Steam boiler automatic control system

Contents

1. General part

Introduction

1.1.Process description

1.2.Description of object structure

1.3.Base the need for monitoring, regulation and alarm

process parameters

2. Special part

2.1.Select Automation Tools

2.2.Description of the object automation diagram

2.3.Description of instrumentation board

2.4.Description of external connection diagram

2.5.Recipitation of schematic diagram

2.6. Description of installation and adjustment of the system

automatic control

2.7.Order Equipment Specification

2.8.Specification for installation

products and materials

3. Research part

3.1.The object of the study

3.2.Recalculating sensitivity of steam supply control system

3.3. Calculation of automatic temperature control system

4. Economic part

4.1. Cost estimates of automation equipment

4.2. Calculation of depreciation deductions

4.3. Calculation of the number of workers and

4.4. Calculation of the annual salary fund of specialists

4.5. Payroll calculation

4.6. Estimated operating costs

4.7. Calculation of economic efficiency of ATS

5. Life safety and ecology

5.1.Protection of labor

5.2.Protection measures for employees against harmful factors

5.3. Environmental protection measures

5.4.Compute emissions from natural gas boiler house

5.5.Security in emergency situations

List of sources used

Summary

The process of superheated steam preparation in the boiler plant based on the DE1014GM boiler is described. Methods of automatic control of temperature of superheated steam depending on its flow rate are considered. Automation schemes based on modern electronic modules have been developed. Transient processes in automatic control system are calculated and its stability is studied. The economic effect from the introduction of ECS boiler plant DE1014GM is calculated.

Introduction

In terms of automation, thermal power engineering occupies one of the leading places among other industries. Thermal power plants are characterized by the continuity of their processes. At the same time, the generation of thermal and electrical energy at any time must correspond to consumption (load). Almost all operations at thermal power plants are mechanized, and transitional processes in them develop relatively quickly. This explains the high development of automation in the thermal power industry.

Automation of parameters offers significant advantages:

1) ensures reduction of the number of working personnel, i.e. increase of their labor productivity,

2) leads to a change in the nature of labor of maintenance personnel,

3) increases the accuracy of maintaining the parameters of the generated steam,

4) improves safety of work and reliability of equipment operation,

5) increases efficiency of steam generator operation.

Automation of steam generators includes automatic regulation, remote control, process protection, heat and technical control, process interlocks and alarms.

Automatic control ensures the course of continuous processes in the steam generator (water supply, combustion, steam overheating, etc.)

Remote control allows the duty personnel to start and stop the steam generator plant, as well as switch and adjust its mechanisms at a distance, from the console where the control devices are concentrated.

Thermal control over the operation of the steam generator and equipment is carried out using showing and self-recording devices, acting automatically. Devices conduct continuous monitoring of processes taking place in a steam generator plant, or are connected to a measurement object by maintenance personnel or an information-computing machine. Heat control devices are placed on panels, control boards as convenient as possible for observation and maintenance.

Process interlocks are performed in a given sequence of operations during starting and stopping of mechanisms of the steam generator plant, as well as in cases of process protection actuation. Interlocks exclude incorrect operations when servicing a steam generator plant, provide disconnection in the necessary sequence of equipment in case of an accident.

Process alarm devices inform the duty personnel about the state of the equipment (in operation, stopped, etc.), warn about the approach of the parameter to a dangerous value, report on the occurrence of an emergency state of the steam generator and its equipment. Sound and light alarms are used.

Operation of boilers shall ensure reliable and efficient generation of steam of required parameters and safe working conditions of personnel. In order to fulfill these requirements, operation must be carried out in strict accordance with the laws, rules, norms and guidelines, in particular, in accordance with the "Rules for the construction and safe operation of steam boilers" of Gosgortekhnadzor, "Rules for the technical operation of electric stations and networks," "Rules for the technical operation of heat-using plants and heating networks," etc.

On the basis of the mentioned materials, job descriptions and process instructions for equipment maintenance, repair, safety, accident prevention and elimination, etc. shall be drawn up for each boiler plant. Technical passports for equipment, as-built, operational and technological diagrams of pipelines of various purposes shall be drawn up. Knowledge of the instructions, boiler operating mode maps and specified materials is mandatory for the personnel. The knowledge of the maintenance personnel should be systematically checked.

