HEAT AND GAS SUPPLY

AND VENTILATION

Novosibirsk 2008

FEDERAL EDUCATION AGENCY OF THE RUSSIAN FEDERATION

NOVOSIBIRSK STATE

ARCHITECTURAL AND CONSTRUCTION UNIVERSITY (SIBSTRIN)

ON THE. Popov

SYSTEMS AUTOMATION

HEAT AND GAS SUPPLY

AND VENTILATION

Tutorial

Novosibirsk 2008

ON THE. Popov

Automation of heat and gas supply and ventilation systems

Tutorial. – Novosibirsk: NGASU (Sibstrin), 2008.

The training manual examines the principles of developing automation schemes and existing engineering solutions for the automation of specific heat and gas supply and heat consumption systems, boiler plants, ventilation systems and microclimate air conditioning systems.

The manual is intended for students studying in specialty 270109 in the direction of “Construction”.

Reviewers:

- IN AND. Kostin, Doctor of Technical Sciences, Professor of the Department

heat and gas supply and ventilation

NGASU (Sibstrin)

– D.V. Zedgenizov, Ph.D., senior researcher laboratories

mine aerodynamics IGD SB RAS

© Popov N.A. 2008

Bibliography…………………………………………….
MJ VSh-1986, 304 p.
The physical foundations of production process control, the theoretical foundations of control and regulation, automation technology and equipment, automation schemes for various TGV systems, technical and economic data and automation prospects are considered.
Table of contents of the book Automation and automation of heat and gas supply and ventilation systems.
Preface.
Introduction.
Basics of automation of production processes.
General information.
The importance of automatic control of production processes.
Conditions, aspects and stages of automation.
Features of automation of Tgv systems.
Basic concepts and definitions.
Characteristics of technological processes.
Basic definitions.
Classification of automation subsystems.
Fundamentals of the theory of management and regulation.
Physical foundations of control and structure of systems.
The concept of managing simple processes (objects).
The essence of the management process.
The concept of feedback.
Automatic regulator and structure of the automatic regulation system.
Two control methods.
Basic principles of management.
Control object and its properties.
Accumulating capacity of the object.
Self-regulation. The influence of internal feedback.
Lag.
Static characteristics of the object.
Dynamic mode of the object.
Mathematical models of the simplest objects.
Manageability of objects.
Typical research methods for Asr and Asu.
The concept of a link in an automatic system.
Basic typical dynamic links.
Operational method in automation.
Structural diagrams. Connection of links.
Transfer functions of typical objects.
Equipment and automation equipment.
Measurement and control of technological process parameters.
Classification of measured quantities.
Principles and methods of measurement (control).
Accuracy and errors of measurements.
Classification of measuring equipment and sensors.
Sensor characteristics.
State system of industrial devices and automation equipment.
Means for measuring basic parameters in Tgv systems.
Temperature sensors.
Gas (air) humidity sensors.
Pressure (vacuum) sensors.
Flow sensors.
Measuring the amount of heat.
Level sensors between two media.
Determination of the chemical composition of substances.
Other measurements.
Basic circuits for connecting electrical sensors of non-electrical quantities.
Adding devices.
Signal transmission methods.
Amplifier-converter devices.
Hydraulic boosters.
Pneumatic amplifiers.
Electrical amplifiers. Relay.
Electronic amplifiers.
Multistage amplification.
Executive devices.
Hydraulic and pneumatic actuators.
Electrical actuators.
Master devices.
Classification of regulators according to the nature of the setting influence.
Main types of master devices.
Acr and microcomputers.
Regulatory authorities.
Characteristics of distribution bodies.
Main types of distribution bodies.
Regulating devices.
Static calculations of regulator elements.
Automatic regulators.
Classification of automatic regulators.
Basic properties of regulators.
Continuous and intermittent regulators.
Automatic control systems.
Regulation statics.
Dynamics of regulation.
Transient processes in Asr.
Stability of regulation.
Stability criteria.
Quality of regulation.
Basic laws (algorithms) of regulation.
Related regulation.
Comparative characteristics and choice of regulator.
Controller settings.
Reliability Asr.
Automation in heat and gas supply and ventilation systems.
Design of automation schemes, installation and operation of automation devices.
Basics of designing automation circuits.
Installation, adjustment and operation of automation equipment.
Automatic remote control of electric motors.
Principles of relay contactor control.
Control of an asynchronous electric motor with a squirrel-cage rotor.
Control of an electric motor with a wound rotor.
Reversing and controlling backup electric motors.
Remote control circuit equipment.
Automation of heat supply systems.
Basic principles of automation.
Automation of district thermal stations.
Automation of pumping units.
Automation of recharge of heating networks.
Automation of condensate and drainage devices.
Automatic protection of the heating network against pressure increase.
Automation of group heating points.
Automation of heat consumption systems.
Automation of hot water supply systems.
Principles of thermal management of buildings.
Automation of heat supply at local heating points.
Individual regulation of the thermal regime of heated premises.
Pressure regulation in heating systems.
Automation of low-power boiler houses.
Basic principles of boiler room automation.
Automation of steam generators.
Technological protection of boilers.
Automation of hot water boilers.
Automation of gas fuel boilers.
Automation of fuel-burning devices of micro-boilers.
Automation of water treatment systems.
Automation of fuel preparation devices.
Automation of ventilation systems.
Automation of exhaust ventilation systems.
Automation of aspiration and pneumatic transport systems.
Automation of aeration devices.
Methods for regulating air temperature.
Automation of supply ventilation systems.
Automation of air curtains.
Automation of air heating.
Automation of artificial climate installations.
Thermodynamic fundamentals of automation Well.
Principles and methods of regulating humidity in Wells.
Automation of central wells.
Automation of refrigeration units.
Automation of autonomous air conditioners.
Automation of gas supply systems for gas consumption.
Automatic regulation of gas pressure and flow.
Automation of gas-using installations.
Automatic protection of underground pipelines from electrochemical corrosion.
Automation when working with liquid gases.
Telemechanics and dispatching.
Basic concepts.
Construction of telemechanics circuits.
Telemechanics and dispatching in Tgv systems.
Prospects for the development of automation of Tgv systems.
Technical and economic assessment of automation.
New directions for automation of Tgv systems.
application.
Literature.
Subject index.

