Waste-to-Energy Retrofit: Centrifugal Fans for CFB Boiler-to-Grate Furnace Conversion

Project Background

This project is part of a waste-to-energy plant retrofit project, aiming to convert the existing circulating fluidized bed (CFB) boiler into a mechanical grate furnace.

After the furnace modification, the combustion process and operating conditions changed, which placed new demands on the air supply, furnace cooling, sealing, and flue gas extraction systems.

The existing fan equipment was designed for the previous CFB boiler and can no longer fully meet the new process parameter requirements.

Customer Needs

The customer needs to replace existing blowers to adapt to the operational requirements of the modified mechanical grate furnace system.

The key requirement is not merely replacing the old blowers, but ensuring that the performance of the new blowers matches the airflow, pressure, and temperature conditions of the modified system.

Depending on the modified process requirements, different types of blowers are needed at different operating points.

Operating Conditions

The provided centrifugal fans meet a wide range of operating requirements:

Airflow: 4,510–234,400 m³/h

Pressure: 2,760–8,500 Pa

Temperature: 30–150°C

This system is suitable for both ambient temperature air supply and high-temperature flue gas extraction.

For example, an induced draft fan handling flue gas at approximately 150°C requires an airflow of up to 234,400 m³/h.

SIMO BLOWER Solutions

Based on the customer's updated process parameters, SIMO BLOWER provides 10 centrifugal fans for five different applications:

Primary Air Fans（2 sets）

Provide combustion air for mechanical grate furnaces.

Secondary Air Fans（2 sets）

Provide secondary combustion air and support the required air distribution.

Furnace Wall Cooling Fans（2 sets）

Provide cooling air for designated furnace areas.

Sealing Fans（2 sets）

Provide compressed air for sealing applications within the system.

Exhaust Draft Fans（2 sets）

Extract high-temperature flue gas and maintain the required airflow and negative pressure for the system.

Each fan is selected based on its specific operating conditions, rather than simply replacing existing fans with the same model.

Fan Selection in Retrofit Projects

Furnace modification alters the operating points of the entire air and flue gas system.

Therefore, SIMO Blowers evaluated the new requirements based on the following factors:

Airflow, Pressure, Temperature, Process Load, System Resistance, and Drive Requirements

This ensures the replacement fan is compatible with the improved production process.

This step is particularly crucial for retrofit projects because using existing fan parameters without reassessment could lead to insufficient airflow, excessive pressure, motor overload, or unstable operation.

Manufacturing and Quality Control

After the fan specifications are confirmed, SIMO Blowers conducts manufacturing and inspection work according to project requirements.

Key production stages include:

The fan rotor is motion-balanced before delivery to control vibration and ensure stable operation.

Simultaneously, SIMO Blowers prepares all technical and inspection documents required for equipment delivery.

Project Value

This project demonstrates a crucial consideration in waste-to-energy retrofit projects:

When the combustion process changes, the blower system may also require reassessment.

By selecting a suitable replacement blower based on the new operating conditions, the blower system can better meet the requirements of the upgraded mechanical grate furnace.

For industrial retrofit projects, the suitable blower is not necessarily the same model as the original equipment.

The key is to match the blower with the new process.

SIMO Blower Waste-to-Energy Blower Retrofit Solution

SIMO Blower provides centrifugal blower solutions for applications such as waste-to-energy, boiler retrofits, combustion air, and flue gas treatment.

For blower replacement projects, customers can provide the following information:

● Air volume 

● Pressure

● Temperature

● Gas conditions

● Existing blower data

● New process requirements

SIMO engineers can assess the updated operating conditions and recommend a suitable centrifugal blower solution.

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