A single-stage water washing and desalination system and its hierarchical control method and storage medium

Abstract

The present invention provides a single-stage water washing and desalination system and its hierarchical control method and storage medium. During initial production, after the slurry tank reaches a set liquid level, feeding is stopped, the slurry outlet valve is opened to allow the slurry to enter a solid-liquid separation device, the filter cake alkali metal salt content is determined, and when the filter cake alkali metal salt content is within the alkali metal salt control content range, the filter cake is sent to the sintering batching process to participate in sintering. At the same time, before the clear liquid tank reaches the set liquid level, the second alkali metal salt concentration of the clear liquid in the clear liquid tank is obtained. When the second alkali metal salt concentration is within the alkali metal salt control concentration range, new water and dust removal ash are continued to be added to the slurry tank in proportion, and the second liquid outlet valve is opened to allow the clear liquid in the clear liquid tank to enter the subsequent evaporation crystallization salt separation process. The present application realizes hierarchical control of the filter cake alkali metal salt content and clear liquid concentration, and controls the clear liquid concentration within an appropriate range while ensuring the quality of the filter cake as much as possible.

Description

Technical Field

[0001] The present invention relates to the technical field of sintering dust removal ash disposal, and in particular to a single-stage water washing and desalination system and a hierarchical control method and a storage medium thereof. Background Art

[0002] Sintering dust removal ash mainly comes from the dust generated during the sintering machine head, machine tail and environmental dust removal process, especially the sintering machine head dust removal ash, which contains more K and Na alkali metal elements.

[0003] Currently, the commonly used Figure 4 The typical water washing desalination system shown is used to remove K and Na alkali metal elements. The working principle of the water washing desalination system is mainly based on two core processes: water washing and evaporation crystallization. The soluble substances (such as K and Na) in the dust removal ash are separated by the water washing process, and the salt in the water washing liquid is crystallized and separated by evaporation crystallization technology to produce by-product salt. The filter cake produced by the solid-liquid separation device re-enters the sintering batching process as a sintering raw material and participates in the sintering process again, realizing the recycling of resources in the dust removal ash.

[0004] However, in the prior art, all dust removal ash is usually washed with the same water washing process, for example, all the dust removal ash from the head is washed with the same water washing process. Figure 4 The multi-stage water washing or single-stage water washing shown in the figure has an uncertain final washing liquid concentration due to the fact that the source or composition of the dust removal ash in the sintering plant is usually uncertain, and the water in the filter cake is brought from the slurry. The water in the slurry is actually an alkali metal solution, part of which goes through the clear liquid channel, and the rest goes with the filter cake. The alkali metal salts in the filter cake are brought by the alkali metal solution that goes with the filter cake, which may cause the alkali metal concentration of the filter cake to be higher than or lower than the alkali metal content of the sintering raw material. Since the Fe element in the dust removal ash is required for the sintering process, while alkali metals such as K and Na are not required for the sintering process, if the content of alkali metals such as K and Na is higher than the alkali metal content of the sintering raw material, the filter cake will re-enter the sintering process, which will cause the alkali metal to be enriched in the raw material, which is not conducive to the subsequent sintering production and the quality of the sintered ore.

[0005] In addition, since the source or composition of the dust removal ash in the sintering plant is usually uncertain, the final water washing liquid concentration is uncertain when the same water washing process is used. The final water washing liquid concentration produced in this way may be relatively high. For example, the alkali metal salt concentration in the clear liquid is close to the saturation concentration. In this case, when the temperature drops, KCl crystals in the clear liquid are prone to crystallize when cooled in the pipeline, which is prone to pipeline blockage and is not conducive to production. The final clear liquid concentration may also be low. For example, the alkali metal salt concentration in the clear liquid is far lower than the saturation concentration. In this case, more energy is required to evaporate the water in the water washing liquid in the subsequent evaporation and crystallization salt separation process, thereby increasing ineffective energy consumption.

[0006] Since the quality of the filter cake has a direct impact on the quality of the sintering raw materials, in actual production needs, the priority of controlling the filter cake quality is higher than the priority of controlling the clear liquid concentration. Therefore, it is of great significance to provide a hierarchical control method based on filter cake quality control and clear liquid concentration control.

[0007] In view of this, it is necessary to propose a single-stage water washing desalination system and its hierarchical control method and storage medium to solve or at least alleviate the above-mentioned defects. Summary of the Invention

[0008] The main purpose of the present invention is to provide a single-stage water washing desalination system and its hierarchical control method and storage medium, so as to solve the technical problem that the prior art is difficult to achieve hierarchical control of filter cake quality and clear liquid concentration in the water washing desalination system.

[0009] To achieve the above object, the present invention provides a hierarchical control method for a single-stage water washing and desalination system, comprising the steps of:

[0010] S1, during initial production, close the slurry outlet valve of the slurry tank, and introduce new water and dust ash into the slurry tank in proportion, so that the new water and the dust ash are mixed in the slurry tank to form slurry;

[0011] S2, after the slurry tank reaches a set liquid level, stop adding material, open the slurry outlet valve to allow the slurry to enter the solid-liquid separation device; wherein the solid-liquid separation device is used to receive the slurry and produce filter cake and clear liquid, and the clear liquid enters the clear liquid tank, and the clear liquid tank includes a first liquid outlet valve and a second liquid outlet valve, and the first liquid outlet valve and the second liquid outlet valve are in a closed state before the clear liquid tank reaches the set liquid level;

[0012] S3, obtaining a first alkali metal salt concentration of the clear liquid generated by the solid-liquid separation device and a water content of the filter cake, determining an alkali metal salt content of the filter cake based on the first alkali metal salt concentration and the water content, and first determining whether the alkali metal salt content of the filter cake is within an alkali metal salt control content range;

[0013] S4, when the alkali metal salt content of the filter cake is within the alkali metal salt control range, determining that the alkali metal in the filter cake will not be enriched in the sintering raw materials, and sending the filter cake to the sintering batching process to participate in sintering; and simultaneously obtaining a second alkali metal salt concentration of the clear liquid in the clear liquid tank before the clear liquid tank reaches a set liquid level;

[0014] S5, determining whether the second alkali metal salt concentration is within the alkali metal salt control concentration range;

[0015] S6. When the concentration of the second alkali metal salt is within the alkali metal salt control concentration range, it is determined that the concentration of the second alkali metal salt is within the desired range. After the clear liquid tank reaches the set liquid level, new water and dust removal ash are continued to be added to the slurry tank in proportion, and the second liquid outlet valve is opened to allow the clear liquid in the clear liquid tank to enter the subsequent evaporation and crystallization salt separation process; wherein the capacity of the slurry tank is greater than the capacity of the clear liquid tank.

[0016] Preferably, the step S5 further includes the following steps:

[0017] S51, when the second alkali metal salt concentration is greater than the upper limit of the alkali metal salt control concentration range, it is determined that the second alkali metal salt concentration is in a high concentration range, and steps S52 to S53 are executed;

[0018] S52, opening the second water inlet valve and increasing the valve opening of the second water inlet valve according to a preset step size;

[0019] S53, waiting for a first preset time, re-obtaining the second alkali metal salt concentration of the clear liquid in the clear liquid tank, and proceeding to step S5;

[0020] S54, when the second alkali metal salt concentration is less than the lower limit of the alkali metal salt control concentration range, it is determined that the second alkali metal salt concentration is in a low concentration range, and steps S55 to S57 are executed;

[0021] S55, opening the first liquid outlet valve to return the clear liquid in the clear liquid tank to the slurry tank, and continuing to add new water and dust removal ash to the slurry tank in proportion; wherein the flow rate of the first liquid outlet valve is controlled to be the same as the flow rate of the clear liquid generated by the solid-liquid separation device;

[0022] S56, waiting for a second preset time, re-obtaining the alkali metal salt content of the filter cake, and determining whether the alkali metal salt content of the filter cake is within the alkali metal salt control content range;

[0023] S57, when the alkali metal salt content of the filter cake is within the alkali metal salt control content range, it is determined that the alkali metal of the filter cake will not be enriched in the sintering raw material, and the produced filter cake is continued to be sent to the sintering batching process to participate in sintering, and the second alkali metal salt concentration of the clear liquid in the clear liquid tank is re-obtained, and the process proceeds to step S5.

