2011 Project Success Highlights

Project:  HRST was contacted by a facility running a waste heat boiler with a unique drum level problem...the level was 5" to 6" higher on one end.  Having only 10" of operational range between low and high water trip points meant that the level was within 2" of both trip points at all times!

Discussion of the problem history revealed the usual suspects (transmitter calibration, instrument plumbing/installation, plugged level taps, etc) had been checked and rechecked.  The boiler manufacturer had also been to the site twice to make modifications that did not solve the problem.

An HRST engineer went to the site to gather information.  Review of drawings and a drum inspection revealed a problem with the design of the primary steam separation equipment.  An issue with the secondary steam separator was also identified during the on-site closing meeting, and the plant revealed that carryover has also been a problem with the boiler.

After a brief study, HRST redesigned the drum internals and had them fabricated.  The small drum size required a custom cyclone separator design.  The new cyclones were installed by a local contractor with a redesigned secondary separator to stop carryover.  Upon restart, the level difference between drum ends was measured at less than one inch, and the steam purity was within specification.  Problem solved!

More 2011 Project Successes:

1. Many, many HRSG inspection and troubleshooting projects. 
2. Acoustic baffle design and materials
3. Center gas baffles
4. DA spray nozzle gaskets
5. Forged Nozzles
6. Economizer ShockMaster Retrofits
7. "Gang Seal" pipe penetration seals
8. Gas Baffle Doors
9. Header perforated plates
10. HP desuperheater drain pot design
11. Inlet duct liner materials replacement #2
12. LP Drum liner design and materials
13. Drum manway gaskets
14. Side wall baffle design
15. Tube plugs
16. Numerous boiler roof and floor fabric pipe penetration seals
17. Numerous boiler roof and floor metal pipe penetration seals
18. Retrofit easy-open access door kits for HRSG walls and roofs
19. FAC tube sleeve inserts
20. Tube tie repair design and materials
21. Wall and floor liner clips, flashings and shims

 2010 Project Success Highlights

Project:  After 20-plus years of operation with no maintenance, a client’s HRSG flow distribution baffle began to have problems. Investigation concluded that their recent need to operate at low turn-down on their GT was the problem. The decreased exhaust mass flow increased turbine exhaust temperature. The higher temperatures to the HRSG decreased the strength of the flow distribution baffle located in the inlet duct, just upstream of the duct burner. Soon the perforated plate section of the flow baffle experienced significant cracks, and began to progressively bow, threatening to impinge on the duct burner. A replacement baffle assembly was needed and HRST was asked to help. Because the original design was so successful, the user wanted a mostly in-kind baffle replacement but with a few upgrades to withstand the more severe operating conditions while still meeting the original design criteria. HRST designed and supplied the upgrade. Our on-site technical advisor, field installation drawings, and a hard-working contractor hired by the client made the work go quickly and smoothly.

Above:  Installation of new HRST supplied Perforated Plate Flow Element sections.

Project:  One of our customers came to us with an interesting request and challenge. “Help us keep the Peregrine Falcons from diving into our HRSG stack at high speeds and then not being able to find their way back out.” After careful consideration on a deterrent that would not restrict gas flow and yet stop our speedy feathered friends, the solution was a large stack screen with a stainless steel grid on a stainless frame that will be visible to the birds and resist corrosion. Thanks to some creative HRST design features, the screen was installed on a 230’ high stack in a matter of about 20 minutes from the time it was hoisted off of the ground until it was set in the top of the stack. Installation took place back in June and last we heard the birds are safe and happy and the plant owners are happy with their new bird screen. We can now add “bird-friendly” to our list of product features!

Above:  Installation of HRST supplied Bird Screen on HRSG Stack.