Operation of boilers is carried out according to production tasks compiled according to plans and schedules of steam generation, fuel consumption, electric power consumption for own needs, it is mandatory to maintain an operational log, which contains the instructions of the manager and the records of the personnel on duty on the operation of the equipment, as well as a repair book, which records information about the observed defects and measures to eliminate them.

Primary reporting shall be maintained, consisting of daily statements for the operation of units and records of recording devices and secondary reporting, including generalized data on boilers for a certain period. Each boiler is assigned its own number, all communications are painted in a certain conditional color set by GOST. The installation of boilers in the room must comply with the rules of Gosgortekhnadzor, safety requirements, sanitary and technical standards, fire safety requirements.

1.1.Process description.

A steam boiler is a complex of units designed to produce water vapor. This complex consists of a number of heat exchange devices connected to each other and serving to transfer heat from fuel combustion products to water and steam. The initial carrier of energy, the presence of which is necessary for the formation of steam from water, is the fuel.

The main elements of the working process carried out in the plant are:

1) fuel combustion process,

2) process of heat exchange between combustion products or burning fuel itself with water,

3) steam generation process consisting of water heating, evaporation and steam heating.

During operation, two interacting flows are formed in boilers: the flow of working medium and the flow of coolant formed in the furnace.

As a result of this interaction, steam of a given pressure and temperature is obtained at the outlet of the object.

One of the main tasks that arises during the operation of the boiler unit is to ensure equality between the energy produced and consumed. In turn, the processes of steam generation and energy transfer in the boiler unit are uniquely associated with the amount of substance in the currents of the working medium and coolant.

Fuel combustion is a continuous physicochemical process. The chemical side of combustion is the process of oxidizing its combustible elements with oxygen, passing at a certain temperature and accompanied by the release of heat. The intensity of combustion, as well as the economy and stability of the fuel combustion process depend on the method of supply and distribution of air between the fuel particles. It is conventionally accepted to divide the fuel combustion process into three stages: ignition, combustion and afterburning. These steps generally proceed sequentially over time, partially superimposed on one another.

The calculation of the combustion process usually consists of determining the amount of air per m3 required to combust the unit mass or volume of the fuel of the amount and composition of the heat balance and determining the temperature of the combustion.

The heat transfer value is the heat transfer of the heat energy generated by the combustion of the fuel, the water from which steam is to be obtained, or the steam if it is necessary to raise its temperature above the saturation temperature. The heat exchange process in the boiler proceeds through waterproof heat conducting walls called the heating surface. Heating surfaces are made in the form of pipes. Inside the pipes there is a continuous circulation of water, and outside they are washed by hot flue gases or perceive thermal energy by radiation. Thus, all types of heat transfer take place in the boiler: thermal conductivity, convection and radiation. Accordingly, the heating surface is divided into convective and radiation. The amount of heat transferred through a unit of heating area per unit time is called the heat stress of the heating surface. Voltage value is limited, first, by properties of material of heating surface, second, by maximum possible intensity of heat transfer from hot heat carrier to surface, from heating surface to cold heat carrier.

The intensity of the heat transfer coefficient is higher, the higher the temperature difference of the heat carriers, the speed of their movement relative to the heating surface and the higher the surface purity.

The formation of steam in boilers proceeds with a certain sequence. Already in the screen pipes, the formation of steam begins. This process proceeds at high temperature and pressure. The phenomenon of evaporation consists in the fact that individual liquid molecules located at its surface and having high speeds and, therefore, higher kinetic energy compared to other molecules, overcoming the power effects of neighboring molecules, which creates surface tension, fly into the surrounding space. With an increase in tempera-tour, the intensity of evaporation increases. The reverse vaporization process is called condensation. The liquid formed by condensation is called condensate. It is used to cool metal surfaces in superheaters.

The steam generated in the boiler unit is divided into saturated and superheated. Saturated steam, in turn, is divided into dry and wet. Since superheated steam is required at thermal power plants, a superheater is installed for its overheating, in this case, a screen and conjunctive one, in which heat obtained from combustion of fuel and exhaust gases is used for steam overheating. The obtained superheated steam at temperature T = 540 С and pressure P = 100 atm goes to technological needs.

