According to the different temperature of waste heat, the utilization grade of energy grade is different, which can be divided into three grades.
The waste heat above 650℃ is of high grade;
The waste heat at 650 -- 250℃ is medium grade;
Waste heat below 250℃ is low grade.
The high grade waste heat is the high quality energy, it occupies a very important proportion in the total amount of waste heat energy, it should be carefully managed to recover.
Low grade waste heat, although the temperature is low, it is difficult to recover, but because it accounts for a very large proportion in the waste heat energy, the utilization potential is great, we should actively take effective measures to carry out the recovery and utilization of this part of waste heat.
The waste heat of medium grade is a better secondary energy, it occupies a large proportion in the total waste heat energy, and it is not to be neglected in the waste heat recovery, and it is more advantageous in the conditions and methods of waste heat recovery than the first two.
2. The source of waste heat
The waste heat of the above three grades can be derived from the following sources:
1.Waste heat of high-temperature flue gas.
This kind of working medium has high temperature and high heat, and the proportion of residual heat can be recovered is relatively high, accounting for about 50% of the total waste heat resource.
2. Waste heat of cooling medium.
This part of the residual heat accounts for about 15% - 23% of the total amount of waste heat resources, which is a considerable amount.
3.Waste heat from high temperature slag of high temperature products.
This amount of residual heat accounts for about 6% to 14% of the total residual heat.
4. Waste heat produced by chemical reactions of substances.
It accounts for about 5 to 9 percent of the total waste heat resources.
5. Waste heat of combustible exhaust gas, waste liquid, etc.
This excess heat accounts for about 8% of the total pre-heat.
6. Exhaust gas discharged, waste heat of waste water.
This part of the matter emissions into the atmosphere and the environment of the residual heat about 10% - 16% of the total resources.