Power supply to cement plant

Contents

1 Introduction

1.1 General provisions

1.2 Characteristics of the enterprise and its electric receivers

1.3 Initial data

2 Main part

2.1 Determination of electrical loads of the enterprise

2.2 Determining the center of electrical loads

2.3 Selection of rational network voltages

2.4 Selection of location, number and power of transformers

Workshop TPs

2.5 Calculation of compensating devices power

2.6 Selection of power supply scheme of the enterprise

2.7 Calculation and power selection of GPP transformers

2.8 Calculation of short circuit currents on the HV side

2.9 Selection and check of equipment on the GPP

2.9.1 HV side equipment selection

2.9.2 Selection of LV switchgears and switches

2.9.3 Selection of LV side voltage transformers

2.9.4 Selection of current transformers on LV side

2.9.5 Selection of fuses on LV side

2.9.6 Selection of auxiliary transformers

2.9.7 Selection of TP shop disconnectors

2.9.8 Calculation and selection of wire and cable sections

2.10 Calculation of cable line relay protection from GPP to TP

2.11 Calculation of 0.4 kV power system

2.11.1 Selection of package busbars

2.11.2 Selection of distribution cabinets

2.11.3 Calculation and selection of wire and cable sections

2.11.4 Selection of protection devices

2.12 Calculation of three-phase short circuit at lower voltage

2.13 Feasibility Study for the Implementation of the ASCUE System

2.14 Selection of accounting system. Definition of measured parameters, methods

transmission of information

3 Special part

4 Occupational health and safety

4.1 Calculation of the workshop lighting unit

4.2 Calculation of grounding device for TC substation

4.3 Calculation of lightning protection of GPP

4.4 Selection of circuit neutral mode

4.5 Electromagnetic Field Protection Measures

4.5.1 Influence of electric and magnetic fields of industrial frequency

on human health

4.5.2 Substation overvoltage protection

4.6 Safety measures during works on equipment

4.6.1 Personnel requirements

4.6.2 Technical measures ensuring safety of operation

with voltage relief

5 Organizational and economic part

5.1 Determination of Purchase Energy Costs

5.2 Organization of repairs

5.3 Determination of operational and repair personnel

5.4 Personnel Payroll Organization, Payroll Cost Calculation

5.5 Determination of Material and Spare Parts Requirements

5.6 Determination of cost of 1 kWh consumed by the enterprise

electric power

Conclusion

List of used literature

1 introduction

1.1 General provisions

The acceleration of scientific and technological progress dictates the need to improve industrial energy: the creation of economical, reliable power supply systems for industrial enterprises, lighting, automated control systems for electric drives and technological processes; introduction of microprocessor technology, gas-insulated or vacuum electric equipment, new complete converter devices.

The first largest amount of electricity consumed belongs to industry, which accounts for 60% of all electricity generated in the country. With the help of electric energy, millions of machines and mechanisms are driven, rooms are illuminated, and production processes are automatically controlled. Now there are technologies (electrophysical and electrochemical methods of processing metals and products), where electricity is the only energy carrier.

Power supply systems of enterprises consisting of networks up to and above 1000 V voltage and transformer converter and distribution substations are used to ensure the supply of electricity in the required quantity and of appropriate quality from power systems to industrial facilities, plants and mechanisms. Therefore, at the design stage, much attention is paid to the creation of economically viable power supply schemes, their reliability, and ensuring the quality of electricity.

At the same time, the issue of rational use of fuel and energy resources, their saving, combating power losses as a result of accidents, unsatisfactory operation and repair of equipment and equipment, the use of unacceptably large amounts of transformations, the use of unsustainable voltages, the number and power of transformers remains urgent. Occupational safety and personnel safety measures are also an important issue.

All these issues will be presented for consideration in this diploma project, the specific purpose of which is to develop a power supply scheme for the cement plant.

1.2 Characteristics of the enterprise and its electric receivers

Cement production is a complex and energy-intensive process.