[0024] Preferably, the step S56 further includes the following steps:

[0025] When the alkali metal salt content of the filter cake is greater than the upper limit of the alkali metal salt control content range, the first liquid outlet valve is closed and the second liquid outlet valve is opened to allow the clear liquid in the clear liquid tank to enter the subsequent evaporation crystallization salt separation process.

[0026] Preferably, the step S6 further includes the following steps:

[0027] S71, when the production condition is stable, obtain the alkali metal salt concentration of the clear liquid produced by the solid-liquid separation device at the current time k and the moisture content of the filter cake , according to the concentration of alkali metal salt and moisture content Determine the alkali metal salt content of the filter cake , and judge the alkali metal salt content of the filter cake Whether it is within the controlled content range of alkali metal salts;

[0028] S72, alkali metal salt content in filter cake When the content of alkali metal salt is within the control range, it is determined that the alkali metal in the filter cake will not be enriched in the sintering raw materials;

[0029] S73, obtaining the alkali metal salt concentration of the clear liquid in the clear liquid tank at time k+m , determine the concentration of alkali metal salt Whether it is within the control concentration range of alkali metal salt;

[0030] S74, at alkali metal salt concentration When the concentration of the alkali metal salt is within the control range, the current state is maintained and production continues.

[0031] Preferably, the step S71 further includes the following steps:

[0032] The concentration of alkali metal salts When the concentration of alkali metal salt is greater than the upper limit of the control concentration range of alkali metal salt, the alkali metal salt concentration is determined to be When the concentration is in the high range, the first water inlet valve is opened and the valve opening of the first water inlet valve is increased according to the preset step length; wait for t time, assign k+t to k, and return to step S71.

[0033] Preferably, the step S73 further includes the following steps:

[0034] S731, at the alkali metal salt concentration When the concentration of alkali metal salt is greater than the upper limit of the control concentration range of alkali metal salt, the alkali metal salt concentration is determined to be If the concentration is high, execute steps S732 to S733;

[0035] S732, opening the second water inlet valve and increasing the valve opening of the second water inlet valve according to a preset step size;

[0036] S733, wait for t time, assign k+m+t to k+m, and return to step S73;

[0037] S734, at the alkali metal salt concentration When the concentration of the alkali metal salt is less than the lower limit of the control concentration range of the alkali metal salt, it is determined that the concentration of the alkali metal salt is less than the lower limit of the control concentration range of the alkali metal salt. If the concentration is low, execute steps S735 to S737;

[0038] S735, opening the first liquid outlet valve to return the clear liquid in the clear liquid tank to the slurry tank, and continuing to add new water and dust removal ash to the slurry tank in proportion; wherein the flow rate of the first liquid outlet valve is controlled to be the same as the flow rate of the clear liquid generated by the solid-liquid separation device;

[0039] S736: Wait for time t and re-obtain the filter cake alkali metal salt content at time k+m+t , and judge the alkali metal salt content of the filter cake Whether it is within the controlled content range of alkali metal salts;

[0040] S737, alkali metal salt content in filter cake When the content of alkali metal salt is within the control range, it is determined that the alkali metal in the filter cake will not be enriched in the sintering raw materials, and the filter cake is continued to be sent to the sintering batching process to participate in sintering, and k+m+t is assigned to k+m, and the process returns to step S73.

[0041] Preferably, the step S736 further includes the following steps:

[0042] Alkali metal salt content in filter cake When the content of the alkali metal salt is greater than the upper limit of the control range, the first liquid outlet valve is closed and the second liquid outlet valve is opened to allow the clear liquid in the clear liquid tank to enter the subsequent evaporation crystallization salt separation process.

[0043] The present invention also provides a single-stage water washing and desalination system, comprising a slurry tank, a solid-liquid separation device, a clear liquid tank, and a control system, wherein the slurry tank comprises a slurry tank body, a first water inlet assembly for receiving external new water, an ash inlet assembly for receiving external dust ash, a liquid return assembly for receiving clear liquid returned from the clear liquid tank, and a slurry discharge assembly, wherein the first water inlet assembly is provided with a first water inlet valve, and the slurry discharge assembly is provided with a slurry discharge valve, water enters the slurry tank body through the first water inlet assembly, the dust ash enters the slurry tank body through the ash inlet assembly, and the water and dust ash are mixed in the slurry tank body to form slurry; the solid-liquid separation device is used to receive the slurry from the slurry discharge assembly and produce a first clear liquid and a filter cake;

[0044] The clear liquid tank includes a clear liquid tank body, a second water inlet assembly for receiving new water from the outside, a liquid inlet assembly for receiving the first clear liquid, a first liquid outlet assembly, and a second liquid outlet assembly, wherein the second water inlet assembly is provided with a second water inlet valve, the first liquid outlet assembly is provided with a first liquid outlet valve, and the second liquid outlet assembly is provided with a second liquid outlet valve. The first clear liquid enters the clear liquid tank body through the liquid inlet assembly, and the second clear liquid in the clear liquid tank body is transported to the subsequent evaporation, crystallization and salt separation process through the second liquid outlet assembly. The second clear liquid in the clear liquid tank body is transported to the slurry tank body through the first liquid outlet assembly and the liquid return assembly;

[0045] The first water inlet valve, slurry outlet valve, second water inlet valve, first liquid outlet valve and second liquid outlet valve are all connected to the control system. The control system includes a memory, a processor and a computer program stored in the memory and runnable on the processor. When the computer program is executed by the processor, the steps of the hierarchical control method of a single-stage water washing and desalination system as described above are implemented.

[0046] The present invention also provides a storage medium storing a computer program, which, when executed by a processor, implements the steps of the hierarchical control method for a single-stage water washing and desalination system as described above.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The present invention provides a single-stage water washing and desalination system and its hierarchical control method and storage medium. The present application realizes hierarchical control of the alkali metal salt content of the filter cake and the concentration of the clear liquid, and controls the concentration of the clear liquid within an appropriate range while ensuring the quality of the filter cake as much as possible. Specifically, the priority goal of the present application is to control the alkali metal salt content of the filter cake so that the filter cake does not lead to alkali metal enrichment when it is sintered again as a sintering raw material, thereby improving resource utilization. Secondly, on the basis of the quality control of the filter cake meeting the standards, the concentration of the clear liquid is judged. When the alkali metal salt concentration of the clear liquid is within an appropriate range, it can prevent the problem of excessive alkali metal salt concentration in the clear liquid and crystallization in the conveying pipeline, thereby preventing the pipeline from being blocked due to cold crystallization, and can also provide a higher concentration of clear liquid for the subsequent evaporation and crystallization process, thereby reducing ineffective energy consumption as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0050] Figure 1 is a schematic diagram of a flow chart in one embodiment of the present invention;

[0051] Figure 2 It is a schematic diagram of a sintering machine head electrostatic precipitator system in the prior art;

[0052] Figure 3 This is a typical ash unloading sequence diagram of the electrostatic precipitator of the four-electric field sintering head in the prior art;

[0053] Figure 4 This is a typical water washing desalination process flow chart in the prior art;

[0054] Figure 5 FIG. 1 is a schematic diagram of a system structure in one embodiment of the present invention.

[0055] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0056] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0058] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0059] In addition, the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0060] Those skilled in the art will be aware that with the rapid development of modern industry, the scale of steel production is expanding, energy consumption is increasing, and energy conservation and environmental protection indicators are becoming increasingly important considerations in the steel production process. In steel production, iron-containing raw ore must undergo a sintering system before entering the blast furnace for smelting. This process involves mixing various powdered iron-containing raw materials with appropriate amounts of fuel (pulverized coal, coke) and flux, adding an appropriate amount of fresh water, and then forming pellets. After this process, the raw materials are laid out on a sintering trolley and roasted, undergoing a series of physical and chemical changes to form a sintered ore that is easily smelted. This process is called sintering.

[0061] During sintering production, the dusty flue gas from the large flue must be treated through dust removal, desulfurization, denitrification and other purification processes before it can be discharged. The mainstream sintering flue gas dust removal method is to use the head electrostatic precipitator to treat the dust in the sintering large flue flue. The dust ash collected by the head electrostatic precipitator accounts for about 2% to 4% of the sintered ore production. A company with an annual output of 10 million tons of steel requires about 16 million tons of sintered ore, which will produce about 500,000 tons of dust ash per year. The schematic diagram of the head electrostatic precipitator of an existing large sintering machine is shown below. Figure 2 shown.

