Organic waste liquid and pulverized coal oxygen-enriched co-combustion and waste heat cascade recovery method and system

Abstract

According to the organic waste liquid and pulverized coal oxygen-enriched co-combustion and waste heat cascade recovery method and system, the organic waste liquid is firstly concentrated, so that the concentrated liquid and free water are obtained, and the free water absorbs flue gas waste heat to supply heat to users; the method comprises the following steps: concentrating the organic waste liquid to obtain a concentrated solution, adding pulverized coal preheated by flue gas waste heat into the concentrated solution, mixing to obtain a water-coal-organic waste liquid mixed slurry, preheating oxygen-enriched oxygen by using the flue gas waste heat, atomizing the mixed slurry, and combusting under an oxygen-enriched condition to fully combust the organic waste liquid. Flue gas waste heat is recovered through a multi-stage heat exchange device, so that heat energy converted from chemical energy of organic waste liquid is subjected to energy gradient utilization.

Description

Technical Field

[0001] The present invention relates to the technical field of organic waste liquid recovery, and particularly to a method and system for oxy-fuel co-combustion of organic waste liquid and pulverized coal and cascaded waste heat recovery. Background Art

[0002] In industries such as papermaking, medicine, pesticides, petrochemicals, and textiles, a large amount of organic waste liquid is discharged. These waste liquids are characterized by high organic matter concentration, complex composition, and high treatment difficulty, resulting in high treatment costs. Specifically, the biochemical oxygen demand in such waste liquids is usually greater than 100 mg / L, and the chemical oxygen demand exceeds 2,000 mg / L. Therefore, the current challenge is how to efficiently treat organic waste liquids with a wide range of sources, various types, different compositions, and varying concentrations.

[0003] Organic waste liquid is mainly composed of elements such as carbon, hydrogen, oxygen, nitrogen, and sulfur, and has a certain calorific value itself. For waste liquids with a higher calorific value, they can be directly used as fuel. For waste liquids with a lower calorific value, they need to be concentrated or auxiliary fuel added to achieve combustion. During the combustion process, the heat released by the combustion of the waste liquid can be collected through a waste heat recovery device, thereby reducing production costs. However, common auxiliary fuels such as natural gas produce a large amount of water vapor during combustion, which will share a part of the heat that should originally be provided by the organic waste liquid. In addition, when concentrating waste liquids with a low calorific value, a large amount of free water will be generated. Therefore, how to effectively utilize this free water to recover the heat generated by the combustion of organic waste liquid has become an urgent technical problem to be solved. Summary of the Invention

[0004] The present invention provides a method and system for oxy-fuel co-combustion of organic waste liquid and pulverized coal and cascaded waste heat recovery, aiming to solve the technical problem in the prior art that it is difficult to effectively utilize free water to recover the heat generated by the combustion of organic waste liquid. The invention can not only efficiently convert organic waste liquid into an energy resource, but also improve the energy utilization rate and reduce environmental pollution through a series of optimization measures.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A system for oxy-fuel co-combustion of organic waste liquid and pulverized coal and cascaded waste heat recovery, comprising: An organic waste liquid storage device for storing organic waste liquid and feeding it into an organic waste liquid concentration and separation device; An organic waste liquid concentration and separation device for converting organic waste liquid into a concentrated liquid and free water; A stirring and pulping device for mixing the concentrated liquid with pulverized coal to form a mixed slurry; A slurry combustion device for atomizing, burning the mixed slurry and performing preliminary waste heat recovery on the flue gas; The waste heat recovery device recovers the waste heat of the flue gas generated during the combustion process and applies it to the preheating of pulverized coal and air; The oxygen supply device ensures that the combustion environment has an appropriate oxygen concentration to promote complete combustion.

[0006] A further improvement of the present invention is that the organic waste liquid concentration and separation device is provided with a first liquid outlet and a second liquid outlet. The liquid outlet of the organic waste liquid storage device is connected to the liquid inlet of the organic waste liquid concentration and separation device, which is used to convert the organic waste liquid into a concentrated liquid containing concentrated organic waste liquid.

