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|Are you looking for a chemical injection flowmeter? Contact the specialists! Litre Meter have tailor-made solutions for measuring: methanol, demulsifier, corrosion inhibitor, scale inhibitor, wax inhibitor, biocide and oxygen scavenger. Low flow rates and high pressures both subsea and topsides. Proven over many years. Installed throughout the world.
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Chemical injection is the process designed to assist in the production of oil. Various chemicals are injection into the crude oil to provide a degree of protection. For example a scale inhibitor will prevent the build-up of scale on the pipes and fittings used to transport the oil on its journey to the refinery. Flowmeters are used to monitor and control the amount of chemicals added to the crude oil. Biocide prevents the build-up of organisms in the pipe. Corrosion inhibitor is the most popular additive to be measured. There are various types depending on the type of main liquid. Pour point depressant is added to reduce the pour point thereby making the oil easier to flow through the main pipelines. Most of the chemicals added tend to be at low flow rates of the order of 0.01 to 90 litres per hour (typical LF15 flow rate range). LDHI or Low Dosage Hydrate Inhibitor has the highest injection rate sometimes up to 17,000 litres per hour (V270). It is designed to inhibit water based mixtures which would otherwise have a tendency to freeze. Methanol is often used with the same effect. More exotic chemicals are used for similar purposes all with the intention of reducing cost on the way to the refinery. It is a little known fact that flowmeters are used to measure these chemicals which contribute 30% of the cost of running an offshore platform. Control systems are often manually set from the flowmeter displayed value (either locally or from the SCADA system) and there is a trend towards automation of this process using control valves such as SkoFlo. A typically turndown ratio of 500:1 is measurable with the VFF positive displacement flowmeters (eg LF05). Often the systems are relatively slow dynamically and need only slight adjustments from day-to-day which is why manual control is still so popular. It is important that the flow measurement system for the chemicals is able to cope with the pulsing nature of the pumps used and also with the high pressures that are encountered. These can be up to 1035bar/15000psi/15ksi in modern systems injecting subsea. Topsides injection is at lower pressures typically from 200 to 1000 psi. There is also a trend towards measuring the chemicals subsea i.e. underwater rather than when the crude oil reaches the surface. Not only does the flowmeter have to work at high internal pressures of over 10,000 psi, 690bar but also with external pressures up to 345bar/5000psi.
Materials of construction:
Most chemicals measured in chemical injection applications are suitable for 316 stainless steel. The main exception is Sodium Hypochlorite where most manufacturers will switch to Titanium. On the elastomer selection FPM is normally acceptable with the notable exception of methanol and maybe LDHI. FFKM is sometimes specified when, during the life of the platform, the actual chemical being measured cannot be guaranteed or when the vendor or fluid is not yet known.
A corrosion inhibitor is a chemical additive used in acid treatments to protect steel & iron wellbore & treatment equipment from a corrosive fluid such as crude oil. Generally they are added to a treatment fluid and are formulated to protect metal components that will be in contact with the aggressive fluid. The protection is designed to remain effective under expected pressure and temperature conditions. The corrosion inhibitor is measured by a flow meter so that a control system can regulate the amount of inhibitor to match the crude oil throughput. In some treatments the inhibitor is added and is adsorbed on to the pipe surface to form a protective film. This reduces the destructive reaction of aid with metals. The inhibitor does not completely stop the corrosion reaction but eliminates over 99% of the metal loss that would occur if the corrosion inhibitor were not present. Some corrosion inhibitors are efficient in hydrogen sulphide environments, operate on steels such as high-strength chrome steel, duplex alloys and can be used at elevated temperatures.
All measured with Litre Meter VFF flowmeters – positive displacement, rotary piston. This flowmeter series can accurately measure pulsing flows, accurately measure at high pressures – above 1000 bar if required, accurately measure a wide range of viscosities, provide years of reliable service in tough environments.