In the late fall of 2020 Fitzemeyer and Tocci Associates, Inc, an MEP firm in Woburn, MA., contacted Frank I. Rounds Co. to meet at a Massachusetts hospital to evaluate options for its existing boilers.
The 500-horsepower Cleaver-Brooks boilers were still in serviceable shape, however, the hospital was interested in a long-term, sustainable solution. The boilers provided steam to the hospital for heating, sterilization, domestic hot water, and various other process loads. The longevity demonstrated with their existing boilers was the main driver for the facility to request replacement equipment from the same manufacturer, Cleaver-Brooks.
During the site walk-through and records review with the engineers, several design proposals were considered but the general overall approach was to improve the efficiency and reduce the emissions at the most reasonable cost.
The Solution
(2) two Cleaver-Brooks 600 horsepower CBEX boilers with Hawk 4000 control including the following features that contribute to the optimal operating efficiency of the boiler and burner:
- VFD (variable frequency drive) on the combustion blower to adjust as needed for the system demands
- Oxygen trim system that automatically adjusts the fuel-to-air ratio of the flame by correcting excess air
- Parallel positioning that maintains the optimal fuel-to-air ratio of the burner flame
The original boiler’s burner was operating at about 5 – 6 % O2 across the firing range, while the new burners are expected to achieve 3% O2. The oxygen trimming translates to improved efficiency and reduced fuel usage, which reduces the overall carbon footprint.
The modulating stack damper we installed is designed to help maintain draft control, while minimizing heat loss from the boilers.
Advanced Controls
A Hawk Master Panel was also provided to Lead / Lag the new boilers, along with the existing 300 HP boiler that remained.
The Master Panel also incorporated the control and communications to the new Deaerator, which also provides direct control and communications with the Building Management System.
In addition to the new boilers and controls, a 45,000 lbs./hr., a Spraymaster Deaerator equipped with an Advanced Deaerator Control (ADAC) was installed. The ADAC is a PLC-based deaerator control system designed to monitor and optimize the delivery of feedwater to the boiler.
The steam capacity of the facility is above 30,000 lb/hr. currently, with the Boilers and Deaerator designed for expansion.
Plans and Specifications were generated by the Engineer and sent out to Contractors to bid a turnkey price for the removal of the old boilers, and installation of the new boilers and deaerator.
Walsh Brothers, a General Contractor from Boston, and Lake HVAC a Mechanical Contractor from Stoneham, were selected as the bid winner and successfully completed the contract.
As a team, engineers, suppliers, and contractors came together to outfit this boiler plant with the latest technology to operate as efficiently as possible with the fewer carbon emissions possible. Contact Frank I. Rounds for your next boiler plant evaluation or project.