What is a water pump
What is a water pump?
Table of Contents
- 1 What is a water pump?
- 2 Structure of water pump
- 3 Working principle of water pump
- 4 Purpose of water pump
- 5 Classification of pumps
- 6 Installation method of water pump
- 7 Precautions for water pump
- 8 Main problems of water pump
- 9 Technical requirements for water pump
- 10 How to buy water pump
- 11 Development trend of water pump
A water pump is a machine that conveys or pressurizes liquid. It transfers the mechanical energy or other external energy of the prime mover to the liquid so as to increase the energy of the liquid, which is mainly used for conveying liquid, including water, oil, acid and alkali liquid, emulsion, suspending emulsion and liquid metal.
It can also transport liquids, gas mixtures and liquids containing suspended solids. The technical parameters of pump performance include flow, suction head, head, shaft power, water power, efficiency, etc; According to different working principles, it can be divided into positive displacement pump, vane pump and so on. Positive displacement pump uses the change of its working chamber volume to transfer energy; Vane pump uses the interaction between rotating blades and water to transfer energy, including centrifugal pump, axial flow pump and mixed flow pump.
Structure of water pump
When the water pump rotor works at high speed, if its mass is unbalanced, a large centrifugal force will be generated during rotation, resulting in vibration or damage of the water pump. The balance of the rotor is achieved through the mass balance of various components (including shaft, impeller, shaft sleeve, balance disc, etc.), so the static balance verification shall be carried out for the newly installed impeller. The specific methods are:
- (1) Install the impeller on the dummy shaft and put it on the static balance test bench with the level adjusted. There are two tracks on the test bench on which the dummy shaft can roll freely.
- (2) Mark the heavy side of the impeller. If the impeller mass is unbalanced, the heavier side will always automatically turn to the lower side. Add a heavy block (stick with the surface or increase or decrease the iron sheet with a clip) at the symmetrical position of the heavy place (i.e. the lighter side) until the impeller can stop at any position.
- (3) Weigh the mass of the weighting block. Instead of adding weight on the lighter side of the impeller, the balance of the impeller is achieved by reducing weight on the heavier side. During weight reduction, milling machine or grinding wheel can be used (when the removal amount is small), but note that the depth of milling or grinding shall not exceed 1 / 3 of the thickness of impeller cover plate. For the impeller after static balance, the allowable deviation of static balance shall not exceed the product of the impeller outer diameter and 0.025g/mm. For example, for an impeller with a diameter of 200mm, the allowable deviation is 5g.
Disassembly and assembly of coupling
- (1) When removing the coupling, it is not allowed to knock directly with a hammer, but should be padded with a copper rod, and the hub of the coupling should be hit instead of the outer edge of the coupling, because it is very easy to be damaged here. The best way is to disassemble the coupling with a clutch. For small and medium-sized pumps, the coupling is easy to take down because of its small interference. For larger water pumps, there is a large interference between the coupling and the shaft, so the coupling must be heated during disassembly.
- (2) When assembling the coupling, pay attention to the serial number of the key (for couplings with more than two keys). When striking with a copper rod, pay attention to the striking part. For example, when knocking on the end face of the shaft hole, it is easy to cause the shaft hole to shrink, so that the shaft cannot pass through; Knocking on the outer edge of the coupling is easy to damage the flatness of the end face, which will affect the measurement accuracy when aligning with a feeler gauge in the future. The coupling with large interference shall be heated before installation.
- (3) Coupling pins, nuts, washers and rubber pads must be consistent in their respective specifications and sizes to avoid affecting the dynamic balance of the coupling. Corresponding marks shall be made on coupling bolts and corresponding coupling pin holes to prevent wrong installation.
- (4) Transition fit is generally adopted for the fit between the coupling and the shaft, which may have a small amount of interference or clearance. For the coupling with long hub, loose transition fit can be adopted. Due to the long shaft hole and rough surface processing, some interference will naturally occur after assembly. If it is found that the fit between the coupling and the shaft is too loose, affecting the concentricity of the hole and shaft, repair welding shall be carried out. Pitting or copper skin on the shaft is an expedient measure and cannot be used as an ideal method.
Working principle of water pump
- 1. Positive displacement pump: use the periodic change of working chamber volume to transport liquid.
- 2. Vane pump: use the interaction between vane and liquid to transport liquid.
1. Working principle of centrifugal pump
Before the water pump starts, fill the pump and the inlet pipe with water. After the water pump runs, under the action of the centrifugal force generated by the high-speed rotation of the impeller, the water in the impeller channel is thrown around and pressed into the volute, the impeller inlet forms a vacuum, and the water in the pool is sucked along the suction pipe under the external atmospheric pressure to supplement this space. Then the inhaled water is thrown out by the impeller and enters the outlet pipe through the volute. Thus, if the centrifugal pump impeller rotates continuously, it can continuously absorb and press water, and the water can be continuously raised from low to high or far away. To sum up, centrifugal pump is called centrifugal pump because it lifts water to a high place under the action of centrifugal force generated by high-speed rotation of impeller.
2. General characteristics of centrifugal pump
(1) The flow direction of water along the centrifugal pump is to suck in along the axial direction of the impeller and flow out perpendicular to the axial direction, that is, the inlet and outlet flow directions form 90 ° to each other.
(2) Because the centrifugal pump forms vacuum water absorption by the inlet of the impeller, water must be injected into the pump and the suction pipe or pumped with a vacuum pump before starting, so as to exhaust the air to form a vacuum. Moreover, the pump shell and the suction pipeline must be strictly sealed without air leakage, otherwise there will be no vacuum and water will not be absorbed.
(3) Since it is impossible to form absolute vacuum at the impeller inlet, the suction height of the centrifugal pump shall not exceed 10m. In addition, the actual allowable installation height (the height between the pump axis and the suction water surface) is far less than 10m due to the loss along the water flow through the suction pipeline. If the installation is too high, it will not absorb water; In addition, since the atmospheric pressure in mountainous areas is lower than that in plain areas, when the same water pump is installed in mountainous areas, especially in mountainous areas, its installation height should be reduced, otherwise it can not absorb water.
Axial flow pump
Working principle and characteristics of axial flow pump:
1. Working principle of axial flow pump
The working principle of axial flow pump is different from that of centrifugal pump. It mainly uses the thrust generated by the high-speed rotation of impeller to lift water. The lift generated by the rotating blades of the axial flow pump on the water can push the water from below to above.
The blades of the axial flow pump are generally immersed in the pool of the suction water source. Due to the high-speed rotation of the impeller, the water is continuously pushed upward under the lift generated by the blade, so that the water flows out along the outlet pipe. With the continuous rotation of the impeller, the water is continuously pressed to a high place.
2. General characteristics of axial flow pump
- (1) The flow direction of water in the axial flow pump is along the axial suction and axial outflow of the impeller, so it is called axial flow pump.
- (2) Low lift (1 ~ 13m), large flow and high benefit. It is suitable for drainage and irrigation in plain, lake and river areas.
- (3) There is no need to fill water before starting, and the operation is simple.
Mixed flow pump
1. Working principle of mixed flow pump
As the impeller shape of the mixed flow pump is between the impeller of the centrifugal pump and the impeller of the axial flow pump, the working principle of the mixed flow pump has both centrifugal force and lifting force. By the combined action of the two, the water flows out of the impeller at a certain angle with the shaft and lifts the water to a higher place through the volute chamber and pipeline.
