Considerations in Designing a Closed Loop Heating Medium System

AIChE 2013 Spring Conference

Topical 6: 13^th Topical Conference on Gas Utilization – LNG Technology and Development

Considerations in Designing a Closed Loop Heating Medium System

Benjamin Gross, Process Engineering, Bechtel Oil, Gas & Chemicals, Inc. 

Debby Sielegar, P.E., Process Engineering, Bechtel Oil, Gas & Chemicals, Inc.

Abstract

A closed loop heating medium system using synthetic heat transfer fluids, such as hot oil, has become a desirable alternative to the conventional boiler feed water / steam in the oil, gas and petrochemical industry. Whether it is for onshore or offshore applications, such systems are reliable, low-maintenance and can be implemented at relatively low cost.

Closed loop hot oil systems can be designed using various configurations depending on the process heat demand, availability of waste heat recovery, desired process control schematic and system reliability, and other operational preferences. In an LNG plant, several factors can affect the required process heat input requirement, such as the feed gas sources and quality, operating conditions, and operating objectives. Waste heat recovery improves the overall plant efficiency by utilizing the waste heat from the exhaust of gas turbines or power generation units. While waste heat recovery reduces fuel consumption, increases LNG production and environmental emission benefits, and therefore the NPV of the plant, other factors such as plot space, local environmental regulation differences, and operational preferences may lead to other simple alternative closed loop heating medium system utilizing conventional fired heater.

These various system configurations along with equipment / mechanical design, process control and reliability, and relief system design challenges for a closed loop heating medium system integrated with or without waste heat recovery are discussed in this paper.