Sodium methoxide preparation system for fluorescent whitening agent

Abstract

This invention discloses a sodium methoxide preparation vessel, preparation system, and method for preparing fluorescent whitening agents, belonging to the chemical industry. It includes the following apparatus: an esterification vessel, a preparation vessel, a distillation vessel, a sodium methoxide preparation vessel, a coarse powder crystallization vessel, a dissolving vessel, and a fine powder crystallization vessel. The sodium methoxide preparation vessel includes shock-absorbing components and a shock-absorbing drying assembly to achieve rapid temperature control within the reaction vessel without affecting its stirring and shock-absorbing functions. The process includes the following steps: adding biphenyl dichlorobenzyl and triethyl phosphite to the esterification vessel under nitrogen atmosphere, heating, stirring, and reflux; adding DMF, sodium o-sulfonate benzaldehyde, and sodium methoxide to the resulting ester; maintaining the temperature for a certain time; adding concentrated sulfuric acid; stirring, heating, and distilling; adding industrial salt and cooling; and then dissolving, filtering, cooling, and pressure filtration. This invention allows for the recycling of materials and byproducts, saves energy, reduces waste emissions, and achieves industrial recycling.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering, and more specifically, to a sodium methoxide preparation vessel, preparation system, and method for preparing fluorescent whitening agents. Background Technology

[0002] CBS351, or CBS for short, is a fluorescent whitening agent, specifically 4,4'-bis(2-sulfonate sodium styrene)biphenyl. It dissolves rapidly in cold water and possesses properties such as lightfastness, bleach resistance, and easy degradation, making it widely used in laundry detergents and other washing products for whitening. CBS is commonly available in four formulations: solid, paste, emulsion, and liquid. The solid product appears as a bright yellow-green uniform powder or granules; the paste product appears as a pale yellow-green; and the emulsion and liquid products both appear as pale yellow-green or yellow-green. All products are anionic and readily soluble in water. At 25°C, the solubility of the solid product in water is 25 g / L, the emulsion product contains 20-30%, and the maximum concentration of the liquid product in a pure aqueous solution at 25°C is approximately 2.5%. The maximum absorption wavelength in its spectrum is 349 nm. Its traditional manufacturing process involves a biphenyl benzylation reaction, followed by esterification with phosphite, and then condensation with sodium o-sulfonate benzaldehyde. However, during the preparation process, the actual reaction conditions often fluctuate with changes in the environment, leading to product instability. At the same time, the industrial waste generated during the production process is not only excessive but also not well treated. Summary of the Invention

[0003] 1. Technical problems to be solved

[0004] In view of the problems existing in the prior art, the purpose of this invention is to provide a sodium methoxide preparation vessel, preparation system and method for preparing fluorescent whitening agents, to strengthen process control in the preparation process, to provide better conditions for the reaction environment, to recycle and reuse materials and by-products in the production process, to save energy, to reduce the emission of waste gas, wastewater, and solid waste, and to realize the recycling of industrial production materials.

[0005] 2. Technical Solution

[0006] To solve the above problems, the present invention adopts the following technical solution.

[0007] A sodium methoxide preparation vessel for preparing fluorescent whitening agents, wherein a shock-absorbing and drying assembly is installed in the sodium methoxide preparation vessel, the shock-absorbing and drying assembly including a temperature control tube, a temperature control tube jacket and a through-hole shock absorber;

[0008] The upper part of the temperature control tube forms a first annular pipe, and the lower part forms a second annular pipe parallel to the first annular pipe. The first annular pipe and the second annular pipe are connected by multiple vertically arranged connecting pipes that are regularly distributed, forming a basket shape as a whole.

[0009] The temperature control tube has several inverted L-shaped pipes extending upwards from its top circumference, which are regularly distributed on the first annular pipe. Several straight pipes extend horizontally outwards from the bottom circumference of the temperature control tube. The outer casing of the temperature control tube is annular with several pipes with expansion joints distributed outwards, each pipe fitting onto a straight pipe on the temperature control tube. The through-hole type shock absorber is a double-layered annular structure with springs distributed circumferentially between the annular layers. Several through holes are provided according to the spring distribution to fit onto pipes on the outer casing of the temperature control tube. The outer side of the through-hole type shock absorber connects to the inner side of the outer layer of the vessel body, and the inner side of the through-hole type shock absorber is located on the outer side of the outer casing of the temperature control tube, with a gap between the through-hole type shock absorber and the outer side of the outer casing of the temperature control tube.

[0010] Furthermore, the sodium methoxide preparation vessel also includes a motor, vessel body, stirring rod, stirring blades, shock absorbers, shock absorber packing, and temperature controller;

[0011] The motor is installed above the vessel body, which is divided into a top cover and a vessel body. The top of the top cover has several feed inlets and a steam outlet. The top cover and the vessel body are sealed together by a flange. The vessel body is hollow inside. The lower half of the motor is connected to and drives a stirring rod. The stirring rod has stirring blades in the middle and lower part. The vessel body is divided into an inner layer and an outer layer, with a certain space between them. A sealed partition is provided near the outer wall of the inner layer in the space. A temperature controller is installed in the partition. The partition is connected to the outside of the sodium methoxide preparation vessel by an openable and closable channel. A shock-absorbing component is provided between the partition and the outer layer of the vessel body. The shock-absorbing component is a double-ringed structure with a circumferentially distributed spring installed in the interlayer between the two layers. The space between the inner and outer layers at the bottom of the vessel body is filled with shock-absorbing filler.

[0012] Furthermore, the sodium methoxide preparation vessel for preparing fluorescent whitening agents also includes a high-pressure self-tightening flange. The vibration-damping drying assembly is installed in the lower region of the sodium methoxide preparation vessel and located above the vibration-damping packing. The straight pipe consists of a long straight pipe and a short straight pipe. Each pair of inverted L-shaped pipes and short straight pipes are located on the same central axis in the vertical direction. Each short straight pipe is connected to the long straight pipe through the high-pressure self-tightening flange. The outermost channel of each inverted L-shaped pipe is fixed to the inner side of the inner layer of the vessel body through a flange and connects to the partition. The outermost end of each long straight pipe is connected to the outer side of the outer layer of the vessel body. The sealing between the long straight pipe and the inner layer of the vessel body is achieved using a flange. The inner side of the temperature control pipe jacket is connected to the outer side of the inner layer of the vessel body.

[0013] Furthermore, the upper half of the temperature control tube is provided with two symmetrical detachable mounting guides. The mounting guides are T-shaped, consisting of a longer side and a shorter side. The shorter side is a hollow channel that is nested and connected to the temperature control tube. One end of the longer side is provided with a notch.

[0014] The lower part of the stirring rod is provided with an installation auxiliary component, which is a through tube with an auxiliary block on its outer wall. The auxiliary block is composed of a long block and a short block in an L-shape, and the long block and the short block form a right angle with the right angle opening facing upward. The long block forms an acute angle with the central axis of the stirring rod with the opening facing upward, so that the auxiliary block forms an inclined angle relative to the stirring rod. The upper part of the long block is narrowed, and the narrowed width is less than the width of the notch on the installation guide. The inclined angle of the auxiliary block and the notch angle of the installation guide match, so that the notch engages with the auxiliary block.

[0015] A system for preparing a fluorescent whitening agent including a sodium methoxide preparation vessel includes an esterification vessel, a triethyl phosphite receiving tank, a preparation vessel, a first condensation vessel, a precision filter, a second condensation vessel, a distillation vessel, a recycled water receiving tank, a low-boiling DMF receiving tank, a high-boiling DMF receiving tank, a sodium methoxide preparation vessel, a coarse powder crystallization vessel, a filter press, a dissolving vessel, a filter, and a fine powder crystallization vessel.

[0016] The two outlets of the esterification reactor are respectively connected to the inlet of the triethyl phosphite receiving tank and the inlet of the second condensation reactor.

