Patent Application
20100326549
The invention relates to method and systems wherein the fluid stream from an object to be evacuated is filtered before it enters into vacuum pump with the maximum purity to the level of 99% and up to the particle size of 0.3 microns with Minimum pressure difference thereby improving the life cycle of pump and process performance of system.
1. Vacuum is a negative pressure condition created to remove gas molecules from a process work chamber with a object to provide a clean work space free of gases that effect product quality and process performance. Vacuum is used in numerous Industrial products, processes and applications like Lighting products, Drying of chemicals, Vacuum conveying systems, Electronic industry, Semiconductor(s) process, Food & Pharma process, reactors, Lighting products, picture tube manufacturing processes etc.
2. Vacuum pumps are divided mainly in four major categories as under
3. Above Vacuum Pumps are used to evacuate all work chambers/objects in order to get desired result for product, process & performance as per process requirement.
4. In this process of evacuation there are always chances that small quantities of dust, mist, chemical fumes or foreign materials will enter in to Vacuum Pump's chamber there by increasing the chances of wear and tear of all moving parts of pumps. These foreign materials will contaminate the pumps; oil and water and there by reduce its efficiency and efficacy enormously. Oil ring vacuum pumps therefore require periodic oil replacements to maintain pump performance. If this foreign particle size are more, then same particles will not only have the impact on mechanical performance of all moving parts in all types of pumps, but would also increase the maintenance cost of pump due to wear and tear of all moving parts and would also increase power cost. If oil is contaminated the Vacuum Pump's performance will come down drastically and it would fail to serve its intended purpose.
5. To avoid problems of impurities in Vacuum Pump's now a days DRY/SCREW type vacuum pumps have been developed which can generate 0.1 torr with additional booster pumps and are available in markets but are quite expensive. Screw type vacuum pumps are also having limitations about dust load. In such cases also periodic cleanings are needed as explained in US Patent application no 20070172361.
6. Other than this if dangerous chemicals or other non environment friendly foreign materials enter in to the oil there will be problem with disposal of oil when contaminants are endanger to environment and society. When such oil is disposed it may effect the environment very badly if the disposed oil is not handled properly or recycled properly.
7. Water ring vacuum pumps can take ample amount of dust and fumes load from process effectively as compared to Oil ring/dry screw/claw type vacuum pumps. Water ring vacuum pumps however consume more power and auxiliary water pump is required to feed the water in to vacuum pump and finally water ring vacuum pumps will deliver less vacuum than that by oil ring vacuum pumps. Over and above this the water also required to be get cooled in cooling towers and handling this contaminated water is an issue especially where contamination is high. If the water is not handled or treated properly the quality of the water will effect the environment.
8. There are steam ejector type vacuum pumps also available which can deliver up to 0.1 Torr with two or more pumps in series arrangement. However, these pumps require lot of heat to generate steam and again the steam contaminated with foreign materials produce bad quality of steam codensate and this will increase the hardness of water. If same condensate is re-circulated through boiler leads to lot of scaling and further contributes to reduction in thermal efficiency of boilers.
9. To filter the fluid stream there are some mechanical filters which are in use at present. The following likely drawbacks are there to use same filters on Vacuum pump suction lines.
10. There are lot of different types of traps to trap liquid fumes entry in to vacuum pumps like refrigerant traps, Liquid nitrogen traps etc. These are very expensive and have high operating costs.
11. Normally in wine processing industry the air stream towards vacuum pump is heated up to 110 Deg C to kill the bacteria which is going out from vacuum pump. Otherwise all bacteria will go out and effect environment badly. In this process of heating lot of electrical energy is needed to heat the air flow.
12. Diffusions pumps are made available for vacuum levels up to 1×10 sup (−10) torr for high vacuum applications. These pumps are face the problem of oil back streaming in to process chamber or/product to be evacuated. This back streaming of oil in PPM (Parts per Million) levels will effect process performance and/or product quality very badly. The same are discuseed in detailed in U.S. Pat. No. 3,782,816 and U.S. Pat. No. 5,700,134.
