CN115093888A - A method for preparing water coke slurry by mixing blue carbon powder with ultrasonically modified sludge - Google Patents

Abstract

The invention discloses a method for preparing water coke slurry by mixing blue carbon powder with ultrasonically modified sludge. The sludge is modified and pretreated by ultrasonic means to destroy the floc structure of the sludge, and then a suitable dispersant is added to prepare the sludge. A high-performance slurry is produced, and the sludge is first put into an ultrasonic generator for pretreatment, and the mechanical action of ultrasonic waves is used to promote the dispersion of the sludge floc structure and the rupture of the microbial cell wall in the sludge, and release the flocs and cells. Moisture, reduce particle density, and in the process of ultrasonic action, it can promote the decomposition of refractory organic matter and the release of organic matter, nitrogen and phosphorus, improve the bioavailability of organic matter, and then obtain modified sludge; through crushing, mixing, grinding and In the screening process, the blue carbon is divided into five different particle size grades. The dry pulping process is used. The modified sludge is mixed with blue carbon powder, and then mixed with water and dispersant evenly. Sludge water coke slurry.

Description

A method for preparing water coke slurry by mixing blue carbon powder with ultrasonically modified sludge

technical field

The invention relates to a method for preparing water coke slurry by mixing ultrasonically modified sludge with blue carbon powder, in particular to using ultrasonic wave to pretreat sludge, and mixing modified sludge, blue carbon powder, dispersant and water to prepare sludge water coke The technical method of using ultrasonic mechanical action to break the sludge floc structure and prepare high-performance modified sludge water coke slurry.

Background technique

With the continuous increase of urban sewage production in China, the production of urban sewage sludge has also increased sharply. Direct discharge of sewage sludge into soil or water bodies can cause serious environmental pollution and health problems if untreated or improperly treated. The sludge has high water content, is perishable, has a strong odor, contains a large number of pathogenic bacteria, parasite eggs, heavy metals such as chromium, mercury, and dioxins and other toxic, harmful and carcinogenic substances that are difficult to degrade. Therefore, it is of great significance to find a cost-effective and environmentally friendly way to treat sludge.

Therefore, it is of great significance to find a cost-effective and environmentally friendly way to treat sludge. A coal-water slurry is a highly concentrated suspension in which pulverized coal is dispersed in water. The CWS should exhibit the highest possible solids loading, good fluidity and stability in industrial applications. A new method of sludge treatment is to add sludge to CWS to prepare sludge CWS, which can be used as boiler fuel or gasification feed, which also meets the needs of sustainable development, not only for sewage The water and calorific value in the sludge are fully utilized to achieve the goal of energy and resource utilization of the sludge. This method has a major impact on the treatment of sewage sludge.

my country's blue carbon resources are abundant, but for blue carbon powder with a particle size of less than 6mm, because the particle size does not meet the production requirements, it is discarded and stored in rivers or fields, or directly sold as low-cost fuel, resulting in a great waste of resources. In order to prevent dust pollution and improve economic benefits, people have gradually explored the field of water coke slurry. As a new liquid fuel after coal-water slurry, it is also composed of 60% to 70% of blue carbon, 30% to 40% of water and 1% to 2% of additives. Mixing sludge to prepare water coke slurry is a new method for sludge treatment. The method not only eliminates harmful microorganisms and solidifies heavy metals in the sludge, but also fully utilizes the moisture and calorific value of the sludge, which is of great significance to the energy and resource utilization of the sludge.

In addition, due to the relatively developed floc structure and strong water interception force of the sludge, it is easy to bind water in the floc, resulting in the reduction of free water and the poor fluidity of the slurry; a large amount of gas will also be stored in the developed floc structure. Reduce the service life of the slurry. Therefore, in order to destroy the floc structure of the sludge, ultrasonic modification is used for pretreatment; in order to effectively exert the effect of the additive, it is necessary to use blue carbon powder as the raw material and select a suitable dispersant. Based on this, a complete system for the preparation of modified sludge-water coke slurry is realized.

