Cleaning device for fiber powder for powder-coated filter and elution characteristic evaluation method

Abstract

According to the cleaning device for the fiber powder for the powder covering filter and the dissolution characteristic evaluation method, leaching in a constant-temperature environment is achieved through cooperation of the double-layer pipe and temperature-control leaching, fiber powder is intercepted in combination with a sand core, impurities are efficiently separated and dissolved out, a three-stage dynamic leaching strategy is adopted, gradient time design is adopted, and the dissolution characteristic of the fiber powder is evaluated. According to the method, the dissolution behavior of the fiber powder in the whole life cycle is covered, the accumulated dissolved matter mass is calculated by utilizing integration, the dissolution characteristic of the fiber powder for the powder covering filter is accurately evaluated, the safety of the powder covering filter after being put into operation is improved, the possibility of equipment corrosion is reduced, and the water quality is improved.

Description

Technical Field

[0001] The present invention relates to the field of condensate polishing, and particularly to a cleaning device for fiber powder used in a powder-coated filter and a method for evaluating the dissolution characteristics thereof. Background Art

[0002] In a condensate polishing system, a powder-coated filter is an important type of condensate treatment equipment, and its filter media mainly include powder resin and fiber powder. Among them, the fiber powder mainly plays a role in increasing the flocculation volume and porosity of the filter media to enhance the filtration characteristics.

[0003] Fiber powder is chemically regarded as inert. However, during the manufacturing process from wood pulp, various impurities introduced by the manufacturing process and contained in the raw materials themselves will remain in the fiber powder. These impurities will enter the water-vapor system in the form of dissolved substances after the powder-coated filter is put into operation, which may affect the water quality and corrode the equipment.

[0004] Therefore, accurately evaluating the dissolution characteristics of fiber powder is an important way to screen filter media, estimate the operation cycle, and improve water quality for a system using a powder-coated filter. Summary of the Invention

[0005] In a first aspect of the present disclosure, there is provided a cleaning device for fiber powder used in a powder-coated filter, including:

[0006] A rinsing module, including a beaker (1), a constant flow pump (2), the inner tube of a double-layer tube (3), a sand core (4), and a sample collection tube (5) connected in sequence. The beaker (1) is filled with ultrapure water, which flows into the inner tube through the constant flow pump (2) to rinse the fiber powder installed in the inner tube, and the rinsing liquid after rinsing flows into the sample collection tube (5);

[0007] A heat preservation module, including a water bath (6), a constant flow pump (7), and the outer tube of the double-layer tube (3) connected in sequence. The water bath (6) is filled with constant-temperature water, which flows into the outer tube through the constant flow pump (7) for heat preservation and then flows back to the water bath after flowing out of the outer tube.

[0008] In combination with the first aspect, the circulating water temperature of the outer tube of the double-layer tube (3) is kept constant at 50 ± 1 °C.

[0009] In combination with the first aspect, the flow rate of the constant flow pump (2) is 5 ± 0.5 mL / min, and the flow rate of the constant flow pump (7) is 10 ± 1 mL / min.

[0010] In combination with the first aspect, the pore diameter of the sand core (4) is less than or equal to 0.45 μm and is used to intercept the fiber powder.

[0011] In a second aspect of the present disclosure, there is provided a method for evaluating the dissolution characteristics of fiber powder used in a powder-coated filter, using the above device, including:

[0012] Take the fiber powder sample to be tested and place it in the inner tube of the double-layer tube (3);

[0013] Inject ultrapure water in the beaker (1) into the inner tube through the constant flow pump (2) to wash the fiber powder in the inner tube in three stages. The washing liquid after washing flows into the sample collection tube (5), where,

[0014] In the first stage, washing is carried out every first preset time, in the second stage, washing is carried out every second preset time, and in the third stage, washing is carried out every third preset time.

[0015] The first preset time is less than the second preset time, the second preset time is less than the third preset time, and the durations of the first stage, the second stage, and the third stage increase in sequence;

[0016] Measure the conductivity of the washing liquid, and take the washing time as the abscissa and the conductivity of the washing liquid as the ordinate to plot the relationship curve of the conductivity changing with the washing time;

[0017] Fit the relationship curve to obtain the dissolution rate of the fiber powder, and evaluate the dissolution characteristics of the fiber powder according to the dissolution rate.

[0018] Combined with the second aspect, the fitting of the relationship curve to obtain the dissolution rate of the fiber powder is through the following formula:

[0019] y = A * exp(-B * x) + y0,

[0020] where y is the conductivity, the sum of A and y0 is the initial dissolution value, B is the dissolution rate, and x is the washing time.

[0021] Combined with the second aspect, the judgment criteria for the dissolution characteristics include: if the sum of A and y0 is less than 50 and B < 0.25, ∫ydx < 200, then the fiber powder meets the requirements.

