Step-by-step instructions for working on a distillation and mash column. Digest - industrial safety Laboratory work testing a batch distillation column

Goal of the work:

Study of the operation of a laboratory packed column periodic action at maximum (full) and working irrigation.

Determination of the number of stages of concentration change (theoretical plates) in the column under different operating modes.

Determination of the height of the nozzle equivalent to a theoretical plate (HETP).

Determination of irrigation coefficient.

Determination of the temperature of the top and bottom of the column.

1. Description laboratory installation

The laboratory installation (Figure 1) includes a packed column 1, a heating mantle 2, a return condenser - refrigerator 3 and a distillate refrigerator 4. Metal spirals are used as packing in the column. To ensure the adiabatic process of the rectification process, the column has lateral electrical heating 5. Inlatrom 6. The cube of the column 1, placed in a heating mantle, has a bottom sampler 7. A condenser is used to condense the vapor phase - a refrigerator 3. The distillate selection is regulated by a tap 8. The sampled distillate is cooled in the refrigerator 4 and receiver 9 arrives. To maintain atmospheric pressure There is an air vent 10 in the column.

1- distillation column; 2 – heating mantle; 3 – return condenser – refrigerator; 4 – distillate refrigerator; 5 – lateral electric heating; 6 – LATR; 7 – sampler; 8 – tap; 9 - receiver

Figure 3 – Laboratory setup diagram

2. Experimental procedure.

An initial mixture containing NCC and VCC is prepared, 50 ml of the mixture is loaded into the column cube.

Start-up of the installation begins with the supply of water to the condenser - refrigerator. Then the heating mantle is turned on. After the mixture boils and irrigation appears in the lower part of the nozzle, the side heating is turned on. The intensity of the side heating is maintained such that a layer of liquid appears at the top of the nozzle. This phenomenon is called “flooding” of the column. “Choke” is necessary to wet the nozzle and, accordingly, intensify the mass transfer process. The side heating is then reduced until the set flow rate (number of drops per minute above and below the nozzle) is achieved. In this case, the layer of liquid located above the nozzle flows into the column cube. Side heating should be reduced gradually so that irrigation does not stop. If irrigation stops, then it is necessary to “flood” the column again. This sets the column mode corresponding to the full irrigation mode. The distillate is not selected.

After maintaining the full irrigation regime for 30-40 minutes, 3-4 drops of distillate and the residue are taken for analysis. Next, the operating mode is set with distillate selection at a speed of 6-10 drops per minute. After receiving 2.5 - 4 ml of distillate, 3-4 drops of distillate and the same amount of the residue are taken for analysis, and work on the column ends. The heating mantle and side heating stop. The supply of water to the refrigerator condenser stops 15-20 minutes after the heaters are turned off.

Four samples taken during the experiment (distillate and residue with full irrigation and operating mode of the column) are analyzed on a refractometer at 20 o C. Using the graphical relationship “refractive index - composition”, the NCC content in all samples is determined in volume fractions.

The results of the experiment are recorded in a journal. It must be kept in mind that the number of drops per minute above and below the nozzle are not necessarily equal to each other. However, they must be close and constant in time under steady-state operating conditions of the column.

Experimental data:

Full irrigation mode:

n dist = 1.392

n cube = 1.433

Volume fractions:

distillate – 0.95

cube – 0.56

Work mode:

Top of the column – 135

At selection – 18

n dist = 1.3925

n cube = 1.44

Volume fractions:

distillate – 0.92

cube – 0.51

3. Processing of experimental results

The volumetric compositions of the distillate and residue are converted to molar compositions.

With full irrigation:

During working irrigation:

Let's determine the reflux ratio:

Excess irrigation ratio:

According to the schedule we determine:

where

Number of stages with full irrigation – 15

During operating mode – 23

Packing height equivalent to one theoretical plate:

With full irrigation:

During operating mode:

Find the temperature of the top and bottom of the column:

With full irrigation: t 1 = 98.8 0 C and t 2 = 102.0 0 C

During operating mode: t 1 = 99.0 0 C and t 2 = 102.5 0 C

In operating mode, the number of theoretical plates is greater than in full irrigation, so the height of the nozzle is correspondingly smaller.

