If you are marine engineer, the you should must know Turbocharge washing procedure. This questions also asked in MMD Oral exam.
Turbocharger is an important components of engine which increase the power to weight ratio of the engine. A turbocharger is an instrument fitted on the engine to increase the overall efficiency of the engine. Turbocharger affects the efficiency of the efficiency of engine. So, we need to washing it properly on time.
Let us first understand why turbocharger washing is necessary. If washing of blade of turbine and blower side is not done then a layer of air and exhaust gas formed on the blade. All Energy of exhaust gas not transfer to blade so, it does not rotate with adequate speed so, air required for combustion is not adequate so proper combustion does not takes place. Thus, we understand how fouling affects efficiency.
As due to fouling of blade there is decrease in efficiency of engine. so, need to do washing procedure of turbocharger on time. According to instructions mentions in the manual of turbocharger , washing is done.
Important point related turbocharger washing
- Keep in mind that , if you have not done the washing procedure of blade of blower and turbine from a long time then do not do washing procedure. Before doing washing procedure, make sure a complete overhaul of turbocharger is done. If you have not done overhauling ( if not cleaned for a long time ) and do washing of blade then deposits on the blade will not remove properly. some of the deposits left on blade. When Turbocharger run it create a Noise and heavy vibrations due to imbalancing of blade. It is very difficult to handle and cause break the some important part of the turbocharger.
- For washing the blade of blower side, a separate connections is provided.
- Fouling on the blade of exhaust side is less as compare to blower side. It is logical questions, everyone know. It is because due a high temperature and pressure gas falls on the blades and did the work of removing all the deposits accumulated on blade. As exhaust from combustion chamber contain some amount of impurity like caco3, carbon deposits and ash etc. So, some amount of exhaust deposits remain on turbine blade.
- Sometimes, surveyor ask that , how will you know the efficiency of turbocharger is good. Again, this is tricky questions. Efficiency of Turbocharger can be get from Difference of inlet and outlet temperature of t/c. Because from difference, We can conclude that how much exhaust gas energy is is used or transfered to the blade for rotation.
Turbocharger Washing procedure
Foe cleaning of blade we use either water or grit. For both separate connections given
Here, i will explain both washing procedure if turbocharger.
Procedure of washing the turbine blade of turbocharger
Note :- When we will do water washing then we reduce the engine rpm. We also use Warm water instead of cold water At the pressure of 4.5 bar. WE do this because cold water and hot surface of blade cause cracking of blade of t/c due to quenching effect.
First inform the bridge that we are going to t/c water washing.
Take the wind directions. Why we check wind directions ? it is because of fire hazards.
We have to decrease the RPM of engine before doing washing procedure. But speed will not decrease suddenly. Take at least 30 minutes to decrease the speed gradually. Keep decreasing speed till temperature of exhaust gas at the inlet of T/c is approximately 200-230 Degree Celcius.
When we reached at required rpm then wait and run the engine the engine at same speed for approximately 10-minutes so that temperature stablizes.
Now open the drain of Turbocharger.
There Are two Valves provided, one for drain and other for supplying warm water.
As we already open the drain, now open the valve of water washing. Let it open for 10 minutes. Ninety percent of water get evaporated and ten % of water come from the drain.
Water coming out from the drain should be checked and if it is clean that means cleaning procedure is done properly. Now close the drain valve of T/c.
Now close the water supply valve. Run the engine at same speed for ten minutes. Then increase speed gradually. Meanwhile check abnormal vibrations or noise from t/c.
This is water washing procedure of Turbocharger on turbine side.
Dry washing of Turbine side
There is a Box provided for putting a grit. Gauge glass fitted on it to check the level of grit.
There are three valve fitted to grit cylinderical box. One valve is for putting grit. another valve for supplying air. One valve is fitted at bottom of box which supply grit or air to turbine. name valve A, B AND C.
Valve A :- For supplying Grit to box.
Valve B :- For supplying air.
Valve C :- For supplying air of grit to inlet to turbine.
Dry washing is done at high RPM.
Increase the RPM of engine same as mention above to decrease And come speed at required RPM and let it run for 10 minutes and wait for all parameters to come stable. Check the air bottle pressure and drain it.
- First inform the bridge and check the directions of wind.
- Open the valve A and fill the grit in the box. Fill the grit upto 3/4 th level and close the valve.
- Open the Valve C grit will enter to turbine side.
- Open the Valve B and provide compressed and wait for a minutes and after that close it.
- From the sight glass and help of torch check all grit in turbine side is gone or not. But keep in mind that close the Valve C before seeing the conditions of grit,.
This is dry washing procedure of turbine side of turbocharger.
Dry washing of blower side of turbocharger
You to do the dry washing at high RPM. Follow the above procedure to increase the RPM and Run for ten minutes to stablize all parameters.
Check the air bottle pressure and drain it.
Valve A :- For putting grit
Valve B :- Supplying air
Valve C :- For supplying air to blower side of turbocharger.
Open the Valve A and put the grit up to 3/4th level of box. Open the valve C
Open the valve B and provide compressed air. Wait for a minutes and close valve B and the Valve C.
This is all about washing procedure of turbocharger.
Advantages of water washing
The main advantages of water washing is that cleaning of blade is proper and increase the efficiency of T?C.
Disadvantages of water washing
- There is more chance on increase of corrosion of blade.. It is due to sulphuric acid in exhaust gas.
- If with water washing is not done properly cause noise or imbalnce of blade and leads to break.
- It takes more time in cleaning.
So, because of the above reason we dp grit washing. Note :- During grit washing make ensure that drain of t/c closed.