[0062] like Figure 2 As shown, the electric fields of the sintering machine head electrostatic precipitator are arranged in series in sequence. After the dust-laden flue gas is processed by each electric field, it enters the next process after meeting the entry standard. The dust collected by each electric field enters the ash storage bin of each electric field. The ash unloading system of the ash storage bin of each electric field operates according to the set program / ash unloading timing cycle. The dust from all electric fields is collected into the dust ash buffer bin by the dust ash conveying system. The dust collected in the dust ash buffer bin will be disposed of by the subsequent dust ash disposal process.

[0063] It is important to note that many ore raw materials contain high levels of alkali metal elements such as K and Na. Due to their low boiling points, the compounds formed by these alkali metal elements evaporate directly into the flue gas during the high-temperature sintering process, or are reduced by coke to the corresponding elemental metal gas, which escapes and condenses in the electrostatic precipitator system, combining with the Cl element present in the raw materials, and is then captured into the dust ash. The dust ash mainly contains various elements such as TFe, K, and Na (K and Na exist in the form of KCl and NaCl). It should be noted that the existing sintering dust ash disposal solutions are generally:

[0064] (1) Stockpiling (transportation is considered solid waste). The problem with stockpiling is that it requires a lot of storage space, and as production progresses, the accumulated dust will accumulate more and more, and eventually a way out will have to be found. Currently, all steel companies have a large amount of electrostatic precipitator dust stored in the machine head waiting to be disposed of;

[0065] (2) Directly re-enter the sintering batching process as a sintering raw material and participate in the sintering process again. The Fe element in the dust removal ash is required for the sintering process, but the re-entry of alkali metals such as K and Na into the sintering process is detrimental to subsequent sintering production and sintered ore quality. In addition, it will form a closed-loop circulation of dust, resulting in an increase in the ineffective load of the sintering system.

[0066] (3) After removing the K and Na elements from the dust ash, it can be used as a sintering raw material and participate in the sintering process without causing adverse effects on the sintering production. At present, the commonly used K and Na removal process is the water washing desalination method. The typical water washing desalination method flow chart is as follows: Figure 4 As shown:

[0067] like Figure 4 As shown in the figure, the sintering dust from the dust ash buffer bin and the new water are mixed in the slurry tank to generate slurry. The generated slurry is separated into solid and liquid in the solid-liquid separation device. KCl and NaCl are dissolved in the clear liquid and carried away by the clear liquid to the subsequent evaporation and crystallization process. The filter cake enters the secondary fresh water washing process or is sent to sintering. Because the K and Na content in the dust is high, multi-stage fresh water washing is required ( Figure 4 It is a single-stage water washing desalination system) to meet the requirements of removing K and Na elements;

[0068] like Figure 4 As shown, the primary clear liquid is sent to the evaporation crystallization salt separation process. The KCl and NaCl separated in the evaporation crystallization salt separation process can be sold as commodities, so the high content of KCl and NaCl in the filter cake is also a waste of raw materials.

[0069] It is worth noting that, as shown in Table 1 below, Table 1 is the composition (mass fraction) of the electrostatic precipitator ash in each electric field of the Anshan Iron and Steel sintering machine head electrostatic precipitator:

[0070]

[0071] Table 1 lists the composition (mass fraction) of the electrostatic precipitator dust from the die heads of the second and third sintering machines at Ansteel. This technical solution focuses on four components: TFe, FeO, NaCl, and KCl (boxed in the rectangular boxes in Table 1). TFe represents total iron, which is the sum of the iron in all iron-containing components in the ore (here, the die head dust). It is calculated from the total iron content in metallic iron (Fe), ferroferric oxide (Fe₃O₄), ferric oxide (Fe₂O₃), and ferrous oxide (FeO) in the ore. FeO is listed separately because its content is a critical indicator for blast furnace production and is therefore used to assess ore quality. The iron in the FeO column is already included in the TFe column.

[0072] As can be seen from the rectangular boxes in Table 1, the composition of the electrostatic precipitator ash from each sintering machine varies due to differences in raw material composition. However, a common characteristic is that the Fe content (TFe + FeO) is high and the alkali metal salt content (NaCl + KCl) is low in the first field. The Fe content (TFe + FeO) gradually decreases with subsequent fields, while the alkali metal salt content (NaCl + KCl) gradually increases. The compositional differences between the ash from each field are significant. This table is representative; the compositional distribution of the electrostatic precipitator ash from each field at steel companies is similar to that of Anshan Iron and Steel.

[0073] It should be noted that the dust removal efficiency of a single electric field of an electrostatic precipitator is about 80%. Taking into account the influence of the airflow moving backward from the first electric field and carrying away some of the falling dust, the dust removed by the first electric field accounts for about 60% of the total dust removed, and the dust removed by the second electric field is about 60% of the remaining 40%, that is, 24%. The same applies to the remaining electric fields.

[0074] like Figure 3 The die head electrostatic precipitator shown is a sintering die head electrostatic precipitator with four electric fields. The typical ash unloading logic of the ash storage bin in each electric field is as follows: Figure 3 As shown, specifically, the head electrostatic precipitator is periodically and continuously unloading dust during operation. In the figure, T1 is a standard unloading cycle, and subsequent unloading can be regarded as a repetition of multiple similar T1 standard unloading cycles. Figure 3 As shown, the T1 dust unloading cycle can be decomposed into 5 sections, namely:

[0075] TT0: The dust storage section of each electric field ash storage bin of the head dust collector. The dust unloading equipment of each dust removal electric field in the TT0 section does not work. The ash storage bin of each dust removal electric field stores the electrostatic precipitator ash collected by the electrostatic precipitator to form an ash storage bin material seal.

[0076] TT1: An electric field ash unloading section. At this time, the amount of ash stored in the ash storage bin of an electric field is close to or reaches the high material level, an electric field ash unloading equipment is working, and an electric field ash unloading is performed. The duration of ash unloading is TT1, and the start time point of ash unloading is t1. When the amount of ash stored in the ash storage bin of an electric field is close to or reaches the low material level, the electric field ash unloading ends, and the end time point of ash unloading is t2.

[0077] TT2: The second electric field ash unloading section. At this time, the ash storage volume in the ash storage bin of the second electric field is close to or reaches the high material level. The second electric field ash unloading equipment works and the second electric field unloads ash. The duration of ash unloading is TT2. The start time of ash unloading is t2. When the ash storage volume unloaded to the second electric field is close to or reaches the low material level, the second electric field ash unloading ends. The end time of ash unloading is t3.

[0078] TT3: Three-field ash unloading section. At this time, the ash storage volume in the ash storage bin of the three-field is close to or reaches the high material level. The three-field ash unloading equipment works and the three-field ash unloading lasts for TT3. The unloading start time is t3. When the ash storage volume in the ash storage bin of the three-field is close to or reaches the low material level, the second-field ash unloading ends, and the unloading end time is t4.

[0079] TT4: Four-field ash unloading section. At this time, the ash storage volume in the ash storage bin of the four-field is close to or reaches the high material level. The four-field ash unloading equipment works and the four-field ash unloading continues for TT4. The unloading start time is t4. When the ash storage volume in the ash storage bin of the four-field is close to or reaches the low material level, the four-field ash unloading ends. The unloading end time is t5.

[0080] T2 is the second dust unloading cycle, and the dust unloading of the head dust collector repeats the above cycle.

[0081] like Figure 2 and Figure 3 As shown, in actual production, the dust removal electric fields have the same dust unloading capacity, and the dust removal ash conveying system is configured with the conveying capacity according to the dust unloading amount of a single dust removal electric field, that is, the dust removal ash conveying system usually only allows one dust removal electric field to unload ash, and does not allow two dust removal electric fields to unload ash at the same time.

[0082] It should be understood by those skilled in the art that Figure 2 The dust collected in the dust collection buffer bin is Figure 4 The raw materials for the water washing and desalination process shown in the figure are as follows. Figure 3 The existing head electrostatic precipitator dust removal method shown in the figure will cause the dust collected by each electric field in the dust collection ash buffer bin to be as follows Figure 1 The distribution pattern shown is that the dust collected by the first electric field ash storage bin of the electrostatic precipitator is first received (roughly from high material level to low material level), and then the dust collected by the second electric field ash storage bin of the electrostatic precipitator is received, and the rest are deduced by analogy. 2 Sintering machine is used for calculation, a 360m 2 The sintering machine sintered 10,000 tons of ore daily, and the dust removal ash volume was calculated as 3% of 3%, which is 300 tons. The ash unloading cycle of the electrostatic precipitator at the machine head is 8 hours, and the ash unloading volume in one unloading cycle is 100 tons. If the normal ash storage capacity of the dust removal ash storage bin is 100 tons, then in the ash storage bin, there are ~60 tons of first-field dust removal ash in the continuous space of the dust removal ash storage bin, and ~24 tons of second-field dust removal ash is immediately behind it, and the remaining electric field ash is stored in the dust removal ash storage bin in the same way.

