TOCHAL has accumulated considerable expertise in the application of its own technology as well as technology from other internationally known licensors. The wide range of technologies available to TOCHAL enables the company to offer an open policy on technology selection issues. In addition, the collaboration with first class technology providers gives TOCHAL an outstanding level of expertise and knowledge of some of the best known processes and technologies.
TOCHAL is in a position to recommend the most suitable technology for client's specific requirements and to implement projects based on its proprietary technology, know-how or using third party processes or indeed based on a combination of both.
It is TOCHAL’s policy to provide clients with plants, equipment and services which, in terms of performance, safety, reliability, low environmental impact, ease of operation and maintenance conform to both the contractual and the relevant regulatory requirements in a cost effective manner. This is achieved by carrying out all our corporate activities (i.e., engineering, procurement, construction) in accordance with our HSE-Q (Health, Safety, Environment, Quality)
We supply following skid mounted process packages:
TEG Dehydration Package
MEG Regeneration Package
MEG Reclaiming Package
TEG Dehydration Package
Gas dehydration with glycol is a well-established process which allows continuous plant operation enabling simpler and more economic plant to be utilized than for many other systems such as molecular sieves and refrigeration plants.
In the evolution of the glycol dehydration process, Tri-Ethylene Glycol (TEG) has become the preferred agent since it provides good dehydration combined with minimal loss from vaporization and degradation.
The process can be used between a temperature range of 5 - 70°C and virtually any pressure. Where large quantities of water are being removed the heat released during absorption needs to be taken into consideration in the system design.
The wet gas and condensate/water liquid mixture flows to the inlet separator where the free and entrained liquids are removed to minimize carryover into TEG contactor. The wet gas is subsequently brought into intimate counter-current contact with Tri-Ethylene Glycol on structured packing in the mass transfer section of the TEG contactor to achieve the desired degree of dehydration. The performance of the Glycol Contactor, in relation to the process requirements is determined by carefully selecting the following parameters:
Height of Packing
Packing Design
Tri-Ethylene Glycol Concentration
Tri-Ethylene Glycol Circulation Rate
After leaving the top of the packing, the gas passes through a wire mesh demisting device, which serves to reduce glycol entrainment losses to a negligible level. The dry gas then leaves the contactor.
Water-rich glycol from the bottom of the contactor column is sent under level control to the Skid-mounted Regeneration Package, where it is passed through a coil in the top of still column. This provides reflux cooling in the still and preheats the rich TEG (temperature is increased by approximately 10°C) prior to flashing in glycol flash drum to remove dissolved and entrained gases.
Glycol then falls into the Glycol Reboiler, which operates at 204°C and is regenerated to a purity of 99.7 wt % with the aid of external stripping column which uses a portion of the overhead dry gas from the contactor column as a stripping medium. The stripping column is capable to increase the purity of the Glycol to 99.9%.
The regenerated Lean Glycol then flows into the Surge drum. The Surge Drum provides the glycol circulation system with sufficient volume to enable a steady flow of glycol to the contactor, and has a sufficient capacity to recover all TEG filling the regeneration unit in normal operation. The Glycol Reboiler is heated by a steam tube bundle. Required high pressure steam will be supplied in battery limit and produced high pressure condensate will be received in high pressure steam condensate surge drum via level controlled. The high pressure condensate after receiving and accumulating in surge drum will be routed and boosted by two centrifugal pumps.
MEG Regeneration Package
MEG is used to prevent hydrate formation in natural gas stream. This process is a well-established process, which allows continuous plant operation enabling simpler and more economic plant to be utilized than for many other systems.
MEG has become the preferred agent since it provides good hydrate inhibitor combined with minimal loss from vaporization and degradation.
The process can be used between a temperature range of 5 - 70°C and virtually any pressure. Where large quantities of water are being removed, the heat released during absorption needs to be taken into consideration in the system design.
