A ship has hundreds of machinery and systems which helps in its day to day operations. Lubrication plays a vital role in smooth running of these machineries by overcoming and reducing heat, neutralizing acid combustion by-products, preventing scuffing, lessening friction and thereby combating wear and tear between two running surfaces.
The main engine lube oil system on ships ensure lubrication of the main bearings through pumping of lube oil by duplex oil filters, to the crossheads, and guides, piston cooling and bottom end bearings through the swivel jointed pipes in the engine casings.
The engine cylinders have their own lube oil system, which lubricates the surfaces between the cylinder wall and the piston rings through a set of concentric nozzles or quills fitted around the cylinder liner.
It is imperative to maintain the lubricating oil’s properties and to ensure it is in good condition.
This is executed by the watchkeeping engineer who is responsible for carrying out proficient engine room watch especially, on lube-oil temperature, pressure and the condition of oil.
The common contamination of the lube oil can occur because of:
Jacket Water Leaking
Cooler Leakage
Fuel Contamination through Poor Atomization of fuel and unburnt fuel.
High Exhaust Temperature, Burned Cylinder Oil, Carbon from incomplete combustion and products of fuel composition
Scale formation, wear and tear and biological contamination.
Such contamination need to be purified to maintain the quality of lube oil throughout as the quality of lube oil determines equipment lifetime and its productivity.
As impure lube oil leads to:
Reduction in fuel efficiency.
Corrosion on mechanical parts.
Increase in acid formation in trunk type piston engine.
Reduce Load Carrying capacity
Microbial Degradation
Case Crankcase Explosion.
Therefore, we need Lube oil purifier on ships for proper purification of lube oil with minimum throughput or batch purification in case of heavy contamination.
There are three ways in which lube oil purification can be done:
centrifugation,
filtration and
coalescence.
A high-speed centrifugal purifier is installed on a ship to get rid of the unwanted contaminants and pollutants from the lube oil.
On ships, separate marine purifiers are used for fuel and lube oil. Lube oil is purified only through centrifugation while the fuel oil uses both centrifugation and gravity separation.
On ships, it is also referred to as Centrifuge. It is a purifier that separates two liquid substances based on their difference in density with the use of gravity disc to separate solid and water and sealing water as an operator with two-holed lower discs; one for water and other for oil.
Construction Features of Centrifugal Purifier or “Centrifuge”: Electric Motor: This is responsible for driving various components such as bowl, tachometer, gear-pump via pinion gear, and rotating counter.
Friction Clutch: Friction clutch is installed on the horizontal shaft to safeguard and protect the electric motor from damage as the complete purifier assembly is too heavy for a motor to take the full load from the start without overheating. Once the system attends a preset required momentum, the pads gradually move out under centrifugal force connecting the motor directly to the bowl. It is necessary for the friction clutch to engage with the drum for the revolution of the bowl. It safeguards against heavy starting current. A solid coupling, then due to a large starting current, would simply overheat and burn the motor winding. Therefore, friction coupling allows for some time, and after the motor reaches a certain RPM, the coupling gets engaged thereon.
Gear Box: The Gear Box Assembly in Marine Lube oil Centrifugal purifier consists of a motor shaft, friction clutch, the breaking lever, spur gear, worm gear and the attached gear pump.
The Bowl & Disc Stack: The Bowl is a solid assembly made up of high tensile steel working within purifier frame with ample space to accumulate and discharge sludge. Disc Stacks are incorporated with small holes to form the interface line and carry out separation using centrifugal force that causes oil to move inward and water and solid particle to move outward.
Dry Air Generator For Power Systems Dry air generators are more unique in power systems for large transformers and reactors.
When the transformer is shipped out from the factory, the heavier insulating oil is extracted and replaced with light dry air, which reduces the transportation cost of the large transformer.
Due to the long maintenance and accident repair time of a large transformer, sometimes it is more than half a month. If there is no absolute dry air filled into the transformer continuously, the transformer body will be seriously wet and rusted, accordingly the transformer insulation performance will be destroyed.
The dry air generator ensures that the internal insulation of the transformer will not get wet during the maintenance process, and the maintenance personnel will not suffocate due to lack of oxygen when working inside the equipment. It can avoid the influence of external climate change, avoid the traditional transformer oil thermal circulation drying method. It can improve the oil’s insulation performance and reduce the moisture, and also ensure the personal safety of maintenance personnel.
