How can the temperature of the secondary combustion chamber be controlled to the extreme?

I’m not very familiar with your process. Is the goal to keep the temperature in the secondary combustion chamber at 1100°C? Is this what you call the pinnacle? If you can truly confirm the existence of this critical point, is this critical point the maximum temperature? If you want to keep the wind at a critical level, as in your last sentence, can the temperature be adjusted automatically? If a critical point exists, it can be achieved using split-range control + ratio control, provided that the changes in temperature and air volume are linear. The requirements you mentioned are not quite clear; the process requirements need to be described more precisely.

Just use temperature along with the damper or fan frequency control to implement a PID control

The meaning expressed may not be entirely accurate; the so-called critical point refers to the heat released from the complete combustion of the flue gases at the inlet of the secondary combustion chamber. Of course, this maximum temperature is not necessarily 1100°C – we have also reached temperatures of 1200°C (in which case it’s still necessary to control the temperature). What we are considering now is how to raise the temperature as close as possible to 1100°C when the calorific value is insufficient. At such times, burners might still be used, as fossil fuels are still required; this raises the issue of energy conservation and reduction of consumption, which is why efforts are made to keep the temperature as high as possible under these conditions. We employ processes for the harmless and volume-reduced disposal of hazardous waste through incineration.

PID can control the size of the damper based on the oxygen content at the outlet; this is a practice used in many industries. However, there are also some issues; for example, the temperature at the outlet of the secondary combustion chamber is very high, and the pressure sensing tube for monitoring oxygen content is a consumable item that incurs significant costs ； Secondly, it’s hard to say how well the damper function can be controlled considering the factor of oxygen content. The range of the empirical parameters is also quite large; it’s said to be 6–10% ； Some say it’s 8–12%, depending on operating conditions; it still seems immature.

Isn’t the oxygen content an indirect parameter? It’s better to control the temperature directly; the oxygen level can be treated as something like a feedforward element. If there is no increase in oxygen level further down the pipeline, testing can be done at the low-temperature section.

I thought carefully about what you said and guess it might mean this: the exhaust gases from the first combustion chamber enter the second combustion chamber where they undergo secondary combustion, thereby achieving truly harmless emissions. The second combustion chamber also requires fuel for combustion. The optimal amount of secondary air is exactly that which allows for sufficient combustion of both the exhaust gases and the fuel, thus maximizing the heat output. If more air is used, it’s unnecessary; it doesn’t increase the heat output and instead has a cooling effect, causing the temperature to drop. If too little air is used, the fuel and exhaust gases cannot burn fully. Therefore, below this optimal point, increasing the amount of secondary air helps to achieve more complete combustion of the fuel, and as a result, the temperature gradually rises. I’m not sure if my understanding is correct. So here’s the question: the value of this critical point for the secondary air flow isn’t fixed. It is influenced by the amount of exhaust gas generated in the combustion chamber, as well as by the amount of fuel used. In other words, it’s a matter of the air-fuel ratio. If you want the air flow to be just right so that the fuel and exhaust gas can burn completely, it’s not easy to do that. You need to take into account the air-fuel ratio required for fuel combustion, as well as that required for exhaust gas combustion. Additionally, you also need to know the amounts of fuel and exhaust gas involved. Can you determine these parameters? I think that the fuel parameters might be uniform and easy to handle. However, the exhaust gases could vary depending on the types of hazardous waste being processed; this seems more complicated. I wonder if my understanding is correct?

Haha, have you ever made a burner?

Oxygen content confirmation is an indirect parameter, but as mentioned on the seventh floor, temperature control means that this equilibrium point can change and is not fixed.

Isn’t it the temperature that you need to control? What changes are the amount of flue gas and the amount of air; it is these amounts of air that are adjusted in order to maintain a constant temperature, right?

I have worked in the thermoelectric field for 10 years, so I am very familiar with boiler combustion.