The carbon should be changed when the glycol starts getting dark or when the pressure drops across the carbon purifier reaches 10 to 20 lbs. At constant temperature, the water content of the inlet gas increases as the pressure is lowered. The demister is usually designed for a maximum pressure drop of 15 to 35 lbs, depending on the basic design. The lean glycol flows from the reboiler into the accumulator. It should be held 10F hotter than the incoming gas to the absorber. If the paraffin gets into the glycol system, a three-phase liquid hydrocarbon separator can be placed on the rich glycol side to remove the paraffin before it enters the reboiler. We may use cookies (and other technology) for constant improvement of our website, to personalize content to you, and may use cookies to deliver advertising messages and offers that we believe are relevant. Reboiler Design Temperature 450F . I would suspect that the element is undersized for the application or you are lacking the electrical feed to bring the element to its full temp. What happens if too much salt gets in the glycol system? What happened? Finally, you need to have a good understanding of common problems and their solutions. This adjustment can also hold the condenser temperature at the desired level. Monitor the glycol pH and try to determine if the corrosion is coming from the pipeline or from within the glycol system. Yes. Many times you can detect it by looking for finely divided black particles in the glycol. To perform a good troubleshoot on glycol dehydration equipment, you must know what the system is designed for and how the currentconditions compare to that design. If you are not reaching the optimum percentages in either phase, you will have a good idea where to start looking for a problem. How do the glycol and gas mix in the absorber? However, a glycol unit is commonly used for gas dehydration. The vessel should have a length/diameter (L/D) ratio of 5:1 or better. The mixing is achieved by using trays containing usually bubble caps or valves or by filling the vessel with a tower packing. The Kimray Chronicleis your source for news within the Kimray community. Contact and American Chillers sales engineer for assistance. Removing impurities such as hydrocarbons, lube oil and solid contaminants from the glycol will not only increase the removal rate of water from the gas but it will also protect the reboiler and heat exchangers from contamination buildup and loss of efficiency. What would be the cause of the heat exchanger not working properly and sending the glycol too hot to the glycol pumps. Coal-based carbons are hard and dense. The same can be said for discrepancies in flow rate and temperature. Acid cleaning is good for removing inorganic deposits. Line separators on the sales gas leaving the absorber can sometimes be effectively used. I did not realize that glycol can be subject to vaporization. The salt will collect on the firetube in the reboiler to restrict heat transfer and cause corrosion problems. . Schlumberger glycol dehydration processes I believe the massive Glycol loss occurs as carry over with the product gas from the contactor tower. Finally, the cooler could be under-sized for the system. . Apparently the unit was not cleaned before the new glycol was added. The gas moves up through the vessel and the glycol moves downward through the vessel. What should the condenser temperature in the top of the still be? Our company is making a concerted effort to improve our glycol plant operations. The resulting ice sometimes pushes up into the absorber, damaging the chimney tray. Is equipment operating within specifications (flow-rate and temperature)? The tower packing manufacturer should be consulted for design information. f. thermometer with thermowell; kimray glycol pump with "y" strainer on pump suction, ball check; valve on pump discharge; shell and tube type glycol to glycol heat . Will carbon in the purifier remove solids? Multiple stages of removal are contained on a single skid-mounted unit, giving you a wide range of options and flexibility to configure the system to your specific application. Solid paraffin would plug the separator. Are there any limitations to changing pressure on the absorber? Viking pumps are used in Gas Dehydration. For Ethylene Glycol Solutions Temperature Chart For Ethylene Glycol Solutions Books Pics is a cool site that allows you to download fresh books and magazines for free. Or a flow meter could be installed. How slowly should a glycol unit be shut down? Most American Chillers have heat exchangers large enough to handle 30% PG without loss of capacity due to our value-added engineering practices. The field supervisor and operators need both on-the-job and classroom training to help them fully understand