FI120027B - Method and apparatus for wetting dusting materials - Google Patents

Abstract

Arrangement for mixing a liquid with a flowing solid substance, comprising a reaction chamber (1), a connection (2) for feeding the flowing solid substance to the reaction chamber (1), a connection (3) for removing the mixed substance from the reaction chamber (1), and a connection (13) for feeding the liquid to the reaction chamber (1). For mixing the liquid there are elements (10) for feeding the liquid to the reaction chamber (1) in the form of droplets and elements (11,12,15) for feeding a compressed gas to the reaction chamber (1). On the central axis of the reaction chamber (1) is preferably arranged a mixer shaft (6), which comprises elements (9-12) for feeding the liquid and the gas to the reaction chamber from the outer surface of the shaft (6).

Description

The present invention relates to a process for mixing a liquid with a flowing solid according to the preamble of claim 1. Fields of application of the method include, for example, wetting and cooling power plant ash, wetting concrete components, wetting the dry matter of the paper industry, and even pre-wetting the dry matter in bakeries. In general, the process is for wetting the dry matter of the process industry 10.

The invention also relates to apparatus for carrying out the method.

15 There are many reasons why different types of dusting materials need to be wetted in the process industry. For example, in the treatment of hot ash, the purpose of wetting is to lower the temperature to eliminate the risk of ignition and to facilitate handling and prevent dusting. On the other hand, the purpose of the wetting 20 may be a mixture of a dusting agent and a wetting agent. Such processes exist, for example, in the bakery and paper industries, where the finely divided solid is mixed with water or other liquid to be used elsewhere in the manufacturing process.

25 Dusts are fine and dry fluids by their very nature. Wetting them effectively is quite difficult. It is true that the substance, which comes into direct contact with the liquid in contact with the dust, is easily wetted, which then forms an easily adherent mass which is poorly permeable to water. Thus, the finely divided dry substance easily accumulates in dry-centered lumps with a surface layer that prevents wetting of the material in the center. The slurry forming the surface layer is often quite adhesive, 35 so that the material to be wetted is easily and firmly adhered 2 to all surfaces it contacts. It takes a lot of work and energy to disassemble and remove the slurry, lumps and pulp adhering to the equipment walls. On the other hand, the risk of clogging is high and the humidifiers required a lot of cleaning and maintenance work to function reliably.

One device used in power plant processes for humidifying ash is a humidifying screw in which a mixture of ash and water is conveyed by a screw thread. The problem with this device is its easy clogging and quite laborious cleaning after clogging. Thus, this device cannot be considered to operate with satisfactory reliability in industrial processes. Attempts have been made to reduce clogging by coating the interior portions of the device 15 with rubber, but this entails high costs both in manufacture and in the renewal of coatings.

The object of the present invention is to provide a humidifying apparatus in which the wetting liquid and the wetting agent are brought into contact with each other and have a better wetting result.

The invention is based on feeding a wettable substance into a reaction chamber where a pressurized gas is blown into it and a droplet-like liquid is injected into the jets. Liquid 25 is fed into the apparatus along the longitudinal axis of the shaft along transverse, preferably radial, bores to the reaction chamber. The air is supplied through the axial passages, respectively, and preferably from radial, transverse bores.

30

In particular, compressed air and water are supplied to the moistened material.

According to a preferred embodiment of the invention, the compressed air and water 35 are supplied by means of an axle arranged on the central axis of the reaction chamber.

The radius of rotation towards the chamber edges and the shaft is rotated simultaneously.

According to a further embodiment of the invention, rod-shaped splinters are arranged on the shaft 5 and adapted to rotate with the shaft.

More particularly, the method according to the invention is characterized in what is set forth in the characterizing part of claim 1.

The apparatus according to the invention, in turn, is characterized by what is stated in the characterizing part of claim 4.

15

The invention provides considerable advantages.

