Sustainable oily sludge smoldering catalytic treatment method

Abstract

The invention discloses a sustainable oily sludge smoldering catalytic treatment method. The method comprises the step of carrying out smoldering treatment on oily sludge under the action of a catalyst. According to the method, the catalyst is adopted for catalyzing smoldering of the oily sludge, so that the combustion rate and the spreading speed of a smoldering front surface can be increased, smoldering products are improved, generation of harmful gas is reduced, and the purposes of harmlessness and recycling are achieved; the activation energy required by the smoldering reaction is reduced, the smoldering peak temperature is improved, the peak temperature occurrence time is shortened, and energy conservation can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of oily sludge treatment, and in particular to a sustainable smoldering catalytic treatment method for oily sludge. Background Art

[0002] Oily sludge is a solid waste generated in the production process of the petroleum industry, mainly from oil field exploitation, oil refining and storage and transportation. Its composition is complex, including petroleum hydrocarbon organic pollutants, heavy metals, sediment and water, with high calorific value characteristics, and it also seriously pollutes the environment. At present, the treatment of oily sludge is moving towards the three goals of "harmlessness", "resource utilization" and "reduction", and smoldering technology is one of the commonly used treatment technologies.

[0003] Smoldering refers to a slow, flameless combustion phenomenon, such as the burning of charcoal and cigarettes. Smoldering combustion requires a "fuel" with a high calorific value, a breathable mixing medium, and a temperature that reaches the ignition point. The oily sludge smoldering combustion treatment technology slowly burns the oily sludge in a low-oxygen environment, and slowly oxidizes and decomposes the oily sludge through air supply. This technology has the advantages of low energy consumption and the ability to handle complex organic components. However, the inventors found in practical research that smoldering combustion has the disadvantages of incomplete combustion, slow combustion rate, and low treatment efficiency (basically an intermittent or batch treatment process).

[0004] Therefore, it is expected to develop new technical methods that can at least partially overcome the deficiencies in the prior art. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies in the prior art and propose a sustainable smoldering catalytic treatment method and system for oily sludge, which can carry out sustainable smoldering catalytic treatment of oily sludge, has the advantages of fast combustion rate and high combustion efficiency, and can achieve the "three transformations" goals.

[0006] More specifically, the present invention proposes a sustainable smoldering catalytic treatment method for oily sludge, which comprises smoldering the oily sludge under the action of a catalyst.

[0007] According to an embodiment of the present invention, the smoldering treatment includes feeding the oily sludge into a smoldering reactor for smoldering. The smoldering reactor includes a feeding part, a catalytic part and a heating part from top to bottom. The catalytic part is provided with a smoldering catalyst for catalyzing the smoldering of the oily sludge.

[0008] According to an embodiment of the present invention, the smoldering treatment further comprises:

[0009] a. Heating the oily sludge in the heating section and injecting air into the heating section at the same time;

[0010] b. Detecting the temperature of the oily sludge in the heating section, and stopping heating the oily sludge in the heating section when it is detected that the temperature curve of the oily sludge in the heating section changes sharply and a smoldering front appears;

[0011] c. Detecting the temperature of the oily sludge in the catalytic section. When a sharp change in the temperature curve and a smoldering front are detected in the oily sludge at the upper part of the catalytic section, the oily sludge in the feed section is pushed into the catalytic section for catalytic smoldering. At the same time, the material originally stored in the catalytic section enters the heating section to provide a heat source for the smoldering in the feed section, and the material originally stored in the heating section is discharged from the smoldering reactor; and

[0012] d. Feed new oily sludge into the feed part of the smoldering reactor and repeat the above step c, thereby achieving sustainable treatment of the oily sludge.

[0013] According to an embodiment of the present invention, the sustainable smoldering catalytic treatment method for oily sludge further comprises: before feeding, uniformly stirring the oily sludge or uniformly mixing the oily sludge with a solid porous medium, wherein the solid porous medium is, for example, alumina beads or quartz sand.

[0014] According to an embodiment of the present invention, the sustainable method for catalytic treatment of smoldering oily sludge further comprises treating the gas generated by the smoldering, wherein the treatment comprises condensation, denitrification and denitrification.

