Viscous material pneumatic conveying system and control method

Abstract

The invention discloses a pneumatic conveying system for viscous materials and a control method, and relates to the technical field of environmental protection treatment.The pneumatic conveying system comprises a sludge receiving hopper, a viscous material storage device, a mixed material storage device, a crushing and mixing device and a pneumatic conveying device; the sludge receiving and discharging platform is communicated with a feeding port of the viscous material storage device, a discharging port of the viscous material storage device and a discharging port of the mixed material storage device are both communicated with a feeding port of the crushing and mixing device, and a discharging port of the crushing and mixing device is communicated with the pneumatic conveying device. The pneumatic conveying test of the mixed material shows that after the mixed material enters the viscous material, the viscosity of the mixed viscous material is greatly reduced, and the influence of material crushing and pneumatic conveying is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection treatment, and more specifically to the technical field of a pneumatic conveying system and control method for viscous materials. Background Art

[0002] As is well known, semi-dry sludge refers to the sludge discharged from urban sewage treatment plants after treating domestic sewage, with a moisture content of 35% - 60% and strong viscosity. It is quite difficult to design in the storage, transportation and other links in the application field of co-firing sludge in power plants. Currently, the commonly adopted method in the industry is to control the moisture content of the sludge at about 15% through a thermal drying process, and then convey it to the furnace for co-firing together with raw coal through a coal conveying line. This system has disadvantages such as high investment in drying equipment, small output, large floor area, high energy consumption, and poor environmental protection of the conveying system, and urgently needs to be improved and optimized.

[0003] However, sludge with a moisture content of 35% - 60% belongs to viscous materials. Viscous materials have the characteristic of anti-fluidity. Once the material particles come into contact with each other or with external objects, they are easily bonded into lumps and block the flow channel, which brings great harm to industrial designs and operations such as material storage, transfer, and transportation.

[0004] Combined with the characteristics of a circulating fluidized bed boiler, it is proposed whether an environmentally friendly and sealed conveying technology can be adopted to directly convey semi-dry sludge to the furnace for co-firing, bypassing the above intermediate links. In this way, the economy and environmental protection of the system will be greatly improved. Further analysis shows that the pneumatic conveying system has characteristics such as good airtightness, flexible layout, and strong adjustability. The pneumatic conveying system is an ideal conveying option.

[0005] Due to the characteristics of viscous materials such as easy aggregation into lumps and anti-fluidity, and there is no mature research experience in the pneumatic conveying of viscous materials at home and abroad, there is no data available for the relevant mechanisms (laws) of the pneumatic conveying of viscous materials. For example, regarding the relevant material properties, conveying conditions, flow regime control in the pipeline, and their correlations, it is necessary to understand and master the basic principles and requirements of pneumatic conveying. More importantly, the characteristics of viscous materials and the flow regime control technology in the pipeline are all unknown research fields for us. The current technical problems in the pneumatic conveying of viscous materials are as follows:

[0006] Viscous materials are easily bonded into lumps when in contact and easily block the flow channel. How to reduce the moisture content (viscosity) of viscous materials and break the conditions for the formation of "aggregation and clumping" of viscous materials. Summary of the Invention

[0007] The purpose of the present invention is: to solve the above technical problems, the present invention provides a pneumatic conveying system and control method for viscous materials.

[0008] The present invention specifically adopts the following technical solutions to achieve the above purpose:

[0009] The present invention provides a pneumatic conveying system for viscous materials, which includes a sludge receiving hopper, a viscous material storage device, a blending material storage device, a crushing and blending device, and a pneumatic conveying device;

[0010] The sludge receiving and discharging platform is communicated with the feed inlet of the viscous material storage device. The discharge outlets of both the viscous material storage device and the blending material storage device are communicated with the feed inlet of the crushing and blending device, and the discharge outlet of the crushing and blending device is communicated with the pneumatic conveying device.

[0011] Specifically, pneumatic conveying has the advantages of low use cost and high conveying efficiency. In addition, the out-of-furnace blending of viscous materials can, to a certain extent, increase the residence time of the blending materials in the furnace for reacting with SO2, save the total limestone powder resources in the power plant to a certain extent, improve the resource utilization rate, and reduce resource consumption; the pneumatic conveying part can also greatly reduce the wear of equipment pipelines, extend the service life of facilities, and reduce the operation and maintenance costs.

