PAPERmaking! Vol11 Nr2 2025

Rasool et al.

Repair-rate ( ࣂ ࢐ ) θ1=0.49

Failure-rate ( ࣆ ࢏ ) μ1=0.023

Table 2 . Failure and repair rates of subsystems of stock preparation unit of paper plant

Sr. No.

Sub-system

1 2 3

Storage Tank (I)

Repulping/Slushing (II) Deflaking Process (III) Storage and Mixing Chest (IV)

μ2=0.02 μ3=0.06

θ2=0.75 θ3=0.5

4

μ4=0.011

θ4=0.099

5

Paper Machine (V)

μ5=0.03

θ5=0.65

From Table 3, it is observed that reliability and availability of the stock preparation unit is less in comparison to its weakest subsystem. The maximum MTBF is 90.9090 and minimum is 5.5556 associated with subsystems storage & Mixing chest and deflaking process respectively. The MTBF for the stock preparation unit is 223.276241. Similarly, MTTR of the stock preparation unit is 15.1426537.

Table 3 . RAMD indices for subsystems and system of the Stock Preparation unit

RAMD indices of subsystems

SSI

SSII

SSIII

SSIV

SSV

System

଴Ǥ଴ଶଷ௧ ݁ି

଴Ǥ଴ଶ௧ ݁ି

଴Ǥଵ଼ ௧ ݁ି

଴Ǥ଴ଵଵ௧ ݁ି

଴Ǥ଴ଷ௧ ݁ି

଴Ǥଶ଺ସ௧

Reliability ݁ି

0.955165692 ͲǤͻ͹ͶͲʹͷͻ͹Ͷ ͲǤͻ͹͹͵Ͳͳ͵ͺ͹ ͲǤͻ ͲǤͻͷͷͺͺʹ͵ͷ͵ ͲǤ͹ͺʹʹͳʹͶͶ͸ ሺ െ݁ି ͳ ଴Ǥସଽ଴଴଴଴଴଴଺௧ ሻ ሺ െ݁ି ͳ ଴Ǥ଻ସଽଽଽଽଽଵଶ௧ ሻ ሺ െ݁ି ͳ ଻Ǥ଻ସଽଽଽଽ଼଼ ௧ ሻ ሺ െ݁ି ͳ ଴Ǥ଴ଽଽ௧ ሻ ሺ െ݁ି ͳ ଴Ǥ଺ହ଴଴଴଴଴ଵ଺௧ ሻ ሺ െ݁ି ͳ ଽǤ଻ଷ଼ ଽଽଽ଼ ଵ௧ ሻ 0.849343052 ͲǤͻͲͲ͹Ͳʹͻ͹ͻ ͲǤͻͳͲͷ͵ͷʹͳ͵ ͲǤ͹ͶͲͲ͸ͻͺͲ͸ ͲǤͺͶͺʹ͸ͺͻͷͷ 0.437288184 43.4782609

Availability

Maintainabilit y Dependability (Dmin) MTBF (hrs.)

ͷͲ ͷǤͷͷͷͷͷͷͷ͸ ͻͲǤͻͲͻͲͻͲͻ ͵͵Ǥ͵͵͵͵͵͵͵ ʹʹ͵Ǥʹ͹͸ʹͶͳ ͳǤ͵͵͵͵͵͵Ͷͻ ͲǤͳʹͻͲ͵ʹʹ͸ ͳͲǤͳͲͳͲͳͲͳ ͳǤͷ͵ͺͶ͸ͳͷ ͳͷǤͳͶʹ͸ͷ͵͹

MTTR (hrs.)

2.0408163

21.3043481 ͵͹ǤͶͻͻͻͻͷ͸ Ͷ͵ǤͲͷͷͷͷͶͻ ͻ ʹͳǤ͸͸͸͸͸͹ʹ The effect of variation in failure rates of various subsystems analyzed on reliability of subsystems and stock preparation unit and appended in tables 4, 5, 6,7 and 8. It is revealed that with the increment of failure rate of subsystem there is a steep decline in the reliability of subsystem and stock preparation unit. It is observed that subsystem namely Deflaking is the least reliable among all subsystems having reliability Ϭ͘ ϮϮϯϭϯ͘ 

Dependability ratio (d)

Table 4 . Effect of change in failure rate (μ 1 ) on the reliability of the Storage Tank and stock preparation unit Time (hrs.) System Subsystem I μ 1 = 0.013 μ 1 = 0.023 μ 1 = 0.033 μ 1 = 0.043 μ 1 = 0.013 μ 1 = 0.023 μ 1 = 0.033

μ 1 = 0.043 0.650509 0.423162 0.275271 0.179066 0.116484

10 20 30 40 50

0.078866 0.00622 0.000491 3.87E-05 3.05E-06

0.794534 0.631284 0.501576 0.398519 0.316637

0.718924 0.516851 0.371577 0.267135 0.19205

0.650509 0.423162 0.275271 0.179066 0.116484

0.878095 0.771052 0.677057 0.594521 0.522046

0.794534 0.631284 0.501576 0.398519 0.316637

0.718924 0.516851 0.371577 0.267135 0.19205

Braz. J. Biom. ǡ˜Ǥ 43 ǡ‡ǦͶ͵͹͸ʹǡʹͲʹͷǤ  13

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