A centralized compressed air production system based on multi-source coupling of coal-fired units

Abstract

The present invention discloses a centralized compressed air production system based on multi-source coupling of coal-fired units. The sludge collection and drying system includes a sludge storage, a crane grab bucket, a first screw conveyor, a dehydration device, a second screw conveyor, a paddle dryer, and a scraper. The paddle dryer has a drying heat source inlet. The blending and coordinated incineration system includes a coal storage, a loader, a primary mixing bin, a lifting conveyor, a secondary mixing bin, and a circulating fluidized bed boiler. The circulating fluidized bed boiler has a boiler steam outlet and a boiler steam inlet. The compressed air production system includes a back-pressure steam turbine, a first compressor, a condensing tractor, and a second compressor. The back-pressure steam turbine has a first steam inlet and a first steam outlet, and the condensing tractor has a second steam inlet and a second steam outlet. The system achieves compressed air production by coupling heat sources at multiple locations to drive the compressed air production system. It has comprehensive functions and strong practicality.

Description

Technical Field

[0001] The present invention relates to the technical field of energy recovery, and more particularly to a centralized compressed air production system based on multi-source coupling of coal-fired units. Background Art

[0002] Compressed air, the second most important power source after electricity, is clear, transparent, easy to transport, has no harmful properties, poses no fire hazard, is not susceptible to overload, and can operate in many adverse environments. It has been widely used in the textile and water treatment industries. In particular, an increasing number of processes in the textile industry are being completed using pneumatic technology. Currently, pneumatic applications are widely used in fiber material conveying, rubber roller pressurization, mobile workstations, jet air processing, jet automation technology, and component cleaning. However, traditional processes often rely on the existing power grid, using high-quality electricity converted through small screw air compressors. These units are dispersed, have small capacity, low energy conversion efficiency, and high carbon emissions, making them difficult to manage. Furthermore, solid waste such as scraps and industrial sludge generated during industrial park manufacturing processes is not effectively treated and accumulates around the park, potentially impacting the surrounding environment. While the conventional disposal method, sanitary landfill, offers the advantages of high throughput, rapid processing, and low cost, it is often limited by land availability and lacks sufficient space for disposal. Furthermore, the complex composition of these sludge and scraps, and the fermentation-generated leachate and greenhouse gases, make them uneconomical according to current environmental protection requirements.

[0003] In recent years, the drying and co-incineration of organic solid waste has been widely developed, and it has undoubtedly become the most thorough route for reduction, stabilization, harmlessness and resource utilization. Chinese patent CN103395958 A invented a disc-type dryer. Although it can effectively treat wet sludge, it does not consider the contribution of convective heat transfer to heat transfer and has high requirements for mud quality. Chinese patent CN102153256 A invented a sludge treatment method and a sludge treatment system, which provides ideas for the coordinated disposal of organic solid waste. However, the types of solid waste that can be disposed of are limited, and the co-incineration process has serious pipe blockage and sticking problems. It also does not combine solid waste disposal with centralized compressed air supply. Therefore, can the two be combined to dispose of the solid waste in the park while providing a centralized compressed air production method with the help of the existing heat network pipe rack in the park, providing clean and green comprehensive energy for the park's production and manufacturing. Assist in the construction of a circular economy industrial park.

[0004] Based on this, the present invention proposes a centralized compressed air production system based on multi-source coupling of coal-fired units. Summary of the Invention

[0005] The purpose of the present invention is to provide a method that can solve the shortcomings of the above-mentioned technologies, so as to achieve safe, efficient, low-cost, resource-based, harmless, reduced, stabilized and large-scale disposal of solid waste in the park, and at the same time provide the region with a green, low-carbon energy compressed air and steam.

[0006] To solve the above technical problems, the purpose of the present invention is achieved as follows: The present invention relates to a centralized compressed air production system based on multi-source coupling of coal-fired units, comprising a sludge collection and drying system, a blending and coordinated incineration system, a compressed air production system, and a flue gas treatment system;

[0007] The sludge collection and drying system includes a mud storage, a driving grab, a first screw conveyor, a dewatering device, a second screw conveyor, a paddle dryer and a scraper. The driving grab conveys the wet sludge stored in the mud storage to the first screw conveyor. The output end of the first screw conveyor is connected to the input end of the dewatering device, the output end of the dewatering device is connected to the input end of the second screw conveyor, the output end of the second screw conveyor is connected to the input end of the paddle dryer, the output end of the paddle dryer is connected to the input end of the scraper, and the paddle dryer has a drying heat source inlet.

