Looking for breakthrough ideas for innovation challenges? Try Patsnap Eureka!

Method for recovering performance of electrolyzer for use in production of polysulfide and method for stopping holding electrolyzer

a technology of electrolyzer and polysulfide, which is applied in the direction of electrolysis process, electrolysis components, etc., can solve the problems of increasing the resistance of the membrane, increasing the electricity required, and increasing the voltag

Inactive Publication Date: 2009-10-01
NIPPON PAPER IND CO LTD +2
View PDF7 Cites 11 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent text describes a problem with an electrolyzer used in the production of polysulfide. The problem is that the membrane between the anode and cathode compartments can become scaled, causing an increase in resistance and voltage. This requires the electrolyzer to be cleaned periodically, which can be time-consuming and costly. The invention provides a method for stopping and holding the electrolyzer to prevent the problem, and also provides a method for cleaning the anode compartment to restore its performance. This allows for longer periods of use without the need for costly maintenance.

Problems solved by technology

The electrolyzer described as above had a problem in that calcium and other trace constituents, contained in the solution introduced into the anode compartment, were precipitated on the membrane to be turned into scales, to thereby induce an increase in the membrane resistance, causing a rise in voltage.
This problem is economically undesirable because it will bring about an increase in electricity required for production of polysulfide.
Further, it is not easy to remove impurities, such as calcium and so forth, deposited on the membrane, and if an attempt is made to clean impurities with a strong acid, this will raise a possibility that an anode corrosion problem occurs.
Those problems are taken as a first issue.
With the method for producing polysulfide with the use of the electrolyzer described as above, a problem has been encountered in that when electrolytic oxidation is started again after stopping-holding of the electrolytic oxidation, a voltage required for electrolytic oxidation becomes higher than before stopping of the electrolytic oxidation.
This problem is undesirable because it will bring about an increase in electricity required for production of polysulfide as is the case with the first issue.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Method for recovering performance of electrolyzer for use in production of polysulfide and method for stopping holding electrolyzer
  • Method for recovering performance of electrolyzer for use in production of polysulfide and method for stopping holding electrolyzer
  • Method for recovering performance of electrolyzer for use in production of polysulfide and method for stopping holding electrolyzer

Examples

Experimental program
Comparison scheme
Effect test

working example 1

[0061]A white liquor having the following composition was oxidized by electrolytic oxidation. Electrolysis conditions were as follows: A double-chamber electrolyzer was assembled, the electrolyzer comprising a porous nickel member serving as an anode (an anode surface area per an anode compartment volume: 5600 m2 / m3, the average diameter of openings in the mesh of the anode: 0.51 mm, an anode surface area per a unit membrane area: 28 m2 / m2), iron expansion metal serving as a cathode, and a perfluoro resin cation-exchange membrane serving as a membrane. The white liquor having the following composition was introduced into the electrolyzer, and electrolysis was carried out under the condition of electrolysis temperature: 85° C., and current density at the membrane: 6 kA / m2, having thereby obtained a polysulfide liquor of polysulfide sulfur concentration 9 g / L at current efficiency 95%. Further, NaOH was formed on the cathode side of the electrolyzer at current efficiency 80%, and an a...

working example 2

[0066]Electrolytic oxidation was conducted under a condition of the same electrolyzer, and white liquor as those for Working Example 1, except that the same hydrochloric acid that was used in Working Example 1, with 0.5 mass % of RESCOR A-825 (manufactured by Toei Kasei Co., Ltd.) as an anticorrosive, added thereto, was used as a cleaning fluid, and after stopping the electrolytic oxidation, cleaning was applied, subsequently, resuming electrolytic oxidation. Table 1 shows calcium concentration, and nickel concentration in the cleaning fluid at the time of completion of cleaning, and a voltage required for electrolytic oxidation 10 days after resumption of electrolysis.

working example 3

[0067]Electrolytic oxidation was conducted under a condition of the same electrolyzer, and white liquor as those for Working Example 1, except that 1.0 mass % of hydrochloric acid with 0.5 mass % of RESCOR A-825 (manufactured by Toei Kasei Co., Ltd.) as an anticorrosive, added thereto, was used as a cleaning fluid, and after stopping the electrolytic oxidation, cleaning was applied, subsequently, resuming electrolytic oxidation. Table 1 shows calcium concentration, and nickel concentration in the cleaning fluid at the time of completion of cleaning, and a voltage required for electrolytic oxidation 10 days after resumption of electrolysis.

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

In an electrolyzer comprising an anode compartment provided with porous anodes, a cathode compartment, and a membrane providing a partition between the anode compartment and the cathode compartment, wherein a solution containing sulfide ions is introduced into the anode compartment, and an aqueous solution containing caustic soda is introduced into the cathode compartment, thereby producing a polysulfide containing polysulfide sulfur through electrolytic oxidation, wherein the anode compartment of the electrolyzer is cleaned with the use, of an aqueous solution containing at least either one of an inorganic acid, a chelating agent, and a scale-cleaning agent, thereby recovering performance of the electrolyzer. Further, when the contents of the anode compartment are replaced with an alkaline aqueous solution containing not more than 0.1 mass % of sulfide ions and not more than 0.1 mass % of carbonate ions upon stopping the electrolytic oxidation, thereby maintaining the performance of the electrolyzer.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a method for recovering performance of an electrolyzer for use in production of polysulfide by electrolytic oxidation of a white liquor or a green liquor, a method for stopping-holding an electrolyzer and a method for efficiently producing polysulfide by making use of the method for recovering the performance of the electrolyzer and the method for stopping-holding the electrolyzer.BACKGROUND OF THE INVENTION[0002]To attain a higher production yield at the time of production of chemical pulp is an important issue for effective utilization of wood resources. There is available a polysulfide cooking process as one of high yield technologies for production of kraft pulp currently in the mainstream of the chemical pulp. As disclosed in, for example, JP 61-259754 A, and JP 53-92981 A, a digesting liquor in the polysulfide cooking process is produced by oxidizing an alkaline aqueous solution containing sodium sulfide, the so-call...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(United States)
IPC IPC(8): C25B1/22C25B15/00
CPCC25B15/00C25B1/14
Inventor KUROSU, KAZUHIROWATANABE, KEIGOTANAKA, JUNJI
Owner NIPPON PAPER IND CO LTD
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Patsnap Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Patsnap Eureka Blog
Learn More
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic, Popular Technical Reports.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap|About US| Contact US: help@patsnap.com