Variable speed hydraulic coupling and drive unit of hydraulic coupling

Transcription

1 Variable speed hydraulic coupling and drive unit of hydraulic coupling I. Model designation YO / / / Modificait on code Output speed of drive unit (r/min) Input speed of coupling or drive unit (r/min) Specification: effective diameter of running wheel of coupling (mm) P: split type; D: independent support; X: rotary housing; S: water medium; J: decelearation; Z: acceleration C: outlet adjustment; R: inlet adjustment; F: compound adjustment T: Variable speed type; L: clutch type; C: drive unit (composite structure of coupling and gear drive) Hydraulic coupling (a general standard term for all hydraulic couplings and drive units) II. Guide for type selection 1. According to the rated speed (i.e. the input speed of hydraulic coupling or drive unit) and required transmission power of motor, refer to the power characteristic curve (P-n) and technical parameter schedule in the catalogue to select the model and specification of hydraulic coupling and drive unit; 2. When selecting a drive unit for YOC z acceleration type coupling, first divide the rated speed (n T ) of working machine by the hydraulic efficiency (η y =0.97) of hydraulic coupling to calculate the speed (n B ) of pump impeller in the coupling, then divide the shaft power (P T ) of working machine by the hydraulic efficiency of hydraulic coupling to calculate the power (P B ) of pump impeller in the coupling. Select the required specification in the power characteristic diagram according to the values of P B and n B. 3. The coefficient design must take into account the efficiency loss of hydraulic coupling or drive unit and shaft coupling. When making type selection matching for variable speed coupling, the design margin of the rated power of motor relative to the shaft power of working machine is 1.04~1.06; when making type selection matching for drive unit of coupling, the design margin of

2 the rated power of motor relative to the shaft power of working machine is 1.06~ The rated slip ratio of hydraulic coupling is 1.5~3%, the range of transmission power listed in the technical parameter table is that corresponding to the rated slip ratio in high efficiency area, the selection of coupling with the transmission power beyond the lower limit in the technical parameter table will be favorable to improving the transmission efficiency, but will reduce the cost performance. 5. When the hydraulic coupling and drive unit are used for centrifugal machinery with M n 2, the range of speed regulation is 1~1/5; when they are used for constant torque machinery with M=C, the range of speed regulation is 1~1/3. 6. The characteristics of speed regulation when the hydraulic coupling is matched with different loads (see the attached characteristic curve diagram). 7. When making type selection, the rotational direction of equipment must be indicated, i.e. when viewing from the end of motor, the input shaft of coupling and drive unit rotates clockwise or counterclockwise. Typical load curve: 1. Constant torque load (e.g.: positive displacement pump, variable displacement compressor) 2. Decreasing torque load (e.g.: boiler feed pump at sliding pressure operating condition) 3. Parabolic torque load (damping parabola without back pressure pump, blower) 4. Decreasing torque load (e.g.: boiler feed pump at stable pressure operating condition) This characteristic curve diagram shows that: the functional relation formed by the transmission torque and transmission ratio of coupling when the position of scoop tube is different. The ideal speed ratio forms stable penetration between the torque curve and load curve. Torque curve of different drive unit vs. characteristic curve of variable speed hydraulic coupling Working area Parameter MK I, IV Starting working area MK torque S min II Speed regulating working area S min transmission torque III Load working area Required minimum slip S=(1-n 1 /n 2 )-100[%] n 1 = input speed n 2 = output speed III. Operating principle The hydraulic coupling is equivalent to a combination of centrifugal pump and hydraulic turbine, the hermetic working chamber formed between the pump impeller (centrifugal pump) and turbine (hydraulic turbine) is full of liquid (generally mineral oil). When the prime mover drives the pump impeller to rotate, the pump impeller is just like a centrifugal pump, which makes the liquid in the working chamber flow along the passage on the blade of pump impeller from inner edge towards outer edge and impact the turbine at high speed, thus the mechanical energy input by the prime mover is converted into the kinetic energy and pressure energy of liquid; under the impact of liquid flow, the turbine is started, and meanwhile drives the working machine to rotate, the turbine is just like a hydraulic turbine which converts the kinetic energy and pressure energy of

