Quantcast Chapter 1 Boilers

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 
CHAPTER 1 BOILERS Learning  Objectives:  Describe  the  principles  and  theory  of  steam  generation. Identify  different  types  of  boilers  and  the  design  requirements  for  boilers.  Describe the purpose and operation of the different types of boilers and their fittings and accessories. Describe the methods and procedures for the testing and treatment of boiler water. Describe methods and procedures involved in fireside and waterside cleaning. A  boiler  is  an  enclosed  vessel  in  which  water  is heated and circulated, either as hot water or steam, to produce  a  source  for  either  heat  or  power.  A  central heating  plant  may  have  one  or  more  boilers  that  use gas, oil, or coal as fuel. The steam generated is used to heat  buildings,  provide  hot  water,  and  provide  steam for   cleaning,   sterilizing,  cooking,  and  laundering operations. Small package boilers also provide steam and hot water for small buildings. A   careful   study   of   this   chapter   can   help   you acquire  useful  knowledge  of  steam  generation,  types of   boilers   pertinent   to   Seabee   operations,   various fittings  commonly  found  on  boilers,  and  so  on.  The primary  objective  of  this  chapter  is  to  lay  the foundation  for  you  to  develop  skill  in  the  operation, maintenance, and repair of boilers. STEAM  GENERATION  THEORY Learning  Objective: Describe  the  principles  and theory of steam generation. To  acquaint  you  with  some  of  the  fundamentals underlying  the  process  of  steam  operation,  suppose that you set an open pan of water on the stove and turn on  the  heat.  You  find  that  the  heat  causes  the temperature of the water to increase and, at the same time,  to  expand  in  volume.  When  the  temperature reaches the BOILING POINT (212°F or 100°C at sea level). a physical change occurs in the water; the water starts vaporizing. When you hold the temperature at the boiling  point  long  enough,  the  water  continues  to vaporize until the pan is dry. A point to remember is that THE  TEMPERATURE  OF  WATER  DOES  NOT INCREASE BEYOND THE BOILING POINT. Even if you add more heat after the water starts to boil, the water 1-1 cannot get any hotter as long as it remains at the same pressure. Now suppose you place a tightly fitting lid on the pan of  boiling  water.  The  lid  prevents  the  steam  from escaping from the pan and this results in a buildup of pressure inside the container. However, when you make an opening in the lid, the steam escapes at the same rate it is generated. As long as water remains in the pan and as long as the pressure remains constant, the temperature of the water and steam remains constant and equal. The steam boiler operates on the same basic principle as  a  closed  container  of  boiling  water.  By  way  of comparison, it is as true with the boiler as with the closed container that steam formed during boiling tends to push against the water and sides of the vessel. Because of this downward  pressure  on  the  surface  of  the  water,  a temperature in excess of 212°F is required for boiling. The higher temperature is obtained simply by increasing the  supply  of  heat;  therefore,  the  rules  you  should remember are as follows: 1. All of the water in a vessel, when held at the boiling point long enough, will change into steam. AS LONG  AS  THE  PRESSURE  IS  HELD  CONSTANT, THE   TEMPERATURE   OF   THE   STEAM   AND BOILING WATER REMAINS THE SAME. 2. AN INCREASE IN PRESSURE RESULTS IN AN   INCREASE   IN   THE   BOILING   POINT TEMPERATURE  OF  WATER. A handy formula with a couple of fixed factors will prove this theory. The square root of steam pressure multiplied  by  14  plus  198  will  give  you  the  steam temperature.    When you have 1 psig of steam pressure, the square root is one times 14 plus 198 which equals 212°F which is the temperature that the water will boil at 1 psig.



Construction News
 


Privacy Statement - Copyright Information. - Contact Us

comments powered by Disqus

Integrated Publishing, Inc.
9438 US Hwy 19N #311 Port Richey, FL 34668

Phone For Parts Inquiries: (727) 755-3260
Google +