[0083] As shown in Table 1, the dust components of each electric field of the head electrostatic precipitator are quite different. Figure 3 The existing head electrostatic precipitator dust removal method shown will lead to Figure 4 The raw material composition of the water washing desalination method shown in the figure fluctuates greatly. Figure 4As an example of the water washing and desalination process, if the 360m 2 Within 8 hours, the sintering machine head ash will first receive ~60t of first-stage electric field dust removal ash, then ~24t of second-stage electric field dust removal ash, and so on. However, due to the influence of many interfering factors in the production process, it is difficult for the water washing and desalination process to determine the subsequent raw material composition.

[0084] Since the TFe and FeO contents in the dust removed by the first electric field are high and the NaCl and KCl contents are low, while the TFe and FeO contents in the subsequent electric fields decrease successively and the NaCl and KCl contents increase successively, it is obvious that the large fluctuations in the raw material composition and the uncertainty of the raw material composition will lead to large fluctuations in the filter cake output, TFe and FeO contents in the filter cake, and KCl and NaCl contents in the clear liquid of the water washing desalination method, and ultimately lead to unstable production in the water washing desalination process. This is also the main factor for the large production fluctuations, frequent equipment failures, high production costs and production jams in the existing single-stage water washing desalination process of electrostatic precipitator ash from the sintering machine head.

[0085] Please see the attached Figure 5 The present invention also provides a single-stage water washing and desalination system, comprising a slurry tank, a solid-liquid separation device, a clear liquid tank, and a control system (not shown), wherein the slurry tank comprises a slurry tank body, a first water inlet assembly for receiving external new water, an ash inlet assembly for receiving external dust ash, a liquid return assembly for receiving clear liquid returned from the clear liquid tank, and a slurry discharge assembly, wherein the first water inlet assembly is provided with a first water inlet valve, and the slurry discharge assembly is provided with a slurry discharge valve, water enters the slurry tank body through the first water inlet assembly, the dust ash enters the slurry tank body through the ash inlet assembly, and the water and dust ash are mixed in the slurry tank body to form a slurry; the solid-liquid separation device is used to receive the slurry from the slurry discharge assembly and produce a first clear liquid and a filter cake;

[0086] The clear liquid tank includes a clear liquid tank body, a second water inlet assembly for receiving new water from the outside, a liquid inlet assembly for receiving the first clear liquid, a first liquid outlet assembly, and a second liquid outlet assembly, wherein the second water inlet assembly is provided with a second water inlet valve, the first liquid outlet assembly is provided with a first liquid outlet valve, and the second liquid outlet assembly is provided with a second liquid outlet valve. The first clear liquid enters the clear liquid tank body through the liquid inlet assembly, and the second clear liquid in the clear liquid tank body is transported to a subsequent evaporation and crystallization salt separation process through the second liquid outlet assembly, or the second clear liquid in the clear liquid tank body is transported to the slurry tank body through the first liquid outlet assembly and the liquid return assembly;

[0087] The first water inlet valve, slurry outlet valve, second water inlet valve, first liquid outlet valve and second liquid outlet valve are all connected to the control system. The control system includes a memory, a processor and a computer program stored in the memory and runnable on the processor. When the computer program is executed by the processor, the steps of the hierarchical control method of a single-stage water washing and desalination system as described above are implemented.

[0088] Specifically, external fresh water enters the slurry tank body through the first water inlet assembly, while sintered dust ash enters the slurry tank body through the ash inlet assembly. Inside the slurry tank body, water and dust ash mix to form a slurry. The mixed slurry is output to the solid-liquid separation device through the slurry outlet valve of the slurry outlet assembly. The solid-liquid separation device receives the slurry from the slurry tank and produces a filter cake and a first clear liquid. The first clear liquid can enter the clear liquid tank body through the liquid inlet assembly. In the clear liquid tank, the second clear liquid can be transported to the subsequent evaporation crystallization and salt separation process for further processing through the second liquid outlet assembly. Alternatively, the second clear liquid can also be returned to the slurry tank body through the first liquid outlet assembly and the liquid return assembly for circulating water washing to increase the clear liquid concentration. When the amount of clear liquid in the clear liquid tank is insufficient or the clear liquid concentration needs to be adjusted, external fresh water can enter the clear liquid tank body through the second water inlet valve of the second water inlet assembly. Compared with traditional water washing and desalination systems, this system has the advantages of simple structure, easy operation, and low maintenance cost.

[0089] Please refer to Figures 1 to 5 The present invention provides a hierarchical control method for a single-stage water washing and desalination system, comprising the following steps:

[0090] S1, during initial production, close the slurry outlet valve of the slurry tank, and introduce new water and dust ash into the slurry tank in proportion, so that the new water and the dust ash are mixed in the slurry tank to form slurry;

[0091] Preferably, the step S1 of introducing new water and dust ash into the slurry tank in proportion comprises the following steps: the new water and dust ash are mixed in accordance with the static new water-ash ratio CK. AB Entering the slurry tank; wherein the static new water-cement ratio CK AB The value range is 2~4. It is worth noting that the static water-cement ratio CK AB The principle of determination is that the water-cement can be fully mixed to form a slurry with good fluidity, and the static water-cement ratio CK AB It can be obtained through water-cement mixing experiments and production experience. The commonly used static water-cement ratio CK AB The commonly used value range is 2~4.

[0092] S2, stop adding material after the slurry tank reaches the set liquid level, open the slurry discharge valve to allow the slurry to enter the solid-liquid separation device; wherein, the solid-liquid separation device is used to receive the slurry and produce filter cake and clear liquid, and the clear liquid enters the clear liquid tank, and the clear liquid tank includes a first liquid outlet valve and a second liquid outlet valve, and the first liquid outlet valve and the second liquid outlet valve are in a closed state before the clear liquid tank reaches the set liquid level; wherein, the set liquid level can be pre-set, for example, the slurry tank reaches 85% of the capacity.

[0093] S3, obtaining a first alkali metal salt concentration of the clear liquid generated by the solid-liquid separation device and a water content of the filter cake, determining an alkali metal salt content of the filter cake based on the first alkali metal salt concentration and the water content, and first determining whether the alkali metal salt content of the filter cake is within an alkali metal salt control content range;

[0094] Specifically, the priority goal of this application is to control the alkali metal salt content of the filter cake so that the filter cake will not be enriched in alkali metals when it is used as a sintering raw material for sintering again. If the alkali metal salt content of the filter cake is higher than the upper limit of the alkali metal salt control content range, the alkali metal content of the filter cake will be enriched in the raw material. Since the Fe element in the dust removal ash is required for the sintering process, the re-entry of alkali metals such as K and Na into the sintering process is not conducive to subsequent sintering production and sintered ore quality. In addition, a closed-loop circulation of dust will be formed, resulting in an increase in the invalid load of the sintering system; if it is lower than the upper limit of the alkali metal salt control content range, the alkali metal content of the filter cake will not be enriched in the raw material. The filter cake can be used as a sintering production raw material to participate in the sintering batching without causing adverse effects on sintering production, thereby improving resource utilization. Therefore, this application prioritizes determining the alkali metal salt content of the filter cake.

[0095] Furthermore, the alkali metal salt content of the filter cake can be determined by the first alkali metal salt concentration and the moisture content, wherein the first alkali metal salt concentration can be detected online by a concentration meter, and the moisture content of the filter cake can be obtained by detection by a microwave moisture meter, or combined with actual historical data, it can be known that the actual filter cake moisture content that can be achieved by the solid-liquid separation device is between 20% and 30%. The current filter cake moisture content can be obtained based on the operating condition settings of the solid-liquid separation device (such as centrifuge speed, residence time, filter press pressure, etc.) and production experience. The filter cake moisture content can be regarded as a constant under stable production conditions.