Laboratory work No. 5

“Study of the operation of failure-type lattice plates”

Goal of the work:

Study of the influence of hydrodynamic characteristics on the position of the dispersion point and the “flooding” point on a column model using an air-water system.

1,2 - rotameter; 3 - compressor; 4 - distribution grid; 5 - pressure gauge;

6 - plate; 7 - column; 8 - control valve.

Figure 4 - Laboratory setup diagram

1 Methodology of work

Turn on the compressor, creating a small air flow through the model. The pressure drop is measured using pressure gauge 5 on the plate without irrigation in order to determine the resistance coefficient of the dry plate. Then reduce the air flow to).

Set the specified water flow rate using the rotameter and create a small air flow through the model. When the plate operates at a steady state, the resistance of the plate is measured, and the maximum value of the difference, which is observed at given flow rates of liquid and gas, and the height of the foam on the plate are measured. Then the air flow rate is slightly increased using the valve on the rotameter. With a new air flow rate, after 3-5 minutes of operation the plates again measure the difference and height of the foam. Record the flow of water and air when the tray initially comes into operation. Increase air flow. The data is entered into table 1.1

Table 1.1- Experiment results

2 Processing of experiment results

Determine the relative free cross-section of the plate using the formula:

Using the air flow rate, determine the air speed in the full cross section of the column

Let's calculate the resistance coefficients of a “dry” plate, taking into account that at air flow Q 2 = 0.007 m 3 /s plate resistance
=80 Pa

Using the pressure drop across the “dry” plate, determine the resistance coefficient of the “dry plate”:

Table 2.2 - Calculation results

We studied the influence of hydrodynamic characteristics on the position of the dispersion point and the “flooding” point on a column model using an air-water system. We calculated the pressure drop across the plate and compared it with the experimental value.

Laboratory work.

Study of the rectification process

Goal of the work:

study of the rectification process ethyl alcohol on a periodic installation,

calculation of the number of theoretical plates,

coefficient determination useful action distillation column.

Basic information

Rectification is the process of separating liquid homogeneous mixtures through the mutual exchange of components between liquid and vapor obtained by evaporation of the mixture being separated. This process is based on the different volatility of the components that make up the mixture, i.e. on the difference in their boiling points at the same pressure.

The rectification process is carried out in columns, which are vertical cylindrical devices with contact devices. The most widely used in industry are distillation columns in which cap, sieve and failure plates are used as contact devices. In a distillation column, flows of vapor and liquid that are nonequilibrium in composition pass towards each other. The steam in the column goes from bottom to top, and the liquid flows from top to bottom. As a result of contact interaction, the vapor is enriched with a more volatile (low-boiling) component, and the liquid is enriched with a less volatile (high-boiling) component. The developed phase contact surface on the plates is formed by bubbles and jets of vapor as it repeatedly passes (bubbling) through layers of liquid.

The main task of rectification plants in the food industry is to obtain rectified alcohol with an alcohol concentration of at least 96% with a minimum content of foreign impurities from 40% raw alcohol. It is known that ethyl alcohol dissolves well in water, forming a binary water-alcohol mixture with varying alcohol content. Boiling point of 100% ethyl alcohol (t bale =73.8°C at a pressure of 760 mmHg. Art.) differs significantly from the properties of distilled water, and this difference is used when separating the components of various alcohol-containing materials to obtain high-concentration alcohol. There are molar, mass and volume concentrations of alcohol. Traditionally, the food and chemical industries use the concept of volumetric concentration as the ratio of the volume of dissolved liquid to the volume of the entire solution. This value is expressed as a percentage and is designated as % vol. or in fractions of m 3 /m 3 , l/l, ml/ml. Due to differences in the densities of alcohol (ρ = 0.790 g/ml) and water (ρ = 1.000 g/ml) and their thermal expansion characteristics, volumetric and weight concentrations do not always translate correctly into each other.

