A pulp bleaching pretreatment device
By adding 27.5% hydrogen peroxide to the pulp pretreatment unit and mixing it with the pulp, the problem of balancing improved pulp brightness and low pollution after oxygen delignification was solved, thus improving pre-bleaching brightness and reducing pollutant emissions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ASIA SYMBOL SHANDONG PULP & PAPER
- Filing Date
- 2025-09-30
- Publication Date
- 2026-07-31
AI Technical Summary
In existing technologies, it is difficult to achieve both improved pulp brightness and low pollution after oxygen delignification, resulting in high chemical consumption and high risk of pollutant emissions during the bleaching stage.
A pulp bleaching pretreatment device is used. 27.5% hydrogen peroxide is added to the pulp conveying system through the hydrogen peroxide conveying system. After being mixed with the pulp, it is stored in the pulp storage system. The hydrogen peroxide is used to oxidize and degrade residual lignin macromolecules in an alkaline high-temperature environment, thereby improving the whiteness before bleaching and reducing the amount of subsequent chemicals used.
It improves the pre-bleaching whiteness of the pulp, reduces the generation of pollutants, and lowers the emission of organochlorine compounds, achieving a balance between improving pulp whiteness and reducing pollution.
Smart Images
Figure CN224578534U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of pulp production, and in particular to a pulp bleaching pretreatment apparatus. Background Technology
[0002] Bleached sulfate pulping is a cornerstone process for producing high-brightness, high-strength pulp and manufacturing high-end paper products. Its main process flow includes raw material pretreatment, cooking, screening, oxygen delignification, and bleaching. High-grade cultural printing paper and household paper products have high brightness requirements, typically targeting a brightness of 89% ISO or higher. To meet pulp mills' demands for high-brightness, low-pollution pulp, the pulp after cooking and washing undergoes an oxygen delignification stage. This stage, conducted in an alkaline (NaOH) and high-temperature environment, utilizes oxygen as an oxidant to selectively oxidize and degrade residual lignin macromolecules through a free radical chain reaction. This fragments and polarizes the lignin (increasing the number of hydrophilic groups such as carboxyl and hydroxyl groups), ultimately dissolving it in the alkaline solution and washing it away, resulting in a significant reduction in the pre-bleaching kappa number. After oxygen delignification, the pulp's brightness can reach 49%-53% ISO.
[0003] To meet the pulp mill's demand for high-brightness, low-pollution pulp, the bleaching process mainly adopts elemental chlorine-free bleaching (ECF bleaching), which consists of a high-temperature delignification stage (DHT), an enhanced alkali extraction stage (EOP), a first chlorine dioxide bleaching stage (D1), and a second chlorine dioxide bleaching stage (D2). Among them, DHT, D1, and D2 are ClO2 bleaching stages, and the EOP stage is an oxygen-enhanced alkali extraction stage. By adjusting the amount of chemicals used in each stage, the final target brightness is achieved.
[0004] Due to the influence of wood chip quality, the pulping process may result in high kappa values and poor oxygen removal efficiency in the cooked pulp. This leads to low initial bleaching degree, high effective chlorine consumption during the bleaching stage, heavy load on related chemical equipment, and even the possibility that the post-bleaching brightness may not reach the target brightness. In traditional processes, the pulp directly enters the bleaching stage after oxygen removal. Since the brightness is only 49%-53% ISO, a large amount of ClO2 is still needed for subsequent bleaching, which greatly increases the risk of toxic organochlorides (AOX) emissions.
[0005] Therefore, how to balance the improvement of pulp brightness and low pollution after oxygen delignification is a problem that urgently needs to be solved by those skilled in the art. Utility Model Content
[0006] This application proposes a pulp bleaching pretreatment device that improves the pre-bleaching whiteness of the pulp and reduces the amount of contaminants generated, thereby achieving both improved pulp whiteness and low pollution.
[0007] To achieve the above objectives, this application discloses the following technical solutions:
[0008] A pulp bleaching pretreatment apparatus includes a hydrogen peroxide conveying system, a pulp conveying system, and a pulp storage system; the outlet of the hydrogen peroxide conveying system is connected to the pulp conveying system; the outlet of the pulp conveying system is connected to the inlet of the pulp storage system; the pulp storage system mixes hydrogen peroxide with pulp and stores it to prepare for pulp bleaching.
