Understanding your boiler system should not be difficult. An unfortunate trend in the industry, however, goes against making things simple, cluttering the market with terminology and explanations that are confusing and difficult to understand. Whether you are a first-time industrial boiler buyer, considering a replacement or just looking for ways to improve your existing steam system, this article is for you. In it, we will present a few points to help you get the most out of your steam system, regardless of your supplier or situation.
Efficiency Saves Money
Efficiency represents the single greatest impact on your annual costs. In any boiler application, the bottom line is that you want your steam system to be running as efficiently as possible. The better the efficiency, the better the boiler is burning fuel, and the less you spend on fuel each year. As fuel costs continue to rise, the annual cost to operate a boiler can have the potential to triple that of a new boiler installation. When choosing between similar manufacturers, be sure that the efficiency rating is as high as possible. A boiler with even a slightly higher efficiency rating has the potential to offset the costs of installation in the first year.
In most industrial settings, boilers end up being sized incorrectly for their application. This problem affects both oversized and undersized systems. Most boilers operate at a peak efficiency during high firing rates. If the boiler is oversized for its application, it only delivers at lower firing rates. These lowered rates drive down efficiency numbers and cost money. Conversely, a system that is undersized will struggle to meet steam demands, causing the application to fall behind while you wait. This is a problem that typically ails processes where production has increased beyond what the boiler can deliver. In both cases, whatever potential supplier you are working with should be able to provide a personalized solution that is sized correctly for your steam application. This solution should be tailored to your individual needs and application as well as account for the possibility of future expansion.
In any boiler application, you want your steam system to be running as efficiently as possible.
Maintaining Combustion Rates
In order to keep the boiler firing at an ideal rate, it requires excess air. This excess air, however, needs to be calculated and calibrated to a specific amount: Too much or too little will result in wasted energy, unburned fuel and carbon monoxide or soot, all of which work against proper heat transfer. This results in the boiler consuming more fuel just to achieve your previous results.
Monitor TDS Levels
Those impurities in water commonly are known as total dissolved solids (TDS). Because it is impossible to remove all of these impurities, each boiler has a total TDS level that it is capable of running under without seeing a reduction in performance. This TDS control comes in the form of blowdown, a periodic removal of water from the system that flushes out these undesirable qualities. While blowdown is a necessary procedure, it is worth noting that the water being dumped is water for which you have already paid (multiple times). You paid for its delivery, paid for its treatment and paid to heat it. With this in mind, a boiler that is capable of operating with higher TDS levels also will require less blowdown and less wasted water.
The Economizer Section
A type of heat exchanger used with boilers, an economizer is a great way to raise a boiler’s efficiency. All boilers produce exhaust gases, which typically are vented into the atmosphere. An economizer makes use of these otherwise wasted gases as a heat source. Common ways include being used to preheat the boiler’s feedwater or to be an extension of the boiler itself, depending on the design. While adding an economizer section incurs an additional cost, the addition will increase overall boiler efficiency, further lowering fuel and ongoing operating costs.
Proper water treatment is key to avoiding leftover residue or scale clinging to internal components.
Bring Back the Condensate
As steam travels from the boiler though a network of pipes for its eventual use, some of that steam will inevitably condense and return to water. Many installations consider this water to be useless and simply dump it down the drain alongside the blowdown. This, however, is a tremendous waste of energy. Similar to the case of blowdown, condensate is water for which you have already paid a significant price. In order to maximize this potential energy, it is always advisable for condensate to be trapped and returned to the feedwater tank for reuse. Because condensate is just shy of its boiling point and has condensed from clean steam, it requires minimal heating and chemical treatment. Adding it back into the feedwater tank significant lowers both the required heat and use of chemicals to prepare water for use in the boiler. Returning the condensate once again increases the efficiency of not just the boiler, but the entire plant.
Speaking of unfortunate habits within the boiler industry, another is neglecting the regular upkeep of equipment – a practice that can cause boiler performance to drop significantly over time. Most suppliers will recommend a maintenance schedule when the burner is purchased to ensure smooth operation of the boiler, associated equipment and piping. While there is always a temptation to save money and delay the time between maintenance, at this point, there has already been a significant investment in the steam system. Regular maintenance is integral to protecting that investment and ensuring the longevity of the boiler. Having a trained technician visit regularly may seem like an unnecessary cost. It pales in comparison to the costs associated with a plant-wide shutdown in the event of a boiler going offline, however, as well the time spent waiting for a technician to arrive at the plant to get the boiler running again. Keeping up with maintenance allows identification of potential problems before they occur, and keeps the operation running without interruptions.
While adequate insulation typically is standard on newer systems, it is still worthwhile to take a closer look on the boiler and throughout the steam system. If the boiler is warm to the touch or, worse, if the boiler is too hot to safely approach, you are paying to heat much more than just the feedwater. You also are paying to heat up the entire room. As with efficiency ratings, a potential supplier should be able to provide the numbers behind heat loss, referred to as radiation and convection losses. A product with less heat loss will not have you paying to heat up the boiler room and will result in greater savings. The same is true of the pipes and fittings in the plant. Any hot surface should be insulated in order to keep the heat inside the pipes from radiating into the air, and to protect plant personnel. The alternative is that more of steam will transform back into condensate, and the boiler will have to work harder to fulfill steam demands. A modern installation should include this, but when managing an older system, consider inspecting the steam lines for areas where insulation may have been removed, damaged or is missing altogether. An update in insulation can represent savings of tens of thousands of dollars, depending on the size of the steam system.
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