FIELD OF INVENTION
The present invention relates to an apparatus for the separation of gas and liquid from a flow mixture of gas and liquid, and more particularly the present invention relates to a process and apparatus for separating sulphuric acid mist from air.
RELATED ART
During charging of lead accumulators the electrolyte in the form of sulphuric acid and distilled water often becomes violently agitated by the evolution of gas towards the end of the charge. On boost charging it is often the case that the electrolyte boils. In both cases large quantities of air laden with sulphuric acid mist are produced.
It is an urgent matter, both from environmental and work personnel health considerations to remove such sulphuric acid mist from the air and render it innocuous. Thus, for the personnel, the sulphuric acid in the gas evolved both destroys clothing and injures the skin by contact and causes unhygienic conditions for lungs and eyes in the event of a lengthy stay in the battery charging room, and for the environment the sulphuric acid mist attacks vegetation and metallic surfaces, especially of aluminium, which are discolored and often gradually and unnoticeably corrode at places where ventilation pipes for air containing sulphuric acid emerge.
US Patent No 5464459 discloses a baffle-type mist eliminator. The invention provides for substantially straight, linear segments that comprising of the blade or baffle profile in combination with a relatively small inclination from the vertical for the inlet pass and a relatively larger inclination from the vertical of the outlet pass. In this invention, the air faces a lot of resistance while entering the mist eliminator. Thus this type of eliminator needs forceful entry of air.
The present eliminator is a cylindrical housing for the baffles with same inclination and semicircular size.
US Patent No 7311744, 6190438, 6630014 and Publication No WOO 103803 discloses mist eliminator having an elongated housing with a cyclonic flow inducing vane assembly. These are gas/ liquid separator of cyclonic variety. In this invention, the air faces a lot of resistance while entering the mist eliminator. Thus, this type of eliminator needs forceful entry of air.
In the present invention, there is no cyclonic flow. The flow is in zig-zag way.
US Patent No 6623547 discloses a washing tower, in which its inside is divided into plurality of stages by trays containing the gas diffuser at least in a part. A washing solution is poured on the trays for each stage so as to form washing tanks, an inlet of the gas containing sulfuric acid mist is provided at a lower part of the tower, and an outlet of the gas is provided at an upper part of the tower. In this invention, there is a pump for air suction at the entrance.
In the present invention, no washing liquid is used for mist absorption. The mist condenses on the baffles and drips down the inclined baffles back to the reservoir. Therefore, no suction is required.
US Patent No 4028077 discloses a mist eliminator with spaced eliminator blades. The first and second series of blades defining a separator unit having a plurality of zig-zag or chevron shaped gas flow channels with the longitudinal axes of the blades tilted at an angle of about 30 DEG tc about 45 DEG to the direction of flow of the gas stream. In this invention, the air is first passed through a liquid and then difussed.
In the present invention, no liquid is required to remove condensate. It is uncomplicated and easy to handle.
US Patent No 5230725 discloses a multilayer type mist eliminator having a first layer of a plurality of mutually parallel spaced partitions defining respective flow channels between the partitions. The step of scrubbing and washing is involved. In the present invention no washing is required.
US Patent No 5269823 discloses a mist eliminator comprising of a plurality of nonsinusoidal wave sections, in which shifting in the downstream direction of the turning points as compared to pure sine-waves results in a suppression of droplet reflection and an increase of the reentrainment velocity due to the thus achieved larger angle of impact on the effective eliminating surfaces. Thus, the suppression is being done by decreasing the velocity.
The present invention is purely mechanical used for removing liquid droplets from a gas stream by increasing the time lag via increasing the number of baffles.
US Publication No 20040007132 relates to a vane-type mist eliminator with pocket-like channels extending along the lengths of the vanes. This eliminator works only for high velocity gases. The present invention is suitable for sulphuric acid/ low velocity fumes.
Publication No GB1493122 is a charging cabinet having a chamber of substantially triangular shape in cross-section containing long, sharp -edged turnings of plastics material and passing the air containing the sulphuric acid mist in a turbulent flow through the container or chamber.
In the present invention, there is circular cross section with semicircular baffles.