[0008] The blending and coordinated incineration system includes a coal storage, a loader, a primary mixing bin, a lifting conveyor, a secondary mixing bin and a circulating fluidized bed boiler. The loader transports the coal stored in the coal storage to the primary mixing bin. The output end of the scraper is connected to the primary mixing bin. The lifting conveyor transports the material in the primary mixing bin to the secondary mixing bin. The output end of the secondary mixing bin is connected to the input end of the circulating fluidized bed boiler. The circulating fluidized bed boiler has a boiler steam outlet and a boiler steam inlet.

[0009] The compressed air production system includes a back-pressure steam turbine, a first compressor, a condensing engine and a second compressor. The output shaft of the back-pressure steam turbine is transmission-connected to the input shaft of the first compressor, and the output shaft of the condensing engine is transmission-connected to the input shaft of the second compressor. The back-pressure steam turbine has a first steam inlet and a first steam outlet, and the condensing engine has a second steam inlet and a second steam outlet. The boiler steam outlet is connected to the first steam inlet, the first steam outlet is connected to the second steam inlet, and the second steam outlet is connected to the boiler steam inlet. A drying heat source outlet is also provided between the first steam outlet and the second steam inlet, which is connected to the drying heat source inlet through a pipeline.

[0010] The present invention is further configured such that: a condenser, a low-temperature heater, a deaerator, and a high-temperature heater are sequentially connected in series between the second steam outlet and the boiler steam inlet.

[0011] The present invention is further configured as follows: the circulating fluidized bed boiler has a flue gas outlet; the flue gas treatment system includes an SNCR denitrification device, an SCR denitrification device, an electrostatic precipitator, an activated carbon adsorption filtration device, a wet desulfurization device and a wet electrostatic precipitator connected in series in sequence, the wet electrostatic precipitator has an exhaust port, and the inlet of the SNCR denitrification device is connected to the flue gas outlet.

[0012] The present invention is further configured such that: the wet desulfurization device is a limestone gypsum wet desulfurization absorption tower.

[0013] The present invention is further configured such that: the first screw conveyor and the second screw conveyor are both shaftless screw conveyors.

[0014] The present invention is further configured such that: the dehydration equipment is a centrifugal dehydrator or an extrusion screw press.

[0015] In summary, the present invention has the following beneficial effects: the centralized compressed air production system based on multi-source coupling of coal-fired units involved in the present invention drives the compressed air production system by coupling heat sources at multiple source positions in the system, thereby realizing energy-saving production of compressed air, and using part of the surplus heat source for drying operation of the dryer, and the exhaust steam at the tail end continues to flow back to the boiler for heating after post-processing, with green emissions and environmental protection, high energy recovery and utilization rate, complete overall functions and strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flow chart of the centralized compressed air production system of the present invention. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the preferred embodiments of the present invention are described below in conjunction with specific examples. However, it should be understood that these descriptions are only for the purpose of further illustrating the features and advantages of the present invention, and are not intended to limit the patent claims of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0018] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0019] Example 1

[0020] See also Figure 1 As shown, the embodiment involves a centralized compressed air production system based on multi-source coupling of coal-fired units, including a sludge collection and drying system, a blending and coordinated incineration system, a compressed air production system, and a flue gas treatment system;

[0021] The sludge collection and drying system includes a mud storage 1, a driving grab 2, a first screw conveyor 3, a dewatering device 4, a second screw conveyor 5, a paddle dryer 6 and a scraper 7. The driving grab 2 conveys the wet sludge stored in the mud storage 1 to the first screw conveyor 3. The output end of the first screw conveyor 3 is connected to the input end of the dewatering device 4. The output end of the dewatering device 4 is connected to the input end of the second screw conveyor 5. The output end of the second screw conveyor 5 is connected to the input end of the paddle dryer 6. The output end of the paddle dryer 6 is connected to the input end of the scraper 7. The paddle dryer 6 has a drying heat source inlet.

[0022] The blending and coordinated incineration system includes a coal storage 8, a loader 9, a primary mixing bin 10, an elevating conveyor 11, a secondary mixing bin 12 and a circulating fluidized bed boiler 13. The loader 9 transports the coal stored in the coal storage 8 to the primary mixing bin 10. The output end of the scraper 7 is connected to the primary mixing bin 10. The elevating conveyor 11 transports the material in the primary mixing bin 10 to the secondary mixing bin 12. The output end of the secondary mixing bin 12 is connected to the input end of the circulating fluidized bed boiler 13. The circulating fluidized bed boiler 13 has a boiler steam outlet and a boiler steam inlet.