[0009] In some embodiments, the hydrogen peroxide delivery system includes a hydrogen peroxide storage tank, a hydrogen peroxide pressurization pump, a hydrogen peroxide delivery pipe, a flow meter, and a hydrogen peroxide flow control valve;
[0010] The inlet end of the hydrogen peroxide delivery pipe is connected to the hydrogen peroxide storage tank, and the outlet end of the hydrogen peroxide delivery pipe is connected to the slurry delivery system. The hydrogen peroxide pressurization pump, flow meter, and hydrogen peroxide flow control valve are located on the hydrogen peroxide delivery pipe.
[0011] In some embodiments, the slurry delivery system includes a slurry delivery pipe, a mixing assembly, a mixing delivery pipe, a mixing delivery pump, and a mixing delivery control valve;
[0012] The hydrogen peroxide delivery pipe is connected to the slurry delivery pipe, and the connection point of the hydrogen peroxide delivery pipe and the slurry delivery pipe is located 1.5m-2m in front of the mixing component;
[0013] The inlet end of the mixing component is connected to the outlet end of the slurry conveying pipe, the outlet end of the mixing component is connected to the inlet end of the mixing conveying pipe, and the outlet end of the mixing conveying pipe is connected to the slurry storage system.
[0014] The mixing pump and mixing control valve are located on the mixing pipe, and at one end close to the mixing assembly.
[0015] In some embodiments, the slurry storage system includes a slurry storage tower, and a mixing delivery pipe is connected to the upper inlet of the slurry storage tower.
[0016] In some embodiments, the slurry storage tower also includes a slurry level gauge that can monitor the slurry level height inside the slurry storage tower.
[0017] In some embodiments, the slurry delivery system also includes a pH meter and an online alkali adjustment component, located before the connection point between the hydrogen peroxide delivery pipe and the slurry delivery pipe.
[0018] Some embodiments also include a control cabinet, which is electrically connected to the hydrogen peroxide pressurization pump, flow meter, hydrogen peroxide flow control valve, mixing delivery pump, mixing delivery control valve, pH meter, and online alkali adjustment assembly, respectively.
[0019] In some embodiments, the hydrogen peroxide storage tank also includes a hydrogen peroxide supply pipe and a hydrogen peroxide level control valve, the hydrogen peroxide level control valve being located on the hydrogen peroxide supply pipe, and the outlet end of the hydrogen peroxide supply pipe being connected to the hydrogen peroxide storage tank.
[0020] In some embodiments, the hydrogen peroxide delivery system also includes at least two pressure gauges located on the hydrogen peroxide delivery pipe, one before and one after the hydrogen peroxide booster pump.
[0021] Some embodiments also include an insulation section located in the slurry conveying system to ensure that the temperature of the slurry conveying system is maintained at a set value.
[0022] As can be seen from the above technical solution, when treating oxygen-delignified pulp before bleaching, the pulp bleaching pretreatment device provided in this application can be used. Hydrogen peroxide is added to the pulp conveying system through the hydrogen peroxide conveying system. After the two are mixed, they are stored in the pulp storage system. The brightness of the pulp is improved by hydrogen peroxide, thereby reducing the dosage of subsequent added chemicals, so as to achieve the effect of improving the brightness of the pulp after oxygen delignification and low pollution. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort, and this application can be applied to other similar scenarios based on the provided drawings, all of which fall within the scope of protection of this utility model. Unless obvious from the linguistic context or otherwise specified, the same reference numerals in the drawings represent the same structure or operation.
[0024] Figure 1 This is a flowchart of a water-saving device provided in an embodiment of this application;
[0025] Among them, 10-pulp bleaching pretreatment device;
[0026] 100 - Hydrogen peroxide conveying system; 200 - Slurry conveying system; 300 - Slurry storage system;
[0027] 110 - Hydrogen peroxide storage tank; 111 - Hydrogen peroxide supply pipe; 120 - Hydrogen peroxide booster pump; 130 - Hydrogen peroxide delivery pipe; 140 - Flow meter; 150 - Hydrogen peroxide flow control valve;
[0028] 210 - Slurry delivery pipe; 211 - pH meter; 220 - Mixing assembly; 230 - Mixing delivery pipe; 240 - Mixing delivery pump; 250 - Mixing delivery control valve;
[0029] 310 - Slurry Storage Tower. Detailed Implementation
[0030] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the application and not intended to limit it. The described embodiments are only a part of the embodiments of the present application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without inventive effort are within the scope of protection of the present application.
