Reduce Toxic Emissions : Waste Incineration & Hot Gas Filters

By: Anna Stenning

Waste incineration is probably one of the most effective ways of getting rid of factory and industrial products. The problems of trying to expel wastage are that there is not enough space on the earths ground to keep them. In addition, they cause issues to the environment as well effect the top soil of the earth's ground. Hot gas filters are used for trapping fine particles after coal combustion reducing the risk of pollutants being exposed into the atmosphere.

What Is It?

Coal is the most abundant fossil fuel; the combustion of coal requires hot gas filters, strong enough to take the pressure of the combusted fuel and the corrosive and erosive particles. Furthermore, these filters will also need to be cost effective, withstand the corrosion, elevated heat, temperature transients and thermal shock.

Hot gas filters are usually available as porous candles made from sturdy rigid ceramic, fibre ceramic, sintered metal or for lower temperatures porous plastics. These work by collecting the more toxic and corrosive particles, thus producing clean coal combustion techniques.

Waste incineration is quite literally burning all waste matter. They are good alternative to other waste disposal methods such as land filling, and is especially popular in places like Japan whereby land space is scarce for land filling. It is also reduces the emission of toxic waste and controls the level of waste disposal.

Small-scale waste incineration is referred to burning household waste and is usually uncontrolled compared to a medium scale waste incineration. This is usually in reference to an in-house hospital incinerator, used specifically for disposing hospital equipment. Larger scaled incineration is usually for municipal waste. They can deal with between 100 to 1000 tons of waste per day and the waste used can vary in size, weight, calorific value and characteristic.

Problems Of Incineration

It is argued that incinerating waste is problematic in that the exhaust emitted are known as dioxin and furan. These have been argued to be a cause for concern if emitted in high amounts, however, a technique known as scrubbing can help prevent and reduce the emission numbers. However, the process generates many of the gaseous waste, making the health hazard of these emissions is a continuous subject of controversy.

The problem with hot gas filtration is that it can only filter out pollutants. Other particles such as gas or vapours can pass through even the most efficient of all filters and often need to be removed through making it react to a solid known as a sorbent. This technique is called dry scrubbing. The reactions are usually quite slow; however, they work well as the sorbent is blown into the gas stream created a fixed bed of sorbent. This then creates tortuous paths, in which the gas would travel through and then react with the sorbent. The different sorbents that can be used are bicarbonate of soda, or powdered/hydrated lime to remove acid gases.

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