Stack temperature is the temperature of the combustion gases (dry and water vapor) leaving the boiler. A well-designed boiler removes as much heat as possible from the combustion gases. Thus, lower stack temperature represents more effective heat transfer and lower heat loss up the stack. The stack temperature reflects the energy that did not transfer from the fuel to steam or hot water. Stack temperature is a visible indicator of boiler efficiency. Any time efficiency is guaranteed, predicted stack temperatures should be verified.
Stack loss is a measure of the amount of heat carried away by dry flue gases (unused heat) and the moisture loss (product of combustion), based on the fuel analysis of the specific fuel being used, moisture in the combustion air, etc.
Condensing boilers can achieve up to 98% thermal efficiency, compared to 70%-80% with conventional designs (based on the higher heating value of fuels). Typical models offer efficiencies over 90% when the return water temperature is at 110 ºF or less; the lower the return water temperature, the higher the efficiency gain.
The combustion air preheater is definitely one of heat exchanger applications. Based on Figure 1 below, flue gas simply leaves steam boiler and passes via air preheater. The combustion air is passed through this equipment too to increase its temperature before being combined with boiler fuel.
Because the temperature of combustion air is lower than the temperature of flue gas, combustion air receive heat transfer from flue gas through combustion air preheater in the process of convection heat transfer. The heat transfer make temperature of flue gas lower and consequently minimizes its heat loss and also decreases the air temperature to stack.
In a boiler, energy from the fuel is transferred to liquid water in order to create steam. Once the water is heated to boiling point, it is vaporized and turned into saturated steam. When saturated steam is heated above boiling point, dry steam is created and all traces of moisture are erased. This is called superheated steam.
Boiler controls provide an extra level of safety and reassurance: they allow you to understand your boiler's daily operations better, as well as perform the crucial duty of ensuring that your boiler is operating safely and efficiently. Regardless of what kind of industrial or commercial operation you run, here are some must-have boiler controls to get the most out of your equipment.
Reliability is absolutely essential to optimal boiler performance. In order to achieve the highest degree of dependability in a boiler it is important to identify and address the primary causes of boiler problems. One of the most common issues that can compromise a boiler is poor water quality.
The effect of water quality on boiler performance is a huge concern for plant owners and operators. Premature boiler failure often occurs as a result of poor or inconsistent feed water quality. Hard water elements in feed water are responsible for a number of issues:
One of the most difficult questions of purchasing new boilers is deciding how many boilers will be necessary. The best way is to consult with an expert who can guide you through the process. However, there are two factors to consider before you speak to an expert.
Purchasing a new boiler is a big decision for any company or organization. It means investing thousands of dollars in a piece of equipment you’ll be using for many years to come. Needless to say, it’s not a venture you should take lightly. You need to know ahead of time exactly what you should be looking for in a new boiler.
