Furnace pretreatment system for sludge blending combustion of circulating fluidized bed boiler

Abstract

The utility model discloses a pre-treatment system for a sludge blending combustion furnace of a circulating fluidized bed boiler, which relates to the technical field of biomass environment-friendly treatment and comprises a sludge pre-treatment system, a sludge receiving and discharging platform, a pneumatic conveying system, a deodorization system and a sludge filtrate recovery system, the sludge filtrate recovery system is communicated with the sludge front pretreatment system, sludge treated by the sludge front pretreatment system is conveyed to the sludge receiving and discharging platform, the sludge receiving and discharging platform is communicated with the pneumatic conveying system, and the deodorization system is communicated with the sludge front pretreatment system, the sludge receiving and discharging platform and the pneumatic conveying system. According to the utility model, a new non-heat drying and pneumatic conveying viscous material closed treatment technology is adopted, and a mixed material pneumatic conveying test shows that after a mixed material enters the viscous material, the moisture content of the material is reduced by about 10%, the viscosity is greatly reduced, and the influence of material crushing and pneumatic conveying is greatly reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of biomass environmental protection treatment, and more specifically to the technical field of a circulating fluidized bed boiler mixed combustion sludge furnace pre-treatment system. Background Art

[0002] In recent years, with the acceleration of my country's urbanization and the rapid expansion of sewage treatment capacity in major cities, the amount of sludge has also increased significantly. According to research, approximately 70% of the sludge discharged from sewage treatment plants in 333 major cities in my country is not properly treated, resulting in significant pollution and re-pollution problems. The harmless treatment, reduction, and resource utilization of sludge are urgently needed.

[0003] At present, among many treatment and disposal methods, co-incineration process is considered to be one of the most effective technologies in sludge treatment. Relevant co-incineration power plants have been put into operation in China, achieving both harmless treatment of waste and economic benefits.

[0004] However, in order for sludge to be successfully co-combusted in power plants, it needs to go through sludge pre-treatment, storage and transportation. The commonly adopted treatment technology is to use a coal conveyor line to feed the sludge into the furnace for co-combustion after thermal drying (steam or flue gas) treatment. This method has the disadvantages of high energy consumption, high investment, complex system, large area and poor environmental protection.

[0005] Pneumatic conveying technology has the characteristics of strong sealing, fast material conveying / response speed, flexible pipeline layout, small footprint, and high level of automation control. It is widely used in the fields of dry (small particle) materials, medium and short distance transportation, and industrial conveying design with relatively poor layout conditions.

[0006] Sludge with a moisture content of 35%-60% is referred to as "plate and frame wet sludge" / Semi-dry sludge is a sticky material that resists fluidity. Once particles of the material come into contact with each other or with external objects, they tend to stick together and clumping, blocking the flow path. This poses a great threat to industrial design and operation such as material storage, transfer, and transportation.

[0007] So far, there are no relevant literature reports on pneumatic conveying of viscous materials. There is no mature experience to draw on for the storage, transfer and transportation of viscous materials, especially pneumatic conveying.

[0008] A new and different sludge treatment technology route was proposed in the sludge pretreatment, storage, transfer and transportation links, with the goal of achieving comprehensive advantages in technology, economy and environmental protection. In this process, a series of technical difficulties were encountered, mainly the following technical difficulties:

[0009] 1. How to reduce the moisture content of sludge, increase the calorific value of sludge, and reduce the latent heat of gasification consumed in the furnace when sludge is added to the furnace for co-combustion.

[0010] 2. For sticky sludge identified in the sludge pre-treatment stage, how to avoid sticking and clogging during the material receiving, storage and transfer stages? How to deal with the odor emitted in the sludge circulation stage and the wastewater generated in the pre-treatment stage?

[0011] 3. How to design the sticky sludge conveying system. Utility Model Content

[0012] The purpose of the utility model is to solve the above technical problems and provide a circulating fluidized bed boiler pre-treatment system for mixing sludge.