2. General characteristics of mixed flow pump
(1) Compared with centrifugal pump, mixed flow pump has lower head and larger flow. Compared with axial flow pump, mixed flow pump has higher head and lower flow. It is suitable for drainage and irrigation in plain and lake areas.
(2) Water is sucked in and out along the flow direction of the mixed flow pump at a certain angle with the impeller shaft, so it is also called inclined flow pump.
Purpose of water pump
It is widely used in shipbuilding, oil exploitation, truck and so on. In 2008, the ship output reached 15000 tons, and the DWT accounted for 21% of the world market. By 2015, it will become the largest shipbuilding country in the world. In order to ensure the normal navigation or mooring of the ship and meet the living needs of crew and passengers, each ship must be equipped with a certain number of marine pumps that can play a corresponding role. Marine pumps are one of the important auxiliary machines. According to incomplete statistics, among various ship auxiliary mechanical equipment, the total number of marine pumps of various types and different purposes accounts for about 20% – 30% of the total amount of ship mechanical equipment, and the price of marine pumps also accounts for a large proportion in the cost of ship equipment. In the total cost, marine pumps account for about 4% – 8% of the cost of marine equipment. Generally, the purchase of marine pumps for more than one medium-sized ship can reach more than 10 million yuan. When it comes to the key pump market, it is necessary to say that the completed “west to East Gas Transmission” project in China also needs pump products. At the same time, the state will build other natural gas transmission pipelines, and a large number of pump products are also required in these projects.
The water pump has different purposes, different conveying liquid media, different flow and different lift ranges. Therefore, its structural form is certainly different and its materials are also different. To sum up, it can be roughly divided into:
- 1. Urban water supply
- 2. Sewage system
- 3. Civil and building systems
- 4. Agricultural water conservancy system
- 5. Power station system
- 6. Chemical system
- 7. Petroleum industry system
- 8. Mine Metallurgical System
- 9. Light industry system
- 10. Ship system
- 11. Piping system
Classification of pumps
Classification by use
Transfer pump, circulating pump, fire pump, pressure test pump, sewage pump, metering pump, sanitary pump, dosing pump, gelatinization pump, infusion pump, defoaming pump, process pump, oil transfer pump, feed pump, drainage pump, drain pump, dredging pump, sprinkler pump, booster pump, high pressure pump, insulation pump, high temperature pump, low temperature pump, condensate pump, heat network pump, cooling pump, HVAC pump, deep well pump, pain pump Chemotherapy pump, air pump, blood pump, material pump, sulfur removal pump, shear pump, grinding pump, fuel pump, fish suction pump, bathtub pump, source heat pump, filter pump, oxygenation pump, shampoo pump, injection pump, inflation pump, gas pump, art pump, odorization pump and chopping pump.
Petroleum pump, metallurgical pump, chemical pump, fishery pump, mining pump, electric pump, hydraulic pump, water treatment pump, food pump, brewing pump, pharmaceutical pump, beverage pump, oil refining pump, seasoning pump, papermaking pump, textile pump, printing and dyeing pump, pottery pump, paint pump, pesticide pump, chemical fertilizer pump, sugar pump, alcohol pump, environmental protection pump, salt pump, beer pump, starch pump, water supply pump, heating pump Agricultural pump, garden pump, aquarium pump, boiler pump, medical pump, marine pump, aviation pump, automobile pump, fire pump, cement pump, air conditioning pump, nuclear power pump, mechanical pump, gas pump and oil-gas mixed transmission pump.
Classification by principle
Reciprocating pump, plunger pump, piston pump, diaphragm pump, rotor pump, screw pump, liquid ring pump, gear pump, sliding vane pump, roots pump, roller pump, cam pump, peristaltic pump, disturbing pump, vane pump, centrifugal pump, axial flow pump, mixed flow pump, vortex pump, jet pump, water hammer pump, vacuum pump, shell pump, hose pump and worm pump.
Classification by media
Clean water pump, sewage pump, hot water pump, hot oil pump, heavy oil pump, heavy oil pump, slag oil pump, asphalt pump, impurity pump, slurry pump, slurry pump, mortar pump, ash pump, mud pump, cement pump, concrete pump, powder pump, acid pump, air pump, steam pump, oxygen pump, ammonia pump, gas pump, blood pump, foam pump, emulsion pump, paint pump, etc. Sulfuric acid pump, hydrochloric acid pump, colloid pump, alcohol pump, beer pump, wine pump, chocolate pump, milk pump, starch pump, wort pump, toothpaste pump, brine pump, brine pump, alkali pump, molten salt pump, grease pump, pesticide pump, fertilizer pump, reagent pump, gas-liquid pump, oil pump, chemical fiber pump, spinning pump, dose pump, paint pump, pulp pump, insulin pump Concentrated slurry pump, air pump, water pump and oil pump.
Water circulating pump
The circulating water pump is set at the heat station (heat Center), heat source or cold source, etc. In the closed loop of the heating system or air conditioning water system, the circulating water pump does not lift the water to a high place, but makes the water circulate in the system again and again to overcome the resistance loss of the loop, which has no direct relationship with the height of the building. Therefore, it is called the circulating water pump.
How to select circulating water pump
When selecting circulating water pump, the following provisions shall be met:
- (1) The total flow of the circulating water pump shall not be less than the total design flow of the pipe network. When a bypass pipe is installed from the outlet of the hot water boiler to the suction of the circulating water pump, the flow through the bypass pipe shall be included.
- (2) The flow head characteristic curve of the circulating water pump shall be relatively gentle near the working point of the pump, so that the change of the head of the circulating water pump is small when the hydraulic condition of the network changes. Generally, the characteristic curve of single-stage water pump is relatively flat, and single-stage water pump should be selected as circulating water pump.
- (3) The pressure bearing and temperature resistance of circulating water pump shall adapt to the design parameters of heat supply network. Circulating water pumps are mostly installed on the return pipe of heat supply network. The allowable working temperature of circulating water pump shall not be lower than 80 ℃. If it is installed on the water supply pipe of the heat supply network, a high temperature resistant hot water circulating pump must be used.
- (4) The working point of circulating water pump shall be within the efficient working range of water pump.
- (5) The determination of the number of circulating water pumps is related to the heating regulation mode adopted by the hot water heating system. The number of circulating water pumps shall not be less than two, one of which is standby. When four or more water pumps operate in parallel, standby water pumps can not be set. When centralized quality regulation is adopted, water pumps of the same model should be selected for parallel operation.
- (6) For multi heat source networked operation or single heat source heating system with central mass flow regulation, the circulating water pump of heat source shall adopt variable frequency speed regulating pump.
- (7) When the hot water heating system adopts the quality regulation of changing the flow in stages, the flow and head in each stage are different. In order to save electric energy, pump sets with different flow and head should be selected.
- (8) For the hot water heating system with hot water supply heat load, the network flow during non heating period is much less than that during heating period, so it can be considered to add a circulating water pump for special hot water load.
- (9) When multiple water pumps operate in parallel, the hydraulic characteristic curve of water pump and heat supply network shall be drawn, its working point shall be determined, and the water pump shall be selected.
