Impurity removal method of chlorine dioxide vertical generator

Abstract

The invention relates to an impurity removal method of a chlorine dioxide vertical generator, which comprises the following steps: adding first pure water and a sodium hypochlorite solution into the chlorine dioxide vertical generator, continuously boiling under a vacuum condition, cooling and discharging liquid; washing with second pure water and discharging liquid; the boiling temperature is lower than 80 DEG C. Different from the prior art, the technical scheme provides a mode for efficiently removing impurities in a mode that the sodium hypochlorite solution is boiled at the temperature lower than 80 DEG C, the boiling temperature in the mode is lower than the efficient decomposition temperature 80 DEG C of hypochlorite, the hypochlorite is high in stability, the decomposition amount is small although the hypochlorite is boiled, and therefore the impurity removing efficiency is higher; the chlorine dioxide vertical generator impurity removal device has the advantages of simple and effective impurity removal of the chlorine dioxide vertical generator, no residue, reduction of the decomposition of chlorine dioxide, and improvement of the production efficiency and the production safety.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of papermaking, in particular to a method for removing impurities from a chlorine dioxide vertical generator. BACKGROUND

[0002] The chlorine dioxide workshop is the most important workshop for producing bleaching agents in pulp and papermaking. Abnormal decomposition of chlorine dioxide will cause the production of bleaching agents to be interrupted, and in severe cases, it will affect the operation of the pulp line.

[0003] After a large chlorine dioxide vertical generator has been installed and operated for a period of time, various equipment systems will have oil, wood chips, dust, resin and other organic matter entering the generator system, adhering to the generator wall and gas pipeline. These impurities will cause the produced chlorine dioxide gas to decompose during normal production, affecting production efficiency and posing a safety hazard. SUMMARY

[0004] In view of the above problems, the present application provides a method for removing impurities from a chlorine dioxide vertical generator, which can effectively remove impurities in the system, improve production efficiency and reduce production hazards.

[0005] The present application provides a method for removing impurities from a chlorine dioxide vertical generator, which comprises the following steps: adding first pure water and sodium hypochlorite solution to the chlorine dioxide vertical generator, and after boiling under vacuum conditions, cooling and draining; then flushing the drain with second pure water; the boiling temperature is lower than 80℃.

[0006] Unlike the prior art, the above technical solution provides a high-efficiency impurity removal method using a sodium hypochlorite solution boiling method below 80℃. In this method, the boiling temperature is lower than the high-efficiency decomposition temperature of hypochlorite ions (80℃), and the stability of hypochlorite ions is higher. Although boiling, the decomposition amount is small, so the impurity removal efficiency is higher. It is simple and effective to remove impurities from the chlorine dioxide vertical generator, and there is no residue itself, which reduces the decomposition of chlorine dioxide, improves the production efficiency and production safety.

[0007] In some embodiments, the mass ratio of the first pure water to the sodium hypochlorite solution is 1:3-5; the concentration of the sodium hypochlorite solution is 10%-15%.

[0008] In some embodiments, the vacuum condition is -70kpa to -75kpa.

[0009] In some embodiments, the boiling temperature is 69-75℃. This temperature can maintain the effective boiling state of the hypochloric acid solution, and the decomposition rate of hypochlorite ions is relatively low.

[0010] In some embodiments, the boiling time is 5-7 hours.

[0011] In some embodiments, the vertical generator heat exchange system uses steam heating, and the steam consumption is 6000 kg / h.

[0012] In some embodiments, the cooling liquid discharge temperature is 60-65℃.

[0013] In some embodiments, the second pure water flushing time is 10-15 minutes.

[0014] In some embodiments, the gas phase outlet of the vertical generator is connected to an absorption tower, and the temperature in the absorption tower is controlled below 50℃.

[0015] In some embodiments, the first pure water and sodium hypochlorite solution are added in an amount of the maximum working capacity of the chlorine dioxide vertical generator.

[0016] The above summary of the invention is only a summary of the technical solutions of the present application. In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, and then can be implemented according to the content of the description of the text, and in order to let the above-mentioned purpose and other purposes, characteristics and advantages of the present application can be more easily understood, the following is described in combination with the specific embodiments of the present application. DETAILED DESCRIPTION

[0017] In order to explain the technical content, structural features, purposes and effects of the technical solutions in detail, the following will be described in detail in combination with specific embodiments.

[0018] In order to explain the possible application scenarios, technical principles, specific schemes that can be implemented, purposes and effects that can be achieved, the following will be described in detail in combination with the specific embodiments listed. The embodiments described in this paper are only used to more clearly explain the technical solutions of the present application, therefore only as an example, and cannot limit the protection scope of the present application.

