HEAT RECOVERY UNITS
PART 1 GENERAL
A. Section includes: Section Includes: Heat recovery unit (HRU) and all controls and
accessories for a complete operable system.
B. All supplied components of the HRU shall be furnished and fully integrated by the
HRU system supplier, having Unit Responsibility, in a complete package with all
piping, wiring and controls included:
1. System supplier shall be responsible for furnishing and installation of all piping,
valves, and wiring within the HRU package.
2. CONTRACTOR shall be responsible for furnishing and installing all
interconnecting piping, wiring and conduit between the HRU package and the
fuel cell mechanical balance of plant (MBOP).
C. Related Sections:
1. Section 01140 - Work Restrictions.
2. Section 01330 - Submittal Procedures.
3. Section 01600 - Product Requirements.
4. Section 01612 - Seismic Design Criteria.
5. Section 01614 - Wind Design Criteria.
6. Section 01756 - Testing, Training, and Facility Start-Up.
7. Section 01782 - Operation and Maintenance Data.
8. Section 09960 - Coatings.
9. Section 15050 - Basic Mechanical Materials and Methods.
10. Section 15052 - Basic Piping Materials and Methods.
11. Section 15958 - Mechanical Equipment Testing.
12. Section 16010 - Electrical Requirements.
D. Inclusion of a specific manufacturer’s name in the Specifications does not mean that
the specific manufacturer’s standard product will be acceptable. Specified
manufacturer’s or other manufacturer’s standard product shall be modified as
required to meet the Specifications.
A. American Society for Testing and Materials (ASTM).
B. American Society of Mechanical Engineers (ASME).
C. American National Standards Institute (ANSI).
D. American Welding Society (AWS).
E. National Electrical Manufacturers Association (NEMA).
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1.03 SYSTEM DESCRIPTION
1. The HRU shall include the following components as recommended by the
B. Heat Recovery Silencer:
1. The heat recovery silencer shall be a vertical type, single- or multi-pass gas
flow, shop-assembled unit designed to recover the sensible heat energy
contained in gas exhausted from a Fuel Cell Energy, Inc. DFC300MA fuel cell
MBOP and transfer it to the plant hot water system.
C. Full Port Exhaust Bypass Assembly:
1. The HRU shall be provided with a full port exhaust bypass assembly located at
the top of the heat recovery silencer.
2. The full port exhaust bypass assembly shall provide for modulated bypass with
leakage less than 2 percent to control turn down performance and/or
excessive flue gas backpressure due to fouling.
D. Liquid Temperature Control Assembly:
1. A liquid temperature control assembly shall be provided to control the full port
exhaust bypass to maintain leaving water temperature.
A. Submit in accordance with Section 01330 and Section 15050.
B. Operation and Maintenance Manuals: Submit in accordance with Section 01782.
C. Submit data and shop drawings in accordance with Section 01330. Data and shop
drawings shall contain complete dimensions with sufficient detail to define the
installation, anchor bolt layout, piping connections, wiring connections, and special
requirements. Data and shop drawings should include as a minimum:
1. Operational descriptions of all components.
2. General arrangement and outline drawings of each HRU package indicating
dimensions, weights, materials of construction, piping interfaces (size, type,
and location), electrical and control interface locations and details, location and
relationship of key components, and other pertinent data as may be necessary
to support the ENGINEER's layout and design of interconnecting mechanical,
piping, electrical, and controls work.
3. Dimensioned drawings, specifications, characteristics, and other original
equipment manufacturer (OEM) technical data for each item of equipment
furnished including, but not limited to, piping specialties, safety relief valves,
regulating and control valves, and instrumentation and control components.
4. Pressure settings of all safety-relief valves including their cracking pressure,
backpressure at full flow, and reset pressure. The flow rate from each
safety-relief valve at full flow shall also be provided.
5. Provisions for handling at the jobsite during unloading, moving, and
installation, and provisions for permanent support and mounting.
