Heat Exchangers in Plants & Refineries | Energy Conservation


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Heat Exchangers in Plants & Refineries | Energy Conservation

  • Can you use heat integration more in an area of integrity?
  • Can heat integration be applied among compatible units?
  • Can heat integration done directly?
  • Do you need a buffer system to conduct heat integration?
  • Can you use combustion gas turbine exhaust to produce utility belt from hot oil, for instance?
  • Can you add extra heat exchanger unit?
  • Do you have an application for heat transfer enhancement?
  • Do you have a possibility to add more tubes?
  • Do you have a possibility to use twisted tube units?
  • Do you have a possibility to enhance the fin fan coolers surface area?
  • Can extra shells be installed on re-boilers so that exhaust steam can be used in place of HP steam?
  • Is cooling water rate optimized via heat exchangers configuration in series or parallel arrangement?
  • Is that possible to operate the crude oil de-Salter using hot water and less washing water?
  • Are the crude heat train monitored to proactively clean it and reduce fouling?

Heat exchangers are used throughout the process plants to recover heat from processes and transfer heat to the process flows. Next to efficient integration of heat flows throughout the process plant, refinery for instance, the efficient operation of heat exchangers is a major area of interest.

In a complex refinery, most processes occur under high temperature and pressure conditions; the management and optimization of heat transfer among processes is therefore crucial to increasing overall energy efficiency. Fouling, a deposit buildup in units and piping that impedes heat transfer, requires the combustion of additional fuel.

For example, the processing of many heavy crude oils in the United States increases the likelihood of localized coke deposits in the heating furnaces, thereby reducing furnace efficiency and creating potential equipment failure. The problem of fouling increases with increased processing of heavier crudes.

Fouling is the effect of several process variables and heat exchanger design. Fouling may follow the combination of different mechanisms. Several methods of investigation have been underway to attempt to reduce fouling including the use of sensors to detect early fouling, physical and chemical methods to create high temperature coatings (without equipment modification), the use of ultrasound, as well as the improved long term design and operation of facilities.

Worldwide research in fouling reduction and mitigation is continuing by focusing on understanding the principles of fouling and redesign of heat exchangers and reactors. Currently, various methods to reduce fouling focus on process control, temperature control, regular maintenance and cleaning of the heat exchangers (either mechanically or chemically) and retrofit of reactor tubes.

Overall energy savings of 0.7% by cleaning the heat exchanger tubes of the crude distillation unit and other furnaces can be achieved with reasonable payback period. Fouling was identified as a major energy loss in many refineries. Regular cleaning of heat exchangers and maintenance of insulation would result in significant annual savings.

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