Method for assisting coal-fired unit in sludge blending combustion through waste heat of internal combustion engine

Abstract

The invention relates to the field of municipal sludge drying and internal combustion engine flue gas utilization, in particular to a method for assisting a coal-fired unit to burn sludge in a mixed mode through waste heat of an internal combustion engine, and the method comprises the steps that high-temperature flue gas generated by the internal combustion engine is mixed; the mixed flue gas is used for performing multi-stage treatment on the sludge. Municipal sludge is dried by fully utilizing high-temperature flue gas drying waste heat of the internal combustion engine, and the overall energy efficiency of the system can be improved.

Description

Technical Field

[0001] The invention relates to the field of municipal sludge drying and internal combustion engine flue gas utilization, in particular to a method for internal combustion engine waste heat-assisted coal-fired unit to burn sludge. Background Art

[0002] Although advanced large-scale gas internal combustion engines can achieve a thermal efficiency of more than 45%, the exhaust gas temperature is still as high as 300 to 500 degrees Celsius. If the waste heat of this part of high-temperature flue gas is not effectively utilized, a large amount of energy loss will result. The traditional approach is to recover heat by installing a waste heat boiler and then use the generated steam to generate electricity. However, due to the low parameters of the generated steam, the power generation efficiency of this method is not ideal. In addition, the initial investment in adding a waste heat boiler power generation system is large, making the overall economic benefits not ideal.

[0003] In my country, many coal-fired power plants use pulverized coal combustion boilers. Coal needs to be ground into fine powder by a pulverizer, and then hot air is used to send the pulverized coal into the boiler for combustion. At present, some coal-fired power plants located around cities have begun to burn municipal sludge, which not only solves the problem of municipal sludge treatment, but also reduces carbon emissions by replacing part of the coal use. However, the municipal sludge produced by the sewage treatment plant is a paste-like substance with a water content of more than 80%. It cannot be directly mixed with pulverized coal for combustion and must be dried first. The traditional sludge drying method is to use high-temperature steam generated by the boiler to remove moisture, but this method will consume the steam of the boiler, reduce the power generation efficiency of the coal-fired power plant, and thus affect the overall economy of the power plant. Summary of the invention

[0004] In view of the above problems or problems existing in the prior art, the present invention is proposed.

[0005] Therefore, the purpose of the present invention is to provide a method for using waste heat from an internal combustion engine to assist a coal-fired unit in burning sludge, which can solve the problem that the flue gas from the internal combustion engine cannot be effectively utilized and the problem that sludge drying consumes boiler steam and reduces the power generation efficiency of the coal-fired power plant.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: a method for using waste heat from an internal combustion engine to assist a coal-fired unit in burning sludge, comprising mixing the high-temperature flue gas generated by the internal combustion engine; and performing multi-stage treatment on the sludge using the mixed flue gas.

[0007] As a preferred embodiment of the method of using waste heat from an internal combustion engine to assist a coal-fired unit in burning sludge, mixing the high-temperature flue gas generated by the internal combustion engine comprises mixing the high-temperature flue gas generated by the internal combustion engine with cold air in a mixer to form a mixed flue gas.

[0008] As a preferred scheme of the method of using waste heat from an internal combustion engine to assist a coal-fired unit in burning sludge, the high-temperature flue gas generated by the mixing internal combustion engine further comprises: controlling the ratio of the high-temperature flue gas and the cold air by a thermostat so that the temperature range of the mixed flue gas discharged from the mixer is controlled between 180 and 220 degrees.

[0009] As a preferred embodiment of the method of using waste heat from an internal combustion engine to assist a coal-fired unit in burning sludge, the method comprises: using mixed flue gas to perform multi-stage treatment on the sludge, including: using mixed flue gas to dry the dehydrated sludge to form dry sludge, and then recycling the dry sludge; using the mixed flue gas obtained by drying the dehydrated sludge to heat the wet sludge, and then treating the mixed flue gas to form dehydrated sludge; and discharging the mixed flue gas after heating the wet sludge.

[0010] As a preferred solution of the method for co-firing sludge in a coal-fired unit assisted by waste heat from an internal combustion engine of the present invention, drying the dehydrated sludge using the mixed flue gas includes drying the dehydrated sludge using the mixed flue gas in a sludge dryer.

[0011] As a preferred embodiment of the method of using waste heat from an internal combustion engine to assist a coal-fired unit in burning sludge, the method comprises: using the mixed flue gas obtained by drying the dehydrated sludge to heat the wet sludge in a sludge digester to heat the wet sludge, thereby destroying the cell walls in the wet sludge and causing the water in the cell walls to overflow.