[0031] To address the issue that pulp after oxygen delignification cannot simultaneously achieve increased brightness and low contamination, this application, in conjunction with the accompanying drawings, specifically describes the structure of the pulp pretreatment device 10 for bleaching:
[0032] See Figure 1 This application describes a pulp bleaching pretreatment apparatus 10, including a hydrogen peroxide conveying system 100, a pulp conveying system 200, and a pulp storage system 300; the outlet end of the hydrogen peroxide conveying system 100 is connected to the pulp conveying system 200; the outlet end of the pulp conveying system 200 is connected to the inlet end of the pulp storage system 300; the pulp storage system 300 mixes hydrogen peroxide with pulp and stores it to prepare for pulp bleaching.
[0033] As can be seen from the above technical solution, when treating oxygen-delignified pulp before bleaching, the pulp bleaching pretreatment device 10 provided in this application can be used. 27.5% hydrogen peroxide is added to the pulp conveying system 200 through the hydrogen peroxide conveying system 100. After mixing, the two are stored in the pulp storage system 300. The brightness of the pulp is improved by using hydrogen peroxide, thereby reducing the dosage of chemicals added later, thus achieving the effect of both improving brightness and reducing pollution.
[0034] The hydrogen peroxide delivery system 100, a highlight of this application, provides 27.5% hydrogen peroxide to the slurry delivery system 200. Under alkaline and high-temperature conditions, hydrogen peroxide decomposes to produce hydrogen peroxide anions and a small amount of free radicals. These active substances oxidize and degrade the chromophores in residual lignin macromolecules, thereby improving pre-bleaching whiteness and reducing the difference between pre-bleaching whiteness and the target whiteness. This reduces the amount of effective chlorides such as ClO2 added in the subsequent bleaching stage. Because the hydrogen peroxide reaction only produces water and oxygen, without generating pollutants, and the reduced ClO2 usage decreases the formation of organochlorides (AOX), it also reduces pollutant emissions. The reason for choosing a 27.5% hydrogen peroxide concentration is that it is a commonly used industrial standard concentration, requiring no additional dilution and reducing operational complexity. The dosage of 1-2 kg / Adt has also been experimentally verified; when the dosage is below 1 kg / Adt, the whiteness improvement is less than 1% ISO, and when it is above 2 kg / Adt, the whiteness improvement slows down and the cost increases significantly. The structural features of the hydrogen peroxide delivery system 100 will be described in detail below.
[0035] To ensure a more stable delivery of hydrogen peroxide by the hydrogen peroxide delivery system 100, the system includes a hydrogen peroxide storage tank 110, a hydrogen peroxide booster pump 120, a hydrogen peroxide delivery pipe 130, a flow meter 140, and a hydrogen peroxide flow control valve 150. The hydrogen peroxide delivery pipe 130 serves as the connecting line for the entire hydrogen peroxide delivery system 100, linking all the components together in series. The inlet end of the hydrogen peroxide delivery pipe 130 is connected to the hydrogen peroxide storage tank 110, and the outlet end is connected to the slurry delivery system 200. The hydrogen peroxide booster pump 120, the flow meter 140, and the hydrogen peroxide flow control valve 150 are all located on the hydrogen peroxide delivery pipe 130.
[0036] The hydrogen peroxide storage tank 110 serves as a hydrogen peroxide supply device, storing a certain amount of hydrogen peroxide to ensure a stable flow rate within the hydrogen peroxide delivery pipe 130. To ensure stable hydrogen peroxide delivery, a hydrogen peroxide supply pipe 111 and a hydrogen peroxide level control valve are typically installed. The hydrogen peroxide level control valve is located on the hydrogen peroxide supply pipe 111, whose outlet end is connected to the hydrogen peroxide storage tank 110. The hydrogen peroxide level control valve adjusts its opening based on the liquid level in the hydrogen peroxide storage tank 110. Generally, a mechanical float-type level control valve or an electromagnetic control valve can be used.