1. In any process of productions where steps involves reactions, melting, crystallizations, coatings, filling, drying, fermentation in a vessel for further processing a particular pressure is necessarily required to be carried out in vacuum. Thus a specific gravity of gas which flows into the vacuum pump is very small. When the gas together with other constituents flows into the vacuum pump, the gas flows appropriately but the crystallization in the vessel for processing prevent the reaction or reduced ability to convey other constituents which includes substantially the dust particles and therefore dust is accumulated in the vacuum pump. There are several inventions, which deal with this difficulty and have been able to reduce the amount of accumulated dust but how ever could not facilitate the satisfactory running of the vacuum pump and thereby require the frequent operations to remove the dust in the vacuum pump.
2. To prevent dust from flowing into vacuum pump attempts have been made to separate the dust by providing filters/cyclone separators, Traps and Traps in series or the like between the vacuum pump and the dust producing device however there was not a complete solution because dust causes blocking of through-parts in the filter, efficiency of which are then greatly reduced. The effective evacuation performance of the vacuum pump for the process of production by reaction, melting and crystallization vessel for processing prevents the reaction process the melting process and the crystallization process on a continuous basis.
3. Any process performances which are to be performed in vacuum its efficiency/effectiveness, productivity and product quality is dependent on vacuum level achieved in any said process. If foreign materials, fumes and dust and mist enters in vacuum pump it will reduce vacuum level and same will effect over all performance of process. If dust enters in to any vacuum pump in the middle of process cycle the pumping capacity of vacuum pump will come down and this will increase the cycle time or reduce process performance.
4. Vacuum pump pumping capacity will depends on conductance of pipe lines and restrictions, if any. For example if vacuum pump is for capacity of 100 Liters per minute (LPM) and if there is a restriction in pipe line the vacuum pump would conduct only 90 Liters per minute (LPM) the net pumping capacity of said vacuum pump would thus be restricted to 90 Liters per minute (LPM). On account of this problem people will not prefer to install any kind of mechanical filters where process vacuum is more important than maintenance of vacuum pumps.
5. To work in dusty/Fumes environment process of evacuation suitable pumps are Water Jet/Water ring/Steam jet (single stage/Multiple stage) vacuum pumps these pumps can take the load of impurities from process but the draw back in this system are
6. By using our unique filter the effluent generation will come close to Zero and also vacuum levels can be improved with over all energy savings up to 25%. The vacuum levels can also be improved by more than 8% from that of existing water ring and steam ejector vacuum pumps by replacing these pumps with any type oil ring vacuum pumps along with filter.
U.S. Pat. No. 5,776,216: A vacuum pump filter for filtering debris from a semiconductor(s) system is disclosed. The vacuum pump filter includes an inlet port for connecting to a chamber. A first filter holder is connected to the inlet port for filtering large debris. A second filter holder for filtering middle debris is connected to the first filter holder. A third filter holder is connected to the second filter holder for filtering small debris. A outlet port is connected to the third filter holder via a terminal. The other terminal of the outlet port is connected to a pump system.
United States Patent Application #: 20060276049
Title: High Efficiency Trap for Deposition Process
Abstract: The present invention provides a system, apparatus and method for improving the efficiency of a semiconductor(s) processing system, such as a deposition system by decreasing or substantially eliminating the accumulation of by-products in the apparatus components of the semiconductor(s) processing system. The present invention further relates to improving the efficiency of a fore line trap associated with a semiconductor(s) processing system, wherein the trap removes substantially all of the by-products from the exhaust gas from the processing chamber. In addition, the present invention provides a system, apparatus and method for efficiently clearing traps of accumulated by-products from exhaust gas of a semiconductor(s) processing system.
Device and method to mitigate hydrogen explosions in vacuum furnaces
U.S. Pat. No. 6,888,713
Abstract:
A device to mitigate hydrogen explosions in a vacuum furnace includes at least one igniter, an ignition transformer, and an electrical switch. The at least one igniter includes a set of high-voltage Electrode(s)s and is connected to the ignition transformer by high-voltage wires. The electrical switch activates the ignition transformer to provide power to the at least one igniter forming a continuous electrical arc between the Electrode(s)s. The at least one igniter is located inside the vacuum furnace at an opening where air may enter the vacuum furnace, which may contain a hydrogen and steam gas mixture under accident conditions. The device consumes hydrogen by controlled combustion as flammable mixtures are formed.
United States Patent Application #: 20070231162
Title: Vacuum Pump
Abstract: A multi-stage vacuum pump comprises, between adjacent stages of the pump, a continuous ignition source for igniting a fuel within a pumped fluid. This can ensure that the concentration of the fuel in fluid exhaust from the pump is below its lower explosive limit.
