JPS5912724A - Recirculation type purification of oil of fryer - Google Patents

Abstract

PURPOSE:To suppress the oxidation of oil, by separating and removing fine particles in recirculated oil by electrostatic filtration to remove extemely fine particles. CONSTITUTION:The oil 2 in a fryer 1 heated by a burner 3 is taken out by opening the valve 5 of the arranged pipe 4 provided to the bottom part of the fryer 1 and the taken out recirculated oil is passed through a strainer 6 to remove coarse particles therein. The coarse particle removed oil is sent to a thin film evaporator 9 through an arranged pipe 8 by a pump 7 to remove moisture in the recirculated oil. The removed moisture is sent to a condenser 14 from an arranged pipe 13 and discharged to a discharge pipe 16 as condensed water. The dehydrated recirculated oil is introduced into an electrostatic filter 11 by an arranged pipe 10 and carbonized fine particles in the oil are attracted to and collected by the anode in the electrostatic filter 11. Purified recirculated oil is returned to the fryer 1 from an arranged pipe 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fryer for commercially producing fried foods, and more particularly to a method for continuously removing fried scum and chars generated in oil during use of the fryer. .

The slag and charred substances generated when frying foods in a fryer adhere to fried products and deteriorate their quality.
Not only does this reduce the product value, but it also accelerates the oxidation of the oil and deteriorates its properties, and the volatile compounds such as acrolein produced by the oxidative decomposition of the oil deteriorate the environment at work sites. Therefore, during use of a fryer, oil is purified by constantly drawing out a portion of the oil, separating the slag and charred substances contained in the oil, and then returning it to the fryer. However, currently commercially available fryers simply filter the fried slag and charred matter through a simple filter, but the particle size is 2.
It is difficult to remove particles of ~10μ. When filtration is performed using a fine mesh material such as sintered metal as a filter, the degree of filtering is large.

The present invention can remove oil slag and carbide in a fryer with little pressure loss, down to extremely fine particles of carbide, prevent oil oxidation, extend the life of the oil,
We propose a circulating oil purification method for fryers that improves the quality of fried products by removing carbonized particles.
That is, the present invention provides a circulating oil purification method in which a portion of the oil in a heated 7-ryer is drained into bales, particles in the oil are removed, and then recirculated into a fryer. After removing the water, water in the circulating oil is removed by thin film evaporation, and then an electrostatic voltage is applied to the circulating oil to electrostatically collect fine particles in the circulating oil, and the purified circulating oil is placed in a fryer. This is a circulation-type oil purification method for fryers, which is characterized by returning the oil.

Hereinafter, the method of the present invention will be explained in detail based on the drawings showing one embodiment thereof.

FIG. 1 is a flow sheet of a fryer circulation oil purification apparatus showing an example of a concrete implementation of the fryer oil purification method of the present invention.

The oil 2 in the fryer 1 heated by the cylinder burner 6 is taken out by opening the valve 5 of the pipe 4 at the bottom of the fryer 1, and the coarse particles of the taken out circulating oil are removed by the strainer B. The mesh installed in the strainer 6 has a mesh size of about 40 to 80, and this is to prevent clogging of the next pump 7, to lighten the load when removing particulates in the subsequent stage, and to increase the removal effect. be. The circulating oil from which coarse particles have been removed is sent to a thin film evaporator 9 via a pipe 8 by a pump 7. Although any type of thin film evaporator can be adopted, the purpose of the thin film evaporator used in the present invention is to remove water dispersed in circulating oil, and the circulating oil introduced has already reached a temperature higher than the boiling point of water. Because it is heated to a high temperature, there is no need for special heating during thin film evaporation.
The pumped-up circulating oil collides with the separation plate and flows down in a thin film. FIG. 2 shows an example of such a thin film evaporator, in which water flows successively through conical separation plates 21 and 22. Moisture in the circulating oil is formed into a thin film before circulation, which turns it into scum due to the high temperature of the oil, and water is almost completely separated from the circulating oil by flowing down several stages of separation plates.

In addition to the type shown in FIG. 2, the thin film type evaporator may also be of a type in which a thin film flows down the inner or outer surface of a commonly used cylinder.

The released water vapor flows from the top of the thin film evaporator 9 to the pipe 1.
3, the condensed water is condensed in a condenser 14, and the condensed water is discharged to a drain pipe 16 via a valve 15.