[0019] In this paper, the term "embodiment" means that the specific features, structures or characteristics described in combination with the embodiment can be included in at least one embodiment of the present application. The term "embodiment" appears in various places in the specification does not necessarily refer to the same embodiment, and does not particularly limit its independence or association with other embodiments. In principle, in this application, as long as there is no technical contradiction or conflict, the technical features mentioned in each embodiment can be combined in any way to form a corresponding implementable technical solution.

[0020] Unless otherwise defined, the meaning of the technical terms used in this paper is the same as that generally understood by those skilled in the art to which the present application belongs; the use of related terms in this paper is only for the purpose of describing specific embodiments, and is not intended to limit the present application.

[0021] In the description of the present application, the phrase "and / or" is a description of the relationship between two objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases: A exists, B exists, and A and B exist at the same time. In addition, the character " / " herein generally represents that the associated objects before and after are an "or" logical relationship.

[0022] In the present application, the terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantity, primary and secondary or order relationship between the entities or operations.

[0023] In the present application, the phrases "include", "contain", "have" or other similar expressions used in the sentences are intended to cover non-exclusive inclusion, and these expressions do not exclude the presence of additional elements in the process, method or product including the described elements, so that the process, method or product including a series of elements can not only include those limited elements, but also include other elements not explicitly listed, or also include the elements inherent to such process, method or product.

[0024] As the same understanding as in the "Guidelines for Examination", in the present application, the expressions "greater than", "less than", "exceed" and the like are understood as not including the number; the expressions "above", "below", "within" and the like are understood as including the number. In addition, in the description of the embodiments of the present application, the meaning of "multiple" is more than two (including two), and similar expressions related to "multiple" are also understood in this way, for example, "multiple groups", "multiple times" and the like, unless otherwise explicitly limited.

[0025] The chlorine dioxide vertical generator used in the present embodiment uses chemical method to prepare chlorine dioxide.

[0026] The present application provides a method for removing impurities from a chlorine dioxide vertical generator, which comprises the following steps: adding first pure water and sodium hypochlorite solution into the chlorine dioxide vertical generator, and after boiling under vacuum condition, cooling and discharging the liquid; then washing the discharged liquid with second pure water; the boiling temperature is lower than 80℃.

[0027] Dissociation of sodium hypochlorite: NaClO is dissociated into Na + and ClO- (hypochlorite ion) after dissolving in water, and ClO- will hydrolyze to make the solution alkaline:

[0028] Solution environment: after mixing with NaClO, the solution is weakly alkaline (pH≈10), and if the temperature is maintained above 80℃, it will promote the thermal decomposition reaction of ClO-; if the temperature is lower than 80℃, the hypochlorite is relatively stable, and can be oxidized and reduced with impurities.

[0029] Moreover, the boiling reaction itself has intense molecular activity, which also helps to remove impurities in the chlorine dioxide vertical generator and pipeline.

[0030] Unlike the prior art, the above technical solution provides a way of efficiently removing impurities by boiling the sodium hypochlorite solution below 80℃, in which the boiling temperature is lower than the efficient decomposition temperature 80℃ of hypochlorite, and the hypochlorite is less decomposed, so it has higher impurity removal efficiency, and it is simple and effective to remove impurities from the chlorine dioxide vertical generator, and has no residual itself, reduces the decomposition of chlorine dioxide, and improves the production efficiency and safety.

[0031] In some embodiments, the mass ratio of the first pure water to the sodium hypochlorite solution is 1:3-5; and the concentration of the sodium hypochlorite solution is 10%-15%.

[0032] In some embodiments, the mass ratio of the first pure water to the sodium hypochlorite solution is 1:3, and the concentration of the sodium hypochlorite solution is 10%.

[0033] In some embodiments, the vacuum condition is-70kpa to-75kpa.

[0034] In some embodiments, the boiling temperature is 69-75℃.

[0035] In some embodiments, the boiling time is 5-7 hours.

[0036] In some embodiments, the vertical generator uses a heat exchange system for steam heating, and the steam consumption is 6000kg / h during boiling.

[0037] In some embodiments, the cooling and liquid discharge temperature is 60-65℃.

[0038] In some embodiments, the second pure water flushing time is 10-15 minutes.

[0039] In some embodiments, the exhaust port of the vertical generator is connected to an absorption tower, and the temperature in the absorption tower is controlled below 50℃. In order to prevent the temperature from being too high and burning out the filler, the temperature in the absorption tower is controlled below 50℃, and the water cooling system is used for cooling, and the water addition amount is 80m 3 / h.

[0040] In this embodiment, the vacuum ejector injection pressure is controlled at 11KG to 12KG, and the vacuum ejector return valve opening is adjusted to control the system vacuum at-70kpa~ -75kpa.

[0041] In this embodiment, the first pure water and sodium hypochlorite solution are added in an amount of the maximum working capacity of the chlorine dioxide vertical generator.

