Condensate Polishers

Condensate Polishers

The Condensate Polishers will be connected at downstream of the condensate pumps. The Condensate Polishing System remove dissolved solids (such as Fe and Cu), ionic substance, silica and Na / Mg / Cl(there is a possibility to enter seawater in condensate water system by the condenser leakage).

The other function :

   §Remove suspended solid

   §Remove impurities (condenser leakage)

   §Clean-up impurities ( start up )

The source of Impurities is showed in the following figure :

figure 1. impurities sources

Condensate Polishers reduces the risk of damage to the boiler and turbine caused by the concentration of soluble impurities that corrode internals. In additional, the condensate polisher protects the system against condenser leaks. Plant with condensate polishers can also be started up more quickly. Saving the utility time and money and allowing more flexibility of operation.

Condensate Polisher is like Mix Bed Exchange Vessel in Demineralization Plant. It is contain Cation and Anion Resin in a vessel. The both resin can be separated  or mixed as configuration. When the resin is exhausted, the resin must be regeneration. The exhausted parameter is measured by conductivity of Condensate Polisher outlet. Exhausted mixed bed resins (Cation and Anion Resin) are typically regenerated externally to fulfill the highest purity demands. The system consists of two vessels (Cation Vessel and Anion Vessel) for resin separation and regeneration as well as third vessel for interim storage of the interface resin. Cation resin is regenerated by Acid substance ( H2SO4; HCl etc ), where as Anion resin is regenereted by Base substance( NaOH ).

figure 2. condensate polishers

Coal Runoff Waste Water Treatment Process

Coal Runoff Waste Water Treatment (WWT) Process


The waste water source of Coal Runoff WWT is from Coal yard sedimentation pond. The process block diagram is as follow :

figure 1. simplified coal runoff block diagram 

There are 6 basic process in Coal Runoff Waste Water Treatment, that are:
    1. Coagulation
    2. Floculation
    3. Clarification or Sedimentation
    4. Filtration
    5. Neutralization
    6. Sludge thickening

Coagulation is destabilization process of suspended solid colloid material with coagulant agent to produce micro floc using rapid-mix.

Floculation is floc formation process which basically uses agglomeration grouping between particles and coagulants with gentle mixing to combine several particles into large floc.

Sedimentation is the process by which suspended solid particle are removed from the water by means of gravity or separation. Sedimentation involves one or more basins, called Clarifier. In properly designed clarifier, the velocity of the water is reduced so that gravity is the predominant  force acting on the water/solid suspension. The key factor in this process is speed. The rate at which a floc particle drops out of the water has to be faster than the rate at which the water flows from the tank's inlet or slow mix end to its outlet or filtration end. The difference in specific gravity between the water and the particles causes the particles to settle to the bottom of the basin. Some plants have added baffles or weirs in the sedimentation basins to limit short-circulating through the basin, promoting better settling.

To maximize the sedimentation rate, usually used Lamella Clarifier. Inclined tubes and plates can be used in sedimentation basins to allow greater loading rate of sedimentation. This technology relies on the theory of reduced-depth sedimentation : particles need only settle to the surface of the tube or plate below for removal from the process flow. Generally, a space of two inches is provided between tube walls or plates to maximize settling efficiency. The typical angle of inclination is about 60 degrees, so that settled solid slide down to the bottom of the basin.

figure 2. lamella clarifier

Filtration is a process used to separate solids from liquids or gases using a filter medium that allows the fluid to pass through but not the solid. The term "filtration" applies whether the filter is mechanical, biological, or physical. The fluid that passes through the filter is called the filtrate. The filter medium may be a surface filter, which is a solid that traps solid particles, or a depth filter, which is a bed of material that traps the solid. Oversize particles may form a filter cake on top of the filter and may also block the filter lattice, preventing the fluid phase from crossing the filter, known as blinding. The size of the largest particles that can successfully pass through a filter is called the effective pore size of that filter. The separation of solid and fluid is imperfect; solids will be contaminated with some fluid and filtrate will contain fine particles (depending on the pore size, filter thickness and biological activity).