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Textbook for universities/A. A. Kalmakov, Yu. Ya. Kuvshinov, S. S. Romanova, S. A, Shchelkunov; Ed. V. N. Bogoslovsky. - M.: Stroyizdat, 1986 - 479 p.: ill.

The theoretical, engineering and methodological foundations of the dynamics of heat and gas supply and microclimate conditioning systems (HGS and SCM) as automation objects are outlined. Given the os...

• 3.73 MB
• added 06/04/2011

Textbook for universities/A. A. Kalmakov, Yu. Ya-Kuvshinov, S. S. Romanova, S. A. Shchelkunov; Ed. V. N. Bogoslovsky. - M.: Stroyizdat, 1986. - 479 p.: ill.

The theoretical, engineering and methodological foundations of the dynamics of heat and gas supply and microclimate conditioning systems (HGS and SCM) as automation objects are outlined. Given the basic...

• 1.99 MB
• added 02/14/2011

Textbook manual for universities. - L., Stroyizdat, Leningrad. department, 1976. - 216 p.

The textbook outlines the basic concepts from the theory of automatic control and outlines an engineering approach to the selection of types of regulators, provides a description of the elements of the regulators, examines the advantages and disadvantages of the applied circuits...

• 1.58 MB
• added 12/02/2008

Khabarovsk, 2005
Album No. 1 of typical design solutions
"Automation of heating systems and
hot water supply"

Album No. 2 of typical design solutions

Methodological materials for use
in the educational process and in diploma design.

• 7.79 MB
• added 04/25/2009

Tutorial. K.: Outpost-Prim, 2005. - 560 p.

The textbook is a presentation of the course “Special technology” for training adjusters of devices, equipment and automatic control, regulation and control systems in the field of ventilation and air conditioning.
The book describes the basic principles of the theory of autom...

• 1.22 MB
• added 12/13/2009

Methodological materials for use. No author.
in the educational process and in diploma design for students of specialty 290700 “Heat and Gas Supply and Ventilation” of all forms of education.
Khabarovsk 2004. Without author.

Preface.
Ventilation system with supply air temperature control.
System...

Automation of heat and gas supply and ventilation systems

Section I. BASICS OF AUTOMATION OF PRODUCTION PROCESSES

Chapter 1. General information

1. The importance of automatic control of production processes
2. Conditions, aspects and stages of automation
3. Features of automation of DVT systems

Chapter 2. Basic concepts and definitions

1. Characteristics of technological processes
2. Basic definitions
3. Classification of automation subsystems

Section II. FUNDAMENTALS OF CONTROL AND REGULATION THEORY

Chapter 3. Physical foundations of control and structure of systems.

1. The concept of managing simple processes (objects)
2. The essence of the management process
3. The concept of feedback
4. Automatic regulator and structure of automatic regulation system
5. Two control methods

1. basic principles of management

Chapter 4. Control object and its properties

1. Accumulating capacity of the object
2. Self-regulation. Impact of Internal Feedback
3. Lag
4. Static characteristics of the object
5. Dynamic object mode
6. Mathematical models of the simplest objects
7. Manageability of objects

Chapter 5. Typical methods for studying ASR and ACS

1. The concept of a link in an automatic system
2. Basic typical dynamic links
3. Operational method in automation
4. Symbolic representation of the equations of dynamics
5. Structural diagrams. Connection of links
6. Transfer functions of typical objects

Section III. EQUIPMENT AND AUTOMATION MEANS

Chapter 6. Measurement and control of technological process parameters

1. Classification of measured quantities
2. Principles and methods of measurement (control)
3. Accuracy and errors of measurements
4. Classification of measuring equipment and sensors
5. Sensor characteristics
6. State system of industrial instruments and automation equipment

Chapter 7. Means for measuring basic parameters in DVT systems

1. Temperature sensors
2. Gas (air) humidity sensors
3. Pressure (vacuum) sensors
4. Flow sensors
5. Heat measurement
6. Interface level sensors
7. Determination of the chemical composition of substances
8. Other measurements
9. Basic circuits for connecting electrical sensors of non-electrical quantities
10. Adding devices
11. Signal transmission methods