[0096] Furthermore, the water in the filter cake is brought from the slurry. The water in the slurry is actually an alkali metal solution. Part of it flows through the clear liquid channel, and the rest flows with the filter cake. The alkali metal salt in the filter cake is brought by the alkali metal solution that flows with the filter cake. In summary, the alkali metal salt content in the filter cake can be calculated as shown in Formula 3b:

[0097] Formula 3b

[0098] Of which: NDB1 is the alkali metal salt content of filter cake B1, unit: % CM B1 is the amount of filter cake produced by the solid-liquid separation device, unit: kg; HS B1 is the moisture content in filter cake B1, unit: % ND G1 is the first alkali metal salt concentration of the clear solution G1, unit: %;

[0099] As a preferred embodiment, the present application provides a method for determining the controlled content range of alkali metal salt, as follows:

[0100] Table 2: Ingredients used in sintering

[0101]

[0102] As shown in Table 2, steel companies determine the sintering ingredient ratio within the next production cycle based on raw material inventory, production demand, etc.; steel companies can plan different ratios based on raw material inventory, production demand, etc.; the alkali metal (K, Na) content in each raw material component is different, and the alkali metal (K, Na) content in each raw material component is known (it can be obtained through existing mature technical means, which will not be detailed here); the alkali metal content (K, Na) of different ratios can be calculated based on the ingredient list. For example, the alkali metal content calculated for ratio 1 is J1, and the alkali metal content calculated for ratio 2 is J2;

[0103] As shown in Table 1, the alkali metal salts in the dust removal ash are mainly KCl, NaCl accounts for 5.6% of the alkali metal salts, and KCl accounts for 94.4% of the alkali metal salts. In the sintering raw materials, alkali metals exist in various forms and form alkali metal salts (NaCl, KCl) during the sintering process. The alkali metal salt content in the dust removal ash can be converted into alkali metal content according to Formula 1:

[0104] ;Formula 1

[0105] Wherein: k1 is the alkali metal content, unit: %; k2 is the alkali metal salt content, unit: %; 19 is the sequence number of K element in the periodic table; 17 is the sequence number of Cl element in the periodic table;

[0106] Because the alkali metal salt in the dust removal ash is mainly KCl, NaCl accounts for 5.6% of the alkali metal salt, and KCl accounts for 94.4% of the alkali metal salt. Considering the allowable deviation in engineering, in order to simplify the calculation, in the preferred embodiment, the influence of NaCl is not considered in Formula 1;

[0107] If a sintering process is produced using ratio 1, the alkali metal content in the sintering raw materials is J1. Under the production conditions of ratio 1, if the converted alkali metal content of the electrostatic precipitator filter cake after water washing meets the requirements of formula 2, the alkali metal will not be enriched in the raw materials, that is, the water washing and desalination process meets the requirements for removing alkali metals.

[0108] ;Formula 2

[0109] ;Formula 3

[0110] Therefore, the control standard of alkali metal salt of filter cake B1 in the water washing and desalination process can be set:

[0111] Formula 3a

[0112] Of which: ND B1 is the alkali metal salt content in the filter cake, unit: %; H is the correction factor for engineering errors such as measurement, which can be 1.0~1.5; J1 is the alkali metal content in sintering ratio 1, unit: %; k2 is the control standard for alkali metal salt content in the filter cake, unit: %

[0113] As shown in Formula 3, if the alkali metal salt content in the filter cake meets the requirements of Formula 3, it means that after the filter cake re-enters the sintering ingredients, the alkali metal content in the filter cake is less than or equal to the alkali metal content in the sintering ingredients, that is, at this time, the filter cake entering the sintering will not lead to the enrichment of alkali metals.

[0114] As a preferred example, 0~k2 can be taken as the controlled content range of the alkali metal salt.

[0115] S4, when the alkali metal salt content of the filter cake is within the alkali metal salt control range, determining that the alkali metal in the filter cake will not be enriched in the sintering raw materials, and sending the filter cake to the sintering batching process to participate in sintering; and simultaneously obtaining a second alkali metal salt concentration of the clear liquid in the clear liquid tank before the clear liquid tank reaches a set liquid level;

[0116] It is worth noting that when the alkali metal salt content of the filter cake is within the alkali metal salt control content range, that is, the quality of the filter cake is effectively controlled first, then the concentration of the clear liquid is further judged. Specifically, the second alkali metal salt concentration of the clear liquid in the clear liquid tank is obtained before the clear liquid tank reaches the set liquid level, wherein the second alkali metal salt concentration can be obtained by setting a concentration meter to achieve online real-time detection.

[0117] S5, determining whether the second alkali metal salt concentration is within the alkali metal salt control concentration range;

[0118] Preferably, the target concentration of the alkali metal salt is obtained by the following steps:

[0119] Get the current clear liquid temperature T1 in the clear liquid tank and the saturated concentration of KCl at temperature T1 , unit %; according to the formula Determine the target concentration of the alkali metal salt , unit %, where is the calculation coefficient, dimensionless, ranging from 0.5 to 0.8;

[0120] It is worth noting that, as shown in Table 1, the alkali metal salts in the dust removal ash are mainly KCl, NaCl accounts for 5.6% of the alkali metal salts, and KCl accounts for 94.4% of the alkali metal salts. In the preferred embodiment, the concentration of KCl is used as the judgment condition for the concentration of the alkali metal salts. It is also worth noting that the solubility (i.e., saturation concentration) of each substance at different temperatures is different. For KCl, as the temperature increases, its solubility in water also increases. The saturation concentration of KCl at temperature T1 can be determined by consulting the relevant solubility table or using the empirical formula. After determining the saturation concentration of KCl, the coefficient is calculated using the above formula. The formula is used to calculate the target concentration of alkali metal in the clear solution, and the calculation coefficient is It is a value between 0.5 and 0.8 and can be determined based on experimental data or engineering experience.

[0121] Specifically, according to this formula, if the alkali metal salt concentration in the clear liquid is close to the saturation concentration, then when the temperature drops, KCl crystals in the clear liquid are likely to crystallize in the pipeline, easily clogging the pipeline and hindering production. If the alkali metal salt concentration in the clear liquid is far below the saturation concentration, more energy will be consumed to evaporate water in the subsequent evaporation and crystallization salt separation process, which is not conducive to the subsequent evaporation and crystallization salt separation process. Therefore, it is appropriate to use 50% to 80% of the saturation concentration of the clear liquid as the control target for the clear liquid concentration. The specific coefficient can be ultimately determined based on production experience. Alternatively, in another preferred example, the clear liquid concentration can also be controlled to fluctuate within a certain range, such as 75% to 80%, which is more conducive to production regulation.

[0122] This embodiment considers the effect of temperature on the solubility of KCl and determines the target concentration of the alkali metal in the clear liquid accordingly, thereby achieving precise control of the alkali metal salt concentration in the clear liquid. Controlling the alkali metal salt concentration of the clear liquid according to this target can avoid the problem of crystallization in the pipeline due to cooling or increased ineffective energy consumption caused by excessively high or low concentrations.

[0123] As a better example, take 75%~80% of the alkali metal salt is used to control the concentration range.

[0124] S6. When the concentration of the second alkali metal salt is within the alkali metal salt control concentration range, it is determined that the concentration of the second alkali metal salt is within the desired range. After the clear liquid tank reaches the set liquid level, new water and dust removal ash are continued to be added to the slurry tank in proportion, and the second liquid outlet valve is opened to allow the clear liquid in the clear liquid tank to enter the subsequent evaporation and crystallization salt separation process; wherein the capacity of the slurry tank is greater than the capacity of the clear liquid tank.

[0125] Specifically, when the second alkali metal salt concentration is within the alkali metal salt control concentration range, it is determined that the second alkali metal salt concentration is within the desired range, and the concentration of the clear liquid is considered to be within the desired range. After the clear liquid tank reaches the set liquid level, the second liquid outlet valve is opened to send the clear liquid to the evaporation and crystallization salt separation process. The clear liquid removes water by evaporation, causing the alkali metal salt to crystallize and precipitate, thereby achieving the separation and recovery of salts, realizing the resource utilization of industrial waste, and reducing environmental pollution. At this time, the alkali metal salt concentration of the clear liquid is within an appropriate range, neither too high nor too low, which can prevent the problem of excessive alkali metal salt concentration in the clear liquid and crystallization in the delivery pipeline from clogging the pipeline, and can also provide a higher concentration of clear liquid for the subsequent evaporation and crystallization process, thereby minimizing ineffective energy consumption, thereby achieving graded control of filter cake quality and clear liquid.