[0007] A further improvement of the present invention is that the liquid inlet of the stirring and pulping device is connected to the first liquid outlet of the organic waste liquid concentration and separation device, which is used to fully mix the pulverized coal and the concentrated liquid; the stirring and pulping device includes a pulverized coal feeding and stirring device and a pulping device. The pulping device includes a first feeding port and a second feeding port. The first liquid outlet of the organic waste liquid concentration and separation device is connected to the first feeding port of the pulping device, and the discharge port of the pulverized coal feeding and stirring device is connected to the second feeding port of the pulping device. The pulverized coal feeding device is provided with a liquid inlet.

[0008] A further improvement of the present invention is that the slurry combustion device includes a combustion furnace, an atomizer and a first heat exchange device. The feeding port of the slurry combustion device is connected to the discharge port of the pulping device, and the feeding port of the atomizer is connected to the discharge port of the pulping device. The atomizer is arranged in the combustion furnace and is used to atomize and burn the mixed slurry. The gas outlet of the combustion furnace is connected to the gas inlet of the first heat exchange device. The first heat exchange device is provided with a liquid inlet and a liquid outlet. The liquid inlet of the first heat exchange device is connected to the second liquid outlet of the organic waste liquid concentration and separation device, which is used to heat the free water separated in the organic waste liquid concentration and separation device by using the waste heat of the flue gas. After the free water is heated, it supplies heat to the user unit.

[0009] A further improvement of the present invention is that the waste heat recovery device includes a heat exchange unit and a gas transmission device. The heat exchange unit includes a second heat exchange device, a third heat exchange device and a pulverized coal conveying device; the second heat exchange device includes a first gas inlet, a second gas inlet, a first gas outlet and a second gas outlet; the gas outlet of the first heat exchange device is connected to the first gas inlet of the second heat exchange device, which is used to recover the waste heat of the flue gas after the combustion of the organic waste liquid in the slurry combustion device; the second gas inlet of the second heat exchange device is connected to the gas outlet of the gas transmission device, and the first gas outlet of the second heat exchange device is connected to the gas inlet of the combustion furnace, which is used to preheat the oxygen-enriched oxygen sent into the combustion furnace by using the waste heat of the flue gas; the discharge port of the pulverized coal conveying device is connected to the feeding port of the third heat exchange device, and the discharge port of the third heat exchange device is connected to the feeding port of the pulverized coal feeding and stirring device, which is used to preheat the pulverized coal and then send it into the pulverized coal feeding and stirring device to be stirred into slurry.

[0010] A further improvement of the present invention lies in that the oxygen supply device includes an oxygen tank and an oxygen injection valve. The first air inlet and the second air inlet of the oxygen supply device are both provided on the oxygen injection valve. The first air inlet of the oxygen injection valve is communicated with the air outlet of the oxygen tank, the second air inlet of the oxygen injection valve is communicated with the first air outlet of the second heat exchange device, and the air outlet of the oxygen injection valve is communicated with the air inlet of the combustion furnace. The oxygen tank is used to adjust the air supply balance of supplying oxygen-rich oxygen to the combustion furnace, and the oxygen injection valve controls the air input and output of the oxygen tank.

[0011] A further improvement of the present invention lies in that it further includes: N ventilation ducts, and the N ventilation ducts include a first ventilation duct, a second ventilation duct and a third ventilation duct. The air inlets of the first ventilation duct, the second ventilation duct and the third ventilation duct are respectively communicated with the air outlet of the oxygen injection valve, and the air outlets of the first ventilation duct, the second ventilation duct and the third ventilation duct are respectively communicated with the air inlet of the combustion furnace. The N ventilation ducts are used to adjust the uniform supply of oxygen-rich oxygen in the combustion furnace.

[0012] The method for oxy-fuel co-combustion of organic waste liquid and pulverized coal and cascade recovery of waste heat includes: (1) Storing the collected organic waste liquid to be treated in the organic waste liquid storage device; (2) Concentrating the collected organic waste liquid in the organic waste liquid concentration and separation device to separate the concentrated liquid containing high-concentration organic matter and free water; (3) Adding pulverized coal to the concentrated liquid in the stirring and pulping device and fully stirring to prepare a mixed slurry composed of water, pulverized coal and concentrated liquid; (4) Atomizing and burning the mixed slurry in the slurry combustion device, and the combustion process is carried out under the condition of oxygen-rich and with the participation of excess air, and the excess air needs to be preheated, and its heat source comes from the recovered flue gas waste heat; (5) Conducting multiple heat exchange processes through the slurry combustion device and the waste heat recovery device to recover the waste heat in the flue gas; wherein, the flue gas waste heat is used to preheat the pulverized coal and the air required for combustion.

