| MECHANICAL VACUUM BOOSTERS:-Mechanical | | | | easily by the Mechanical Boosters, since the volumetric |
| Vacuum Boosters are dry pumps that meet most of | | | | displacements/pumping speeds are insensitive to the |
| the ideal vacuum pump requirements. They work on | | | | inlet & outlet working pressures.Typical Booster |
| positive displacement principle and are used to boost | | | | Installation |
| the performance of water ring /oil ring /rotating vane | | | | (1) Evaporator (2) Gauge (3) Condenser (4) |
| piston pumps and steam or water ejectors. They are | | | | Mechanical Booster |
| used in combination with any one of the above | | | | (5) backup PumpEverest ................. Leaders in Vacuum |
| mentioned pumps, to overcome their limitations. | | | | Booster Technology Boosters for Vacuum Process |
| Vacuum booster pumps offer very desirable | | | | © Everest Transmission January, 2005.Calculating |
| characteristics which make them the most cost | | | | the Pump Capacity: - |
| effective and power efficient option.The major | | | | Based on the fundamental gas laws PV= RT, an |
| advantages are:-(a) Can be integrated with any | | | | expression can be derived for Volumetric Flow Rates |
| installed vacuum system such as Steam Ejectors, | | | | required for pumping different vapors/gases. Based on |
| Water Ring Pumps, Oil Sealed Pumps, Water Ejectors, | | | | the Mass flow rates one can estimate the pump |
| etc.(b) The vacuum booster is a Dry Pump as it does | | | | capacity required.V = R . Tgas / P Q1/M1 + Q2/M2 ............. |
| not use any pumping fluid. It pumps vapor or gases | | | | Qn/Mn |
| with equal ease. Small amounts of condensed fluid can | | | | Where V = Inlet Volume flow rate m3/hr. |
| also be pumped.(c) Vacuum boosters are power | | | | R = Universal gas Constant, 83.14 mbar m3/ Kgmol x |
| efficient. Very often a combination of Vacuum | | | | ºK |
| Booster and suitable backup pump results in reduced | | | | Tgas = Gas/Vapor abs. Temp, in ºK |
| power consumption per unit of pumping speed. They | | | | P = Process Absolute Pressure in mbar |
| provide high pumping speeds even at low pressures.(d) | | | | Q1, Q2, Q3 = Gas / Vapor flow rate, in Kg/hr. |
| Boosters increase the working vacuum of the | | | | M1 , M2 ,M3 = Molar mass, in Kg/mol. of gas |
| process, in most cases very essential for process | | | | vapor.Booster Operation: |
| performance and efficiency. Vacuum Booster can be | | | | Power Constraints restrict the total differential |
| used over a wide working pressure range, | | | | pressures across the booster. This demands to |
| from 100 Torr down to 0.001 Torr (mm of mercury), | | | | ensure the total differential pressure across the |
| with suitable arrangement of backup pumps.Everest | | | | Booster must not exceed the rated limits. This can be |
| ...................... Leaders in Vacuum Booster Technology | | | | ensured by any of the following means:-1.) Manual |
| Boosters for Vacuum Process © Everest | | | | method:- Initially the fore pump is switched on until the |
| Transmission January, 2005.(e) It has very low pump | | | | required cut in pressure is achieved and there-after the |
| friction losses, hence requires relatively low power for | | | | booster is switched on.2.) Auto method:- Installation of |
| high volumetric | | | | mechanical By-pass arrangement across the booster |
| speeds. Typically, their speeds, at low vacuums are | | | | or hydro kinematic drive or Variable Frequency Drive |
| 20-30 times higher than corresponding vane | | | | (VFD). In this arrangement, the booster and fore pump |
| pumps / ring pumps of equivalent power.(f) Use of | | | | can be started simultaneously from |
| electronic control devices such as Variable Frequency | | | | atmosphere.Advantages of using Electronic Variable |
| Control Drive allow to modify | | | | Speed Control Device |
| vacuum boosters operating characteristics to | | | | Electronic A.C Variable Frequency Control Drives are |
| conform to the operational requirements of the prime | | | | most preferred devices used to regulate the |
| vacuum pumps. Hence they can be easily integrated | | | | Booster speed to match the varying load conditions |
| into all existing pumping set up to boost their | | | | of the process. These drives enhance the overall |
| performance.(g) Vacuum boosters don't have any | | | | performance of the Boosters and offer various |
| valves, rings, stuffing box etc., therefore, do not | | | | advantages for the trouble free operation.The major |
| demand regular maintenance.(h) Due to vapor | | | | advantages are: - |
| compression action by the booster, the pressure at the | | | | 1. Booster can be started directly from atmosphere. |
| discharge of booster (or inlet of backup pump) is | | | | Everest ................... Leaders in Vacuum Booster |
| maintained high, resulting in advantages such as low | | | | Technology |
| back streaming of prime pump fluid, effective | | | | Boosters for Vacuum Process © Everest |
| condensation even at higher condenser temperatures | | | | Transmission January, 2005. |
| and improvement of the backup pump efficiency.The | | | | 2. No need for separate pressure switch, by pass line |
