Mechanical Atomizing Desuperheater - Copes-Vulcan - #2

After sufficient time, all of the liquid is vaporized, resulting in final fluid flow at the desired lower temperature. The operation is quite simple.

Cooling liquid flow is controlled by a valve which

responds to changes received from the tempera­ture controller or temperature control system. This liquid then passes through the main tube

of the desuperheater to the spray nozzle and discharges into the header as a fine spray. By

controlling the flow through the spray nozzle and maintaining proper header velocities, good reliable temperature control is obtained. Speed

of response is optimized by:

1) The proper range selection of the

temperature controller

2) Placement of the controller as close to the valve as possible

3) Use of a valve positioner

4) Precise throttling of the cooling liquid valve

The cross section of the MA's tube is designed to minimize problems of mechanical vibration associated with compressible fluid flow. For example, as the main fluid flows past the desuperheater, vortices are formed and

dissipated at a frequency dependent on the velocity, viscosity and diameter of pipe. The

desuperheater has been designed to minimize problems associated with vibration so that tube failure will not occur.

Each nozzle is tailored to meet a specific set of

operating conditions. In addition, the nozzle design optimizes the cooling liquid particle size

so that quick evaporation can take place. If the liquid was merely pumped into the line without a spray, control problems and liquid fall-out might occur. If liquid falls out of the main fluid and

settles on the pipe, thermal stress and cracking

might occur. The MA Desuperheaters produce rapid absorption of the liquid by mechanically

producing fine droplets. The surface area per unit volume of liquid exposed to the hot fluid is large,

thereby producing quick evaporation.

The MA-I / MA-IU is a mechanical atomizing desuperheater that is generally used for applica­tions which feature steady loads. It is particularly designed for rugged service and can maintain final temperature to within 20°F (11°C) of satura­tion. In addition to steady load service, it is often used for attemporating applications, and performs equally well for both.

Maximum cooling liquid capacity is 25,860 lbs/hr (11,700 kg/hr) at a nozzle differential pressure of 160 psi (1100 kPa) when using 100°F (38°C)

water. Multiple units or other models can be installed in a header for higher capacities.

This model is available in two mounting options. The MA-I is designed for welding to the pipe line and the MA-IU is flange mounted. The MA-IU also offers mounting commonality with other

'U'-series desuperheaters (MA-IIU, MNSD-V and SAMN-U).

The MA-I/MA-IU can be installed in pipe headers,

elbows, tees and similar fittings. The main line suffers no appreciable pressure loss due to its restriction. No special supports are required for installation.

The higher the main fluid velocity the better the

desuperheating, since, with higher velocity, a shorter distance is required to achieve mixing. The temperature sensing element should be

located approximately 40' (12m) downstream

from the desuperheater.

The DeZURIK/Copes-Vulcan MA Desuperheaters reduce steam or gas temperatures by introducing

cooling liquids directly into the hot fluid. Temp­erature reduction is essentially a matter of heat

transfer, where the cooling liquid is placed in direct contact with the hot fluid and receives the necessary heat for evaporation.

Control Valve

Steam

Temperature Controller sends signal to cooling water control valve, which in turn regulates flow of water to mechanical atomizing desuperheater.

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