[0017] The two outlets of the preparation vessel are respectively connected to the inlet of the first condensation vessel and the inlet of the sodium methoxide preparation vessel. The outlet of the first condensation vessel, the precision filter, and one of the inlets of the second condensation vessel are sequentially connected. At the same time, the outlet of the sodium methoxide preparation vessel is connected to the other inlet of the second condensation vessel. The outlet of the second condensation vessel is connected to the inlet of the distillation vessel. The four outlets of the distillation vessel are respectively connected to the inlet of the recovery water receiving tank, the inlet of the DMF low-boiling receiving tank, the inlet of the DMF high-boiling receiving tank, and the inlet of the coarse powder crystallization vessel. The outlet of the coarse powder crystallization vessel is connected to one of the inlets of the filter press. The outlet of the filter press is connected to the inlet of the dissolving vessel. The outlet of the dissolving vessel is connected to the filter. The filter is connected to the inlet of the fine powder crystallization vessel. At the same time, the outlet of the fine powder crystallization vessel is connected to the other inlet of the filter press. The filter press, the dissolving vessel, the filter, and the fine powder crystallization vessel form a loop.

[0018] Furthermore, the esterification reactor is equipped with a biphenyl dichlorobenzyl inlet, a triethyl phosphite inlet, a nitrogen inlet, a sampling port, and a type 5 ester outlet. The triethyl phosphite receiving tank is equipped with a triethyl phosphite outlet. The preparation reactor is equipped with a DMF inlet. The first condensation reactor is equipped with an o-sulfonate benzaldehyde inlet. The sodium methoxide preparation reactor is equipped with a solid sodium methoxide inlet. The second condensation reactor is equipped with a type 5 ester inlet, which is connected to the type 5 ester outlet on the esterification reactor. The distillation reactor is equipped with a concentrated sulfuric acid inlet and a water / tap water inlet. The coarse powder crystallization reactor is equipped with an industrial salt inlet. The dissolving reactor is equipped with a water inlet. The above devices are controlled by DCS interlocking.

[0019] A method for preparing a fluorescent whitening agent includes the following steps:

[0020] The first step involves adding a portion of biphenyl dichlorobenzyl and triethyl phosphite to an esterification reactor. Under nitrogen atmosphere, the reactor is heated and maintained at 98-102°C while stirring to dissolve the material. The remaining triethyl phosphite is then added dropwise while the temperature is controlled at 130-140°C and refluxed. After the addition is complete, the temperature is naturally raised to 155-165°C and refluxed to recover the triethyl phosphite, yielding the esterified product.

[0021] The second step involves stirring and filtering DMF and sodium o-sulfonate benzaldehyde, adding the esterified product obtained in the first step, adding sodium methoxide dropwise while stirring, and then maintaining the temperature at 47-53℃ after the addition is complete.

[0022] The third step involves adding concentrated sulfuric acid to the material obtained in the previous step, stirring and heating it to 70-80℃ and then distilling it to recover DMF. Water is added and the mixture is stirred and dispersed for 5-10 minutes. The mixture is then distilled under negative pressure. After completion, the mixture is stirred and cooled to 40-50℃. Industrial salt is added and the temperature is lowered to 8-10℃. Stirring is stopped, and coarse powder is filtered, unloaded and dissolved, circulated and filtered, cooled, and fine powder is filtered.

[0023] Furthermore, in the first step, triethyl phosphite is added in two separate additions at a ratio of 1:2.

[0024] Furthermore, in the first step, the content of type 5 esters in the esterified product is ≥97%.

[0025] Furthermore, the distillation time after stirring and heating in the third step is 1.5-5 hours.

[0026] Furthermore, in the first step, the basic principle of the esterification reaction process is: [Reaction equation would be inserted here]

[0027]

[0028] Furthermore, in the second and third steps, the basic principle of the condensation reaction process is as follows:

[0029]

[0030] Furthermore, the reaction equation for the main esterification synthesis reaction of the present invention is as follows:

[0031]

[0032] Furthermore, the reaction equation for the condensation synthesis reaction of the present invention is as follows:

[0033]

[0034] 3. Beneficial effects

[0035] Compared with the prior art, the advantages of this invention are:

[0036] (1) The present invention reduces the vibration effect of the reactor during the production process by designing a shock-absorbing drying assembly.

[0037] (2) The present invention recovers triethyl phosphite used in the preparation of fluorescent whitening agent and recycles methanol mother liquor and DMF, effectively reducing the discharge of industrial waste.

[0038] (3) The present invention can achieve rapid temperature control in the reactor by designing a temperature control tube, without affecting the stirring and shock absorption effect of the reactor. It has significant temperature control and drying effect on the bottom of the reactor, and avoids changes in properties due to the characteristics of materials and final products in a humid environment.

[0039] (4) The present invention interacts with the temperature control tube jacket and the through hole type shock absorber in spatial position, but leaves a gap at the connection position. Therefore, when the through hole type shock absorber is subjected to external load spring expansion and contraction deformation, it will not affect the heat conduction function of the temperature control tube.

[0040] (5) This invention provides a technical process for the large-scale industrial production of fluorescent whitening agents, which is applicable to various application conditions. The materials and by-products used can be recycled and reused, realizing the circular use of industrial production. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the system structure for the esterification synthesis of the present invention;

[0042] Figure 2 This is a schematic diagram of the system structure of the condensation synthesis and finished product of the present invention;

[0043] Figure 3 This is a schematic diagram of the sodium methoxide preparation vessel of the present invention;

[0044] Figure 4 This is a cross-sectional view of the sodium methoxide preparation vessel of the present invention;

[0045] Figure 5 This is a three-dimensional structural view of the shock absorber of the present invention;

[0046] Figure 6 This is a three-dimensional structural view of the heating tube of the present invention;

[0047] Figure 7 This is a three-dimensional structural view of the heating tube jacket of the present invention;

[0048] Figure 8 This is a perspective view of the assembly of the heating tube and the heating tube jacket of the present invention;

[0049] Figure 9This is a three-dimensional structural view of the through-hole type shock absorber of the present invention;

[0050] Figure 10 This is a three-dimensional structural view of the shock-absorbing and drying assembly of the present invention.

[0051] Figure 11 This is a perspective view of the installation structure of the shock-absorbing and drying assembly of the present invention;

[0052] Figure 12 This is a perspective view of the installation structure of the stirring rod of the present invention;

[0053] Figure 13 This is a schematic diagram of the installation of the shock-absorbing and drying assembly of the present invention;

[0054] Figure 14 This is a partial schematic diagram of point C of the shock-absorbing and drying assembly of the present invention;

[0055] Figure 15 This is a process flow diagram of the esterification synthesis of the present invention;

[0056] Figure 16 This is a process flow diagram of the condensation synthesis of the present invention.

[0057] The following are the labels in the diagram: 1 Esterification kettle, 2 Triethyl phosphite receiving tank, 3 Preparation kettle, 4 First condensation kettle, 5 Precision filter, 6 Second condensation kettle, 7 Distillation kettle, 8 Recycled water receiving tank, 9 DMF low-boiling receiving tank, 10 DMF high-boiling receiving tank, 11 Sodium methoxide preparation kettle, 12 Coarse powder crystallization kettle, 13 Filter press, 14 Dissolving kettle, 15 Filter, 16 Fine powder crystallization kettle, 111 Motor, 112 Kettle body, 113 Stirring rod, 1131 Installation auxiliary parts, 114 Stirring blades, 115 Vibration damping parts, 116 Vibration damping packing, 117 Temperature controller, 118 Vibration damping and drying assembly, 1181 Temperature control tube, 1182 High-pressure self-tightening flange, 1183 Temperature control tube outer sleeve, 1184 Through-hole type vibration damping parts, 1185 Installation guide. Detailed Implementation

[0058] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0059] Example 1:

[0060] Please see Figure 1-15 A system for preparing a fluorescent whitening agent includes an esterification vessel 1, a triethyl phosphite receiving tank 2, a preparation vessel 3, a first condensation vessel 4, a precision filter 5, a second condensation vessel 6, a distillation vessel 7, a recycled water receiving tank 8, a DMF low-boiling receiving tank 9, a DMF high-boiling receiving tank 10, a sodium methoxide preparation vessel 11, a coarse powder crystallization vessel 12, a filter press 13, a dissolving vessel 14, a filter 15, and a fine powder crystallization vessel 16.

