Boiler - heat recovery unit V-90B

Contents

Introduction

1. Description of the cat-la

2. Heat calculation of boiler unit

3. Evaporation Surface Calculation

Conclusion

List of information sources

Introduction

Energy reached its peak in Soviet times, when construction was actively developing on the vast expanses of a huge country. In record time, industrial cities appeared that required a large amount of electricity. It was provided to them by giant power plants. Both thermal, atomic (new at that time, progressive, direction of the electric power industry), and hydroelectric power plants, for the creation of which rivers were sent to another channel. Against this background, the appearance and development of energy technology and recycling boilers was logical. They, being part of the production line, perform several functions at once. They simultaneously serve to cool flue gases after furnaces of a particular production, serve as a kind of protection in the event that the production gases are toxic, as well as to generate steam that goes either for technological or heating needs, or takes further part in the production line.

The rational use of fuel and energy resources is an important task, the importance of which is increasingly growing. Significant savings in fuel and energy resources can be achieved with a wider involvement of secondary energy resources in the fuel and energy balance of the country, which are available in almost all industries where thermal processes are used, primarily high-temperature ones. The thermal efficiency for many thermal processes does not exceed 1535%.

The use of secondary energy resources (RES) has received considerable attention in recent years. However, the issues of the rational use of RES are not sufficiently covered. It is necessary for rational use of RES to increase the efficiency of recovery boilers and power engineering units, which can be achieved by the following measures:

- application of high-efficiency heat perception of heating surfaces (pipes with small diameters, longitudinal and transverse fins, gas medium turbulizers);

- development and development of high-efficiency methods of cleaning heating surfaces from external sediments of technological carry-over (acoustic, incompationic shock-wave );

- expansion of pipes application with surface layer coating by elements reliably operating under conditions of corrosion-erosion media exposure;

- development of basic structures and creation of unified modules for units and parts based on them;

- application of automatic design systems;

- application of automatic control systems.

1. boiler description

Recovery boiler V-90B designed to cool converted gases and produce saturated steam with a steam capacity of 5 t/h and a pressure of 0.8 MPa and a temperature of 170 ° C for technological and household needs of the enterprise.

Recovery boiler-gas-tube, with natural circulation, vertical, with removed steam collector. The boiler can be installed in closed and open rooms with ambient temperature up to 35C.

The evaporation part is a drum with an internal diameter of 1560 mm and a wall thickness of 20 mm, with flat flanged bottoms and evaporation pipes welded to them. The drum is installed at an angle of 10 relative to the vertical axis to improve natural circulation and the required steam volume above the water level in the drum and maintain low humidity of steam. Gas branch pipes welded to upper and lower bottoms of drum are provided for supply and from-water of gases. Gas passes through 99 chimneys with a diameter of 83 × 3, 5 mm (steel 20K). Lower gas supply through inlet gas chamber. Evaporator drum pipes are fixed in tube boards by means of their flaring in them. Special caps in the form of an expanding diffuser are installed at the ends of the chimney pipes, which increase the service life of the evaporation drum and the inlet edge of the pipes due to intense dust discharge. Separation device in the form of hole sheets and reflector is located in drum. Steam collector with internal diameter of 1200 mm with wall thickness of 13 mm is installed on two supports (movable and not movable) welded to vertical shell of drum. Feed water with a temperature of 105 ° C enters the upper drum, and from it through two lowering pipes to the evaporation drum. Steam-water mixture is directed through pipes to separation drum. During installation, boilers rest on four supports welded to the drum in its lower part.

For maintenance, the recovery boiler is equipped with scaffolding and ladders, control instruments, necessary valves and pipelines within the boiler.

The recovery boiler is supplied by transportable units: two drums with an evaporative surface, a drum collector with a separation device, brackets, supports, a pipeline within the boiler, and valves.

Vertical gas tube boilers were not widely used in industry due to known design and operational shortcomings: the possibility of steaming the upper flat bottoms, unreliable attachment of pipes in pipe boards, the impossibility of ensuring stable cooling of pipe boards, etc.

Conclusion

The course design shows the calibration and structural heat and heat calculation of the B90B boiler unit designed to cool the converted gases. Steam efficiency of boiler D = 5030 kg/s, parameters of working medium in heating surface; convective part of boiler is calculated by means of joint solution of equations of thermal balance and heat transfer by method of successive approximations.

By taking the temperature of the gases behind the heating surface, solving the equation of thermal balance, heat transfer; calculating the value of the coefficient of heat transfer from the gases to the wall for evaporation bundles, they found the amount of heat that is perceived by the heating surface from the utilised gases Qt, as well as the heat perception of the heating surface by convection and radiation of the utilised gases Qb.

The temperature of the exhaust gases is known and has been accepted as a tempera-tour of gases after the evaporation surface. The heat calculation of the boiler unit was carried out, as a result of which the following were calculated: heat perception of the evaporation surface, the calculated length of the chimney pipes of the drum, heat transfer coefficients from gases to the wall, heat transfer in staggered bundles by convection and radiation taking into account the contamination of the pipe wall, the average speed of gases, error of calculations. Also, as a result of the calculation, the boiler design was determined, in particular, an increase in the length of the chimneys in the evaporation drums to improve heat perception and heat exchange by emitting recycled gases .

Thermal divergence within acceptable limits.

Котел-утилизатор для охлаждения конвертерных газов В-90Б.dwg