A solid polycarboxylate superplasticizer preparation system and preparation method

Abstract

A solid polycarboxylate superplasticizer preparation system and method are disclosed, belonging to the technical field of concrete superplasticizer component preparation. The solid polycarboxylate superplasticizer preparation system includes a polyether reaction device, a polycarboxylate mother liquor concentration device, and a flake machine. The polyether reaction device is connected to the polycarboxylate mother liquor concentration device and a low-temperature water device via a heat recovery device. The polycarboxylate mother liquor concentration device is connected to the material inlet of the flake machine, and the low-temperature water device is connected to the low-temperature water inlet of the flake machine. The beneficial effect of this invention is that it can fully utilize the surplus hot water from the polyether reaction heat recovery system as a heat source for the solidification of the polycarboxylate superplasticizer mother liquor, preparing the polycarboxylate superplasticizer mother liquor into solid polycarboxylate, thus reducing energy consumption and improving product quality.

Description

Technical Field

[0001] This invention relates to the field of concrete water-reducing agent component preparation technology, and in particular to a solid polycarboxylate water-reducing agent preparation system and preparation method. Background Technology

[0002] Solid polycarboxylate superplasticizer (SPC) is a commonly used admixture in dry-mix mortar, cement-based grouting materials, and shotcrete. It can be directly mixed and packaged with various powder materials. Before use, SPC is in a physically mixed state; its performance is effectively released upon adding water. SPC mother liquor is typically produced through free radical polymerization of aqueous solution, resulting in an aqueous solution with a solids content of 40%–50%. SPC mother liquor is widely used in high-strength, high-performance concrete, ready-mixed concrete, commercial concrete, and high-flowability concrete. However, the high transportation costs due to the need for specialized transport vehicles and the low solids content of the aqueous solution limit its sales reach.

[0003] Polycarboxylate superplasticizer mother liquor is typically obtained by copolymerizing polyether macromonomers with unsaturated monomers such as acrylic acid and hydroxyethyl acrylate. The polyether macromonomers are obtained through anionic stepwise addition polymerization with ethylene oxide, using alkenyl alcohol as an initiator and alkali as a catalyst. The production of polyether macromonomers is a highly exothermic reaction process; ethylene oxide releases 2140 kJ / kg of heat during ring opening. To maintain the reaction temperature, the heat of reaction needs to be removed from the reaction system promptly. Traditional polyether reactors employ a two-stage heat exchange system. The first-stage system uses hot water as a medium to exchange heat with the reactants via an external circulating heat exchanger. The second-stage system uses circulating cooling water as a medium to exchange heat with the hot water system of the first-stage system via a plate heat exchanger. The hot water system, combined with the lithium bromide chiller, forms a low-temperature water system. This system uses hot water to prepare low-temperature water at 7°C–12°C for use as a cooling source in polyether sheet formation. However, less than 50% of the hot water is used to prepare the low-temperature water; a significant amount of reaction heat is carried away by the circulating cooling water, resulting in inefficient utilization of the reaction heat. Furthermore, because the polyether reaction is intermittent, the heat released is also intermittent, posing challenges to heat recovery.

[0004] Patent CN115449022A discloses a method for preparing a high water-reducing powdered polycarboxylate superplasticizer. The method involves removing moisture from the polycarboxylate mother liquor obtained by aqueous solution polymerization through spray drying to obtain a powdered solid polycarboxylate with excellent product performance. However, spray drying suffers from high energy consumption due to its low thermal efficiency.

[0005] Patent CN108084362A discloses a solid polycarboxylate superplasticizer, its preparation method, and its uses. It employs bulk polymerization, followed by cooling and grinding to obtain solid granular polycarboxylate. While this saves energy in the dehydration process, it still requires the use of an electrically refrigerated centrifuge unit to prepare low-temperature water for cooling the molten polycarboxylate. Furthermore, because mass and heat transfer issues cannot be resolved during bulk polymerization, the conversion rate of the polyether macromonomer in the product is low, resulting in poor product performance and making it difficult to meet application requirements.

[0006] Solid polycarboxylate superplasticizers can solve the problem of product sales radius, but existing technologies struggle to balance product performance and low energy consumption. Therefore, developing a solid polycarboxylate superplasticizer preparation system and method that guarantees product performance and energy saving is of great significance. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a solid polycarboxylate superplasticizer preparation system and method. This system can fully utilize the surplus hot water from the polyether reaction heat recovery system as a heat source for solidifying the polycarboxylate superplasticizer mother liquor, thereby preparing the polycarboxylate superplasticizer mother liquor into solid polycarboxylate, reducing energy consumption and improving product quality.

[0008] To achieve the above objectives, the technical solution adopted by the present invention to solve its technical problem is as follows: the solid polycarboxylate superplasticizer preparation system includes a polyether reaction device, a polycarboxylate mother liquor concentration device, and a flake machine. The polyether reaction device is connected to the polycarboxylate mother liquor concentration device and the low-temperature water device through a heat recovery device. The polycarboxylate mother liquor concentration device is connected to the material inlet of the flake machine, and the low-temperature water device is connected to the low-temperature water inlet of the flake machine.

[0009] The polyether reaction device and the heat recovery device are set up as a set, and two or more sets are set up. Multiple sets of the polyether reaction device and the heat recovery device are connected in parallel and then connected to the polycarboxylate mother liquor concentration device and the low temperature water device.

[0010] The polyether reaction device includes an external circulation spray reactor and circulating heat exchangers I and II connected thereto. Circulating heat exchangers I and II are connected in parallel and then connected to the heat recovery device.