3 liquid into the output mechanical energy. Then, the liquid flows along the passage on the blade of turbine from outer edge towards inner edge and enters into the pump impeller again, thus beginning the next cycle. Through this kind of repetitive energy conversion, flexible power transmission is realized between the prime mover and working machine. IV. Speed regulation principle The speed regulation of variable speed hydraulic coupling is realized through the volume regulation of transmission medium. In the liquid storage chamber formed by the pump impeller, turbine and housing of coupling, there is a scoop tube which can slide radially. When the coupling rotates, due to the action of centrifugal force, a rotating liquid ring is produced in the liquid storage chamber, with certain pressure on the surface of liquid ring, thus making the liquid discharged from the liquid storage chamber through the opening of scoop tube. When the opening of scoop tube is located at the bottom of liquid ring, the liquid in the chamber will be totally discharged, the working machine is under no-load, low-speed or still condition; when the scoop tube is located in the middle part, the working machine operates at medium speed and at medium load; when the scoop tube is located on the inner edge of liquid ring, the working machine operates at full speed and at full load. The coupling can control the scoop tube through an electric actuator or hydraulic oil cylinder to change the thickness of liquid ring arbitrarily, thus changing the volume of the part of transmission medium which can directly tranmit the power, therefore, the coupling can realize stepless speed regulation. V. Application field and energy conservation principle of variable speed hydraulic coupling Table 15 Industry category Electric power Iron and steel 5.1 Application fields of variable speed hydraulic coupling (Table 15) Equipment using variable speed hydraulic coupling for speed regulation Boiler feed pump, circulating water pump, heating network circulating pump, slurry pump, coal slurry pump, nuclear power plant sodium pump, fan type coal mill, hammer type coal crusher, boiler forced draught fan, boiler induced draught fan, cooling fan, compressor, belt conveyor, etc. Converter dust removal fan, dust removal fan for molten iron pretreatment, blast furnace blower, blast furnace dust removal fan, cupola furnace blower, soaking furnace fan for rough rolling mill, heating furnace induced draught fan, electric furnace dust removal fan, coke guide and coal loader dust removal fan, sulfur dioxide fan, compressor, slag flushing pump, descaling pump, water supply pump, sewage pump, slurry pump, drainage pump, belt conveyor, etc. Purpose and benefit Stable no-load starting Mitigate the impact and torsional vibration, and avoid cavitation. Parallel operation with multiple drives Extend the service life of equipment, and reduce the failure rate of equipment Save about 20% of energy Stable no-load starting Mitigate the impact and torsional vibration, and avoid the surging of fan Wash the impeller to maintain it with the fan operating at low speed Extend the service life of equipment, and reduce the failure rate of equipment Improve the output

4 Non-ferrous metallurgical Cement Mining Chemical Light, textile and paper-makin g Petrochemic al Coal Transportatio n Municipal Blower for copper smelting converter, smoke exhaust fan and blower for nickel smelter, fan at calcining kiln tail of aluminum plant, blower and dust removal fan for zinc smelting, mud pump for aluminum or mine, water supply pump, compressor, sewage pump, belt conveyor etc. Kiln head and tail fan of rotary kiln, Roots blower for vertical kiln, slurry delivery pump for raw slurry of mines, belt conveyor, water supply pump, dust removal fan etc. Belt conveyor, mud pump, slurry pump, oil isolation pump, elevator, compressor, various types of fans and pumps, chemical slurry pump for mines, compressor, water supply and draingage pump and main fan for mine shaft. Raw material fan for phthalic anhydride workshop, water supply pump for chemical plant, sewage pump, enzyme preparation mixer, chemical granulator, belt conveyor, raw material crusher, sulphuric acid fan, coal gas fan Fan for lye recovery boiler of papermaking plant, air conditioning fan for textile mill, soybean meal roller press, fan for bagasse-pulverized coal boiler of sugar-making factory Gas compressor, injection pump, water injection pump, pipeline transportation pump, charge pump, pipeline compressor, water treatment pump, ship loading pump, crude oil charge pump, refrigerating compressor, CO 2 compressor, propane compressor, hydrogenation unit, hydrogen circulating unit, moisture trap, oil pump for oil refinery, oil shaft drill jumbo, cooling fan for well drilling Belt conveyor, downhill belt conveyor, dust removal fan, main fan for mines, high-pressure water pump for hydraulic coal mining Speed regulation of main drive and cooling fan of internal combustion locomotive, drive of shunting locomotive, air conditioning fan for subway, speed regulation, shunting etc. of marine engine Water supply pump of waterworks, municipal sewage pump, high-rise building water supply pump, rubbish sludge slurry pump, fan and water pump for rubbish power plant, water pump for intermediate water treatment, coal gas blower, boiler house fan, water pump and heating network Save about 40% of energy Stable light-duty starting Mitigate the impact, and isolate the torsional vibration Extend the service life of equipment, and reduce the failure rate of equipment Improve the output Save 15%~35% of energy Stable no-load starting Parallel operation with multiple drives Hydraulic slowdown brake Save 15%~35% of energy Save 15%~35% of energy Save 15%~25% of energy Save 20%~40% of energy Harmonize multiple machines for balanced drive Stable light-duty starting Save 10%~25% of energy Harmonize multiple machines and balance the load for synchronous operation Stable light-duty starting, with stable parallel operation Save 10%~20% of energy Save 10%~20% of energy