[0022] Combined with the second aspect, the total duration of the three-stage washing is not less than 120 min, the proportion of the first stage ≤ 20%, and the proportion of the third stage ≥ 50%.

[0023] Combined with the second aspect, the method further includes synchronously measuring the content index of the dissolved substances in the washing liquid when measuring the conductivity of the washing liquid.

[0024] Combined with the second aspect, the content index of the dissolved substances is measured by integrating y = A * exp(-B * x) + y0.

[0025] Beneficial effects: A cleaning device and a dissolution characteristic evaluation method for fiber powder used in a powder-covered filter provided by the present disclosure achieve rinsing under a constant temperature environment through the coordinated temperature control rinsing of a double-layer tube. The fiber powder is intercepted by a sand core and the dissolved impurities are efficiently separated. A three-stage dynamic rinsing strategy is adopted, with a gradient time design to cover the dissolution behavior of the fiber powder throughout its life cycle. The cumulative mass of the dissolved substances is calculated by integration to accurately evaluate the dissolution characteristics of the fiber powder used in the powder-covered filter, improving the safety after the powder-covered filter is put into operation, reducing the possibility of corroding equipment, and improving the water quality. Brief Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of a cleaning device for fiber powder used in a powder-covered filter according to an embodiment of the present disclosure;

[0027] Figure 2 It is a schematic flow diagram of a method for evaluating the characteristics of fiber powder used in a powder-covered filter according to an embodiment of the present disclosure.

[0028] Figure 3 It is a relationship curve of the conductivity changing with the rinsing time according to an embodiment of the present disclosure. Detailed Embodiments

[0029] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present disclosure.

[0030] The terms used in the embodiments of the present disclosure are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present disclosure. The singular forms of "a", "the", and "said" used in the embodiments of the present disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0031] It should be understood that although the terms first, second, third, etc. may be used in the embodiments of the present disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the embodiments of the present disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining".

[0032] Such as Figure 1As shown in the figure, it is a schematic structural diagram of a cleaning device for fiber powder used in a powder-covered filter according to an embodiment of the present disclosure, including:

[0033] The rinsing module includes a beaker (1), a constant flow pump (2), the inner tube of a double-layer tube (3), a sand core (4), and a sample collection tube (5) connected in sequence. Ultra-pure water is contained in the beaker (1) and flows into the inner tube through the constant flow pump (2) to rinse the fiber powder installed in the inner tube. The rinsing liquid after rinsing flows into the sample collection tube (5);

[0034] The heat preservation module includes a water bath (6), a constant flow pump (7), and the outer tube of the double-layer tube (3) connected in sequence. Constant-temperature water is contained in the water bath (6) and flows into the outer tube through the constant flow pump (7) for heat preservation, and then flows back to the water bath after flowing out of the outer tube.

[0035] Beneficial effects: The outer tube circulates constant-temperature water combined with the linkage of two constant flow pumps, completely eliminating the interference of temperature on the dissolution behavior and meeting the control requirements of the high-purity water system for background pollution.

[0036] The microporous retention characteristics of the sand core cooperate with the ultra-pure water rinsing to accurately separate the fiber powder and the dissolved impurities, providing a reliable sample for the subsequent evaluation of the dissolution characteristics.

[0037] Furthermore, the circulating water temperature of the outer tube of the double-layer tube (3) is constant at 50 ± 1°C.

[0038] Beneficial effects: The temperature fluctuation is controlled within ±1°C, avoiding abnormal dissolution rates of fiber powder caused by temperature changes (such as high temperature accelerating ion dissolution and low temperature inhibiting diffusion), and ensuring the comparability of dissolution experiment data;

[0039] 50°C is close to the temperature of condensate water treatment in power plants, making the test results more suitable for engineering application scenarios;

[0040] The constant-temperature environment inhibits the drift of the conductivity of ultra-pure water (such as when the temperature increases by 1°C, the conductivity increases by about 2%), ensuring the detection accuracy of the conductivity of the rinsing liquid.

[0041] Furthermore, the flow rate of the constant flow pump (2) is 5 ± 0.5 mL / min, and the flow rate of the constant flow pump (7) is 10 ± 1 mL / min.

[0042] Beneficial effects: Rinsing at a low speed (5 mL / min) prolongs the water-powder contact time, avoiding the residue of dissolved substances caused by short flow (such as incomplete retention of iron ions), and improving the impurity removal rate;

[0043] High-speed heat preservation circulation (10 mL / min) enhances the convective heat transfer between the double-layer tube walls, offsetting the heat dissipation of the environment and ensuring that the temperature gradient of the fiber powder layer ≤ ±0.5°C;

[0044] Precision of ±0.5 mL / min (error ≤ 10%) to avoid deviation of dissolution rate caused by flow rate fluctuation.