Publication No JP10066813 discloses a mist eliminator having an outlet duct in the center part in a cylindrical outside container through a moisture adsorbing member.
In the present invention, adsorbent is not being used. Liquid drops are removed by increasing time lag.
Publication No CA1327534 discloses a mist eliminator module scrubbing the flue gas with water. It is used for heavy duty application such as refineries.
The present invention is applicable only for fumes with low velocity.
Publication No JP9271619 is directed to a mist eliminator with a barrier plate having a large number of apertures between the steam inlet duct of a mist eliminator container and a mist eliminator so that the surface thereof is made parallel to the mist eliminator. This eliminator is suitable for high velocity air.
In the present invention, baffles are semicircular and no apertures are being used. This eliminator is applicable for low velocity fumes.
Publication No DE3707919 discloses mist eliminator for the installation in an essentially vertically arranged flow channel. There are arranged two superposed layers (13, 14) of droplet-catching lamellae above the grooves, which are spaced apart side by side and mutually offset by preferably half a lamella pitch parallel to one another and perpendicularly to the longitudinal axis of the lamellae. This structure is
very complicated.
The present invention provides a simple structure which is easy to use and very cost effective.
Reference may be made to the publication by P. W. James, B.J. Azzopardi, Y. Wang and J.P. Hughes. The article explains only numerical simulations of the motion, and subsequent deposition of droplets on wave-plate mist eliminator surfaces
Further, reference may be made to a publication by Koch-Glitsch, Inc., Otto York Division. The article explains Flexi Chevron Mist Eliminators having baffle or zigzag blade modules tailored for either vertical or horizontal flow installations. This is suitable for high velocity gases.
Yet further, reference may be made to a publication by Bill Loony etal, Power Engineering, November 2007. The article explains chevron shaped baffles that removes fine droplets of alkaline reactant, slurry that become entrained in the flue gas stream inside the tower during operation. This is suitable for heavy duty application.
Still further, reference may be made to a publication by B. J. Azzopardi et.al, Chemical Engineering Science, September 2002. The article explains wave plate mist eliminator largely dependent on gas superficial velocity.
Further, reference may be made to a publication by Elasto Polymer Processors. The article explains chevron type mist eliminators designed for viscous liquids. It consists series of parallel zigzag vanes on which the droplets impinges as the gas flows therethrough. It is available in PP, PVC, PCVF, and FRP with the use of various resins and SS. This system is not suitable for viscous liquids.
With all the above discussed restrictions or limitations it is required to have improved mist eliminator for separating sulphuric acid mist from air. Thie mist eliminator according to the present invention is provided with a plurality of baffles through which flow of the acid gas is retarded, which gets cooled and converted into acid. This falls back into the battery. Mist eliminator provided in the invention is cost effective since the whole unit is preferably made up of for example PP (poly propeline). The mist eliminator serves the purpose of avoiding the acid mist to release in air, thus it avoids the acid loss in the battery and consequent battery drying up so that the separators can be kept wet for a longer period, which ensures better life and performance of the battery.
OBJECTS OF THE INVENTION
The primary object of the present invention is to provide an improved mist eliminator.
Another object of the present invention is to provide a mist eliminator which separates sulphuric acid mist from air.
Yet another object of the present invention is to provide apparatus for separating sulphuric acid mist from air in which sharp edged turnings of plastics material is provided.
Still another object of the present invention is to provide apparatus for separating sulphuric acid mist from air which is economical.
Another object of the present invention is to provide mist eliminator which can serve the purpose of preventing environment pollution and spillage of acid.
Yet another object of the present invention is to provide a mist separator in which time lag can be increased/ decreased as per the requirement.
Still another object of the present invention is to avoid escaping of acid from the battery while charging.
Another object of the present invention is to keep the charging environment free from acid fumes.
Yet another object of the present invention is to enhance life of the connecting cables used in charging by reducing the corroding effects of the environment.
Still another object of the present invention is to provide an eliminator which is applicable for low velocity fumes.
Yet another object of the present invention is to provide a mean which can increase the performance of the battery.
