Boiler Blog Archive | Nationwide Boiler Inc.

In our last blog, we reviewed the three common types of watertube boilers: D-Type, O-Type, and A-Type. There is, however, another package watertube boiler on the market today; the Ds-type, providing a fourth option to consider when you are planning for a new boiler. In fact, the Ds-type design is patented and manufactured by Superior Boiler and is one of their most popular watertube boiler models. 

The configuration for this type of boiler is similar to the D-Type, with one upper steam drum, one lower drum, and one convection bank. One of the main differences lies in the convection bank flow area (the bank of tubes that provide convection heat transfer), which is much larger and utilizes upside-down L shaped tubes. This larger area means a reduced boiler pressure drop on the flue gas side. A smaller fan is required, reducing both cost and energy usage.

With Ds-type boilers, the furnace is more centralized and the cross section is more square compared to the rectangular furnace cross section of a D-type boiler. The square shape improves the heat flux from the burner due to walls being more equidistant from the heat source, and with a more uniform heat flux we get improved heat transfer with lower emissions.

Compared to D-type boilers, the Ds-type offers additional features and advantages: 

- Improved shipping and rigging due to a more centralized center of gravity.
- More compact footprint; roughly 1-2ft shorter than typical package boiler. 
- No need for a burner platform since the burner is lower to the ground. 
- The option to be designed with a top exhaust outlet, providing space savings with the ability to mount the economizer in a vertical configuration above the boiler. D-type boilers are limited to a side outlet and horizontal, ground-mounted configuration. 
- An overall lower capital cost caused by fewer transitions and breeching, smaller fan requirement, better heat transfer, and better performance.

In the boiler industry, there are three main types of watertube boilers: D-type, O-type, and A-type (see the graphic). Boilers can be designed for either saturated or superheated steam, and they can be packaged or field-erected. Package watertube boilers are designed to be small enough for highway transportation and are factory assembled. Field-erected boilers are just as they sound; multiple components are assembled and installed in the field.

For each boiler type, there are differences in superheater design and performance. Before diving into those differences, let’s review each of the main types of watertube boilers. 

D-type boilers have one steam drum and one lower drum, centered over each other with the furnace offset to one side. These boilers are designed with only one generating bank. 

O-type boilers also have one steam drum and one lower drum, however, they are centered over each other with the furnace in the center. These boilers are designed with two generating banks (i.e. the flue gas flow splits into the two sides at the end of the furnace). 

A-type boilers are similar to O-type and include two generating banks. The major difference is the number of drums and placement. A-type boilers include one steam drum at the top center, and two lower drums; one placed on each side of the furnace.

Nationwide Boiler's first Steamlines Newsletter of 2021 is out and available for viewing! Read up on the latest happenings at Nationwide, industry news, technical tips, and more, including... 

A SOLUTION TO STEAM SUPPLIER OUTAGES
Nationwide has nearly 55 years of experience responding to emergency needs, and there is no doubt that we are able and ready to dispatch equipment in a moments notice. What may come as a surprise to some is that unplanned and emergency rentals make up a smaller portion of our business than planned outages. And at times, rental boilers are used for process steam when the outage is planned by the steam supplier next door.

REMOTE WORK: IS IT THE FUTURE?
Since the pandemic forced many companies (including NBI) to move to a temporary remote work model, some corporations like Google, Dropbox, Facebook, and Salesforce are going all in with remote work as a permanent way of business. But is remote work for everyone, and is it the future? Hear from our President & CEO, Larry Day, for his take on the matter.

GETTING TO KNOW OUR STORAGE YARDS
Nationwide Boiler has a purpose built rental fleet featuring firetube and watertube boilers, mobile steam plants, and boiler auxiliary equipment. Partnering with multiple distinguished companies in our industry for the storage & maintenance of this equipment allows us to offer a quick and cost effective solution when a temporary steam need arises.

CALIFORNIA EMISSION RULE UPDATES
More changes are upon us here in California, and at Nationwide Boiler we make it a priority to stay abreast of AQMD emission rulings that will affect our customer base. The three areas of focus at this point are the South Coast AQMD, San Joaquin Valley APCD, and San Diego APCD.

Do you work with boilers? The American Boiler Manufacturer's Association (ABMA) recently published a Boiler Installation Guide that addresses common issues impacting the safety and performance of boilers. This handy guide references eight major areas with strict codes and requirements that must be followed for proper design and installation. These areas include:

 -  Combustion Air Supply
 -  Stacks and Ductwork
 -  Draft Controls
 -  Gas Train Design
 -  Combustion Tuning
 -  Safety Controls
 -  Piping and Valves
 -  Outdoor Installations

Check out the complete guide to prepare for your next boiler design and installation project. And don't forget to call Nationwide Boiler for your next temporary rental boiler project or new and used boiler needs.