[0011] The external circulation spray reactor includes a reactor body, a material inlet at the top of the reactor body, a material outlet at the bottom of the reactor, and a circulation spray port I and a circulation spray port II at the top of the reactor.

[0012] The material outlet is connected to branch pipe I and branch pipe II. Branch pipe I is connected to the circulating spray port I in sequence through circulating pump I and circulating heat exchanger I. Branch pipe II is connected to the circulating spray port II in sequence through circulating pump II and circulating heat exchanger II.

[0013] The circulating heat exchanger I and the circulating heat exchanger II have the same structure, both including a heat exchanger body. The heat exchanger body is connected to the external circulating spray reactor through a material circulation pipe, and the heat exchanger body is connected to the heat recovery device through a hot water circulation pipe I.

[0014] The heat recovery device includes a hot water heat exchange device and a hot water supply device. The hot water heat exchange device includes a hot water heat exchanger, which is connected to the hot water circulation pipe I via a hot water circulation pipe II. A hot water transfer pump and a hot water expansion tank are connected inside the hot water circulation pipe II. The hot water heat exchanger is connected to the hot water supply device, the polycarboxylate mother liquor concentration device, and the low-temperature water device via the hot water circulation pipe I.

[0015] The hot water supply device includes a hot water storage tank, which is connected to the hot water circulation pipeline I via a hot water transfer pump. The hot water storage tank is also provided with a return port connected to the hot water outlet of the polycarboxylate mother liquor concentration device and the low-temperature water device.

[0016] The polycarboxylate mother liquor concentration device includes a polycarboxylate mother liquor heater and a scraped film evaporator. The material outlet of the polycarboxylate mother liquor heater is connected to the material inlet of the sheeter in sequence through the scraped film evaporator and the molten polycarboxylate transfer pump. The polycarboxylate mother liquor heater is connected to the heat recovery device through hot water circulation pipe II, and the scraped film evaporator is connected to the heat recovery device through hot water circulation pipe III.

[0017] The low-temperature water device includes a hot-water type lithium bromide chiller, which is connected to the heat recovery device via a hot-water circulation pipe IV. The hot-water type lithium bromide chiller is also connected to the low-temperature water delivery pump, the low-temperature water storage tank, and the low-temperature water circulation pipe II of the slagging machine via a low-temperature water circulation pipe I.

[0018] A method for preparing a solid polycarboxylate superplasticizer, using the aforementioned preparation system, includes the following steps:

[0019] Step 1: The polyether reaction is carried out in the polyether reactor. The heat released by the reaction is exchanged, so that the heat is transferred from the material to the hot water.

[0020] Step 2: The heat-conducting hot water that has obtained heat is transferred to the hot water through a heat recovery device, causing the hot water to heat up.

[0021] Step 3: Using hot water as a heat source, the polycarboxylate mother liquor is heated and dehydrated through a polycarboxylate mother liquor concentration device to obtain molten polycarboxylate;

[0022] Step 4: Using hot water as a heat source, prepare low-temperature water through a low-temperature water device, and use it as a cold source for the sheeter. The sheeter cools and sheets the molten polycarboxylic acid to obtain solid polycarboxylic acid.

[0023] The beneficial effects of this invention are:

[0024] 1. This invention makes full use of the heat released by the polyether reaction in the polyether reactor, which is fully recovered by the heat recovery device. The resulting hot water is used as the heat source for the solidification of polycarboxylate mother liquor, avoiding the loss of heat through circulating cooling water and causing unnecessary energy waste.

[0025] 2. This invention employs a complete set of equipment consisting of at least two polyether reaction devices and a heat recovery device. By rationally arranging the operation of the reaction devices, it ensures that at least one device is in the reaction state and can continuously release reaction heat, thereby ensuring sufficient reaction heat to supply the hot water device for stable operation and solving the problem of difficult intermittent reaction heat recovery.

[0026] 3. This invention uses recycled hot water as a heat source for heating the polycarboxylate mother liquor and as a heat source for heating the scraped film evaporator, thereby heating and dehydrating the polycarboxylate mother liquor under reduced pressure, thus reducing steam consumption.

[0027] 4. This invention uses recycled hot water as the heat source for a hot water-type lithium bromide chiller to prepare low-temperature water, and the low-temperature water is used as the cold source for a flake generator. Compared with an electric refrigeration centrifugal chiller, it has a significant energy-saving effect.

[0028] 5. This invention uses a scraped film evaporator to dehydrate the polycarboxylate mother liquor, which is well matched with the hot water recovered by the intermittent reaction heat utilization system, so that the reaction heat is fully utilized. Moreover, because the residence time of the polycarboxylate mother liquor is short and the dehydration temperature is much lower than that of the spray drying process, the reaction can be further carried out during the dehydration process to improve the conversion rate and improve the product quality. Attached Figure Description

[0029] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0030] Figure 1 This is a schematic diagram of the solid polycarboxylate superplasticizer preparation system of the present invention;

[0031] Figure 2 This is a flowchart of the preparation method of the solid polycarboxylate superplasticizer of the present invention;