[0013] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0014] The utility model provides a circulating fluidized bed boiler co-firing sludge pretreatment system, comprising a sludge pre-pretreatment system, a sludge receiving and unloading platform, a pneumatic conveying system, a deodorizing system, and a sludge filtrate recovery system; the sludge filtrate recovery system is connected to the sludge pre-pretreatment system, the sludge treated by the sludge pre-pretreatment system is transported to the sludge receiving and unloading platform, the sludge receiving and unloading platform is connected to the pneumatic conveying system, and the deodorizing system is connected to the sludge pre-pretreatment system, the sludge receiving and unloading platform, and the pneumatic conveying system;

[0015] The pneumatic conveying system includes a sludge receiving hopper, a viscous material storage device, a mixed material storage device, a crushing and mixing device and a pneumatic conveying device coordinated with the sludge receiving and unloading platform; the sludge receiving hopper is connected to the feed port of the viscous material storage device, the discharge port of the viscous material storage device and the discharge port of the mixed material storage device are both connected to the feed port of the crushing and mixing device, and the discharge port of the crushing and mixing device is connected to the pneumatic conveying device.

[0016] Specifically, the mixing of viscous materials outside the furnace can, to a certain extent, increase the residence time of the mixed materials in the furnace to react with SO2, and to a certain extent save the total limestone powder resources of the power plant, improve resource utilization, and reduce resource consumption; the pneumatic conveying part can also greatly reduce the wear of equipment pipelines, increase the operating life of the facilities, and reduce operation and maintenance costs.

[0017] In one embodiment, the sludge pre-treatment system is a membrane plate and frame filter press system, and the sludge filtrate recovery system is connected to the liquid outlet of the membrane plate and frame filter press system.

[0018] The diaphragm plate and frame filter press system includes a modulation chamber, a diaphragm pump, a filter press, a pressurized water pump, a clean water tank, a scraper, and an air storage tank; the modulation chamber is connected to the feed port of the filter press through the diaphragm pump, the clean water tank is connected to the water inlet of the filter press through the pressurized water pump, the sludge outlet of the filter press is arranged above the scraper, the scraper outlet is connected to the sludge receiving and unloading platform (or connected to the sludge receiving and unloading platform through a trolley), and the air storage tank is connected to the air inlet of the filter press through a pipeline;

[0019] The liquid outlet of the filter press is connected to the sludge filtrate recovery system, which includes a filtrate box. The filtrate box is divided into two pipelines through a filtrate pump. One pipeline is connected to the tank truck and the other pipeline is connected to the conditioning tank.

[0020] Specifically, the control method for reducing the moisture content of sticky materials involves combining the impact of boiler combustion efficiency with the investment and operating energy consumption of the filter press equipment to determine the type of heatless drying equipment and the moisture content calculation method. Sludge with an 80% moisture content is transported to the plant by dedicated sludge trucks and directly to the sludge conditioning bin. Water is added to the conditioning bin to dilute the sludge moisture content to above 92%. Flocculants and coagulants are then added and mixed until uniform. The sludge is then pumped into a diaphragm filter press for primary dehydration. Once the primary dehydration is complete, a sludge cake is formed. A high-pressure pump is then activated to inject high-pressure water into the diaphragm plates, performing a secondary, powerful squeeze and dehydration process to reduce the cake moisture content to below 60%. The sludge cake falls into a scraper conveyor connected to the bottom and is transported to the sludge silo. The sludge filtrate is collected in a filtrate tank, partially pumped back to the conditioning bin for reuse, and the remainder is transported by tanker truck to the sewage treatment plant for treatment or within the plant.

[0021] In one embodiment, the sludge receiving and unloading platform is an openable and closable closed unloading platform.

[0022] In one embodiment, the sludge receiving hopper is connected to a bucket elevator, and the discharge port of the bucket elevator is connected to a viscous material storage device; the viscous material storage device is a sludge heatless drying treatment workshop or a sludge silo.

[0023] In one embodiment, two sludge discharge ports are provided at the bottom of the sludge silo, and a corresponding variable frequency discharge screw is provided at each sludge discharge port;

[0024] The blending material storage device includes two sludge crushers, and the feed port of each sludge crusher is connected to the discharge port of the corresponding variable frequency unloading screw;

[0025] The pneumatic conveying device includes two pneumatic conveyors, and the feed port of each pneumatic conveyor is connected to the discharge port of the corresponding sludge crusher.

[0026] In one embodiment, a discharge port is provided at the bottom of each pneumatic conveyor, and a conveying fan is connected to the side wall of each pneumatic conveyor through a pipeline.