The most important advantage of the invention is to ensure reliable wetting and to avoid clogging. There is less need for maintenance and, due to 20 reliable operations, humidifier downtime does not interfere with the processes that depend on it. The process is applicable to many different processes that require wetting of particulate material. The apparatus is intended in particular for the treatment of finely divided dusty substances, but can also be used for the processing of chips, wood chips or other materials or mixtures of materials which are reasonably light and small in size. It is essential that the solid parts of the material are brought into the reaction chamber by the action of blown air. Thus, the object 30 is to treat a flowing solid.

The design of the device is simple and easy to open and maintain. Wearable parts are few and simple and thus advantageously replaceable as required.

35 4

The invention will now be explained in more detail with reference to the accompanying drawings.

Figure 1 is a side sectional view of one embodiment of the invention in sectional view.

Figure 2 shows the device of Figure 1 in the direction of the end.

The body of the apparatus is formed by a tubular reaction chamber 1 and an inlet 2 formed above it and an outlet 3 below. The inlet 2 is narrower than the diameter of the reaction chamber 1 to allow effective mixing and the outlet 3 is at least equal to the diameter of the reaction chamber 1. The body of the device is divided along the central axis 4 of the reaction chamber 1 along the dividing line 5 in a horizontal plane. The unit can be opened at the dividing line 5 for cleaning and maintenance.

The actual mixing section is formed by a mixing shaft 6 mounted on the central axis 4 of the reaction chamber 1. The mixing shaft 6 passes through the end walls 7 of the reaction chamber and the passageways of the shaft 6 are sealed by seals 8 and adapted to be rotated in the reaction chamber (1). At mid-25 of the mixing shaft 6, a fluid supply channel 9 passes from which radial bores 10 terminating opposite to the outer surface of the mixing shaft are provided. The bores are arranged 180 ° apart. At the first end of the fluid supply conduit 9 and the mixing shaft 6, the opposite end of the liquid supply conduit 6 is closed. For supplying pressurized gas, the mixing shaft has two gas supply channels 11, from which transverse gas supply bores 12 extend to the outer surface of the mixing shaft. The pressurized gas is supplied to the shaft via gas supply lines 15. Further, rod-shaped discs 14 are disposed on the outer surface of the mixing shaft 5. These discs 14 rotate the mixing shaft 6 as a spiral and at least some of them extend close to the inner wall of the reaction chamber.

5

The method and apparatus of the invention operate in the following manner.

The material to be wetted, for example a further 10 hot dust ashes of the power plant, is fed from above through the inlet 2 into the reaction chamber 1. In the chamber, the ash is irrigated to permanently quench and cool and prevent dusting in subsequent processing steps. The mixing shaft is rotated at about 500 to 600 rpm, and through the gas holes 12, compressed air is supplied at a pressure of 3-8 bar from a normal compressed air network. The fluid drills 10, in turn, are fed with normal mill raw water pressure of 2-4 bar. The water supply bores 12 are dimensioned such that the water to be supplied drops when leaving the bores 10. The droplet-like water 20 is evenly distributed in the wettable material, so that the wetting result is more uniform and caking is not easily accomplished. Another factor that substantially affects the uniformity of wetting is the effect of compressed air supplied through a large volume of compressed air supply bores. The volume of the pressure manifold flushes the material to be wetted and, when fed through the rotating shaft, produces a highly turbulent flow, which prevents the dusting material from remaining in place and forming lumps under the influence of water. Thus, compressed air homogenizes the flow of matter and flushes the feed material to facilitate mixing of the liquid. The amount of compressed air must be reasonably high to ensure foaming.

Dispersion pieces 14 rotate at high speed in the reaction chamber and further mix flows in the chamber and 6 disintegrate lump deposits. However, their most important function is to keep the walls of the reaction chamber clean by preventing the wetted material from sticking to the walls of the reaction chamber.

5 Water is introduced into the reaction chamber in an adjustable amount. The amount can be adjusted with a simple setting valve. The water pressure must be sufficient to cause it to drop into the water supply boreholes. The volume control, for example, in the humidification of the ash is adjusted to stop the dusting, but no liquid water can escape from the humidifier or the ash is allowed to sludge. If the equipment becomes dusty, the amount of water is naturally increased, and ash sludge is reduced. If it is necessary to fine-tune the ratio of liquid to dust to be mixed, measurement and automatic control can be used.