[0032] The labels in the above figures are as follows: 1. Polyether reactor, 11. External circulation spray reactor, 111. Reactor body, 112. Material inlet, 113. Material outlet, 114. Circulation spray nozzle I, 115. Circulation spray nozzle II, 12. Circulation heat exchanger I, 13. Circulation heat exchanger II, 14. Circulation pump I, 15. Circulation pump II, 16. Material circulation pipeline, 17. Hot water circulation pipeline I, 2. Heat recovery device, 21. Hot water heat exchange device, 211. Hot water heat exchanger, 212. Hot water circulation pipeline II, 213. Hot water conveyance... 214. Hot water expansion tank; 215. Hot water circulation pipeline I; 22. Hot water supply device; 221. Hot water storage tank; 222. Hot water transfer pump; 3. Polycarboxylate mother liquor concentration device; 31. Polycarboxylate mother liquor heater; 32. Scraped film evaporator; 33. Molten polycarboxylate transfer pump; 34. Hot water circulation pipeline II; 35. Hot water circulation pipeline III; 4. Low temperature water device; 41. Hot water type lithium bromide refrigerator; 42. Hot water circulation pipeline IV; 43. Low temperature water circulation pipeline I; 44. Low temperature water transfer pump; 45. Low temperature water storage tank; 5. Flake machine. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0034] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] The existing technology has the following technical problems: 1. The heat recovery system of the polyether reactor fails to utilize all the heat of reaction, and a large amount of heat of reaction still needs to be carried away by circulating cooling water, resulting in energy waste. 2. Traditional solid polycarboxylate production processes suffer from problems of excessively high energy consumption or poor product quality.

[0037] To solve the above technical problems, the specific implementation scheme of the present invention is as follows: Figure 1 As shown, this invention provides a solid polycarboxylate superplasticizer preparation system. The system includes a polyether reactor 1, a polycarboxylate mother liquor concentration device 3, and a flake generator 5. The polyether reactor 1 is connected to the polycarboxylate mother liquor concentration device 3 and a low-temperature water device 4 via a heat recovery device 2. The polycarboxylate mother liquor concentration device 3 is connected to the material inlet 112 of the flake generator 5, and the low-temperature water device 4 is connected to the low-temperature water inlet of the flake generator 5. This invention fully utilizes the heat released from the polyether reaction in the polyether reactor 1, which is fully recovered by the heat recovery device 2. The resulting hot water serves as the heat source for the solidification of the polycarboxylate mother liquor in the polycarboxylate mother liquor concentration device 3, avoiding the loss of heat through circulating cooling water and thus preventing unnecessary energy waste. Furthermore, the recovered hot water is used as the heat source for the low-temperature water device 4 to prepare low-temperature water, which then serves as the cold source for the flake generator 5, resulting in significant energy savings compared to an electrically refrigerated centrifugal chiller.

[0038] Specifically, the polyether reaction unit 1 and the heat recovery unit 2 are installed as a set, with two or more sets installed. Multiple sets of polyether reaction units 1 and heat recovery units 2 are connected in parallel to the polycarboxylate mother liquor concentration unit 3 and the low-temperature water unit 4, ensuring that at least one unit is in a reaction state and can continuously release reaction heat. This ensures sufficient reaction heat for the stable operation of the hot water unit, solving the problem of difficult heat recovery in intermittent reactions. (The attached text is incomplete and requires further context.) Figure 1 Only one set of devices is shown. The hot water circulation pipelines of the heat recovery device 2 of multiple devices are combined into a main pipeline and then connected to the polycarboxylate mother liquor concentration device 3 and the low temperature water device 4.

[0039] Specifically, the polyether reaction device 1 includes an external circulation spray reactor 11 and circulating heat exchangers I 12 and II 13 connected thereto. Circulating heat exchangers I 12 and II 13 are connected in parallel and then connected to the heat recovery device 2. Circulating heat exchangers I 12 and II 13 can be set to the same specifications or different specifications, depending on actual needs.

[0040] The external circulation spray reactor 11 includes a reactor body 111, a material inlet 112 at the top of the reactor body 111, a material outlet 113 at the bottom of the reactor, and a circulation spray port I 114 and a circulation spray port II 115 at the top of the reactor. Branch pipe I and branch pipe II are connected to the material outlet 113. Branch pipe I is connected to the circulation spray port I 114 in sequence through circulation pump I 14 and circulation heat exchanger I 12. Branch pipe II is connected to the circulation spray port II 115 in sequence through circulation pump II 15 and circulation heat exchanger II 13, so as to realize heat recovery during the material circulation spraying process, heat exchange and temperature rise of hot water, and provide heat source for polycarboxylate mother liquor concentration device 3 and low temperature water device 4.

[0041] The circulating heat exchangers I12 and II13 have the same structure, both including a heat exchanger body. The heat exchanger body is connected to the external circulating spray reactor 11 through a material circulation pipe 16. A circulation pump I14 or circulation pump II15 is installed in the material circulation pipe 16 to realize the circulating spraying of materials. The heat exchanger body is connected to the heat recovery device 2 through a hot water circulation pipe I17, so that the heat released by the polyether reaction in the external circulating spray reactor 11 is transferred to the hot water circulation pipe I17 during the material circulation process, which increases the temperature of the hot water flowing out of the heat exchanger body through the hot water circulation pipe I17, and increases the temperature of the hot water in the heat recovery device 2, so as to provide a heat source for the polycarboxylate mother liquor concentration device 3 and the low temperature water device 4.

[0042] Specifically, the heat recovery device 2 includes a hot water heat exchanger 21 and a hot water supply device 22. The hot water heat exchanger 21 includes a hot water heat exchanger 211, which is connected to a hot water circulation pipe I 17 via a hot water circulation pipe II 212, allowing the heated hot water to flow into the hot water heat exchanger 211. A hot water transfer pump 213 and a hot water expansion tank 214 are connected to the hot water circulation pipe II 212. The hot water transfer pump 213 circulates the hot water, while the hot water expansion tank 214 serves to hold water and maintain pressure, ensuring the relative stability of the overall pressure during the operation of the hot water heat exchanger 21. The hot water heat exchanger 211 is connected to the hot water supply device 22, the polycarboxylate mother liquor concentration device 3, and the low-temperature water device 4 via a hot water circulation pipe I 215. The hot water heat exchanger 211 is connected to the hot water supply device 22 via the hot water circulation pipe I 215 to circulate and supply hot water, thereby providing a heat source for the polycarboxylate mother liquor concentration device 3 and the low-temperature water device 4.

