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The volume measuring apparatus

The determination of the number of operations, by one reactor per day

,

where n – the number of operations per day;

t - the operating time of the reactor per day, hour;

t – the duration of the stages of the process, hour.

Value "n"can be found the other way:

,

where Vwith – daily volume of recyclable materials, m3;

Vg – working capacity of all devices of this technological stage.

Determination of working capacity of all devices this stage

.

Calculate the total volume of all vehicles

,

where Vcommon – total volume of all machines of this technological stage;

j - the fill factor of the device.

The fill factor of j has different values depending on the nature of the process, carried out in this unit.

When choosing the fill factor can be guided by the following data, presented in table. 8.1.

Table 8.1. Values of fill factors

The nature of the process, flowing in the reactor The degree of filling
Storage of liquid (store) 0,8¸0,90
Measuring liquids (the measuring tanks)
Physical or chemical processes without foaming effects
Processes, accompanied by foaming (an exothermic reaction, boiling, etc.)
Suspension and emulsion polymerization
0,8¸0,85
0,75¸0,80
0,4¸0,6
0,65¸0,75

The optimum capacity of the reactor is selected according to the specific conditions of this process. You must use practical data on the volume of existing production apparatus.

The calculation of the number of devices of a given stage is determined by the expression

,

where To - number of devices;

V – total one unit (catalog), m3.

If the proposed apparatus is not provided by the directory, the volume of the device is chosen for practical reasons. In any case, after selecting apparatus provides a brief description of its design characteristics and indication of the material.

Calculation of volumes of devices of continuous pastizales in determining the scope of recyclable materials, per hour (or per second)

, m3/h.

The calculation of the working capacity of all devices

Vg=Vhour×t,

where Vg – working capacity of all devices, m3;

t - the residence time of reaction mass in the apparatus, watch.

The calculation of the total capacity of all vehicles:

.

The choice of a standard unit or a new design is as follows. For devices of continuous action machines "ideal" displacement – must, first of all, to determine the relationship between the height (or length) the device and its cross section.

For a given rate of flow of the reaction mass it is possible to calculate the height (length) the apparatus of ideal displacement by the formula

N=W×t,

where N – height (length) apparatus, m;

t - the residence time of the reaction mixture, with.

Cross-sectional area of the apparatus of ideal displacement is determined as follows:

.

The number of machines of continuous action is defined, for periodic processes:

,

where V – the volume of one reactor, m3.

At the end of the calculation should contain detailed description of design features and material the selected device, as well as a description of the starting period of the reactor before it is put into a continuous process.

Combined apparatus for mixing cascade and sectional types of the main issue of the process design is to determine the optimal number of series-connected devices or partitions, as well as displacement.

In those cases, when you have the equation of the process kinetics and the known values of the rate constants of reactions, used the analytical method of calculation of a multi-reactor or cascade devices.

Below are some typical examples, illustrating methods to determine the volume of the reactor, which characterize the manufacture with the different chemical reactions with known kinetic equations, and without them.

Example 8.1. To calculate polycondensation of digitalcertificate performance W=3 t/day. The process of periodic. Data on the operation of the apparatus when loading 1 tons of digitalcertificate are shown in table. 8.2.

Solution:

.

GOST 9931-61 take equal amount of RAP 2,5 m3.

Table 8.2. The mode of operation of the reactor periodicheskogo action (RAP)

Technological stage Time,
t, h
tstart,
°C
tcon,
°C
The amount of mass in the apparatus, G, kg The number of ethylene glycol distills, kg
Download 0,3 -
Heating the RAP 1,0 -
The distillate of ethylene glycol 1,0
The reduction of pressure to 0,1 mm.St. and polycondensation 2,0
Unloading 0,7 -
Cooling apparatus 1,0 -

Example 8.2. The calculation of the duration of the reaction using the reaction kinetics. In a batch reactor, the chemical process, the speed of which is determined by the equation of the form

when n=1 and To=0,000895 with-1.

The initial concentration of the original product And equal WithA0=1 mol/l. The final degree of conversion xAnd=0,96.

It is required to determine duration of response t3.

Solution:

Next substitute t3 in tn and we finish the calculation as well, as indicated in the example 8.1.

Example 8.3. In the reactor the reaction occurs in the gas phase by equation 4A®+6C at 648,89 To, speed which is described by the expression RA=2,78×10-3×CA. The degree of transformation xAnd=0,80. The pressure in the system – 4,6 ATM. The feed rate of reactant A is equal to GAnd=5,03×10-4 KMOL/s. To calculate the volume RWND.

Solution: Volume RWND find by the formula

At constant pressure

,

where0 – the initial concentration of the reactant,

e – coefficient, taking into account the volume change of the system

.

Substitute the corresponding values in the original formula

.

After integration one obtains the following expression:

;

KMOL/m3.

m3.

GOST 13372-87 take the nearest volume of the tubular reactor equal to 1,6 m3.

In that case, when the unknown kinetic rate constants of the reaction, stay take practical data (from the regulations of Department).

Below is an example of the calculation of the volume RUNG on the adopted value of the residence time t.

Example 8.4. To calculate the volume RWND for daily production
50 tons of ethyl acetate from acetic acid. Raw data: time t=7270с, the density of the reacting mixture constant r=120,56 kg/m3.

Solution:The designated space velocity of the reacting mixture for the production of 50 t matter.

m3/with.

RWND volume defined by the equation

VRUND=VWith×t=4,8×10-3×7270=34,8 m3.

GOST 13372-67 take the nearest amount of the device, equal
40 m3.

Example 8.5.In RSND is the reaction of the type A®In, which is characterized by a kinetic equation RAnd=5,55×10-5×WithAnd, with-1. You must obtain 2,77×10-5 KMOL/s of substances In the original mixture, containing the substance And the quantity 0,1 KMOL/m3. The degree of transformation xAnd=0,5. You want to determine the volume of reactor mixing.

Solution: RSND amount defined by the equation

.

Express WithAnd=And0×(1-xAnd). Determine the feed rate of the starting mixture

KMOL/s.

Substitute these values into the first equation and we get the desired volume value

.

GOST 13372-67 take equal amount RSND 10 m3.

When you run the project engineer is obliged to perform technological calculations of auxiliary equipment, all transport devices (belt and screw conveyors, pneumatic transport, etc.), and also to calculate the required performance and to select appropriate types of feeders, dispensers, batchbox, cyclones and t. d.

The calculation of appropriate equipment is not considered here, it can be found in the literature on processes and apparatuses of chemical technology.

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