The raw material is a natural mixture of limestone and clay, extracted by an open method. Upon arrival at the plant, the raw materials go through two stages of crushing. In the primary crushing shop, it is ground into pieces of 200300 mm, and then goes to the secondary crushing shop, where further crushing is carried out to dimensions of 2530 mm. The resulting product enters the limestone warehouse. Raw materials are fed through belt conveyors to a raw material workshop, where raw materials mills with a capacity of 7080 tons per hour are installed, in which limestone is milled to flour.

Cement base is clinker produced by roasting raw flour in rotary furnaces. Under the influence of high temperature (t = 14501550 0C), the raw material mass undergoes a number of chemical and physical transformations. After firing, the clinker enters the refrigerator, in which it is cooled to t = 80120 0C and sent via belt conveyors to a warehouse, where various additives are also stored, by the addition of which various grades of cement can be obtained. In the warehouse, the clinker must be kept for 15 days in order for the supply of free lime to occur, which must be no more than 0.5-0.7%. then the clinker is fed to a grinding shop in which cement mills are installed. Besides clinker, milled gypsum is fed into mill in amount of 5%. The resulting dust-air mixture from cement mills enters electrofilters in which fine cement dust is collected and deposited. The voltage on the electrodes is 75,000 V. The resulting cement is supplied by pneumovant pumps from precipitators to cement warehouses, where it is stored before packaging and goes through a further cooling stage.

The cement plant is a highly mechanized and automated enterprise. By the nature of the loads, the plant as a whole belongs to consumers of 2 categories. The number of hours of using the maximum load is 7400 hours, the plant operates in shift 3.

The environment in the workshops is normal, with the exception of chemical water treatment and pumping station (wet), grinding shop, cement warehouses (dust).

The main electric receivers are synchronous motors with a voltage of 10 kV in the amount of 12 pieces and receivers with a voltage of 0.4 kV of the firing shop. Their total capacity is 85% of the capacity of the entire plant.

3 special part

Occupational diseases in the enterprise

Construction materials industry enterprises are located in all regions of the Russian Federation. The Novosibirsk region and Altai Territory as a whole are ranked among the areas with the most atmospheric air pollution by the production of building materials.

Around the cement plants, zones have developed with an increased content of dust in the air, including cement dust, benzapyrin and other harmful substances.

Emissions of pollutants from the construction materials industry mainly contain dust and suspended substances (54%), as well as carbon monoxide (23.3%), sulfur dioxide, nitrogen oxide, hydrogen sulfide, formaldehyde, toluene, xylene and other substances. The largest share of emissions comes from enterprises producing cement - 273 thousand tons or 40.5%.

Volley emissions from blasting and open-pit extraction of natural raw materials make a significant contribution to air pollution.

The main pollutant of cement production plants is dust containing silicon oxides, calcium, manganese, iron, arsenic, mercury, lead, fluorine and fluoride compounds.

Production dust is a very common hazardous and harmful production factor. Dust is encountered by workers in mining, engineering, metallurgy, building materials, textiles, agriculture, etc.

Dust can have a fibrogenic irritating and toxic effect on the human body. dust of certain substances and materials (fiberglass, mica, etc.) has an irritating effect on the upper respiratory tract, mucous membrane of the eyes, skin.

Dust of toxic substances (lead, chromium, beryllium, etc.), entering the lungs into the human body, have a toxic effect characteristic of them depending on their physical, chemical and physicochemical properties.

Fibrogenic is the effect of dust in which connective tissue grows in the lungs, disrupting the normal structure and functions of the body.

The damaging effect of dust is largely determined by its dispersion (dust particle size). The most fibrogenic activity has disintegration aerosols with a particle size of up to 5 μm and most of all particles with a size of 1... 2 μm, as well as condensation aerosols with particles less than 0.3... 0.4 μm, most deeply penetrating and trapped in the lungs.

The degree of danger of dust also depends on the shape of the particles, their hardness, fibre resistance, electric charging, specific surface area, etc.