[0061] The esterification reactor 1 is equipped with a biphenyl dichlorobenzyl inlet, a triethyl phosphite inlet, a triethyl phosphite outlet, a nitrogen inlet, a sampling port, and a type 5 ester outlet. The type 5 ester outlet is connected to the type 5 ester inlet on the second condensation reactor 6. The triethyl phosphite outlet is connected to the triethyl phosphite receiving tank 2, which is used to recover triethyl phosphite. The esterification reactor 1 and the triethyl phosphite receiving tank 2 are used to complete the esterification reaction.

[0062] The mixing vessel 3 is equipped with a DMF inlet. One of the outlets of the mixing vessel 3 is connected to one of the inlets of the first condensation vessel 4. The first condensation vessel 4 is also equipped with a sodium o-sulfonate benzaldehyde inlet. The outlet of the first condensation vessel 4 is connected to a precision filter 5, which is connected to one of the inlets of the second condensation vessel 6. The other outlet of the mixing vessel 3 is connected to one of the inlets of the sodium methoxide mixing vessel 11. The sodium methoxide mixing vessel 11 is also equipped with a solid sodium methoxide inlet. The outlet of the sodium methoxide mixing vessel 11 is connected to the other inlet of the second condensation vessel 6. The second condensation vessel... The second condensation vessel 6 is equipped with a type 5 ester inlet, which is connected to the type 5 ester outlet of the esterification vessel 1. The outlet of the second condensation vessel 6 is connected to one of the inlets of the distillation vessel 7. The distillation vessel 7 is also equipped with a concentrated sulfuric acid inlet and a water / tap water inlet. Several outlets of the distillation vessel 7 are respectively connected to the inlets of the recovery water receiving tank 8, the DMF low-boiling receiving tank 9, the DMF high-boiling receiving tank 10, and the coarse powder crystallization vessel 12. The coarse powder crystallization vessel 12 is also equipped with an industrial salt inlet. The outlet of the coarse powder crystallization vessel 12 is connected to one of the inlets of the filter press 13.

[0063] The outlet of the filter press 13 is connected to one of the inlets of the dissolving vessel 14. The outlet of the dissolving vessel 14 is connected to two filters 15 in sequence. The filters 15 are connected to the inlet of the fine powder crystallization vessel 16. The outlet of the fine powder crystallization vessel 16 is connected to the inlet of the filter press 13 to achieve circulation. The dissolving vessel 14 is also equipped with a water inlet. All the above devices are interlocked and controlled by DCS.

[0064] In use, open the inlet valve of esterification vessel 1, add biphenyl dichlorobenzyl to esterification vessel 1, open the nitrogen inlet to replace esterification vessel 1, add triethyl phosphite, heat and stir, keep warm and reflux, first open the outlet of triethyl phosphite, use triethyl phosphite receiving tank 2 to recover triethyl phosphite, when triethyl phosphite is recovered to the point that there is no liquid reflux in the sight glass, perform sampling operation, after the sample test is qualified, esterification vessel 1 discharges type V ester into the second condensation vessel 6.

[0065] DMF is added to the preparation vessel 3, and sodium o-sulfonate benzaldehyde is added to the first condensation vessel 4. The stirring in the first condensation vessel 4 is turned on until the material is completely dissolved. After dissolution, the material is sent to the precision filter 5 for circulation and cleaning, and then filtered to the second condensation vessel 6. DMF is transferred to the sodium methoxide preparation vessel 11 through the preparation vessel 3, and solid sodium methoxide is added to the sodium methoxide preparation vessel 11. Type 5 ester is added to the second condensation vessel 6 through the esterification vessel 1. When the temperature in the second condensation vessel drops to 43-47℃, sodium methoxide is added dropwise to the second condensation vessel 6. The material is transferred to the distillation vessel 7, and concentrated sulfuric acid is added to the distillation vessel 7. The DMF low-boiling receiving tank 9 is turned on to recover DMF. When the temperature reaches 120℃, the recovery continues for 10 minutes. The DMF high-boiling receiving tank 10 is turned on. After recycling, add water / tap water to the distillation kettle 7, heat and stir, transfer the material to the coarse powder crystallization kettle 12, stir and cool, add industrial salt to the coarse powder crystallization kettle 12, cool, turn off the stirring, transfer the material to the filter press 13 for coarse powder filtration, after completion, unload to the dissolving kettle 14 for dissolution, then circulate through the filter 15 for 40 minutes, take a sample to observe whether there are impurities in the solution, after meeting the requirements, transfer the material through the filter 15 to the fine powder crystallization kettle 16, cool, and then discharge to the filter press 13 for pressing, after completion, put into storage and take samples for testing.

[0066] Example 2:

[0067] Please see Figure 1-15 A sodium methoxide preparation vessel for preparing fluorescent whitening agents, namely sodium methoxide preparation vessel 11, includes a motor 111, vessel body 112, stirring rod 113, stirring blade 114, shock absorber 115, shock absorber packing 116, temperature controller 117, and shock absorber drying assembly 118.

[0068] The motor 111 is installed above the vessel body 112. The vessel body 112 is divided into an upper cover and a vessel body. Several feed inlets and steam outlets are opened at the top of the upper cover. The upper cover and the vessel body are sealed together by a flange. The vessel body is divided into an inner layer and an outer layer. There is a certain space between the inner layer and the outer layer. The inner layer of the vessel body has a cavity. The lower part of the motor 111 is connected to and drives the stirring rod 113. The stirring rod 113 has stirring blades 114 in the middle and lower part.

[0069] Within the space between the inner and outer layers of the vessel body, a sealed partition is provided near the outer wall of the inner layer. A temperature controller 117 is installed within the partition. The partition is connected to the outside of the sodium methoxide preparation vessel 11 by an openable and closable channel. A shock-absorbing component 115 is provided between the partition and the outer layer of the vessel body. The shock-absorbing component 115 is a double-ringed structure, with a circumferentially distributed spring installed in the interlayer between the two layers to reduce the shaking amplitude of the vessel body during stirring. The space between the inner and outer layers at the bottom of the vessel body is filled with shock-absorbing filler 116 to buffer the shaking of the inner layer of the vessel body during high-speed stirring.

[0070] The vibration damping and drying assembly 118 is installed in the lower region of the sodium methoxide preparation vessel 11 and is located above the vibration damping packing 116. The vibration damping and drying assembly 118 includes a temperature control pipe 1181, a high-pressure self-tightening flange 1182, a temperature control pipe outer sleeve 1183, and a through-hole type vibration damper 1184. The upper part of the temperature control pipe 1181 forms a first annular pipe, and the lower part forms a second annular pipe parallel to the first annular pipe. The first annular pipe and the second annular pipe are connected by multiple vertically arranged connecting pipes in a regular distribution, forming a basket shape. Five inverted L-shaped pipes are connected to the top circumference of the temperature control pipe 1181. The L-shaped pipes are regularly distributed on the first ring pipe. Five straight pipes are connected horizontally outward from the bottom circumference. The straight pipes are composed of long straight pipes and short straight pipes. To achieve the shortest path distance, each pair of inverted L-shaped pipes and short straight pipes are located on the same central axis in the vertical direction. Each short straight pipe is connected to the long straight pipe through a high-pressure self-tightening flange 1182, which realizes and simplifies the installation and disassembly of the temperature control pipe 1181. The outermost channel of each inverted L-shaped pipe is fixed to the inner side of the inner layer of the vessel body through a flange and connects to the partition. The outermost end of each long straight pipe is connected to the outer side of the outer layer of the vessel body. The sealing between the long straight pipe and the inner layer of the vessel body is achieved by a flange.

