Method for preparing sludge coal water slurry through sludge pretreatment

Abstract

The invention provides a method for preparing sludge coal slurry by sludge pretreatment, which comprises the following steps: treating sludge by using a modifier and heating and stirring coupling, and then mixing and stirring the pretreated sludge with pulverized coal, water and a dispersing agent to prepare sludge coal water slurry; and adding the crushed raw coal, the pretreated sludge, water and a dispersing agent into a ball mill, and grinding to obtain the sludge coal water slurry. The sludge is pretreated by heating and stirring and coupling with the modifier, so that on one hand, cell walls of microorganisms can be destroyed, protein is easy to biodegrade, and pretreatment reaction is accelerated, and on the other hand, a flocculation structure of the sludge can be destroyed, water in the flocculation structure is released, the fluidity of the sludge is improved, and the water in the sludge is fully utilized; and the water consumption in the pulping process is saved. The method solves the problems that the flocculent structure bundle of the sludge is strong in water property, high in water content and difficult to treat, and finally realizes reduction, recycling and harmless utilization of the sludge.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste resource utilization, and in particular to a method for preparing sludge-water-coal slurry by sludge pretreatment. Technical Background

[0002] Sludge is a solid or fluid substance produced after sewage treatment. Its water content is generally between 50% and 99%. Sludge is mainly composed of organic components, and the solid components include a complex mixture of organic debris, bacterial cells, inorganic particles and colloids. Sludge is formed by the coagulation of suspended solids in water in different ways. It has a loose structure, irregular shape, a reticular structure, high specific surface area, porosity and water content, and poor dehydration performance. Sludge has a high content of organic matter, is easy to rot, has a strong odor, and contains parasite eggs, pathogenic microorganisms, heavy metals such as copper, zinc, and chromium, as well as salts, dioxins and other toxic and harmful substances that are difficult to degrade, which increases the difficulty of sludge treatment, limits the resource utilization of sludge, and seriously affects the utilization value of sludge. Adding a certain proportion of sludge to water-coal slurry can not only utilize the water in the sludge, but also utilize the calorific value of the sludge to achieve the purpose of sludge resource utilization.

[0003] Sludge-water-coal slurry is a sludge disposal technology developed based on water-coal slurry technology. Liquid fuel is prepared by mixing sludge, coal, water and dispersant, and directly applied to existing water-coal slurry boilers and gasifier equipment to reduce utilization costs. In addition, sludge-water-coal slurry technology not only has the ability to treat sludge on a large scale, but also can efficiently recover the calorific value in the sludge, and as the incineration process proceeds, harmful substances in the sludge can be harmlessly treated to a great extent. Therefore, the development of sludge-water-coal slurry technology is of great significance for sludge reduction, resource utilization and harmless utilization.

[0004] CN 213272635 U discloses a sludge-water-coal slurry blending system for a coal-fired boiler, comprising a slurry making tank, a slurry storage tank, a slurry injection device, a controller and corresponding valves. Crushed coal, sludge, additives and water are mixed and sent into the slurry making tank, where sludge-water-coal slurry is made. After filtering the slurry, the sludge-water-coal slurry that meets the requirements is transported to the slurry storage tank by a slurry discharge pump for storage, and the slurry is sent to the injection system by a slurry supply pump to enter the furnace for combustion, thereby achieving the purpose of sludge blending.

[0005] CN 111534339 A discloses a method for preparing water-coal slurry using sludge, comprising the following steps: drying the sludge after sewage treatment to a moisture content of less than 20% and grinding it to pass through a 60-mesh sieve; mixing the sieved sludge with organic hazardous waste; and then grinding it or grinding it together with coal to the particle size required for preparing water-coal slurry to prepare water-coal slurry.

[0006] CN 107164003 A discloses a method for improving the slurrying property of sludge water-coal slurry by using ultrasonic wave to break up sludge flocs, wherein the modified sludge is mixed with coal, slurrying additives, water, etc. to prepare sludge water-coal slurry, or the modified sludge is mixed with finished water-coal slurry, and stirred evenly to prepare sludge water-coal slurry. In the technical solution, the concentration of sludge water-coal slurry is 59%-60%, and the slurrying concentration is relatively low.

[0007] CN 106833778 B discloses a method for preparing water-coal slurry by recycling sludge. The method comprises the following steps: placing the sludge into a microwave high-pressure heating reactor for treatment under the conditions of microwave power of 300-800W, pressure of 20-50MPa and time of 5-15min; mixing the microwave-treated sludge with alkaline printing and dyeing wastewater, coal and a dispersant, and grinding the sludge with a mill to obtain the sludge water-coal slurry.

