In flour milling, storage is directly related to product quality. Flour is prone to adsorb impurities, moisture caking, and may also harbor microorganisms, the sanitary condition of the storage equipment directly determines the safety and stability of the final product. Hygienic stainless steel silo is the mainstream storage equipment in the industry with suitable material and structure design. The silo mentioned here can be combined with the characteristics of flour storage, from the material, structure, sealing, cleaning, safety and other aspects of the formation of a comprehensive design standards, each point is closely related to storage safety, processing suitability.
Sanitary stainless steel silo in the role of flour processing
The quality and stability of flour from the receipt of raw materials, through the processing of the whole process, the health control of the storage link is particularly critical. Flour in the storage process, if contact with impurities, water vapor, pests or microorganisms, it is very easy to caking, mold, odor and other problems, not only affect the processing performance of flour, but also pose a serious threat to food safety.
Sanitary stainless steel silo through scientific design, can effectively isolate the external pollution, keep the environment inside the silo clean and dry, to provide stable storage conditions for flour, to ensure the consistency of the quality of flour from storage to subsequent processing.
In the whole flour milling process, the silo is not an isolated storage equipment, but closely synergized with the milling unit, pneumatic conveying system and packaging system. Raw materials, after milling, are pneumatically conveyed into the silo for temporary storage, and then orderly discharged from the silo according to packaging or further processing requirements, forming a highly efficient closed loop of production.
If non-hygienic silos are used, there may be gaps, dead corners or materials that do not meet food contact requirements, which can easily cause flour residue, bacteria or adsorption of pollutants. These problems will not only lead to an increase in flour loss, but also may lead to food safety accidents due to product contamination, which will bring economic loss and brand risk to the enterprise.
The core hygiene design principle of stainless steel silos for flour milling
Hygiene design is the core competitiveness of stainless steel silos for flour milling, and is the basis for ensuring the safety of flour storage. This principle runs through the silo material selection, structural processing, sealing design and other aspects, each detail is centered on the “non-polluting, easy to clean, anti-residue” core requirements.
Food-grade stainless steel materials for flour contact
silo and flour direct contact parts, material selection must meet the strict requirements of food contact materials, the industry’s most widely used are 304 and 316L stainless steel. 304 stainless steel has good corrosion resistance and mechanical strength, to meet the needs of most of the flour milling scenarios, more cost-effective, is the basic model of food-grade stainless steel materials. Material.
For processing environment with high humidity, or special hygiene requirements of the enterprise, 316L stainless steel is more suitable. It adds molybdenum on the basis of 304 stainless steel, corrosion resistance, oxidation resistance is stronger, and can effectively resist water vapor, slight acidic and alkaline environment on the erosion of the material, to further reduce the risk of material contamination of flour.
In addition to the performance of the material itself, the compliance and traceability of food-grade stainless steel is equally important. Enterprises in the procurement of silos, you need to ask the supplier to provide material certificates, food contact materials compliance test reports and other documents to ensure that the stainless steel material used in accordance with GB 4806 series and other national food contact material safety standards.
The traceability of the material can guarantee that when subsequent problems occur, the source of the material can be quickly located and production batch, to provide strong support for food safety traceability, which is also the basic requirements of the food processing industry on the material of the equipment.
Hygienic treatment of the inner surface and welding quality
The inner wall of the silo is in direct contact with the flour, and the roughness of its surface directly affects the residual situation of the flour and the difficulty of cleaning. The industry usually requires that the inner wall roughness Ra value is not more than 0.8μm, smooth surface can reduce the adsorption and residue of flour particles, and at the same time, it is easy to carry out the subsequent cleaning operations.
In order to avoid gaps and dead corners breeding bacteria, flour accumulation, sanitary stainless steel silo commonly used all-welded structure, instead of the traditional bolt connection. The welding process requires strict quality control to avoid problems such as false welding, leakage welding, etc., to ensure the sealing and firmness of the weld.
The weld part is the key area of hygiene control, and after the welding is completed, it must be ground and polished, so that the surface of the weld and the inner wall of the silo to maintain a smooth transition, with no bumps, depressions or gaps. After grinding and polishing, the welded seam should reach the same roughness standard with the inner wall, to eliminate the health dead corner fundamentally.
Fully sealed anti-pollution structure design
The flour processing workshop is dusty and susceptible to external pests, water vapor and pollutants, so the fully sealed design of the silo is crucial. All the openings of the silo, such as inlet, outlet, manhole, access port, etc., need to be equipped with reliable sealing structure to realize the double protection against dust and insects.
