Steam Boiler Design

Steam Boiler Design:

Boiler design is the process of designing boilers used for various purposes. The main function of a boiler is to heat water to generate steam. Steam produced in a boiler can be used for a variety of purposes including space heating, sterilization, drying, humidification and power generation. The temperature or condition of steam required for these applications is different, so boiler designs vary accordingly.

Modern Design Benefit:

Modern boiler design offers several benefits. In the past, improper design of boilers has caused explosions which led to loss of life and property. Modern designs attempt to avoid such mishaps. Further, mathematical modeling can determine how much space a boiler will need and the type of materials to be used. When the design specifications of a boiler are determined, design engineers can estimate a cost and time schedule for the construction.

Essential Boiler Fittings-Steam Trap.

ESSENTIAL BOILER FITTINGS-STEAM TRAP:

A steam trap is a device used to discharge condensate and non-condense able gases with a negligible consumption or loss of live steam. Most steam traps are nothing more than automatic valves. They open, close or modulate automatically. The three important functions of steam traps are:

1. Discharge condensate as soon as it is formed.(Unless it is desirable to use the sensible heat of the liquid condensate)
2. Have a negligible steam consumption.(i.e. being energy efficient)
3. Have the capability of discharging air and other non-condense able gases.

Three views of a c.1885 steam trap. The general appearance of this arrangement is as in Fig. 1 or Fig. 3, the center view, Fig. 2, shows the cardinal feature of this trap, that it contains a collector for silt, sand, or sediment which is not, as in most other traps of the time, carried out through the valve with the e-flux of water.

Steam Boiler Or Steam Generator Works In A Power Plant

Thermal power plants are one of the main sources of electricity in both industrialized and developing countries. The variation in the thermal power stations is due to the different fuel sources (coal, natural gas, naphtha, etc). In a thermal power plant, one of coal, oil or natural gas is used to heat the boiler to convert the water into steam. In fact, more than half of the electricity generated in the world is by using coal as the primary fuel.

Boiler Essential Fittings Pressure Gauge

Pressure measurement

Example of the widely used Bourbon pressure gauge

Many techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure and display pressure in an integral unit are called pressure gauges or vacuum gauges. A manometer is a good example as it uses a column of liquid to both measure and indicate pressure. Likewise the widely used Bourbon gauge is a mechanical device which both measures and indicates, and is probably the best known type of gauge.

A vacuum gauge is an absolute pressure gauge used to measure the pressures lower than the ambient atmospheric pressure.

Other methods of pressure measurement involve sensors which can transmit the pressure reading to a remote indicator or control system.

Boiler Types

Boiler types

Haycock and wagon top boilers

For the first Newcomer engine of 1712, the boiler was little more than large brewer's kettle installed beneath the power cylinder. Because the engine's power was derived from the vacuum produced by condensation of the steam, the requirement was for large volumes of steam at very low pressure hardly more than 1 psi (6.9 k Pa) The whole boiler was set into brickwork which retained some heat. A voluminous cos therefore a great deal of heat wasted up the chimney. In later models, notably by John Smeaton, heating surface was considerably increased by making the gases heat the boiler sides, passing through a flal fire was lit on a grate beneath the slightly dished pan which gave a very small heating surface; there waue. Smeaton further lengthened the path of the gases by means of a spiral labyrinth flue beneath the boiler. These under-fired boilers were used in various forms throughout the 18th Century. Some were of round section (haycock). A longer version on a rectangular plan was developed around 1775 by Bolton and Watt (wagon top boiler). This is what is today known as a three-pass boiler, the fire heating the underside, the gases then passing through a central square-section tubular flue and finally around the boiler sides.

Essential Boiler Fittings-Safety Valve

A safety valve

A safety valve is a valve that acts as a fail-safe in a thermal-hydraulics plant. An example of safety valve is a pressure relief valve (PRV), which automatically releases a substance from a boiler, pressure vessel, or other system, when the pressure or temperature exceeds preset limits. Pilot-operated relief valves are a specialized type of pressure safety valve.

Safety valves were first developed for use on steam boilers during the Industrial Revolution. Early boilers operating without them were prone to explosion.

Vacuum safety valves (or combined pressure/vacuum safety valves) are used to prevent a tank from collapsing while it is being emptied, or when cold rinse water is used after hot CIP (clean-in-place) or SIP (sterilization-in-place) procedures. When sizing a vacuum safety valve, the calculation method is not defined in any norm, particularly in the hot CIP / cold water scenario, but some manufacturers [1] have developed sizing simulations.

More About Safety Valve

Boiler Safety To Avoid Boiler Accidents

Boiler safety

When water is converted to steam it expands in volume over 1,000 times and travels down steam pipes at over 100 kilometers/hr. Because of this, steam is a good way of moving energy and heat around a site from a central boiler house to where it is needed, but without the right boiler feed water treatment, a steam-raising plant will suffer from scale formation and corrosion.

At best, this increases energy costs and can lead to poor quality steam, reduced efficiency, shorter plant life and an operation which is unreliable. At worst, it can lead to catastrophic failure and loss of life. While variations in standards may exist in different countries, stringent legal, testing, training and certification is applied to try to minimize or prevent such occurrences. Failure modes include:

• over pressurization of the boiler

• insufficient water in the boiler causing overheating and vessel failure

• pressure vessel failure of the boiler due to inadequate construction or maintenance.