**Detailed explanation of the function of Roots blower for boilers**
**1、 Overview of Core Functions**
The Roots blower in the boiler system mainly undertakes the functions of gas transportation and pressure maintenance, and its core functions can be summarized into the following three categories:
|* * Function Type * * | * * Specific Functions * * | * * Typical Application Scenarios * *|
|--------------------|------------------------------------------------|-----------------------------|
|* * Combustion and oxygen supply * * | Delivering stable air flow to the furnace to ensure full combustion of fuel | Blast system for coal-fired/gas-fired boilers|
|* * Material conveying * * | Pneumatic conveying of coal powder, fly ash, limestone and other media | Circulating fluidized bed (CFB), coal powder furnace|
|* * Process gas circulation * * | Maintain gas flow in flue gas recirculation (FGR), desulfurization and denitrification systems | Environmental protection facilities supporting|
---
**2、 Analysis of Segmented Functions**
**1. Combustion air supply**
-Working principle:
By forcing air supply to overcome furnace resistance (usually 15-35kPa), the air flow rate and fuel quantity are matched according to the air-fuel ratio:
$$
Q_{air} = \frac{m_{fuel} \times AFR}{60} \quad (m3/min)
$$
*Example: A 10t/h coal-fired boiler (AFR=1.2) requires an air volume of approximately 12m3/min*
-* * Technical Advantages * *:
-Flow fluctuation ＜ ± 2 (better than centrifugal fan)
-Maintain a constant air supply volume even when the furnace back pressure changes
**2. Bed material fluidization of fluidized bed boiler**
-* * Key Parameters * *:
|Parameters | Conventional fluidized bed requirements | Roots blower adaptability|
|----------------|--------------------|---------------------|
|Fluidization wind speed | 0.8-1.5m/s | Precise control through frequency conversion|
|Pressure stability | Δ P ＜ 5 | Natural advantages of volumetric structure|
|Particle tolerance |<200 μ m dust | Pre cyclone separator required|
-* * Typical Configuration * *:
```mermaid
flowchart LR
A Roots blower -->B air preheater -->C air chamber -->D air distribution plate -->E bed material fluidization
```
**3. Pneumatic ash conveying system**
-* * Performance Requirements * *:
-Transport concentration ratio: 3-10kg ash/kg gas
-Wear resistant design: hard alloy (C ≥ 55) is welded onto the surface of the impeller
-* * Economic Comparison * *:
|Transportation method | Energy consumption (kWh/t ash) | Maintenance cycle|
|-----------|--------------|-----------|
|Roots blower | 8-12 | 6-8 months|
|Screw compressor | 10-15 | 3-4 months|
**4. Environmental protection system supporting facilities**
-Application of desulfurization and denitrification:
-Limestone slurry injection: The pressure needs to be stable at 25-40kPa
-Flue Gas Recirculation (FGR): Flow regulation ratio up to 1:3
---
**3、 Key points of system integration**
1. Explosion proof design (coal-fired/gas-fired boilers)
-Motor protection: Ex d Ⅱ B T4 (methane environment)
-Static electricity: impeller grounding resistance ＜ 10 Ω
2. High temperature resistance measures**
-Shell water cooling jacket (working condition>150 ℃)
-The sealing material selected is graphite filled PTFE (temperature resistant to 250 ℃)
3. Dust protection**
-Third level filtration system:
```
Coarse filtration (100 μ m) → Cyclone separation (20 μ m) → Bag filter (5 μ m)
```
-Differential pressure monitoring: triggering blowback when exceeding 500Pa
---
**4、 Energy efficiency optimization plan**
1. * * Variable frequency control**
-Energy saving calculation:
$$
\Text {Energy saving}=P_N \ times [1- (\ frac {n2} {n1}) ^ 3] \ times T
$$
*Example: 75kW fan speed reduction of 20, annual power saving ≈ 32000 kWh*
2. * * Heat recovery system**
-Preheating combustion air using exhaust at 80-120 ℃ (recovery efficiency of 30-50)
---
**5、 Selection technical specifications**
|* * Parameter * * | Coal fired boiler requirements | Gas fired boiler requirements|
|----------------|--------------------|--------------------|
|Flow margin |+20 |+15|
|Pressure margin |+10 |+5|
|Temperature resistance level | ≤ 250 ℃ | ≤ 150 ℃|
|Protection level | IP65 (dustproof and waterproof) | IP54|
---
**6、 Key points of maintenance management**
1. * * Daily inspection**
-Vibration value: ≤ 4.5mm/s (ISO 10816 standard)
-Bearing temperature: ≤ 95 ℃ (monitored by infrared thermometer)
2. * * Regular maintenance**
-Change gear oil every 2000 hours (ISO VG220)
-Clean the muffler filter cotton every six months (weight loss<15)
---
**7、 Industry application differences**
|Boiler type | Roots blower configuration characteristics | Typical brand and model|
|---------------|-----------------------------------------|---------------------|
|Circulating fluidized bed | High pressure type (49kPa)+wear-resistant impeller | Changsheng CSR-200|
|Coal powder furnace | Explosion proof type+Precision filtration | Changsheng CSR-150H|
|Gas boiler | Low noise design (≤ 85dB (A)) | Changsheng CSR-125B|
---
**Summary * *:
The Roots blower for boilers is the core equipment for combustion optimization, material transportation, and environmental compliance. Its constant flow characteristics and strong anti-interference ability are particularly suitable for the complex working conditions of boiler systems. When selecting, special consideration should be given to the characteristics of the medium (dust/corrosiveness) and system resistance, and corresponding protective measures should be configured. For large boiler systems (>35t/h), it is recommended to adopt a multi machine parallel+variable frequency control scheme to improve energy efficiency.