[0126] As a preferred embodiment, the step S5 further includes the following steps:

[0127] S51, when the second alkali metal salt concentration is greater than the upper limit of the alkali metal salt control concentration range, it is determined that the second alkali metal salt concentration is in a high concentration range, and steps S52 to S53 are executed;

[0128] S52, opening the second water inlet valve and increasing the valve opening of the second water inlet valve according to a preset step size;

[0129] S53, waiting for a first preset time, re-obtaining the second alkali metal salt concentration of the clear liquid in the clear liquid tank, and proceeding to step S5;

[0130] S54, when the second alkali metal salt concentration is less than the lower limit of the alkali metal salt control concentration range, it is determined that the second alkali metal salt concentration is in a low concentration range, and steps S55 to S57 are executed;

[0131] S55, opening the first liquid outlet valve to return the clear liquid in the clear liquid tank to the slurry tank, and continuing to add new water and dust removal ash to the slurry tank in proportion; wherein the flow rate of the first liquid outlet valve is controlled to be the same as the flow rate of the clear liquid generated by the solid-liquid separation device;

[0132] S56, waiting for a second preset time, re-obtaining the alkali metal salt content of the filter cake, and determining whether the alkali metal salt content of the filter cake is within the alkali metal salt control content range;

[0133] S57, when the alkali metal salt content of the filter cake is within the alkali metal salt control content range, it is determined that the alkali metal of the filter cake will not be enriched in the sintering raw material, and the produced filter cake is continued to be sent to the sintering batching process to participate in sintering, and the second alkali metal salt concentration of the clear liquid in the clear liquid tank is re-obtained, and the process proceeds to step S5.

[0134] Specifically, when the second alkali metal salt concentration is greater than the upper limit of the alkali metal salt control concentration range, it indicates that the alkali metal salt concentration of the clear liquid is too high, and the alkali metal salt concentration of the clear liquid in the clear liquid tank is determined to be in a high concentration range. If the clear liquid is directly sent to the subsequent evaporation and crystallization salt separation process at this time, crystallization is likely to occur in the conveying pipeline, which is likely to clog the pipeline, thereby being detrimental to production.

[0135] Therefore, in this embodiment, the clear liquid is diluted by adding an appropriate amount of water to the clear liquid tank to control the alkali metal salt concentration of the clear liquid within a desired range. The water flow rate of the water inlet valve is gradually increased by gradually increasing the valve opening by a preset step size (for example, increasing the opening by 3% each time), thereby increasing the water flow rate entering the clear liquid tank. After waiting for a first preset time duration (for example, 10 seconds), the second alkali metal salt concentration of the clear liquid in the clear liquid tank is re-obtained. For example, after the first increase in the preset step size, the second alkali metal salt concentration of the clear liquid in the clear liquid tank may be within the alkali metal salt control concentration range, or it may still be above the upper limit of the alkali metal salt control concentration range. Therefore, the process returns to step S5 to re-determine the clear liquid concentration. If the conditions are not met, the valve opening is increased by a second preset step size until it is within the alkali metal salt control concentration range.

[0136] Similarly, when the second alkali metal salt concentration is less than the lower limit of the alkali metal salt control concentration range, it means that the alkali metal salt concentration of the clear liquid is low. If the clear liquid is directly sent to the subsequent evaporation and crystallization salt separation process at this time, the basic principle of the evaporation and crystallization process is to heat the KCl and NaCl mixed solution to evaporate the water in the KCl and NaCl mixed solution, so that the KCl and NaCl in the mixed solution are supersaturated, thereby forming KCl and NaCl crystals, and finally obtaining KCl and NaCl products. If the alkali metal salt concentration of the clear liquid is lower, more water needs to be evaporated, which requires a large amount of ineffective energy consumption.

[0137] In this case, new water and dust removal ash are continuously added to the slurry tank in proportion to maintain production activities and increase the concentration of the subsequent clear liquid. After the clear liquid tank reaches the set liquid level, the clear liquid is not directly sent to the subsequent evaporation and crystallization salt separation process. Instead, the first liquid outlet valve is opened to return the low-concentration clear liquid to the slurry tank for another water washing process. At the same time, the flow rate of the first liquid outlet valve is controlled to make it the same as the clear liquid flow rate generated by the solid-liquid separation device to maintain the stability and continuity of the system, so that a clear liquid-enriched salt circulation system is formed between the slurry tank, the solid-liquid separation device, and the clear liquid tank.

[0138] However, it is worth noting that although returning the clear liquid in the clear liquid tank to the slurry tank can increase the second alkali metal salt concentration, the enrichment of the alkali metal salt will also increase the alkali metal salt content of the filter cake. Since the quality of the filter cake is the primary control target of this application, it is necessary to further determine whether the alkali metal salt content of the filter cake is within the alkali metal salt control content range. When the alkali metal salt content of the filter cake is within the alkali metal salt control content range, it is determined that the filter cake alkali metal will not be enriched in the sintering raw materials, and the resulting filter cake is continued to be sent to the sintering batching process to participate in sintering, and the second alkali metal salt concentration of the clear liquid in the clear liquid tank is re-obtained, and step S5 is entered. The purpose of entering step S5 is to again determine whether the clear liquid concentration meets the conditions and then execute according to the corresponding conditions above.

[0139] Furthermore, the step S56 further includes the following steps:

[0140] When the alkali metal salt content of the filter cake is greater than the upper limit of the alkali metal salt control content range, the first liquid outlet valve is closed and the second liquid outlet valve is opened to allow the clear liquid in the clear liquid tank to enter the subsequent evaporation crystallization salt separation process.

[0141] It is worth noting that if the alkali metal salt content of the filter cake is greater than the upper limit of the alkali metal salt control content range, it means that the current circulation system of the clear liquid enriched salt will cause the filter cake quality to be substandard. The first liquid outlet valve is closed and the second liquid outlet valve is opened to allow the clear liquid in the clear liquid tank to enter the subsequent evaporation crystallization salt separation process, cutting off the circulation system of the clear liquid enriched salt. The liquid inlet of the slurry tank is only supplied by new water. Therefore, the alkali metal salt content of the filter cake will gradually decrease to the alkali metal salt control content range. At this time, regardless of the clear liquid concentration control, the clear liquid in the clear liquid tank will directly enter the subsequent evaporation crystallization salt separation process to ensure the primary goal of filter cake quality control.

[0142] As a preferred embodiment, the step S6 further includes the following steps:

[0143] S71, when the production condition is stable, obtain the alkali metal salt concentration of the clear liquid produced by the solid-liquid separation device at the current time k and the moisture content of the filter cake , according to the concentration of alkali metal salt and moisture content Determine the alkali metal salt content of the filter cake , and judge the alkali metal salt content of the filter cake Whether it is within the controlled content range of alkali metal salts;

[0144] S72, alkali metal salt content in filter cake When the content of alkali metal salt is within the control range, it is determined that the alkali metal in the filter cake will not be enriched in the sintering raw materials;

[0145] S73, obtaining the alkali metal salt concentration of the clear liquid in the clear liquid tank at time k+m , determine the concentration of alkali metal salt Whether it is within the control concentration range of alkali metal salt;

[0146] S74, at alkali metal salt concentration When the concentration of the alkali metal salt is within the control range, the current state is maintained and production continues.

[0147] Preferably, the step S71 further includes the following steps:

[0148] The concentration of alkali metal salts When the concentration of alkali metal salt is greater than the upper limit of the control concentration range of alkali metal salt, the alkali metal salt concentration is determined to be When the concentration is in the high range, the first water inlet valve is opened and the valve opening of the first water inlet valve is increased according to the preset step length; wait for t time, assign k+t to k, and return to step S71.

[0149] It is worth noting that in order to continuously achieve the graded control of the filter cake quality and the clear liquid under stable production conditions, the present embodiment obtains the filter cake alkali metal salt content at the time k of stable production. , the alkali metal salt content in the filter cake When the alkali metal salt content is within the control range, it is determined that the alkali metal in the filter cake will not be enriched in the sintering raw materials, indicating that the filter cake quality is controlled within the appropriate range. At this time, the alkali metal salt concentration in the clear liquid tank at time k+m (for example, 5s after time k) is , determine the concentration of alkali metal salt Is it within the control concentration range of alkali metal salt? When the concentration of the alkali metal salt is within the control range, the current state is maintained and production continues, which indicates that the concentration of the clear solution is also controlled within the appropriate range.