SUMMARY OF THE INVENTION
In order to overcome above mentioned problems and to achieve the said objects, the present invention provides an apparatus for separating sulphuric acid mist from air comprising of a container or chamber in which mist is entrained. A mist eliminator is used for removing liquid droplets from a gas stream. A zigzag gas/liquid separator for a gas/liquid mixture flowing vertically upward there through includes a cylindrical housing, a top wall having a gas outlet, a gas/liquid inlet, and baffles spanning the inlet. The improvement includes an annular wall transverse to the baffles adjacent to the inlet of housing. The annular wall, in combination with the baffles, defines an annular volume wherein separated liquid may drain downwardly toward the annular wall substantially without resistance from the gas/liquid flow. A drain carries the separated liquid directly to a liquid reservoir/ battery.
The process embodying the invention is cost effective since the separation material placed in the container, such as but not limited to long and sharp edged turnings of PP (poly propeline) is obtainable easily.
The sulphuric acid in the mist adheres to the surface of the baffles and agglomerates to form drops which in turn combine into a stream which is collected in a receptacle. It has been found that this separation effect does not take place if the air with the sulphuric acid mist is caused to pass through a container filled with granulate of round or oval PP particles. If a container filled with granulate of round or oval PP articles are used, after a certain time, the column will become flooded and no further separation will take place. It can therefore not be considered to be solely the surface enlargement which is of decisive importance but rather the shape of the long, sharp-edged turnings of the plastics material, in the case of PP.
In an embodiment of the present invention, the material of the cylindrical tube can be poly vinyl chloride, polypropelene or any other suitable polymer.
In another embodiment of the present invention, rectangular cross section can also be used as a long column with baffle inside in inclined position.

In another embodiment of the present invention, Polycarbonate, Low Linear Density Polyethylene, ABS, Stainless Steel (SS), SS-3161, bakelite, glass, acrylic can also be used.
In yet another embodiment, the number of baffles can be increased or decreased as per requirement.
In still another embodiment, the top can have N number of holes.
The foregoing as well as additional objects, features and advantages of the invention will be more readily apparent from the drawings and their detailed descriptions.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:
Fig. 1 shows improved mist eliminator; and
Fig. 2 shows top view of improved mist eliminator in accordance with the present invention;
Fig. 3 is the inner view of the improved mist eliminator.
DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
Reference may be made to Fig. 1, which shows an improved mist eliminator 10 in accordance with the invention provided on the battery while charging. As shown, the improved mist eliminator 10 comprises a substantially cylindrical housing 11 having a top wall 12 with atleast two holes defining gas outlet therein. The hydrogen and oxygen passes out through the holes. The improved mist eliminator 10 is oriented vertically with a gas/liquid inlet oriented downwardly. Further, the mist eliminator is provided with baffles (13), through which the flow of acid gas is retarded which gets cooled followed by convertion into acid. This falls back into the battery.
An annular wall is provided so as to accommodate said baffles. The annular wall is dimensioned such that the wall, in combination with the baffles 13, defines a substantially annular volume within the separation chamber wherein droplets of mist and particles of foam separated from a gas/liquid mixture flowing from the inlet 14 to the outlet may travel downwardly toward the annular wall substantially without direct impingement thereon from the upwardly flowing gas mixture.
As shown, the improved mist eliminator 10 is mounted over the battery. Air with mist and foam entrained therein, is drawn upwardly through inlet 14, baffles 13 and separation chamber and towards the outlet. Baffle assembly 13 imparts swirling zigzag motion to the gas/liquid mixture flowing there through. The resultant zigzag motion provides a time lag for the fumes. Therefore, the fumes become cool and the sulphuric acid present in the fumes are retarded due to the time lag. The retarded drops of sulphuric acid come back to the battery and the air (hydrogen and oxygen) passes out through the holes 12. The time lag can be increased/ decreased by increasing/ decreasing the number of baffles 13. As the eliminator condenses the sulphuric acid moving with the fumes, it reduces the loss of acid from the battery and hence increases the performance of the battery. This type of mist eliminator 10 is suitable for low velocity fumes.
