Reducing Hydrate Formation and Pipeline Corrosion with Methanol Injection Pumps - Case Study

Methanol Injection Pumps This week we look at a client who was looking to reduce hydrate formation and pipeline corrosion with methanol. But before we do, what is Methanol and how does it relate to hydrate formation and pipe corrosion? Methanol, Hydrate Formation and Pipeline Corrosion Methanol is a simple alcohol produced during the gasification process utilized in various offshore applications. It has the long-term potential as an alternative fuel, as it is often cheaper to produce than other alternative fuels such as Hydrogen, Liquid Natural Gas (LNG) and Ethanol, and can be produced from a number of renewable sources such as Biomass and Landfill Gas, as well being recoverable from Industrial emissions. Methanol is also used in marine Vessels as a way of lowering emissions, treating them to decrease the amount of Nitrous Oxide (NOx) and soot produced. It can also be mixed with fuel to increase the octane rating by up to 3 percentage points when 10% is added. Although less flammable than diesel, and having around half the energy density too, it still has the potential to be used in a range of applications. One of its main uses in the Oil and Gas Industry is in the prevention of corrosion in pipelines where hydrate formation occurs at low temperatures. Hydrate formations occur when water and natural gases encounter a combination of low temperatures and high pressures, which if not addressed can lead to the corrosion of pipelines, the formation of slurries and crystallisation which can clog pipework and process equipment such as valves and process instrumentation. The Clients’ Project Our client was installing a new injection package to an unmanned offshore platform located in the North Sea. As part of this package, they wanted to protect the existing pipework and ensure that the pipeline was shielded from corrosion and kept well maintained. The pipeline was operating at a pressure of over 250 Bar, and they required an ATEX dosing pump to inject Methanol into the system at over 250 Bar, which could be controlled remotely to alter output flow. So why were they injecting methanol…? Methanol Reduces Hydrate Formation Methanol is used to erode naturally occurring deposits in wells, as it can melt hydrates and prevents the formation of crystalline structures. In principle it works similar to when grit is applied to road surfaces in winter, lowering the freezing point of surface water. Methanol lowers the temperature in which hydrates are formed, meaning they require a lower temperature in order to be produced, and through its addition within a process prevents formation of such deposits. The Solution, Our Pumps We specified and selected three Tekdos Plunger Pumps built in Stainless Steel AISI 316, with chemically resistant PTFE Diaphragms. The plunger dosing pumps were built with all wetted parts in AISI316, and supplied with motors suitable for inverter operation to enable easy control over dosing flow rate. The 3 units were delivered in 4-5 Weeks. Our range of Tekdos Plunger pumps are designed according to API675 standards, matching the accuracy required for continuous operation of +-1%, as well as the build requirements of API675. API675 Standard The American Petroleum Institute (API) has a set of minimum standards which pumps are required to meet in order to comply with an API Standard. API Standards are outlined for different technologies of pumps with API675 being used for Positive Displacement Pumps. Other API Standards include API674 for reciprocating positive displacement pumps, and API610 for Centrifugal Pumps. When an API standard is revised or modified in any way it is labelled with an edition and month of modification e.g., API675, 3rd Edition, Nov 2012. Although a unit may state it complies with a specific standard, there are often deviations listed as to which points in the standard units can comply with, as well as others which they deviate from as some of the criteria outlined in API Standards can be optional. If you have a high pressure dosing or metering application and are unsure of which pump to use, speak to us to see how we can help.

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