Chapter seven - Combating hydrates using heat and pressure

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This chapter discusses means of combating hydrate formation is to avoid the regions of pressure and temperature where hydrates would form. A plug forms in a pipeline because the three criteria for hydrate formation are present—water, gas, and the right combination of temperature and pressure. This discussion examines how one can take advantage of the third criterion in the battle against hydrates. To prevent the formation of hydrates, one merely has to keep the fluid warmer than the hydrate forming conditions (with the inclusion of a suitable margin for safety). Alternatively, it may be possible to operate at a pressure less than the hydrate formation pressure. With a buried pipeline, which loses heat to the surroundings as the fluid flows, the temperature must be such that no point in the pipeline is in the region where a hydrate will form. This heating is usually accomplished by two means, either by using line heaters or heat tracing. Additionally, line heaters are used to maintain the temperature adequate that prohibits hydrates synthesis. The fire tube is a large diameter U-tube, which is the source of energy for the heater. The fuel gas and air enter the fire tube and are burned to produce the heat.