[0150] Since the source or composition of the dust from the sintering plant is usually uncertain, the concentration of alkali metal salts in the filter cake may increase. When the concentration of alkali metal salt is greater than the upper limit of the control concentration range of alkali metal salt, the alkali metal salt concentration is determined to be If the concentration is high, the first water inlet valve is opened and its opening is increased in preset increments (e.g., 3% increments). After waiting for a time t (e.g., 10 seconds), k is assigned the value k+t, and the process returns to step S71. Returning to step S71, the filter cake alkali metal salt content is re-tested and the corresponding control steps are performed according to the above steps.

[0151] Furthermore, the step S73 further includes the following steps:

[0152] S731, at the alkali metal salt concentration When the concentration of alkali metal salt is greater than the upper limit of the control concentration range of alkali metal salt, the alkali metal salt concentration is determined to be If the concentration is high, execute steps S732 to S733;

[0153] S732, opening the second water inlet valve and increasing the valve opening of the second water inlet valve according to a preset step size;

[0154] S733, wait for t time, assign k+m+t to k+m, and return to step S73;

[0155] S734, at the alkali metal salt concentration When the concentration of the alkali metal salt is less than the lower limit of the control concentration range of the alkali metal salt, it is determined that the concentration of the alkali metal salt is less than the lower limit of the control concentration range of the alkali metal salt. If the concentration is low, execute steps S735 to S737;

[0156] S735, opening the first liquid outlet valve to return the clear liquid in the clear liquid tank to the slurry tank, and continuing to add new water and dust removal ash to the slurry tank in proportion; wherein the flow rate of the first liquid outlet valve is controlled to be the same as the flow rate of the clear liquid generated by the solid-liquid separation device;

[0157] S736: Wait for time t and re-obtain the filter cake alkali metal salt content at time k+m+t , and judge the alkali metal salt content of the filter cake Whether it is within the controlled content range of alkali metal salts;

[0158] S737, alkali metal salt content in filter cake When the content of alkali metal salt is within the control range, it is determined that the alkali metal in the filter cake will not be enriched in the sintering raw materials, and the filter cake is continued to be sent to the sintering batching process to participate in sintering, and k+m+t is assigned to k+m, and the process returns to step S73.

[0159] Specifically, at the alkali metal salt concentration When the value is greater than the upper limit of the alkali metal salt control concentration range, it indicates that the alkali metal salt concentration of the clear liquid is too high, and the alkali metal salt concentration of the clear liquid in the clear liquid tank is determined to be in a high concentration range. If the clear liquid is directly sent to the subsequent evaporation and crystallization salt separation process at this time, crystallization is likely to occur in the conveying pipeline, which is easy to block the pipeline, thus being detrimental to production.

[0160] Therefore, in this embodiment, the clear liquid is diluted by adding an appropriate amount of water to the clear liquid tank to control the alkali metal salt concentration of the clear liquid to be within the desired range. The water flow rate of the water inlet valve is gradually increased by increasing the valve opening by a preset step size (for example, increasing the opening by 3% each time), thereby increasing the water flow rate entering the clear liquid tank. After waiting for a period of time t (for example, 10 seconds), the alkali metal salt concentration of the clear liquid in the clear liquid tank is re-obtained. For example, after increasing the preset step size for the first time, the alkali metal salt concentration of the clear liquid in the clear liquid tank is obtained again. It may be within the alkali metal salt control concentration range, or it may still be higher than the upper limit of the alkali metal salt control concentration range. Therefore, return to step S73 to judge the clear liquid concentration again. If the conditions are not met, continue to increase the preset step size to increase the valve opening for the second time until it is within the alkali metal salt control concentration range.

[0161] Likewise, at the alkali metal salt concentration When the concentration of the alkali metal salt is less than the lower limit of the control range of the alkali metal salt, it means that the alkali metal salt concentration of the clear liquid is too low. If the clear liquid is directly sent to the subsequent evaporation and crystallization salt separation process at this time, the basic principle of the evaporation and crystallization process is to heat the KCl and NaCl mixed solution to evaporate the water in the KCl and NaCl mixed solution, so that the KCl and NaCl in the mixed solution are supersaturated, thereby forming KCl and NaCl crystals, and finally obtaining KCl and NaCl products. The lower the concentration of the alkali metal salt in the clear liquid, the more water needs to be evaporated, which requires a lot of ineffective energy consumption.

[0162] In this case, new water and dust removal ash are continuously added to the slurry tank in proportion to maintain production activities and increase the concentration of the subsequent clear liquid. After the clear liquid tank reaches the set liquid level, the clear liquid is not directly sent to the subsequent evaporation and crystallization salt separation process. Instead, the first liquid outlet valve is opened to return the low-concentration clear liquid to the slurry tank for another water washing process. At the same time, the flow rate of the first liquid outlet valve is controlled to make it the same as the clear liquid flow rate generated by the solid-liquid separation device to maintain the stability and continuity of the system, so that a clear liquid-enriched salt circulation system is formed between the slurry tank, the solid-liquid separation device, and the clear liquid tank.

[0163] However, it is worth noting that although returning the clear liquid in the clear liquid tank to the slurry tank can increase the second alkali metal salt concentration, the enrichment of the alkali metal salt will also increase the alkali metal salt content of the filter cake. Since the quality of the filter cake is the primary control target of this application, it is necessary to further determine whether the alkali metal salt content of the filter cake is within the alkali metal salt control content range. When the alkali metal salt content of the filter cake is within the alkali metal salt control content range, it is determined that the filter cake alkali metal will not be enriched in the sintering raw materials, and the resulting filter cake is continued to be sent to the sintering batching process to participate in sintering, and the second alkali metal salt concentration of the clear liquid in the clear liquid tank is re-obtained, and step S73 is entered. The purpose of entering step S73 is to again determine whether the clear liquid concentration meets the conditions and then execute according to the corresponding conditions above.

[0164] Furthermore, the step S736 further includes the following steps:

[0165] Alkali metal salt content in filter cake When the content of the alkali metal salt is greater than the upper limit of the control range, the first liquid outlet valve is closed and the second liquid outlet valve is opened to allow the clear liquid in the clear liquid tank to enter the subsequent evaporation crystallization salt separation process.

[0166] If the filter cake alkali metal salt content If the value of the clear liquid concentration is greater than the upper limit of the control range of the alkali metal salt content, it means that the current circulation system of the clear liquid enriched salt will cause the filter cake quality to be substandard. The first liquid outlet valve is closed and the second liquid outlet valve is opened to allow the clear liquid in the clear liquid tank to enter the subsequent evaporation crystallization salt separation process, cutting off the circulation system of the clear liquid enriched salt. The liquid inlet of the slurry tank is only supplied by new water. Therefore, the alkali metal salt content of the filter cake will gradually decrease to the control range of the alkali metal salt content. At this time, regardless of the clear liquid concentration control, the clear liquid in the clear liquid tank will directly enter the subsequent evaporation crystallization salt separation process to ensure the primary goal of filter cake quality control.

[0167] The present invention also provides a storage medium storing a computer program. When executed by a processor, the computer program implements the steps of the aforementioned hierarchical control method for a single-stage water washing and desalination system. It is understood that, when executed by the processor, the aforementioned hierarchical control method for a single-stage water washing and desalination system is implemented. Therefore, all embodiments of the aforementioned method are applicable to this storage medium and can achieve the same or similar beneficial effects.