[0015] According to an embodiment of the present invention, the catalyst is selected from molecular sieves, metal oxide catalysts and metal salt catalysts, such as dolomite and ZSM-5 molecular sieves. For example, in the catalytic smoldering of oily sludge, the smoldering peak temperature can be higher than 625°C, such as higher than 660°C, higher than 680°C.

[0016] According to an embodiment of the present invention, the temperature for heating the oily sludge in the heating part is 400-500° C., and air is injected into the heating part by an air compressor at a flow rate of 10-30 L / min.

[0017] According to an embodiment of the present invention, the oil content of the oily sludge is 6-25% and the water content is less than 30%.

[0018] According to an embodiment of the present invention, the amount of the catalyst used is 10-40 kg / 1000 kg.

[0019] According to an embodiment of the present invention, a heat storage medium is also provided in the heating section. In step a, the heat storage medium is heated while the oily sludge is heated to store heat. After the heating is stopped in step b, the heat storage medium can be continuously released to promote the propagation of the smoldering front to the catalytic section.

[0020] In the embodiment of the present invention, the smoldering of oily sludge is catalyzed by using a catalyst, which can increase the combustion rate, the propagation speed of the smoldering front, improve the smoldering products, reduce the generation of harmful gases, and achieve the goals of "harmlessness" and "resource utilization"; reduce the activation energy required for the smoldering reaction, increase the smoldering peak temperature, shorten the peak temperature occurrence time, and achieve energy saving;

[0021] In the embodiment of the present invention, the smoldering reactor adopts a three-stage type, so that the oily sludge reaches the ignition point. After the external heat source is cut off, the entire smoldering reactor forms a sustainable reaction, which saves energy consumption and promotes the complete combustion of the oily sludge, achieving the goal of "reduction";

[0022] In the embodiments of the present invention, the treatment of the smoldering gas product, such as the use of condensation and separation technology, achieves the goal of maximum "resource utilization". BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a process of a sustainable smoldering catalytic treatment method of oily sludge according to an embodiment of the present invention;

[0024] Figure 2 It is a schematic structural diagram of a sustainable oily sludge smoldering catalytic treatment system according to an embodiment of the present invention;

[0025] Figure 3 It is a schematic structural diagram of a smoldering reactor in a sustainable oily sludge smoldering catalytic treatment system according to an embodiment of the present invention;

[0026] Figure 4 Based on Figure 3 A schematic diagram of the top view of the catalytic part (in the dotted frame) of the smoldering reactor shown;

[0027] Figure 5 Based on Figure 3 A schematic side view of the catalytic part of the smoldering reactor from another angle; and

[0028] Figure 6 It is a schematic structural diagram of a truncated cone-shaped partition (with heating wires wrapped around it) of a smoldering reaction furnace in a sustainable oily sludge smoldering catalytic treatment system according to an embodiment of the present invention;

[0029] Figure 7 Fourier transform infrared spectra of samples and products before and after the smoldering reaction in each experiment according to the embodiments of the present invention;

[0030] Figure 8 The gas chromatograms of samples and products before and after the smoldering reaction in each experiment according to the embodiments of the present invention;

[0031] Fig. 9is an energy spectrum diagram of oily sludge before treatment according to an embodiment of the present invention;

[0032] Fig.10 This is an energy spectrum of a sample after smoldering combustion of oily sludge in Experiment a according to an embodiment of the present invention;

[0033] Fig.11 It is an energy spectrum diagram of a sample after smoldering combustion of oily sludge in Experiment b according to an embodiment of the present invention;

[0034] Fig.12 The energy spectrum of the sample after smoldering combustion of oily sludge in Experiment c according to the embodiment of the present invention; and

[0035] Fig.13 The average peak temperature, average peak temperature occurrence time and average thermocouple heating rate of thermocouples T1-T4 treating oily sludge in experiments a, b and c are shown respectively. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings. The shown contents are used to fully illustrate the contents of the present invention, but are not used to limit the present invention.

[0037] Figure 1 This is a schematic diagram of a sustainable smoldering catalytic treatment method for oily sludge according to an embodiment of the present invention. As shown in the figure, the sustainable smoldering catalytic treatment method for oily sludge according to the embodiment may include the following steps:

[0038] First, the oily sludge can be fed into the smoldering reactor. Before feeding, the oily sludge can be stirred to make it uniform, which is conducive to smoldering.