Chapter 8. Amplifier-converter devices

1. Hydraulic boosters
2. Pneumatic amplifiers
3. Electrical amplifiers. Relay
4. Electronic amplifiers
5. Multi-stage amplification

Chapter 9. Actuators

1. Hydraulic and pneumatic actuators
2. Electrical actuators

Chapter 10. Master devices

1. Classification of regulators according to the nature of the setting influence
2. Main types of master devices
3. ASR and microcomputers

Chapter 11. Regulatory Bodies

1. Characteristics of distribution bodies
2. Main types of distribution bodies
3. Regulating devices
4. Static calculations of regulator elements

Chapter 12. Automatic regulators

1. Classification of automatic regulators
2. Basic properties of regulators

Chapter 13. Automatic control systems

1. Regulation statics
2. Diwamics of regulation
3. Transient processes in ASR
4. Stability of regulation
5. Stability criteria
6. Quality of regulation
7. Basic laws (algorithms) of regulation
8. Related regulation
9. Comparative characteristics and choice of regulator
10. Controller settings
11. Reliability of ASR

Section IV. AUTOMATION IN HEAT AND GAS SUPPLY AND VENTILATION SYSTEMS

Chapter 14. Design of automation schemes, installation and operation of automation devices

1. Automation Circuit Design Basics
2. Installation, adjustment and operation of automation equipment

Chapter 15. Automatic remote control of electric motors

1. Principles of relay contactor control
2. Control of an asynchronous electric motor with a squirrel cage rotor
3. Control of an electric motor with a wound rotor
4. Reversing and controlling standby electric motors
5. Remote control circuit hardware

Chapter 16. Automation of heat supply systems

1. Basic principles of automation
2. Automation of district thermal stations
3. Automation of pumping units
4. Automation of recharge of heating networks
5. Automation of condensate and drainage devices
6. Automatic protection of the heating network against pressure increase
7. Automation of group heating points

Chapter 17. Automation of heat consumption systems

1. Automation of hot water supply systems
2. Principles of thermal management of buildings
3. Automation of heat supply at local heating points
4. Individual regulation of the thermal regime of heated rooms
5. Pressure regulation in heating systems

Chapter 18. Automation of low-power boiler houses

1. Basic principles of boiler room automation
2. Automation of steam generators
3. Technological protection of boilers
4. Automation of hot water boilers
5. Automation of gas fuel boilers
6. Automation of fuel-burning devices of microboilers
7. Automation of water treatment systems
8. Automation of fuel preparation devices

Chapter 19. Automation of ventilation systems

1. Automation of exhaust ventilation systems
2. Automation of aspiration and pneumatic transport systems
3. Automation of aeration devices
4. Air temperature control methods
5. Automation of supply ventilation systems
6. Automation of air curtains
7. Automation of air heating

Chapter 20. Automation of artificial climate installations

1. Thermodynamic fundamentals of SCR automation
2. Principles and methods of regulating humidity in SCR
3. Automation of central cash registers
4. Automation of refrigeration units
5. Automation of autonomous air conditioners

Chapter 21. Automation of gas supply and gas consumption systems

1. Automatic regulation of gas pressure and flow
2. Automation of gas-using plants
3. Automatic protection of underground pipelines from electrochemical corrosion
4. Automation when working with liquid gases

Chapter 22. Telemechanics and dispatching

1. Basic Concepts
2. Construction of telemechanics circuits
3. Telemechanics and dispatching in DVT systems

Chapter 23. Prospects for the development of automation of DVT systems

1. Technical and economic assessment of automation
2. New directions for automation of DVT systems

The widespread introduction of automation and automation equipment into various branches of technology has necessitated the study of the discipline “Automation of Production Processes” by students of almost all engineering and technical specialties of higher education.

The objective of studying the discipline is to become familiar with modern principles and methods of effective management of production processes and installations, as well as automatic means. The fundamentals of the theory of control and regulation, the principle of operation and design of automation equipment, and the basic fundamental solutions of the circuits are outlined. used in heat, gas supply and ventilation (DHV) systems to increase labor productivity and save fuel and energy resources.

Automation of the production process is the pinnacle of technical equipment in this industry. Therefore, along with mandatory special knowledge on automation objects, serious training is required in fundamental disciplines - special sections of mathematics, physics, theoretical mechanics, electrical engineering, etc. A feature of automation is the transition from traditional stationary modes and calculations to non-stationary, dynamic ones, characteristic of the field of use of automation tools.

The book examines modern domestic automatic systems, as well as some of the latest foreign developments.

Automation uses a large amount of graphic material in the form of various diagrams, so the key to successful mastery of the course is mandatory knowledge of the ABC of automation - standard symbols. When considering automation schemes, the author limited himself to only fundamental decisions, giving the reader the opportunity to expand his knowledge using reference and regulatory literature.

Based on materials from http://www.tgv.khstu.ru

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Introduction

1. Heat and gas supply and microclimate conditioning systems as automation objects

2. Centralized heat and gas supply systems

3. Mechanization and automation of production of heat and gas supply and ventilation systems

3.1 Automation of heat and gas supply systems and microclimate conditioning

3.2 Automation of ventilation and air conditioning systems

4. Technical automation equipment

4.1 Primary transducers (sensors)

5. Modern control schemes for air conditioning systems

Conclusion

List of sources used

Introduction

Relevance. For many years, work has been underway to create heat supply automation tools.

