• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A primary object of the invention is to improve the efficiency of centrifugal purifiers which separate particles from gases by means of centrifugal forces. In particular, the invention is intended to improve the separation of small particles. This increase efficiency is obtained according to the invention by combining the particles before they reach the centrifugal cleaner into larger particles. This fusion is obtained by charging the particles contained in the gas with charges of different polarity. Particles of different polarity will then be pulled towards each other by the coulomb forces and thereby merged into larger and separable particles in the centrifugal cleaner.
    公开号:SE0901347A1
    申请号:SE0901347
    申请日:2009-10-19
    公开日:2011-04-20
    发明作者:Torgny Lagerstedt
    申请人:Torgny Lagerstedt Ab；
    IPC主号:
    专利说明:

    with very high electrical voltages both in the corona stage and in the trapping part. The high voltages in the trapping part entail a risk of electrical overload in the electrostatic precipitator. An electrostat trainer must therefore often be taken out of service for cleaning.
    Centrifugal cleaner: Gases can also be purified with centrifugal technology. There, the gas is set with particles in rotation and the particles are separated by centrifugal forces acting on the particles. The two predominant types of centrifugal purifiers are the cyclone and the centrifuge. The Cyclone is a simple and inexpensive cleaner that can handle large amounts of particles and the cyclone can continuously discharge the separated particles. However, the cyclone has the great disadvantage that only relatively large particles can be separated. In particular, cyclones intended for large den fates have a low separation capacity for small particles. As an example, a cyclone dimensioned for a fl fate of 10 m3 / h has difficulty separating particles smaller than 3 u (particle diameter, one u is one thousandth of a millimeter). A cyclone dimensioned for 1000 mg / h cannot handle particles smaller than about 10 u.
    An efficient gas purification is obtained if the gas and the particles rotate in a centrifuge. Gas and particles here co-rotate with rotating separation elements in the centrifuge. This type of centrifuge can separate very small particles. But to handle small particles, the centrifuge must be made large in relation to the fl fate through the centrifuge. A practical limit on particle sizes that can be separated is about 1 u. In a centrifuge, the trapped particles can be continuously discharged from the centrifuge.
    Centrifuges are especially suitable for separating liquid particles (liquid droplets) from a gas. The trapped liquid droplets form a liquid that can be continuously discharged from the centrifuge.
    Liquid particles in a gas can, depending on the process that formed the particles, be small and smaller than 1 u. As previously mentioned, a practically useful centrifuge has difficulty separating particles with sizes below 1 u.
    Below are examples of some processes where small particles are formed. Liquid particles formed by condensation are small. Examples where small particles are formed by condensation are kitchen applications where vapors from heated oils and fats are condensed into droplets. Filters can be used here, but a filter clogs quickly. Usually, these grease particle-laden gases are passed out through a filter with limited efficiency and a larger part of the particles pass on through a ventilation system to a chimney. Grease will also get stuck and accumulate in the ducts of the ventilation system. The find in filters and ducts then poses a major fire risk. Other areas with small particles are curing where hot objects are cooled with oil. Curing causes problems with large amounts of small particles.
    Internal combustion engines also produce large amounts of small particles in the exhaust gases and in the crankcase ventilation. The particles in the exhaust gases are created in the combustion itself. In the crankcase ventilation, large amounts of small oil particles are created by the high temperatures and the strong agitation in the lubrication engine's lubrication system.
    The invention relates to a method of increasing the efficiency of cleaners using centrifugal technology. In order for the utility of the invention to be clear, a description is given here of the principles of centrifugal purification and the sedimentation rate of particles in a G field.
    In centrifugal purification, the particles are separated from a gas by gas and particles rotating and the centrifugal forces generated on the particles cause the particles to settle out of the gas and end up on a nearby solid wall. For efficient particle separation, it is essential that the particles have a high sedimentation rate in the centrifugal field.
    The sedimentation rate Us of the particle depends linearly on the centrifugal acceleration G and quadratic on the particle diameter D according to the relationship below.
    U s w G - Dz The velocity also depends linearly on the density difference between gas and particle and inversely proportional to the viscosity of the gas. But these parameters usually can not be affected.