[0012] This solution discloses the pneumatic conveying technology for viscous materials + blending materials, in which the conveying equipment adopts a fan + continuously adjustable pneumatic conveying device + pipeline system, and the conveying parameters (optimal material-air ratio, air flow rate, pressure, etc.) are configured according to the optimal parameters determined by experiments.

[0013] The proposed pneumatic conveying technology for viscous materials is advanced in overall technical indicators, good in environmental protection, fast in adjustment and reaction, and reasonable in economic (low investment and energy consumption indicators) indicators, filling the research gap in the field of pneumatic conveying of viscous materials.

[0014] The idea of adding an "isolation layer" between viscous particles is proposed, and then another "blending material" is introduced as the "isolation layer" and mixed into the sludge to break the conditions for the formation of "agglomeration and clumping" of viscous materials. The pneumatic conveying experiment of the blending materials in the present invention shows that after the "blending materials" enter the viscous materials, the moisture content of the materials drops by about 10%, the viscosity drops significantly, and the influence on the material crushing and pneumatic conveying is greatly reduced.

[0015] In an embodiment, the sludge receiving hopper is communicated with a bucket elevator, and the discharge outlet of the bucket elevator is communicated with the viscous material storage device.

[0016] Specifically, the setting of the bucket elevator can be applicable to viscous material storage devices (sludge non-thermal drying workshop or sludge silo) at different heights.

[0017] In an embodiment, the viscous material storage device is a sludge non-thermal drying workshop or a sludge silo.

[0018] Specifically, for the "blended material", it is proposed that limestone powder, coal powder, fly ash, bottom slag, bed material, biomass material, etc. can be selected. Considering the operation requirements of the circulating fluidized bed boiler, limestone powder is preferably selected as the test "blended material", mainly considering the characteristics of limestone powder and making full use of the existing in-furnace conveying system in the power plant. After the two materials are blended and conveyed, it can not only solve the problem of blockage in the conveying of sticky materials, but also improve the wear problem in the separate conveying of limestone powder. After limestone powder and sludge are fed into the furnace, it does not affect the combustion conditions in the furnace, but will improve the desulfurization efficiency to a certain extent.

[0019] In one embodiment, there are two sludge discharge ports at the bottom of the sludge storage bin, and corresponding variable-frequency discharging screws are arranged at each sludge discharge port.

[0020] The blended material storage device includes two sludge crushers, and the feed ports of each sludge crusher are communicated with the discharge ports of the corresponding variable-frequency discharging screws.

[0021] The pneumatic conveying device includes two pneumatic conveyors, and the feed ports of each pneumatic conveyor are communicated with the discharge ports of the corresponding sludge crushers.

[0022] In one embodiment, there are discharge ports at the bottom of each pneumatic conveyor, and a conveying fan is connected to the side wall of each pneumatic conveyor through a pipeline.

[0023] In one embodiment, the blended material storage device includes a hot air system communicated with the side wall of the limestone powder silo. The hot air system includes a hot air pipeline communicated with the side wall of the limestone powder silo, an air-vaporizing fan and an electric heater arranged on the hot air pipeline.

[0024] Specifically, the air-vaporizing fan is located behind the electric heater along the air flow direction.

[0025] In one embodiment, a variable-frequency feeder is arranged on the discharge main pipe at the bottom of each limestone powder silo. Through a three-way or switching valve, it is divided into two pipelines, and each pipeline is communicated with the feed port of the corresponding sludge crusher. The variable-frequency feeder is interlocked and regulated with the variable-frequency discharging screw to control the blending ratio.

[0026] In one embodiment, the sludge receiving and discharging platform is an enclosed discharging platform.

[0027] Specifically, for the sticky material receiving and discharging platform, a recommended openable and closable enclosed discharging platform is adopted, and its opening and closing are interlocked and controlled with the deodorization system.

[0028] Another aspect of the present invention provides a control method for a pneumatic conveying system of sticky materials. Using the above-mentioned pneumatic conveying system of sticky materials, it includes the following steps:

[0029] S1. The sludge enters the viscous material storage device through the sludge receiving hopper and the bucket elevator; limestone powder is added to the limestone powder silo as an isolation layer for the sludge.

