Energy equipment

Humidity control in the preservation of energy equipment

The best way to solve problems in the preservation of equipment

How to preserve equipment and to prolong its serviceability?
How to stop corrosion on the surfaces of energy equipment during is preservation?
How to reduce the costs of equipment preservation?

In order to achieve these goals, it is necessary to choose an effective way to preserve equipment that will provide the best protection of corrosive surfaces from excessive humidity!

During lengthy periods of idle time of thermal and nuclear power plants equipment, parts of equipment need protection from corrosion:

•→ turbine •→ electric filter
•→ boiler •→ feeding electric pump, feeding turbo pump
•→ steam circuit •→ low-pressure vapor over-heater
•→ gas circuit •→ equipment of substations (open switchgears)
•→ generator •→ transformer
•→ condensator •→ cabinets and block boards
•→ system of ash and slag removal •→ reserve containers for extra condensate, feed-up  water, etc.

The main reason for occurrence and development of corrosion, and, as the consequence, for destruction of surfaces of units and mechanisms of the above-listed equipment is uncontrolled humidity.

At high relative humidity of 60-100%, the rate of corrosion processes in the steels is 100 – 2000 times higher than at a lower humidity of 30-40%.

The mechanism and rate of atmospheric (stationary) corrosion depends primarily on the humidity-level of the surface of the corrosive metal.

For example: for boiler steels the critical relative humidity is 60%. At humidity higher than 60% the speed of atmospheric corrosion drastically increases g/m2h. Thickness of steel reduces by up to 0.057 mm / year.

Safe preservation retains the quality of equipment, reduces repair and reconstruction costs, maintains technical and economic parameters of thermal power plants and reduces production costs.

Well-known preservation methods such as

  • maintaining excessive pressure in the steam circuit;
  • preservation with hydrazine-ammonia solution;
  • preservation with inert gas (nitrogen);
  • preservation with ammonia solution or gaseous ammonia;
  • oxidation with oxygen;
  • vacuum drying and ventilation with atmospheric air;
  • preservation with inhibited air;
  • preservation with contact inhibitor;
  • preservation with octadecylamine

have the following disadvantages:

  • repair of surfaces cannot be conducted simultaneously with the preservation;
  • high cost of reagents, complex technology of their storage, preparation and utilization, environmental issues;
  • annual consumption of electricity for conservation of one unit, need for installation of additional equipment – ventilating and air heating;
  • considerable maintenance costs.

Taking in consideration these disadvantages dry preservation techniques are highly recommended.

The best solution for preservation of energy equipment is the system of dry preservation which uses the method of adsorption and installation of dessicant equipment.

The preservation by dry air suggests complete removal of moisture from the preserved volume and decrease of the relative humidity below 40%. Under these conditions the speed of harbor corrosion is reduced to an acceptable level of 0.03 g/m2h and is constant throughout the entire preserved circuit. To exclude the occurrence of “dead zones” during preservation by dry air, special attention should be paid to productivity of dehumidifier that creates the necessary speed along the circuit and the optimum scheme of preservation.

For example, for a 300 MW unit, at the expulsion of circuit NRCH, APS, PPC VD- CVP-CIO ND-IPC-LPC-condenser, the most appropriate dessicant equipment is MDC3000. Increased productivity of this equipment reduces drying time of the preserved circuit. At the end of operation, a hermetically closed preserved circuit is placed in reserve. To prevent suction of moisture from the outside, through space in between the fittings, it is recommended to conduct such expulsions regularly.

The most effective solution for preservation of energy equipment is the installation of desiccant dehumidifiers of Desiccant Technologies Group.

The desiccant dehumidifier of Desiccant Technologies Group maintains the recommended relative humidity and necessary air flow conditions at the preservation of equipment. It prevents development of corrosion.

Equipment of DT Group is used for preservation of

•→ turbine •→ electric filter
•→ boiler •→ feeding electric pump, feeding turbo pump
•→ steam circuit •→ low-pressure vapor over-heater
•→ gas circuit •→ equipment of substations (open switchgears)
•→ generator •→ transformer
•→ condensator •→ cabinets and block boards
•→ system of ash and slag removal •→ reserve containers for extra condensate, feed-up  water, etc.

The advantages of desiccant dehumidifiers of DT Group

  • High drying efficiency at a low energy-consumption level.
  • Efficient operation at low temperatures.
  • Easy installation.
  • Small size and low weight.
  • Possibility to fully automate the process of humidity control.
  • Corrosion-resistant body (stainless steel, aluminum zinc).
  • Compliance with all acting Directives and quality standards of the EU.

Desiccant Technologies Group, European manufacturer of high-tech industrial dehumidifiers, well-accounted for in many industries, produces the most advanced equipment for the effective control of humidity at preservation of equipment.

Installation of DT Group Industrial Desiccant dehumidifiers

  • reduces costs of preservation of equipment;
  • reduces energy-consumption;
  • increases technical readiness of the power station;
  • prevents condensation;
  • prevents corrosion;
  • increases productivity of air-drying equipment;
  • reduces the drying time of preserved equipment;
  • creates the necessary microclimate for preservation;
  • increases the serviceability of equipment.

 

How does the desiccant dehumidifier work?

The air which should be dehumidified (process air) goes through the desiccant rotor. Water molecules are adsorbed in a special silicagel rotor.

Desiccant rotor is regenerated by the second air stream preheated to 90-140 °C. Moisture is removed from the premises in the form of warm moist air.

industrial desiccant dehumidifier

Industrial desiccant dehumidifier DT Group

publisher Energy equipment