    One way to expand the application ranges of cyclones and centrifuges is to, according to the invention, combine small particles into larger particles before they enter a cyclone or centrifuge. As a collective name, cyclones and centrifuges in the following are called centrifugal purifiers. The combined particles can easily be trapped in centrifugal purifiers and thus the great advantage of these purifiers is utilized in being able to handle large amounts of particles and continuously discharge the trapped particles during operation.
    Method according to the invention One way to increase the efficiency of centrifugal purifiers is to combine small particles into larger particles which can be easily separated in a centrifugal purifier. This merging of particles is accomplished according to the invention by charging the particles with electrical charges of different polarity. Particles with different polarity will by electrostatic action, so-called coulomb action, be pulled towards each other and form larger particles that can be easily separated in a centrifugal cleaner. A small particle can combine with a small particle to form a larger particle separable in the centrifugal cleaner. A small particle can also be merged with a large particle and this combined particle is easily separated in the centrifugal cleaner. Typically, the particle-laden gas contains a spectrum of particle sizes and fusion between all sizes of particles will take place.
    The particles are suggested to be charged by the particles passing through a corona field, but other charging mechanisms may also be conceivable. When corona charging particles, the gas stream with particles passes a wire or tip that has a high electrical voltage.
    The voltage that can be positive or negative is in the order of 10 to 50 kV (kilovolts). A positive corona voltage results in positively charged particles, a negative voltage results in negatively charged particles. The particles in the gas stream can be given different charge (polarity) with a corona voltage that changes polarity with a certain frequency and thus creates alternating positively charged and negatively charged particles.
    The particles are then mixed downstream of the corona field, merging positively charged particles with negatively charged particles. The gas with particles can also be divided into two streams where one stream passes a corona tent which gives a positive charge and the other stream passes a corona field which gives a negative charge. The gas streams are then mixed, whereby a particle fusion takes place.
    In an alternative form of the invention, the separation of small particles from a gas stream which mainly contains small particles can be significantly improved by the following procedure: The gas stream with small particles is mixed with large auxiliary particles. The gas stream which now contains a mixture of small and large particles passes a charging step where the particles are charged with different polarity according to previously described methods. The large particles have a high degree of charge (more on this later) and attract small particles of opposite polarity. A further alternative is to allow the particles in the gas stream with small particles to be charged in a charging step. The gas stream with small charged particles is mixed with a gas stream containing large charged auxiliary particles having an opposite charge. The auxiliary particles come from a source where the auxiliary particles are of such a size that the auxiliary particles can be safely separated in a centrifugal cleaner. These large auxiliary particles will now capture the small particles through the coulomb effect. The large particles are so large that they are separated by a good margin in the centrifugal cleaner, whereby also the small particles are separated. To clarify the background and advantages of the above-described method of large auxiliary particles, a brief description of the coulomb effect and possible degree of charge of particles is given below.
    Two particles with opposite charge are attracted to each other by the effect of coulomb. The magnitude of the force between two particles is described by F = K-q-lëql 12 Where ql is the charge on one particle and qz the charge on the other particle, l is the distance between the particles and K is a constant. As the expression above shows, the coulomb force of the product depends on the respective charge of the particles and inversely proportional to the distance between the particles squared. In order to obtain an efficient fusion of the particles, the particles must have as large a charge as possible. However, the possible charge of the particles depends on the size of the particle. A large particle can be charged to a high charge in that a larger number of elementary charges (electron charge) can be carried by a large particle compared to a small particle. The number of elementary charges that can be carried by a particle depends on the diameter of the particle squared.
    A particle with a diameter of 0.3 u can be charged with about 20 elementary charges. A particle with a diameter of 3 u can be charged with about 2000 elementary charges. The product of the charge of two 0.3 u particles is 400 and the product of charge of a 0.3 u particle and a 3 u particle is 20,000. The coulomb force between a 0.3 u particle and a 3 u particle is 50 times higher than the coulomb force between two 0.3 u particles. I.e. a mixture of charged in this case 3 p. particles effectively attracts 0.3 p. particles which are then easily separated in subsequent centrifugal purifiers.