[0030] S2. After controlling the mixing ratio of the sludge and limestone powder according to the blending ratio test and the property test of the mixture, the particle size of the crushed limestone powder is smaller than that of the crushed sludge particles, and the blending parameters of the mixture in the crushing and blending device are accurately controlled.

[0031] S3. Enter the crushing and blending device to mix and crush to obtain a mixture, and control the particle size of the mixture.

[0032] S4. According to the experimental study on the pneumatic conveying of the mixture, the pneumatic conveying parameters are determined by using the property method test + amplification / simulation technology method, and are conveyed through the pneumatic conveying device.

[0033] S5. The conveying effect is verified by simulation, the optimal parameters of the system under different conditions are obtained, and the parameters of the pneumatic conveying device are controlled.

[0034] In an embodiment, the moisture content of the limestone powder < 2.5%, it is a powdery material before crushing, the maximum particle size < 1 mm; the maximum particle size of the mixture is 5 mm.

[0035] The beneficial effects of the present invention are as follows:

[0036] 1. According to the above analysis of the pipeline blockage reasons, using the method of simply reducing the surface moisture cannot completely solve the problem of material viscosity. Aiming at the sticking and blocking mechanism of semi-dry sludge, the idea of adding an "isolation layer" between viscous particles is proposed, and then another "blending material" is introduced as an "isolation layer" to be mixed into the sludge, breaking the conditions for the formation of "agglomeration and clumping" of viscous materials. The pneumatic conveying test of the blending material in the present invention shows that after the "blending material" enters the viscous material, the calculation formula of the material moisture content is as follows:

[0037] Moisture content of the blended material = Moisture content of the original viscous material × (1 - blending ratio) + Moisture content of the blending material × blending ratio;

[0038] The viscosity of the blended viscous material drops significantly, and the influence on material crushing and pneumatic conveying is greatly reduced.

[0039] 2. The pneumatic conveying technology of viscous materials proposed in the present invention is advanced in overall technical indicators, good in environmental protection, fast in adjustment reaction, and reasonable in economic (low investment and energy consumption indicators) indicators, filling the research gap in the field of pneumatic conveying of viscous materials.

[0040] 3. When cooperating with the related system for sludge co-firing, it has obvious advantages over the conventional treatment system in terms of technology, economy, and environmental protection.

[0041] 4. Overcame the long-standing technical problem of pneumatic conveying of viscous materials in the industry, filling the technical gap in this field. After horizontal technical, economic, and environmental comparisons of multiple solutions, this system is leading in the industry in terms of investment, energy consumption, and environmental protection, and has broad prospects for popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0043] Figure 1 is the structural schematic diagram of the present invention;

[0044] Figure 2 is the control flow chart of the present invention;

[0045] Reference numerals: 1 - sludge receiving hopper, 2 - bucket elevator, 3 - sludge crusher, 4 - variable-frequency discharging screw, 5 - sludge silo, 6 - pneumatic conveyor, 7 - limestone powder silo, 8 - gasification blower, 9 - electric heater, 10 - conveying blower, 11 - variable-frequency feeder. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] To make the technical problems, technical solutions, and technical effects of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0048] It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0049] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "inside", "outside", "upper", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0050] Example 1

[0051] As Figure 1 shown, this embodiment provides a pneumatic conveying system for viscous materials, which includes a sludge receiving hopper 1, a viscous material storage device, a blending material storage device, a crushing and blending device, and a pneumatic conveying device;

[0052] The sludge receiving hopper 1 is communicated with the feed inlet of the viscous material storage device, and the discharge outlets of both the viscous material storage device and the blending material storage device are communicated with the feed inlet of the crushing and blending device, and the discharge outlet of the crushing and blending device is communicated with the pneumatic conveying device.

[0053] Specifically, pneumatic conveying has the advantages of low use cost and high conveying efficiency. In addition, the out-of-furnace blending of viscous materials can, to a certain extent, increase the residence time of the blending material in the furnace during the reaction with SO2, can, to a certain extent, save the total limestone powder resources of the power plant, improve the resource utilization rate, and reduce resource consumption; the pneumatic conveying part can also greatly reduce the wear of equipment pipelines, improve the operation life of facilities, and reduce the operation and maintenance costs.

