JP-7854734-B2 - Corrosion-resistant screw pump rotating shaft
Inventors
- 末廣 盛男
- 末廣 大幸
Assignees
- スエヒロシステム株式会社
Dates
- Publication Date
- 20260507
- Application Date
- 20240919
- Priority Date
- 20230919
Claims (3)
- A shaft body is installed in an inclined channel spanning an upper and lower water channel, with its upper end supported by an upper bearing on land and its lower end supported by an underwater bearing in the water. The shaft body is provided with blades that protrude continuously and spirally from its outer circumferential surface, The rotating shaft of a corrosion-resistant screw pump is characterized in that the shaft body is made of carbon steel, which has a higher Young's modulus than stainless steel, the blades are made of stainless steel, which has stronger corrosion resistance than carbon steel, and the carbon steel portion of the shaft body is thermally sprayed with stainless steel below the high water level of the sewer channel to protect it from corrosion.
- A shaft body is installed in an inclined channel spanning an upper and lower water channel, with its upper end supported by an upper bearing on land and its lower end supported by an underwater bearing in the water. The shaft body is provided with blades that protrude continuously and spirally from its outer circumferential surface, The rotating shaft of a corrosion-resistant screw pump is characterized in that the shaft body and blades are made of carbon steel, which has a higher Young's modulus than stainless steel, and stainless steel is thermally sprayed onto the carbon steel portion below the high water level of the sewer channel to protect it from corrosion.
- A shaft body is installed in an inclined channel spanning an upper and lower water channel, with its upper end supported by an upper bearing on land and its lower end supported by an underwater bearing in the water. The shaft body is provided with blades that protrude continuously and spirally from its outer circumferential surface, The rotating shaft of a corrosion-resistant screw pump is characterized in that the shaft body is made of carbon steel, which has a higher Young's modulus than stainless steel, the blades are made of carbon steel, which has a higher Young's modulus than stainless steel, and stainless steel, which has stronger corrosion resistance than carbon steel, and the rotating shaft of the screw pump is thermal-sprayed with stainless steel below the high water level of the sewer channel, which is the submerged portion of the carbon steel, in order to protect the shaft body from corrosion.
Description
This invention relates to a screw pump for pumping water from a low place to a high place. Figure 5 is a schematic diagram of the overall configuration of a screw pump. The screw pump 1 consists of a rotating shaft (also called a runner) 2, which integrates the upper shaft, blades (also called an impeller), and submersible shaft; a mortar casing 7; an upper bearing 4; a submersible bearing 5; and a drive mechanism 6. The screw pump 1 is positioned in an inclined channel connecting the upper and lower waterways. With this configuration, the screw pump 1 rotates the impeller 3 on the rotating shaft (runner) 2 using the drive mechanism 6, thereby pumping water from the lower waterway and sending it to the upper waterway (disclosed, for example, in Patent Document 1). Note that the rotating shaft (runner) is an integrated unit consisting of the lower shaft, shaft, upper shaft, and blades; the shaft may be hollow. Traditionally, the material of such screw pumps has been selected based on the operating environment. For example, when increasing the pumping height, the screw pump is positioned at a 30 to 40 degree angle, requiring a longer overall length. As the overall length of the screw pump increases, the deflection of the body (rotating shaft), which is supported only by bearings at the upper and lower ends, becomes greater. Therefore, carbon steel with a high Young's modulus, such as SS400, is selected for the lower shaft of the rotating shaft, and SS400 steel is used for the blades. Shorter pumps have less deflection, so they are often made of stainless steel. Furthermore, in sewage treatment facilities or industrial wastewater treatment facilities where the wastewater contains hydrogen sulfide ( H₂S ), screw pumps may corrode. For this reason, stainless steel such as SUS304 or SUS316 is selected for both the blades of the rotating shaft and the lower shaft. Alternatively, if carbon steel is used, the rotating shaft surface is painted or coated with stainless steel thermal spraying. Furthermore, some water treatment facilities, such as sewage treatment plants, produce wastewater containing sand. This sandy wastewater can abrade and wear down the rotating screw pumps. For this reason, carbon steel is chosen, but considering corrosiveness, countermeasures are taken by increasing the wall thickness of carbon steel or stainless steel materials. The material for the rotating shaft of a screw pump can be selected from carbon steel, stainless steel, and carbon steel with stainless steel thermal spraying. However, stainless steel is generally more expensive than carbon steel. For example, if (i) carbon steel with surface coating is considered to be 1, then (ii) stainless steel will cost twice as much as (i). Also, (iii) if stainless steel thermal spraying is applied to carbon steel such as SS400, the cost will be more than three times that of (i). Patent No. 5869127 This is diagram 1 illustrating the rotating shaft of the corrosion-resistant screw pump of the present invention.This is diagram 2 illustrating the rotating shaft of the corrosion-resistant screw pump of the present invention.This is an explanatory diagram of the rotating shaft of a corrosion-resistant screw pump as shown in Modification Example 1.This is an explanatory diagram of the rotating shaft of a corrosion-resistant screw pump in modified example 2.This is a diagram illustrating a screw pump. An embodiment of the rotating shaft of the corrosion-resistant screw pump of the present invention will be described in detail below with reference to the drawings. Figure 1 is an explanatory diagram 1 of the rotating shaft of the corrosion-resistant screw pump of the present invention. Figure 2 is an explanatory diagram 2 of the rotating shaft of the corrosion-resistant screw pump of the present invention. As shown in the figures, the rotating shaft 10 of the corrosion-resistant screw pump of the present invention is provided with a shaft body 20 that is arranged in an inclined waterway spanning an upper waterway and a sewer waterway, and whose upper end is rotatably supported by an upper bearing 12 on land and whose lower end is supported by an underwater bearing 14 in the water, and blades 30 that protrude continuously and spirally from the outer circumferential surface of the shaft body 20, the shaft body 20 being made of carbon steel and the blades 30 being made of stainless steel, and the shaft body 20 being coated with stainless steel thermal spray S. In this embodiment, the shaft body 20 refers only to the shaft excluding the impeller of the rotating shaft. The shaft body 20 is made of carbon steel such as SS400, which has a large Young's modulus, because its overall length increases and deflection occurs when the pumping height increases. In this embodiment, carbon steel refers to a type of steel that is an alloy of iron and carbon, in which the amount of elements other than carbon is less than the amount that would classify it as alloy steel (for e