MVS-4150 roller mid-engine mill

Contents

INTRODUCTION

PROCESS PART

Justification and description of selected process

production schemes

2 SPECIAL PART

2.1 Analysis of roll mill design and operation principle

2.2 Patent search and analysis of its results

2.3 The Essence of Modernization

2.4 Calculation of the main parameters of the roller medium-speed mill

2.4.1 Determination of mill capacity

2.4.2 Determination of the number and size of grinding rolls

2.4.3 Determination of working elements speed

2.4.4 Determination of roll force on grinding layer

material and roll axis loads

2.4.5 Determination of gutter geometry and roll mounting angle

2.4.6 Calculation of roller suspension pins to the frame and bars

2.4.7 Calculation of roll angle adjustment bolt

2.4.8 Determination of motor power of the main drive

mills and specific energy consumption for grinding

2.5 Separator Calculation

2.5.1 Determination of conventional axial speeds of drying agent

in mill areas

2.5.2 Determination of separator diameter

2.5.3 Determination of maximum particle size and boundary

divisions

2.5.4 Determination of separator drive motor power

3 ELECTRICAL PART

3.1 Calculation of engine parameters as per T-diagram of replacement

3.2 Transmitter Selection

3.3 Converter block diagram and description

3.4 Development of electric drive power circuit

3.4.1 Description of power circuit

3.4.2 Selection of power circuit elements

4 LIFE SAFETY

4.1 Analysis of production conditions

4.2 Measures excluding injuries and occupational

diseases

4.3 Environmental Protection

5 ECONOMIC PART

5.1 Feasibility Study

5.2 Evaluation of the cost-effectiveness of the investment project

5.2.1 Calculation of capital investments

5.2.2 Change of operating costs by factors

5.2.3 Changing Cash Flows

5.2.4 Calculation of project cost-effectiveness indicators

5.3 Planning of cost of products and basic equipment

economic indicators

5.3.1 Product Cost Planning

5.3.2 Adjustment of the main technical and economic indicators

CONCLUSION

List of literature

Applications

Introduction

Electric drive is an electromechanical system that ensures the implementation of various technological and production processes in industry, agriculture, transport, public utilities and in everyday life using mechanical energy. The purpose of the electric drive is to ensure the movement of the actuators of the working machines and mechanisms and to control this movement. In other words, the electric drive, being the energy basis for the implementation of technological and production processes, largely determines their quality, energy and technical and economic indicators.

Scientific and technological progress, automation and complex mechanization of technological and production processes determine the constant improvement and development of modern electric drive. First of all, this refers to the increasing introduction of automated electric drives using a variety of semiconductor power converters and microprocessor control tools. New types of electrical machines and devices, variable coordinate sensors and other components used in electric drives are constantly emerging.

The expansion and complexity of the functions performed by the electric drive, the use of new elements and devices in them, the increasing inclusion of the electric drive in the automation systems of technological processes require a high level of training of specialists involved in their design, installation, adjustment and operation. They must understand the main physical processes taking place in electric drives, know the purpose, device, principle of operation, properties and characteristics of their components, understand the control circuits and be able to select their elements, as well as determine the technical and economic performance of the electric drive.

Among consumers of electricity, the leader is an electric drive. The greatest demand is the drive of small (up to 3.7 kW) and medium (up to 37 kW) power based on asynchronous motors.

Under current conditions, increasing tariffs for electric energy, the use of thyristor frequency converters (THRs) is an urgent task. The use of such actuators enables:

saving of electric energy consumption;

decrease of starting current level;

reduced response time to load change;

reduced error of speed control.

The introduction of thyristor frequency converters in the production, in addition to direct saving of electric energy, has other advantages:

electric drive provides smooth start-up and long-term operation of the mechanism in the operating range of rotation frequencies, as well as accurate automatic control of the specified process parameters;

thyristor electric drive increases the efficiency of mechanisms due to optimal implementation of various requirements for the technological process;

increased service life of electrical and mechanical equipment due to limitation of starting currents, sharp jerks, mechanical and hydraulic impacts.

