Design Enhancements & Material Upgrades
Manway System Upgrade
For lack of information about better solutions, some HRSG operators are unknowingly employing unsafe or outdated practices for sealing of HRSG Drum Manways. This occurs particularly in their high energy steam drums. Over the past few decades the power industry has seen numerous incidents of spiral wound gasket failures on High Pressure Drum manway systems resulting in injury, loss of life and significant property damage.
Ensuring safe and reliable operation of your HRSG is of critical importance and Nooter/Eriksen is able to support this effort with simple and inexpensive modifications to this most critical component. By evaluating the drum manway as a complete engineered system instead of a series of individual components, Nooter/Eriksen offers a combination of specialized hardware packaged with a proven installation procedure that removes the need to hot torque and reduces the likelihood of forced outages due to cycling related leaks. Appropriate second generation “Steel-trap” gasket types designed specifically with sealing of a drum manway in mind, provide a reliable seal against the unique requirements presented with sealing elliptical manway doors. When packaged with live-loaded Disc Spring Washer stacks, N/E was able to engineer a system that provides a reliable seal even under daily cyclic operation.
Split Plate Design
Manway Cover Resurface
Manway Ring Resurface
Economizer Drain Consolidation
Many early HRSGs designs consist of overly complicated preheater and economizer drain systems. In addition to causing physical access restrictions to the drain valves for routine opening and maintenance, these designs can contribute to long-term susceptibility in the heat transfer coils themselves to damage from flow bypass. Due to slight pressure drop as fluid passes through a heat transfer coil, the drain valves for individual headers further upstream and downstream in a coil will have slightly different pressures. Flow bypass occurs when two or more header drain valves in the same cluster have begun to leak by and this slight pressure variation drives bypass flow. Because of differences in fluid temperature at these headers, leaking drain valves has been known to contribute to localized tube failures in the coils at or near the drain locations as colder water is introduced into hotter tubes, creating localized thermally induced stresses.
Small Bore Leaks
Large Bore + Small Bore Leaks
Nooter/Eriksen has developed solutions for all these issues and is able to offer them as a fully inclusive drain retrofit that offers numerous advantages to the reliability of the HRSG and eases the life of the HRSG operators and maintenance personnel.
For HRSGs that are 2 or more bundles wide, N/E will consolidate the drain lines inside of the HRSG ductwork. This reduces the total number of drain penetrations through the casing.
- This will reduce the number of drain bellows by up to two thirds.
- Likewise, this will reduce the number of header drain valves by up to two thirds.
N/E will upgrade from Globe valves to metal seated ball valves.
- These valves are much more resistant to erosion in this application and provide a more reliable shut-off reducing the risk of flow bypass.
- Additionally, these are quarter turn valves that allow operators and maintenance personnel to be able to open or close valves in a fraction of the time as the current globe valve configurations.
N/E will use inverted drain bellows designed to operate internal to the flu gas. This prevents trapped moisture and the external erosion of drain lines.
N/E is able to orient and place the new drain manifolds in such a way as to increase overall access to the HRSG underside and consolidate the valves to a centralized location.
Original Layout Example
New Layout Example
Casing Penetration Seals
Inverted drain bellows
The inverted drain bellows retrofit is a Nooter/Eriksen Aftermarket upgrade used to address corrosion issues in cold-end HRSG drains. Corrosion issues can result in expensive and repetitive maintenance. This will shorten the life of bellows themselves and sometimes lead to forced outages. Because of their location on the O.D. of the drain line and inside the metal bellow. The issues are nearly impossible to inspect and predict. This makes it difficult to provide the appropriate preventative maintenance. By designing a bellow that is intended to be used internal to the flue gas environment, Nooter/Eriksen is able to offer a solution that does not trap moisture and can easily be installed during times of simple drain line maintenance.
Trapped Water and Debris
Inverted Bellow Solution
The use of Metal bellows for penetration seals of large bore process pipe penetrations has many advantages over traditional fabric expansion joints. These bellows have a greater cycle life when compared to their fabric counterpart and will last considerably longer. However, the installation of such joints creates significant challenges and as a result they are not easily replaced in the field. Consider using these joints any time the opportunity presents itself when maintenance of the corresponding process piping or nozzle is being performed. Nooter/Eriksen also has experienced construction crews that specialize in the conical welding required to install these joints without the removal of the nozzle.
Conical Field Welding
Vibration Support Upgrade
Turbine modifications often lead to increased vibration and noise in the unit. The front coil vibration supports will endure the majority of this abuse. Nooter/Eriksen has successfully completed many upgrades/retrofits to a more robust design that is far better suited for higher turbulent environments.
Vibration Support Upgrade/Retrofit
Scallop Bar Upgrade
As an OEM supplier Nooter/Eriksen has the knowledge and resources to both supply replacements and evaluate best suited upgrades when it comes to valves. Typically, piping and valving upgrades can improve the long-term efficiency and ease of maintenance of the HRSG. We have decades of experience available to help solve any valve related issue that you may encounter.
Field Install of NRV
HP IP Economizer Drain
Drain Upgrade Valves