Excess air provides safe operation above stoichiometric conditions. A burner is typically set up with 15% to 20% excess air in higher firing ranges. Higher excess air levels result in fuel being used to heat the air instead of transferring it to usable energy, increasing stack losses and significantly decreasing efficiency. Boilers with lower excess air throughout the operating range have higher efficiencies.
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.
In theory, to have the most efficient combustion in any combustion process, the quantity of fuel and air would be in a perfect ratio to provide perfect combustion with no unused fuel or air. This type of theoretical perfect combustion is called stoichiometric combustion. In practice, however, for safety and maintenance needs, additional air beyond the theoretical "perfect ratio" needs to be added to the combustion process - this is referred to as "excess air".
1. Your existing system is inefficient
Efficiency is key when it comes to plant heating. Utilizing efficient equipment can save your company a significant amount of money in the long run and it is better for the environment. If you know that your existing system is not as efficient as it could be and it is in need of repair, it may be worth looking into thermal oil system replacement.
2. Your existing system features helical coil technology
Helical coils are common in thermal oil heaters from most manufacturers. But there are many reasons why serpentine coils are the better way to go when it comes to thermal fluid heating. Repairs to helical coils can be so expensive and time consuming that in many cases you are better off investing in new equipment – and it is well worth it to consider a new thermal oil system that features serpentine coil technology instead.
In the case of a thermal oil heater in a high-temperature operation state, if it encounters an emergency situation of power failure, its correct treatment is:
When the circulating oil pump cannot operate normally due to power failure, the heat transfer oil in the furnace tube will exceed the allowable value in a short time due to the residual heat of the furnace. At this time, the cold oil switching valve should be opened to release the cold oil in the expansion tank. And sent to the oil storage tank. At the same time, wet coal pressure or emergency shutdown is required and needs to be completed within 5 minutes.
In addition, we need to pay attention to not to put the oil in the expansion tank clean, otherwise the system will inhale air and cause problems. An oil level mark can be made on the oil level of the oil storage tank. When the cold oil is replaced, the valve can be closed in time to avoid the expansion of the expansion tank and the oil storage tank.
Package boiler is a boiler that had been fabricated and available as a complete package. The entire pressure parts have been assembled in the workshop and ready to be sent to the field or site where power plant is located. On the field/site requires only connection and integration of course work in electrical connections, water pipes, steam pipes and fuel piping system to operate. Package boiler is one of classification of boiler based on erection. Design package boilers in general are the type of Fire Tube Boiler and have made up shell and tubes. This type has high heat transfer both radiation and convection.
Retrofitting a piece of equipment or an existing industrial heating system can be very challenging, but it can be especially frustrating if you haven't planned well ahead of time. You'll want to be sure that you've done your homework to ensure that retrofitting the piece of equipment you have in the way you have in mind is actually possible.
If it is possible, you'll want to work with the appropriate engineers to figure out exactly what it will entail, how much it will cost, what impact it will have on operations, etc.
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.