The selection of sealing materials should also meet the requirements of food grade, and the use of seals containing harmful substances and easy to age off is strictly prohibited. Commonly used food-grade sealing materials, including silicone rubber, fluoroelastomer, etc., these materials are not only excellent sealing performance, but also has a high and low temperature resistance, not easy to aging, odorless, etc., will not cause contamination of flour.
In addition to protecting against external pollutants, the sealing structure also needs to effectively prevent water vapor condensation inside the silo and external water vapor infiltration. When water vapor enters the silo, it will cause the flour to be damp and lumpy, and even breed mold, which will affect the quality of flour, so the sealing design should take into account the moisture-proof function to ensure the dry and stable environment inside the silo.
Easy-cleaning and residue-free discharge design
Flour has a certain degree of viscosity, if the internal structure of the silo is not reasonably designed, it is very easy to have problems such as hanging powder, material residue, etc., and the long-term accumulation of residual flour will breed bacteria and contaminate the subsequent storage of materials. Therefore, easy to clean and no residual discharge design is one of the core characteristics of sanitary silo.
The cone design of the silo directly affects the discharge effect, usually with a large cone angle design, the cone angle is generally not less than 60 °, such a design can utilize the gravity of the flour itself, to ensure that the material is completely emptied, to avoid the formation of accumulation of residues in the cone. Part of the special scenarios, can also be equipped with flow aids to assist the discharge of materials to further reduce the residue.
The overall structure of the silo needs to be easy to clean, with no complicated bumps or dead corners on the inner wall, and compatible with dry cleaning or auxiliary CIP (Cleaning In Place) cleaning methods. For silos that need to be cleaned regularly, the internal structure should be designed so that cleaning tools can easily reach all parts, reducing the difficulty of cleaning, improving cleaning efficiency, and ensuring that there is no flour residue and bacterial growth after cleaning.
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Elimination of dead ends of the sanitary structure design
Sanitary dead ends are one of the main sources of contamination in the process of flour storage, so the elimination of all the dead ends in the silo is the core requirement of the sanitary stainless steel silo structure design. In addition to the treatment of welded parts, the overall structural layout inside the silo also needs to follow the principle of “smooth, no accumulation”.
Traditional silo internal reinforcement bars are mostly exposed design, easy to form bumps and gaps, and become a dead end for flour accumulation and bacterial growth. Sanitary stainless steel silos usually use external reinforcement or internal reinforcement smooth treatment to ensure that the surface of the silo is not exposed bumps, all structural transitions are smooth, to avoid the accumulation of flour in the localization.
Manhole and access port is an important channel for daily maintenance and cleaning of the silo, and its design should also take into account the health requirements. Sanitary manholes and access ports need to be equipped with a cover plate with good sealing performance, the cover plate and the silo connection needs to be smoothed, with no gaps and dead ends, and at the same time, it is easy to open and close, so as not to affect the daily operation and cleaning and maintenance.
The layout of pipelines, valves and other components inside the silo should also avoid the formation of sanitary dead ends. All components should be as close as possible to the silo wall or embedded design to reduce the raised parts, to ensure that the flour can flow smoothly and not produce a buildup of residue.
Moisture-proof and anti-condensation design features
Flour is highly hygroscopic, so if the storage environment has high humidity or condensation, it will easily lead to lumps and molds, which will seriously affect the quality and shelf life of the flour. Therefore, moisture-proof and anti-condensation design is an important feature of sanitary stainless steel silo to adapt to different storage environments.
For different regional climatic conditions and storage environment, sanitary stainless steel silo will be equipped with corresponding thermal insulation program. Commonly used insulation methods include wrapping insulation in the outer wall of the silo, or double-wall structure filled with insulation materials, effectively isolating the external temperature changes on the environment of the silo, reducing the possibility of condensation on the wall of the silo.
In addition to insulation measures, the silo will optimize the ventilation structure, control the humidity inside the silo and other ways to prevent condensation. Some high-end silo will be equipped with temperature and humidity monitoring system, real-time monitoring of temperature and humidity changes in the silo, once the humidity exceeds the standard or temperature anomalies, can be taken in a timely manner to take measures such as ventilation, to avoid condensation caused by flour caking and mold.
