BOILER-BASICS by linzhengnd

VIEWS: 18 PAGES: 13

									                                                         “Right step of Maintenance is the SOUL™ of efficiency”
An ISO 900:2008 Certified Comp.



                                                         BOILER-BASICS
                   What is a Boiler?
                       Boiler, also called STEAM GENERATOR, is an apparatus designed to convert a liquid to vapor.
                   In a conventional steam power plant, a boiler consists of a furnace in which fuel is burned, surfaces
                   to transmit heat from the combustion products to the water, and a space where steam can form and
                   collect. A conventional boiler has a furnace that burns a fossil fuel or, in some installations, waste
                   fuels. A nuclear reactor can also serve as a source of heat for generating steam under pressure.

                       Boilers were built as early as the 1st century AD by Hero of Alexandria but were used only as
                   toys. Not until the 17th century was serious consideration given to the potential of steam power for
                   practical work. Denis Papin of France designed the first boiler with a safety valve in 1679; boilers
                   were made of wrought iron; as the advantages of high pressure and temperature were realized,
                   manufactures turned to steel. Modern boilers are made of alloy steel to withstand high pressures and
                   extremely high temperatures.

                   Most conventional steam boilers are classed as either fire-tube or water tube types. In the fire-tube
                   type, the water surrounds the steel tubes through which hot gases from the furnace flow. The steam
                   generated collects above the water level in a cylindrically shaped drum. A safety valve is set to allow
                   escape of steam at pressures above normal operating pressure; this device is necessary on all boilers,
                   because continued addition of heat to water in a closed vessel without means of steam escape result
                   in a rise in pressure and ultimately, in explosion of the boiler. Fire-tube boilers have the advantage of
                   being easy to install and operate. They are widely used in small installations to heat buildings and to
                   provide power for factory processes. Fire-tube boilers are also used in steam locomotives.

                   In the water tube boiler, the water is inside tubes with the hot furnace gases circulating outside the
                   tubes. When the steam turbo generator was developed early in the 20th century, modern water tube
                   boilers were developed in response to the demand for large quantities of steam at pressures and
                   temperatures far exceeding those possible with fire-tube boilers. The tubes are outside the steam
                   drum, Which has no heating surface and is much smaller than in the fire-tube boiler. For this reason,
                   the drum of the water tube boiler is better able to withstand higher pressures and temperatures. A
                   wide variety of sizes and designs of water tube boilers are used in ships and factories. The express
                   boiler is designed with small water tubes for quick generation of steam. The flash boiler may not
                   require a steam drum, because the tubes operate at such high temperatures that the feed water flashes
                   into steam and superheats before leaving the tubes. The largest units are found in the central-station
                   power plants of public utilities. Units of substantial size are used in steel mills, paper mils, oil
                   refineries, chemical plants, and other large manufacturing plants.




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                   What is combustion?
                        The process of combustion is a high speed, high temperature chemical reaction. It is the rapid
                   union of an element or a compound with oxygen that results in the production of heat-essentially; it
                   is a controlled explosion.

                       Combustion occurs when the elements in a fuel combine with oxygen top produce heat. All
                   fuels, whether they are solid, liquid or in gaseous form, consist primarily of compounds of carbon
                   and hydrogen called hydrocarbons. Sulfur is also present in these fuels.

                   What are the products of combustion?
                      When the hydrogen and oxygen combine, intense heat and water vapor is formed. When carbon
                   and oxygen combine, intense heat and the compounds of carbon monoxide or carbon dioxide are
                   formed. When sulfur and oxygen combines, sulfur dioxide and heat are formed.

                   These chemical reactions take place in a furnace during the burning of fuel, provided there is
                   sufficient air (oxygen) to completely burn the fuel. Very little of the released carbon is actually
                   “consumed” in the combustion reaction because flame temperature seldom reaches the vaporization
                   point of carbon. Most of it combines with oxygen to form CO2and passes out the vent. Carbon,
                   which cools before it can combine with oxygen to form CO2, passes out the vent as visible smoke.
                   The intense yellow color of an oil flame is largely caused by incandescent carbon particles.

