Experimental testing device and method for flowing scaling characteristics and phenomena of pulping and papermaking black liquid

Abstract

The invention discloses a device and a method for testing flowing scaling characteristics and phenomena of pulping and papermaking black liquid. The device comprises a stock solution tank, a metering pump, a drain valve, a test tube, a recovery tank, a condensation tube, a collection tank, a heater, a reflux valve, a reflux tube, a reflux tank, a temperature sensor, a pressure sensor, a temperature control device and a control terminal. The method comprises the steps of short pipe scaling obtaining, firing treatment and calculation. According to the invention, operation is more convenient during scaling observation and sampling; in the whole process, treatment of the black liquor is basically in an uninterrupted state, the process of replacing the test tube is efficient and convenient, the test tube can be further disassembled into a short tube, the scaling amount and the scaling form in the short tube after the black liquor is circularly evaporated for a certain time can be very easily observed through the short tube, and scaling sampling is facilitated; the device can simulate the evaporation conditions of the papermaking wastewater black liquor under different temperatures and different flows, and research the evaporation rate of the black liquor, the comparison of scaling amount and the scaling form.

Description

Technical Field

[0001] The invention belongs to the technical field of papermaking black liquor experimental research, and in particular relates to an experimental testing device and method for the flow scaling characteristics and phenomena of pulping and papermaking black liquor. Background Art

[0002] Black liquor is a highly concentrated waste liquid composed of wood cellulose, lignin and other chemicals, usually produced during the chemical pulping process. During chemical pulping (such as the sodium hydroxide process or the sulfite process), wood is treated with chemicals to decompose lignin to extract cellulose. This process produces a large amount of black liquor, which contains organic matter, inorganic salts, ash and water. The composition of black liquor includes not only the waste liquid itself, but also unextracted lignin and other chemicals. If black liquor is not treated, direct discharge will cause serious environmental pollution. Its high COD (chemical oxygen demand) and BOD (biological oxygen demand) values ​​will cause eutrophication and poisoning to water bodies, affecting aquatic ecology. Therefore, reasonable black liquor treatment is an important part of the sustainable development of the papermaking industry.

[0003] Black liquor scaling is also an important industrial problem. Scaling will reduce the efficiency of heat conduction, hinder the flow of fluid in the pipeline, increase the energy consumption of pumping, and the scaling substances may enter the final product, affecting the purity and quality of the product. In general, black liquor scaling has a significant impact on the operation of the equipment and the quality of the product. At present, the prior art has not reported any test equipment for the characteristics and phenomena of black liquor flow scaling. The patent application for a device and evaluation method for simulating the flow of black liquor in pipelines to observe scaling phenomena (application number: 202410778621.6) is the research result of the inventor's team. The emergence of this device fills the gap in the field of black liquor flow scaling research and test equipment. In actual applications, it is found that the equipment is inconvenient to operate in terms of observation and maintenance.

[0004] Regarding the experimental test methods for the characteristics and phenomena of black liquor scaling, the formation process of black liquor scaling usually takes a long time to observe obvious scaling phenomena, which makes the existing test methods have a long cycle and low efficiency. Especially in the industrial production process, it is particularly important to observe the characteristics and phenomena of black liquor scaling and quickly evaluate the scaling tendency of black liquor without affecting the operation of the equipment. And because sodium carbonate and sodium sulfate in black liquor are the main components of pipeline scaling, they will gradually precipitate due to the evaporation of black liquor water to form scaling. For the future treatment of black liquor scaling, it is also necessary to observe the surface morphology of sodium carbonate and sodium sulfate and measure the amount of the two.

[0005] Therefore, it is necessary to develop a new test device and method for the flow scaling characteristics and phenomena of pulping and papermaking black liquor. Summary of the invention

[0006] In order to solve the above technical problems, the first object of the present invention is to provide an experimental test device for the flow scaling characteristics and phenomena of pulping and papermaking black liquor, so as to facilitate the experimental operation.

[0007] A second object of the present invention is to provide an experimental test method for the flow scaling characteristics and phenomena of pulping and papermaking black liquor.

