Complex heat recovery systems are Nooter/Eriksen’s specialty. All systems are designed for maximum reliability, efficiency and availability. The heat recovery systems for each specific application is custom designed to meet the customer’s requirements at the lowest possible cost without sacrificing quality or more maintainability.

N/E performs a complete engineering analysis
 to assure the industry’s most well-planned
 and efficient installation. Using state of the art
 computer aided design methods, entire
 systems are modeled to prevent interferences
and expensive rework at site. N/E is the
industry leader in providing HRSGs with constructability features that minimize field installation labor and shorten construction schedules. N/E’s design features provide optimum flexibility in the installation sequence, taking into account transportation limitations, while maximizing overall shop fabrication.

Using state of the art
computer aided design methods, entire
 systems are modeled to prevent interferences
and expensive rework at site.


There are several major areas that are affected by cycling an HRSG:

  1. Equipment flexibility

  2. Potential equipment malfunction

  3. Operational concerns

  4. Fatigue of thick pressure parts

As units have become more and more cyclic, Nooter/Eriksen has learned that there are several very important things that must be done to ensure the equipment will operate reliably. Some of these features directly address the concerns owners have regarding cyclic units and others are offered as options to help make equipment last longer.

N/E knows there are several important factors that must be done to ensure all cyclic service equipment operates reliably. 

HP Superheater and Reheater Coil Flexibility  

All coils in N/E designed HRSG’s are top supported. N/E is the only supplier to provide constant load spring supports on one of the upper headers. All tube to upper support connections are straight with no bends to create less moment stress magnifiers. Further, the attaching piping which can also restrain the lower headers and prevent free vertical expansion is routed such that good vertical flexibility is provided.

Lower Header Coil Restraints 

N/E’s coil restraints are specially designed to allow all tube rows to expand in the vertical direction freely but at the same time allow for gas flow induced movement restraint.

External Piping 

When possible, avoid top to bottom routing of piping from one coil to the other. 

High Chrome Materials 

For cyclic units it is important to keep the thickness of key components as thin as possible. N/E has substantial experience with all alloy materials (low to high alloys).

Stack Dampers

One method of assisting in maintaining temperature and pressure within the HRSG during a period of shutdown is the use of a Stack Damper. N/E can offer this type of equipment as an option. For further heat retention we recommend that the exhaust stack be insulated up to the stack damper. N/E can offer this type of equipment as an option.


To minimize the potential for desuperheater condensate tube quenching, it is N/E’s standard to supply inline condensate pots cycling capabilities upstream, downstream or both from the desuperheater location. All N/E HRSG’s are supplied with thermocouples at appropriate distance downstream of the desuperheaters. 

Combined Upper and Lower Headers

It is N/E’s standard to never use partition plates when the headers are tied together top and bottom. The standard approach would be to split the lower headers apart into pressure levels so the tubes can expand independently of the other pressure section.

Tube Stub to Header Connections 

Helps minimize header thicknesses.


With a straightforward approach to installing HRSGs, N/E is dedicated to reducing the erector’s time on site with innovative features and options for enhanced constructability. Other OEM’s offer what they call modular construction, but N/E has continued to improve our modular construction over the past 25 years. We offer multiple modularization designs to suit your site locaiton and labor cost needs. Our objective continues to be to reduce field man‑hours.

Standard features that reduce field man-hours

N/E has developed several standard features that dramatically reduce field man-hours.

  • Minimizes riser piping welds and casing penetrations
  • Swagelok type tubing for atmospheric drains
  • New and improved secondary panel handling and temporary fit-up makes for faster casing erection
  • Compression fit casing wall to floor and roof design simplifies connection and eliminates packed head seams
  • Improved vertical field seams reduce field man-hours

Options for enhanced constructability

Whether it be before or after an order,
N/E can offer options to enhance constructability at most sites.

  • Bolted moment connections
  • Extra large modules
  • Valves shop-welded in piping
  • Shop installed pipe support stanchions
  • Shop fabricated small bore piping
  • One crane lift device
  • Drum trim shop fabricated


HRSGs can be designed to include important features to meet the latest thermal environmental standards. In addition to extensive experience with selective catalytic reduction (SCR) systems and oxidation catalysts and VOC units, N/E has developed its own noise attenuation technology, with results substantiated at over 30 installations.