Utilization method of galvanized wire desalted water and galvanized sheet production equipment

Abstract

The invention provides a galvanized wire desalted water utilization method and galvanized sheet production equipment. The utilization method comprises the following steps: introducing desalted water into a finishing machine for use, collecting generated finishing wastewater, and treating the finishing wastewater through a first precipitation ultrafiltration mechanism to obtain first treated desalted water; introducing the first treated desalted water into a withdrawal and straightening machine for use, collecting generated withdrawal and straightening wastewater, and treating the withdrawal and straightening wastewater through a second precipitation ultrafiltration mechanism to obtain second treated desalted water; introducing the second treated desalted water into a galvanizing line water quenching tank and a desalted water circulating tank for circulating flow, collecting part of generated water quenching wastewater, and treating the water quenching wastewater through a third precipitation ultrafiltration mechanism to obtain third treated desalted water; introducing the third treated desalted water into a cleaning section for use; the desalted water is subjected to cascade utilization, so that the use amount of the desalted water is reduced, the wastewater discharge is reduced, the treatment load, the treatment scale and the treatment cost of the oily wastewater are reduced, and the water production and supply pressure of the desalted water is relieved.

Description

Technical Field

[0001] The invention relates to the field of cold-rolled galvanizing line production, in particular to a method for utilizing desalted water in a galvanizing line and galvanized sheet production equipment. Background Art

[0002] Desalted water is used in the skinning section, straightening section, water quenching section and cleaning section of the cold-rolled galvanizing line. The cleaning section is divided into electrolytic degreasing section, alkaline scrubbing section and hot water rinsing section. Among them, the desalted water used in the skinning section and straightening section is directly discharged as wastewater, resulting in a large overall consumption of desalted water, a large amount of wastewater generated by the desalted water, and a great pressure on subsequent wastewater treatment. Summary of the invention

[0003] The main purpose of the present invention is to provide a method for utilizing desalted water in a galvanizing line and galvanized sheet production equipment to solve the technical problems of large desalted water consumption and large total amount of wastewater generated in the existing cold-rolled galvanizing line.

[0004] To achieve the above object, the present invention provides a method for utilizing desalted water in a galvanizing line, comprising the following steps:

[0005] The desalted water is passed into the polishing machine for use and the polishing wastewater generated is collected, and then the polishing wastewater is treated by a first precipitation ultrafiltration mechanism to obtain a first treated desalted water.

[0006] The first treated desalted water is passed into the straightening machine for use and the generated straightening wastewater is collected, and then the straightening wastewater is treated by a second precipitation ultrafiltration mechanism to obtain the second treated desalted water.

[0007] The second treated desalted water is passed into the galvanizing line water quenching tank and the desalted water circulation box for circulation, and part of the generated water quenching wastewater is collected. The water quenching wastewater is then treated by a third precipitation ultrafiltration mechanism to obtain a third treated desalted water.

[0008] The third treated desalted water is passed into the cleaning section for use.

[0009] Wherein, the filtration components of the first precipitation ultrafiltration mechanism, the second precipitation ultrafiltration mechanism and the third precipitation ultrafiltration mechanism include an inorganic ceramic membrane, and the filtration accuracy of the inorganic ceramic membrane is 50nm.

[0010] According to an embodiment of the present application, at least one of the following steps is also included:

[0011] A portion of the first treated desalted water is passed into the skin-finishing machine for recycling.

[0012] A portion of the second treated desalted water is passed into the tension and leveling machine for circulation.

[0013] Part of the third treated desalted water is passed into the galvanizing line water quenching tank and the desalted water circulation box for circulation.

[0014] According to the implementation manner of the present application, the finishing wastewater, the straightening wastewater and the water quenching wastewater are pressurized to 0.3-0.4 MPa and filtered through the filter components of the first sedimentation ultrafiltration mechanism, the second sedimentation ultrafiltration mechanism and the third sedimentation ultrafiltration mechanism respectively.

[0015] According to the implementation mode of the present application, it also includes collecting the steam condensed water generated by each hot air drying equipment in the galvanizing line, passing it into a third precipitation ultrafiltration mechanism for treatment, and obtaining steam condensed desalted water.