United States Patent Application #: 20070201988
Title: Vacuum Pump
Abstract: A vacuum pump comprises a rotor assembly mounted on a driven shaft, and a motor for rotating a drive shaft in forward and reverse directions. A driven member is located on the driven shaft and a drive member is located on the drive shaft for engaging the driven member to couple the driven shaft to the drive shaft. Each member has first and second impact surfaces. The members are configured to permit at least one quarter of a revolution of the drive member relative to the driven member in either the forward or the reverse direction before one of the impact surfaces of the drive member impacts upon a corresponding impact surface of the driven member. This can enable the drive member to acquire sufficient angular momentum before it impacts the driven member such that the amount of energy transferred to the driven shaft upon impact can be sufficient to free a pump that has become locked by process deposits. In the event that the pump is not restarted “first time”, the motor direction can be reversed to bring the other impact surfaces into contact with the same angular momentum. This sequence can be repeated as required until the pump restarts.
United States Patent Application #: 20060228272
Title: Purifier
Abstract: A purifier is described for use in a gas processing application. The purifier comprises a chamber having a gas inlet and a gas outlet. A series of baffles are arranged in the chamber and coated with a getter material selected for its ability to react with species to be removed from a gas stream and form stable compounds. The chamber also houses a source of the getter material, which is periodically activated to refresh the coating of getter material on the baffles.
U.S. Pat. No. 3,782,861
Abstract: An oil diffusion pump which has a plurality of coaxially arranged cylindrical chimneys extending from the bottom of a cylindrical envelope. The bottom of said envelope has hollow projections extending upwardly between the chimneys and a heating element has portions thereof extending into said hollow projections.
U.S. Pat. No. 5,700,134—Diffusion Pumps
Abstract: A diffusion pump is provided with an outer body and a chimney positioned within the outer body. A top cap is positioned about the top of the chimney to form an annular passageway (or an annular array of passageways) there between. A guard ring is positioned generally above the top cap. Coolers cool the outer body and the guard ring and working fluid present in the base of the outer body is heated to cause evaporated oil to pass up the chimney. A baffle, substantially thermally isolated from the guard ring, is contained within the outer body.
U.S. Pat. No. 2,377,391 (1945) to White discloses one of the earliest inventions regarding electronic air cleaners. A method and apparatus of charging suspended particles in air is taught. Once charged, a separate precipitator removes the particles. Broadly speaking, the invention comprises increasing the strength of the electric field between a discharge and a non-discharge Electrode(s) in the portion of the field adjacent the non-discharge Electrode(s). This may advantageously be effected by providing a previous, non-discharging auxiliary or grid Electrode(s) member between the discharge Electrode(s) and non-discharge Electrode(s), and maintaining a substantially greater potential difference per unit of spacing between the auxiliary Electrode(s) and non-discharge Electrode(s) than between the discharge Electrode(s) and the auxiliary Electrode(s). The auxiliary Electrode(s) is maintained at a potential between that of the discharge Electrode(s) and that of the non-discharge Electrode(s), so that the polarity of the field between the discharge Electrode(s) and the auxiliary Electrode(s) is the same as that of the field between the auxiliary Electrode(s) and the non-discharge Electrode(s).
U.S. Pat. No. 3,915,672 (1975) to Penney discloses an electrostatic precipitator having parallel-grounded plate Electrode(s) dust collectors. High voltage corona wires are located between the plate Electrode(s)s. They charge the dust particles, which are then drawn to the plate Electrode(s)s. The corona wires are pulsed in order to prevent back-corona which otherwise occurs due to the high resistivity of the dust accumulation on the plate Electrode(s)s.
U.S. Pat. No. 5,055,118 (1991) to Nagoshi et al. discloses an electrostatic dust collector. A first positive ionization Electrode(s) positively ionizes the dust. Then the dust passes into a chamber having a pair of un-insulated Electrode(s)s at a high voltage, separated by an insulation layer. Coulomb's law causes the dust to collect on the grounded Electrode(s), thereby neutralizing the charge of the dust particles. The dust only collects on the grounded Electrode(s) due to special gaps in the laminate, which prevents dust build-up on other components. The theory is that dust accumulation on only the grounded Electrode(s) does not cause significant deterioration of the electric charge due to the neutralization by the dust particles. However, it is clear that cleaning of the negative Electrode(s)s is necessary to maintain airflow.
