Scrubber for gas and vapour streams from industrial processes

Abstract: There is described an apparatus for the purification of gas and vapour streams by the removal of solid, liquid or aeriform polluting substances, comprising: a stator consisting of a tubular body (1) having a cylindrical inner wall (1a), which body is furnished with at least one inlet aperture (5) for the admission of gas or vapour streams containing solid, liquid or gaseous impurities and with at least one discharge aperture (6), a coaxial rotor (7, 8, 9) extending longitudinally and revolvably supported inside the said tubular body (1) in such a way as to define with the said cylindrical wall at least one annular passage, means (10) for the admission of liquid into the said tubular body (1).

Description: In its more general aspect the present invention relates to an apparatus for the purification of gas and vapour streams, from industrial processes, by the removal of solid, liquid or aeriform polluting substances. In particular, the invention relates to an apparatus which effects the abovementioned purification under dynamic conditions. Various types of apparatuses are known in the art which effect the purification of gases by the removal of polluting substances by scrubbing with a suitable liquid. Among these may be mentioned scrubbing columns, cyclone scrubbers and Venturi type scrubbers. These latter apparatuses comprise a Venturi tube through which a gas is made to pass and into the throat of which is sprayed the scrubbing liquid. Through the effect of the high gas velocity, the liquid is finely atomized and the intimate contact achieved allows good dissolution of the soluble pollutants and good capture of the insoluble pollutants. The Venturi tube is connected to a cyclone in which the liquid droplets together with the entrained impurities are eliminated. However, the effectiveness of Venturi scrubbers drops when the dimensions of the particles of the pollutants fall to micron levels, since these tend to be expelled in the form of an aerosol. The problem underlying the present invention is that of making available an apparatus for the purification of gases or vapours from industrial processes by the removal of solid, liquid or aeriform polluting substances, which has high efficiency and in particular makes it possible to eliminate to the maximum degree the condensable aeriform impurities contained in the abovementioned gases. This problem is solved, according to the invention, by an apparatus for the purification of gas or vapour streams by the removal of solid, liquid or aeriform polluting substances, characterized in that it comprises: a tubular body having a cylindrical inner wall, which tubular body is furnished with a cooling jacket and is closed at opposite extremities by end plates and is furnished with at least one inlet aperture for the admission of a gas or vapour stream containing solid, liquid or gaseous impurities and with at least one discharge aperture, a coaxial shaft extending longitudinally and revolvably supported inside the said tubular body, at least one group of blades fixed radially on the said shaft, at least one rotating body of a purely conical shape fixed on and coaxially to the said shaft, the base of which faces the said discharge aperture and has a diameter almost equal to the diameter of the inner wall of the said tubular body with which it forms an annular passage, means for the admission of liquid into the said tubular body upstream of the said at least one rotating body of a purely conical shape. Preferably, the abovementioned shaft is hollow and one or more apertures made therein constitute the abovementioned means for the admission of liquid into the said tubular body. The abovementioned apertures are preferably made in proximity to the apex of the said at least one rotating body of a purely conical shape. Expediently, the apparatus according to the invention further comprises one or more liquid spray admission nozzles on the inner wall of the said tubular body at its lateral surface. According to a preferred embodiment of the invention, the apparatus comprises a plurality of groups of blades and a plurality of cones. The advantages and characteristics of this invention will emerge more clearly from the description of an apparatus for the purification of gases or vapours from industrial processes by the removal of solid, liquid or aeriform polluting substances, given below with reference to the appended drawing. With reference to the abovementioned figure, an apparatus according to the invention comprises a tubular body 1, having a cylindrical inner wall 1a, which tubular body 1 is arranged with its axis horizontal and is closed at the opposite extremities by ends 2, 3, and coaxially furnished with a cooling jacket 4, intended to have water or some other refrigerating liquid passed through it in order to maintain the inner wall of the said body 1 at a prefixed temperature. The tubular body 1 is furnished with an inlet aperture 5 for the gas or vapour to be subjected to purification and with a discharge aperture 6. Supported revolvably inside the tubular body 1 is a coaxial hollow shaft 7 furnished with blades 8 arranged helically and oriented so as to centrifuge and convey the gas or vapour subjected to treatment towards the discharge aperture 6. Additionally, fixed on and coaxially to the shaft 7 are rotating bodies of a purely conical shape 9, the base of which faces the discharge aperture 6 and has a diameter almost equal to the diameter of the tubular body 1. At the apex of each rotating body of a purely conical shape 9, the shaft 7 has apertures 10 for the admission of a liquid. The inner wall of the tubular body 1 has apertures 11 for the spray admission of a liquid. According to a non-binding interpretation, the operation of the apparatus could be as follows. The gas or vapour stream which is to be purified by the removal of solid, liquid or gaseous impurities is admitted into the tubular body 1 through the inlet aperture 5 and there it is subjected to extremely intense mechanical action by the blade 8 of the shaft 7, which revolves at a speed of between 200 and 1000 revolutions/ minute. Consequent upon such intense mechanical action, a considerable forward thrust and an extremely turbulent motion is imparted to the gas. The gas, when it reaches the lateral surface of the rotating body of a purely conical shape 9, enters into contact with the liquid admitted into the tubular body 1 through the apertures 10 and is then forced, under the thrust imparted by the blades 8, to pass through the extremely narrow gap between the base of the rotating body of a purely conical shape 9 and the inner wall of the body 1. At this point the velocity of the gas increases enormously and further increases its already high turbulence while its pressure decreases simultaneously; at the same time the liquid is very finely atomized, while the temperature of the inner wall 1a of the tubular body 1 is kept at low values by virtue of the cooling jacket 4. These conditions together produce very intimate contact between the water droplets of the liquid and the solid and liquid impurities contained in the gas and bring about the condensation of any condensable gaseous impurities; all this is done with greater efficiency than that of prior art apparatuses. The effects of the apparatus according to the invention are magnified if provision is made for the presence of several banks of radial elements of various design, such as blades, cones and screw spans, and in particular when groups of blades 8 and rotating bodies of a purely conical shape 9 are alternated. This may be useful in cases where the impurities contained in the gas to be treated are of very small dimensions or are difficult to condense. The purifying action of the apparatus according to the invention can be further enhanced if, in addition to the liquid introduced into the body 1 through the apertures 10, another liquid is admitted as a spray into the abovementioned body 1 through the apertures 11. The liquid admitted into the body 1 consists, in most cases, of water; however, should the gas to be treated contain liquid or gaseous impurities of a hydrophobic nature (for example aliphatic or aromatic hydrocarbons), advantageous use may be made of a solvent from the family of polyalkylene glycols, such as "cellosolve". The apparatus according to the invention makes it possible to purify variable gas or vapour flow rates, depending on the turbulence which is desired and on the quantity of liquid admitted. With the apparatus of the invention it is possible to eliminate particles of dimensions less than one micrometre from the treated gases or vapours. A major advantage of the apparatus according to the invention is that it allows the possibility of regulating the efficiency of the purification process on the basis of the characteristics of the gaseous material to be treated, by altering the speed of rotation of the driven shaft and the temperature of the liquid contained in the refrigerating jacket. Another advantage, of undeniable industrial benefit, of the apparatus according to the invention consists in the fact that there is no formation of scale and it is de facto self-cleaning. Obviously, for contingent technical and technological reasons, the apparatus according to the invention can be furnished with one or more cooling jackets so as to produce a temperature gradient along the apparatus and thus effect a heat exchange geared towards particular working requirements.

