Why is single screw pump Better?

A screw pump is a rotary pump that relies on the volume change and movement of the meshing space formed by the pump body and the screw to transport liquid or increase its pressure. Screw pumps are divided into single screw pumps, double screw pumps and three screw pumps according to the number of screws. When the active screw rotates, it drives the driven screw that meshes with it to rotate together, and the volume of the screw meshing space at one end of the suction chamber gradually increases, and the pressure decreases. The liquid enters the meshing space volume under the action of the pressure difference. When the volume increases to form a sealed chamber, the liquid moves continuously along the axial direction in each sealed chamber until it reaches one end of the discharge chamber. At this time, the volume of the screw meshing space at one end of the discharge chamber gradually decreases, and the liquid is discharged. The working principle of the screw pump is similar to that of the gear pump, except that the screw replaces the gear in structure. The table shows the characteristics and application range of various screw pumps. The flow and pressure pulse of the screw pump are very small, the noise and vibration are small, and it has self-priming ability, but the screw processing is more difficult. The pump has two structures: single suction and double suction, but the single screw pump only has single suction. The pump must be equipped with a safety valve (single screw pump does not need to be equipped) to prevent the pump or prime mover from being damaged due to some reasons such as blockage of the discharge pipe, which causes the pump outlet pressure to exceed the allowable value.

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1. Function and purpose of single screw pump

Based on the unique performance and excellent quality of “can transport high concentration, high viscosity, high abrasiveness, high solid content, multiple mixed media containing gas, solid liquid, adjustable speed to control flow, and can maintain the integrity of the transported materials”, single screw pumps can be widely used in the following fields to transport various media:

1) Application in environmental protection and energy fields: Single screw pumps are widely used in new energy fields, such as biogas, solar energy, wind energy, solid waste treatment, etc. Among them, screw pumps can transport a mixture of biogas slurry, biogas residue, plant straw and animal feces, and separated and treated food waste in the field of biogas.

2) Application in the field of food and medicine: In modern society, the hygiene requirements of food processing are becoming increasingly stringent. The single screw pump is designed and manufactured according to EHEDG and QHD standards, and the materials are certified by FDA, BGVV, and PL. For processes with strict hygiene requirements and conveying sensitive media containing solid particles, the single screw pump meets the requirements of the 3A standard. There is no dead corner in the flow part, which is easy to clean and meets the requirements of GIP online cleaning and SIP high-temperature sterilization treatment process.

3) Application in the field of oil and gas: The single screw pump can be used for vertical wells or horizontal wells. It has a compact structure, small footprint, low energy consumption, reliable operation, and low life cycle cost. It is particularly suitable for the exploitation of heavy oil and sand-containing gas formations. In addition, in the process of oil field production and transportation, the oil field pump series is a unique solution designed specifically for different processes in the oil field.

4) Application in the field of chemical industry: Single screw pumps convey harsh media. For different purposes, carbon steel, stainless steel, bidirectional stainless steel, Hastelloy and titanium alloy and even ceramic rotors are selected. When the medium cannot be made of elastic materials due to high temperature or certain chemical components, plastic stators, cast iron stators, etc. can be used. The conveyed media are very wide, such as dyes, pigments, paints, coatings, various acid and alkali solutions, various catalysts, various chemical raw materials with complex components, etc. It has been successfully applied to pulp and paper, emulsion explosives, water-coal slurry, mining, refining and chemical plants, etc.

5) Application of metering dosing technology and system: The flow rate and speed of the single screw pump are proportional. By adjusting the speed, the purpose of accurate quantitative delivery can be achieved. The combined control system of the robot arm can provide a strong guarantee for modern automated continuous production. The coating is uniform, without accumulation, breakpoints, or dripping.

Of course, in addition to the above-mentioned environmental protection energy, petrochemical, food and medicine and other fields, single screw pumps are also widely used in the food industry.

