Toaster (Desolventizer Toaster) for Solvent Stripping from Wet Meal

General Description

The BMTR type toaster (desolventizer toaster) is a device for desolventization (removal of solvent (hexane) from wet meal after it exits the extractor. The purpose of its use is to remove harmful substances from wet meal, such as n-hexane, urease, glucosinolate and its decomposition products, as well as to denature some proteins so that it (meal) can be used as raw material for the production of protein products, feed and even for the possibility of manufacturing one of the most environmentally friendly fabrics from soy fiber.

The toaster includes functions of solvent removal, material roasting, subsequent drying and cooling. It is widely used in various types of oil extraction plants due to its energy-saving characteristics. In addition, it has advantages such as wide application range, reliability in operation, convenience in operation and maintenance, stability of technical indicators, good desolventization and material dehydration effect.

Housing

The BMTR type toaster is a vertically positioned column consisting of a certain number of sections (pans). The number of sections in the toaster depends on its capacity. As an example, consider a toaster with eight sections (capacity 400 tons of wet meal per day, see figure on the right).

Structurally, it consists of two preliminary desolventization sections, three mixed desolventization sections, main desolventization section, drying section, cooling section, power unit, and discharge device.

Desolventization (Solvent Stripping Process)

As noted above, this toaster has two preliminary solvent stripping sections. Indirect steam is supplied to the lower parts of these sections, thereby heating and, as a result, increasing the temperature of the wet meal and thus evaporating most of the solvent. This, as well as additional passage of material through three mixed stripping sections, significantly reduces the solvent content in the meal before its final stripping with direct steam in the sixth section.

The meal after the first five stripping sections still contains a small amount of solvent. In the sixth section - the deep desolventization section - the meal is subjected to leaching with direct (live) steam. The outer shell of the section has a steam jacket, and the bottom plate has thousands of steam holes through which direct steam is sprayed under pressure of 0.05-0.1 MPa. The sprayed direct steam completely contacts the material when passing through its layer, which predetermines complete use of steam and ensures almost ideal effect of solvent removal from the meal.

Drying and Cooling

The meal, which in the sixth section has reached the required indicator of residual solvent content, eventually enters the drying section, which mainly serves to retain the material, regulate its humidity and recover heat. After passing through the drying section, the high-temperature meal enters the cooling section, in the lower part of which there are also thousands of holes for supplying cold air. After the meal temperature drops below 45°C, it is transported directly to the meal warehouse for storage or sale, and the blown air is directed to a cyclone for precipitation of meal residues.

Transmission

The transmission consists of a main shaft and several systems of different type agitators. The preliminary and mixed sections, as well as the drying and cooling sections, are equipped with double-arm agitators, the purpose of which is to make the material layer homogeneous as a result of its mixing. The sixth section - the deep solvent stripping section - is equipped with three types of agitators functioning in three levels of the meal layer. In the upper layer, the material is mixed by a double-arm agitator, which is used for its uniform dispersion; the middle layer is equipped with a single-arm agitator, and the lower one - with a double-arm agitator. The middle and lower level agitators serve to mix the meal to ensure free access of direct steam to all layers of material and thereby improve the effect of solvent removal and give the material homogeneity. The transmission mechanism uses bottom drive. The agitator shaft is connected to the reducer through a coupling and then driven by a motor.

Sectional Material Discharge Mechanism

Each section is equipped with an automatic material discharge device that automatically activates when the material layer reaches a set height. This mechanism is characterized by simple design and reliability in operation.

BMTR 340x8 Toaster Technical Parameters