Claims: Apparatus for the purification of gas or vapour streams by the removal of solid, liquid or aeriform polluting substances, characterized in that it comprises: a tubular body (1), having a cylindrical inner wall (1a), which tubular body (1) is optionally furnished with a cooling jacket (4) and is closed at opposite extremities by end plates (2,3) and is furnished with at least one inlet aperture (5) for the admission of a gas or vapour stream containing solid,liquid or gaseous impurities and with at least one discharge aperture (6), a coaxial shaft (7) extending longitudinally and revolvably supported inside the said tubular body (1), at least one group of blades (8) fixed radially on the said shaft (7), at least one rotating body of a purely conical shape (9) fixed on and coaxially to the said shaft (7), the base of which faces the said discharge aperture and has a diameter almost equal to the diameter of the inner wall (1a) of the said tubular body (1), with which it forms an annular passage, means (10 and/or 11) for the admission of liquid into the said tubular body (1) upstream of the said at least one rotating body of a purely conical shape (9). Apparatus according to claim 1, characterized in that the said shaft (7) is hollow and, at the apex of the said at least one rotating body of a purely conical shape, it has apertures (10) constituting the said means for the admission of liquid into the said tubular body (1). Apparatus according to any one of claims 1 and 2, characterized in that it comprises a plurality of groups of blades (8) and a plurality of rotating bodies of a purely conical shape (9). Apparatus according to any one of claims 1 to 3, characterized in that it further comprises, on the inner wall of the said tubular body (1), at its lateral surface, one or more liquid spray admission nozzles (11).

Inventors: VEZZANI CORRADO, VEZZANI, CORRADO
Applicants: VOMM IMPIANTI & PROCESSI SRL, VOMM IMPIANTI E PROCESSI S.R.L.
Application year: 1996
Main classification: B01D47
IPC codes: B01D47