[0039] Oily sludge smoldering is a flameless heterogeneous combustion, a self-sustaining smoldering process, which realizes the drying and combustion process of oily sludge by generating heat through the reaction itself, and the processing temperature is 500-700°C. Generally, smoldering combustion needs to meet three conditions: fuel, oxidant (oxygen) and ignition point. Oily sludge smoldering uses the organic matter contained in the sludge itself as fuel. Generally speaking, the oil content of oily sludge is 6%-25% to meet the smoldering requirements; too low oil content may not be able to sustain smoldering, and too high oil content may cause smoldering to easily turn into flame combustion. When the oil content is too high, solid porous media such as alumina balls can be appropriately used to mix the oily sludge. On the one hand, the oil content is reduced, and on the other hand, the solid porous medium can improve the permeability of the oily sludge, which is conducive to gas circulation and heat transfer, thereby facilitating smoldering. The material ratio of solid porous media and oily sludge can be appropriately selected, for example, it can be 1:3-2:1. In addition, the moisture in the oily sludge will also affect the smoldering effect. The moisture in the oily sludge is preferably not more than 30%, and the moisture content can also be adjusted by using solid porous media.

[0040] The smoldering reactor of the embodiment may include a feeding part, a catalytic part and a heating part from top to bottom. The catalytic part is provided with a smoldering catalyst for catalyzing the smoldering of oily sludge.

[0041] After the oily sludge feed fills the feed part, the catalytic part and the heating part, the heating part can be preheated, for example, the oily sludge in the heating part can be heated by using electric heating wires or other heat sources. The heating temperature is preferably to achieve smoldering ignition of the oily sludge, for example, the heating temperature can be controlled to be 400-500°C. As mentioned above, in order to achieve smoldering, an oxidant is also required, so air is injected into the heating part while preheating, for example, it can be injected by using an air compressor, and the flow rate can be, for example, 10-30L / min.

[0042] In order to detect whether the oily sludge is ignited, a temperature sensor (such as a thermocouple sensor) can be used to detect the temperature of the oily sludge in the heating section. When it is detected that the temperature curve changes sharply and a smoldering front appears, it can be determined that the oily sludge in the heating section is smoldering and igniting. At this time, the heating of the oily sludge in the heating section can be stopped. In addition, a heat storage medium can be provided in the heating section, so that the heat storage medium is also heated while the oily sludge is heated. The thermal storage medium can be, for example, a ceramic granular material, such as selected from corundum, mullite, zircon, aluminum titanate and cordierite. These media are resistant to high temperatures and have good heat storage capacity. When the heating of the oily sludge is stopped, additional heat will still be provided due to thermal inertia, which promotes the complete combustion of the oily sludge and the propagation of the smoldering front, and maintains the stability of the smoldering process.

[0043] The smoldering oily sludge in the heating section gradually moves upward to the catalytic section, causing the smoldering of the oily sludge in the catalytic section. The catalytic section is provided with a catalyst to catalyze the smoldering of the oily sludge.

[0044] Research has found that zeolite can promote the dehydrogenation and aromatization of aromatics in pyrolysis oil during catalytic pyrolysis, promote the breaking of CC bonds and CH bonds, and facilitate the formation of short-chain hydrocarbons and hydrogen; some molecular sieves have a deoxidation effect, which can reduce the content of oxygen heterocycles in pyrolysis oil and promote the cracking of heavy chain alkane molecules into light saturated hydrocarbons. Metal oxide catalysts can include CaO, NiO and Fe2O3, etc.; transition metal ions on the surface of active sites may react with carboxylic acids and sulfur, resulting in the breaking of CC bonds and the formation of light components; for example, adding CaO as a catalyst can improve pyrolysis efficiency, reduce solid phase yield, and increase gas-liquid phase conversion rate. Metal salt catalysts are mainly composed of light metals such as Al, Na, Ca, and K. They have good performance in improving the yield and quality of pyrolysis oil and gas and reducing the activation energy of pyrolysis reactions. For example, Ca-based catalysts have high microwave absorption capacity and accelerate the heating rate during pyrolysis of oil sludge; at the same time, Ca-based catalysts have a good promoting effect on the conversion of oily sludge.

[0045] In the embodiment of the present invention, the catalyst can be selected from molecular sieves, metal oxide catalysts and metal salt catalysts, for example, dolomite and ZSM-5 molecular sieves, etc. In the embodiment of the present invention, the amount of the catalyst can be about 10-40 kg / 1000 kg.