[0042] Example 1

[0043] The first pure water and 10wt% sodium hypochlorite solution are added into the chlorine dioxide vertical generator, and the mass ratio of the first pure water to the 10wt% sodium hypochlorite solution is 1:3; under the condition of-70kpa~ -75kpa vacuum, 6000kg / h steam is used to heat the chlorine dioxide vertical generator, and the boiling is maintained at 69~75℃ for 6h, and then the liquid is discharged after cooling at 60~65℃; after flushing with the second pure water for 10-15 minutes, the liquid is discharged, and the cleaning and impurity removal are completed.

[0044] After the chlorine dioxide vertical generator is cleaned and impurities are removed, the first decomposition of chlorine dioxide occurs after 8 days of continuous operation, and the second cleaning is required after 25 days of operation.

[0045] Example 2

[0046] The first pure water and 15wt% sodium hypochlorite solution are added into the chlorine dioxide vertical generator, and the mass ratio of the first pure water to the 15wt% sodium hypochlorite solution is 1:5; under the condition of-70kpa~ -75kpa vacuum, 6000kg / h steam is used to heat the chlorine dioxide vertical generator, and the boiling is maintained at 69~75℃ for 5h, and then the liquid is discharged after cooling at 60~65℃; after flushing with the second pure water for 10-15 minutes, the liquid is discharged, and the cleaning and impurity removal are completed.

[0047] After the chlorine dioxide vertical generator is cleaned and impurities are removed, the first decomposition of chlorine dioxide occurs after 9 days of continuous operation, and the second cleaning is required after 24 days of operation.

[0048] Example 3

[0049] The first pure water and 12wt% sodium hypochlorite solution are added into the chlorine dioxide vertical generator, and the mass ratio of the first pure water to the 12wt% sodium hypochlorite solution is 1:4; under the condition of-70kpa~ -75kpa vacuum, 6000kg / h steam is used to heat the chlorine dioxide vertical generator, and the boiling is maintained at 69~75℃ for 7h, and then the liquid is discharged after cooling at 60~65℃; after flushing with the second pure water for 10-15 minutes, the liquid is discharged, and the cleaning and impurity removal are completed.

[0050] The chlorine dioxide vertical generator is cleaned and impurities are removed, and after continuous operation for 7 days, the first decomposition of chlorine dioxide occurs, and after operation for 22 days, secondary cleaning is required.

[0051] Comparative example:

[0052] A 10wt% sodium hypochlorite solution is added to the chlorine dioxide vertical generator, heated to boiling, and kept boiling for 6h, then cooled to 60-65℃ and drained; then rinsed with second pure water for 10-15 minutes and drained to complete cleaning and impurity removal.

[0053] The chlorine dioxide vertical generator is cleaned and impurities are removed, and after continuous operation for 5 days, the first decomposition of chlorine dioxide occurs, and after operation for 15 days, secondary cleaning is required.

[0054] Finally, it should be noted that although the above embodiments have been described in the specification of the present application, this does not limit the patent protection scope of the present application. Any technical solution obtained by replacing or modifying the equivalent structure or equivalent process based on the essential concept of the present application, using the content described in the specification of the present application, and directly or indirectly implementing the technical solutions of the above embodiments in other related technical fields, etc., are all included in the patent protection scope of the present application.

Claims

1. A method for removing impurities from a vertical chlorine dioxide generator, characterized in that: The impurity removal method comprises the following steps: Add first pure water and sodium hypochlorite solution into the vertical chlorine dioxide generator, boil under vacuum conditions, cool and drain the liquid; then rinse the liquid with second pure water; the boiling temperature is lower than 80°C.

2. The impurity removal method according to claim 1, wherein The mass ratio of the first pure water to the sodium hypochlorite solution is 1:3-5; the concentration of the sodium hypochlorite solution is 10%-15%.

3. The impurity removal method according to claim 1, wherein: The vacuum condition is -70kPa to -75kPa.

4. The impurity removal method according to claim 1, characterized in that: The boiling temperature is 69-75°C.

5. The impurity removal method according to claim 1, characterized in that: The boiling time is 5-7 hours.

6. The impurity removal method according to claim 1, characterized in that: The vertical generator adopts a heat exchange system to heat with steam, and the steam consumption during boiling is 6000 kg / h.

7. The impurity removal method according to claim 1, characterized in that: The cooling liquid temperature is 60-65°C.

8. The impurity removal method according to claim 1, characterized in that: The second pure water rinsing time is 10-15 minutes.

9. The impurity removal method according to claim 1, characterized in that: The gas phase outlet of the vertical generator is connected to an absorption tower, and the temperature in the absorption tower is controlled below 50°C.

10. The impurity removal method according to claim 1, characterized in that: The amount of the first pure water and sodium hypochlorite solution added is the maximum working capacity of the vertical chlorine dioxide generator.