Injection of corrosion inhibitor with LEWA pumps and packages

High oil and gas prices are favoring the utilization of beds with lower oil and gas yields, as well as the recovery of fields with small usable portions or high water/CO2/H2 S portions.

The injection of corrosion inhibitor is indispensable for efficient conveyance.

The anti-corrosion agents used to bind the oxygen or form a protective layer on the inner walls of the pipes and thus prevent corrosion.

Solutions for the injection of corrosion inhibitor

The advantages of LEWA diaphragm metering pumps and packages in the injection of corrosion inhibitor:

  • Hermetically sealed LEWA diaphragm pumps are ideal due to the high pressures and the fact that some inhibitors are carcinogenic (e.g. chromate/ hydrazine).
  • The use of special, corrosion-resistant materials is possible (Hastelloy valve seats, ceramic oxide valve balls)
  • Designed for extreme temperatures
  • A space saving and more economical alternative to so-called flow dividers is the division of corrosion inhibitors with an easily maintained multiple metering pump. This has a replacement pump head, which can be turned on quickly and reliably by valve actuation in each injection line.
  • For possible slug metering, we recommend the installation of metering pumps or systems with 2/6 pole motors. This allows slug and normal metering to be operated cost effectively

Background of the injection of corrosion inhibitors

Process description

A distinction is made between anodic and cathodic corrosion inhibitors.

Cathodic corrosion inhibitors are mainly used for oil and gas production.

In the offshore industry, production sites are being driven into increasingly deeper water. This increases the discharge pressure. While 160-250 bar are sufficient onshore, the offshore pressure is often above 900 bar. The flow rate is normally around 50 l/h. Injection is continuous.

Possible chemical reactions must be detected and accounted for:

The components of crude oil cause corrosion and scale deposits. The injection of corrosion and scale deposit inhibitors helps. Limited success is achieved by using a combination of these additives, since both chemicals neutralize and are rendered inactive.

It should therefore be checked whether a reduction of the injection volume of the corrosion inhibitor could lead to a residual acidic content in the crude oil, which would destroy the scale deposits anyway.

Central distribution of corrosion inhibitors:

If several injection points are supplied with corrosion inhibitors at a central location, the use of flow dividers must be considered. This requires only the installation of one large pump to provide the entire flow and a multiple distributor system.

The flow is distributed via small valves and pressure compensating devices and delivered to the various injection points. However, the space requirements only appear to be better, since in actuality each injection point requires a separate control system. Moreover, the injected fluid must be very pure, since otherwise the pressure compensation valves, which have very tight tolerances, can get stuck.

Highly pure fluids and very small components are very sensible to fluctuations in viscosity and pressure.

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