The separation of alcohol from a water-alcohol mixture must be carried out at a boiling point corresponding to the concentration of the mixture and constant vapor pressure above the mixture. At a pressure of 760 mm Hg. Art. The boiling point of water-alcohol mixtures of different concentrations decreases almost continuously from 100 °C at an alcohol concentration of 0% to 78.3 °C at 100%. The exception is a certain concentration region near the azeotrope point (94.6%), where the boiling point becomes slightly lower than the boiling point of 100% alcohol (Fig. 1). Azeotropic or nonseparately boiling mixtures are those in which the vapor is in equilibrium with the liquid and has the same composition as the boiling mixture.

Figure 1 – Temperature dependence of saturated aqueous-alcoholic

steam at a pressure of 760 mm Hg.

Separation of such mixtures by rectification is impossible, since condensation of vapors produces a liquid of the same composition as the original mixture, which is called “ethyl alcohol - rectified.” Its boiling point is 78.15 °C, and the alcohol concentration, set State standard Russian Federation - from 96 to 96.4%. In this case, the density of the condensed liquid at 20 °C is 8.12 g/ml, the vapor density at 760 mm Hg. - 1.601 g/ml, and specific heat vaporization - 925 J/g.

To obtain rectified alcohol, installations are used continuous action(Fig. 2). In them, raw alcohol and superheated water vapor are mixed at the bottom of the distillation column and water-alcohol vapor with a temperature of 94 ° C is converted.

The initial mixture is stored in storage tank 3, from which pump 9 through filter 11 is supplied to pressure tank 4. From pressure tank 4, the initial mixture flows by gravity through a rotameter into a heater located in cube 2, where it is heated by the bottom residue. The temperature of the initial mixture after heating is determined by the thermometer reading. In distillation column 1, the heated initial mixture is supplied to 7, 9 or 11 plates, counting from the top. The column has 12 sieve trays with segmented drainage devices. The inner diameter of the column is 200mm.

Figure 2 – Schematic diagram industrial installation continuous action using heating steam

1 – Distillation column; 2 – cube; 3 – storage tank; 4 – pressure tank; 5 – reflux condenser; 6 – distillate collection; 7 – bottoms refrigerator; 8 – collection of still remains; 9 – pump; 10 – rotameter; 11 – filter

From the lower plate, the liquid flows into the evaporator cube 2, which has a coil inside, heated by steam. The heating steam condensate from the coil is discharged into the sewer through a condensation pot. The flow of heating steam is regulated by a valve, and the pressure is determined by a pressure gauge. In the evaporator cube, part of the liquid is converted into steam, and the other is removed as a still residue. The bottom residue passes through refrigerator 7, where it is cooled with water, and enters collector 8. From collector 8, the bottom residue is returned to storage tank 3. Collectors 6, 8 and the annulus of reflux condenser 5 are connected to the atmosphere, which ensures operation of the column under atmospheric pressure. From the top plate of the column, steam enriched with the low-boiling component enters the reflux condenser 5, which is also cooled with water. Water flow is measured by a rotameter, and its temperature at the inlet and outlet is measured by thermometers. The liquid formed in the reflux condenser after complete condensation of the steam is divided into two parts. One in the form of reflux is supplied to irrigate the column, and the other is taken in the form of distillate, which enters collection 6 and is then sent to storage tank 3. The amount of reflux and distillate is measured by rotameters.

The column is equipped with samplers for liquid from the plates, reflux, distillate, liquid in the still, as well as samplers for steam entering the plate and leaving the foam layer. Steam samplers are equipped with pipe-in-pipe heat exchangers in which steam samples are condensed and the condensate is collected in separate containers. Temperature sensors are installed on each tray of the column, operating in conjunction with a secondary device. Knowing the temperature of the liquid on the plates allows one to determine the temperature profile along the height of the column.