[0023] The compressed air production system includes a back-pressure steam turbine 14, a first compressor 15, a condensing engine 16 and a second compressor 17. The output shaft of the back-pressure steam turbine 14 is transmission-connected to the input shaft of the first compressor 15, and the output shaft of the condensing engine 16 is transmission-connected to the input shaft of the second compressor 17. The back-pressure steam turbine 14 has a first steam inlet and a first steam outlet, and the condensing engine 16 has a second steam inlet and a second steam outlet. The boiler steam outlet is connected to the first steam inlet, the first steam outlet is connected to the second steam inlet, and the second steam outlet is connected to the boiler steam inlet. A drying heat source outlet is also provided between the first steam outlet and the second steam inlet, which is connected to the drying heat source inlet through a pipeline.

[0024] Furthermore, a condenser, a low-temperature heater, a deaerator, and a high-temperature heater are sequentially connected in series between the second steam outlet and the boiler steam inlet.

[0025] Furthermore, the circulating fluidized bed boiler has a flue gas outlet; the flue gas treatment system includes an SNCR denitrification device 18, an SCR denitrification device 19, an electrostatic precipitator 20, an activated carbon adsorption filtration device 21, a wet desulfurization device 22 and a wet electrostatic precipitator 23 connected in series in sequence, the wet electrostatic precipitator 23 has an exhaust port 24, and the inlet of the SNCR denitrification device 18 is connected to the flue gas outlet.

[0026] Furthermore, the wet desulfurization device 22 is a limestone gypsum wet desulfurization absorption tower.

[0027] Furthermore, the first screw conveyor 3 and the second screw conveyor 5 are both shaftless screw conveyors.

[0028] Furthermore, the dehydration equipment 4 is a centrifugal dehydrator or an extrusion screw press.

[0029] In this implementation, the sludge collection and drying system is used to further dry the wet sludge and reduce its moisture content. After being collected and stored in a sludge storage tank, the sludge is dried by the drying system, reducing its moisture content to approximately 40%. The resulting waste gas and wastewater are treated to meet standards, with a portion of the reclaimed water undergoing advanced treatment for comprehensive utilization, and a portion discharged through pipelines.

[0030] The blending and coordinated incineration system combines various organic materials with coal for co-incineration. Dry sludge, after drying, is coupled with coal, and then further coupled with industrial park scraps (gypsum powder and biomass powder). This deep coupling further increases the fuel's calorific value and reduces its viscosity. After incineration in a circulating fluidized bed system, the resulting ash is transported and solidified.

[0031] In the compressed air production system, the steam generated after co-incineration drives a back-pressure steam turbine, which in turn drives the compressor to produce compressed air. A portion of the extracted steam serves as a heat source for the condensing turbine, driving the compressor to continue producing compressed air. The remaining heat is used as a heat source for sludge drying and as a supplementary heat source for the steam heating network main pipe, providing heat to users. The exhaust steam is cooled in the condenser and then passes through the low-temperature heater, deaerator, and high-temperature heater before returning to the boiler to continue absorbing heat.

[0032] The flue gas generated after the co-incineration in the flue gas treatment system undergoes selective non-catalytic reduction reaction (SNCR), B2 selective catalytic reduction technology (SCR), electrostatic precipitator, activated carbon adsorbent, limestone-gypsum wet desulfurization, and wet electrostatic precipitator, and is discharged through the emission port to meet the emission standards.

[0033] Currently, there are two methods for incinerating organic solid waste sludge: one is to directly incinerate wet sludge mixed with coal, and the other is to dry the wet sludge before mixing it with coal for incineration. Direct sludge incineration without drying has many disadvantages. Due to the high water content of the raw sludge, direct incineration in the furnace can easily lead to problems such as difficulty in controlling the bed temperature and overheating of the superheater. It also increases the amount of flue gas, exacerbating wear on the heating surfaces at the rear of the boiler. Furthermore, due to the high water content of the flue gas, the acid dew point of the flue gas is high, which aggravates low-temperature corrosion of the heating surfaces at the rear of the boiler. High exhaust temperatures increase heat loss from the incinerator, reducing boiler thermal efficiency. Furthermore, the sludge treatment capacity is limited, affecting boiler output and increasing flue gas treatment costs. Furthermore, dioxin emission concentrations in the flue gas are generally between 0.5 ngTEQ / m³ and 0.8 ngTEQ / m³, which is higher than the emission concentration of drying followed by incineration. Therefore, it is generally no longer used. Drying the sludge before incineration overcomes the disadvantages of direct incineration and is widely accepted. The following table lists several primary methods for pre-incineration sludge drying. The most scientific and rational approach is a combination of mechanical deep dehydration and steam drying (mechanical dehydration using a screw press followed by low-grade steam through a paddle dryer). This method achieves a fundamental balance between sludge thermal resource utilization and processing energy, while also reducing flue gas pollutant concentrations and enabling comprehensive utilization of ash and slag, achieving a harmonious balance of energy conservation and emission reduction. However, the high proportion of coal used in the single-fuel blend contributes to high carbon emissions. Furthermore, a moisture content of 40% falls within the sludge's viscosity range, which can easily cause blockage in coal pipes during routine operation, impacting equipment performance. Based on this, we proposed a multi-source coupling approach to further reduce the coal proportion and fuel viscosity, thereby further reducing carbon emissions and enabling centralized compressed air production.

