Desuperheaters

In many paper mills steam is superheated and distributed at high pressure for efficiency reasons. The pipe sizes required to transport the high pressure steam are smaller due to the low specific volume of the steam, and turbine efficiency is optimized when high pressure superheated steam isused. Kadant Johnson desuperheaters are designed to reduce the temperature of superheated steam for optimal heat transfer and efficiency.

Spray Type
The spray type is the most simple design and includes a spray nozzle and thermal liner. It is used only in conditions where the load remains constant. The cooling medium is injected into the superheated steam through a nozzle and the temperature is reduced by evaporative cooling.

Venturi Type
The venturi design uses the velocity of the steam to atomize the cooling water and effectively operates over a wide range of operating loads. As the cooling medium enters the desuperheater, it is preheated in a circulatory chamber around the entrance of the secondary or inner venturi. It is then introduced into this secondary venturi through a series of specially designed jet ports where the final atomization by the steam flow occurs. The venturi design minimizes pressure drop so that the downstream pressure is nearly equal to upstream pressure.

Ejector Atomizing Type
The ejector atomizing desuperheater is similar to the venturi design, but provides for a high turndown capability of 50:1. Proper sizing of auxiliary equipment such as water control valve, steam valves, etc. is critical to achieve optimal performance.

Kadant Johnson desuperheaters are custom designed for each application and are available in various materials. The simple yet efficient design allows for direct installation into the stream pipeline with flanged connections. All desuperheaters can be installed in either horizontal, vertical or diagonal pipelines providing there is sufficient straight run both upstream and downstream of the desuperheater.

Features

• Desuperheater sizes range from 2" to 30" for wide application
• Steam system knowledge is applied to design and sizing
• Superheated steam temperature reduction improves heat transfer properties
• No moving parts or special supports required
• Optional control package available