[0013] A further improvement of the present invention lies in that the water content of the organic waste liquid before concentration exceeds 70%, and the water content of the concentrated liquid after concentration should be between 10% and 20%; the mass ratio of water to pulverized coal in the mixed slurry is maintained at 30% - 40%:60% - 70%, and the mass ratio of water to concentrated liquid should be maintained at 10% - 20%:80% - 90%.

[0014] A further improvement of the present invention lies in that the air coefficient of the excess air is set between 1.05 and 1.25, and the oxygen volume concentration is controlled within the range of 24% to 35%.

[0015] Compared with the prior art, the present invention has at least the following beneficial technical effects: The method and system for oxy-fuel co-combustion of organic waste liquid and pulverized coal and cascade recovery of waste heat provided by the present invention demonstrate significant advantages and technological progress, which are specifically reflected in the following aspects: 1. Efficient energy recovery: First, the organic waste liquid is concentrated to obtain a concentrated liquid and free water. Pulverized coal is added to the concentrated liquid to prepare a mixed slurry, which is atomized and burned under oxygen-rich conditions. This process not only ensures the full combustion of the organic waste liquid but also generates considerable waste heat. Subsequently, this waste heat is used to preheat the pulverized coal and the air required for combustion, further improving the overall energy utilization rate. The free water is used to absorb the waste heat of the flue gas and then supplied to users, achieving the effective recovery of the heat generated during the combustion of the organic waste liquid and achieving the purpose of efficiently using the free water.

[0016] 2. Recycling of water resources: The concentrated free water is used as an important part of the heat exchange stage, realizing the complete reuse of water resources within the system. This not only saves precious water resources but also reduces the dependence on external water sources, reflecting the environmental protection design concept.

[0017] 3. Multi-stage heat conversion mechanism: The system is equipped with a first heat exchange device and a multi-level heat exchange device including a second heat exchange device and a third heat exchange device, realizing the cascade utilization of the heat generated by the combustion of the organic waste liquid, effectively transferring the heat between the concentrated free water, the pulverized coal entering the system, and the air, so as to maximize the extraction and utilization of the energy in the organic waste liquid.

[0018] 4. Optimization of combustion conditions: By heating the air entering the slurry combustion device, the present invention effectively prevents heat loss caused by the introduction of external cold air and promotes a more complete combustion process. This method not only improves the combustion efficiency but also indirectly enhances the recovery rate of the energy of the organic waste liquid.

[0019] In summary, the method and system for oxy-fuel co-combustion of organic waste liquid and pulverized coal and cascade recovery of waste heat of the present invention can effectively convert the chemical energy in the organic waste liquid into heat energy, and by using the free water generated during the concentration process as a medium, maximize the recovery and utilization of this heat. At the same time, by preheating the pulverized coal and air entering the system, not only can the combustion efficiency be improved, but also the heat loss caused by the introduction of air can be avoided, thus realizing the full utilization of the energy of the organic waste liquid. Description of the Drawings

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings required for the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0021] Figure 1 It is a schematic flow chart of the method provided by the embodiment of the present invention; Figure 2 It is a schematic logical structure diagram of the system provided by the embodiment of the present invention; Figure 3 It is a schematic structural diagram of the system provided by the embodiment of the present invention; Wherein, 1 - organic waste liquid storage device, 2 - organic waste liquid concentration and separation device, 3 - stirring and pulping device, 31 - pulverized coal feeding part, 32 - pulping device, 4 - slurry combustion device, 41 - combustion furnace, 42 - atomizer, 43 - first heat exchange device, 5 - waste heat recovery device, 51 - heat exchange unit, 511 - second heat exchange device, 512 - third heat exchange device, 52 - gas transmission device, 6 - oxygen supply device, 61 - oxygen tank, 62 - oxygen injection valve, 7 - N-section ventilation duct, 71 - first ventilation duct, 72 - second ventilation duct, 73 - third ventilation duct, 8 - tail gas treatment unit, 9 - user unit, 10 - pulverized coal conveying device. Specific Embodiments

[0022] In the following text, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the accompanying drawings and the description are considered to be exemplary in nature rather than restrictive.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0025] In the present invention, unless otherwise clearly defined and limited, terms such as "mounted", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or a communication connection; it may be directly connected, or indirectly connected through an intermediate medium, and may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include the first and second features not being in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher level height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower level height than the second feature.

