RU2316384C2 - Method and device for catching and recuperating vapors of hydrocarbons - Google Patents

Abstract

FIELD: environmental protection.

SUBSTANCE: method comprises supplying vapor-gas mixture to absorber (1) through pipeline (39). The absorber is inclined to the absorbent drain. The absorbent is supplied from pipeline (31) to absorber (1) by means of pump (34). The fraction of low-boiling vapors is absorbed when the gas-vapor mixture flows through slot spaces between disks (7) in sections (4) of absorber (1) with subsequent removing cleaned gas and absorbent from it. One part of saturated absorbent flows through pipeline (17), filter (21), heat exchanging condenser (16), collector (22), float valve (23), controlled valve (24), heater (25) and enters three-five sections of sorption unit (2), and the other unheated part enters the first section. The cleaned absorbent enters collecting vessel (8). After cooling the cleaned absorbent flows through pipeline (31), filter (33), pump (34), check valve (35), and controlled valve (36) and is returned to absorber (1).

EFFECT: reduced environment contamination.

12 cl, 3 dwg, 4 ex

Description

The invention relates to processes and apparatuses of the chemical and oil refining industries, transportation systems, storage, transshipment and sale of petroleum products, pharmaceutical and food industries, as well as environmental environmental protection systems, and allows by collecting harmful, toxic and useful fumes from gas-vapor mixtures, and hydrocarbon vapor (HC) from the air-vapor mixture (PVA), significantly reduce atmospheric pollution, return (recuperate) valuable products to the process.

This invention can be widely used in oil refineries, oil depots, automobile, railway and offshore overpasses for the loading and unloading of petroleum products, including gas stations during storage and refueling of vehicles, as well as for collecting and recovering solvent vapors, low boiling components in the chemical and petrochemical industry, paint and varnish production, food and medical industries, etc.

So, the air-vapor mixture evaporating from oil storage tanks at oil refineries, oil depots, or on oil loading and unloading racks during filling-emptying operations of various kinds of containers contains air and a significant amount of vaporous hydrocarbons (a wide fraction of hydrocarbons - BFLH) - approximately 15 to 85 vol.% - up to 1.5 kg in 1 m ^{3 of} PVA, which when released into the atmosphere leads to both significant environmental pollution, an increase in chronic diseases of the population, and to loss marketable petroleum products, in particular light fractions of gasoline, kerosene, etc. (while reducing the quality of the oil products themselves). Therefore, the air-vapor mixture must be cleaned of atmospheric polluting vapors before returning to the atmosphere (with the return of the latter to the storage tank or special storage devices), which will reduce the loss of marketable petroleum products or catch harmful substances while preventing environmental pollution. Similar problems exist in other industries - chemical, petrochemical, food, medical, perfumery and others, where they work with boiling (volatile) fractions.

A number of known methods for capturing vaporous components from gas mixtures, for example, hydrocarbon vapors from a steam-air mixture, which have found practical application:

1. The method according to Pat. RU No. 2100689, M.cl. F17C 3/00 consists in trapping hydrocarbon vapors with a liquid sorbent, which is used as part of the liquid petroleum products that are taken from the bottom of the tank, cooled and returned to the top of the tank, irrigating in countercurrent hydrocarbon vapor. This method is quite simple, but extremely energy-intensive, has a low absorption capacity due to the small surface of the contact phases, is ineffective and can only be used in the treatment of steam-air mixtures with a low concentration of volatile components (low-boiling hydrocarbon fractions). In this connection, this method is used extremely rarely and only for short-term (up to 1-3 days) storage of oil directly at the production sites (mainly in the northern regions), since the absorbent (oil) is saturated quite quickly with trapped light hydrocarbons up to equilibrium state and, accordingly, termination of the absorption process, i.e. the need for almost continuous pumping of oil for its further processing is obvious, while the non-trapped hydrocarbon vapors are diverted to the associated gas collector for their further utilization.

2. A method for utilizing gasoline vapors (see the PR1-SEAD process in the journal ErdI, Erdgas, Kohle, Volume 108, No. 2, p. 81) includes two-stage adsorption of vapor on activated carbon, coal regeneration by the action of vacuum (while heating adsorbent) and (or) by blowing with heated air, absorption of hydrocarbons extracted from coal (at their high concentration) directly with gasoline from the tank.

This method, which ensures the utilization of vapors from tanks, allows to achieve a high degree of purification, but it is extremely complicated and cumbersome, because involves a multi-stage sequence of technological operations leading to the presence in the installation for its implementation of metal-consuming, large-sized adsorption and absorption blocks, a complex hardware-technological stage of desorption, a control system, etc. A significant drawback of the method, in view of the periodicity of the process, is the need to introduce backup adsorption blocks when long continuous operation, which is caused by the need for their successive sequential regeneration with periodic A new replacement for the adsorbent activated carbon in them.