[0168] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A hierarchical control method for a single-stage water washing and desalination system, characterized in that: Including steps: S1, during initial production, close the slurry outlet valve of the slurry tank, and introduce new water and dust ash into the slurry tank in proportion, so that the new water and the dust ash are mixed in the slurry tank to form slurry; S2, after the slurry tank reaches a set liquid level, stop adding material, open the slurry outlet valve to allow the slurry to enter the solid-liquid separation device; wherein the solid-liquid separation device is used to receive the slurry and produce filter cake and clear liquid, and the clear liquid enters the clear liquid tank, and the clear liquid tank includes a first liquid outlet valve and a second liquid outlet valve, and the first liquid outlet valve and the second liquid outlet valve are in a closed state before the clear liquid tank reaches the set liquid level; S3, obtaining a first alkali metal salt concentration of the clear liquid generated by the solid-liquid separation device and a water content of the filter cake, determining an alkali metal salt content of the filter cake based on the first alkali metal salt concentration and the water content, and first determining whether the alkali metal salt content of the filter cake is within an alkali metal salt control content range; S4, when the alkali metal salt content of the filter cake is within the alkali metal salt control range, determining that the alkali metal in the filter cake will not be enriched in the sintering raw materials, and sending the filter cake to the sintering batching process to participate in sintering; and simultaneously obtaining a second alkali metal salt concentration of the clear liquid in the clear liquid tank before the clear liquid tank reaches a set liquid level; S5, determining whether the second alkali metal salt concentration is within the alkali metal salt control concentration range; S6. When the concentration of the second alkali metal salt is within the alkali metal salt control concentration range, it is determined that the concentration of the second alkali metal salt is within the desired range. After the clear liquid tank reaches the set liquid level, new water and dust removal ash are continued to be added to the slurry tank in proportion, and the second liquid outlet valve is opened to allow the clear liquid in the clear liquid tank to enter the subsequent evaporation and crystallization salt separation process; wherein the capacity of the slurry tank is greater than the capacity of the clear liquid tank.

2. The hierarchical control method for a single-stage water washing and desalination system according to claim 1, characterized in that: The step S5 further includes the following steps: S51, when the second alkali metal salt concentration is greater than the upper limit of the alkali metal salt control concentration range, it is determined that the second alkali metal salt concentration is in a high concentration range, and steps S52 to S53 are executed; S52, opening the second water inlet valve and increasing the valve opening of the second water inlet valve according to a preset step size; S53, waiting for a first preset time, re-obtaining the second alkali metal salt concentration of the clear liquid in the clear liquid tank, and proceeding to step S5; S54, when the second alkali metal salt concentration is less than the lower limit of the alkali metal salt control concentration range, it is determined that the second alkali metal salt concentration is in a low concentration range, and steps S55 to S57 are executed; S55, opening the first liquid outlet valve to return the clear liquid in the clear liquid tank to the slurry tank, and continuing to add new water and dust removal ash to the slurry tank in proportion; wherein the flow rate of the first liquid outlet valve is controlled to be the same as the flow rate of the clear liquid generated by the solid-liquid separation device; S56, waiting for a second preset time, re-obtaining the alkali metal salt content of the filter cake, and determining whether the alkali metal salt content of the filter cake is within the alkali metal salt control content range; S57, when the alkali metal salt content of the filter cake is within the alkali metal salt control content range, it is determined that the alkali metal of the filter cake will not be enriched in the sintering raw material, and the produced filter cake is continued to be sent to the sintering batching process to participate in sintering, and the second alkali metal salt concentration of the clear liquid in the clear liquid tank is re-obtained, and the process proceeds to step S5.

3. The hierarchical control method for a single-stage water washing and desalination system according to claim 2, characterized in that: The step S56 further includes the following steps: When the alkali metal salt content of the filter cake is greater than the upper limit of the alkali metal salt control content range, the first liquid outlet valve is closed and the second liquid outlet valve is opened to allow the clear liquid in the clear liquid tank to enter the subsequent evaporation crystallization salt separation process.

4. The hierarchical control method for a single-stage water washing and desalination system according to claim 3, characterized in that: The step S6 further includes the following steps: S71, when the production condition is stable, obtain the alkali metal salt concentration of the clear liquid produced by the solid-liquid separation device at the current time k and the moisture content of the filter cake , according to the concentration of alkali metal salt and moisture content Determine the alkali metal salt content of the filter cake , and judge the alkali metal salt content of the filter cake Whether it is within the controlled content range of alkali metal salts; S72, alkali metal salt content in filter cake When the content of alkali metal salt is within the control range, it is determined that the alkali metal in the filter cake will not be enriched in the sintering raw materials; S73, obtaining the alkali metal salt concentration of the clear liquid in the clear liquid tank at time k+m , determine the concentration of alkali metal salt Whether it is within the control concentration range of alkali metal salt; S74, at alkali metal salt concentration When the concentration of the alkali metal salt is within the control range, the current state is maintained and production continues.

5. The hierarchical control method for a single-stage water washing and desalination system according to claim 4, characterized in that: The step S71 further includes the following steps: The concentration of alkali metal salts When the concentration of alkali metal salt is greater than the upper limit of the control concentration range of alkali metal salt, the alkali metal salt concentration is determined to be When the concentration is high, the first water inlet valve is opened and the valve opening of the first water inlet valve is increased according to the preset step length; Wait for time t, assign k+t to k, and return to step S71.

6. The hierarchical control method for a single-stage water washing and desalination system according to claim 5, characterized in that: The step S73 further includes the following steps: S731, at the alkali metal salt concentration When the concentration of alkali metal salt is greater than the upper limit of the control concentration range of alkali metal salt, the alkali metal salt concentration is determined to be If the concentration is high, execute steps S732 to S733; S732, opening the second water inlet valve and increasing the valve opening of the second water inlet valve according to a preset step size; S733, wait for t time, assign k+m+t to k+m, and return to step S73; S734, at the alkali metal salt concentration When the concentration of the alkali metal salt is less than the lower limit of the control concentration range of the alkali metal salt, it is determined that the concentration of the alkali metal salt is less than the lower limit of the control concentration range of the alkali metal salt. If the concentration is low, execute steps S735 to S737; S735, opening the first liquid outlet valve to return the clear liquid in the clear liquid tank to the slurry tank, and continuing to add new water and dust removal ash to the slurry tank in proportion; wherein the flow rate of the first liquid outlet valve is controlled to be the same as the flow rate of the clear liquid generated by the solid-liquid separation device; S736: Wait for time t and re-obtain the filter cake alkali metal salt content at time k+m+t , and judge the alkali metal salt content of the filter cake Whether it is within the controlled content range of alkali metal salts; S737, alkali metal salt content in filter cake When the content of alkali metal salt is within the control range, it is determined that the alkali metal in the filter cake will not be enriched in the sintering raw materials, and the filter cake is continued to be sent to the sintering batching process to participate in sintering, and k+m+t is assigned to k+m, and the process returns to step S73.

7. The hierarchical control method for a single-stage water washing and desalination system according to claim 6, characterized in that: The step S736 further includes the following steps: Alkali metal salt content in filter cake When the content of the alkali metal salt is greater than the upper limit of the control range, the first liquid outlet valve is closed and the second liquid outlet valve is opened to allow the clear liquid in the clear liquid tank to enter the subsequent evaporation crystallization salt separation process.

8. A single-stage water washing and desalination system, characterized in that: The invention comprises a slurry tank, a solid-liquid separation device, a clear liquid tank and a control system, wherein the slurry tank comprises a slurry tank body, a first water inlet assembly for receiving external new water, an ash inlet assembly for receiving external dust ash, a liquid return assembly for receiving clear liquid returned from the clear liquid tank, and a slurry discharge assembly, wherein the first water inlet assembly is provided with a first water inlet valve, and the slurry discharge assembly is provided with a slurry discharge valve, water enters the slurry tank body through the first water inlet assembly, the dust ash enters the slurry tank body through the ash inlet assembly, and the water and the dust ash are mixed in the slurry tank body to form slurry; the solid-liquid separation device is used to receive the slurry from the slurry discharge assembly and produce a first clear liquid and a filter cake; The clear liquid tank includes a clear liquid tank body, a second water inlet assembly for receiving new water from the outside, a liquid inlet assembly for receiving the first clear liquid, a first liquid outlet assembly, and a second liquid outlet assembly, wherein the second water inlet assembly is provided with a second water inlet valve, the first liquid outlet assembly is provided with a first liquid outlet valve, and the second liquid outlet assembly is provided with a second liquid outlet valve. The first clear liquid enters the clear liquid tank body through the liquid inlet assembly, and the second clear liquid in the clear liquid tank body is transported to a subsequent evaporation and crystallization salt separation process through the second liquid outlet assembly, or the second clear liquid in the clear liquid tank body is transported to the slurry tank body through the first liquid outlet assembly and the liquid return assembly; The first water inlet valve, slurry outlet valve, second water inlet valve, first liquid outlet valve and second liquid outlet valve are all connected to the control system, and the control system includes a memory, a processor and a computer program stored in the memory and runnable on the processor. When the computer program is executed by the processor, the steps of the hierarchical control method of a single-stage water washing and desalination system as described in any one of claims 1 to 7 are implemented.

9. A storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the hierarchical control method for a single-stage water washing and desalination system according to any one of claims 1 to 7 are implemented.

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