Industrial boilers are essential in many industries, providing the necessary heat and steam for production process. This guide aims to help you choose the right industrial boiler by addressing key considerations and common questions.

1. Analyzing Business Needs: Understanding Steam and Hot Water Demand

Before selecting an industrial boiler, it is essential to understand the business's actual needs, including the supply quantity and parameters of steam and hot water.

  • Assessing Total Load Requirement: Understand the steam and hot water needs for production processes or heating. For example, if a factory requires 10 tons of steam daily, the total load range should be set at 10 tons/day.

  • Identifying Peak Demand:Determine the duration and frequency of peak demand periods. For instance, peak demand may occur from 8 to 10 a.m., during which steam consumption might reach 15 tons/day.

  • Ensuring Economic Efficiency: The boiler should operate at or above 75% of its rated capacity to maintain efficient and cost-effective performance.

  • Planning for Redundancy: Consider the need for backup capacity to cover boiler outages. It is generally recommended to have a backup boiler to ensure uninterrupted production or heating.

2. Determining Steam and Hot Water Parameters

After understanding the demand for steam and hot water, specific parameters need to be determined to select the appropriate boiler.

  • Saturated Steam Parameters: Industries such as textile dyeing, food processing, rubber manufacturing, and petrochemicals need to determine the saturated steam parameters according to production process requirements to maintain consistent temperatures. For example, the textile dyeing industry requires constant high-temperature steam for dyeing and setting, necessitating a boiler that can stably provide saturated steam at specific pressures and temperatures.

  • Pressure and Temperature: Generally, the boiler pressure should be higher than the required saturated steam pressure to compensate for pressure losses in pipelines or networks. For instance, if production requires a steam pressure of 1.5MPa but there might be a pressure drop of 0.2MPa during transmission, the boiler should provide at least 1.8MPa. Adding a 25-30% pressure margin, the boiler should be designed to provide approximately 2.25MPa to ensure stable and safe system operation.

3. Steam Boilers vs. Hot Water Boilers: Which is Right for Your Needs?

Hot water heating is more energy-efficient and comfortable than steam, but many factories still need steam for heating in production processes. Choose based on the following scenarios:

  • If you need a large amount of steam but a small amount of hot water, use a steam boiler with a heat exchanger to produce hot water.

  • If you need a large amount of hot water and a small amount of high-pressure steam, use a hot water boiler and install a small steam boiler for steam needs.

  • If both steam and hot water demands are small, choose a boiler that can produce both.

  • If both steam and hot water demands are large, consider the entire system to choose suitable equipment.

4. Classification and Application of Industrial Boilers

Industrial boilers are classified based on structure, pressure, water circulation type, fuel, and capacity.

By Boiler Type:

Global coal consumption reached an all-time high in 2022 and the world is heading towards a new record in 2023. However, due to the complex characteristics of coal, specific designs are required for certain types. Common types of industrial boilers include:

1. Chain Grate Boiler: This boiler is suitable for burning various types of coal, particularly higher quality coal. With the support of the furnace arch, it can handle coal with a higher calorific value. However, chain grates have high metal consumption, so lower calorific value coal requires a larger grate area, increasing metal consumption.

  • Suitable Fuel: Medium to high-quality coal (calorific value above 4000 kcal/kg).

2. Moving Grate Boiler: This boiler stirs coal during the combustion process, making it suitable for various coal types. Due to its inferior cooling compared to the chain grate, it is ideal for burning coal with high ash content, as the ash can protect the grate bars from overheating and burning out.

  • Suitable Fuel: Coal with high ash content (calorific value between 2700 and 4500 kcal/kg).

3. Pneumatic Throwing Grate Boiler: This boiler has wide fuel adaptability but is unsuitable for burning anthracite. Anthracite requires a long rear arch, while the pneumatic throwing grate needs an open furnace and secondary air. This boiler features semi-suspended combustion and sensitive load adjustment but produces flue gas with high dust levels. Measures such as controlling coal particle size and optimizing secondary air use are necessary to reduce dust content.

  • Suitable Fuel: Various types of coal, but not suitable for anthracite.

4. Circulating Sand Bed Boiler: This boiler is suitable for burning various coal types with a calorific value above 1300 kcal/kg, whether high or low quality. It has low metal consumption, is cost-effective, and offers significant development potential, particularly in environmental protection and burning low-quality coal.

  • Suitable Fuel: Any coal with a calorific value above 1300 kcal/kg.

5. Fine Coal Ppwder Boiler: This boiler is suitable for large-capacity industrial applications due to its complex auxiliary equipment. However, it is not economically efficient for smaller boilers. In regions such as central and southern areas, pulverized coal boilers and dual-purpose boilers with bagasse are commonly used for capacities above 10 tons/hour. Using pulverized coal boilers for small industrial applications is not recommended.

