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Lo-Air Concept

IP.com Disclosure Number: IPCOM000021118D
Publication Date: 2003-Dec-23
Document File: 3 page(s) / 264K

Publishing Venue

The IP.com Prior Art Database

Related People

Sergey Malkov: INVENTOR

Abstract

Main idea of invention is the process (sequence of sub-processes with defined conditions) that enables to shorten the impregnation stage down to few minutes. Prerequisites for this are effective removal of entrapped air from the chips followed by partial removal of chip moisture. When treated chips come to contact with cooking liquor, the liquor rapidly fills the wood voids. The complete penetration would be expected to take 2-5 minutes.

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Issued By

 

Sergey Malkov

 

Subject: “Lo-Air Concept”

 

MAIN IDEA / OBJECTIVES

Main idea of invention is the process (sequence of sub-processes with defined conditions) that enables to shorten the impregnation stage down to few minutes. Prerequisites for this are effective removal of entrapped air from the chips followed by partial removal of chip moisture. When treated chips come to contact with cooking liquor, the liquor rapidly fills the wood voids. The complete penetration would be expected to take 2-5 minutes.

BENEFITS

1) New process provides rapid and complete penetration of cooking liquor into chip voids. The amount of penetrated liquor is much higher than with conventional front-end technology. This ensures high alkali concentration inside the wood chips at the start of the cook (see Table 1).

Table 1. Estimation of alkali uptake with new concept.

 

BIRCH

PINE

 

Original

"Lo-Air"

Original

"Lo-Air"

Initial Moisture Content, %

50

50

50

50

Basic Density, kg/m3

500

500

400

400

Moisture Content after Front-end, %

52

35

52

35

Chip volume (per 1 t o.d. wood), m3

2.00

2.00

2.50

2.50

Liquid volume (per 1 t o.d. wood), m3

1.08

0.54

1.08

0.54

Wood volume (per 1 t o.d. wood), m3

0.67

0.67

0.67

0.67

Penetrated liquor (per 1 t o.d. wood), m3

0.25

0.79

0.75

1.29

Liquor EA as NaOH, kg/m3

72

72

80

80

NaOH uptake, kg/t o.d. wood

18.0

57.2

60.0

103.6

NaOH uptake, % on o.d. wood

1.8

5.7

6.0

10.4

2) Rapid penetration enables to eliminate impregnation vessel and impregnation stage at the top of the digester. This further leads to simplification of the system and increase of production capacity up to 15% in case of single vessel digesters (see Figure 1).

Figure 1. Capacity increase of single vessel digester.

3) Another benefit achieved is the maximum removal of entrained air from the system. This entrained air causes numerous problems in downstream operations (foaming, pump efficiency reduction, reduction of drainage rate of pulp, etc).

4) Finally, pulping homogeneity can be improved.

PROCESS DESCRIPTION

Figure 2. Simplified process diagram.

Process consists of three sub-processes:

1) Atmospheric presteaming of wood chips for long...