WO2008153404A1

WO2008153404A1 - Method and device for drying of flowable substances

Info

Publication number: WO2008153404A1
Application number: PCT/NO2007/000211
Authority: WO
Inventors: Jan Erik Larsen; Helge Dyrnes
Original assignee: Environmental Waste Technology As
Priority date: 2007-06-15
Filing date: 2007-06-15
Publication date: 2008-12-18

Abstract

A method for drying batches of flowable substances by heating the substance on dishes arranged in a stack of dish units in a closed container. This is subjected to vacuum and supplied with heating energy to the individual dishes. The substance is dried on stationary dishes. After stationary drying, the substance is mechanically disintegrated and removed from a dish unit via the underlying unit, for emptying the drying dishes before replenishing with fresh substance to be dried. A device for conducting this method has a stack of circular dish units (34 - 40) arranged in a closed container (11). Each dish unit includes a drying dish (41) with a heating element (44). The closed container is connected to a vacuum pump (32). A supply conduit providing substance to be dried is arranged above the upper dish unit (40) of the stack. The drying dishes (41) are circular and each is allocated a rotatable, powered blade member (51) which in operation disintegrates the dried mass and empties it from each dish unit (34 - 40) for removal from the stack of dishes.

Description

Method and device for drying of flowable substances

The invention relates to a method as stated in the introductory part of claim 1 , for drying a flowable substance, as well as a device for conducting this method.

In this connection "flowable substance" is intended to mean any fluid or sludge composition containing a surplus of a fluid, particularly water, where a partly or completely vaporization of the fluid is desirable.

Background

In many circumstances, it is desirable to remove a liquid from a liquid containing mass. One example is the removal of water from drilling mud.

Convection driers in which the mass to be dried is moved continuously from level to level in a carousel, hot gas, e.g. air, being circulated are known. Such processes and equipment are usually used for particulate substances, the drying is provided by circulating gas.

Also known are contact driers which move the substance to be dried continuously from level to level in a stable of dish units, each dish being heated. This drier can only function when the mass can flow freely, without adhering to the dish surfaces. This drying is therefore not suitable for various muds.

Further, it is known to dry a substance on heated trays under vacuum. This process is suitable for various substances. However, the capacity of this kind of discontinuous operation is too low for most kinds of industrial drying, including drying of residues from the oil industry.

Object

The main object of the invention is to provide a method and a device for providing contact drying in batches, preferably under vacuum, with higher capacity than known methods/processes or at least to provide the public with a useful choice.

The Invention

The method according to the invention is stated in claim 1. This allows a substantial capacity increase for a given size of the device compared to prior art methods. This can be achieved with a device which is substantially simpler than prior art continuously operated contact driers.

Claim 2 states favourable features of this method.

A device according to the invention for carrying out this method is stated in claim 4. This device has a simple structure and a high capacity compared to the size.

An important advantage is the possibility to provide different capacities with standardized parts. It will also be suitable for substances which are not easily dried in a continuous process.

Claims 5 to 7 states particularly advantageous features of the device. The invention is described more detailed in the following examples.

Examples:

The Invention is described in the following with reference to the drawing, wherein Figure 1 shows a sectioned side view of an embodiment of a drying device according to the invention, with seven levels,

Figure 2 shows a plane view from above, of the drying device of Figure 1 , Figure 3 shows a perspective view of a dish with a rotating scraper for the drying device in Figure 1 , while

Figure 4 shows a sectioned side view of a drying dish as shown in Figure 2.

Detailed Description of the Invention The drying device of Figure 1 comprises a cylindrical, closed container 11 arranged with a vertical axis on three legs 12, two of which are shown. The container 11 comprises a tubular main part 13 with a lower and an upper annular flange 14 and 15, respectively, a funnel shaped bottom 16 attached with bolts to the lower annular flange 14, and a domed lid 17 attached with bolts to the upper annular flange 15. At the lower end of the funnel shaped bottom 16, a valve 18 is arranged with connection to an output screw 19.

In the container 11 a central, axial tube 20 is arranged, which at the lower end rests on a stud 21 for sliding up and down, and at the upper end 22 providing a slide valve in a guiding tube 23 suspended from the top of the lid 17, The upper end 22 of the tube 20 is extended upward with an activating and powering rod 24, into a gear housing 25 at the top of the lid 17, with an axially relocatable engagement with a operatinging device 26 powered by a motor 27. On the top of the gear housing 25, the activating and powering rod 24 is linked to an activating arm 28. The activating arm 28 is at one end 29 linked to a rib 30 on the lid 17. At the other end, the activating arm 28 is connected to a linear motor 31 , e.g. an air cylinder with a piston, for moving of the axial tube 20. The purpose of this design will become apparent from the following description.

On the lid 17, an air powered ejector 32 with a suction tube 33 extending under the lid, is also arranged.

