RU2752432C1 - Twin-screw conveyor with electric heating elements - Google Patents

Abstract

FIELD: screw conveyors.

SUBSTANCE: invention relates to screw conveyors and can be used for loading organic waste, drilling oil sludge and waste lignin sludge into a reactor for their thermal processing. The twin-screw loading device contains a shell 1 with windows 2 and 3 for loading and unloading. Inside the shell 1, there are two engaging augers 5 with parallel axes connected with a augers’ rotation drive. On the outer surface of the shell 1 there are installed heating sections 19, each of which includes a split casing 13 with electric heating elements 12 fixed in it. The cross-sectional contour of the inner surfaces of the cage 13 adjacent to the shell 1 repeats the contour of the cross-section of the outer surface of the shell 1.

EFFECT: invention allows significantly reducing the time for replacing an inoperative electric heating element and preventing clogging of the internal chamber of the device with the supplied product.

6 cl, 4 dwg

Description

The invention relates to screw conveyors and can be used for loading organic waste, drilling oil sludge and waste lignin sludge into a reactor for their thermal processing.

Known screw conveyor, made according to a single-screw scheme, having electric heating using an intermediate heat carrier - oil. The housing of the screw conveyor is surrounded by a jacket, in the cavity of which electric heating elements are located, the jacket is filled with oil. The cavity of the jacket is connected to an expansion tank through which the coolant is filled and replenished. Also, the jacket has drain, filling fittings and devices for controlling the temperature of the coolant. The auger shaft bearings are located outside the inner cavity (CN 206984990 U, publ. 09.02.2018).

The disadvantage of this device is the type of heating using an intermediate heat carrier, in which additional devices are needed to ensure the circulation of the heat carrier, the complexity of repairing the heating system, the need for periodic oil changes and monitoring of its condition. There is also a possibility of oil getting into the cavity of the internal chamber of the device and vice versa of the product getting from the internal cavity of the device into the cavity of the coolant.

Also known is a screw conveyor for transporting drill cuttings over a wide temperature range. The conveyor contains a body made in the form of a trough, closed with a cover, at the ends of which drive and non-drive bearing supports are installed, each of which consists of a body and a spherical roller bearing, a quick-detachable screw auger is installed in the trough on the supports, made in the form of a shaft with a screw blade, on the lower outer part of the conveyor body, a steam jacket is fixed, which is a metal rolled sheet and forms a cavity, divided into sections by stiffening ribs made on the body; stiffening ribs contain holes for free passage of steam between the above-mentioned sections, each of the sections is equipped with an outlet pipe for condensate discharge, and the first section is additionally equipped with an inlet pipe for steam supply (RU 184124 U1, publ. 16.10.2018).

The disadvantages of this screw conveyor are the complexity of the design and manufacture of heating elements, requiring a large number of welding operations and the formation of a large number of internal cavities in which condensate can form and accumulate, leading to accelerated wear of the structure and a decrease in the reliability of work.

Known system for heating grain material, which contains a screw conveyor having a housing made in a U-shaped section, and a cover. The screw is located in the housing with the possibility of rotation. On the outer surface of the body there is a number of volumetric electric heaters, also having a U-shaped cross-section, and on the cover there is a number of flat electric heaters. Volumetric electric heaters, like flat ones, are connected in parallel. Electric heaters are made on the basis of butyl rubber and have an electrically conductive layer with electrodes placed in an insulating layer. Each volumetric electric heater has electrodes located along its shape. The electrodes are installed at an equal distance from each other, and the outermost of them are located at the junction of the cover. The auger conveyor has loading and unloading windows, and the auger of the auger conveyor is equipped with a drive (RU 2322297 C2, publ. 20.04.2008).

The disadvantage of this solution is that heaters based on butyl rubber have a maximum operating temperature of 100 ° C, and this is not enough for heating organic waste to a temperature of 40 ° C before processing. The screw conveyor is made according to a single-screw scheme, which is suitable for grain, but not for oil sludge, and when the product sticks to the screw screw, there is no possibility of self-cleaning. The housing of the auger conveyor is not hermetically sealed, as the grain does not need to be sealed.

The closest to the proposed one is a heated screw conveyor containing a cylindrical housing with a screw located inside it, which is connected to a drive. The body is wrapped with a heating tape, on top of which there is mineral wool insulation on the body (Heated screw conveyor ШС-160П https://jasko.all.biz/shnekovyj-transporter-s-podogrevom-shs-160p-g7333616; Zhasco. Auger conveyors. Auger heated conveyor ШС-160П https://jasko.nt-rt.ru/images/manuals/shnek-transport.pdf). This conveyor is made as a prototype.

The disadvantage of this solution is that if the heating tape fails, disassembly of the entire heating structure will be required, and if the screw conveyor is mounted in cramped conditions, then the disassembly of the insulation may require dismantling the entire conveyor. Repairing or replacing a heating tape (heating cable) is a laborious and costly operation. In addition, the conveyor is also designed as a single-screw, and when the product sticks to the screw, there is no possibility of self-cleaning of the screw.

The technical problem solved by the invention is to ensure a continuous supply of the heated product to the reactor, to significantly reduce the time for replacing an inoperative electric heating element, to prevent clogging of the internal chamber of the device by the supplied product, as well as to maintain excess pressure in the reactor due to the tightness of the internal chamber of the device.

The technical result achieved by the invention consists in providing the possibility of quick replacement of an inoperative electric heating element due to the modular design of electric heating while ensuring the cleaning of the screw surfaces of the screws.