[0027] In one embodiment, the admixture storage device includes a limestone powder silo and a hot air system connected to a side wall of the limestone powder silo, the hot air system including a hot air duct connected to the side wall of the limestone powder silo, a gasification blower and an electric heater both provided on the hot air duct;

[0028] The discharge port at the bottom of each limestone powder silo is divided into two pipelines, each pipeline is connected to the corresponding sludge crusher feed port, and each pipeline needs to be equipped with a frequency conversion feeder, which is linked with the frequency conversion unloading screw for adjustment and control to achieve control of the mixing ratio.

[0029] In one embodiment, the admixture storage device is a limestone powder silo.

[0030] In one embodiment, the deodorization system includes a deodorization air collecting hood, branch air collecting pipes connected to each deodorization air collecting hood, a main air collecting pipe connected to each branch air collecting pipe, and a negative pressure deodorization fan arranged on the main air collecting pipe. The main air collecting pipe is connected to the air inlet of the conveying fan. There are multiple deodorization air collecting hoods, which are respectively located in the sludge loading and unloading platform, the sticky material storage device, the crusher and the sludge pre-treatment system.

[0031] Specifically, considering the large energy consumption, land occupation and investment of traditional biomass and other deodorization systems, it is proposed to jointly design a negative pressure to positive pressure system with a pneumatic sludge conveying system, and send it into the furnace for co-combustion. This new process system has the characteristics of simple system, flexible control, low investment and energy consumption, and environmental protection.

[0032] In one embodiment, the deodorization system further comprises a telescopic odor-proof cover located inside the sludge receiving and unloading platform, a walking device is provided below the telescopic odor-proof cover, and two tracks cooperating with the walking device are provided on both sides of the inner bottom of the sludge receiving and unloading platform.

[0033] The beneficial effects of the utility model are as follows:

[0034] 1. The utility model proposes a new sludge mixing furnace pretreatment system that adopts the technology and control method of heatless drying + pneumatic conveying, wherein the control method is:

[0035] 1) Heatless drying: Using a diaphragm plate and frame filter press, the filter press system design indicators, such as moisture content, filter press pressure, type, etc., are determined by calculating the impact on boiler combustion efficiency, filter press system investment and operating energy consumption.

[0036] 2) Pneumatic conveying: To achieve pneumatic conveying of viscous materials, the method adopted is "one crushing, two blending, three controls". "One crushing" is to reasonably control the particle size distribution of crushed sludge, which also includes the selection of crusher; "two blending" is to reasonably control the blending ratio, which also includes the optimization of blending materials; "three controls" is to reasonably control the pneumatic conveying design parameters, such as material-gas ratio, pressure drop, gas volume, pipe diameter, etc.

[0037] 2. The utility model adopts a new closed treatment technology for sticky materials with heatless drying + pneumatic conveying, which not only greatly saves system investment, but also greatly saves operating energy consumption, so that the comprehensive economy and environmental protection of the co-firing of sticky materials in circulating fluidized bed boiler power plants are greatly enhanced, and it promotes the large-scale application of sludge treatment and disposal in circulating fluidized bed boiler power plants, laying a good foundation for the win-win situation of power plants and sewage treatment plants, and improving the environmental protection and social nature of sludge treatment and disposal.

[0038] 3. Simply reducing surface moisture cannot completely solve the problem of material stickiness. To address the sticking and blocking mechanism of semi-dry sludge, the idea of ​​adding an "isolation layer" between sticky particles was proposed. Furthermore, another "admixture" was introduced into the sludge as an isolation layer to break up the "agglomeration" and agglomeration conditions of the sticky material. Tests of pneumatic conveying of the admixture with this utility model showed that after the "admixture" was introduced into the sticky material, the moisture content of the material decreased by about 10%, the viscosity was significantly reduced, and the impact of material breakage and pneumatic conveying was greatly reduced.

[0039] 4. The pneumatic conveying technology for viscous materials proposed in this utility model has advanced technical indicators as a whole, good environmental protection, rapid adjustment response, and reasonable economic indicators (low investment and energy consumption indicators), filling the research gap in the field of pneumatic conveying of viscous materials.

[0040] 5. In conjunction with the sludge co-incineration related systems, it has obvious advantages over conventional treatment systems in terms of technology, economy and environmental protection.

[0041] 6. It has overcome the technical difficulties in pneumatic conveying of sticky materials that have long plagued the industry, filling the technological gap in this field. After a horizontal comparison of multiple schemes in terms of technology, economy and environmental protection, it is concluded that the system is industry-leading in terms of investment, energy consumption and environmental protection, and has broad prospects for promotion and application.