One of the objects of the invention is to safeguard all types of vacuum pumps (as explained in 2 above) from contamination from dust, mist and gaseous particles by providing a unique kind of filter which operates on electrostatic precipitation principles. It is also an object of the invention to provide low cost Ultra High vacuum pressure electro static filter, which can filter effectively up to 0.3-micron size. It is an object of the invention to provide electro static filter for all kinds of vacuum pumps up to ultra high vacuum pumps. (On Line cleaning)
Electrostatic precipitation principle is used to filter all dust, mist, oily & gaseous particles on vacuum pump suction line to filter fluid stream which is going towards the vacuum pump to safe guard vacuum pumps from contamination from dust, mist & gaseous particles.
Also by additional fixtures like flame proof panels and flame proof fixtures same filter can effectively used in flame proof environment like solvent recovery systems, semi conductor(s) process systems in Bulk drugs and Pharma and semi-conductor(s) processes where fumes of explosive in nature are coming from process towards vacuum pump.
And to increase the area of collection Electrode(s) and to improve filter efficiency main External housing with flanged end (1) is connected to collection negative/grounded Electrode(s) and same grounded connection is shown in Drawing no 3.
And to increase filter cleaning period and to have more grounded collection area for fumes and collectants which are in liquid form a separate trap with drain valve (20) as shown in Drawing no 4 can be provided
Where fumes generation is very high and little time is available for filter cleaning, a separate cleaning fluid inlet valve (21) can be provided to clean filter while filter is in assembled condition on main pipe line as shown in (drawing no 4) with Drain valve (20) to drain cleaning fluid from cleaning process.
Ref fig Sectional View of Vacuum Line electrostatic filters (Drawing No 1) contain following items
External Housing Tube with Flange End (1)
Is made up of MS, SS316, Inconel, Hastalloy with flange end on both sides for easy mounting on vacuum line and have same metal pieces are welded on top to fix the Glass to Metal Or Ceramic to Metal/Rubber to metal Seals (5) with ‘O’ Rings (15) for hermitically sealing to avoid any vacuum leakages up to a vacuum level of 1×10 sup (−6) torr.
Gas Distributor (2)
This is made up of Insulated materials with high Dielectric strength like Nylon, Glass filled nylon, Plastics, Teflon etc to avoid accidental short circuiting and to distribute the stream of air flow from work chamber equally, and same is having hallowed slots to distribute flow equally across filter.
Ionization Zone Negative/Grounded Electrode(s)(s) (3)
This is negative elctrode(s) made up of Aluminum, SS316, Steel or Nickel alloys, Hastalloys, Inconel alloys same are Electrically insulated from Ionization Zone Positive Electrode(s) (4) and same are electrically connected to External Housing tube with Flange End (1).And are supported by Ionization Zone Negative Electrode Supporter/conductor(s) (8).
Ionization Zone Positive Electrode(s) (4)
This is Electrode(s) is/are made up of Alluminum, SS316, Steel or Nickel alloys, Hastalloys, Inconel alloys same are Electrically insulated from Ionization Zone Negative/Grounded Electrode(s) (3) and connected to Glass to Metal Or Ceramic to Metal/Rubber to metal Seals (5) with Ionization Zone Positive Electrode(s) Supporter/conductor(s) (9) to pass the high voltage DC through electrrodes. These Electrode(s)s are having sharp corners edges as shown in Drawing No 10 to produce corona effect to Ionize/charge the all particles on which is passing through kept horizantally to increase ionization time and improve filter efficiency.
Glass to Metal or Ceramic to Metal/Rubber to Metal Seals (5)
Is Electrically Insulated with Glass/Rubber/Ceramic between main body and feed through rod and also hermitically sealed up to vacuum level of 1×10 sup (−6) torr. Through this High Voltage DC current will flow to create corona and charge particles passing through. Total quantity is 2 Nos. One is connected for Ionization zone (6) and one is connected for collection zone (7) to supply high voltage currents to positive electrodes in bothe zones separately.
