Monday, October 24, 2011

Mechanical Booster Pumps

EVEREST has introduced  Mechanical Booster Pumps to meet the growing demand of the Vacuum Process Industry where fast pump down times are required and energy usage concerns rule out any alternative pump selection.

Everest Boosters pumps  (ROOTS TWIN LOBE TYPE) combine high pumping speed with relatively low power consumption. When such Booster pumps are used in combination with Oil sealed rotary  or Water ring pumps , the speed  and ultimate vacuum of the combination can be increased by TWO to TEN times.. They reduce the effect of oil contamination (back streaming). Rotary Pumps have a limitation to Size, Pumping Speeds, and Temperature rise and consume relatively large amount of power since there is  a continuous friction between the vanes and the casing. A combination of small rotary pump and Everest Booster overcomes the above limitations and gives:- 

  1. High pumping speeds
  2. Higher ultimate vacuums
  3. Low power consumption per unit pumping speed
  4. Prevents oil back streaming
  5. Improvement in overall pumping efficiency
Everest Vacuum Boosters are import substitutes, developed specially to boost the performance of the vacuum pumps, in low-pressure range, where Rotary vacuum pumps have poor volumetric efficiency.  Everest Boosters operate into a fore vacuum created by single or double stage Rotary Pumps (oil sealed or Water ring) . Everest Boosters are capable of moving large quantity of gas at low pressures, with far smaller power consumption than for any other equipment now available. 

The internals of a Booster are totally free of any sealant fluid, and therefore the pumping is dry. Also because of the vapor Compression action by the booster, the pressure at the inlet of the fore pump is relatively high, resulting in higher volumetric pumping efficiency & low back streaming of sealing oil. Everest Twin Lobe Boosters are used in series with fluid sealed Rotary pumps/any other suitable fore pump to achieve higher speeds and lower ultimate pressures. Since the rotors in a Booster rotate within the casing with finite clearances, no lubrication of the internals is required and the pumping is totally oil free.

Everest Twin Lobe Boosters are used mainly in two modes: -
  • Compression mode
  • Transport mode
In compression pumping, the general application, a booster is placed in series with a rotary pump whose rated speed is much lower than the booster speed. The ratio of Booster speed to pump speed is termed as STAGING RATIO and the ratio of Booster outlet pressure to inlet pressure is COMPRESSION RATIO.

In compression mode the staging ratio ranges between 2 - 15 while the compression ratios achieved range between 10-40, depending upon combination selection. Initially, pumping is initiated at atmospheric pressures by Rotary pump/Fore pump and after achieving the recommended cut in pressure the booster is switched on. A bypass line around the booster may be provided for the initial pump down period. Boosters with hydrokinematic drive/Variable Frequency control are also available which allow simultaneous start-up of the booster & the fore pump. This initial pumping by fore pump is necessary since considerable heat is generated by pumping gas at high pressures with the booster and the power input is also considerably higher. For this reason the booster is generally switched on at cut-in pressures of 20-60 Torr. A suitable vacuum switch can be installed between the booster & the fore pump, set for cutin pressure, so that the booster is switched on only on achieving the designed cut-in pressures. However, for short duration the booster can with-stand excessive differential pressure across it. The Booster-Rotary Pump combination are generally recommended when speed of 3000 LPM or  higher are required since the combination is most economical and power saving than any rotary pump of similar capacity. 

As evident from the Typical Performance Curve, booster is most effective in the pressure range of 1 -0.001 Torr having high pumping speeds and relatively low power consumption for this range.  A Typical performance curve is drawn for a Booster combination indicating the individual and combination performance with single stage & double stage rotary pump.

In transport mode pumping, the Booster is used in series with the rotary pump with staging ratio 1. Both the pumps are started simultaneously at atmospheric pressures since the critical pressure drop can never exceed. This combination effects higher ultimate pressure without much increase in pumping speed.  However, throughput at lower pressures increases resulting in higher ultimate pressure. 

Boosting the performance of diffusion pump systems
Improving the quality of lamps
Use in vacuum heat treatment and degassing
Use in drying application
Use in distillation
Use in gas re-circulation and gas pressure boosting
Use in semi – conductor processing

The use and application of Everest Boosters in Industry:  Vacuum Roots Blowers are widely used in the industry. Until recently their use in India was restricted because the item was imported and therefore very expensive. However, for the past few years Everest Blowers have been making the item and its usage has increased by leaps and bounds.  Today there are hundreds of installations using this product.  So this is a good time to look at various applications and see how Everest Boosters can improve performance and reduce energy costs.

