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Control and management of wheat moisture regulation process

Nov 30, 2023

Control and management of wheat moisture regulation process

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(1) Determination of grinding water and wheat moistening time

Proper and relatively stable grinding moisture is an important condition for the milling process to run optimally. In actual production, in order to achieve the best milling performance of wheat moisture, the optimal grinding moisture and wheat wetting time of wheat should be reasonably determined.

Determination of grinding moisture

According to the general law of milling process, the grinding water should be between 15% ~ 17%. The reference grinding moisture range of hard wheat is 15.5%~17%, and that of soft wheat is 14%~15.5%. Considering the influence of factors such as the type of specific milling process, the state of raw materials, the moisture requirements of the product, the quality and yield of the product, the moisture loss in the grinding process, the climate and operating habits, etc., the optimal grinding moisture of wheat is also different.

Under normal conditions, the higher the water content of the mill, the better the quality of the product, the lower the ash content, the better the color, but the fluidity of the material becomes poor, the moisture of the corresponding product increases, and the storage period is shortened; When the grinding moisture exceeds a certain value, it will also lead to a significant decrease in yield and flour yield. For a stable process, under the premise that the yield and flour moisture meet the requirements, the grinding moisture of the flour when the quality is good, the ash content is low and the yield rate is high should be used as the optimal grinding moisture of the corresponding raw wheat.

According to certain conditions, once the grinding water is determined, it should be kept relatively stable. Under the condition that the raw materials and product requirements remain unchanged, if the grinding water fluctuates, it will not only be unfavorable to the product quality and output, but also the distribution ratio of various intermediate products in the powder road will also change irregularly, which will cause difficulties to the operation of the powder road.

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Determination of the time of wheat running

It generally takes 8 hours for the moisture on the wheat skin to penetrate evenly in the grains, and it takes about 12 hours to complete the physical and chemical combination, volume expansion and heating reactions with the internal substances of the wheat, and to exist in the wheat grain structure in a relatively stable state, but it takes more time to achieve the equilibrium of all wheat grains through the conduction between the grains.

When the primary water process is adopted, the wheat running time is generally controlled at 16~30h. When there are more hard wheat in the raw materials, the moisture content of the raw materials is low, and the climate is cold and dry, the wheat moistening time should be 24~30h hours; When the raw material is soft wheat, the wheat moistening time can be 16~24h.

When the secondary wetting process is adopted, the first wetting time is usually greater than that of the second wetting, and the corresponding first wetting time is about 20 h, and the second wetting time is about 16 h.

In production, the requirements for the wheat running time are relatively strict, the wheat running time is too short, the endosperm can not be completely soft, the endosperm structure is uneven, and the rolling distance is not easy to adjust during grinding, and there will be a phenomenon of impenetrable grinding and difficult sifting. If the wheat is moistened for too long, it will cause the moisture of the wheat skin to evaporate, so that the moisture of the wheat skin will become dry and easy to break, which will affect the milling performance.

(2) Calculation of the flow rate and amount of landing

The water flow rate refers to the weight of water added to the wheat per unit time of the water equipment, and the unit is kg/h. The water flow rate is the main working parameter of the moisture conditioning equipment, and its size and stability will directly affect the effect of water regulation.

Figure 3-11 shows how the water bonding process works. Since the flow rate of dry matter of wheat before and after water is constant, the relationship between water flow and other parameters can be deduced from this basis.

Figure 3-11 The working principle of the water bonding process

Flow rate of dry matter of wheat before water = G×(100-W1)%

Flow rate of dry matter of wheat after water = (G+μ)×(100-W2)%

After the two-way finishing, it obtains:

μ＝Ｇ××100% （3-3）

The amount of water is the weight of the water added to the weight of the raw material to be added as a percentage of the water flow, that is, the water flow rate and the wheat flow rate through the water applicator. As in Eq. (3-4).

ZS ＝＝ ×100% （3-4）

Where: μ - water flow rate (Kg/h);

G - the flow rate of wheat before watering, that is, the flow rate of wool wheat cleaning process (Kg/h);

W1 - moisture of wheat before watering, i.e. moisture of wool wheat (%);

W2 - the moisture of wheat after watering, ≈ into the mill water (%);

ZS - Amount of landing, % (Kg water/Kg wheat).