1.2 Description of the structure of the object

Steam boilers of DE type with a steam capacity of 10 t/h, with an absolute pressure of 1.4 MPa (14 kgf/cm2) are designed to generate saturated or superheated steam used for the technological needs of industrial enterprises for heat supply to heating and burning water supply systems.

Double-drum vertical-water-tube boilers are made according to the structural scheme "D," a characteristic feature of which is the lateral location of the convective part of the boiler relative to the firebox.

The main components of the boilers are the upper and lower drums 1, the convective bundle and forming the furnace chamber 2 the left furnace screen (gas-flooded partition), the right furnace screen, pipes for shielding the front wall of the furnace and the rear screen.

Air required for fuel combustion is supplied from below to the furnace by blast fans 3. The fuel combustion process proceeds at high temperatures, so the boiler screen pipes receive a significant amount of heat by radiation.

Fuel combustion products, otherwise referred to as gases, are supplied to the chimney gas ducts, the surface of the superheater 4 is heated, the pipes of the economizer 6 are washed, in which the pit water is heated to a temperature close to 200 ° C, supplied to the drums of the boiler 1. Further, the flue gases pass into the chimney 5 and enter the air chimney 7. Gases come out of it through the atmosphere. Water is supplied to the boiler via pipeline 9, gas pipeline 10. Steam from the boiler drum, bypassing superheater 4, is supplied to steam pipeline 11.

One of the most important indicators of boiler design is its circulation capacity. Uniform and intensive circulation of water and steam mixture facilitates the washing off of bubbles of steam and gas emitted from the water, as well as prevents the deposition of scale on the walls, which in turn provides a low wall temperature (200-400 C), not much higher than the saturation temperature and not yet dangerous for the strength of boiler steel. Steam boiler DE 1014 G belongs to natural circulation boilers .

2.1 Selection of automation tools

The complex of devices and devices of the type "Loop D" is designed to build local systems for automatic regulation of thermal processes in the power industry, industrial complex, heat supply and heating systems. The complex includes fourteen versions of multifunctional control devices with pulse output of RS 29 type and two versions of three-position amplifier of U29 type.

The Circuit 2 complex is built according to the model principle on a modern microelectronic element base. It is characterized by expanded functionality, wider use of DC signals, increased accuracy and reliability, significantly smaller dimensions and weight compared to the Loop complex

Control devices of PC29 type provide amplification, damping and indication of mismatch signal. Together with the constant speed actuator, the regulators form PI - or PID - control laws and allow manual control of the actuator. They provide indication of the position of the actuator equipped with rheostatic or inductive position sensors, as well as analogue-relay conversion through two channels with actuation indexation.

Depending on the modification, the devices can perform additional functions: differentiation of signals according to aperiodic law, nonlinear signal conversion, digital indication of one of four signals on call. The design of control devices is uniform. The functional structure of most versions of the devices can be easily changed by rearranging the jumpers on a special switching field accessible to the consumer, which makes it possible to perform analog-relay conversion with damping, input signals by derivative, and perform dynamic communication between the regulators.

2.2.Recipitation of automation diagram.

Functional diagram of process automation systems is the main technical document defining the structure and nature of process automation systems, as well as their equipping with instruments and automation tools. The functional diagram gives a simplified image of the units subject to automation, as well as the devices, automation and control tools depicted by the symbols according to the current standards, as well as the communication line between them.

The steam boiler control and control automation scheme provides for the following systems:

system for automatic control and control of boiler heat load

automatic control and control system of boiler power supply

automatic control and control system of gas-air ratio

system for automatic control and control of vacuum in boiler furnace

automatic pressure monitoring system

automatic temperature monitoring system

automatic gas cut-off system

2.2.1.Automatic control system

And heat

load control.

Thermal load controller operates from two parameters:

1. Pressure drop proportional to steam flow rate is created on DKS 10200A/G diaphragm (pos.1-2) installed on steam line, converted by SAPFIR22DD2420 measuring converter (pos.1-3) into unified current signal of 0-5 mA and supplied to BIK1 root extraction unit (pos.1-4), which is assigned to 2PIPDD D 2 converter output controller. And on the secondary device DISC2502121 (pos.1-6).

