Calculation of the heat load of a heating furnace
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Dear friends from Sichuan, how can we calculate the heat load of a heating furnace more accurately? What data is needed? Currently, the two heating furnaces in my workshop share the same fuel oil.
Dry gas composition: Hydrogen: 7.65%, Methane: 67.2%, Ethane: 19.31%, Ethylene: 2.18%; other components are negligible for now. When burned in complete combination with oxygen, 1 mole of hydrogen releases 285.8 KJ of heat, 1 mole of methane releases 890 KJ, 1 mole of ethane releases 1559.9 KJ, and 1 mole of ethylene releases 1409.6 KJ. Under standard conditions, the volume of 1 mole of gas is 22.4 L. For a processing volume of 93 tons, the fuel gas flow rate to the heating furnace is 3700 standard cubic meters per hour. In total, 3700000/22.4 = 165178.57 mol. The heat of combustion per mol of dry gas is given by Q = 285.8*0.0765 + 890*0.672 + 1559.9*0.1931 + 1409.6*0.0218 = 951.88 KJ. Under ideal conditions, the heat released per hour when the dry gas burns completely is Q (ideal) = 951.88*165178.57 = 157230177 KJ. The heat of combustion per cubic meter of dry gas is 42.5 megajoules; the specific heat capacity of combined oil is 1000 kal = 4180 J. The oil pressure changes within the furnace tubes, and its specific heat also changes accordingly; however, these changes are not very significant, so it is assumed that they remain constant. With a flow rate of 43 cubic meters per hour per unit, the total flow rate for four units is 43*4*0.85 = 146.2 tons. The temperature of the oil drawn from the bottom of the distillation tower is 320 degrees, while the temperature at the outlet of the furnace is 493 degrees; thus, the temperature difference is 493–320 = 172 degrees. It is assumed that the temperature drops by 15 degrees per hour from the bottom of the distillation tower to before the four-way valve. To bring the oil to a temperature of 493 degrees, the heat required is Q1 = CM(T1–T2) = 4180*146.2*187 = 114278692 KJ. This calculation uses the method of positive balance. In reality, the heat released by the furnace per hour (Q(actual)) equals Q(ideal)*η; since specific values cannot be determined, it is assumed that this efficiency is 85%. Therefore, the thermal efficiency of the furnace is Q1/Q(actual) = 114278692/(1157230177*0.85) = 85.5%. Using the simplified formula provided in technical references, the thermal efficiency of the furnace is estimated to be around 82.5%
Reply to 1# pxbgf: By performing an energy balance on crude oil before and after passing through the heating furnace, it is possible to calculate the heat load of the furnace. The properties of the crude oil are needed, as well as the vaporization rate, the properties of products such as those from the top and side streams of the atmospheric distillation column and the residue, and the temperatures of the crude oil before and after entering the heater.
Please analyze and discuss how to calculate the heat load rate of coking heaters Is there a formula?
I have a small program upstairs for calculating the thermal efficiency of stoves; I’ll leave my contact information for you.
This master, please send one to me at 527872786@qq.com. Thank you
The teacher, please send one to me.:: Email: liutie78@163.com
Please send one to me, master. 307673313@qq.com
Master, could you send me one? Thank you.
Hello, could you send me one? dyc0204@126.com
I calculated it using HYSYS and Excel, and the difference in load is quite large