[0054] The air for pneumatic conveying of the pneumatic conveying device is the odor sucked by negative pressure. After the conversion of negative pressure and positive pressure is realized by a Roots blower, it is mixed with the sludge mixture in the mixing chamber at the outlet of the adjustable conveyor, and the sludge mixture is directly sent to the furnace through the conveying pipeline. A sealing air is provided at the interface between the powder conveying pipeline and the furnace.

[0055] This solution discloses the pneumatic conveying technology of viscous materials + blending materials, in which the conveying equipment adopts a blower + a continuously adjustable pneumatic conveying device + a pipeline system, and the conveying parameters (optimal material-air ratio, air flow rate, pressure, etc.) are determined according to experiments to obtain the optimal parameter configuration.

[0056] The proposed pneumatic conveying technology for viscous materials is advanced in overall technical indicators, good in environmental protection, fast in adjustment reaction, and reasonable in economic (low investment and energy consumption indicators) indicators, filling the research gap in the field of pneumatic conveying of viscous materials.

[0057] The sludge receiving hopper 1 is communicated with the bucket elevator 2, and the discharge outlet of the bucket elevator 2 is communicated with the viscous material storage device.

[0058] Specifically, the setting of the bucket elevator 2 can be applicable to the viscous material storage devices (sludge non-thermal drying workshop or sludge bin 5) at different heights.

[0059] The viscous material storage device is a sludge non-thermal drying workshop or a sludge bin 5.

[0060] Two sludge discharge ports are arranged at the bottom of the sludge bin 5, and corresponding variable-frequency discharging screws 4 are arranged at each sludge discharge port;

[0061] The blending material storage device includes two sludge crushers 3, and the feed ports of the sludge crushers 3 communicate with the discharge ports of the corresponding variable-frequency discharging screws 4;

[0062] The pneumatic conveying device includes two pneumatic conveyors 6, and the feed ports of the pneumatic conveyors 6 communicate with the discharge ports of the corresponding sludge crushers 3.

[0063] Each pneumatic conveyor 6 is provided with a discharge port at the bottom, and a conveying fan 10 is connected to the side wall of each pneumatic conveyor 6 through a pipeline.

[0064] The blending material storage device includes a hot air system communicated with the side wall of the limestone powder bin 7. The hot air system includes a hot air pipeline communicated with the side wall of the limestone powder bin 7, a gasification blower 8 and an electric heater 9 arranged on the hot air pipeline.

[0065] Specifically, the gasification blower 8 is located behind the electric heater 9 along the air flow direction.

[0066] A variable-frequency feeder 11 is arranged on the discharge main pipe at the bottom of each limestone powder bin 7. Through a three-way or switching valve, it is divided into two pipelines again. Each pipeline communicates with the feed port of the corresponding sludge crusher 3. The variable-frequency feeder 11 is interlocked and regulated with the variable-frequency discharging screw to realize the control of the blending ratio.

[0067] The sludge receiving and discharging platform is a closed discharging platform. Specifically, for the viscous material receiving and discharging platform, a recommended openable and closable closed discharging platform is adopted, and its opening and closing are interlocked with the deodorization system.

[0068] Embodiment 2

[0069] As Figure 2 shown, this embodiment provides a control method for a pneumatic conveying system of viscous materials. Using the above-mentioned pneumatic conveying system of viscous materials, it includes the following steps:

[0070] S1. The sludge enters the viscous material storage device through the sludge receiving hopper and the bucket elevator; limestone powder is added into the limestone powder bin as an isolation layer for the sludge;

[0071] S2. According to the blending ratio test and the mixed material property test, after the blending ratio of the sludge and the limestone powder is controlled, the particle size of the crushed limestone powder is smaller than the crushed sludge particles, and the blending material parameters of the mixed material in the crushing and blending device are controlled;

[0072] S3, entering the crushing and blending device to mix and crush to obtain a mixture, and controlling the particle size of the mixture;

[0073] S4. According to the experimental research on pneumatic conveying of mixed materials, the pneumatic conveying parameters are determined by material property test + amplification / simulation technology, and the mixture is transported by pneumatic conveying device;

[0074] S5. Verify the conveying effect through simulation, obtain the optimal parameters of the system under different conditions, and control the parameters of the pneumatic conveying device.

[0075] Specifically, the sludge is semi-dry sludge with a moisture content of 35-60%. It is a block material before crushing and does not require special treatment.