[0008] The first object of the present invention is achieved in this way, including a raw liquid tank, a metering pump, a discharge valve, a test tube, a recovery tank, a condenser, a collection tank, a heater, a reflux valve, a reflux pipe, a reflux tank, a temperature sensor, a pressure sensor, a temperature control device, and a control terminal. The discharge end of the raw liquid tank is connected to the inlet end of the metering pump through a pipeline, the discharge end of the metering pump is connected to the bottom inlet end of the test tube through a pipeline, and the pipeline is provided with a discharge valve, the pipeline between the discharge valve and the metering pump is connected with a reflux pipe, the reflux pipe is connected to the inlet end of the reflux tank, and the reflux pipe is provided with a reflux valve, the discharge end of the reflux tank is connected to the inlet end of the raw liquid tank through a pipeline, and the discharge end of the test tube top is connected to the inlet end of the reflux tank. The end is connected to the inlet end of the recovery tank through a pipeline, the gas discharge end on the side of the recovery tank is connected to the inlet end of the condenser through a gas pipeline, the discharge end of the condenser is connected to the inlet end of the collection tank through a pipeline, the liquid discharge end of the recovery tank is connected to the inlet end of the raw liquid tank through a liquid pipeline, the test tube includes a plurality of short tubes and pipeline connectors, the short tubes are connected by pipeline connectors, a heater is provided outside the test tube, the heater is provided with a temperature control device, pressure sensors are provided at the inlet end and the discharge end of the test tube, a temperature sensor is provided in the middle of the test tube, and the metering pump, temperature sensor, pressure sensor, and temperature control device are electrically connected to the control terminal respectively.

[0009] Among them, the control terminal is used to receive and display the temperature and pressure data transmitted by the temperature sensor and the pressure sensor, and the control terminal controls the opening or closing of the metering pump and the temperature control device, which are all well-known technologies in the art.

[0010] Preferably, the heater is a tubular electric heater, and the heater is arranged outside the test tube in a spirally wound shape.

[0011] The second object of the present invention is achieved by comprising the following steps: S1. First, the residual black liquor is sent to the reflux tank through the reflux valve, then one section of the short tube is removed and replaced, the black liquor in the reflux tank is sent back to the original liquid tank, the metering pump is turned on and the evaporation process is continued; the scale in the replaced short tube is scraped with a medicine spoon, and the total mass of the scale in the short tube is weighed after drying, and plasma water is added to dissolve it. After it is completely dissolved, it is stirred evenly and divided into four equal solutions; S2. Filter one of the solutions using a quantitative filter paper, place the filter residue in a muffle furnace and burn it, cool it after burning, grind it into powder, observe and analyze it using a scanning electron microscope (SEM) to obtain its surface morphology and material composition; S3, the remaining three solutions are filtered with quantitative filter paper to remove the solidified material and insoluble precipitate in the solution to obtain a filtrate; a sufficient amount of saturated barium chloride solution is added to the filtrate to precipitate sodium carbonate and sodium sulfate in the form of barium carbonate and barium sulfate, and the filtrate is filtered with quantitative filter paper, and the filter paper and the filtrate are placed in a muffle furnace and burned for 4 hours to obtain a burnt product, and the weight of the burnt product is weighed to obtain the total mass of barium carbonate and barium sulfate; a sufficient amount of concentrated hydrochloric acid is added to the burnt product, and the product is filtered again with quantitative filter paper, and placed in a muffle furnace and burned, and weighed to obtain the mass of barium sulfate; wherein the mass fraction of concentrated hydrochloric acid is 50%; The mass a of sodium carbonate is calculated from the mass b of barium carbonate by its relative molecular mass: ; The mass x of sodium sulfate is calculated from the mass y of barium sulfate by its relative molecular mass: ; The calculated results of three samples are averaged; the relative molecular mass of sodium carbonate is 106, the relative molecular mass of barium carbonate is 197, the relative molecular mass of sodium sulfate is 142, and the relative molecular mass of barium sulfate is 233.