Neutralization is a chemical reaction in which acid and base react to form salt and water. Hydrogen (H+) ions and hydroxide (OH- ions) reacts with each other to form water. The strong acid and strong base neutralization have the pH value of 7. Before discharging the waste water, adjast pH is very important. In Indonesia, keep pH around 6.5 - 8.5.

figure 3. pH scale

The Side process is Heavy Metal Precipitation. This happen at the Coagulation than which injected Precipitation Agent. The principle technology to remove metals pollutants from wastewater is by chemical precipitation. Chemical precipitation includes two secondary removal mechanisms, coprecipitation and adsorption . Precipitation processes are characterized by the solubility of the metal to be removed. They are generally designed to precipitate trace metals to their solubility limits and obtain additional removal by coprecipitation and adsorption during the precipitation reaction.        There are many different treatment variables that affect these processes. They include the optimum pH , the type of chemical treatments used, and the number of treatment stages, as well as the temperature and volume of wastewater, and the chemical specifications of the pollutants to be removed.                                                                                                                                                    In theory, the precipitation process has two steps, nucleation followed by particle growth. Nucleation is represented by the appearance of very small particle seeds which are generally composed of 10–100 molecules. Particle growth involves the addition of more atoms or molecules into this particle structure. The rate and extent of this process is dependent upon the temperature and chemical characteristics of the wastewater, such as the concentration of metal initially present and other ionic species present, which can compete with or form soluble complexes with the target metal species.

Heavy metals are present in many industrial wastewaters. Examples of such metals are cadmium , copper , lead , mercury , nickel , and zinc. In general, these metals can be complexed to insoluble species by  adding sulfide, hydroxide, and carbonate ions to a solution. For example, the precipitation of copper (Cu) hydroxide is accomplished by adjusting the pH of the water to above 8, using precipitant chemicals such as lime (Ca(OH)2) or sodium hydroxide (NaOH). Precipitation of metallic carbonate and sulfide species can be accomplished by the addition of calcium carbonate or sodium sulfide. The removal of coprecipitive metals during precipitation of the soluble metals is aided by the presence of solid ferric oxide, which acts as an adsorbent during the precipitation reaction. For example, hydroxide precipitation of ferric chloride can be used as the source of ferric oxide for coprecipitation and adsorption reactions. Precipitation, coprecipitation, and adsorption reactions generate suspended solids which must be separated from the wastewater. Flocculation and clarification are again employed to assist in solids separation.

figure 4. solubility of various metal vs pH

This Process is in asmuch as the soluble metal is react with a reagent (Sulfide) to form an insoluble metal sulfide complex. The reaction is as below :

Sulfide precipitation is often a more effective alternative to hydroxide since the metal sulfide (MS) generally have lower solubility and much higher binding contants. Thus, the sulfide can displace chelants better than hydroxides and force the reaction toward the insoluble precipitate. Very low levels of metals can be achieved with sulfide precipitation. Copper, cadmium,zink, and mercury can be effectively precipitated with short contact time.

Sulfide precipitation uses either a soluble sulfide or an insoluble sulfide as the source ofbthe sulfide reagent. In soluble sulfide precipitation such as Hydrogen Sulfide ( H2S), Sodium Sulfide ( Na2S), or Sodium Hydrogen Sulfide (NaHS) serve as the source of sulfide. In insoluble sulfide such as Ferrous Sulfide (FeS).

Alkalinity, Hardness and LSI (Langelier Saturation Index)

Alkalinity, Hardness and LSI (Langelier Saturation Index)

Before explaining about these material, let's see the figure below:

figure 1. the carbonate cycle - surface water

Alkalinity is water's capacity to resist acidic changes in pH, essentially alkalinity is water's ability to neutralize acid. Alkalinity refers to the total amount of bases in water expressed in mg/l of equivalent calcium carbonate This ability is referred to as a buffering capacity. A water body with a high level of alkalinity (which is different than an alkaline water body) has higher levels of calcium carbonate, CaCO3, which can decrease the water's acidity. Therefore, alkalinity measures how much acid can be added to a water body before a large pH change occurs. So, while pH measures the strength of an acid (base), alkalinity measures the ability to neutralize acid (base). Mathematically, alkalinity can be determined by:

