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