Ionization Zone (6)
This is zone comprises of Ionization Zone Positive Electrode(s) (4), Ionization Zone Negative/Grounded Electrode(s) (3), Ionization Zone Negative Electrode(s) Supporter/conductor(s) (8) And & Ionization Zone Positive Electrode(s) Supporter/conductor(s) (9) with Bush(es) (Insulator/Holder) (14) to insulate Electrode(s) and to charge/ionize particles which is passing through along with air.
Collection Zone (7)
This is zone comprises of Collection Zone Negative/Grounded Electrode(s) (10) Collection Zone Positive Electrode(s) (11) Collection Zone Negative Electrode Supporter/conductor(s) (12) Collection Zone Positive elctrode Supporter/conductor(s) (13) Bush(es) (Insulator/Holder) (14) Insulator/Retainer(s) (22) to collect dust, mist particles from process followed by Ionization zone (6).
Ionization Zone Negative Electrode Supporter/Conductor(s) (8) & Ionization Zone Positive Electrode Supporter/Conductor(s) (9)
These are metal rod(s) made up of SS316, Steel or Nickel alloys, Hastalloys, Inconel alloys to Electrically conduct between Ionization Zone Negative/Grounded Electrode(s) (3) and Ionization Zone Positive Electrode(s) (4) respectively.
Collection Zone Negative/Grounded Electrode(s) (10)
This is negative elctrode(s) made up of Alluminum, SS316, Steel or Nickel alloys, Hastalloys, Inconel alloys same are Electrically insulated from Collection Zone Positive Electrode(s) (11) and same are electrically connected to External Housing tube with Flange End (1) to have more collection area. And are supported by Collection Zone Negative Electrode Supporter/conductor(s) (12) and are electrically insulated by Bush(es) (Insulator/Holder) (14) from Collection Zone Positive Electrode(s) (11) to collect dust, mist particles from process.
Collection Zone Positive Electrode(s) (11)
This is positive elctrode(s) made up of Alluminum, SS316, Steel or Nickel alloys, Hastalloys, Inconel alloys same are Electrically insulated from Collection Zone Negative/Grounded Electrode(s) (10) and same are electrically connected Glass to Metal Or Ceramic to Metal/Rubber to metal Seals (5) through. And are supported by Collection Zone Positive elctrode Supporter/conductor(s) (13) Bush(es) (Insulator/Holder) (14). and are electrically insulated by Bush(es) (Insulator/Holder) (14) from Collection Zone Negative/Grounded Electrode(s) (10). Insulator/Retainer(s) (22) is inserted at edges of positive Electrodes to maintain equi distance between two Electrodes and also Electrically insualate from External Housing tube with Flange End (1) and negative elctrodes from positive electrodes.
Collection Zone Negative Electrode Supporter/Conductor(s) (12) & Collection Zone Positive electrode Supporter/Conductor(s) (13)
These are metal rods made up of SS316, Steel or Nickel alloys, Hastalloys, Inconel alloys to support Electrode(s)s and also Electrically conduct between all Collection Zone Negative/Grounded Electrode(s) (10), Collection Zone Positive Electrode(s) (11) respectively.
Bush(s) (Insulator/Holder) (14)
Is made up of High di electric strength materials like Teflon, Ceramic and or of Reinforced plastics to insulate both positive and negative Electrode(s) and also support physically both Electrodes to maintain equi distance between Electrodes.
‘O’ Ring(s) (15)
This is made up of Viton, silicon, neoprene rubbers to seal all mating joints hermitically sealed up to vacuum level of 1×10 Sup (−6) torr. These O rings are at flange joints, Glass to Metal or Ceramic to Metal/Rubber to metal Seals (5) to avoid any leakages in vacuum system.
Flame Proof Panel (16)
This is electrical control panel is normally made up of light weight alluminum or any reinfoced plastics to mount all electrical transformers, relays, Bridge rectifiers, control switchings etc to keep in safe environments and to avoid any accidental sparking to cath fire and to avoid any sort of explosion. The same panels are available in market as per safety requirements and as per industry standards and norms.
Flame Proof Fixture (17)
It is made up of light metal like Alluminum alloys or reinforced plastics mounted on Glass to Metal Or Ceramic to Metal/Rubber to metal Seals (5) to have hermitical sealing and also to with stand high positive pressure up to 10 Kg/cm2 to avoid any sort sparks coming out to catch fire if any flammable gas mixtures or traces present in atmosphere due to any leakages in any of system around area The design and safety standrads are as per industrial norms and standards.