Boiler feed pump
The boiler feed pump is to draw water into the boiler drum. Generally, the drum level is controlled by the loop. The steam in the drum is sent to the steam consuming equipment and takes away the corresponding water. Therefore, it is necessary to supplement the hydraulic equipment from the boiler feed pump to maintain the normal water level.
Operation manual of boiler feed pump
1. Operation specification must see
Warning: violation of operating procedures and habits may cause personal injury or death.
Caution: violation of operating procedures and habits may cause damage to the equipment.
Note: operating procedures and conditions shall be paid great attention to.
2. Assembly and disassembly of pump
1. Pump assembly the assembly quality of the DG pump directly affects the normal operation of the pump, and affects the service life and performance parameters of the pump; The vibration and noise of the unit shall be affected, and the following points shall be paid attention to during assembly:
- a. The concentricity of the assembled parts of the fixed part shall be guaranteed by the manufacturing accuracy and assembly quality of the parts, and the machining accuracy and surface roughness of the parts shall be guaranteed without collision and scratch. Molybdenum disulfide used as sealant shall be clean. The screws and bolts used for fastening shall be stressed evenly.
- b. The alignment between the impeller outlet channel and the guide vane inlet channel depends on the axial size of each part. The quality of flow channel to neutral directly affects the performance of the pump, so the size of the pump can not be adjusted at will.
- c. After the pump is assembled and before packing is installed, rotate the pump rotor by hand to check whether the pump rotor rotates flexibly in the housing and whether the axial movement meets the specified requirements.
- d. After the above inspection meets the requirements, fill the shaft seals at both ends of the pump, and pay attention to the relative position of the packing ring in the packing chamber.
2. Pump removal
a. Disassembly shall be carried out in the reverse order of assembly. During disassembly, the manufacturing accuracy of parts shall be strictly protected from damage.
b. When removing the threading rod, each middle section shall be padded first to avoid sinking and bending the shaft after the stop of each middle section is loose.
3. Pump installation
In addition to meeting the general installation technical requirements, the following points shall be paid attention to during the installation of this type of pump:
1. When the motor and water pump are installed together, the axial direction of the pump coupling end shall be pulled out, and a 3-5mm end clearance value shall be reserved to ensure the axial clearance value between the pump and motor coupling.
Note: grouting shall be carried out after the bottom plate is leveled and the equipment levelness is good
Caution: for successful installation, the coupling adjustment must be correct, and the flexible coupling cannot compensate for any obvious misalignment. Misalignment may cause rapid wear, noise, vibration and damage to the equipment. Therefore, the coupling must be adjusted within the given limits.
Caution: measures must be taken to support the inlet and outlet pipes of the pump to prevent excessive load at the inlet and outlet of the pump.
2. The centerline of pump and motor shaft shall be on the same horizontal line.
3. The pump can only bear its own internal force, not any external force.
4. Start, operation and shutdown of pump.
Warning: for the safety of the operator, do not operate beyond the conditions of the pump nameplate, so as not to endanger the safety of the equipment and operators. In order to ensure the smooth operation and maintenance of the pump and other actions, please refer to the instructions.
1. Before starting the pump, turn the rotor to check whether the rotor is flexible.
2. Check whether the rotation direction of the motor is consistent with that of the pump.
3. Close the gate valve and pressure gauge cock at the pump outlet, and use the delivered liquid or vacuum system to discharge the air in the suction pipe and pump body (it is strictly prohibited to start and run empty).
4. Check the tightness of the connecting bolts between the pump and the motor and the safety conditions around the pump to make the pump ready to start.
Warning: the equipment can only be operated after the coupling shield is installed. Ignoring this point will cause casualties.
5. Start the pump. After the pump operates normally, open the pressure gauge cock, slowly open the outlet gate valve, and control the given head of the pump according to the reading of the outlet pressure gauge.
1. This type of pump balances the axial force by the internal balance mechanism. The balance device has the balance liquid flowing out, and the balance liquid is connected to the suction section by the balance water pipe.
2. The rolling bearings of this type of pump are equipped with cooling devices. The cooling water pipe must be connected before the water pump runs. The change of bearing temperature rise reflects the assembly quality of the pump. The bearing temperature rise shall not be higher than the ambient temperature by 35 ℃ and the maximum temperature shall not be higher than 75 ℃.
Warning: operating equipment without proper lubrication may cause bearing heating, fracture, pump locked rotor and equipment damage, and personal injury to operators.
3. The rotor of this type of pump has certain axial movement during operation, and the clearance between the end faces of the two couplings of the motor and the water pump shall be ensured.
4. During the operation of the pump, the wear of the impeller, sealing ring, guide vane sleeve, balance disc and shaft sleeve shall be checked regularly. If the wear is too large, it shall be replaced in time.
Warning: do not attempt to repair, maintain or clean the rotating machinery, otherwise the personal safety of operators will be endangered.
5. Users shall formulate more detailed operating procedures according to specific conditions.
（3） Shutdown: close the pressure gauge cock before shutdown, and then slowly close the outlet gate valve. The motor can be stopped only after the outlet gate valve is closed.
Main structure of boiler feed pump
The suction port and discharge port of the pump are vertically upward, and the axial force of the rotor is balanced by the balance plate. The shaft seal can be a packing seal or a mechanical seal. Only DG85-80, DG85-67 and DG155-67 adopt sliding bearings for rotor support, which are lubricated with thin oil, and other pumps adopt rolling bearings.
1. Pump housing section
The pump shell is mainly connected by bolts from the bearing body, front section, middle section, rear section and guide vane. The center line of the suction inlet of the front section is horizontal, and the outlet of the rear section is vertical to the horizontal.
2. Rotor part the rotor part is mainly composed of shaft and impeller, shaft sleeve, balance plate and other parts installed on the shaft. The parts on the shaft are fastened with flat keys and shaft sleeve nuts to make them integral with the shaft. The whole rotor is supported on the pump shell by bearings at both ends, and the number of impellers in the rotor part is determined according to the stage of the pump.
3. Bearing part
This type of pump bearing has two types: sliding bearing and rolling bearing, which are determined according to different models and do not bear axial force. During the operation of the pump, the rotor part shall be allowed to move axially in the pump shell, and the centripetal ball bearing shall not be used
4. Pump seal
The sealing surfaces between the front, middle and rear sections of the pump are sealed with molybdenum disulfide grease. The rotor part and the fixed part are sealed by sealing ring, guide vane sleeve, packing, etc. when the wear degree of the sealing ring and guide vane sleeve has affected the operation and performance of the pump, it shall be replaced.
When this type of pump is in use, the position of packing ring shall be placed correctly. The tightness of packing must be appropriate so that the liquid can exude drop by drop.
Daily maintenance of boiler feed pump
Boiler feed pump is the key to the safe and stable operation of boiler system. It is an important part of boiler automatic liquid level regulation system designed and established by using modern automatic control technology. China has more than 400000 sets of boiler equipment, most of which are boilers for industrial enterprises and boiler systems for power plants, and a small part is used in commercial fields such as residential baths. The stable operation of feed water pump is the basis of boiler operation and an important part of modern boiler liquid level regulation system. Once the feed pump fails, it will seriously endanger the operation safety of the boiler and lead to major accidents. Therefore, strengthening the daily maintenance and repair of feed pump in boiler system has become an important work of modern boiler maintenance department.
