RTO regenerative thermal incinerator
Its principle is to heat the organic waste gas to more than 760 ℃, so that the VOC in the waste gas can be oxidized and decomposed into carbon dioxide and water. The high-temperature gas generated by oxidation flows through the special ceramic heat storage body to heat the ceramic body and "store heat", which is used to preheat the subsequent organic waste gas. So as to save the fuel consumption of waste gas heating. The ceramic regenerator shall be divided into two (including two) or more zones or chambers. Each regenerator shall go through the procedures of heat storage, heat release and cleaning in turn, and work continuously again and again. After the "heat release" of the regenerator, an appropriate amount of clean air shall be introduced immediately to clean the regenerator (to ensure that the VOC removal rate is more than 95%). The "heat storage" procedure can be entered only after the cleaning is completed.
RTO (regenerative thermal oxidizer) is an organic waste gas treatment technology rising in China in recent ten years. This technology is especially suitable for the treatment of organic waste gas with medium and low air volume, medium and high concentration and complex composition. It is popular with many local environmental protection departments because of its high treatment efficiency, basically no secondary pollution and stable operation. After the use in recent years, RTO has also exposed some problems, among which the more prominent problem is the safety problems such as fire and explosion of RTO. According to the statistics of the environmental protection department of a Petrochemical Industrial Park in China, there are 7 sets of RTO equipment in the park, including 3 sets of fire, explosion and other safety accidents to varying degrees. Therefore, both environmental protection design companies and chemical enterprises must attach great importance to the safety of RTO.
According to the investigation on the use of some enterprises, there are mainly the following reasons:
(1) RTO is not considered in the design of the main devices of some enterprises, resulting in inadequate safety measures in the design, insufficient automation, and mismatch between the actual working conditions and the equipment load.
(2) The composition of organic waste gas from enterprises is relatively diversified and the gas volume is unstable. Due to the intermittent production characteristics of fine chemical enterprises, the concentration and amount of organic waste gas will change intermittently.
(3) Some enterprises did not reasonably select equipment and facilities according to their own actual conditions. The actual working condition after production is quite different from the ideal condition of RTO.
(4) The unexpected problems are not well considered, and the response to unexpected problems is not appropriate and timely.
In order to prevent the occurrence of RTO safety accidents and reduce accident losses, environmental protection design units must put safety issues first in RTO design. At present, the common measures are summarized as follows:
(1) Designers should understand the customer's process and clarify the emission characteristics of organic waste gas and possible sudden factors in the process.
(2) Strictly control the concentration of organic matter imported from RTO to control it at a safe level, which is the most fundamental measure to prevent explosion. RTO itself is an ignition source. If the inlet concentration has exceeded the lower explosion limit, even if the explosion-proof fan and anti-static pipe are used in front, it will not help. As the lower explosion limit of organic matter will be greatly reduced with the increase of gas temperature, and due to the sudden emission of organic waste gas from chemical enterprises, the inlet concentration must be far lower than the lower explosion limit. The main measures include ① installing concentration monitors at the exhaust gas inlet and necessary exhaust gas branch inlet; ② For high concentration exhaust gas, add dilution air valve at RTO inlet; ③ Add buffer tank at the exhaust gas inlet, and the volume of buffer tank shall be properly designed; ④ Interlock control among concentration monitor, dilution air valve, RTO fan and other instruments and equipment to make correct actions for sudden problems at the first time.
(3) In order to reduce the loss caused by safety accidents, the following measures are generally taken: ① add flame arrester at RTO inlet to prevent tempering; ② Add explosion relief sheet at the corner of combustion chamber, buffer tank and pipeline; ③ Set up some fire-fighting facilities near the equipment.