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31 Jul 2014

Types of boilers

There is no specific way in which you can classify a boiler but according to the little knowledge we have classified boilers into seven main classes


Classification base upon


  • Orientation of the shell
  • Utility of the boilers
  • Heating system
  • Tube content
  • Type of fuel
  • Circulation method
  • Way of heating

According to the Orientation of the shell

Base upon the orientation of the shell with respect to ground boiler can be classified into three types
  • Vertical boilers
  • Horizontal boilers
  • Inclined boilers

According to the Utility of the boilers

Base upon the Utility boilers can be classified into two main types
  • Stationary boilers
  • Portable boilers

According to the Heating system

According to the place from which liquid in the boiler is heated, boilers are classified into two main types
  • Externally fired boilers
  • Internally fired boilers

According to the Tube content

According to the type of fluid inside the tube, boilers are classified into two main types
  • Fires tube boilers
  • Water tube Boilers

According to the Type of fuel

According to the type of fuel used by the boilers to heat the fluid they are classified into three main types
  • Solid fuel boilers
  • Liquid fuel boilers
  • Gas fuel boilers

According to fluid Circulation method

According to the source by which fluid moves from the boiler they are classified into two main types
  • Free circulation boilers
  • forces circulation boilers

According to the Way of heating

According to the way in which fluid inside the boiler is heated they are classified into three main types
  • fired boilers
  • Unfired boilers
  • Supplementary fired boilers



23 Jul 2014

Flash and Double flash geothermal power plant



Flash and double flash geothermal power plant make use of the water that is between 300 to 700 F. Flash and double flash is the name given to this power plant because of its working phenomena


Parts of the Flash and Double flash geothermal power plant


Geothermal vent

A deep well is drilled into the surface of the well to extract hot water from the geothermal source called geothermal vent

Steam tank

Water from the geothermal source is taken into the tank where some of it is converted into the steam and some into the boiling water.

High pressure separator

Steam tank have boiling water and high pressure steam together at same place. High pressure separator separates the steam from the water and forwards the steam to the turbine and water toward low pressure separator

Low pressure separator

Boiling water from the high pressure separator in move to the low pressure separator after passing through the throttling valve. Low pressure separator separates the low pressure steam from the boiling water

Turbine

Steam turbines are used to produce the electricity from steam. Steam are introduce at two points, high pressure steam is introduce at first stage and low pressure steam is introduce at few stages back from the first stage

Condense

Steam which passes from the turbine is still at very high pressure and that pressure is reduce by condenser and steam is converted into the water.


Working of Flash and Double flash geothermal power plant


Hot water from geothermal source is taken to the steam tank where reduce is pressure result into production of the boiling water and high pressure steam. Now high pressure separator separates the steam and water, steam moves toward the turbine and water moves toward low pressure separator. Before low pressure separator there is a throttle valve which increase the pressure of the water and low pressure separates the low pressure steam and water, steam moves toward the turbine and water towards the reinjection pump. Low pressure steam in injected after the few stages from the first stages of the steam turbine because of its low pressure. 



20 Jul 2014

Binary cycle Geothermal Power Plant




Binary cycle is the type of geothermal power plant which works with the water having the temperature below 400 F and uses the concept of heat exchanger to transfer the heat of hot water to relatively low boiling liquid, which then converted into vapor face. This high pressure vapors then used by the turbine to produce the electricity


Parts of Binary cycle Geothermal Power Plant

Geothermal vent

It is a deep drilled hole which starts from the surface of the earth and end at the geothermal source. High pressure superheated water moves from the source towards the surface through the pipes.

Heat exchanger

This part of the Binary cycle Geothermal Power Plant differentiates it from the other types of the geothermal power plants. Heat exchanger is the device which exchanges the heat between two liquids flowing in different pipes at different temperature.

Turbine

Turbine is the part which converts the pressure energy of the fluid into the kinetic energy. Rotating turbine is used to rotate the generator to produce the electricity.

Generator

Generator is the electrical device use to convert the rotation motion of the turbine onto the electrical energy

Condenser

High pressure liquid after passing through the turbine moves into the condenser where its pressure is released and it is converted into normal liquid form


Working of Binary cycle Geothermal Power Plant

Water at temperature below 400 F is taken from the geothermal source and passes through the heat exchanger where its heat is transfer to a relatively low boiling liquid. Low boiling liquid when absorb heat get vaporized and establish more pressure than water at the same temperature. After heat exchanger water moves back into the ground whereas low boiling liquid moves toward the turbine in the vapor face at high pressure. Turbine blades convert the pressure energy of the liquid into the rotation motion of the turbine and rotation motion of the turbine is converted into electrical energy by the electric generator. Liquid then moves into the condenser where its pressure is released and it can be used again.


