It is well known that the moisture content of the dryer and cooler of the compound fertilizer production line is high, the dust concentration is large, and the compound fertilizer dust is easy to absorb moisture and other factors. For many years, the bag filter has not been widely promoted in the compound fertilizer industry. The main technical barriers of the hand, the abandoned bag dust collector is only used to control the traditional concept of the production environment, the special bag filter for the compound fertilizer can replace the backward process of the original compound fertilizer production line dryer and the exhaust gas of the cooler using the cyclone + sedimentation chamber. A number of technological innovations ensure long-term stable operation of the bag filter under high-humidity and dust-containing gas conditions.
I. Introduction:
In the whole steam granulation compound fertilizer production process, dryer exhaust, cooler exhaust, vibrating screen or drum screen, crusher and other equipment will generate a large amount of dust, affecting the production environment, if these dusts are not effectively recycled, The pollution of the environment even affects normal production. More importantly, a lot of valuable raw materials are wasted. The dust is treated by cyclone + sedimentation chamber, the dust removal efficiency is low, up to 60-70%, and the dust chamber should be cleaned frequently, waste manpower and material resources, and the recycled dust has different composition differences due to the production of different content of products, and cannot be directly Used for returning materials. With the bag filter, the dust removal efficiency is up to 99%, and the discharge concentration completely meets or exceeds the national standard. Because the dust is instantly recovered, there is no difference in composition, and it can be directly transported to the return belt through the belt conveyor for secondary granulation. Or collect the dust as a high-quality raw material for the production of flushing fertilizer, which saves a lot of labor costs for manually cleaning the dust in the dust chamber and increases economic benefits.
Second, the design principle of bag filter system for compound fertilizer production line;
Combined with the high-humidity dust-containing gas under actual working conditions, the dust is easy to absorb moisture, etc., through technological innovation and key technical treatment programs. Ensure that the bag filter is operated reliably and stably for a long time under the conditions of high humidity and dusty flue gas, avoiding the dust hydrolysis paste bag. Effectively prevent dust from sticking, causing ash failure, ash discharge system failure and serious ash accumulation in the pipeline. At the same time, it can realize maintenance and replacement of the dust collector without stopping, and reduce unnecessary parking rate.
Third, the technical indicators after the implementation of the bag dust removal system program:
1. Dust capture rate: >98% (There is no flying dust in the workshop, the production environment has been greatly improved.)
2. Dust emission concentration ≤ 30mg/Nm3 (fully meet or exceed national emission standards)
3. Energy consumption index: about 10% increase in energy consumption (bag dust collector fan requires high wind pressure, motor power is slightly larger)
4. Dust recovery: 8-10 tons / day (can be directly returned to granulation or used as raw materials for production of fertilizer)
5. Saving cleaning costs: 60,000-80,000/year (cleaning room once every 15 days, cleaning up about 4,000 yuan each time)
6. Production line parking rate: 60% reduction (do not clean the settlement room, no downtime maintenance can greatly reduce the parking rate)
7. Annual production capacity: increase by 10-15% (integrated factors can effectively increase production capacity)
Fourth, the overall design idea of ​​the bag dust removal system:
(Gold Chia Tai Co., Ltd. 200,000 tons of compound fertilizer compound fertilizer production line, for example)
1. Process: After the compound fertilizer is granulated by steam in the granulator, the wet material is cooled and hardened on the belt conveyor, and then dried and dehydrated into the l# dryer. The dried material enters the first-stage cooling drum for natural cooling, and then is lifted to the second floor by the hoist to be sieved. The large particles after the sieving are crushed and returned to the granulator together with the fine material under the sieve to regranulate. The qualified particles are then cooled into the secondary cooling drum, and then lifted to the second floor by the hoist to be sieved. The qualified particles after screening are treated by moisture-proof and anti-caking coating, and then air-cooled into the finished belt measuring package. .
2, bag dust removal system design: combined with the actual working conditions of the production line and the drying machine, cooling machine exhaust gas measured data of the same level production line, taking into account the need to ensure the exhaust volume of the dryer, cooling drum in the entire production system, Minimize the problem of uneven air distribution caused by ventilation ducts. The dryer exhaust gas is treated with a two-stage filter bag filter (1# dust collector), and the 1# cooling drum and 2# cooling drum are combined. The table cloth dust collector (2# dust collector) is used for processing, and the dust gas of the flat vibrating screen, the crusher and the conveyor belts of the belt conveyors on the second floor are collected together and treated by a bag filter (3# dust collector). The bag dust removal system has the functions of heating, heat preservation and blending hot air, so as to ensure that the high-humidity dust-containing gas is not lower than the dew point temperature, and the dust-absorbing moisture-absorbing paste bag is avoided.
