Low Pressure Low-Down

Historically, steam has been a powerful resource for space heating in homes and commercial buildings. Steam has proven extremely effective at providing controlled, consistent heat to distribute throughout a building without the need for pumps by simply using a durable steam boiler. In fact, the heating effectiveness of steam still makes it a staple heat source after more than a century.

Over the past 50 years, however, the use of steam for providing regular comfort (space) heating has declined, as many businesses employ newer technologies. Yet, specific industries and applications such as breweries, distilleries, dairy production and scientific laboratories are all increasing the demand for steam heating and enjoying a myriad of benefits as a result.

Why steam heating?

Many businesses require precise levels of heat to achieve a desired outcome. For example, in food production industries, it is tremendously important for all production to maintain consistent quality. This can be difficult to achieve with some other heating technologies, such as direct fired heating. Direct fired heating requires management of extremely high temperatures that can fluctuate and scorch products to yield varying results.

蒸汽加热,另一方面,生成same large heat loads, but in a more controlled form, creating greater consistency and resulting in higher product quality. Steam heating is available from high- and low-pressure steam boilers, allowing businesses to match equipment to their unique needs. Many industries that may have traditionally opted for high-pressure steam are now realizing the benefits they can achieve with low-pressure steam applications.

Rising use of low pressure steam

The operating pressure of steam boilers should match the temperatures required for each specific application — such as pasteurizing beer or yogurt. It is a common misconception, however, that low-pressure steam boilers are not suited for process heating. In fact, many businesses running high-pressure steam boilers could likely satisfy heating needs with low-pressure steam boilers and achieve the same results, while saving on both equipment purchases and operating costs.

Low-pressure steam is limited to 15 PSI. High-pressure steam applications require more than 15 PSI. However, with high-pressure steam, complex and costly regulations set in. Owning and operating high-pressure steam systems may require staff to undergo specific training and certification, and require that staff be present 24 hours per day. Businesses must purchase additional, specialized insurance coverage specific to high-pressure steam. Therefore, opting for low-pressure steam when it satisfies the process requirements reduces regulatory burden, increases staffing flexibility and reduces overall insurance costs.

In addition, high-pressure steam systems can be more expensive to purchase, install and repair. High-pressure steam systems often call for expensive, specialized welding during assembly or repairs, adding to cost of ownership.

While many steam heat applications can easily be accomplished with either low or high-pressure systems, some processes are better suited for high-pressure technology. For example, high-pressure steam is ideal for extremely large facilities with high heat demands, such as hospitals with sterilization and in autoclave requirements. These applications need much higher pressure — 60 PSI and above.

Modern day low-pressure steam applications

There are many growing industry applications in the U.S. that embrace low-pressure steam heat for its cost-efficiency and versatility.

Food and beverage

Pasteurization, in particular, requires products to be heated to very specific temperatures to eliminate certain harmful pathogens, without overheating and impacting taste.

An increasing number of small craft brewers, micro-pubs, and micro-distilleries are enjoying the low costs associated with low-pressure steam heat while achieving consistent batches and reducing waste. In addition, food and beverage industries, such as dairy production, can use their steam boilers to create hot water through a steam-to-water heat exchanger for cleaning and other sanitizing needs.

Laboratories

Another unique application of low-pressure steam heat is demonstrated in scientific laboratory buildings. Labs on college campuses use a tremendous amount of exhaust air when conducting experiments and tests. To make up for the large amount of exhaust air, the laboratories bring in an equal amount of outside air, which can be extremely cold in the winter, and require a significant amount of heat to warm up to neutral conditions. When the air is below freezing point, other forms of heating the building — such as hot water coils — may be more susceptible to freezing and damage. Low-pressure steam, however, is much less vulnerable to this risk and provides large heat capacities.

Lumber kilns

Low-pressure steam heat also is proving very useful in kiln drying of specialty lumber. Mills often house a variety of specialty hardwoods used for making furniture, or cedar planks used for cooking, that require drying in a kiln. Using a low-pressure steam boiler enables mills to perform this function safely and effectively for standardized results, increasing the quality of the wood. The manageability and consistency of low-pressure steam heat make it ideal for these and other growing industries.

食品和饮料行业,如啤酒distilleries and dairy production, adopt low-pressure steam heat systems at an increasing rate, other sectors are just starting to familiarize themselves with the application opportunities and benefits of the technology. Chemicals or cosmetics manufacturers, for example, are discovering they can swap a high-pressure system for a low-pressure steam application to obtain the same results at a reduced installed cost as well as lower operating costs.

Factors to consider

When selecting a low-pressure steam boiler, buyers should take inventory of their business’ needs and facility amenities before making a selection. Most low-pressure steam boiler systems are highly configurable to match the unique needs of different applications. Furthermore, many low-pressure boiler systems can be built into existing systems or designed for new installations — ensuring consistency and efficiency for each individual application.

Further underscoring their versatility, low-pressure commercial steam boilers come in a variety of sizes and run on several different fuel sources. High-quality options can operate on natural gas, propane, oil or a dual fuel option, while ranging in size from 48 pounds/hour to 8,800 pounds/hour in a single boiler.

When evaluating boiler options, determine what is required for optimal production first, and then build a system to match to avoid unnecessary costs. For businesses with limited demands, there are simple atmospheric burners available at low costs. For higher-demand operations, power burner models allow for greater capacity and flexibility.

Controls for the burners also are customizable to enable varying levels of precision in temperature regulation throughout the system. Burner control ranges from:

• Good: Simple on/off functionality

• Better: Low/high/low offers low-stage to more closely match lighter loads and reduce energy consumption

• Best: Full modulation offers precision heating and variable controls

Businesses with complex heating requirements may opt for a multiple boiler control system to run larger operations more efficiently.

Finally, businesses should choose a low-pressure steam boiler after consultation with a professional in the industry with expert knowledge on specifying the best boiler to meet steam system operational needs. An industry expert can explain the different steam piping designs available to ensure the product fits the application seamlessly and achieves optimal performance.

Dave Burggren is director of Commercial Sales for Weil-McLain, a North American designer and manufacturer of hydronic comfort heating systems for residential, commercial and institutional buildings. Founded in 1881, Weil-McLain is based in Burr Ridge, Illinois., with manufacturing facilities in Michigan City, Indiana. and Eden, North Carolina, and regional sales offices throughout the U.S. and Canada.