Talking about how to design fermenter

The fermenter is the reaction equipment (the main equipment for realizing chemical reaction in chemical production. Its function: 1 to make the material mix evenly; 2 to make the gas disperse well in the liquid phase; 3 to make the solid particles uniformly suspended in the liquid phase; Uniform another liquid phase is uniformly suspended or fully emulsified; 5 strengthens the mass transfer between phases; 6 enhances heat transfer. For homogeneous phase reaction, mainly 1, 2 and 2 points), it has been widely used in pharmaceutical, monosodium glutamate, and enzyme production. , food industry, etc. Its main components include the kettle body, the stirring device, the heat transfer device, and the shaft sealing device. Also add other accessories as needed, such as welding manholes, hand holes and various joints (to facilitate the repair of internals and feeding, discharging), install thermometers, pressure gauges, sight glasses, safety relief devices (for the operation process) Effectively monitor and control the temperature and pressure of materials, etc. The kettle body is composed of a simplified body and two heads, and its function is to provide a certain space for the chemical reaction of the materials. The stirring device is composed of a transmission device, a stirring shaft and a stirrer. Its function is to uniformly mix various materials participating in the reaction, so that the materials are in good contact and accelerate the chemical reaction. The stirring device can be divided into non-submersible type (only the driving machine and the speed reducer and the transmission system are exposed outside the liquid and the submersible type (from the driving machine to the agitator all sneak into the liquid). The heat transfer device is set inside the kettle body. The coil or the jacket is arranged outside the kettle body, and its function is to control the temperature of the material within the range required for the reaction. The shaft sealing device is a seal between the stirring tank and the stirring shaft to prevent the escape of the reaction material and the debris. Infiltration. Usually filled with packing or mechanical seal.

1 characteristics of the fermenter

Must have sufficient strength, sealing, corrosion resistance and stability.

2 fermenter work requirements

As a reaction kettle, it is required to be clean and the reaction process can maintain a constant temperature, so that the fermentation bacteria can be fermented well. At the same time, the agitator makes the material mix evenly, accelerates the reaction speed, shortens the fermentation cycle, strengthens the heat transfer, and takes away the heat generated in the fermentation process in time to ensure the normal reaction.

3 Fermentation tank design basis <br> fermenter volume, maximum working pressure, working temperature, working medium and corrosion, heat transfer area, agitation form, speed and power, fitting those nozzles and other process requirements.

4 fermenter design requirements

The design is strictly in accordance with the provisions of the steel pressure vessel, material selection, design, manufacture, inspection and acceptance. At the same time, we strive to be economical and reasonable, and to save materials from all aspects of material selection and manufacturing.

5 fermenter design steps

5.1 material balance

The main structural parameters are determined by process calculations.

5.2 heat balance

Find the heat load and heat loss of the equipment in the process through heat balance.

5.3 Determination of structural form and size

According to the process requirements, according to the volume, weight, characteristics, heat transfer type, installation and maintenance requirements of the material, determine the structural form and external dimensions of the fermenter, such as the height of the simplified body, the choice of the shape of the head, and the choice of the shaft seal form.

5.4 material selection

According to the working conditions of the components, the pressure, temperature, chemical corrosion and other conditions as well as the provisions of the "Steel Pressure Vessel", the materials are selected from the principle of material supply and economy.

5.5 strength calculation

According to the structural form of the parts, the mechanical conditions and the mechanical properties and corrosion of the materials, the strength calculation is carried out to determine the structural size. Such as the simplified body, the wall thickness of the head and the shaft diameter. In the calculation, it is strictly in accordance with the standard.

5.6 optional parts

The reactor is equipped with agitation, transmission, sealing, heat transfer and other components, and most of them have been serialized and standardized. Therefore, the components for the reactor are selected according to the process conditions, manufacturing, installation and other factors.