Advantages of Binary cycle Geothermal Power Plant

  • Low initial cast than other types because it has lesser parts than other types
  • Zero eliminations because it’s a closed cycle process
  • Most geothermal resources are moderate temperature so this process is most widely used.
  • Safer than all other types




16 Jul 2014

Direct dry steam geothermal power plant





Oldest type of the geothermal power plant which uses the steam taken directly from the geothermal source it is the simplest and the most efficient type of geothermal power plant


Parts of direct dry steam geothermal power plant

Geothermal vent

Geothermal vent is a well drilled from the surface of the earth to the geothermal source to extract the steam energy from their up to the turbine of the geothermal power plant.

Steam tank

Steam from the geothermal source is first introduce into the tank where hot water is converted into the steam therefor it is also called steam tank

Separator

After the steam tank there is a separator which removes all the unwanted particles from the steam which could damage the turbine.

Turbine

After the separator steam strike the turbine which convert the pressure energy into the kinetic energy of the generator

Generator

Rotation energy transfer by the turbine to the generator is used by the generator to produce the electricity.

Condenser

Steam after passing through the turbine is transfer to the condenser where it is cooled and then return to the core of the earth.


Working of the direct dry steam geothermal power plant

A deep well is drilled into the earth up to the geothermal source. Super-heated water moves up through the pipes into the tank where water is converted into the steam and that steam is then passes through the separator and moves toward the turbine where high pressure of the steam is converted in to rotation motion of the turbine by the blades of the turbine. Turbine is connected to the generator which converts the rotation motion into the electricity.



7 Jul 2014

Investment Casting (Lost Wax Process)


Investment casting is expandable mold metal casting process which is also known as lost wax process because the pattern is made up of wax and is melted away when it is heated. Wax is recovered and can be used again and again that’s why this process is called investment casting process.


Steps involve in investment casting

Step 1 

First and most unique step is the making of the patter which is of wax. A few number of pattern are attached to the wax sprue





Step 2

Pattern attached to wax sprue is then fully dipped in the refractory material tank so that it is fully covered by the refractory material. It is them drayed to make it rigid





Step 3 

Pattern is now inverted and heated to remove the wax from it. After the removal of the wax patter is now hollow from inside and metal can be poured in it




Step 4

To remove all the contaminants from the mold it is heated at very high temperature and them hot molten metal is poured into it and then kept for a long time for cooling





Step 5

After the metal is cooled refractory material is removed and pattern is removed from the metal sprue






Advantages of investment casting


  • Complex parts can be manufactured
  • High dimensional control
  • Good surface finish
  • Wax is recovered
  • No machining is required
  • Net shape process




Disadvantages of investment casting


  • Take more time than other processes
  • Expansive than other processes


Shell Molding




Shell molding is the expandable mold metal casting process in which mold is a thin shell of sand held together by the binder usually a thermosetting resin. It was invented by the German in about 1940s. Thickness of the shell mold is about 9 mm


Steps involves in Shell molding


Step 1

A metal plate is used to make the pattern. Shape of the patter is like the shape of shell mold you need. Metal plate is heated and they fixed on a container containing the sand and the thermosetting resign.




Step 2

Container is inverted so that the sand and thermosetting resign may came into contact with each other. Heated plate melts the resign and makes a shell of sand around the pattern.




Step 3

In order to remove the extra sand and uncured resign container is reposition again and plate is detached from it




Step 4

Shell made is not properly cured yet so it is heated in a heater for proper curing.




Step 5

After proper curing shell mold is removed from the patter.





Step 6

Same process is preformed to make the other half of the mold and then both halves are attached in a box and supported by the sand. Molten metal is poured.





Step 7

Finish metal product is removed from the shell mold 





Advantages of shell molding


  • Smother surface of the mold, 
  • Ease for the molten metal to flow. 
  • Good dimensional accuracy. 
  • Machining is not required.  
  • Usually no cracks in casting. 
  • Mechanizing for mass production gives good results




Disadvantages of Shell Molding


  • Most expansive metal pattern. 
  • Takes more time.  
  • Not suitable for small production




3 Jul 2014

Advantages and Disadvantages of Reciprocating Pump



Following are the advantages and disadvantages of reciprocating pump


Advantages of reciprocating pump


  • High efficiency
  • No priming needed
  • Can deliver water at high pressure
  • Can work in wide pressure range
  • Continuous rate of discharge


Disadvantages of reciprocating pump

  • More parts mean high initial cost
  • High maintenance cost
  • No uniform torque
  • Low discharging capacity
  • Pulsating flow
  • Difficult to pump viscous fluid
  • High wear in parts

Working of Reciprocating Pump




As we have discuss classification of reciprocating pump is our last post and now we will discuss the working of two basic types of reciprocating, single and double acting reciprocating pump.