[0071] The temperature control tube outer sleeve 1183 is annular, and five pipes with pipe expansion joints are distributed around the circumference of the temperature control tube outer sleeve 1183. Each pipe is fitted with a long straight pipe of the temperature control tube 1181. The inner side of the temperature control tube outer sleeve 1183 is connected to the outer side of the inner layer of the vessel body.

[0072] The through-hole type shock absorber 1184 is a double-layered ring with a spring distributed in a circle between the two layers. Several through holes are provided at the double-layered ring according to the distribution of the springs. These through holes are used to connect the pipes on the temperature control tube outer sleeve 1183. The outer side of the through-hole type shock absorber 1184 is connected to the inner side of the outer layer of the vessel body, and the inner side of the through-hole type shock absorber 1184 is located on the outer side of the temperature control tube outer sleeve 1183. A gap is left between the through-hole type shock absorber 1184 and the outer side of the temperature control tube outer sleeve 1183.

[0073] During use, the heat-conducting medium inside the temperature control tube 117 conducts heat energy to the interior of the vessel 112, which greatly accelerates the required drying time during drying. At the same time, it can quickly complete the evaporation of liquid at the bottom of the vessel cavity and avoid residue. This avoids the situation where sodium methoxide decomposes rapidly into methanol and sodium hydroxide when it comes into contact with water during actual operation, thus affecting the overall reaction effect of the technology.

[0074] The through-hole type vibration damper 1184, positioned between the inner and outer layers of the sodium methoxide preparation vessel 11, provides vibration damping and isolation for the inner layer of the vessel during reaction operations. Simultaneously, due to the gap between the temperature control tube outer sleeve 1183 and the through-hole type vibration damper 1184, the temperature control tube 1181 can still function normally even when the through-hole type vibration damper 1184 is subjected to external load spring expansion and contraction deformation.

[0075] Furthermore, the application scope of this sodium methoxide preparation vessel 11 can be extended to other reaction vessels as required by the production process.

[0076] Example 3:

[0077] Please see Figure 1-15 Based on Example 2, a sodium methoxide preparation vessel for preparing fluorescent whitening agents is used. The sodium methoxide preparation vessel 11 used is different from that in Example 2 in that the upper half of the temperature control tube 1181 is provided with two symmetrical detachable mounting guides 1185. The mounting guide 1185 is T-shaped, consisting of a longer side and a shorter side. The shorter side is a hollow channel and is nested to connect the temperature control tube 1181. There is a notch at one end of the longer side.

[0078] A mounting auxiliary component 1131 is provided at the lower part of the stirring rod 113. The mounting auxiliary component 1131 is in the shape of a through pipe, and an auxiliary block is provided on the outer wall. The auxiliary block is composed of a long block and a short block in an L shape. The long block and the short block form a right angle with the right angle opening facing upward. The long block forms an acute angle with the central axis of the stirring rod 113 with the opening facing upward. Thus, the auxiliary block forms an inclined angle relative to the stirring rod 113. The upper part of the long block is narrowed, and the narrowed width is less than the width of the notch on the mounting guide 1185. The inclined angle of the auxiliary block and the notch angle of the mounting guide 1185 are matched, and the notch can lock the auxiliary block.

[0079] In actual installation, due to the large volume of the sodium methoxide preparation vessel 11, the installation of the shock-absorbing drying assembly 118 requires the use of tools such as a crane. At this time, aligning each pipe opening with the appropriate through hole becomes quite tricky. To simplify this operation, the installation auxiliary component 1131 is used in conjunction with the installation guide component 1185. By using the notch on the installation guide component 1185, the shock-absorbing drying assembly 118 is lowered from the upper part of the auxiliary block of the installation auxiliary component 1131 along the track of the auxiliary block during the lowering of the crane. The lowest point is aligned with the through hole of the inner and outer layers of the vessel body 112. Since the width of the upper part of the auxiliary block is tightened, the notch can easily be engaged with the auxiliary block along the arc of the auxiliary block, thereby calibrating the position.

[0080] To maintain overall balance during descent and to minimize the rotation distance so that the notch on the mounting guide 1185 can engage with the auxiliary block on the mounting auxiliary component 1131, two mounting guides 1185 are symmetrically arranged.

[0081] In addition, after installation is completed, remove the installation guide 1185 and installation auxiliary component 1131, and then continue to install the stirring blade 114.

[0082] Example 4:

[0083] Please see Figure 1-15 A method for preparing a fluorescent whitening agent includes the following steps.

[0084] 1. Prenatal preparation

[0085] 1.1 Determine whether the raw materials required for production, such as triethyl phosphite (2930 kg), biphenyl dichlorobenzyl (2000 kg), sodium o-sulfonate benzaldehyde (3820 kg), recovered DMF / new DMF (13500 kg), solid sodium methoxide (1150 kg), concentrated sulfuric acid (125 kg), industrial salt (600 kg), and filter aid (20 kg), are sufficient;

[0086] 1.2 Weigh 3000 kg (weighing module display switch DCS interlock) of triethyl phosphite;

[0087] 1.3 Open the feed valve of the intermediate tank of triethyl phosphite, open the feed pump of triethyl phosphite (the feed pump and the intermediate tank are interlocked by the DCS for high and low liquid levels, with high liquid level alarm and shut-off) and the discharge valve of the triethyl phosphite storage tank in the tank area.

[0088] 1.4 Standard quantities of triethyl phosphite were pumped from the triethyl phosphite storage tank in the tank area into the intermediate triethyl phosphite tank.

[0089] After 1.5 is completed, the discharge valve of the triethyl phosphite storage tank, the feed valve of the intermediate triethyl phosphite tank, and the triethyl phosphite feeding pump are installed in sequence.

[0090] 2 Feeding

[0091] 2.1 Check and fully open the circulating water outlet and inlet valves of the condenser on the esterification vessel;

[0092] 2.2 Open the feeding valve of the esterification reactor, use a crane to lift the biphenyl dichlorobenzyl, move it above the feeding hopper of the esterification reactor, activate the vibration transmission alarm device of the feeding hopper, untie the bottom strap of the packaging, and add 2000 kg of biphenyl dichlorobenzyl into the esterification reactor. Purge the remaining material in the feeding hopper with nitrogen. Fold up the packaging bag, pack it, and place it in the packaging bag placement area, ensuring proper "5S" on-site management.

[0093] 2.3 Open the nitrogen inlet valve to purge the esterification reactor. After purging, operate the DCS to open the waste gas absorption valve of the gas-liquid separator, open the circulation return valve and the return valve to the reactor, close the triethyl phosphite recovery valve of the esterification reactor, fully open the triethyl phosphite feed valve of the esterification reactor and the manual valve and flow valve of the triethyl phosphite intermediate tank, start the triethyl phosphite pump, and pump 980 kg (weighing module display switch DCS interlock) of triethyl phosphite into the esterification reactor. When the weight display of the triethyl phosphite intermediate tank is 2150 kg (weighing module display switch DCS interlock), the DCS interlock automatically shuts off the triethyl phosphite pump and the triethyl phosphite feed valve of the esterification reactor.

[0094] 3 liters

[0095] 3.1 After the biphenyl dichlorobenzyl is fed, open the nitrogen inlet valve to purge and replace the esterification vessel. The DCS interlock opens the condensate drain valve and the steam valve to drain the circulating water in the jacket. The DCS interlock automatically closes the drain valve. Adjust the jacket steam inlet valve to 70%, raise the temperature to 105℃, close the steam valve, allow the temperature to rise naturally, turn on the stirrer and adjust the speed to 30%, stir for 10 minutes (observe the material dissolution: if there is a lot of undissolved material around the reactor, maintain the speed and continue stirring for 5 minutes), then adjust the speed to 70%.

[0096] 3.2 After the agitator is started, the temperature will drop. The DCS interlock will automatically open the jacket steam inlet valve by 50% to raise the temperature to 100±2℃. Then the DCS interlock will close the steam inlet valve.

