MULTIPLE CYCLONE SEPARATOR

Abstract: Purification unit for separation of solid particles from gases comprising at least one group of a number of flow cylinders arranged in a common chamber and each having a fixed rotary head for setting incoming gas in rotary motion, an outlet diffusor for purified gas projecting concentrically into the outlet end of each flow cylinder and forming together with the surrounding cylinder an annular gap with its inlet portion, through which gap separated particles stream out to said chamber. In order to obtain at least the same purifying effect with several dust separators connected in parallel and each comprising a flow cylinder with a fixed rotary head and outlet diffusor as with one single dust separator the common dust collecting chamber (8) is connected by way of at least one suction line (19) to a steplessly adjustable blower (18) in order to maintain a negative pressure in said chamber (8) optimizing the purification.

Description: MULTIPLE CYCLONE SEPARATOR This invention relates to a purification unit for separating solid particles from gases, for example flue gases, air mixed with duet, air-blast etc., βaid unit comprising one or more groups of each a number of mutu¬ ally parallel flow cylinders arranged in a common cham¬ ber, each cylinder being connected at its inlet end to a fixed rotary head for setting incoming gas in rotary motion in the respective flow cylinder, an outlet dif¬ fusor projecting concentrically into the outlet end of each such cylinder, purified gaβ streaming out through said outlet diffusor, said outlet diffusor forming with its inlet portion enclosed by the flow cylinder an an- nular gap together with the surrounding cylinder, the separated solid particles streaming out through said annular gap to said closed chamber serving for dust collectio . Dust separators comprising one single flow cy- under with associated rotation generator connected to the inlet end of the cylinder and having an outlet dif¬ fusor projecting concentrically into the outlet end of the flow cylinder are previously known. This type of dust separator has appeared to operate very satiεfact- orily as far as flue gases and other gases containing particles of a small mass are concerned and purifies such gases up to about 99.7% which is quite acceptable in most connections that may be concerned with the pre¬ sent type of dust separator. However, a disadvantage of this known dust separator is a very low capacity, i.e. below 600 m^ gaε per hour, and therefore it has not been used to any large extent despite its high effici¬ ency in purification. In order to improve the capacity several such dust separators have been connected in parallel by arranging the flow pipes of all dust separators in a common cloε- ed dust collecting chamber in which the gap of the dust separators between flow cylinder and outlet diffusor ends for discharge of separate particles in the collecting chamber. An example of such a dust separat- ing unit is shown in Swedish lay-open print 304 668. Thus, parallel connection of a plurality of dust se¬ parators to one unit has been tested in practice but no better purification degree than about 86X, i.e. a puri¬ fication degree that is too low to be considered ac- ceptable in most connections, has been obtained. There¬ fore purification units containing several dust se¬ parators connected in parallel of this type have not been used in practice, either. After establishing that purification units con- taining several dust separators connected in parallel of the type indicated above do not give the desired purification effect ate pts have been made to solve this problem but without any appreciable success so far. However, this problem will have its solution by the present invention, the result of which is a purifi¬ cation unit consisting of one of several dust separat¬ ing units having an efficiency of the purification that corresponds to and is even somewhat better than the ef¬ ficiency obtained by means of one single dust separator of the relative type, and this is independent of which kind of impurified gas is to be purified. By means of the unit of the invention even air-blast can be purifi¬ ed for re-use of the very blast agent. In accordance with the invention this is achieved in that the purification unit has been given the char¬ acteristic features defined in the claims. The invention is described in the following in greater detail with reference to the enclosed drawings, wherein Fiσ. 1 shows a section of a purification unit according to the invention, Figs . 2 and 3 are perspec¬ tive views on a smaller scale of a module or group of nine and three, respectively, dust separating units connected in parallel, Fig. 4 shows a modified design with a rotary head mounted before each dust separating unit, Fig. 5 is a partial end view of a rotary head and Fiα. 6 shows a section taken substantially along the line VI-VI in Fig. 5. The purification unit of the invention for separa¬ tion of dust and other solid particles from impurified gases inclusive of air comprises a number of similar dust separating units 1 of cyclone type which are ar¬ ranged in rows in a casing 2 having an inlet 3 for the gas or gases to be purified and an outlet 4 for the gas or gases purified. Each dust separator 1 included in the unit comprises a fixed rotary head 6 located in an inlet chamber 5 for setting incoming gas in rotation, preferably a helical rotary motion, and a flow cylinder 7 connected to the rotary head 6 and arranged in a closed dust collecting chamber 8 common to all the flow cylinders 7 of the dust separators included in the unit. This chamber is quite separated from the inlet chamber 5 which is common to all units 1, and a col¬ lecting container not shown on the drawings can be con¬ nected to the dust collecting