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Food Processing

Selection of Level Meters for its Application in Grain Oil Production

In recent years, with continuous improvement of production automation and optimization in China, output of grain oil production keeps increasing and its quality has improved significantly. Grain oil manufacturers also demand higher quality level measurement equipment, such as liquid level switches and magnetic level indicators. In order to help users better select the most suitable level measuring instrument for grain oil production, we are going to introduce how to select and apply liquid level switches in grain oil production process in this article.

1. Application of oil level measuring instruments such as liquid level switches in grain oil production

To meet edible oil quality standard, oil production must undergo multiple refining processes such as deacidification, degumming, decoloring, and deodorization etc. Generally there are two methods to produce edible oil at present: pressing method and leaching method.Below is the flow chart for edible oil production process:

Selection of Level Meters for its Application in Grain Oil Production

Fig.1 Edible oil process flow chart

From the production preparation to edible oil final product, each step in the process has a decisive effect on the quality of edible oil production and there are varieties of special equipment and various instruments involved in each step.

Special equipment includes washing pot, neutralization reaction tank, oleic acid reaction tank, vacuum desolvator, white clay premix tank, decolorization tower, deodorization tower etc. The onsite liquid level measurement instruments used with this special equipment are two types: level switches and continuous level meters. Among them, a fork liquid level switch is generally used on pipelines to control liquid level and operation (on/off) of pumps. At the same time, magnetic level indicators are used for many large and small storage tanks onsite to detect liquid level. Magnetic level indicator has advantages of simple installation and easy onsite inspection. It is widely used for various storage tanks. For safety reasons, besides installing a magnetic level indicator on the tank, level switches are also installed at high and low positions on the tank for double safety assurance.

2. Selection of oil level switches

There are many level meter manufacturers in the market at home and abroad offering different quality of products. It is very important to select proper oil level meters because process data in the production process such as liquid level, flow rate, temperature and pressure etc. are transmitted to a PLC control system from these measuring instruments onsite. If one of the instruments fails to measure or measures inaccurately, it will directly affect product quality and production efficiency, even lead to serious safety accidents and cause huge economic loss to the enterprise.

Safety in production process is very important. Users usually select measuring instruments very carefully. The working conditions in grain oil production process are quite complicated. For example, material temperature in some steps is very high, about 250ºC; There is higher pressure in some storage tanks; some materials are with high viscosity; and grain oil is flammable, etc. Therefore, higher technical requirements are placed to the level meters:

1. With high temperature resistance, can work reliably at 250ºC process temperatures.

2. With high pressure durability, high temperature working conditions are often accompanied with high pressure.

3. Grain oil is flammable, and measuring instruments in the production process must be with Explosion-Proof Certificate.

4. With large redundancy for material buildup because grain oil is sticky and easy to stick to the measurement probe to result in measurement errors.

An edible oil company in Shantou introduced a new Swedish process in which a new type of soft tower deodorization system and a thin film packed tower for deodorization combined with a tray tower for thermal decolorization are used. In soft tower, oil flows vertically in the packed tower to effectively contact with water vapor. Unlike the traditional deodorization tower which works under normal pressure, the new soft deodorization tower works in vacuum environment, and the "pressure" in the new soft deodorization tower changes very little. At 250℃, free fatty acids and odors can be effectively removed in very short time with a small amount of steam. Because a complete set of equipment was imported, a good quality of measuring instruments was needed to assist the normal operation of the equipment. The customer carefully compared and tested various instruments in the market at home and abroad. Finally, Shenzhen Jiwei Ring-11 Fork Liquid Level Switch and Flap-11 Magnetic Level Indicator successfully won the bid because of the excellent quality which is comparable to imported brand names and its high cost-effective ratio.

Fig.2 Ring-11 Fork Liquid Level Switch installed onsite

Fig.3 Jiwei Flap-11 Magnetic Level Indicator installed onsite

Jiwei Ring-11 Fork Liquid level switch is a compact highly reliable level switch dedicated to liquid level measurement and control. It has following characteristics and advantages:

1. With industry leading performance in high temperature endurance, process temperature can be up to 250℃.

2. Based on detecting changes of vibrating frequency when fork body comes into contact with the measured material. The measurable medium density can be as low as 0.5g/cm³.

3. With compact design, only 40mm long, not only suitable for vessels, storage tanks and other various tanks etc., but also suitable for pipelines and other applications with constricted space.

4. With high reliability because of detecting changes of vibrating frequency.

5. With strong disturbance resistance, measurement will not be affected by foam, bubbles, viscosity, vibration etc.

6. With flameproof enclosure explosion protection: Ex d IIC T6.

7. Ingress protection rating reaches to IP66/IP67.

The performance of Jiwei Fork Liquid Level Switch is more prominent in comparison with similar products at home and abroad.

Level switch comparison table

Specifications	Imported brand	Similar products in domestic market	Jiwei Ring-11
Measurable medium density	As low as 0.5g/cm³	As low as 0.7g/cm³	As low as 0.5g/cm³
Medium temperature	Up to 250℃	Up to 150℃	Up to 250℃
Explosion protection	Ex d IIC T6	Ex d IIB T4	Ex d IIC T6
Ingress Protection	IP66/IP67	IP65	IP66/IP67
Fork body	40mm long	Longer than 40mm	40mm long
Disturbance resistance	strong	poor	strong
Cost-effective ratio	low	low	high

Because of easy onsite observation and convenient for installation, magnetic level indicator is widely used in various industrial applications. However, it is difficult for users to select among so many similar products in the market with different qualities. Compared with other similar products, Jiwei Flap-11 Magnetic Level Indicator has following advantages:

1.Distinctive design with broader display panel greatly increases visual distance and viewing angle of the instrument. With larger sharp scale and digits, display panel appears beautiful and elegant outlook.

2.Accessory such as Magnetic Switch and Reed-11 Remote Transmitters are certified for both Flameproof Enclosure and Intrinsic Safety.

3.Exceeds national standard IP54, higher rating of Ingress Protection IP65 and IP66/IP67 are selectable for different applications.

4.Made of 316L stainless steel, suitable for level measurement of majority corrosive liquids.

Jiwei Fork Liquid Level Switches and Magnetic Level Indicators have excellent quality and are highly cost effective. They are widely used in liquid level measurement for grain oil production, petrochemical industry etc. The excellent performance of level meters from Jiwei is well praised by our customers.