[0042] 7. It is proposed to design a new process system that combines the pneumatic sludge conveying system with a negative pressure to positive pressure deodorization system and sends it into the furnace for co-combustion. It has the characteristics of simple system, flexible control, low investment and energy consumption, and environmental protection.

[0043] 8. The wastewater generated during the sludge pre-filtration process is collected centrally and transported to the sewage treatment plant empty by sludge transport trucks for treatment. This is a simple method with the best economy and applicability.

[0044] 9. The unloading platform adopts a flexibly openable and closed enclosed space structure, and is equipped with a chain switch to achieve chaining with the negative pressure deodorization system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 It is a structural diagram of the utility model;

[0047] Figure 2 This is a structural diagram of the sludge receiving and unloading platform;

[0048] Figure 3 is a schematic diagram of the deodorization system;

[0049] Figure 4 is a schematic diagram of the sludge filtrate recovery system;

[0050] Figure 5 This is a graph showing the effect of sludge moisture content on boiler efficiency;

[0051] Figure 6 This is the relationship diagram between investment and energy consumption of heatless drying system;

[0052] Figure 7 It is a schematic diagram of the diaphragm plate and frame filter press system and the sludge filtrate recovery system;

[0053] Figure 8 It is a schematic diagram of the structure of the sludge receiving and unloading platform, pneumatic conveying system and deodorization system;

[0054] Figure markings: 1-sludge receiving hopper, 2-bucket elevator, 3-sludge crusher, 4-frequency conversion unloading screw, 5-sludge silo, 6-pneumatic conveyor, 7-limestone powder silo, 7a-frequency conversion feeder, 8-gasification fan, 9-electric heater, 10-conveying fan, 11-telescopic odor-proof hood, 12-traveling device, 13-track, 14-negative pressure deodorizing fan, 15-conditioning bin, 16-diaphragm pump, 17-filter press, 18-clean water tank, 19-pressure water pump, 20-filtrate box, 21-filtrate pump, 22-scraper, 23-gas storage tank. DETAILED DESCRIPTION

[0055] To make the technical problems, technical solutions, and technical effects of the present invention more clear, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0056] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0057] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. In addition, the terms "first," "second," etc. are used only to distinguish the descriptions and are not to be understood as indicating or implying relative importance.

[0058] In the description of the embodiments of the present invention, it should be noted that the terms "inside", "outside", "upper", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the present invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as a limitation on the present invention.

[0059] Example 1

[0060] like Figures 1 to 4 As shown, this embodiment provides a circulating fluidized bed boiler co-firing sludge pretreatment system, including a sludge pre-pretreatment system, a sludge receiving and unloading platform, a pneumatic conveying system, a deodorization system, and a sludge filtrate recovery system; the sludge filtrate recovery system is connected to the sludge pre-pretreatment system, and the sludge treated by the sludge pre-pretreatment system is transported to the sludge receiving and unloading platform, the sludge receiving and unloading platform is connected to the pneumatic conveying system, and the deodorization system is connected to the sludge pre-pretreatment system, the sludge receiving and unloading platform, and the pneumatic conveying system;

[0061] The pneumatic conveying system includes a sludge receiving hopper 1 coordinated with the sludge receiving and unloading platform, a viscous material storage device, a mixed material storage device, a crushing and mixing device, and a pneumatic conveying device; the sludge receiving hopper 1 is connected to the feed port of the viscous material storage device, the discharge port of the viscous material storage device and the discharge port of the mixed material storage device are both connected to the feed port of the crushing and mixing device, and the discharge port of the crushing and mixing device is connected to the pneumatic conveying device.

[0062] Specifically, the mixing of viscous materials outside the furnace can, to a certain extent, increase the residence time of the mixed materials in the furnace to react with SO2, and to a certain extent save the total limestone powder resources of the power plant, improve resource utilization, and reduce resource consumption; the pneumatic conveying part can also greatly reduce the wear of equipment pipelines, increase the operating life of the facilities, and reduce operation and maintenance costs.

[0063] Example 2

[0064] This embodiment is a further optimization based on the embodiment 1, specifically:

[0065] The sludge pre-treatment system is a diaphragm plate and frame filter press system, and the sludge filtrate recovery system is connected to the liquid outlet of the diaphragm plate and frame filter press system.