More 2010 Project Successes:

1. Many, many HRSG inspection and troubleshooting projects. 
2. Slide plate replacements for HP Steam Drum saddles.
3. Structural stiffening ring retrofit for out of round circular inlet duct.
4. Improved duct burner element supports.
5. ASME code calculations for condition assessment benchmarking.
6. Layout and installation drawings for inlet duct liner replacement.
7. Quick open boiler Access Doors.
8. Inspection Repair Procedure and Materials.
9. High-lateral movement HRSG pipe penetration seals.
10. Boiler sidewall pipe penetration seal assembly.
11. Replacement HRSG roof casing design and supply.
12. HRSG Tube Tie Repair Design and materials
13. HRSG Side Wall Pipe Penetration Gang Seals
14. Retrofit Wear Plates for inside Blowdown tank
15. T-91 tube stubs
16. SA-178A bent tube stubs
17. HRSG Inlet Duct Liner redesign, supply and install technical advisor
18. Cold Reheat to Hot Reheat bypass design and material supply
19. Upgraded steam drum manway yokes
20. Superheater drain piping redesign, material supply, including pipe casing seals
21. HRSG Floor Pipe Penetration Seals
22. HRSG Inspection and Warranty Problem Evaluation in Pakistan

2009 Project Success Highlights

Project:  A USA power plant found longitudinal and circumferential cracks in their boiler's 8 inch, 650psig, 950 deg F steam pipe for export steam. The cracks were downstream of the desuperheater and the original configuration did not include an internal thermal liner to protect the pipe wall from the water spray. HRST supplied a new section of pipe which included a mounting designed for their new desuperheater spray probe, plus a thermal liner to avoid future water spray thermal shock. Our on-site technical advisor helped to ensure that the installation contractor followed all applicable code criteria for a successful installation. (Photo below)

Above Left:  Retrofit Desuperheater Assembly.  Above Right:  Retrofit IP Economizer Headers

Project:  Inspection revealed an HRSG economizer design that creates stress during start-ups and shutdowns.  Reliability was important for the client, so we modified the design and supplied the needed retrofit IP economizer headers.  (Photo above.)

More 2009 Project Successes:

1. Many, many HRSG inspection and troubleshooting projects.
2. Liner plates, studs and technical advisor to repair HRSG inlet duct damaged.
3. HRST Shockmaster economizer conversion engineering.
4. Retrofit IP Economizer headers for improved cycling of HRSGs.
5. HRSG flow distribution perforated plate design and fabrication.
6. Improved pipe penetration seals for HRSG sidewall, floor and roof pipes.
7. Replacement liner system design for HRSG floor liner.
8. Reheater desuperheater temperature monitoring kit.
9. Economizer replacement fabrication drawings.
10. Boiler Superheater Tube Support Improvements.
11. Designed improved HRSG gas baffling improvements
12. Designed Superheater Drain System improvements
13. Steam drum manway door, hinges and gasket alignment kits.
14. Supply of improved retrofit HRSG Access doors.

2008 Project Success Highlights

Project:  Shortly after their 2008 plant commissioning, a client experienced failed fabric pipe penetration seals in the high temperature Superheater/Reheater section. After having difficulties with the OEM on getting a better design, the plant came to HRST for a solution. First we inspected their arrangement to assess their needs. Some of their pipe seals required allowance for extra lateral expansion and angular rotation on the piping. In the end, we provided 18 bottom seals, 20 roof seals, 16 inner liner donuts and 1 access door. Problem solved!

Before                                                   After

More 2008 Project Successes

1. HRSG Inspection and Troubleshooting: 160+ HRSG’s in 2008.
2. Numerous HRST retrofit Pipe Penetration Seals supplied for HRSGs.
3. Designed and supplied the first triple-pipe penetration gang seal.
4. Redesign existing tube ties/supports to eliminate tube rattle and vibration at several HRSG plant sites.
5. Provided tube bundle cleaning procedures and tools for several HRSG plants.
6. Supplied new evaporator tube panels and a technical advisor to improve HRSG reliability.
7. Designed and supplied a complete casing, liner and penetration seal replacement under hot section of an HRSG.
8. Designed and supplied three retrofit HRST Shockmaster economizers to improve HRSG reliability.
9. Supplied tube material for emergency tube repairs.
10. Redesigned a steam separation system in steam drum to avoid carryover.

This list is only a portion of our 2008 projects.  Give us a call to see if we have tackled your problem on a previous project.