Chemical and Pulping Ltd

DDS vs. RDH

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This page describes the major differences between RDH and DDS.

DDS (patent pending) versus RDH

The DDS  cooking system is an enhanced design of the RDH cooking system.  The modifications create more stable temperatures and residue chemicals in the tank farm, less channeling in the digester, and more efficient pulp discharge to ensure lower kappa variation, more consistent production rates, and highly automated cooking operations with minimum operator intervention.  This superior design has addressed these performance concerns by better piping configurations, better heat exchanger design and most importantly, through the use of modern process control techniques (Advanced Process Control).

Conversion from RDH to DDS Installation Data

DingFeng Pulp Company converted their Beloit (GLV) RDH to DDS in 2004.  The following data indicates the benefits of DDS over RDH.  (Data provided by DingFeng Pulp Company).

Item

Unit

RDH

10/03 - 3/04

DDS

4/04 - 11/04

Difference

Note

Digesters

-

3

4

+1

 

Production

t/month

5905

8138

+2233

9000t

in Aug.

Yield/cook

t/cook

10. 6

11. 1

+0. 5

 

Bleaching Pulp Yield

%

47. 4

47. 7

+0. 3

 

Steam usage in cooking

t/tp

0. 93

0. 84

-0. 09

 

Reject rate

%

4. 2

2. 3

-1.9

 

Kappa no.

-

15. 7

14. 6

-0.9

 

Defoamer usage

kg/tp

1. 35

0. 93

-0. 42

 

Residual alkali

%

0. 50

0. 41

-0. 09

 

Chlorine Consumption

kg/tp

87. 5

4 - 7 / 04:  85.1

8 - 11 / 04:  69.0

-18. 5

60. 5 in Nov

Brightness

%ISO

87. 9

88. 2

+0. 3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Design Advancements of DDS over RDH

The DDS has many design advancements over the RDH process.  They include modifications to the tank farm vessels and piping, the digester piping, and advanced control techniques in the DCS.

 

DDS Process & Control
DDS Delignification

Home Up DDS History DDS Theory DDS Performance DDS Process Diagram DDS vs. RDH Patents

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