Boosting the performance of Diffusion Pump Systems:  Vacuum metallizing plants are widely used to produce a vast range of metallized plastic/glass/metallic  objects, such as reflectors, mirrors, clock and radio cabinets.  A typical plant is shown in Figure before.  For fast production, a typical cycle time is 6 to 10 minutes, though times in excess of 30 minutes are not unknown.  A series combination of a rotary oil-=sealed mechanical pump and a Diffusion pump are generally used.  The problem is that in the pressure range 10 –3  Torr to 1 Torr, the speed of both the pumps is very low, hence pump-down times are generally slow.  A look at the speed characteristics of typical Oil-Sealed Rotary Pump will show that the pump speed rapidly starts falling at pressures below one Torr.  The speed of the diffusion pump starts to fall rapidly at pressures above 0.001 Torr.  Hence, in the transition pressure range of 0.0001 to 1 Torr both rotary and diffusion pumps perform well below their optimum levels.  The consequence of this is that the overall process cycle is lengthened.  This results in high energy and overhead costs.  Everest Booster has its peak pumping speeds in the pressure range of 0.001 Torr and 1 Torr.  Further because there is little friction in the rotating parts, high pumping speeds are possible at low power consumption.  In the transition pressure range Everest Booster can provide five to ten times more pumping speed than the Rotary Pump of the same HP.  Thus, to boost the performance of a Diffusion Pumped system, the modern trend is to use a Mechanical Booster between the rotary pump and diffusion pump.  Everest Vacuum Booster inserted between the Diffusion and Rotary pump provides a high or boosted pumping speed and thereby enables a fast pump-down process cycle.  The productivity improvement can be as high as 100% to 200%.  Advantages of using Everest Booster.

  1. Higher pumping speed by a factor of 5 to 10 times that of the rotary pump.
  2. Power Saving: The Everest Booster, by virtue of speed enhancement and shorter process cycles, saves power.
  3. Long service life and very low maintenance because there are no rubbing/mechanical friction between internals.
  4. Less frequent oil changing.
Improving the Quality of Lamps:  Process lines for the production of tube lights, miniature and auto lamps
typically require vacuums of the order of 0.01 to 0.001 Torr.  The requirement of high-speed machine operation where frequent leakages occur due to breakage and wear and tear places heavy demands on pumping systems. The consequence of this is that rotary pumps are frequently replaced due to deterioration in performance. Everest Booster improves matters by:

  1. Increasing the speed of the Rotary pumps by a factor of 3-5 times.
  2. Enables less frequent maintenance of the rotary pump, since it can deliver less than peak performance and still provide adequate/superior vacuum to the machine.
  3. In the production of vacuum lamps using Everest Booster substantially improves the product quality and life.
Use in Vacuum Heat Treatment and Degassing:  Vacuum annealing is necessary for those special steels, which would get embrittled due to incorporation of oxygen if heated in air.  Heating under vacuum and subsequent quenching in inert gas is sometimes the only method that is possible for treatment of such steels.  Since heating imposes considerable gas loads on the rotary pump, Everest Booster provides the benefit of being able to handle these heavy gas loads at low pressures in an economical way.  A major advantage with Everest Booster is easy and instantaneous startup, unlike diffusion pump or oil booster, which requires substantial heat up time (and consequent waste of energy) to come up to a state of operational readiness.

Use in Drying Applications:  Drying or removal of moisture is an important industrial process.  The  applications range from dehydration of foods products to removal of moisture from cable and transformer oils.  The problem of moisture removal is especially acute  at low pressures where even a small amount of water results in a large release of water vapor.

Everest Boosters are capable of providing pumping speeds of the order of 5,000 liters per minute to 1,50,000 liters per minute and more at low pressures in the range of 0.001 to 50m Torr, at very modest power requirements as compared to oil booster pumps and steam ejectors, providing efficient solutions.