5. Key technical treatment of bag dust removal system:
1) Dryer high temperature dust exhaust bag dust collector system features:
1. Because the tail gas of the dryer in the compound fertilizer system is high-humidity dusty gas and the dust concentration is high, in the dust removal system, the double-tube heating type cyclone dust collector is used for the first-stage dust removal, and the large particle dust is under the action of centrifugal force. It is possible to remove 60-70% of the dust and then enter the bag filter for fine filtration.
2. Adding a mixing air valve to the main flue gas pipeline before entering the cyclone dust collector, the mixing air valve is connected to the hot gas main pipe of the hot air furnace, and is used for opening the mixed hot air when the flue gas measurement is lower than the dew point temperature. Gas is heated, this device is only used under certain working conditions.
2) The insulation and heating function of the bag filter:
In order to avoid the ambient temperature of the precipitator is lowered and the temperature in the bag filter is lowered when parking for a long time. The dust remaining on the surface of the dust filter bag and the ash wall absorbs moisture, and a steam heating coil is added to the dust hopper and the four walls of the box to increase the temperature inside the dust collector and avoid the dust bonding paste bag. The dust collector and the air inlet pipe are treated with 10cm rock wool for heat preservation.
3) Selection of filter material and processing technology for bag filter:
In the selection of polyester needle felt filter material, the filter material should be treated with PTFE microporous film. This is the most advanced filter material post-treatment technology. After the film is coated, most of the dust is trapped on the surface of the filter bag film. It is easy to bond and block the filter bag, and has the functions of easy cleaning, water and oil proof, acid and alkali corrosion resistance. (Note: PTFE - chemical name: PTFE, is the most resistant to the "king of fiber", moisture resistance ≤ 30% and has very good chemical stability, acid and alkali resistance, oxidation resistance, and extreme High weather resistance.)
The dust-removing cloth bag adopts the advanced ultrasonic hot-melt filter bag making process, which can solve the drawbacks of the traditional three-needle six-line sewing filter bag subject to the sewing thread material and process limitation, and the use of the non-durable opening line in the long-term environment with acid-base corrosion environment. This process can increase the life of the filter bag.
4) Design of anti-blocking ash and ash discharge system:
Compound fertilizer dust is very easy to absorb moisture and bond. Conventional screw conveyor will squeeze the dust on the spiral wall to form a very dense ash layer, and the thicker and thicker the spiral blade wears, the motor load is large. . Therefore, our company has carried out various technical improvements on the screw conveyor to adapt to the smooth delivery of compound fertilizer dust.
New anti-blocking easy to clean ash and ash discharge system:
1. The spiral ash conveying machine is integrated into the ash hopper. Since the ash hopper is sealed and the steam drum heating device is arranged on the outer surface of the ash hopper, the dust remaining at the bottom of the ash hopper is not easy to absorb moisture to form a slab.
2. The lower part of the ash bucket is flanged. Once the dust slabs in the ash bucket wear the spiral blades, the ash hopper bottom cover can be easily removed for cleaning. The ash discharge valve is also designed with an inspection door to facilitate the cleaning of the dust adhering to the V-shaped trough.
5) Off-line cleaning and non-stop maintenance technology design:
Off-line cleaning technology: the dust collector is divided into several independent chambers, and a pneumatic offline valve is installed at the outlet of each unit chamber. When cleaning, the offline valve of the current chamber is automatically controlled by PLC to make the whole cleaning. The process is not disturbed by the updraft, accelerates the dust to fall, reduces the secondary adsorption of the dust, and makes the duster more thorough.
Non-stop maintenance technology: It is an extension of the offline cleaning technology. It requires manual control of the pneumatic offline valve and the air inlet damper butterfly valve during off-line maintenance, so that the single chamber is offline and has no negative pressure, while the other chambers work normally. You can repair or replace parts without downtime.
6) Anti-ashing design of pipes and ash buckets:
Using an advanced electro-pneumatic dropper, an electro-pneumatic percussion hammer is placed at intervals of 5-6 meters on the main pipe. When working, the hammer can be activated from the far and near by a special control system. The ash on the ground is shaken, and the dust falling off can be removed under the action of high negative pressure and high wind speed (pipe wind speed 18-20 m/s), which can effectively solve the sticky wall in the production process of powder materials. , hanging material, blockage, bridging, etc. and no damage and deformation of the silo.
The problem of dust adhesion on the wall of the ash can also be solved by the electromagnetic pneumatic powder falling device.
Six, review
The bag filter has the characteristics of reliable operation, automatic PLC program control, simple operation, labor saving, and low operating cost. With the promotion and application of new technologies and new materials for bag filters, the application of bag filters in the compound fertilizer industry is not limited to the role of the production environment, but gradually becomes the tail gas treatment and dust recovery in the compound fertilizer production line. Key equipment for the multiple roles of utilization and environmental governance.
Twin-Wall Pc Hollow Sheets ,Polycarbonate Hollow Solid Corrugated Sheet,Polycarbonate Hollow Sheet Clear,Hollow Core Polycarbonate Sheets
NINGBO CHAOMEI PLASTIC CO.,LTD , https://www.pcban88.com