[0037] Taking a mechanical float-type level control valve as an example: With the working liquid level set at 30%, when the liquid level in the hydrogen peroxide storage tank 110 is below 30%, the float descends due to buoyancy. Simultaneously, the valve stem connected to the float also descends, increasing the valve opening of the hydrogen peroxide level control valve. At this time, the hydrogen peroxide supply pipe 111 delivers hydrogen peroxide into the hydrogen peroxide storage tank 110, and the liquid level begins to rise. When the liquid level rises to 30%, the float gradually rises under buoyancy, pushing the valve stem upward, causing the hydrogen peroxide level control valve to gradually close until it shuts off. At this point, the hydrogen peroxide supply pipe 111 stops delivering hydrogen peroxide. This structure maintains the liquid level in the hydrogen peroxide storage tank 110 at approximately 30%. Furthermore, the mechanical float-type level control valve relies on buoyancy, eliminating the need for additional power and reducing energy consumption.
[0038] To balance strength and corrosion resistance, the hydrogen peroxide delivery pipe 130 is typically made of 316L stainless steel. This material offers superior corrosion resistance compared to ordinary stainless steel, releases very few metal ions, and does not react with hydrogen peroxide, significantly ensuring the stability of hydrogen peroxide delivery. It also possesses extremely high strength, capable of withstanding vibrations from the pump in the hydrogen peroxide delivery system 100 or external impacts, thus extending the service life of the system. Furthermore, to prevent gaps during installation, the hydrogen peroxide delivery pipe 130 is connected to other components using welding, preferably argon arc welding. The weld seams are polished and passivated to reduce the risk of hydrogen peroxide crystals precipitating on the pipe and to prevent the hydrogen peroxide solution from remaining in the pipe's internal gaps and causing corrosion.
[0039] As the power source for the hydrogen peroxide delivery system 100, the stable operation of the hydrogen peroxide booster pump 120 is crucial. To ensure the safe and stable operation of the hydrogen peroxide booster pump 120, it is essential to first consider installing it near the hydrogen peroxide storage tank 110, shortening the pipeline path at the pump inlet to reduce the risk of gas entering the pump body. Simultaneously, the hydrogen peroxide delivery pipes 130 before and after the pump should be smoothly connected to prevent turbulence and dead zones, avoiding prolonged stagnation of hydrogen peroxide before and after the pump, thus reducing corrosion of the hydrogen peroxide booster pump 120. Similarly, the pump body of the hydrogen peroxide booster pump 120 should preferably be made of 316L stainless steel to prevent corrosion of the pump body by hydrogen peroxide, thus ensuring more stable operation of the hydrogen peroxide booster pump 120.
[0040] The function of flow meter 140 is to detect the flow rate of hydrogen peroxide, and the function of hydrogen peroxide flow control valve 150 is to control the flow rate of hydrogen peroxide delivery pipe 130. In this application, the control accuracy of flow meter 140 needs to be maintained at ±0.5% to achieve fine control of the hydrogen peroxide delivery flow rate, keeping the hydrogen peroxide delivery flow rate within a stable range. When flow meter 140 detects that the flow rate is too high, the opening of hydrogen peroxide flow control valve 150 can be reduced, thereby reducing the flow rate of hydrogen peroxide delivery pipe 130; when flow meter 140 detects that the flow rate is too low, the opening of hydrogen peroxide flow control valve 150 can be increased, thereby increasing the flow rate of hydrogen peroxide delivery pipe 130.
[0041] To maintain the delivery pressure of the hydrogen peroxide delivery system 100 at 0.3-0.5 MPa, the system includes at least two pressure gauges, one before and one after the hydrogen peroxide booster pump 120. Both gauges are located on the hydrogen peroxide delivery pipe 130 and monitor the pipe pressure before and after the pump. Since the pipe pressure of the slurry delivery system 200 is 0.2-0.4 MPa, to ensure the outlet pressure of the hydrogen peroxide booster pump 120 meets the required standard, the hydrogen peroxide flow control valve 150 can be adjusted based on the pressure readings of the pressure gauges before and after the pump, thus maintaining the outlet pressure of the hydrogen peroxide booster pump 120 at 0.3-0.5 MPa. Alternatively, if the hydrogen peroxide booster pump 120 is a variable frequency pump, the operating frequency can be adjusted to achieve the standard outlet pressure. The pressure gauges facilitate on-site inspection and adjustment.
[0042] The structure of the hydrogen peroxide conveying system 100 has been introduced above. Next, the structure of the slurry conveying system 200 will be introduced.