[0046] The temperature of the oily sludge in the catalytic section can be detected to understand the smoldering condition of the oily sludge. For example, multiple temperature sensors can be set in the catalytic section to detect the temperature changes of the materials at different positions in the catalytic section. For example, when a sharp change in the temperature curve is detected in the material at the bottom of the catalytic section and a smoldering front appears, it means that the smoldering front has spread from the heating section to the catalytic section; when a sharp change in the temperature curve is detected in the material at the top of the catalytic section and a smoldering front appears, it means that the smoldering front has spread to the top of the catalytic section.

[0047] When it is detected that the smoldering front has propagated to the top of the catalytic section, the oily sludge in the feed section can be pushed into the catalytic section for catalytic smoldering. At the same time, the original material in the catalytic section is pushed into the heating section and the original material in the heating section is discharged from the smoldering reactor. The smoldering material in the catalytic section still contains a large amount of preheated or even a small amount of unburned organic matter, so discharging these materials into the heating section can make full use of the waste heat and further fully treat the residual organic matter therein.

[0048] Afterwards, new oily sludge can be fed into the feed section.

[0049] By repeating the above steps, sustainable treatment of oily sludge can be achieved, which can greatly improve the efficiency of sludge treatment.

[0050] In addition, the embodiment of the present invention may also include a treatment step for smoldering flue gas. For example, the smoldering flue gas may be subjected to condensation, denitrification and denitrification, etc., and then discharged into the atmosphere. Condensation may be performed using a condenser, for example. The smoldering flue gas contains products such as olefins, alkanes, and aromatics. Condensation may liquefy some of the products, thereby obtaining oil phase products and achieving full utilization of resources. The gas after condensation may also be subjected to denitrification and denitrification. The techniques and equipment for denitrification and denitrification are well known in the art and will not be described in detail herein.

[0051] An exemplary sustainable oily sludge smoldering catalytic treatment system that can implement the sustainable oily sludge smoldering catalytic treatment method of the present invention is described in detail below with reference to the accompanying drawings.

[0052] Figure 2 The present invention is a schematic structural diagram of a sustainable oily sludge smoldering catalytic treatment system according to an embodiment of the present invention. As shown in the figure, the sustainable oily sludge smoldering catalytic treatment system of the embodiment may include a smoldering reactor (10), a feeding device (20), a tail gas treatment device (30) and an air supply device (40), wherein the feeding device (20) is connected to a feeding port (121) of the smoldering reactor (10) for feeding the smoldering reactor (10). The tail gas treatment device (30) is connected to a flue gas discharge port of the smoldering reactor (10) for treating smoldering flue gas. The air supply device (40) is connected to an air diffusion pipe (144) of the smoldering reactor (10) for providing air / oxygen to the smoldering reactor (10).

[0053] Figure 3 It is a schematic structural diagram of a smoldering reactor in a sustainable oily sludge smoldering catalytic treatment system according to an embodiment of the present invention; Figure 4 Based on Figure 3 A schematic diagram of the top view of the catalyst portion (in the dotted frame) of the smoldering reactor shown; Figure 5 Based on Figure 3 A schematic side view of the catalytic part of the smoldering reactor from another angle; and Figure 6 The truncated cone partition (with heating wire wrapped around it) of the smoldering reactor in the sustainable oily sludge smoldering catalytic treatment system according to the embodiment of the present invention is a schematic structural diagram. The smoldering reactor (10) is described below in conjunction with the accompanying drawings.

[0054] As shown in the figure, the smoldering reactor (10) includes a shell (11), which is in the shape of a hollow column and includes a feed part (12), a catalytic part (13) and a heating part (14) from top to bottom. In order to achieve a better heat preservation effect, a heat preservation layer (15) can also be provided on the outer periphery of the shell (11).

[0055] The feed section (12) is located at the upper section of the smoldering reactor (10) and may be provided with a feed port (121) and a smoke exhaust port (not marked). The feed port (121) is connected to the feed device (20), and the oily sludge enters the smoldering reactor (10) through the feed port, and the smoke generated by the smoldering of the smoldering reactor (10) enters the tail gas treatment device (30) through the smoke exhaust port.