    The method according to the invention is particularly suitable for improving the separation of particles from a gas during centrifugal purification. Even when purifying a gas with a filter, it can be an advantage to combine small particles into large particles before the gas with particles enters the filter. When the particles are large, simpler alters with larger pore sizes can be used. Such filters are cheaper and easier to clean.
    SUMMARY OF THE INVENTION A primary object of the invention is to improve the efficiency of centrifugal purifiers which separate particles from gases by means of centrifugal forces.
    Inventory is especially intended to improve the separation of small particles. This improvement is obtained according to the features stated in claim 1, where the particles before they reach the centrifugal cleaner are combined into larger particles by charging the particles contained in the gas with charges of different polarity. Particles with different polarity will then be pulled towards each other by the coulomb forces and then merged into larger particles separable in the centrifugal cleaner.
    The invention also relates to a method of achieving this improvement according to the features stated in claim 2, where the charging of particles takes place with a corona voltage which varies between positive and negative voltage.
    The invention also relates to a method of achieving this improvement according to the features stated in claim 3 where the gas stream with particles is divided into two gas streams and the particles in one gas stream are charged with positive polarity and the particles in the other gas stream are charged with negative polarity. The gas streams are then mixed with each other and a fusion of particles into large particles takes place.
    The invention also relates to a method of achieving this improvement according to the features stated in claim 4, wherein the charging of the particles in the gas streams described in claim 3 takes place with corona charging.
    The invention also relates to a method of achieving this improvement according to the features stated in claim 5 where the gas stream with particles is divided into two gas streams and the particles in each gas stream are charged with a corona voltage which alternates between positive and negative voltage. Merger into larger particles takes place in the respective gas stream. The gas streams are then mixed with each other and a further fusion into large particles takes place.
    The invention also relates to a method of achieving this improvement according to the features stated in claim 6, wherein a gas stream with substantially small particles to be purified is mixed with a gas stream containing large particles. Small and large particles are then charged and mixed according to the methods described in claims 1 to 5.
    The invention also relates to a method of achieving this improvement according to the features stated in claim 7, where a gas stream with substantially small particles is charged with a certain polarity. The charged gas stream with small particles is mixed with a gas stream containing large charged particles of opposite polarity. Small particles are then combined with the large particles.
    DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Figure 1 shows a principle sketch of the method of improving the efficiency of a centrifugal cleaner by entering the particulate gas 1 included in the cleaner system into a particle aggregation stage 2 placed in front of the centrifugal cleaner 4 where on different particles.
    The particles of different polarity are mixed and the particles of different polarity are pulled towards each other by coulomb forces and merge into larger particles and the gas 3 with mainly large particles leaves the aggregation step 2 and is led into a centrifugal purifier 4 where the particles are separated from the gas by centrifugal force. The purified gas 5 is passed further out of the centrifugal cleaner. The trapped particles remain in the centrifugal purifier or are continuously discharged from the centrifugal purifier via the discharge 6. The purified gas 5 can be passed on to a conventional filter stage to ensure that a minimal amount of particles is released into the environment. The filter step is not shown in Figure 1.
    Figure 2 shows the aggregation step 2 where the particulate gas 1 enters a aggregation step 2 located before the centrifugal cleaner 4 where gas with particles passes the charging part 20 in which the particles are charged with the charging elements 21.
    The charging elements 21 consist of a series of thin wires or tips which are energized with a high voltage and the particles which pass the wires / tips are charged with corona charging. Detailed design of the corona part is not shown in the clock.
    The corona wires / tips 21 are supplied with a high voltage from the high voltage assembly 22 via the electrical wire 23 which connects to the corona wires / tips 21.