6. Normal and maximum loads (weights, thrusts, etc) which must be carried
externally during installation and operation, and limitations on any loads which
may be imposed on the HRU system by external elements.
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7. Provisions and requirements for normal access and service, and special
allowances required for proper maintenance.
8. ASME boiler and pressure vessel (B&PV) Code, Section VIII, Division 1,
design calculations stamped by a licensed ASME boiler inspector.
9. A materials list for all fabricated structural and fluid containing components. All
such material outside the code boundary shall be listed by their ASTM
designation. All fabricated and fluid containing components within the code
boundary shall be listed by their ASME B&PV code designation or ASTM
designation as specified by the ASME B&PV code.
10. Mill certifications for materials used in all pressure containing components
within the ASME B&PV code boundary.
11. Seismic calculations and anchor bolt sizing in accordance with Section 01612.
12. Wind calculations and anchor bolt sizing in accordance with Section 01614.
13. List of spare parts included and a list of recommended spare parts to be
14. Complete equipment lists with catalog data and other information to
demonstrate conformance with the Contract Documents and Specifications.
1.05 DELIVERY, STORAGE, AND HANDLING
A. As specified in Section 15050.
1.06 PROJECT CONDITIONS
A. Provide equipment suitable for project conditions specified in Section 15050.
B. All equipment furnished shall be located outdoors in a wastewater treatment plant
C. HRU shall be installed in a limited space as indicated on the Drawings.
D. Dimensions and orientation are indicated on the Contract Drawings. HRU
manufacturer shall design HRU package to fit within the space shown on the
Contract Drawings, oriented as indicated on the Contract Drawings.
1.07 SEQUENCING AND SCHEDULING
A. Coordinate with work restrictions specified in Section 01140.
A. As specified in Section 15050.
B. Manufacturer’s warranty shall be issued in the DISTRICT’s name.
A. Special Tools: Deliver 1 set of special tools needed to assemble and disassemble
the components of the HRU requiring regular maintenance.
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1.10 QUALITY ASSURANCE
A. Regulatory Requirements:
1. HRU design, fabrication, inspection, and testing shall be in accordance with
ASME B&PV Code, Section VIII, Division 1, (and be so stamped) and other
applicable sections of the B&PV Code.
2. The HRU shall be registered with the National Board of Boiler and Pressure
PART 2 PRODUCTS
A. One of the Following or Equal:
1. Cain Industries, Inc., Model HRSR.
A. All components and materials shall be suitable for use outdoors in a wastewater
B. Exterior Casing: 10-gauge Type 304 stainless steel.
C. Inner Wall: Type 304 stainless steel.
D. Tubes: Type 316 stainless steel.
E. Fins: Type 304 stainless steel.
F. Header: Type 316 stainless steel.
G. Bypass Damper: Type 316 stainless steel.
H. Bypass Damper Shaft: Type 316 stainless steel.
I. Other Components: Type 304 or 316 stainless steel.
A. Provide 1 HRU for Each Fuel Cell Power Plant:
1. Fuel cell power plant is Fuel Cell Energy, Inc. DFC300MA model.
B. Each HRU shall be designed based on the inlet and outlet conditions listed in the
Parameter Units Gas Side Water Side
Fluid - Air Water
Design Exhaust Flow Rate lb/h 3950 -
Design Water Flow Rate gpm - 30
Design Inlet Temperature deg F 700 140
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Parameter Units Gas Side Water Side
Design Outlet Temperature deg F 320 167.7
Design Gas Pressure in. w.c. 10 -
Design Water Pressure psig - 150
Hydrostatic Test Pressure psig - 225
Maximum Temperature deg F 1000 220
Maximum Allowable Backpressure in. w.c. 2.5 -
Maximum Water Pressure Drop psig - 2.5
Flange Connection Size in. 8 2
Minimum Heat Recovered MBTU/H - 402
A. Heat Recovery Silencer:
1. Counter flow heat transfer design with gas tight enclosure, liquid header
manifolds connected to single row finned tube assemblies.
2. One-inch diameter 0.065-inch thick tubes with 0.03-inch thick fins nickel
brazed to the tubes.