Use in Distillation:  In distillation applications Everest Booster Pump and water – ring / oil-sealed rotary
vacuum pump combination can provide low pressure and high pumping speeds more economically than steam ejectors.  The outstanding advantage of using Everest Booster is:
Negligible environmental pollution compared to steam ejectors
  • Dry operation- This means that no working fluids are used in the operation of the pump and therefore there are no problems of contaminations of or by the condensate
  • Instantaneous startup and shut down
  • High energy efficiency per unit of pumping capacity
Use in Gas-recirculation and Gas Pressure Boosting:  In systems that re-circulate gases, such as lasers, heat exchangers and chemical process plants, the use of Everest Booster is essential to overcome the pressure losses of pipeline and sealed chambers.  Everest Boosters have the outstanding advantage that they offer dry operation, which can be totally sealed off from the surrounding atmosphere.

In long pipelines, Everest Boosters can be used to boost the gas pressure. This reduces the requirement of high driving pressures to pump gases through pipes and because Everest Booster is totally sealed and oil free, even inflammable gases such as biogas, L.P.G, C.N.G, etc., can be easily pumped.  

Use in Semi-Conductor Processing:  Mechanical Boosters are used in Semi-conductor processing industry as a part of dry pumping / oil-free pumping systems.  Such systems are necessary to handle the high corrosive and often poisonous gases used in semi-conductor production.  The main advantage of the Everest Booster is its sealed – off operation and long life between maintenance procedures.  

Typical Installations:-

Typical arrangement of Booster installations are shown. The booster can be directly mounted on the suction of the fore pump or mounted on a base frame with connection  to fore pump.  For applications involving pumping of CONDENSABLE VAPOR  like in distillation, a suitable condenser can be installed in between the Booster & Fore pump. In such cases the Fore pump size can be reduced drastically, to match  the NON-CONDENSABLE load.

Initially the fore pump is switched on until the required cut in pressure is achieved and there-after the booster is switched on. In case mechanical b-pass arrangement across the booster or hydrokinematic drive or Variable frequency drive is used , the booster and fore pump can be started simultaneously from atmosphere.

Tuesday, October 18, 2011

Report on Everest vacuum pumping system Intalled in xyz pharma ltd. for replacement of steam jet ejector

The Vacuum Pumping system manufactured by M/s Everest Blower Systems has been successfully installed at M/s XYZ Pharma Ltd. The Job has been done to the entire satisfaction of XYZ Pharma Ltd.


Day1 (21-06-2011) The Team Everest reached the site and the material was unpacked and shifted to the exact site of installation. Meeting held with Mr. X(AGM Plant) and Mr. Y (Sr. Manager Utilities) and a team of
Engineers is assigned to us for the commissioning of the Vacuum Pumping System.
Guidelines given to the engineers of M/s XYZ Pharma Ltd. regarding the construction of the pipelines and other electrical parameters required.

Day2 (22-06-2011) Pipelines were found to be ready but some other changes were suggested and the work started again immediately in the presence of all officials  from supplier as well as users side with the cooperation of Maintenance Team from XYZ.
Day3 (23-06-2011) The Vacuum Pump was connected but was not started as to check the parameters of the Present Setup in Reactor which was having a Water Ring Pump of 20 HP connected with 2 Steam Jet Ejectors and a Post Everest Mechanical Vacuum Booster of 7.5 HP motor.

The batch in reactor was completed in 15 Hrs 30 Mins.
The Table from Production Department is as below:

As evident from the reports attached prepared by XYZ Production deptt. Everest VPS is giving high vacuum of the order of 710-720 mm of Hg thus reducing distillation temperature to 20-25 deg. Celcius. Against the vacuum of 670 mm of Hg achieved by XYZ Steam Jet Ejector & Product distillation at a temperature of 38.2 deg. Celcius.

Day4 (24-06-2011)

The Everest Vacuum Pumping System was accordingly changed and connected to Reactor reactor having 5 KL capacity. Vacuum Drop was found to be there in the reactor Reactor for which the batch was stopped to check the pipelines for leakages.

Leakages were found after checking the pipelines @ 0.8 Kg/cm2 air pressure and been rectified. The leakage test has to be performed @ 2 kg/cm 2 pressure to get the exact leakage in the plant and setup.
Batch started again and the vacuum was seen as 710-720 mm of Hg in the Dial Gauge over the reactor for which the batch completion time was seen to be 36 Hrs. 30 mins as compared to 42 Hours as against the XYZ present Steam Jet Set Up.

