With the increasing requirements for environmental protection in China, RTO (Regenerative Thermal Oxidizer) devices are being used more and more widely, and all kinds of manufacturers are springing up. As a highly efficient device for treating VOCs (Volatile Organic Compounds), RTOs sometimes exceed the emission standards in actual operation. To address this phenomenon, we have summarized ten key factors that may lead to exceeding the emission standard of RTO incineration device, which are shared below:

Ten factors

01 Defective pre-treatment design of VOCs exhaust gas

VOCs emitting enterprises that provide incomplete basic data or fail to accurately reflect the actual VOCs exhaust gas composition and concentration will likely result in a defective design of the pretreatment program. For example, if the enterprise fails to specify the specific composition of VOCs, the RTO device may not be able to adequately take into account the presence of certain specific gases, such as dimethylamine, during the design stage. This may not only lead to the lack of necessary treatment steps in the pre-treatment system (e.g., acid washing), but may also lay a hidden danger for the subsequent operational safety.

02 Defective design of RTO safety facilities

Combustible gas detection signals were not incorporated into the RTO control program system at the time of design. When the concentration of combustible gases in the exhaust gas reaches the potential explosion limit, the system is unable to automatically trigger safety measures such as dilution or switching to bypass, which leads to a high concentration of combustible gases entering the RTO furnace body directly, increasing the risk of fire or explosion. Since 2020, as required by the new engineering specifications, all RTO units must be equipped with this function to ensure a timely response when dangerous gas concentrations are detected and to effectively prevent safety accidents.

03 The process design of the VOCs exhaust gas transportation system does not fully consider the characteristics of the fine chemical production process

The unstable pressure in the VOCs exhaust gas branch pipe may lead to an increased risk of exhaust gas leakage. At the same time, if the design of the VOCs exhaust gas transportation piping is not reasonable, it may also cause liquid accumulation, further increasing the risk of VOCs concentration reaching or exceeding the lower explosion limit.

04 Lack of effective control of VOCs concentration and oxygen content

If the vacuum exhaust from the reactor is not condensed, and the branch pipes in each workshop are directly connected to the exhaust gas main without corresponding control measures, this may lead to difficulties in effectively controlling the concentration of VOCs. In addition, drastic fluctuations in the concentration of VOCs exhaust gas will affect the stable operation of the RTO device, which will lead to emissions exceeding the standard.

05 Uneven airflow distribution of VOCs

Uneven distribution of airflow in the combustion chamber affects the residence time of the exhaust gases in the combustion chamber, which may lead to a decrease in the removal efficiency of VOCs.

06 Insufficient residence time

Insufficient residence time of VOCs in the combustion chamber may reduce their removal efficiency. According to national norms, the minimum residence time of VOCs exhaust gases in the combustion chamber should not be less than 0.75 seconds. However, for some specific substances, longer residence times may be required to achieve more complete degradation by incineration.

07 Improper air excess factor

An air excess factor that is too high or too low can affect the combustion efficiency and therefore the removal of VOCs.

08 Poor performance of the heat accumulator

The heat transfer performance and heat storage efficiency of the heat storage body is directly related to the heat utilization efficiency of the RTO device and exhaust gas preheating effect, which in turn affects the overall VOCs removal efficiency.

09 VOCs exhaust gas composition is complex

Different types and compositions of VOCs in the exhaust gas will lead to differences in their combustion characteristics and the ease of pyrolysis reaction. Some complex organic compounds may require higher temperatures or longer residence times to achieve complete oxidation.

10 RTO core component - switching valve performance problems

Poor performance of the switching valve is a key factor affecting the stable operation of the RTO plant and the VOCs removal efficiency, especially the leakage problem of the core component. There are significant differences in the leakage rates of different types of valves, such as poppet valves and flat push valves. The use of gas sealing technology can effectively reduce the leakage rate of valves, but this needs to be fully considered at the design and selection stage. In addition, the use of other types of valves, such as butterfly valves, can be explored as an alternative to further optimize the sealing performance and operational stability of the RTO system.

Environmental impacts of excessive RTO emissions

01 Deterioration of air quality

Excessive VOCs (Volatile Organic Compounds) emissions will lead to a deterioration of air quality and increase the concentration of harmful substances in the atmosphere, affecting human health and the growth of plants and animals.

02 Increased greenhouse effect

Certain VOCs are potent greenhouse gases, and exceeding the emission limits will exacerbate the global warming problem.

03 Photochemical smog

VOCs and nitrogen oxides produce photochemical smog under the action of sunlight, leading to deterioration of urban air quality and affecting the quality of life and health of residents.

Solutions for RTO emission exceeding the standard

01 Enhance the pre-treatment of exhaust gas

Condensation: For high boiling point VOCs, they can be concentrated and recovered by condensation to reduce the amount of exhaust gas entering RTO.

Adsorption: Use activated carbon, molecular sieve and other adsorbents to remove low concentration VOCs and reduce the load into RTO.

Scrubbing: Remove particles and soluble VOCs from the exhaust gases by water or chemical solutions, especially for exhaust gases containing acidic and alkaline gases.

Filtration: Installation of high-efficiency filters to remove solid particles from the exhaust gas and protect the internal components of the RTO.

02 Optimizing RTO design and operation

Combustion chamber design: Ensure uniform airflow distribution in the combustion chamber to increase the residence time and contact area of VOCs in the combustion chamber, thus improving the removal efficiency.

Air excess coefficient: precisely control the air excess coefficient and keep it within the optimal range to ensure efficient combustion and VOCs removal.

Heat accumulator selection: Choose high-efficiency heat storage materials, such as high-quality ceramic heat accumulators, to improve heat recovery efficiency and reduce energy consumption.

Valve performance: Ensure good performance of the switching valve to reduce leakage and improve the stability and reliability of the system.

03 Real-time monitoring and control system

Online monitoring: install an online monitoring system to monitor key parameters such as VOCs concentration, temperature, pressure, etc. in real time, so as to detect abnormal situations in time.

Automatic control: adopting automatic control system, automatically adjusting the operating parameters, such as air intake, combustion temperature, etc., according to the monitoring data to ensure stable operation.

04 Regular maintenance and overhaul

Regular inspection: Regularly inspect the RTO device, including key components such as heat accumulator, burner, valve, pipeline, etc., to ensure its normal operation.

Cleaning and maintenance: Regularly clean the heat accumulator and filter to prevent clogging and performance degradation.

Replacement of consumables: Timely replacement of failed adsorbents, filter elements and other consumables to maintain the effectiveness of the pretreatment system.

05 Emergency treatment measures

Bypass pipeline: Set up a bypass pipeline so that the exhaust gas can be discharged directly to a safe place when the RTO device fails to avoid exceeding the emission standard.

Backup system: Consider setting up a backup treatment system to cope with unexpected situations and ensure continuous operation.

Emergency plan: Make a detailed emergency plan, including troubleshooting process, personnel training, emergency material preparation, etc., to ensure a quick response in case of emergency.

Source: Content from the network, for reference and communication only, erosion and deletion.