chamber θ. Gas intended for purification arrives at the chamber 5 via the inlet 3 and a helical rotary motion is imparted to the gas by the rotary heads 6 through the following flow cylinders 7, dust and other solid particles accompanying incoming gas being concentrated thanks to their inertia, i.e. through the action of centrifugal force, along the in- side of the respective flow cylinder 7. The rotary head 6 of each dust separating unit has a dome- or cup-shaped mantle of an inside diameter larger than the following cylinder 7 and is provided in its mantle with a number of, for example five, uniform- ly distributed, inlet openings 9 located substantially in a radial plane and hollows or recesses 10 in the mantle surface leading to the respective opening 9, the width and depth of said recesses increasing towards the respective opening and which have a concave curved form in cross-section, as is best apparent from Figs. 3 and 6, each portion 11 of the mantle defining a hollow or recess 10 functioning as guide blades for setting in¬ coming gas in rotary motion. Each inlet opening 9 in a rotary head 6 has its upper limiting line 9a so located that it borders on or preferably overlaps the lower limiting line 9b of the opening. At the outlet end of each flow cylinder there is arranged an outlet diffusor 12 ending in an outlet chamber 13 for the purified gas streaming out of the units 1, said outlet chamber being quite separated from the dust collecting chamber 8. Each outlet diffusor 12 extends concentrically into its flow cylinder 7 with a funnel-shaped inlet portion 14 and forms together with the end section of the flow cylinder an annular gap 15 ending in the closed dust collecting chamber 8. Impurified gas entering through the inlet 3 of the unit is distributed on the different dust separating units 1 and is set in rotation by the rotary head 6 of the respective unit and the helically rotating gas stream in each flow cylinder 7 continues through the cylinder 7 and the particles included in the gas are thrown by the influence of the centrifugal force against the cylinder wall and form a rotating dust film. When the gas stream reaches the outlet diffusor 12 the portion thereof streaming out of the diffusor is purified while the remaining portion of the gas stream, i.e. the portion containing the dust film and rotating close to the cylinder wall continues in a rotating way into and out through the diffusor gap 15 to the collec¬ ting chamber 8 where the particles fall down by the in- fluence of gravity and are preferably collected in a container. The number of dust separators 1 included in a unit according to the invention is adapted with respect to the amount of gas to be purified per unit of time. In order to make this adaptation easier the separating portion or portions of the unit can be composed of cassettes or modules 16 each comprising a suitable number, for example 1, 2-8 or 9, of dust separating units 1 enclosed in a casing 17 with at least one open side and easy to join and connect to a collecting con- tainer of a suitable size. Examples of two such modules 16 are shown in Figβ . 2 and 3 containing nine and three, respectively, units 1. A εteplessly adjustable blower 18 is connected to the dust collecting chamber 8 of the unit and is asso- ciated with the chamber 8 through one or several suc¬ tion lines 16 depending on i.a. the number of dust se¬ parating units 1 belonging to the chamber 8 for main¬ taining a negative pressure within said chamber 8. Each suction line 19 should be connected to the dust col- lecting chamber 8 spaced from the diffusor gaps 19 and preferably as much remote from these as possible. One or several of the suction lines 19 can also extend into the chamber 8 between the units 1 and have their inlet opening located at some distance from the walls of the casing. The blower 18 is connected with its pressure line 20 to the channel leading to the unit before the inlet 3 of the unit or to another space, for example the atmosphere or the chamber, the air of which is purified, which is possible thanks to the fact that the return flow caused by the blower 18 is such a small portion of the total main flow through the unit which is less than 0.150 and maximally 3% and is almost puri¬ fied. For the steplesε adjustment of the blower 18 there is arranged an operating or steering means 21, by means of which, thus, the negative pressure in the dust col- lecting chamber 8 can be changed steplesεly within wide limitε. An equalization of the differential pressure between the flow cylinders ending in the dust collect¬ ing chamber 8 with its column 15 in the area around the gap 15 thereof is achieved, the result of said equali¬ zation being that the flow cylinders 7 do not disturb each other but operate as separate units, i.e. as if they were alone and quite separated from each other. In this way several dust separating units connected in parallel are obtained which contain purification means capable of purifying impurified gases at least as ef¬ fectively as a plant containing one single dust se¬ parator 1 of the relative type and thus to at least 99.7%. Thanks to this possibility of adjusting the ne- gative pressure in the dust collecting chamber 8 step- lessly it is also possible to control, i.e. increase or reduce, the flow rate through the diffusor gaps 15, and in this way the purification unit of this invention also enables an optimal purification of impurified gases independently of the size and mass of the par¬ ticles forming the impurities. The purification unit of the invention can for instance be used for recovery of blast agents from air blast which has not been possible by means of known purification units of this type, and this is due to the possibility of achieving a high cur¬ rent rate through the diffusor gaps 15, and