Vacuum Pressure Sensor (18)
This is vacuum pressure sensor to measure the vacuum level in side filter housing and send electrical signal to filter along with vacuum pump ON signal to supply the high voltage DC supply to filter. Norally it is having variable pressure settings as per standards the setiing can be done in range of 1 to 760 Torr. Prefferably set at less than 45 Torr because at vacuum pressure of 45 Torr or less majority of flammable gases and or mixture of gases ignition cannot occur at pressures lower than 60 mbar (45 Torr).
This system is required for Flame proof and or explosion proof area only as per safety and standards required.
Controller (19)
Will take signal from both vacuum pump and Vacuum pressure sensor (18) process both signals and send signal to electrical source supply relay for filter. This will shut off electrical power supply to filter as a safety measure when 1) When vcacuum pump tripped or stopped due to any reason and (Or) 2) When the system pressure reaches or more than 45 Ton Vacuum pressure. This control system is needed only when filter has to work in Flame prrof and Explosion proof environments only.
Drain Valve (20) & Cleaning Fluid Inlet Valve (21)
Thses are valves to clean filter on line by draining the collectants from process and from cleaning and sending cleaning fluid when system was stopped to clean filter with out dismantling from main line.
Insulator/Retainer(s) (22)
Mounted on edges of collection zone positive Electrode(s) (11) prefferably Made up of high di electric strength materials like Rubbers, Teflon, ceramic to maintain equi distance between both positive and negative Electrodes and electrically insulate with External Housing tube with Flange End (1).
Cable Entry for Flame Proof fixture (23)
This is mounted with rubber Bush(es) to with stand positive pressure to avoid electrical sparks to come out side in case of flame proof and explosive proof environments to avoid accidents. This is as per Industrial standards and safety norms for flame proof and explosion proof environments.
Ionization Zone Power Supply Cable H2 (24) & Collection Zone Power Supply Cable H1 (25)
This is highvoltage cable with double or tripple layer insulation to with stand high voltages up to 20000 V DC and to pass electrical currents for Ionization and collection zones respectively.
Negative/Grounded Electrodes Connecting Cable (26)
This is highvoltage cable with double or tripple layer insulation to with stand high voltages up to 20000 V DC and to close circuit and ground the negative Electrodes as shonw in drawing no 2.
In Put Signal from Vacuum Pump (27)
This is electrical signal from Vacuum pump ON/OFF position to by processing this signal and also from Vacuum pressure sensor (18) the electrical signal to filter will be processed by Controller (19) as safety measure for filter to work in flame proof and explosion proof environments.
1) Schematic lay out of vacuum pump and Filter installation Drawing No 1
2) Schematic electrical circuit drawings Drawing No 2
3) Filter construction/Detailed drawing Drawing No 3
4) Filter construction/Detailed with on line cleaning draining system Drawing no 4
5) Filter construction/Detailed drawing for flame proof application Drawing No 5
6) Schematic circuit drawing for flame proof application drawing no 6
7) Schematic Drawing for High capacity filter (vertical)for bigger vacuum pumps Drawing No 7
8) Corona Distribution pattern in Ionization & Collection zone Drawing no 8
9) Schematic drawing for filters in series to improve efficiency Drawing No 9
10) Schematic drawing for Ionization zone Positive Electrode(s) (4) Drawing No 10
The fluid first pass through the Ionization Zone (6) it was covered by anInsulated Diverter (2) located on Internal side External Housing tube with Flange End (1) is hermitically sealed and tested at vacuum level of 1×10 sup (−6) Torr, Divertor (2) is made up of with High Di electric strength materials like Glass filled Nylon or Glass filled Teflon or Ceramic materials to avoid short circuiting of Electrodes accidentally if touches to Electrodes and to distribute the fluid stream equally between the set of Parallel Ionization Zone Negative/Grounded Electrode(s) (3) & Ionization Zone Positive Electrode(s) (4) to ionize all air Borne particles like dust, Mist,fumes and liquid particles along with stream pass through equally spaced set of Electrode(s)s supported by Ionization Zone Negative Electrode(s) Supporter/conductor(s) (8) & Ionization Zone Positive Electrode(s) Supporter/conductor(s) (9). These Electrode(s)s are connected to High DC Voltage up to 12000 VDC Through the Glass to Metal/ceramic to Metal/Rubber to Metal Seals (5) to work as a current carrier and also for hermitically sealing of filter up to vacuum level of 1×10 (−6) torr and to pass high DC voltage current through positive Electrode(s) to complete circuit. And to generate Corona effect to charge all air borne particles which is passing through. The corona configuration has been described clearly in drawing no (8). The long plate with corona discharge points in direction of flow will contribute for improvement of filter efficiency up to particle size of 0.3 microns and also 99% efficiency.