Description of the experimental setup

Real work involves studying the process of rectification of ethyl alcohol in a laboratory installation with an electric heater (9) and periodic filling of alcohol-containing raw materials, the operation diagram of which is shown in Figure 3. The installation consists of an evaporation cube (1), a distillation column (2) vertically installed on its lid, and electric heater (9).

Figure 3 – Schematic diagram of a laboratory distillation unit with an electric heater and periodic filling of the evaporation tank with a water-alcohol mixture.

The main part of the installation is composite column, which is divided into upper (3) and lower (2) distillation parts. Top part includes a condensing device (4), a cooler (5), an alcohol selection regulator (6) and a system of pipes connecting them (10). During rectification, cooling water constantly flows in countercurrent into the condenser (4) and heat exchanger (5), made according to the “pipe-in-pipe” scheme. In the upper part of the evaporation tank, manometric tube leads are made to measure the pressure of the generated steam and the pressure drop in the column.

Unlike industrial distillation columns with cap, sieve and sink trays in laboratory columns ultra-small diameter (10-30mm) as contact elements, the most widely used are “Sulzer” type nozzles made of stainless corrugated mesh or spiral prismatic springs made of stainless steel. The process of heat and mass transfer on such contact elements occurs continuously along the entire height of the column, and a state of equilibrium equivalent to one theoretical plate occurs after steam overcomes a certain layer, the height of which is associated with the height of the theoretical plateVTT or transfer unit heightVEP . This height is usually estimated in millimeters, which makes it easy to evaluate the effectiveness of a particular nozzle byVEP . So when internal diameter columns of 30 mm, the BEP of the spiral-prismatic nozzle is 15-30, and for the “Sulzer” nozzle used in our case, 20-25 mm. However, even with a column diameter of 40 mm, their efficiency is virtually the same andVEP is 25-30 mm. Thus, for packed columns, the height of the transfer unit strongly depends on the diameter of the column and increases rapidly as it increases. Therefore one of promising directions improving energy efficiency industrial equipment is its miniaturization and use large quantity contact elements.

Safety requirements

Students are allowed to perform laboratory work only after undergoing instructions on labor safety and fire safety in the laboratory and at the workplace.

In accordance with them, before starting the installation, you need to familiarize yourself with its structure and external inspection to check the serviceability of the distillation column, evaporation tank, pipelines, shut-off valves, electrical appliances; presence of grounding, serviceability protective shutdown, electrical and thermal insulation.

The installation should be started in the presence of a training foreman and under his direct supervision.

To avoid flooding of the distillation column and emergency release of hot reflux, strictly follow the recommendations for the procedure for carrying out laboratory work.

When working on the installation, exercise caution and accuracy. Remember that during operation some of its elements and devices have a temperature of about 100 about S.

Work order

Familiarize yourself with the diagram of the laboratory setup and the location of instruments. Compose its description and prepare tables for recording test results.

Fill the evaporation tank 3/4 full with raw alcohol with a concentration of no more than 45%.

Completely block the distillate selection with its selection regulator.

Check the correct assembly and tightness of the pipe system.

Connect the inlet and outlet of cooling water to the water supply network and make sure that the series connection of the heat exchanger of the discharged condensate and the condenser itself are correctly connected in order to operate in counter-flow mode of the coolant.

* The complete time to prepare the installation for operation takes from 5 to 20 minutes, depending on work skills, the need to refill the evaporation tank, clean it, the duration of connection to the water supply network, etc.

Connect the stand to a 220 V network and turn on the power supply.

Connect the automated stand toUSBcomputer connector and run the program Start → Programs →MeasLAB→ “Rectification” (Figure 5). For a more detailed introduction to working with software, open the description of the “Software Operation Guide”.