[0076] The selection principle of admixture as the "isolation layer" of sludge is as follows: the particle size is smaller than that of the crushed sludge particles, the hardness and bulk density are relatively large, and the adsorption (moisture) property is good; during pneumatic conveying, the "admixture" not only has the function of isolating the "stickiness" of the sludge, but also has a certain "abrasiveness", which can "offset" the influence of the sludge particles "adhering" to the pipeline to a certain extent; it is easy to obtain, economical, and cannot have a negative impact on the boiler combustion. Considering the circulating fluidized bed boiler unit, limestone powder needs to be added during the operation of the boiler. Limestone powder as an "admixture" just meets the requirements of the above conditions. Therefore, limestone powder is selected as the "isolation layer" of sludge particles (for limestone powder, the residence time in the furnace is prolonged after being added to the sludge, which will improve the desulfurization efficiency to a certain extent). The limestone powder of the admixture has a moisture content of <2.5%, and is a powdery material before crushing, with a maximum particle size of <1mm.

[0077] The crusher adopts a thin-piece or axe-type special crusher.

[0078] The mixing ratio of the crushed mixture is determined mainly by controlling the viscosity of the mixture, that is, the looseness. It needs to reach the "dry and loose" level - it cannot be agglomerated by hand (the moisture content is about 10% lower than the original sludge), and the material is granular, with a median diameter of 1-1.4mm and a maximum particle size of <5mm. The control measure is achieved by controlling the amount of limestone powder added, specifically by controlling the speed of the electric feeder on the adding line.

[0079] The pneumatic conveying system is composed of a fan + (adjustable) silo pump + pipeline system. The main design parameters are determined by material property test + amplification / simulation technology to obtain the optimal parameters of the system under different conditions. The test results are the characteristics of crushed sludge and limestone powder samples.

[0080] Within the conveying distance of 0 - 300 m and the conveying capacity of 0 - 21.5 t / h, the optimal design parameters are a material - to - gas ratio of 13, an air consumption of 20 - 35 m³ / min, a conveying pipe diameter of DN125 / 150, a flow velocity of 15 - 23 m / s, a pipeline pressure drop of 70 Kpa, and the flow regime inside the pipeline is a "medium - phase" conveying state.

[0081] In one embodiment, the moisture content of the limestone powder is < 2.5%, it is a powdery material before crushing, and the maximum particle size is < 1 mm;

[0082] The maximum particle size of the mixture is 5 mm.

[0083] The following is to analyze and solve problems through pneumatic conveying tests:

[0084] 1. The process of sludge material property testing is as follows:

[0085] (1). Crushing test of the original sludge to test the sludge material properties:

[0086] 1). Particle size distribution: It was initially assumed that the maximum particle size of sludge particles was controlled within 3 mm, and the smaller the better. The crushing test found that the crushing particle size was inversely proportional to the viscosity. The smaller the particle size, the greater the surface viscosity, and it was more likely to aggregate into lumps after crushing. After the test, the optimal particle size and distribution of the crushed sludge particles (maximum particle size of 5 mm) were found.

[0087] Through the above - mentioned experimental research, it was found that the viscosity of the material had a great influence on the crushing, air - drying, and conveying systems. The crushing particle size was inversely proportional to the material viscosity. Air - drying had little effect on the material viscosity. Whether it was the original or air - dried sludge, pneumatic conveying blockage occurred frequently, the system output was small, the air consumption was large, the system operation was unstable, and pneumatic conveying of viscous materials was not successful.

[0088] 2). Moisture content, bulk density, angle of repose:

[0089] After the test, relevant data such as the moisture content (including surface moisture content), bulk density, and angle of repose of the sludge were obtained.

[0090] 3). Viscosity:

[0091] Analyze the mechanism of sticky blockage in pneumatic conveying of viscous materials: When viscous materials are in the process of being conveyed in the bin pump and pipeline, they are subjected to wear, extrusion, etc., which makes the internal moisture easy to "come out", the overall "viscosity" increases, and it is easy to adhere to the inner walls of equipment, pipelines, and elbows, causing blockage phenomena;

[0092] Since semi - dry sludge has strong solid characteristics and cannot be measured with an ordinary (liquid - measuring) viscometer, we use two methods for comprehensive measurement. One is the degree of looseness, and the agglomeration of the sludge is tested by manual inspection; the other is the surface moisture content, which is closely related to viscosity.

