CN113666597B - A kind of additive for pyrolysis of hazardous waste sludge and pyrolysis treatment method - Google Patents

Abstract

The invention discloses an additive for hazardous waste sludge pyrolysis, which is a calcined additive obtained by calcining ground natural ores, or a calcined additive obtained by calcining ground natural ores, mixing the calcined additive, nickel salt and ultrapure water, stirring, drying and calcining. The invention also discloses a hazardous waste sludge pyrolysis treatment method, which comprises the following steps: drying the dangerous waste sludge to constant weight; the method comprises the following steps of (1) placing hazardous waste sludge and additives in a pyrolysis furnace in a segmented manner, and enabling the additives to be closer to a pyrolysis gas outlet of the pyrolysis furnace; and carrying out pyrolysis treatment on the hazardous waste sludge in the nitrogen atmosphere, and collecting pyrolysis gas. The additive can effectively improve the yield and the product quality of the pyrolysis of the hazardous waste sludge and obtain the hydrogen-rich synthesis gas with high added value.

Description

A kind of additive for pyrolysis of hazardous waste sludge and pyrolysis treatment method

technical field

The invention belongs to the field of hazardous waste treatment, in particular to the field of hazardous waste sludge treatment, and relates to an additive for hazardous waste sludge pyrolysis and a hazardous waste sludge pyrolysis treatment method. The dissolved additives are suitable for hazardous waste sludge such as oily sludge, printing and dyeing sludge, pickling sludge, electroplating sludge and medical sludge.

Background technique

The stock of hazardous waste sludge in my country is huge, and a large amount of new hazardous waste sludge is produced every year. According to incomplete statistics, the total amount of oily sludge produced in the petrochemical mining process is about 8×10 ⁶ tons per year. Hazardous waste sludge is a mixture of various hydrocarbons, water, heavy metals and solid particulate matter, which contains organic matter. Direct incineration or landfill will undoubtedly cause a great waste of resources; secondly, hazardous waste sludge itself not only contains A large number of toxic and harmful compounds (benzene, polycyclic aromatic hydrocarbons, etc.), and bacteria, parasites and heavy metals (Hg, Cu, Cr, Zn, etc.) that wrap pathogens, etc., if they are directly discharged without treatment, will be harmful to soil, water and human health. will cause immeasurable damage.

The existing hazardous waste sludge treatment methods include extraction, biological method, incineration, solidification and pyrolysis. Among them, pyrolysis of hazardous waste sludge is a process with good application prospects. High-temperature catalytic pyrolysis can effectively kill bacteria and parasites in hazardous waste sludge, and has high treatment efficiency for toxic and harmful organic matter, and can obtain high-efficiency The value-added hydrogen-rich syngas realizes the reduction, harmlessness and resource utilization of hazardous waste sludge. The existing additives for the pyrolysis of hazardous waste sludge are mainly artificially synthesized nickel-based catalysts and molecular sieves, which have the disadvantages of high cost, low output, poor mechanical strength, large energy consumption, low resource utilization efficiency, low product added value, and poor economy. question.

In view of this, it is particularly important to design an additive for the pyrolysis of hazardous waste sludge.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the problems existing in the prior art, and provide an additive for pyrolysis of hazardous waste sludge. The additive has the characteristics of wide source, low cost, high efficiency and high mechanical strength. Hazardous waste sludge can greatly increase the volume fraction and yield of _H2 in the pyrolysis gas, with better economic benefits.

To achieve the above object, the present invention provides the following technical solutions:

An additive for pyrolysis of hazardous waste sludge, the additive is a calcining additive obtained by grinding natural ore and then calcining, or grinding a natural ore and then calcining to obtain a calcining additive, and then adding Ultrapure water (ie deionized water) is mixed, fully stirred so that the nickel salt is evenly loaded on the calcined additive, and the obtained nickel-loaded additive is calcined after drying.

Described natural ore is the natural mineral containing Fe, Mg, Ca, Si; Preferably, described natural ore is any one in olivine (OL), Xiuyan jade (XY), edinite (ID) species or a mixture of multiple species.

