ABB Contrac Precise Continuous Control of Water Injection Control Valves for Steam Boilers with Superheaters

Contrac - Electric Actuators

Introduction

The water injection valve on a steam boiler controls the amount of cooling water injected into the superheated steam in the superheater and reheater.

The amount of water injected is decisive for the temperature of the steam inside and at the output of the superheater.

Too much water injection can lead to excessive cooling of the steam, which negatively affects efficiency.

On the other hand, insufficient water injection leads to excessive steam temperature and pressure.

The risk of damage to the superheater, turbine and downstream components increases as a result.

For optimal operation of the superheater at the lowest possible steam temperature and the highest possible hot steam temperature, the

continuous and precise mass flow control of the injected cooling water is first required.

Depending on the operating conditions, this requirement means that very small amounts of water need to be supplied, thus requiring highly accurate positioning in disproportionate areas of the valve.

The operating environment is extremely harsh.

In addition, the ambient temperature in the superheater area can be very high.

The Solution

The use of a Contrac continuous electric actuator ensures ideal positioning of the water spray control valve.

Even high temperature models with ambient temperatures up to 85 °C can achieve S9-100 % duty cycles without restriction.

The special design of the Contract actuator, with oil-lubricated spur gears and electrical components for S9-100 % duty cycles, allows high precision in the positioning of the sprinkler valve.

High precision and true continuous positioning of the water spray valve is achieved.

Due to the special design and operating principle of the Contrac actuator, the dead band is only ±0.05 %.

This precision allows for highly accurate positioning of all types of valves over the entire range.

All components are IP66 rated and can be used even under the harshest environmental conditions.

CONTEC motorized linear actuator type RSD with power electronics unit EBN853

Oil-lubricated spur gears with ball bearing spindles ensure

- wear-free operation

- Max. operating temperature 85 °C

- Robust design

- Precise control of the injected water by means of high-precision positioning

- IP rating IP66