[0097] 4 drops added

[0098] 4.1 The temperature is naturally raised to 135±5℃. The DCS interlock automatically opens the triethyl phosphite feed valve of the esterification vessel and the triethyl phosphite pump, and drips in the remaining 1950kg (weighing module display switch DCS interlock) of triethyl phosphite, controlling the temperature at 135±5℃ for reflux (controlled by the DCS interlock of the vessel temperature, steam inlet valve and steam outlet).

[0099] 5-liter heat preservation

[0100] 5.1 After the addition is complete, the DCS interlock automatically closes the feed valve of triethyl phosphite in the esterification reactor and the feed valve of the intermediate tank of triethyl phosphite. When the temperature continues to rise, the DCS interlock automatically opens the jacket steam inlet valve to 35%. When the temperature drops, the jacket steam inlet valve opens to 70%. When the temperature rises to 140±2℃, the DCS interlock automatically closes the jacket steam inlet valve, adjusts the speed to 93%, and allows the temperature to rise naturally to 160±5℃ for heat preservation and reflux for 4 hours.

[0101] 6. Distillation

[0102] 6.1 After the heat preservation is completed, the DCS interlock automatically closes the circulation reflux valve and the reflux return valve, and the DCS interlock starts the triethyl phosphite vacuum recovery system (first close the vent valve of the triethyl phosphite recovery receiving tank, then open the vacuum pump vacuum valve, and finally open the triethyl phosphite recovery valve of the esterification kettle) to recover triethyl phosphite.

[0103] 6.2 When the negative pressure reaches -90KPa, the temperature is controlled at 160±5℃ (the opening of the jacket steam inlet valve is automatically adjusted according to the steam pressure and temperature during the process to maintain the temperature at 160±5℃), and the negative pressure is -92-100KPa;

[0104] 6.3 After recovering triethyl phosphite until there is no liquid backflow in the sight glass (3 hours), close the triethyl phosphite recovery valve. The DCS interlock automatically closes the jacket steam inlet valve and stops stirring. The DCS interlock automatically opens the waste gas valve on the gas-liquid separator. Sampling is performed through the sampling port of the esterification reactor. The extracted esterified sample is in liquid form. Pour it into a stainless steel tray to cool. After the sample cools and solidifies, send the sample (about 30g) to the testing center for gas phase content detection. Close the sampling port after sampling is completed.

[0105] 6.4 Sample and test the content of type V esters. If the content is ≥97%, discharge the material into the first condensation reactor when the temperature is reduced to 125±2℃.

[0106] 7 Feeding

[0107] 7.1 Place 8000 kg (weighing module display switch DCS interlock) of recycled DMF / newly purchased DMF into the preparation vessel, open the feeding hopper valve of the preparation vessel, use a crane to lift sodium o-sulfonate benzaldehyde, move it above the feeding hopper of the condensation vessel, turn on the vibration transmission alarm device of the feeding hopper, open the bottom tie of the packaging, and put 3820 kg (if the content is less than 95%, quantitative replenishment is required) of sodium o-sulfonate benzaldehyde into the first condensation vessel. Turn on the stirring until the material is completely dissolved, circulate and clean it through the filter, confirm that the second condensation vessel is clean and the bottom valve is closed, and then filter it through the precision filter into the second condensation vessel;

[0108] 7.2 Check whether the sodium methoxide preparation vessel has reached a dry and clean state and whether the bottom valve is closed; open the vent valve and switch the DMF feed valve on the vessel to 4000kg (weighing module display switch DCS interlock) to recover DMF / newly purchased DMF, turn on the vibration conveyor alarm device of the feeding hopper, and put a total of 1150kg of solid sodium methoxide into the sodium methoxide preparation vessel through the feeding hopper.

[0109] 8. Feeding

[0110] 8.1 Using DCS operation, first drain the condensate from the discharge pipe jacket, then open the discharge pipe jacket for steam preheating for 15 minutes (adjust the preheating time to 30 minutes in winter);

[0111] 8.2 Open the bottom valve of the esterification reactor using the DCS interlock, and put all the synthesized type 5 ester into the second condensation reactor. After the ester is put in, let it flow by gravity for 3-5 minutes.

[0112] 8.3 If the temperature of the second condensation vessel is greater than 47°C, the chilled brine inlet valve is opened via DCS interlock to cool it down to 45±2°C;

[0113] 9. Cooling the reactor

[0114] 9.1 Open the circulating water outlet valve and inlet valve of the esterification reactor jacket via DCS interlock, and close the circulating water inlet valve when the reactor temperature drops to 125±2℃.

[0115] 10. Collect and weigh the recovered triethyl phosphite.

[0116] 10.1 After checking that the electrostatic bridging is intact and recording the liquid level, the DCS interlock is activated to start the triethyl phosphite recovery pump to release the recovered triethyl phosphite from the triethyl phosphite recovery receiving tank into a barrel. Samples are taken and sent for testing. The barrel lid is then tightened, the weight is recorded, and the barrel is stored in a designated storage area.

[0117] 11 drops of solid sodium methoxide were added.

[0118] 11.1 When the temperature of the material in the second condensation kettle drops to 45±2℃, the DCS interlock automatically closes the waste gas absorption valve, opens the negative pressure methanol recovery system, and automatically opens the solid sodium methoxide dripping flow valve through the DCS interlock to start dripping solid sodium methoxide. The reaction temperature of the second condensation kettle and the frequency of the sodium methoxide transfer pump in the kettle are interlocked by the DCS to control the temperature of the reaction liquid at 45±2℃.

[0119] 11.2 During the dropwise addition process, attention should be paid to the weight inside the sodium methoxide preparation vessel (R1313). When the weight inside the sodium methoxide preparation vessel reaches 1020.8 kg, the DCS interlock should be used to shut down the stirring of the sodium methoxide preparation vessel.

[0120] 11.3 After the solid sodium methoxide has finished dripping, open the DMF feed valve on the sodium methoxide preparation vessel and turn the liquid level to 200kg. Use the recovered DMF / newly purchased DMF to flush the pipeline inside the sodium methoxide preparation vessel. After flushing, close the bottom valve of the sodium methoxide preparation vessel and the solid sodium methoxide dripping valve through the DCS interlock. After the dripping is completed, allow the temperature to rise naturally to 50±3℃ and keep it warm. The entire dripping process takes 3 hours.

[0121] 12 Insulation

[0122] 12.1 After the addition is complete, keep the temperature at 50±3℃ for 6 hours. After the temperature is maintained, turn off the stirring in the second condensation vessel.

[0123] 13 transfer materials

[0124] 13.1 Check whether the distillation vessel is dry and clean. After meeting the requirements, the DCS interlock sequentially opens the feed valve on the distillation vessel and the discharge valve of the second condensation vessel, and starts the transfer pump of the second condensation vessel to transfer the material. After manually confirming that the transfer is completed, add 800kg DMF to flush the pipeline. The DCS interlock sequentially closes the transfer pump of the second condensation vessel, the discharge valve of the second condensation vessel, and the feed valve on the distillation vessel.

[0125] 14 Steamed DMF

[0126] 14.1 After quantitatively adding concentrated sulfuric acid into the distillation kettle, sequentially open the circulating water inlet valve of the condenser on the distillation stripping section, close the water inlet valve and waste gas valve of the distillation kettle jacket, open the waste gas valve on the DMF low-boiling receiving tank, turn on the vacuum pump to create a vacuum, and open the vacuum valve on the distillation kettle. When the vacuum gauge on the distillation kettle shows a vacuum degree ≥ 0.060 MPa, adjust the stirring frequency to 50%, open the steam valve to 100%, set the coil steam pressure to 0.3 MPa, and start heating. Control the temperature at 70-80℃. When the vacuum gauge on the distillation kettle shows a vacuum degree ≥ 0.080 MPa, maintain the stirring frequency at 100% and keep stirring for 1.5-2 hours.