[0016] According to the implementation mode of the present application, the flow rate of the desalted water is 18 to 20 cubic meters per hour, the flow rate of the first treated desalted water is 16 to 18 cubic meters per hour, the flow rate of the second treated desalted water is 15 to 17 cubic meters per hour, and the flow rate of the third treated desalted water is 15 to 16 cubic meters per hour.

[0017] According to an embodiment of the present application, the first sedimentation ultrafiltration mechanism, the second sedimentation ultrafiltration mechanism and the third sedimentation ultrafiltration mechanism each include an inclined plate sedimentation tank, a filtration assembly, a clean water tank, a pickling tank, an alkali washing tank and a rinsing tank.

[0018] The inclined plate sedimentation tank is used to precipitate and stratify wastewater, and the filter assembly is connected to the inclined plate sedimentation tank; the clear water tank collects the filtrate of the filter assembly; the inclined plate sedimentation tank collects the residual liquid of the filter assembly; the acid washing tank, alkali washing tank and rinsing tank are respectively connected to the filter assembly to supply liquid to wash the filter assembly.

[0019] According to an embodiment of the present application, a step of cleaning the filter assembly is also included, and the cleaning step includes:

[0020] The filter components are switched, rinsed, alkaline washed, rinsed, acid washed, rinsed, and switched in sequence.

[0021] The mass fractions of the acid content and the alkali content of the cleaning solution corresponding to the alkaline cleaning and the acid cleaning are 1% to 2% respectively, and the water temperature of the cleaning solution is 50-60°C.

[0022] The water temperature of the rinsing is 30-40°C.

[0023] According to an embodiment of the present application, the step of passing the third treated desalted water into the cleaning section for use comprises:

[0024] A portion of the third treated desalted water is mixed with a degreasing agent and preheated in the annealing furnace before being electrolytically cleaned.

[0025] A portion of the third treated desalted water is mixed with a degreasing agent and preheated in the annealing furnace before being alkaline scrubbed.

[0026] Then, a portion of the third treated desalted water is preheated in the annealing furnace and then rinsed with hot water.

[0027] According to the implementation mode of the present application, it also includes:

[0028] The oily wastewater obtained by electrolytic cleaning and the alkaline wastewater obtained by alkaline brushing are sent to the cold rolling wastewater station for treatment.

[0029] The present application also provides a galvanized sheet production equipment, comprising a cleaning section, a drying equipment, a continuous annealing furnace, a zinc pot, a galvanizing line water quenching tank, a first hot air drying equipment, a skin pass machine, a straightening machine, a second hot air drying equipment, a passivation machine, a third hot air drying equipment and a desalted water supply equipment, which are arranged in sequence. The desalted water supply equipment operates according to the above-mentioned method for utilizing the desalted water of the galvanizing line.

[0030] In the above-mentioned method for utilizing desalted water in the galvanizing line, according to the requirements of the skin-smoothing section, straightening section, water quenching section and cleaning section for the cleanliness of desalted water, the used desalted water is processed to remove only the zinc powder and oil that have a greater impact on the subsequent sections, and then the supply sequence of desalted water and each treated desalted water is reasonably arranged. That is, the desalted water is utilized in cascade, which saves the use of desalted water and reduces wastewater discharge, reduces the load, scale and cost of oily wastewater treatment, and relieves the water production and supply pressure of desalted water. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0032] Figure 1 It is an application flow chart of a method for utilizing desalted water in a galvanizing line according to one embodiment of the present application.

[0033] Figure 2 It is a module schematic diagram of a precipitation ultrafiltration mechanism according to one embodiment of the present application;

[0034] Figure 3 It is a schematic diagram of the operation of the sedimentation ultrafiltration mechanism of one embodiment of the present application.

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot 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 the features.

[0039] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually 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.

[0040] In the prior art, the polishing section, straightening section, and water quenching section are all operated directly with desalted water, and the desalted water used in the polishing section and straightening section is directly discharged as wastewater. The amount of desalted water used in each stage is relatively large. For example, in some processes, the amount of desalted water used in the cleaning section is about 20 cubic meters per hour, and the amount of desalted water used in the water quenching tank section is 15-17 cubic meters per hour. The amount here is mainly adjusted according to the cooling capacity of the desalted water cooler; the amount of desalted water used in the polishing section and straightening section is 18-20 cubic meters per hour and 16-18 cubic meters per hour respectively.