A reduction of 5 Hours 30 Mins was observed by the production people with the help of Everest vacuum Pumping System.

Day5 (25-06-2011)The opinion was taken from the production department saying that the product obtained with the Everest system found to be good in nature and the distillation rate is also high improving the quality of their product. System has been under running the whole day & quality of XYZ product found to be satisfactory.
Day6 (30-06-2011) Mr.Y (Manager Purchase) came to the Plant to check  the system installed and also had discussion with Mr.Y (Maintenance Department), Mr. X (Electrical Department) & Mr. S & Mr. T (Production Department).

Mr. Y suggested some Points of improvements and pointed out and which were immediately
rectified. After the same was done, Vacuum System Performance found to be even better. 

Day7 -10 Vacuum Pumping System Performance continuously monitored for current/ power consumption & Yield calculation by the production department and was found to be steady and satisfactory by the plant/ process officials.


Mr. T: “ The System is running good and is easy to handle with no use of steam as earlier due to which sometimes they had to stop the batch and then restart the process for attaining desired level of vacuum.”
Mr. O:” The System is showing satisfactory results by increasing the distillate volume as well as improving the quality of the product. We will look further for this kind of System soon. The running of the pump is very easy& helpful for the production people.” 

ELECTRICAL DEPARTMENT:Mr.Y:” The control panel supplied by Everest is very good, compact and automated, the main part is the VFD’s installed which will be helpful in reducing the power to 40% as to the connected load, the operation and connections are easy and user friendly.”

Mr. M:” The systems design is good and easy to understand and maintain, oil required is very less, no steam consumption, very easy to maintain.”
Mr. X:” The system connected is very good in performance and also very user friendly, there is no as such maintenance required at the regular intervals as seen in the previous systems for cleaning the nozzles of the ejectors for not getting proper amount of flow of steam, this is very good and automated system.”

MAJOR ADVANTAGES:1)Batch cycle time reduction by 8.5 Hours was seen as compared to the present setup of XYZ.
2)Lot of Power saving was seen in Everest Vacuum system as it was consuming only 7.9 units per hour.
3)No steam consumption hence lot of steam is saved.
4)Lot of cooling water was seen to be as 2.7 m3/hr and a reduction upto 10 times was seen.
5)Easy to start & Stop, user friendly.
6)Better Product Quality was observed by the Production Department.
The Everest Vacuum Pumping System has shown the fruitful results by its exclusive features and excellent performance will be performing well in the future also.
As per the discussions and the meeting with the XYZ Officials in the early stages of the project, they
have shown their willingness to replace all the existing pumps with Everest Vacuum Pumps once the
performance is observed to be satisfactory with the desired level of savings.
M/S XYZ Pharma , have placed repeat orders for 10 more vacuum systems and have generated many
more areas of requirement for placement of orders even further.  

Wednesday, October 5, 2011

Boosters for vacuum processes


Mechanical Vacuum Boosters are dry pumps  that meet most of the ideal vacuum pump requirements.  They work on positive displacement  principle and are used to boost the performance of water ring /oil ring /rotating vane /piston pumps and steam or water ejectors.  They are used in combination with any one of the above mentioned pumps, to overcome their limitations. Vacuum booster pumps offer very desirable characteristics which make them the most cost effective and power efficient option.

The major advantages are:-
(a) Can be integrated with any installed vacuum system such as Steam Ejectors, Water Ring Pumps, Oil Sealed Pumps, Water Ejectors, etc.

(b) The vacuum booster is a Dry Pump as it does not use any pumping fluid. It pumps vapor or gases with equal ease.  Small amounts of condensed fluid can also be pumped.

(c) Vacuum boosters are power efficient. Very  often a combination of Vacuum Booster and suitable backup pump results in reduced power consumption per unit of pumping speed.  They provide high pumping speeds even at low pressures.

(d) Boosters increase the working vacuum of the process, in most cases very essential for process performance and efficiency. Vacuum Booster can  be used over a wide working pressure range, from 100 Torr down to 0.001 Torr (mm of mercury), with suitable arrangement of backup pumps.

(e) It  has very low pump friction losses, hence  requires relatively low power for high volumetric  speeds. Typically, their speeds, at low vacuums are 20-30 times higher than corresponding vane pumps / ring pumps of equivalent power. 