                   Is the combustion process 100% efficient?
                       Combustion can never be 100% efficient. All fuels contain some moisture and noncombustible:

                   •      Top-quality coal is 20% noncombustible.
                   •      Residual oil is 10% noncombustible.
                   •      Natural gas is 6% noncombustible.

                   What are the various types of combustion?
                     There are three types of combustion:

                   •      Perfect
                   •      Complete
                   •      Incomplete

                        Perfect combustion is achieved when all the fuel is burned suing only the theoretical amount of
                   air, But as we said before perfect combustion cannot be achieved in a boiler.

                       Complete Combustion is achieved when all the fuel is burned using the minimal amount of air
                   above the theoretical amount of air needed to burn the furl. Complete combustion is always our goal.
                   With complete combustion, the fuel is burned at the highest combustion efficiency with low
                   pollution.
                      Incomplete Combustion occurs when all the fuel s not burned, which result in the formation of
                   soot and smoke.

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                   What is the air requirement for combustion?
                       Oxygen for combustion is obtained from the atmosphere, which is about 21% oxygen by volume
                   or 23% by weight. About 2000 cubic feet of are is required to burn one gallon of fuel oil at 80%
                   efficiency to sea level. About 15 cubic feet of air is required to burn one cubic foot or natural gas at
                   75% at sea level. Stated another way:

                       A 100 HP boiler requires 75,000 ft3 of fresh air per hour for combustion to take place. Most of
                   the 79% of air that is not oxygen is nitrogen, with traces of other elements.

                   Nitrogen is inert at ordinary flame temperature and forms few compounds as the result of
                   combustion. Nitrogen is an unwanted “parasite” that must be accepted in order to obtain the oxygen.
                   It contributes nothing to combustion, it increases the volume of combustion products to be vented,
                   and it steals heat from the reaction and now creates a growing environmental problems as well.


                   What is primary air?
                      Primary Air controls the rate of combustion, which determines the amount of fuel that can be
                   burned.

                   What is secondary air?
                   Secondary Air controls combustion efficiency by controlling how completely the fuel is burned.

                   What is excess air in combustion?
                       Excess Air is air supplied to the burner that exceeds the theoretical amount needed to burn the
                   fuel.

                   How does the composition of fuel used influence the combustion air requirements?
                       Combustion air requirements are based on the composition of the fuel used. Fuels commonly
                   used contain nitrogen, ash, oxygen, sulfur, carbon and hydrogen. When a fuel has a large volume of
                   nitrogen that must be accepted along with desired oxygen, more excess air must be provided. That
                   excess air has a chilling effect on the flame. Some fuel particles fail to combine with oxygen and
                   pass out of the vent unburned. Water vapor is a by-product of burning hydrogen. It too subtracts heat
                   from the flame and becomes steam at flue gas temperature, passing out of the vent as vapor mixed
                   with the combustion products.

                      Natural gas contains more hydrogen and less carbon per unit of heat content than oil and
                   consequently its combustion produces a great deal more water vapor, Which withdraws a greater
                   amount of heat from the flame. Therefore gas efficiency is always slightly less than oil efficiency.

                       Air requirements for combustion are generally expressed in cubic feet air per gallon of oil or per
                   cubic foot of gas for convenience because fans, ducts and other air moving devices are rated incubi
                   feet per minute or cubic feet per hour. The Fuel/Air Ratio for combustion is actually a weight ratio
                   based on the required weight of oxygen for a given weight of fuel.



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                   Does the altitude affect the air required for combustion?
                              At sea level or at altitudes up to 3000 feet, the weight of oxygen per cubic foot of air does
                   not vary sufficiently to create major problems. At higher altitudes, air density has to taken into
                   consideration. At 5000 feet above sea level, air has approximately 4/5 of its weight at sea level,
                   therefore about 20% more air by volume must be introduced to obtain the required oxygen for
                   combustion. Fuel gas obeys the same Physical laws as air-at 5000 feet above sea level 20% greater
                   gas volume is required to obtain sea level weight of combustibles. A gallon of fuel oil has the same
                   weight at any altitude and no fuel-input increase is necessary.