1. Failure analysis of boiler feed pump the feed pump system of modern large boilers is composed of multiple feed pumps, mainly two to three start-up feed pumps, and one or two electric feed pumps are used as standby or auxiliary. This configuration of feed water pump is conducive to starting the standby feed water pump system to make up insufficient when the feed water pump host system fails or cannot meet the boiler operation requirements, so as to avoid boiler shutdown caused by feed water pump failure. Common boiler feed pump faults mainly focus on lubricating oil system, air avoidance system, speed regulation system, overheating of auxiliary motor and insufficient flow. Through scientific analysis and fault cause finding, it is the basis for troubleshooting and solving the boiler feed pump fault. Only by troubleshooting the fault cause can we avoid the recurrence of the same type of fault. The causes and troubleshooting of different fault types are discussed below.
2. Analysis and troubleshooting of common faults of boiler feed pump
Analysis and elimination of motor overheating of electric feed pump for feed pump powered by motor, the most common fault is motor overheating. The main causes of motor overheating are high or low voltage, poor transmission, ventilation system failure or unit failure. When the motor overheats seriously, it will cause insulation burn out and rotor bar break. Therefore, in case of overheating of the motor, other pneumatic power modes shall be adopted for shutdown and maintenance. In case of motor overheating caused by voltage, the motor power supply system shall be checked, and the overheating fault of boiler feed pump motor shall be solved by restoring stable power supply. In addition, the poor external transmission will also cause the motor to overheat. Due to the poor transmission between the motor and the feed pump, the motor load is too large, resulting in the phenomenon of a small horse pulling a cart. The motor overload is the temperature rise. This situation must be repaired in time, resulting in unit failure. Thoroughly check the traditional system of motor and feed pump. The common traditional problems are mainly caused by lack of oil in the rotating bearing of the transmission system and bearing damage. Find out the fault point and replace or lubricate it. One of the most common faults caused by motor overheating due to the fault of the same subsystem is that the ventilation system cannot complete the work it should undertake due to fan damage, ventilation duct blockage, bearing wear and other reasons, resulting in motor overheating and serious coil burning. This situation must be checked one by one to find out the cause of the fault. The fault can be solved by unblocking the ventilation duct, repairing the fan and replacing the bearing.
The common causes of overheating of feed pump body and boiler feed pump body are friction caused by bearing damage, or lack of oil and poor oil quality in the lubrication system. Therefore, after finding that the feed pump body is overheated, first check whether the lubricating system is short of oil or the lubricating oil contains impurities, and then check whether the bearing is damaged. If the pump body that has just been repaired is overheated, check whether the clearance of rolling bearing or bracket cover is too small. After the above inspection, the pump body still generates heat. Check whether the pump shaft is bent or the two shafts are not concentric. At the same time, check the impeller balance, adjust the pump shaft or adjust the concentricity of the two shafts, and remove the impeller balance hole, so as to ensure the rotation balance between the pump shaft and the impeller and eliminate the fault.
The main causes of insufficient flow of boiler feed pump are pump blade damage, pipeline blockage or leakage. For the feed pump driven by belt, it is also necessary to consider whether the low speed caused by belt slip causes insufficient flow. After checking the belt, check the pipeline. If the leakage is blocked and the flow is still insufficient, consider whether the impeller is damaged. Check the impeller and lubricate the bearing to avoid insufficient flow due to insufficient speed caused by poor lubrication or damage of the bearing.
Removal of vibration fault of boiler feed pump system the fault of bearing system of boiler feed pump will cause insufficient flow, pump body heating, poor operation, etc. on the one hand, the fault is caused by lack of lubricating oil or impurities in lubricating oil. On the other hand, the vibration of unit will also cause the increase of bearing system fault. Excessive vibration of feed pump system will have an important impact on the safety of the whole unit, seriously endanger the safe and stable operation of the unit, and excessive vibration has an important impact on the unit and unit foundation. The causes of excessive vibration of the unit are mainly due to the deformation of pump shaft or motor rotor shaft rod, bearing damage and looseness of base fixing bolts. In case of excessive vibration of the unit, first check whether the bolts of the fixed base are firm, and then check whether the bearing is overheated and does not rotate smoothly. If the line is crossed, it can be determined that the excessive vibration is caused by bearing damage. If the unit still vibrates after other reasons are eliminated, it can be considered that the excessive vibration is caused by the deformation of pump shaft or motor rotor shaft rod. The deformation of pump shaft or motor rotor shaft rod is mostly temporary deformation, which is caused by local overheating due to the damage of unit bearing. The temperature can be balanced and the deformation can disappear after shutdown.
Daily maintenance focusing on Fault Prevention the daily maintenance of modern boiler feed pump must aim at fault prevention and establish a scientific maintenance system and system to guide the daily maintenance of feed pump. Establish failure and replacement records of feed pump parts and components, and master the damage time of each part in detail, so as to facilitate the timely replacement of parts and components before their service life in the later stage, so as to avoid the damage to the unit caused by untimely discovery of parts and components (such as bearings, etc.). In addition, the maintenance of feed pump lubrication system shall be strengthened, the lubricating oil quantity shall be checked regularly, and the parts shall be lubricated in time to avoid the occurrence of “dry grinding”. Before adding lubricating oil, pay attention to check the oil quality and the cleanliness of the adding port to avoid bringing impurities into the adding process to damage the bearing. During the maintenance, pay attention to the inspection and maintenance of the feed pump system pipeline, plug the leakage in time, check the anti rust coating on the outside of the pipeline frequently, and spray the coating peeling in time, so as to ensure the anti-corrosion of the pipeline. Attention shall also be paid to the inspection and maintenance of water source treatment system of feed pump during maintenance.
Conclusion boiler feed pump is an important part of modern boiler, which has an important impact on the safe and stable operation of boiler. Therefore, the boiler maintenance and management department must pay attention to the maintenance and management of the boiler feed pump system, carry out maintenance scientifically for the purpose of fault prevention, and timely replace the parts with expired service life, so as to avoid greater damage to the unit after the parts are damaged. Establish the maintenance record of feed pump system, and determine the replacement time according to the boiler operation and scientific analysis of the record, so as to ensure the stable operation of feed pump system. This requires the maintenance department to strengthen the training of professional and technical personnel. Professional and technical personnel are required not only to have high professional knowledge and skills of boiler feed pump, but also to have modern equipment management concepts and methods. Ensure the safe and stable operation of the boiler with scientific management and high-level professional skills.
Installation method of water pump
- 1. If the geographical environment permits, the water pump shall be as close to the water source as possible to reduce the length of the suction pipe. The foundation at the installation place of the water pump shall be firm, and a special foundation shall be built for the fixed pump station.
- 2. The water inlet pipeline shall be sealed reliably, must have special support, and cannot be hung on the water pump. For the inlet pipe equipped with bottom valve, the axis of the bottom valve shall be installed perpendicular to the horizontal plane as far as possible, and the included angle between the axis and the horizontal plane shall not be less than 45 °. When the water source is a channel, the bottom valve shall be more than 0.50m higher than the water bottom, and screening shall be added to prevent sundries from entering the pump.