Ionization Positive Electrode(s) is simple metal Electrode(s) with Aluminum, Steel, SS-316, Hast Alloys, Inconel Alloys, Nickel Alloys to the design size with serrations on all four sides to have sharp points to generate corona effect to discharge corona to Ionize all air borne particles as shown in drawing no (10)
The Bush(es) (Insulator/Holder) (14) Insulator/Reatiner(s)(s) (22) will also work as an insulating media between both Electrode(s)s and physically supports Electrodes to maintain equi distance between Electrodes and Electrically Insulate Positive Electrode(s)between External Housing tube with Flange End (1) respectively.
For These Electrodes the Power from external source will be supplied up to 12000 VDC from Step up transformer and Bridge rectifier as shown Drawing No2 and drawing no 6. The main power supply connected to Electrode(s)s in Ionization zone (6) and Collection zone (7) through hermitically sealed Glass to metal or Ceramic to Metal or Rubber to Metal seals (5) of quantity 2 nos placed on Outer chamber placed at both ends of filter external housing tube with flange (1) in drawing no 3 to Drawing no 5 which was meant for to pass the electricity (high Voltage DC) and also seal hermitically sealing up to Ultra High Vacuum 1×10 sup (−6) torr.
Then This Fluid stream moves towards the Collection Zone (7) where collection zone contains Collection Zone Negative/Grounded Electrode(s) (10) & Collection Zone Positive Electrode(s) (11) which was supported by Collection Zone Positive elctrode Supporter/conductor(s) (13) which was supported by Collection Zone Negative Electrode(s)s Supporter/conductor(s) (12) is made of steel, MS, Nickel, Inconel vertically Insulated with Bush(es) Insulator/Holder (14) made up of (Nylon/Teflon/ceramic or any High dielectric strength materials rods to hold properly to maintain equal distance exactly as per design requirements and insulate both Electrode(s)s. These Bush(es)(es)es spaced equi distance between positive and negative Electrode(s)s to insulate the Electrode(s)s, physically support Electrode(s)s and also maintain equi distance between Electrode(s) to Electrode(s). Insulator/Retainer (22) mounted on collection zone positive elctrode (11) meant for Insulation and to maintain equi distance between both positive and negative Electrode(s)s and to avoid short circuit of positive Electrode(s)s and external housing tube with flanged end (1).
Positive Electrode(s) (11) and All charged positive particles will move to Collection Zone Negative Electrode(s) (10). And some of dust may adhere to collection zone positive electordes (11) also as explained above all charged particles adhere to Collection zone negative Electrode(s)s (10) Dust and mist and fumes also adhere collected on External housing tube with flanged end (1) hence it was connected to ground ie negative Electrodes.
Fresh dust/Fume free air will enter in to vacuum pump The Elecrodes Positive and negative will be coated with special coating at edges to avoid back corona and arcing, In such cases we can use higher voltages to improve filter performance in case of particle size up to or less than 0.3 microns and also efficiency of system to 99%. By installing 2 or more filters in services with improve filtration efficiency to 99.99%.
By changing the orientation of filter vertical with inlet from bottom side of filter and out let from top side of filter as shown in Drawing. No. 07 for cleaning process easier for easy handling and maintenance of filter.
Diffusion Pumps are are having problem of oil back streaming of oil fumes to work chamber it will effect the process and or contaminate the work chamber. In this case oil fumes will enter first in to collection zone and then Ionization zone. This will filter all oils fumes from back streaming by more than 98%.
When Bacterial, fungi, Algae passes through high intensity corona zone this bacterial will be killed to reasonablly.