[0066] The diaphragm plate and frame filter press system includes a conditioning chamber 15, a diaphragm pump 16, a filter press 17, a pressurized water pump 19, a clean water tank 18, a scraper 22, and an air storage tank 23;

[0067] The conditioning chamber 15 is connected to the feed port of the filter press 17 via a diaphragm pump 16, the clean water tank 18 is connected to the water inlet of the filter press 17 via a pressurized water pump 19, the sludge outlet of the filter press 17 is arranged above the scraper 22, and the air storage tank 23 is connected to the air inlet of the filter press 17 via a pipeline;

[0068] The liquid outlet of the filter press 17 is connected to the sludge filtrate recovery system, which includes a filtrate box 20. The filtrate box 20 is divided into two pipelines through a filtrate pump 21. One pipeline is connected to the tank truck and the other pipeline is connected to the mixing tank 15.

[0069] Specifically, the control method for reducing the moisture content of sticky materials is to combine the influence of boiler combustion efficiency and the investment and operating energy consumption of filter press equipment to jointly determine the type of heatless drying equipment and the calculation method of moisture content.

[0070] The sludge receiving and unloading platform adopts an openable and closable closed unloading platform, and the opening and closing of the closed unloading platform is interlocked with the deodorization system.

[0071] Specifically, when the enclosed unloading platform is in the open state, the deodorization system starts working, and when the enclosed unloading platform is in the closed state, the deodorization system does not work.

[0072] Example 3

[0073] This embodiment is a further optimization based on the second embodiment, specifically:

[0074] The sludge receiving hopper 1 is connected to a bucket elevator 2, and the discharge port of the bucket elevator 2 is connected to a viscous material storage device; the viscous material storage device is a sludge heatless drying treatment workshop or a sludge silo 5.

[0075] There are two sludge discharge ports at the bottom of the sludge silo 5, and each sludge discharge port is provided with a corresponding variable frequency discharge screw 4;

[0076] The blending material storage device includes two sludge crushers 3, and the feed port of each sludge crusher 3 is connected to the discharge port of the corresponding variable frequency unloading screw 4;

[0077] The pneumatic conveying device includes two pneumatic conveyors 6 , and the feed port of each pneumatic conveyor 6 is connected to the discharge port of the corresponding sludge crusher 3 .

[0078] A discharge port is provided at the bottom of each pneumatic conveyor 6 , and a conveying fan 10 is connected to the side wall of each pneumatic conveyor 6 through a pipeline.

[0079] The admixture storage device includes a limestone powder bin 7 and a hot air system connected to the side wall of the limestone powder bin 7. The hot air system includes a hot air duct connected to the side wall of the limestone powder bin 7, a gasification blower 8 and an electric heater 9 both of which are arranged on the hot air duct;

[0080] The discharge port at the bottom of each limestone powder bin 7 is divided into two pipes, each pipe is connected to the corresponding sludge crusher 3 feed port, each pipe is equipped with a variable frequency feeder 7a, and is interlocked with the variable frequency unloading screw 4 for adjustment and control to achieve mixing ratio control.

[0081] Example 4

[0082] This embodiment is a further optimization based on the embodiment 3, specifically:

[0083] The deodorization system includes a deodorizing air collecting hood, branch air collecting pipes connected to each deodorizing air collecting hood, a main air collecting pipe connected to each branch air collecting pipe, a negative pressure deodorizing fan 14 arranged on the main air collecting pipe, and the main air collecting pipe is connected to the air inlet of the conveying fan 10. There are multiple deodorizing air collecting hoods, which are respectively located in the sludge receiving and unloading platform, the sticky material storage device, the sludge crusher and the sludge pre-treatment system.

[0084] Specifically, considering the large energy consumption, land occupation and investment of traditional biomass and other deodorization systems, it is proposed to jointly design a negative pressure to positive pressure system with a pneumatic sludge conveying system, and send it into the furnace for co-combustion. This new process system has the characteristics of simple system, flexible control, low investment and energy consumption, and environmental protection.

[0085] The deodorization system also includes a telescopic odor-proof cover 11 located inside the sludge receiving and unloading platform. A walking device 12 is provided below the telescopic odor-proof cover 11. Two tracks 13 cooperating with the walking device 12 are respectively provided on both sides of the inner bottom of the sludge receiving and unloading platform.

