As an aspiring marine engineer, one would always learn how a machine works, its principle, construction, standard operating procedures and safety measures to be taken while handling the system. This is a common procedure/method, which is followed by engineers working on board ships.
However, machines do not break down or stop working in a particular way. More than often engineers onboard experience things different from what they have learnt from engineering books. In spite of having good knowledge of particular machinery, an engineer can get stuck when it comes to troubleshooting machines during an emergency.
So how do marine engineers prepare themselves for all types of machinery problems?
The answer can be found in reverse thinking or reverse brainstorming.
What is reverse brainstorming or reverse thinking?
Reverse brainstorming is a process of problem solving which involves addressing the opposite of the problem you’re trying to solve, so instead of attempting to find solutions for a specific problem, try to find what could cause more of the same problem.
Instead of asking what a problem is and how to fix it, reverse brainstorming asks “What causes the problem?” or “How could I possibly cause the problem?”
So as a marine engineer onboard, you can think of reasons as to why and how something does not operate and prepare different ways to troubleshoot the same.
Reverse thinking is a proven method for solving problems and finding innovative solutions to the same problem. This provides a practical approach to solving complex issues on board ships.
For e.g., let’s take the example of a fresh water generator of low-pressure evaporation type found in most of the vessels.
Fresh water generator is used onboard ship to produce fresh water from seawater. But it produces distillate water only if the entire system is flawless and correct sequence is followed in operating & maintaining the equipment all the time.
One of the most common problems in freshwater generators is the distillate water produced is too salty.
So to apply reverse thinking, instead of finding solutions to the problem at the last moment we can reserve think the issue in advance as to what can cause the issue.
- If the brine ejector is clogged or if the feed is too high, the seawater may reach the condensate chamber
- Sea water can accumulated in condensate collecting chamber before starting the fresh water generator due to feed water valve kept open and/or vacuum breaker not opened after stopping the fresh water generator previous time
- Demister which is used to filter water droplets carried along with the vapour, is torn or fallen down
- The tubes of condenser are leaky
- The salinity indicator is faulty and giving false indication
These are some of the main reasons that can cause show high salinity in water. As you gain more experience of on board machinery, you will be able to apply the reverse thinking approach in a better manner.
Let’s understand some more ways to troubleshoot problems using reverse thinking.
The first process in starting fresh water generator is to create vacuum inside the shell to make seawater evaporate at a lesser temperature than its boiling point at atmospheric pressure.
At this stage, a common problem experienced is insufficient vacuum formation.
A reverse-thinking approach can help troubleshoot this problem in a much easier manner. Some of the common reasons you can think of are:
- Faulty vacuum gauge indicating false value even after vacuum is actually created
- Vacuum breaker valve not closed before starting
- Bottom blow valve opened during chemical cleaning may not be closed
- Feed water inlet valve not fully closed sucking in seawater and fills the chamber completely when the system is not in operation
- Air ejector or brine ejector may be clogged
- Incorrect tightness of any gauges, pipe flanges etc. connected to the shell
- Joints removed for any maintenance or renewal may not be proper or damaged, leading to air leakage inside
- Suction & discharge valves of the ejector pump are not open, insufficient pump pressure due to clogged strainer, pump sucking in air or pump failure
- Overboard discharge valve of the ejector may not be open
- Drain valve may be open or distillate pump gland is worn and leaks air into the system
Once the vacuum is attained, the cooling medium to condenser and feed to evaporator is admitted by throttling the condenser inlet and outlet valves and feed water valve respectively before the heating medium is supplied and then jacket cooling water is fed into the evaporator by throttling the jacket water inlet valve.
Now once the fresh water generator is in operation it is supposed to produce fresh water of designed capacity by subsequent evaporation and condensation process.
At this stage, it is often found that the discharge pressure of the distillate pump is low or it fluctuates more or there is reduce fresh water production. Reverse thinking this problem can help to find solution to the problem well in advance. Reasons you can think of:
- Discharge valve of the distillate pump may not be opened
- Insufficient supply of jacket cooling water and requires more closing of by-pass valve.
- Insufficient supply of feed water.
- Back pressure is more & filling valve requires throttling
- Air ejector may be clogged
- Distillate line or impeller eye of distillate pump may be clogged & distillate produced remains in the collecting chamber
- Sticky solenoid valve
- Scale formation in evaporator and condenser tubes
- Increased seawater temperature causing reduced condensation
- Reduced heat transfer efficiency of evaporator or condenser due to scale formation.
- Flow meter may be faulty indicating reduced production than actual
Reverse thinking machinery problems not only helps engineers in finding different solutions to the same problem but also prepare them well in advance for a variety of problems. Marine engineers while learning about any machinery and the function of its components should always try to think reverse by visualising the machinery in a practical manner and understanding what can be the reasons that can lead to certain problem.
Such an understanding would not only help in easy troubleshooting of any fault but also the necessity of carrying out routine maintenance and checks on all equipment by insisting the consequences on failure of doing it. Moreover, if such practical difficulties are well exposed during understanding the basics of the machinery, it would be much easier to handle situations on board ships even at the junior level.
It is time marine engineers apply new and innovative approach such as reverse thinking in order to solve a variety of on board problems to ensure that they are well prepared for all kind of maintenance work and emergency situations on ships.
Over to you..
Do you think reverse thinking approach can help marine engineers on board ships?
Let us know in the comments below.
References: Sasakura fresh water generator equipment manual