Filter to Work in Flame Proof Environment
Even small accidental back corona/Electric spark may ignite flammable fumes presence in side filter. It may ignite fumes if fumes are in between LEL (Lower explosive limits) and (UEL) Upper explosive limits. Even if fumes get ignited the rise in pressure in pipe line and or filter will be 10 times than its actual pressure before ignition takes place. Pressure after ignition is equal to or less than atmospheric pressure. The above is clearly discussed in U.S. Pat. No. 6,888,713 and also US Patent Application no 20070231162
For majority of gases, ignition cannot occur at pressures lower than 60 mbar (45 Torr). Therefore flammability issues usually arise only after that point in vacuum system where the gas is compressed above this pressure level. The vacuum pressure sensor (18) therefore will be set at the pressure as is required for industrial and safety standards and norms. To send signal to electrical circuit of filter. If vacuum pump trips or stops due to any reason even when vacuum pressure is less than 45 Torr or set point in vacuum pressure sensor (18) the filter electrical supply will be stopped. The mounting of vacuum pressure sensor can be done on filter and or on Vacuum process chamber. As a practice of safety to avoid problems due to malfunction with vacuum pressure sensor we can opt for Dual vacuum pressure sensors also if safety standards are required to be followed to meet specific requirements.
Here special operating practices and procedures as well as equipments such as detonation and flame arrestors may be required on vacuum line as per industry standards and norms to install filter in flame proof and explosion proof environments. These norms and standards will/may vary from Industry to industry, process to process, location to location and country to country. There will always be different standards and norms and practices which would be required to be practiced in the construction of filter and filter safety measures to meet specifiuc requirements to work safe in above said environments.
The same filter can be used in flame proof environment like pharma, bulk drugs, Semi-conductor(s) processes etc., with additional flame proof fixtures (17) and flame proof panel (16) in put signal from vacuum pump (27) and Vacuum pressure sensor (18) as per industrial standards and Government regulations as applicable to individual countries for safe operation of filter in flame proof and or explosion environments.
The main filter is controlled by vacuum pump signal (27) and also vacuum pressure sensor (18) when both pump is in running condition and also the vacuum level reached to set point the signal will be sent to the filter electrical control circuit through controller (19) the filter will start functioning sending Ionization and collection currents through (H1 & H2) to Ionize and charge all air borne particles which are passing through to collect same and to stop entry of these impurities in to vacuum pump system. In such cases where flame proof environment filter the filter efficiency will come down and same depends up on the size of chamber to be evacuated, Pipe line sizes and distances, Minimum vacuum pressure required to put the filter in operation, Time required to reach required vacuum level and many more.
The vacuum level set points will depend on flammable impurities and properties presence from vacuum process work chamber under its explosive limits classification as per normal standards and safe practices of regulating authorities and Industrial safety norms and standards.
The vacuum connection for Vacuum pressure sensor either can be taken from filter housing and/or vacuum process work chamber as per convenience and as per requirement of system.
Design Data
The Diameter of filter will depends on mainly
The Fluid stream velocity we considered as 0.1 Meters/Second to 2 Meters/Second based on Impurities present in Fluid stream and Cleanliness required.
Stream Flow in Cubic Meters per Seconds=(Q)
Speed Meters Per Second=(N).
Cross sectional Area of tube in Square meters=(A)=Q/N
Dia of Tube=Square Root of (1.3×Area of Tube).
Ionization time (T) is 6 to 30 Milli seconds.
(Again the Ionization time depends upon the Impurities present and also the Cleanliness required).
Then the Length of Each Electrode(s)=Speed of Fluid stream (N)/Ionization time (T).
Based on this formula the Length of Electrode(s)s will be calculated.
Ionization Zone Potential difference DC Voltage (V1)=Up to 12000 VDC.
Collection zone DC In Put voltage=Up to 6000 V DC.
And there will be a collection pot between Ionization and collection zone this collection pot enables top hold more quantity of Liquid contaminants and to hold and dispose safely for some time after collection of liquid impurities from process. The Above said equations can be used to decide the filter size approximately
If the diameter of filter is too big to handle and clean filter Electrode(s) assembly manually the filter orientation will be vertical as shown in figure Drawing No 7 for easy cleaning with out dismantling of filter from main line.
| Number | Date | Country | Kind |
|---|---|---|---|
| 295/MUM/2008 | Feb 2008 | IN | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IN09/00091 | 2/9/2009 | WO | 00 | 8/6/2010 |