[0012] As a preferred embodiment of the method for using waste heat from an internal combustion engine to assist a coal-fired unit in burning sludge, the further processing to form dehydrated sludge comprises: subjecting the wet sludge heated by the mixed flue gas to sedimentation and filter press processing to form dehydrated sludge.

[0013] As a preferred embodiment of the method of using waste heat from an internal combustion engine to assist a coal-fired unit in burning sludge, the method comprises: heating wet sludge with mixed flue gas obtained by drying dehydrated sludge, and then treating the mixed flue gas to form dehydrated sludge, wherein the temperature of the mixed flue gas obtained by drying the dehydrated sludge is 120 to 140°C.

[0014] As a preferred embodiment of the method of using waste heat from an internal combustion engine to assist a coal-fired unit in burning sludge, the method comprises: using the mixed flue gas obtained by drying the dehydrated sludge to heat the wet sludge in a sludge digester, and heating the wet sludge to 80 degrees by directly contacting the mixed flue gas obtained by drying the dehydrated sludge with the wet sludge.

[0015] As a preferred scheme of the method of burning sludge in a coal-fired unit assisted by waste heat from an internal combustion engine described in the present invention, recycling dry sludge includes sending the dry sludge into a coal mill and mixing it with coal and grinding it together, so that the sludge and coal powder are fully mixed to avoid the influence of uneven mixing on the combustion of the boiler.

[0016] The beneficial effects of the present invention are as follows: the method of using waste heat from an internal combustion engine to assist a coal-fired unit in burning sludge can improve the overall energy efficiency of the system by making full use of the waste heat from high-temperature flue gas drying of the internal combustion engine to dry the municipal sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0018] Figure 1 The overall structural diagram of the method for using waste heat from an internal combustion engine to assist coal-fired units in burning sludge. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0020] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0022] Example 1

[0023] Reference Figure 1 , which is the first embodiment of the present invention, provides a method for burning sludge in a coal-fired unit assisted by waste heat from an internal combustion engine, specifically comprising: mixing the high-temperature flue gas generated by the internal combustion engine 100; and performing multi-stage treatment on the sludge using the mixed flue gas.

[0024] Furthermore, mixing the high-temperature flue gas generated by the internal combustion engine 100 includes: mixing the high-temperature flue gas generated by the internal combustion engine 100 and cold air in the mixer 200 to form mixed flue gas.

[0025] Furthermore, the high-temperature flue gas generated by the hybrid internal combustion engine 100 also includes: adjusting the ratio of the high-temperature flue gas and the cold air through the temperature controller 600, so that the temperature range of the mixed flue gas discharged from the mixer 200 is controlled between 180 and 220 degrees, preferably 200 degrees.

[0026] It needs to be explained that although advanced large-scale gas internal combustion engines can achieve a thermal efficiency of more than 45%, the exhaust gas temperature is still as high as 300 to 500 degrees Celsius. If the waste heat of this part of high-temperature flue gas is not effectively utilized, a large amount of energy loss will result. The traditional approach is to recover heat by installing a waste heat boiler and then use the generated steam to generate electricity. However, due to the low parameters of the generated steam, the power generation efficiency of this method is not ideal. In addition, the initial investment in adding a waste heat boiler power generation system is large, making the overall economic benefits not ideal.

[0027] In response to these problems, the present invention controls the ratio of high-temperature flue gas and cold air through the thermostat 600, so that the temperature range of the mixed flue gas discharged from the mixer 200 is controlled between 180 and 220 degrees. Compared with the flue gas directly generated by the internal combustion engine 100 at a temperature of up to 300 to 500 degrees Celsius, the mixed flue gas at this temperature has a relatively stable temperature, and its heat energy can be effectively recovered by heat exchange equipment (such as a heat recovery boiler or a heat exchanger); the mixed flue gas between 180 and 220 degrees has a small temperature difference with the ambient temperature, and the heat loss is relatively low, which can more effectively retain heat energy and improve the overall thermal energy utilization efficiency; flue gas at a temperature of up to 300 to 500 degrees Celsius is prone to corrosion and wear in pipes and equipment, while the mixed flue gas between 180 and 220 degrees has a relatively small risk of damage to the equipment due to its lower temperature, thereby extending the service life of the equipment.

[0028] In this embodiment, the specific temperature control logic for the mixed flue gas is as follows: the temperature of the mixed gas is adjusted by changing the flow rate of cold air and the exhaust gas of the internal combustion engine 100, and the thermostat 600 monitors the exhaust temperature of the internal combustion engine and the ambient air temperature, adjusts the valve and monitors the temperature of the mixed flue gas to ensure that it is within the required range.

[0029] Example 2

[0030] Reference Figure 1 , which is the second embodiment of the present invention, and this embodiment is based on the previous embodiment.

