Deaerator working principle, Types and Process Control

Deaerator working principle, Types and Process Control

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Deaerators is commonly employed in any chemical process industry or in Power Plants wherever boiler is utilized for steam production from boiler feed water. Deaerator solves the aim of removal of unwanted dissolved gases and dissolved oxygen from the boiler feed water before going in boilers. Most of the deaerators are designed in such how that the dissolved oxygen content within the outlet water is regarding7 ppb by WTC.

Principle of Dearators

Dearator commonly works based on the subsequent principles.

Henry’s Law

According to Henry’s low is in a liquid the gas solubility is directly proportional to the partial pressure. thus if we tend to decrease the partial pressure of the dissolved gas by adding steam in Deaerator, its solubility decreases and also the gas is faraway from water.

Inverse Solubility of Water

When the temperature of water is growing, the dissolved oxygen content within the water is decreases. Thus the water temp. is growing by inserting steam in Deaerator, the dissolved gas solubility is reduced and also the gases are withdrawal from water.

Types of Deaerators

1. Tray types Deaerator

Tray type deaerators contain perforated trays within the top of the Deaeration section. The bottom portion volume is high for used as storage for boiler feed water. Feed water to deaerator enters into the perforated trays wherever the area and residence time is growing to contact with steam. Then the water goes to the horizontal storage section wherever steam is pass through sparger pipe to withdrawn the remaining traces of dissolved gases and keep the stored water at its saturation temperature.

Tray Deaerator

2. Spray type Deaerator

Spray Deaerator type deaerator contains spray nozzle in feed water entry space. it’s then preheated and deaerated and sent to storage section. In storage section also steam is additional to stay the water at its saturation temperature.

Spray type Deaerator

Process control system in Deaerator

Deaerator operate in very low pressure steam about 0.5 to 1.5 kg/cm2 with can produce in process plant.The low steam sources could also be anyone of the following: Extraction from back pressure turbines, Flash steam recovered from Boiler blow down or letdown steam from high pressure steam header through pressure reducing valve. Steam pressure within the deaerator should be maintained to facilitate the removal of dissolved gases from water and also to produce adequate NPSH to boiler feed pump. Deaerators are commonly put in at high elevation so as to produce enough NPSH within the event of failure in steam pressure control conjointly. Pressure safety valve is additionally fitted to avoid pressurization of deaerator because of malfunctioning of pressure control valve.

Process control system in Deaerator

Water Level control

Main sources of raw water to deaerator are Treated water from water treatment plant and steam condensate from the condensing type turbines. During the stable plant operation the water balance is maintained and through any upset within the higher than said sources water level fluctuates and control is important. High level and low level alarms are provided. Low level might lead to starvation of feed water in pump and High level leads to water entry into steam header. Thus overflow drain is put in to drain the water if very high level is reached.

 

Deaerator Water Level control

 

Other benefits of Deaerator

Dearator acts as an extra storage that provides reserve amount of boiler feed water throughout upstream water supply failure for momentary periods commonly for about twenty minutes.

In some of the Plants, Deaerator is additionally used for dosing oxygen scavenging chemicals like hydrazine or Hydroquinone.

What is a Boiler? & its types

 

Boiler overview

What is a Boiler? & its types

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What is Boiler:- A boiler is outlined as “A closed vessel during which water or different liquid is heated, steam or vapor is generated, steam is super heated, or any combination therefrom, besieged or vacuum, to be used external to itself, by the direct application of energy from the combustion of fuels, from electricity or energy ”.

A Brief Introduction :

Boiler may be a main operating element of thermal power plants.

Water is helpful and low-cost medium for transferring heat to a method.

once water is warm into steam its volume will increase regarding 1,600 times, manufacturing a force that’s virtually as explosive as bomb.

This causes the boiler to be extra ordinarily dangerous instruments and equipment will be treated carefully

Liquid once heated to the vaporous state this method is named evaporation.

The heating surface is any a part of the boiler; hot gases of combustion square measure on one facet and water on the opposite. Any a part of the boiler metal that truly contributes to creating steam is heating surface.

the quantity of heating surface of a boiler is expressed in sq. meters.

The larger the heating surface a boiler has, the a lot of economical it becomes.

 

CPP Boiler Plant over view

Fuel Used in Boiler

The list of major fuels that square measure used in boiler systems is given below:

1. N.G. (Natural Gas)

2. Propane

3. Oil

4. Electricity

5. Solids Fuels like Coal & Wood

6. Renewable Energy

Solid Boiler fuels:- Major solid fuels used for burning in a very boiler embody coal and wood. They were the sole fuel sources obtainable to be used in boiler systems before the emergence of heating heating oil. These square measure the most affordable means that of boiler fuels that are becoming exhausted day by day because uncontrolled use.