[0012] Compared with the prior art, the present invention has the following technical effects: 1. The device of the present invention is designed with a black liquor reflux function, which is not only convenient for disassembly and assembly, but also more convenient for operation during scaling observation and sampling; 2. The device of the present invention treats black liquor in an uninterrupted state during the whole process. The process of replacing the test tube is efficient and convenient. The test tube can be further disassembled into short tubes. Through the short tubes, it is very easy to observe the amount and morphology of scaling in the short section after the black liquor has been cyclically evaporated for a certain period of time, which is helpful for scaling sampling; 3. The device of the present invention can simulate the evaporation conditions of papermaking wastewater black liquor at different temperatures and flow rates, and study the evaporation rate of black liquor, the comparison of scaling amount and the morphology of scaling; 4. The method of the present invention focuses on measuring sodium carbonate and sodium sulfate, which are highly correlated with black liquor scaling. A scanning electron microscope (SEM) is used to observe the surface morphology and distribution of the two, and a qualitative analysis is performed on the elements therein. At the same time, a chemical method is used to quantitatively analyze the sodium carbonate and sodium sulfate. The operation is simple and convenient, and the results of multiple measurements are more accurate. The observation of the mixed scaling morphology of the two is more intuitive, and it provides a reference for the future treatment of scaling of sodium carbonate and sodium sulfate in pipelines by different methods, as well as the analysis of different microscopic morphologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the device of the present invention; Figure 2 It is a schematic diagram of the structure of the test tube; In the figure: 1-raw liquid tank, 2-metering pump, 3-drain valve, 4-test tube, 401-short tube, 402-pipeline connector, 5-recovery tank, 6-condenser, 7-collection tank, 8-heater, 9-reflux valve, 10-reflux pipe, 11-reflux tank, 12-temperature sensor, 13-pressure sensor, 14-temperature control device, 15-control terminal. DETAILED DESCRIPTION

[0014] The present invention is further described below in conjunction with the accompanying drawings, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0015] Example 1 As attached Figure 1 ~Attached Figure 2 The test device for testing the flow scaling characteristics and phenomena of pulping and papermaking black liquor in the present embodiment shown in the figure comprises a raw liquid tank 1, a metering pump 2, a drain valve 3, a test tube 4, a recovery tank 5, a condenser 6, a collecting tank 7, a heater 8, a reflux valve 9, a reflux pipe 10, a reflux tank 11, a temperature sensor 12, a pressure sensor 13, a temperature control device 14, and a control terminal 15. The discharge end of the raw liquid tank 1 is connected to the inlet end of the metering pump 2 through a pipeline, the discharge end of the metering pump 2 is connected to the bottom inlet end of the test tube 4 through a pipeline, and the pipeline is provided with a drain valve 3, the pipeline between the drain valve 3 and the metering pump 2 is connected with a reflux pipe 10, the reflux pipe 10 is connected to the inlet end of the reflux tank 11, and the reflux pipe 10 is provided with a reflux valve 9, the discharge end of the reflux tank 11 is connected to the inlet end of the raw liquid tank 1 through a pipeline, and the test The top discharge end of the test tube 4 is connected to the inlet end of the recovery tank 5 through a pipeline, the gas discharge end on the side of the recovery tank 5 is connected to the inlet end of the condenser 6 through a gas pipeline, the discharge end of the condenser 6 is connected to the inlet end of the collection tank 7 through a pipeline, the liquid discharge end of the recovery tank 5 is connected to the inlet end of the raw liquid tank 1 through a liquid pipeline, the test tube 4 includes a plurality of short tubes 401 and a pipeline connector 402, the short tubes 401 are connected by the pipeline connector 402, the test tube 4 is provided with a heater 8 outside, the heater 8 is provided with a temperature control device 14, the inlet end and the discharge end of the test tube 4 are respectively provided with pressure sensors 13, the middle part of the test tube 4 is provided with a temperature sensor 12, the metering pump 2, the temperature sensor 12, the pressure sensor 13, the temperature control device 14 are respectively electrically connected to the control terminal 15.