3. Methods of purification of hydrocarbons from a gas-vapor mixture (see US Pat. RU No. 2035365, M.cl. B65D 90/30, 05.20.1995; auth. St. SU No. 1512870, M.cl. B65D 90/30, 10/07/1989 ; Pat. RU No. 2193443, Mcl B65D 90/30, 10.29.2001), based on the forced pumping of the PVA by an ejector (liquid-gas-jet) pump through a separator into a vertical absorption column. The liquid phase from the separator tank through the cooling coil exits to the pump inlet with the formation of a liquid medium circulation circuit (absorbent) through the ejector pump. In a vertical absorption column, hydrocarbon vapors are absorbed by cooled liquid kerosene (in countercurrent mode), which is discharged into a spent absorbent tank. From the separator tank, a part of the saturated absorbent by the second pump is directed through the heating heat exchanger to the stripper (consisting of a vertical distillation column, boiler and condenser cooler), in which the trapped hydrocarbon vapors are separated from kerosene, while the purified kerosene is returned through the absorbent heating and cooling coils to the absorber for reuse in a new cycle, and the condensate of light gasoline fractions (regenerated hydrocarbon vapors) from refrigerators and the capacitor is partially removed in a distillation column, is derived partly into the container with gasoline.

Although these methods are much simpler than adsorption methods, a number of problems arise in them, the first of which is the significant gasdynamic resistance of the gas paths of the absorption columns, associated with the difficulty of organizing an intense and uniform heat and mass transfer process during the absorption of volatile components, the difficulty of cleaning the vapor-air mixture from the droplet phase with with a particle diameter of 3-15 microns formed after the ejector, which in aggregate does not always allow achieving the required degree of purification of the vapor-air mixture from hydrocarbons while satisfying the criterion of efficiency-cost. In addition, jet ejection pumps for the flow rates under consideration have significant dimensions at low efficiency, which, combined with the complexity of the hardware design of the technological processes of the circuits under consideration, in the form of gas-jet devices, separators, vertical absorption and distillation columns, etc. - makes installations for their implementation cumbersome (especially in height), metal-intensive and difficult to operate at large temperature differences (summer-winter) and, ultimately, expensive and unprofitable even for large volumes of transshipment of petroleum products, not to mention the relatively small emissions of steam and air mixtures.

4. Methods of purification of hydrocarbons from the vapor-air mixture (see US Pat. No. 4475928, M.cl. B01D 53/14, 1984; Pat. RU No. 2155631, M.cl. B01D 53/14, 05/06/1996; Pat. RU No. 2088298, Mcl B01D 5/00, B01D 90/30, 03/23/1995) include the absorption of hydrocarbon vapors by chilled kerosene, followed by regeneration of kerosene by heating and absorption of vapors extracted from kerosene by gasoline.

These methods, when using kerosene as an absorbent (far from an optimal absorbent), provide a hydrocarbon capture rate of less than 85%, which is unsatisfactory in most cases, especially at low concentrations of the captured component in the mixture. In addition, to ensure the indicated efficiency of the absorption process, it is necessary to cool kerosene to a temperature of -10 ÷ -20 ° C, which requires high energy costs. To reduce energy costs during the implementation of absorption methods and to reduce the consumption of the absorbent used - kerosene, these methods use additional operations and devices that provide either preliminary air sampling from the air-vapor mixture, for example, using membranes, which leads to an increase in the concentration of hydrocarbons in the PVA supplied into the absorber, or the compression of the vapor-air mixture in the compressor to P _a = 0.3-0.6 MPa, which at low hydrocarbon concentrations is safe only when using "wet "compressors with limited compression and, as a rule, having either low efficiency or problems due to the selection of lubricating oils compatible with PVA.

However, in practice, an increase in pressure in the absorption column leads to a significant increase in energy consumption for compressing large PVA costs, i.e. increase compressor power and total energy costs for the implementation of the process (3-5 times). In this case, the compression of PVA to pressures of (0.5-0.8) MPa with a hydrocarbon concentration in the range from 0.8 to 17 vol.% Can lead to ignition or even explosion of PVA, which requires guaranteed operation of the plants on “rich” mixtures (with a hydrocarbon concentration of more than 17%, which is possible only if the oxygen in the “air” is replaced with an inert gas), or the use of predominantly wet compression technologies with the enrichment of PVA, which further complicates the process of trapping and recovering BFLH. In addition, increasing the working pressure in the system requires more complex and expensive measures to ensure the safe operation of such systems, leading to more complicated installations, an increase in the metal consumption and dimensions of the installations, and, as a consequence, an increase in their cost.

In addition, the use of kerosene as an absorbent limits the scope of these methods for production with large volumes and the range of produced and stored petroleum products, such as oil refineries (refineries) and oil depots (NB), where kerosene is always available. At gas stations, where, as a rule, only gasoline and diesel fuel (DT) are stored from petroleum products, the construction of additional containers for storing kerosene is required.