[0041] This results in a large overall consumption of desalted water, and the total amount of wastewater generated by the desalted water is also large. However, after research, the applicant found that the water quality of the polishing wastewater and polishing wastewater after use in the polishing section and the straightening section is very good, as shown in Table 1. After simple treatment, it has the value of repeated use. For example, as long as the oil and zinc powder are filtered, the use requirements of the desalted water in the polishing section and the straightening section can be met. The following table shows the water quality of the desalted water after the water quenching section and the polishing and straightening section are used up.

[0042] Table 1 The quality of desalted water after the prior art water quenching section and the skin straightening and straightening section are used up

[0043] Detection indicators Water quenching tank wastewater Wastewater from skin-finishing and leveling machines Suspended matter (mg / L) 23 13 pH 7.70 7.98 Conductivity (μs / cm) 3.74 4.01 Total hardness (mg / L) none none Calcium hardness (mg / L) 0.017 0.014 Chloride ion (mg / L) 1.14 1.83 Sulfate(mg / L) none none Soluble SiO2(mg / L) none none Total Iron (mg / L) none none Total oil (mg / L) 0.27 0.79 Zinc (mg / L) none none Anionic surfactant (mg / L) 0.007 0.003

[0044] If it is directly discharged and sent to the wastewater treatment station in the form of wastewater, not only will the total amount of wastewater be large, but the treatment cost will also be high. The specific reasons are as follows: there are many types of wastewater treated in the wastewater station. In order to ensure that the treated wastewater meets the discharge standards, multiple types of treatment methods are required. In fact, polishing wastewater and polishing wastewater do not need this type of treatment, which increases the treatment cost.

[0045] In addition, the zinc powder in the wastewater is not collected in this way, but enters the wastewater treatment station in the form of wastewater, resulting in high zinc content and even lead ions in the wastewater discharged from the wastewater station. The collection of zinc powder can realize the recycling of zinc resources.

[0046] In addition to the high cost of post-processing, the actual production cost of using large amounts of desalinated water is also high. In some ways, the process of producing water from desalinated water includes:

[0047] The source water first passes through the inclined plate filter to settle the sediment, then is pressurized by a water pump into a multi-media filter (containing quartz sand and activated carbon) for initial filtration, and then is pressurized by a water pump precision filter (with PP cotton material vertical pipe filter element with a filtration accuracy of 5μm) for initial filtration, and then is pressurized to 1MPa by a water pump into the reverse osmosis device, and then passes through the cation bed, anion bed, and mixed bed of the ion exchange, and then uses the height difference to filter the ion exchange resin through the resin collector before entering the product water pool. The water production process has high energy consumption, multiple water production processes, and many bottlenecks in the water production process, resulting in limited water production capacity.

[0048] The water produced by the desalted water station near the cold rolling mill has always been a bottleneck resource, which is specifically reflected in the following aspects: 1) There are many users: in addition to the cold rolling acid rolling line, pickling line, single frame, three galvanizing lines, and cover flat units, the desalted water also includes three sets of units in the power generation workshop and the coking dry quenching workshop; 2) The influence of seasonal changes: In addition, the desalted water production capacity is affected by seasonal changes (affected by the thermal expansion and contraction of the reverse osmosis membrane); 3) The water production capacity is limited: on the one hand, the water production process is complicated (such as primary and fine filtration, reverse osmosis, cation bed, anion bed, mixed bed, etc.); on the other hand, the water production process has high energy consumption, such as increasing the water pressure to 1MPa to enter the reverse osmosis device; on the third hand, the design capacity is limited; on the fourth hand, the investment in adding desalted water production capacity is large.

[0049] Based on this, the present invention provides a method for utilizing desalted water in a galvanizing line, see Figure 1 , including the following steps:

[0050] S100: passing desalted water into a polishing machine for use and collecting the polishing wastewater generated, and then treating the polishing wastewater through a first precipitation ultrafiltration mechanism to obtain a first treated desalted water.

