1 Scope
This standard specifies the design and calculation method of thermal efficiency of gas-fired and oil-fired petrochemical tubular heaters. This standard is applicable to the design and calculation of thermal efficiency of gas-fired and oil-fired petrochemical tubular heaters.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
thermal efficiency
total heat absorbed divided by total heat input, or difference of total heat input minus total heat loss divided by total heat input
2.2
system
object whose thermal efficiency is calculated by thermal balance The objects outside the boundary of the system are all referred to as the external environment
2.3
total heat absorbed
sum of the used heat output from the system to the external environment
2.4
total heat input
sum of heat from the external environment to the system
2.5
total heat loss
sum of the unused parts of heat from the external environment to the system
2.6
lower heating value
heat of reaction when the water vapor in the combustion products still exists in gaseous state after the fuel is completely burned, based on 15°C
2.7
sensible heat
heat absorbed or released by a substance along change in temperature. Generally, it refers to the sensible heat under specified pressure
2.8
datum temperature
reference temperature that measures the heat brought in or out by objects crossing the boundary of the system, entering the system, or leaving the system, under which, it is assumed that the enthalpy values of all objects are zero
3 Design and calculation of thermal efficiency
3.1 The thermal efficiency shall be calculated using Equations (1) and (2):
Foreword i
1 Scope
2 Terms and definitions
3 Design and calculation of thermal efficiency
Annex A (Informative) Design and calculation chart
Explanation of wording in this standard
