A large industrial boiler can operate successfully for 25 years or more. However, the decrease in a boiler's performance and associated gradual increase in annual maintenance and operating costs can signal a need for change. When required, the boiler-replacement process typically is not as simple as merely changing out a failing boiler. So what happens when a boiler reaches the end of its useful life? Where does the process of replacing an old boiler begin? Simply put, boiler replacement takes much more effort than pulling out an old boiler and sliding in a new one.

The replacement of a large industrial boiler easily can involve $1 million or more, so it only makes sense to put thought into boiler-related decisions, minimizing costs while maximizing benefits. This article will present several tips on how to approach industrial-boiler replacement. The tips will highlight several key factors that should be considered before an actual in-depth engineering design commences. A typical industrial boiler that produces 30,000 lb per hour of 150-psig saturated steam will be used in this article as a basis for discussion.

Plan Ahead

A large industrial boiler can take 20 to 40 weeks from order placement through drawing submittals and final approvals to arrive at a job site. It is essential to develop a preliminary project schedule at the start of a boiler-replacement project. The schedule should set a desired target for boiler operation and work backward to a drop-dead order-placement date. No project, especially one involving a boiler replacement, runs as smoothly as desired, so the schedule must include some “float time” to ensure the desired startup date is obtainable. While many scheduled tasks can occur in conjunction, some cannot. Therefore, it is important that a professional with knowledge of the overall procedures be involved in the scheduling process.

A boiler needs to be specified, priced, and purchased before emission data can be obtained for the completion of the environmental-permit process and the arrival of certified drawings, which allow for the start of a detailed design. While tending to this process, it may be possible to start other tasks, such as preparing the site before the actual design has been completed. Care must be taken not to impede the continued operation of the original boiler until the schedule allows it to be removed from service.

Plan the Space

The placement of a new boiler often is assumed to be a simple decision that continuously is postponed and finally addressed during the design stage. Unfortunately, this can cause problems later. However, only two basic placement choices are available: Situate the new boiler in the same spot as the old one, or find used space nearby. There are advantages and disadvantages with each possibility.

If a new boiler is slated to be placed in an old boiler's spot, a couple of items must be addressed. First, a facility's operating schedule must be studied to determine whether the old boiler can be removed and the new boiler installed without the facility's normal operation being disturbed. Assuming the required equipment and personnel are ready and available, an aggressive, well-coordinated schedule could demand four months for a completed change-out. Summer typically is reserved for this type of change-out, which a schedule must take into consideration.

If a new boiler must be placed in an old boiler's spot and a facility's operating schedule does not allow sufficient time to execute the change-out, a rental boiler can be moved into a temporary space and operated during the demolition and construction process. This option has the advantage of allowing the complete construction schedule to occur at any time for as long as required without operation disruptions. However, the cost of a rental boiler could add tens of thousands of dollars per month to overall project costs and many more thousands of dollars in connection costs.

The major advantage of placing a new boiler in an old boiler's spot is that most of the supporting utilities (steam and water piping, electric power, control wiring, etc.) already will be in the right area. If the schedule is unaccommodating or the cost of a rental boiler is prohibitive, a new boiler will have to be located in a space not already occupied by a piece of critical equipment. The advantages are that the work schedule allows for more flexibility of available time, probably does not require a summer time slot, and does not endanger a facility's continued operation. The major disadvantages are that the new boiler may not be adjacent to other boilers and, thus, may be considerably more difficult for an operator to see and access, and thousands of dollars will be spent connecting the new boiler to the existing water, steam, fuel, and electric systems in the boiler room.