[0051] The amount of desalted water used in the polishing section is large (18-20 cubic meters per hour), and desalted water must be used because the conductivity of desalted water is extremely low and the salt content is small, and the surface of the galvanized strip will not scale after drying. In addition, the desalted water used by the polishing machine needs to be pressurized to nearly 10MPa for use, and the nozzle is small and cannot be blocked. The water quality of the desalted water is required to be high here. And polishing requires the use of working rollers to press the galvanized strip and the desalted water also plays a lubricating role during the pressing process, so the cleanliness of the water is higher, otherwise it may leave marks on the galvanized strip, such as pits. Therefore, in this application, desalted water is selected for the polishing section, rather than the desalted water after treatment of desalination wastewater.

[0052] Four rows of desalted water nozzles at the skin-pass mill entrance spray the upper support roller, upper working roller, lower working roller and lower support roller of the skin-pass mill at the same time. Its functions include: 1) lubricating the galvanized strip and rollers; 2) removing the zinc powder adhering to the rollers. The skin-pass mill outlet uses high-pressure water spray, that is, desalted water is sprayed between the support roller and the working roller in two rows with small flow and high pressure. Its main function is to remove the zinc powder adhering to the rollers.

[0053] Polishing wastewater is usually collected in the corresponding pit on site, and then enters the first sedimentation ultrafiltration mechanism for treatment. Referring to the above analysis, the water quality of polishing wastewater is relatively high. Therefore, in comparison, the first sedimentation ultrafiltration mechanism is used to remove oil and zinc powder from polishing wastewater. For example, it is only necessary to pressurize the polishing wastewater with low conductivity to 0.3-0.4MPa through a water pump and pass it through the filter component of the first sedimentation ultrafiltration mechanism to obtain low conductivity, low oil content and low zinc powder content, which can meet the water demand of the straightening machine. The filter component includes an inorganic ceramic membrane, and the filtration accuracy of the inorganic ceramic membrane is 50nm.

[0054] Inorganic ceramic membranes have excellent ability to remove oil and zinc powder. In addition, ceramic membranes are less likely to be contaminated, have strong continuous operation capabilities, and have large membrane flux and are not easy to attenuate.

[0055] S200: passing the first treated desalted water into the straightening machine for use and collecting the generated straightening wastewater, and then treating the straightening wastewater through a second sedimentation ultrafiltration mechanism to obtain a second treated desalted water.

[0056] The water consumption of the straightening machine is similar to that of the skin-passing machine, which is 16 to 18 cubic meters per hour. It also needs to be pressurized and passed into the nozzle for use, so the water quality requirements are relatively high, slightly lower than that of the skin-passing machine.

[0057] The collection of straightening wastewater and its treatment process through the second sedimentation ultrafiltration mechanism are similar to the collection and treatment process of finishing wastewater, and will not be repeated here.

[0058] S300: The second treated desalted water is passed through the galvanizing line water quenching tank and the desalted water circulation box for circulation, part of the generated water quenching wastewater is collected, and the water quenching wastewater is then treated by a third precipitation ultrafiltration mechanism to obtain a third treated desalted water.

[0059] The water consumption of the galvanizing line water quenching tank is large (the consumption is 15-17 cubic meters per hour, and the consumption here is mainly based on the cooling capacity of the desalted water cooler). The second-treated desalted water circulates in the galvanizing line water quenching tank and the desalted water circulation tank. Among them, the second-treated desalted water in the galvanizing line water quenching tank continuously contacts and cools the galvanized sheet. During the cooling process, the zinc powder on the surface of the galvanized sheet continuously enters the second-treated desalted water, and the water temperature of the second-treated desalted water also continues to rise and then is cooled in the desalted water circulation tank. In the specific process, heat exchange occurs with the external circulating water to reduce part of the temperature.

[0060] The collection of water quenching wastewater and the treatment process of the third precipitation ultrafiltration mechanism are similar to the collection and treatment process of finishing wastewater, which will not be repeated. The filtration components of the first precipitation ultrafiltration mechanism, the second precipitation ultrafiltration mechanism and the third precipitation ultrafiltration mechanism include an inorganic ceramic membrane, and the filtration accuracy of the inorganic ceramic membrane is 50nm.

[0061] S400: passing the third treated desalted water into the cleaning section for use. Wherein, the filtration components of the first precipitation ultrafiltration mechanism, the second precipitation ultrafiltration mechanism and the third precipitation ultrafiltration mechanism include an inorganic ceramic membrane, and the filtration accuracy of the inorganic ceramic membrane is 50nm.

