siemens - Public Service Commission

4.3.2 Other Reasons For Selecting The Proposed Bundle
The remarkable features of the 4-pass arrangement were recognized by worldwide
MSR manufacturers in the mid-’70s. Virtually all original equipment designers of
MSRs have various patents covering different elements of this fundamental 4-pass
design (TEI has two). The conception and evolution of the 4-pass came as a result of
the inadequacy of the 2-pass to provide long-term reliable equipment. In addition,
the 4-pass proved not only to operate more efficiently, but also to produce a higher
performance, as compared to the primitive 2-pass.
The specific features comprising the proposed 4-pass which is considerably
improved over the existing OEM design are described below and are mentioned
throughout this technical section.
The performance advantage of the octagonal High Capacity type field layout vs. your
existing rectangular one is a sufficient advantage to prefer this type of design. But
there are other benefits also, such as a heavier bundle which is less susceptible to
lift; lower number of tube rows which reduces tubeside channeling and which
increases the cross section of the upper flow channel, thus reducing pressure drop
and enhancing longitudinal, even cross flow distribution. Moreover, due to larger
number of tubes, each tube is subject to a lesser heat duty, which is a desired state
during abrupt change in unit load.
The replacement reheaters offered here are of customized design which completely
eliminates existing problems typical to the OEM equipment and furthermore,
enhances the MSR performance. The design was especially developed by TEI for
replacement of reheaters in MSRs of the same make as the ones at your CR-3.
The design includes mechanical features which provide for structural integrity and
for improved operation. It also provides for easy maintenance.
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