Turn on VK 1 heater operation switch to the starting mode of 1 kW.

After stabilizing the readings of the measuring instruments, launch the computer system for automatic measurement (Figure 5) of process parameters and turn on the heating of the evaporation tank, and according to the readings of the instruments, monitor changes in the temperature of the liquid and vapor-gas environment.

Figure 5 – Appearance"Rectification" program

Monitor the consistent flow of steam generated in the evaporation tank into the distillation column and condenser; the beginning of vapor condensation and distillate formation. Record the boiling point of the solution, the temperature and pressure of the vapor-gas medium in the evaporation tank, total quantity energy spent on heating the liquid, the design of the installation and heat loss to the environment and enter the data obtained in Table 1.

Fully open the distillate selection regulator and count the number of drops entering the alcohol receiver in 20 seconds.

Set the reflux ratio to at least 4, setting the distillate selection regulator to a 5-fold reduced number of drops for the same time.

When steam and reflux of low-boiling components of the bottom liquid accumulate in the upper part of the column, a slow and consistent selection of these substances into the receiving tank is organized using a manually controlled distillate selection regulator, followed by their identification using computer records of the temperature of the vapor entering the condenser and taking into account the actual atmospheric pressure.

After the release of low-boiling components, the longest period of work begins on the rectification of ethyl alcohol itself, which is carried out at a reflux ratio of at least 3 and replacing the receiving container with a new one. In this case, it is important to prevent the column from flooding, the onset of which can be determined by the appearance of characteristic pulsations in the recording of the pressure drop in the column and the appearance of “gurgling” sounds during operation of the installation. The distillate selection is set correctly if, 5-15 minutes after stopping the selection, the vapor temperature in the upper part of the column has not decreased.

At the stage of obtaining the main product, measure traditional ways using a portable thermometer, a measuring container and a computer stopwatch and enter into the table the values ​​of slowly changing distillation parameters:

flow rate of water cooling the heat exchanger and reflux condenser;

temperature of water entering the heat exchanger;

water temperature at the outlet of the heat exchanger;

temperature of water entering the reflux condenser;

temperature of water leaving the reflux condenser.

Complete the selection of food alcohol when the temperature of its vapor exceeds 0.1 above 78.3 °C.

Selection of tail fractions of impurities contained in the feedstock. This does not imply changing the column settings, but only replacing the receiving tank. The selection of tail fractions is completed when the steam temperature in the condenser reaches about 82-85 °C.

After finishing work, turn off the heater of the evaporation tank (button BK1). After the column has cooled, stop supplying water to the condenser and heat exchanger. Switch off the measurement system and digital measuring instruments on front panel installations.

Disconnect the unit from the electrical network.

After draining the bottom residue and cleaning the evaporation tank, return the installation to its original state.

Process the received data and enter its results in Table 1.

Determine the number of theoretical plates of the distillation column and compare the total height of 3 drawers with the result obtained.

Answer control questions and draw independent conclusions about the work performed.

Slowly changing process parameters

Flow rate of water cooling the heat exchanger and reflux condenser ___ l/s

Temperature of water entering the heat exchanger ___ 0 WITH

Water temperature at the heat exchanger outlet ___ 0 WITH

Temperature of water entering the reflux condenser ___ 0 WITH

Water temperature at the outlet of the reflux condenser ___ 0 WITH

Table 1. Results of measurements and calculations.