[0008] The above-mentioned sludge water-coal slurry treatment methods are mainly dehydration and reduction or direct co-combustion, which makes it difficult to fully utilize the moisture and calorific value of the sludge due to its high water content. Therefore, it is necessary to pretreat the sludge before preparing the sludge water-coal slurry, but the currently disclosed technologies have disadvantages such as high power consumption, high pressure, high reagent price, and poor pretreatment effect. Therefore, in view of the high water content and special flocculation structure of the sludge, directly mixing the sludge with coal powder to prepare water-coal slurry will reduce its slurryability or slurry concentration, and the slurry will become unstable. A method for preparing sludge water-coal slurry by sludge pretreatment is invented to increase the amount of sludge added and the slurry concentration, which is of great significance to achieve sludge reduction, resource utilization, and harmless utilization.

[0009] In view of the above-mentioned deficiencies, a sludge pretreatment method is urgently needed in the industry that can effectively solve the problems of strong water binding property and high water content of sludge flocculent structure and at the same time render the harmful substances in the sludge harmless. Summary of the invention

[0010] Based on the above analysis, the present invention proposes a method for preparing sludge coal slurry by sludge pretreatment. That is, the sludge is treated by coupling a modifier and heating and stirring, and then the pretreated sludge is mixed and stirred with coal powder, water, and a dispersant to prepare sludge water-coal slurry, or the crushed raw coal and the pretreated sludge, water, and a dispersant are added to a ball mill and ground to obtain sludge water-coal slurry. The method for preparing sludge water-coal slurry by sludge pretreatment described in the present invention mainly solves the problem that the sludge flocculent structure has strong water binding properties and high water content and is difficult to handle, and directly mixing the sludge with coal powder to prepare water-coal slurry will reduce its slurrying properties or the concentration of the slurry, and the slurry is unstable, thereby achieving sludge reduction, resource utilization, and harmless utilization.

[0011] The present invention is achieved by the following steps:

[0012] The present invention first discloses a method for preparing sludge-water coal slurry by sludge pretreatment, comprising the following steps:

[0013] (1) Mixing sludge, a modifier and water in a certain proportion, and heating and stirring to obtain pretreated sludge;

[0014] (2) mixing the pretreated sludge with coal powder, additives and water and subjecting the mixture to high-speed stirring and shearing to obtain a sludge-water coal slurry;

[0015] Alternatively, the crushed raw coal, pre-treated sludge, water and dispersant are added into a ball mill and ground to obtain sludge-water-coal slurry.

[0016] Due to the strong water binding property and high water content of sludge, the method of the present invention adopts a modifier and heating and stirring coupling to modify the sludge, and coal powder, dispersant and water are added to the pretreated sludge and mixed and stirred to obtain sludge water-coal slurry. By pretreating the sludge by heating, stirring and coupling with a modifier, on the one hand, the cell walls of microorganisms can be destroyed, so that the protein is easy to biodegrade and the pretreatment reaction is accelerated; on the other hand, the flocculation structure of the sludge can be destroyed, so that the water in the flocculation structure is released, the fluidity of the sludge is improved, the water in the sludge is fully utilized, and the amount of water used in the pulping process is saved. After the sludge is pretreated, substances such as proteins and carbohydrates released from the sludge will generate a certain amount of humic acid under certain conditions, which can improve the stability of the sludge water-coal slurry.

[0017] Furthermore, the sludge in step (1) is municipal sludge or industrial sludge, and has a moisture content of 50% to 99%.

[0018] Furthermore, the modifier in step (1) is one or more of sulfuric acid, hydrochloric acid, nitric acid, sodium hydroxide, calcium hydroxide, and hydrogen peroxide.

[0019] Furthermore, in step (1), the mass ratio of the modifier to the sludge is 0.05-0.4:1.

[0020] Furthermore, in step (1), the heating temperature is 25 to 90° C., the heating time is 0.5 h to 6 h, and the stirring speed is 300 r / min to 1000 r / min.

[0021] Furthermore, the dispersant in step (2) is one or more of naphthalene, polycarboxylic acid, fatty acid, and aminosulfonic acid.

[0022] Furthermore, the raw coal in step (2) is one or more of lignite, long flame coal and bituminous coal.

[0023] Furthermore, the sludge-water-coal slurry prepared in step (2) comprises the following raw materials in the following weight ratio: 60-70 parts of coal powder, 0.6-1.5 parts of dispersant, 5-40 parts of pretreated sludge, and 10-30 parts of tap water or deionized water.

[0024] The invention also discloses a sludge-water-coal slurry prepared according to any one of the above preparation methods.