                   Boiler Design

                   What is the heat balance for a boiler?
                       Fuel fed to a burner is converted to heat. The heat is absorbed by the water in the boiler….but
                   not all the heat released from the fuel is used to heat the water. Some of the heat is wasted in the
                   process. The heat balance of a boiler consists of accounting for all the heat units in the fuel used or
                   wasted. It is a balance because it is the sum of all the heat consumed. Heat balance of a boiler is
                   found by using the following equation:

                   A=B+C
                   A= heat energy available in the fuel
                   B= heat energy absorbed any the water in the boiler
                   C= heat losses
                   Therefore:
                   Efficiency of the unit = B divided by A
                   What are the energy losses the occur in a boiler?
                     Gases of combustion to atmosphere (about 9%)
                     Incomplete combustion (about 1%)
                     Moisture in fuel (less than 1%)
                     Moisture in air used for combustion (less than 1%)
                     Water vapor produced from the burning of hydrogen (about 2%)
                     Unburned combustibles (about 2%)
                     Radiation (about3%)
                   Total heat losses in this examples equal 18-19% While some of these losses are preventable losses
                   over which the boiler operator has control, such as:

                       Heat carried away in the dry chimney gases
                       Incomplete combustion of the fuel
                       Unburned combustibles (about 2%)
                   Much of the resulting efficiency of a boiler is the result of its basic het transfer design. Boiler
                   designs that use all possible heat transfer surfaces to their fullest advantage consistently produce the
                   most efficient source of steam or hot water with the lowest total lifetime costs.

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An ISO 900:2008 Certified Comp.




                  What are the various heating surfaces in a boiler?
                      Regardless of how a boiler is constructed, it has only one purpose to transfer the heat, produced
                by burning fuel, to the water. Transfer of heat will occur through all of the metal surfaces, if they are
                exposed to heat on one side and have water on the other side. These surfaces are those that make up
                “boiler heating surface” calculations.

                            Heating surface is expressed in square feet and may be defined as:

                                   Radiant Heating Surface- (also called direct or primary) including all water-back surface
                            that are directly exposed to the radiant heat of the combustion flame.

                                  Converted Heating Surfaces – (also called indirect or secondary) including all those
                            water-backed surfaces exposed only to hot combustion gases.

                                  Extended Heating Surface – referring to the surface of economizers and super heaters
                            used in certain types of water tube boilers. This term is not used with fire tube boilers.

                What is a “pass” for a boiler?
                      Boilers are called “one-pass,” “two-pass,” “three-pass” or “four-pass,” according to the number
                of times the heat released in combustion is conducted through the boiler before the gases exit the vent.
                The furnace in which the combustion takes place is counted as one “pass,” If the tubes are arranged so
                that they are actually an extension of the combustion chamber, as in a vertical tube unit, then they are
                not considered as a separate pass and the unit is then called a “one pass” boiler.

                      If the tubes are arranged so that the combustion gases must make a 1800 turn to enter them, then
                each group of flue passages requiring a reversal of gas direction is referred to as a separate “pass.” For
                examples: a three-pass boiler consists of a furnace (first pass) from which the gases exit with a 1800
                turn in to a course of flue tubes (second pass) from which they exit with a 1800 turn into another
                course of flue tubes (third pass) before exiting into the vent.

                How are boilers rated?
                     Commercial boiler ratings may be stated in several ways, but are always directly related to the
                amount of heat that will be produced when the boiler is fired ar a specified fuel input under specified
                conditions.

                      The basic factor governing boiler output is the rate of heat release that can be maintained in the
                furnace as determined by the type of firing equipment used:
                      The heat release rate of a boiler is an expression of the rate at which the combustion of the fuel
                liberates heat energy based on the fuel input in Joules per hour. Heat release rate may be defined as
                either Joules per hour per cubic meter of furnace volume or as Joules per hour square meter of radiant
                heating surface. Gross output rating is the total amount of heat available at the boiler outlet for a
                specific fuel input. Gross output is usually expressed in:


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                      Thousand of Joules per hour (KJ)
                      Boiler Horsepower (BHP)
                      Kilograms of steam per hour

                One boiler horsepower is defined as the evaporation of 15.7 Kilograms of water at 1000 C into steam
                1000 C. At 0 gauge pressure, or 1000 C heat of the vaporization of steam is 2252 KJ/Kg. Therefore:
                One Boiler Horsepower is equal to 35356 KJ

                Note: In order to avoid combustion, the gross output for any steam pressure s always shown at the
                standard condition “from and at 1000C.” Although more heat input per kilogram of steam is actually
                required as steam pressure increases, the work equivalent per kilogram of steam also increases as
                steam pressure increases, so the rating stated at “standard” condition are valid regardless of the
                pressure at which the boiler is operated.