SUMMARY OF THE INVENTION

The invention overcomes the deficiencies in the prior art, and provides a method for preparing water coke slurry with ultrasonically modified sludge mixed with blue carbon powder, so that the performance of the slurry is obviously improved, and a theoretical foundation is laid for the subsequent application and promotion of the slurry. The sludge is modified and pretreated by ultrasonic means to destroy the floc structure of the sludge, and then a suitable dispersant is added to prepare a high-performance slurry.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is: a method for preparing water coke slurry by mixing blue carbon powder with ultrasonically modified sludge, which is carried out according to the following steps:

The first step is to put the sludge into the ultrasonic generator for pretreatment, and use the mechanical action of ultrasonic waves to promote the dispersion of the sludge floc structure and the rupture of the microbial cell wall in the sludge, and release the water in the flocs and cells, Reduce the particle density, in the process of ultrasonic action, it can promote the decomposition of refractory organic matter and the release of organic matter, nitrogen and phosphorus, improve the bioavailability of organic matter, and then obtain modified sludge;

In the second step, the northern Shaanxi Shenfu orchid charcoal powder is divided into five different particle size grades, which are 20 to 40, respectively, according to the particle size grading of the Texaco gasification process. Mesh, 40-120 mesh, 120-200 mesh, 200-325 mesh and larger than 325 mesh;

The third step is to use the dry pulping process to mix the modified sludge in the first step and the blue carbon powder in the second step, mix with water and dispersant evenly, and use the pulping stirring device to fully stir to obtain a uniform Sludge water coke slurry.

The operating conditions of the ultrasonic generating device are as follows: the frequency is 27 kHz, the amplitude is 50%, the current is 0.35 A, and the ultrasonic time is 60-240 min.

The mass ratio relationship of each raw material component of the sludge water coke slurry is as follows:

Using dried sludge: dry orchid carbon powder = 10:100, dispersant: dry orchid carbon powder = 0.8:100.

The sludge is the product after mechanical dehydration of the municipal sewage treatment plant, and its moisture content is 90%.

The pulping dispersing agent adopts an anionic compound dispersing agent, and in the mass ratio relationship, sodium salt of naphthalenesulfonic acid formaldehyde polymer: polycarboxylate water reducing agent=0.5:0.5.

The sludge water coke slurry of the finished product is prepared by using blue carbon powder, modified sludge, dispersant and water.

Compared with the prior art, the present invention has the following beneficial effects: the present invention utilizes ultrasonic waves to modify the sludge, the amount of negative charges on the surface of the sludge particles increases, and the sludge is exposed to ultrasonic waves to destroy flocs and microbial cell walls, and releases the The water and particle density in the flocs and cells are increased, and then the modified sludge is mixed with blue carbon powder, dispersant, and distilled water to prepare water coke slurry, which can significantly reduce the apparent viscosity of the sludge water coke slurry and improve the Its slurry concentration, stability and fluidity can obtain sludge water coke slurry with excellent performance. The invention adopts low-frequency ultrasonic wave to pretreat the modified sludge, has low energy consumption, short pretreatment time, simple method and easy realization; the apparent viscosity can be reduced by more than 42%, the slurry concentration can be increased by more than 1.7 percentage points, and the water separation rate can be reduced to 0%, the fluidity is linear, and no precipitation occurs after standing for 7 days. Compared with the existing technology, the cost of transportation is reduced, and the economical value of the sludge water coke slurry is increased; the sludge water coke slurry is improved. It improves the pulping performance, improves the pulping concentration, realizes the utilization of sludge energy and resources, and also meets the needs of sustainable development.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is a schematic diagram of the process flow of mixing ultrasonically modified sludge with blue carbon powder, dispersant and water to prepare sludge-water coke slurry in the present invention.

Figure 2 is a schematic diagram of the influence of ultrasonically modified sludge on the rheology of sludge water coke slurry in the present invention.

Fig. 3 is a schematic diagram showing the influence of modified sludge on the maximum slurry concentration of sludge water coke slurry in the present invention.

Detailed ways

As shown in Fig. 1, Fig. 2 and Fig. 3, the present invention utilizes ultrasonic wave to modify sludge, and the negative charge on the surface of sludge particles increases, exposing the sludge to ultrasonic waves to destroy flocs and microbial cell walls, and release flocs and the water in the cells, the particle density has been improved, and then the modified sludge is mixed with blue carbon powder, dispersant and distilled water to prepare water coke slurry, which can significantly reduce the apparent viscosity of the sludge water coke slurry and improve its composition. The slurry concentration, stability and fluidity can be obtained to obtain sludge water coke slurry with excellent performance.

