U.S.A. demands MAZDA Desuperheaters for critical applications         

Manufactured by MAZDA Limited in India.
Marketed by Croll Reynolds Company Inc, U.S.A
Installed in one of the electric power plant through Alstom power U.S.A.

PIPE BOWING PROBLEMS SOLVED IN ONE OF THE MAJOR POWER PLANTS IN U.S.A.

Application

At a reputed power plant in the USA, a Pressure Reducing Valve controlled the pressure and flow.Stringent requirements of steam demand existed and varied from 800 lbs/hr to 18000 lbs/hr. Pressure demands also varied from 286 psig to 666 psig, which needed to be reduced to 300 psig. The steam temperature of the steam was 1000°F. The requirement: to bring down the temperature of the steam to 700°F by injecting water. Extreme turndown presented a design challenge, even for the most seasoned engineering staff.

Statement of problem

The existing Desuperheater functioned perfectly between steam flows from 8000 lbs/hr to 18000 lbs/hr. However, when the steam demand dropped below 8000 lbs/hr,condensate would be formed and get carried downstream into the piping system. This resulted in an uneven temperature profile over the cross section of the pipe to arch or hump with expansion. The lower section of the pipe was driven beyond the yield strength of material, causing permanent deformation (stretching ). When the temperature around the piping cross section reached equilibrium, the bottom of the pipe deformed longer than the top, inducing a large bending moment into the pipe, forcing it into a bow shape. This thermal bowing harmed in two ways: (1) Permanent deformation of the material in the bottom of the pipe that can initiate fatigue cracks and accelerated creep damage. (2) This action accounted for large bending moments and deflections on the piping system that were not accounted for. This contributed to overstressing of pipe Material and also damage to supports in other locations.
This ultimately lead to frequent replacement of the downstream piping and costly premature failures.

MAZDA solved the problem by supplying the most efficient form of steam desuperheater : “State of the Art” - Laval Jet Atomising Desuperheater.

Summary

Since adequate steam velocities were not maintained, installation of Pipeline desuperheaters was ruled out. We recommended an appropriate plant layout and control philosophy, and our representative assisted with the start up of the facility and successfully commissioned the desuperheater.
With the ability to operate under large turndowns and stringent process conditions, Mazda desuperheaters provide a cost effective, energy efficient means of meeting critical and complex needs for process and power plants.

Schematic Diagram Installation Of Steam Atomising Desuperheater