[0043] The function of the slurry conveying system 200 is to mix oxygen-delignified slurry with hydrogen peroxide and convey the mixture to the slurry storage system 300. The selected slurry concentration is 11.5%-12.0%. Controlling the slurry concentration is crucial because excessively high concentrations can lead to uneven mixing, while excessively low concentrations reduce reaction efficiency. The slurry conveying system 200 includes a slurry conveying pipe 210, a mixing component 220, a mixing and conveying pipe 230, a mixing and conveying pump 240, and a mixing and conveying control valve 250. The slurry conveying pipe 210 and the mixing and conveying pipe 230 connect the various components in series within the slurry conveying system 200.
[0044] First, the pulp delivery pipe 210 originates from the pulp washer used in the oxygen delignification pulp treatment. After washing, the pulp's pH value remains between 10 and 10.5, and its temperature approaches 100°C. Therefore, the pulp delivery pipe 210 must meet the requirements for alkali resistance and high temperature resistance. Here, 316L stainless steel, the same material as the hydrogen peroxide delivery pipe 130, is preferred. Of course, to ensure the stability of the pulp's pH, the pulp delivery system 200 also includes a pH meter 211 and an online alkali adjustment component. The pH meter 211 and the online alkali adjustment component are located before the connection point between the hydrogen peroxide delivery pipe 130 and the pulp delivery pipe 210. This design ensures that the pH value of the pulp is maintained at 10-10.5 before mixing with hydrogen peroxide, which is more conducive to improving measurement accuracy compared to mixing the pulp with hydrogen peroxide. When the pH detector 211 detects that the pH value of the slurry is low, it will transmit a signal to the online alkali adjustment component, which will then provide sodium hydroxide (commonly known as caustic soda) or magnesium hydroxide to raise the pH value of the slurry. When the pH detector 211 detects that the pH value of the slurry reaches 10-10.5, it will transmit a signal to the online alkali adjustment component to stop adding alkali, thereby maintaining the pH balance of the slurry.
[0045] Next, the outlet end of the hydrogen peroxide delivery pipe 130 is connected to the slurry delivery pipe 210, and the connection point between the hydrogen peroxide delivery pipe 130 and the slurry delivery pipe 210 is located 1.5m-2m in front of the mixing component 220. The purpose of this is to ensure that the mixture of hydrogen peroxide and slurry has a certain flow rate before entering the mixing component 220. After entering the mixing component 220, the turbulence allows the hydrogen peroxide and slurry to be fully and evenly mixed, which is more conducive to the reaction of hydrogen peroxide to improve the whiteness of the slurry.
[0046] The mixture after passing through the mixing component 220 is pressurized by the mixing delivery pump 240 located near the mixing component 220, causing the mixture to flow through the mixing delivery control valve 250 and into the slurry storage system 300 via the mixture delivery pipe. It is important to note that because the mixture contains hydrogen peroxide and slurry, the mixture delivery pipe, mixing delivery pump 240, and mixing delivery control valve 250 must all be made of 316L stainless steel and connected using argon arc welding. During the arrangement of the mixture delivery pipe, sharp corners should be avoided, and pipe bends must be greater than or equal to 90° to ensure smoother transport of the slurry and mixture and prevent accumulation in the pipes. Of course, drain valves should be provided before and after the mixing delivery pump 240 for future maintenance, drainage, and sludge removal.
[0047] Having introduced the slurry conveying system 200, we will now introduce the slurry storage system 300.
[0048] The function of the slurry storage system 300 is to provide a stable buffer space for the slurry, preparing it for the subsequent bleaching process. In this application, hydrogen peroxide is added to the slurry, allowing the mixture of hydrogen peroxide and slurry to react fully within this stable buffer space, thereby significantly improving the whiteness of the slurry. The slurry storage system 300 includes a slurry storage tower 310, and a mixing and conveying pipe 230 is connected to the upper inlet of the slurry storage tower 310. The advantage of feeding the mixture from the top of the storage tower 310 through the mixing conveying pipe 230 is that the mixture entering the storage tower 310 is located at the top layer of the cross-section of the storage tower 310, while the mixture at the bottom has already undergone a long reaction. By controlling the opening of the lower outlet, the mixture at the bottom that has completed the reaction can flow out slowly, thereby creating a layered piston-like feeding effect in the storage tower 310: new mixture enters from the top, and the mixture that has completed the reaction flows out from the bottom. This orderly feeding can prevent back mixing of the mixture and make the reaction time of the mixture controllable. In this embodiment, the reaction time of the mixture can be controlled within 30-45 minutes by controlling the liquid level height of the storage tower 310 and the feeding and discharging speed.
