MW OTSG, 100bar(a) steam pressure Increased steam / production capacity Reduced BFW requirement Reduced blowdown volume

9 90% Steam Quality Benefits Constant Dry Steam Operating Parameters Quality BFW BFW Temp Fuel Heat Input Blow- Down Rate Dry Steam Rate Blow- Down Dry Steam % Change BFW % m 3 /hr Deg C MW (LHV) m 3 /hr m 3 /hr % % % % Fuel Typical 64.5 MW OTSG, 100bar(a) steam pressure Reduced fuel consumption Reduced BFW requirement Reduced blowdown volume

10 Benefits of 90% Steam Quality Constant Fuel Heat Input Constant Dry Steam

11 Pigging OTSGs can be pigged using standard pigging procedures Screw head attachments used as a rough cleaning of smooth piping which also cleans the rifle tips Pin attachments are for cleaning smooth piping and rifle valleys Number and alignment of pig pins match rifle profile Pigging Frequency does not change when operating at 90% steam quality Screw head pig for cleaning rifled tips Pin pig for cleaning between rifles

12 Pigging Pigs successfully pass through entire pass Pig core markings indicate that the pig travelled through the pipe pattern Inspections show no evidence of fouling or gouging of the tubes

13 Additional Points 90% steam quality is achievable using the same BFW as a 75% - 80% OTSG Technology has been retrofitted in OTSGs (>220MMBtu/hr) operating at producing faculties in Alberta OTSGs supplied by IST in Alberta / Saskatchewan operate at 90% steam quality Devon Jackfish 2 pilot is currently taking place

14 Devon Pilot Objectives Validate the process guarantee (90% steam quality) Validate reliable operation Establish optimum operating limits Collect baseline data for commercialization Validate potential to improve water usage Reduction in blowdown up to 58% Reduction in makeup water up to 15% Reduction in water throughput up to 9.6%

15 Thank You Albert Mansour Innovative Steam Technologies (IST)