[0056] An electric scraper plate (122) is also provided in the feed section (12), which can move up and down along the feed section (12) under the drive of the drive motor (123) to push the oily sludge in the feed section (12) to move downward. The drive motor (123) can be arranged above the smoldering reactor (10) and connected to the shaft of the electric scraper plate (122), thereby driving the electric scraper plate (122). Generally, when feeding, the height of the electric scraper plate (122) can be set above the feed port (121) and below the flue gas outlet, so as to prevent the oily sludge from entering the flue gas outlet. When the feeding is completed, the height of the electric scraper plate (122) can rise to above the flue gas outlet, thereby facilitating the smoldering flue gas to enter the flue gas outlet.

[0057] The catalytic section (13) is located in the middle section of the smoldering reaction furnace (10), wherein a plurality of detachable flat catalyst boxes (131) are provided, and catalysts are contained in the catalyst boxes (131), thereby smoldering catalysis is performed on the oily sludge contained in the catalytic section (13).

[0058] refer to Figure 4 and Figure 5 The catalyst box (131) can be a flat hollow box as a whole, with small holes formed on each surface, and the catalyst is contained in the box. Granular catalysts such as molecular sieves, metal oxides, metal salts, etc. can be used, and the particle size of the particles is larger than the diameter of the small holes, thereby preventing the catalyst from leaking out. Pins (1311) can be fixed on both sides of the catalyst box (131), and corresponding sockets (unmarked) are provided on the inner side wall of the catalyst part (13), so that the catalyst box (131) can be fixed in the catalyst part (13) by the pins. This method can be used to fix multiple catalyst boxes (131) in the catalyst part (13) at intervals. Of course, other fixing means can also be used. Multiple catalyst boxes (131) are arranged at intervals, so that the oily sludge can pass through the catalyst part (13), and the oily sludge wraps the catalyst box (131), achieving sufficient contact and catalytic effect.

[0059] refer to Figure 3 and Figure 6The heating part (14) is located at the lower section of the smoldering reactor (10), wherein a truncated cone-shaped partition (141) is provided therein for separating the oily sludge from the heat storage medium (143). A discharge port (142) is formed at the bottom of the truncated cone for discharging the oily sludge and other materials in the heating part (14) out of the smoldering reactor (10). The side surface of the truncated cone is perforated, and the perforations on the side surface can facilitate the transmission of heat and gas. A wire mesh (not shown) can also be provided on the inner surface of the truncated cone to prevent sludge from penetrating. A heating wire (145) is wound on the outer surface of the side surface of the truncated cone, and a heat storage medium (143) is filled in the space between the side surface of the truncated cone and the housing (11). The heat storage medium (143) can be, for example, a material that is resistant to high temperatures and has a strong heat storage capacity, such as a ceramic granular material, for example, selected from corundum, mullite, zircon, aluminum titanate, and cordierite. The heating wire (145) is used to heat the oily sludge in the heating part (14) and heat the heat storage medium (143) at the same time.

[0060] An air diffusion pipe (144) is provided below the heat storage medium (143), and the air diffusion pipe (144) is connected to the air inlet hole at the bottom of the smoldering reaction furnace (10). The air diffusion pipe has holes evenly distributed to evenly distribute air to the heat storage medium (143) for transferring air and heat. A multi-hole annular circular plate (not marked) may also be provided above the air diffusion pipe (144) to provide support for the heat storage medium (143) and further evenly diffuse the air to ensure the uniformity of the supplied airflow.

[0061] like Figure 1 As shown, the sustainable oily sludge smoldering catalytic treatment system of the implementation scheme may also include an air supply device (40) connected to the air diffusion pipe (144), and the air supply device (40) may, for example, include an air compressor (41), a flow meter (42), and a valve (43) and a dryer (44) therebetween, thereby, the air compressor (41) can supply compressed air of a certain pressure and flow rate to the heating part (14) to achieve combustion support.