Example 1

The sludge is taken from the mechanically dewatered sludge produced by a sewage treatment plant, and the mechanically dehydrated sludge is put into an oven for drying for ultrasonic modification and subsequent preparation of sludge water coke slurry. The ultrasonic processing system in the multifunctional microwave synthesis extractor is adopted. The device consists of three parts: ultrasonic vibration head, driving power box and fixed sleeve. The frequency of the control ultrasound was 27 kHz, the amplitude was 50%, the current was 0.35 A, and the ultrasonic treatment time was set at 60, 120, 180 and 240 min.

When the modified sludge is mixed with blue carbon powder to prepare sludge water coke slurry, the mass ratio relationship of each raw material component is: dried sludge: dry blue carbon powder = 10:100, dispersant: dry blue carbon powder = 0.8:100. The dispersing agent is an anionic compound dispersing agent (naphthalenesulfonic acid formaldehyde polymer sodium salt: polycarboxylate water reducing agent=0.5:0.5). The solid mass concentration of the prepared sludge water coke slurry is 65%.

The apparent viscosity of the slurry was measured using a rotational viscometer.

As shown in Figure 2, the effect of ultrasonic modification of sludge on the rheology of sludge water coke slurry. It can be seen from Figure 2 that the apparent viscosity of the sludge water coke slurry decreases with the increase of the shear rate, showing the behavior of shear thinning, which has the characteristics of a pseudoplastic fluid. High viscosity can increase the difficulty of particle settling at low shear rates, low viscosity can reduce transportation costs at high shear rates, and pseudoplastic behavior is also key to preventing clogging of atomizing nozzles. Therefore, the addition of modified sludge had a positive effect on the pseudoplastic behavior of the sludge water coke slurry, and the apparent viscosity of the slurry decreased significantly; with the increase of the shear rate, the apparent viscosity gradually decreased, showing a pseudoplastic behavior fluid. The addition of modified sludge can significantly improve the rheological properties of sludge water coke slurry.

The rheology of water coke pulp is an important index for evaluating water coke pulp, which has a great influence on storage and transportation. The Herschel-Bulkley model was used to describe the rheology of the modified sludge water coke slurry.

The calculation formula is: τ=τ ₀ +K·γ ⁿ ;

In the formula: n——rheological coefficient, representing the degree to which the blue carbon pulp deviates from the Newtonian fluid;

K——Consistency coefficient, Pa· ^sn ;

τ——shear stress, Pa;

γ——shear rate, s ^-1 ;

τ ₀ ——Yield stress, Pa.

When n<1, the slurry is a pseudoplastic fluid with "shear-thinning"; when n>1, the slurry is a swelling-plastic fluid with "shear-thickening"; if n=1, it is a Newtonian fluid fluid. Generally speaking, the larger the concentration of the slurry, the larger the K value, the smaller the n value, and the more obvious the pseudoplasticity. From the parameter changes in Table 1, it can be seen that the rheological index n value of the modified sludge water coke slurry is less than 1, indicating that the slurry is a pseudoplastic fluid. In addition, with the different ultrasonic time of sludge, the consistency coefficient K of sludge water coke slurry changes; when the ultrasonic time is 240min, the value of rheological index n is the largest, and the value of consistency coefficient K is the smallest. A stable spatial structure is formed between the organic matter and water molecules, which hinders the relative motion of solid particles.

Table 1. Fitting parameters of rheological model of sludge water coke slurry prepared by ultrasonically modified sludge

