In the past, large feed pumps of domestic production were completed, predominantly, tooth-type clutch (MH). In recent years, there is a tendency to replace staff gear couplings nutrient pumps with both electric – and a turbine drive for the elastic coupling plate (MUP), initiated by the major power generating enterprises of Ukraine and CIS countries. The largest thermal power plant in Ukraine and Russia are continuing a systematic replacement of the Ministry of Health in the MUP for mechanical requirements, Make sure to experience the obvious benefits of the past. Systematizing the main advantages of CBM.
- Radical reduction of static and dynamic loads on the bearings of the shafts
tooth-type clutch, having mobility in all directions in unloaded condition, when loading torque creates considerable axial and radial forces and the moments of reaction to the relative displacement of the shafts by friction forces engaged. And:
- the value of reactions is great, because due to the large amount of force engaged, transmitting torque
- significant reactions occur even at the slightest, the order of micrometers, shaft misalignment;
- while rotating shafts are impulse responses, stroke character, because due to the nonlinear forces of dry friction (even at normal Lubricant).
The consequence of these factors are large radial and axial loads on the bearings of the shafts, and dynamic, impact nature. These loads lead to a decrease in reliability and life, virtually rapid failure of the support bearing assemblies.
The elastic plate clutch It compensates for the relative displacements of the shaft solely by the elastic deformation of the elastic element packages, so:
- the value in the radial reactions, angular and axial shaft misalignment is negligible;
- reactions are minor, even with substantial misalignment of shafts;
- reactions are static in nature, dynamic component is virtually absent.
Thus, CBM provides the use of a radical reduction of static and dynamic loads on the bearings of the shafts, which leads to increased reliability and life of the rotor poles (and indirectly – and seals by reducing the axial and radial displacement of the rotor).
- Reduced noise vibration and
Reducing the dynamic loads on connected shafts and bearings when replacing the Ministry of Health on the MUP, It leads to a significant reduction of machine vibration. Made “NTC” vibration monitoring treatment outcomes over 100 centrifugal pumps of various types, which conducted the replacement clutches, It gives the following statistical results.
The average values of vibration parameters on the pump bearings
|№||The direction and point of measurement||Vibration Parameter name||Initial value (tooth-type clutch)||The value after replacing the clutch plate on the elastic||Reduced vibration parameter after replacing the clutch, times|
|1||Werth. Motor direction t.№1||RMS vibration||1,7||1,1||1,55|
|PEAK vibration (up to 1000 Hz)||4,8||1,6||3,00|
|2||Werth. Motor direction t.№2||RMS vibration||2,3||1,6||1,44|
|3||The horizontal direction of the motor t.№1||RMS vibration||2,2||1,6||1,38|
|4||The horizontal direction of the motor t.№2||RMS vibration||2,5||1,7||1,47|
|5||The axial direction of the motor t.№2||RMS vibration||1,6||1,4||1,14|
|6||Werth. Pump direction t.№3||RMS vibration||4,1||0,9||4,56|
|7||Werth. Pump direction t.№4||RMS vibration||3,6||0,9||4,00|
|8||Horizontal Pump direction t.№3||RMS vibration||2,7||1,2||2,25|
|9||Horizontal Pump direction t.№4||RMS vibration||1,8||1,0||1,80|
|10||The axial direction of the pump t.№3||RMS vibration||2,1||1,0||2,1|
Comments to the results given:
- CBM application leads to a significant reduction of vibration parameters;
- reduction in peak velocity and RMS (rms) vibrouskoreniâ average, at 4-5 time, It is a confirmation of the radical reduction of dynamic loads on components of machine shafts by the MUP in comparison with the MoH;
- decrease in the value of the average RMS vibration, more than 2 fold, in some cases, would “cram” the machine in tough international standards for permitted vibration parameters.
- Stable long-term balance of MUP.
Mobile connection mating parts gear couplings are made on loose fit. Radial clearance or backlash leads to uncertainty mutual radial position relative to the coupling of the spacer coupling halves on both sides,, Consequently, for imbalances, random in magnitude and direction. The random nature of the magnitude and direction of imbalance, varying from start to start, It does not allow any balance the clutch assembly, nor even compensate its way “podbalansirovki in own bearings”.
for example, mass spacers clutch gear pump PE 580-195 is 80 kg, and possible radial play in Teeth – up 227 m ( ! ). imbalance, due to the random offset spacers mass center by radial play, can make up for the clutch commissioned to 9080 g * mm, and the accuracy class of the coupling assembly of balancing mass at the coupling half 30-45 kg and speed 3000 rpm can not be guaranteed better G40 ( ! ) according to GOST ISO 1940-1-2007.
But when the clutch, accompanied by friction in the gearing, regardless of its method of alignment, inevitable wear and the growing increase in the radial play, which lead to the rising increase in coupling imbalance and an increase in vibration unit.
Unlike gear, in the elastic plate clutch mutual alignment of parts is precise landings on smooth surfaces and cylindrical not broken during operation. for example, for coupling MUP2-2100, used in the same unit with the pump PE 580-195, possible imbalance is limited to 1200 g * mm, and the class balancing accuracy can be achieved at the level G2,5.
- Coupling MUP has a stable characteristic of axial force dependence on the magnitude of the shafts axial displacement, This characteristic practically does not depend on the transmitted moment, and also guarantees the reliability of detuning from the axial resonances of the spacer. This is especially important for large nutrient units, since large motors with sleeve bearings, usually, no support units, which in combination with the use of gear couplings leads to typical problems with uncontrolled axial stroke engine rotors – friction in the axial restrictive clamps, they wear, drawdown automatic overheating etc.
- increased reliability, and resource performance clutch MUP.
When designing the MUP strength calculation is carried out on an unlimited resource, and the lack of wearing parts suggests the reality of achieving coupling of the resource without repair, an equal share of the unit, taking into account current and capital repairs. According to our company, subject to the conditions of use of passport, Most of our clutches MUP work properly from the beginning of their production in 1995 year without replacement of the elastic members and other components. Thus, in addition to the alleged reduction of the cost of the life cycle of the clutch CBM, MH replacement on CBM will lead to some improvement in aggregate indicators of reliability.
CBM sleeves advantage is the absence of need for lubrication and any maintenance during operation, except for periodic inspection of the state of the elastic elements during routine maintenance of the unit.
Thus, implementation of CBM in the feed pump to replace the Ministry of Health, we find it, because it leads to an improvement of important technical characteristics of the entire pump unit.