[0062] The amount of water used in the cleaning section is relatively large (about 20 cubic meters per hour). The cleaning section is divided into the electrolytic degreasing section, the alkaline scrubbing section and the hot water rinsing section. The electrolytic degreasing section: removes the oil stains adhering to the surface of the strip by electrolysis; the alkaline scrubbing section: removes the degreasing substances brought by degreasing. The function of degreasing is to degrease the surface of the strip and remove iron powder, dust and other debris on the surface of the strip. In the alkaline scrubbing section, the surface of the strip is first cleaned by spraying and scrubbing, further cleaning impurities and oil stains, and rinsing off the alkaline solution on the surface of the strip. The hot water rinsing section, that is, the three-level rinsing section behind, uses a spray method to clean the alkaline solution and impurities remaining on the surface of the strip to ensure a good cleaning effect.

[0063] In the technical solution of the present application, the zinc powder and oil content in the desalted water after use in the skinning, straightening, and water quenching sections of the galvanizing line are filtered out by a precipitation ultrafiltration mechanism and reused in the skinning, straightening, water quenching, and cleaning sections of the galvanizing line. This solves the problem of tight supply of desalted water and realizes the recycling of this bottleneck resource. In addition, it reduces the amount of oily wastewater, reduces the load of oily wastewater treatment in the wastewater station (because the oily wastewater is biochemically treated in the middle stage, the biochemical treatment load is reduced, the wastewater treatment time in the biochemical process is increased, and it is easy to meet the discharge standards after treatment), and reduces the treatment cost of oily wastewater.

[0064] It meets the requirements of the national overall trend of energy conservation and emission reduction. The desalted water used in the skin-smoothing and straightening sections was not reused due to one-time use, which caused the water supply of the desalted water station to be tight, and the desalted water used by the cold rolling units was also tight, making it difficult to communicate and coordinate a series of production; in addition, due to the large load of oily wastewater treatment in the wastewater station, the effluent water quality often exceeded the standard. Through the actual use of this technology, the relevant problems have been solved.

[0065] The existing technology uses 30-40 cubic meters of desalted water per hour for a galvanizing line, while in the technical solution of this application, the desalted water consumption is 15-20 cubic meters per hour. The desalted water consumption of only one galvanizing line is reduced from 30-40 cubic meters per hour to 15-20 cubic meters per hour, while a cold rolling mill has two or even four galvanizing lines. This application realizes the self-circulation and cascade utilization of desalted water, comprehensively considers the water-saving situation of the whole line of desalted water, greatly reduces the consumption of desalted water per ton of galvanized steel, and also saves the water production cost of the desalted water station and the investment in the expansion of the water production capacity of the desalted water station (large investment) is greatly saved.

[0066] In the above-mentioned method for utilizing desalted water in the galvanizing line, according to the requirements of the skin-smoothing section, straightening section, water quenching section and cleaning section for the cleanliness of desalted water, the used desalted water is processed to remove only the zinc powder and oil that have a greater impact on the subsequent sections, and then the supply sequence of desalted water and each treated desalted water is reasonably arranged. That is, the desalted water is utilized in cascade, which saves the use of desalted water and reduces wastewater discharge, reduces the load, scale and cost of oily wastewater treatment, and relieves the water production and supply pressure of desalted water.

[0067] In some embodiments, see Figure 1 , further comprising at least one of the following steps:

[0068] A portion of the first treated desalted water is passed into the skin-finishing machine for recycling.

[0069] A portion of the second treated desalted water is passed into the tension and leveling machine for circulation.

[0070] Part of the third treated desalted water is passed into the galvanizing line water quenching tank and the desalted water circulation box for circulation.

[0071] In addition to being used in the next process for cascade, the first treated desalted water, the second treated desalted water and the third treated desalted water can all be self-circulated according to the water consumption requirements of the corresponding use stage to achieve water balance. For example, when the water consumption of the tension and leveling machine decreases and the water consumption of the skin-passing machine increases, part of the first treated desalted water can be passed into the skin-passing machine for circulation.