[0025] The beneficial effects of the present invention are:

[0026] (1) The method of the present invention destroys the cell wall of the sludge, breaks the flocculent structure of the sludge, releases bound water, and recycles this water;

[0027] (2) The method of the present invention can not only increase the amount of sludge added, but also ensure a higher slurry concentration of sludge-water coal slurry;

[0028] (3) The method of the present invention can feed the prepared sludge water-coal slurry into the water-coal slurry boiler and gasification furnace equipment, efficiently recover the calorific value in the sludge, and as the incineration process proceeds, the harmful substances in the sludge are rendered harmless to a great extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a process flow chart of a method for preparing sludge-water coal slurry by sludge pretreatment.

[0030] Figure 2 It is a process flow chart of a method for preparing sludge-water-coal slurry by sludge pretreatment as described in Examples 1-3 of the present invention.

[0031] Figure 3 This is a process flow chart of a method for preparing sludge-water-coal slurry by sludge pretreatment as described in Example 4 of the present invention. DETAILED DESCRIPTION

[0032] Example 1

[0033] The sludge used in this embodiment is chemical sludge with a moisture content of 75%; the raw coal powder is obtained by crushing and grinding long flame coal with a moisture content of 6.5%, 1) adding sodium hydroxide reagent to the sludge, and the addition amount condition is 20% NaOH solution; 2) stirring for 1.5 hours at a heating temperature of 90°C and a stirring speed of 400r / min to obtain pretreated sludge; 3) mixing the pretreated sludge with 20% of the dry weight of coal with 170.4g of coal powder, 1.6g of sodium methylenebisnaphthalene sulfonate / polycarboxylate and water, stirring and shearing at a stirring speed of 1000r / min and a processing time of 15min to obtain sludge water-coal slurry.

[0034] When the amount of pre-treated sludge added is 20% of the mass of dry coal powder, the water content is 120g, the water used for pulping is 95g, and 25g of water needs to be removed to obtain sludge water-coal slurry.

[0035] The mass ratio of sodium methylene bisnaphthalene sulfonate to polycarboxylate is 7:3.

[0036] The concentration of the water-coal slurry prepared in this example is 64.87% at 1200 MPa·s. The slurry has good fluidity. After standing for seven days, no precipitation is observed, and the stability is good.

[0037] Example 2

[0038] The sludge used in this embodiment is chemical sludge with a moisture content of 75%; the raw coal powder is obtained by crushing and grinding the long flame coal, 1) adding hydrogen peroxide reagent to the sludge in an amount of 25% H2O2 solution; 2) stirring for 3 hours at a heating temperature of 60°C and a stirring rate of 400r / min to obtain pretreated sludge; 3) mixing 16% pretreated sludge with 178.92g coal powder, 2.4g naphthalene sulfonate and water, stirring and shearing at a stirring rate of 1100r / min for 12min to obtain sludge water-coal slurry.

[0039] The amount of pre-treated sludge added is 16% of the dry coal powder mass, the water content is 96g, and the water used for pulping is 96g. No additional water is needed to directly prepare the sludge water-coal slurry.

[0040] The water-coal slurry prepared in this embodiment has a viscosity of 63.47% at 1200 MPa·s, and the slurry has good fluidity. After standing for seven days, soft precipitates are observed, indicating good stability.

[0041] Example 3

[0042] The sludge used in this embodiment is chemical sludge; the raw coal powder is obtained by crushing and grinding the long flame coal, 1) adding nitric acid solution to the sludge, the addition amount is 20% HNO3 solution; 2) stirring at a heating temperature of 45°C and a stirring rate of 400r / min for 4h to obtain pretreated sludge; 3) mixing 10% of the pretreated sludge by dry weight of coal with 191.7g of coal powder, 2g of naphthalene sulfonate and water, stirring and shearing at a stirring rate of 1200r / min for 10min to obtain sludge water-coal slurry.

[0043] The amount of pre-treated sludge added is 10% of the dry coal powder mass, the water content is 60g, the water used for slurrying is 93.3g, and an additional 33.3g of water is required to prepare sludge water-coal slurry.

[0044] The concentration of the water-coal slurry prepared in this embodiment at 1200 MPa·s is 64.28%, and the slurry has good fluidity. After standing for seven days, soft precipitation is observed, and the stability is good.

[0045] Example 4

[0046] The sludge used in this embodiment is chemical sludge with a moisture content of 75%. 1) Sodium hydroxide reagent is added to the sludge in an amount of 20% NaOH solution, and stirred for 1.5 hours at a heating temperature of 90°C and a stirring rate of 400r / min to obtain pretreated sludge; 2) Long flame coal is crushed and then added to a ball mill with the sludge pretreated in 1), sodium methylenebisnaphthalene sulfonate / polycarboxylate, and water for grinding to obtain sludge water-coal slurry.

