FI121163B - A submerged evaporator - Google Patents

Description

FIELD OF THE INVENTION

The invention relates to a submersible evaporator, the structures s of which are placed inside it, so as to dampen the oscillation of the liquid surface in the evaporator and thereby control the oscillation that occurs and prevent splashing.

BACKGROUND OF THE INVENTION

Submersible evaporator refers to a device for passing hot flue gases under the surface of the liquid to be evaporated, thereby causing the liquid to evaporate and simultaneously crystallize the desired product from the liquid.

In direct immersion evaporation, bubbles of hot gases discharged from the immersion tube are passed through the liquid. Thus, it is possible to provide very efficient material and heat transfer from the gases to the liquid to be evaporated. Since no heat exchangers are needed, material issues do not pose any problems. For this reason, direct submersible evaporators are used especially in chemical and metallurgical processes where corrosive conditions cause material difficulties. Typically, such are heating, evaporation and crystallization of strongly acidic solutions such as metal sulfate solutions.

In submersible evaporators, the submersible tube is generally arranged in an upright position, since this minimizes the amount of structural material in direct contact with the fluid being treated.

U.S. Patent 4,278,494 discloses a submersible evaporator with one large tube for supplying hot gas. The result is evaporator vibration and liquid splashes prepared with a horizontal combustion chamber and a connecting tube bellows. As the amount of gas increases, the size of the bubbles formed also increases, since gas cannot be fed at very high speeds, since it is known that the penetration of the gas jet increases with speed 2. When the gas velocity is relatively low, it is not well absorbed by the liquid into which it is fed, and therefore the lifting force produces a strong gas swell effect.

U.S. Patent No. 2,867,972 discloses a submersible evaporator in which an attempt is made to reduce vibration by notching a gas discharge tube in a saw blade.

In the solution of DE 34 47 060, the submersible evaporator operates with a suction so that only a very small submersion depth can be used for the discharge tube. Separate oblique tubes are used in the equipment. The disadvantage of these is that when the piping is lifted during maintenance, the lid must be provided with an opening of the same size.

In the solution according to Fl-85337, gas is fed into the solution to be evaporated through a series of smaller vertical tubes. The advantage is that the gas can be supplied at relatively high speeds, but its permeability remains low due to the small size of the nozzle. In practical cases, however, the damping of the oscillation has not been sufficient in all respects.

PURPOSE OF THE INVENTION

The purpose of the submersible evaporator structure of the present invention is to reduce the disadvantages of the submersible evaporators, such as fluid surface oscillation, which causes corrosive splashes and further oscillation of the entire evaporator due to oscillation.

SUMMARY OF THE INVENTION

The essential features of the invention will be apparent from the appended claims.

The invention relates to a submersible evaporator formed by a cylindrical fluid reservoir and a submerged conduit through which a hot gas is fed through a plurality of gas channels and a nozzle connected thereto below a liquid surface, and at least three circular the vertical plate.

5

The number of vertical plates fixed to the rotary plate is at least 3, preferably 4-6. It is typical of a submersible evaporator structure that a gap is left between the vertical plates and the submerged tube for removing the submersible tube while the circulation tube is stationary.

10

According to one embodiment of the invention, the horizontal plates are provided with a horizontal plate arranged substantially horizontally below the liquid surface in the vicinity thereof. The width of the horizontal plate is preferably 2 to 8% of the circumference of the circular tube.

15

According to another embodiment of the invention, the liquid tank of the submersible evaporator is provided with a plate grid consisting of two plates placed perpendicular to each other. The plate grid is located below the liquid surface in a substantially horizontal plane and is 2 to 7% of the height of the cylindrical portion of the fluid container.

LIST OF FIGURES

Fig. 1 is a plan view of a prior art solution, Fig. 2 is a plan view of another prior art 25, Fig. 3 is a plan view of a damped submersible evaporator according to the invention, and Fig. 4 is a cross-sectional view of the submersible evaporator of Fig. 3.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 is a plan view of a submersible evaporator depicted in the prior art consisting of a container 1 containing a fluid to be evaporated 2 and 4 from a single large submerged tube 3 through which hot gas is fed under the liquid surface of the container. The liquid is introduced into the tank via the pipe connection 4 and the gases are discharged together through the pipe 5. The crystallized salt is removed from the bottom of the container to one through 6. The gas jet is known to provide around 5 vacuum areas, so that especially the solution around the discharge opening mixes well with the jet. The higher the jet speed, the stronger the mixing.

In particular, when large submerged tubes are used, the gas flow rate must be reduced to reduce the permeability of the gas. As a result, the gas drops to the surface of the liquid in large bubbles. As can be seen from the principle image and known from practical experience, large bubbles cause significant surface oscillation and, as a result, the entire submersible oscillator.