the process principles and equipment. Typical glycol dryers comprehend reaching the water dew point of the treated gas to as low as -10-20 . It should be held 10F hotter than the incoming gas to the absorber. In the long run, this will lessen the wear and tear on your glycol regneration process and equipmentand save money on filters and fuel costs for the burner. Glycol Regeneration: 5 Ways to Maximize Glycol Purity, Lever Operated Piston Balanced Throttling, Pneumatically Operated Diaphragm Balanced, Pneumatically Operated Piston Balanced Throttling, Free Water Knockout Mechanical Three Phase, Horizontal Separator High Pressure Pneumatic Three Phase, Horizontal Separator Low Pressure Mechanical Three Phase, Vertical Separator High Pressure Electric Three Phase, Vertical Separator High Pressure Pneumatic Three Phase, Vertical Separator Low Pressure Electric Two Phase, Vertical Separator Low Pressure Mechanical Two Phase. Glycol is hydroscopic, meaning it attracts water to itself. Excessively high circulation rates will increase glycol losses. It can also prevent inadequate glycol-gas contact in the absorber and increase pump maintenance problems. The proper gas and glycol flow rates should be established for good mixing. To operate a glycol unit, a vapor stream is drawn from and returned to the deethanizer after it is dehydrated. This method is used with an over/under design style glycol regeneration unit. The gas then flows to the fuel gas scrubber and the lean glycol flows through a filter into the reboiler. In all cases, the glycol would need replaced and the system should be steam-cleaned. Here are some causes of excessive glycol consumption. This will increase the efficiency of the reboiler so that it does not have to expend more energy to heat the glycol to the optimal temperature for water removal. Even though it has a premium Page . A demist pad, with the wrong thickness, composition or location in the absorber, can also increase glycol losses. As a general rule, a glycol dehydration system (contact type) can lose about 1 lb of glycol or 0.1 gallons of glycol per mmscf of gas. Depending on what type of service as well as environmental concerns and operational issues. Since the petrochemical industry is not on the top priority list for hydrocarbon feedstocks, you are very wise to seek ways to conserve glycol consumption. Things to check: 1. Most glycol pumps do not have an adequate circulation rate to help much anyway. It would be very uncommon to get O2 into the dehydration system; not unheard of, just uncommon. What can we do to conserve glycol consumption in our plants? In very cold weather, the free water in the dump line on the scrubber can freeze. The gaseous hydrocarbons can be recovered and used as fuel for the reboiler. Sludge collects throughout the glycol system and the new glycol will quickly absorb the sludge if it is not removed by cleaning. At atmospheric pressure and a maximum reboiler temperature of 204 C [400 F] the highest glycol concentration of lean TEG that can be achieved is roughly 99 mass percent. Preheating the glycol also extends the time that the glycol is at this optimal temperature inside the reboiler, resulting in greater distillation and purity levels. Glycol or other inhibitors are recommended for most process cooling applications even if the fluid temperature doesnt reach temperatures near freezing. It should be located downstream of the sock filter, if one is used. The blanket gas is normally piped to the regular vent connection on the top of the accumulator. This will allow the lean glycol to start cooling quickly. Jerry Martin serves as Kimray's Senior Director of Sales. They are the most widely used. Yes. Yes. This means the chiller with a 10 ton capacity for chilling water will have a capacity between 8 tons and 9.3 tons with 40% PG. Yes, but not as efficiently as a solid filter. It is usually not necessary to hook up a separator vent on the accumulator. What can we do to improve the situation? They are usually referred to by the names of their original patent holders, such as Drizo, Coldfinger and so forth. They are very expensive and tend to break down in the reboiler, thus becoming another foam promoter. boric acid and propylene glycol for termite control Previous boric acid and propylene glycol for termite control He provides product and applications training for the Kimrays sales team and customers. If you dont know what they should be at each phase, you wont be able to identify potential clues that will help you diagnose the problem. When things didnt clear up as easily as Id hoped, I had no idea if the conditions existed when I got there, or if I created them with my tinkering. What happens to the glycol system if poor filtration is maintained? Any hydrocarbons that