Name of parameters and units of measurement

Current values ​​of monitored parameters

Average value

1. Heating the feedstock to boiling point

Heating time until liquid begins to boil, min

Temperature of the initial mixture after heating, 0 C,

Temperature of steam and reflux in the condenser, kPa

2. Initial period of rectification. Selection of head fractions

Pressure of the vapor-gas mixture at the inlet of the column, kPa

Electric Energy, released by the heater, number of counter pulses

3. The main period of rectification of ethyl alcohol

Evaporation time of low-boiling fractions, min

Liquid boiling point, °C

Temperature of steam and reflux in the column, kPa

Steam temperature in the condenser, kPa

Pressure of the vapor-gas mixture at the inlet of the column, kPa

Pressure of the distillate column in a hydrostatic density meter, kPa

Consumption of sampled distillate, number of drops per 20 seconds

Electrical energy released by the heater, number of counter pulses

4. The final period of rectification. Selection of tailing fractions

Evaporation time of low-boiling fractions, min

Liquid boiling point, °C

Temperature of steam and reflux in the column, kPa

Steam temperature in the condenser, kPa

Pressure of the vapor-gas mixture at the inlet of the column, kPa

Pressure of the distillate column in a hydrostatic density meter, kPa

Consumption of sampled distillate, number of drops per 20 seconds

Electrical energy released by the heater, number of counter pulses

Bottoms concentration X w , %

Distillate concentration X w, %

Processing of experimental data

For the average values ​​of the parameters of the main stage of rectification, the molar concentrations of alcohol in the initial mixture X are calculated by volume F and distillate X p . Recalculate the consumption of the original mixtureFand distillate R in moles. From the material balance equations of the column, the flow rate and concentration of the bottom residue are found using the equations

W= F – P, X w =(FX F – PX p )/ W,

Where F, P, W-consumption of the initial mixture, distillate, bottoms, kmol/s;

X f . X p . X w -compositions of the initial mixture, distillate, bottoms, mol. shares.

Determine the reflux ratioR– ratio of reflux flow to distillate flow and calculate the amount of steamG, climbing the column. Knowing the magnitudeGand column diameter (D at = 20 mm), determine the steam velocity in the free section of the column w. The steam velocity in the column can also be calculated by determining the amount of steam from the equation heat balance reflux condenser (this calculation can be used as a test calculation).

Based on reference data, an equilibrium curve is drawn on graph paper.y= f(x) on y-x diagram(Figure 5) and mark on the x-axis the concentration values ​​of the initial mixture X

f– the ratio of the consumption of the initial mixture to the consumption of the distillate.

Calculate the segment , which is cut off by the working line of the top of the column on the ordinate axis (Figure 6). Through point A (x p = y p ) and the resulting segment draw the working line of the upper part of the column. Through point D (x w= y w ) and point C draw the working line of the bottom of the column. Between the equilibrium and operating lines, steps of concentration changes are constructed (Figure 6). Each stage corresponds to one theoretical plate. Having determined the number of theoretical stepsn T , and, knowing the number of real plates in the columnn, find the average efficiency of the plate using the equation

The efficiency of the plate depends on the hydrodynamic conditions and physical and chemical properties steam and liquid.

When the column operates on its own, the distillate is not selected, i.e. reflux ratio is infinity . In this case, the working line of the column coincides with the diagonal.

Control questions

What process of separating substances is called rectification? What differences are used? physical properties separated substances?

Which mixtures are called azeotropic or continuous boiling mixtures? Why can't they be separated using rectification?

Why does the standard set the concentration of rectified alcohol equal to %. What additional requirements apply to this product?

How is a distillation column constructed? What devices are used in it as elements to increase the contact interaction of the phases moving in the column?

What causes flooding of the distillation column? How can it be detected and prevented?

How does a distillation column work when the reflux ratio is zero? How does the degree of purification and concentration of the resulting ethyl alcohol change?

Which of the substances contained in alcohol-containing raw materials are considered low- or low-boiling: aldehydes, acetones, heavy alcohols, methyl alcohol, fusel oils? Which of them are distilled immediately after the release of rectified alcohol?

Why does the selection of food alcohol end when its vapor temperature reaches 0.1 higher and not lower than 78.3 ° C?

Literature

Bogdanov Yu.P., Zotov V.N., Koloskov S.P. etc. Handbook on alcohol production. Equipment, means of mechanization and automation. - M: Light and food industry, 1983, 343 pp.