Alkalinity provides a buffering capacity to aqueous system. The higher alkalinity is, the higher the buffering capacity against pH changes. These 3 ions all react with H+ ions to reduce acidity, increasing alkalinity and pH. The following is those ion :

Hardness, the sum of the calcium and magnesium concentrations in water. Calcium (Ca) typically represents 2/3 total hardness; Magnesium ( Mg) typically represent about 1/3 total hardness. Alkalinity and water hardness are fairly similar--essentially they both come from sources in nature. Water moves through rocks (and picks up minerals as it does so) on its way to rivers and lakes. When limestone and dolomite dissolve in water, one half of the molecule is calcium or magnesium (the "hardness") and the other half is the carbonate (the "alkalinity"). This means that the level of water hardness and alkalinity in a place will be very similar. However, they are very separate measurements, and have very different importance.

Waters are often categorized according to degrees of hardness as follows:

0-75 mg/l - soft

75-150 mg/l - moderately hard

150-300 mg/l - hard

over 300 mg/l - very hard

The capacity of natural water to neutralize acidity or its alkalinity resides primarily in the amounts of bicarbonate and carbonate dissolved in it. Water with pH below 4.5 does not contain bicarbonate and has a source of acidity stronger than carbon dioxide. This is the reason the color change of methyl orange indicator from yellow to orange at pH 4.5 can be used to signal the end point of alkalinity titration. 

Such a low pH in water usually is from sulfuric acid that originates from the oxidation of naturally occurring iron sulfite in geological material or from acidic rain. Water with pH of 4.5-8.3 contains both bicarbonate (alkalinity) and carbon dioxide (acidity). Water with a pH above 8.3 contains carbonate and bicarbonate, but no measurable carbon dioxide.

figure 2. Relationships of carbon dioxide, bicarbonate and carbonate to pH

For example, kindly please to follow the calculation below :

Now is time to discuss about LSI (Langelier Saturation Index). The LSI is basically a way to determine if water is corrosive (negative LSI) or scale-forming (positive LSI). LSI between -0.30 and +0.30 is the widely accepted range, while 0.00 is perfect equilibrium ( with calcium carbonate). Water wants to be in equilibrium, and will find a way to get there. Under-saturation is corrosive, and over-saturation is scale-forming. Water can only hold so much calcium in solution. If water is in LSI equilibrium, neither etching nor scaling will happen. The LSI tells us how saturated the water is with calcium. The Langelier Index is one of several tools used by water operators for stabilizing water to control both internal corrosion and the deposition of scale. Water supply operators can optimize their water supply systems and identify leakage potentials with the Langelier Index. Leakage is a common problem in Newfoundland and Labrador due to the acidic nature of provincial natural waters.

Experience has shown that Langelier Index in the range of -1 to +1 has a relatively low corrosion impact on metallic components of the distribution system. Langelier Index values outside this range may result in laundry stains or leaks. The following is the LSI range as a benchmark:

figure 3. LSI range

How to calculate LSI?

The formula of LSI is . . . ...

figure 4. pH vs Alkalinity

To consider the value of pHsat,can be used graphic or formula as following example :

figure 5. LSI calculation by nomograph

Rankine Cycle

Rankine Cycle at Power Plant

Rankine cycle is a cycle that converse heat energy to power or motion energy. Almost all of steam engine and power plant use Rankine cycle for producing electricity.

figure 1. Rankine Cycle

Water as working fluid at the Rankine cycle is close loop cycle. It's mean water constantly at the end of  process will goes back to initial process. At this cycle, This water undergoes four processes in accordance with the picture below :

figure 2. Temperature - Enthalpy ( T-H ) diagram

The process that happen are:

1. C-D Process, working fluid or water is pumped from low pressure to high pressure, and water is in liquid phase so pump no need high enough input power. This process is namely Isentropic-compression because there is no entropy changing ideally when pumping process.
2. D-F Process, high pressure water entry into boiler for isobaric heating (constant pressure). Heating source is from coal burning, HSD (High Speed Diesel/Oil) or Nuclear Reaction. In Boiler, water is phase changing from liquid to saturated steam (liquid and steam mixing), steam and 100 % superheated steam.
3. F-G Process, this process is happen at steam turbine. Saturated steam from boiler enter to Turbine and undergoes isentropic expansion. Inherent energy from steam is converted to motion energy in Turbine.
4. G-C Process, steam from turbine enter to condenser and happen condensation isobaric. Steam is converted to liquid again so can be used at the cycle.

