Remould Case Study--Desulfurization Absorption Tower Mixer

Remould Case Study--Datang Xinyang Power Generation Co., LTD

#4 Desulfurization Absorption Tower Mixer

General Outline:

Equipment Information

Operating Status

Remould Plans

Remould Results

Scene photo

Conclusion

Equipment Information:

Datang Xinyang Power Generation Co., LTD. #4 furnace desulfurization absorption tower mixer is professionally designed according to the requirements of site conditions. The absorber diameter of 16 meters, the maximum liquid level is 8.5 meters, and the slurry density are important basis for design. 

The main parameters of the original mixer are as follows:

·  Power: 37 kW

·  Impeller diameter: 1400 mm

·  Shaft diameter: 80 mm

·  Shaft length: 1585 mm

·  Rotating speed: 140 r/min

Operating status:

After a long period of operation, the original mixers gradually showed the following problems:

1. Large vibration: 

During operation, the mixers have obvious vibration, It’s not only increases the wear of the equipment, but also adversely affects the stability of the system.

2. High running current: 

The running current of the original mixers is obviously high, resulting in increased energy consumption and increased equipment load.

3. High daily maintenance costs: 

Due to frequent wear of mechanical seals, the mechanical seal need to be replaced two to three times a year, increasing maintenance costs.

4. Large security risks: 

Due to the unstable operation of the equipment, downtime and even shotcrete occur from time to time, there are large security risks, affecting the normal production of the system.

Remould plans:

In view of the above problems, our company proposed the following remould plans:

1. Adjust the impeller diameter: 

Change the impeller diameter from the original 1400mm to 1200mm. By reducing the impeller diameter, the vibration and current can be reduced. In the meantime, it can improve the mixing efficiency.

2. Optimize cantilever shaft length: 

The cantilever shaft length is changed from 1585mm to 1550mm. The shaft length is slightly shortened to optimize the mechanical structure of the mixer, reduce the bearing force, and improve the operation stability.

After detailed calculation and analysis, the blade diameter, speed, shaft diameter, shaft length and motor power of the modified mixers can fully meet the requirements of the field absorber.

Comparison table before and after renovation

Data	Before	After
Power	37KW	37KW
Impeller diameter	1400 rpm	1200 rpm
Shaft diameter	80 mm	80 mm
Shaft length	1585 mm	1550 mm
Operating speed	140 r/min	148 r/min
Operating current	55A	38A

Remould results:

The operation performance of the modified mixers have been significantly improved, as follows:

1. Optimize the impeller structure: 

The impeller with a guide plate designed by our factory is one of the most advanced structures at present. In actual operation, the amount of liquid discharged is increased by 25% compared with the original structure, and the processing capacity of the desulfurization absorber is greatly enhanced.

2. Improve mixer efficiency: 

By increasing the speed from 140r/min to 148r/min, the mixer efficiency is increased by 6%, achieving a more uniform slurry mixing and reducing local deposition.

3. Prolong the service life: 

After the transformation, the vibration and current of the mixers are significantly reduced, and the overall load of the mixers is reduced. It significantly extends the service life and reduces the daily maintenance frequency and cost.

4. Energy saving: 

After the transformation, the operating current of the mixers is reduced to 38A, which greatly reduces the energy consumption and realizes the energy-saving effect.

Scene photo：

Conclusion:

Absorber mixer is the key equipment in flue gas desulfurization system, and its selection and design are very important. If the selection and setting of the absorption tower agitator is not proper, it will lead to insufficient oxidation of calcium sulfite, low utilization rate of limestone, seriously affect the desulfurization efficiency, and even affect the quality of the generated gypsum; At the same time, uneven mixing may cause local deposition of the tank bottom, especially at the pump inlet, where the sediment will increase the risk of cavitation of the pump, and high concentrations of slurry may enter the pump, causing damage to the equipment.

Through this transformation, we not only solved the problems of vibration and high energy consumption of the original mixers, but also greatly improved the desulfurization efficiency of the mixer and the operation stability of the equipment, effectively reduced the operating cost and safety risks of the equipment, and ensured the long-term stable operation of the system.

Therefore, in the design and layout of desulfurization absorber agitator, it is necessary to combine the field working condition data for fine design, to ensure the efficient and reliable operation of desulfurization system.