[0027] It should also be understood that the terms used in the specification of the present invention are for the purpose of describing particular embodiments only and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0028] It should be further understood that the term " / and" as used in the specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0029] Various structural schematic diagrams according to the disclosed embodiments of the present invention are shown in the accompanying drawings. These figures are not drawn to scale, where certain details are enlarged for the purpose of clear expression, and certain details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art can additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0030] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] Embodiment 1 As Figure 2 and Figure 3 shown, an organic waste liquid and pulverized coal oxy-fuel co-combustion and waste heat cascade recovery system of the present invention includes a complete set of organic waste liquid and pulverized coal oxy-fuel co-combustion and waste heat cascade recovery system. The main components of the system include: An organic waste liquid storage device 1 for storing organic waste liquid and feeding the organic waste liquid into an organic waste liquid concentration and separation device 2; The organic waste liquid concentration and separation device 2 is provided with a first liquid outlet and a second liquid outlet. The liquid outlet of the organic waste liquid storage device 1 is communicated with the liquid inlet of the organic waste liquid concentration and separation device 2, and is used for converting the organic waste liquid into a concentrated liquid containing concentrated organic waste liquid; A stirring and pulping device 3. The liquid inlet of the stirring and pulping device 3 is communicated with the first liquid outlet of the organic waste liquid concentration and separation device 2, and is used for fully mixing pulverized coal and the concentrated liquid. The stirring and pulping device 3 includes a pulverized coal feeding and stirring device 31 and a pulping device 32. The pulping device 32 includes a first feeding port and a second feeding port. The first liquid outlet of the organic waste liquid concentration and separation device 2 is communicated with the first feeding port of the pulping device 32, and the discharge port of the pulverized coal feeding and stirring device 31 is communicated with the second feeding port of the pulping device 32. The pulverized coal feeding device is provided with a liquid inlet; A slurry combustion device 4. The feeding port of the slurry combustion device 4 is communicated with the discharge port of the pulping device 32. The slurry combustion device 4 includes a combustion furnace 41, an atomizer 42, and a first heat exchange device 43. The feeding port of the atomizer 42 is communicated with the discharge port of the pulping device 32. The atomizer 42 is arranged in the combustion furnace and is used for atomizing and burning the mixed slurry. The gas outlet of the combustion furnace 41 is communicated with the gas inlet of the first heat exchange device 43. The first heat exchange device 43 is provided with a liquid inlet and a liquid outlet. The liquid inlet of the first heat exchange device 43 is communicated with the second liquid outlet of the organic waste liquid concentration and separation device 2, and is used for heating the free water separated in the organic waste liquid concentration and separation device 2 by using the waste heat of the flue gas. After the free water is heated, it supplies heat to the user unit 9; Waste heat recovery device 5, the waste heat recovery device 5 includes a heat exchange unit 51 and a gas transmission device 53. The heat exchange unit 51 includes a second heat exchange device 511, a third heat exchange device 512, and a pulverized coal conveying device 10. The second heat exchange device 511 includes a first air inlet, a second air inlet, a first air outlet, and a second air outlet; the air outlet of the first heat exchange device 43 is connected to the first air inlet of the second heat exchange device 511 to recover the waste heat of the flue gas after the combustion of the organic waste liquid in the slurry combustion device 4; the second air inlet of the second heat exchange device 511 is connected to the air outlet of the gas transmission device 53, and the first air outlet of the second heat exchange device 511 is connected to the air inlet of the combustion furnace 41 to preheat the oxygen-enriched oxygen fed into the combustion furnace 41 by using the waste heat of the flue gas; the discharge port of the pulverized coal conveying device 10 is connected to the feed port of the third heat exchange device 512, and the discharge port of the third heat exchange device 512 is connected to the feed port of the pulverized coal feeding and stirring device 31 to preheat the pulverized coal and then enter the pulverized coal feeding and stirring device 31 for stirring to form a slurry; Oxygen supply device 6, the oxygen supply device 6 includes an oxygen tank 61 and an oxygen injection valve 62. The first air inlet and the second air inlet of the oxygen supply device 6 are both provided on the oxygen injection valve 62. The first air inlet of the oxygen injection valve 62 is connected to the air outlet of the oxygen tank 61, the second air inlet of the oxygen injection valve 62 is connected to the first air outlet of the second heat exchange device 511, and the air outlet of the oxygen injection valve 62 is connected to the air inlet of the combustion furnace 41. The oxygen tank 61 is used to adjust the gas supply balance of supplying oxygen-enriched oxygen to the combustion furnace 41, and the oxygen injection valve 62 controls the gas input and output of the oxygen tank 61.

