We look at what you need to know when considering flash steam recovery, so you get the best return on investment in your system.
Flash steam is an unavoidable loss – it’s part of steam-using process. What you can control, however, whether you decide to recover this lost energy and water, and re-use it in another process.
If you consider that around 14% of steam used at 8 bar g turns to flash steam, a plume represents a significant loss of water from a system. Food manufacturing processes that use large quantities of high-pressure steam, such as steam jacketed vessels or rotary dryers, produce more flash steam. There is potential for this lost energy to be captured and recycled so you can reuse it in another process
Saving money and energy are the obvious advantages of implementing heat recovery. In addition, a lower carbon footprint, and even the mitigation of reputational risks might tip the balance when it comes to deciding whether to invest in flash steam recovery.
Before you look to recover heat energy from a plume into another process or system, it’s important to identify and address any controllable heat energy losses in your system. If not accounted for, these hidden losses can affect your return on investment. Furthermore, without this diagnosis, it’s impossible to have a realistic expectation of how much energy you will be able to recover from your flash steam plumes.
Controllable losses can occur due to:
• Passing steam traps
• leaking safety valves
• other repairable leaks.
These can be avoided through a number of actions, including scheduling regular steam trap surveys with a steam system expert, keeping stringent records of your safety devices, and continual monitoring of your key plant and steam-using equipment.
A specialist engineer will be able to identify the root causes of your steam loss and determine if there is an opportunity for flash steam recovery at your food manufacturing plant.
If an opportunity to recycle condensate is identified, the engineer can start doing the sums to see if the investment meets your goals.
Saving money and energy are an advantage to implementing heat recovery, but other factors such as a lower carbon footprint or even mitigating reputational risks are important too.
With payback periods of flash steam recovery as short as 12 months in some cases, saving money may appear the most desirable advantage, but cost efficiency is certainly not the only benefit.
Condensate is, essentially, heat energy and any that is lost from your steam system must be replaced by cold water that must be treated and heated from a lower temperature. This incurs both fuel costs and also water charges.
A Process using steam that runs on approximately 10 bar g, could lose around 15-16% in flash steam. Particularly in water-scarce regions, that’s a significant loss. In these cases, the return on investment calculation can start to appear extremely favourable and tip the balance in favour of implementing the flash steam recovery process.
A more efficient system
Condensate is distilled water and contains almost no total dissolved solids (TDS). Returning more condensate to the feed tank reduces the need for blowdown – the process that reduces the concentration of dissolved solids in the boiler water. This reduces the energy lost from the boiler.
Mitigate reputational risk
Flash steam is visible and may even be considered an eyesore. While flash steam plumes have no negative impact on air quality, they can be confused in the eyes of the public with harmful CO2 emissions. Although this is a misperception, some manufacturers may wish to reduce their visible steam plumes, especially if they can capitalise on other benefits of flash steam recovery.
Flexible energy recovery
Depending on your processes, it can make sense to capitalise on your flash steam plumes during certain times of the year and depending on the temperature. Some food manufactures require more energy during colder months, for example to keep oil at a certain viscosity. A professional engineer will be able to advise how you can maximise the benefit of your steam plumes in line with your processes, so you reap the rewards.
Flash steam recovery may be a great idea however it’s just one part of the picture. Having a specialist engineer assess your entire steam system is an opportunity to ensure you’re operating sustainably.
Are you using the correct grade of steam in your process? Using an inappropriate grade of steam for your process(es) can be a source of contamination.
Spirax Sarco tailors steam engineering solutions to food and beverage processes: blanching, peeling and cooking to extrusion, pasteurisation and shrink-wrapping.
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Manufacturers looking to achieve maximum efficiencies from their steam system should consider the recovery of flash steam, eliminating losses that are within control.
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