VOC gas is a volatile organic compound that is harmful to the human body. This gas comes from the waste gas generated in the industrial production process. In order to reduce the harm of this kind of industrial waste gas to the atmospheric environment, we need to adopt certain methods to deal with it. The more common treatment method is the oxidation method, that is, the thermal oxidation reaction of VOC gas occurs through the incineration of industrial waste gas, and the harmless treatment of organic waste gas is finally realized.
Common industrial waste gas combustion processes mainly include Direct Fired Thermal Oxidizer(DFTO), Regenerative Thermal Oxidizers(RTO), Regenerative Catalytic Oxidation(RCO), Catalytic Oxidizer(CO). The advantages and disadvantages of these combustion processes and the thermal oxidizer cost will be described in detail in the following text.
Direct Fired Thermal Oxidizer(DFTO)
Working principle
The design of direct-fired thermal oxidizer is simple, which can be divided into horizontal and vertical structures. Inject exhaust gas and waste liquid directly into the furnace of a direct-fired thermal oxidizer for thorough incineration. The temperature of the incinerator should be controlled at 1000~1500℃, the highest should not exceed 1200℃, and the lowest should not be lower than 900℃. The temperature of the flue gas after incineration can be reused by a waste heat boiler to generate steam. After being reused, the flue gas temperature will reach about 300°C, not lower than 280°C. The oxygen content in the incinerator is controlled between 10% and 16%.
Thermal oxidizer cost
Since the combustion state of organic waste gas in a direct-fired thermal oxidizer is flame combustion, its incineration efficiency is higher than RTO. But thermal oxidizer price and operating cost are relatively high.
Regenerative Thermal Oxidizers(RTO)
Working principle
The regenerative thermal oxidizers the organic matter (VOCs) in the exhaust gas to the corresponding carbon dioxide and water under the action of high temperature, thereby purifying the exhaust gas and recovering the heat released when the exhaust gas is decomposed. The high-temperature gas generated by the oxidation reaction flows through the special ceramic heat storage body, which makes the ceramic body heat up, and “storage heat”, which is used to preheat the subsequent organic waste gas. Thereby saving the fuel consumption required for heating up the exhaust gas. The ceramic regenerator is divided into two or more. Each regenerator goes through the heat storage-heat release-cleaning procedures, in turn, repeating and working continuously. After the heat of the regenerator is released, immediately enter an appropriate amount of clean air to clean the regenerator to ensure that the VOC gas removal rate is above 98%. Only after the cleaning is completed, will the heat storage program be entered again, otherwise the residual VOC gas will be discharged into the chimney along with the flue gas, thereby reducing the processing efficiency.
Thermal oxidizer cost
Compared with other combustion processes, the fuel cost of the regenerative thermal incinerator is lower, but the thermal oxidizer price is high, which will increase the investment cost.
Regenerative Catalytic Oxidation(RCO)
Working principle
Industrial waste gas enters the double-tank regenerative catalytic oxidation incinerator, and the three-way switching air valve guides the waste gas into the heat storage tank of the equipment to preheat the waste gas. The exhaust gas is slowly heated by the thermal storage ceramic block and then enters the catalytic bed. The VOC gas is decomposed and oxidized by the catalyst, and the released heat is used to heat the ceramic block in the second heat storage tank to reduce the consumption of auxiliary fuel. If the VOC gas concentration is high enough and the energy released by oxidation and decomposition is enough, the RCO device does not need fuel replenishment. For example, when the RCO heat recovery rate reaches 95%, the outlet temperature of the RCO equipment is only 25°C higher than the inlet temperature.
Thermal oxidizer cost
Regenerative catalytic oxidation incinerator also has the characteristics of high thermal oxidizer cost and low fuel cost.
Catalytic Oxidizer(CO)
Working principle
The design of the catalytic oxidizer is based on the exhaust air volume, VOC concentration, and the required destruction and removal efficiency. The exhaust gas containing VOC is introduced into the heat exchanger in the system by the system fan. After the exhaust gas is heated by the heat exchanger, it enters the burner. At this time, the exhaust gas is heated to the catalytic decomposition temperature. Through the action of the catalyst bed, the catalytic decomposition releases heat energy, and the VOC gas is decomposed into carbon dioxide and moisture. After that, the purified gas enters the side shell of the heat exchanger to heat the untreated VOC exhaust gas on the side of the heat exchange tube. This way can effectively reduce energy consumption. Finally, the purified gas is discharged into the atmosphere from the chimney.
Thermal oxidizer cost
The fuel cost of the catalytic oxidation furnace is low and the thermal oxidizer price is high, which leads to the corresponding increase in investment cost.