[0032] N-section ventilation duct, the N-section ventilation duct includes a first ventilation duct 71, a second ventilation duct 72, and a third ventilation duct 73. The air inlets of the first ventilation duct 71, the second ventilation duct 72, and the third ventilation duct 73 are respectively connected to the air outlet of the oxygen injection valve 62, and the air outlets of the first ventilation duct 71, the second ventilation duct 72, and the third ventilation duct 73 are respectively connected to the air inlet of the combustion furnace 41. The N-section ventilation duct can be used to adjust the uniform supply of oxygen-enriched oxygen to the combustion furnace 41.

[0033] As Figure 1 shown, the method for oxy-fuel co-combustion of organic waste liquid and pulverized coal and cascade waste heat recovery of the present invention is as follows: 1) Store the collected organic waste liquid to be treated in the organic waste liquid storage device 1; 2) Concentrate the collected organic waste liquid in the organic waste liquid concentration and separation device 2 to separate the concentrated liquid containing high-concentration organic matter and free water. Use the waste heat of the flue gas recovered from the first heat exchange device 43 to heat the free water separated in the organic waste liquid concentration and separation device 2, and the heated free water supplies heat to the user unit 9; the water content of the organic waste liquid before concentration > 70%, and the water content of the concentrated liquid after concentration is 15%; 3) Add pulverized coal into the concentrated liquid in the stirring and pulping device 3 and stir well to prepare a mixed slurry composed of water, pulverized coal and concentrated liquid. The pulverized coal is preheated by the third heat exchange device 512 and then sent to the pulverized coal feeding and stirring device 31 to be stirred into slurry; the mass ratio of water to pulverized coal in the mixed slurry is 35%:65%; the mass ratio of water to concentrated liquid in the mixed slurry is 15%:85%. 4) Atomize the above-mentioned mixed slurry in the atomizer 42 in the slurry combustion device 4 and then burn it. The combustion process is carried out under the conditions of oxygen-rich and with excess air participating, and the excess air needs to be preheated in advance. Its heat source comes from the waste heat of the flue gas recovered in the second heat exchange device 511 in step 5. The air coefficient of the excess air is set to 1.1, and the volume concentration of oxygen in the oxygen-rich oxygen is 30%.

[0034] 5) Through the first heat exchange device 43 in the slurry combustion device 4 and the second heat exchange device 512 and the third heat exchange device 513 in the waste heat recovery device, carry out multiple heat exchange processes to recover the waste heat in the flue gas. The waste heat of the flue gas is used to preheat the pulverized coal and the air required for combustion and to heat the free water; the flue gas after recovering the waste heat is sent to the chimney 8 for emission.

[0035] Example 2 When comparing Example 2 with Example 1, the differences between Example 2 and Example 1 are as follows: The air coefficient of the excess air is 1.05, and the volume concentration of oxygen in the oxygen-rich oxygen is 24%.

[0036] The mass ratio of water to pulverized coal in the mixed slurry is 30%:70%; the mass ratio of water to organic waste liquid in the mixed slurry is 10%:90%.

[0037] The water content of the concentrated liquid is 10%.

[0038] Example 3 When comparing Example 3 with Example 1, the differences between Example 3 and Example 1 are as follows: The air coefficient of the excess air is 1.25, and the volume concentration of oxygen in the oxygen-rich oxygen is 35%.