[0072] In some embodiments, see Figure 1The polishing wastewater, the straightening wastewater and the water quenching wastewater are pressurized to 0.3-0.4MPa and filtered through the filter components of the first precipitation ultrafiltration mechanism, the second precipitation ultrafiltration mechanism and the third precipitation ultrafiltration mechanism respectively. This method has high filtration efficiency and high filtration quality.

[0073] In some embodiments, the method further includes collecting steam condensed water generated by each hot air drying device in the galvanizing line, passing the water into a third precipitation ultrafiltration mechanism for treatment, and obtaining steam condensed desalted water.

[0074] For example, the steam condensate produced by the hot air dryer on the top of the water quenching tank, the hot air dryer after skin-passing and straightening, and the hot air dryer after passivation is collected. The temperature of the steam condensate is relatively high, so it will carry some iron ions and some iron filings when flowing in the pipeline. In addition, its composition is close to desalted water. Therefore, the presence of iron ions and some iron filings makes it unsuitable for skin-passing or straightening. For example, iron filings cause pits on the surface of the strip after skin-passing, and iron ions cause the surface of the strip after straightening to turn yellow due to iron ion oxidation.

[0075] The steam condensate is passed into the third precipitation ultrafiltration mechanism for treatment, which increases the total amount of desalted water in the third treatment and is beneficial to balancing the water consumption of the cleaning section, because the water consumption of the cleaning section is relatively large.

[0076] The water volume of desalted water decays by 10-15% for each cycle (desalted water or treated desalted water treated by precipitation ultrafiltration mechanism after use is regarded as one cycle). The flow rate of the third treated desalted water is about 15 cubic meters per hour, and with the supplement of steam condensed water, it can basically meet the water demand of about 20 cubic meters per hour of the cleaning section. It can be said that the steam condensed desalted water is both a water supplement for the third treated desalted water and a heat supplement for the third treated desalted water.

[0077] In some embodiments, the flow rate of the desalted water is 18 to 20 cubic meters per hour, the flow rate of the first treated desalted water is 15 to 18 cubic meters per hour, the flow rate of the second treated desalted water is 15 to 17 cubic meters per hour, and the flow rate of the third treated desalted water is 15 to 16 cubic meters per hour.

[0078] In some embodiments, see Figure 2 and Figure 3 The first precipitation ultrafiltration mechanism, the second precipitation ultrafiltration mechanism and the third precipitation ultrafiltration mechanism each include an inclined plate sedimentation tank, a filter assembly, a clean water tank, an acid washing tank, an alkali washing tank and a rinsing tank;

[0079] The inclined plate sedimentation tank is used to precipitate and stratify wastewater, and the filter assembly is connected to the inclined plate sedimentation tank; the clear water tank collects the filtrate of the filter assembly; the inclined plate sedimentation tank collects the residual liquid of the filter assembly; the acid washing tank, alkali washing tank and rinsing tank are respectively connected to the filter assembly to supply liquid to wash the filter assembly.

[0080] Desalted water after skin-finishing, straightening and water quenching can be respectively put into the corresponding collection tanks, and then pumped into the inclined plate sedimentation tank by the lifting pump for stratification. The oil stains on the roller surface of the skin-finishing machine and the straightening machine and the oil stains on the bearings are in the form of floating oil in the water. After the inclined plate sedimentation tank controls the liquid level to allow it to overflow, the floating oil can flow into the collection tank beside the oil machine and then into the oil-containing wastewater treatment system of the wastewater station. Zinc powder and ash are collected by natural sedimentation for slag discharge, and the middle clear liquid is pumped into the filter assembly by the liquid supply pump for circulation filtration. The feed liquid is filtered by the cross-flow of the inorganic ceramic membrane of the filter assembly, and part of it forms the filtered liquid and flows into the clear water tank by gravity, and the other part flows back to the inclined plate sedimentation tank through the return pipeline. The middle clear liquid circulates continuously, and the filtered permeate is continuously produced to achieve the separation effect. The clear liquid in the clear water tank is pumped into each user point.

[0081] Take polishing wastewater as an example. After being collected, polishing wastewater enters the inclined plate sedimentation tank, where it is precipitated and layered. The upper layer is oily substances, the middle layer is water to be filtered, and the bottom layer is zinc powder. The oily substances and zinc powder are separated and collected separately. The water to be filtered is pressurized and passed into the filter assembly for filtration. The filter assembly includes an inorganic ceramic membrane. The filtrate is the first treated desalted water, and the filtrate of the filter assembly is returned to the inclined plate sedimentation tank for re-precipitation and layering.

