How to improve combustion efficiency in flue

How to improve combustion efficiency in flue

1 Introduction

As the concepts and awareness of energy saving and environmental protection are more and more valued by people, protecting the environment and saving energy have become a responsibility of people or enterprises. How to reduce energy consumption, improve combustion efficiency, choose appropriate measuring instruments, and meet the requirements of analysis and measurement data.

2. Flue gas measurement and combustion efficiency

All combustion devices, whether power plant boilers, industrial furnaces, various burners or heating devices, are designed to convert a fuel into heat or electricity for production. In particular, people working harder today need to improve combustion efficiency and reduce the emission of pollution sources, that is, reduce NOX, SO2, and HC (incompletely burned fuel); to achieve emissions that meet the standards, in order to facilitate ecological environmental protection. To improve the combustion efficiency, a portable flue gas analyzer can be used for periodic measurements and a continuous online flue gas analysis system can be used to measure the oxygen content in the flue, nuclear fuel content, or carbon monoxide content, and the excess air coefficient and combustion efficiency value can be calculated. , Heat loss and other parameters.

3. Fuel substances

The main substances involved in fuel are fuel and oxygen. Fuels are generally gaseous (such as natural gas, liquefied gas), liquid (such as light oil, heavy oil), solid (such as wood, coal), and oxygen is directly taken from the air. In other words, the two main substances generally become fuel and air. The air contains 79% nitrogen, 20.9% oxygen and a very small amount of other gases.

The so-called increase in combustion efficiency is to allow the right amount of fuel and the right amount of air to burn at the best ratio. 79% of nitrogen in the air is not involved in the combustion, but it is also heated during the combustion process, absorbing energy from the flue Was discharged into the atmosphere. In order to allow 20.9% of the oxygen in the air to participate in the combustion, it is necessary to heat the nitrogen nearly 4 times and then release it. The loss of this energy is inevitable, but it can be managed to a minimum. If the air input can be reduced to the greatest extent possible while ensuring sufficient fuel consumption, this form of loss will be minimized. However, the reduction of air must be carried out on the premise of ensuring that the fuel is fully burned, otherwise the energy loss due to insufficient combustion of the fuel is also very considerable, and the atmosphere will also pollute.

4. Find the best burning point

How to find the optimal combustion point is the key to saving energy consumption. Using oxygen content to analyze theoretically: the more excess air in Figure 1, the greater the loss of energy consumption; if the oxygen content increases, the nitrogen The more energy taken away. To reduce energy consumption, the oxygen content in the flue must be reduced; however, if the oxygen content drops too much, the fuel will be incompletely combusted due to insufficient oxygen, and this will cause losses, so what is the appropriate oxygen content?

In the figure, the area of ​​the heavily colored shaded portion of excessive fuel energy consumption indicates the energy consumption caused by unburned fuel, and the combustible gas in the flue.

It can be seen from the figure that when the unburned combustible gas is higher, the energy loss is greater. To reduce energy consumption, the excess combustible gas content in the smoke must be reduced, and polyoxygen is added to participate in the reaction. In order to reach a more appropriate level?

Because no matter what kind of fuel is hydrocarbons (CxHy), when the fuel enters the furnace, the carbon breaks easily and reacts with oxygen to form carbon dioxide and water, and a small part does not react with oxygen enough to form CO + H2, from Run away in the flue.