In the VOCs treatment process, the RTO (Regenerative Thermal Oxidizer) thermal storage combustion oxidation system is the most commonly used treatment process, which has an advantage in high-temperature oxidation treatment due to its low energy consumption ratio. Generally, the overall heat recovery efficiency is ≥ 95%. Although this process has relatively low energy consumption, for many low concentration situations, natural gas still needs to be consumed for heating treatment, which is also one of the key factors in daily burner selection. Below, we will briefly introduce the specific accounting process and principle.

This introduction of the calculation is for simplified calculation, and detailed calculation requires many variable factors and mathematical equations. However, the results can be used as a simple reference for daily burner selection and natural gas consumption, especially in the early stage of the scheme. Considering the universality of the calculation, this calculation ignores the variable factors that may occur in different processes such as RTO heat dissipation, blowing air, combustion air and fuel, as well as other heat extraction ports, and mainly considers the main combustion and heat storage processes.

Firstly, before calculating, we need to understand a concept, the definition and concept of heat recovery efficiency. The simplified calculation formula for heat recovery efficiency is

among

Tcom is the temperature of the combustion chamber, ℃

Tin is the inlet temperature of the exhaust gas, ℃

Tin is the exhaust gas outlet temperature, ℃

In general, the heat recovery efficiency requirement is ≥ 95%. The efficiency of other heat storage that cannot be achieved is the current heat loss, which refers to the energy that the burner needs to provide when the concentration is 0. This is the part we need to calculate. The following example will illustrate.

For example, a three bed RTO with a flow rate of 10000m3/Nm3, inlet temperature of 35 ℃, design thermal efficiency ≥ 95%, average furnace temperature of 850 ℃, fuel of natural gas, and calorific value of 8500kcal/Nm3.

According to the temperature and heat storage efficiency formula,

Can calculate the exhaust gas outlet temperature

This burner needs to replenish the energy lost in this part, and the energy loss is calculated according to

For the convenience of calculation, the combustion specific heat capacity is calculated simply based on a constant specific heat capacity,

Finally, according to the formula, calculate the heat as follows

136500kcal, the final calculation of the amount of natural gas consumed

The above selection values are the minimum burner selection values, which are also zero concentration gas consumption values. Fine calculation requires comprehensive and complex calculation by adding blowing air, combustion efficiency, heat dissipation efficiency, and the results of adding the actual selected burner and combustion air. Moreover, the actual inlet concentration cannot be zero, and the heat storage efficiency is greater than 95%. Therefore, the gas consumption also needs to fluctuate according to the changes in the calorific value of the imported exhaust gas. However, in the actual selection of burners, empirical coefficients can be added for simple selection, such as the 136000 burner above. If non explosion proof and brand MAXON is selected, a 250000 kcal burner can be selected.

In summary, the above accounting process can quickly provide data reference during the preliminary scheme and energy consumption accounting stages. After the actual project is implemented, in-depth calculations and negative verification are needed to maintain correct selection and improve public engineering conditions.