[0086] Feasibility analysis of Example 4:

[0087] 1. Based on the feasibility analysis of the sludge pretreatment system, the following work was carried out:

[0088] 1) Investigated various types of heatless drying systems;

[0089] 2) The influence of sludge moisture content on boiler efficiency was studied and the relevant curve was drawn (see Figure 5 : Effect of sludge moisture content on boiler efficiency);

[0090] 3) After economic comparison of various heatless drying technologies, a membrane plate and frame filter press system was selected;

[0091] 4) The relationship between the water content of the membrane plate and frame filter press system and the system investment and energy consumption was studied, and the relevant curve was drawn (see Figure 6 : Relationship diagram between investment and energy consumption of heatless drying system);

[0092] 5) Based on the relationship between sludge moisture content and boiler efficiency, a technical and economic comparison of multiple heatless drying technologies was conducted, and the diaphragm plate and frame filter press system was finally determined as our recommended system, and the optimal technical parameter points of the system were determined.

[0093] 2. The following work was carried out for the feasibility analysis of the pneumatic conveying system, deodorization system and sludge filtrate recovery system:

[0094] 1) The material properties of the sludge with moisture content determined in the sludge pre-treatment process were analyzed; it was found that the sludge moisture content and viscosity were closely related to the filter press sludge conditioning agent (ash content), and were also related to the filter press pressure, time, etc.

[0095] 2) Conducted research on the process of receiving, storing, and transferring materials in the sludge plant, and mastered the relevant system design and equipment selection (see Figure 7 : Telescopic odor shield for unloading platform).

[0096] 3) Considering the large energy consumption, land occupation and investment of traditional biomass deodorization systems, it is proposed to design a new process system that is combined with the pneumatic sludge conveying system to convert negative pressure into positive pressure and send it into the furnace for mixed combustion. This system has the characteristics of simple system, flexible control, low investment and energy consumption, and environmental protection (see Figure 3 : Sludge odor negative pressure to positive pressure system).

[0097] 4) Sludge filtrate recovery system: The wastewater generated during the sludge pre-filtering process is collected centrally and transported to the sewage treatment plant in a simple way with empty sludge transport trucks. This is the most economical and applicable method (see Figure 4 : Sludge filtrate recovery system).

[0098] 3. The feasibility analysis and experimental research of the pneumatic conveying system for sticky sludge have been carried out in the following aspects:

[0099] 3.1. Phase I: Initial (original / air-dried) sludge test study:

[0100] (1) The properties of two representative sticky sludge materials were tested and analyzed, and one of them was selected for the following research;

[0101] (2) Conducted crushing test research and determined to use blade / axe crusher type;

[0102] (3) Air drying / drying test research was conducted;

[0103] (4) Experimental study on pneumatic conveying of undisturbed / air-dried sludge was conducted.

[0104] Through the above experimental research, it was found that the viscosity of the material has a great influence on the crushing, air drying and conveying systems. The particle size of the crushed particles is inversely proportional to the viscosity of the material. Air drying has little effect on the viscosity of the material. Regardless of the original or air-dried sludge, pneumatic conveying blockage occurs frequently, the system output is small, the gas consumption is large, the system operation is unstable, and the pneumatic conveying of sticky materials is unsuccessful.

[0105] 3.2 The second stage of work: cause analysis and proposal of innovative ideas:

[0106] (1) Cause analysis and research, analyzing the mechanism of sticking and blocking of pneumatically conveyed viscous materials: During the transportation process of silo pumps and pipelines, viscous materials are subjected to wear and extrusion, which makes it easy for internal moisture to "drill out", and the overall "stickiness" is enhanced, making it easy to adhere to the inner wall of equipment, pipelines, and elbows, causing blockage;

[0107] (2) Innovative ideas were proposed. To address the sticking mechanism, the idea of ​​adding an "isolation layer" between the sticky particles was proposed. Furthermore, another "admixture" was introduced as an "isolation layer" to break the "agglomeration and agglomeration" conditions of the sticky material, as well as the requirements for the material properties of this material:

[0108] 1) The material is easily available in power plants and does not need to be purchased separately;

[0109] 2) The particle size is smaller than that of the crushed particles and the specific surface area is larger. The particle structure surface is preferably irregular and porous, with strong water absorption and can evenly "adhere" to the surface of the crushed sludge particles.

[0110] 3) The bulk density and hardness are relatively large. During pneumatic conveying, the "admixture" has a certain "abrasiveness", which can "offset" the effect of sludge particles "adhering" to the pipeline and blocking it to a certain extent.

