Apparatebau GmbH

TECHNICAL INFORMATION DENOX 2013

CALDYN DeNOx-System

Principle

For the NOx reduction in flue gasesusually two industrial processesare used:

§ selective catalytic reductionSCR§ selective non-catalytic reduction

SNCR

In both processes theenvironmentally harmful nitrogenoxides are converted into nitrogenand water by adding a reducingagent. As a reducing agent ammoniaor urea solution can be used, sincethey react selectively with NOx.Typical areas of applications are theNOx reduction in the exhaust gasesfrom:

§ cement industry§ oil, gas and coal combustion§ waste incineration plants§ gas / diesel engines§ gas turbines§ wood incineration plants

Denitrification employing theSCR method

With the SCR method the nitrogenoxides are reduced to molecularnitrogen using a catalyst. Thereducing agent is injected attemperatures from 200°C to 450°C.In order to guarantee ahomogeneous distribution in theflue gas a static mixer is foreseenin most systems.An important factor for a successfuloperation of the system is theatomising technology.CALDYN has more than 20 yearsof experience in this field andprovides the necessary atomisinglances as well as the respectiveengineering. CALDYN guaranteesthe complete evaporation of theinjected liquid before the gasreaches the catalyst respectivelythe static mixer. Extremely shortevaporation distances are achieved,while also smallest channels canbe used.

Denitrification employing theSNCR methodWith the SNCR method thereducing agent is directly injectedinto the hot flue gases attemperatures from 900  °C to1100 °C. The water in the solutionevaporates and the reducing agentreacts with NO to water andnitrogen. At temperaturesexceeding 1100 °C the addedNH3 is increasingly oxidized. Attemperatures below 900 °C therate of reduction decreasesleading to an increased ammoniaslip.As no static mixers can be used dueto the high flue gas temperatures, ahomogeneous injection of thereducing agent in the flue gas isrequired. In order to observe thelegal limits an optimumdimensioning and regulation of thesystem is essential.For this method CALDYN providesthe complete atomising technologywith engineering as well as thepump and regulating stationincluding the PLC control system.

Advantages of the SNCR method

§ low capital investment§ no additional apparatus in the flue

gas system (direct spraying intothe boiler, reheating chamber,etc.)§ no pre-dedusting required§ quick retrofitting possible§ no catalyst required

It depends on the atomisation!

Nozzle CSL was developed byCALDYN (German patent 1976) andhas been proven as a very robustand economical sprayingtechnology over decades. Liquidand gas are mixed at low velocitiesin a mixing chamber andaccelerated to the sonic velocity ofthe two phase mixture. Theatomisation is achieved by thepressure jump at the outlet of thenozzle when the mixture is

expanded in a gas atmosphere (seethe following figure and respectivelythe Technical Information CALDYNnozzles CSL 2013).

The atomising system is the mostimportant component of the SNCRsystem. Particularly the evaporatingdistances and the jet throw of thenozzles have to be considered whendimensioning the SNCR system.The spray jets of the nozzles have topenetrate the flue gas withoutcausing lump formations anddamage due to incompleteevaporation.Specially developed softwareassists our engineers in the systemdesign.

Software for the design of CALDYNnozzles CSL

Analysis of the droplet velocitydistribution with a PDPA system

Working principle of the CALDYNnozzle CSL

Characteristics

CALDYN nozzles CSL generate adefined and narrow droplet sizedistribution. A variation of the jetthrow and the droplet sizedistribution can be achieved bychanging the liquid flow rate and thegas pressure. The liquid flow ratecan be regulated from zero tomaximum design flow rates.The following figure shows the jetvelocity profile of a CALDYN nozzleCSL.

The combination of single nozzlesin a multiple orifice cluster or severalnozzles in line (see the TechnicalInformation CALDYN nozzlesCSL  2013) allows an optimumadaptation to different duct ortower cross sectional areas.

Calculated jet velocity profile of aCALDYN nozzle CSL

3D-CAD model for a pump and regulating station with control box (2 lines)

Control system

Depending on the contents of NOx inthe clean gas the spraying system isautomatically and continuouslyadjusted to the varying parameters.Due to changing temperatures in theflue gas several levels of nozzlesare installed. For each range oftemperature the respective level isused. Thus operating costs andammonia slip are reduced.

Control box with touch panel mountedat the regulating station

In the CALDYN system specialcontrollers in the pressure air linebefore the lances keep the air flowrate constant.

While using more than oneatomising lance the controllers arebalancing the liquid flow at thelances automatically. This preventsstratification in the gas stream dueto different liquid flows at the lances.

Design

The lances are made out of heatresistant stainless steel. Anadditional cooling system is usuallynot required. Optional the lancescan be designed with protectiontube and barrier air connection.

SNCR lance with protective tube andbarrier air connection

Typical SCR lance

Lance with variable built-in length, withquick coupling, suitable for small built-indiameters

Scheme SNCR method

Valve racks for l iquid and pressure air distributionat lance level installed in a box for dust protection

Packing of a SNCR system

Lance level with urea line, pressure air line and barrierair line

Pressure boosting station and pump station for unloadingof ammonia water

Pump and regulating station with tank for dilution water

Lance level with urea line, pressure air line and barrierair line

Stainless steel tankfor ammonia water(cement industry)

PE tank double-walled for urea solutionFRP tank for urea solution, double-walled with surfaceheating and insulation

Stainless steel tankfor urea solutionand PE tanks forwaste water(cement industry)

Main advantages of the CALDYN system

§ Low energy consumption § No additional lance cooling§ Efficient use of reducing agent § Little maintenance required§ Wide range of regulation § Long wearing and plugging-free nozzles§ Easy installation / retrofitting

Scope of SupplyThe CALDYN scope of supply includes the engineering, delivery of lances with nozzles CSL, atomising systems withspecial design on customer’s request for DeNOx-systems as well as complete plants. Detailed information is availablefor further applications of the CALDYN nozzle CSL (quenching systems, spray absorber, evaporation of waste water,aerosol enlargement, etc.).

ReferencesCALDYN has delivered DeNOx systems and atomising lances for denitrification plants to the following companies:

Grashofstraße 12, D-76275 EttlingenTel. ++49-7243/5403-0 / Fax ++49-7243/5403-99

E-mail: info@CALDYN.de / Internet: http://www.CALDYN.de

Apparatebau GmbH