Boiler Water Chemistry & Steam Generation System in Power Plant in India
Boiler Water Chemistry & Steam Generation System in Power Plant generates steam at a temperature of 150°C is in operation.
Introduction to Boiler and Steam Generation System in Power Plant.
Boilers are often the principal steam and hot water generator system used in Industrial power generation plant or commercial heating by combusted fuels to improve manufacturing processes, increase engine efficiency and conserve energy. In the boiler Electric Furnace when a fuel is burned, the chemical energy in the fuel is converted into heat by specific electrochemical reactions and it is the function of a boiler to transfer this heat to the contained water by generating high-pressure steam in a boiler for generating electric power. In a fossil fuel power plant, the higher the furnace temperature, the faster the steam production.
Two types of the boiler are in Thermal Power Plant:
Based on the direction of the principal axis of the shell a Horizontal, Vertical and Inclined boiler, the boilers are divided into two parts.
1. Fire Tube Boiler:- The fire tube boiler consists of a number of tubes through which heat passes in a closed vessel, which are surrounded by water. Due to hot fire tube, the water heated up and converts the water into steam. A fire tube boiler cannot produce steam at high pressure as the water and steam both are present in the same vessel.
There are two types of Fire Tube Boiler:
I. External Furnace Fire Tube Boiler
II. Internal Furnace Fire Tube Boiler
Advantages & Disadvantages of Fire Tube Boiler:
Water Tube Boiler: This kind of boiler in which the water is heated inside tubes and the hot gasses surround them. The tubes are interconnected to common channels or headers. Water tube boiler is fitted just opposite to the fire tube boiler.
There are three types of Water Tube Boiler:
I. Horizontal straight Tube Boiler
II. Bent Tube Boiler
III. Cyclone Fired Boiler
Advantages & Disadvantages of Water Tube Boiler:
The Boiler is one of the parts in the global heating system. A Hydronic system consists of few main parts.
1. Burner & Heat Exchanger (the part producing the heat)
2. Piping, Circulator pumps, and Valves (The part circulating the heat)
3. Radiators and convectors (the parts emitting the heat to the room)
4. Firebox (act as a mediator where the fuel of a system meets the air)
5. Combustion Air Blower and Steam Traps
6. Deaerators/Condenser (Used to maintain tank water temperature at around 105 degree Celsius)
7. Economizer (Heat Exchanger)
8. Superheater (This part increase the temperature of saturated steam)
Internal Boiler fitting Valves and Accessories:
1. Butterfly Valves: It is made up of two semi-circular plates hinged on a same spindle, it is used to allow flow in one direction only.
2. Gate Valves: It is widely used in Industrial Piping. They are called as stop valves as it fully shut off or turn on flow.
3. Globe Valves: Globe valve seating is parallel position to the line of flow.
4. Swing Check Valves: It uses a hinged mounted disc that swings. It can be used in the horizontal and vertical position.
5. Check Valves: The valves are designed to automatically prevent the reverse flow in a pipeline system.
6. Lift or Piston Check Valve: This kind of Check valve uses a piston rather than a hinge-mounted disc to prevent the reversal of flow.
7. Regulating Valves: This type of Valve can be used in any system on a boiler from flow to fuel flow. By adjusting the flow area, regulators attempts to manage flow.
8. Direct-Operated Regulator: Within this valve, managed pressure is applied to some internal surface.
The boiler should be designed to generate high-quality steam and the maximum amount of heat possible from combustion into the water using a process such as Conduction as the flow of heat from one solid to another, Radiation as heat transfers in boiler furnace, and Convection as a transfer of energy by movement of a medium.
Boiler Efficiency Calculation:
There are two methods to measure the boiler efficiency:
1. Boiler Efficiency by Direct Method: Boiler efficiency depends on many parameters apart from combustion. In this Method The energy gain of the working fluid is compared with the energy Content of the boiler fuel:
Boiler Efficiency = Heat Output/Heat Input*100
Boiler Efficiency = (Q * (Hg – Hf))/ (q * GCV) * 100%
Q = Rate of steam flow in kg/h
Hg = enthalpy of steam (kcal/kg)
Hf = enthalpy of water in kcal/kg
q = quality of fuel used per hour in kg/hr
GCV = Gross Calorific value in the fuel in kcal/kg
2. Indirect Method: To measure the Indirect Boiler efficiency, We have following parameter like:
Boiler Efficiency by Indirect Method = 100 – (L1+ L2 + L3 + L4 + L5 + L6 + L7+ L8)
Ultimate analysis of fuel (H2, S2, S, C moisture constraint, ash constraint)
Percentage of O2 or CO2 at flue gas
Flue gas temperature at the outlet
The ambient temperature in deg c and humidity of air in kg/kg
GCV of fuel in kcal/kg
Ash percentage in combustible fuel
GCV of ash in kcal/kg