[0043] The hot water supply device 22 includes a hot water storage tank 221, which is connected to a hot water circulation pipe I 215 via a hot water transfer pump 222 to continuously supply hot water. This hot water is heated after heat exchange to provide a heat source for the polycarboxylate mother liquor concentration device 3 and the low-temperature water device 4. The hot water storage tank 221 is also equipped with a return port connected to the hot water outlets of the polycarboxylate mother liquor concentration device 3 and the low-temperature water device 4 to achieve hot water circulation.

[0044] Specifically, the polycarboxylate mother liquor concentration device 3 includes a polycarboxylate mother liquor heater 31 and a scraped-film evaporator 32. The material outlet 113 of the polycarboxylate mother liquor heater 31 is connected to the material inlet 112 of the sheeter 5 via the scraped-film evaporator 32 and the molten polycarboxylate transfer pump 33. The polycarboxylate mother liquor is heated by the polycarboxylate mother liquor heater 31, and dehydrated by vacuum distillation in the scraped-film evaporator 32 to form molten polycarboxylate. Due to the short residence time of the polycarboxylate mother liquor and the dehydration temperature being much lower than that of the spray drying process, further reactions can be carried out during the dehydration process to improve the conversion rate. After the molten polycarboxylate enters the sheeter 5 for solidification, the product quality can be improved. The polycarboxylate mother liquor heater 31 is connected to the heat recovery device 2 via a hot water circulation pipe II 34, and the scraped-film evaporator 32 is connected to the heat recovery device 2 via a hot water circulation pipe III 35. By using the recovered hot water as the heat source for heating the polycarboxylate mother liquor and as the heat source for heating the scraped-film evaporator 32, the steam consumption is reduced, achieving the purpose of energy saving and consumption reduction.

[0045] Specifically, the low-temperature water device 4 includes a hot-water type lithium bromide chiller 41. The hot-water type lithium bromide chiller 41 uses hot water as a heat source and is connected to a heat recovery device 2 via a hot water circulation pipe IV 42, which continuously provides heat to the chiller. The hot-water type lithium bromide chiller 41 uses circulating cooling water as a refrigerant. It is connected to a low-temperature water transfer pump 44, a low-temperature water storage tank 45, and a low-temperature water circulation pipe II of the flake generator 5 via a low-temperature water circulation pipe I 43. Water from the low-temperature water storage tank 45 is pumped to the hot-water type lithium bromide chiller 41 by the low-temperature water transfer pump 44, lowering its temperature before flowing into the low-temperature water circulation pipe II of the flake generator 5, serving as a cold source for the flake generator 5. Using recovered hot water as the heat source for the hot-water type lithium bromide chiller 41 to prepare low-temperature water, and using this low-temperature water as the cold source for the flake generator 5, results in significant energy savings compared to an electrically refrigerated centrifugal chiller unit.

[0046] like Figure 2 As shown, the method for preparing solid polycarboxylate superplasticizer using the above-described preparation system includes the following steps:

[0047] Step 1: The polyether reaction is carried out in the polyether reaction device 1. The heat released by the reaction is exchanged, so that the heat is transferred from the material to the hot water.

[0048] Specifically, 1) Ethylene oxide is continuously added to the external circulation spray reactor 11, with alkenyl alcohol as the initiator and alkali as the catalyst, and a polymerization reaction is carried out in the reaction device. During the reaction, ethylene oxide undergoes ring-opening exothermic reaction to obtain polyether macromonomers, including methyl allyl alcohol polyoxyethylene ether, isopentenyl alcohol polyoxyethylene ether, vinyl polyoxyethylene ether, or hydroxybutyl vinyl polyethylene glycol ether. 2) The reaction product enters the material circulation pipe 16 of the circulation heat exchanger 12 through circulation pump I14 and then enters the circulation spray port I114. At the same time, the reaction product enters the material circulation pipe 16 of the circulation heat exchanger 13 through circulation pump II15 and then enters the circulation spray port II115. During this process, the hot water flowing in the hot water circulation pipe I17 absorbs the heat from the material circulation pipe 16 and rises in temperature. The operating parameters of circulating heat exchanger I12 and circulating heat exchanger II13 are as follows: the temperature at the material inlet is 120℃~145℃, the temperature at the material outlet is 110℃~130℃, the temperature at the hot water inlet is 90℃~100℃, and the temperature at the hot water outlet is 100℃~115℃.

[0049] The heat released by the polyether reaction in the external circulation spray reactor 11 is transferred to the hot water circulation pipe I17 during the material circulation process, which raises the temperature of the hot water flowing out of the heat exchanger body from the hot water circulation pipe I17, and raises the temperature of the hot water in the heat recovery device 2, so as to provide a heat source for the polycarboxylate mother liquor concentration device 3 and the low temperature water device 4.

[0050] Step 2: The heat-conducting hot water that has obtained heat is transferred to the hot water through the heat recovery device 2, thereby raising the temperature of the hot water.