5.7 Construction drawing design

1 According to the results of the design calculation, draw the construction drawing, determine the technical requirements of the manufacturing, and propose the weight of each component and the total weight of the equipment, the material variety, specifications, dosage and standard parts, and purchased parts. 2 generally includes: equipment general drawing, assembly drawing, component drawing, part drawing, special tool drawing, nozzle and bearing orientation map, pre-weld parts drawing, etc. 3 Technical requirements: technical requirements for manufacturing, assembly, inspection and commissioning, maintenance, repair, etc., can be marked on the drawings, or can be compiled separately, and called technical conditions when compiled separately.

6 specific design content

6.1 Determination of main structural parameters

6.2 Calculate the thermal load and heat loss of the equipment

6.3 tank structure design and strength calculation

1 tank length calculation

2 tank volume determination

3 Determination of the simplified inner diameter and the simplified length

6.4 Simplified body, head strength calculation and thickness determination 1 Material selection 2 Tube wall thickness calculation 3 Head wall thickness calculation 4 Hydrostatic test

6.5 opening reinforcement

1 The reason for the reinforcement of the opening is because the strength of the opening is not only weakened in the opening portion of the container, but also the deformation of the structure of the container is inconsistent due to the structural continuity of the container, and a large additional is generated at the opening and the joint. Internal force, deformation, so the thickness of the shell should be appropriately thickened at the opening.

2 general provisions for opening

a. The opening in the housing should be circular, elliptical or oblong. When an elliptical or oblong hole is opened in the casing, the ratio of the long diameter to the short diameter of the hole should be no more than 2.0.

b. When a long round hole is formed on the convex head, the opening reinforcement should be calculated according to the long axis of the long circular hole; the long circular hole is formed on the cylinder, and when the long axis/short axis is ≤2, and the short axis is parallel to the axis of the cylinder, the opening reinforcement It should be calculated according to the short axis of the oblong hole (when the long axis / short axis > 2, it should be calculated according to the long axis of the long circular opening).

8 reinforcement design principles

a. Reinforcement of equal section area: The rule of reinforcement of the board is defined by the principle that the cross-sectional area of ​​the partially reinforced metal should be greater than or equal to the cross-sectional area of ​​the shell wall weakened by the opening. This method was first adopted in the design method of opening reinforcement. It is conservative and cumbersome, but it has a long history of use. The results are more reliable under static pressure conditions. At present, more design specifications are adopted.

b. Reinforcement by limit analysis: The basic starting point of this method is that the yield pressure after the opening of the shell is substantially equal to the yield pressure when the hole is not opened, and the total stress around the discontinuous stress around the opening and the stress of the primary film is less than Double yield limit (three times the allowable stress)

This design approach only allows the use of a total reinforcement structure.

4 conditions that do not allow additional reinforcement

a. Not all openings in the container need to be reinforced, because at the time of design, the actual wall thickness of the container and the nozzle has a certain margin compared to the wall thickness required for strength. Therefore, when the opening size is within a certain range, it may not be separately reinforced.

b. 0GB150 has specific provisions for the maximum aperture that does not require additional reinforcement. When the hole is opened in the cylinder, the spherical shell, the conical shell and the convex head (within the inner diameter of the 80 mm head of the center of the head), no additional reinforcement is allowed when the following requirements are met: 1 The distance between the centers of two adjacent openings (calculated as the arc length of the curved surface) shall not be less than twice the sum of the two diameters; 2 when the nominal thickness of the casing is greater than 12 mm, the nominal diameter of the joint is less than or equal to 80 mm; When the thickness is less than or equal to 12 mm, the nominal diameter of the nozzle is less than or equal to 50 mm.

6.6 takeover selection

1 Determination of the pressure level of the take-over material and the joint flange

2 Determination of the extension length and wall thickness of the nozzle

3Select the connection form of the take-over and the container wall and the reinforcement of the take-over

6.7 Selection of other accessories

When the accessories are selected, they should be selected according to the standard pressure and size.

6.8 Stirring device design

1 agitator

a. Mixer selection

b. Stirrer power calculation

C. Stirrer strength calculation

d. Mixing shaft mechanical calculation

2 transmission design

6.9 heat transfer device design

6.10 shaft seal device design

6.11 bearing design

Determine the design content based on the type selected.

(Menggen Qiqige Inner Mongolia Chemical Vocational College)