Along the central tube 20, seven dish units 34 - 40 as shown in figure 3 and 4 , are stacked. The dish units 34 - 40 each comprise a drying dish 41 with a rim 42 which is outwardly bevelled. Centrally a sleeve 43 extending from the bottom to the level of the rim 42 is arranged.

Under the bottom of the drying dish 41 , a closed second bottom 44 with a steam supply tube 45 is arranged.

Distributed along the circumference, four brackets 46 with a slot 47 from the free edge are arranged, for locking the dish units 34 - 40 against turning.

The sleeve 43, having a casing 48 extending over the edge of the sleeve, is provided with a lower shirt which covers the end of the sleeve 43 of the underlying dish unit. The casing 48 is suspended under a rotor arm 51 as described below.

Inside the casing 48 is a carrying sleeve 50 which is without contact with the dish unit. The sleeve 50 carries a two-sided rotor arms 51 which extends across the dish unit. The sleeve 50 is dimensioned according to the diameter of the central tube 20, to be attached thereto. On rotating the tube 20, the sleeve 50 and the rotor arms 51 of the dish units 34 - 40 are also rotated, and by lifting of the central shaft 20 with the activating arm 28, the rotor arms 51 are lifted from the bottom of the drying dish.

The rotor arms 51 , shown more detailed in Figures 3 and 4, have a sheet joke 52 with a radial reinforcing rib 53 and upwardly inclined ends 54. At the sleeve 50, an annular collar 55 is arranged. Under the rotor arm 51 and as an integrated part thereof, both parts of the arm have a series of blades 56, five on each side. The blades 56 are arranged at an angle to the rotor arm, to provide a scraping effect on rotation. For the inlet of a substance to the drying device, the lid 17 has an inlet tube 57. The inlet tube can be connected to a supply tube from a pump or from a silo. When the mass is supplied to the upper dish unit 40 in the stack, this will be filled and mass will flow over the edge of the inner sleeve 43 and from there fill all lower dish units. In an alternative embodiment, is the mass supplied distributed among the dish units.

Utilization

After the supply of a substance to be dried to the drying unit, a heating medium is supplied, e.g. steam, to the double bottom 44 through supply tubes. By operating the ejector 32, a vacuum is created to remove vaporized water from the substance.

Thus the drying is started with batch operation. The supply of steam is conducted with stationary and lifted rotor 51 until the drying is finished. Then the rotor arms 51 are lowered by activating the linear motor 31 , and rotated. The rotation of the blades 56 will have a scraping effect on the dried mass, and moves the content towards and over the edge 42. The particles of the substance will fall through the annular space 58 at the wall of the container and be collected at the bottom for removal with the screw 19.

The device according to the invention can be used for various fluid residues, such as drilling mud, fluids containing oil, various oils and recycled oil, residues from fish processing and butchers, from fishfarming, and flowable masses containing chemicals or being contaminated, e.g. by chemicals. The drying can be both for recycling and for destruction.

Modifications

The dish units may be provided with other kinds of heating element than the double bottom for steam. Tube heater or electro heater or combinations of different heating systems can be used. The number of rotor arms and of blades may be lower or higher than shown in the example.

The device according to the invention can advantageously be arranged in groups of identical multiple units, e.g. two, supplied with substance for drying from a common supply, operated by a common pump and energy unit and leaving the dried mass to a common receiver.

Claims

1. A method for drying of batches of flowable substance by heating the substance on dishes arranged in a stack of dish units in a closed container placed under vacuum and supplied with heating energy to the individual dishes, in which the substance is dried on stationary dishes and that the substance, after stationary drying is mechanically disintegrated with a rotating member and removed from a dish unit via the underlying unit, for emptying the drying dishes before replenishing of fresh substance to be dried.

2. A method according to claim 1 , in which a vacuum is created in the closed container with a fluid supplied to an ejector.

3. A device for conducting drying batches of a flowable substance comprising a stack of circular dish units arranged in a closed container, each dish unit having a drying dish with a heating element and wherein the closed container is connected to a vacuum pump with a supply conduit for the substance to be dried arranged above the upper dish unit of the stack, and wherein drying dish is allocated a rotatable, powered blade member which at intermittent operation after drying, disintegrates the dried mass and moves it from one dish unit to a lower dish unit or from the stack of dish units, for collecting and removal from the container.

4. A device according to claim 3, wherein each drying dish has a central collar which is lower than the outer edge of the drying dish, for overflow of disintegrated, dried mass.

5. A device according to claim 4, wherein, arranged radially inside each annular collar is a tubular casing with a radially extended lower shirt for leading fresh mass to a lower drying dish.

6. A device according to any one of the claims 3 to 5, wherein a rotatable shaft is arranged centrally to the stack of dish units, and wherein a rotor with at least one arm and carrying blades is arranged over each dish to disintegrate the dried mass on each drying dish and move the disintegrated mass toward and over the edge.

7. A device according to claim 6, wherein the shaft is axially movable with a power member to lift the blades from the area of the drying mass, and lower it to the bottom of the dish.