[0051] Specifically, the heated hot water flows in the hot water circulation pipe II 212 of the hot water heat exchanger 211. At the same time, the hot water in the hot water storage tank 221 enters the hot water circulation pipe I 215 of the hot water heat exchanger 211 through the hot water transfer pump 222, so that the hot water exchanges heat in the hot water heat exchanger 211, thereby raising the temperature of the hot water flowing out of the hot water heat exchanger 211 and providing a heat source for the polycarboxylate mother liquor concentration device 3 and the low temperature water device 4.

[0052] The operating parameters of the hot water heat exchanger 211 are as follows: hot water inlet temperature 100℃~115℃, hot water outlet temperature 90℃~100℃; hot water inlet temperature 75℃~85℃, hot water outlet temperature 85℃~95℃. The pressure of the hot water expansion tank 214 is 0.0MPaG~0.3MPaG, and the pressure of the hot water storage tank 221 is atmospheric pressure.

[0053] Step 3: Using hot water as a heat source, the polycarboxylate mother liquor is heated and dehydrated through the polycarboxylate mother liquor concentration device 3 to obtain molten polycarboxylate.

[0054] Specifically, the polycarboxylate mother liquor is a readily available composition, a comb-shaped polymer obtained by free radical polymerization of polyether macromonomers and small monomers such as acrylic acid and hydroxyethyl acrylate in aqueous solution. This includes water-reducing polycarboxylate mother liquor, slump-retaining polycarboxylate mother liquor, comprehensive polycarboxylate mother liquor, and early-strength polycarboxylate mother liquor. The content of each component is not detailed here. The water content of the polycarboxylate mother liquor is 30.0%–70.0%.

[0055] After being heated in the polycarboxylate mother liquor heater 31, the polycarboxylate mother liquor enters the scraped film evaporator 32 for vacuum distillation and dehydration to form molten polycarboxylate. The molten polycarboxylate is then introduced into the sheet-forming machine 5 for solidification via the molten polycarboxylate transfer pump 33. During this process, the heated hot water flowing out of the hot water heat exchanger 211 flows into the hot water circulation pipe II 34 of the polycarboxylate mother liquor heater 31 and the hot water circulation pipe III 35 of the scraped film evaporator 32, and then flows back into the hot water storage tank 221. This provides a heat source for the polycarboxylate mother liquor heater 31 and the scraped film evaporator 32, heating and dehydrating the polycarboxylate mother liquor under reduced pressure, thus reducing steam consumption and achieving the goal of energy saving and consumption reduction.

[0056] The operating parameters of the scraped film evaporator 32 are as follows: hot water inlet temperature is 85℃~95℃, hot water return temperature is 75℃~85℃, vacuum degree is 1KPaA~20KPaA, molten polycarboxylate temperature is 65℃~85℃, and the water content of the obtained molten polycarboxylate is 0.1%~3.0%.

[0057] Step 4: Using hot water as a heat source, low-temperature water is prepared through low-temperature water device 4 and used as a cold source for sheet forming machine 5. The molten polycarboxylic acid is cooled and sheeted through sheet forming machine 5 to obtain solid polycarboxylic acid.

[0058] Specifically, the heated hot water flowing out of the hot water heat exchanger 211 simultaneously flows into the hot water circulation pipe IV 42 of the hot water type lithium bromide chiller 41. The hot water type lithium bromide chiller 41 uses circulating cooling water as refrigerant. At the same time, the water in the low temperature water storage tank 45 is transported to the hot water type lithium bromide chiller 41 through the low temperature water transfer pump 44 for cooling. The resulting low temperature water flows into the low temperature water circulation pipe II of the sheeter 5 as a cold source for the sheeter 5, thereby cooling and sheeting the molten polycarboxylic acid flowing into the sheeter 5 to obtain solid polycarboxylic acid.

[0059] The operating parameters of the hot water type lithium bromide chiller 41 are as follows: hot water inlet temperature is 85℃~95℃, hot water outlet temperature is 75℃~85℃, low temperature water outlet temperature is 6℃~8℃, low temperature water inlet temperature is 11℃~13℃, circulating cooling water supply temperature is 30℃~34℃, and circulating cooling water return temperature is 38℃~42℃.

[0060] The operating parameters of the sheeter 5 are as follows: the inlet temperature of low-temperature water is 6℃~8℃, the outlet temperature of low-temperature water is 11℃~13℃, the temperature of molten polycarboxylate is 65℃~85℃, the temperature of solid polycarboxylate is 20℃~35℃, and the water content of the obtained solid polycarboxylate is 0.1%~3.0%.

[0061] The following examples further illustrate the preparation method of solid polycarboxylate superplasticizer.

[0062] Example 1

[0063] The method for preparing solid polycarboxylate superplasticizer using the above preparation system includes the following steps:

[0064] (1) Ethylene oxide is continuously added to the external circulation spray reactor 11. The alkenyl alcohol is used as the initiator and the base is used as the catalyst. The ethylene oxide undergoes a ring-opening exothermic reaction in the reaction device. The heat released by the reaction is exchanged through the circulating heat exchanger I12 and the circulating heat exchanger II13. The heat is transferred from the material to the hot water. The operating parameters of the circulating heat exchanger I12 and the circulating heat exchanger II13 are: the material inlet temperature is 125℃, the material outlet temperature is 108℃, the hot water inlet temperature is 95℃, and the hot water outlet temperature is 105℃.

[0065] (2) The heat-conducting water that obtains heat is transferred to the hot water through the heat-conducting water heat exchanger 211. The operating parameters of the heat-conducting water heat exchanger 211 are as follows: the inlet temperature of the hot water is 105℃, the outlet temperature of the hot water is 95℃, the pressure of the hot water expansion tank 214 is 0.20MPaG; the inlet temperature of the hot water is 80℃, the outlet temperature of the hot water is 90℃, and the pressure of the hot water storage tank 221 is atmospheric pressure.