[0062] In order to detect the temperature of the material in the smoldering reactor (10) and understand the smoldering condition of the oily sludge therein, a plurality of temperature sensors (50) can also be arranged on the side walls of the catalyst section (13) and the heating section (14) of the smoldering reactor (10). As shown in the figure, the embodiment shows that four thermocouple sensors are arranged from bottom to top on the side wall of the catalyst section (13), and one thermocouple sensor is arranged in the heating section (14). It should be understood that the number of temperature sensors (50) and the positions where they are arranged can be arranged according to actual needs. The thermocouple sensor in the heating section (14) is used to detect the smoldering ignition condition of the oily sludge in the heating section (14). When it is detected that the temperature curve of the oily sludge changes sharply and a smoldering front appears, it means that the oily sludge in the heating section (14) has been ignited. At this time, the heating wire (145) can stop heating the oily sludge in the heating section to save fuel. The four thermocouple sensors in the catalyst section (13) can detect the temperature and smoldering of the oily sludge in the catalyst section (13). For example, when the topmost thermocouple sensor in the catalyst section detects a sharp change in the temperature curve and the appearance of a smoldering front, it means that the smoldering front has spread to the top of the catalyst section.

[0063] refer to Figure 1 In order to control and display the detected temperature, the sustainable oily sludge smoldering catalytic treatment system of the embodiment may also include a temperature display (60) and a program temperature riser (70). The plurality of temperature sensors (50) are electrically connected to the temperature display (60), so that the detected temperature changes can be transmitted to the temperature display (60) for storage and display. The heating wire (145) is connected to the program temperature riser (70) to control the heating wire to heat, such as controlling the heating temperature and heating time of the heating wire.

[0064] like Figure 1 As shown, the sustainable oily sludge smoldering catalytic treatment system of the embodiment may further include a feeding device (20) connected to the feeding port (121), wherein the feeding device (20) includes a feeding hopper (21) and a stirring device (22). The stirring device (22) stirs the oily sludge (or a mixture of the oily sludge and the solid porous medium) in the feeding hopper (21), and after the mixture is stirred evenly, the mixture is fed into the smoldering reactor (10) through the feeding port (121).

[0065] As shown in the figure, the sustainable oily sludge smoldering catalytic treatment system of the implementation scheme may also include a tail gas treatment device (30) connected to the flue gas discharge port of the feed part (12) for treating the gas generated by the smoldering. More specifically, the tail gas treatment device (30) may include a condenser (31), a collection tank (32) and a desulfurization and denitrification device (33). The smoldering flue gas contains products such as olefins, alkanes, and aromatics. The condenser can liquefy some of the products to obtain oil phase products, which are stored in the collection tank. The tail gas after condensation can then enter the desulfurization and denitrification device (33) for desulfurization and denitrification treatment, and then be emptied. The technology and equipment for denitrification and denitrification are well known in the art and will not be repeated here.

[0066] The following experiments are conducted using the method and device of the present invention to further illustrate the present invention.

[0067] 1. Experimental materials: oily sludge (Tianjin Dagang Oilfield), initial sludge oil content is 12.36%, water content is 14.70%, catalyst: ZSM-5 molecular sieve, dolomite; heat storage medium: corundum mullite

[0068] 2. Experimental instruments: smoldering reaction furnace (the present invention); ZX-1800 temperature controller (Beijing Zixin Technology Co., Ltd.); temperature recorder THM060K (Yuyao Tenghui Temperature Control Instrument Factory); air compressor TG30B (Hong Kong Tuguan Industrial Co., Ltd.); rotor flowmeter FM-6 (Duhuoer Company); infrared spectrophotometer oil tester JLBG-126 (Jiguang Technology Co., Ltd.); Fourier transform infrared spectrometer TENSOR 27 (Bruker Company, Germany); field emission environmental scanning electron microscope Quanta 400 (FE I Company, the Netherlands); thermogravimetric analyzer SDT 600 (TA Company, the United States); gas chromatograph GC 8890 (Agilent Company, the United States); inductively coupled plasma mass spectrometer I CP-MS 7800 (Agilent Company, the United States); condenser (Beijing Zixin Technology Co., Ltd.).

[0069] 3. Experimental process:

[0070] Experiment a: ZSM-5 molecular sieve as catalyst

[0071] About 2 kg of ZSM-5 molecular sieve was loaded into the catalyst box, and about 200 kg of oily sludge was injected into the smoldering reactor. The mass ratio of the materials in the heating section, the catalytic section and the feeding section was about 1:2:2. Five thermocouple thermometers were arranged in the smoldering reactor, which were respectively marked as T0-T4, wherein T0 was arranged in the heating section, and T1-T4 were arranged in the catalytic section from bottom to top. The temperatures of the five thermocouples were collected by a digital temperature controller and recorded every 1 minute.

