During the production process, the plants of all sectors, from metallurgy, thermoelectric, chemicals to pharmaceuticals or textiles and garments, use high-temperature furnaces. Research results show that when fuels are burnt, only a small amount of it is utilized, while the rest the energy goes to waste in the form of heat. Experts are now focusing on how to recover all this heat and turn it into electricity in order to use it in production.

Eighty percent of waste heat from industrial plants can be recovered and reused

Thanks to waste heat recovery techniques, the efficiency of thermal energy at industrial production lines can now exceed 90 percent. The utilization of heat during the burning process also helps reduce the amount of CO2 (carbon dioxide), SO2 (sulfur dioxide) and other kinds of toxic gas that are produced by industrial production facilities by 50-80 percent. Waste heat recovery solutions are not only energy efficient and minimize the emissions of dangerous exhaust, but it also brings companies considerable economic benefits.

Recovery is simple

The process of waste heat reuse takes place in different stages. The most important stage is waste heat recovery, when waste heat is recovered and then reused.

Waste heat can be recovered with several different methods. The most popular principle of heat exchange is that of reverse flow heat exchangers. This method allows for the recovery of 80 percent of waste heat and the utilization of 90 percent of the fuels. Vailand, a European firm, recently launched a type of equipment that uses an attached device to recover heat for reuse. This device is able to utilize 95 percent of waste heat.

In technical terms, the reverse flow operation principle is simple. Thermal energy from exhaust fumes or from wastewater is transmitted through clean air or water into a heat exchange room. The heated-clean air is then transferred to another production stage that requires a lower temperature or it is pumped into furnaces to accelerate the burning process. The heated-clean water will also be transferred to another production stage that requires hot water or it is pumped into steam boilers. With this method, plants that use steam boilers are able to recover heat and millions of liters of steam for reuse.

American scientists have invented a system that uses propane to transform waste heat from industrial exhaust pipes into electricity. This system generates power and helps reduce carbon dioxide emissions and other kinds of dangerous waste. Another group of scientists have invented a second turbine that allows industrial production facilities to utilize all of the waste heat from exhaust pipes that work at temperature below 450 degrees centigrade. Power plants that use these double turbine systems can increase their efficiency from 35 percent to 60 percent.

High economic benefits

It is estimated that if 20 percent of industrial waste heat can be utilized to generate electricity, the USGermany) consumed two million euros worth of gas each year. Since it installed three heat recovery systems that cost 150,000 euros, fuel consumption has been reduced, which has allowed the plant to save about 1.4 million euros each year. will have an additional 20 percent of power. Previously, the Laufenberg Plastic Lamination Plant (

In Vietnam, the TH Textiles and Dyes Joint Stock Company used to consume four tonnes of coal each day. Since it installed the heat recovery system from the Simon Group (Germany), the company has been able to reduce its coal consumption by 50 percent. After 72 days, the company saved enough money to cover the installation cost for the equipment. 

The utilization of waste heat brings companies considerable economic benefits and it also contributes to reducing environmental pollution and conserving energy.

The reuse of thermal energy reduces not only the cost of fuel consumption but also the cost of investment in additional facilities. Most industrial production lines that were built in recent years have heat recovery systems that were designed to be compatible with the operation of furnaces, steam boilers, exhaust pipes and wastewater drainage systems. The amount of money that can be saved from reducing the size of furnaces and exhaust pipes is higher than the total cost of installation of a heat recovery system.

The paradigm of a reverse flow heat recovery device

The waste heat reprocessing technology can be applied in most production systems. However, many companies are not interested in this technology. Due to the lack of information, they are afraid that it will be costly to install this technology. They are also unaware that this green technology will help them reduce the cost of production, enhance their competitiveness and contribute to improving the environment.

Energy resources are becoming exhausted due to massive consumption. Energy conservation therefore has become a matter of global concern. Industrial production facilities consume large amounts of energy and cause environmental pollution. Learning how to deal with exhaust fumes and wastewater that comes from industrial production facilities every day is still a pressing problem. Heat recovery technology will hopefully help improve the situation and prevent the earth from warming up.

By Tran Lieu