The natural ore is ground to a particle size of 0.2-0.3 mm.

The calcination conditions are as follows: in an air atmosphere, at a heating rate of 5°C/min to 20°C/min, the temperature is raised from normal temperature to 800°C to 1000°C, and the constant temperature time is 2 to 6 hours to obtain a calcined additive with developed pores, which is convenient for follow-up. Nickel loaded. The calcined additives corresponding to olivine (OL), xiuyan jade (XY) and edinite (ID) are calcined olivine (C-OL), calcined xiuyan jade (C-XY), calcined edinite (C-OL), respectively. -ID).

Preferably, the calcination conditions are as follows: in an air atmosphere, at a heating rate of 10°C/min, the temperature is raised from normal temperature to 900°C, and the temperature is kept constant for 4 hours.

The nickel salt is any one or a mixture of nickel nitrate hexahydrate and nickel chloride.

The mass ratio of the calcining additive, nickel salt and ultrapure water is (5-8):(2-4):(100-200), preferably 5:2:100. The method of controlling the amount of ultrapure water is not only beneficial to the hydrolysis of the nickel salt and the dispersion of the natural ore, but also to the subsequent stirring, so that the nickel is loaded more uniformly.

The stirring is mechanical stirring, the rotating speed is 300r/min～500r/min, and the stirring time is 10～14 hours.

The drying temperature was 105°C, and the drying was carried out to constant weight.

The re-calcining conditions are as follows: in an air atmosphere, the temperature is raised to 800° C. to 1000° C. at 5° C./min to 20° C./min, and the constant temperature is 2 to 6 hours to obtain the nickel-carrying additive. The nickel-loaded additives corresponding to olivine (OL), Xiuyan jade (XY), and edinite (ID) are nickel-loaded calcined olivine (C-OL (Ni)), calcined Xiuyan jade (C-XY (Ni), respectively. )), calcined edinite (C-ID(Ni)).

Preferably, the re-calcining conditions are as follows: in an air atmosphere, the temperature is raised from normal temperature to 900° C. at a heating rate of 10° C./min, and the constant temperature is 4 hours.

Another object of the present invention is to provide a method for pyrolysis treatment of hazardous waste sludge, comprising the following steps:

Step (1), pretreatment of hazardous waste sludge: drying the hazardous waste sludge to constant weight;

Step (2), placing hazardous waste sludge and additives: placing the hazardous waste sludge and additives in the pyrolysis furnace in sections, so that the additives are closer to the pyrolysis gas outlet of the pyrolysis furnace;

Step (3), pyrolysis of hazardous waste sludge: in a nitrogen atmosphere, pyrolysis of hazardous waste sludge is performed to collect pyrolysis gas.

The hazardous waste sludge is a mixture of any one or more of oily sludge, printing and dyeing sludge, pickling sludge, electroplating sludge and medical sludge. The total content of saturated hydrocarbons and aromatic hydrocarbons in the hazardous waste sludge is greater than 15%.

In step (1), preferably, the hazardous waste sludge pretreatment: screening out impurities in the hazardous waste sludge, pulverizing, and drying to constant weight.

In step (2), the mass ratio of the hazardous waste sludge to the additive is (5-8):(1-3), preferably 2.5:1.

The pyrolysis furnace is a vertical pyrolysis furnace, and the reaction part of the vertical pyrolysis furnace is a quartz tube. The quartz tube is vertically installed in the vertical pyrolysis furnace, and a heating device is provided around the quartz tube in the vertical pyrolysis furnace. In the lower part of the vertical pyrolysis furnace, a heating belt is installed to heat the bottom of the quartz tube to prevent the pyrolysis gas from condensing in advance.

A perforated additive platform and a bottom perforated hazardous waste sludge platform that can move up and down inside the pyrolysis furnace are installed from bottom to top in the pyrolysis furnace, and the hazardous waste sludge is placed in the hazardous waste sludge. On the platform, the additive is placed on the additive platform, and the hazardous waste sludge is controlled not to contact the additive, and the distance between the hazardous waste sludge and the additive is generally maintained at 150-250mm.

