Prospects for industrial application and technology development of VOCs waste gas treatment

1 Introduction

Volatic Organic Compounds (VOCs) refer to organic compounds with a boiling point of 50-260 ° C under normal pressure. In recent years, VOCs gas pollution has received more and more attention. VOCs waste gas seriously pollutes the environment and endangers human health. Therefore, it is very important and urgent to try to control and control its pollution. This paper mainly reviews the principle of VOCs waste gas treatment technology and the industrial application of VOCs waste gas treatment in a certain branch of Sinopec, and looks forward to the development direction of VOCs treatment technology.

2. Industrial application

2.1 Main process technology selection

At present, there are many domestic oil and gas recovery process technologies: activated carbon adsorption vacuum regeneration technology, membrane separation recovery technology, condensation oil and gas recovery technology, oil and gas collection to low pressure gas or furnace incineration technology.

2.1.1 Comparison of recycling processes, the list is as follows

2.1.2 Project Process Selection

The 15# tank area and the 17# tank area of ​​a certain branch of Sinopec are mainly triphenyl. Through the analysis of various oil and gas recovery processes, comprehensive process technology, workshop management, site layout, investment estimation and other factors, combined with the ongoing construction facilities in China, it is proposed to tank top oil and gas 15# tank area, 17# tank The districts are connected in a centralized manner, and after being boosted by the induced draft fan, they enter the low-pressure gas pipeline network and are optimized and improved on the basis of this technical scheme.

2.2 Tank top gas collection to low pressure gas process technology program

2.2.1 Tank top breathing gas collection system

The collection of gas in the tank area is a key factor for the effective recovery of the breathing gas. To ensure the safety of each tank and to ensure the effective gas delivery, it is necessary to equip the fire arrester (detonation type) and the oil and gas recovery breathing valve. After all tanks have been connected, the emergency relief valve remains on the tank. In order to ensure the safety of the tank area, a nitrogen sealing system should be properly installed in all tanks, and a detonation type flame arrester and a shut-off valve should be installed at the top of the tank top. At the same time, it is necessary to install an oil and gas recovery breathing valve and a safety relief device at the top of the tank.

2.2.2 Oil and gas recovery process principle and process

The tank top oil and gas enters the oil and gas recovery main pipe through the shut-off valve and flame arrester on the oil and gas recovery branch pipe of each storage tank to ensure the transportation of oil and gas. The oil and gas recovery main line is equipped with a frequency-controlled oil and gas transmission fan, and the fan outlet goes to the low-pressure gas collection system.

2.2.3 Security measures

(1) Add or improve nitrogen sealing facilities for existing storage tanks to ensure reasonable setting and effective operation of nitrogen storage systems for each storage tank. A safety pressure relief port is added to the top of the tank.

(2) A gas phase communication pipe is arranged between the same oil storage tanks, and in order to avoid mutual influence between the storage tanks under fire conditions, a flame arrester is arranged at each of the storage tank outlets.

The flame arrester uses a product with good fire resistance, and the resistance drop should not exceed 0.3KPa.

(3) in the receiver outlet (ID fan inlet) and installation of oxy-line detector, monitors the oxygen concentration in the vapor space within the tank and the low-pressure gas into the system in real time, while the high alarm and fan outlet pipe control valves chain, when When the oxygen concentration reaches the high concentration value, the alarm will be closed, and the induced draft fan will be closed, and the nitrogen will be added to the system until the detection index reaches the set requirement.

2.2.4 Main technical indicators

(1) Device scale

15# tank area, induced draft fan displacement 1000Nm3 / h, one; 17 # tank area, induced draft fan displacement 1000Nm3 / h, one. The above reference to the nuclear of similar devices in China

The result is determined.

(2) Control of emission gas index

Non-methane total hydrocarbon pollutant discharge port: removal efficiency ≥95%, 120mg/m3

Benzene pollutant emission limit: 4mg/m3

Toluene pollutant emission limit: 15mg/m3

Xylene pollutant emission limit: 20mg/m3

2.3 VOC reduction calculation According to the “ Energy Conservation Guidelines for Petroleum Reservoir Design”, calculate the large respiratory loss (1.2.3 emissions) of high saturated vapor pressure, and calculate the existing data:

Breathing gas emission concentration: 37g/m?

Average amount of large respiratory emissions (approx.): 460m?/h

Annual VOC reduction = (about) 37g / m? * 150m? / h * 8000 hours = 136 tons.

3, summary

(1) There is a lack of comprehensive detection data of respiratory gas composition, gas volume, temperature and pressure in each storage tank area. It is recommended that the owner analyze and test the different tanks in different time periods to provide a reliable basis for further design work.

(2) There are still few mature cases of oil and gas recovery facilities in light oil tank farms of domestic petrochemical enterprises. It is recommended to further investigate and demonstrate the domestic and international oil and gas recovery technologies, and learn from the existing mature and mature technologies to optimize the process plan of this project. Safe and reasonable long-term operation after the facility is put into use.