Steam Jackets in Boilers | Definition, Types, and Applications

What are Steam Jackets?

Steam jackets are designed in various ways to accomplish particular processing requirements. In other words, steam jackets act as a secondary enclosure over a boiler shell. A steam jacket consisting of an outer cylinder surrounding the vessel is the most commonly used jacketed vessel. The steam circulates on the outer jacket and condenses on the wall. Jacketed vessels contain an internal space or cavity usually filled with circulating fluid that is ideal for heating and cooling monitoring and to ensure minimal condensation on the outer jacket wall as well as the transfer of heat in the vessel.

For jacketed heating purposes, operating temperature is required to be up to 350°F. The steam and hot water generally serve as heat transfer forms. The advantages of using steam jackets are as follows,

• The jacket temperature is controlled efficiently with hot water. It helps in preventing damage or loss to the product due to overheating.
• Hot water enables the enhanced quality of the product
• Hot water distributes heat more uniformly compared to steam. It destroys hot spots that lead to products baking on the walls of the vessel.
• With glass-lined reactors, steam can shock and damage the lining. On the other hand, hot water facilitates hassle-free transitions from heating to cooling.
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Steam jackets are excellent for heat transfer, easy to control, and efficient to maintain the high quality of the product processed. The heat transfer area or the vessel wall surface area is calculated by using the following formula,

Q = U x A x ?Tm

Although steam jackets are ideal for transferring heat, many process managers opt for hot water instead of steam to heat the jacketed vessels. The vessel walls are designed of stainless steel or glass-lined carbon steel, and the glass lining acts as an additional resistant layer for corrosion. The steam jacket space depends on the vessel size. But usually, its width ranges between 50mm and 300 mm.

Types of Steam Jackets:

There are three major types of steam jackets found,

Conventional steam jackets:

Conventional steam jackets provide excess coverage for the entire or part of the vessel. It is best suited for high-pressure applications by providing excellent insulation benefits and creating both inner and outer vessel walls. These jackets are available in baffled and unbaffled styles, along with agitating nozzles that aids in improving turbulence and overall efficiency in the absence of baffles.

Dimple steam jackets:

Dimple vessel jacket utilizes a light-gauge metal jacket adjoined to the main vessel through spots or plug welds. Such a system provides strength and durability with minimal excess weight or expense.

Half-pipe coil steam jacket:

Half-pipe coil vessel jackets are ideal for high-temperature processing operations in industries. These jackets are best suited for heat transfer and thermic fluid heating systems and are divided into multi-pass zones for maximum flexibility.

Heat transfer can greatly differ from one design to the other as well as from one processing application to the other. Usually, conventional steam jackets require more shell thickness to balance the stress of heat expansion, especially if the jacket and shell are manufactured from different materials. Dimpled steam jackets and half-pipe coil steam jackets are highly preferred for the thermic fluid heating system.

Applications of Steam Jackets:

The closed-loop heating system of the steam jacket fulfills the requirement of heating and cooling for a single process operation in industries. Vessels and equipment that require frequent cleanings also benefit from the jacketed vessel as it spares the equipment from internal coils for heating or cooling. Some of the industries that benefit from the ease and reliability of steam jackets are as follows:

• Chemicals
• Petrochemicals
• Food
• Milk and Diary
• Distilleries and Breweries

Conclusion:

Rakhoh Boilers are trusted steam boiler manufacturers in Pune for 38+ years, delivering efficient and reliable industrial boilers, waste heat recovery systems, thermic fluid heaters, and boiler accessories in over 26 countries worldwide. We provide excellent boiler services such as steam trap assessment, boiler automation, energy audit, annual maintenance contract, etc., to boost the efficiency and the productivity of the steam boilers.

Explore more about our products and services on www.rakhoh.com