Lean-TEG

Rich TEG to sep Rich TEG to still Lean TEG from reboiler Lean TEG to pumps (max) Lean TEG to contactor... 

A computer program was developed by Grandhidsan et al., to estimate the number of trays and the circulation rate of lean TEG needed to dry nat-ual gas. It was found that more accurate predictions of the rate could be achieved using this program than using hand calculation. ... 

TRAYS IN GLYCOL CONTACTOR GLYCOL REGENERATION HEAT LOAD (MW) CONTACTOR LEAN TEG CONCENTRATION (% Wt) OPERATING TEMPERATURE (°c) 98.4 98.7 99.0 99.3 99.5 ... 

For the purpose of this study, a contactor column with two theoretical stages and with the feed composition shown in Table 2 was simulated. The concentration of the lean TEG stream was 99.0 weight % TEG, and it was assumed the TEG temperature was the same as the feed gas. The feed gas was saturated with water at feed conditions. For each contactor pressure and temperature, the lean TEG circulation ratio was varied. 

Lean TEG is used as a reflux to the contactor, and tire water dew point of the dehydrated gas depends on the concentration of tire lean TEG. With the increase in lean-TEG purity, tire equilibrium dew point of the dehydrated gas is reduced. The minimum TEG concentration required for a specified dehydration depends on the contactor temperature and equilibrium dew point. Achieving tire required lean-TEG concentration depends on the design of the regenerator. Normally, a 98.5 wt% lean-TEG concentration can be achieved if the regenerator reboiler is operated at 204°C. Generally, the following Figure 5.7 is used to establish the minimum lean-TEG concentration [3]. 

Figure 5.7 Minimum lean TEG concentration. (Courtesy Gas Processing Supplier Association.)...

The number of theoretical stages required depends on tiie reflux rate, lean-TEG concentration, and the water removal requirements. Water removal is defined as... 

For proper estimation of exchanger heat duty, it is essential to calculate the density and specific heat of glycol. For lean TEG, the density is approximately estimated as... 

The required concentration of lean TEG is a function of reboiler temper-afure and stripping gas flow. Generally, the reboiler for the TEG regeneration system is maintained at 204°C, and at this reboiler temperature, 98.5 wt% TEG is achievable without using any stripping gas. The reboiler temperature is generally set to a maximum value of 204°C, though a lower reboiler temperature is possible. 

The lean-TEG concentration is first estimated using Figure 5.7, and then Figure 5.9 is used to optimize the reboiler temperature and stripping gas flow [2]. 

Required l later removal ePNciency exceeds maximum achievabiB efficiency. Increase lean TEG concentration by increasing approach to equilibrium temperature or incraase lean glycol recirculation rate... 

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