3. Liquid header manifolds shall contain 3/4-inch NPT connections for venting,
draining, and safety relief valves.
4. Provided with 3/4-inch ASME relief valve and 3/4-inch NPT vent.
5. Factory insulated with high temperature insulation.
6. Provided with hinged gas tight inspection doors providing complete access to
the entire heating surface for inspection, tube removal, and cleaning.
7. Vessel shall be designed such that no tube-to-tube, or tube-to-header joint
welds are in contact with the exhaust stream.
8. ASME and National Board stamped for Section VIII, Division I.
9. Provided complete with sound attenuation.
10. Provided with lifting lugs to facilitate unloading and handling of the HRU and
accessories at the jobsite.
11. Galvanized steel H-beam support base.
B. Full Port Exhaust Bypass Assembly:
1. Designed to bypass up to 99 percent of the exhaust flow at the maximum open
2. Attached to the top of the heat recovery silencer with horizontal inlet and
3. Provided with bypass damper and electric modulating actuator powered and
wired from the liquid temperature control assembly panel.
C. Liquid Temperature Control Assembly/Panel:
1. Provided with 4-20 mA output controller, thermocouple, thermocouple well and
wire, with all required appurtenances for modulating the full port exhaust
bypass assembly bypass damper.
2. Wired for 120-Volt/60-Hertz.
3. Electrical and instrumentation and control components shall be installed in
stainless steel NEMA 4X or NEMA 7 enclosures as required by the
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Specifications and the NEC based on the internal components and area
classification indicated on the Drawings or specified herein.
4. All electrical components and controls shall be factory wired and tested prior to
D. Equipment Pads, Anchorage and Support Requirements:
1. This paragraph specifies equipment anchorage and support requirements
applicable to work provided by the HRU supplier.
2. All HRU equipment and installations provided by the HRU manufacturer shall
reside on a 6-inch (minimum) equipment pad and be securely supported and
3. Anchorage: Anchors shall be Type 316 stainless steel. Fabricate and install in
accordance as indicated on the Drawings and Section 01612 and 05120.
E. Field Instrumentation:
1. All field instrumentation shall be in accordance with DIVISION 13.
A. Prepare surfaces and apply protective finishes as specified in Section 09960.
2.06 SOURCE QUALITY CONTROL
A. Witnessing: Source or factory testing shall be witnessed by the ENGINEER or
DISTRICT when indicated; provide advanced notice of source testing as specified in
B. Equipment Performance Test: Test Level 1; test as specified in Section 15958.
C. Factory Acceptance Testing of the HRU shall be performed before delivery to the
1. Functional Hydraulic and Electrical Testing of HRU components shall be
performed to demonstrate that actuators, instruments, dampers,
communication between vendor control panel and actuators work properly and
shall require only minor adjustments on site:
a. Hydrostatic Testing:
1) Prior to being enclosed in their casings, the heat recovery unit and
pressure retaining assemblies shall be hydrostatically tested with
potable water in accordance with ASME B&PV Code.
2) Minimum hydrostatic test duration shall be 1 hour. All components
shall be thoroughly drained and dried after completion of the
2. Any software shall be platform tested.
PART 3 EXECUTION
A. Install products in accordance with manufacturer’s instructions and as specified in
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3.02 FIELD QUALITY CONTROL
A. Witnessing: All field-testing shall be witnessed by the ENGINEER or DISTRICT
when indicated; provide advanced notice of source testing as specified in
B. Inspection and Checkout: As specified in Sections 15050 and 15958.
C. Equipment Performance Test: Test Level 1; test as specified in Section 15958.
D. Operational Testing: As specified in Section 01756.
E. Field performance testing shall be conducted and reported in accordance with
ASME Performance Test Code.
F. CONTRACTOR shall furnish and install all materials and any special equipment
required to accomplish the performance test.
3.03 MANUFACTURER’S FIELD SERVICES
A. Training: As specified in Section 01756.
END OF SECTION
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