During the cleaning process, there is a loss of moisture in the wheat; If spraying water is used, the moisture of wheat will increase slightly, and the increase or decrease of wheat moisture in these processes is generally 0.1%~0.4%, so the moisture of wheat after water is different from that when it is milled. However, the water content of the mill is generally 15%~17%, the comprehensive impact of loss and spray on the moisture can be ignored, and the wheat that has just been watered is also inconvenient to measure, so in the actual production, it is considered that W2 is the water in the mill, so the water flow rate can be calculated by equation (3-3) and the operation of the water equipment can be guided.

ZS is the amount of water, which is used to reflect the water capacity of the water equipment. In actual production, the difference of (W2-W1) can also be used to describe the water holding capacity of the water machine, which is measured in percentage points.

MOISTURE CONTROLLER FOR WHEAT FLOUR MILL MOISTURE DETECTION CONTROL (immy.cn)

(3) Control of water flow

In daily production, if the automatic water flow control system is adopted, the water flow rate is automatically determined by the control system after the determined water entering the mill is inputted. However, for the process effect of the control system, it is necessary to regularly use manual methods to detect, generally the standard moisture measurement method can be used to detect the moisture of wool wheat, according to the known flow rate of wool wheat and the determined water content into the mill, the required water flow value is calculated by equation (3-3), and the calculation results are checked with the actual water flow rate of the automatic water landing system, and if the problem is found, it needs to be adjusted in time. If the flow rate of Maomai treatment is unstable, although the control system can be adapted within a certain range, the water flow control mechanism will operate frequently, which is likely to cause equipment failure and lead to unstable water effect. Therefore, when using the automatic water control system, it is still necessary to pay attention to maintaining the stability of the flow rate of the wool wheat.

When the manual water control system is adopted, under the premise of a certain flow rate of wool wheat, the corresponding water flow rate is calculated according to the required grinding water and the current wool wheat water content, and the water valve is operated to adjust the water flow, so that the indication scale of the rotameter is equal to the required water flow rate. In order to obtain the current wool wheat moisture in time to guide the calculation of water flow, a rapid moisture analyzer should be used to measure the wool wheat moisture every hour. In order to facilitate the operation, a water card can be made according to the actual situation of the factory to guide the operation. In addition, during the production process, the rapid moisture analyzer used should be calibrated regularly using standard moisture determination methods, and any deviations should be corrected in time.

(4) The management of the wheat warehouse

Control the wheat time, and the raw materials that have not reached the wheat time should not be released for use.

Because the moisture of the raw materials out of the warehouse in advance is mainly concentrated in the skin, the moisture of the skin is very high, the flow is difficult, and it is easy to block the equipment; The distribution of water in the raw materials is uneven, the water in the endosperm has not yet penetrated, and the main purpose of water regulation has not been achieved.

The raw materials must be in time to ensure the time of running the wheat

The timely entry of raw materials into the warehouse is the basic condition to ensure the time of moistening. In order to ensure this, in actual operation, the inflow rate of the wheat silo should be 1.2 times that of the wheat milling flow, so that there is enough wheat in the wheat silo, and the raw materials that have not yet reached the wheat time will not be released in the production for the needs of milling.

During the production process, the amount of wheat stored in the wheat silo should be checked frequently, and each production shift must meet the requirements of the total wheat storage in the wheat silo within the specified time before the operation of the wool wheat cleaning process can be suspended.

Strengthen the monitoring of the material level in the wheat silo

The material level device should be set in the upper, middle and lower positions in the wheat silo, which is not only conducive to the grasp of the amount of wheat in the silo, but also convenient for timely opening and discharging, closing and stopping the material.

Monitor the discharging process frequently

In the process of discharging in the runmai silo, in addition to paying attention to the flow state of the material in the silo pipe, the surface of the material layer in the silo should be frequently observed. If the center sinks and the surface layer of wheat moves laterally, the situation of the silo outlet and silo wall should be checked in time to prevent funnel flow.

Prevent the deterioration of raw materials in the warehouse

Moisturizing time for too long will lead to a decrease in the moisture content of the wheat skin, which will make the water regulation effect worse.