(f) Use of electronic control devices such as Variable Frequency Control Drive allow to modify vacuum boosters operating characteristics to conform to the operational requirements of the prime vacuum pumps.  Hence they can be easily integrated into all existing pumping set up to boost their performance. 

(g) Vacuum boosters don’t have any valves, rings, stuffing box etc., therefore, do not demand regular

(h) Due to vapor compression action by the booster, the pressure at the discharge of booster (or inlet of backup pump) is maintained high, resulting in advantages such as low back streaming of prime pump fluid, effective condensation even at higher condenser temperatures and improvement of the backup pump efficiency.

The Table below gives a rough estimate of how the boosters enhance the working vacuums of the processes when installed in combination with various types of industrial vacuum pumps currently  used in the industry. They can effectively  replace multistage steam ejectors, resulting in considerable steam savings and reduced loads on cooling towers. Mechanical Vacuum Boosters are versatile machines and their characteristics depend largely on backing pump.  Various types of backing pump can be used, depending upon the system requirement and ultimate vacuum needs. However, the final vacuum is governed by the suitable selection of the backing pump and booster arrangement. The table below gives a broad range of vacuum achieved with various backing pumps combinations

For example, if a process is using water ring Pump, the estimated working vacuums would be of the order of about 670-710 mmHg gauge (90-50  mmHg abs.), largely depending on the water temperature and pump design. When a Booster is installed prior to the water ring pump, in series, the vacuum levels of the order of 5-10 Torr  can be easily achieved. In a Multi-Stage booster installation, vacuum levels of the order of 0.5 Torr & better can easily be expected. Mechanical Boosters offer a completely dry pumping solution and donot add to any vapor load, unlike steam ejectors, and therefore, do not require large inter stage condenses.

At low vacuums, higher pumping speeds are required to maintain the through-put, since the specific volume increases with the increase in vacuum. Vacuum boosters enhance the pumping speeds by  about 3-10 times depending upon the  selection by virtue of which one can expect higher process rates and through-puts. The drawbacks of steam ejector system such as sensitivity to motive fluid pressures and discharge pressure are overcome easily by the Mechanical Boosters, since the volumetric displacements/pumping speeds are insensitive to the inlet & outlet working pressures.  

Advantages of using Electronic Variable Speed Control Device Electronic A.C Variable Frequency Control Drives are most preferred devices used to regulate the Booster speed to match the varying load conditions of the process. These drives enhance the overall performance of the Boosters and offer various advantages for the trouble free operation. 

The major advantages are: -
  • Booster can be started directly from atmosphere
  • No need for separate pressure switch, by pass line or offloading valves
  • Considerable savings in power
  • Prevents over-heating of Boosters
  • Protects the Booster against overload and excessive pressures
  • Offers complete protection to motor against over voltage, under voltage, over current, Over-heating, ground fault
  • Eliminates the needs of separate starter and  overload relays for the Motor
  • Automatically adjusts the speed of Booster between low and high range set giving high pumping speeds with relatively low input power
The Electronic Variable Frequency Control Drive is a microprocessor based electronic drive which is specially programmed to meet the demands of the Booster allowing it to operate directly from atmosphere along with suitable fore pump.  Conventionally, Boosters can be started only after achieving fore vacuum in the range of 30 – 100 Torr, as they are not recommended for direct discharge into the atmosphere.  Use of Pressure Switch, Hydro kinematic drive and by pass valves is necessary to prevent the overloading of the  Booster. However with the installation of electronic variable frequency control drive all the conventional methods can be bypassed since the drive is programmed to regulate the Booster speed automatically, keeping the load on motor within permissible limits. This allows the Booster to start simultaneously with backup pump.

When the backup-pump and Booster are started the drive reduces the Booster speed to the pre-set levels and as the vacuum is created the Booster speed picks up, reaching the final pre-set speed, giving most optimum performance over the entire range. Since all the parameters are easily programmable, one can adjust the booster pumping speeds to match the system requirements easily and quickly.  The drive limits the current to the motor and safeguards the motor against over voltage, under voltage, electronic thermal,  overheat ground fault i.e. protects the motor against all possible faults. External computer control over all aspects of  booster performance is possible via RS485 serial interface built into the drive electronics. This enables the Booster to be integrated into any computer-controlled operating system.