The harmful nature of production dust is due to its ability to cause occupational lung diseases, primarily pneumoconiosis. the most common and severe form of pneumoconiosis is silicosis (pulmonary dust fibrosis), which develops as a result of inhalation of dust, containing free silicon dioxide. Silicatoses occur when exposed to dust silicates, where the silica is in a bonded state. these diseases include asbestosis, talcosis, cementosis, kaolinosis, etc. There are other types of pneumoconioses (metalloconiosis, cotton, grain pneumoconiosis, etc.). Production dust, having an irritating effect, can cause professional dust bronchitis, pneumonia, asthmatic rhinitis, bronchial asthma, and reduce the protective properties of the body. Under the influence of dust, conjunctivites, skin lesions develop. Metal aerosols, dust of toxic chemicals can lead to chronic and acute poisonings characteristic of this toxic substance. The effect of dust exacerbates heavy physical labor, unfavorable meteorological conditions, some gases. The decisive effect on the degree of damage to the human body by harmful chemicals (and dust) is their concentration in the air of the working zone and the duration of exposure.

It should be borne in mind that in production conditions, workers are usually exposed to several harmful substances at the same time. At the same time, potentiation (disproportionate enhancement of the harmful effect), summation, "antagonism" (reduction of the harmful effect) and "independent" action of poisons are possible.

Other harmful and hazardous production factors also affect the toxic effects of harmful substances. For example, increased temperature and humidity, as well as strong muscle tension, in most cases increase the body's sensitivity to the toxic effect of a harmful substance.

Individual characteristics of a person are of some importance. It is known, for example, that when working in the same conditions, some people get pneumoconiosis relatively quickly, and others work in 2... 3 times longer without any changes in their health.

Measures to combat production dust are diverse: rationalization of the production process, its mechanization and automation, organization of general and local ventilation, sealing of equipment, replacement of dry methods of operation with wet ones, etc. Personal protective equipment is anti-air sprayers.

A common and constantly increasing negative factor of the urban environment is electromagnetic fields (EMF) created by various devices that generate, transmit, execute electricity. Electromagnetic pollution in populated areas has become so significant that the World Health Organization has included this problem among the most urgent for humans.

Currently, there are a huge number of a wide variety of EMF sources: power lines, satellite communication stations, radio relay installations, television transmission centers, switchgears, electric transport, computers, mobile phones, microwave ovens, air conditioners.

The human body in EMI partially absorbs its energy, which turns into thermal, raising the temperature of the body or individual organs, tissues, cells. The biological effect of EMF depends on the wavelength, intensity and mode of radiation, the duration and nature of radiation of the body, the area of ​ ​ the irradiated surface, the anatomical structure of the organ or tissue. The higher the field power. shorter wavelength, longer irradiation time, the stronger the negative effect of EMF on the body. The consequences of the effects of EMF on humans are violation of electrophysiological processes in the central, nervous and cardiovascular systems, thyroid functions, generative function of the body, eye damage - cataract, change in the composition of peripheral blood.

Sources of electric fields are power lines, switchgears. With prolonged chronic exposure to EP, subjective disorders are noted in the form of complaints of a neurotic nature (feeling of severity and headache, memory deterioration, increased fatigue, irritability, heart pain, sleep disorder, apathy, depression with increased sensitivity to bright light, sharp sounds and other irritants).

The most sensitive to electrostatic fields are the nervous, cardiovascular, neurogumoral systems of the body.

Widely used in various fields of science, technology, communications, industry. agriculture, medicine, laser biology. A laser or optical quantum generator is an electromagnetic radiation generator of the optical range based on the use of forced radiation.

Laser radiation adversely affects the organs of vision. The use of high-power lasers poses a risk of damage to the skin and even internal organs. Under the influence of laser rays, changes occur in the central nervous, cardiovascular, endocrine systems, leading to impaired health.

Ultraviolet radiation is an eye-invisible EMI. The biological effect of ultraviolet rays of sunlight is manifested in their positive effect on the human body. The consequence of lack of light is avitaminosis D, weakening of the body's protective immunobiological reactions, exacerbation of chronic diseases, functional disorder of the nervous system.