[0049] Accordingly, to facilitate the control of the liquid level in the slurry storage tower 310, the slurry storage tower 310 also includes a slurry level gauge, which can typically be a radar level gauge or an ultrasonic level gauge. The working principle of a radar level gauge is that it transmits high-frequency electromagnetic waves through an antenna. After the electromagnetic waves contact the surface of the mixed liquid, they are reflected back and received by the same antenna. By calculating the time it takes for the electromagnetic waves to return, the liquid level distance is determined. The advantage of a radar level gauge is that it does not contact the mixed liquid and is unaffected by the temperature or steam interference of the mixed liquid. The principle of an ultrasonic level gauge is similar to that of a radar level gauge. It transmits ultrasonic waves, which are reflected back after contacting the surface of the mixed liquid and are received by the transmitter. The time it takes for the sound waves to return is calculated to determine the liquid level distance. The advantage of an ultrasonic level gauge is that it does not contact the mixed liquid and has lower installation costs.
[0050] The mixing pump 240 and the mixing control valve 250 are located on the mixing pipe 230 and at one end close to the mixing assembly 220.
[0051] The structure and principle of the pulp storage system 300 have been described above. It should also be noted that the pulp bleaching pretreatment device 10 includes a control cabinet. The control cabinet is electrically connected to the hydrogen peroxide pressurization pump 120, flow meter 140, hydrogen peroxide flow control valve 150, mixing and conveying pump 240, mixing and conveying control valve 250, pulp level gauge, pH detector 211, and online alkali adjustment components for power distribution and automatic control of these components. This allows for more precise control of the pulp bleaching pretreatment device 10 and reduces manpower requirements.
[0052] In some embodiments, to maintain a constant temperature during pulp conveying, the pulp bleaching pretreatment device 10 also includes an insulation section located in the pulp conveying system 200, typically outside the pulp conveying pipe 210, mixing component 220, and mixing conveying pipe 230. To further prevent heat loss, an insulation section is also provided on the mixing conveying control valve 250. The insulation section can be made of rubber-plastic insulation cotton or centrifugal glass wool. In this embodiment, since the initial pulp temperature is 100°C, centrifugal glass wool is preferred, and it is wrapped circumferentially around the areas requiring insulation. This design prevents heat loss while also making it convenient for operators to work and avoiding burns. Of course, if the pulp conveying system 200 is located outdoors, the protection of the centrifugal glass wool should also be considered. A galvanized steel or aluminum alloy protective shell can be added to the outside of the centrifugal glass wool to protect it from wind, sun, and external damage.
[0053] The structure of the pulp bleaching pretreatment device 10 has been described above. The following describes the operation steps of the pulp bleaching pretreatment device 10. First, the pulp that has undergone the oxygen delignification stage is washed in a pulp washer, controlling the pH of the pulp to be 10-10.5 and the temperature to be around 100℃. Then, the hydrogen peroxide storage tank 110 and the pulp delivery pipe 210 are connected through a hydrogen peroxide delivery pipe 130. A hydrogen peroxide pressurization pump 120, a flow meter 140, and a hydrogen peroxide flow control valve 150 are sequentially installed on the hydrogen peroxide delivery pipe 130. Next, the hydrogen peroxide pressurization pump 120 controls the delivery pressure of the hydrogen peroxide to 0.3-0.5 MPa, and the flow meter 140 controls the flow rate. The flow rate of hydrogen peroxide is controlled by valves 40 and 150. 27.5% hydrogen peroxide is added to the slurry at a rate of 1-2 kg / Adt (octane-dry slurry). The concentration of the mixed slurry is adjusted to 11.5%-12.0%. Finally, the mixed slurry is transported to the storage tower 310 by the mixing and conveying pump 240. The level of the storage tower 310 is controlled by the storage level gauge to maintain it at 40%-60%, so that the hydrogen peroxide and the slurry can fully react in an alkaline high-temperature environment to improve the whiteness of the slurry.
[0054] In the above context, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
[0055] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. "And / or" in this article is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone.