                Which boiler designs are more common?
                      Fire tube Boiler- Here the combustion products from the burning fuel are conducted to the boiler
                flue outlet through flue passages (tubes) that are surrounded by water. The tubes may be arranged
                horizontally or vertically above the furnace. Sometimes baffles to tabulators are inserted in the tubes to
                control gas velocity and improve the heat transfer by forcing the hot gases into more intimate contact
                with the tube walls.

                     Water tube Boiler- Here the hot combustion gases are directed over the tunes in which the boiler
                water circulates. Metal or refractory baffles direct the gas flow to improve heat transfer.

                Hoe do I select a boiler?
                     There are five points of concern that should be applied when selecting the appropriate boiler
                design for a specific installation. They are:

                          System Type: Steam or Hot Water
                          System Load
                          Performance Considerations
                          Codes and standards

                             The two system types encountered are steam and hot water systems. Steam and hot water
                             boilers for these systems are defined according to design pressure and operating pressure.

                      Design pressure is the maximum pressure used in the design of the boiler for purpose of
                calculating the minimum permissible thickness or physical characteristics of the pressure vessel part of
                the boiler. Typically, the safety relief valves are set at or below design pressure. Operating pressure is
                the pressure of the boiler at which it normally operates. The operating pressure is set at a suitable level
                below the setting of the pressure relieving valves to prevent their frequent opening during normal
                operation.



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                 Steam boilers are designed for low pressure of high-pressure application. Low-pressure boilers are
                limited to 15-psig design and are typically used for heating applications only. High-pressure boilers
                have operating pressures typically from 75 psig to 300 psig and are typically used for process loads
                and/or heating requirements.

                      Hot water boilers are commonly used for heating applications with the boilers supplying water to
                the system at 820C to 1040 C. Typical operating pressures for these systems are from 30 psig to 125
                psig. If a system requires hot water of more than 1160 C, a high temperature water boiler should be
                used.

                What is a system Load?
                     System Load is measured in either KJ or Kilograms of Steam(at a specific pressure and
                temperature). To determine system load, you will need to know the following information:

                      Heating Load
                      Process Load
                      Combination Load

                      A Heating Load is typically low-pressure steam or hot water and s relatively easy to define. The
                      Heating load will include large seasonal variations but no large instantaneous demand changes. A
                      heating boiler should be sized to the worst probable weather conditions, which means that true
                      capacity will rarely be reached. Once a heating load is computed, the number can easily be
                      transferred into equipment size requirements.

                      A process Load is usually a high-pressure steam application pertaining to manufacturing
                processes where heat from either steam or hot water is used in the process. A process load can be
                further defined as continuous or batch load.

                      Continuous load is defined as a load that is fairly constant, very much like a heating load. Batch
                loads are loads characterized by short-term demands or the M.I.D. factor. Due to the fact that a very
                large instantaneous demand can be several times larger than the rating of the boiler, very careful boiler
                selection should take place in such process load situations.

                      Many facilities have combination loads with a mixture of different types of processes and
                heating. The information given above should be taken into consideration in an additive manner when
                you encounter such situations.

                      Loads vary and a boiler must be capable of handing the minimum load, the maximum load and
                all the load variations in between. These variations fall into three basic types:

                          Seasonal Variations
                          Daily Variations
                          M.I.D. Variations



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                      To accurately determine the load of any system. Load tracking is recommended. The ability of a
                boiler to answer variable load demands depends on the boiler type, feed water valve control and
                combustion controls. If the analysis of a load show a highly variable situation, a more complex control
                package may be required. Below is an illustration of a load tracking collection form.