[0127] 14.2 When the DMF low-boiling-point receiving tank level rises slowly, after the reflux through the sight glass of the recovery pipe decreases, open the steam valve to 40%, set the coil steam pressure to 0.45 MPa, continue heating, and control the temperature at 90-100℃. Maintain stirring for 40-60 minutes. Open the steam inlet valve of the inner coil of the distillation vessel to 50%, and fully open the outer coil steam inlet valve. Maintain the coil steam pressure to 0.5 MPa and continue heating. When the temperature reaches 120℃, continue recovery for 10 minutes. The DCS interlock starts the feed valve of the DMF high-boiling-point receiving tank and the DMF high-boiling-point receiving liquid pump. When the temperature reaches 130℃, maintain the stirring frequency at 100%, control the secondary condensate discharge temperature to ≤40℃, maintain stirring for 60 minutes, and fully open the steam inlet valve of the inner coil of the distillation vessel. When the vacuum degree is ≥0.090MPa, maintain stirring for 2.5-3 hours until the frequency-controlled stirring load is too high and an alarm is triggered. When the first audible alarm is triggered, adjust the stirring frequency to 80%. When the second audible alarm is triggered, the vacuum degree is ≥0.092MPa, and the stirring frequency is adjusted to 60%. When the third audible alarm is triggered, the vacuum degree is ≥0.094MPa, and the stirring frequency is adjusted to 40%. When the fourth audible alarm is triggered, the vacuum degree is ≥0.096MPa, and the stirring frequency is adjusted to 30%. DMF distillation ends. Record the DMF level for this recovery. The distilled low-boiling DMF mother liquor is pumped from the low-boiling DMF receiving tank to the mother liquor storage tank in the solvent recovery workshop for DMF recovery. The distilled high-boiling DMF is reused.

[0128] 15 distilled water

[0129] 15.1 After DMF distillation is complete, close the DMF recovery valve sequentially, open the jacketed water / tap water inlet valve, add 3000 kg of jacketed water to the distillation vessel, stir and disperse for 5-10 minutes, adjust the steam valve to 100%, adjust the stirring frequency to 100%, open the vent valve of the recovery water receiving tank, open the recovery water inlet valve, and turn on the DMF aqueous solution pump. The material in the distillation vessel will heat up; closely monitor the changes in the material's state inside the vessel, and perform negative pressure distillation to distill off 3000 kg of water. Then, open the jacketed water / tap water inlet valve and add 2000 kg of jacketed water. Add g to the distillation kettle, stir and disperse for 5-10 minutes, adjust the steam valve to 100%, adjust the stirring frequency to 100%, open the vent valve of the recovery water receiving tank, open the recovery water inlet valve, and activate the DMF aqueous solution pump. The material in the distillation kettle will heat up. Closely monitor the changes in the state of the material inside the kettle and perform negative pressure distillation to distill 2000 kg of water. After the water distillation is complete, close the steam inlet valve, turn off the vacuum pump, close the vacuum gas phase outlet valve, open the direct steam to break the vacuum inside the kettle, and close the direct steam inlet valve after the kettle reaches normal pressure. Open the vent valve of the distillation kettle to end the water distillation.

[0130] 16 transfer materials

[0131] 16.1 Open the inlet valve for the jacket water / tap water, add 9000 kg of jacket water to the distillation kettle, adjust the steam valve to 100%, adjust the stirring frequency to 100%, turn on the steam to heat up, and when the temperature rises to 70-75℃, completely close the steam valve and let it heat up naturally to 80℃ and stir well.

[0132] 16.2 Open the feed valve of the coarse powder crystallizer, the bottom valve of the distillation vessel, and the transfer pump to transfer the material. After the transfer is completed, open the inlet valve of the jacket water / tap water and add 800 kg of jacket water to the distillation vessel to flush the pipeline. After flushing the pipeline, close the transfer pump, the feed valve of the coarse powder crystallizer, and the bottom valve of the distillation vessel. Use the residual heat to dry the vessel and wait for the next batch of material to be added.

[0133] 17 early cold

[0134] 17.1 After the flushing of the pipeline is completed, close the feed valve of the coarse powder crystallizer. After the material transfer is completed, turn on the agitator of the coarse powder crystallizer and turn on the circulating water inlet valve of the coarse powder crystallizer to cool down. When the temperature drops to 45±5℃.

[0135] 18 Cryogenic

[0136] 18.1 Add 600 kg of industrial salt to the coarse powder crystallization kettle, open the inlet valve of the chilled brine to cool down to 9±1℃, close the inlet and outlet valves of the chilled brine, turn off the stirring of the coarse powder crystallization kettle, and start the coarse powder pressure filtration.

[0137] 19 Coarse powder filter press

[0138] 19.1 Open the filter press and clean the accumulated material on the plates, frames, and filter cloth. Manually arrange the filter plates to ensure that each filter plate is aligned with the head of the filter press and that the plates are tightly packed together. Open the drain valve on the diaphragm plate, turn on the pressing button, and press the filter press. Control the pressure range between 18 MPa and 20 MPa. Open the feed valve of the filter press, open the bottom valve of the coarse powder crystallization vessel, and turn on the transfer pump to feed the material (during the feeding process, check for any leakage between the filter cloths. If any leakage is found, immediately turn off the transfer pump and the bottom valve of the coarse powder crystallization vessel, stop the filter press, check and rearrange the filter plates, and then resume the filter press).

[0139] 19.2 After the liquid level in the bottom floor filtrate receiving tank is 2 / 3 full, turn on the coarse powder filtrate pump to pump the coarse filtrate into the large tank (230m3 tank). Open the manhole cover to observe whether the material in the kettle has been completely pressed. If the material has not been completely pressed and cannot be pressed in, turn off the transfer pump, the bottom valve of the coarse powder crystallization kettle, and the feed valve of the filter press. Water press for 10 minutes, then stop water pressing. Turn on the feed valve of the filter press, the bottom valve of the coarse powder crystallization kettle, and the transfer pump again to continue pressing. After the material has been pressed, turn off the transfer pump, the bottom valve of the coarse powder crystallization kettle, the feed valve of the filter press, and close the diaphragm plate drain valve in sequence.

[0140] 19.3 Add water to the pressing tank until the liquid level reaches the tank level mark. Turn on the multi-section pump and adjust the water pressure to 0.6-0.8 MPa. Press for 30-40 minutes. After pressing, turn off the multi-section pump in sequence, open the diaphragm plate drain valve, drain the water, and then release the plate to the limit position to unload the material.

[0141] 20 Discharge Dissolution

[0142] 20.1 After checking that the dissolving vessel is clean and free of impurities and meets the requirements, close the bottom valve of the dissolving vessel, open the connecting valve, add 5400 kg of water, open the direct steam inlet valve, start stirring, and when the temperature rises to 60-70℃, loosen the filter press, start the conveyor belt to unload the material, and control the unloading time to 20-25 minutes.

[0143] 20.2 After unloading is completed, turn off the conveyor belts sequentially, cover the vessel, and continue heating until it reaches 80-85℃. Then, close the steam inlet valve and observe the changes in the state of the material inside the vessel. The temperature will naturally rise to 93-97℃.

[0144] 20.3 Once the material in the reactor is completely dissolved (if the material cannot be completely dissolved, a measured amount of water can be added), transfer the material to the circulating reactor one and start circulating filtration.

[0145] 21-cycle filtration

[0146] 21.1 Check that both filters are in good working order (filter plates and sealing rings are intact), the filter plate openings and slots are securely fixed without any looseness, cover the covers, tighten the lifting eye bolts, preheat with steam for 10-15 minutes, then open the circulation return valve, the bottom valve of the circulation vessel, and the high-temperature pump outlet valve in sequence, and start the high-temperature pump for circulation filtration (the filter pressure should be controlled ≤0.4Mpa; if the pressure exceeds this range, close the bottom valve, the high-temperature pump and the pump outlet in sequence, stop the operation, check and reinstall the filter plates).

