What is the air slide conveying?
Air slide conveying is a form of conveying that uses air or other gases to flow bulk materials in pipelines.
What materials can be conveyed by air slide conveying?
Typical bulk materials such as powders, granules, spheres, and irregularly shaped particles used in air slide conveying methods are less than 20 mm (0.75 in). Most air slide conveying materials have a bulk density of 0.1-1 t/m3.
Two types of air slide conveying
Dilute phase transport
Air slide conveying can be designed as a positive or negative pressure system. The most commonly used air slide conveying method is the dilute phase conveying of the mixture of material and gas. Depending on the size, shape, and weight of the material particles, the conveying speed will vary from 4 to 40 m/s (4000 to 8000 ft/min). Dilute phase delivery systems are reliable for a wide range of materials with different characteristics, such as high bulk density, strong cohesion, or extremely irregular particle shapes. Material may degrade or wear due to higher air velocities.
Dense Phase Conveying
Dense phase conveying is to use high-pressure gas to press the material, and the gas source pressure can be as high as 0.7MPa. The characteristics of dense phase conveying are low air volume and high solid-gas ratio, and the material moves in a fluidized state or plunger shape in the tube. Large conveying capacity and long conveying distance, up to 100-1000m.
What are the components of an air slide conveying system?
The air slide conveying system consists of an air source system, feeding system, pipeline system, dust removal system, silo system, and control system.
On many occasions, there are also drying systems, metering systems, packaging systems, etc. in the conveying system.
The transportation methods of the air slide conveying system are pressure feeding type (positive pressure system), suction feeding type (negative pressure system), and pressure suction mixing type.
Air source system
Pressure feed
In the pressure-feed conveying system, the air source system generally uses an air compressor or a Roots blower. Since the exhaust is used for conveying, the machine itself will not have special maintenance problems. The general machine can be repaired according to the instructions for manual maintenance.
Suction
In the suction conveying system, the air source system generally adopts a water circulation vacuum pump or a Roots vacuum pump. Since the suction is used for conveying, if the suction contains dust, it will accelerate the wear of the fan, affect the air volume of the fan, and then affect the stability of the system. The dust adheres to the inside of the fan, which will also reduce the performance of the fan and cause vibration, which will affect the life of the fan. Therefore, it is necessary to regularly clean the inside of the fan, and regularly check the damage to the filter bag of the front dust collector. Once found, replace it immediately to maintain a good operating condition.
Piping system
In the air slide conveying system, the pipeline system is relatively simple and the most important. The pipeline system is divided into straight pipe sections and curved pipe sections.
There is a section of air connection pipeline between the air source system and the material supply system, which plays a very important role in the transportation system.
When the materials in the feeding system have requirements on the air source, air source processing equipment can be added to this pipeline system, such as an air filter, air cooler, pressure transmitter, etc.
- The function of the air filter is to filter the air at the outlet of the Roots blower to achieve three-level filtration accuracy and improve the quality of the product;
- The air cooler is a device that is added when the material has a requirement on the temperature of the gas. It reduces the temperature of the Roots blower and protects the product from denaturation due to the influence of temperature;
- The pressure transmitter generally needs to be configured. Its function is to detect and output the conveying capacity of the entire system in real-time, including no-load pressure and load pressure and can start and stop feeding according to the pressure value, or frequency conversion feeding to protect the system. normal operation.
Maintenance points
The maintenance points of the pipeline system: the air duct provides the air connection pipeline between the systems for the air source in the pressure-feeding conveying, and is the connecting pipeline between the dust removal system and the air source system in the suction-feeding conveyance. Generally speaking, The maintenance of these two parts of the pipeline is not large, you must pay attention to the sealing condition of the joint, and check whether the body is rusted frequently. The damage to the wind cap will cause the entry of rainwater, which should be repaired in time.
In the pressure-feeding conveying system, the pipeline system also includes the intermediate gas storage tank, the steam-water separator, the gas supply system, and the corresponding piping, except that the steam-water separator belongs to the pressure vessel, and its use requirements should be checked regularly according to the requirements of the pressure vessel. Safety, at the same time, special attention should be paid to whether the set pressure of the safety valve is accurate. The moisture in the gas storage tank and the steam-water separator should be discharged in time. The above air slide components are always in the best condition.