The energy program provides for a further increase in the level of centralization of heat supply through the construction of thermal power plants and regional, including autonomous heat centers.

Domestic and foreign experience in the development and operation of automated TGS and SCM systems shows that an indispensable condition for the development of automation is not only the improvement of technical means of automation, but also a comprehensive analysis of the operating modes and regulation of the TGS and SCM systems themselves.

In the development of technical and economic prerequisites for the introduction and use of automation of TGS and SCM and, accordingly, in the development of technical means of automation, three characteristic periods can be distinguished: the initial stage, the stage of complex automation and the stage of automated control systems.

In general, the initial stage was a stage of mechanization and automation of individual processes. The use of automation was not widespread, and the volume of technical means used was small, and their production was not an independent industry. But it was at this stage that some modern principles for constructing lower levels of automation and, in particular, the foundations of modern remote control using electric, pneumatic and hydraulic motors to drive shut-off and control valves were formed.

The transition to the second stage—comprehensive automation of production—occurred in conditions of increasing labor productivity, consolidation of unit capacities of units and installations, and the development of the material, scientific and technical base of automation. The third (modern) stage of automation development is characterized as the stage of automated control systems (ACS), the emergence of which coincided with the development and dissemination of computer technology. At this stage, it becomes advisable to automate increasingly complex control functions. The spread of modern automated control systems is largely determined by the state of information display technology. Cathode-ray indicators (displays) are becoming promising means of displaying information. The new technology for displaying information makes it possible to abandon bulky mimic diagrams and dramatically reduce the number of devices, signal boards and indicators on switchboards and control panels.

Due to the variety of required types of instruments and devices, it is advisable to appear within the framework of GSP complexes of a narrower profile, designed to perform individual engineering tasks. The complexes have wide functionality that allows you to create automated process control systems of a wide variety of complexity and structure, including in TGS and SCM systems.

The purpose of this work is to study the automation and mechanization of the production of heat and gas supply and ventilation systems.

To achieve this goal, the following tasks must be solved:

To study heat and gas supply and microclimate conditioning systems as automation objects, centralized heat and gas supply systems;

Research mechanization and automation of production of heat and gas supply and ventilation systems;

Consider technical means of automation;

Describe modern control schemes for air conditioning systems.

1. Heat and gas supply and microclimate conditioning systems as automation objects

The complex of engineering systems for heat and gas supply and microclimate conditioning is designed to generate thermal energy, transport hot water, steam and gas through heat and gas networks to buildings and use these energy carriers to maintain specified microclimate parameters in them, for production and economic needs. The block diagram of the heat and gas supply and microclimate conditioning system (HGS and CM) is presented in Figure 1.

Figure 1 - Block diagram of the heat and gas supply and microclimate conditioning system (TGS and CM)

1 - residential and public buildings; 2 - industrial buildings; 3 - combined heat and power plant (boiler room); GDS - gas distribution station; GRP - gas control point; TsTP - central heating point; CO - heating system; SGV - hot water supply system; SV - ventilation system; SUTV - exhaust air heat recovery system; SHS - refrigeration system; SCV - air conditioning system (comfort and technological).

The basic general scheme of TGS and KM can be divided into two parts: the first consists of external centralized heat supply and gas supply systems, the second, being an energy consumer, includes the building and internal engineering systems for providing microclimate, economic and production needs.

2. Centralized heat and gas supply systems

Reliable and economical supply of heat to all categories of consumers is achieved by managing the operation of centralized heat supply. The purpose of control is to provide consumers with the required coolant flow at a given temperature, i.e. ensuring the required hydraulic and warm conditions of the system. This is achieved by maintaining specified pressure values, temperature pressure differences t at different points of the system. Temperature changes in accordance with changes in heat consumption of buildings are carried out at a thermal power plant or in a boiler room. The coolant from the thermal power plant is transported through main heating networks to neighborhoods and then through distribution or apartment heating networks to buildings or a group of buildings. In large heating networks, especially in district ones, where there is a sharp fluctuation in the coolant pressure drop, the hydraulic regime is highly unstable. To ensure the normal hydraulic mode of heating networks, it is necessary for consumers to maintain such a pressure drop of the coolant, which in all cases must exceed the minimum value required for the normal operation of heat-consuming installations, heat exchangers, mixers, and pumps. In this case, the consumer will receive the required coolant flow at a given temperature.

Since it is impossible to provide the necessary hydraulic and thermal conditions for numerous heat consumers through centralized control at a thermal power plant or boiler house, intermediate stages of maintaining temperature and water pressure are used - central heating points (CHS). The coolant temperature after the central heating station is 70-150 0 C using mixing pumps or heating water heaters. At subscriber inputs, in the presence of central heating stations, without preparation of the coolant, a local mode of heat supply for heating is carried out in elevators or heat exchangers. In long-distance heating networks with unfavorable terrain, there is a need to construct pumping substations, which are usually an additional step in maintaining the required hydraulic regime of the heating network to the substations by maintaining pressure in front of the pump. For normal operation of the heat treatment plant, it is necessary to maintain a given level of condensate H in steam-water heaters and make-up water deaerators.

