Standardkessel Baumgarte has the necessary know-how to develop an optimal concept for emission reduction, recovery and flue gas conditioning that is specifically tailored to your requirements.
A suitable process for separating pollutants or solvents from a carrier gas is direct condensation, in application under normal pressure conditions as well as in the positive and negative pressure range.
Two technologies are available for direct condensation for this purpose.
In the spray cooler the waste gas is cooled by direct contact with the cooled liquid in the liquid jet. The liquid itself is adjusted to the desired temperature by indirect cooling, usually in a heat exchanger.
As a result of the continuous supply of liquid, the phase interface between gas and liquid is constantly renewed. The intensive contact causes a washing, absorption or condensation effect and, thus, a mass transfer between gas and liquid. The exhaust gas cools down to condensation temperature, the pollutants and solvents contained in the exhaust gas condense to saturation conditions. The condensate mixes with the supplied liquid and is collected together with the spray jet in the apparatus sump. The liquid is drained off via a level control and the purified gas stream is discharged via a specially designed demister.
If required, the condensation unit can also be designed for operation on discontinuous processes (batch operations) and in the event of fluctuations in the exhaust gas volume. The technology is often used as a pre-separator or quencher for highly loaded or very warm exhaust gas streams as a preliminary stage of further cleaning processes and is also applicable for use in closed exhaust gas systems (e.g. of a dryer or coating system).
For condensation of the components, the exhaust gas is conveyed by means of a blower in a bubble column through the liquid bath, which is cooled to the condensation temperature. The liquid usually corresponds to the composition of the condensate from the exhaust gas stream. The exhaust gas cools in the bubble column to the temperature set in the accumulator below the dew point of the compounds. In the process, the pollutants and solvents contained in the exhaust gas condense out to saturation conditions. The condensate is collected directly in the liquid. If required, the system can be designed for operation in discontinuous processes (batch processes).
As the cooling process of the waste gas is achieved by direct contact with the liquid bath, the bath itself is adjusted to the desired temperature by indirect cooling. Due to the turbulence generated by the exhaust gas streaming through, no plugging/clogging can occur. In this way, the bath cooler constantly cleans itself. Between the exhaust gas mixture and the cooled liquid, there are no separating transfer walls that are prone to fouling. The process is also successfully used when concentration peaks require smoothing in order to make other downstream recoveries and cleaning processes possible at all. The outlet concentration remains almost the same.
The demands of industry on cleaning processes are complex, requiring system solutions and consideration of the individual possible emission reduction measures.
In many cases, waste gas and exhaust air streams can no longer be purified in an ecologically sensible way using a single-stage purification process alone.
Operational experience has shown that, with regard to the constituents and their concentration in the exhaust gas, further process stages usually have to be used upstream and/or downstream as supplements. Official regulations also often demand that process combinations be provided as a complete solution. Combined processes are multi-stage systems in which an adapted process is used for each stage, depending on the volume flow and the pollutant load.
Processes frequently emit waste gas streams with pollutants or solvents of the most varied properties, which have to be considered when condensation is applied.
These include, for example, the pour point undershooting of individual substances and mixed crystals (eutectic), insolubilities or a freezing out of substances from the liquid due to partial solubility. If a single-stage deep-freeze condensation is not sufficient, a pre-condensation stage is installed upstream. The stage is designed according to the required temperature control for condensation.
A typical application is the combination of the spray cooler with the bath cooler. In this case, the spray cooler is used as a pre-separator or as a quencher, for example, in the case of a highly charged, very warm exhaust gas stream or a high water content in the exhaust gas. The pre-condensation is then usually operated at condensation temperatures above 0 °C, the second stage in the low-temperature range. The temperature control, i.e. the selected temperature grading, must be determined for optimum process control depending on the application.
Further processes by combining the cleaning processes with
- Upstream/downstream gas scrubbing for the separation of inorganic pollutants, etc.
- For waste gas streams with short concentration peaks, there is the possibility of using an adsorbent bed to smooth concentration peaks before catalytic oxidation.
- Use of zeolites for concentration for optimised design of downstream catalytic oxidation