[0082] The filter components need to be cleaned after a certain period of use, so acid cleaning tanks, alkali cleaning tanks, and rinsing tanks are needed. The acid cleaning tanks, alkali cleaning tanks, and rinsing tanks store part of the clear liquid for preparing the alkali solution, acid solution, and rinsing liquid for cleaning the membrane tubes.

[0083] In some embodiments, see Figure 2 and Figure 3 , further comprising the step of cleaning the filter assembly, the cleaning step comprising:

[0084] The filter assembly is switched, rinsed, alkaline washed, rinsed, acid washed, rinsed, switched in sequence. The mass fractions of the acid content and the alkali content of the cleaning liquid corresponding to the alkaline washing and acid washing are 1% to 2% respectively. The water temperature of the cleaning liquid is 50-60°C. The water temperature of the rinsing is 30-40°C.

[0085] After a certain period of operation, the membrane needs to be cleaned to restore the permeation flux. The cleaning of ceramic membrane filtration devices generally includes switching, rinsing, alkaline washing, acid washing and other steps. The acid and alkali content of the acid and alkali cleaning solution is generally controlled at about 1%-2% by mass. The general steps of cleaning are switching, rinsing, alkaline washing, rinsing, acid washing, rinsing, switching.

[0086] Among them, switching is the switching between the normal membrane filtration state and the membrane cleaning state. For example, when cleaning, switching is the process of switching from the normal working state to the membrane cleaning state. It includes that the waste desalted water does not enter the membrane tube, but the corresponding rinsing liquid (the rinsing liquid can be clean desalted water) enters the membrane tube to clean the membrane tube. Switching is the process of switching from the normal working state to the membrane cleaning state. Rinsing is an intermediate process from one washing to another washing. Its purpose is to prevent mutual contamination, such as acid washing after alkaline washing; such as after acid washing, when the membrane is about to enter the normal working state; rinsing must be performed.

[0087] The water temperature for chemical cleaning is generally controlled at 50-60℃, and the switching water temperature is controlled at 30-40℃. The cleaning time is about 2.0 to 4.0 hours. If the flux is not restored, chemical cleaning and rinsing can be performed again.

[0088] In some embodiments, see Figure 3 The step of passing the third treated desalted water into the cleaning section for use comprises:

[0089] A portion of the third treated desalted water is mixed with a degreasing agent and preheated in the annealing furnace before being electrolytically cleaned.

[0090] A portion of the third treated desalted water is mixed with a degreasing agent and preheated in the annealing furnace before being alkaline scrubbed.

[0091] Then, a portion of the third treated desalted water is preheated in the annealing furnace and then rinsed with hot water.

[0092] In some embodiments, it also includes:

[0093] The oily wastewater obtained by electrolytic cleaning and the alkaline wastewater obtained by alkaline brushing are sent to the cold rolling wastewater station for treatment.

[0094] The present application also provides a galvanized sheet production equipment, comprising a cleaning section, a drying equipment, a continuous annealing furnace, a zinc pot, a galvanizing line water quenching tank, a first hot air drying equipment, a skin pass machine, a straightening machine, a second hot air drying equipment, a passivation machine, a third hot air drying equipment and a desalted water supply equipment, which are arranged in sequence. The desalted water supply equipment operates according to the above-mentioned method for utilizing the desalted water of the galvanizing line.

[0095] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for utilizing desalted water in a galvanizing line, characterized in that: The following steps are involved: Passing desalted water into a polishing machine for use and collecting the polishing wastewater generated, and then treating the polishing wastewater through a first precipitation ultrafiltration mechanism to obtain a first treated desalted water; The first treated desalted water is passed into the straightening machine for use and the straightening wastewater generated is collected, and the straightening wastewater is then treated by a second precipitation ultrafiltration mechanism to obtain a second treated desalted water; The second treated desalted water is passed into the galvanizing line water quenching tank and the desalted water circulation box for circulation, part of the generated water quenching wastewater is collected, and the water quenching wastewater is then treated by the third precipitation ultrafiltration mechanism to obtain the third treated desalted water; Passing the third treated desalted water into the cleaning section for use; Wherein, the filtration components of the first precipitation ultrafiltration mechanism, the second precipitation ultrafiltration mechanism and the third precipitation ultrafiltration mechanism include an inorganic ceramic membrane, and the filtration accuracy of the inorganic ceramic membrane is 50nm.