Working of Single acting reciprocating pump



Suction

Let us suppose that the pump piston is at the inner dead centre and the crank start to rotate in the clock wise direction. As the crank start to rotate piston start to move toward the outer dead centre. As the piston moves back vacuum is created and force the suction valve to open and suck up the water from the sump into the cylinder of the pump




Delivery

Now after the suction process is complete, piston of the pump is at the outer dead centre. As crank continuou to rotate the piston of the pump is now force to move toward the inner dead centre and in doing so piston force the water and creates the pressure inside the pump and as the pressure reached a specific value delivery valve is open and water is transfer to the tank.



Working of Double acting reciprocating pump



Piston moving in right direction

let us suppose that the piston is initially at the centre of the cylinder and crank start to rotate on clock wise direction so the piston will move toward the right side and thus vacuume is created at left side of the piston and pressure is created at the right side of the piston. Vacuum at left side force the water to move into the cylinder from the sump and pressure at the right force the water to move up from the delivery pipe in to the tank




Piston moving in left direction

As the crank continuou to rotate, piston after reaching at one end now moves is left direction and so pressure is created at the left side of the piston and vacuum is created on the right side of the pump. Vacuum cause the water to move up in the pump and pressure cause the water in pump to move into the tank.

2 Jul 2014

Components of Reciprocating Pump



Components of reciprocating pump with their details are as follow


Crank

Crank is a circular disk attached to the motor and used to transfer the rotation motion of the motor to the piston



Connecting rod

Connecting rod is the long solid rod. It provide connection between crank and the piston. It also convert the rotation motion of crank into the linear motion of the piston.



Piston  

Piston is the solid cylinder like part of the pump which moves linearly in the hollow cylinder of the pump. It motion is main reason behind suction and deliverance of the liquid



Cylinder

It is a hollow cylinder in which piston moves. Suction and deliverance take place with in it. Suction and delivery pipe and valves are attached to its one end piston come and go back from other end.



Suction pipe

Pipe which take liquid from the source and provide it to the cylinder of the pump  is called suction pump



Suction valve

It is one way valve place between suction pipe and cylinder of the pump. It is open when suction take place and close when delivery of the water is taking place



Delivery pipe

Pipe which take water from the cylinder of the pump and provide it to the tank is called delivery  pipe.



Delivery valve

It is one away vale and placed at the point of attachment of delivery pipe with cylinder. It is open when delivery of water is taking place and closed when suction of water in taking place



Strainer

It is a filter like parts provided at the end of suction pipe. Its main function is to stop is solid particles from entering into the pipe



Air vessel

Installed at the suction and delivery pipe and its main function is to give a steady flow by reducing the frictional head 



Classification of Reciprocating Pump



Follow are the three fields in which the reciprocating are classified

1. According to the contact between water and plunger
2. According to the number of cylinders
3. According to the air vessel



According to the contact between water and plunger

Single acting pump

A single acting pump is one which has one suction valve, delivery valve and one suction and delivery pipe. It suck up the fluid only in one direction and in single stroke called  suction stroke and deliver it in a single stroke called delivery stroke





Double acting pump

A double acting pump is one which has two suction valves, delivery valves and two suction and delivery pipes. If we suppose that piston is in the center of the cylinder then one suction and delivery pipe is on one side and one delivery and suction pipe is on other side of the piston.





According to the number of cylinders

1. Single cylinder pump

Single cylinder pump is one in which their is only cylinder connected to a single shaft. It could be a single acting or double acting pump.


2. Double cylinder pump

Double cylinder pump is one which have two cylinder attached to a single shaft.Separate suction and delivery valve is provided to each cylinder.Crank of the pump is set at an angle of 180 


3. Triple cylinder pump

When the pump has three cylinders attached to a single shaft then the pump is called triple cylinder pump. Crank is set at an angle of 120



According to the air vessel

1. With air vessel

Some reciprocating pump are provided with a separate air vessel attache to the suction and delivery valve. Its main function is to accumulate excess quantity of water by compressing the air in the vessel


2. With out Air vessel

Some pump lack the air vessel because of the nature of their work. for example the reciprocating boiler feed pumps does not have air vessel because they may introduce air into the deaerated water