                Minimum                              Average                               Maximum

                Heating Load 1                       -                                     -
                Heating Load 2                       -                                     -
                Heating Load 3                       -                                     -
                Total Heating Load                   -                                     -
                Process load 1                       -                                     -
                Process load 2                       -                                     -
                Total Process Load                   -                                     -
                Instantaneous                        -                                     -
                Load                                 -                                     -
                Total Load                           -                                     -

                Utilize a load demand matrix to analyze each load and determine minimum, average, and maximum
                load requirements.

                What are the considerations in selecting the ideal number of boilers?
                    The important criteria in selecting the ideal number of boilers are:

                          Need for back-up boilers
                          Load Type
                          Downtime

                      When selecting boiler consideration should be given to future expansion, emergency repairs
                and maintenance situations.

                      Often, especially in a heating/process mixed load situation, a section of a large “winter” boiler
                and a smaller “summer” boiler will provide the best and most cost effective solution when measured
                on a lowest yearly operating cost basis.




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                What are the performance considerations in selecting a boiler?
                      Untreated or raw water is never pure. Water contain varying amounts of gases, solids and
                pollutants. Water in the form of rain absorbs gases from the air asit falls to the ground. As it absorbs
                into and seeps downward through the ground it picks up even more chemicals and minerals. By the
                time the water is pumped up from its ground source and delivered to our faucet. It is loaded with salts,
                dissolved gases and inorganic compounds.

                      Common impurities that can affect physical plant operations are listed below.
                Common Water
                Impurities
                Impurity                  Source                         Effect
                Algae                     Organic growth                 Fouling
                Calcium                   Mineral deposits               Scale
                Carbon dioxide            dissolve gases                 Corrosion
                Chloride                  mineral deposits               Corrosion
                Free acids                industrial waste               Corrosion
                Hardness                  mineral deposits               Scale
                Magnesium                 mineral deposits               Scale
                Oxygen                    dissolved gases                Corrosion
                Silica                    Mineral deposits               Scale
                Solids                    Undissolved material           Fouling

                What are the major problems associated with water quality and equipment?

                          The five major problems associated with water quality and equipment problems are:

                                  Scale Formation
                                  Corrosion
                                  Fouling
                                  Foaming
                                  Embitterment
                          Scale is an extremely hard substance created when mineral salts come out of solution as their
                          solubility drops with a rise in water temperature. Scale –forming salts adhere directly to heating
                          surfaces forming layers of insulation on the metal substantially decreasing its heat transfer
                          efficiency.

                          Corrosion occurs when metals (by acid or electrolytic action) attack metals. The metals is eaten
                          away similar to the generalized rusting of an automobile fender. Corrosion increases
                          maintenance costs, results in premature replacement of equipment and causes unnecessary safety
                          risks. Corrosion occurs where levels of oxygen or carbon dioxide are high, where pH values are
                          low, where contact occurs between dissimilar metals and in damp environments or corrosive
                          atmospheres. Fouling occurs when restriction develops in piping and equipment passages,
                          creating inefficient water flow. The major consequences of fouling to boiler room equipment are
                          energy waste and increased operating/ maintenance costs.


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                      When fouling is allowed to continue and proliferate in a system, cooling towers, heat exchangers
                and other critical devices could give rise to the emergence of health-related issues such a Legionnaires
                Disease. Foaming is a condition in which concentrations of soluble salts (aggravated by grease,
                suspended solids or organic material) create frothy bubbles (resembling the foam in a beer mug) in the
                steam space of a boiler. Foaming can cause priming- in which the bubbles break and create a liquid
                that combines to form slugs of water that are carried over into the steam system. Pressure from the
                steam can create velocities as high as 125-160 km per hour for slugs of water discharged into steam
                lines. These slugs can wreak havoc with turbine blades, actuating devices and piping downstream of
                the boiler. Caustic Embitterment occurs when hairline crakes appear in highly stressed areas due to
                high concentrations of alkaline salts that liberate hydrogen, which is then absorbed by the iron in steel,
                effectively changing its physical properties. This condition is caused largely by boiler water with pH
                values 11 + and manifests itself in high-temperature areas of the boiler.

                      Unless Embitterment problems are constantly monitored and controlled, they will take their toll
                in higher fuel costs, increased safety risks, unnecessary downtime and equipment replacement.

