2. What is VOC Abatement Equipment ?

What is VOC Abatement Equipment ?

Welcome to Nichias web page for introduction of VOC removal technique

It is equipment to combust, recover and refine VOCs which are exhausted from facilities. Do you know various types of VOC abatement techniques, such as physical adsorption by activated carbon and direct fired combustion by incinerator, are available ?
In this section, VOC abatement overview and removal techniques are introduced for your information.

What is a VOC Abatement System ?

It is a system to combust, recover and refine Volatile Organic Compounds (VOCs) which are exhausted from facilities. Due to the usage of VOC abatement systems, VOCs in the targeted exhaust gases can be combusted and purified air can be released to the atmosphere.

Generally, the implementation of VOC abatement systems have been carried out in the following order.
(1) Measuring and monitoring the environment by a system supplier
(2) Planning for the removal system
(3) Proposing the system design
(4) Installation and commissioning of the system
(5) Maintenance service after installation

Also, various types of VOC removal techniques, which can minimize operating costs by recycling organic solvents included in the recovered liquid, can remove malodor and are not necessary to assemble on site, have been developed and supplied commercially.

VOC Removal Technique

Both combustion and adsorption techniques are available for VOC removal.

Combustion Technique

Combustion is a technique to decompose VOCs into carbon dioxide by thermal oxidization and has been used for removal systems in many facilities.
There are three different combustion methods.
- Direct Combustion System by flame incineration
- Regenerative Combustion System
- Catalytic Combustion System

In a direct combustion system, targeted VOC laiden air is incinerated by a burner.
Combustion temperature is around 750 to 850 degrees C and VOCs are decomposed efficiently. The structure of combustion devices are very simple and its installation is inexpensive, and the maintenance for the systems is generally easy.
These systems have been used for VOC removal in paint booth, print booth and chemical processes. However, it is not recommended for use when the process inlet airflow volume is large and its concentration is low because fuel consumption will be high. Moreover, there is a risk that nitrogen oxides will be easily generated.

In a regenerative combustion system, VOC laiden air is passed through the heat storage materials (Honeycomb-structured Ceramics and Saddles) and is decomposed with regenerative combustion. It can maximize thermal efficiency up to about 95% and its self-combustion concentration can generally be decreased.
These systems have also been used for VOC removal in paint booth, print booth and chemical processes. However, they are heavy and expensive and have a risk that they are not suitable for ‎intermittent operation.

In a catalytic combustion system, targeted VOC laiden air is decomposed by thermal oxidization at a lower combustion temperature around 350 to 450 degrees C together with a catalyst function. They can save auxiliary fuel expense for low temperature combustion and can generally reduce nitrogen oxide generation.
These systems have been used for VOC removal in paint booth, print booth and chemical processes. However, there is a risk that activated energy of the catalyst will be lost due to catalytic poisoning. When silicone, phosphorus and sulfur are deposited on the catalyst pore, catalyst function is drastically decreased due to catalytic poisoning.

Adsorption Technique

Adsorption is a technique to adsorb VOCs physically by using activated carbon and an incombustible adsorbent (hydrophobic zeolite etc.). Re-use is possible by recovery of VOCs and no intermediate compounds are generated during the process.
These systems have been used for VOC removal in chemical processes, cleaning and air conditioning for clean rooms in the electronics industry. However, they are mentioned as some issues to prevent the deterioration of adsorbent and cost increase.

Other techniques, such as VOC decomposition by photo excitation catalyst, plasma enhanced discharge, ozone oxidization, biochemical processes and VOC ingredient waste liquid treatment have been supplied to the market.
- Decomposition by photo excitation catalyst has a low operating cost.
- Decomposition by plasma enhanced discharge has high effective decomposition efficiency with energy efficient design.
- Decomposition by ozone oxidization or biochemical process is energy efficient and easy maintenance. Each technique offers something unique to the VOC abatement system.