make it over to the re-boiler from the tower flash quickly in the still and carry through to the next place they can cool and condense. I believe your glycol temperature may be a little bit low to begin with. This scrubber is used to remove liquids from incoming gas stream. If you do not isolate the tower then upstream feed gas will continue to flow while trying to blow down the tower. If you operate a glycol dehydration system, short of something spewing, leaking or catching on fire, the most common and troublesome problems come in the form of a symptom that you have to find a cause for. Normally the glycol unit manufacturer provides a stripping gas chart in the instructional manual when stripping gas is used. "The upstream gas directed to the . Three gallons of glycol for every pound of water to be removed should be circulated. Other glycols may be acceptable. Triethylene Glycol is used as a liquid desiccant to remove the water from natural gas. Another condensation method is to use an internal reflux coil in the top of the still column. It should have provisions for back flushing with water to remove loose dust. Why is the condenser temperature in the top of the still column important? The Kimray Chronicleis your source for news within the Kimray community. Ideally, you want your glycol to be 98% or higher in purity. The basic operation of both systems are similar however the choosing which application better suites your process is subject to variable such as operating temperature. Glycol dehydration is a chemical engineering unit process that uses a liquid desiccant, usually a glycol, for the removal of water from natural gas and natural gas liquids (NGL). How much neutralizer should be used to raise the glycol pH? (More plausible). . By inspecting the firetube or by shutting off the burner on the reboiler at night and looking down the firebox. You will need to close the upstream feed valve to isolate the tower before depressurizing the tower. In this case, the tower packing is used to allow thorough mixing of the rich glycol and the hot vapors coming from the reboiler. The type and thickness of the mist pad should be carefully studied to minimize glycol losses. Where should the carbon purifier be located in the circulating stream? Glycol boiling point is 546F, but the degradation temperature of glycol is 404F, so do not operate the reboiler over that temperature. If these salt removal systems are not available, what should we do? How frequently should the filter elements be changed? Insulation can help when light hydrocarbons collect on the vessel walls due to excessive condensation. Saturated steam can be put down through the bed to help remove the dust. At any rate, the only way I know of to prevent this is to put a control valve on the outlet of the tower, effectively becoming a back-pressure valve. Therefore, the filter should be placed downstream from the hydrocarbon separator. If too high, the glycol vaporization losses with the water vapor will increase. Moreover, the injection rate for hydrate . Our gas-glycol pump maintenance costs have been very high. GLY-TECH's course provides a proper countermeasure that can prevent this occurrence. Conversely, glycol pumps are very temperature sensitive. If the pressure drop across the absorber suddenly rises about 20 lbs and the glycol removed from the system does not foam, the foam problem is usually a mechanical type. What type of glycol is best? Next, over-circulating the glycol may also be a cause check your circulation rates to make sure you are not over-taxing the system. Higher glycol purity levels mean you can circulate less glycol through the dehydration system to remove the same amount of water. The demethanizer operates at an overhead temperature of about 108 C. (162 F.) at 16 bara (232 psia). This could especially be true if the downcomer is a packed column to aid in gas stripping. Trayed towers are more vulnerable than packed towers. What should be the maximum reboiler temperature to avoid glycol decomposition? That is usually accomplished by installing a globe valve on the inlet to the coils and a bypass between the inlet and outlet with another globe valve. That depends upon the vessel design. The downcomer between the reboiler and accumulator may be plugged. A high-pressure blow-case pot should do the trick. The Glycol Dehydration Unit is a reliable, efficient system for removing water from natural gas well streams in order to meet typical pipeline and process specifications. Could it be the reason why massive glycol carried over? When the gas and colder glycol co-mingle in the absorber, the gas will be cooled and this can create hydrocarbon condensation. A triethylene glycol (TEG) gas dehydration system is a setup used to eliminate water vapor from newly