| Table below gives a rough estimate of how the | | | | or offloading valves. |
| boosters enhance the working vacuums of the | | | | 3. Considerable savings in power. |
| processes when installed in combination with various | | | | 4. Prevents over-heating of Boosters. |
| types of industrial vacuum pumps currently used in the | | | | 5. Protects the Booster against overload and |
| industry. They can effectively replace multistage | | | | excessive pressures. |
| steam ejectors, resulting in considerable steam savings | | | | 6. Offers complete protection to motor against over |
| and reduced loads on cooling towers. Mechanical | | | | voltage, under voltage, over current, |
| Vacuum Boosters are versatile machines and their | | | | Over-heating, ground fault. |
| characteristics depend largely on backing pump. | | | | 7. Eliminates the needs of separate starter and |
| Various types of backing pump can be used, | | | | overload relays for the Motor. |
| depending upon the system requirement and ultimate | | | | 8. Automatically adjusts the speed of Booster |
| vacuum needs. | | | | between low and high range set giving high |
| However, the final vacuum is governed by the suitable | | | | pumping speeds with relatively low input power.The |
| selection of the backing pump and booster | | | | Electronic Variable Frequency Control Drive is a |
| arrangement. The table below gives a broad range of | | | | microprocessor based electronic drive which is |
| vacuum achieved with various backing pumps | | | | specially programmed to meet the demands of the |
| combinations.Vacuum Pump Expected vacuum | | | | Booster allowing it to operate directly from |
| Vacuum on installation Range of Booster (single stage) | | | | atmosphere along with suitable fore pump. |
| Single Stage Ejector 150 Torr 15 - 30 Torr | | | | Conventionally, Boosters can be started only after |
| Water Ejector 100 Torr 10 - 20 Torr | | | | achieving fore vacuum in the range of 30 - 100 Torr, |
| Water Ring Pump 40 - 60 Torr 5 - 10 Torr | | | | as they are not recommended for direct discharge into |
| Liquid Ring Pump 20 - 30 Torr 2 - 5 Torr | | | | the atmosphere. Use of Pressure Switch, Hydro |
| Piston Pumps 20 - 30 Torr 2 - 5 Torr | | | | kinematic drive and by pass valves is necessary to |
| Rotary Piston Pumps 0.1 Torr 0.01 Torr | | | | prevent the overloading of the Booster. However with |
| Rotary Vane Oil Pump 0.01 - 0.001 Torr 0.001 - 0.0001 | | | | the installation of Electronic Variable Frequency Control |
| Torr. | | | | Drive all the conventional methods can be bypassed |
| Everest ................ Leaders in Vacuum Booster Technology | | | | since the drive is programmed to regulate the Booster |
| Boosters for Vacuum Process © Everest | | | | speed automatically, keeping the load on motor within |
| Transmission January, 2005.For example, if a process | | | | permissible limits. This allows the Booster to start |
| is using water ring Pump, the estimated working | | | | simultaneously with backup pump. When the |
| vacuums would be of the order of about 670-710 | | | | backup-pump and Booster are started the drive |
| mmHg gauge (90-50 mmHg abs.), largely depending on | | | | reduces the Booster speed to the pre-set levels and |
| the water temperature and pump design. When a | | | | as the vacuum is created the Booster speed picks up, |
| Booster is installed prior to the water ring pump, in | | | | reaching the final pre-set speed, giving most optimum |
| series, the vacuum levels of the order of 5-10 Torr can | | | | performance over the entire range. Since all the |
| be easily achieved. In a Multi-Stage booster installation, | | | | parameters are easily programmable, one can adjust |
| vacuum levels of the order of 0.5 Torr & better can | | | | the booster pumping speeds to match the system |
| easily be expected. Mechanical Boosters offer a | | | | requirements easily and quickly. The drive limits the |
| completely dry pumping solution and do not add to any | | | | current to the motor and safeguards the motor against |
| vapor load, unlike steam ejectors, and therefore, do not | | | | over voltage, under voltage, electronic thermal, |
| require large inter stage condenses. At low vacuums, | | | | overheat ground faults. i.e. protects the motor against |
| higher pumping speeds are required to maintain the | | | | all possible faults. |
| through-put, since the specific volume increases with | | | | External computer control over all aspects of booster |
| the increase in vacuum. Vacuum boosters enhance | | | | performance is possible via RS485 serial interface built |
| the pumping speeds by about 3-10 times depending | | | | into the drive electronics. This enables the Booster to |
| upon the selection by virtue of which one can expect | | | | be integrated into any computer-controlled operating |
| higher process rates and through-puts. The drawbacks | | | | system.To know more about this site visit this site: is |
| of steam ejector system such as sensitivity to motive | | | | author and designer of the guide area of blowers. |
| fluid pressures and discharge pressure are overcome | | | | |