[0039] The mass ratio of water to pulverized coal in the mixed slurry is 40%:60%; the mass ratio of water to organic waste liquid in the mixed slurry is 20%:80%.

[0040] The water content of the concentrated liquid is 20%.

[0041] Comparative Example 1 When comparing Example 1 with Comparative Example 1, the differences between Example 1 and Comparative Example 1 are as follows: Do not heat the pulverized coal and the air entering the combustion furnace.

[0042] Comparative Example 2 When comparing Example 1 with Comparative Example 2, the differences between Example 1 and Comparative Example 2 are as follows: The air coefficient of excess air is 1.0, and the volume concentration of oxygen in the oxygen-enriched air is 20%.

[0043] The mass ratio of water to pulverized coal in the mixed slurry is 20%:80%; the mass ratio of water to organic waste liquid in the mixed slurry is 5%:95%.

[0044] The moisture content of the concentrated liquid is 5%.

[0045] Comparative Example 3 When comparing Example 1 with Comparative Example 3, the differences between Example 1 and Comparative Example 3 are as follows: The air coefficient of excess air is 1.3, and the volume concentration of oxygen in the oxygen-enriched air is 40%.

[0046] The mass ratio of water to pulverized coal in the mixed slurry is 50%:50%; the mass ratio of water to organic waste liquid in the mixed slurry is 30%:70%.

[0047] The moisture content of the concentrated liquid is 30%.

[0048] Related experiments The heat utilization rates during the implementation of Examples 1 - 3 and Comparative Examples 1 - 3 were respectively counted, and the results are shown in Table 1.

[0049] Test methods for related experiments Heat utilization rate: The heat generated by the slurry combustion device 4 after combustion, the exchanged heat of the first heat exchanger 43, the second heat exchanger 512, and the third heat exchanger 513, the heat loss of the pipeline itself, the heat of the externally introduced air, the heat of the exhausted tail gas, and the total theoretical combustion heat of the organic waste liquid were respectively counted.

[0050] Among them, the calculation formula for the heat loss rate is: Heat loss rate = (Heat of the externally introduced air + Total theoretical combustion heat - Heat generated by the slurry combustion device 4 - Exchanged heat of the first heat exchanger 43, the second heat exchanger 512, and the third heat exchanger 513 - Heat loss of the pipeline itself - Heat of the exhausted tail gas) / Total theoretical combustion heat Table 1: Test results of heat utilization rate

[0051] Specific analysis of Table 1 The heat utilization rate refers to the utilization situation of the heat generated by the combustion of the organic waste liquid after being processed by the method and system for co - combustion of organic waste liquid and pulverized coal with oxygen enrichment and cascade recovery of waste heat of the present invention. The higher the heat utilization rate, the higher the degree of heat recovery and utilization in the method and system.

[0052] From the data of Examples 1 - 3, it can be seen that: If the method and system for oxy-fuel co-combustion of organic waste liquid and pulverized coal and cascade recovery of waste heat in the present invention are adopted, the free water generated from the organic waste liquid during the concentration process can be used to absorb the waste heat of the flue gas, thereby converting the chemical energy in the organic waste liquid into heat energy for heating users. The heat extracted from the flue gas is used to heat the pulverized coal and air entering the system, so as to ensure the effective utilization of heat during the subsequent combustion process, and the overall heat utilization rate is above 70%.

[0053] It can be seen from the data of Comparative Examples 1-3 that: If the waste heat of the flue gas in the present invention is not used to heat the pulverized coal and air, it will lead to a low heat utilization rate of the system.

[0054] If the process conditions or parameters adopted are not within the scope of the conditions of the present invention, the heat utilization rate of the system of the present invention will be reduced.

[0055] Conclusion One or more technical solutions in the embodiments of the present invention at least further have the following technical effects or advantages: 1. The method provided by the embodiment of the present invention first concentrates the organic waste liquid to obtain a concentrated liquid and free water, and the free water absorbs the waste heat of the flue gas to supply heat to users; then the pulverized coal preheated by the waste heat of the flue gas is added to the concentrated liquid for mixing to obtain a water-coal-organic waste liquid mixed slurry, and the oxygen-enriched oxygen is preheated by the waste heat of the flue gas, and then the mixed slurry is atomized and burned under oxygen-enriched conditions, so that the organic waste liquid burns sufficiently. The waste heat of the flue gas is recovered through a multi-stage heat exchange device, so that the heat energy converted from the chemical energy of the organic waste liquid is subjected to energy cascade utilization.