The hazardous waste sludge platform can be a quartz hanging basket.

Preferably, quartz wool is laid on the hazardous waste sludge platform, and then the hazardous waste sludge is placed; quartz wool is laid on the additive platform, and additives are then placed.

In step (3), nitrogen is introduced from the upper part of the pyrolysis furnace, and in a nitrogen atmosphere, the hazardous waste sludge is pyrolyzed, and the pyrolysis gas is brought out of the pyrolysis furnace from the lower part by the nitrogen as power. The air bag collects the pyrolysis gas.

The temperature of the pyrolysis treatment is 700°C to 900°C, and the time of the pyrolysis treatment is 30min to 90min.

The pyrolysis gas is hydrogen-rich synthesis gas, which can be reused.

As a further technical solution of the method for pyrolysis treatment of hazardous waste sludge according to the present invention, the method further includes recycling the pyrolysis residue.

Compared with the prior art, the beneficial effects of the present invention:

1. The additive of the present invention has more metal catalytic components such as Ni, Fe, Mg, Ca, etc., has high catalytic activity, and can efficiently convert toxic and harmful compounds (benzene, polycyclic aromatic hydrocarbons, etc.) into flammable small molecules Hydrocarbons are reused.

2. The surface of the additive of the present invention has abundant pores and capillary structure, which is beneficial to the mass transfer and heat transfer in the pyrolysis process of hazardous waste sludge, so that the pyrolysis efficiency is higher, and the active components are uniformly dispersed, and the catalytic effect is good.

3. The additive of the present invention uses natural ore as raw material, has a wide range of sources, simple processing technology, low cost, high efficiency and high mechanical strength.

4. The additive of the invention can effectively improve the output and product quality of the pyrolysis of hazardous waste sludge, and obtain high value-added hydrogen-rich synthesis gas. The main components of the pyrolysis gas are CH ₄ , H ₂ , CO and CO ₂ . Additives C-OL, C-XY, C-OL(Ni), C-XY(Ni), C-ID(Ni) can effectively improve the temperature at 700℃～900℃, especially at 900℃. The total pyrolysis gas production and _H2 production of the pyrolysis of hazardous waste sludge, among which C-XY(Ni) has the best effect. The additive C-ID can significantly increase the CO production of hazardous waste sludge pyrolysis, and the CO yield exceeds 55%, which is suitable for the CO conversion of hazardous waste sludge pyrolysis.

Description of drawings

Figure 1 is the SEM and EDX micrographs of different additives; among them, a: SEM photo of C-OL, b: SEM photo of C-OL(Ni), c: EDX photo of C-OL(Ni), d: SEM image of C-XY, e: SEM image of C-XY(Ni), f: EDX image of C-XY(Ni), g: SEM image of C-ID, h: SEM image of C-ID(Ni) Photograph, i: EDX photograph of C-ID(Ni).

Fig. 2 is an oily sludge pyrolysis test device. In Figure 2, 1-N ₂ bottles; 2-Gas mass flow controller; 3-Quartz tube; 4-Vertical fixed bed reactor; 5-Quartz hanging basket; 51-Hazardous waste sludge sample; 52-Quartz wool ; 53-hole; 6-additive platform; 61-additive sample; 62-quartz wool; 63-platform hole; 7-heating belt; 8-gas condensation device; 9-gas purification device; 10-air bag; 11 - 1st valve; 12 - 2nd valve.

Figure 3 shows the gas production results from the pyrolysis of oily sludge alone.

Figure 4 shows the gas production results of oily sludge pyrolysis with C-OL additive.

Figure 5 shows the gas production results of oily sludge pyrolysis with C-XY additives.

Figure 6 shows the gas production results of oily sludge pyrolysis under C-ID additive.

Figure 7 shows the gas production results of oily sludge pyrolysis with C-OL(Ni) additive.

Figure 8 shows the gas production results of oily sludge pyrolysis with C-XY(Ni) additives.

Figure 9 shows the gas production results of oily sludge pyrolysis with C-ID(Ni) additive.