  • Suitable Fuel: Not suitable for small boilers with a capacity below 20 tons/hour.

By Boiler Design:

  • Fire Tube Boilers: Suitable for small-capacity boilers (up to 4 tons/hour). Simple structure, suitable for small applications.

  • Water Tube Boilers: Suitable for large-capacity and high-pressure applications (above 4 tons/hour). High safety, improved combustion efficiency.

By Outlet Pressure:

  • Atmospheric boilers, low-pressure boilers (below 2.5MPa), medium-pressure boilers (2.5MPa to 6.0MPa), high-pressure boilers (above 6.0MPa), ultra-high pressure boilers, subcritical boilers, supercritical boilers, ultra-supercritical boilers.

By Water Circulation Type:

  • Natural Circulation Boilers: Rely on the density difference between water and steam for circulation. Advantages include simple structure, stable operation, and low maintenance cost. Suitable for medium and low-pressure applications.

  • Forced Circulation Boilers: Use mechanical pumps for water circulation, suitable for high-pressure and large-capacity applications. Higher efficiency and flexibility, but more complex and costly to maintain.

By Fuel Type:

  • Solid fuel boilers: such as coal-fired boilers.

  • Liquid fuel boilers: such as oil-fired boilers.

  • Gas fuel boilers: such as gas-fired boilers.

  • Waste heat boilers: utilize waste heat from industrial processes.

  • Waste material boilers: use industrial waste as fuel.

By Capacity

  • Small boilers: less than 20 tons/hour.

  • Medium boilers: between 20 and 75 tons/hour.

  • Large boilers: more than 75 tons/hour.

Other Factors:

  • Size: Different manufacturers may have varying dimensions for the same model, so users need to know the specific size.

  • Load Fluctuations: Boilers must handle load variations, ensuring stable and efficient operation under different conditions.

  • Environmental Pollution: Choose low-pollution boilers that meet emission standards.

  • Automation: Highly mechanized and automated boilers improve efficiency and reduce labor costs and operational risks.

  • Water Quality: Boiler performance and lifespan depend on water quality, which must meet standards.

5. Determining Boiler Capacity and Quantity

Choosing the right capacity and number of boilers is crucial:

  • Total Load Range: Based on production or heating needs, determine the total load range and peak load. For example, a food processing plant with a daily steam demand of 5 tons but peak demand of 8 tons in the morning and afternoon. Set the total load range at 8 tons/day.

  • Equipment Capacity: The boiler's economic load should be above 75% of the rated capacity. For example, a boiler rated at 10 tons should operate above 7.5 tons for efficient operation.

  • Backup Capacity: Consider backup capacity for boiler outages. A textile plant with a daily demand of 12 tons can have two 12-ton boilers, with one as a backup.

6. Water Treatment Techniques for Industrial Boilers

Water treatment is critical for efficient boiler operation and longevity. Key considerations include:

Water Quality Requirements and Treatment Methods:

  • Water Softening: Remove calcium and magnesium salts to prevent scaling using ion exchange technology.

  • Deaeration: Prevent corrosion using thermal, vacuum, or chemical deaeration methods, with thermal deaeration being the most common.

Water Treatment Characteristics:

  • In-Boiler Treatment: Add softening agents to the boiler to convert scale-forming substances into sludge, which is then discharged. Advantages: simple and cost-effective, but requires regular cleaning.

  • External Treatment: Softens water before it enters the boiler, thoroughly removing salts and impurities. Advantages: more effective, reduces scaling and corrosion, but higher cost and requires professional maintenance.

Chemical Dosing Applicability:

  • No water-cooled wall tubes.

  • Reliable sludge removal during operation.

  • Mud formation from dosing does not affect boiler safety.

  • Low steam quality requirements.

7. Maintenance and Safety Measures for Industrial Boilers

Regular maintenance and safety measures are vital for optimal boiler performance and lifespan:

  • Regular Maintenance: Includes inspections, cleaning of smoke tubes and water tubes, replacing worn parts, and monitoring control systems.

  • Safety Measures: Operators should receive professional training and follow all safety regulations and procedures.

Conclusion

Choosing the right industrial boiler requires thorough research and careful evaluation of factory needs. Low-pressure boilers are suitable for light industry applications such as food and beverage, textiles, chemicals, and pharmaceuticals. In contrast, medium to high-pressure large boilers, with high automation and remote control systems, are better suited for power plants, ships, and heavy industry.

OSHIMA has over 30 years of experience in manufacturing and sales, specializing in various small and medium-sized boilers. Our product range includes fire tube, water tube, condensing, electric, and biomass boilers to meet different industry needs and standards. Contact us for more information on boiler solutions.

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