    The high voltage assembly 22 supplies the wires / tips 21 with a voltage which at a certain frequency varies between plus and minus voltages, the particles passing through the wires 21 having an alternating positive and negative polarity. The frequency of the voltage change is selected to obtain the best possible fusion of particles. The selected frequency will depend on the geometric design of the corona stage, the velocity of the gas and the amount and particle size of the gas. The gas 24 leaving the corona stage 20 now contains particles with alternating positive and negative charge. Particles of different polarity now merge into larger particles in the mixing part 25. The gas 26 which now mainly contains large particles is led out of the aggregation step 2 to be led further into the centrifugal purifier 4 where the particles are separated from the gas by means of centrifugal force. The purified gas 5 is passed further out of the centrifugal cleaner. The trapped particles remain in the centrifugal purifier or are continuously discharged from the centrifugal purifier via the discharge 6. The purified gas 5 can be passed on to a conventional filter stage to ensure that a minimal amount of particles is released into the environment. The filter stage is not shown in Figure 2. Figure 3 shows the particle aggregation stage 30 where the particulate gas 1 enters the aggregation stage 30 where gas with particles is divided into two substreams 31 and 32.
    The respective partial current passes the charging elements 33, 34 in which the particles in the gas are charged with corona charging. The charging elements in 33, 34 consist of a series of thin wires or tips. Detailed design of the corona part is not shown in the clock.
    The charging element 34 is supplied with a high voltage by the high voltage supply 35 via the electrical line 36. Similarly, the charging element 33 is supplied with a high voltage by the high voltage supply 37 via the electrical line 38. The two high voltage units 35, 37 supply respective charging elements 34, 33 with voltages of a certain voltage. the gas flows different polarity. Wherein the gas stream 39 contains particles with a positive charge and the gas stream 40 contains particles with a negative charge or vice versa. The gas streams 39, 40 containing particles with charged to different polarity now go to the mixing part 41 where the particles in the gas merge into larger particles. The gas 42 which now mainly contains large particles is led out of the aggregation step 30 to be led further into the centrifugal purifier 4 where the particles are separated from the gas by means of centrifugal force. The purified gas 5 is passed further out of the centrifugal cleaner. The trapped particles remain in the centrifugal purifier or are continuously discharged from the centrifugal purifier via the discharge 6. The purified gas 5 can be passed on to a conventional filter stage to ensure that a minimal amount of particles is released into the environment. The filter step is not shown in Figure 3.
    Figure 4 shows the gas stream 1 with small particles mixed with the gas stream 8 containing large auxiliary particles. The mixed gas streams are led into the particle merging stage 2 where the particles in the constituent gas 1 and 8 are charged with a charge having different polarity on different particles. The particles of different polarity are mixed and the particles of different polarity are pulled towards each other by coulomb forces and merge into larger particles and the gas 3 with substantially large particles leaves the aggregation step 2 and is led into a centrifugal purifier 4 where the particles are separated from the gas by centrifugal force. The purified gas 5 is passed further out of the centrifugal cleaner. The trapped particles remain in the centrifugal purifier or are continuously discharged from the centrifugal purifier via the discharge 6. The purified gas 5 can be passed on to a conventional filter stage to ensure that a minimal amount of particles is released into the environment. The filter step is not shown in Figure 4.
    Figure 5 shows a merging step 50 where the particles in the constituent gas 51 which essentially contain small particles are charged in a charging step 52 and this charging takes place to the same polarity on all particles. The gas 53 with charged particles is led to the mixing chamber 54. In the mixing chamber 54 the gas 53 is mixed with the gas 55 containing large auxiliary particles having opposite polarity to the particle polarity of the gas 53. The large charged particles in the gas 55 will now attract the coulomb forces between the particles. the small particles in the gas 53. The gas 56 with the large and combined particles is then led to the centrifugal purifier stage 4 where the large particles are separated from the gas. The purified gas 5 is led further out of the system. The trapped particles remain in the centrifugal cleaner or are continuously forced out of the centrifugal cleaner via the discharge 6. The purified gas 5 can be passed on to a conventional filter stage to ensure that a minimal amount of particles is released into the environment. The filter step is not shown in Figure 5.
    The gas 60 contains auxiliary particles that are created or selected from a source where only large and easily separable particles are included in the centrifugal cleaner. The auxiliary particles are charged in the charging step 61 with a polarity opposite to the polarity of the particles in the gas 53. The charged large particles in the gas 55 are mixed as previously mentioned with the gas 53 in the mixing step 54.
    Brief description of the figures Figure 1 shows a charging step with a subsequent cleaning step.