Detailed ways

The technical solutions of the present invention will be further described below through specific embodiments.

Example 1

Take olivine (OL), first grind it to 60 mesh (ie 0.25mm) to facilitate olivine calcination to be more complete, and then calcinate in an air atmosphere: at a heating rate of 10 °C/min, from room temperature to 900 °C, constant temperature calcination for 4 1 hour, the calcined olivine (denoted as: C-OL) with developed pores was obtained.

Weigh 5g of calcined olivine (C-OL), put it into a 250mL glass cup, then weigh 2g of nickel chloride solid powder, put it into it, add deionized water (100mL) while stirring with the glass cup; After the liquid is in a turbid state, put the stirring rod of the stirrer into it, stir at a speed of 400r/min for 12 hours until the mixture is uniform, so that the nickel chloride is evenly loaded on the calcined olivine; Constant weight, then placed in a muffle furnace, heated from room temperature to 900 °C at a heating rate of 10 °C/min, calcined at 900 °C for 4 h, then the solid powder was taken out, cooled, and crushed to 60 mesh to obtain nickel-loaded calcination. Olivine (denoted as: C-OL(Ni)), stored in a sample bag.

Example 2

Take Xiuyan jade (XY), first grind it to 60 mesh, and then calcinate in air: at a heating rate of 10°C/min, the temperature is raised from room temperature to 900°C, and calcined at a constant temperature for 4 hours to obtain calcined Xiuyan jade with developed pores ( Denoted as: C-XY).

Weigh 5g of calcined Xiuyan jade (C-XY), put it into a 250mL glass cup, then weigh 2g of nickel chloride solid powder, put it into it, add deionized water (100mL) while stirring with a glass cup; After the mixture liquid is in a turbid state, put the stirring rod of the stirrer in it, the speed is 400r/min, and stir for 12 hours; then it is placed in an oven, dried at 105 °C to constant weight, and then placed in a muffle furnace. 10°C/min, heated from room temperature to 900°C, calcined at a constant temperature of 900°C for 4 hours, then the solid powder was taken out, cooled, and crushed to 60 mesh to obtain nickel-loaded calcined Xiuyan jade (denoted as C-XY(Ni)) , stored in the sample bag.

Example 3

Take edinite (ID), first grind it to 60 mesh, and then calcinate in an air atmosphere: at a heating rate of 10°C/min, the temperature is raised from room temperature to 900°C, and calcined at a constant temperature for 4 hours to obtain calcined edinite with developed pores ( Note as: C-ID).

Weigh 5g of calcined edinite (C-ID), put it into a 250mL glass cup, then weigh 2g of nickel chloride solid powder, put it into it, add deionized water (100mL) and stir with the glass cup; when After the mixture liquid is in a turbid state, put the stirring rod of the stirrer into it, and stir at a speed of 400r/min for 12 hours; then place it in an oven, dry it at 105°C to constant weight, and then place it in a muffle furnace to heat up At a rate of 10°C/min, the temperature was raised from room temperature to 900°C, and calcined at a constant temperature of 900°C for 4 hours. Then the solid powder was taken out, cooled, and crushed to 60 mesh to obtain nickel-loaded calcined edinite (denoted as: C-ID(Ni) ), stored in the sample bag.

Calcined olivine (C-OL), calcined Xiuyan jade (C-XY), calcined edinite (C-ID), nickel-loaded calcined olivine (C-OL(Ni)), calcined Xiuyan jade (C- The XRF analysis of XY(Ni)) and calcined edinite (C-ID(Ni)) is shown in Table 1, and the ICP analysis is shown in Table 2, indicating that the additive has more metal catalysts such as Ni, Fe, Mg, Ca, etc. Components; SEM, EDX analysis As shown in Figure 1, the surface of the additive has abundant pores and capillary structures, which is conducive to mass and heat transfer during the pyrolysis of hazardous waste sludge, and the active components are uniformly dispersed.