[0111] (3) “Blending materials” include limestone powder, coal powder, fly ash, bottom ash, bed material, biomass material, etc. Limestone powder was selected for the test, mainly considering the characteristics of limestone powder and making full use of the existing furnace conveying system of the power plant. The two materials were mixed and conveyed, which not only solved the problem of viscous material transportation blockage, but also improved the wear problem of limestone powder transportation alone.

[0112] 3.3 The third phase of work: Adjustment (mixing with limestone powder) sludge test research:

[0113] (1) Conduct limestone powder blending test research, including blending ratio test and mixture material property test;

[0114] (2) Conducting experimental research on pneumatic conveying of mixtures to determine the optimal conveying parameters;

[0115] (3) Carry out simulation to obtain the optimal technical parameters of the system under different conditions.

[0116] The above research found that the addition of "admixture" to viscous materials reduced the material's moisture content and, more importantly, its viscosity, significantly reducing material breakage and the impact of pneumatic conveying. Key findings include: when the sludge conveying distance is between 100 and 300 meters, the output of a single system is ≤7.2 tons / hour, and the limestone powder blending ratio is 30%, the material clumping and blockage problem disappears, the pneumatic conveying system operates smoothly, and the material-to-air ratio is 13.08, effectively eliminating pipeline blockage.

[0117] 4. For supporting projects, we conducted technical and economic comparative studies on multiple options and carried out the following work in response to different conditions:

[0118] (1) Carry out the design research of the closed mechanical conveying system of hanging belt conveyor;

[0119] (2) Conducted design research on the pneumatic conveying system with fan + adjustable conveyor;

[0120] (3) Comparative analysis of the technical, economic, and environmental performance of mechanical conveying systems and pneumatic conveying systems.

[0121] 5. Recommendation of new treatment technology for final sludge co-incineration:

[0122] Combining the research contents of all the above treatment links, we have formed the content of "a circulating fluidized bed boiler mixed combustion sludge pre-treatment system". Through the above research, we have mastered the core technology of the system, obtained key technical parameters, and overcome the technical difficulties of pneumatic conveying of sticky materials that have long plagued the industry, filling the technical gap in this field. After horizontal multi-scheme technical, economic and environmental comparison, the conclusion is that this system is industry-leading in terms of investment, energy consumption and environmental protection, and has broad prospects for promotion and application. Figure 4-6 Pneumatic conveying system solution with fan + adjustable conveyor.

[0123] Compared with the traditional system, the overall technical and economic effects of this solution are as follows:

[0124] (1) Economical

[0125]

[0126] Compared with the traditional system, this patented solution can save initial investment of approximately RMB 5.59 million and reduce energy consumption by approximately 3,732kw.

[0127] (2) Technical

[0128] A new closed-type treatment technology for sticky materials using heatless drying + pneumatic conveying has been adopted, which not only greatly saves system investment, but also greatly saves operating energy consumption, greatly enhancing the comprehensive economy and environmental protection of the co-firing of sticky materials in circulating fluidized bed boiler power plants, paving the way for the large-scale promotion and application of sludge treatment and disposal in circulating fluidized bed boiler power plants, laying a good foundation for a win-win situation for power plants and sewage treatment plants, and improving the environmental protection and social nature of sludge treatment and disposal.

Claims

1. A circulating fluidized bed boiler pre-treatment system for sludge co-firing, characterized in that: It includes a sludge pre-treatment system, a sludge receiving and unloading platform, a pneumatic conveying system, a deodorization system, and a sludge filtrate recovery system; the sludge filtrate recovery system is connected to the sludge pre-treatment system, and the sludge treated by the sludge pre-treatment system is transported to the sludge receiving and unloading platform, the sludge receiving and unloading platform is connected to the pneumatic conveying system, and the deodorization system is connected to the sludge pre-treatment system, the sludge receiving and unloading platform, and the pneumatic conveying system; The pneumatic conveying system comprises a sludge receiving hopper (1) coordinated with the sludge receiving and unloading platform, a viscous material storage device, an admixture storage device, a crushing and blending device, and a pneumatic conveying device; the sludge receiving hopper (1) is connected to the feed port of the viscous material storage device, the discharge port of the viscous material storage device and the discharge port of the admixture storage device are both connected to the feed port of the crushing and blending device, and the discharge port of the crushing and blending device is connected to the pneumatic conveying device.

