WET & DRY BOILER STORAGE METHODS:

In this blog we will examine proper procedure for short and long-term boiler storage. Certain boiler owners that don’t use their boilers for steam or hot water processing perform storage techniques each year, in effort to keep those boilers not required for process or comfort heat from corrosion. Though not inclusive, the storage process can greatly eliminate missteps that can lead to costly repairs after boilers are shut down for the season. 

Best Practice: There are two (2) basic methods of laying up a boiler for extended periods of time; wet and dry storage.

Short Term Storage: Though Wet or Dry is acceptable, wet storage may be beneficial due to lower overall water loss along with time & material (chemicals & absorption media) savings. 

Long Term Storage: Dry storage is the best method. This avoids the normally wetted steel surfaces from experiencing advanced corrosion. See details that follow.

 

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Wet Storage

1) If the unit is to be stored for no longer than a month and emergency service is required, wet storage is satisfactory. Wet storage is not generally employed for boilers that may be subjected to freezing temperatures. Several alternative methods may be employed.

• The boiler to be stored should be closed and filled to the top with chemically treated feedwater or condensate, to minimize corrosion during standby storage.
• Water pressure greater than atmospheric pressure should be maintained within the boiler during the storage period.
• A tank may be connected to the highest vent of the boiler to maintain statis head pressure above that of atmospheric pressure.
• For short periods of wet storage, the water or condensate in the boiler should contain approximately 450 PPM of caustic soda and 200 PPM of sodium sulfite. Similar products may be used as recommended by your water chemist.
• If the boiler is equipped with a superheater of the drainable type, it can also be filled with the above, described treated water by overflowing from the boiler vessel.
• If the superheater is non-drainable, it should be filled with condensate or demineralized water containing no more than 1 PPM of dissolved solids. Before introducing the water into the superheater, sufficient hydrazine should be added to achieve a concentration of about 200 PPM.
• Sufficient volatile alkali should also be added to produce a pH of 10. The treated water may be introduced into the superheater through an outlet header drain until the water flows into the boiler. When the superheater is filled, close the vents and drains. This quality of water may also be used in the boiler.
• If the storage period should extend beyond a month, the concentration of hydrazine 1should be doubled.

2) As an alternative, the boiler may be stored with water at normal operating level in the drum and nitrogen maintained at greater than atmospheric pressure in all vapor spaces.

• To prevent in-leakage of air, it is necessary to supply nitrogen at the vents before the boiler pressure falls to zero as the boiler is coming off the line.
• If boiler pressure falls to zero, the boiler should be fired to re-establish pressure and drums and superheaters thoroughly vented to remove air before nitrogen is admitted.
• All partly filled steam WET STORAGE drums and superheater headers should be connected in parallel to the nitrogen supply.
• If nitrogen is supplied only to the steam drum, nitrogen pressure should be greater than the hydrostatic head of the longest vertical column of condensate that could be produced in the superheater, or a minimum of 5 psi. 3.
• Rather than maintain the water in the boiler at normal operating level with a nitrogen cap, it is sometimes preferred to drain the boiler completely, applying nitrogen continuously during the draining operation and maintaining a pressure of nitrogen greater than atmospheric throughout the draining and subsequent storage.

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Dry Storage

Dry storage is preferable for boilers out of service for extended periods of time or in locations where freezing temperatures may be expected during standby.

• The cleaned boiler should be thoroughly dried, since any moisture left on the metal surface would cause corrosion.
• After drying, precautions should be taken to preclude entry of moisture in any form from steam lines, feed lines, or air.
• A moisture absorbing material should be used, such as quicklime, at the rate of two (2) pounds, silica gel or Drierite at the rate of five (5) pounds for 30 cubic feet of boiler volume. It may be placed on desiccant trays inside the drums or inside the shell to absorb moisture from the air.
• The manholes should then be closed and all connections on the boiler should be tightly blanked.

The effectiveness of the materials for such purposes and the need for their renewal should be determined through regular internal boiler inspections.

We would strongly recommend that large signs be placed in conspicuous places around the boiler to indicate the presence of moisture absorbing materials. The message to be conveyed can be as follows: Note: Moisture absorbing material has been placed in both the fireside and waterside of this boiler. These materials must be removed before any water is introduced into the boiler and before the boiler is fired.

For long periods of storage, internal inspections should be performed to assess the condition of the moisture absorbing materials. Such inspections should be initiated monthly, unless experience dictates otherwise. The moisture absorbing material increases in volume as moisture is absorbed, making it necessary to use deep pans. Fresh material should be substituted as needed at the time of the inspection. Alternatively, air dried externally to the boiler may be circulated through it. The distribution should be carefully checked to be sure the air flows over all areas.

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Other Protections:

Boilers stored in other than a dry, warm protected atmosphere, should have exterior component protection. Also, common vented boiler consideration included below.

