Sewage pump is a kind of non-blocking pump. It has various forms: for example, submersible and dry. The most common submersible type is WQ submersible sewage pump. The most common dry sewage pump is W-type horizontal sewage. Pump and WL vertical sewage pump. It is mainly used to transport urban sewage, and contains fibers in feces or liquids. A medium of solid particles such as paper dust, usually at a temperature of not more than 80 ° C. Because the medium being conveyed contains fibers that are easily entangled or bunched. Therefore, the pump flow path is easy to block, and once the pump is blocked, the pump can not work normally, or even burn the motor, thereby causing poor drainage. It has a serious impact on urban life and environmental protection. Therefore, anti-blocking and reliability are important factors in the quality of sewage pumps.
Structure of the sewage pump The spiral volute is basically not used in the sewage pump. The annular pressure water chamber is more convenient to use on a small sewage pump because of its simple structure. However, due to the appearance of the intermediate type (semi-spiral) pressurized water chamber, the application range of the annular pressurized water chamber is gradually reduced. Because the intermediate type pressurized water chamber has both the high efficiency of the spiral and the high permeability of the annular pressurized water chamber, it has attracted more and more attention from manufacturers. Like other pumps, the impeller, the pressurized water chamber, and the two core components of the sewage pump. The performance of the pump is representative of the performance of the pump, the anti-blocking performance of the sewage pump, the efficiency of the high and low, as well as the cavitation performance, anti-abrasion performance is mainly guaranteed by the two major components of the leaf pump and the pressurized water chamber. The following are introduced separately: 1. Impeller structure type: The structure of the impeller is divided into four categories: vane type (open type, closed type), swirl type, flow path type, (including single flow path and double flow path) spiral centrifugation. Four types. The open semi-open impeller is easy to manufacture. When the impeller is clogged, it can be easily cleaned and repaired. However, in the long-term operation, the gap between the vane and the sidewall of the pressurized water chamber will increase when the particles are abraded. Reduce efficiency. And the addition of the gap destroys the pressure difference distribution on the blade. Not only does it generate a large amount of vortex loss, but it also increases the axial force of the pump. At the same time, due to the increased clearance, the stability of the liquid flow state in the flow channel is destroyed, causing the pump to vibrate. This type of impeller is not easy to transport. The medium of large particles and long fibers, in terms of performance, the impeller of this type has low efficiency, and the highest efficiency is about 92% of that of the ordinary closed impeller, and the head curve is relatively flat. 2. Swirl impeller: The pump with this type of impeller is partially or completely retracted from the flow passage of the pressurized water chamber. Therefore, the non-clogging performance is good, and the ability to pass the particles and the passage ability of the long fibers are strong. The particles move in the pressurized water chamber by the vortex generated by the rotation of the impeller, and the suspended particles themselves do not generate energy, but exchange energy with the liquid in the flow channel. During the flow process, the suspended particles or long fibers are not in contact with the blades, and the blades are less worn, and there is no case where the gaps are increased due to abrasion, and the problem of serious decline in efficiency is not caused in long-term operation. The pump of the type impeller is suitable for pumping media containing large particles and long fibers. In terms of performance, the impeller has low efficiency, which is only about 70% of the ordinary closed impeller, and the head curve is relatively flat. 3. Closed impeller: This type of impeller has high normal efficiency. Moreover, the condition is relatively stable in long-term operation, and the axial force of the pump using the type impeller is small, and the auxiliary blades can be disposed on the front and rear covers. The secondary vanes on the front cover reduce vortex losses at the impeller inlet and wear of the particles against the seal ring. The auxiliary vanes on the rear cover not only balance the axial force, but also prevent the suspended particles from entering the mechanical seal chamber to protect the mechanical seal. However, the impeller of the type has poor non-blocking property and is easy to be entangled, and is not suitable for pumping a sewage medium containing large particles (long fibers). 4. Flow path impeller: This type of impeller is a bladeless impeller. The impeller flow path is a curved flow path from the inlet to the outlet. Therefore, it is suitable for pumping a medium containing large particles and long fibers. Good resistance to blocking. In terms of performance, the efficiency of the impeller of this type is not much different from that of the ordinary closed impeller, but the head curve of the impeller pump is steeply lowered. The power curve is relatively stable and it is not easy to produce super power. However, the impeller performance of this type of impeller is not as good as that of the ordinary closed impeller, especially suitable for pumps with pressurized inlets. 5. Screw Centrifugal Impeller: The blade of this type of impeller is a twisted spiral blade that extends axially from the suction port on the tapered hub body. The pump of the impeller has the functions of a positive displacement pump and a centrifugal pump. When the suspended particles flow through the blade, they do not hit any part of the pump, so the damage is good. It is less destructive to the transported material. The pump with this type of impeller is suitable for pumping media containing large particles and long fibers, as well as high concentration media, due to the propulsion of the spiral and the high permeability of the suspended particles. It has obvious features in the case where the damage of the transport medium is strictly required. In terms of performance, the pump has a steep drop head curve and a flat power curve. The structure of the pressurized water chamber The most common type of pressurized water chamber used for sewage pumps is the volute. In the internal submersible pump, radial vanes or runner vanes are often used. The volute has three types: spiral type, ring type and intermediate type.
【Case of centrifugal pump irrigation pump]】
Centrifugal pump (except self-priming pump) must fill the water pump and inlet pipe before starting. There are two main methods of filling water before the centrifugal pump is started: one is the assembly bottom. The valve is filled with water. Otherwise, the pump is not able to pump water. The centrifugal pump does not produce water after starting, often because the air in the pump is not drained and the water is not filled. In the process of insoluble sulfur production, high temperature insoluble sulfur must be quenched by quenching liquid to stabilize. The quenching liquid circulation is completed by centrifugal pump. Because the quenching liquid is corrosive, and the pump is frequently opened and closed, the operator The pumping process is quite vocal, and it is eager to change the cumbersome and original method of pumping. After analysis and research, it was decided to adopt the following method to change the time of pumping operation, thus avoiding the trouble of having to pump the pump before each pump is turned on. As shown in Fig. 1, add a small bucket before the suction port of the centrifugal pump. The bottom surface of the small barrel is not lower than the highest point of the pump casing of the centrifugal pump. Before the pump is opened, the quenching liquid is filled from the flange hole above the small barrel, and then sealed with the flange of the raft, so that the pump is opened once and then the pump is opened. There is no need to refill the pump, thus greatly improving the working conditions of the operator. Now quantitatively analyze the effect of the height on the suction pump after adding the keg. For a general centrifugal pump, the suction height is calculated as follows: Zs=Hs(ρw)/(ρ)-hfs Zs is the suction height, Hs is the allowable suction “vacuum degree” value specified in the pump performance table, hfs is the head loss in the suction line and the allowable cavitation allowance, the above unit is m; ρw is water Density, ρ is the density of the liquid delivered, in units of kg.m-3. After the pump is improved by the above method, due to the structural reasons, after the centrifugal pump is turned on, the gas in the pipette before the keg is stored in the upper part of the keg, so that a certain pressure is formed in the keg, and the pressure is formed. The size can be obtained from the ideal gas theorem PV1=PgV2, ie pg. Where, P is the gas pressure in the upper part of the bucket at the time of operation, pg is the atmospheric pressure, Pa; V1 is the volume of the small barrel, and V2 is the volume inside the pipette of the pipette before the small barrel, m3.