[0016] The working principle and working process of the present invention are as follows: the black liquor to be evaporated is sent into the raw liquid tank 1, and the black liquor is transported to the test tube 4 at a given speed by the metering pump 2 for evaporation; the heater 8 is controlled by the temperature control device 14 to heat the test tube 4; The heated black liquor is sent to the recovery tank 5, and the evaporated gas is liquefied through the condenser 6 and sent to the collection tank 7; the black liquor in the recovery tank 5 is sent back to the original liquid tank 1 and evaporated again in a fixed time cycle; When it is necessary to observe and sample the scaling in the test tube 4, the metering pump 2 is turned off, and the residual black liquor is sent to the reflux tank 11 through the reflux valve 9; then the test tube 4 is removed and replaced; the black liquor in the reflux tank 11 is sent back to the original liquid tank 1, and the metering pump 2 is turned on and the evaporation treatment is continued; the replaced test tube 4 can be further disassembled by the pipe connector 402 and divided into several short tubes 401, so as to facilitate the comprehensive observation of scaling conditions; the black liquor is reprocessed by comparing the scaling thickness and scaling morphology at different temperatures and different flow rates; The two pressure sensors 13 are used to monitor the pressure at the inlet and outlet of the pressure test tube 4, and can further calculate the pressure difference and the density of the black liquor in the pipeline. The density before and after the evaporation of the black liquor and the temperature sensor can indirectly reflect the evaporation efficiency of the black liquor at this temperature.

[0017] Example 2 The method of testing the device for testing the flow scaling characteristics and phenomena of pulping and papermaking black liquor according to Example 1 comprises the following steps: S1. After the black liquor flows at a temperature of 80° C. for 72 hours in the test device, the residual black liquor is sent to the reflux tank 11 through the reflux valve 9, and then one section of the short pipe 401 is removed and replaced. The length of the short pipe is 0.1 meter and the nominal diameter is DN40. The black liquor in the reflux tank 11 is sent back to the original liquid tank 1, and the metering pump 2 is turned on and the evaporation treatment is continued; the scale in the replaced short pipe 401 is scraped with a medicine spoon, and the total mass of the scale in the short pipe is weighed after drying to obtain 4.948 g, and an appropriate amount of plasma water is added to dissolve it. After it is completely dissolved, it is stirred evenly and divided into four equal parts of solution; S2. Filter one of the solutions using quantitative filter paper, and place the filter residue in a muffle furnace and burn it at a temperature of 575±25° C. for 4 hours. After the burning is completed, cool it, grind it into powder, and observe and analyze it using a scanning electron microscope to obtain its surface morphology and material composition; S3, the remaining three solutions were filtered using quantitative filter paper to remove the solidified material and insoluble precipitate in the solution to obtain a filtrate; 5 ml of saturated barium chloride solution was added to each of the three filtrates to precipitate sodium carbonate and sodium sulfate in the form of barium carbonate and barium sulfate, and the filtrates were filtered using quantitative filter paper, and the filter paper and the filtrate were placed in a muffle furnace and calcined at a temperature of 575±25°C for 4 hours to obtain three calcined products, and the weights of the calcined products were weighed respectively, that is, the total masses of barium carbonate and barium sulfate were 0.421 g, 0.389 g, and 0.443 g, respectively; 2 ml of 50% concentrated hydrochloric acid was added to each of the three calcined products, and the products were filtered again using quantitative filter paper, placed in a muffle furnace and calcined at a temperature of 575±25°C for 4 hours, and weighed to obtain barium sulfates of 0.133 g, 0.129 g, and 0.151 g, respectively; The mass a of sodium carbonate is calculated from the mass b of barium carbonate by its relative molecular mass: ; The mass x of sodium sulfate is calculated from the mass y of barium sulfate by its relative molecular mass: ; The relative molecular mass of sodium carbonate is 106, the relative molecular mass of barium carbonate is 197, the relative molecular mass of sodium sulfate is 142, and the relative molecular mass of barium sulfate is 233; Calculation shows that the mass of barium carbonate of the three samples is 0.288g, 0.260g, and 0.292g, the mass of sodium sulfate is 0.081g, 0.079g, and 0.092g, and the mass of sodium carbonate is 0.155g, 0.140g, and 0.157g; the mass of barium sulfate of the three samples calculated according to the average value is 0.138g, the mass of barium carbonate is 0.280g, the mass of sodium sulfate is 0.084g, and the mass of sodium carbonate is 0.150g.

