JPS6216719B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method that does not cause scale to form on the walls of equipment when an acidic liquid containing calcium oxalate comes into contact with manufacturing equipment in the manufacturing process of products made from plants. Various products such as pulp, sugar, whiskey, and vegetable oil have been known in many fields as products made from plants, such as pulp, sugar, whiskey, and vegetable oil. In this process, scale is generated and adhered to the inner wall of the equipment that comes into contact with the liquid, which often impedes smooth operation. Therefore, the above-mentioned scales are often removed, but this work is not easy, and a preferable method for removing scales or preventing scale formation has been strongly desired in the art. For example, in the cooking liquor used in the production of pulp by the sulfite method, sulfur is first burned in a burner to create sulfur dioxide gas, which is supplied from the bottom to a tower filled with limestone, and from the top of the tower. It used to be made by supplying water, but in recent years, with the intention of improving pulp quality and yield, a cooking liquor using soda or ammonia has been used instead of calcium. The pulp obtained using this method is called soda-based sulfite pulp or ammonia-based sulfite pulp. The waste liquid of the cooking liquor used in the production of pulp by the soda-based sulfite method or the ammonia-based sulfite method is concentrated in an evaporative concentrator, and then the concentrated liquid is heated and burned to recover chemicals, or
Although it is used as a binder, insoluble substances gradually deposit on the inner walls of the evaporative concentration equipment for the waste liquid, and eventually become attached as scales, reducing the heat transfer coefficient. is being descaled. However, this scale is not efficiently removed by common acids or alkalis or detergents.
In addition, in the whiskey manufacturing process, the residual liquid remaining after distilling and separating the product is evaporated and concentrated, and the concentrated liquid is used as feed, pharmaceutical raw materials, etc. However, this still residual liquid is insoluble in the inner wall of the evaporation concentrator. The evaporative concentrator is descaled because scale is deposited due to the deposition of substances and this reduces the heat transfer coefficient. Similar to the above, this scale is also not easy to remove. Furthermore, in the raw material sugar production process for cane sugar or beet sugar, insoluble substances gradually deposit on the inner wall of the evaporation concentrator in the process of concentrating the clear juice to obtain the sugar juice, and eventually become attached as scale, causing a decrease in the heat transfer coefficient. In order to reduce this, scale is removed, but this scale is also not easy to remove as described above. The scale generated in the above-mentioned sulfite pulp manufacturing process, whiskey manufacturing process, raw sugar manufacturing process, etc. can be removed to some extent by applying external mechanical force to it, but it is difficult to efficiently remove it from the entire surface of the container wall. Moreover, the actual work is complicated and is not an efficient or simple method. In addition, as a conventionally known method for preventing scale formation, there is a method in which scale formation causing substances such as calcium and magnesium in the liquid are removed in advance by ion exchange. In addition to the exchange tower and associated equipment, it requires a large amount of energy, making it impractical. In particular, it is difficult to apply it to the prevention of scale formation in the manufacturing process of pulp, whiskey, raw sugar, etc., which handles a huge amount of liquid. Another method for preventing scale formation is to add chelating agents such as sodium ethylenediaminetetraacetate and condensed phosphates to the liquid, but these chelating agents only have a high chelating ability in alkaline conditions. Therefore, in the manufacturing process, such as the liquid containing calcium oxalate
Even if these chelating agents are added to an acidic liquid with a low pH, there is almost no effect on preventing scale formation. The present inventors have learned that the scale described above is a complex structure composed of various components, but its main component is calcium oxalate. We came to the conclusion that this was due to the calcium oxalate content contained in the product, and as a result of experimentally exploring the effects of adding various chemicals as a way to prevent precipitation, we unexpectedly found that it contains aluminum ions and sulfamic acid anions. We have discovered a new fact that it is effective to do so, and have completed the present invention. The purpose of the present invention is to provide a simple, efficient, and safe method for preventing scale formation on the walls of processing equipment when acidic liquid containing calcium oxalate comes into contact with the processing equipment in the manufacturing process of products made from plants. The purpose is to provide a method. The method for preventing scale formation of the present invention involves adding (1) aluminum ions and (2) hydrochloric acid, nitric acid, sulfamic acid, formic acid, acetic acid, propionic acid, oxalic acid, glycolic acid, malonic acid, apple acid, etc. to an acidic solution containing calcium oxalate. acid, butyric acid,
It is characterized by containing anion of one or more acids selected from the group consisting of tartaric acid, citric acid, and gluconic acid. In the present invention, the acidic liquid containing calcium oxalate is a by-product or treatment liquid in the manufacturing process of products made from plants, such as cooking waste liquid used in the pulp manufacturing process by the sulfite method. , especially the waste liquid subjected to the concentration treatment,