[0093] (2) To reduce the viscosity of sludge and create good conditions for pneumatic conveying, the following two methods were used to reduce the surface moisture content of sludge:

[0094] 1) Air drying test: The sludge was air dried, but the results were not satisfactory. It required a lot of wind and a long time, and the economic efficiency was very poor, so this method was abandoned.

[0095] 2) Drying test: The sludge was evenly spread out and exposed to the sun for 1 hour, and the characteristics of the dried sludge were tested. Its moisture content can be reduced by 10%, and the effect is not obvious after that.

[0096] (3) Pneumatic conveying test of original / air-dried sludge:

[0097] 1) Pneumatic conveying test of original sludge, the specific method is as follows:

[0098] The test shows that the original sludge is not suitable for pneumatic conveying, pipeline blockage occurs frequently, the system output is small, the gas consumption is large, the system operation is unstable, and the pneumatic conveying is unsuccessful.

[0099] 2) Pneumatic conveying test of air-dried sludge, the specific method is as follows:

[0100] The test showed that although the surface moisture content of the air-dried sludge was reduced, similar problems still existed in the pneumatic conveying of the original sludge, and the pneumatic conveying was unsuccessful. After analysis, it was found that the reason for the pipeline blockage of the air-dried sludge was that the viscous material was subjected to wear and extrusion during the pipeline transportation process, causing the internal moisture to "drill" out, and the overall "viscosity" was enhanced, thus causing blockage on the inner wall of the pipeline and elbow.

[0101] 3. This embodiment method proposes the following contents:

[0102] (1) The idea of ​​“isolation layer” is proposed:

[0103] According to the above analysis of the causes of pipeline blockage, the method of simply reducing the surface moisture cannot completely solve the problem of material stickiness. In view of the stickiness mechanism of semi-dry sludge, the idea of ​​adding an "isolation layer" between sticky particles is proposed, and then another "admixture" is introduced as an "isolation layer" to mix into the sludge to break the "agglomeration and agglomeration" conditions of sticky materials; the requirements for this "admixture" are as follows:

[0104] 1) The material is easily available in power plants and does not need to be purchased separately.

[0105] 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.

[0106] 3) The bulk density and hardness are relatively large. During pneumatic conveying, the "mixture" has a certain "abrasiveness", which can "offset" the effect of sludge particles "adhering" to the pipeline and blocking it to a certain extent.

[0107] (2) Determination of “blended materials”:

[0108] The "admixture" proposed can include limestone powder, coal powder, fly ash, bottom slag, bed material, biomass material, etc. Combined with the operating requirements of the circulating fluidized bed boiler, after research, limestone powder was finally selected as the test "admixture", mainly considering the characteristics of limestone powder and making the best use of the power plant's existing furnace conveying system. The two materials are mixed and conveyed, which can not only solve the problem of blockage in the transportation of sticky materials, but also improve the wear problem of limestone powder conveying alone.

[0109] After the "admixture" enters the sticky material, the moisture content of the material decreases, and more importantly, the viscosity decreases significantly, and the impact of material crushing and pneumatic conveying is greatly reduced. The main research results are: when the sludge conveying distance is in the range of 100-300m, the output of a single system is ≤7.2t / h, and when the limestone powder blending ratio is 30%, the material agglomeration and blockage problem "disappears", the pneumatic conveying system runs smoothly, the material-gas ratio is 13.08, and the pipeline sticking and blocking problem is solved.

[0110] 4. Test of sludge mixed with limestone powder:

[0111] (1) The blending test is as follows:

[0112] In conjunction with the pneumatic conveying test of the admixture, tests on different mixing ratios of limestone powder were carried out, and the material properties of limestone powder and mixed materials were tested separately to determine the optimal mixing ratio and study the relationship between the mixing ratio and system output.

[0113] (2) Pneumatic conveying test of admixtures:

[0114] Pneumatic conveying tests of mixtures with different blending ratios are carried out. According to the characteristics of the mixed materials, including adding looseness factors, the flow state of the materials in the pipeline is determined, and the dilute phase-medium phase flow mode is selected. The conveying effect of the conveying system under different conditions is tested, and the main technical parameters, such as conveying speed, pressure loss, material-to-gas ratio, and conveying effect (whether there is sticking or not), are tested.