[0066] (3) Using hot water as a heat source, the polycarboxylate mother liquor is heated by the polycarboxylate mother liquor heater 31. The operating parameters of the polycarboxylate mother liquor heater 31 are: the polycarboxylate mother liquor feed temperature is 25℃, the polycarboxylate mother liquor discharge temperature is 85℃, and the polycarboxylate mother liquor water content is 50.0%.

[0067] (4) Using hot water as a heat source, the polycarboxylate mother liquor is dehydrated through the scraped film evaporator 32 to obtain molten polycarboxylate. The operating parameters of the scraped film evaporator 32 are: hot water inlet temperature is 90℃, hot water return temperature is 80℃, vacuum degree is 3KPaA, molten polycarboxylate temperature is 80℃, and molten polycarboxylate water content is 0.5%.

[0068] (5) Using hot water as a heat source, low-temperature water is prepared by hot water type lithium bromide refrigerator 41. The operating parameters of hot water type lithium bromide refrigerator 41 are: hot water inlet temperature is 90℃, hot water outlet temperature is 80℃, low-temperature water outlet temperature is 7℃, low-temperature water inlet temperature is 12℃, circulating cooling water supply temperature is 32℃, and circulating cooling water return temperature is 40℃.

[0069] (6) Low-temperature water is prepared using a hot water type lithium bromide refrigerator 41 as a cold source. Molten polycarboxylic acid is cooled and precipitated by a precipitator 5 to obtain solid polycarboxylic acid. The operating parameters of the precipitator 5 are: low-temperature water inlet temperature is 7°C, low-temperature water outlet temperature is 12°C, molten polycarboxylic acid temperature is 80°C, solid polycarboxylic acid temperature is 25°C, and the water content of solid polycarboxylic acid is 0.6%.

[0070] Example 2

[0071] The method for preparing solid polycarboxylate superplasticizer using the above preparation system includes the following steps:

[0072] (1) Ethylene oxide is continuously added to the external circulation spray reactor 11. The alkenyl alcohol is used as the initiator and the base is used as the catalyst. The ethylene oxide undergoes a ring-opening exothermic reaction in the reaction device. The heat released by the reaction is exchanged through the large and small circulation heat exchangers. The heat is transferred from the material to the hot water through the heat transfer. The operating parameters of the large and small circulation heat exchangers are: material inlet temperature is 135℃, material outlet temperature is 120℃, hot water inlet temperature is 105℃, and hot water outlet temperature is 115℃.

[0073] (2) The heat-conducting hot water is transferred to the hot water through the heat-conducting hot water heat exchanger 211. The operating parameters of the heat-conducting hot water heat exchanger 211 are as follows: the inlet temperature of the hot water is 115℃, the outlet temperature of the hot water is 105℃, the pressure of the hot water expansion tank 214 is 0.25MPaG; the inlet temperature of the hot water is 87℃, the outlet temperature of the hot water is 97℃, and the pressure of the hot water storage tank 221 is atmospheric pressure.

[0074] (3) Using hot water as a heat source, the polycarboxylate mother liquor is heated by the polycarboxylate mother liquor heater 31. The operating parameters of the polycarboxylate mother liquor heater 31 are: the polycarboxylate mother liquor feed temperature is 25℃, the polycarboxylate mother liquor discharge temperature is 90℃, and the polycarboxylate mother liquor water content is 60.0%.

[0075] (4) Using hot water as a heat source, the polycarboxylic acid mother liquor is dehydrated through the scraped film evaporator 32 to obtain molten polycarboxylic acid. The operating parameters of the scraped film evaporator 32 are: hot water inlet temperature is 97℃, hot water return temperature is 87℃, vacuum degree is 4KPaA, molten polycarboxylic acid temperature is 82℃, and molten polycarboxylic acid water content is 0.6%.

[0076] (5) Using hot water as a heat source, low-temperature water is prepared by hot water type lithium bromide refrigerator 41. The operating parameters of hot water type lithium bromide refrigerator 41 are: hot water inlet temperature is 97℃, hot water outlet temperature is 87℃, low-temperature water outlet temperature is 8℃, low-temperature water inlet temperature is 13℃, circulating cooling water supply temperature is 32℃, and circulating cooling water return temperature is 40℃.

[0077] (6) Low-temperature water is prepared by hot water type lithium bromide refrigerator 41 as cold source, and molten polycarboxylic acid is cooled and precipitated by precipitator 5 to obtain solid polycarboxylic acid. The operating parameters of precipitator 5 are: low-temperature water inlet temperature is 8℃, low-temperature water outlet temperature is 13℃, molten polycarboxylic acid temperature is 82℃, solid polycarboxylic acid temperature is 28℃, and solid polycarboxylic acid water content is 0.7%.

[0078] Example 3

[0079] The method for preparing solid polycarboxylate superplasticizer using the above preparation system includes the following steps:

[0080] (1) Ethylene oxide is continuously added into the external circulation spray reactor 11. The alkenyl alcohol is used as the initiator and the base is used as the catalyst. The ethylene oxide undergoes a ring-opening exothermic reaction in the reaction device. The heat released by the reaction is exchanged through the large and small circulation heat exchangers. The heat is transferred from the material to the hot water through heat transfer. The operating parameters of the large and small circulation heat exchangers are: material inlet temperature is 130℃, material outlet temperature is 115℃, hot water inlet temperature is 100℃, and hot water outlet temperature is 110℃.

