Energy savings for Huaxin Cement, China?

Energy savings for Huaxin Cement, China?
Published: 21 December 2011

An ABB multidrive solution for Huaxin Cement is saving 1.6mkW/hr of electrical energy a year on a demanding conveyor application at the company’s plant in Hubei.

Huaxin Cement has become a model in China’s Circular Economy (CE) initiative.?The CE initiative requires companies to minimise their consumption of resources, reduce their emission of pollutants, and recycle waste and byproducts in their production processes.??Part-owned by Holcim, Huaxin Cement produces 1.8Mt of cement and 75GWh of electric power a year at its Zigui plant in Hubei province.

The power is generated using waste heat from the production process and by collecting and incinerating the debris that floats past the plant in the nearby Yangtze River.??When Huaxin Cement installed a new 2km downhill conveyor belt to transport crushed limestone from a nearby mine to a storage yard at the plant, it looked to ABB for a solution that would operate at the highest levels of reliability and energy efficiency, as well as strengthen Huaxin’s profile of sustainable ‘circular’ production.

The ABB multidrive is saving Huaxin Cement 1.6mkW/hr of energy a year, as well as providing smooth operation and efficient control of a demanding conveyor application.

Downhill conveyors are demanding applications. Continuous braking is necessary to prevent excessive movement of the belt as it moves downhill.??At Hubei, the difference in elevation between the top and bottom of the 1965m conveyor is 320m and the inclination is 10.7 degrees. The belt is powered by two 500kW motors, which are controlled by an ABB ACS800 multidrive with a regenerative supply unit that feeds energy back into the grid.

The drive provides dynamic control of the speed and torque of the motors and enables soft starting and stopping of the conveyor belt. Soft starting eliminates mechanical stress during startup and prevents the material from spilling and the belt from folding.??

During downhill operation the drive harnesses the energy produced by the conveyor system and feeds it back into the cement plant’s power network.??Huaxin Cement has calculated that the ABB multidrive solution has achieved annual energy savings of up to 1.6mkW/hr, which is worth US$138,000 a year. The savings in greenhouse gas emissions are correspondingly huge, thus making a significant contribution to Huaxin’s CE targets.