- 3. The base of the machine and pump shall be horizontal and firmly connected with the foundation. When the machine and pump are driven by belt, the tight edge of the belt is at the bottom, so the transmission efficiency is high, and the rotation direction of the water pump impeller shall be consistent with the direction indicated by the arrow; When coupling transmission is adopted, the machine and pump must be coaxial.
- 4. The installation position of the water pump shall meet the requirements of allowable vacuum suction height, and the foundation must be horizontal and stable to ensure that the rotation direction of the power machinery is consistent with that of the water pump.
- 5. If there are multiple units in the same machine room, there shall be a distance of more than 800mm between units and between units and walls.
- 6. The suction pipe of the water pump must be well sealed, and elbows and gate valves shall be reduced as far as possible. Air shall be exhausted during filling and water diversion. Air shall not accumulate in the pipe during operation. The suction pipe is required to be slightly inclined to connect with the water inlet of the water pump, and the water inlet shall have a certain submergence depth.
Precautions for water pump
- 1. If the water pump has any small fault, remember not to let it work. If the packing of the water pump shaft is worn, it shall be added in time. If the water pump continues to be used, the air will leak. The direct impact of this is the increase of motor energy consumption, which will damage the impeller.
- 2. If the pump vibrates strongly during use, you must stop and check the cause, otherwise the pump will also be damaged.
- 3. When the bottom valve of the water pump leaks, some people will fill the inlet pipe of the water pump with dry soil and flush the water to the bottom valve. This is really undesirable. Because when the dry soil is put into the water inlet pipe, when the water pump starts working, the dry soil will enter the pump, which will damage the water pump impeller and bearing, which shortens the service life of the water pump. When the bottom valve leaks, it must be repaired. If it is very serious, it needs to be replaced with a new one.
- 4. Pay attention to the maintenance of the water pump after use. For example, when the water pump is used up, drain the water in the water pump. It is best to unload the water pipe and rinse it with clean water.
- 5. The adhesive tape on the water pump shall also be removed, and then washed with water and dried in the light. Do not put the adhesive tape in a dark and humid place. The adhesive tape of the water pump must not be stained with oil, let alone some sticky things on the adhesive tape.
- 6. Carefully check whether there are cracks on the impeller and whether the impeller is fixed on the bearing. If there are cracks and looseness, it shall be repaired in time. If there is soil on the water pump impeller, it shall also be cleaned.
Main problems of water pump
Unable to start
First, check the power supply: whether the connector is firmly connected; Whether the switch contacts tightly; Whether the fuse is blown; Whether three-phase power supply is equal. In case of open circuit, poor contact, fuse blown and phase loss, the cause shall be found out and repaired in time. Secondly, check whether it is the mechanical failure of the pump itself. The common reasons are: the packing is too tight or the impeller is blocked by sundries between the impeller and the pump body; The pump shaft, bearing and leakage reducing ring are rusted; Serious bending of pump shaft, etc. Elimination method: loosen the filler and dredge the water diversion tank; Disassemble the pump body, remove sundries and rust; Remove the pump shaft and calibrate or replace it with a new one.
Water pump heating
Cause: bearing damage; The clearance of rolling bearing or bracket cover is too small; The pump shaft is bent or the two shafts are not concentric; The tape is too tight; Lack of oil or poor oil quality; The balance hole on the impeller is blocked, and the impeller loses balance, increasing the thrust to one side. Troubleshooting: replace the bearing; Remove the rear cover and install a gasket between the bracket and the bearing seat; Investigate the pump shaft or adjust the concentricity of the two shafts; Properly loosen the belt tightness; Add clean butter, which accounts for about 60% of the clearance in the bearing; Remove the blockage in the balance hole.
Can’t absorb water
The reason is that there is air in the pump body or air accumulated in the water inlet pipe, or the bottom valve is not closed tightly, the filling water is insufficient, the packing of the vacuum pump leaks seriously, and the gate valve or flap valve is not closed tightly. Troubleshooting: first raise the water pressure, then fill the pump body with water, and then start the machine. At the same time, check whether the check valve is tight and whether the pipeline and joint have air leakage. If air leakage is found, apply lubricating oil or blending paint on the joint after disassembly, and tighten the screws. Check the oil seal ring of the water pump shaft. If it is seriously worn, replace it with a new one. Water leakage or air leakage of pipeline. The nut may not be tightened during installation. If the leakage is not serious, cement can be applied at the place of air leakage or water leakage, or cement slurry mixed with asphalt oil. For temporary repairs, apply some wet mud or soft soap. If there is water leakage at the joint, the nut can be tightened with a wrench. If the water leakage is serious, it must be disassembled and disassembled again and the cracked pipe must be replaced; Reduce the head and press the nozzle of the water pump into the water for 0.5m.
There are mainly the following reasons: the electric rotor is unbalanced; Poor coupling connection; Bearing wear and bending; Loose and broken parts of rotating parts; The pipeline support is not firm. Adjustment, repair, reinforcement, straightening and replacement can be adopted respectively.
There are four reasons. First, the reasons for power supply: the voltage is high or low. Under specific load, if the voltage variation range should be beyond + 10% to – 5% of the rated value, the motor will overheat; The three-phase voltage of the power supply is asymmetric, and the phase to phase imbalance of the three-phase voltage of the power supply exceeds 5%, which will lead to overheating of the winding; Lack of phase operation. Experience shows that more than 85% of the burned agricultural motors are caused by lack of phase operation. Lack of phase protection devices shall be installed on the motors. Second, the reasons for the water pump: the power is not matched, the small horse pulls the cart, and the motor runs overload for a long time, which makes the motor temperature too high; The motor with too frequent startup and short-time or intermittent working system shall work continuously. The starting times shall be limited, the thermal protection shall be correctly selected and used according to the rated value on the motor. The third reason is the motor body: the connection method is wrong, and the △ shape is wrongly connected into Y shape, which makes the temperature of the motor rise rapidly; Stator winding has phase to phase short circuit, turn to turn short circuit or local grounding. In case of light, the motor is overheated locally, and in case of serious, the insulation is burned out; The squirrel cage rotor is broken or defective, and the iron core temperature rises rapidly when the motor runs for 1 to 2 hours; If the ventilation system fails, check whether the fan is damaged, whether the rotation direction is correct and whether the ventilation duct is blocked; Bearing wear and rotor eccentric bore sweeping make the stator and rotor iron cores rub against each other and produce metal impact sound. The iron core temperature rises rapidly. In serious cases, the motor smokes and even the coil is burned. Fourth, the reasons for the working environment: the motor winding is damp or dust and oil stain are attached to the winding, resulting in reduced insulation. The insulation resistance of the motor shall be measured and cleaned and dried; The ambient temperature is too high. When the ambient temperature exceeds 35 ℃, the high inlet air temperature will make the temperature of the motor too high. Try to improve its working environment. Such as putting up a shed for sunshade, etc. Note: in case of failure due to electrical reasons, electricians with professional qualification certificates shall be invited for maintenance. People with a little knowledge shall not repair blindly to prevent personal injury accidents.
Deep well submersible pump
First, look at the difference between the current of the water pump running at this time and the current of normal operation. If it is smaller than the normal operation (basically 2\3 of the normal current), there will be problems such as impeller wear and blockage of the check valve at the top of the pump head. If the current is as large as usual, it is the leakage of pipe pad, pipe and pump body. If the current is greater than that during normal operation, it can be determined that it is the wear of vulnerable parts. In addition, if the cable is damaged, the water volume is as large as usual, but the current will become larger. The current of 3-phase 380V motor is generally 2.2A. The above reasons can be found by the repairman who often maintains the deep well pump.