The description of the cycle through the T-H diagram above is the most basic and simple Rankine cycle. In the aplication there are some modification in order to reach higher thermal efficiency. For example is using preheater ( low pressure heater and high pressure heater) before entring the boiler. The other modification is using Reheater at the outlet steam leaving the turbine, then use reheated steam enter second turbine (intermediate pressure turbine). For easy understanding, kindly please to see the figure below:

figure 3. steam water cycle overview

At the above figure, condensate water is pumped by Condensate Pump from Condenser to Deaeretor or Feed Water Tank which happen preheating process. Water is also through preheater (LP H and HP H) before entering boiler. The heating source is from extraction steam that taken from certain stages in the steam turbine.

Thermal Efficiency

Thermal efficiency of Rankine cycle is comparison between power that resulting from steam turbine which have been reduced by pump power, with heat power entering the boiler. Kindly please to see T-H Diagram in figure. 2 above.

The heating value absorbed by steam can be calculated by following formula :

                                          Qin = m (Hf - Hd)

Steam has decreased enthalpy when conversion process from heat power to motion power in turbine, showed in F-G line in the figure 2 above. The number of decreased enthalpy can be used to calculated how much motion energy resulted from turbine, as following formula:

                                           Wout=m(Hf - Hg)

The next process is condensation in Condenser. Steam that leave from steam turbine is going to Condenser. Here can be seen that there is a heat energy not converted completely to motion energy. Steam that condensation is decreasing enthalpy ( G - C line ), this can be used to calculate the heat out with following formula :


                                           Qout=m(Hg-Hc)


The pressure of condensate water is increased by pump before entering boiler, showed in C-D line. The line show not more enthalpy increasing. It mean the energy that given to water is not significant. The entering energy can be calculated by:


                                            Win=m( Hd-Hc)


The Thermal Efficiency formula is:

                                η_termal = (W_out – W_in) / Q_in

To be easier in calculation, mass variable can be removed.

Water Treatment Miscellaneous Parameters

• Turbidity and Total Suspended Solid ( TSS )

    When we refer to Turbidity, we are looking at how clear or translucent the liquid is by looking at the water’s light scattering properties. Testing turbidity can reveal some suspended solids, algae, organic material, and any other minuscule particles that cause the liquid to become cloudy or murky resulting in a higher Nephelometric Turbidity Unit (NTU) reading. NTU’s are units that are used to describe turbidity. A low NTU reading indicates clearer liquid and higher readings indicate low water clarity. NTU readings generally range from 1 to 4000 where 1 would indicate pristine clarity and 4000 would have the transparency similar to that of milk. An NTU reading of less than 1 is generally considered quite good for tap water.

    Total Suspended Solids (TSS) refers to any particles that are suspended in the water column. These particles can include silt, algae, sediment, and other solids floating in the water (both organic and inorganic). These particles are defined as being large enough to not pass through the filter (through the filtration process) used to separate them from the water. Suspended solids absorb heat from sunlight and as a result, the water temperature increases resulting in a deprivation of dissolved oxygen in the water which can be disastrous to aquatic life if levels are too high. TSS can be measured in ppm, mg/L, g/L and %. To determine TSS, you need to run sample liquid through a filtering process where the sample is filtered, dried, and weighed. Results can be ran through the below formula to determine the TSS in mg/L.

      There are portable instruments available that do measure TSS but they can get quite expensive. The best meter we have found measures both TSS and turbidity is made by Hach. It is a portable hand-held meter complete in a carry case which measures turbidity, suspended solids, and sludge blanket level . More information on this product can be found here.

     When looking at TSS readings, it is generally considered that a reading of less than 20 mg/L is clear. Readings between 40 and 80 mg/L will begin to appear cloudy and readings over 150 mg/L will appear quite dirty. These numbers can vary depending of the type of particles present and are provided as a guide only.