The device of the invention can be made of conventional structural materials such as carbon steel, stainless or acid-proof steel, composite materials or polyethylene. If necessary, its parts can be rubber coated to increase wear resistance. The construction materials you choose will, of course, depend on the type of materials and the conditions of use.

In addition to the above, the present invention has other embodiments and.

Instead of the mixing shaft, compressed air and water can be supplied from the inner walls of the chamber, in particular upwardly directed nozzles, against the direction of dusting. However, in this case, the device is likely to become quite difficult to adjust to operating conditions and it may be difficult to obtain the mixing result as with the device described above. Although the device is primarily a humidifier, it can be used as a mixer, particularly for mixing one or more dusty substances and a liquid. Instead of air, even inert gas can be used as a mixing gas when the materials to be treated so require. The water supply channels and the air channels in the shaft can be arranged in other ways and, in particular, there may be several air channels arranged around the water supply channels. However, both are at least one, as are fluid and air supply drills. The bores 10, 12 may be arranged directly radially or obliquely or part obliquely and part directly radially to provide 10 transverse flows. Dispersion pieces 14 are preferably pin-like, though circular, but wing-like pieces could be contemplated in objects where there is no such high risk of wetting of the wetted material.

The reaction chamber 1 and the inlet and outlet ports are preferably rotationally cross-sectional. In this case, the mixing works well in the reaction chamber and the couplings are easy to prepare and connect to the reaction chamber. If these are other forms, the feed inlet should have a feed cross-section smaller than the reaction chamber and outlet.

Claims (8)

A process for mixing a liquid with a flowing solid, comprising: 5. introducing a flowing solid into the reaction chamber (1), - blowing a pressurized gas with the flowing substance in the reaction chamber (1), characterized in that the device along the mixing shaft (6) longitudinally along the shaft (6) and at least partially transverse, preferably radial bores (10), into the reaction chamber (1), and 15. the gas is fed into the longitudinal channels (6) 11) through and preferably from radial bores (12) at least partially transverse. Method according to claim 1, characterized in that the pressurized gas is air and the liquid is water. Method according to Claim 1 or 2, characterized in that the liquid and gas are supplied through a mixing shaft (6) arranged on the central shaft (4) of the reaction chamber (1) from the outer surface of the mixing shaft (6) towards the edges and shaft (6). rotated simultaneously. Apparatus for mixing a liquid with a flowing solid, comprising: - a reaction chamber (1), - a fluid (1) for supplying a flowing solid to the reaction chamber (1), 35 (3) for removing the mixed substance from the reaction chamber (1), - a mixing shaft (6), - one (13) for supplying liquid to the reaction chamber (1), - means (10) for supplying liquid to the reaction chamber (1) 5 in droplets, and - means (11, 12, 15) for supplying pressurized gas to the reaction chamber (1), characterized by 10 - means (13) for supplying fluid to the device along the mixing axis (6) along a longitudinal axis (6) of the shaft (6) and at least partially transverse, preferably radial bores (10), to the reaction chamber (1), and - means (11, 12, 15) for supplying gas through the longitudinal channels (11) of the mixing shaft (6), respectively, and preferably from radial, at least partially transverse bores (12). 20 Apparatus according to claim 4, characterized by a mixing shaft (6) adapted to the central axis (4) of the reaction chamber (1), comprising means (9-12) for supplying liquid and gas from the outer surface of the shaft (6) to the reaction chamber (1). Apparatus according to one of Claims 4 to 5, characterized in that the flow solid inlet (2) has a smaller cross-section than the reaction chamber (1) and the outlet (3). Apparatus according to one of Claims 4 to 6, characterized in that radial spreading means (14) are arranged on the mixing shaft (6). Apparatus according to one of Claims 4 to 6, characterized in that the reaction chamber (1) is rotationally symmetrical and is arranged to be distributed along a horizontal dividing line (5) passing through its central axis (4).