2. The method for utilizing desalted water in a galvanizing line according to claim 1, characterized in that: Also includes at least one of the following steps: Passing part of the first treated desalted water into the skin-finishing machine for recycling; Passing part of the second treated desalted water into the tension and leveling machine for recycling; Part of the third treated desalted water is passed into the galvanizing line water quenching tank and the desalted water circulation box for circulation.

3. The method for utilizing desalted water in a galvanizing line according to claim 1, characterized in that: The finishing wastewater, the straightening wastewater and the water quenching wastewater are pressurized to 0.3-0.4 MPa and filtered through the filter components of the first precipitation ultrafiltration mechanism, the second precipitation ultrafiltration mechanism and the third precipitation ultrafiltration mechanism respectively.

4. The method for utilizing desalted water in a galvanizing line according to claim 1, characterized in that: It also includes collecting steam condensed water generated by each hot air drying equipment in the galvanizing line, passing it into a third precipitation ultrafiltration mechanism for treatment, and obtaining steam condensed desalted water.

5. The method for utilizing desalted water in a galvanizing line according to claim 1, characterized in that: The flow rate of the desalted water is 18 to 20 cubic meters per hour, the flow rate of the first treated desalted water is 16 to 18 cubic meters per hour, the flow rate of the second treated desalted water is 15 to 17 cubic meters per hour, and the flow rate of the third treated desalted water is 15 to 16 cubic meters per hour.

6. The method for utilizing desalted water in a galvanizing line according to claim 1, characterized in that: The first precipitation ultrafiltration mechanism, the second precipitation ultrafiltration mechanism and the third precipitation ultrafiltration mechanism each include an inclined plate sedimentation tank, a filter assembly, a clean water tank, an acid washing tank, an alkali washing tank and a rinsing tank; The inclined plate sedimentation tank is used to precipitate and stratify wastewater, and the filter assembly is connected to the inclined plate sedimentation tank; the clear water tank collects the filtrate of the filter assembly; the inclined plate sedimentation tank collects the residual liquid of the filter assembly; the acid washing tank, alkali washing tank and rinsing tank are respectively connected to the filter assembly to supply liquid to wash the filter assembly.

7. The method for utilizing desalted water in a galvanizing line according to claim 6, characterized in that: The filter assembly is further comprised of a step of cleaning the filter assembly, wherein the cleaning step comprises: The filter components are switched, rinsed, alkaline washed, rinsed, acid washed, rinsed, and switched in sequence; The mass fractions of the acid content and the alkali content of the cleaning solution corresponding to the alkaline cleaning and the acid cleaning are 1% to 2% respectively; and the water temperature of the cleaning solution is 50-60°C; The water temperature of the rinsing is 30-40°C.

8. The method for utilizing desalted water in a galvanizing line according to claim 1, characterized in that: The step of passing the third treated desalted water into the cleaning section for use comprises: Mixing a portion of the third treated desalted water with a degreasing agent and preheating the mixture in an annealing furnace and then performing electrolytic cleaning; Then, a part of the third treated desalted water is mixed with a degreasing agent and preheated in the annealing furnace, and then alkali scrubbing is performed; Then, a portion of the third treated desalted water is preheated in the annealing furnace and then rinsed with hot water.

9. The method for utilizing desalted water in a galvanizing line according to claim 8, characterized in that: Also includes: The oily wastewater obtained by electrolytic cleaning and the alkaline wastewater obtained by alkaline brushing are sent to the cold rolling wastewater station for treatment.

10. A galvanized sheet production equipment, characterized in that: The method comprises a cleaning section, a drying device, a continuous annealing furnace, a zinc pot, a galvanizing line water quenching tank, a first hot air drying device, a skin pass machine, a straightening machine, a second hot air drying device, a passivation machine, a third hot air drying device and a desalted water supply device which are arranged in sequence. The desalted water supply device operates according to the method for utilizing desalted water of a galvanizing line according to any one of claims 1 to 9.

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