Steam is one of the core elements of many industrial processes. From the textile industry, which uses steam for mangling, washing, drying, and ironing, to the food and beverage industry, where it is used for pasteurization or grain drying – steam is always there!
Without steam, many industrial processes would be significantly more complex and therefore more costly. The following applies: The better the steam generator is adapted to the respective operating conditions and production goals, the more the advantages of steam can be exploited in industrial production. But how do you find the right model for your company among the various steam boilers? Because this decision is not always easy, we at JUMAG present the three most prominent steam generator systems here:
- Shell boiler
- Forced-flow boiler
- Double-flow boiler
By carefully weighing all the advantages and disadvantages, we support you in choosing the right steam generator for your company.
The shell boiler
The shell boiler is one of the three most popular steam generator models in the industry. The most common is the flame-tube three-pass boiler, which consists of a single flame tube and two flue gas passes. Basically, every shell boiler has a cylindrical shell, which affects the steam quality.
Advantages of the Shell Boiler
1. Large Water Volume
As the name suggests, the shell boiler’s cylindrical design allows for a large water volume in the boiler and thus stable steam generation.
2. High Minute Load
The design of the flame-tube three-pass boiler, in particular, offers a high minute load. This means it operates efficiently even under rapid and significant load changes.
3. Dry Steam
Due to its specific design, the shell boiler produces dry steam, which is important in many industrial processes.
4. Very Robust
Another advantage of the shell boiler design: It is very robust and resistant to stress.
5. Very Durable
Thanks to its robust construction and high-quality materials, the shell boiler has a long service life.
Disadvantages of the Shell Boiler
1. Size and Weight
One disadvantage of the robust design is that the shell boiler is difficult to transport due to its size and weight and requires a lot of space during operation.
2. Costs
Also due to its size and enormous power, the purchase costs for the shell boiler are relatively high.
3. Long Heat-Up Time
Compared to other models, the boiler takes longer to reach operating temperature.
4. Boiler Room
The shell boiler may require a large boiler room. This can be a problem if space is limited.
5. Installation Criteria
The installation of a shell boiler is demanding and requires specific requirements that are not met in every facility.
6. Permits
Due to its size and specific design, permits are required for the shell boiler, resulting in recurring fixed costs.
7. Monitoring (Boiler Attendant)
Because of its high demands, the shell boiler requires continuous monitoring by a trained boiler attendant. This entails additional costs.
The shell boiler is extremely powerful, but its operation only makes economic sense under certain operational conditions. Therefore, its purchase should be carefully considered and only made after careful consideration of the operational conditions and the production target.
Forced flow boiler
The once-flow boiler is a water-tube boiler with a superheater. In this system, the flow of water and steam is forced by a piston feed pump.
Advantages of the Once-Flow Boiler
1. Small Space Requirement
The once-flow boiler requires relatively little space, which is particularly advantageous for operations with limited space.
2. Lightweight
Due to its design, the once-flow boiler is lightweight, which makes transport and installation easier.
3. Low Cost
The once-flow boiler is characterized by low acquisition and installation costs.
4. Fast Start-Up
The once-flow boiler system quickly reaches operating temperature, thus achieving rapid response times.
5. Adaptability (Standby)
The ability to place the once-flow boiler into standby mode makes it particularly energy efficient.
6. No Strict Installation Criteria
The installation of a once-flow boiler requires less stringent criteria.
7. Cascading Possible
The system can be cascaded to meet demand while achieving a wide control range. Depending on the load, only as many steam generators as are actually needed are activated. Additionally, the customer has redundancy and can at least partially produce steam should a steam generator fail or be repaired.
Disadvantages of the Once-Flow Boiler
1. Low Minute Load
For rapid power changes with high steam demand in a short period of time, the once-flow boiler is less efficient than other steam generation systems.
2. High Steam Humidity
The system tends to produce steam with higher humidity, which ultimately results in energy loss.
3. Wear (with piston pumps and during blowdown)
The piston pump is maintenance-intensive, and the blowdown effect can lead to increased wear (abrasion of the pipe wall).
4. Thin pipe wall thickness (rapid material wear)
The thin pipe wall thickness can lead to faster material wear.
5. Small diameter (rapid scaling)
The small diameter promotes faster scaling, which can impair efficiency.
The once-through boiler saves a lot of space and money, which is an important factor for many companies. However, it experiences faster wear and cannot handle the high minute load of a shell boiler.
Dwarf water chamber boiler
The small water chamber boiler combines the advantages of both its counterparts. Its design combines the size and weight savings of the once-through boiler with robustness and durability.
Advantages of the small water chamber boiler
1. Small footprint
Thanks to its compact design, the small water chamber boiler requires little space during operation.
2. Low weight
Its innovative design ensures a low weight, facilitating transport and installation.
3. Low costs
The small water chamber boiler combines the cost-effective features of both systems, thus enabling an economical solution.
4. Fast and gentle start-up behavior
The start-up process of the small water chamber boiler is not only very fast but also gentle, which minimizes wear.
5. Adaptability (Standby)
Due to its adaptability and efficient use in standby mode, the small water chamber boiler is particularly energy-efficient.
6. Hardly Strict Installation Criteria
The installation criteria are comparatively lenient, making it easier to adapt to different operating conditions.
7. Cascading Possible
The shell boiler system can be cascaded to flexibly meet demand.
8. Energy Efficient (Low Operating Costs)
With low operating costs (OpEx), the boiler also scores highly in terms of energy efficiency.
9. Robust
Like the shell boiler, the shell boiler is characterized by a robust design that ensures longevity and reliability.
Disadvantages of the Shell Boiler
1. Low Minute Load
Like the once-through boiler, the shell boiler has a lower minute load, which must be taken into account when faced with rapid load changes.
2. Boiler Over-Tearing Possible
Due to the possibility of boiler over-tearing, specific control mechanisms are required.
3. Only possible up to 13 bar
The miniature water chamber boiler is limited to operating pressures of up to 13 bar.
4. A pressure reducing valve is required for pressures above 7 bar.
Pressures above 7 bar require a pressure reducing valve, which can increase installation complexity.
Our conclusion: The dwarf water chamber boiler is the king among steam generators
The comparison shows: The small water chamber boiler impressively combines the advantages of its two counterparts, the shell boiler and the once-through boiler. Its economy, durability, and efficiency are particularly impressive and meet relevant purchasing criteria for many companies.
However, each company should individually consider which of the three models is the right one for them, taking into account its production conditions and production goals. We at JUMAG are happy to advise you on the various steam boilers used in industry. Simply contact us and we will help you find the perfect steam generator system for your specific application.
