One of the largest plants in the area of Chau Khe craft village, Dinh Bang commune, Bac Ninh province, the Xanh Ha Steel Plant sells about 3,500 tonnes of steel billets and 10,000 tonnes of finished steel products each year, consuming more than 4,000 MWh of electricity and about 900 tonnes of coal. The expenses on electricity and coal consumption account for more than 50 percent of the total production cost at the plant. The plant has undergone an energy audit to seek suitable solutions for energy conservation.

The leadership of the plant said that except the expenditure on input materials, the cost of energy consumption accounts for 50.4 percent of the total amount of all the remaining expenses on steel billet production (the percentage is 68 percent in the area of making finished steel products). Such a high expenditure on energy consumption is unacceptable especially in circumstances when energy prices rise continuously. Therefore, it is urgently necessary for the plant to improve management and take appropriate technical solutions to save energy in order to enhance the competitiveness of products and make a higher profit as well as prevent adverse impacts on the environment.

The main types of energy that are used by the Xanh Ha Steel Plant include electricity, coal and fuel gas. The expenditure on electricity accounts for 43 percent of the total cost of energy consumption, and coal 56 percent while the expenditure on fuel gas accounts for just a small percentage. Each month, the plant has to spend more than VND4 million to buy four gas tanks and 10 oxygen (O2) tanks.

Steel production

Survey results show that low-load operation and the low capacity coefficient of the engines of most equipment items at the steel production workshop are the main reasons leading to electricity losses. Apart from the two main stages of steel production, power consumption in subordinate stages accounts for 21 percent of the total amount of electricity that is consumed throughout the production process. Electrical equipment items that are used to make finished products are of low capacity. During the production process, only some types of equipment operate continuously while other equipment items are kept at the no-load status wasting much electricity.

In the area of crude steel production, an energy conservation solution proposed by the auditors is to install the Powerboss power saving equipment, which can help the plant save 18 percent of the total amount of power consumption, i.e. 10.26kWh each day. This solution allows the plant to save 67,700kWh of electricity or more than VND70 million.

In the area of steel refining, the installation of inverters can help the plant save a large amount of power or about VND106 million each year.

The installation of water supply and treatment systems to cool the tempering furnaces also allows the plant to save VND24 million each year.

Reducing heat losses

Built in 2004, the tempering furnaces of the Xanh Ha Steel Plant cause big heat losses during the operation process. The main reason is that the construction of these tempering furnaces was incompliant with some technical standards. For this reason, the furnaces consume too much coal to start the operation process.

There are many solutions that can be taken to reduce heat losses, for example 1) choosing a suitable coefficient of redundant air (this solution allows to save VND658 million each year), 2) reducing heat losses caused by unsuitable heat-conducting materials to save VND227 million each year, and 3) reducing heat losses when opening the door of furnaces to save VND354 million each year.

The auditors said that the above solutions are feasible because they require low investment and it takes not much time to recover the invested amount of capital. Of the aforementioned three solutions, the second one requires investment of VND52 million, and the remaining two solutions can be taken by organizing training courses to improve workers’ consciousness of the need to save power.

Tightening management

Currently, many steel plants are actively saving power. The auditors said that though they use the same kinds of input materials and similar production lines, the Xanh Ha Steel Plant consumes much more energy than the Thai Nguyen Steel Joint Stock Company. The reason is that the Thai Nguyen Steel Joint Stock Company keeps a close watch on the situation of energy consumption and they have set norms for energy consumption. Moreover, they use suitable kinds of input wasted materials and have reduced the time needed to produce a batch of steel products.

Specifically, the Thai Nguyen Steel Joint Stock Company consumes 760kWh of electricity to produce each tonne of steel billets, 50.2kWh less compared with the Xanh Ha Steel Plant. This means with the same production output, the Thai Nguyen Steel Joint Stock Company can save 182MWh or about VND120 million each year.

Survey results show that the average amount of no-load losses at the Xanh Ha Steel Plant is 62,000kWh of electricity every year. A solution that is proposed to the plant is to reorganize the production process to reduce no-load operation of equipment by a maximum of 50 percent. This solution allows the plant to save more than VND80 million annually.

In addition, it is necessary to intensify training and propaganda in order to improve the consciousness of workers and all staff members of the plant about the need to save electricity. Maintaining equipment items periodically is also necessary to improve their efficiency and reduce power losses during the operation process.

By Nga Nguyen