[0115] (3) Determine the technical parameters of the engineering system:

[0116] Due to numerous variable factors in the above tests, such as the characteristics of the two materials, the blending ratio, system output, conveying distance, material-gas ratio, etc., based on a large number of tests and the best (stable operation, low energy consumption) test results, the best test parameters (blending ratio, material-gas ratio, etc.) were determined. Then, using "scaling-up technology" and simulation work, the best system design parameters for engineering design under different conveying conditions and different outputs were finally determined, and the method for mastering the key indicators of the design and control of the pneumatic conveying system for viscous materials was obtained.

[0117] The technical and economic effects obtained as a whole in Example 2 compared with the traditional system are as follows:

[0118] (1) Economy

[0119]

[0120] Compared with the traditional system, the two solutions of this patent can save about 27.8 / 8.59 million yuan in initial investment and reduce energy consumption by about 3967 / 3732 kw. From the above comparison, it can be seen that the new technology solution has obvious advantages in both investment and operating energy consumption, especially the recommended solution (the pressure filtration system is set outside the factory), with huge advantages.

[0121] (2) Technology

[0122] A new closed treatment technology for viscous materials using heatless drying + pneumatic conveying is adopted, which not only greatly saves system investment but also significantly reduces operating energy consumption, greatly enhancing the comprehensive economy and environmental protection of co-firing viscous materials in a circulating fluidized bed boiler power plant. It lays a good foundation for the large-scale popularization and application of sludge treatment and disposal in a circulating fluidized bed boiler power plant, achieving a win-win situation for power plants and sewage treatment plants, and improving the environmental protection and sociality of sludge treatment and disposal.

[0123] In addition, the description of the system interlock requirements:

[0124] (1) Before the system runs, the conditions of each device and valve configured in the system should be checked first to see if they are normal, flexible, and in a closed state.

[0125] (2) Start the furnace inlet seal air system.

[0126] (3) No-load commissioning process:

[0127] According to the actual operation process, conduct no-load commissioning. Start the fan to suck the odor and the silo pump conveying pipeline to the furnace system - unloading platform - bucket elevator - sludge silo / limestone powder silo - unloading screw / (limestone powder silo bag filter - gasification system - electric feeder) - crusher - silo pump. The closing process is the reverse of the above process.

[0128] Note: The sludge discharge screw, limestone powder electric feeder, and silo pump are all regulating devices. During programming, they are required to be interlocked and automatically adjusted to ensure that when the operating conditions of the system change, the operating parameters of the system are always controllable and optimized.

[0129] (4) Load commissioning operation process:

[0130] The same as the no-load commissioning process, the following points should also be noted for interlocking control:

[0131] 1) The pressure of the main air delivery pipe is interlocked with the pneumatic conveying device. After confirming that the pressure of the main air pipe is not less than the minimum set value, the conveying unit group can operate.

[0132] 2) The pressure transmitter on the sludge conveying main pipe is interlocked with the blockage removal valve. When it is monitored that the pressure of the conveying main pipe is higher than the set value, the blockage removal valve is opened for blockage removal, and when the main pipe pressure returns to the normal value, the blockage removal valve is closed.

[0133] 3) When the conveying pipeline is blocked and still blocked after starting the automatic blockage removal program, or when the conveyor fails, the operating line is closed (for maintenance), and at the same time, the standby conveying equipment and pipelines are enabled.

[0134] 4) The operating logic of the conveying system is interlocked with the material levels of the sludge silo 5 and the variable-frequency discharge screw 4. When it is monitored that the high-level alarm of the sludge silo 5 occurs, the feeding process is stopped, and when the low-level is monitored, the sludge is discharged from the sludge silo 5.

[0135] 5) The variable-frequency discharge screw 4 of the sludge silo 5 is interlocked with the operating load of the furnace. It is required to adjust the rotation speed of the variable-frequency feeder 11 in a timely manner according to this feedback value, and adjust the sludge conveying volume to meet the requirements of the boiler (5% blending ratio).

[0136] 6) During actual operation, when the actual sludge consumption is lower than the system design output, the output of each conveying pipeline should be evenly adjusted.