• Wood
• Coal
• Briquettes
• Pet Coke
• Rice Husk

Liquid Boiler Fuels :

• L.D.O.
• F.O.
• LPG :- In observe, LPG is especially employed in applications wherever the supply of gas is either terribly restricted or expensive. LPG works as a boiler fuel in similar manner as gas. However, the boiler in use should be capable of conversion options so it may be created compatible with LPG.

Major vaporous Boiler Fuels square measure as :

• LPG
• LNG
• PNG are often accustomed do the combustion for the precise purpose.

Components of Boiler System

There square measure three backbone parts of any boiler system:

1. Boiler Feed Water System

Water that converts into steam by vessel system known as Feed water & system that regulates feed water known as Feed water system.

There square measure 2 styles of feed water systems in boilers:

 

Boiler Feed Water Pump Design

• Open feed System
• Closed feed system

There square measure2 main sources of feed water:

• Condensed steam came from the processes
• Raw water organized from outside the boiler plant processes ( Called: Makeup Water)
• Boiler feed pump: Ring-section model with sound stage
• Multi Stage Boiler Feed pump

2. Boiler Steam System

Steam System is quite main dominant system of boiler method. Steam Systems square measure accountable to gather all generated steam within the method.

Steam systems send steam generated within the method to the purpose of use through pipes ( piping system). Throughout the method, steam pressure is controlled and controlled with the assistance of boiler system components like valves, steam pressure gauges etc.

 Process Flow Diagram

There square measure three backbone parts of any boiler system:

1. Boiler Feed Water System

Water that converts into steam by vessel system known as Feed water & system that regulates feed water known as Feed water system.

There square measure 2 styles of feed water systems in boilers:

• Open feed System
• Closed feed system

There square measure2 main sources of feed water:

• Condensed steam came from the processes
• Raw water organized from outside the boiler plant processes (Called: Makeup Water)
• Boiler feed pump: Ring-section model with sound stage
• Multi Stage Boiler Feed pump

2. Boiler Steam System

Steam System is quite main dominant system of boiler method. Steam Systems square measure accountable to gather all generated steam within the method.

Steam systems send steam generated within the method to the purpose of use through pipes ( piping system). Throughout the method, steam pressure is controlled and controlled with the assistance of boiler system components like valves, steam pressure gauges etc.

3. Boiler equipment

Fueling is that the heart of boiler method consists of all needed|the mandatory} parts and instrumentation to feed fuel to get required heat. The instrumentation needed within the equipment depends on the sort of fuel employed in the system.

Boiler Applications

The Boilers have a really a large application in numerous industries like

1. Food Plant

Food should usually be heated or boiled through out process. so this industrial sector clearly desires lots of thermal energy. However, some steam applications square measure still stunning; a decent example is potato process.

2. Breweries

Most people apprehend that a decent and attractive Breweries consists of hops, malt and water. However, before enjoying the Breweries there’s a posh production method. Malt must be ground coarsely and mixed with water. The brewer calls this mashing. The mash should be heated to numerous temperatures in 2 to four hours. Steam generated with the vessel is generally used as a heat carrier. after, hops square measure else and also the mixture must relax. Then yeast is else and triggers the fermentation so the Breweries gets the specified result. once more when bottles or barrels are empty they’re unremarkable came to the still. in fact the breweries initial got to clean them before they’ll be refilled. For this method steam is once more needed to heat up the water required for cleanup.

3. Building materials Plant

Large amounts of steam also are necessary for the assembly of formed bricks. the fundamental materials like sand, lime, water, etc. square measure mixed and ironed to comparatively loose stone compounds. after, the stones square measure transported to an enormous pressure vessel (autoclave) that is then closed and steam is injected. The stones got to harden at a temperature of roughly two hundred °C and a pressure of regarding sixteen bar for a particular amount of your time and may then be withdrawn as finished stones.

4. Sewer pipe rehabilitation

What to try and do if there’s a drain leakage? This draw back will either be solved by means that of excavation works at the underground pipes and renewal of the waste product pipe systems or with rehabilitation tubes. These tubes square measure over dimension hoses that square measure inserted within the pipes while not excavation work so inflated with steam. The plastic hose attaches itself to the waste product pipe below application of pressure and temperature and also the pipe will still be used for several years.

Many different Industries uses of type boiler like :

• Power Sector
• Textiles
• Plywood
• Food process Plant
• F.M.C.G.
• Sugar Plants, etc