[0147] 21.2 Circulate the filter for 40 minutes, take a sample of about 500 ml in a 1000 ml beaker, and observe whether there are impurities in the solution. If it meets the requirements, close the bottom valve, open the feed valve of the fine powder crystallizer, open the discharge valve of the precision filter, open the feed valve of the precision filter, and close the first valve of the circulation vessel after the material fills the precision filter for 2-3 minutes.

[0148] 21.3 Start the agitator in the fine powder crystallization kettle and filter it. Open the circulating water inlet valve to cool it down. Observe the changes in the material inside the kettle through the sight glass on the upper part of the circulating kettle. When the material is almost completely filtered, transfer the material in the dissolving kettle to the circulating kettle. Open the valve of the circulating kettle and close the feed valve of the fine powder crystallization kettle. Switch back to the circulating kettle for circulation. Clean the filter once for the entire kettle.

[0149] 22 Cooling

[0150] 22.1 When the material in the fine powder crystallizer cools down to 45±5℃, open the brine jacket outlet valve of the cryogenic reactor and open the brine inlet valve of the fine powder crystallizer to start cooling down to 14±1℃ and start pressing.

[0151] 23 Fine Powder Filter Press

[0152] 23.1 Open the filter press and clean the accumulated material on the plates, frames, and filter cloths. Manually arrange the filter plates to ensure they are aligned longitudinally and transversely towards the press head and tightly packed. Open the drain valve on the diaphragm plate, turn on the clamping button, and press the filter press firmly. Control the pressure range to 18 MPa to 20 MPa. Open the filter press feed valve, then sequentially open the bottom valve of the fine powder crystallization kettle. Start the transfer pump to feed the material (during feeding, check for any leakage between the filter cloths; if leakage occurs, immediately close the transfer pump and the bottom valve of the fine powder crystallization kettle, stop the filter press, check and rearrange the filter plates, and then resume the filter press). When the liquid level in the bottom jacket water receiving tank is half full, turn on the jacket water pump to pump the jacket water into the jacket water tank. Open the kettle cover to observe whether the material inside the kettle is under pressure. If the material is not fully pressed and cannot be pressed further, close the transfer pump, the bottom valve of the fine powder crystallization kettle, and the feed valve of the filter press. Water press for 10 minutes, then stop. Reopen the feed valve of the filter press, the bottom valve of the fine powder crystallization kettle, and the transfer pump to continue pressing. After the material is fully pressed, close the transfer pump, the bottom valve of the fine powder crystallization kettle, and the feed valve of the filter press in sequence, and close the diaphragm drain valve. Add water to the pressing tank until the liquid level reaches the tank's fixed level mark. Start the multi-section pump and adjust the water pressure to 0.6-0.8 MPa. Water press for 30-40 minutes. After water pressing is complete, close the multi-section pump in sequence, open the diaphragm drain valve, drain the water, and release the plate to the limit position to unload the material. Pour the filtrate from the secondary filtration into the refrigerant storage tank, waiting for the next batch to be used.

[0153] 24. Completed work, warehousing, and sampling for testing

[0154] 24.1 Unload the filter cake, bag it, weigh it, cover it with a cloth, and use a hydraulic cart to pull it to the designated location (take the filter cake from the upper left corner of plate 31-31 of the filter press). Fill in the batch number, weight, time and work group on the material identification card, and put it into the warehouse after completion.

[0155] Preparation of 25 barite filter cake (single-reactor calculation)

[0156] 25.1 Add 1000kg of water and 20kg of filter aid to the second circulating vessel, heat to 70℃ and circulate for 25-30 minutes to the second reaction vessel. The filter layer is now complete.

[0157] 25.2 Add 3000 kg of water and 2800 kg of No. 14 filter cake to the second circulating vessel. Open the steam inlet valve, start stirring, and when the temperature reaches 95℃, observe the change in the state of the material in the vessel. When the material in the vessel is completely dissolved and transparent, keep it at this temperature for 30 minutes, and then start circulating filtration.

[0158] 25.3 Circulate the filter for 40 minutes. Take a sample of about 500 ml in a 1000 ml beaker and observe whether there are impurities in the solution. If the impurities are not up to standard, disassemble and clean the filter and reinstall the filter plate. If it is up to standard, you can proceed with filtration. Check whether the crystallization vessel is clean and free of impurities. After meeting the requirements, close the bottom valve, open the crystallization vessel feed valve, open the precision filter discharge valve, and open the precision filter feed valve. After the material fills the precision filter for 2-3 minutes, close the second valve of the circulation vessel.

[0159] 25.4 Start the crystallizer stirring and filter, open the circulating water inlet valve for cooling; observe the material changes in the reactor through the sight glass of the second circulating reactor. When the material is almost completely filtered, add 4000 kg of water, open the circulation valve of the second circulating reactor, close the feed valve of the first circulating reactor, switch back to the second circulating reactor for circulation, and clean the filter once for the entire reactor.

[0160] 25.5 When the material in the crystallizer cools down to 45±5℃, close the circulating water inlet and outlet valves and open the crystallizer chilled brine inlet valve to start cooling down to 15±1℃;

[0161] 25.6 Turn on the filter press clamping button to tighten the filter press, controlling the pressure range between 18 MPa and 20 MPa. Open the filter press feed valve, then open the crystallization vessel bottom valve in sequence, and start the transfer pump to feed the material (during the feeding process, check for any leakage between the filter cloths; if any leakage is found, immediately close the feed valve, transfer pump, and crystallization vessel bottom valve, stop the filter press, check and adjust the filter plates, and then resume the filter press). When the liquid level in the bottom jacket water receiving tank is half full, turn on the jacket water pump to pump the jacket water into the large tank. Open the manhole cover to observe whether the material in the vessel has been completely pressed. After the material has been pressed, close the transfer pump, crystallization vessel bottom valve, and filter press feed valve in sequence, and close the diaphragm plate drain valve. Turn on the multi-section pump, adjust the water pressure to 0.6–0.8 MPa, and water press for 30–40 minutes. After water pressing is completed, close the multi-section pump in sequence, open the diaphragm plate drain valve, drain the water, loosen the plate to the limit position, and discharge the material. Pack the filter cake into bags and weigh it.

Claims

1. A sodium methoxide preparation vessel for preparing fluorescent whitening agents, characterized in that: The sodium methoxide preparation vessel (11) is equipped with a shock-absorbing and drying assembly (118), which includes a temperature control tube (1181), a temperature control tube jacket (1183), and a through-hole shock absorber (1184). The upper part of the temperature control tube (1181) forms a first annular pipe, and the lower part forms a second annular pipe parallel to the first annular pipe. The first annular pipe and the second annular pipe are connected by multiple vertically arranged connecting pipes in a regular distribution, forming a basket shape as a whole. The sodium methoxide preparation kettle includes a kettle body, which is divided into a top cover and a kettle body. The kettle body is divided into an inner layer and an outer layer, and there is a certain space between the inner layer and the outer layer. The temperature control tube (1181) has several inverted L-shaped pipes extending upward from its top circumference, which are regularly distributed on the first annular pipe. The temperature control tube (1181) has several straight pipes extending outward horizontally from its bottom circumference. The temperature control tube outer sleeve (1183) is annular and has several pipes with expansion joints distributed outward. Each pipe with an expansion joint is fitted onto the straight pipe on the temperature control tube (1181). The through-hole type shock absorber (1184) is a double-layered annular structure. Springs are installed in a circular pattern between the annular layers, and several through holes are provided according to the distribution of the springs to fit onto the temperature control tube outer sleeve (1183). The outer side of the through-hole type shock absorber (1184) is connected to the inner side of the outer layer of the vessel body. The inner side of the through-hole type shock absorber (1184) is located on the outer side of the temperature control tube outer sleeve (1183), and there is a gap between the through-hole type shock absorber (1184) and the outer side of the temperature control tube outer sleeve (1183).

