1.1 Basic Theory
A submersible pump, also known as a submerged electric pump, is an integrated mechanical device combining a centrifugal pump and an electric motor for the purpose of transporting fluids. Looking back over the past 300 years, from the Dutchman Daniel Bernoulli proposing the Bernoulli equation in 1738 and publishing "Hydrodynamique" (Fluid Mechanics) to 17 years later when the Swiss mathematician Leonhard Euler published "General Principles on the Movement of Fluids" and proposed the basic equations of ideal fluids and continuity equations, this laid the theoretical foundation for the design of centrifugal pumps.
The centrifugal pump was first proposed by the French engineer Papin. In 1689, he invented a machine that could be regarded as the prototype of the centrifugal pump. In 1705, he manufactured the first pump suitable for lifting liquids. This pump adopted a multi-blade impeller and a conical pump casing.
The first centrifugal pump in modern times, which was also a turning point marking the mass production and commercialization of centrifugal pumps, is currently commonly referred to as the Massachusetts pump. Its designer was an American, and it began mass production in Massachusetts, USA in 1818. The split-case, double-suction impeller, radial straight blades, and conical casing centrifugal pump with a split-case design is the "ancestor" of modern split-case centrifugal pumps.
1.2 The submersible pump was introduced.
In the late 19th century and early 20th century, during the heyday of steam turbines, reciprocating pumps almost dominated the pump application market. Until the end of the 19th century, the advent of electric motors, especially the practical high-speed electric motor developed by the German Siemens (in 1866), and the American Gordon who manufactured a two-phase giant generator with an output power of 447KW, a height of 3 meters, and a weight of 22 tons (in 1882); and the two-phase alternating current generator of Tesla in the United States (in 1896) began to operate at Niagara Power Plant, delivering 3750KW of alternating current at 5000V all the way to Buffalo City, 40 kilometers away, enabled centrifugal pumps to obtain an ideal power source. Especially the theoretical research and practical work of many scholars in the UK such as Reynolds and in Germany such as Pfleiderer, the efficiency of centrifugal pumps was greatly improved, and their superiority was fully exerted. Centrifugal pumps then achieved widespread development and gradually replaced centrifugal pumps, becoming a pump with a wide range of applications and the largest production volume.
Submersible pumps are a type of centrifugal pumps, commonly referred to as "water pumps" in common parlance. With the advent of electric motors, centrifugal pumps have seen extensive development. However, the emergence of submersible pumps was relatively later. In 1904, to meet certain special situations such as the need to pump water from wells, the engineers of the Byron Jackson Company in the United States designed and manufactured the world's first dry (inflatable) submersible pump with the pump and motor connected horizontally and capable of being used underwater, replacing deep well pumps. This is also recognized as the first successful submersible motor pump and is considered the "ancestor" of modern submersible pumps; in 1928, the Byron Jackson Company in the United States invented a submersible pump with the pump and motor connected vertically, which was an early well-used submersible pump. The motor structures are of water-filled type, dry type, and oil-filled type. Early submersible pumps were mainly used in water supply industries, subway drainage, water irrigation stations, and mining industries, etc.
In the 1930s, Hayward Tyler from the UK, KSB Company and RITZ from Germany, Flygt from Sweden, BJ Company from the US, TRW Company from the US, Hitachi from Japan, and other companies successively began to produce deep well submersible pumps. For instance, the deep well submersible electric pump developed by the German company Pleuger was successfully applied to drainage and water lifting of daily drinking water in subway systems. Submersible pumps attracted the attention of many engineering experts and technicians. The products of Pleuger Company were widely used in many projects such as the Moscow subway, France, Mexico and Argentina's water irrigation stations.
In the late 1940s, submersible water pumps for both water supply and drainage, which combined the functions of a motor and a pump, began to be produced one after another.
For instance, in 1948, the Swedish company Sterbery-Flygt was the first to manufacture the world's first small-sized operation surface submersible water pump, which fundamentally simplified the type of the pump and the structure of the submersible water pump, invented the direct connection method between the motor shaft and the pump impeller, and reduced the manufacturing cost of the submersible water pump by nearly half. It soon became the main drainage equipment in the construction industry and the mining industry. In 1956, the B series submersible sewage pump was successfully developed and promoted, which was used to convey liquids containing solid particles, suspended substances or fibrous suspended substances in industrial processes, domestic sewage, industrial wastewater, etc. It was soon widely applied in municipal, environmental protection, light industry, chemical industry, mining, metallurgy, pharmaceuticals, food and other industries, and became one of the main equipment for sewage treatment projects.