    Figure 2 shows a charging step with subsequent purifier steps where particles in the gas are charged in the charging step with alternating positive and negative polarity. This charging is done with corona charging. ll Figure 3 is a charging step with subsequent purifier steps where the gas in the charging step is divided into two substreams and particle charging takes place in the respective substream.
    Figure 4 shows a charging step with subsequent purifier steps where large particles are mixed into the gas before the gas to be purified enters the charging stage.
    Figure 5 shows a charging step with subsequent purge steps where large charged particles are mixed into a particle stream with small charged particles.
    权利要求:
    Claims (3)
    [1]
    Claim 1) In a gas purifier using centrifugal technology to purify a gas from solid or liquid particles contained in the gas, the efficiency of separating small particles is increased by the upstream centrifugal purifier being placed in a charging stage which charges the particles in the gas with electric charges that have different polarity on different particles, whereby particles with different polarity are pulled towards each other and merged into larger particles during the transport between the charging step and the cleaner. These combined large particles are then separated in the centrifugal cleaner located downstream of the charging step.
    [2]
    A method according to claim 1, wherein the charging of the particles takes place in a charging step, characterized in that the charging takes place with corona charging which is driven with a voltage which alternates between plus and minus and thus charges the particles with alternating plus and minus polarity. 3) A method according to claim 1, characterized in that the gas stream with constituent particles is divided into two substreams, the particles in one substream being charged with positive polarity and the particles in the other substream being charged with negative polarity. The two substreams are then led together in a common gas stream whereby particles of different polarity are drawn towards each other and combined into larger particles which can be separated in the downstream centrifugal cleaner. 4) A method according to claim 3, characterized in that the charging of the particles in the two gas streams takes place with corona charging. 5) A method according to claim 4, characterized in that the charging of the particles in the two gas streams takes place with corona charging which alternately charges the particles with positive and negative polarity in the respective gas stream. 6) In a gas purifier using centrifugal technology to purify a gas from solid or liquid particles contained in the gas, increase the efficiency of small particle separation, characterized in that the upstream purifier is placed in a device which mixes large particles in a gas stream containing small particles. particles. The mixture of small and large particles is charged according to the method described in claim 1 or any of the subclaims 2 to 5. 7) In a gas purifier using centrifugal technology to purify a gas from solid or liquid particles contained in the gas, increase the efficiency for separating small particles characterized by the upstream purifier, a device is placed which mixes large charged particles into a gas stream containing small charged particles of opposite charge. The small particles being pulled towards and stuck by coulomb forces or joining the large particles which are easily separated in a subsequent centrifugal cleaning step.
    [3]
    3.) In a gas purifier used to purify a gas from solid or liquid particles contained in the gas, increase the efficiency of small particle separation by the upstream purifier placing a charging stage which charges the particles in the gas with electric charges having different polarity on different particles, particles with different polarity being pulled towards each other and merged into larger particles during the transport between the charging stage and the cleaner. These combined large particles are then separated in the cleaner located downstream of the charging stage, characterized in that the cleaner located downstream of the charging stage consists of a cyclone. 9) 14 In a gas purifier used to purify a gas from solid or liquid particles contained in the gas, increase the efficiency of small particle separation by the upstream purifier placing a charging stage which charges the particles in the gas with electric charges having different polarity on different particles, particles with different polarity being pulled towards each other and merged into larger particles during the transport between the charging stage and the cleaner. These combined large particles are then separated in the cleaner located downstream of the charging step, characterized in that the cleaner located downstream of the charging step consists of a centrifuge. 10) In a gas purifier used to purify a gas from solid or liquid particles contained in the gas, increase the efficiency of small particle separation by placing the upstream purifier in a charging stage which charges the particles in the gas with electric charges having different polarity. on different particles, particles with different polarity being pulled towards each other and merged into larger particles during the transport between the charging stage and the cleaner. These combined large particles are then separated in the cleaner placed downstream of the charging stage, characterized in that the cleaner placed downstream of the charging stage consists of an fi filter.
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    同族专利:
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE0901347A|SE535789C2|2009-10-19|2009-10-19|Ways to increase efficiency in cleaner using centrifugal technology|SE0901347A| SE535789C2|2009-10-19|2009-10-19|Ways to increase efficiency in cleaner using centrifugal technology|
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