• Burner components that are subject to rust, such as jackshaft, linkage, valve stems, moving parts, etc., should be lightly coated with a rust inhibitor and covered to protect them from moisture and condensation.
• Electrical equipment, electronic controls, relays, switches, etc., should be similarly protected.
• Pneumatic controls, regulators, diaphragm or piston operated equipment should be drained or unloaded and protected so that moisture, condensation, rust, etc. will not damage the equipment during a long period of storage.
• Feedwater lines, as well as blowdown, soot-blower (if equipped), drain lines, etc., should all be drained and dried out.
• Valve stems, solenoid valves and diaphragms should all be protected by lubricant, rust inhibitors, plastic coverings or sealants.
• Where boilers are “common vented” and only one boiler will be stored, be sure to seal or block-off & VISUALLY TAG vent opening at the flue gas outlet to eliminate possible moisture and potential flue gas entry from the fireside via down or backdraft. Monoxide detection alarm in boiler room recommended.

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Consult your boiler water treatment professional if further guidance is required.

Customer Service:

Our Service Team is ready to assist in preparing to store your boiler or bringing your boiler out of storage in preparation for the upcoming heating season. This includes, cleaning, replacing filters, re-gasketing, filling, closing and firing your boiler(s).  Additionally, we can perform your CSD-1 testing and reporting along with combustion checks and/or setting and offer recommendations which can help you save on annual fuel costs. Visual inspection and function testing of critical components to reduce emergency and demand maintenance costs are also done at this time.

Contact one of our team professionals to obtain pricing or schedule your service visit.

CALL (248) 589-8220 – Service: Brian Frank at EXT. 116   or   Lou Willoughby at EXT. 123

                                    Scheduling: Debra Smalstig at EXT. 117  or  Brian Frank at EXT. 116

 

Storage basics Courtesy of Cleaver-Brooks w/supplemental commentary by:

M. Conley / D. J. Conley Associates Inc. 1974 – present.

 

In this blog we cover general steps when faced with the decision to replace older outdated burners vs. a complete boiler replacement.

Whether your consideration to replace comes from a poorly functioning burner, the drive to become more environmentally friendly, improve performance & reliability, increase efficiency or a combination of factors, the following will provide guidance to help achieve your goals.

1. Verify your boiler’s condition and expected longevity.

• • Perform internal fireside and waterside inspection to ensure vessel integrity and insulating materials are in good condition and repair/ replace components, as necessary.
  • Consider boiler life expectancy and costs associated with reaching boiler end date with respect to other ancillaries that may need replacement.
  • Upon review of results, determine if proceeding to step 2 is viable.

2. Employ a reputable burner supplier & installer to establish the budget.

• • Determine if your burner project will require an “air permit” through Michigan DEQ/EGLE, (Department of Environment, Great Lakes & Energy), AQD (Air Quality Division).
  • Select burner type to match goals. Fuel type, standard or low NOx, Single-Point- Linkage vs. Parallel Position, Linkage-less, Burner firing rate control. (See illustrations below)
  • Select emission level required or expected. Generally, in SE Lower Michigan under Boiler MACT, below 10 MMBTU/Hr. burning natural gas will expect new burners to be 30 PPM NOx or less emission level.
  • Determine if emission level be achieved will be via FGR (flue gas recirculation) or by internal burner design w/o FGR. Installed cost & blower horsepower (operating costs) normally affect this decision.
  • Establish burner turndown required. Most conventional replacement burners today depending upon capacity and fuel burned, will deliver anywhere from 5 to 10:1 turndown. Verify offering with customer expectation with all associated fuel(s) to be used.
  • Consider VFD (variable frequency drive) as part of control strategy for better combustion control and electrical energy savings. Weigh added cost vs. potential payback. VFD does not make sense for all size & type projects. Payback using VFD on small burner/boiler used for comfort heat only may not make sense.
  • Combustion and Firing rate controls: Consider overall control strategy to compliment chosen burner using technology that best fits your plant’s operation and budget. Discuss & decide flame safeguard & scanner type, load demand and duty cycle with firing rate control from main or “master” panel (multiple boilers/burners), diagnostics, connectivity to remote device, phone app or BMS, alarm options, implementation of oxygen trim system, reporting and recording options via SCADA, PC, HMI screen size (if required) & boiler level control upgrades.

*   See “prométha” connected solutions below for example.