The cavitation of water pump is caused by the vaporization of water. The so-called vaporization is the process of water from liquid to vapor. The vaporization of water has a certain relationship with temperature and pressure. Under a certain pressure, the water begins to vaporize when the temperature rises to a certain value; If the pressure drops to a certain value at a certain temperature, the water will also vaporize. This pressure is called the vaporization pressure of water at that temperature. If in the flow process, the pressure in a local area is equal to or lower than the vaporization pressure corresponding to the water temperature, the water vaporizes there. After vaporization, many small bubbles of steam and gas will be formed. When the bubble flows from the low-pressure area to the high-pressure area with the water flow, the bubble breaks under the action of high pressure, and the high-pressure water flows to the space occupied by these original bubbles at a very high speed, forming an impact force. Under the action of water hammer pressure, the metal surface forms fatigue and is seriously damaged. Therefore, the partial process of bubble formation, development and rupture resulting in material damage is called cavitation phenomenon.
Reasons for efficiency decline
- 1. Due to the scouring of water flow, the inner wall of the pump channel and the water surface of the impeller become rough and uneven, and the friction coefficient of the channel in the pump increases. In addition, the flow velocity of water in the pump is very large, and the head loss increases. Reduced hydraulic efficiency.
- 2. Due to the addition of drugs or water quality in front of the pump, there is serious scaling or corrosion in the pump shell. Serious scaling in the pump shell can increase the wall thickness of the pump shell by about 2ram, and the scale tumor is formed on the inner wall of the pump, which reduces the volume of the pump body, reduces the pumping capacity, roughens the flow channel and increases the head loss. Both passenger volume efficiency and hydraulic efficiency are reduced.
- 3. Due to casting defects, cavitation, abrasion, corrosion and chemical etching caused by water pump processing technology, cavities or cracks are generated in the pump channel, and vortices are generated during water flow, resulting in energy loss. Reduced hydraulic efficiency.
- 4. Cavitation on the impeller surface. As the negative pressure is generated when the blade runs behind the water surface, when the pressure PK < PVA, cavitation and honeycomb surface will be generated, and the pump blade will be subject to cavitation under the action of electrochemical corrosion.
- 5. Volume loss and mechanical loss. Due to the long service time of the pump, the leakage and resistance caused by mechanical wear increase, which reduces the volumetric efficiency and mechanical efficiency.
- The above reasons make the performance of the water pump worse. The operation efficiency can be reduced by 2 ~ 5%, and the pump efficiency can be reduced by more than 10% in serious cases.
Vibration cause analysis
Analysis on the causes of pump vibration there are many reasons for the vibration of units and pump house buildings. Some factors are related and interact. Generally speaking, there are mainly the following four reasons.
The motor is the main equipment of the unit. The internal magnetic imbalance of the motor and the imbalance of other electrical systems often cause vibration and noise. For example, during the operation of asynchronous motor, the radial alternating magnetic tension between stator and rotor caused by the harmonic magnetic flux interaction between stator and rotor teeth, or during the operation of large synchronous motor, the magnetic center of stator and rotor is inconsistent or the air gap difference in all directions exceeds the allowable deviation value, etc., may cause periodic vibration and noise of motor.
Strong vibration and noise will be generated due to unbalanced mass, rough manufacture, poor installation quality of rotating parts of motor and water pump, asymmetric axis of unit, swing exceeding allowable value, poor mechanical strength and stiffness of parts, wear and damage of bearing and sealing parts, and resonance between critical speed of water pump and natural frequency of unit.
The uneven flow velocity and pressure distribution at the inlet and outlet of the pump, the pressure pulsation of the working liquid at the inlet and outlet of the pump, liquid flow around, bias flow and flow separation, non rated working conditions and pump cavitation caused by various reasons are common causes of pump unit vibration. The rapid change of pressure in the water transmission pipeline and the action of water hammer caused by dynamic transition processes such as pump start-up and shutdown, valve opening and closing, working condition change and emergency shutdown often lead to vibration of pump house and unit.
Hydraulic and other aspects
Unreasonable design of water inlet channel of the unit or mismatch with the unit, improper submergence depth of water pump, and unreasonable startup and shutdown sequence of the unit will worsen the water inlet conditions, produce vortex, induce cavitation or aggravate the vibration of the unit and pump house. When the unit with broken siphon vacuum cut-off is started, if the air entrainment in the hump section is difficult, the siphon formation time is too long; The design of the racket door of the unit with broken racket door is unreasonable, opening and closing, and constantly hitting the racket door seat; Uneven settlement of the foundation supporting the water pump and motor or poor rigidity of the foundation will also lead to vibration of the unit.
When users choose water pumps, it is best to go to the sales points recognized by the agricultural machinery department and be sure to recognize the manufacturers. It is recommended to give priority to the purchase of water filled submersible pump, and see the brand and product quality certificate. Never buy “three noes” (i.e. no manufacturer, no production date, no production license) products, otherwise there will be problems and users will be helpless.
As users, due to the limitations of professional knowledge, it is difficult to make a decision. The best way is to consult experts in water pumps. You might as well consult some old water pump users, especially those with similar service conditions. It is a wise choice to buy products that are trusted by these users, reliable quality and more mature. At the same time, the use of single-phase pump or three-phase pump shall be determined according to the local power supply.
The high noise of the water pump may be due to the following reasons:
- (1) The impact of the rotary vane on the cylinder block, the residual volume of the water pump and the sound of the pressure oil in the exhaust dead gap;
- (2) Impact of exhaust valve plate on valve seat and support;
- (3) Echo and bubble burst sound in the box;
- (4) Bearing noise;
- (5) Noise caused by a large amount of gas and oil impacting the oil baffle;
- (6) Others. Such as noise caused by transmission, fan noise of air cooling water pump, etc.
- (7) Motor noise, which is a crucial factor.
Water leakage fault
- 1. The cooling water added into the cooling water radiator by the operator is seawater, resulting in damage to the internal water channel and external interface of the diesel engine. Therefore, when using the diesel engine, it must be operated in strict accordance with the provisions of the diesel engine.
- 2. The antifreeze added into the water supply radiator by the operator is highly corrosive, resulting in damage to the water channel components of the diesel engine.
- 3. The sealing ring is worn or aged, resulting in the sealing surface can not be sealed and water leakage.
1. Remove the damaged parts of the diesel engine, wash the water radiator and the water channel inside the engine body with fresh water, and replace the damaged diesel engine parts.
2. After assembly, adjustment and test run, the diesel engine returns to normal, and the fault is eliminated.
The methods of fuel water mixing include inlet pipe water spraying and emulsified diesel oil.
1. Intake pipe spray
The main function of intake pipe water spray is to absorb heat and dilute fuel density. When a small amount of water enters the combustion chamber and atomizes well, the oil droplets are broken into smaller oil droplets due to the “micro explosion” of water vapor, which promotes the formation and combustion of the mixture. In the combustion process, the maximum combustion temperature can be reduced due to the endothermic effect of water. For example, the mixed injection of water and oil can reduce the fuel density and further reduce the maximum combustion temperature, so the NOx emission is reduced. It should be noted that the water storage tank should be antifreezed in winter, and the water spray amount should be automatically adjusted according to the load.
