Unicon System

D400 Series
Nozzle Spray Steam Desuperheater

Key Features & Benefits | Technical Data | Performance

Technical Data

Basic Design Standard : ASME B16.34

General

The selection of optimum equipment and an appropriate piping plan is necessary to achieve excellent temperature control.
Guidelines for selecting equipment and precautions for the piping plan are provided in a separate UNICON technical book

Selecting a Desuperheater

When selecting a desuperheater, it’s important to understand the type of equipment that will use the desuperheated steam.
In particular, you should carefully consider the operating conditions, including the range of load fluctuations in downstream equipment and the acceptable range for drainage.
It’s also essential to account for the conditions of the cooling water, auxiliary steam, and any transient states during plant start-up and shutdown.
Therefore, when designing a new plant, special attention should be given to the desuperheater design.
It is recommended to select the desuperheater and configure the control loop through detailed discussions with the manufacturer’s engineers.

Control Range for the Valve

To maintain stable and accurate temperature control, the cooling water control valve must operate smoothly across the entire load range.
It should effectively regulate the cooling water flow required during high-load conditions while also precisely controlling the minimum water flow during low-load conditions to match the downstream requirements.
As the load decreases, the steam temperature at the desuperheater inlet typically drops, necessitating a turn-down ratio for the cooling water control valve (the ratio of the minimum controllable Cv value to the maximum Cv value) that is considerably higher than that of the desuperheater itself.

Key Features & Benefits

Basic Design Standard : ASME B16.34

Wide Range of Design Options

Broad Selection of Nozzle Sizes

Erosion-Resistant Materials

Designed with materials that ensure long service life and reliability in harsh conditions.

Easy Maintenance

Simple Installation

Optimized Design

Swirled Discharge Nozzle

Performance

High efficiency atomization.
High rangeability variable area spray unit.
Accurate and repeatable control of fluid temperature to within 6 °C, providing appropriate installation and instrumentation are used.
High spray water pressure capability.

D410M Multiple Variable Spray Nozzle

Multi-variable nozzle desuperheater is used as a primary attemperator (inter-stage) and a secondary attemperator (final stage) to regulate the output temperature of the boiler/HRSG.

D420 Venturi Nozzle

Venturi-type desuperheater is used for temperature control of steam in small-sized pipes. The spray water is controlled through a separate spray water control valve.

D410S Variable Spray Nozzle

Desuperheater with a single variable nozzle is used for desuperheating steam in small and medium-sized pipes.

D410SM Multiple Variable Spray Nozzle

Desuperheater with several variable nozzles is used for desuperheating steam that requires large spray water flow quantities.

D410V

Combination of D410S or D410SM and a control valve is used for desuperheating steam that requires a high rangeability of spray water.