[0081] (2) The heat-conducting hot water is transferred to the hot water through the heat-conducting hot water heat exchanger 211. The operating parameters of the heat-conducting hot water heat exchanger 211 are as follows: the inlet temperature of the hot water is 110℃, the outlet temperature of the hot water is 100℃, the pressure of the hot water expansion tank 214 is 0.25MPaG; the inlet temperature of the hot water is 85℃, the outlet temperature of the hot water is 95℃, and the pressure of the hot water storage tank 221 is atmospheric pressure.

[0082] (3) Using hot water as a heat source, the polycarboxylate mother liquor is heated by the polycarboxylate mother liquor heater 31. The operating parameters of the polycarboxylate mother liquor heater 31 are: the polycarboxylate mother liquor feed temperature is 28℃, the polycarboxylate mother liquor discharge temperature is 87℃, and the polycarboxylate mother liquor water content is 40.0%.

[0083] (4) Using hot water as a heat source, the polycarboxylate mother liquor is dehydrated through the scraped film evaporator 32 to obtain molten polycarboxylate. The operating parameters of the scraped film evaporator 32 are: hot water inlet temperature is 95℃, hot water return temperature is 85℃, vacuum degree is 2KPaA, molten polycarboxylate temperature is 80℃, and molten polycarboxylate water content is 0.3%.

[0084] (5) Using hot water as a heat source, low-temperature water is prepared by hot water type lithium bromide refrigerator 41. The operating parameters of hot water type lithium bromide refrigerator 41 are: hot water inlet temperature is 95℃, hot water outlet temperature is 85℃, low-temperature water outlet temperature is 6℃, low-temperature water inlet temperature is 12℃, circulating cooling water supply temperature is 31℃, and circulating cooling water return temperature is 39℃.

[0085] (6) Low-temperature water is prepared using a hot water type lithium bromide refrigerator 41 as a cold source. Molten polycarboxylic acid is cooled and precipitated by a precipitator 5 to obtain solid polycarboxylic acid. The operating parameters of the precipitator 5 are: low-temperature water inlet temperature is 6℃, low-temperature water outlet temperature is 12℃, molten polycarboxylic acid temperature is 78℃, solid polycarboxylic acid temperature is 26℃, and solid polycarboxylic acid water content is 0.4%.

[0086] Comparative Example 1

[0087] Using polycarboxylic acid mother liquor with the same composition as in Examples 1-3, and referring to the technical solution of Example 1 in patent CN115449022A, powdered polycarboxylic acid was obtained by spray drying.

[0088] Comparative Example 2

[0089] Referring to the technical solution of Example 1 in patent CN108084362A, molten polycarboxylic acid is obtained by bulk polymerization, and then low-temperature water is used as a cold source to cool the molten polycarboxylic acid into block polycarboxylic acid. Then, dry ice is used as a cold source and a pulverizer is used to grind the block polycarboxylic acid into solid granular polycarboxylic acid.

[0090] Based on Examples 1-3 and Comparative Examples 1 and 2 above, the following is an examination of the performance of the solid polycarboxylate superplasticizer prepared by the present invention by testing the fluidity, molecular weight and polyether macromonomer conversion rate of cement paste and comparing energy consumption.

[0091] Referring to the test method for the fluidity of cement paste in GB / T 8077-2012 "Test Method for Homogeneity of Concrete Admixtures", polycarboxylate mother liquor and solid polycarboxylate were prepared into samples with a solid content of 10%. The sample dosage was fixed, and the initial fluidity (denoted by FL0), 1-hour fluidity (denoted by FL60), and 2-hour fluidity (denoted by FL120) were compared over time. The molecular weight and macromonomer conversion rate of the samples were tested using a Waters E2695 gel chromatograph. The chromatographic conditions were as follows: column: Waters Ultrahydrogel TM120, TM250, and TM500 in series; flow rate: 1 ml / min; column temperature: 40℃; mobile phase: 0.1 M NaNO3 aqueous solution. The test results are shown in the table below: Mn is the number-average molecular weight, Mw is the weight-average molecular weight, and Mw / Mn is the polydispersity index, which is used to measure the width of the molecular weight distribution. The closer the polydispersity index is to 1, the closer Mw and Mn are, and the more concentrated the molecular weight distribution is.

[0092] Table 1 Comparison Results

[0093] Polycarboxylate mother liquor 1.3 250 220 180 16183 26831 1.66 95.35 Example 1 1.3 252 222 182 15832 27654 1.75 96.36 Low Example 2 1.3 253 225 187 15352 28828 1.88 96.53 Low Example 3 1.3 248 218 185 15056 28102 1.87 96.72 Low Comparative Example 1 1.3 245 218 175 16564 32785 1.98 96.84 high Comparative Example 2 1.3 210 175 130 12536 25068 2.00 83.48 middle

[0094] The solid polycarboxylic acids prepared in Examples 1-3 and Comparative Example 1 of this invention have performance comparable to the polycarboxylic acid mother liquor before curing, and are far superior to Comparative Example 2. The product performance of Comparative Example 1 is comparable to that of Examples 1-3 of this invention, but its energy consumption is too high, resulting in poor economic efficiency.

[0095] The present invention has the following beneficial effects:

[0096] 1. This invention makes full use of the heat released by the polyether reaction in the polyether reactor, which is fully recovered by the heat recovery device. The resulting hot water is used as the heat source for the solidification of polycarboxylate mother liquor, avoiding the loss of heat through circulating cooling water and causing unnecessary energy waste.