Our GF series dry air generator is mainly composed of air compressor, gas storage tank, cold dryer, suction dryer, three-stage precision dry air filter, pressure reducing valve, flow meter and electric control system.
Its features are as below:
The air compressor takes the latest patent Injection screw rotor from ATLAS COPCO and driven by the efficient and maintenance-free device. It features barely supervised, long-term stable and reliable work, self-diagnostic fault and alarm. The machine has an automatic restart function after power-off.
No heat regenerative dryer uses the principle of pressure swing adsorption to make the desiccant agent absorbing under the pressure of pipe network, and then switch to desorption under the atmospheric pressure and lead back about 14% of the dry gas from the outlet of drier for further purification regeneration. The two towers are working as above alternatively to provide the user with dry compressed air
Means of control:
It adopts the advanced and reliable microcomputer program controller featured automatic timing, auto-switching work. The machine is working stably and reliably and won’t be affected by the power grid, voltage, electric field effects.
This machine has a power supply voltage, air outlet pressure, air outlet dew point, air outlet temperature, adsorption tower pressure and a series of parameters of real-time display instruments for the operation of equipment at any time can be observed, recorded, and greatly facilitate the management.
Lesser known facts about TTR testing that are affecting your results Transformer Turns Ratio (TTR) testing is one of the most common ways of assessing the condition of a transformer’s windings and core. Throughout the life of a transformer, TTR results are compared against the nameplate ratings to reveal insulation deterioration, shorted turns, core heating or other abnormalities. TTR tester is simple, so is often taken for granted without fully understanding the basis of the test. As a result, when measurements are not within expected limits, it is hard to determine the cause and resolve the problem.
This article focusses on some of the lesser known aspects of TTR testing, such as the effect of applied test voltage, step-up versus step-down excitation; differences between nameplate ratio, voltage ratio and turns ratio; sources of error; per phase testing vs true three-phase testing; and more.
The basics
Transformers transfer power between circuits, usually at different levels of voltage and current, by electromagnetic induction. This function depends on the relationship between the number of turns of a specific pair of windings in the transformer. As this relationship is so important, TTR testing is typically performed many times throughout the life of a transformer – during manufacture, at acceptance and then during routine maintenance and as an aid to fault finding.
Modern TTR instruments will work by applying a voltage on one winding of the transformer (VP), measuring the resulting voltage on another winding (VS) and then calculating the ratio of these two voltages. This is the transformer voltage ratio (TVR), but it should be noted that for three-phase transformers, a correction factor, which depends on the vector configuration of the windings, has to be applied.
As TTR measurements are made under no load conditions, impedance will have a negligible effect on the results. The measured value of TVR will, therefore, be approximately equal to TTR, the turns ratio. For this reason, it is standard industry practice to validate TTR with an instrument that in reality measures TVR.
SF6 Gas analyzer Description of the SF6 Gas analyzer The model GA11 SF6 Gas analyzer are innovative and reliable instruments for determining the quality of different insulating gases. Among these insulating gases are included SF6, Novec? 4710 gas mixture (g3 gas) as well as applications for technical air (clean air/ dry air, based on oxygen and nitrogen). The SF6 Gas analyzer GA11 can measure the concentration of up to six parameters, depending on the selected equipment variant.
Set up
A clearly arranged menu structure and a 7" colourtouchscreen allow for intuitive operation. Sensors for the measurement of purity and humidity are included as standard. Optionally, the SF6 gas recovery and refilling system can be extended with electrochemical sensors for determining the SF6 gas decomposition products.
Applications of the SF6 Gas analyzer Analysis of the gas quality in gas-filled equipment
For the analysis of SF6 gas, g3 gas or N2 gas
Special features of the SF6 Gas analyzer Provides measured values for humidity, gas composition (purity) and decomposition products (optional)
Low transport weight of 25 kg
Three methods for emission-free treatment of the measurement gas: - Direct pumping back into the tested compartment - Pumping into an external gas cylinder - Collecting in an external gas bag
Battery power for min. 5 measurements or mains supply
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