2. Emulsified diesel
Water is mixed into diesel, i.e. emulsified diesel. Due to its “emblem explosion” effect, the fuel atomization is good, the well promotes the air in the combustion chamber to form a strong turbulence, the distribution of fuel and air is more uniform, and the generated soot is reduced. The water gas reaction of water vapor also reduces soot emission. In addition, emulsified diesel can reduce the maximum combustion temperature, so the generation of NOx is reduced.
Maintenance scheme of water pump
During the long-term operation of the water pump, there are often wear of the bearing housing of the water pump bearing frame, wear of the bearing position, crack fracture of the pump body, cavitation of the water pump, scouring wear and so on. After the above problems occur, the traditional solution of the enterprise is repair welding or machining repair after brush plating, but both of them have certain disadvantages: the thermal stress generated by repair welding at high temperature cannot be completely eliminated, which is easy to cause material damage and lead to bending or fracture of components; However, brush plating is easy to peel off due to the limitation of coating thickness, and the above two methods use metal to repair metal, which can not change the “hard to hard” coordination relationship, and will still cause re wear under the comprehensive action of various forces. In view of the above problems, contemporary western countries mostly use the repair methods of polymer composites, which have comprehensive properties such as super adhesion and excellent compressive strength. The application of polymer materials for repair can avoid disassembly and machining. There is no influence of repair welding thermal stress, and the repair thickness is not limited. At the same time, the metal materials of the product do not have concessions, which can absorb the impact vibration of the equipment, avoid the possibility of re wear, greatly prolong the service life of equipment components, save a lot of shutdown time for the enterprise and create great economic value.
Technical requirements for water pump
The so-called head refers to the required head, not the water lifting height, which is particularly important for the selection of water pump. The pump lift is about 1.15 ~ 1.20 times of the lifting height. If the vertical height from a water source to the water consuming place is 20m, the required lift is about 23 ~ 24m.
When selecting the water pump, the head on the nameplate of the water pump should be close to the required head, and the general deviation should not exceed 20%. In this case, the efficiency of the water pump is the highest, energy saving and more economical. If the lift on the nameplate is far less than the required lift, the water pump often can not meet the needs of users. Even if it can pump water, the water volume is pitifully small. On the contrary, when the high head pump is used for low head, the flow will be too large, resulting in motor overload. If it runs for a long time, the motor temperature will rise, and the winding insulation will gradually age and even burn the motor.
The requirements of horizontal water pump for service conditions are introduced.
Characteristics of horizontal water pump
The pump produced by the plant is suitable for pumping sewage and sludge in various harsh environments. The water pump is of down suction type, which can drain the surface water on the working surface, and the motor is a water filled different submersible three-phase step motor. Able to work in long-term diving or out of the water. Small floor area, convenient installation and use, reliable and durable, long service life. The following introduces the service conditions of horizontal water pump.
Service conditions of horizontal water pump
Horizontal water pump is a water lifting machine with motor and water pump directly connected into the water. It is mainly applicable to farmland irrigation, water supply and drainage projects of cities and industrial and mining enterprises.
Power requirements for horizontal water pump:
- 1. The rated frequency is 50Hz, and the rated voltage at the motor end shall be 380 ± 5% three-phase AC power supply (if the user’s voltage is 660V, special order is required)
- 2. The load power of transformer shall not exceed 75% of its capacity.
- 3. When the transformer is far from the well, the voltage drop of the transmission line shall be considered. For the motor with power greater than 45KW, the distance from the transformer to the wellhead shall not exceed 20m. When it is greater than 20m, the specification of the transmission line shall be two levels greater than that of the distribution cable, and the voltage drop of the transmission line shall be considered.
Water quality requirements for horizontal water pump:
- 1. Generally non corrosive clean water
- 2. Sand content in water shall not be greater than 0.01% (mass ratio)
- 3. PH value of pH is in the range of 6.5-8.5.
- 4. The chloride ion content in water shall not be greater than 400 mg/L
- 5. Hydrogen sulfide content shall not be greater than 1.5ml g/L
- 6. The water temperature shall not be higher than 20 ℃.
Summary of service environment and conditions of horizontal water pump:
- 1. Three phase AC power supply with power frequency of 50Hz and rated voltage of 380V or 660V (with allowable difference of plus or minus 5%).
- 2. The solid volume ratio of the conveying medium is less than 2%, and the density of the conveying medium is 1.2×10.
- 3. The temperature of conveying medium shall not exceed 40 ℃.
- 4. The pH value of the conveying medium is 4-10.
- 5. For the sewage submersible pump unit without sleeve, the electric pump motor is allowed to be exposed to the water surface for short-term operation of no more than 0.5 hours from the cooling state of the motor.
- 6. Based on the center of the impeller, the submergence depth shall not exceed 20m.
How to buy water pump
The flow of the water pump, that is, the water output, generally should not be too large, otherwise it will increase the cost of purchasing the water pump. It shall be selected as required. For example, the self-priming water pump used by the user’s family, the flow shall be smaller as far as possible; If users use submersible pumps for irrigation, they can appropriately select larger flow pumps.
- 1) We should choose pumps according to local conditions. There are three types of commonly used agricultural water pumps, namely centrifugal pump, axial flow pump and mixed flow pump. Centrifugal pump has high lift, but small water output, which is suitable for mountainous areas and well irrigation areas; The axial flow pump has large water output, but the head is not too high, so it is suitable for plain areas; The water output and head of mixed flow pump are between centrifugal pump and axial flow pump, which is suitable for plain and hilly areas. Users should purchase according to the local conditions, water source and water lifting height.
- 2) The water pump shall be properly selected. After determining the type of water pump, its economic performance should be considered, especially the selection of pump head, flow and supporting power. It must be noted that the head (total head) indicated on the water pump label is different from the outlet head (actual head) in use, because there will be a certain resistance loss when the water flows near the water delivery pipe and pipeline. Therefore, the actual head is generally 10% – 20% lower than the total head, and the water output is reduced accordingly. Therefore, in actual use, it can only be estimated according to 80% ~ 90% of the head and flow indicated on the sign. The selection of the supporting power of the water pump can be based on the power indicated on the sign. In order to make the water pump start quickly and use safely, the power of the power machine can also be slightly greater than the power required by the water pump, generally about 10% higher; If there is power, when purchasing the water pump, you can choose the matching water pump according to the power of the power machine.
- 3) Strict procedures should be followed to purchase water pumps. Check the “three certificates” when purchasing, that is, agricultural machinery promotion license, production license and product inspection certificate. Only when the three certificates are complete can we avoid purchasing obsolete products and inferior products.
Selection of number of sets
- 1. Generally, only one pump is used for normal operation, because one large pump is equivalent to two small pumps working in parallel (referring to the same head and flow), and the efficiency of the large pump is higher than that of the small pump. Therefore, from the perspective of energy saving, it is better to choose one large pump instead of two small pumps. However, in case of the following situations, the parallel cooperation of two pumps can be considered: the flow is large, and one pump can not reach this flow.
- 2. For large pumps requiring 50% standby rate, two smaller pumps can be changed to work and two for standby (four in total)
- 3. For some large pumps, pumps with 70% flow requirements can be selected for parallel operation without standby pumps. When one pump is overhauled, the other pump still undertakes 70% of the transportation in production.