                How do I improve the input water quality for my boiler?
                    There are three tools that can be used to improve water quality:

                                Internal Treatment- conditioning the water to pre-determined levels by using a variety of
                          chemicals.
                                Demineralization- the replacement of specific inorganic salts by ion exchange.
                                Desecration- the removal of dissolved oxygen and carbon dioxide by heating and
                          bombarding the water with steam.

                While demineralization and desecration can be accomplished easily by investment in the appropriate
                support equipment, internal treatment calls for a more concerted effort. However, most organizations
                large enough to have in-house maintenance will find that the combination of these three tools will
                more than pay for themselves in defrayed operating costs. By-products of a well-implemented
                program are:
                             Increased Heat Transfer
                             Lower Fuel Expenditures
                             Lower Chemical Consumption
                Expected for steam trap maintenance, water treatment has the most potential for reducing annual
                operating costs of your power plant.

                What is meant by chemical treatment for water? Is chemical treatment the cheapest way to treat
                the input water?
                      Some people consider chemical treatment to be the least expensive and only necessary water
                treatment program for their system. They often feel that way because the relatively “small” amounts of
                money spent consistently “seems” like less of an investment than equipment first costs.

                     While chemical treatment is a necessary part of water treatment it is almost never the cheapest or
                most effective single way. For most systems, the best possible cost/benefit ratio will come from a
                balanced equipment/chemical treatment approach.

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                     Chemical treatment is simply thee addition of chemicals to the feed water to accomplish one of
                two things:

                          To cause compounds to stay in solution to be removed by continuous or surface blow down.
                          To cause compounds to precipitate out of solution to be removed by bottom blow down.

                     Chemical treatment programs that are mot accompanied by effective blow down monitoring are
                one of the leading causes of excessive boiler operating inefficiencies and/or failure.

                     Most organizations with an in house staff will be able to perform water treatment duties
                themselves. Maintenance departments that don’t have the in-house time or expertise ought to consider
                contracting these duties out to a reputable vendor.

                How do I maintain optimum efficiency of my system?

                          What is required to insure that your system is operating as its optimum efficiency is a staff or
                          vendor who can regularly perform the following functions:

                                  Will be familiar with all of your water treatment/boiler room equipment and its frequency
                          of operation.
                                  Will keep a written analysis of yur water, indicating constituents found and in what
                          amounts.
                                  Will regularly test your water and log results.
                                  Will interpret results of in- house tests and make appropriate corrections to your
                          treatment program.
                                  Will establish parameters for the use of chemicals and method for introduction/removal
                          for the system.
                                  Will see to it that equipment is fed, bled and blown down as per equipment
                          manufacturer’s instructions.
                                  Will perform regular inspection of all equipment.
                                  Will establish chemical inventory and reorder points.
                                  Will do all of the above on a regular basis.
                Which equipment is necessary to support a water treatment program for an open steam system?
                           Chemical Feed System
                           Water Softener system
                           Bottom and/or Surface Blow down
                           Boiler Feed water System or Deaerator System
                           Condensate Return System

                          Chemicals Feed is an important part of even the smallest physical plant. This equipment enables
                          you to “feed” the appropriar\te amounts of chemicals into a system to protect equipment against
                          scaling and corrosion. These units usually consist of a tank, stand, pump, motor and agitator.
                          Wired so that the unit operates in conjunction with the feed water or deaerator unit in open steam
                          systems, this equipment insures that the chemical treatment of your water is consistently being


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                          fed with the smallest amount of chemical treatment required to provide your customer with
                          optimum treatment and payback results.

                       A water softener System is another investment that should be made no matter how large the
                facility you are dealing with. These units are available in a wide range of sizes for anything from a
                light commercial to a heavy industrial application.

                      Fed from a raw water source, it is the water softener that produces the conditioned water for a
                system up front that will reduce the undesirable minerals that produce detrimental scale on heat
                transfer surfaces. Use of water softener will also reduce the need for expensive chemical scale control
                additives. Blow down Systems eliminate the mineral build-up that causes boiler scale and corrosion.

                     Bottom blow down units forcibly remove the sludge, that is the result of a precipitating chemical
                program, from the bottom of the boiler.