in this way each tendency to a braking accumulation of' particles in front of the diffusor gaps within the flow cylinders 7 is eliminated. Aε a result of this particles may be sucked along with the purified gas through the dif- fuεorε 12, the consequence being an impaired purifica¬ tion. A high flow rate through the diffuεor gaps 15 gives a higher rotation speed for the gas within the flow cylinders 7 and consequently also a more efficient concentration of heavy particles. In order to further increase the rotary speed within the flow cylinders 7 there is arranged another rotary head 22 of the same type as the rotary head 6 of the dust separating units in front of each dust se¬ parating unit 1 and coaxially with its rotary head 6. These are attached in a wall 23 between the inlet 3 of the unit and the wall 24 supporting the dust separating units 1. A first purification of the gas takes place in the space between these two walls in that the heaviest particles are separated from the gas thanks to the ro- tary motion in which the impurified gas is set by the further rotary head 22, and the rotary speed of this gas is thereafter increased by the rotary head 6 of the respective dust separating unit resulting in a very ef¬ ficient purification in the second step, i.e. in the flow cylinders 7, and the diffusor gaps 15 thereof end¬ ing in the chamber 8 which is defined by the walls 24 and 25, the latter of which is the partition between the chamber 8 and the outlet chamber 13. The flow through this purification unit is decided by a main blower 26 which can be arranged either before the inlet 3 of the unit or after its outlet 4. This latter location of the main blower is shown in Fig. 1, This invention is not restricted to what has been described above and shown on the drawings but it can be changed and modified in several different manners with¬ in the scope of the inventive idea defined in the ap¬ pended claims. Thus, the alternative with one dust se¬ parating unit 1 and a rotary head mounted before this arranged as a purification unit with blower to obtain a negative pressure in the dust collecting chamber is in¬ cluded in the inventive idea. For automatic control of the purification unit in dependence on the amount of impurities in gas streaming out through the outlet 4 a detecting means connected to the operating or control means of the blower can be ar¬ ranged in the outlet 4, said means detecting the amount of impurities in the gas streaming out through the out¬ let and, in case this amount will increase over a pre¬ determined value, actuates the control means of the blower to adjust the blower until said predetermined value is reached again.

Claims: CLAIMS 1. Purification unit for separation of solid par¬ ticles from gases, for example flue gases, air mixed with dust, air-blast etc., said unit comprising one or more groups of each a number of mutually parallel flow cylinders arranged in a common chamber, said cylinders each being connected at their inlet end to a fixed ro¬ tary head for setting incoming gas in rotary motion in the respective flow cylinder, the outlet end of each such cylinder projecting concentrically into an outlet diffusor through which purified gas streams out and which forms together with the surrounding cylinder with its inlet portion enclosed by the flow cylinder an an- nular gap through which the separated solid particles stream out to said closed chamber serving for dust col¬ lection, c h a r a c t e r i z e d in that the dust collecting chamber (8) is connected by way of at least one suction line (19) to a stepleεεly adjustable blower (18) in order to maintain a negative pressure in said chamber (8) optimizing the purification. 2. The purification unit of claim 1, c h a r ¬ a c t e r i z e d in that the pressure side of the blower is connected to the inlet line of the unit be- fore the inlet (3) of the unit or to another εpace, for example the atmosphere. 3. The purification unit of claim 1 or 2, c h a r a c t e r i z e d in that the suction line of the blower iε associated with the dust collecting cham- ber (8) spaced, preferably maximally spaced, from the gap (15) of the flow cylinders ending in said chamber. 4. The purification unit of any one of the pre¬ ceding claims, c h a r a c t e r i z e d in that the blower (18) is connected to the dust collecting chamber (8) by way of several suction lines (19). 5. The purification unit of claim 4, c h a r - a c t e r i z e d in that one or more suction lines extend into the dust collecting chamber (8) . 6. The purification unit of any one of the pre¬ ceding claims, c h a r a c t e r i z e d in that another rotary head (22) for setting incoming gas in rotary motion before its entry into the dust separating units (1) is arranged between the inlet (3) of the unit and the rotary heads (6) of the dust separating units coaxially with each of these heads (6). 7. The purification unit of claim 6, c h a r ¬ a c t e r i z e d in that the further rotary heads (22) end in a common chamber which is the collecting chamber of the particles separated due to the rotation in which incoming gas is set by the further rotary heads (22). 8. The purification unit of any one of the pre¬ ceding claims, c h a r a c t e r i z e d in that the flow produced by the εteplessly adjustable blower (18) is such a small portion of the main flow through the unit that it is less than 0.1% and not greater than 3% and preferably not greater than 2%. 9. The purification unit of claims 7 and 8, c h a r a c t e r i z e d by the alternative that the unit comprises one single dust separating unit (1) pro- vided with said further rotary head (22) .

Inventors: JOHANSSON ERNST, JOHANSSON, ERNST
Applicants: JOHANSSON ERNST, JOHANSSON, ERNST
Application year: 1987
Main classification: B01D45
IPC codes: B01D45, B04C3