Table 1. Comparative analysis of metal components of different additives based on XRF (weight percent)

Table 2. Comparative analysis of metal components of different additives based on ICP (mg/g)

Example 4

Hazardous waste sludge treatment: take oily sludge as an example for hazardous waste sludge. The oily sludge was taken from Shanghai Baosteel. Before the start of the test, the oily sludge was sieved out of impurities, then ground and pulverized, and dried in an oven to a constant temperature. Heavy, cool, put the oily sludge sample into a ziplock bag, put it in a drying dish for storage, and use it for later use.

The four-component analysis of heavy oil in oily sludge samples is shown in Table 3.

Table 3. Comparative analysis of four components of heavy oil in oily sludge samples (unit: weight percentage)

The calcined olivine (C-OL), nickel-loaded calcined olivine (C-OL(Ni)), calcined Xiuyan jade (C-XY), nickel-loaded calcined Xiuyan jade prepared in Examples 1, 2, and 3 (C-XY(Ni)), calcined edinite (C-ID), and nickel-loaded calcined edinite (C-ID(Ni)) are additives, which are respectively used for pyrolysis treatment of hazardous waste sludge.

The oily sludge pyrolysis test device is shown in Figure 2, including a vertical fixed bed reactor 4, an _N2 bottle 1, a gas condensation device 8, a gas purification device 9, and an air bag 10; in the vertical fixed bed reaction A quartz tube 3 is installed inside the reactor 4, a heating zone is arranged around the quartz tube 3 in the vertical fixed bed reactor 4, and a heating belt 7 is installed at the lower part of the vertical fixed bed reactor 4 for heating the quartz tube. The bottom prevents the pyrolysis gas from condensing in advance; an additive platform 6 and a quartz hanging basket 5 that can move up and down along the inside of the quartz tube 3 are installed inside the quartz tube 3 from bottom to top, and the bottom of the quartz hanging basket is 150-250 mm from the additive platform The bottom of the described quartz hanging basket 5 is provided with small holes 53 to facilitate the passage of gas, quartz wool 52 is laid at the bottom of the quartz blue, and a hazardous waste sludge sample 51 is placed on the quartz wool 52; the bottom of the additive platform 6 is provided with a platform The small holes 63 are convenient for the passage of pyrolysis gas, and quartz wool 62 is laid on the bottom of the additive platform 6, and the additive 61 is placed on the quartz wool 62 to form an additive layer; the gas outlet of the N bottle ₁ is passed through the gas mass flow controller 2, The first valve 11 is connected to the upper air inlet of the quartz tube 3, and N is fed into the quartz tube ₃ during the test to form a nitrogen atmosphere; the lower pyrolysis gas outlet of the quartz tube 3 passes through the second valve 12, The gas condensing device 8 and the gas purification device (which are formed by connecting U-shaped tubes filled with color-changing silica gel and activated carbon respectively) 9 are connected to the gas bag 10 .

The test steps are as follows:

Step (1), use an electronic balance to accurately weigh 5 g of the treated oily sludge sample and 2 g of the additive, put the oily sludge sample into the quartz hanging basket, pour the additive evenly on the additive platform, then put the hanging basket, quartz The tube and flange are assembled and put into the vertical fixed bed reactor;

Step (2), before the experiment starts, control the nitrogen flow rate at 200mL/min, pass it into the quartz tube for purging for about 10min, and use the soap flowmeter to calibrate the actual air flow, and start heating after the actual flow rate is determined, and the heating rate is 10 ° C /min;

Step (3), when the temperature reaches a predetermined temperature (500°C, 600°C, 700°C, 800°C, 900°C), considering the large size of the heating furnace, keep the temperature for 10 minutes, and then control the bottom of the hanging basket to be about 200mm away from the additive layer, Start pyrolysis, constant temperature pyrolysis 60min;

Step (4), the gas generated by pyrolysis is finally collected by the air bag through condensation, drying of discolored silica gel and activated carbon adsorption;

In step (5), the collected gas is analyzed by a gas analyzer, and the main analyzed products are: CO, CO ₂ , H ₂ , and CH ₄ .

