1. Process Flow Diagram
2. Process description
The workshop organic waste gas is collected through the suction hood, and under the action of the exhaust fan, it is transported through the pipeline into the dry filter, and then into the Activated carbon The organic pollutants in the adsorption device are adsorbed by the activated carbon, and the purified gas is discharged after being pressurized by the fan. After the adsorption of activated carbon is saturated, professional manufacturers shall recycle it after regeneration.
3、 Activated carbon Adsorption principle of
a. The adsorption phenomenon occurs at two different phase interfaces. The adsorption process is the diffusion process at the interface, and the adsorption occurs on the solid surface, which is caused by the residual attraction on the solid surface.
Adsorption can be divided into physical adsorption and chemical adsorption; Physical adsorption, also known as van der Waals adsorption, is caused by the electrostatic force or van der Waals gravity between the adsorbent and the adsorbate molecule. When the molecular gravity between the solid and the gas is greater than that between the gas molecules, even if the pressure of the gas is lower than the operating temperature and the saturated vapor pressure, the gas molecules will condense on the solid surface, Physical adsorption is an endothermic process.
Chemisorption, also known as active adsorption, is caused by the chemical reaction force between the adsorbent surface and the adsorbate molecule, which involves the destruction and recombination of chemical bonds in the molecule. Therefore, the adsorption heat in the chemical adsorption process is greater than that in the physical adsorption process.
In the process of adsorption, there is no strict boundary between physical adsorption and chemical adsorption, and the same substance is often chemically adsorbed at a lower temperature. Activated carbon fiber adsorption is mainly physical adsorption, but due to the presence of surfactant, there is also some chemical adsorption.
b. Characteristics of activated carbon adsorption on waste gas:
(1) The adsorption of aromatic compounds is better than that of non aromatic compounds.
(2) The adsorption of hydrocarbons with branched bonds is physically superior to that of straight chain hydrocarbons.
(3) The adsorption of organic substances containing inorganic groups is always lower than that of substances without inorganic groups.
(4) The adsorption of compounds with high molecular weight and high boiling point is always higher than that of compounds with low molecular weight and low boiling point.
(5) The higher the concentration of adsorbate, the higher the adsorption capacity.
(6) The larger the internal surface area of adsorbent is. The higher the adsorption capacity.
Activated carbon fiber
Activated carbon fiber (ACF), a new type of adsorption material, is a new type of organic waste gas recovery method developed in recent years. It is considered to be an effective new method to recover and purify organic waste gas, which has attracted great attention of researchers and related enterprises in recent years. Compared with traditional activated carbon, activated carbon fiber has the following excellent characteristics:
1) Large specific surface area and high effective adsorption capacity;
2) Fast adsorption and desorption, low energy consumption and easy regeneration;
3) High strength and long service life;
4) Various shapes, convenient for engineering application;
5) It can adsorb low concentration gas;
6) Strong adsorption selectivity.
Activated carbon fiber organic waste gas recovery device
Taking the typical three box adsorption device in the activated carbon fiber organic waste gas recovery device as an example, its equipment composition, process flow and technical characteristics are analyzed.
Equipment composition
The adsorption equipment is composed of induced draft fan, surface cooler, filter, adsorber, layered tank, etc. The operation of the whole system is controlled by PLC program, and the adsorber is automatically switched to alternately operate the adsorption, desorption and drying process.
technological process
Volatile organic gas passes through a certain pre-treatment device first, and then through the filter to further remove impurities in the tail gas, so as to ensure that these impurities do not occupy the pores of the activated carbon fiber, affecting the adsorption efficiency and service life of the activated carbon fiber; The filtered tail gas is introduced into the adsorption equipment through the fan.
Activated carbon fibers that have absorbed a certain amount of organic solvents are desorbed with saturated water vapor. After the desorption is completed, the filtered outside air is sent to the adsorber for drying by the fan, so that the activated carbon fiber bed is cooled and the residual steam is removed, so that the activated carbon fiber can maintain a high adsorption efficiency. The dried adsorber enters the next working procedure cycle for adsorption.
The desorbed mixed steam containing organic matter enters the condenser for primary condensation, and the condensate is cooled by the plate condenser. The condensed organic matter and condensate water enter the layering tank, which is stratified by gravity. The upper organic matter automatically overflows to the storage tank, and then is sent to the adsorption recovery equipment by the transfer pump; The condensate in the lower layer is discharged into the wastewater treatment system.
Technical characteristics
(1) Reasonable structure
The adsorption core is a cage structure, which has the characteristics of less activated carbon fiber consumption and large treatment air volume, and can greatly reduce the cost of organic waste gas treatment.
(2) High adsorption rate
Due to the specific surface area of activated carbon fiber, its adsorption rate can reach more than 95%. The use of zhuanli technology can achieve multi-level adsorption, which can achieve very high adsorption rate. It is an adsorption device that can meet the stringent environmental protection emission requirements in the world at present.
(3) Low operation energy consumption and cost
Due to the low energy consumption of activated carbon fiber desorption and regeneration, as well as the small air flow resistance and fan power of the activated carbon fiber winding core, the gas consumption and power consumption of the activated carbon fiber organic waste gas purification and recovery device are relatively low in operation.
(4) Fully automatic control, unattended operation
It is centrally controlled by German Siemens programmable controller, integrated with solenoid valve and German Festo cylinder to execute actions, with high reliability. The simulation panel designed according to the process flow shows that the operation status can be clearly seen at a glance, and has fault detection and indication functions. Strong reliability, simple operation and easy maintenance.
(5) Safe and reliable, suitable for places with explosion risk
Explosion proof fan and pump are used. The control cabinet and pneumatic cabinet adopt positive pressure explosion-proof technology, the external signals are connected through the safety barrier, and the system is grounded to ensure the safety of the device.