Devyatykh G.G., Elliev Yu.E. Introduction to Theory deep cleaning substances. – M. Nauka, 1981. – 320 p.

Main condition safe operation distillation columns is to ensure their tightness. The reason for the violation of the tightness of the columns may be an increase in pressure in the apparatus above acceptable standards, corrosion and erosion of the body, various mechanical damage. An increase in pressure can occur when the column is overloaded with the mixture being separated, the temperature in the column bottom increases, or holes in the distribution devices.[ ...]

To prevent an increase in pressure in the column, carefully control the quantity and composition of the mixture being separated, and the temperature along the height of the apparatus. In this case, the temperature of the top of the column is maintained by a regulator that changes the irrigation supply. In order to avoid “flooding” of the column when the product flow rate increases, it is necessary to ensure that the cap plates are installed strictly horizontally, and the number and diameter of overflow devices on the plates correspond to the performance of the apparatus. To eliminate the possibility of gas breakthrough into the column, the pipe of the lower plate is lowered below the liquid level in the column cube.[...]

The operation of sieve trays requires special attention, as they are easily clogged with sediments, such as resins, formed during the processing process. [...]

In case of excessive pressure increase, the columns are equipped with a protective automatic blocking system, check valves on the supply line of raw materials and reagents and safety valves that release excess vapor to the flare. In this case, fire arresters are installed on the outlet lines coming from the safety valves.[...]

A sharp increase in pressure in the column when water gets into it is very dangerous. The boiling of water in the column causes such a rapid increase in pressure that the safety valves do not have time to operate, and the apparatus may rupture. To prevent water from entering the distillation column, it is necessary to: ensure that the raw materials and irrigation do not contain water; before supplying hot water steam to the cube of the column, it is necessary to completely remove condensate from the supply steam line; periodically check for cracks and damage on the tubes of the column cube heater and in the irrigation refrigerators.[...]

A major danger is posed by leakage of columns operating under vacuum. In this case, air is sucked into the column, and an explosive mixture is formed directly in the apparatus itself. Increased requirements are placed on the tightness of vacuum columns; in particular, they are used flange connections type “tenon and groove”, the sucked vapors are analyzed for oxygen content, vacuum extinguishing is provided with the help of inert gases (nitrogen).[...]

The safety of operation of vacuum columns is largely determined by the completeness of condensation of petroleum product vapors sucked out with air. Condensation of petroleum vapors usually occurs in a barometric condenser. When condensation is incomplete, some of the products enter the sewer system through ejection devices, and when dry mechanical vacuum pumps are used, they are released into the atmosphere, polluting it. Therefore, emissions from vacuum pumps, as well as water discharged into the sewer system from barometric condensers, are subject to preliminary purification.[...]

For free flow of water through the barometric pipe of a barometric condenser, its height must be at least 10.5-11 m, then the weight of the water in the pipe completely balances the force of atmospheric pressure, and the water freely drains into a well equipped with a hydraulic seal. The hydraulic seal, which usually has a height of 0.6-0.8 m, eliminates the danger of air being sucked into the column through the barometric pipe. The flow of water into the barometric condenser is regulated so that the water drained through the drain pipe into the well has a temperature of no more than 30-35 ° C and does not contain petroleum products. When water consumption increases, it does not have time to go into the well, its level rises, and the water fills bottom part capacitor, disrupting its operation. In addition, through the helmet pipe, water can get onto the upper plates of the distillation column and disrupt its mode.[...]

When the product enters the column, abrasion of its walls occurs. Therefore, at the point where the product is introduced, a protective “snail” is installed, replaceable as it is destroyed, directing the flow to the center of the column in a spiral.[...]

