Stirrer 54/102

Technical assignment for the course project on applied mechanics

The purpose of the project is to develop, in accordance with the initial data, sketched, technical designs and fragments of working design documentation for a typical apparatus with a mechanical mixing device, designed to carry out the mixing process in a liquid-phase system at the specified process parameters and properties of the working medium, with ensuring operability in working conditions for a given service life.

Introduction

Modern technological equipment includes a variety of technical devices: machines, devices and devices. A machine is a device that performs mechanical movements in order to perform useful work by converting energy. The kinematic basis of any machine is a mechanism, that is, a device in the form of a system of bodies that converts the movement of some bodies into the expedient movement of other bodies. By the term apparatus in the chemical industry is understood a device in which the technological process is carried out due to physicochemical transformations. Some processes occur at elevated pressures and temperatures of treated media, which can be aggressive, toxic, explosive, fire hazardous, and include expensive components. Such process characteristics require increased safety and reliability of the equipment.

Devices are usually equipped with various heat exchangers, machines, mechanisms, as well as instruments and devices that perform the functions of control, measurement, regulation and control. Structural materials used for the manufacture of equipment elements shall ensure strength, corrosion resistance and heat resistance in operation.

Design is the development of a common product design. Design is the definition of the shape and dimensions of all features

general design of the product.

Project - a set of text and graphic documents obtained as a result of design and construction, designed for the manufacture, control and operation of the product.

When designing process equipment, it is necessary to ensure its high quality, that is, a set of properties that determine the functioning of the equipment in accordance with its purpose. Quality is characterized by: technological efficiency, economy, reliability, convenience, ease of maintenance and operation, and other properties. Process efficiency is determined by the efficiency of the process. Cost effectiveness is determined by the overall cost of designing, manufacturing, erection, operation and disposal of the equipment after the end of its service life. Reliability is the property of the product to perform the specified functions, keeping its performance within the specified limits for the specified service life.

During design it is necessary to observe the sequence of design works and the rules of technical documentation (explanatory note, drawings).

Project Goals and Objectives

The purpose of the course project on "Applied Mechanics" is to develop, in accordance with the initial data, sketched, technical designs and fragments of working design documentation for a typical apparatus with a mechanical mixing device, designed to carry out the mixing process in a liquid-phase system at given pressures, temperature and properties of the working medium, while maintaining operability in working conditions for a given service life. As well as the development of skills in the practical application of knowledge obtained by students during the study of the cycle of general engineering disciplines.

A stirrer is one of the most common types of chemical and technological equipment. It consists of typical elements found in many devices for various purposes: housing, drive, heat exchange devices, flange joints, shaft seals, etc. Calculation techniques used in the design of a stirrer are typical, that is, common to many other types of equipment.

During the course project the following tasks are set:

a) mastering the basis of the design methodology;

b) competent use of all-Russian and industry regulatory documents (GOST, OSts, Rostekhnadzor rules, etc.) related to the design, selection of operating parameters and rules for the operation of equipment of chemical industry enterprises;

c) selection of structural, sealing materials, selection of typical elements of the apparatus and assessment of its reliability;

d) performance of design and check calculations of typical elements according to the main criteria of their operability, which make it possible to identify the compliance of the apparatus with the requirements of operation (at the same time, special attention should be paid to opening the reserves of operability of standardized elements and increasing equipment productivity);

e) structural design of the apparatus in accordance with the given process parameters;

e) competent report and protection of the adopted technical decisions at the meeting of the commission for the reception of course projects .

General characteristics of the designed apparatus

Stirrers are widely used in chemical and many other industries. In devices of this type, many hydromechanical and mass exchange processes are carried out in one- and multiphase media (emulsions, solutions, suspensions). Substances with various properties, including aggressive, explosive, fire hazardous and toxic, are used as the working medium. The processes are usually carried out at elevated temperatures, overpressure or vacuum. Mixing intensifies heat and mass transfer processes and is often a prerequisite for the efficient flow of chemical reactions. The design of the apparatus shall ensure its reliable operation in the specified process mode during the specified service life. Chemical devices are subject to periodic inspections of scheduled preventive repairs.

The sets can be vertical and horizontal. The main elements of the apparatus are a body and a mechanical agitator. In general, the shell of the body consists of a cylindrical part connected to the bottom and cover, which have an elliptical, conical, hemispherical or flat shape. Apparatus housings are standardized (GOST 9931-85).

By the body of the apparatus is meant a hermetically closed pressure vessel in which mixing is carried out. Vertical apparatus housings can be of two types: WEE (vertical, elliptical bottom, elliptical cover); VRE (vertical, conical bottom, elliptical cover). Mechanical mixing devices (LCP) of all devices are structures consisting of a drive, a shaft and a stirrer. The agitator drive consists of an electric motor, a mechanical transmission in the form of a reduction gear or a belt transmission and a drive post. Electric motor converts electric energy into mechanical energy. Reduction gear transmits rotary motion from motor shaft with reduction of rotation speed and increase of torque on output shaft of drive. The drive strut, combining the drive parts into a single unit, serves to attach the LCP elements. The output shaft of the reduction gear is connected to the shaft by means of a coupling (longitudinal-detachable or flange). At the end of the shaft there is a stirrer: three-blade, vane, turbine open or frame.

