Fire tubes glycol reboilers

The gas from the glycol/condensate separator can be used for fuel gas. In many small field gas packaged units this gas is routed directly to fire tubes in the reboiler, and provides the heat for reconcentrating the glycol. This se[>.irator is sometimes referred to as a gas/glycol separator or pump gas separator. 

The selected system comprises three direct-fired hot oil heaters, surge vessels ond circulation pumps. The hot oil is circulated in a closed loop through the tube bundles in the glycol reboilers. The system allows accurate control of the glycol tempercture ond by designing the fired heaters os a redundant utility system cvailoble to the three process troins the reliability of the system is thereby improved. 

Contamination of the glycol with sodium chloride and/or calcium chloride is a conunon problem. The best solution is an efficient separator in the gas feed line however, no separator is 100% efficient and some brine contamination is inevitable when brine is present in the feed gas stream. Sodium chloride decreases in solubility with increased temperature and therefore precipitates out on hot surfaces (e.g., in the fire-tube reboiler). Calcium chloride has the more common characteristic of being less soluble at low temperatures than at high temperatures. It, therefore, tends to come out of solution in low temperature portions of the system. For example, 95% TEG solution will hold about 4% NaCl at 100°F and less than 2% at 300 F while the same glycol solution will hold 1 % CaCl2 at lOCF and about 35% of this salt at 300°F. 

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