Figure 3 shows the gas production results of oily sludge pyrolysis alone (without additives), Figures 4 to 9 show the gas production results of oily sludge pyrolysis with additives, and Table 4 shows the oily sludge pyrolysis alone and additives at 900 °C. Gas yield from pyrolysis. It can be seen that at a temperature of 700℃～900℃, especially at a temperature of 900℃, the additives C-OL, C-XY, C-OL(Ni), C-XY(Ni), and C-ID(Ni) can all be Effectively increase the total pyrolysis gas production and _H2 production of the pyrolysis of hazardous waste sludge, among which C-XY(Ni) has the best effect. The additive C-ID can significantly increase the CO production of hazardous waste sludge pyrolysis, and the CO yield exceeds 55%, which is suitable for waste sludge pyrolysis CO conversion.

Table 4. Gas yields of oily sludge pyrolysis alone and with additives at 900 °C

Claims (10)

1. an additive for pyrolysis of hazardous waste sludge, characterized in that: the additive is a calcined additive obtained by calcining after the natural ore is ground, or the natural ore is ground and calcined to obtain a calcined additive, and then The calcined additive, nickel salt and ultrapure water are mixed, stirred, dried and then calcined to obtain the nickel-loaded additive; Wherein, described natural ore is any one or more mixing in Xiuyan jade, Yiding stone; The calcining conditions are as follows: in an air atmosphere, the temperature is raised to 800°C to 1000°C at a heating rate of 5°C/min to 20°C/min, and the constant temperature time is 2 to 6 hours; The mass ratio of the calcining additive, nickel salt and ultrapure water is (5～8):(2～4):(100～200); The re-calcining conditions are as follows: in an air atmosphere, the temperature is raised to 800°C to 1000°C at 5°C/min to 20°C/min, and the constant temperature is 2 to 6 hours. 2. The additive for pyrolysis of hazardous waste sludge according to claim 1, characterized in that: the conditions for the calcination are: in an air atmosphere, at a heating rate of 10°C/min, the temperature is raised from normal temperature to 900°C, Constant temperature for 4 hours. 3 . The additive for pyrolysis of hazardous waste sludge according to claim 1 , wherein the nickel salt is any one or a mixture of nickel nitrate hexahydrate and nickel chloride. 4 . 4. The additive for pyrolysis of hazardous waste sludge according to claim 1, wherein the mass ratio of the calcining additive, nickel salt, and ultrapure water is 5:2:100. 5 . The additive for pyrolysis of hazardous waste sludge according to claim 1 , wherein the re-calcining conditions are: air atmosphere, with a heating rate of 10° C./min, from normal temperature to 900° C. 5 . , the constant temperature time is 4 hours. 6. A method for pyrolysis treatment of hazardous waste sludge, characterized in that: comprising the steps of: Step (1), pretreatment of hazardous waste sludge: drying the hazardous waste sludge to constant weight; the total content of saturated hydrocarbons and aromatic hydrocarbons in the hazardous waste sludge is greater than 15%; Step (2), placing the hazardous waste sludge and the additive: placing the hazardous waste sludge and the additive described in claim 1 in the pyrolysis furnace in sections, so that the additive is closer to the pyrolysis gas outlet of the pyrolysis furnace; Step (3), pyrolysis of hazardous waste sludge: in a nitrogen atmosphere, pyrolysis of hazardous waste sludge is performed to collect pyrolysis gas. 7. The method for pyrolysis treatment of hazardous waste sludge according to claim 6, wherein the hazardous waste sludge is oily sludge, printing and dyeing sludge, pickling sludge, electroplating sludge and medical sludge Any one or more of them are mixed. 8. The method for pyrolysis treatment of hazardous waste sludge according to claim 6, characterized in that: in step (2), the mass ratio of the hazardous waste sludge to the additive is (5～8): (1～8) 3). 9 . The pyrolysis treatment method for hazardous waste sludge according to claim 8 , wherein in step (2), the mass ratio of the hazardous waste sludge to the additive is 2.5:1. 10 . 10 . The method for pyrolysis treatment of hazardous waste sludge according to claim 6 , wherein in step (3), the temperature of the pyrolysis treatment is 700°C to 900°C. 11 .

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