15

Figure 2 illustrates another prior art submersible evaporator solution consisting of a tank 7 and a submerged tube 8. The lower part of the submerged tube is formed by a plurality of downwardly directed tubes 9 and all gas is discharged into the liquid 10 in the tank through these tubes. The liquid is introduced into the container through the conduit 11, the gases are vented through the 12 and the crystallized salt through the bottom 13. A submerged conduit formed of separate gas tubes is surrounded by a circulating tube 14, which is provided with openings from which gas introduced into the liquid or a mixture of gas and liquid can be discharged into the liquid.

25

In the solution of Figure 2, small jets of different kinds are initially formed, but they also tend to merge into larger jets, forming a uniform bubble rising upwardly in the circulation pipe. An advantage of the method described in connection with Fig. 1 is that in this solution 30 higher gas flow rates can be used than in the solution according to Fig. 1, but the gas penetration remains reasonable. These result in a significantly lower lifting force and still result in less surface swing 5 than in the case of Figure 1. Flowwise, the solution of Figure 2 is very good, but in practice, however, separate pipes cannot withstand.

Figures 3 and 4 illustrate a submersible evaporator 15 according to the invention consisting of a cylindrical fluid reservoir 16 and a submerged tube 17. The fluid to be heated and evaporated is introduced through the inlet 18, the gas is discharged through the gas 19 and the crystallized solid through the tapered outlet 20. A plurality of gas channels 21 are formed at the bottom of the submerged pipe ίο either during manufacture or after machining. Thus, the gas channels formed in the submerged tube have less wear than the individual tubes. A circulating tube 22 is provided around the submerged tube, which is provided with openings for gas or liquid mixture to be discharged into the liquid.

At least three, preferably 4-6 vertical plates 24 are disposed in the rotary tube to dampen the oscillation of the liquid surface 23 and the consequent submersible evaporator vibration. When the number 20 is at least three, surface oscillation can be prevented in two directions, i.e., both vertical and transverse. The vertical plates are preferably attached radially to the inner wall of the rotary tube and are typically of the length of the rotary tube. A gap is provided between the vertical plates and the wall of the submerged tube, which allows unobstructed removal of the submerged tube for maintenance, even though the circulating tube is in place. The vertical plates can substantially prevent splashes rising up from the liquid surface, which corrode the submerged tube and prevent fluid surface oscillation.

To compensate for surface oscillation, the rotary tube of the submersible evaporator 30 according to the invention may be further provided with horizontal plates 25 attached to the vertical plates 24, which preferably extend horizontally on either side of the vertical plate. The horizontal plates are placed under the liquid surface, 6 near it. The dimension of the horizontal plate from the wall of the circular tube to the submerged tube is typically the same as that of the vertical plate. The width of the horizontal plate is such that it does not substantially prevent the gas bubbles from rising, and typically one horizontal plate has a width of 2 to 8% of the circumference of the circulating tube.

5

Another way to dampen the surface oscillation is to place a plate grid 26 in the sink evaporator container 16 outside the circulation tube and below the liquid surface 23, which further smoothes the liquid surface throughout the container. The plate lattice consists of two ίο plates set perpendicular to each other. The plate lattice is typically placed in a horizontal position, extending to the edges of the container, and its height is in the order of 2 to 7% of the height of the cylindrical portion of the container. The plate lattice is particularly advantageous in smaller evaporators.

It should be noted that although Figures 3 and 4 show three different ways of leveling the liquid surface of a submersible evaporator, in particular vertical plates can be used in accordance with the invention without horizontal plates or lattice plates or in combination with either structure.

20

Claims (8)

A submersible evaporator (15) formed by a cylindrical fluid reservoir (16) and a submerged conduit (17) through which hot gas 5 is fed through a plurality of gas conduits (21) below the liquid surface, and a circular conduit (22) surrounding the submerged conduit. ), characterized in that at least 3 radial vertical plates (24) are attached to the inner wall of the circulation pipe. ίο Submersible evaporator according to Claim 1, characterized in that the number of vertical plates is at least 3, preferably 4-6. Submersible evaporator according to Claim 1, characterized in that a gap is left between the vertical plates (24) and the submerged tube (17) for removing the submerged tube 15 with the rotary tube (22) in place. Submersible evaporator according to Claim 1, characterized in that a horizontal plate (25) is disposed on the vertical plates (24) in the vicinity of the liquid surface (23), which is substantially horizontal. 20 Submersible evaporator according to Claim 4, characterized in that the horizontal plate (25) has a width of 2 to 8% of the circumference of the circulation pipe (22). Submersible evaporator according to claim 1, characterized in that the liquid reservoir (16) of the submersible evaporator is provided with a plate grid (26) consisting of two gratings arranged perpendicular to each other. Submersible evaporator according to Claim 6, characterized in that the plate grid (26) is located below the liquid surface (23) in a substantially horizontal plane and has a height of 2 to 7% of the height of the cylindrical part of the liquid container (16). Submersible evaporator according to Claim 1, characterized in that the gas channels (21) are formed at the bottom of the submersible evaporator.