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TYPICAL CONDITION WHICH EFFECT GLYCOL LOSSES

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Typical Condition Which Effect Glycol Losses Carryover with outlet gas leaving the contactor. Leaks at the pump or pipe fittings. High still overhead temperature. Contactor column operating at excess gas rates. Foaming. Rapid changes in the gas rate. But Who do we know if our system operating efficiently or not. Well, we take glycol samples in the field have lab test them, in term of the results then you make the necessary adjustments to reach maximum drying efficiency. Now we can find out by analyzing the glycol, now it can tell us Glycol weight percentage Water content Hydrocarbon content Salt contaminant Solids contaminant The pH of glycol Iron content Foaming tendencies Glycol weight Percentage The glycol weight percentage reefer’s to the amount of glycol in the glycol solution also known as glycol purity. Lean glycol should contain about 98.5 to 99.9% glycol. Rich glycol content varies about 93 to 96% glycol. Let’s assume rich glycol sample is i
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OPERATING PRESSURE

Operating Pressure Conditions for Effective Glycol Conditioning and Reduction of Glycol Losses Now let’s look at operating pressure inthe contactor, re-generator, filters and GCG separator.  Contactor Operating Pressure If you operate the contactor below the properly design pressure you will have problems.  First, at constant temperature water content of inlet gas increases and pressure decreases, causing the unit work harder to dry the gas. Secondly, at constant gas rates the gas velocity through the contactor increases as the pressure decreases causing carryover problem. Regenerator Operating Pressure Regenerator pressure where build-up If there is plugging or flooding problem in the still packing and increases regenerator pressure prevent some water boiling out of the glycol requiring higher temperature in the re-boiler, this waste fuel gas and also the glycol degradation. Filter Operating Pressure As far as filter goes a pressure drop up of 3 to 6 psig is norm
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OPERATING TEMPERATURE

Operating Temperature Conditions for Effective Glycol Conditioning and Reduction of Glycol Losses First we look at operating temperatures in the contactor, re-boiler and still overhead. Than we look at operating pressures in next post. Contactor Operating Temperature In the contactor the temperature of inlet gas and the glycol affect the amount of water removal from the saturated gas. Now if you recall that constant pressure of natural gas can be hold pure water as the temperature the gas increases and what is that mean, well its mean if we keep the inlet gas temperature low the unit will have less water content to remove from the gas. Now you also want to keep the lean glycol temperature down to minimum when entering the contactor but still 10 o F-15 o F (5 o C-7 o C)  higher than the inlet gas temperature. Why? For several reasons, Advantages of Low Inlet Temperature Warm glycol absorbs water more easily that hot glycol. Cool inlet gas has less water in it.   Hy
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HEAT EXCHANGERS

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Heat Exchangers Used in Gas Dehydration Process These are two types of heat exchanger used to cool the glycol and the glycol dehydration unit.  Glycol to glycol heat exchanger and  Glycol to gas heat exchanger.  Now, lean glycol leave the re-boiler must be cooled proper to entering the contactor the cooling allows to lean glycol to absorb the maximum quality of water from the gas in the contactor. The heat exchanger is very important in the overall operating efficiency of the dehydration unit they substantially reduce the amount of heat required by the re-boiler and allow maximum gas dehydration in the contactor.  The first stage of glycol cooling occurrence the glycol to glycol heat exchanger.  This heat exchanger cool the lean glycol coming from surge tank at 400 o F (204 o C ) to temperature of 212 o F  (100 o C ).  The final stage of lean glycol cooling occurrence the glycol to gas heat exchanger.  Dry gas leaving the contactor passes through the gly
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SURGE TANK & PUMP

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Surge Tank or Accumulator Now the surge tank store regenerated glycol for pump suction and it is commonly position under the re-boiler. Vapor which are trapped in the surge tank could cause circular pump to vapor lock. Therefore a vent line is provided to remove these vapors from the surge tank. Pump Most small dehydration unit used a fluid driven pump (Nandpur Field). Larger units generally used electrical driven reciprocating pumps in either case.  The pump is a critical part of the unit because it has the only moving part in the system. Pump Safety Now before the rich glycol enters the pump it passes through a strainer to remove large particles leaks can be a problem around glycol column pumps. Proper packing land maintance and use the manufacture recommended packing can minimize this problem.
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RE-GENERATOR

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Re-Generator (Method to Recovered Glycol from Water-Glycol Mixture) The re-generator is a combination of glycol re-boiler and the still column. They work together to regenerate rich glycol. Making it lean glycol and ready to use in the contactor column.  The re-boilers supply heat to separate glycol and water by simple distillation. Glycol is heated to a temperature between  380℉ to 400℉ (193℃ to 204℃) to removing up water vapor to regenerate the glycol to 98.5% to 90%. The temperature of TEG should not exceed 400℉ (204℃) because TEG will began to breakdown at higher temperature. Re-boilers can be direct fire (Nandpur Field) or heated by steam or hot oil. Direct Fire Re-Boiler Direct Fired Re-boiler type containing a removable fire box and fire tube is normally used and over flow weir maintains the glycol level in the re-boiler excess glycol spills over the weir and flows downward into the surge tank by gravity by passing through Glycol-Glycol Heat Exchanger. When th
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FILTERS

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Filters Used In Gas Dehydration Process Filters are installed in the glycol stream to remove solids and other contaminates which may cause plaguing and foams. Types of Filter Two types of filter commonly used as a gas dehydration system. One type is used for solids removal. Other for dissolved contaminants removal. For solid removals fine stream shock type or cartridge filter (Nandpur Field) are used. Now solved particles cause erosion of pump piston valve seals and plugging of equipment and foaming. Solid Removal (Cartridge or Shock Filters) Shock filter are commonly used type of solid removal. Shock filter consist cylindrical elements that are replaced as they coated with solids.  Differential Pressure Gauge A difference pressure gauge measure pressure drop across the element a pressure drop of 3 to 6 psig  (21 to 41 kpa) is normal as glycol flow through the element the pressure drop increases as the element remove solid material and inverse
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