Drum dryer BN 2.8-16-NU-03

Contents

Introduction

1 Analytical Overview

2 Description of apparatus design and operation principle

3 Selection of main structural materials

4 Strength calculation of stiffness and stability of elements

drum dryer

5 Technology of apparatus manufacturing

6 Repair and installation

List of literature

Introduction

Drying is the removal of moisture vapors generated when heat is supplied to the dried materials (bulk, liquid and paste). The intensity of drying depends on the method of supplying heat to the material being dried and removing evaporating moisture, as well as the speed of movement of moisture from the depth layers of the material to its surface. The latter, in turn, is determined by the thermophysical properties of the material to be dried and the form of moisture bonding therewith.

Due to the large range of materials to be dried (more than 200 thousand types of materials are dried in the chemical industry), many different types of dryers are used, which makes it difficult to clearly classify and typify them.

Selection of basic structural materials

According to a task for the term paper the drum dryer BN 2,816NU03 is manufactured of knots and details, adjoining to a product, of carbon steel.

At an operating temperature from 20 to +350 wasps for production of the case of a drum and also loading and unloading cameras GOST 38088 VSt3ps2 steel is recommended.

For the manufacture of support and support shrouds, we accept steel 45 as per GOST 105088.

For the manufacture of support and thrust rollers, steel 35 is adopted as per GOST 105088.

For production of axes of support rollers we accept steel 45 as per GOST 105088.

Strength calculation of the stiffness and stability of the drum dryer elements

4.1 Selection of initial data

4.1.1 Design temperature

Operating temperature of the heat carrier on an entrance to drum dryer 280 wasps, and 100 wasps at the exit from the dryer. As a rule, the calculated wall temperature of the dryer body is taken equal to the temperature of the medium increased by 20 ° C.

We accept the design temperature of 300 wasps.

Technology of apparatus manufacturing

Production of cylindrical shell of drum body.

Manufacturing of single-seam shell in heated state. Shell blank is coated with chalk solution on both sides to prevent scale formation and is loaded into furnace. After heating, the sheet is taken out of the furnace and fed to the roll table of the sheet bending machine. At the same time, it is necessary to ensure that the temperature of the workpiece does not fall below 1050 ° C. From the surface of the blank, the scale is also cleaned in a minimum period so that the temperature of the blank does not decrease less than 1000 ° C. After bending of blank on sheet bending machine it is supplied to stand for assembly of longitudinal joint. Immediately before the assembly, the length of the circle (sweep) is measured at the ends and in the middle of the shell and its diameter is determined. Displacement of edges along thickness is eliminated, places of installation of clamps and pockets are marked and clamps, pockets and outlet plates are installed at longitudinal joint, they are gripped by electric welding and welded finally. Longitudinal edge of shell joint is placed for gas cutting. After the edge section the shells are cleaned from traces of scale and rust to metallic gloss. After electric slag welding of longitudinal joint, cutting of clamps, pockets, grinding and control, shell surfaces are coated with chalk solution, shell is loaded into furnace, heated to 980 ° C and supplied to sheet bending machine for straightening. The shell is then removed from the machine and the weld is X-rayed, cut and corrected.

As a result of heat treatment of steel, a scale appears on the rolled stock surface. After double normalization, its thickness is 0.71 mm, after tempering 0.090.13 mm, which in both cases cannot be removed by solvents, but can be removed by a blasting machine.

Main requirements for welding:

1) Proper preparation of seams - edges must be cut.

2) Compliance with the applied technology is primarily the choice of electrodes. Electrodes and additive materials are selected depending on the steel grade from which the part is made.

Repair and installation

Dryers are long and are supported by rollers mounted on separate foundations. The inner surfaces of the dryers are washed with hot gases. In this regard, sometimes drums are lined with refractory materials inside. When drying abrasive materials, the inner surfaces of the drums, like the drum mills, are booked.

During operation, bearings and trunnions of rollers (axes) of support rollers, surfaces of support rollers and support bands, internal partitions, casing shells, end sealing rings, etc. wear out.

The rollers are made of steel with a slightly lower hardness than the steel from which the bands are made. This is due to the fact that changing or restoring the roller is easier than shrouding. The surfaces of the rollers must be well treated. To increase wear resistance, surfaces of rollers are laid with hard alloys. Roller is fitted on roller by hot fit. Roller is installed on roller centers for processing. At the same time worn out trunnions of the roller itself are restored to initial dimensions.

Improper installation of rollers and their uneven wear can cause deflection of the drum. Other drum failures are possible; violation of welds, formation of bulges, wall blowing. Therefore, during repairs, the drum is carefully checked. Shells are restored according to conventional technology for cylindrical devices.

Bandages wear out during long-term operation and their shape is distorted. The surfaces of the bands are swept in place. If the degree of wear is such that it is impossible to stroke the band, it is removed. This operation is very laborious: they remove the adjacent shell of the drum with the band, cut or rivet the old band, put a new one, then the shell with the band is installed in its former place and brewed.

After repair of the units, the rectilinear and slope of the drum axis, the uniformity of resting by all bands on their roller supports, the coaxiality of the sealing rings, etc. are checked.

Installation of equipment means a set of works related to bringing it into operation. For this purpose, the installed equipment must be fully assembled, installed in the design position and included in the process diagram of the unit or installation.

By the beginning of the installation work, lifting and transportation equipment should be installed, health, safety, fire safety measures should be carried out. Compliance with design of equipment nozzles and support structures shall be checked. The results of the inspection are drawn up by acts.

Equipment installation includes the following main operations: preparation and installation of mechanisms and devices for lifting and installation of the apparatus on the foundation; unpacking of equipment, completeness check and acceptance for installation; preparation of equipment for installation (cleaning of preservation lubricants, assembly of equipment, hydraulic tests, application of thermal insulation, etc.); foundation check and installation of foundation bolts; moving the equipment within the installation area; lifting and installation of equipment to the design position; reconciliation and fixation of equipment on the foundation; installation of internal devices; removal of lifting devices; strength and density tests; preparation for equipment commissioning with execution of necessary documents.

After setting of foundation concrete and fixing of foundation bolts, the position of the axes of the units is finally checked. Check is performed on at least two mutually perpendicular planes. In the case of drums, the lifting and installation of the blocks starts with a drive mechanism, which allows the mounted shells to be rotated around their axis. This facilitates fitting, alignment and welding of shell joints. When rotating the shells, it is possible to easily set the run-out of their ends using a pin mass. Installation of air ducts and dust collecting chambers in each individual case is carried out in accordance with the instructions in the installation drawings.

During installation of drum dryers, the bed and other support devices are carefully checked. To do this, use levels and plumbs, as well as special indicators. Liquid concrete is poured under support structures after their final attachment. Trial start-up can take place only after holding the required period of concrete setting and hardening.

Drying drums are put into operation after a trial idle run during the time specified in the certificate. At that oil temperature in bearings, density of joints, density of grinding chambers and crankcase, etc. are checked.

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