[0045] Further, the pore diameter of the sand core (4) is less than or equal to 0.45 μm, which is used to intercept fiber powder.

[0046] Beneficial effects: Pore diameter ≤ 0.45 μm can completely block the typical fiber powder particle size (>1 μm), preventing sample loss from affecting the integral calculation of the total dissolution amount;

[0047] The microporous structure balances interception and air permeability, ensuring stable flow resistance of the eluent and maintaining the set flow rate of the constant flow pump.

[0048] As Figure 2 shown, it is a schematic flow chart of a method for evaluating the characteristics of fiber powder for a powder covering filter according to an embodiment of the present disclosure, including:

[0049] S201: Take a fiber powder sample to be tested and place it in the inner tube of the double-layer tube (3);

[0050] S202: Inject ultrapure water in the beaker (1) into the inner tube through the constant flow pump (2), and wash the fiber powder in the inner tube in three stages. The eluent after washing flows into the sample collection tube (5), where

[0051] In the first stage, washing is carried out every first preset time, in the second stage, washing is carried out every second preset time, and in the third stage, washing is carried out every third preset time,

[0052] The first preset time is less than the second preset time, the second preset time is less than the third preset time, and the durations of the first stage, the second stage, and the third stage increase in sequence;

[0053] S203: Measure the conductivity of the eluent, and draw a relationship curve of the change of the conductivity with the washing time with the washing time as the abscissa and the conductivity of the eluent as the ordinate;

[0054] S204: Fit the relationship curve to obtain the dissolution rate of the fiber powder, and evaluate the dissolution characteristics of the fiber powder according to the dissolution rate.

[0055] Exemplarily, take 3 g of the fiber powder sample to be tested and place it in a 220 mL double-layer tube, and start cleaning.

[0056] After starting, within the first 20 min (the first stage), the effluent is collected every 5 min (the first preset time).

[0057] After 20 min (the second stage), the effluent is collected once every 10 min (the second preset time).

[0058] After 1 h (the third stage), the effluent is collected every 20 min (the third preset time).

[0059] Stop collecting until the total elution time reaches 2 h.

[0060] Measure the conductivity of the collected effluent, as shown in Table 1.

[0061] Table 1 Conductivity of the effluent

[0062]

[0063]

[0064] Taking the elution time as the abscissa and the conductivity of the eluent as the ordinate, plot the relationship curve of the conductivity changing with the elution time (as Figure 3 ).

[0065] Fit the relationship curve through the following formula Figure 3 in the relationship curve:

[0066] y = A * exp(-B * x) + y0,

[0067] where y is the conductivity, the sum of A and y0 is the initial dissolution value, B is the dissolution rate, and x is the elution time.

[0068] Obtain: y = 9.53exp(-0.22x) + 1.37, and its dissolution rate is 0.22, proving that its dissolution rate is not high and the fiber powder meets the requirements.

[0069] Furthermore, fitting the relationship curve, the dissolution rate of the fiber powder is obtained through the following formula:

[0070] y = A * exp(-B * x) + y0,

[0071] where y is the conductivity, A is the initial dissolution value, B is the dissolution rate, x is the elution time, and y0 is the fixed conductivity.

[0072] Beneficial effects: The stripping efficiency of pollutants (such as iron ions and organic degradants) from the surface of the fiber powder is directly reflected by the dissolution rate constant. A lower B value can significantly reduce the risk of the dissolved substances polluting the water-vapor system of the unit. Combining with the three-stage gradient elution strategy (total duration ≥ 120 min, the proportion of the third stage ≥ 50%), the model parameters can map the actual working conditions of the high-temperature condensate system (≤ 85°C).

[0073] Furthermore, the determination criteria for the dissolution characteristics include: if the sum of A and y0 is less than 50, B < 0.25, and ∫ydx < 200, then the fiber powder meets the requirements.

[0074] A lower B value indicates a low dissolution rate of the fiber powder, which can maintain chemical inertness during the operation of the unit and significantly reduce the content of dissolved substances released into the water-vapor system of the unit, thereby reducing the conductivity of the boiler water and ensuring its normal operation.

[0075] Furthermore, the total duration of the three-stage rinsing is not less than 120 min, the proportion of the first stage is ≤20%, and the proportion of the third stage is ≥50%.

[0076] The first stage (≤20% of the duration): quickly remove loose surface impurities (such as corrosion products), and flush at a high flow rate for a short time to avoid clogging the filter element;

[0077] The third stage (≥50% of the duration): perform long-interval rinsing to fully release deep-layer steady residues (such as silicates), and the duration proportion exceeding half ensures the full dissociation of stubborn pollutants;

[0078] The total duration ≥120 min covers the start-up and shutdown cycles of the unit (refer to high-temperature operation ≤75°C), and the gradient time design (1 - 2 min → 5 - 8 min → 15 - 20 min) synchronously restores the effects of temperature and pressure fluctuations on dissolution, shortening the evaluation cycle.