2. Pressure change signal in boiler drum. Pressure in the boiler bar-bath is measured using SAPPHIR22DI2150 converter (item 1-1). The unified current signal 0-5 mA from the converter goes to the regulator RS 29.0.12 (pos.1-7) and to the secondary device DISC2502121 (POS.1-5).

In regulator signals are summed from transducers with specified value. If these values are equal, then the regulator does not affect the object. If the adjustable parameter deviates from the specified value, a pulse signal is generated at the output of the regulator, which in U29.3 amplifier (pos.7-8) is converted into a change in the state of contactless keys. The U29.3 amplifier has three contactless switches for controlling the MEO actuator 40/250.25R (pos.1-9), the shaft of which is connected through the system of rods and levers with the control element of the ECU 100, which changes the gas supply to the boiler furnace.

2.2.2.Automatic control system

And

control of boiler power supply.

The boiler power regulator operates according to a three-pulse scheme, three receptacles are used: feed water flow; steam flow rate; level in the boiler bar.

Feed water flow rate and steam flow rate are measured by the variable drop method. The pressure difference proportional to a feedwater expense created on a diaphragm of DKS 10100A/G1 (poses.2-1), and the pressure difference proportional to steam consumption created on a diaphragm of DKS 10200A/G1 (poses.1-2) are measured and will be transformed by the SAPFIR-22DD-2420 converters (poses.13;22) to the unified current signals 0-5 ma., from the output of the measuring SAPFIR22DD2420 converters the signals are given on blocks of extraction of root BIK1 (poses.14; 2-3) intended for linearization of static characteristic of SAPFIR-22DD converters

Signals 0-5 mA from BIC -1 units are transmitted to DISK 2502121 secondary devices (pos.16, 2-5) and to the output of RS regulator 29.0.12 (pos.2-7).

The level in the boiler drum is measured by SAPFIR22DI2150 converter (pos.2-4) and converted into a unified current signal of 0-5 mA, which is supplied to DISK 2502121 secondary device (pos.2-6) and to the input of RS controller 29.0.12 (pos.2-7).

In case of deviation of one of the specified parameters, JN controller 29 acts by means of amplifier U 29.3 (pos. 2-8) on MEO mechanism 40/250.25 (pos. 2-9), which actuates control element of CPC 100 (pos. 10) installed on feedwater pipeline.

2.2.3.Automatic control system

And

gas-to-air control.

Measurement of gas and air flow rate is carried out by the variable drop method. Pressure drop across DKS diaphragm 0, 6100A/G1 (pos. 3-2) and DKS diaphragm 0,6400/G-1 (pos. 3-1) is measured by SAPFIR22DD-2420 converter (pos. 33; 34). Signal 05mA from the converter is supplied to BIC-1 root extraction unit (pos. 35; 3-6) intended for linearization of static characteristic of SAPFIR22DD converter. Signal 0-5 mA from BIC -1 root extraction unit is transmitted to DISK 2502121 secondary device (pos.38; 39) and to JN controller 29.0.12 (pos. 3-7).

In the regulator PC 29, two incoming signals are summed up and then compared to a predetermined value. If the adjustable parameter deviates from the specified value, an error signal appears at the input of the electronic regulator unit. At that, pulse signal (24V) is generated at regulator output, which is supplied to U29.3 amplifier. (pos.313) The amplifier U29.3 controls the actuator of the MEO 40/100.25 (pos.311), which changes the air supply with the help of the regulator. Oxygen correction (O2) in exhaust gases is performed in this system. The signal from the indicator to oxygen "Alpha" (pos.312) through the secondary device DISC 2502121 (pos.310) goes to the regulator RS 29.0.42 (pos.314), at its output there is a signal that is corrective for the regulator RS 29.0.12 (pos.3-7).

2.2.4. Automatic control and control system in the boiler furnace.

Pressure in boiler furnace is measured using SAPFIR converter 22 DIV 2310 (pos.4-1). The signal from the converter is transmitted to secondary device DISC 2502121 (pos.4-3) and to JN controller 29.0.12 (pos.4-2). In case of deviation of adjustable parameter, JN controller 29, which by means of amplifier U 29.3 (pos.4-4) energizes motor of 40/100.25R MEO actuator mechanism (pos.4-5), which changes the positions of the smoke pump guide vanes.