3. Mechanization and automation of production systemsheat and gas supply and ventilationAndlations

3.1 Automation of heat and gas supply systems and microclimate conditioning

In accordance with existing instructions and design practice, the design of an automatic process control system contains graphic (drawings and diagrams) and text parts:

The graphic part of the project includes:

1) functional diagram of process control, automatic regulation, control and signaling;

2) drawings of general views of switchboards and control panels;

3) basic electrical, pneumatic, hydraulic circuits of automatic control, regulation and signaling. In the process of detailed design, graphic materials are developed:

1) schematic diagrams of power supply to devices;

2) installation diagrams of switchboards, consoles and junction boxes;

3) diagrams of external electrical and pipe wiring;

4) drawings of the location of equipment, electrical and pipe wiring;

5) installation drawings of equipment, auxiliary devices, switchboards and control panels.

The initial data for the design are contained in the technical specifications for the development of an automatic process control system.

The main elements of the task are a list of automation objects - technological units and installations, as well as the functions performed by the control and regulation system, which ensures the automation of the management of these objects.

The task contains a number of data that define the general requirements and characteristics of the system, and also describe the control objects. This part of the task consists of three sections:

1) justification for the development;

2) operating conditions of the system;

3) description of the technological process.

The functional diagram of automatic monitoring and control is intended to display the main technical decisions taken when designing a process automation system. It is one of the main documents of the project and is included in its composition when developing technical documentation at all stages of design. In the process of developing a functional diagram, the structure of the created system and functional connections between the control object - the technological process and the hardware of the system - control devices and collection of information about the state of the technological process are formed (Fig. 2).

Figure 2. - Structure of zone placement of the functional diagram of automatic monitoring and control

When creating a functional diagram, determine:

1) an appropriate level of automation of the technological process;

2) principles of organizing control and management of the technological process;

3) technological equipment controlled automatically, remotely or in both modes according to the operator’s instructions;

4) list and meaning of controlled and adjustable parameters;

5) control methods, laws of regulation and management;

6) the scope of automatic protection and blocking of autonomous control circuits of technological units;

7) a set of technical automation equipment, the type of energy for transmitting information;

8) locations of equipment on technological equipment, on switchboards and control panels.

In addition, the diagram provides textual explanations reflecting the purpose and characteristics of technological units, the values ​​of controlled and adjustable parameters, blocking and alarm conditions. Functional diagram is the main document of the project.

3.2 Automation of ventilation and air conditioning systems

Modern requirements for automated ventilation (AV) and air conditioning (AAC) systems contain two contradictory conditions: the first is simplicity and reliability of operation, the second is high quality of operation.

The main principle in the technical organization of automatic control of SV and SCR is the functional design of the hierarchical structure of the protection, regulation and control tasks to be performed.

Any industrial SCR must be equipped with elements and devices for automatic start and stop, as well as emergency protection devices. This is the first level of VCS automation.

The second level of SCR automation is the level of stabilization of equipment operating modes.

The technical implementation of the third hierarchical level is currently being successfully developed and implemented in industry (SV and SCR).

Solving problems of the third level of the equation is associated with information processing and the formation of control actions by solving discrete logical functions or carrying out a series of specific calculations.

The three-level structure of the technical implementation of management and regulation of the operation of SCS makes it possible to organize the operation of systems depending on the specifics of the enterprise and its operating services. Regulation of air conditioning systems is based on the analysis of stationary and non-stationary thermal processes. The further task is to automate the adopted technological control scheme for SCR, which will automatically ensure the specified operating mode and regulation of individual elements and the system as a whole in an optimal mode.

Separate or combined maintenance of specified operating modes of SCRs is carried out by instruments and automation devices, forming both simple local control loops and complex multi-circuit automatic control systems (ACS). The quality of ACS operation is determined mainly by the compliance of the created microclimate parameters in the premises of a building or structure with their required values ​​and depends on the correct choice of both the technological scheme and its equipment, and the elements of the automatic control system of this scheme.

Regulation according to optimal mode

Recently, they have begun to use a method for regulating the air conditioning system according to the optimal mode (developed by A. Ya. Kreslin), which in many cases allows one to avoid reheating the air cooled in the irrigation chamber, as well as to use the heat of the recirculated air more rationally. At any given time, the air in the air conditioning unit undergoes heat and humidity treatment in such a sequence that the consumption of heat and cold is the least.

The method of regulating air conditioning systems according to the optimal mode is more energy efficient. However, it should be noted that the implementation of regulation using the method of optimal modes requires more complex automation, which hinders its practical application.

Method for quantitative control of air conditioning systems. The essence of the method is to regulate the heating and cooling capacity of air conditioning units by changing the flow rate of the processed air.

Air flow control is carried out by changing the fan performance by changing the rotor speed of the electric motor, using adjustable hydraulic or electric couplings (connecting the electric motor to the fan), and using guide vanes in front of the fans.

Regulation of air conditioning systems (see Fig. 3) is achieved using control loops. A thermostat sensitive element installed in the working area of ​​the room or in the exhaust duct senses temperature deviations. The thermostat controls the air heater of the second heating stage VP 2 most often by regulating the coolant supply by valve K.

The constant air humidity in the room is ensured by two dew point thermostats, the sensitive elements of which perceive deviations in the temperature of the air after the irrigation chamber or the water in its pan. The winter dew point thermostat controls sequentially valve K 2 of the air heater of the first heating stage VP 1 and air valves (dampers) K, K 4, K;. The summer dew point thermostat controls the supply of cold water from the refrigeration unit to the irrigation chamber using valve K 6.