recovered natural gas. But pumping TEG against the gas stream at the wellsite is just the beginning. The process of removing water from a substance is called Dehydration Process. The regeneration system typically includes a glycol flash tank (gas . Peter Usually, the level on the fire tube/element side of the re-boiler is maintained by a weir or down-comer. Good morning, please we are loosing too much glycol in out glycol dehydration system. The troubleshooting process can be long and tedious. Varian Linear Accelerator Cooling: Four American Chillers for CA Cancer Center. Full stream or side stream filters can work well, if designed and operated properly. What can be done to combat paraffin problems in a glycol unit? Pressure gauges should be installed on all vessels, including the reboiler, and on. Goes tank to tank no issues, but as soon as we close off the valve to direct the flow up, the pump slows down and will stop. To speak with an expert about your gas dehy system challenges, contact your local Kimray store or authorized distributor. The dry gas passes through a gas/ glycol heat exchangers . At constant gas volumes, the gas velocity through the absorber increases as the pressure is lowered. The glycol dehydration system regenerator operating temperature is maintained by: A - Heat supplied by a bottom reboiler B - A closed water-cooled coil C - Heat supplied by an overhead reboiler D - None of the above A Glycol dehydration systems that do not have glycol flash tanks are more prone to corrosion due to: The glycol circulation rate should be optimized to minimize glycol losses leaving with the sales gas. Either salt removal method can be portable. . One company, after suffering for years with glycol losses of several gallons per mmscf, redesigned and relocated the demist pad in the absorber and cut the glycol consumption back to a reasonable level. Since the pumps lubricates itself with the glycol, they are not able to properly lubricate at the higher temperature causing the pumps to fail prematurely. The first question I would have is; do you have reflux coils in the column? Vessels with bubble cap trays. Glycol with a higher pH tends to saponify any hydrocarbons present to create foaming problems. When this condition exists and glycol is pumped into the absorber, the liquid has difficulty flowing down through the downcomers. ab Inlet gas temperature [C] 30 Inlet gas pressure [kPa] 3000 Inlet gas flow [kmol/h] 501.1 I have obtained the latest Glycol sample lab analysis report . If the dehy worked properly before and started losing glycol all at once, I would tend toward foaming. The rich glycol (wet with absorbed glycol) collects in the hat tray at the bottom of the tower and flows to the power side of the glycol pump. No. The true glycol temperature in the reboiler may vary as much as 150F from the recorded temperature on the dial gauge. The temperature and specific gravity factors for packed glycol contactors are contained in Tables 2A and 2B respectively. If the vessel has no provision for back flushing with water to remove loose dirt, what can be done to remove the dust? You also need to know how each phase issupposed to work and how it is working in comparison. Check the specs of your pump to make sure you are working in operating limits. ingestion of ethylene glycol (antifreeze) and in cats 12-24 hours after ingestion of ethylene glycol; lack of production of urine (known as "anuria") is seen 72-96 hours after ingestion of ethylene glycol if untreated May note severely low body temperature (known as "severe hypothermia") The pump may have stopped circulating the glycol. The meter run does have a check valve to prevent backflow from the pipeline, but if the meter is some distance away then you have to blow the sales line down, which could be a large amount of gas. BENEFITS OF DEHYDRATION UNITS. If you have a shell-in-tube or tube bundle exchanger (Hairpin style), a couple things could be going on: First, your exchangers could be partially plugged causing the rich and/or lean glycol to reside too long. The first place I would look is at the gas analysis. It is more common though that there is a handful of units in a gas treatment facility and there are probably hundreds of facilities like that in the US. It is important the glycol unit be thoroughly cleaned to ensure the contaminates have been removed from the system. Glycol is saved by replacing tower packing. This first time Ive operated a reboiler with a electrical heating source and it is topped out. Normally, a good element made from cloth fabrics is best. The rich glycol could no longer penetrate through the plugged still tower packing, so it was flowing out of the still column vent piping rather than to the reboiler. In either case, flow is adjusted so