[0072] The material in the heating section is heated by a ZX-1800 temperature controller, and air is injected by an air compressor at a gas flow rate of about 15L / min. When the material in the heating section is indirectly heated to a temperature of about 450°C, the sludge smoldering process begins (ignition). T1-T4 respectively record the smoldering temperature of the sludge in the catalytic section. When T4 detects a sharp change in the temperature curve and a peak temperature, the scraper plate is used to drive the sludge in the feed section downward into the catalytic section for smoldering treatment. At the same time, the smoldering material in the catalytic section is squeezed into the heating section, and the material in the heating section is discharged from the smoldering reactor. Then, about 80 kg of oily sludge is injected into the feed section. The above steps are repeated until all the sludge (280 kg) is processed.

[0073] The oil-gas mixture generated during the smoldering treatment process is recovered through the circulating water reflux condensation device at the tail end, and the condensed oil phase product is recovered by the tail collection tank.

[0074] The test items include: the organic matter content in the sludge before and after smoldering; EDS energy spectrum analysis of the sludge before and after smoldering; smoldering efficiency (change in thermocouple temperature parameters); the sample after smoldering is a mixed sample of the products after the first two smoldering in the catalyst section, and the T1-T4 thermocouple temperature parameter value is the average of the three smoldering detection values.

[0075] Experiment B: Dolomite as Catalyst

[0076] Except that 2 kg of dolomite was used as the catalyst instead of ZSM-5 molecular sieve, the rest was the same as experiment a.

[0077] Experiment c: Using quartz sand instead of catalyst

[0078] Except for using 2 kg of quartz sandstone to replace ZSM-5 molecular sieve, the rest is the same as experiment a.

[0079] 4. Experimental Results

[0080] The main components of oily sludge are saturated hydrocarbons, mainly C10-C24 straight-chain alkanes, followed by aromatic compounds and olefins, with less alcohols and phenols and higher heavy hydrocarbons. The analysis found that the changes in the wavelength of functional groups before and after the treatment of oily sludge mainly occurred at 2930cm -1 、2850cm -1 and 1465cm -1 Attached Figure 7 The Fourier transform infrared spectra of each experiment before and after the smoldering reaction are shown; Figure 8The gas chromatograms of the samples and products before and after the smoldering reaction of each experiment are shown. By comparing the FT-IR spectra and GC chromatograms before and after the treatment, it can be clearly seen that the peak intensity is reduced or even disappears, and the organic matter content in the smoldering products after the reaction is extremely low, indicating that the sludge smoldering catalytic technology of the present invention is very effective in degrading organic matter in sludge; in addition, compared with the experiment c without using a catalyst, the effects of the experiments a and b of the present invention are better.

[0081] At a working voltage of 20 kV, an energy dispersive X-ray spectrometer was used to observe the element distribution and changes before and after the oily sludge treatment. Figure 9-12 As shown, attached Fig. 9 is the energy spectrum of oily sludge before treatment; Figure 10-12 The energy spectra of the oily sludge after treatment in experiments a, b and c are respectively. Before the oily sludge was treated, its components were mostly hydrocarbon substances, mainly composed of carbon elements, with a proportion of up to 97%. After the smoldering treatment, it can be observed that the carbon element decreased significantly, and the presence of carbon elements was basically undetectable in the product, while the Si and O elements accounted for the highest proportion. This is because the main components of gravel (silicon dioxide) are Si and O elements. Therefore, it can be concluded that after the smoldering catalytic reaction treatment of the present invention, the hydrocarbon substances in the oily sludge were basically removed and converted into silica gravel. In contrast, in the comparative experiment c without using a catalyst, the residual carbon element content was higher.

[0082] Attached Fig.13 The average peak temperature, peak temperature time difference, and average heating rate of thermocouples T1-T4 for treating oily sludge in experiments a, b, and c are shown respectively, reflecting the effect of catalyst on smoldering. Among them, "average peak temperature" refers to the average of the sum of the peak temperatures of multiple thermocouples (T1, T2, T3, T4); "peak temperature time difference" is the time difference between the peak temperature appearance time of thermocouple T4 and the peak temperature appearance time of another thermocouple T1; heating rate refers to the heating rate of the thermocouple from the ignition temperature (450°C in this experiment) to the peak temperature, and the average heating rate refers to the average heating rate of multiple thermocouples (T1, T2, T3, T4).

