DDS vs. RDH

Chemical and Pulping Ltd

DDS vs. RDH

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 RDHcooking 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.

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