[0056] 2. In the method provided by the embodiment of the present invention, since the free water after concentrating the organic waste liquid is used to supply heat to users, the water resources in the system can be fully utilized, which is energy-saving, environmentally friendly and harmless.

[0057] 3. The system provided by the embodiment of the present invention can effectively realize the conversion between the heat generated by the combustion of the organic waste liquid and the heat of the concentrated free water, the heat of the pulverized coal entering the system and the heat of the air entering the system by adopting the first heat exchange device, the second heat exchange device and the third heat exchange device, and further realize the effective extraction of the heat of the organic waste liquid.

[0058] The foregoing has shown and described the basic principles, main features and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0059] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment only contains an independent technical solution. This narrative style of the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. Organic waste liquid and coal powder oxygen-enriched co-combustion and waste heat cascade recovery system, characterized in that: include: An organic waste liquid collection and storage device is used to store organic waste liquid and send the organic waste liquid to an organic waste liquid concentration and separation device; An organic waste liquid concentration and separation device is used to convert the organic waste liquid into a concentrate and free water; A stirring slurry device, used to mix the concentrated liquid with coal powder to form a mixed slurry; Slurry combustion device, used to complete the atomization and combustion of mixed slurry and the initial waste heat recovery of flue gas; Waste heat recovery device, which recovers the waste heat of flue gas generated during the combustion process and uses it to preheat coal powder and air; Oxygen supply device ensures that the combustion environment has a suitable oxygen concentration to promote complete combustion.

2. The system for oxygen-enriched co-combustion of organic waste liquid and coal powder and cascade recovery of waste heat according to claim 1 is characterized in that: The organic waste liquid concentration and separation device is provided with a first liquid outlet and a second liquid outlet. The liquid outlet of the organic waste liquid collection and storage device is connected to the liquid inlet of the organic waste liquid concentration and separation device, and is used to convert the organic waste liquid into a concentrated liquid containing concentrated organic waste liquid.

3. The system for oxygen-enriched co-combustion of organic waste liquid and pulverized coal and cascade recovery of waste heat according to claim 1 is characterized in that: The liquid inlet of the stirring and pulping device is connected to the first liquid outlet of the organic waste liquid concentration and separation device, so as to fully mix the coal powder and the concentrated liquid; the stirring and pulping device comprises a coal powder feeding and stirring device and a pulping device, the pulping device comprises a first feed inlet and a second feed inlet, the first liquid outlet of the organic waste liquid concentration and separation device is connected to the first feed inlet of the pulping device, the discharge port of the coal powder feeding and stirring device is connected to the second feed inlet of the pulping device, and the coal powder feeding device is provided with a liquid inlet.

4. The system for oxygen-enriched co-combustion of organic waste liquid and pulverized coal and cascade recovery of waste heat according to claim 3 is characterized in that: The slurry combustion device comprises a combustion furnace, an atomizer and a first heat exchange device. The feed inlet of the slurry combustion device is connected to the discharge port of the pulping device, the feed inlet of the atomizer is connected to the discharge port of the pulping device, the atomizer is arranged in the combustion furnace, and is used to atomize and burn the mixed slurry. The air outlet of the combustion furnace is connected to the air inlet of the first heat exchange device. The first heat exchange device is provided with a liquid inlet and a liquid outlet. The liquid inlet of the first heat exchange device is connected to the second liquid outlet of the organic waste liquid concentration and separation device, and is used to utilize the waste heat of flue gas to heat the free water separated in the organic waste liquid concentration and separation device. After the free water is heated, it supplies heat to the user unit.