[0031] Furthermore, the multi-stage treatment of sludge using the mixed flue gas includes: using the mixed flue gas to dry the dewatered sludge to form dry sludge, and then recycling the dry sludge; using the mixed flue gas after drying the dewatered sludge to heat the wet sludge, and then treating it to form dewatered sludge; and discharging the mixed flue gas after heating the wet sludge.

[0032] Furthermore, drying the dewatered sludge by using the mixed flue gas includes: drying the dewatered sludge by using the mixed flue gas in the sludge dryer 300 .

[0033] It should be noted that the sludge dryer 300 is mainly used to dehydrate and dry the sludge generated in the sewage treatment process. Its functions include reducing the volume of sludge to facilitate transportation and treatment; reducing treatment costs and improving the economy of the sewage treatment system; increasing the calorific value of the dried sludge so that it can be used for incineration to generate electricity or as fuel; improving the stability of the sludge, reducing pathogens and odor, and improving environmental friendliness; and facilitating subsequent incineration, composting and other treatments. This makes the sludge dryer play an important role in the sewage treatment system and improves the overall treatment efficiency.

[0034] It needs to be explained that: At present, some coal-fired power plants located around cities have begun to burn municipal sludge, which not only solves the problem of municipal sludge treatment, but also reduces carbon emissions by replacing part of the coal use. However, the municipal sludge produced by the sewage treatment plant is a paste-like substance with a water content of more than 80%. It cannot be directly mixed with coal powder for combustion and must be dried first. The traditional sludge drying method is to use high-temperature steam generated by the boiler to remove moisture, but this method will consume the boiler's steam, reduce the power generation efficiency of the coal-fired power plant, and thus affect the overall economic efficiency of the power plant.

[0035] In view of these problems, the present invention utilizes mixed flue gas to dry the dehydrated sludge, and can directly utilize the heat energy of the mixed flue gas, thus avoiding the consumption of high-temperature steam in the original technology.

[0036] Example 3

[0037] Reference Figure 1 , which is the third embodiment of the present invention, and this embodiment is based on the previous embodiment.

[0038] Furthermore, using the mixed flue gas obtained by drying the dewatered sludge to heat the wet sludge includes: using the mixed flue gas obtained by drying the dewatered sludge to heat the wet sludge in the sludge digester 400 to destroy the cell walls in the wet sludge, so that water in the cell walls overflows.

[0039] Furthermore, the mixed flue gas after the dewatered sludge is dried is used to heat the wet sludge, and then the dewatered sludge is formed by: the temperature of the mixed flue gas after the dewatered sludge is dried is 120-140°C; in the sludge digester 400, the mixed flue gas after the dewatered sludge is dried is used to heat the wet sludge, and the mixed flue gas after the dewatered sludge is dried is used to directly contact the wet sludge, so that the wet sludge is heated to 80 degrees.

[0040] It should be noted that a sludge digester is a device used to treat sludge generated during sewage treatment. Its main function is to decompose organic matter through microorganisms, significantly reduce the volume of sludge, and facilitate subsequent treatment and disposal; improve the stability of sludge, reduce corruption, odor and pathogen content; recycle the generated biogas for power generation, heating or fuel, and achieve resource recycling; reduce degradable organic matter and pathogens, thereby reducing the impact on the environment; and release nutrients (such as nitrogen and phosphorus), which can be used for soil improvement or fertilizer. Overall, sludge digesters improve treatment efficiency in sewage treatment systems and promote resource recovery and environmental protection.

[0041] It should be noted that by using the mixed flue gas after drying the dewatered sludge to heat the wet sludge, the thermal energy of the mixed flue gas can be further utilized; using the mixed flue gas at 120-140°C to heat the wet sludge to 80 degrees can cause the water in the cell walls of the wet sludge to overflow; discharging the moisture in the wet sludge in advance makes the dewatered sludge entering the sludge dryer 300 have lower moisture, thereby making the drying of the dewatered sludge more thorough.

[0042] Example 4

[0043] Reference Figure 1 , which is the fourth embodiment of the present invention, and this embodiment is based on the previous embodiment.

[0044] Further, the further processing to form dehydrated sludge includes: subjecting the wet sludge heated by the mixed flue gas to sedimentation and filter press 500 to form dehydrated sludge.

[0045] It should be noted that the filter press 500 is a device for solid-liquid separation, which is widely used in water treatment, mining, chemical industry, food, pharmaceutical and other industrial fields. Its main function is to separate liquid from solid by applying pressure to achieve the purpose of dehydration and concentration.

[0046] Furthermore, the recycling of dry sludge includes: feeding the dry sludge into a coal mill to mix with coal and grind them together, so that the sludge and coal powder are fully mixed.

