To 2009, 97 cement production lines have been put into operation in the whole country, with the total designed capacity of 57.4 million tons. In 2010, it has been estimated that 13 more production lines would be completed, which will raise the total capacity by 11.7 million tons. In 2011, 12 more lines will be put into operation, the total capacity is estimated to increase by 9.36 million tons. 

In recent years, although the cement sector has made some breakthroughs in technology as well as in production scale, the use and re-use of energy have not been thoroughly investigated.

To solve that problem, at the end of 1997, Vietnam Cement Industry Corporation (VICEM) had approached the rotary-kiln-heat-utilization technology to generate electricity for cement factories, retrench the amount of power purchased from thermal power plants which were introduced by the Ministry of Science, Technology and the Environment, the Ministry of Construction and NEDO organization. After a survey period, at the early 2008, Ha Tien 2 Cement Company had been selected to implement the pilot project “Reducing power consumption in cement plants”.

Energy-intensive industry

Cement sector is a key industry which contributes to the infrastructure construction and boosts the industrialization and modernization of the country. However, this is also a high energy-consuming industry which dramatically affects the environment and the surrounding landscape. The energy use and reuse has attracted great interest of scientists and investors in cement production.

According to Mr. Tran Van Huynh, Chairman of Vietnam Association for Building Materials, Vietnam cement industry is consuming a very large amount of power - each ton of cement requires 100kWh. In 2010, when the cement output of Vietnam reaches 50 million tons, the power consumption will have been 5 billion kWh.

Currently, the main sources of energy of cement production are coal and electricity. During the manufacturing process, a large amount of exhaust heat and dust is discharged into the air which causes environment pollution, waste of energy, waste of resources and reduction in investment efficiency.

When all dry rotary kiln cement production lines of Vietnam are equipped with exhaust-heat- utilization power systems, the total capacity of power stations will be about 200MW which will generate an amount of power equivalent to 25% of power consumed from the grid. This is an impressive number to such a high energy-consuming industry. If that amount of electricity can be utilized, the energy problem in cement plants will be solved, which will not only bring about economic benefits but also protect the environment.

As Mr. Huynh estimated, each ton of exhaust heat could generate 3-4kWh of power. If all cement plants of Vietnam utilize the exhaust heat from the clinker furnace to generate electricity, the amount of power generated by cement plants will be 1.5 billion kWh by 2010.

The exhaust-heat-utilization technology is currently an energy conservation solution in cement sector which is a big interest in Vietnam. Many countries in the world have installed the exhaust heat generators for cement production lines. Japan is the leading country of Asia in this technology with exhaust-heat-utilization boilers and steam turbines.

Energy efficiency

After 4 years of construction and load testing, on 26 March 2002, the technology to utilize exhaust heat from rotary kiln to generate power was officially applied in Ha Tien 2 Cement Company and initially showed high economic and environmental efficiency.

Mr. Do Cao Duong, the technical manager of VICEM, explained the operating principle of the exhaust-heat-utilization power system in Ha Tien 2 Cement Company: the 350 – 380oC exhaust from the rotary kiln is taken into the boiler to exchange heat to create superheated steam which will be used to make the turbine rotate to spin the generator. The remain of the exchanged heat which is about 230oC is used to dry materials for powder grinders.

So, besides utilizing the redundant heat to create steam to spin the generators, the system also reduced the heat in the grinders and filtered dust.

Only from March 2002 to October 2006, this system had provided the total power of 72 million kWh to production lines of Ha Tien 2 Cement Company. Besides, from July 2004 to October 2006, the company had also saved 2.1 million liters of ADO oil.

According to Vietnam Association for Building Materials, this technology is easy to apply in cement plants in Vietnam. However, the amount of generated power totally depends on the amount of exhaust heat utilized from furnaces, so companies need to carefully consider many related factors like technology line, space layout, the structure of power supply and distribution, water supply equipment.

By Minh Duc