• • Confirm boiler/burner “altitude” at installed location. Elevations above 2000 ft. ASL warrant review by an application engineer to confirm fan size or necessity to de-rate burner output affecting rated performance.
  • Consider new burner’s sound pressure levels (dbA at “X” Hz) at all firing rates to verify acceptability.
  • Provide engineering documentation to confirm burner fit and operation with existing boiler’s flange mount, combustion chamber and gas passage area, through stack, breeching, economizer, or other pressure drops to outlet. No excessive back pressure or adverse combustion conditions should arise with normal burner operation at rated capacities. Larger and Industrial boiler/burners with stringent NOx requirements and/or larger furnace areas may require computational fluid dynamic (CFD) analysis to best match new burner with boiler.
  • Burner supplier should provide an “engineered” stack loss calculation for proper verification of expected and acceptable draft conditions.

 3. Review budgetary or firm proposed price.

• • Determine if ROI fits within boiler’s expected life.
  • Consider potential for unforeseen repairs or modifications.
  • Secure funding.   

4. Proceed with investigation of required details.

• • Confirm fuel(s) to be used.
  • Verify fuel delivery system’s integrity including piping, fuel regulation, isolation valves, vents, strainers etc., are operable and up to current code requirements. Repair/replace, as necessary.
  • Confirm gas pressure required at the inlet to the burner and at inlet to fuel train is available and deliverable to fuel train inlet with existing transmission piping.
  • Required electrical service is available and costs include any service upgrades needed to implement new burner electrical feed, low and high voltage along with any required BMS interface, connecting testing and upgrades to existing systems.
  • Consider if UPS/Surge suppressor will be expected or required. Strongly suggest using UPS/Surge suppressor if using PLC type controls.
  • If using IP protocols, verify via coordinated effort with installer, controls contractor and owner for clean integration between new and existing control connections.
  • If using a stand-alone internet connection for remote boiler/burner monitoring, such as “prométha” shown below; confirm all hardware such as modems, power supply, software, mounting, wiring and set-up are included.
  • Confirm installer has included costs for mechanical/electrical and other permits as required.
  • Obtain formal quotation with firm or “not-to-exceed” pricing and agree on T’s & C’s along with labor & material warranty terms.
  • Verify lead times and project completion expectations.
  • Receive copy of all documentation, including but not limited to, permit application(s), Insurance, and installer’s License.

5. Once formal purchase order has been given and prior to release for production:

• • Receive and review submittal information with project team confirming fit, layout, coordination, and sequence of installation.
  • Confirm fuel train layout & inlet location is acceptable and make final changes if needed.
  • Determine drop-ship location, equipment receipt process and materials protection prior to installation.
  • Review all owner safety requirements and provisions, house-keeping measures and site logistics with team and perform sign-off process.

6. Project Completion:

• • Review entire installation for proper completion, including wiring continuity checks, burner and controls mounting, fuel delivery system leak testing and all other (FGR) piping, gaskets, and seals as necessary.
  • Test, check & start new burner, combustion and firing rate controls and other new products as part of project.
  • Submit written documentation of all test procedures, combustion reports and CSD-1 test reports as required.,
  • Call local jurisdiction for inspection. Note: certain jurisdictions may require inspection prior to startup. Verify first.
  • Perform “witness testing” with owner and obtain sign off.
  • Perform operator training, review O & M manuals and review maintenance procedures with owner/operator.
  • Review spare parts (if needed) and purchase points.
  • Sign off project completion documentation “as-built” drawings and close out project.Note: The above will vary with project, however, should provide a general process for your BURNER REPLACEMENT consideration.

 

See Illustrations to assist in understanding basic options:A Typical Standard burner single point positioning / jackshaft control

Typical Burner with Parallel Position Controls

LOW NOx Burner / NO FGR Required with Parallel Position Controls

      

“prométha” Connected Boiler Solutions:

• • Load Management
  • Boiler/Burner Diagnostics
  • Deaerator–Surge Tank Feedwater System Management

 

A variety of reliable connected solutions are available for your consideration.

Please contact our sales team below.

 D.J. Conley has supplied quality Cleaver-Brooks ProFire®/ Industrial Combustion retro-fit burners to the SE Michigan boiler market for nearly 50 years. Our commitment to quality assures your satisfaction. We regularly partner with our contracting community to provide turn-key installations. Give us a call to assist in your next burner project or for a free evaluation of your current boiler/burner system!

Contact us at (248) 589-8220 and ask for Aftermarket Sales or email:  aftermarket@djconley.com

For more information, go to  www.djconley.com   click on “Products”, then scroll to “Boiler Burners”.

Author: M. Conley / D. J. Conley Associates Inc. 1974 – present.

Information in this blog is being furnished by D. J. Conley Associates Inc. and by those having numerous years of experience in design, installation, and application with generation of heating and process steam and hot water products and services. This information along with supplemental data obtained from a variety of sources is for the beneficial use of its audience only. We cannot be held liable for the application or misapplication of products or methods associated with this data which may cause unfavorable issues or harmful outcomes since there are many circumstances beyond our control at play in every individual system. You are welcome to contact us in the event questions should arise.