      Turbidity can be measured using either an electronic turbidity meter or a turbidity tube. Both methods have advantages and disadvantages.

      The Difference of  Turbidity and TSS

    Turbidity and TSS are similar in the sense that they are both measuring clarity of liquid but they aren’t actually measuring the same thing. It is worth noting that measuring turbidity from a sample allows you to get an instantaneous reading of NTUs meaning you can take the reading directly from out in the field. Measuring TSS on the other hand, is a manual and drawn out process requiring a precise technique and measurements that often have to be conducted back in a laboratory. While portable meters are available as mentioned earlier, they are expensive and depending on the application, may or may not be worth the investment. It is worth considering the regularity of testing required and whether testing needs to be done on-site or can be taken back to a laboratory to go through the filtering process.

   Put simply, turbidity looks at how well a light passes through liquid and TSS is a quantitative expression of suspended particles. Even though turbidity and TSS compliment each other, they are both influenced differently. For example, TSS can calculate sedimentation rates, while turbidity can’t. Turbidity and TSS do overlap in the measurement of some particles as shown in the illustration below but as mentioned, they do actually differ making it extremely difficult to form any kind of correlation between the two.

• Specific Conductivity and Anion Conductivity

    There are two types of conductivity measurements: specific and cation. Specific conductivity can detect only large amounts of contaminants. Condenser tube leaks normally start out very small, and may increase over time. For example, condensate flow may be 5,000 gpm, and the “leak” 0.1 gpm. On a volumetric basis, this is 20 ppm. Specific conductance instruments may not be able to detect this small leak unless the cooling water conductivity is very high to start.

    Cation conductivity instruments pass the condensate sample through a cation (ion exchange) resin to convert cations (sodium, calcium, etc.) to the hydrogen form, producing an acidic effluent. Since acids are much more conductive than mineral salt solutions, the effective sensitivity is increased dramatically. The generally accepted lowest detection limit (LDL) is 0.05 micro siemens per centimeter (μS/cm). With such sensitivity, cation conductivity can be a very useful measurement to detect condenser tube leaks.

     Specific conductivity aims to know the number of dissolved solid which contained in water, whereas cation conductivity to know negative ion (anion) which dissolved in water. Nevertheless cation conductivity can not know the kind of anion specifically.

• Chemical Oxygen Demand (COD) , Biological Oxygen Demand (BOD) and Dissolved Oxygen (DO)

BOD or Biochemical/Biological Oxygen Demand is a characteristic that express the amount of dissolved oxygen needed by microorganism (usually bacteria) to decompose or break down the organic matter under anaerobic condition (Umaly and Cuvin, 1998; Metcalf and Eddy, 1991). Reiterated again by Boyd (1990), that organic material decomposed in BOD is organic material that is ready to decompose (readily decomposable organic matter). Mays (1996) defines BOD as a measure of the amount of oxygen used by microbial populations contained in waters in response to the entry of decomposed organic matter. From these notions it can be said that although the BOD value states the amount of oxygen, but for simplicity it can also be interpreted as a description of the amount of biodegradable organics in the waters.

Chemical Oxygen Demand (COD) is a second method of estimating how much oxygen would be depleted from a body of receiving water as a result of bacterial action. test uses a strong chemical oxidizing agent (potassium dichromate or potassium permanganate) to chemically oxidize the organic material in the sample of wastewater under conditions of heat and strong acid, so that all kinds of organic materials, both those that are easy to decompose or are easily complex and difficult to decompose, will oxidize. It has the disadvantage of being completely artificial but is nevertheless considered to yield a result that may be used as the basis upon which to calculate a reasonably accurate and reproducible estimate of the oxygen-demanding properties of a wastewater.

The COD test is often used in conjunction with the BOD test to estimate the amount of nonbiodegradable organic material in a wastewater. In the case of biodegradable organics, the COD is normally in the range of 1.3 to 1.5 times the BOD, and it could be that the BOD value is the same as the COD, but the BOD cannot be greater than the COD. When the result of a COD test is more than twice that of the BOD test, there is good reason to suspect that a significant portion of the organic material in the sample is not biodegradable by ordinary microorganisms. As a side note, it is important to be aware that the sample vial resulting from a COD test can contain leachable mercury above regulatory limits. If such is the case, the sample must be managed as a toxic hazardous waste.