The circulating oil dehydrated in the thin film evaporator 9 is introduced into an electrostatic filter 11 through a pipe 10. The electrostatic filter 11 is provided with an electrode in a container containing circulating oil, which serves as an anode, and the container is installed as a cathode. A DC voltage of 5 to 50 kV is applied between both poles. Due to the electric field caused by this applied voltage, the charged fine particles in the circulating oil are attracted to the opposite electrode depending on the type of static electricity they have. Since the fine particles dispersed in oil are generally negatively charged, the carbonized fine particles in the circulating oil are attracted to and collected by the hot water electrode in the electrostatic filter.

FIG. 3 shows a cross-sectional view of an example of such an electrostatic filter, in which a cylindrical container 31 itself is used as a cathode, an anode 32 is provided in the center, and the anode is surrounded by pleated P paper. It is surrounded by 36. Fine particles in the circulating oil introduced into the container migrate to the anode due to the high voltage applied to both poles, and
Since the fine particles are collected on the top, the collected fine particles can be easily disposed of by replacing the p paper 33 as necessary.

In electrostatic filtration, if oil contains a large amount of water, the electrostatic voltage applied to both poles is likely to short-circuit, reducing the collection efficiency of dispersed particles. Therefore, a thin film evaporator is used before electrostatic filtration. It is necessary to sufficiently remove water by step 9.

The circulating oil from which water has been removed is preferably introduced into the electrostatic filter 11 from the lower part, and the circulating oil that has been electrostatically filtered and becomes clean is taken out from the -1 part of the electrostatic sweat filter 11 and passed through the pipe 11. Returned to Flyer 1.

The movement of the circulating oil from the thin film evaporator 9 to the electrostatic filter 11 and the return from the electrostatic filter 11 to the fryer can both be performed by gravity flow, and in that case, the necessary head for each can be achieved. It is necessary to provide Of course, this movement can also be done using a pump or the like.

In the purification method of the present invention, since particulates are removed by electrostatic filtration, there is no pressure loss due to clogging of particulates, and therefore continuous operation for a long time is possible.

In addition, since particulates in the circulating oil are removed using an electrostatic method,
Since even extremely fine particles are removed, there is less oxidation of the oil, extending the life of the fryer, and there is less generation of irritating volatile substances such as acrolein, which are absorbed by acids, improving the working environment. Furthermore, since carbonized fine particles that degrade the quality of fried products are removed, fried products of constant quality can be produced.

The method of the present invention can effectively remove Wl and fine carbonized particles generated during frying, and can be applied to fried products that generate fine particles such as quince sugar, rice crackers, fried bread, donuts, etc. It is particularly effective in the production of snack foods.

Example 1 Using the apparatus shown in Figure 1, 1 soybean white squeezed oil was used as oil.
heated to °C. A mixture of bread crumbs and wheat flour at a weight ratio of 6°4 was put into a fryer in an amount of 0.35% by weight based on oil, and circulating oil purification was performed.

When the oil returned to the 7-Lier from the electrostatic filter was inspected, it was found that there were almost no particulates in the oil. On the other hand, when the same oil before oil purification was passed through P paper, the result was 7 to 8 μm.
It was observed that some particles remained.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing an embodiment of the oil purification method of the present invention. FIG. 2 is a cross-sectional view of an example of a thin film evaporator, and FIG. 3 is a cross-sectional view of an example of an electrostatic filter. 1 fryer, 2 frying oil, filter ring burner,
6 Strainer, 7. Pump, 9. Thin film evaporator, 11 Electrostatic filter, 14. Condenser, 21.
22 Separation plate, 31 Cylindrical container (cathode), Filter 2 Anode, 36 P paper. Agent: Patent Attorney Katsura Atsuta

Claims (1)

[Claims] (1) In a circulating oil purification method in which a portion of the oil in the heated fryer is extracted, particles in the oil are removed, and then recirculated into the fryer, after coarse particles in the circulating oil are removed,
It is characterized by removing water in the circulating oil by thin film evaporation, then applying an electrostatic voltage to the circulating oil to electrostatically collect fine particles in the circulating oil, and returning the purified circulating oil to the fryer. , Circulating oil purification method for fryers.