Feeding system
In the air slide conveying system, there are many kinds of feeding systems, but they all have to follow one point, which needs to be sealed and sealed. Common feeding systems include rotary feeders, screw conveyors, and silo pump systems.
Rotary Feeder
The feeding system of the rotary feeder needs to use equipment with good air tightness. The professional manufacturer of the feeder should design different structures and seals according to different working conditions. The feeding system is specially used for the positive pressure conveying of the pneumatic conveying system. It can solve a series of problems such as anti-seizing of granular materials, sticking of adhering materials, extrusion, and plasticization of plastic materials, thermal expansion of high-temperature materials, wear-resistant equipment of wear materials, and surface exposure of temperature-difference materials.
The rotary feeder feeding system generally uses the Roots blower as the air source system to form a high-pressure dense-phase conveying state, which has the characteristics of low flow rate, low wear, and low air consumption. For continuous conveying, the silo pump feeding system needs to achieve a specific conveying form, which has certain requirements for the characteristics of the material. It must be powder and must have good fluidity. Different media need to adjust different air volumes and pressures.
Silo pump feeding system
The configuration of the silo pump feeding system is more complicated, including the feeding valve, the discharging valve, the exhaust valve, the pressure gauge, the material level gauge inlet valve group, the pressure regulating valve group, and the control system, etc. It is a highly automated and integrated supply system. material system.
According to different materials and working conditions, the silo pump feeding system can have bottom-drawing and upward-drawing silo pumps for selection.
The tank body of the silo pump is a pressure vessel, and the safety inspection of the tank body needs to be carried out regularly to ensure normal use.
Dust removal system
The dust removal system is very important in the pneumatic conveying system, which is related to the environmental assessment of the project. The dust removal system standard is exhausted 50mg/m3, and the standard configuration of Hengtong’s dust removal system is 20mg/m3, and pulse dust removal is generally configured in the dust removal system. If the installation height is limited or on special occasions, the cyclone separator is also used as the primary dust removal. The dust removal efficiency of the cyclone separator is between 80% and 95%, so the pulse dust collector needs to be added later as the precision dust removal.
The design of the dust collector system is also very important, which is related to the stability of the entire system. According to the different material properties and specific gravity of the materials, it is necessary to select dust collectors with different filter areas, otherwise, the design will not match and the system pressure will be unstable. , so choose a professional manufacturer, which can match various forms of pulse dust collectors for users according to different working conditions.
Silo system
The silo system plays the role of temporarily storing materials during the conveying process of bulk materials. Most of the silos are conical or pyramidal structures, which have both storage and discharge functions. The production of the silo system must be based on different materials. The problems that will exist in the process of storage and unloading and the flow of each material, the dynamic load and static load when the material is full, the gasification and vibration when the material is discharged, etc. should be considered in the design of the silo system. factor. The most common problems of the silo system are arching and bridging. Different silo cone discharge structures can be designed according to different material characteristics, such as biased material opening, curved hopper, inner wall coating, gasification flow aid, etc. The configuration of the silo system usually includes a vacuum release valve, a material level gauge, a metering device, an automatic discharge device, etc.
Control System
Control system: The automation of the electrical system is an important symbol of industrial modernization and the core technology of modern science. It is a technology that enables the control, monitoring and operation of products to be carried out automatically according to the specified degree or plan under the condition of no one and few people. It can improve the reliability of work, the economy of operation, labor productivity, improve labor conditions, etc., and save people from heavy manual labor. Electrical automation technology is an indispensable technology in pneumatic conveying systems, reducing operation. The error rate is improved, the production efficiency is improved, and the use of the automatic control system can make the efficiency of pneumatic conveying more effective.
The electrical control system is a combination of several electrical components. The production of the electrical control system needs to be set according to the equipment parameters in the pneumatic conveying system and the causal relationship between each piece of equipment. Hengtong can customize the control system for different operations according to the different working conditions of customers. , The convenience and practicability of the control system can be realized through the control panel or DCS setting, and the safety and stability of the pneumatic conveying operation can be ensured by optimizing the causal relationship between the various equipment of the conveying system, and designing the monitoring and protection functions.
