Heat load is the amount of heat released per unit time when the fuel is burned in the burner. In a burner, the formula is: heat load = fuel consumption * low calorific value of fuel. The size of the heat load is determined by factors such as the size of the main burner fuel consumption.
1.Definition
Heat load contains two meanings, one is the temperature of the heated parts, and the other is the temperature difference of the parts.
The heat flow is usually used to characterize the heat load of the part, which can be expressed by different parameters in different cases. Under the action of heat flow, q=α(Tg-Tw), depending on the heat transfer coefficient and heat conduction conditions, a certain temperature field is formed on the part. Each point on the part can be characterized by the temperature of the point and its surrounding temperature gradient, the greater the heat flow, the higher the temperature on the heated wall of the part, the greater the thermal stress.
Through the temperature of the heated parts, temperature distribution and heat flow measurement, as well as experiments to obtain the operating factors and some structural factors on the temperature of the parts, the impact of heat flow, you can find out the basic laws between them, pre-estimate the heat load of the parts, to determine the potential for strengthening, but also for the design and improvement of parts, control the heat load of the parts to provide a certain basis.
2.The calculation formula
When the amount of internal energy, kinetic energy, potential energy changes can be ignored and no axial work, the heat input to the system and the heat leaving the system should be balanced, which can be derived from the heat transfer equipment heat balance equation: Q1 + Q2 + Q3 = Q4 + Q5 + Q6
Where Q1 - the heat brought into the equipment by the material, kJ; Q2 - the heat transferred from the heater or coolant to the equipment and the material handled, kJ; Q3 - the thermal effect of the process, kJ; Q4 - the heat brought out of the equipment by the material, kJ; Q5 - the heat or cold consumed by the heating or cooling equipment, kJ; Q6 - the heat dissipated by the equipment to the environment, kJ.
In the above equation, it should be noted that except for Q1 and Q4, all other Q values have both positive and negative cases. For example, when the reaction is exothermic, Q3 takes the "+" sign; conversely, when the reaction absorbs heat, Q3 takes the "-" sign, which is the opposite of what is stipulated in thermodynamics.
From the heat balance equation, we can find Q2, which is the heat load of the equipment. If Q2 is positive, it indicates that heat needs to be supplied to the equipment and the material handled, i.e., heating is required; conversely, it indicates that heat needs to be removed from the equipment and the material handled, i.e., cooling is required.
In addition, for intermittent operation, since the operation may be different in different time periods, the value of Q2 should be calculated separately according to different time periods, and the maximum value should be taken as the basis for designing the heat load of the equipment.
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