In the design process, the influence of different environmental temperature differences, such as low temperature in winter, high temperature and high humidity in summer, etc., will also be fully considered to ensure that the silo can maintain a stable storage environment under different climatic conditions through reasonable structural design and material selection, so as to ensure that the quality of flour is not affected.
Flour dust explosion-proof and pressure relief design
Flour belongs to combustible dust, when the dust reaches a certain concentration in the air and meets the ignition source, it is very easy to cause an explosion, which brings serious threat to the production safety of the enterprise. Therefore, sanitary stainless steel silo must have perfect dust explosion-proof and pressure relief design, in line with the dust explosion-proof safety standards.
Flour dust flammability risk mainly comes from the storage and transportation process of dust accumulation, so the silo design needs to minimize the generation and accumulation of dust, while equipped with reliable explosion-proof and pressure relief devices. Explosion relief device is the core component of explosion-proof design, usually installed on the top or side of the silo, when the silo dust explosion occurs, the explosion relief device can be quickly opened to release the explosion pressure, to avoid structural damage to the silo.
In addition to the explosion relief device, some silos will be equipped with explosion suppression system, explosion isolation devices, etc., to further enhance the explosion performance. Explosion suppression system can be quickly sprayed in the early stages of the explosion suppressant, inhibit the spread of the explosion; explosion isolation device can prevent the explosion flame spread to other equipment or areas, to avoid the expansion of the accident.
Sanitary accessories and interface components
The sanitary performance of sanitary stainless steel silo not only depends on the main structure, its supporting accessories and interface components are equally critical. These components are directly involved in the flour feeding, discharging, sampling, testing and other links, if the design or material does not meet the hygiene requirements, will also cause flour contamination.
The feeding and discharging interface is a key part of the connection between the silo and the conveying system, which should be of sanitary design, with smooth interface surfaces, no dead corners, and excellent sealing performance, to avoid flour residue or external pollutant infiltration in the connection part. The connection of the interface should be easy to dismantle and clean for daily maintenance.
Valve and discharge device as the core component to control the flow of flour, must use food-grade sanitary valves, such as sanitary butterfly valves, ball valves and so on. The internal structure of these valves should be smooth without dead ends, the material meets the requirements of food contact, sealed tightly after closing, no leakage, and at the same time, it is easy to clean and maintain, to ensure that the flour is not contaminated in the process of conveying and discharging.
The design of hygienic sampling port and inspection port should take into account the convenience of sampling and hygienic safety. The sampling port should be equipped with a sealed cover plate to avoid external pollution during sampling, and easy to clean after sampling without flour residue; the inspection port should be convenient for the staff to observe the situation inside the bin, and the sealing performance is good, without affecting the hygienic environment inside the bin.
Installation and operation suitability in the flour mill
sanitary stainless steel silo installation and operation suitability, directly affecting its use and service life, but also related to the smoothness of the flour milling process. In the installation process, according to the site conditions of the flour milling plant, the production process and other factors, reasonable planning of the installation location and mode.
For silos installed indoors, it is necessary to consider the spatial layout of the workshop, ventilation conditions, load-bearing capacity and other factors to ensure that the installation of the silo does not affect the operation of other equipment and personnel, and at the same time facilitates daily cleaning and maintenance. Outdoor installation of the silo, you need to focus on the wind, rain, lightning, frost and other issues, equipped with the appropriate protective measures to avoid damage to the equipment caused by bad weather.
With the increasing level of automation in the flour milling industry, silos need to have compatibility with automated milling systems. The silo’s feeding, discharging, temperature and humidity monitoring functions need to be able to interface with the mill’s automated control system to realize remote control and data collection, improve production efficiency, reduce manual operation, and ensure the hygiene and safety of the operation process.
The accessibility of maintenance and repair is also an important factor to be considered in the installation and design process. Manholes, access ports, valves and other components of the silo need to be set up in a location that is easy for staff to operate, while reserving enough space for maintenance to facilitate daily maintenance, cleaning and troubleshooting. Reasonable accessibility design can reduce maintenance costs and improve the stability of equipment operation.
Summary
For flour milling enterprises, the choice of hygienic stainless steel silos that meet the requirements of key features is not only to meet the basic requirements of food safety regulations, but also an important measure to protect product quality and enhance the competitiveness of enterprises. These core features of the landing, can fundamentally avoid the risk of contamination in the storage link, to ensure that the flour from storage to processing of the whole process of quality and stability, to provide consumers with safe, high-quality flour products.