Under the influence of ultraviolet radiation, blood pressure is normalized, cholesterol is reduced, all types of metabolism are normalized, body resistance is increased, fatigue is reduced, etc.

Ultraviolet radiation from production sources (electrodusks, autogenous flames, mercury-quartz torches) can cause acute and chronic lesions.

The visual analyzer is most susceptible to ultraviolet radiation: acute eye lesions - electro-ophthalmias, which are acute conjunctivitis, erythema of the skin of the face and eyelids is often found, swelling until blisters appear.

Along with the local reaction, general toxic ones are observed: rising temperatures, chills, headache.

Chronic changes in the skin cover cause ultraviolet radiation, expressed in the development of keratosis, malignancies.

EMF intensity of radio frequencies is regulated by GOST 12.1.00684 "EMF of radio frequencies. Additional workplace levels and control requirements. "

Means and methods of EMF protection are divided into:

1) organizational - prevent people from entering zones with high EMF intensity, creating sanitary protection zones around antenna structures;

2) engineering and technical - electrogermatization of circuit elements, units, installation units in order to reduce or eliminate EMF, execution of reflecting and absorbing screens, special clothes made of metallized fabric, glasses;

3) curative and prophylactic.

Additional levels of EP intensity are established by GOST 12.1.00284 "EP of industrial frequency. Additional levels of tension and requirements for field monitoring "

Security features include:

1) stationary shielded devices (visors, canopies, partitions);

2) portable shielded means (shields, umbrellas, screens, etc.);

3) individual protective equipment: protective suits, shielded headgear.

Additional levels of ESP are established by GOST 12.1.04584 "ESP. Additional levels of tension and requirements for field monitoring "

One of the common means of protection is the grounding of mechanical and electrically conductive elements of equipment, the installation of static electricity neutralizers, an increase in air humidity, the use of anti-static robes, shoes, bracelets for protecting hands, etc.

The maximum permissible levels of laser radiation are regulated by "SniP of the device and operation of lasers" No. 580491.

To prevent laser irradiation, it is necessary to either guard the laser zone, or shield the beam, place the lasers in separate rooms and remotely control their operation.

Individual means of protection include special glasses, shields, masks, ensuring the reduction of radiation to the level of PDU.

The intensity of ultraviolet radiation at industrial enterprises is established by the "Sanitary norms of ultraviolet radiation in the premises" No. 455788.

Protective measures include ultraviolet radiation reflectors, protective screens and personal protective equipment for the skin and eyes.

The extent of electromagnetic pollution of the environment has become so significant that some experts consider EMF to be a potent environmental factor with catastrophic consequences for all living things.

The result of prolonged exposure to EMF, even relatively low levels, may be cancers. behavioral changes, memory loss, Parkinson's and Alzheimer's disease, sexual depression, and many others. Especially important is the exposure to EMF for the body developing in the womb and children, as well as people exposed to allergic diseases.

Thus, all of the above requires reliable protection of people from the adverse effects of electromagnetic radiation.

Conclusion

When calculating the power supply of the cement plant, all factors affecting the calculations of the power supply of the enterprise were taken into account.

Thus, the choice of the location of the GPP was made taking into account the mapping of loads of consumers, and the choice of the diagram of electrical connections of the GPP was made on the basis of a technical and economic comparison of the two options. The number and capacity of transformers was determined by the reliability category and the design capacity of the enterprise. The design of the factory power supply was influenced by the presence of synchronous motors, so a two-stage radial circuit using an intermediate distribution point was chosen.

Also, due to synchronous engines, reactive power compensation was not required. Selection of cable line sections is performed by current economic density, checked in emergency mode and specified by calculation for thermal resistance to short-circuit currents.

The choice of the design of the workshop network of the repair and mechanical workshop, the selection of cables, wires, busbars, cabinets was made taking into account their geographical position in the workshop, the design load of electric consumers and the environment in German.

Health and safety issues were considered, lightning protection calculations of the GPP and grounding calculations for TP No. 2 were made.

The diploma project was developed taking into account the requirements of reliability of power supply, economy, maximum reduction of power losses.