To more accurately regulate air humidity, moisture regulators are used, the sensitive elements of which are installed indoors. Humidity regulators control valves K 2 -K 6 in the same sequence as dew point thermostats.

Figure 3. - Air conditioning system with first circulation, year-round operation:

a) scheme of SCR; b) air treatment processes in the I-d diagram; c) regulation schedules; PV - supply fan; BB - exhaust fan; N - pump.

automation control microclimate sensor

4. Technical automation equipment

As a result of control, it is necessary to establish whether the actual state (property) of the control object satisfies the specified technological requirements. Monitoring of system parameters is carried out using measuring instruments.

The essence of measurement is obtaining quantitative information about parameters by comparing the current value of a technological parameter with a certain value taken as a unit. The result of control is an idea of ​​the qualitative characteristics of the controlled objects.

The set of devices with the help of which automatic control operations are performed is called an automatic control system (ACS).

In modern ACS, measurement information from instruments often goes directly to automatic control devices.

Under these conditions, electrical measuring instruments are mainly used, which have the following advantages:

1) ease of changing sensitivity over a wide range of the measured value;

2) low inertia of electrical equipment or a wide frequency range, which makes it possible to measure both slowly and rapidly changing quantities in time;

3) the ability to measure at a distance, in inaccessible places, centralization and simultaneous measurement of numerous quantities that are different in nature;

4) the possibility of completing the measuring and automatic systems they serve from blocks of the same type of electrical equipment, which is of utmost importance for the creation of IMS (measuring information systems).

Method of measurement -- i.e. the set of individual measurement transformations necessary to perceive information about the size of the measured value and transform it into the form that is necessary for the recipient of the information can most clearly be depicted in the form of a functional diagram (Fig. 4).

Figure 4 - Functional diagram of the measurement method

A measuring device is most often structurally divided into three independent units: a sensor, a measuring device and an indicator (or recorder), which can be placed separately from each other and connected to each other by a cable or another communication line.

The sensor of a device for measuring a particular quantity is a constructive combination of several measuring transducers placed directly near the measurement object. Using remote transmission, the rest of the measuring equipment (measuring circuits, amplifier, power supplies, etc.), usually called a measuring device, is made in the form of an independent structural unit, which can be placed in more favorable conditions. Requirements for the last part of the measuring device, i.e. to its index (recorder) are determined by the ease of use of the information received.

In SAC, the sensor is called the primary device. It is connected by a communication line to a secondary device that combines a measuring device and an indicator. The same secondary device can be used to monitor several quantities (parameters). In a more general case, several primary converters - sensors - are connected to one secondary device.

Methods of measurement transformations are divided into two main, fundamentally different classes: the direct transformation method and the balancing transformation method.

The direct conversion method is characterized by the fact that all information conversions are carried out only in one, direct direction - from the input value X through a series of measuring transducers P 1, P 2 ... to the output value Y out: the method is characterized by relatively low accuracy (Fig. 5, A).

The balancing method uses two converter circuits: a direct conversion circuit P 1, P 2 ..., ... and a reverse conversion circuit consisting of a converter c.

Figure 5 - Balancing method

Secondary devices, in accordance with the measurement method used in them, are divided into direct conversion devices and balancing devices. Using the direct conversion method, a device was built to measure temperature using a thermocouple and a millivoltmeter - a logometer - a direct current magnetic-electric device with an electrical counteracting torque (Fig. 6, a, b).

Figure 6 - Temperature measurement circuit using a thermocouple and millivoltmeter (a) and ratiometer circuit (b)

The main advantage of the logometer is the independence of the device readings from the supply voltage E.

In TGS and SCM systems, balancing devices with bridge equilibrium and compensation measuring circuits are widely used.

A bridge with an automatic balancing process is used as a secondary device - an automatic bridge.

In TGS and SCM, automatic bridges are used to measure temperature, as well as substance flow, pressure, liquid level, humidity and many other non-electrical quantities.

Automatic potentiometers are also widely used as secondary devices. Automatic potentiometers are used to measure electrical and non-electrical quantities, which can be previously converted into voltage or direct current emf.

Automatic differential transformer devices are widely used as secondary devices in TGS and SCM systems. They are used to measure non-electrical quantities - pressure, level flow, pressure, etc. (modifications of efficiency, pressure build-up, pressure build-up).

According to their design and purpose, secondary devices are divided into two groups:

a) indicating, giving information about the instantaneous value of the measured parameter.

b) indicating and self-recording, carrying out instantaneous measurements and recording the value of the measured parameter on chart paper.

4.1 Primary transducers (sensors)

Based on the principle of operation, sensors used in electric SAS can be divided into two groups: parametric and generator.

In parametric sensors (thermal resistances, strain resistances, photoresistances, capacitive sensors), the controlled quantity is converted into an electrical circuit parameter: resistance, inductance, capacitance, mutual inductance.

In generator sensors, various types of energy are directly converted into electrical energy. Generator sensors include thermoelectric sensors (thermocouples), induction sensors based on the phenomenon of electromagnetic induction, piezoelectric, photoelectric, etc.