Dissolved Oxygen (DO) is the amount of dissolved oxygen in the solution. The illustration of relation between BOD, COD and DO are the following:

figure 1. BOD COD and DO relationship

Close Cycle Cooling Water (CCCW) and Circulating Water (CW)

Close Cycle Cooling Water (CCCW) and Circulating Water (CW) at Power Plant

The following is the block diagram of Close Cycle Cooling Water (CCCW) and Circulating Water (CW) :

figure 1. CCCW and CW

The function of CCCW  is to cool (decrease temperature) oil, bearing or fluid at process equipment. The close cycle cooling water is from demineralization water from Demineralization Water Plant. Due to cool the oil,bearing, or fluid, the temperature of CCCW is increase. To cool the temperature, CCCW is cooled by CCCW Heat Exchanger. The hot water is CCCW , whereas the cold water is sea water. Sea water is coming from  branch line of Circulating Water ( CW ). The following is the figure of CCCW Heat Exchanger :

figure 2. CCCW Heat Exchanger

The function of CW is to cool outing steam of Turbine LP (Low Pressure). The CW ( Circulating Water)  is from Sea Water which is pumped by Circulating Water (CW) Pump. The place of cooling process is in Condensor. Steam will convert to liquid phase (condensate). The figure of Condensor is below:

figure 3. Condensor

The cooling water discharge is going to outfall (sea water). The main monitoring parameter of cooling water discharge is free residual chlorine (less than 0.2 mg/l) and temperature ( less than 35 0C).

Material Handling Overview

 Coal Handling Overview at Power Plant

The Coal Handling Overview at Power Plant are following:

figure 1. coal handling system

• Coal Receiving Line/ Incoming System / Stacking System

It’s mean coal from ship is transported to stockpille. Coal received by the coal unloader line, then transferred to conveyor belt. The provided conveyor belt ( 2 unit, C1A and C1B ) are continued to tower 01. Tower is used as the connection between two conveyors, and also as a place for magnetic separator.

Magnetic separator is used to separate metal ( Ferro only ) by passing through coal flow in the operating belt conveyor. This device is aimed to prevent metal damaging the belt conveyor, the trapped metal is stick to belt of magnetic separator and directed to collected metal bin at the end of the 3 meters magnetic separator belt. Magnetic Separator can’t make system trip.

Tower functioned to regulate the direction of coal flow, whether to use conveyor A or B. For example, the coal flow from both conveyor 1A and 1B is collected to hopper and then the  diverter gate ( deflector gate ) towards 2A or 2B decide to be opened or closed. Tower has diverter gate is Tower 2, Tower 6, and Crusher building. The other ones are not have diverter gate. Almost in tower there is Dust Suppresion, to scrap or minimize the amount of dust caused by coal when is transporting. The placement is each towers from tower 1 until 5. There is no dust supresion in both crusher building and tower 6 because of preventing plug in coal silo.

Along conveyor 2, there is a load-cell-digital-belt-scale to check the sum of coal unloaded from the ship. Another scale is located on reclaimer A and B to compare the weight from the previous belt scale. So that we can get information whether the coal spill can be tolerated or else should be taken care of.

The conveyor belt is installed in pair; one is used for operation, the other is used as spare. For special condition when the coal stock should send to silo directly, both of the belt can be used. The capacity of belt conveyor is 1500 ton/h, the normal operation is below 1300 ton/h to prevent spillage of coal and undetected metal in coal flow.

Coal conveyor is driven by motor drive [6.5 x 250 A], connected to gear box and fluid coupling. To prevent belt miss-alignment, there are belt alignment roller along the belt conveyor. Metal wire along the side of belt is provided for emergency tool, this device is called Pull Cord Switch. In case operator finds a metal in coal flow. In such case operator draw the wire to activate the interlocking system or stop the belt operation.