[0137] 7) To achieve the above conditions, the operation and interlocking control of the variable-frequency discharge screw 4 of the sludge silo 5 and the variable-frequency feeder 11 of the limestone powder silo 7 also need to be considered to ensure the blending ratio.

Claims

1. A pneumatic conveying system for viscous materials, characterized in that, It includes a sludge receiving hopper (1), a viscous material storage device, a blended material storage device, a crushing and blending device, and a pneumatic conveying device; The sludge receiving hopper (1) is communicated with the feed inlet of the viscous material storage device, the discharge outlets of the viscous material storage device and the blended material storage device are both communicated with the feed inlet of the crushing and blending device, and the discharge outlet of the crushing and blending device is communicated with the pneumatic conveying device.

2. The pneumatic conveying system for viscous materials according to claim 1, characterized in that, A bucket elevator (2) is connected to the discharge outlet of the sludge receiving hopper (1), and the discharge outlet of the bucket elevator (2) is communicated with the viscous material storage device.

3. The pneumatic conveying system for viscous materials according to claim 2, wherein The viscous material storage device is a sludge heatless drying workshop or a sludge silo (5).

4. The pneumatic conveying system for viscous materials according to claim 3, wherein Two sludge discharge outlets are arranged at the bottom of the sludge silo (5), and corresponding variable-frequency discharging screws (4) are arranged at each sludge discharge outlet; The blended material storage device includes two sludge crushers (3), and the feed inlets of the sludge crushers (3) are communicated with the discharge outlets of the corresponding variable-frequency discharging screws (4); The pneumatic conveying device includes two pneumatic conveyors (6), and the feed inlets of the pneumatic conveyors (6) are communicated with the discharge outlets of the corresponding sludge crushers (3).

5. The pneumatic conveying system for viscous materials according to claim 4, characterized in that, Each pneumatic conveyor (6) is provided with a discharge outlet at the bottom, and a conveying fan (10) is connected to the side wall of each pneumatic conveyor (6) through a pipeline.

6. The pneumatic conveying system for viscous materials according to claim 4, wherein, The blended material storage device includes a limestone powder silo (7) and a hot air system communicated with the side wall of the limestone powder silo (7). The hot air system includes a hot air pipeline communicated with the side wall of the limestone powder silo (7), a gasification blower (8) and an electric heater (9) both arranged on the hot air pipeline.

7. A pneumatic conveying system for viscous materials according to claim 6, characterized in that, A variable-frequency feeder (11) is arranged on the discharge main pipe at the discharge outlet at the bottom of each limestone powder silo (7), and is divided into two pipelines through a three-way or a switching valve. Each pipeline is communicated with the feed inlet of the corresponding sludge crusher (3). The variable-frequency feeder (11) is interlocked and regulated with the variable-frequency discharging screw to control the blending ratio.

8. A pneumatic conveying system for viscous materials according to claim 5, wherein, The sludge receiving and discharging platform is a closed discharging platform.

9. A control method for a pneumatic conveying system of viscous materials, which uses a pneumatic conveying system of viscous materials according to any one of claims 1 to 8, characterized in that, It includes the following steps: S1. The sludge enters the viscous material storage device through the sludge receiving hopper (1) and the bucket elevator (2); limestone powder is added into the limestone powder silo (7) as an isolation layer for the sludge; S2. After controlling the blending ratio of the sludge and the limestone powder according to the blending ratio test and the property test of the mixture, the particle size of the crushed limestone powder is smaller than that of the crushed sludge particles, and the blending material parameters of the mixture in the crushing and blending device are controlled; S3. The mixture is mixed and crushed in the crushing and blending device to obtain a blended material, and the particle size of the blended material is controlled; S4. According to the experimental study on the pneumatic conveying of the blended material, the pneumatic conveying parameters are determined by using the material property method test + amplification / simulation technology method and are conveyed through the pneumatic conveying device; S5. The conveying effect is verified by simulation, the parameters of the system under different conditions are obtained, and the parameters of the pneumatic conveying device are controlled.

10. The control method of a pneumatic conveying system for viscous materials according to claim 9, characterized in that, The moisture content of the limestone powder < 2.5%, it is a powdery material before crushing, and the maximum particle size < 1 mm; the maximum particle size of the blended material is 5 mm.

Images