[0034] The wet sludge in the drying step is stored in the mud storage 1 with a moisture content of about 89-90%. It is transported to the first screw conveyor 3 via the driving grab 2, and the moisture content is reduced to about 75% by the centrifugal dehydrator or the extrusion screw press 4. It is then transported to the paddle dryer 6 via the second screw conveyor 5. It is dried by partition heat exchange using 0.8 MPa, 180°C superheated steam (the heat source is extracted from the drying heat source inlet between the first steam outlet and the second steam inlet). The moisture content of the sludge after drying is controlled at about 40%, and it is continued to be transported by the scraper 7, waiting for further co-incineration.

[0035] In the blending and coordinated incineration system, the loader 9 blends the coal from the coal storage 8 at a ratio of 6:3, then transports it to the primary mixing bin 10. The mixed fuel is then lifted by the elevator conveyor 11 and transferred to the secondary mixing bin 12, where it can be mixed with a certain amount of gypsum powder and biomass sawdust. After thorough mixing, it is fed into the circulating fluidized bed boiler 13 for "3T" coordinated incineration. This blending and coordinated incineration of various organic solid wastes within the industrial park is now complete. The furnace temperature is controlled between 850°C and 950°C, and a staged air supply is employed to ensure uniform oxygen concentration and stable bed temperature, further controlling the formation of nitrogen oxides. This staged air supply includes waste gases generated from the sludge storage and drying process during the drying step, which are mixed with air by a fan and then fed into the furnace in a staged manner. These gases primarily contain H2S, NH3, and organic acids. To ensure their complete decomposition, the incineration bed temperature is maintained above 800°C and a certain residence time is required to prevent the formation of dioxins. The ash produced after incineration is transported to the warehouse by compressed air and transported out for solidification, while the steam produced is used as the power of the tractor.

[0036] To fully utilize the enthalpy of steam in compressed air production, a back-pressure and condensing series system is used for cascaded energy utilization. Superheated steam at 8.8 MPa and 535°C is generated by combustion in the boiler. A flow rate of 70 t / h flows through two air inlets, driving the back-pressure tractor to rotate, which in turn drives the subsequent compressor through the coupling. Exhaust steam generated by the tractor is then discharged. After being filtered, the atmosphere is sent into the compressor and is further compressed during the rotation of the compressor impeller. After three-stage compression and two-stage intercooling, the pressure is increased by 0.8~0.9Mpa. After drying at 40~50 degrees Celsius, 1650m3 / min of compressed air is generated for heating users; and the 8.8Mpa, 535℃ steam becomes 0.98Mpa, 270℃ medium-pressure steam after the traction machine works, and part of it is used as the driving heat source of the condensing traction machine 27, which continues to drive the compressor to work, and further generates 1500m3 / min of compressed air R3. The excess part of the extracted steam is used to supplement the flow of the heat network main pipe, and is used as the heat source for steam transportation to the park heat users and sludge drying.

[0037] Next, in the exhaust gas treatment process, the flue gas generated after co-incineration undergoes selective non-catalytic reduction (SNCR) and selective catalytic reduction (SCR) technology, an electrostatic precipitator, activated carbon adsorbents, a flue gas waste heat recovery system, limestone-gypsum wet desulfurization, and wet electrostatic precipitators before being discharged through the outlet to meet standards. This system is fully integrated into the Smart Environmental Protection Island, leveraging low-voltage data science and technology to control treatment compliance at each node. It also leverages historical data for learning, further reducing operation and maintenance costs. Emission outlet monitoring data is connected to the Environmental Protection Bureau for precise monitoring.