The technical result is achieved by a twin-screw loading device containing an oval-section shell with windows for loading and unloading, two engaging augers with parallel axes located inside the shell, a screw rotation drive and heating sections installed on the outer surface of the shell, each of which includes a split cage with fixed in it electric heating elements, while the contour of the cross-section of the inner surfaces of the cage, adjacent to the shell, repeats the contour of the cross-section of the outer surface of the shell.

In a preferred embodiment, the electric heating elements are tubular electric heaters, the axes of which are located along the axes of the screws.

In addition, each split yoke preferably consists of two C-shaped portions.

In a particular case, the auger rotation drive includes a gear motor connected to the auger shafts by means of chain and gear drives so that the augers can rotate in opposite directions.

It is also preferred that the screws are mounted in bearing assemblies located outside the shell chamber.

To ensure the tightness of the inner chamber of the shell, flanges with sealing elements of the auger shafts are installed at its ends.

The invention is illustrated by drawings.

FIG. 1 shows the proposed device with heating elements, front view with a partial section of the chamber.

FIG. 2 - the same, top view.

FIG. 3 - the same, section A-A.

FIG. 4 is an isometric view of the heating section.

The twin-screw loading device with electric heating elements is a sealed inclined shell 1 with a product loading window 2 on one side, and an unloading window (nozzle) 3 on the other (Figs. 1, 2). In a preferred embodiment, the shell 1 has a cross-section in the form of two semicircles connected by equal straight line segments. Inside the shell 1 there are engaging screws 5 with parallel axes. The axes of the screws 5 are located parallel to the axis of the shell 1, and the turns of each screw 5 enter the space between the turns of the other screw 5 (Fig. 3). Along the ends of the shell 1 there are flanges 4 with sealing elements 6 of the shafts of the augers 5. From the side of the loading window 2 to the flange 4 of the shell 1 through the studs a bearing plate with bearing units 7 is fixed, from the side of the discharge branch pipe 3 a bearing plate with bearing units 7 is also fixed, toothed gear 8, chain drive 9 and gear motor 10. Gear motor 10 is connected to the augers 5 through chain drive 9 and gear drive 8. Bearing assemblies 7 are placed outside the chamber of the device to prevent them from overheating and clogging.

Above the discharge nozzle 3 is a sealed hatch 11 for maintenance.

Along the shell 1 on the outside, there are heating sections 19, each of which contains electric heating elements 12, which are tubular electric heaters installed in steel split clips 13 with ceramic insulation 14. Each split clip 13 consists of two identical C-shaped parts (Fig. 4). To ensure uniform heating, tubular electric heaters 12 are located parallel to the axis of the shell 1 with an equal pitch.

On the outer part of each cage 13 there are fastening elements 16 for connecting parts of the cage 13, and electrical leads 15. The cross-section of the surfaces of each cage 13 adjacent to the casing 1, its shape repeats the shape of the cross-section of the outer surface of the casing 1, which ensures tight fit of the cages 13 to the shell surface 1.

To control the temperature and pressure inside the chamber of the device, the temperature and pressure sensors 17, 18 are located on the discharge nozzle 3 (Fig. 1).

This device is effectively used for feeding a product for thermolysis processing.

The proposed twin-screw charging device with electric heating elements operates as follows.

The prepared product is fed into the loading window 2 of the device, is captured by the screws 5 rotating towards each other, and is fed along the shell chamber 1 to the discharge nozzle 3 and further into the reactor. Due to the engagement of the screws 5 during rotation, the screw of one screw 5 cleans the surface of the screw of the other screw 5, preventing the product from sticking.

Due to the continuous operation of the device, as well as the dense filling of the loading window 2 with the product, the inner chamber of the shell 1 remains sealed, which does not allow gases from the reactor to enter the atmosphere.

The nozzle 3 for unloading the device through the flange is hermetically connected to the nozzle for loading the reactor (not shown in the drawings). The screws 5 are driven by the gear motor 10 through the chain and gear drives 9 and 8. Maintenance is carried out through a sealed hatch 11 located above the discharge nozzle 3.

The product is heated by means of electric heating elements 12 installed along the shell 1, located in the clips 13. The clips 13 are tightened with bolts, which allows you to quickly replace a failed heating element by removing one heating section 19 without dismantling the entire heater. To control the intensity of heating, each heating section 19 can be turned off separately, and it is also possible to turn off the electric heating elements 12 through one inside each cage 13.

Claims (6)

1. A twin-screw loading device containing a shell with windows for loading and unloading, two engaging screws with parallel axes installed inside the shell, a screw rotation drive and heating sections installed on the outer surface of the shell, each of which includes a split casing with electric heating elements fixed in it, the contour of the cross-section of the inner surfaces of the cage, adjacent to the shell, repeats the contour of the cross-section of the outer surface of the shell. 2. The device according to claim. 1, in which the electric heating elements are tubular electric heaters, the axes of which are located along the axes of the screws. 3. The device of claim. 1, wherein each split cage consists of two C-shaped parts. 4. The device according to claim. 1, in which the drive for rotation of the screws includes a gear motor associated with the shafts of the screws by means of chain and gear drives, allowing the screws to rotate in opposite directions. 5. The device according to claim 1, in which the screws are installed in bearing assemblies located outside the shell chamber. 6. The device according to claim 1, in which flanges with sealing elements of the auger shafts are installed on the ends of the shell.

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