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Showing posts from May, 2020

Tools tackles used in power plant maintenance

Tools & Tackles are the main resources for power plant maintenance..Thsese are classified into Hand tools,machine tools, lifting tools & measuring tools. Power plant maintenance tools & tackles Powerplants of capacity 10 MW to 100 MW need following tools for routine preventive, predictive & breakdown maintenance works. A. Hand Tools: Spanners (Ring, flat, box, tubular and Allen types) Files (Rectangle, square, triangular, round, half round) Chisels 6", 12" Screw spanner 6", 12" Pipe wrench 12", 24" Plumb Hammer and mallets Pliers (Nose and circlip pliers) Shim cutter Torque wrench Pipe bender Hole and letter punches Screw drivers Line testers Bench vice B. Machine Tools: Single phase Hand drill machine Hand angle grinding machine (AG-4, AG-5 and AG-7) Pipe cutting machine (Chop saw machine) Air blower Vacuum cleaner Hot gun Bearing heaters Power plant Mainte

Constructional materials & welding electrodes used in power plant

What are the various materials used in power plants construction??? 1-Low Carbon Steel IS 2062, IS 1239: For structural steels like plates, angles, channels, beams, platform, walkways & LP steam lines etc. 2-High Carbon Steel SA 106 Gr. B/C, SA210 Gr, B/C, SA 516 Gr. 70: For Boiler pressure parts like water wall panels, headers, economiser coils, down comers, feed water lines, steam drum etc. 3-Alloy Steel SA 213 Gr. P11/T11, P22/T22, P91/T91: Super heater coils and main steam pipe lines. 4-Cast Iron: Travelling grate materials, pulley, coupling etc. 5-Copper: Air conditioning cooling lines. 6-Brass: Surface condenser and oil cooler tubes. 7-Stain Less Steel SS 304, 316, 410 etc: Ejector tubes, surface condenser/oil cooler tubes, control valve stems & valve trim materials 8-Plastics: PVC pipe lines, valves, tanks etc. 9-Steam Turbine ESV: Cast alloy steel HP Casing: Cast alloy steel LP Casing: Carbon steel Rotor: Forged chromium, molybdenum and vanad

Why thermal expansion is necessary in Boilers

Understanding the term expansion & contraction                                  When a body is heated it will expand & when it cooled it contracts. So body expands & deforms when heated & cooled. Change in temperature of a free body causes body to expand & contract without inducing stress. When the deformation of the body is restricted by means of any external force, there will be huge chances of stress induction. Such induced stresses are called temperature stresses. These may be tensile or compressive in nature. Boiler calculations for Boiler operation engineer (BOE) exam Viva Questions & answers for preparation of BOE exam & interview Here L = Original length of the steel bar ∆t = Change in metal temperature deg C ɑ = Coefficient of thermal expansion Temperature strain e = Free deformation / Original length = ∆L / L E = L ɑ ∆t / L = ɑ ∆t Temperature stress σ = Young’s modulus X Strain = E X e Temperature stre

Why does Boiler back fire?

Why   does boiler back fire? Following potential situations may cause back fire in biomass or bagasse fired boilers Protections & Interlocks in power plants 1-Sudden trip of ID fans or closing of fans suction or discharge dampers: If there is no interlock on ID fans trip to FD fans, a very huge back fire occurs in boiler which has potential to cause damages to the Boiler & operators. Sudden closure of ID fans suction or discharge dampers will cause same back fire as above. 2-Malfunctioning of pneumatic dampers positioner  may cause closure of ID fans dampers resulting into huge back fire in Boiler 3-APH tubes jam : Area required   for the flue gas flow is equals to Boiler capacity/9 . Due to accumulation of ash in tubes, the flue gas flow area gets reduce. This situation causes backfire This situation occurs if Boiler is run at lower load for long time without bypassing APH for FD/SA air, as at lower load flue gas temperature will be less, which get co

Question & Answers on ESP troubleshooting

                                   ESP TROUBLESHOOTING GUIDE 1-What are the potential reasons for large dust collection on collecting plates & discharge electrodes? Higher dust load on ESP Improper rapping Low velocity of flue gas Higher resistivity of ash ESP running under capacity 2-Why there is sparking in the fields? Excessive dust formation on plates Very less gap between collecting plate & emitting electrodes Improper alignment of electrodes Obstacle of foreign material in the field & touching the discharge electrode Improper charge ratio 3-What are the reasons for higher emission at stack outlet? Under size ESP or wrong design Improper rapping Higher spark rate Improper distribution of flue gas Transformer not working or under capacity 4-What are the reasons for damage/corrosion of ESP electrodes & casing plates? Operation of ESP at lower flue gas temperature <120 deg C continuously More ash

Question & answers on vacuum troubleshooting in steam turbines

Understanding  the term Vacuum. The earth's atmosphere exerts pressure upon us known as atmospheric pressure which can be measured in number of ways & methods.At the seal level the pressure measured is 760 mm of Hg, 1 Torr or 14.7 PSIa or 1 bar.Because the barometric pressure varies above seal level pressure is used as reference point. As there is 1 bar pressure exerted on our body and also there is 1 bar pressure within our body. So as per Newton's law action &* reaction are equal and opposite, we do not feel any discomfort. That is there is no any pressure difference between inside & out side of the body. Evacuating air from a closed volume develops a pressure differential between the volume and the surrounding atmosphere. If this closed volume is bound by the surface of a vacuum cup and a work piece, atmospheric pressure will press the two objects together. The amount of holding force depends on the surface area shared by the two objects and the vacuu