FI90630C - scrubbers - Google Patents

Description

1 90630

The invention relates to a device for washing gases with a liquid, which is of the type set out in the preamble of the appended claim 1.

Gas scrubbing is necessary either to separate the gas from the gas stream or to separate the chemical gaseous components from the gas stream, or to perform both at the same time. The latter comes into question in use, for example, in connection with the cleaning of flue gases, in which case the acidifying gaseous components are separated from the gas and the so-called flight polyol in the flue gas is separated in the scrubber at the same time.

The scrubber is a previously known device. A type of scrubber known from Eras is a so-called cyclone-type scrubber, in which 20 gas streams are introduced into the pydrivåS. According to the principle of operation, the polycyclone in the gas of TSllS is flushed to the walls of the cyclone and through it out with the water. However, existing solutions aim for gas flow properties, e.g. 25 possible rotating movements, to adjust the gas flow rate and entry into the scrubber. In addition, the placement of the nozzles in known scrubbers does not allow the nozzles to be serviced one at a time while the scrubber is operating.

The object of the invention is to eliminate the above-mentioned points and to provide a scrubber in which the gas can be cyclized without having to undergo special gas inlet arrangements and which can be used in particular in processes where the gas flow-35 mSSrSt can vary over a wide range. Separation of impurities with a simple and easy-to-maintain 2,90630 design. To achieve this object, the scrubber according to the invention is mainly characterized by what is stated in the characterizing part of the appended claim 1.

In the present invention, the rotational movement of the gas flow is substantially caused by tangential nozzles on the circumference of the scrubber, whereby the generation of the tangential movement is independent of the flow rate of the gas fed to the scrubber because the mass of liquid injected is large compared to the fed gas volume. The nozzles are located in two successive separate lies in the pMS flow direction of the gas, between which the flow cross-sectional area 15 has been reduced in the gas flow direction. The rotational motion is enhanced by the phasing because both nozzle groups are tangential.

From the point of view of My5s chemical and pdly separation, a more efficient washing operation is achieved by dividing the operation of the scrubber into two stages in the above-mentioned manner. According to a preferred embodiment of the ErSa, the scrubber is arranged so that the wall portions at the bottom of the compartments formed by each stage extend below the contraction point of the compartments 25 bays, whereby the washing liquid separating from the stage also tends to the lowest point of its own compartment. The TallS scrubber vox must be in a horizontal position, ie the gas flow direction is horizontal. 30

According to a preferred alternative, the nozzles of the at least one nozzle group are individually attached to the walls of the washing space for independent replacement. The maintenance of the device is simple, because the nozzles 35 can be accessed from outside the scrubber, and as a precaution, the nozzle group inside the scrubber does not have to be removed as a whole for maintenance 3,90630. In addition, the nozzles are preferably provided with their own shut-off valves, so that they can be replaced during operation of the scrubber.

The invention will now be described with reference to the accompanying drawing, in which Figure 1 shows a scrubber according to the invention in a cross-section in the direction of gas flow, and Figure 2 shows a scrubber in Figure 1 in cross-section in the plane of line A-A.

15 The scrubber of Fig. 1 is used in the washing space 1 delimited by the walls, where the gas and the washing liquid are brought into contact with each other. The scrubber is in the shape of a rotating body symmetrical about the central axis in the main direction W of the gas flowing through the space 1 IMpi. Perpendicular to the shaft 20, there is a tubular inlet connection 2 for the gas coming from the process, e.g. the boiler, and in the second end there is a correspondingly tubular outlet connection 3 for the treated gas. In the gas pM flow direction W between the inlet connection and the outlet connection 25, the flow cross-sectional area of the space 1 narrows first and widens after the smallest point 4. Thus, the two compartments 1a and 1b of the scrubber space separated by point 4 are formed, which form the PERMANENT treatment steps for the gas flowing through the scrubber compartment. The general shape of the washer 30 is thus in the shape of two truncated cones placed opposite their narrower ends.

The nozzles 5, which form the first nozzle group (only two shown in Fig. 1), are arranged along the circumference of the washing compartment 35 of the first compartment. As shown in Figure 2, the nozzles of the supply nozzle array are oriented circumferentially so that the liquid jet (indicated by dashed lines) 490630 provides a gaseous component in the gas entering the nozzle array area perpendicular to its main flow direction, i.e. in the compartment 1a forming the first stage for circumferential cyclonic rotation.

The term "circumferential" in this context means deviating from the radial direction, the angle between the directions 10 being preferably more than 30 °, most preferably more than 45 °.

After the smallest point 4 of the cross-sectional area, the gas enters a second stage, in the forming compartment 1b of which there is a second group of nozzles 15 formed by the second nozzles 6 (only two nozzles are shown in Fig. 1). The nozzles, like the nozzles of the first array, are oriented perpendicular to the main gas flow direction perpendicular to the main gas flow direction (some female nozzles are shown in phantom in Figure 2), perpendicular to the background. At the same time, a backward flow to the closed end of the compartment 1b in the middle of the compartment 1b at the edges of the compartment 25 is provided at the edges of the nozzles 6 after the gas flows meet the compartment wall (these axial flows are shown in broken lines). The nozzles 6 directed towards the ground wall 30 also help to increase the static pressure in the second compartment 1b.