[0038] Using the above example, the applicant carried out technical transformation based on the original daily sludge processing capacity of 2,050 tons. A 220t / h circulating fluidized bed was put into use, and a 1,500Nm3 / min back-type compressor and a 1,500Nm3 / min condensing compressor were installed as supporting equipment. After drying, the sludge moisture content was controlled at around 45%. A low-calorific-value coal-fired cogeneration project for heat, electricity, and gas was established and put into operation. The project can process 800,000 tons of organic solid waste annually, achieving good results:

[0039] 1. Main fuel indicators

[0040]

[0041] 2. Main operating indicators

[0042]

[0043] 3. Main economic indicators

[0044]

[0045] In summary, the entire process described above not only reduces the amount of solid waste disposed of within the industrial park, but also generates steam that can be used as a power source for compressed air production, electricity, and steam generation within the industrial park. It can also serve as a heat source for drying organic solid waste. This provides clean, green, and comprehensive energy for industrial park production and manufacturing, while also contributing to the development of a circular economy industrial park.

[0046] The centralized compressed air production system based on multi-source coupling of coal-fired units involved in the present invention drives the compressed air production system by coupling heat sources at multiple source positions in the system, thereby realizing energy-saving production of compressed air, and using part of the surplus heat source for drying operation of the dryer, and the exhaust steam at the tail end is further returned to the boiler for heating after post-processing. It has green emissions and is environmentally friendly, with a high energy recovery and utilization rate, complete overall functions, and strong practicality.

[0047] Unless otherwise specified, in the present invention, if there are terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicating orientation or positional relationship, they are based on the orientation or positional relationship actually shown and are 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. Therefore, the terms describing the orientation or positional relationship in the present invention are only used for illustrative purposes and cannot be understood as limiting this patent. For those skilled in the art, the specific meanings of the above terms can be understood in combination with the embodiments and according to specific circumstances.

[0048] Unless otherwise specified or limited, the terms "disposed," "connected," and "connected" in this disclosure should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections or indirect connections through an intermediary; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure based on the specific circumstances.

[0049] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A centralized compressed air production system based on multi-source coupling of coal-fired units, characterized in that: Including sludge collection and drying system, blending and coordinated incineration system, compressed air production system and flue gas treatment system; The sludge collection and drying system includes a mud storage, a driving grab, a first screw conveyor, a dewatering device, a second screw conveyor, a paddle dryer and a scraper. The driving grab conveys the wet sludge stored in the mud storage to the first screw conveyor. The output end of the first screw conveyor is connected to the input end of the dewatering device, the output end of the dewatering device is connected to the input end of the second screw conveyor, the output end of the second screw conveyor is connected to the input end of the paddle dryer, the output end of the paddle dryer is connected to the input end of the scraper, and the paddle dryer has a drying heat source inlet. The blending and coordinated incineration system includes a coal storage, a loader, a primary mixing bin, a lifting conveyor, a secondary mixing bin and a circulating fluidized bed boiler. The loader transports the coal stored in the coal storage to the primary mixing bin. The output end of the scraper is connected to the primary mixing bin. The lifting conveyor transports the material in the primary mixing bin to the secondary mixing bin. The output end of the secondary mixing bin is connected to the input end of the circulating fluidized bed boiler. The circulating fluidized bed boiler has a boiler steam outlet and a boiler steam inlet. The compressed air production system includes a back-pressure steam turbine, a first compressor, a condensing engine and a second compressor. The output shaft of the back-pressure steam turbine is connected to the input shaft of the first compressor, and the output shaft of the condensing engine is connected to the input shaft of the second compressor. The back-pressure steam turbine has a first steam inlet and a first steam outlet, and the condensing engine has a second steam inlet and a second steam outlet. The boiler steam outlet is connected to the first steam inlet, the first steam outlet is connected to the second steam inlet, and the second steam outlet is connected to the boiler steam inlet. A drying heat source outlet connected to the drying heat source inlet through a pipeline is also provided between the first steam outlet and the second steam inlet; a condenser, a low-temperature heater, a deaerator and a high-temperature heater are connected in series between the second steam outlet and the boiler steam inlet in sequence; the first screw conveyor and the second screw conveyor are both shaftless screw conveyors.

2. The centralized compressed air production system based on multi-source coupling of coal-fired units according to claim 1 is characterized in that: The circulating fluidized bed boiler has a flue gas outlet; the flue gas treatment system includes an SNCR denitrification device, an SCR denitrification device, an electrostatic precipitator, an activated carbon adsorption filtration device, a wet desulfurization device and a wet electrostatic precipitator connected in series in sequence, the wet electrostatic precipitator has an exhaust port, and the inlet of the SNCR denitrification device is connected to the flue gas outlet.

3. The centralized compressed air production system based on multi-source coupling of coal-fired units according to claim 2 is characterized in that: The wet desulfurization device is a limestone gypsum wet desulfurization absorption tower.

4. The centralized compressed air production system based on multi-source coupling of coal-fired units according to claim 1 is characterized in that: The dehydration equipment is a centrifugal dehydrator or an extrusion screw press.

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