2. Advantages of screw pumps

1) Wide pressure and flow range. The pressure is about 3.4-340 kgf/cm

2) The flow rate can reach cm3/min; 2. The types and viscosity range of the transported liquids are wide;

3) Because the inertia force of the rotating parts in the pump is low, a very high speed can be used;

4) Good suction performance and self-priming ability;

5) The flow rate is uniform and continuous, with low vibration and low noise;

6) Compared with other rotary pumps, it is less sensitive to incoming gas and dirt;

7) The structure is solid and easy to install and maintain.

3. Disadvantages of screw pumps

1) The processing and assembly requirements of the screw are high;

2) The performance of the pump is sensitive to changes in the viscosity of the liquid

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The Screw pump transports liquid or semi-solid substances through the gap between the screw or spiral rotor and the shell. According to the different screw structures and working principles, Screw pump can be divided into single Screw pump, double Screw pump and three Screw pump.

1.Single Screw pump: a single Screw pump consists of a screw rotor and a fixed housing. When the screw rotates, the liquid is sucked in and pushed along the axial direction of the screw, thus achieving transportation. Single Screw pump is suitable for low to medium viscosity liquid and semi-solid substances, commonly used in sewage treatment, food processing, petrochemical and other fields.

2.Twin Screw pump: twin Screw pump consists of two symmetrically rotating screw rotors and a shell. The gap between the screws forms a sealing chamber, and the liquid is sucked in and transported through the gap between the rotor threads. Twin screw pump has high pressure stability and conveying capacity, and is suitable for media with high viscosity, low flow rate and solid particles, which are commonly used in chemical, petroleum and marine industries.

3.Three Screw pump: 3 Screw pump are composed of three screw rotors and a shell. Multiple sealing chambers are formed between the screws, through which liquid is sucked in and pushed forward. 3 Screw pump have higher pressure stability and transmission capacity, and are suitable for liquid media with high viscosity, high temperature and high pressure, which are commonly used in petroleum, chemical industry, power and other fields.

The advantages and disadvantages of Screw pump

Advantages:

Wide application: Screw pump is suitable for a variety of media, including high viscosity, semi-solid substances and liquids containing solid particles. They are widely used in various industries, including chemical, petroleum, food processing, sewage treatment, papermaking, power, etc.

Efficient energy utilization: Screw pump has efficient conveying efficiency and stable pressure characteristics, which can realize energy conservation.

Low pulsation: the continuous conveying characteristic of Screw pump makes the flow pulsation low, which is conducive to the stability of some technological processes.

Can transport high temperature medium: some types of Screw pump can handle high temperature liquid. Screw pump is a good method for extracting heavy oil and sand bearing crude oil. The Volumetric efficiency of Screw pump increases with the increase of crude oil viscosity.

Self suction capacity: Screw pump has better suction capacity, so it works better in long pipes, oil with higher viscosity and air in the fluid.

Disadvantages:

High initial investment: the initial investment cost of Screw pump is relatively high, especially for the Screw pump with large capacity and high performance.

High maintenance requirements: Screw pump requires high maintenance and cleaning requirements, especially when conveying solid particles or corrosive media, the screw and pump body need to be cleaned and maintained regularly.

Sensitivity to liquid: Screw pump is sensitive to the viscosity and characteristics of liquid, and the change of liquid may affect the performance and output of the pump.

Overall, Screw pump has been widely used in many industries and application fields due to its wide applicability, efficient energy utilization and low pulsation. Although the price of Screw pump is higher than other types of pumps, the characteristics of Screw pump are more obvious. For applications involving the transportation of fuel, oil and other lubricants, Screw pump and gear pump are usually selected as pumping technologies. Since the fluctuation of fluid thickness affects the performance of centrifugal pump much more than that of positive displacement pump, Screw pump and gear pump are usually the most effective solutions for oil and fuel. When choosing to use Screw pump, factors such as specific application demand, budget and medium characteristics should be comprehensively considered.