[0047] The concentration of the water-coal slurry prepared in this embodiment at 1200 MPa·s is 63.86%, and the slurry has good fluidity. After standing for seven days, soft precipitation is observed, and the stability is good.

[0048] Comparative Example 1

[0049] This embodiment is basically the same as embodiment 1, except that steps 1) and 2) are omitted, 20% pretreated sludge on a dry basis of coal is mixed with 170.4g coal powder, 1.6g sodium methylenebisnaphthalene sulfonate / polycarboxylate and water, and stirred and sheared at a stirring rate of 1000r / min and a processing time of 15min to obtain sludge-water-coal slurry.

[0050] The concentration of the water-coal slurry prepared in this embodiment is 58.83% at 1200 mPa·s, and the slurry has good fluidity.

[0051] Comparative Example 2

[0052] This embodiment is basically the same as embodiment 1, except that: step 1) is omitted, and the pretreated sludge is obtained by stirring at a heating temperature of 90°C and a stirring rate of 400 r / min for 1.5 h; 20% of the pretreated sludge by dry weight of coal is mixed with 170.4 g of coal powder, 1.6 g of sodium methylenebisnaphthalene sulfonate / polycarboxylate and water, and stirred and sheared at a stirring rate of 1000 r / min for a treatment time of 15 min to obtain a sludge-water coal slurry.

[0053] The sludge was stirred at a heating temperature of 90°C and a stirring rate of 400 r / min for 1.5 hours to obtain pretreated sludge; 3) the pretreated sludge was mixed with coal powder, sodium methylene bisnaphthalene sulfonate / polycarboxylate and water, and stirred and sheared at a stirring rate of 1000 r / min for 15 minutes to obtain sludge water-coal slurry.

[0054] The concentration of the water-coal slurry prepared in this embodiment at 1200 mPa·s is 60.51%, and the slurry has good fluidity.

[0055] Comparative Example 3

[0056] This embodiment is basically the same as embodiment 1, except that: step 2) is omitted, sodium hydroxide reagent is added to the sludge, and the addition amount condition is 20% NaOH solution to obtain pretreated sludge; 20% pretreated sludge by dry weight of coal is mixed with 170.4g coal powder, 1.6g sodium methylene bis naphthalene sulfonate / polycarboxylate and water, and stirred and sheared at a stirring rate of 1000r / min and a processing time of 15min to obtain sludge water-coal slurry.

[0057] The concentration of the water-coal slurry prepared in this embodiment is 61.73% at 1200 mPa·s, and the slurry has good fluidity.

[0058] In summary, the present invention provides a method for preparing sludge-water-coal slurry by sludge pretreatment, which mainly solves the problems of high water content and difficult treatment of sludge, small blending amount and low slurry concentration, and provides an effective technical path for sludge reduction, harmlessness and resource utilization.

[0059] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which belong to the scope of protection of the present invention.

Claims

1. A method for preparing sludge-water coal slurry by sludge pretreatment, comprising: (1) Mixing sludge, a modifier and water in a certain proportion, heating and stirring to obtain pretreated sludge; (2) mixing the pretreated sludge with coal powder, additives and water and subjecting them to high-speed stirring and shearing to obtain sludge-water coal slurry; or The crushed raw coal, pre-treated sludge, water and dispersant are added into a ball mill and ground to obtain sludge-water-coal slurry.

2. The method according to claim 1, wherein: The sludge in step (1) is municipal sludge or chemical sludge; The water content of the sludge is 50% to 99%.

3. The method according to claim 1, wherein: The modifier in step (1) is one or more of acids, bases and hydrogen peroxide.

4. The method according to claim 3, wherein: The acids include: sulfuric acid, hydrochloric acid, nitric acid; The alkalis include sodium hydroxide and calcium hydroxide.

5. The method according to claim 1, wherein: In step (1), the mass ratio of the modifier to the sludge is 0.05-0.4:

1.

6. The method according to claim 1, wherein: The heating temperature in step (1) is 25-90° C., the heating time is 0.5 h-6 h, and the stirring speed is 300 r / min-1000 r / min.

7. The method according to claim 1, wherein: The coal powder in step (2) is one or more of lignite, long flame coal and bituminous coal.

8. The method of claim 1, wherein: The dispersant in step (2) is one or more of naphthalene, polycarboxylic acid, fatty acid, and aminosulfonic acid.

9. The method according to claim 1, wherein: The sludge-water-coal slurry prepared in step (2) comprises the following raw materials in proportion by weight: 60-70 parts of coal powder, 0.6-1.5 parts of dispersant, 5-40 parts of pretreated sludge, 10-30 parts of tap water or deionized water.

10. A sludge-water-coal slurry prepared according to the method according to any one of claims 1 to 9.

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