5. The system for oxygen-enriched co-combustion of organic waste liquid and pulverized coal and cascade recovery of waste heat according to claim 4 is characterized in that: The waste heat recovery device includes a heat exchange unit and a gas transmission device, and the heat exchange unit includes a second heat exchange device, a third heat exchange device and a pulverized coal conveying device; the second heat exchange device includes a first air inlet, a second air inlet, a first air outlet, and a second air outlet; the air outlet of the first heat exchange device is connected to the first air inlet of the second heat exchange device, so as to realize the recovery of the waste heat of the flue gas after the combustion of the organic waste liquid in the slurry combustion device; the second air inlet of the second heat exchange device is connected to the air outlet of the gas transmission device, and the first air outlet of the second heat exchange device is connected to the air inlet of the combustion furnace, so as to utilize the waste heat of the flue gas to preheat the oxygen-enriched oxygen fed into the combustion furnace; the discharge port of the pulverized coal conveying device is connected to the feed port of the third heat exchange device, and the discharge port of the third heat exchange device is connected to the feed port of the pulverized coal feeding and stirring device, so as to preheat the pulverized coal and enter the pulverized coal feeding and stirring device for stirring to form a slurry.

6. The system for oxygen-enriched co-combustion of organic waste liquid and pulverized coal and cascade recovery of waste heat according to claim 5 is characterized in that: The oxygen supply device includes an oxygen tank and an oxygen injection valve. The first air inlet and the second air inlet of the oxygen supply device are both arranged on the oxygen injection valve. The first air inlet of the oxygen injection valve is connected to the air outlet of the oxygen tank, the second air inlet of the oxygen injection valve is connected to the first air outlet of the second heat exchange device, and the air outlet of the oxygen injection valve is connected to the air inlet of the combustion furnace. The oxygen tank is used to adjust the air supply balance of oxygen-enriched oxygen supplied to the combustion furnace, and the oxygen injection valve controls the gas supply and discharge of the oxygen tank.

7. The system for oxygen-enriched co-combustion of organic waste liquid and pulverized coal and cascade recovery of waste heat according to claim 4 is characterized in that: Also includes: N sections of ventilation ducts, the N sections of ventilation ducts include a first ventilation duct, a second ventilation duct and a third ventilation duct, the air inlets of the first ventilation duct, the second ventilation duct and the third ventilation duct are respectively connected to the air outlet of the oxygen injection valve, and the air outlets of the first ventilation duct, the second ventilation duct and the third ventilation duct are respectively connected to the air inlet of the combustion furnace; the N sections of ventilation ducts are used to adjust the uniform supply of oxygen-enriched oxygen to the combustion furnace.

8. A method for oxygen-enriched co-combustion of organic waste liquid and coal powder and cascade recovery of waste heat, characterized in that: The method is based on the oxygen-enriched co-combustion of organic waste liquid and coal powder and the waste heat cascade recovery system according to any one of claims 1 to 7, comprising: (1) Storing the collected organic waste liquid to be treated in the organic waste liquid storage device; (2) Concentrating the collected organic waste liquid in an organic waste liquid concentration and separation device to separate a concentrated liquid containing high-concentration organic matter and free water; (3) adding the coal powder to the concentrated liquid in a stirring slurry making device and stirring the mixture sufficiently to prepare a mixed slurry consisting of water, the coal powder and the concentrated liquid; (4) The mixed slurry is atomized and then burned in the slurry combustion device. The combustion process is carried out under the conditions of oxygen-rich and excess air. The excess air needs to be preheated, and its heat source comes from the recovered flue gas waste heat; (5) Recovering waste heat from flue gas by performing multiple heat exchange processes through a slurry combustion device and a waste heat recovery device; wherein the waste heat from flue gas is used to preheat pulverized coal and air required for combustion.

9. The method for oxygen-enriched co-combustion of organic waste liquid and coal powder and cascade recovery of waste heat according to claim 8, characterized in that: The water content of the organic waste liquid before concentration exceeds 70%, and the water content of the concentrated liquid after concentration should be between 10% and 20%; the mass ratio of water to coal powder in the mixed slurry is maintained at 30%~40%:60%~70%, and the mass ratio of water to concentrated liquid should be maintained at 10%~20%:80%~90%.

10. The method for oxygen-enriched co-combustion of organic waste liquid and coal powder and cascade recovery of waste heat according to claim 8, characterized in that: The air coefficient of excess air is set between 1.05 and 1.25, and the oxygen volume concentration is controlled in the range of 24% to 35%.

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