Introduction
In a pulverized coal-fired boiler of a large power plant, an oxygen analyzer is essential for combustion control. Exhaust gases from the pulverized coal boiler contain a large quantity of dust and flow very fast. Oxygen analyzers that employ a sampling method may be subject to wear or clogging, resulting in increased maintenance workload and cost.
A solution to this problem is the ZR22G/ZR802G Zirconia Oxygen Analyzer that has no sampling system and utilizes a long-life sensor. A probe protector is attached to protection it against wear.
Expected Benefits
- Improves combustion efficiency for pulverized coal-fired boilers
- Ensures stable, continuous oxygen measurement
- Reduces operating cost
- Minimizes the need for equipment replacement
Process Overview
While heavy oil, light oil , kerosene commonly used as a boiler fuel, coal is also used because it is inexpensive and readily available. Unlike oil, coal and gas produce a large quantity of ashes when it is burned, necessitating pulverized coal-fired boilers to be equipped with an ash removal system such as a cyclone. Exhaust gases from these boilers contain a large quantity of dust (10 to 30 g/Nm3) and flow very fast as the result of the large volume of air being blown into the boiler. For oxygen measurement in large ducts, a probe with a long insertion length is used.
Solution Details
Field Data
Process conditions
| Measurement point | Economizer outlet |
|---|---|
| Temperature | 300 to 400°C |
| Flow rate | ≤ 30 m/s |
| Pressure | ±1.5 kPa |
| Dust | approx. 15 g/Nm3 or less |
| Fuel | pulverized coal |
Measurement system
| Detector | ZR22G-☐☐☐-S-☐-☐-☐-☐-E-A/CV |
|---|---|
| Probe protector | ZO21R-L-☐☐☐-☐*B |
| Converter | ZR802G-☐-☐-N-N /☐ |
| Flow setting unit | ZA8F-☐*C |
| Pressure regulator | G7013XF or G7014XF |
| Case for calibration gas cylinder | E7044KF |
Note: the calibration gas cylinder must be purchased locally
Utilities
| Rated voltage | 100 to 240 V AC |
|---|---|
| Rated frequency | 50/60 Hz |
| Power consumption | 330 VA (Max. 800 VA) |
| Instrument air | 300 to 700 kPa |
Notes
- A probe protector should be attached to the probe for protection against wear or damage. The probe protector should be mounted with the notch of the probe head pointing downstream in the gas flow.
- It is recommended that the detector be installed with the probe tip pointing downward. As shown in the figure, it may be installed horizontally, too. The probe head tip should not point upstream in the gas flow.