Chemical devices are subject to periodic inspections and scheduled preventive repairs.

In this course design, a typical apparatus (of the WEE type - vertical with an elliptical bottom and a detachable elliptical cover with an integral jacket) with a mechanical mixing device is being developed. The apparatus has additional internal devices - baffles and a transfer pipe. The apparatus is designed to carry out a mixing process of 40% AlNO3 solution at an excess pressure of 1.08 MPa and a temperature of 100 ° C. The stirring device is a turbine open stirrer.

Conclusion

In this course work, an apparatus with a stirrer was designed, which consists of the following elements:

housing consisting of a number of elements and devices: shell, cover,

bottom, flange connection of the housing, etc.;

driving a mechanical agitator;

turbine open stirrer;

stirrer shaft;

compacting the stirrer shaft;

shaft coupling;

supports-struts and mounting trunnions;

Materials were selected for the elements and devices of the set:

for the case - 12X18H10T+ St3sp;

for stirrer drive, stirrer shaft, flanges, couplings - 12X18H10T, steel

and 20;

support-struts and mounting trunnions - St3sp;

for bolts - 40x and 40.

for gasket - PE electrolytic;

The calculations showed that the device will be able to pass the tests of Gosgortekhnadzor and function for a given service life under normal operation.

In this work, an apparatus with the following main reliability indicators is designed:

strength of the apparatus body at operating pressure, as-built thickness of the cover walls, cylindrical shell;

the bottoms are 6, 5 and 5 mm respectively. Strength conditions are fulfilled at operating pressure ppv = 0.040 MPa and residual po =

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0.020 MPa; maximum permissible internal rdop.in. and external rhodop.n pressures are 0.574 and 0.092 MPa, respectively.

Tightness is ensured by tightening force 65000N. At that tightness margin ng = 1.496, conditions of bolts strength in conditions of installation and operation are fulfilled, stresses in bolts material are equal to 72.33 MPa and 81 MPa, respectively, at permissible voltage of 126 MPa; the strength condition of the gasket material is satisfied, the specific load q is 10 MPa at a permissible specific load of 130 MPa;

load-carrying capacity and stability of support ribs. Selected Type-

the size of the support posts and trunnions can be selected, since the design loads on one support Gop and trunnion Gz do not exceed the permissible loads on the support Gdop and trunnion Gdopz (13.07 and 4.75; 25 and 20 kN, respectively). The strength conditions of the foundation concrete are also met;

strength, vibration resistance. The strength condition is satisfied by

the maximum tension on torsion of a shaft τкр there are less allowed tension on torsion [τ] kr (9.62 MPas and 59 MPas sootvet-

only). The shaft is vibration resistant and operates in the pre-resonance zone (zhѐstky shaft), the limit angular speed is [omega] pr = 27.03 rad/s, (258 rpm).

loading capacity of couplings. The selected clutch size (elastic sleeve-pin clutch) can be done because

design torque on the shaft section for clutch T.m. = 180.84 Nm is less than the rated torque for

of this clutch size Tnom = 500 Nm.

The calculations showed that the device will be able to pass the tests of Gosgortekhnadzor and function for a given service life under normal operation.

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The following are technical characteristics of the apparatus and technical requirements for manufacturing and testing.

Technical characteristics of the apparatus:

Nominal volume - 2.5 m3, working volume - 2.275 m3.

Medium in the apparatus: HNO3, density 1050 kg⁄m, temperature 100.

The service life of the device is 15 years.

Operating pressure in the housing:

superfluous ri = 0.40 MPas,

residual po = 0.020 MPa.

Maximum pressure in the housing:

internal ppv = 0.51 MPa,

external ph = 0.092 MPa.

Electric motor power:

nominal N = 3 kW,

design Np = 2.6 kW.

Drive: type 1, version 3, dimension 1.

Agitator shaft speed:

operating n = 160 rpm,

limit npred = 258 rpm.

The weight of the device in operating condition is not more than 4 tons.

Technical requirements for fabrication and testing:

The device to make and test according to GOST 20680-2002 "Ap-

parats with mechanical mixing devices. General technical requirements. "

Fabricate and test the apparatus housing in accordance with OST 26-291-94

"Steel and welded vessels and apparatus. General Specifications. "

The apparatus is subject to registration with the bodies of Gosgortekhnadzor and must co-operate

Follow the instructions "Rules for the construction and safe operation of pressure receptacles."

Perform hydraulic test of the apparatus housing with test pressure

lithium 0.40 MPa.

Material of the case of the device is St3sp steel 12X18H10T+, in bulk, mixers,

keys and flanges - 12X18H10T GOST 5632-72, supports - St3sp5 GOST 380- 2005

Permissible corrosion rate is not more than 0.1 mm per year.

End seal shall comply with OST 26-01-

88-87 "End shaft seals for devices with mixing devices. General technical requirements. "

Flange connections of the housing with the cover of the apparatus and the hatch shall be as follows:

follow GOST 28759.5-90 "Flanges of vessels and devices. Technical requirements. "

Stirrer design as per ATK 24.201.17-90, connectors - as per ATK

24.218.06-90, apparatus housing - as per GOST 9931-85.