there is a smaller amount of cool liquid flowing through the reflux coils. A glycol dehydration package can incorporate the following depending on your requirements: High-efficiency inlet oil separators to remove oil from upstream compression. The glycol flows into the accumulator and the water-laden stripping gas passes out through the still column. It is important to understand efficiency you can expect from a properly functioning regen skid. It is moderated slightly by allowing for gas heating from the small glycol flow. Glycol samples only need to be drawn initially unless a significant problem is found during analysis. The MEG and the natural gas are then piped back, as a mixture, towards the mainland. If a vent line is tied into the top of the still column, some of the condensed water can be collected and analyzed to see how much glycol it contains. The TEG purity is about 99 % wt. Flowing more gas through the absorber than it is designed to handle will give a higher vapor velocity and a higher pressure drop. A safe pH for glycol is 7.3. Also, there should be a valve on the downstream side of the tower, though there is not always. A small amount of sweet blanket gas can be passed through the accumulator to keep oxygen out. Try increasing the glycol temp to 196c. This could be the result of compressor oil or amine getting into the system or possibly the tower getting flooded with hydrocarbons. The glycol should be brought into the absorber through a good liquid distributor to prevent channeling. . If the oxygen is showing up further downstream, such as at the sales line meter, The very first place I would check is a VRU pulling directly from tanks rather than a vapor recovery tower. However, since most deposits in the glycol are organic, acid cleaning is not very effective. Since the reboiler temperature is limited to 400F or less to prevent thermal degradation of the glycol, almost all of the enhanced systems center on lowering the partial pressure of water in the system to increase stripping. Purchase Gas Dehydration Field Manual - 1st Edition. Im not sure about the decomposed glycol showing up downstream, other than some solids are making it through your filters. Telemark University College . Wet natural gas streams at low temperatures are at risk of forming . Paraffin usually carries in the gas stream in the vapor phase. It may be necessary to see that the blanket gas valve, piping, and flow control orifice are open to pass gas. Then the gas rate should slowly be increased to the desired gas flow rate. Maximum contact between the glycol and carbon is desired. How can I tell if excess glycol is leaving the top of the still column? Normally, ethane and propane, extracted in a gasoline plant, are used as the feedstocks for manufacturing glycols. The rich glycol returning from the tower, even after passing through the reflux coils, is only between 70 and 90 degrees Fahrenheit. If necessary, you can go as high as 201c but it is better to aim for 196 if that will take care of the problem. A non-horizontal position can cause a firetube burnout. If you operate a glycol dehydration system, short of something spewing, leaking or catching on fire, the most common and troublesome problems come in the form of a symptom that you have to find a cause for. Is equipment clean? Learn more about filtration. A surplus reboiler can even be used, if properly operated. Therefore, a portion or all of the rich glycol should bypass the reflux coil. If the 390F reboiler temperature is accurate, then look for other sources of water entry in the lean glycol. A bright, red glowing hot spot will be visible at spots on the tube where deposits have collected. Rapid surges of gas through the absorber may cause sufficient velocity increase through the trays to break the liquid seals, or it can lift the glycol off the trays, flood the mist extractors and increase glycol losses. A poorly built purifier can create many problems. Yes. what would be some leading causes of low temperature in the still column ( 170-190 degrees)? going down around 184c. If the incoming gas and the circulating glycol are kept clean, the filter elements will last a long time. Sometimes a good spray nozzle to spray the glycol over the tower packing is very beneficial. The saturation coverage on surface Ti rows is determined to be 0.43 monolayer (ML), slightly less than one ethylene glycol per two Ti sites. DEHYDRATION DESIGN CONSIDERATIONS Lean Glycol Concentration Basis for dry gas water content Typically 98.8 - 99.95 wt% TEG purity Gas/Liquid Contact TEG Circulation rate Trays or packing in the contactor Reboiler Temperature Vapourize water content from rich TEG Regenerated lean TEG concentration Avoid glycol degradation Stripping Gas Chillers are used in many applications.