Distillation columns have significant weight on a relatively small supporting surface, so they are installed on massive ring supports equipped with stiffeners and connected to the foundation anchor bolts. For repair work inside the column it is equipped with manhole hatches with a diameter of at least 0.45 m. For ease of work, one hatch is installed for every 4-5 trays. To make it easier to open hatch covers and prevent the possibility of them falling from a height, hatch covers are arranged on hinges (hinges).[...]

Similar chapters in other documents:

Complex distillation columns.

If the original raw material mixture needs to be divided into several components or fractions, then several simple columns connected in series must be used.

Technology system turns out to be quite cumbersome, and the installation is metal-intensive. Therefore, to separate a multicomponent mixture, it is advisable to use complex distillation columns. They are plate-shaped devices that work in conjunction with a stripping column. The stripping section consists of small-diameter columns, installed one on top of the other and combined in a common housing. Stripping columns, as well as the main columns, are equipped with plates. In addition to the top and bottom product, a number of side fractions (shoulder straps) are selected along the height of the column. These fractions are sent to the appropriate section of the stripping column, where they are divided into two parts. The upper product, in this case, is returned to the main column as a side reflux, the lower product is the target side fraction. The use of strippers allows you to select several fractions along the height of the column, which are target along with the upper and lower product leaving the distillation column. Columns of this type are widely used in oil refining to obtain fuel fractions from oil. The design may vary depending on the target products.

Main operational parameters are pressure and temperature. Pressure is directly proportional to temperature and an increase in pressure will be associated with an increase in temperature in the column. To prevent an emergency basic situation for column apparatus

(Depressurization with explosion) it is necessary to maintain the temperature regime in the column to avoid pressure build-up. Temperature conditions are maintained in accordance with standards technological mode, which are marked in technological regulations. Maintaining the necessary temperature regime is provided by heating the column cube and removing heat from the upper part of the column. You can vary the temperature of the top and bottom by changing the amount and temperature of the corresponding flows. For supporting required temperature In the column, the apparatus is covered with a layer of thermal insulation. Thermally insulating material must have low thermal conductivity and must be resistant to high temperatures environment and resistant to vibrations environment and should not be destroyed during operation. The material should not be hygroscopic to prevent the possibility of corrosion of the housing wall. The thickness of the insulation layer is calculated depending on the temperature of the environment and properties insulating material. When carrying out repairs thermal insulation inspected for damage. These could be cracks, chips, ruptures of insulation elements, etc. Most often, insulation damage occurs at the installation site of fittings, hatches, brackets, and platforms. Defects found during repairs must be eliminated. At least once a quarter it is necessary to take temperature measurements at outer surface isolation. If the temperature is below the permissible level, then it is necessary to major renovation isolation.

Theoretical foundations of distillation and rectification

Distillation- This the process of separating homogeneous mixtures of liquids based on their volatility. Volatile liquids are those whose saturated vapor pressure differs significantly from zero at ordinary temperatures.

The theory of distillation is based on the idea of ​​liquid solutions and the formation of a mixture of vapors above them. When mixtures of volatile substances boil, vapors of liquids become enriched in the more volatile component. When such vapors partially condense, they are separated into a vapor phase and a liquid (reflux). At the distillation temperature, the more volatile liquid boils, and the less volatile liquid evaporates without boiling. Such mixtures are called separate-boiling mixtures. IN ideal solutions This situation is realized at any concentration.

In nonideal solutions, there are concentration regions in which both components of a binary mixture boil simultaneously. These are the so-called azeotropic regions or regions of nonseparately boiling liquids. Here, the concentrations of the liquid and vapor phases of binary mixtures are the same, and therefore, during their distillation, it is impossible to increase the concentration of the liquid phase.

Difficult distillation , orrectification - This is multiple distillation of the distillate. Used to improve the efficiency of simple distillation. It is carried out in plate or packed columns. To successfully separate the reflux flowing down the column and the steam moving upward, you can use any contact elements that increase the area and efficiency of their interaction.As contact elements in large distillation columns plates are usually used. Each such plate located in the column is called a physical plate (PT).