- 4. For pumps requiring 24-hour continuous operation, three pumps shall be standby, one for operation, one for standby and one for maintenance.
Distinguish true from false
- First, the product packaging of the original pump or supporting manufacturer is generally standardized, with clear and formal handwriting, with detailed product name, specification and model, registered trademark, factory name, address and telephone number; The packaging of counterfeit parts is generally rough, and the printing of plant address and factory name is not clear.
- Second, the qualified water pump has smooth surface and good workmanship. The more important the spare parts are, the higher the processing accuracy is, and the more strict the anti rust and anti-corrosion of the packaging is. When purchasing, if the parts are found to have rust spots, or the rubber parts are cracked, lose elasticity, or there are exposed processing lines on the journal surface, they should not be the original accessories.
- Third, the appearance of inferior water pumps is sometimes good. However, due to the poor manufacturing process, it is easy to be damaged. When purchasing, you can see the quality of the accessory process as long as you observe the hidden parts such as edges and corners of the accessory.
- Fourth, some water pumps are renovated with waste parts. At this time, the old paint can be found as long as the paint on the surface of the parts is removed. It is best not to use such water pumps.
- Fifth, when the purchased spare parts are installed on the vehicle, it depends on whether they can be matched with other spare parts and have good matching. Generally, the original parts can be well allocated to the vehicle, while the inferior parts are difficult to cooperate well due to the poor process and large processing error.
- Sixth, in order to ensure that the assembly relationship of the water pump meets the technical requirements, some regular parts are coated with assembly marks to ensure the correct installation of accessories. If there are no marks or the marks are fuzzy and illegible, they are not qualified accessories.
- Seventh, the regular water pump assembly and components must be complete and intact to ensure smooth loading and normal operation. If small parts on some assemblies are missing, it is easy to start loading, which may be fake parts.
- Eighth, some important accessories, especially assemblies, are generally delivered with instructions and certificates to guide users in installation, use and maintenance. Fake assemblies generally do not have detailed installation instructions to guide these.
Parameter selection of water pump
Water supply booster station is an effective measure to alleviate the shortage of urban water supply pressure. Its core is to lift the pump station, and the core of the pump station is the pump. The selection of water pump not only affects whether the water supply booster station can work normally, but also directly relates to the operation cost of the pump station.
Centrifugal pump is usually used in domestic water supply pressurization station. Centrifugal pump has the advantages of simple structure, no pulsation of infusion, simple flow regulation and so on. According to the actual situation of the project, first select the category of centrifugal pump and consider it as follows.
- (1) Decide which pump to select according to the characteristics of the medium. Such as clean water pump, corrosion-resistant pump, or chemical process pump and impurity pump, etc. When the medium is highly toxic, valuable or radioactive and other substances that are not allowed to leak, consider selecting non leakage pump (such as shielded pump, magnetic pump, etc.) or double face mechanical seal with leakage collection and leakage alarm device. If the medium is volatile liquid such as liquefied hydrocarbon, low NPSH shall be selected, such as barrel pump.
- (2) Horizontal pump and vertical pump (including submerged pump and pipeline pump) shall be selected according to the on-site installation conditions.
- (3) Single suction pump, double suction pump or small flow centrifugal pump shall be selected according to the flow.
- (4) Single stage pump, multi-stage pump or high-speed centrifugal pump shall be selected according to the lift.
After the above items are determined, the appropriate pump series can be selected according to the characteristics of different series of pumps in various pumps and the conditions of the manufacturer. After the type, series and material of the pump are selected, the model of the pump shall be determined according to the samples and relevant parameters provided by the pump manufacturer.
Development trend of water pump
The requirements for the development of agricultural water pumps are to improve efficiency, reduce energy consumption and make full use of natural energy. Replacing multiple small pumps with one large pump can improve unit efficiency, save materials, reduce energy consumption and project cost, and facilitate automatic management. Therefore, various large axial flow pumps and mixed flow pumps are developing rapidly, with the maximum impeller diameter of 4.6m and 6.2m respectively, and the supporting power of up to 12500 kW. Mixed flow pumps tend to replace some high lift axial flow pumps and low lift centrifugal pumps. In terms of water extraction from deep wells, submersible electric pumps are mainly developed, with a maximum diameter of 1m, and some use 6000 V high-voltage motors with a maximum power of 2500 kW. Water wheel pump, wind pull rod pump, screw pump, diaphragm pump driven by human and animal power, piston pump and water pump specially matched with sprinkler irrigation equipment have also received varying degrees of attention in China and some other countries.
Energy conservation and emission reduction has now become the primary content of the outline of China’s economic development plan. In particular, it has put forward increasingly stringent emission reduction policies for high energy consumption in industries such as electric power, iron and steel, nonferrous metals, petrochemical industry and water treatment. As a fluid transportation equipment in industrial center, water pump occupies the primary part of energy consumption, which has become the primary problem to be solved in energy-saving operation.
The most commonly used driving mode of water pump is driven by motor. The energy-saving method of the pump is to make the pump unit (pump, prime mover and converter) operate at the highest power, so as to reduce its consumption of external input electric energy to the lowest point. The energy-saving of the pump is a comprehensive skill, which involves the energy-saving of the pump itself, the energy-saving of the system and the operation of application management.
The meaning of pump energy saving is serious: the pump is a large power consumer. According to the calculation of general machinery industry association, the pump power consumption accounts for about 20% of the national power generation. The promotion of pump power has a serious meaning on energy conservation and emission reduction.
Article 4 of the property management regulations of the State Council “the State encourages the adoption of new technologies and methods and relies on scientific and technological progress to improve the level of property management and service”. All along, power saving is one of the key operations of property and equipment management. With the continuous promotion of China’s urbanization construction, there are more and more high-level communities and properties. The high-efficiency and energy-saving water pumps to ensure energy-saving rate in shopping malls have become a hot product.
In response to the national demand for building a resource-saving society, the photovoltaic water pump has become a new research trend. The photovoltaic water pump system uses the lasting energy of the sun to work at sunrise and rest at sunset. It operates independently and reliably without personnel and public power grid. The system can be matched with modern energy-saving irrigation facilities such as drip irrigation, sprinkler irrigation, infiltration irrigation and micro wetting irrigation to solve the problems of domestic drinking water, farmland irrigation, soil and water conservation and desert control in remote and arid areas. The photovoltaic water pump system effectively saves water and electricity, greatly reduces the investment in traditional energy, and realizes zero CO2 emission, which is truly in line with the national social development strategy of building “resource-saving” and “environment-friendly”. Solar water pump, also known as photovoltaic water pump, is the most attractive way of water supply in sunny areas in the world, especially in remote areas without electricity. Using the solar energy available everywhere and inexhaustible, the system automatically works at sunrise and rests at sunset, without personnel supervision, and the maintenance workload can be minimized. It is an ideal economy A green energy system integrating reliability and environmental benefits. Photovoltaic water pump system is another new energy application system of CEC Solar Energy Research Institute after photovoltaic (wind power) power station, photovoltaic building integration and photovoltaic lighting system.
Source: Network Arrangement – China Pipe Fitting Manufacturer – Yaang Pipe Industry (www.epowermetals.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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