These include the residual liquid after distillation of the product in the whiskey manufacturing process, especially the residual liquid used for its concentration treatment, and the clarified liquid in the raw sugar manufacturing process.Usually, these liquids are is kept acidic for subsequent processing and is not adjusted to basicity. In basicity, the formation of scale may be further promoted. In the present invention, anions contained in the solution containing calcium oxalate include hydrochloric acid, nitric acid, sulfamic acid, formic acid, acetic acid, propionic acid, oxalic acid, glycolic acid, malonic acid, malic acid, butyric acid, tartaric acid, citric acid, Anions such as gluconic acid,
Usually, anions can be easily included in the liquid by adding a substance that generates these anions. However, even if the solution contains only the acid or anions without the coexistence of aluminum ions, there is no effect of preventing scale formation. Further, even if a substance that supplies aluminum ions is added to the liquid without coexisting the anions, there is no effect of preventing scale formation. In the present invention, the inclusion of aluminum ions is carried out by supplying a substance that generates aluminum ions in the liquid. Of course, it is also preferable to add to the liquid a substance that simultaneously generates aluminum ions and anions of the acid mentioned above in the liquid. In the present invention, preferred anions to be included include sulfamic acid radicals, formic acid radicals, acetic acid radicals, glycolic acid radicals, citrate radicals, glycolic acid radicals, etc., and aluminum ions and these preferred anions are added to an acidic solution containing calcium oxalate. Preferred methods for containing include a solution obtained by reacting the preferred acid with aluminum hydroxide or metal aluminum in water, or a method of adding an aluminum salt isolated from the solution to the solution. In the present invention, the ratio of the aluminum ions and acid anions that should be contained in order to prevent scale formation is as follows:
Generally, 0.33 to 6 equivalents, preferably 1.0 to 3.5 equivalents of the above acid anion are used per equivalent of aluminum ion. In addition, the amount of aluminum ions and acid anions that should be contained is usually 10 to 10% in total in an acidic solution containing calcium oxalate.
The amount is 10,000 ppm, preferably 100 to 1,000 ppm. Thus, according to the present invention, by incorporating aluminum ions and anions of the acid into an acidic solution containing calcium oxalate, scale formation is prevented on the walls of the device with which the solution comes into contact. Of course, as long as the purpose of the present invention is achieved, the acidic solution containing calcium oxalate may contain any other substances such as rust preventives, antifoaming agents, etc. in addition to the aluminum ions and acid anions. Good too. The method of the present invention is easy to implement and has high industrial utility. Hereinafter, the present invention will be described in more detail with reference to Examples, but the technical scope of the present invention is not limited thereto. Example 1 Waste cooking liquor (PH2.3, total solids concentration 12%) used in the pulp manufacturing process using the sulfite method was continuously evaporated for 10 hours and concentrated to about 4 times using the evaporation/concentration method described below. At this time, the amount of scale produced was determined by scraping off the scale that had adhered to the heat exchange part of the device, drying it, and weighing it. Evaporation/concentration method and measurement of scale production (1) Equipment: Consists of a heat exchange section, a flush chamber with a suction port, a circulation pump, and a conduit.The heat exchange section consists of a single stainless steel tube with an outer diameter of 9 mm and surrounding It consists of a glass tube jacket with an outer diameter of 30 mm, and an inlet and an outlet for the inflow and outflow of the cooking waste liquid are provided at both ends of the jacket, and the outlet is connected to a nozzle in the flashing chamber via a conduit. A liquid outlet is provided at the bottom of the flush chamber, the outlet being connected via a conduit to the circulation pump inlet, and the pump outlet being connected via a conduit to the liquid inlet of the jacket. The heating medium flows through the stainless steel single tube from the liquid outflow end of the jacket to the inflow end, where heat is exchanged. The length of the heat exchange part is 300mm
It is. (2) Concentration operation: When the pump operates, the cooking waste liquid flows out from the outlet at the bottom of the flashing chamber, is sent to the heat exchange section through the jacket inlet, passes through the jacket, flows out from the jacket outlet, and is sent to the flashing chamber. . At the same time, by passing a heating medium through the single tube, the liquid is flashed at the nozzle, the evaporated vapor is sucked through the flashing chamber suction port, and the liquid falls to the bottom of the flashing chamber. By continuously carrying out such flashing, the cooking waste liquid is gradually concentrated. (3) Measurement of scale: After completing the above concentration, remove the single tube from the heat exchange section, scrape off the scale that adheres to its surface, dry it, and weigh it. When the cooking waste liquid was concentrated according to the above concentration method, the amount of scale attached was 3.42 g. Then,
Using the same cooking waste liquid, after adding chemicals with the compositional formula shown in Table 1 Experiment Nos. 1 to 6, and concentrating it in the same manner as above, the amount of scale shown in Table 1 was attached. It was confirmed that the amount had decreased significantly.

