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Application HYGROPHIL-H 4230Humidity measurement in flue gas for the detection of tubecracks in incineration plants and power plants

Advantages for the operator:- tube cracks are detected at an early stage

even behind insulation - major damage of the boiler are prevented- availability of the boiler is increased- durability of the boiler is increased

Advantages for the insurance company:- fewer / lower damages- lower payments in the event of damage

Short description

HYGROPHIL-H is a humidity measuring system which works according to the “psy-chrometric principle” and is characterized by high precision, good reproducibility andhigh long-term stability, even in corrosive gas mediums.HYGROPHIL-H is certificated for the measurement of flue gas humidity in accor-dance with the Federal Immission Control Ordinance (BImSchV.), no. 13 and no. 17,and is applied in power stations, waste incineration plants and large combustionplants for the continuous measurement of flue gas humidity.

The reason for „tube cracks“In industrial boiler systems with different types of firing (coal / gas / residual waste /sewage sludge etc.), leakages can develop on flanges and heat exchanger pipes.These leakages frequently cause tube cracks and major boiler damages. They startwith minor hair cracks resulting from the thermo-mechanical influence and from thefatigue of material. Due to the high system pressures, the gas blown to neighbouringpipes or boiler walls results in a kind of chain reaction which rapidly causes majorboiler damages if the leakage is detected too late or isn’t detected at all.When the leakage begins to develop, there is often only a very thin jet of water orwater vapour under high pressure. This jet mixes with the dust particles in the boilerand has an effect comparable to a sand blaster. If this abrasive mixture is active for alonger period of time, it can result in holes in the neighbouring pipes or boiler walls. Ifthis procedure is not prevented early enough, it causes damages with high repaircosts and down-times.

Early detection of damages by means of continuous humidity measurement inthe raw gas Due to the reliable and extremely sensitive measuring technique applied byHYGROPHIL-H, it is possible to detect even the slightest increase of the humidity

Application HYGROPHIL-H 4230 Status: Mai 2003 Page 2

value resulting from leakages in the steam generator. Thus, the operator can take atan early stage the steps required to prevent major boiler damages.The humidity measurement with HYGROPHIL-H particularly allows for the early de-tection of leakages hidden behind insulations.

Due to the continuous, reliable and long-term stable determination of the hu-midity values by means of HYGROPHIL-H, the following measures taken by theoperator can prevent major damage caused by steam leakages

• Evaluate automatically the flue gas humidity in the boiler plant• Lower the steam load (distribution to other boiler plants)• Switch off the boiler plant with short-time repair

Typical progression of the gas humidity in the case of a damage in the vaporizerSource: Public services of Wuppertal Stadtwerke, combined heat and power plant Elberfeld

Typical progression of the gas humidity in the case of a damage in the fluid bed cooler Source: Public services of Wuppertal Stadtwerke, combined heat and power plant Elberfeld

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Due to the application of HYGROPHIL-H, damages that would have been far biggercould be prevented.

Damaged pipe in the vaporizer systemSource: Public services of Wuppertal Stadtwerke, combined heat and power plant Elberfeld

Damaged pipes in the fluid bed cooler Source: Public services of WuppertalStadtwerke, combined heat and powerplant Elberfeld

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Power plant process shown at the example of a lignite-fired power plant:Source: VEAG power plant Lippendorf

Location of test point:The humidity measurement is located after the flue gas cooling and before theflue gas desulpharising plant. Thus, damaged pipes in the steam generatorand in the flue gas cooling system can be detected.

Location oftest point