2. The sodium methoxide preparation vessel for preparing fluorescent whitening agents according to claim 1, characterized in that: The sodium methoxide preparation vessel (11) also includes a motor (111), a stirring rod (113), stirring blades (114), a shock absorber (115), a shock absorber packing (116), and a temperature controller (117). The motor (111) is installed above the vessel body (112). The top of the cover has several feed inlets and steam outlets. The cover and the vessel body are sealed together by a flange. The vessel body is hollow inside. The lower half of the motor (111) is connected to and drives the stirring rod (113). The stirring rod (113) has stirring blades (114) in the middle and lower part. A sealed partition is provided in the space between the inner and outer layers of the vessel body near the outer wall of the inner layer. The partition is used to install a temperature controller (117). The partition is connected to the outer wall of the sodium methoxide preparation vessel (11) through an openable / closeable channel. A shock absorber (115) is provided between the partition and the outer layer of the vessel body. The shock absorber (115) is a double-ringed structure. A spring distributed in a circular pattern is installed in the interlayer between the two layers. The space between the inner and outer layers at the bottom of the vessel body is filled with shock absorber filler (116).

3. The sodium methoxide preparation vessel for preparing fluorescent whitening agents according to claim 2, characterized in that: It also includes a high-pressure self-tightening flange (1182); the vibration damping and drying assembly (118) is installed in the lower region of the sodium methoxide preparation vessel (11) and is located on the upper side of the vibration damping packing (116). The straight pipe is composed of a long straight pipe and a short straight pipe. Each pair of the inverted L-shaped pipes and the short straight pipes are located on the same central axis in the vertical direction. Each of the short straight pipes is connected to the long straight pipe through the high-pressure self-tightening flange (1182). The outermost channel of each of the inverted L-shaped pipes is fixed to the inner side of the inner layer of the vessel body through a flange and is connected to the partition. The outermost end of each of the long straight pipes is connected to the outer side of the outer layer of the vessel body. The sealing between the long straight pipe and the inner layer of the vessel body is achieved by a flange. The inner side of the temperature control pipe jacket (1183) is connected to the outer side of the inner layer of the vessel body.

4. The sodium methoxide preparation vessel for preparing fluorescent whitening agents according to claim 2, characterized in that: The upper half of the temperature control tube (1181) is provided with two symmetrical detachable mounting guides (1185). The mounting guide (1185) is composed of a longer side and a shorter side, and is T-shaped. The shorter side is a hollow channel and is nested to connect the temperature control tube (1181). One end of the longer side is provided with a notch. The lower part of the stirring rod (113) is provided with an installation auxiliary component (1131). The installation auxiliary component (1131) is a through tube and has an auxiliary block on its outer wall. The auxiliary block is composed of a long block and a short block, which are L-shaped and form a right angle with the right angle opening facing upward. The long block and the central axis of the stirring rod (113) form an acute angle with the opening facing upward, so that the auxiliary block forms an inclined angle relative to the stirring rod (113). The upper part of the long block is narrowed, and the narrowed width is less than the width of the notch on the installation guide (1185). The inclined angle of the auxiliary block and the notch angle of the installation guide (1185) match, so that the notch engages with the auxiliary block.

5. A system for preparing a fluorescent whitening agent, characterized in that: The apparatus includes the sodium methoxide preparation vessel as described in claim 1, and further includes an esterification vessel (1), a triethyl phosphite receiving tank (2), a preparation vessel (3), a first condensation vessel (4), a precision filter (5), a second condensation vessel (6), a distillation vessel (7), a recycled water receiving tank (8), a DMF low-boiling receiving tank (9), a DMF high-boiling receiving tank (10), a coarse powder crystallization vessel (12), a filter press (13), a dissolving vessel (14), a filter (15), and a fine powder crystallization vessel (16). The two outlets of the esterification vessel (1) are respectively connected to the inlet of the triethyl phosphite receiving tank (2) and the inlet of the second condensation vessel (6); The two outlets of the preparation vessel (3) are respectively connected to the inlet of the first condensation vessel (4) and the inlet of the sodium methoxide preparation vessel (11). The outlet of the first condensation vessel (4), the precision filter (5), and one of the inlets of the second condensation vessel (6) are connected in sequence. At the same time, the outlet of the sodium methoxide preparation vessel (11) is connected to the other inlet of the second condensation vessel (6). The outlet of the second condensation vessel (6) is connected to the inlet of the distillation vessel (7). The four outlets of the distillation vessel (7) are respectively connected to the inlet of the recovery water receiving tank (8), the inlet of the DMF low-boiling receiving tank (9), and the DMF low-boiling receiving tank (9). The inlet of the MF high-boiling receiving tank (10) and the inlet of the coarse powder crystallizer (12) are connected. The outlet of the coarse powder crystallizer (12) is connected to one of the inlets of the filter press (13). The outlet of the filter press (13) is connected to the inlet of the dissolving tank (14). The outlet of the dissolving tank (14) is connected to the filter (15). The filter (15) is connected to the inlet of the fine powder crystallizer (16). At the same time, the outlet of the fine powder crystallizer (16) is connected to the other inlet of the filter press (13). The filter press (13), the dissolving tank (14), the filter (15) and the fine powder crystallizer (16) form a loop.

6. The preparation system for the fluorescent whitening agent according to claim 5, characterized in that: The esterification vessel (1) is also equipped with a biphenyl dichlorobenzyl inlet, a triethyl phosphite inlet, a nitrogen inlet, a sampling port, and a type 5 ester outlet. The triethyl phosphite receiving tank (2) is equipped with a triethyl phosphite outlet. The preparation vessel (3) is equipped with a DMF inlet. The first condensation vessel (4) is equipped with an o-sulfonate benzaldehyde inlet. The sodium methoxide preparation vessel (11) is equipped with a solid sodium methoxide inlet. The second condensation vessel (6) is equipped with a type 5 ester inlet, which is connected to the type 5 ester outlet on the esterification vessel (1). The distillation vessel (7) is equipped with a concentrated sulfuric acid inlet and a water / tap water inlet. The coarse powder crystallization vessel (12) is equipped with an industrial salt inlet. The dissolving vessel (14) is equipped with a water inlet. The feeding and discharging are controlled by a DCS interlocking device.

7. A method for preparing a fluorescent whitening agent, using the fluorescent whitening agent preparation system described in claim 5, the preparation method comprising the following steps: The first step involves adding biphenyl dichlorobenzyl and a portion of triethyl phosphite to an esterification reactor. Under nitrogen atmosphere, the reactor is heated and maintained at 98-102°C while stirring to dissolve the material. The remaining triethyl phosphite is then added dropwise while the temperature is controlled at 130-140°C and refluxed. After the addition is complete, the temperature is naturally raised to 155-165°C and refluxed to recover the triethyl phosphite, yielding the esterified product. The second step involves stirring and filtering DMF and sodium o-sulfonate benzaldehyde, adding the esterified product obtained in the first step, adding sodium methoxide dropwise while stirring, and then maintaining the temperature at 47-53℃ after the addition is complete. The third step involves adding concentrated sulfuric acid to the material obtained in the previous step, stirring and heating it to 70-80℃ and then distilling it to recover DMF. Water is added and the mixture is stirred and dispersed for 5-10 minutes. The mixture is then distilled under negative pressure. After completion, the mixture is stirred and cooled to 40-50℃. Industrial salt is added and the temperature is lowered to 8-10℃. Stirring is stopped, and coarse powder is filtered, unloaded and dissolved, circulated and filtered, cooled, and fine powder is filtered.

8. The method for preparing a fluorescent whitening agent according to claim 7, characterized in that: In the first step, the ratio of the two additions of triethyl phosphite is 1:

2.

9. The method for preparing a fluorescent whitening agent according to claim 7, characterized in that: In the first step, the content of type 5 esters in the esterified product is ≥97%.

10. The method for preparing a fluorescent whitening agent according to claim 7, characterized in that: The time for stirring, heating, and distillation in the third step is 1.5-5 hours.

Images