In addition, the figures show the circumferentially arranged guides 9 at point 4 in the reduction of the flow cross-sectional area, which ensure that the rotational movement also continues in the second compartment 1b. There may also be more controllers than shown in Figure 2.

5,90630

Figure 1 further shows the washing liquid discharge connections located at the lowest points of the compartments of the axially horizontal washing space 1, the discharge connection 7 in compartment 1a and the discharge connection 8 in compartment-5 sa lb. The washing liquid that has accumulated on the walls of the compartments due to centrifugal force gradually flows towards its own discharge connection under the influence of gravity.

If the scrubber were vertical in structure, a cyclone-type scrubber would not be able to separate the wash water streams so that the first stage wash water would not flow to the second stage based on gravity or in turn depending on the gas inlet. Tallb's loss in certain types of differences in MMM has the advantage of phasing. The situation may be, for example, such that the gas contains two chemical components, the first of which excludes the dissolution of the second into the aqueous phase. If the barrier component can be separated in the first step, there are no obstacles to the separation of the blocked component in the first step in the second step, as long as the dewatering is also separated. The situation arises by washing, for example, gas streams containing hydrochloric acid and sulfur dioxide with water. Hydrochloric acid is much more soluble in water and prevents the partial pressure drop of sulfur dioxide from being sufficiently reduced. In the second step, after the liquid streams have separated, the small amounts of sulfur dioxide which would not otherwise separate can be separated after the hydrochloric acid has escaped. In the above case, the liquid intake to the nozzles of both stages can be common, because the same washing liquid can be used in the stages. The liquid intake is separate for each stage in the event that the different components of the gas require different liquids in the 35 stages.

6 90630

Since the scrubber can have a horizontal structure, the washing steps can then be completely separated in terms of liquid flows. However, other features of the washer can equally well be applied to structures in 5 other positions.

Nozzles 5 and 6 are placed on the outer periphery of the scrubber so much that the washing operation is not substantially disconnected from the nozzles. 10 Since the nozzle housing in the nozzles is constructed in such a way that the inner part 5a, 5b of the housing (Fig. 1), to which the water nozzle itself is attached, can be removed from the scrubber with the separate water pipe to the nozzle closed by the valve 10 (Fig. 2). possible without interruption. Continuous operation of the scrubber in several applications, e.g. power plants, is completely insurmountable for economic reasons.

The sections 1a, 1b forming the scrubber stages are separated at 4, where the gas flow cross-sectional area is reduced. This point 4 helps to separate the steps completely. In this case, it is possible to handle the gas in two stages, so that the gas 25 is brought to its liquid dew point in the first stage of the scrubber (compartment 1a). The gas flow rate at point 4 increases, reducing the static pressure. Since a small amount of liquid droplets is present in the gas, a wax 30 Adds liquid to the gas when the pressure drops, respectively, when the vapor pressure of the liquid is constant. In the second stage (compartment 1b), as the flow rate improves, the static pressure increases according to the Bernoulli equation and also because the nozzles 6 of the second stage are directed in the direction of more gas flow from the pressure wall of the compartment aa-35. In this case, a liquid condenses from the gas phase on all surfaces, even on the surfaces of small polyparticles accompanying the gas 7,90630. The mass of the particle coils increases and the separation in the cyclone-like rear of the scrubber is facilitated.

As the nozzles themselves, some types of nozzles known in the art can be used, which produce a liquid jet of the desired shape, e.g. at an angle of 30-90 °.

10

Claims (7)

A scrubber comprising 5 wall-delimited scrubbers (1) and having an inlet connection (2) for conducting gas to the scrubber and outlet connections (3, 7, 8) for treating gas and liquid, thereby passing a first nozzle group which the nozzles (5) are directed to the pSS flow direction (W) of the incoming gas in the perpendicular flow cross-sectional area perpendicular to the circumference of the washing space (1) so that the liquid jet from the nozzles (5) causes a gas-like rotation of the gas the flow cross-sectional area perpendicular to the flow direction between the first and second nozzle groups is reduced (point 4), characterized in that the nozzles (6) of the second group are likewise oriented in the flow direction (W) of the nozzle group in the downstream direction in the circumferential direction of the washing space (1) to enhance the above-mentioned rotational movement. A scrubber according to claim 1, characterized in that the nozzles (6) of the second nozzle group are directed towards the nozzles (5) of the first nozzle group in the pSS flow direction (W) of the gas entering the area of influence of the two more nozzle groups. Gas scrubber according to Claim 1 or 2, characterized in that the nozzles (5; 6) of the at least one nozzle group are individually mounted on the walls of the scrubber (1) to be replaced independently of one another. A scrubber according to claim 3, characterized in that the nozzles (5; 6) are separately provided with their own shut-off valves (10) for changing them during washing. 9 90630 Gas scrubber according to Claim 1 or 2, characterized in that at a reduced point (4) in the flow cross-sectional area of the scrubbing space (1) there are guides (9) for directing the gas in the direction of rotation 5 in the circumferential direction. A scrubber according to any one of the preceding claims, characterized in that the lowest wall portions in the compartments (1a, 1b) separated by the reduced cross-sectional area (4) lead down from said point (4) to the bays. Gas scrubber according to Claim 6, characterized in that the scrubbing space (1) is arranged horizontally in such a way that the main flow direction (W) of the gas is horizontal. ιο 90630