A few basic questions about heating furnaces

1 Air dampers and flue dampers are generally used together to regulate the oxygen level in the furnace as well as the negative pressure inside the furnace chamber. Generally speaking, the larger the air damper, the higher the oxygen level; the greater the opening degree of the flue dampers, the lower the negative pressure. 2. The oxygen content in the furnace should be efficient; generally, 2-3% is a good level. 3. The negative pressure should be moderate – -50 to -100 is appropriate. If the negative pressure is too low, the smoke will be drawn away at a high rate, resulting in a short residence time inside the furnace, inadequate heat exchange, and low heat utilization efficiency.

What are the effects of a relatively low negative pressure? What is the effect of excess oxygen on combustion? Is low oxygen levels caused by incomplete combustion?

If the negative pressure is too low, the oxygen content may be insufficient, leading to incomplete combustion. Generally, when the negative pressure is at an appropriate level, the oxygen content is also roughly suitable; these two factors need to be adjusted together. If the oxygen content is too high, there might not be any negative pressure in the furnace. Additionally, excess air enters at room temperature and cannot be utilized fully; the fuel needs to heat the air, and a large amount of heat is carried away by the smoke through the chimney, resulting in lower thermal efficiency. I hope this helps

As I understand it (when first working with a furnace), 1: the damper is used to regulate the oxygen supply, while the negative pressure in the furnace chamber is controlled by adjusting the flue dampers； Flue dampers have no direct relation to air volume; the air volume is determined by the blower and dampers. 2. Little air leads to incomplete combustion, wasting fuel and causing pollution ； There is plenty of air, resulting in low thermal efficiency. 3. The burner does not burn well at low negative pressure, and the flame is unstable at high negative pressure (in my opinion). Please give me some advice, expert

1. If the flue dampers remain unchanged and the air valves are opened wide, the oxygen content will naturally increase, but the negative pressure will also increase accordingly. The actual time required for adjustment can be observed; however, the main function of the flue dampers is to regulate negative pressure, while the main function of the air valves is to regulate the oxygen content. Air ventilation is further divided into forced and natural ventilation; the adjustment methods differ depending on the situation. 2. Agree. 3. The combustion condition can be observed through the fire viewing window. Generally, furnaces with natural ventilation are equipped with primary air valves and secondary air valves; the primary air valves are used to adjust the height and color of the flame, while the secondary air valves are used to control the width of the flame and ensure complete combustion. By adjusting these valves in combination, the color and shape of the flame can be made very attractive.

I work in boiler design. There are some differences between heating furnaces and boilers. What will be the situation of the heating furnace market in the next few years or over the next 10 years?

Metallurgical heating furnaces will not see any improvement in the future, as they are sources of severe pollution and high energy consumption; they have been included in the list of facilities to be rectified

I’m not sure whether the heating furnace mentioned by the poster refers to a metallurgical heating furnace or a chemical heating furnace

1. First of all, the opening degree of the air valves is related to both the volume of air and the negative pressure. In general, the opening degree of the air valves in a combustion system is controlled by electric or pneumatic control valves, and this opening degree depends on the feedback temperature and pressure from the furnace. The dampers in the flue are used primarily to control the pressure inside the furnace. 2. Combustion generally falls into three categories. The first is proportional combustion, also known as complete combustion, in which air and fuel (natural gas) are burned in a ratio of 1:10. The second is combustion with excess air; this occurs when there is more air than necessary during combustion, and the excess air carries away the heat energy from the furnace, resulting in waste. The third is combustion with excess fuel; this happens when there is too much fuel available for combustion, and the excess fuel is not burned by the burner and is instead released along with the exhaust gases, again leading to waste. However, in some special types of furnaces, it may be necessary to have either excess air or excess fuel. 3. The pressure inside the furnace is usually maintained at a slight negative or positive pressure, which facilitates combustion in the burner; however, an excessive negative pressure hinders smoke exhaust, requiring forced extraction of the smoke. Excess positive pressure inside the furnace is not conducive to combustion in the burner, but it is beneficial for smoke exhaust.

Chemical heaters, especially those used in the petrochemical industry, are used for preheating materials prior to reactions; in such cases, the heater functions as a reactor.