Based on the type of output value, sensors used in SAC can be divided into groups in which the controlled parameter is converted into the following values:

1) ohmic resistance;

2) capacity;

3) inductance;

4) the magnitude of direct current (voltage);

5) amplitude of alternating current (voltage), etc.

This classification allows you to select the most suitable measuring devices.

Based on the type of input quantities, sensors used in TGS and SCM systems are divided into the following main groups:

1) temperature and heat flow sensors;

2) sensors for humidity and enthalpy of moist air;

3) level sensors;

4) pressure sensors;

5) flow sensors;

6) sensors for analyzing the composition of the substance.

Sensors are one of the most important functional elements of any control system. Their properties and characteristics often largely determine the operation of the SAC as a whole.

5. Modern control schemes for air conditioning systems

Cascade control of SCR. Increasing the accuracy of stabilization of microclimate parameters can be achieved by synthesizing stabilization with correction for deviations from the specified temperature and relative humidity in the room. This is ensured by the transition from single-circuit to double-circuit cascade stabilization systems. Cascade stabilization systems, in essence, should be the main systems for regulating air temperature and humidity.

Figure 7. - Functional diagram of the cascade control system for SCR

This regulator maintains at a given level a certain auxiliary value of the intermediate point of the controlled object. Since the inertia of the controlled section of the first control loop is insignificant, relatively high speed can be achieved in this loop. The first circuit is called stabilizing, the second - corrective. A functional diagram of a continuous cascade stabilization system for direct-flow SCR is shown in Fig. 7. Stabilization of air parameters is carried out using two-stage systems.

Conclusion

At the end of the work done, the following conclusions can be drawn. Automation of production - as well as ventilation systems - is the use of a set of tools that allow production processes to be carried out without the direct participation of a person, but under his control. Automation of production processes leads to increased output, reduced costs and improved product quality.

A central heating system (CHS) is a complex of a heat generator (CHP or boiler house) and heating networks (heating, ventilation, air conditioning and hot water supply systems).

In long-distance heating networks with unfavorable terrain, there is a need to construct pumping substations, which are usually an additional step in maintaining the required hydraulic regime of the heating network to the substations by maintaining pressure in front of the pump. In accordance with existing instructions and design practice, the design of an automatic process control system contains graphic (drawings and diagrams) and text parts.

For the quality management of any technological process, it is necessary to control several characteristic quantities, called process parameters.

In heat and gas supply and microclimate conditioning systems, the main parameters are temperature, heat flows (general, radiation, etc.), humidity, pressure, flow, liquid level and some others.

The operation of cascade systems is based on regulation not by one, but by two regulators, and the regulator that controls the deviation of the main controlled variable from the set value acts not on the object’s regulator, but on the sensor of the auxiliary regulator.

The ultimate goal of technological process automation is the development and implementation of automated process control systems in production, which allows maintaining a given technological regime. To build a modern industrial automation system, the technological process must be equipped with technical means.

Bibliography

1. Bondar E.S. and others. Automation of ventilation and air conditioning systems // K.: “Avanpost-Prim”, - 2014.

2. Gordienko A.S., Sidelnik A.B., Tsibulnik A.A., Microprocessor controllers for ventilation and air conditioning systems // S.O.K.-2014, No. 4-5.

3. SNiP 3.05.07-85 Automation systems.

4. SNiP 2.04.05-91 Heating, ventilation and air conditioning.

5. Solodovnikov V.V. et al., Fundamentals of theory and elements of automatic control systems. Textbook for universities. - M.: Mechanical Engineering, 2012.

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Automation of heat and gas supply and ventilation processes

1. Microclimate systems as automation objects

Maintaining the specified microclimate parameters in buildings and structures is ensured by a complex of engineering systems for heat and gas supply and microclimate conditioning. This complex produces thermal energy, transports hot water, steam and gas through heat and gas networks to buildings and uses these energy resources for production and economic needs, as well as to maintain the specified microclimate parameters in them.

The heat and gas supply and microclimate conditioning system includes external centralized heat supply and gas supply systems, as well as internal (located inside the building) engineering systems for providing microclimate, economic and production needs.

The centralized heat supply system includes heat generators (CHP, boiler houses) and heating networks through which heat is supplied to consumers (heating, ventilation, air conditioning and hot water supply systems).

The centralized gas supply system includes high, medium and low pressure gas networks, gas distribution stations (GDS), gas control points (GRP) and installations (GRU). It is designed to supply gas to heat-generating installations, as well as residential, public and industrial buildings.

The microclimate conditioning system (MCS) is a set of means that serve to maintain the specified microclimate parameters in the premises of buildings. SCM includes heating (HS), ventilation (SV), air conditioning (AAC) systems.

The heat and gas supply mode is different for different consumers. Thus, heat consumption for heating depends mainly on the parameters of the external climate, and heat consumption for hot water supply is determined by water consumption, which varies throughout the day and by day of the week. Heat consumption for ventilation and air conditioning depends both on the operating mode of consumers and on the parameters of the outside air. Gas consumption varies by month of the year, day of the week and hour of day.