In the construction materials industry, thyristor frequency converters are used to control the speed of rotation of separators used in grinding plants. In this way, the grinding fineness can be controlled within wide limits without changing the design of the separator drive.

At present, the requirements for the fineness of the grinding of materials are increasing and make attention be paid to the grinding of materials in roller medium mills, the main advantage of which is the combination of the grinding process and the heat treatment of materials. This makes it possible to grind natural moisture materials and reduce the amount of process equipment that dries the material. Therefore, the relevance of the topic I am considering in this graduation qualification work is obvious.

The essence of modernization

As a result of the patent search, an invention was chosen with copyright certificate No. 1708412, cl. In 02 C 15/04, since this invention will increase the fineness of the milled material without any particular changes in the design of the mill roll.

The rolls of the roller mill before modernization had a banding of conical cross section, which did not allow to obtain a product of particularly fine grinding that meets modern requirements.

The band, which is proposed for introduction, is also made of separate sectors, which increases the repairability of the roll and reduces the repair time, however, the cross-sectional profile of the roll consists of two parts: rectilinear and curvilinear, the length of the rectilinear part is equal to, where B is the width of the roll band, and the curvilinear part is the arc of the circle. This design of the band will increase the fineness of the ground material, which will allow to increase the competitiveness of the products.

Calculation of the main parameters of the roller medium-flow mill

The main indicator of the mill is its productivity, depending on the physical properties of the material, the coefficient of grinding ability and humidity at a constant initial size of the material. In this regard, it is customary to determine the mill productivity according to the conditions of grinding and drying.

By mill grinding capacity is meant the amount of material that can be ground with the most efficient use of input energy. The drying capacity of the mill is the amount of material that can be dried in the mill itself from the moisture at the mill entrance to a predetermined humidity. The nominal capacity of the mill does not always correspond to the optimum values of drying and grinding capacity. It may be limited by drying conditions or grinding conditions. When grinding wet and soft materials, the grinding capacity is usually higher than the drying capacity, for dry and hard materials, the drying capacity of the mill is usually higher than the grinding capacity. Therefore, the mill performance calculations are performed separately for grinding and drying.

Separator Calculation

The separator will be calculated from the following initial data.

Mill capacity for dried material, t/h QC = 300

Initial humidity of the material,% WHAP. = 20

Mill raw material capacity, t/h Q = 315

Humidity of finished product,% WKOH. = 0.5

Temperature of the drying agent at the exit from a mill, tVYH.=120 °C °

Drying agent temperature at mill inlet, ° C tBX.=450°

Material temperature at mill outlet, ° С tMW = 85 °

The type of separator is a mechanical vane rotor with an adjustable number of revolutions.

Characteristics of finished product, residues on sieves:

02 -- 1,5-2 %

008 -- 10-15 %

Frequency rate of circulation kts = 8÷10

Vacuum upstream mill, kgf/m2 HVC = -120

Vacuum downstream mill, kgf/m2 NVYKh = -720

Quantity of drying agent at mill inlet

(under normal conditions), m3/h Qvx.a. = 508500

Quantity of drying agent at mill outlet

(under normal conditions), m3/h Qvx.a. = 701100

The operation of the separator built into the body of a vertical mill with increased humidity of the initial raw materials (up to 20%) is characterized by a number of features, grinding and drying in the mill leads to an increase in circulation to kC = 8? 12 times. Only in this case does the required residence time of the material in the mill be ensured. By the nature of the behavior of the material and gas flow in the mill cavity, it can be conditionally divided into zones: "stagnant zone" - under a grinding plate and rolls; "zone of intense phantoning" - on periphery under guide nozzles. The drying agent, passing through the nozzle ring into the zone of increased cross-sectional area (under the rolls with the frame), due to inertia reduces the speed gradually.

During intensive heat exchange in the mill, the temperature of the drying agent and the volume of the conventional axial velocity will change in height. In the area of the rotor (s) of the separator, the flow must have a velocity slightly higher than that of the limited size particles. The structure of the rotary separator is such that both lateral and partly countercurrent fission takes place in it.