Stacker and reclaimer ( STARE )

This equipment has two function both to stock / receive and to reclaim / deliver coal. Four modes of its operation:

- Operation (O) : normal delivering and receiving process

- Schedule Maintenance (SM) : stopped for predictive maintenance purpose

- Break Down (BD) : stopped for the failure of equipments and accessories

- Idle (I) : stand by mode, ready for normal delivering and receiving operation.

Stare is moved by 8 motor, 4 in left leg and 4 in right leg. There are Rail Calm as safety protection equipment. It is role as the holder between leg of Stare and its rail so the stare is unmoved even something happen in around environment. Safety protection equipments are consist of two kinds, hardware and software. Hardware protection place on 2 m and 300 m of rail counted from north.

Movement of stare is travelling, slewing, and hoisting. These also be called as reclaiming system. When stacking is travelling from north to south, while reclaiming is from south to north.

         The important parts of Stare:

ü  Split Device Þ to control how much coal go to stockpille and go to coal silo ( called also bypass activity ). For example 20 %, its mean coal to silo is 20 % and to stockpille is 80 %.

ü  Collapsable spoon Þ to control when stare is stacking or reclaiming. Close when stacking and open when reclaiming.

ü  Chute wheel Þ placed around bucket wheel , the function is similar with collapsable spoon. Open when stacking and close when reclaiming.

ü  Water Dedusting Þ to decrease the amount of dust from coal when running.

ü  Stockpile overview in display ( Bench ) :

–         Top bench

–         Intermediete bench

–         Bottom bench

• Coal Delivery Line/ Outgoing System / Reclaiming System

The main activity of this system is transporting coal from stock pile to coal silo. After stacked from coal stock pile, the coal distributed to crusher building. In the end of Conveyor 5 A / 5B, there is magnetic separator. After its passing, coal is temporary stored in Susbin. How much coal needed can be adjusted here by regulating its gate. Output from Susbin, coal goes to belt feeder. Then coal flow directly to the vibrating screen. By using spring and unbalanced mass, the screen dynamically separates the coal size. Measure of screen is 2.5 cm x 2.5 cm. The oversized coal go to the crusher. The qualified coal flow to conveyor 6A / 6B directly. In the end both meet again in Conveyor 6A / 6B.

Metal detector is located afterwards, in order to stop the conveyor operating system in case there’s any metal ( all kinds of metal ) slipped among coal. In such case the operator who works in coal control room check the coal flow and separate the detected metal manually. The unwanted metal can damage the pulverizer and another coal processing equipment. Sampling Systems are located in 2 points, in conveyor 2A / 2B and after the metal detector in conveyor 6A / 6B. Sample is needed for coal sampling process executed in laboratory to re-check whether the quality of coal proper compared to its certificate. The sample is automatically took from the coal flow, fall to the sampler bottle. Belt Scale also located here after Sampling system.

From conveyor 6 A and B, the coal distributed to 6 unit of coal silo each unit by using tripper car and tripper gallery. The sequence of filling the coal silo is determined by the coal control room operator regarding to the level of coal inside the silo. For burner coal consumption, 5 coal silos are needed. Another available one is for spare, while the ratio of MCV and LCV is 4:1. The required size for coal burning process inside boiler is 200-mesh grid. 

      Coal Silo Filling Method :

–         Automatically Þ Just adjust set pont ( excample 95 % ). Tripper car will fill silo until reach 95 % and then seek where silo is under 95% level.

–         Manually Þ operator self bring tripper car to silo he want.

Ø  The Parts of Conveyor

1.       Drive, as force service which consist of motor, breaker, fluid coupling ( arrange when starting and regulate rotation ), gear box.

2.       Haed Pully

3.       Tail Pully, here is place of speed sensor

4.       Carrying Roller

5.       Return Roller

Ø  The Protection Equipment in Conveyor

1.   Speed sensor, velocity permitted is 60 m/s until 110 m/s. While in normal operation is about 90 – 95 m/s. The outside of those values will cause trip. To prevent that tragedy, there is necessary needed speed sensor.

2.     Belt misaligment switch

3.     Pull cord switch

4.     Chute plugged switch

5.     Patch limitaton switch