2. A circulating fluidized bed boiler pre-treatment system for sludge co-firing according to claim 1, characterized in that: The sludge pre-treatment system is a membrane plate and frame filter press system, and the sludge filtrate recovery system is connected to the liquid outlet of the membrane plate and frame filter press system; The diaphragm plate-frame filter press system comprises a modulation chamber (15), a diaphragm pump (16), a filter press (17), a pressurized water pump (19), a clean water tank (18), a scraper (22) and an air storage tank (23); The mixing chamber (15) is connected to the feed port of the filter press (17) through the diaphragm pump (16), the clean water tank (18) is connected to the water inlet of the filter press (17) through the pressurized water pump (19), the sludge outlet of the filter press (17) is arranged above the scraper (22), and the air storage tank (23) is connected to the air inlet of the filter press (17) through a pipeline; The liquid outlet of the filter press (17) is connected to the sludge filtrate recovery system, and the sludge filtrate recovery system includes a filtrate box (20). The filtrate box (20) is divided into two pipelines through a filtrate pump (21), one pipeline is connected to a tank truck, and the other pipeline is connected to the mixing tank (15).

3. A circulating fluidized bed boiler pre-treatment system for sludge co-firing according to claim 1, characterized in that: The sludge receiving and unloading platform adopts an openable and closable closed unloading platform.

4. A circulating fluidized bed boiler pre-treatment system for mixing sludge with combustion according to claim 1, characterized in that: The sludge receiving hopper (1) is connected to a bucket elevator (2), and the discharge port of the bucket elevator (2) is connected to the viscous material storage device; the viscous material storage device is a sludge heatless drying treatment workshop or a sludge silo (5).

5. A circulating fluidized bed boiler pre-treatment system for sludge co-firing according to claim 4, characterized in that: The bottom of the sludge silo (5) is provided with two sludge discharge ports, and each of the sludge discharge ports is provided with a corresponding variable frequency discharge screw (4); The blending material storage device comprises two sludge crushers (3), and the feed port of each sludge crusher (3) is connected to the discharge port of the corresponding variable frequency unloading screw (4); The pneumatic conveying device comprises two pneumatic conveyors (6), and the feed port of each pneumatic conveyor (6) is connected to the discharge port of the corresponding sludge crusher (3).

6. A circulating fluidized bed boiler pre-treatment system for sludge co-firing according to claim 5, characterized in that: A discharge port is provided at the bottom of each pneumatic conveyor (6), and a conveying fan (10) is connected to the side wall of each pneumatic conveyor (6) through a pipeline.

7. A circulating fluidized bed boiler pre-treatment system for mixing sludge with combustion according to claim 5, characterized in that: The admixture storage device comprises a limestone powder bin (7) and a hot air system connected to the side wall of the limestone powder bin (7), wherein the hot air system comprises a hot air duct connected to the side wall of the limestone powder bin (7), a gasification blower (8) and an electric heater (9) both of which are arranged on the hot air duct.

8. A circulating fluidized bed boiler pre-treatment system for sludge co-firing according to claim 7, characterized in that: The discharge port at the bottom of each limestone powder bin (7) is divided into two pipes, each of which is connected to the corresponding feed port of the sludge crusher (3). Each of the pipes is provided with a variable frequency feeder (7a), which is interlocked with the variable frequency discharge screw for adjustment and control to achieve control of the mixing ratio.

9. A circulating fluidized bed boiler pre-treatment system for sludge co-firing according to claim 7, characterized in that: The deodorization system includes a deodorization air collecting hood, a branch air collecting pipe connected to each of the deodorization air collecting hoods, a main air collecting pipe connected to each of the branch air collecting pipes, and a negative pressure deodorization fan arranged on the main air collecting pipe. The main air collecting pipe is connected to the air inlet of the conveying fan (10). There are multiple deodorization air collecting hoods, which are respectively located in the sludge receiving and unloading platform, the sludge crusher (3), the viscous material storage device and the sludge pre-treatment system.

10. A circulating fluidized bed boiler pre-treatment system for mixing sludge with combustion according to claim 9, characterized in that: The deodorization system further comprises a telescopic odor-proof cover (11) located inside the sludge receiving and unloading platform, a walking device (12) is provided below the telescopic odor-proof cover (11), and two tracks (13) cooperating with the walking device (12) are respectively provided on both sides of the inner bottom of the sludge receiving and unloading platform.

Images