                      A surface blow down/heat recovery unit produces an ongoing process that removes dissolved
                solids from the top level of water in the boiler while recovering a good deal of heat which is returned
                to the feed water at the same time.

                      As mentioned before: chemicals treatment is performed either to causes compounds to stay in
                solution to be removed by continuous or surface blow down or to cause compounds to precipitate out
                of solution to be removed by bottom blow down. Both systems work well to lower operating.

                      A feed water System is necessary to help maintain peak efficiency and prolong the life of the
                boiler where investment in a dearerator cannot be justified. A water feeding system of some type is
                necessary to make-up for the system loss of water.

                      These systems consist of a tank, stand, pumps, control panel and float device driven by demand
                of a feed water float switch located on the boiler. Feed water systems have the dual function of storing
                and returning hot condensate and supplying make-up water in combination to meet the water demands
                of the boiler. Condensate is water which has condensed from steam in the system. This is very
                valuable water both for its chemical and heat content.
                      Make-up is water that must be brought in to add to the condensate to equal the amount of water
                demanded by the boiler. Make-up should not be raw water that has already gone through a softening
                and filtering process for best results.

                     Often feed water systems come fitted with a pre-heater tube (often referred to a “spare tube”
                assembly) to function well as a “poor man’s deaerator” in some causes. Use of feed water systems also
                accounts for large fuel saving and lower chemical costs.

                      A Deaerator is a mechanical device designed to remove non-condensable gases from boiler feed
                water. Through a process of heating and bombarding water with steam, oxygen and carbon dioxide
                will cause pitting and corrosion- a rusting of the tubes from within and under the water. This is the
                major cause of boiler replacement.


                          BARON Chemicals & Systems (P) Ltd.
                          H-5/ 21, Krishna Nagar, Delhi-110051. Tel:011-22418572,22056393 Fax 91-11-22023200
                          Email: info@baronchemicals.com Web: www.baronchemicals.net
                                                         “Right step of Maintenance is the SOUL™ of efficiency”
An ISO 900:2008 Certified Comp.


                     Condensate Return units can be one of systems best cost/benefit investments. These are often
                simple devices consisting of a small rectangular steel or cast iron tank, pump and motor assemble and
                a float device to turn on the pump to move the condensate to a boiler feed water or deaerator.
                Capturing and reusing treated condensate will result in large energy and water treatment savings.
                Small tanks with small pumps are your best investment producing the best first costs and insuring tat
                condensate is returned to the system as quickly and as hot as possible.


                What procedures are recommended while starting the boiler for the first time?

                       Hot water systems are closed systems and are often the systems that will be replacing old low-
                pressure steam systems for heating in most new construction. If you are dealing with a new system, it
                is important to be aware that three are many harmful substances, which remain in the boiler and piping
                after construction. It is common to find oils, greases, weld slag and other contaminates within the
                system. It is important that a good initial cleaning or boil out of the entire system be conducted before
                filling.

                      It is recommended that chemical treatment be provided for the initial fill of the system.
                Generally, Chemicals will be required to prevent scale formation, promote elimination of dissolved
                gases and control pH. While many experts will tell you that closed systems require little or no
                attention to water treatment, experience has shown that few systems can actually be considered
                completely closed.

                      Especially in older hot water systems, you will encounter losses from pump packing, glands, air
                venting devices and threaded or flanged pipe connections. Make-up is generally provided by an
                automatic fill device.

                     Make-up water provided by the fill device should have some means attached to provided
                chemicals treatment to the raw prior to being introduced to the system. This is generally accomplished
                through a shot-type chemical feeder. These device are used for batch feeding of chemicals into closed
                loop or low make-up water systems manually without the aid of pumps.

                      It is also recommended that a water meter be installed to monitor the make-up water required by
                the system to:

                                  Monitor system loss
                                  Identify system loss
                                  Correct system loss




                          BARON Chemicals & Systems (P) Ltd.
                          H-5/ 21, Krishna Nagar, Delhi-110051. Tel:011-22418572,22056393 Fax 91-11-22023200
                          Email: info@baronchemicals.com Web: www.baronchemicals.net

								
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