Rich MEG will be sent to rich glycol flash drum to remove dissolved and entrained gases and hydrocarbon liquids. The flash drum operates at approx. 4 barg or sufficient head to reach to the Still column and is designed for three-phases of MEG, hydrocarbon condensate, and gas. The dissolved and entrained gases are vented under split range pressure control and the liquid phases separate into distinct glycol and light hydrocarbon layers. Hydrocarbon liquids are skimmed off. The MEG flows out from the bottom of the vessel.
Harmful solids 10 micron and over are removed by filters which could otherwise cause foaming, fouling of heat transfer surfaces. MEG from the rich MEG filter system flows through the Rich/Lean Glycol heat Exchanger where it is preheated by heat exchanger with hot regenerated lean MEG. The pre-heated rich glycol from is sent into the packed section of the MEG still Column.
MEG then falls into the MEG Reboiler. The MEG is regenerated to a purity of 70 wt%; the over head vapor will flow to over head condenser which will cool the over head vapor.
The Surge Drum integrated with reboiler provides sufficient volume to enable a steady flow of MEG to the pump, and has a sufficient capacity to recover all MEG filling the still column and associated piping in normal operation.
It needs to be considered that Due to presence of the salt in MEG the Reboiler, steam coil located at least 6" above the bottom of the reboiler, also a provision has been made for ease of the removal of steam coil. The reflux accumulated can be integrated with the still column, which will reduce installation and initial investment cost.
The expected salts in the formation water will need to be removed before it reaches to saturation level. Otherwise, salt drop out in the system causing blockage and possible corrosion.
MEG Reclaiming Package
Water miscible liquids such as glycols are used in oil and gas production but can become contaminated with dissolved and/or suspended solid matter. Rather than discarding the contaminated liquid, it is generally preferable to remove the solid matter so as to regenerate and reuse the liquid.
At many locations worldwide, dissolved salts and other similar contaminating substances are separated from the process liquid (e.g. glycol) by vacuum flash vaporization processes at oil and gas production facilities, the fluids that come from the oil and gas wells may contain substantial amounts of formation water. This, in turn, contains salts and other unwanted substances. At these facilities, mono-ethylene glycol is injected into hydrocarbon flow lines to prevent the formation of hydrates that can plug pipelines. The water then mixes with the glycol to form a dilute aqueous glycol solution. When the crude hydrocarbons are collected at the oil and gas production plant, the dilute aqueous glycol solution is separated from the hydrocarbon fluids. It is then re-concentrated by boiling off excess water, and transported back upstream to be re-injected into the flow lines.
In this way, the glycol is reused many times. However, in the absence of treatment, it accumulates unwanted non-volatile solid matter with each recycling round.
The salts and other solid matter can build-up until the level of contamination in the glycol causes increased corrosion, rapid thermal degradation of the glycol, unwanted precipitation of solid matter, fouling of heat transfer equipment and other serious, costly, operational problems.
Chlorides, oxides, sulfates, bicarbonates, and carbonates of sodium, potassium, calcium, magnesium, iron, barium, and strontium are examples of inorganic contaminants. Sodium chloride is generally the most prevalent inorganic contaminant. A major source of the salts and other solid matter is the formation water that flows with the hydrocarbon fluids out of the oil and gas production wells. Another source can be the brines and other completion fluids that are injected into the flow lines10 during or after exploration to prepare for initial production, or as a result of well maintenance activities. Other potential sources include the products of corrosion of the flow lines and the chemicals injected into the flow lines to control corrosion. These nonvolatile contaminants must be removed to maintain the quality of the glycol and efficient operations when the glycol is regenerated and reused.
In facilities that treat glycol using a flash vaporization process, a feed stream comprising an aqueous glycol solution containing contaminants such as dissolved salts is caused to boil rapidly upon mixing with a heated recycle fluid within or in proximity to a flash separation vessel. The reclaimed glycol vapors are condensed in a vapor condenser and then pumped back to the lean glycol side of glycol regeneration.