[0047] It needs to be explained that many coal-fired power plants use pulverized coal combustion boilers. The coal needs to be ground into fine powder by a pulverizer, and then hot air is used to send the pulverized coal into the boiler for combustion.

[0048] It should be noted that feeding dry sludge into a coal mill and mixing it with coal for grinding and mixed combustion can make efficient use of resources. By combining the organic matter and heat energy in the sludge with coal powder, the emission and treatment costs of sludge can be reduced, while reducing fuel costs. By optimizing the combustion process, the uniformity and stability of combustion can be improved, the thermal energy conversion efficiency can be increased, and environmental pollution and the emission of unburned substances can be reduced. In addition, mixed combustion can significantly reduce dependence on landfills, promote resource recycling, and is in line with the concept of sustainable development.

[0049] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only several embodiments are described in detail in this disclosure, it should be easily understood by the personnel referring to this disclosure that many modifications are possible (for example, the size, scale, structure, shape and ratio of various elements, and parameter values ​​(for example, temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of a plurality of parts or elements, the position of the element can be inverted or otherwise changed, and the property or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method step can be changed or reordered according to alternative embodiments. Therefore, the present invention is not limited to specific embodiments, but extends to a variety of modifications still falling within the scope of the appended claims.

[0050] It should be understood that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but for those of ordinary skill having the benefit of this disclosure, the development effort will be a routine task of design, fabrication, and production without undue experimentation.

[0051] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for using waste heat from an internal combustion engine to assist coal-fired units in burning sludge, characterized in that: include, mixing high temperature flue gas generated by an internal combustion engine (100); The mixed flue gas is used to carry out multi-stage treatment of sludge.

2. The method for burning sludge in a coal-fired unit using waste heat from an internal combustion engine as claimed in claim 1, characterized in that: The high-temperature flue gas generated by the hybrid internal combustion engine (100) includes: In the mixer (200), high-temperature flue gas generated by the internal combustion engine (100) and cold air are mixed to form mixed flue gas.

3. The method for burning sludge in a coal-fired unit using waste heat from an internal combustion engine as claimed in claim 2, characterized in that: The high-temperature flue gas generated by the hybrid internal combustion engine (100) also includes: The ratio of high-temperature flue gas to cold air is regulated by a temperature controller (600), so that the temperature range of the mixed flue gas discharged from the mixer (200) is controlled between 180 and 220 degrees.

4. The method for burning sludge in a coal-fired unit using waste heat from an internal combustion engine as claimed in claim 3, characterized in that: The multi-stage treatment of sludge using mixed flue gas includes: The mixed flue gas is used to dry the dehydrated sludge to form dry sludge, and then the dry sludge is recycled; The mixed flue gas after drying the dewatered sludge is used to heat the wet sludge, and then the wet sludge is processed to form the dewatered sludge; Discharge the mixed flue gas after heating the wet sludge.

5. The method for burning sludge in a coal-fired unit using waste heat from an internal combustion engine as claimed in claim 4, characterized in that: Drying of dewatered sludge using mixed flue gas includes: The dehydrated sludge is dried using the mixed flue gas in the sludge dryer (300).

6. The method for burning sludge in a coal-fired unit using waste heat from an internal combustion engine as claimed in claim 5, characterized in that: Heating wet sludge by using mixed flue gas after drying dewatered sludge includes: In the sludge digester (400), the mixed flue gas obtained by drying the dehydrated sludge is used to heat the wet sludge, thereby destroying the cell walls in the wet sludge and causing the water in the cell walls to overflow.

7. The method for burning sludge in a coal-fired unit using waste heat from an internal combustion engine as claimed in claim 6, characterized in that: Reprocessing to form dewatered sludge includes: The wet sludge heated by the mixed flue gas is processed by sedimentation and filter press (500) to form dehydrated sludge.

8. The method for burning sludge in a coal-fired unit using waste heat from an internal combustion engine as claimed in claim 7, characterized in that: The mixed flue gas after drying the dewatered sludge is used to heat the wet sludge, and then the dewatered sludge is formed by processing: The temperature of the mixed flue gas after dewatered sludge drying is 120-140°C.

9. The method for burning sludge in a coal-fired unit using waste heat from an internal combustion engine as claimed in claim 8, characterized in that: The method of heating wet sludge in the sludge digester (400) by using the mixed flue gas after drying the dehydrated sludge includes: The wet sludge is heated to 80 degrees by using the mixed flue gas after the dewatered sludge is dried to directly contact with the wet sludge.

10. The method for burning sludge in a coal-fired unit using waste heat from an internal combustion engine as claimed in claim 9, characterized in that: Recycling of dry sludge includes: The dry sludge is fed into a coal mill to be mixed with coal and ground together so that the sludge and coal powder are fully mixed.

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