Claims

1. An experimental test device for the flow scaling characteristics and phenomena of pulping and papermaking black liquor, comprising a raw liquid tank (1), a metering pump (2), a drain valve (3), a test tube (4), a recovery tank (5), a condenser (6), a collection tank (7), a heater (8), a reflux valve (9), a reflux pipe (10), a reflux tank (11), a temperature sensor (12), a pressure sensor (13), a temperature control device (14), and a control terminal (15), characterized in that The discharge end of the raw liquid tank (1) is connected to the inlet end of the metering pump (2) through a pipeline, the discharge end of the metering pump (2) is connected to the inlet end of the bottom of the test tube (4) through a pipeline, and the pipeline is provided with a discharge valve (3), the pipeline between the discharge valve (3) and the metering pump (2) is connected with a reflux pipe (10), the reflux pipe (10) is connected to the inlet end of the reflux tank (11), and the reflux pipe (10) is provided with a reflux valve (9), the discharge end of the reflux tank (11) is connected to the inlet end of the raw liquid tank (1) through a pipeline, the discharge end of the top of the test tube (4) is connected to the inlet end of the recovery tank (5) through a pipeline, the gas discharge end on the side of the recovery tank (5) is connected to the inlet end of the condenser (6) through a gas pipeline, and the discharge end of the condenser (6) is connected to the inlet end of the condenser (6) through a gas pipeline. The pipeline is connected to the inlet end of the collection tank (7); the liquid discharge end of the recovery tank (5) is connected to the inlet end of the raw liquid tank (1) through the liquid pipeline; the test tube (4) comprises a plurality of short tubes (401) and a pipeline connector (402); the short tubes (401) are connected through the pipeline connector (402); a heater (8) is provided outside the test tube (4); the heater (8) is provided with a temperature control device (14); the inlet end and the discharge end of the test tube (4) are respectively provided with pressure sensors (13); a temperature sensor (12) is provided in the middle of the test tube (4); and the metering pump (2), the temperature sensor (12), the pressure sensor (13), and the temperature control device (14) are respectively electrically connected to the control terminal (15).

2. The test device for testing the flow scaling characteristics and phenomena of pulping and papermaking black liquor according to claim 1, characterized in that The heater (8) is a tubular electric heater, and the heater (8) is arranged outside the test tube (4) in a spirally wound shape.

3. The method for testing the flow scaling characteristics and phenomena of pulping and papermaking black liquor is characterized by The following steps are involved: S1. First, the residual black liquor is sent to the reflux tank (11) through the reflux valve (9), then one section of the short tube (401) is removed and replaced, and the black liquor in the reflux tank (11) is sent back to the original liquid tank (1), and the metering pump (2) is turned on and the evaporation treatment is continued; the scale in the replaced short tube (401) is scraped with a medicine spoon, and the total mass of the scale in the short tube is weighed after drying, and plasma water is added to dissolve it. After it is completely dissolved, it is stirred evenly and divided into four equal parts; S2. Filter one of the solutions using a quantitative filter paper, place the filter residue in a muffle furnace and burn it, cool it after burning, grind it into powder, observe and analyze it using a scanning electron microscope to obtain its surface morphology and material composition; S3, the remaining three solutions are filtered using quantitative filter paper to remove the solidified material and insoluble precipitate in the solution to obtain a filtrate; a saturated barium chloride solution is added to the filtrate to precipitate sodium carbonate and sodium sulfate in the form of barium carbonate and barium sulfate, and the filtrate is filtered using quantitative filter paper, and the filter paper and the filtrate are placed in a muffle furnace and burned for 4 hours to obtain a burnt product, and the burnt product is weighed to obtain the total mass of barium carbonate and barium sulfate; concentrated hydrochloric acid is added to the burnt product, and the product is filtered again through quantitative filter paper, placed in a muffle furnace and burned, and weighed to obtain the mass of barium sulfate; wherein the mass fraction of concentrated hydrochloric acid is 50%; The mass a of sodium carbonate is calculated from the mass b of barium carbonate by its relative molecular mass: ; The mass x of sodium sulfate is calculated from the mass y of barium sulfate by its relative molecular mass: The results of three samples were averaged.

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