By the end of the 1960s, Germany, the United States, the United Kingdom, Finland, Russia, Japan (such as Higai, Sakukawa, Inagaki, etc.) had also begun mass production of submersible water pumps for working surfaces. Companies such as ITT in the United States, Byron Jackson Company in the United States, Goulds Company in the United States, Grundfos Company in Denmark, ABS in Germany (now under the Cardo Group in Sweden), Pleuger Company in Germany, Wilo Company in Germany, Hayward Tyler Company in the United Kingdom, Weir Company in the United Kingdom, Hitachih Company in Japan, Ebara Company in Japan, Thyssen Company in Germany, Ritz and KSB Company in Germany, etc. all produced high-performance submersible water pump products.
After nearly 120 years of continuous improvement and development, the special product of combining a pump with an electric motor, the submersible water pump, has become a major category of mechanical products and has developed into an independent "water pump" industry. It has also evolved into a comprehensive technology in the field of technology.
In recent years, due to the unique advantages of submersible pumps and the increasing awareness of submersible pumps in the market, the installation rate of submersible pumps has been continuously rising, and their application has become increasingly widespread. They have become one of the mainstream products and have a huge market demand.
Submersible Water Pumps
2.1 Types of Submersible Pumps
At present, the types of submersible water pumps include well-type submersible pumps, small-scale operation site submersible pumps (including river-type submersible pumps, engineering submersible pumps, etc.), sewage and waste water submersible pumps, mine-type submersible pumps (including mine explosion-proof type and general type), submersible screw electric pumps, axial flow submersible pumps, high-pressure submersible pumps (including mine and well-type high-pressure submersible pumps and general-purpose high-pressure submersible pumps), as well as seawater and salt field submersible pumps, etc.
Due to space limitations, this article only introduces the commonly used sewage and waste water submersible pumps in the environmental protection treatment industry and the submersible pumps for small operation areas.
2.2 Surface-mounted submersible pumps and submersible sewage pumps
The surface operation submersible pump is a type of small submersible pump (single-stage pump). Due to its easy installation and convenient operation, it is widely used in many places. It was first developed by Swedish company Sterbery-Flygt in 1948 as the "surface operation submersible pump".
The so-called sewage refers to used water. Sewage sludge submersible pumps, abbreviated as submersible sewage pumps or sewage pumps, are non-clogging pumps. In English, they are called Non clogging pumps. They are also known as high-solid-rate treatment pumps in foreign countries and are one of the main equipment in sewage treatment projects. According to the latest survey report of the German BMZ institution, approximately 80% to 85% of the world's sewage is not purified and treated. And the total annual sales volume of sewage pumps worldwide is between 5 billion and 6.5 billion euros, which is several times that of water pumps.
Submersible pumps, also known as sewage pumps, are one of the commonly used equipment in the water treatment industry. In the field of water treatment and sewage treatment technology, submersible pumps (including sewage pumps) are the most economical and technologically feasible solution to replace other traditional dry-running (land-based) pumps. Especially during maintenance and installation processes, it has unique advantages over other pumps. Due to the submersible pump design,
By installing devices such as filters and screens, it is possible to prevent large and hard solids from entering the pump's inlet. Soft solids will try to pass through these devices regardless of their size. This has extraordinary significance in the use of sewage pumps. In the face of harsh working conditions, sewage pumps can be safely applied to sewage collection, slurry pumping, rainwater pumping, land drainage, pond drainage, etc. These liquids can be classified into organic, inorganic, abrasive and fibrous types. Organic sewage solids are generally soft and often contain more or less fibrous materials. Inorganic solids are hard and often sharp, with smaller particles.
2.3 Difference between Unobstructed Pumps and Water Pumps
The difference between a non-clogging pump and a water pump lies in the fact that it is designed to allow the largest solid particles to pass through the pump size. Although there are single-blade (no-blade) impellers, the ordinary non-clogging impeller has two blades. The blades of the two-blade impeller are very thick, and there are large rounded corners between the blade and the cover plate at the blade inlet. The no-blade impeller has no blade tips, so it will not get stuck with garbage. On the other hand, due to its asymmetry, the impeller is inherently unbalanced. There are also non-clogging types of submersible pumps, but they are usually not recommended.
