So far the majority of newly-made low-grade utility systems in petroleum corporations of China are still designed by experiential way, namely an arbitrary choice at heat resource and heat trap and a breach of thermodynamics.

This paper indicates the inlet temperature of heat resources net and the cycle water flow are two critical technological parameters of a low-grade utility system and analyses their effects on a low-grade utility system both in theoretical and engineering viewpoints through an practical example with support of detailed data of analogy calculation.

In addition,the low-temperature heat utilization in deaeration of desalted water and temperature elevation of deaerated water is explored on the basis of refinery system integration and optimization.

,Ltd is introduced,and the potential of low-temperature heat utilization is analyzed.

Recovery of heat from boiler exit gas by plate heat exchanger and thermodynamical analysis on utilization of low grade heat energy;

Analyses the advantages of using low temperature geothermal gradient utilization system with serial mode of radiator and water source heat pump for retrofitted projects.