In the oil and gas industry you come across diaphragm pumps within a wide performance range from exploration over processing up to transportation to the consumer.
A great variety of applications is included in the term ‘Chemical Injection’. In all production steps, the operators have to add a variety of different additives in order to prevent undesirable conditions in processes, pipelines, heat exchangers and other components. With partially complex mixtures of organic and inorganic components, very specific effects are attained. The substances injected protect against corrosion, prevent mineral scaling, paraffin and asphaltene precipitation, improve the oil/water separation, support the coagulation of solid particles and have numerous other tasks depending on the oil and gas composition.
Apart from their use for precise supply and injection of such chemicals, the application range of diaphragm pumps in the oil and gas industry has considerably expanded for the last years with regard to the fluids as well as the flow rates. Additionally, they deliver extremely difficult hydrocarbon condensates and slurries loaded with a high portion of toxic components, they inhibit the formation of hydrates by injection of alcohols, they are used for pumping glycols for gas drying, and they safely and very economically boost large volumes of sour gas and CO2 to the injection pressures required for the transportation and storage in geological formations.
Widely differing requirements are placed on the pumps mainly depending on the physical and chemical properties of the fluids, the specific application and, to some extent, on the strongly varying process conditions. Precise monitoring prevents the necessity for excess metering and hence reduces consumption, costs and potential risks to the environment. Uncritical fluids are often conveyed by reciprocating plunger pumps, however, many of the chemicals used in the oil and gas industry are difficult to handle, not just because they are corrosive, have high vapour pressures or extremely low lubricating properties, but due to the fact that a great number of them is unhealthy and partly even extremely toxic or environmentally harmful.
The only convincing solution to safely prevent the release of such critical chemicals into the atmosphere is hermetically tight handling. For leakage-free pumping of fluids all dynamic seals (mechanical seals, packings etc.) must be avoided. This, among others, has led to canned motors and magnetic drives for centrifugal pumps and to diaphragms for reciprocating positive displacement pumps.
Due to this fact, leakage-free diaphragm pumps have found a wide application range in the oil and gas industry, too. This technology is suitable even for the most difficult and critical fluids, which must be injected at high pressures during production, processing and transportation.
Apart from leak-tightness, diaphragm pumps provide all advantages of reciprocating plunger pumps, which are appreciated by operators.
- Pressure firm characteristics (flow is dependent on pressure to a small extent only).
- Linear flow rate adjustment via stroke length and stroke frequency.
- High accuracy and reproducibility.
- High volumetric and mechanical efficiency.
Diaphragm pumps have proven their operational safety and reliability in innumerable applications for the conveyance of fluids with most different physical and chemical properties.
Therefore, they are found also in the main process steps of the following industries:
- chemical industry;
- process technology;
- nuclear technology;
- pharmaceutical industry, gene- and biotechnology; and
- food industry.
Diaphragm pumps are mainly used for low to medium flows at medium to high pressures. They are predominantly known for applications with small flows. In the last 20 years however, process diaphragm pumps with hydraulic powers of up to nearly 1,000kW have been developed. The typical application limits of plastics diaphragms are pressures of up to 400 bar at temperatures of -50°C to 150°C.
Special designs are used in processes up to 800 bar. Pumps with metal diaphragms can reach pressures up to 1,200 bar at temperatures up to 250°C.
Chemical Injection in the Oil and Gas Industry
This includes all injection processes for which special chemicals are used, which facilitate and improve oil and gas production, processing and transportation. Nowadays the oil and gas industry cannot work economically without the use of large amounts of such chemicals. Usually, chemical injection is understood as precise injection of additives against high pressure.
In order to achieve specific effects during production and processing, diaphragm pumps are used for the injection of the following active substances.
Newly developed deep-sea oil and gas fields, as well as fields in remote locations with extreme climatic conditions demand more and more of these application-specific chemicals. The extreme effort required by production plants in water depths of 3,000–4,000 metres, as well as the increased vulnerability to failures and the raised potential for damages, necessitate a rigorous quality process for the chemicals applied and for the injection equipment used.
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