Reliable and economical supply of heat and gas to various categories of consumers is achieved by using several stages of control and regulation. Centralized control of heat supply is carried out at a thermal power plant or in a boiler house. However, it cannot provide the necessary hydraulic and thermal conditions for numerous heat consumers. Therefore, intermediate stages are used to maintain the temperature and pressure of the coolant at central heating points (CHS).

The operation of gas supply systems is controlled by maintaining constant pressure in individual parts of the network, regardless of gas consumption. The required pressure in the network is ensured by gas reduction in the gas distribution system, hydraulic fracturing unit, and gas distribution unit. In addition, the GDS and GRP have devices to shut off the gas supply in the event of an unacceptable increase or decrease in pressure in the network.

Heating, ventilation and air conditioning systems carry out regulatory influences on the microclimate in order to bring its internal parameters into compliance with standardized values. Maintaining the internal air temperature within specified limits during the heating period is ensured by the heating system and is achieved by changing the amount of heat transferred into the room by heating devices. Ventilation systems are designed to maintain acceptable values ​​of microclimate parameters in a room based on comfortable or technological requirements for indoor air parameters. Regulation of the operation of ventilation systems is carried out by changing the flow rates of supply and exhaust air. Air conditioning systems ensure the maintenance of optimal microclimate parameters in the room based on comfort or technological requirements.

Hot water supply systems (HSS) provide consumers with hot water for domestic and economic needs. The task of controlling the water supply system is to maintain the consumer's specified water temperature during its variable consumption.

2. Automated system link

Any automatic control and regulation system consists of individual elements that perform independent functions. Thus, the elements of an automated system can be divided according to their functional purpose.

In each element, the transformation of any physical quantities characterizing the flow of the regulation process is carried out. The smallest number of such quantities for an element is two. One of these quantities is the input, and the other is the output. The transformation of one quantity into another that occurs in most elements has only one direction. For example, in a centrifugal governor, changing the shaft speed causes the clutch to move, but moving the clutch by an external force will not cause a change in the shaft speed. Such elements of the system, which have one degree of freedom, are called elementary dynamic links.

The control object can be considered as one of the links. A diagram that reflects the composition of the links and the nature of the connection between them is called a structural diagram.

The relationship between the output and input quantities of an elementary dynamic link under conditions of its equilibrium is called a static characteristic. The dynamic (in time) transformation of quantities in a link is determined by the corresponding equation (usually differential), as well as by the set of dynamic characteristics of the link.

The links that are part of a particular automatic control and regulation system may have different principles of operation, different designs, etc. The classification of links is based on the nature of the relationship between input and output quantities in the transient process, which is determined by the order of the differential equation describing the dynamic transformation of the signal in the link. With this classification, the entire constructive variety of links is reduced to a small number of their main types. Let's look at the main types of links.

The amplifying (inertia-free, ideal, proportional, capacitive) link is characterized by instantaneous signal transmission from input to output. In this case, the output value does not change over time, and the dynamic equation coincides with the static characteristic and has the form

Here x, y are the input and output quantities, respectively; k - transmission coefficient.

Examples of reinforcing links include a lever, a mechanical transmission, a potentiometer, and a transformer.

The lagging link is characterized by the fact that the output value repeats the input value, but with a delay Lt.

y(t) = x(t-Am).

Here t is the current time.

An example of a lagging link is a transport device or pipeline.

The aperiodic (inertial, static, capacitive, relaxation) link converts the input quantity in accordance with the equation

Here G is a constant coefficient characterizing the inertia of the link.

Examples: room, air heater, gas tank, thermocouple, etc.

The oscillatory (two-capacitor) link converts the input signal into an oscillatory signal. The dynamic equation of the oscillatory link has the form:

Here Ti, Tg are constant coefficients.

Examples: float differential pressure gauge, diaphragm pneumatic valve, etc.

The integrating (astatic, neutral) link converts the input signal in accordance with the equation

An example of an integrating link is an electrical circuit with inductance or capacitance.

The differentiating (pulse) link generates a signal at the output that is proportional to the rate of change of the input value. The dynamic equation of the link has the form:

Examples: tachometer, damper in mechanical transmissions. The generalized equation of any link, control object or automated system as a whole can be represented as:

where a, b are constant coefficients.

3. Transient processes in automatic control systems. Dynamic characteristics of links

The process of transition of a system or object of regulation from one equilibrium state to another is called a transition process. The transient process is described by a function that can be obtained by solving the dynamic equation. The nature and duration of the transition process are determined by the structure of the system, the dynamic characteristics of its links, and the type of disturbing influence.

External disturbances can be different, but when analyzing a system or its elements, they are limited to typical forms of influences: a single stepwise (jump-like) change in time of an input quantity or its periodic change according to a harmonic law.

The dynamic characteristics of a link or system determine its response to such typical forms of influence. These include transition, amplitude-frequency, phase-frequency, amplitude-phase characteristics. They characterize the dynamic properties of a link or an automated system as a whole.

The transient response is the response of a link or system to a single step action. Frequency characteristics reflect the response of a link or system to harmonic oscillations of an input quantity. Amplitude-frequency response (AFC) is the dependence of the ratio of the amplitudes of the output and input signals on the oscillation frequency. The dependence of the phase shift of oscillations of the output and input signals on frequency is called phase-frequency characteristics (PFC). By combining both mentioned characteristics on one graph, we obtain a complex frequency response, which is also called the amplitude-phase response (APC).