China Petroleum & Chemical Corporation， Sinopec Beihai Refining And Chemical Co., Ltd. Plant-Wide VOCs Treatment Project - Rotary Valve RTO

Project Background
Sinopec Beihai Refining and Chemical Co., Ltd. (hereinafter referred to as Beihai Refining and Chemical) is located in the Tieshangang Port Industrial Zone, Beihai City, Guangxi Province. It is one of the most important refining and chemical enterprises of Sinopec in the southwestern region. Currently, Beihai Refining and Chemical has an annual crude oil processing capacity of 6.4 million tons, producing products such as gasoline, diesel, aviation fuel, naphtha, polypropylene, petroleum coke, high-grade road asphalt, sulfur, benzene, xylene, and liquefied petroleum gas.

Source of waste gas
The high-concentration waste gas from the storage tanks, loading, and sewage in the entire plant area of Beihai Refining and Chemical Company is collected and transported to the diesel absorption pretreatment facility for treatment. After being reduced in pressure by the pressure-controlled regulating valve, then it is transported to the RTO furnace for incineration. The waste gas temperature is room temperature, the total waste gas volume is 500-5000Nm³/h, and the total hydrocarbons (C1-C6 hydrocarbons, mainly C4) have a concentration of about 2000-8000mg/Nm³.

Design plan
The Beihai Refining and Chemical Company's plant-wide VOCs collection, transportation, and treatment project uses the technical route of "collection and transportation + diesel absorption + alkali washing + buffered mixed air + RTO" to treat the VOCs waste gas in the plant. After the technical screening, the project finally selected the third-generation technology product - rotary valve RTO.

The rotary valve RTO is mainly composed of a combustion chamber, a ceramic packing bed, a rotary valve, a combustion system, etc. As shown in Figure 2, the furnace body is divided into 12 chambers, of which 5 chambers are for exhaust gas intake, 5 are for purification of exhaust gas, 1 is for cleaning, and 1 is for isolation. The rotary valve exhaust gas distribution valve is driven by a motor to rotate continuously and uniformly. Under the action of the distribution valve, the exhaust gas slowly switches constantly between the 12 chambers. The sealing structure of the rotary valve RTO adopts a lip rubber seal, and the sealing material is selected from wear-resistant, temperature-resistant, and corrosion-resistant materials.

Operation status
The project started operation in 2020. The four-year operation so far has proven the advanced nature of the third-generation technology product - rotary valve RTO technology:
1. The purification efficiency can reach up to 99.8%, and the emission value detected at the chimney outlet is continuously lower than 10mg/m³;
2. The thermal efficiency is as high as 97%;
3. It occupies a small area;
4. The temperature difference between the inlet and outlet of RTO is small, and the equipment is highly energy-saving;
5. The operation of the RTO device is stable and reliable;
6. The rotary valve rubber seal has a good sealing effect, which can achieve continuous emission standards for five years.