Operating conditions
Overhead cranes of boiler houses and turbine shops of CHP and GRES operate under specific conditions:
- The temperature in the service area is up to 60 °C (near boilers and steam lines)
- Thermal radiation from heated surfaces
- Dust content up to 50 mg/m3 at coal plants (ash, unburned coal)
- The operating mode is mostly simple with short periods of intensive loading (repair campaigns 1-2 months per year)
- Limited dimensions of workshops, minimal gaps
Idle crane during the repair period of the power unit entails penalties from the system operator.
Loads on the running wheels
The load on the wheel consists of:
- Crane and bridge weights
- Cargo weights (nominal lifting capacity of CHP cranes is 10-50 tons, rarely up to 100 tons)
- Dynamic forces during starting and braking
- Temperature stresses caused by uneven heating of the bridge
The speed of movement of overhead cranes of the CHP is 30-60 m/min.
Material and heat treatment
The steel grade is 65G (GOST 14959). 60X2 is allowed.
Surface hardness: 320-390 HB for groups 5M–6M, at least 300 HB for 4M.
The depth of the hardened layer is at least 15 mm.
Heat treatment — sorbitization. HDPE quenching is not recommended — when heated above 200 ° C, the hardness decreases by 30-50 NV.
More detailed information about the sizes and technical parameters of crane wheels for various operating conditions is available on the website https://el-kran.ru /
Wear and tear due to dust
At coal—fired thermal power plants, abrasive wear is the main cause of wheel failure.
Mechanism: ash particles (10-50 microns) are embedded in the rolling surface, causing micro-cutting and discoloration.
The intensity is 2-3 times higher than at gas stations.
Reduction measures:
- Installation of cleaning scrapers
- The use of lubricants with anti-wear additives
- Surface hardness in the upper limit (380-390 NV)
- Surfacing with wear-resistant materials (PG-CP4)
The choice of running wheels for overhead cranes of CHP and GRES is carried out depending on the load on the wheel and the operating mode group.:
- Option 1 (load up to 15 tons, 4M mode group):
- Wheel diameter: 400-500mm
- Rib type: K2P (double-chord)
- Surface hardness: 300-340 NV
- Option 2 (load 15-30 t, 5 M mode group):
- Wheel diameter: 630-710mm
- Rib type: K2P (double-chord)
- Surface hardness: 340-370 NV
- Option 3 (30-50 t load, 6M mode group):
- Wheel diameter: 800-900mm
- Rib type: K2P (double-chord)
- Surface hardness: 370-390 NV
Double-chord wheels (K2P) are used for all variants, providing a reliable direction of movement in case of bridge misalignments resulting from thermal deformations. Hardness