In order to further study the effect of modified sludge on the apparent viscosity and stability of sewage coke slurry. It can be seen from Table 2 that the apparent viscosity of the sludge water coke slurry prepared from the original sludge is 711.2 mPas, the water separation rate in 7 days is 6.09%, and there is hard precipitation and poor stability. The addition of modified sludge significantly reduced the apparent viscosity of the sludge water coke slurry, the water separation rate was 0% in 7 days, and no hard precipitation was produced. When the ultrasonic time was 240min, the apparent viscosity of the sludge water coke slurry prepared from the modified sludge was 407.8 mPas, and the slurry viscosity was reduced by 42% compared with the original sludge water coke slurry. The untreated raw sludge floc has a loose structure, rich internal void structure and strong water retention capacity, and the raw sludge contains a large number of cell structures and microorganisms. The untreated sludge is mixed with blue carbon powder. In the preparation of water coke slurry, sludge particles, blue carbon particles and water molecules form a network structure to improve the stability of the slurry, but water still easily enters the floc structure of the sludge, making the pulping ability worse. When the sludge is under the action of ultrasonic waves, the floc structure of the sludge is decomposed, the microbial cell wall is broken, the water in the cell tissue is released, the pore structure of the sludge is changed, and the particle size becomes smaller, which is conducive to particle size grading. There are a large number of oxygen-containing functional groups on the surface of the modified sludge particles, which form stable hydrogen bonds with water and form a hydration film with the blue carbon powder particles, which effectively prevents the aggregation and precipitation between the blue carbon particles.

Table 2. The effect of ultrasonic modification of sludge on the effect of sludge water coke slurry

Example 2

The sludge is taken from the mechanically dewatered sludge produced by a sewage treatment plant, and the mechanically dehydrated sludge is put into an oven for drying for ultrasonic modification and subsequent preparation of sludge water coke slurry. The ultrasonic processing system in the functional microwave synthesis extractor is composed of three parts: ultrasonic vibration head, driving power box and fixed sleeve. The frequency of control ultrasound was 27 kHz, the amplitude was 50%, the current was 0.35 A, and the time of ultrasonic treatment was set to 240 min.

When the modified sludge is mixed with blue carbon powder to prepare sludge water coke slurry, the mass ratio relationship of each raw material component is: dried sludge: dry blue carbon powder = 10:100, dispersant: dry blue carbon powder = 0.8:100. The dispersing agent is an anionic compound dispersing agent (naphthalenesulfonic acid formaldehyde polymer sodium salt: polycarboxylate water reducing agent=0.5:0.5). The solid mass concentration of the prepared sludge water coke slurry is 63%, 65%, 67% and 69%.

The apparent viscosity of the slurry was measured using a rotational viscometer.

In this example, the original sludge and modified sludge were mixed with blue carbon powder to prepare sludge water coke slurry and modified sludge water coke slurry, and the maximum slurry concentration was measured. The results are shown in Figure 3. With the increase of the concentration of sludge water coke slurry and modified sludge water coke slurry, it showed a similar increasing trend. The maximum pulping concentration increased to 66.7% after the original sludge was mixed with blue carbon powder, and the maximum pulping concentration was increased to 68.4% after the modified sludge was mixed with blue carbon powder. The floc structure of sludge is the main reason affecting its pulpability. The sludge flocs have strong hydrophilicity and abundant internal pores. These characteristics make the sludge have a strong water interception ability, and more water is retained in the sludge flocs, and the retained water cannot flow freely; After the floc structure is destroyed, the trapped water will be released, thereby increasing the proportion of free water in the water coke slurry system. Therefore, a high-concentration slurry can be prepared.

Example 3

The sludge is taken from the mechanically dewatered sludge produced by a sewage treatment plant. The mechanically dehydrated sludge is put into an oven for drying for ultrasonic modification and subsequent preparation of sludge water coke slurry, and ultrasonic pretreatment for 240min modification. The sludge and the original sludge were used for the adsorption test. The NNO/PCE dispersant solution with a concentration of 1000mg/L was prepared. The rod was initially stirred, and then placed in a constant temperature water bath oscillator, the water bath temperature was set to 25 °C, and the shaking rate was 150 rpm, and the shaking was 1, 2, 5, 8, 10, 20, 30, 60, 120, 240, 300 respectively. , 360min, then let the suspension sample stand for 30min, transfer an appropriate volume of the upper layer liquid into a centrifuge tube, centrifuge at 8000rpm for 10min with a high-speed centrifuge, centrifuge twice, and separate the supernatant. Calculate the adsorption capacity and compare the adsorption capacity at different times.