[0083] Molecular sieves have strong catalytic cracking ability and thermal stability. Fig.13As shown, it can be clearly observed that the addition of the catalyst molecular sieve greatly increased the average peak temperature to 698.15°C. At the same time, the average thermocouple heating rate increased to a maximum of 39.01°C / min, and the smoldering peak propagation rate increased significantly. Therefore, the addition of the catalyst molecular sieve can reduce the activation energy required for the smoldering reaction. In addition, the average peak temperature appearance time is only 51 minutes. The reduction in peak temperature duration will reduce the generation of harmful substances such as carbon monoxide (CO) and nitrogen oxides (NOx). Dolomite is an acid-base catalyst of mixed oxides with a large specific surface area, certain thermal stability and corrosion resistance. As Fig.13 As shown, it can be clearly observed that the values ​​of each experimental parameter are better than those of experiment c, indicating that the addition of dolomite increases the smoldering combustion rate, accelerates the smoldering propagation time, and improves the overall smoldering removal efficiency.

[0084] The above description of the embodiments is to facilitate the understanding and application of the present invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the embodiments herein, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A sustainable smoldering catalytic treatment method for oily sludge, characterized in that: It involves the smoldering treatment of oily sludge under the action of a catalyst.

2. The sustainable smoldering catalytic treatment method for oily sludge according to claim 1 is characterized in that: The smoldering treatment includes feeding the oily sludge into a smoldering reactor for smoldering. The smoldering reactor includes a feeding part, a catalytic part and a heating part from top to bottom. The catalytic part is provided with a smoldering catalyst for catalyzing the smoldering of the oily sludge.

3. The sustainable smoldering catalytic treatment method for oily sludge according to claim 2 is characterized in that: The smoldering process further comprises: a. Heating the oily sludge in the heating section and injecting air into the heating section at the same time; b. Detecting the temperature of the oily sludge in the heating section, and stopping heating the oily sludge in the heating section when it is detected that the temperature curve of the oily sludge in the heating section changes sharply and a smoldering front appears; c. Detecting the temperature of the oily sludge in the catalytic section. When a sharp change in the temperature curve and a smoldering front are detected in the oily sludge at the upper part of the catalytic section, the oily sludge in the feed section is pushed into the catalytic section for catalytic smoldering. At the same time, the material originally stored in the catalytic section enters the heating section to provide a heat source for the smoldering in the feed section, and the material originally stored in the heating section is discharged from the smoldering reactor; and d. Feed new oily sludge into the feed part of the smoldering reactor and repeat the above step c, thereby achieving sustainable treatment of the oily sludge.

4. The sustainable smoldering catalytic treatment method for oily sludge according to claim 2 is characterized in that: Also includes: Before feeding, the oily sludge is uniformly stirred or the oily sludge is uniformly mixed with a solid porous medium, such as alumina beads or quartz sand.

5. The sustainable catalytic treatment method for smoldering oily sludge according to claim 1 further comprises treating the gas generated by the smoldering, wherein the treatment comprises condensation, denitrification and denitrification.

6. The sustainable smoldering catalytic treatment method for oily sludge according to claim 1 is characterized in that: The catalyst is selected from molecular sieves, metal oxide catalysts and metal salt catalysts, such as dolomite and ZSM-5 molecular sieves.

7. The sustainable smoldering catalytic treatment method for oily sludge according to claim 3 is characterized in that: The temperature for heating the oily sludge in the heating section is 400-500°C, and air is injected into the heating section using an air compressor at a flow rate of 10-30L / min.

8. The sustainable smoldering catalytic treatment method for oily sludge according to claim 1 is characterized in that: The oil content of oily sludge is 6-25% and the water content is less than 30%.

9. The sustainable smoldering catalytic treatment method for oily sludge according to claim 1, characterized in that: The dosage of the catalyst is 10-40kg / 1000kg.

10. The sustainable smoldering catalytic treatment method for oily sludge according to claim 3, characterized in that: A heat storage medium is also provided in the heating section. In step a, the heat storage medium is heated while the oily sludge is heated to store heat. After the heating is stopped in step b, the heat storage medium can be continuously released to promote the propagation of the smoldering front to the catalytic section.

Images