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