[0079] Furthermore, the method also includes synchronously measuring the content index of the dissolved substances in the rinsing solution when measuring the conductivity of the rinsing solution. The content index of the dissolved substances is measured by integrating y = A*exp(-B*x) + y0: ∫(y = A*exp(-B*x) + y0)dx.

[0080] Exemplarily, continue to refer to Figure 3 , and integrate the obtained fitting curve:

[0081] ∫ydx = -43.318e -0.22x +1.37x + C,

[0082] Its main dissolution time is 20 min. Substituting it in, the content index of the dissolved substances during this period is 70.19 μS / cm, indicating that its total dissolved substances are also low.

[0083] Furthermore, the determination criteria for the dissolution characteristics include: if ∫ydx < 75, the fiber powder meets the requirements.

[0084] Beneficial effects: calculating the content index of the dissolved substances reduces the misjudgment rate; the sudden increase in conductivity prompts the need to review the integral value of the dissolved substances, avoiding the distortion of a single index, and providing a double-insurance criterion for the replacement cycle of the fiber powder.

[0085] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present disclosure, and should all be included within the protection scope of the present disclosure.

Claims

1. A cleaning device for fiber powder of a powder-covered filter, characterized in that, Comprising: A rinsing module, including a beaker (1), a constant flow pump (2), the inner tube of a double-layer tube (3), a sand core (4) and a sample collection tube (5) connected in sequence. Ultra-pure water is contained in the beaker (1), and it flows into the inner tube through the constant flow pump (2) to rinse the fiber powder installed in the inner tube. The rinsing liquid after rinsing flows into the sample collection tube (5); A heat preservation module, including a water bath (6), a constant flow pump (7), and the outer tube of the double-layer tube (3) connected in sequence. Constant temperature water is contained in the water bath (6), and it flows into the outer tube through the constant flow pump (7) for heat preservation, and then flows back to the water bath after flowing out of the outer tube.

2. The device according to claim 1, characterized in that The circulating water temperature of the outer tube of the double-layer tube (3) is kept constant at 50 ± 1 °C.

3. The device according to claim 1, characterized in that The flow rate of the constant flow pump (2) is 5 ± 0.5 mL / min, and the flow rate of the constant flow pump (7) is 10 ± 1 mL / min.

4. The device according to claim 1, characterized in that, The pore diameter of the sand core (4) is less than or equal to 0.45 μm and is used to intercept the fiber powder.

5. A method for evaluating the dissolution characteristics of fiber powder for a powder-covered filter, using the device according to claim 1, characterized in that, Including: Take a sample of the fiber powder to be tested and place it in the inner tube of the double-layer tube (3); Inject the ultra-pure water in the beaker (1) into the inner tube through the constant flow pump (2), and rinse the fiber powder installed in the inner tube in three stages. The rinsing liquid after rinsing flows into the sample collection tube (5), where, In the first stage, rinsing is carried out every first preset time, in the second stage, rinsing is carried out every second preset time, and in the third stage, rinsing is carried out every third preset time, The first preset time is less than the second preset time, the second preset time is less than the third preset time, and the durations of the first stage, the second stage, and the third stage increase in sequence; Measure the conductivity of the rinsing liquid, and use the rinsing time as the abscissa and the conductivity of the rinsing liquid as the ordinate to plot the relationship curve of the conductivity changing with the rinsing time; Fit the relationship curve to obtain the dissolution rate of the fiber powder, and evaluate the dissolution characteristics of the fiber powder according to the dissolution rate.

6. The method according to claim 5, characterized in that, The fitting of the relationship curve to obtain the dissolution rate of the fiber powder is through the following formula: y = A * exp(-B * x) + y0, where y is the conductivity, the sum of A and y0 is the initial dissolution value, B is the dissolution rate, and x is the rinsing time.

7. The method according to claim 6, wherein The determination criteria for the dissolution characteristics include: If the sum of A and y0 is less than 50 and B < 0.25, ∫ydx < 200, then the fiber powder meets the requirements.

8. The method according to claim 5, characterized in that The total duration of the three-stage rinsing is not less than 120 min, the proportion of the first stage is ≤ 20%, and the proportion of the third stage is ≥ 50%.

9. The method according to claim 5, characterized in that The method also includes synchronously measuring the content index of the dissolved substances in the rinsing liquid when measuring the conductivity of the rinsing liquid.

10. The method according to claim 9, characterized in that, The content index of the dissolved substances is measured by integrating y = A * exp(-B * x) + y0.

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