[0097] 2. This invention employs a complete set of equipment consisting of at least two polyether reaction devices and a heat recovery device. By rationally arranging the operation of the reaction devices, it ensures that at least one device is in the reaction state and can continuously release reaction heat, thereby ensuring sufficient reaction heat to supply the hot water device for stable operation and solving the problem of difficult intermittent reaction heat recovery.

[0098] 3. This invention uses recycled hot water as a heat source for heating the polycarboxylate mother liquor and as a heat source for heating the scraped film evaporator, thereby heating and dehydrating the polycarboxylate mother liquor under reduced pressure, thus reducing steam consumption.

[0099] 4. This invention uses recycled hot water as the heat source for a hot water-type lithium bromide chiller to prepare low-temperature water, and the low-temperature water is used as the cold source for a flake generator. Compared with an electric refrigeration centrifugal chiller, it has a significant energy-saving effect.

[0100] 5. This invention uses a scraped film evaporator to dehydrate the polycarboxylate mother liquor, which is well matched with the hot water recovered by the intermittent reaction heat utilization system, so that the reaction heat is fully utilized. Moreover, because the residence time of the polycarboxylate mother liquor is short and the dehydration temperature is much lower than that of the spray drying process, the reaction can be further carried out during the dehydration process to improve the conversion rate and improve the product quality.

[0101] The above description is merely an illustration of some principles of the present invention. This specification is not intended to limit the present invention to the specific structures and applicable scope shown. Therefore, all possible modifications and equivalents that may be used fall within the scope of the patent application of this invention.

Claims

1. A solid polycarboxylate superplasticizer preparation system, characterized in that, The system includes a polyether reactor, a polycarboxylate mother liquor concentration unit, and a flake generator. The polyether reactor is connected to the polycarboxylate mother liquor concentration unit and a low-temperature water unit via a heat recovery device. The polycarboxylate mother liquor concentration unit is connected to the material inlet of the flake generator, and the low-temperature water unit is connected to the low-temperature water inlet of the flake generator. The polyether reactor includes an external circulation spray reactor and two circulating heat exchangers I and II connected thereto. Circulating heat exchangers I and II are connected in parallel to the heat recovery device. Circulating heat exchangers I and II have the same structure, both including a heat exchanger body. The heat exchanger body is connected to the external circulation spray reactor via a material circulation pipe, and the heat exchanger body is connected to the heat recovery device via a hot water circulation pipe I. The heat recovery device includes a hot water heat exchanger and a hot water supply device. The hot water heat exchanger includes a hot water heat exchanger, which is connected to the hot water circulation pipe I via a hot water circulation pipe II. A hot water transfer pump and a hot water supply pump are connected within the hot water circulation pipe II. An expansion tank is included. The hot water heat exchanger is connected to the hot water supply device, the polycarboxylate mother liquor concentration device, and the low-temperature water device via hot water circulation pipe I. The hot water supply device includes a hot water storage tank, which is connected to the hot water circulation pipe I via a hot water transfer pump. The hot water storage tank is also equipped with a reflux port connected to the hot water outlet of the polycarboxylate mother liquor concentration device and the low-temperature water device. The polycarboxylate mother liquor concentration device includes a polycarboxylate mother liquor heater and a scraped film evaporator. The material outlet of the polycarboxylate mother liquor heater is connected to the material inlet of the sheeter via the scraped film evaporator and the molten polycarboxylate transfer pump. The polycarboxylate mother liquor heater is connected to the heat recovery device via hot water circulation pipe II. The scraped film evaporator is connected to the heat recovery device via hot water circulation pipe III. The low-temperature water device includes a hot water type lithium bromide refrigerator, which is connected to the heat recovery device via hot water circulation pipe IV. The hot water type lithium bromide refrigerator is connected to the low-temperature water transfer pump, the low-temperature water storage tank, and the low-temperature water circulation pipe II of the sheeter via low-temperature water circulation pipe I.

2. The solid polycarboxylate superplasticizer preparation system according to claim 1, characterized in that: The polyether reaction device and the heat recovery device are set up as a set, and two or more sets are set up. Multiple sets of the polyether reaction device and the heat recovery device are connected in parallel and then connected to the polycarboxylate mother liquor concentration device and the low temperature water device.

3. The solid polycarboxylate superplasticizer preparation system according to claim 2, characterized in that: The external circulation spray reactor includes a reactor body, a material inlet at the top of the reactor body, a material outlet at the bottom of the reactor body, and a circulation spray port I and a circulation spray port II at the upper part of the reactor body. The material outlet is connected to a branch pipe I and a branch pipe II. The branch pipe I is connected to the circulation spray port I in sequence through a circulation pump I and a circulation heat exchanger I. The branch pipe II is connected to the circulation spray port II in sequence through a circulation pump II and a circulation heat exchanger II.

4. A method for preparing a solid polycarboxylate superplasticizer, using the preparation system described in any one of claims 1 to 3, characterized in that, The process includes the following steps: Step 1: A polyether reaction is carried out in a polyether reactor, and the heat released by the reaction is exchanged to transfer heat from the material to the hot water; Step 2: The hot water that has gained heat is exchanged through a heat recovery device, and the heat is transferred from the hot water to the hot water, raising the temperature of the hot water; Step 3: Using the hot water as a heat source, the polycarboxylate mother liquor is heated and dehydrated through a polycarboxylate mother liquor concentration device to obtain molten polycarboxylate; Step 4: Using the hot water as a heat source, low-temperature water is prepared through a low-temperature water device and used as a cold source for a sheeter. The molten polycarboxylate is cooled and sheeted through the sheeter to obtain solid polycarboxylate.

Images