The relationship between the adsorption amount when the adsorption reaches equilibrium and the equilibrium concentration of the solution can be represented by the adsorption isotherm. By studying the adsorption isotherm of the dispersant on the modified sludge surface, the adsorption efficiency and the maximum adsorption degree of the modified sludge particles to the dispersant were obtained, and the adsorption law of the dispersant to the modified sludge particles was revealed. The experiment investigated the isotherm adsorption law of dispersant on the surface of modified sludge particles at 25℃. The concentration of dispersant was controlled from 0 to 2000 mg/L, including 100, 200, 300, 400, 500, 600, 800, 1000, 1500 and 2000 mg/L, and the adsorption time was 360 min.

The amount of adsorption was measured with a UV-2000 UV-Vis spectrophotometer.

In this embodiment, the dispersant molecules can be adsorbed on the surface of the sludge particles, changing the surface properties of the sludge particles, reducing the free energy, and at the same time forming a hydration film of a certain thickness, which effectively enhances the steric hindrance of the sludge water coke slurry. Reduce the viscosity of the slurry. With the increase of dispersant concentration, the adsorption capacity of dispersant began to increase rapidly, and then reached a plateau at high concentration, showing the characteristics of monolayer adsorption; isothermal saturation adsorption of dispersant molecules on the surface of sludge and modified sludge particles The amount of sludge was 8.541mg/g and 8.783mg/g respectively; the effect of adsorption time on the adsorption capacity was 8.336mg/g for sludge and 8.731mg/g for modified sludge; ultrasonic modification could improve the effect of sludge particles on dispersant. So as to improve the pulping performance of the slurry.

The present invention has been described in detail above in conjunction with the embodiments, but the present invention is not limited to the above-mentioned embodiments, and within the knowledge scope possessed by those of ordinary skill in the art, various changes can be made without departing from the purpose of the present invention.

Claims (6)

1. a method for preparing water coke slurry by ultrasonically modified sludge mixing blue carbon powder, is characterized in that, executes according to the following steps: The first step is to put the sludge into the ultrasonic generator for pretreatment, and use the mechanical action of ultrasonic waves to promote the dispersion of the sludge floc structure and the rupture of the microbial cell wall in the sludge, and release the water in the flocs and cells, Reduce the particle density, in the process of ultrasonic action, it can promote the decomposition of refractory organic matter and the release of organic matter, nitrogen and phosphorus, improve the bioavailability of organic matter, and then obtain modified sludge; In the second step, the northern Shaanxi Shenfu orchid charcoal powder is divided into five different particle size grades, which are 20 to 40, respectively, according to the particle size grading of the Texaco gasification process. Mesh, 40-120 mesh, 120-200 mesh, 200-325 mesh and larger than 325 mesh; The third step is to use the dry pulping process to mix the modified sludge in the first step and the blue carbon powder in the second step, mix with water and dispersant evenly, and use the pulping stirring device to fully stir to obtain a uniform Sludge water coke slurry. 2. The method for preparing water coke slurry by mixing blue carbon powder with ultrasonically modified sludge according to claim 1, wherein the operating conditions of the ultrasonic generating device are: the frequency is 27kHz, the amplitude is 50%, The current is 0.35A, and the ultrasonic time is 60-240min. 3. the method for preparing water coke slurry by a kind of ultrasonic modified sludge mixed with blue carbon powder according to claim 1, is characterized in that, the mass proportion relation of each raw material component of described sludge water coke slurry is as follows, Using dried sludge: dry orchid carbon powder = 10:100, dispersant: dry orchid carbon powder = 0.8:100. 4. the method for preparing water coke slurry by mixing blue carbon powder with ultrasonically modified sludge according to claim 1, is characterized in that, described sludge is the product after the mechanical dehydration of municipal sewage treatment plant, and its moisture content is 90%. 5. a method for preparing water coke slurry by mixing blue carbon powder with ultrasonically modified sludge according to claim 1, is characterized in that, described pulping dispersing agent adopts anionic compound dispersing agent, and the mass ratio relationship Medium naphthalenesulfonic acid formaldehyde polymer sodium salt: polycarboxylate water reducing agent=0.5:0.5. 6. The method for preparing water coke slurry by mixing blue carbon powder with ultrasonically modified sludge according to claim 1, it is characterized in that, the sludge water coke slurry described in the finished product is the use of blue carbon powder, modified sludge, The dispersant is formulated with water.

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