Rotary valve RTO has been operating safely and stably for five years with ultra-low emissions——Shanghai ** Petrochemical phenol acetone project

The VOCs treatment project of Shanghai ** Petrochemical phenol acetone contracted by Yurcent Environment has been successfully operated for five years since 2018. The purification is up to 99.5%, the thermal efficiency is up to 97.3%, and realizing the ultra-low emission of non-methane hydrocarbon＜20 mg/m³.With the high thermal efficiency, Rotary Valve RTO can save more than 7000 cubic meters of gas consumption per day, and realizing the dual benefits of environmental protection and energy conservation.

Project background

In 1981, SINOPEC Shanghai ** Petrochemical CO., LTD., the first super large petrochemical enterprise across industries and departments, was established. Over the past 40 years, it gradually developed into a ten million tons oil refining base and clean oil production base, which is the backbone production enterprise of SINOPEC and an important energy production base in Shanghai.

During the “ 13th five years plan” period, the company had invested 1.373 billion yuan in special safety and environmental protection projects, completed more than 260 potential safety hazard rectification and environmental protection projects, including a package of environmental protection treatment projects such as ultra-low emission renovation, sewage standard upgrading renovation and VOCs comprehensive treatment renovation, actively prompted the “six” green development tasks, and established a full-process and full-coverage environmental protection work system of source prevention, process control and end control.

Source of exhaust gas

The 200,000 t/a phenol acetone plant located in Shanghai Chemical Industry Zone, Jinshan District, Shanghai, carried out the VOCs comprehensive treatment and ultra-low emission standard upgrading renovation in 2017, as follows:

Design scheme

The project adopts the technical route of “buffing and mixing+ RTO” to treat VOCs exhaust gas. After technical screening, the third generation technical production—Rotary Valve RTO was finally selected.

Figure1  RTO skid-mounted equipment

Advantages of Rotary Valve RTO

The third generation technology production—Rotary Valve RTO has excellent performance in terms of operation safety, environmental compliance stability operation reliability economy and other aspects. The production technical comparison is as bellow:

Figure2 Rotary Valve RTO structure diagram

Rotary Valve RTO is mainly composed of combustion chamber, ceramic packed bed, combustion system, etc. As shown in figure 2, furnace body was divided into 12 chambers, of which 5 chambers for incoming exhaust gas, 5 chambers for outgoing purified gas, 1 chamber for cleaning, 1 chamber for isolation. Rotary gas distribution valve is driven by motor to rotate continuously and uniformly. Under the action of distribution valve, exhaust gas slowly switches between 12 chambers. The sealing structure of Rotary Valve RTO adopts lip type rubber seal, and the sealing material is made of wear-resistance, temperature-resistance and corrosion-resistance materials.

Figure 3 Process flow and online detection of RTO skid-mounted equipment

Operational aspect

The project has been put into operation since 2018. Based on the five years’ operation, practise has proved that the third generation technology production—Rotary Valve RTO technology is progressiveness:

1、Purification efficiency is up to 99.5%, and the detected value at the chimney outlet is stably less than 20mg/m³ for a long term;

2、Thermal efficiency is up to 97.3%, which can save more than 7000 cubic meters fuel gas compared with the previous treatment equipment;

3、Occupation land is36% smaller than the second generation three-bed RTO.

4、The pressure fluctuation during valve switching is very small, only ±25Pa，and the distributed gas into furnace by rotary valve is continuous, there is no on-off phenomenon and no impact on the front-end facilities.

5、There has never been production restriction and shutdown due to RTO equipment, and the unit has never exceeded the emission standard.

The project uses Rotary Valve RTO to achieve the ultra low emission of non methane hydrocarbon ＜20mg/m³. At the same time, the high thermal efficiency of Rotary Valve RTO saves more than 7000 cubic meters fuel gas consumption per day, and finally achieves the dual benefits of environmental protection and energy conservation.