As the particles thus acted upon move outwardly, the particles enter a substantially zigzag volume of the separation chamber wherein the axially upward velocity component of the gas/liquid mixture flow is greatly reduced, thereby allowing the separated particles to travel downwardly toward annular wall substantially without resistance from the flowing gas/liquid mixture. The particles which collect on annular wall then flow through drain tube 12 so as to be returned to the battery/ reservoir.
The separation material in the container, comprises such as but not limited to the long and sharp edged turnings of PP (poly propeline). The sulphuric acid in the mist adheres to the surface of the baffles 13 and agglomerates to form drops which in turn combines into a stream which is collected in a receptacle. It has been found that, this separation effect does not take place if the air with the sulphuric acid mist is caused to pass through a container filled with granulate of round or oval PP particles. Because if a container filled with granulate of round or oval PP
articles are used, after a certain time the column will become flooded and no further separation will take place. Therefore, it can not be considered that, solely the surface enlargement is of decisive importance rather the shape of the long, sharp-edged turnings of the plastics material, in case of PP carries importance.
Fig. 2 indicates top view 20 of the improved mist eliminator 10 in accordance with the present invention. The improved mist eliminator 10 comprises a substantially cylindrical housing 11 having a circular top 21 wall. The top wall is provided with atleast two holes 22 defining gas outlet 22 therein. The hydrogen and oxygen passes out through the holes 22.
Fig. 3 shows the inner component (30) of the improved mist eliminator (10). The baffles 13 are in semicircular form (31). Baffles (13) are arranged serially on the annular wall 32 in such a way that there rounded portion 33 is towards the periphery of the cylindrical tube 11. Flat portion 34 of the baffles is connected to the cylindrical surface in an ordered manner which provides zigzag motion to the fumes. Baffles 13 are also made up of for example PP. The resultant zigzag motion provides a time lag for the fumes. The fumes are retarded and the sulphuric acid present in the fumes gets condensed due to the time lag. The condensed drops of sulphuric acid get accumulated in the battery. The air (hydrogen and oxygen) passes out through the holes 22. The time lag can be increased/ decreased by increasing/ decreasing the number of baffles 13.
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims: -

WE CLAIM;
1. An improved mist eliminator comprising of a chamber with a top
wall at an upper end provided with gas outlet and an inlet on
bottom wall wherein the chamber is provided with an annular wall
accommodating a plurality of baffles adjacent to the inlet for the
flow of acid gas therethrough.
2. An improved mist eliminator as claimed in claim 1 wherein the gas
outlet comprising of atleast two holes for passage of Hydrogen and
Oxygen therethrough.
3. An improved mist eliminator as claimed in claim 1 or 2 wherein
said baffles are in semicircular form, which are arranged serially
on the annular wall in such a way that, their rounded portion is
directed towards the centre/periphery of the cylindrical tube.
4. An improved mist eliminator as claimed in any of the preceding
claims wherein flat portion of the baffles is connected to the
surface of said chamber in an ordered manner which provides
zigzag motion to the fumes.
5. An improved mist eliminator as claimed in claim 4 wherein said
baffles and chamber are made of plastic material being fiber such
as Poly propylene, Polycarbonate, Low Linear Density Polyethylene,
Stainless Steel, BAKELITE, glass, acrylic and other polymers.
6. An improved mist eliminator as claimed in any of the preceding
claims wherein number of said baffles can be increased or
decreased for increased or decreased timelag imposed by the zigzag
motion, which provides condentation of the acid such as sulphuric
acid during charging of the battery.
7. An improved mist eliminator as claimed in any of the preceding
claims wherein the annular wall is dimensioned such that the wall,
in combination with the baffles, defines a substantially annular
volume within the separation chamber wherein droplets of mist
and particles of foam separated from a gas/liquid mixture flowing
from the inlet to the outlet may travel downwardly toward the
annular wall substantially without direct impingement thereon
from the upwardly flowing gas mixture.
8. An improved mist eliminator as claimed in any of the preceding
claims comprising of said baffles through which the flow of the acid
gas is retarded, which gets cooled and converted into acid falling
back into the battery.
9. An improved mist eliminator as claimed in any of the preceding
claims wherein said chamber is provided with such as circular and
rectangular cross section.
10. An improved mist eliminator substantially as herein described
with reference to the accompanying drawings.