The SNCR Process

The advantage of this process is the low complexity of the plant compared to an SCR process, which is operated after the boiler with the aid of a catalytic converter and very often additional primary energy. The SNCR system is installed in the first boiler pass above the furnace and is therefore part of the boiler. The essential fulfillment criterion for the operation of an SNCR process is the supply of the reagent ammonia or urea at the required flue gas temperature (between 850 and 1050 ° C) and the cross section of the first boiler pass. Since the flue gas temperature is very much dependent on the combustion control / regulation, there is also a direct connection to the performance and efficiency of the NOx reduction via the SNCR.

• Low investment costs, since the combustion chamber or the exhaust duct does not have to be converted

• The SNCR process can be retrofitted in almost all existing boilers at short notice, as only the injection nozzles have to be installed for injection into the furnace

• No re-heating of the flue gas necessary

• No energy losses due to pressure losses

• Suitable for a wide variety of fuels

• Sufficiently high degrees of denitrification without a catalyst

• The reducing agents are produced in large quantities and are available worldwide

• No disposal of used catalyst elements necessary

In order to ensure that the reducing agent is always injected into the optimum range of the temperature window, which is most effective in terms of NOX separation, NH3 slip and reducing agent consumption, in modern systems, the individual injection lances, and thus not the entire level, switched depending on the flue gas temperatures at the respective injection points.

The advantages of individual lance switching are:

• Greater efficiency

• Low NOx emissions

• Low NH3 slip

• Low CO emissions

• Low consumption of reducing agents

Interested?
Find out more about the topic on individual lance switching in our paper.

New generation of SNCR technology

Our patented TWIN-NOx® process combines the advantages of the reducing agents ammonia water and urea and thus achieves the best results.

With the TWIN-NOx® process, the different reaction behaviors of urea solution and ammonia water are specifically applied. Both reducing agents are used alternately or as a mixture, depending on the operating conditions. The respective advantages can thus be used alternatively or in combination, depending on requirements, in order to expand or shift the effective temperature range for the NOx separation and thus to significantly improve the performance of the SNCR process.

Interested?
Find out more about the topic on TWIN-NOx in our paper.

Selective cooling is a patented process with which the flue gases are locally and temporarily cooled down to the effective temperature at those points where the flue gas temperatures are too hot. Temperature imbalances can be compensated for with the injection of cooling water (selective cooling) so that each injection lance can be operated in the optimal temperature range in order to increase efficiency and minimize NH3 slip. To ensure that only those zones that are too hot are "selectively" cooled in the event of temperature imbalances, only a single or a group of cooling lances is specifically activated depending on the temperature profile, which significantly reduces cooling water consumption and thus heat loss in the boiler and Slip is kept low. By switching the cooling with water on or off, a second or third injection level for reducing agent can be omitted in many cases.

Interested?
Find out more about the topic on Selective Cooling in our paper.