[Table] Example 2 In the same manner as in Example 1, the residual liquid from a whiskey still was evaporated and concentrated. The total solids concentration of the whiskey still residue used was
17%, PH was 3.8. It was concentrated three times by evaporation for about 10 hours. The scale adhesion amount is shown in Table 2.

[Table] Example 3 In the same manner as in Example 1, evaporation concentration was carried out using the clarified juice liquid from the raw sugar manufacturing process of cane sugar. The concentration of the clarified juice used was 13.5 in Brix (BX), and the pH was 3.9. It was concentrated 4 times by evaporation for about 10 hours. The scale adhesion amount is shown in Table 3.

[Table] Shows gluconate radicals.
As shown in Tables 1 to 3, according to the method of the present invention, the amount of scale adhesion is significantly reduced, and the prevention of scale formation can be achieved very easily.

Claims (1)

[Scope of Claims] 1. In an acidic liquid containing calcium oxalate, (1) aluminum ions and (2) hydrochloric acid, nitric acid, sulfamic acid, formic acid, acetic acid, propionic acid, oxalic acid, glycolic acid, malonic acid, malic acid. , butyric acid, tartaric acid, citric acid, and gluconic acid. 2. The method according to claim 1, wherein the acid anion is contained in a ratio of 0.33 to 6.0 equivalents to 3 equivalents of aluminum ions. 3 Add aluminum ions and anions of the above acid to a solution containing calcium oxalate in a total amount of 10 to 10%.
The method according to claim 1 or 2, wherein the method is contained in a proportion that gives a concentration of 10,000 ppm. 4. The content of aluminum ions and anions of the acid is achieved by adding a liquid prepared by reacting aluminum hydroxide or metallic aluminum with the acid in water. Claim 1
3. The method according to paragraph 2, paragraph 3. 5. The inclusion of aluminum ions and anions of the acid is achieved by adding an aluminum salt of the acid or a mixture thereof,
The method according to paragraph 2 or 3. 6 Claim 1, wherein the liquid containing calcium oxalate is a cooking waste liquid from a sulfite pulp manufacturing process.
The method according to paragraph 2, paragraph 3, paragraph 4 or paragraph 5. 7. Claim 1, wherein the liquid containing calcium oxalate is distillation still residue from the whiskey manufacturing process.
The method according to paragraph 2, paragraph 3, paragraph 4 or paragraph 5. 8. Claim 1, wherein the liquid containing calcium oxalate is a clear juice liquid in the raw sugar production process,
The method according to item 2, 3, 4 or 5.