Another distinctive feature of the design and operation of the rotary separator is that the amount of drying agent crossing the zone of the separator blades is determined by the conditions of the need to transport the starting material to the zone of the separator and the specific loads through the air.

Transmitter Selection

Consider thyristor frequency converters produced by Russian manufacturers because they have a lower cost than foreign counterparts.

For comparison, we choose two thyristor converters that are most suitable for smooth control of the separator rotation speed: TRIOLAT04 and ERATONP1.

Consider the TRIOLAT04 converter.

Frequency-controlled converter TriolAT04 of special design - for inertial mechanisms. It provides control of mechanism operation in all modes:

smooth frequency start-up with adjustable rate;

long-term operation in a given range of rotation speeds and loads;

braking and shutdown according to the specified algorithms;

ability of TriolAT04 converter operation by signals from feedback sensors;

control of rotation speed in a large range with minimum number of starts and stops;

dissipation of energy released during braking on brake resistors.

Consider the thyristor frequency converter ERATONP1 designed for contactless start, reverse and dynamic braking of three-phase asynchronous motors by phase control of voltage on the stator winding.

Thyristor frequency converter ERATONP1 allows:

significantly reduce starting current and impact moment, which reduces fluctuations in the voltage of the supply network during start-up, increases the service life of the electric motor and mechanism;

the design of the thyristor frequency converter allows it to be used in production with high dusting and heavy operating conditions;

controlling the rotation speed over a large range;

in the thyristor frequency converter ERATONP1, a dynamic braking algorithm is used to eliminate brake current throws;

it is possible to control the brake mechanism with DC or AC electromagnetic drive;

maximum current at the converter output, in start-up mode, can be set from IH to 6IH, in dynamic braking mode - from IH to 4.5IH.

From the analysis of thyristor converters TRIOLAT04 and ERATONP1, it is clear that both converters meet the requirements for maintaining the process, but the ERATONP1 converter has more functionality and less cost. Therefore, to control the rotation speed of the separator, we select the converter "ERATONP1."

Development of electric drive power scheme

3.4.1 Description of power circuit

Power diagram is given in the graphical documentation of DPMO04 024 00 00 00 SS sheet.

The power circuit includes the following external elements: circuit breaker, fuse, indicator bulbs showing the presence and absence of power voltage, contactor. Reactors and thermal relays are supplied with the transmitter.

The engine starts when SB1 button is pressed. The KM1 coil is powered, the contactor is activated, including the contacts in the stator circuit and blocks the start button. When the engine is overloaded, the heat relays KK1 and KK2 operate, which by their contacts disconnect the power supply circuit of the coil KM1. To stop the engine press SB2 button. To protect against short circuits, the QF1 circuit breaker with an electrodynamic release is used.

Conclusion

As a result of the work carried out, the need for obtaining fine chalk was considered and the technological scheme for its production was chosen. The device and principle of operation of the roller medium-flow mill are considered in detail, its technical characteristics are given and the main parameters are calculated. In addition, the main parameters of the mill separator were calculated.

In the electrical part of the work, an adjustable electric drive of the mill separator was developed, the motor parameters were calculated using a T-shaped substitution scheme, and time constants were found that are necessary to adjust the parameters of the thyristor converter. The thyristor frequency converter was analyzed and selected, the principle of its operation with the description of the block diagram of the converter was considered. A power circuit was also developed and switching and protective equipment was chosen.

Also in this work, the issues of safety and labor protection are considered, the working conditions of the maintenance personnel and the state of the microclimate of the production room are analyzed. Measures excluding injuries during operation on a roller mill are considered. Special attention is paid to electrical safety, and the protective grounding of the separator motor was also calculated.

In the economic part of the work, the economic efficiency of the project for the modernization of the rolls of the medium-speed mill was calculated. Based on the results of the calculation, the project is effective, and the payback period for capital costs is 0.21 years.