[0056] It should be noted that, for ease of description, only the parts relevant to the application are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this application can be combined with each other.
[0057] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed, and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. The scope of this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described application concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.
Claims
1. A pulp bleaching pretreatment apparatus, characterized in that, It includes a hydrogen peroxide delivery system (100), a slurry delivery system (200), and a slurry storage system (300); The outlet end of the hydrogen peroxide delivery system (100) is connected to the slurry delivery system (200); The outlet end of the slurry conveying system (200) is connected to the inlet end of the slurry storage system (300); The slurry storage system (300) stores hydrogen peroxide mixed with slurry.
2. The pulp bleaching pretreatment apparatus as described in claim 1, characterized in that, The hydrogen peroxide delivery system (100) includes a hydrogen peroxide storage tank (110), a hydrogen peroxide pressurization pump (120), a hydrogen peroxide delivery pipe (130), a flow meter (140), and a hydrogen peroxide flow control valve (150); The inlet end of the hydrogen peroxide delivery pipe (130) is connected to the hydrogen peroxide storage tank (110), and the outlet end of the hydrogen peroxide delivery pipe (130) is connected to the slurry delivery system (200). The hydrogen peroxide pressurization pump (120), the flow meter (140), and the hydrogen peroxide flow control valve (150) are located on the hydrogen peroxide delivery pipe (130).
3. The pulp bleaching pretreatment apparatus as described in claim 2, characterized in that, The slurry conveying system (200) includes a slurry conveying pipe (210), a mixing component (220), a mixing conveying pipe (230), a mixing conveying pump (240), and a mixing conveying control valve (250); The outlet end of the hydrogen peroxide delivery pipe (130) is connected to the slurry delivery pipe (210), and the connection position between the hydrogen peroxide delivery pipe (130) and the slurry delivery pipe (210) is located 1.5m-2m in front of the mixing component (220). The inlet end of the mixing component (220) is connected to the outlet end of the slurry conveying pipe (210), the outlet end of the mixing component (220) is connected to the inlet end of the mixing conveying pipe (230), and the outlet end of the mixing conveying pipe (230) is connected to the slurry storage system (300). The mixing delivery pump (240) and the mixing delivery control valve (250) are located on the mixing delivery pipe (230) and at one end close to the mixing assembly (220).
4. The pulp bleaching pretreatment apparatus as described in claim 3, characterized in that, The slurry storage system (300) includes a slurry storage tower (310), and the mixing and conveying pipe (230) is connected to the upper inlet of the slurry storage tower (310).
5. The pulp bleaching pretreatment apparatus as described in claim 4, characterized in that, The slurry storage tower (310) also includes a slurry level gauge, which can monitor the liquid level height inside the slurry storage tower (310).
6. The pulp bleaching pretreatment apparatus as described in claim 5, characterized in that, The slurry conveying system (200) also includes a pH detector (211) and an online alkali adjustment component, which are located before the connection point between the hydrogen peroxide conveying pipe (130) and the slurry conveying pipe (210).
7. The pulp bleaching pretreatment apparatus as described in claim 6, characterized in that, It also includes a control cabinet, which is electrically connected to the hydrogen peroxide pressurization pump (120), the flow meter (140), the hydrogen peroxide flow control valve (150), the mixing and conveying pump (240), the mixing and conveying control valve (250), the slurry level gauge, the pH value detector (211), and the online alkali adjustment component, respectively.
8. The pulp bleaching pretreatment apparatus as described in claim 2, characterized in that, The hydrogen peroxide storage tank (110) also includes a hydrogen peroxide supply pipe (111) and a hydrogen peroxide level control valve. The hydrogen peroxide level control valve is located on the hydrogen peroxide supply pipe (111), and the outlet end of the hydrogen peroxide supply pipe (111) is connected to the hydrogen peroxide storage tank (110).
9. The pulp bleaching pretreatment apparatus as described in claim 3, characterized in that, The hydrogen peroxide delivery system (100) also includes at least two pressure gauges located on the hydrogen peroxide delivery pipe (130) and respectively before and after the hydrogen peroxide pressurization pump (120).
10. The pulp bleaching pretreatment apparatus as described in claim 1, characterized in that, It also includes an insulation section located in the slurry conveying system (200) to ensure that the temperature of the slurry conveying system (200) is maintained at a set value.