5 Military equipment circulating pump for communication heating Speed regulation of cooling fan for military vehicle and battle field oil pump carriage Save energy 5.2 Energy-saving principle of hydraulic coupling for speed regulation The energy conservation benefit of using hydraulic coupling for speed regulation is represented in the following five aspects: 1 Reasonable matching and reduction of installed capacity: because variable speed hydraulic coupling enables no-load starting of the motor with large inertial load, the safety factor can be appropriately reduced in the type selection of motor in order to avoid the phenomenon of strong horse pulls a small cart. Compared with the original rigid drive, one motor base number can be reduced at least, and the installed capacity can be reduced by 10%~25%, because of economic and reasonable matching, the energy conservation can be realized. 2 Reduction of starting power consumption of motor. Because hydraulic coupling solves the difficult problem of start of large-inertia machinery, the starting current of motor is low, the starting duration is short, the impact on electric grid is small and the power consumption upon starting is low. Especially for multi-motor drive equipment, because application of hydraulic drive can make motors started in delayed time sequentially, it can avoid impact of simultaneous starting of multiple motors on electric grid, reduces starting current and thus achieves substantial energy conservation of hydraulic coupling for the machinery with long starting time and frequent starting. 3 Reduction of equipment failure rate and improvement of equipment service life. Because hydraulic coupling has the functions as of flexible drive, impact mitigation, isolation of torsional vibration, overload protection etc., the application of hydraulic coupling as the drive can improve drive quality, reduce equipment failure rate and extend equipment service life. For example, after the dust removal fan has been used for a period of time, it will lose balance due to scaling on the blades. While application of hydraulic coupling for speed regulation allows flushing the blades with high pressure water at a low rotating speed, thus enabling the fan to run often under balanced condition and thus increase its service life. Another example, the wear amount of impeller of slurry pump is proportional to the cube of its speed, application of hydraulic coupling for speed regulation to make the slurry pump run at reduced speed when it does not require high flow rate, therefore, it can reduce impeller wear and extend service life. 4 Increase of output. After application of hydraulic coupling for speed regulation, the equipment failure rate and downtime are reduced, therefore, the output increases accordingly. For example, Shanghai Baosteel No. 3 plant used variable speed type hydraulic coupling on the dust removal fan of 25t converter for variable speed running, the major overhaul period of the fan was increased from 329 furnances (times) to 898 furnaces (times), an increase in production of t steel was achieved annually due to reduction of downtime, and the purity and quality of recovered coal gas were somewhat improved. 5 Energy conservation due to speed regulation. The energy conservation and benefit in above four aspects all can be achieved with any equipment adopting the hydraulic coupling drive. Whereas energy conservation through speed regulation can only be achieved when applied on centrifugal machinery. It can be known from above analysis, the flow rate of centrifugal

6 machinery is proportional to the first power of rotating speed, whereas the power is proportional to the cube of rotating speed, therefore, after the speed is reduced, the power is reduced by a great margin. Wheereas application of hydraulic coupling on constant-moment machine cannot achieve energy conservation, instead, it will cause power consumption due to reduced efficiency.