Known installations for capturing hydrocarbon vapors from a steam-air mixture, designed, to one degree or another, for the implementation of the above objectives in paragraphs 3, 4 of the methods - see autosweet. SU No. 1512870, M.cl. B65D 90/30, 10/07/1989; patents RU No. 2193443, M.cl. B01D 53/72, B65D 90/30, 10.29.2001; RU No. 2106903, M.cl. B01D 53/14, B01D 53/75, 04/20/1993; RU No. 2050170, M.cl. B01D 19/00, 11/27/1992; RU No. 2080159, M.cl. B01D 53/14, B01D 53/80, 07/12/1993.

Common to all of the above methods and installations is the implementation of the process of trapping hydrocarbon vapors from an air-vapor mixture by absorption, followed by desorption of the absorbent using for this purpose a wide range of vertical (but extremely bulky) heat and mass transfer devices (columns).

Based on the materials presented in the applications, the plants using these methods should provide a solution to the problem of efficiently trapping hydrocarbon vapors from a steam-air mixture. However, in practice, these methods in a known hardware design (based on classic vertical disk and packed columns) cannot provide the declared performance characteristics due to the peculiarities of their operation at low temperatures in off-design conditions, and therefore they are mainly used in secondary (desorption) circuits of adsorption plants or operate at substantially softer modes, as a rule, only at positive temperatures of the absorbent due to icing of the contact zones of the plants and negative temperatures, which reduces the efficiency of hydrocarbon vapor capture and limits the scope of their use only for rough cleaning of PVA (up to 75 vol.% gasoline vapor or up to 65 vol.% oil vapor is captured, which is unacceptably small).

The main disadvantages of vertical absorption devices are:

- high hydraulic resistance along the working paths, which almost always leads to the need to use "oversized" or "trimmed" columns in height, or equip the units with compressors for forced injection of PVA, capable of initiating ignition of the mixture and reducing the safety of the process;

- a significant variation in the intensity of processes in the working area of packed and plate-type column apparatuses, the formation of bypass effects, droplet emissions, which leads to the need for soothing and separation chambers, regular nozzles and, as a consequence, an increase in the size and cost of the plants.

Such devices and, accordingly, installations equipped with them can be installed only at large refineries, oil depots and oil transshipment complexes with sufficient space for their placement. Such installations can pay off only when operating in continuous modes with large volumes of transshipment and storage of petroleum products.

In some cases, in order to increase the completeness of hydrocarbon capture from PVA, the plants are equipped with additional devices at the outlet — adsorption units (see US Pat. RU No. 2106903, No. 2050170, etc.), or blocks of hydrocarbon oxidation catalysts before exiting the dispersion plugs (see Pat. No. 2080159). The latter method requires appropriate justification (and thorough experimental testing) due to the fact that the concentration of the vapor-air mixture supplied to the blocks of hydrocarbon oxidation catalysts is almost always in the explosive range (0.8-5 vol.% Based on hydrocarbon concentration). The latter circumstance either completely excludes the possibility of using open high-temperature systems in combination with collector piping and traditional fire arresters (penetrated by detonation and deflagration combustion), or requires the introduction of fire arresters capable of containing the spread of detonation and deflagration combustion.

In total, the practical implementation of all the above methods in the proposed hardware design is extremely difficult, mainly due to the cumbersomeness of the vertical absorption and desorption columns used in them and the complex set of fire protection measures at the input and output devices.

The known method (patent RU No. 2088298, Mcl B01D 5/00, B65D 90/30, 03/23/1995), comprising supplying a steam-air mixture with subsequent absorption of hydrocarbon vapors from it by a cooled liquid absorbent and air outlet from the process, and installation ( patent RU No. 2050170, Mcl B01D 19/00, 11.27.1992), containing an absorber, a refrigeration machine, heat exchangers, a pump, connecting supply and exhaust pipelines of absorbent, air-vapor mixture and purified air, automation equipment, including valves, sensors, valves, and an automatic control unit for its operation.

Closest to the proposed method is a method for trapping vapors of low boiling substances from hydrocarbons described in JP application No. 2268808 (CL B01D 53/14, 02.11.1990)), in which the steam-air mixture is supplied to the absorber, followed by absorption of the vapors of low boiling hydrocarbons by a liquid absorbent the withdrawal of purified air and absorbent and the supply of absorbent saturated with hydrocarbons in the stripper.

The obvious advantages of this method is a more rational construction of the process of trapping vapors of boiling substances. However, as in the previously considered methods, relying on the classical hardware design and the incompleteness of its construction, from the point of view of minimizing the energy costs of its implementation, does not allow to transfer it to the cost-effective class while maintaining a number of disadvantages characteristic of the previously considered methods.

The problem to which the present invention is directed, is to create a process for capturing and recovering vapors of low boiling substances (LP), for example low boiling hydrocarbons, alcohols, esters, ammonia and others from gas-vapor mixtures, while excluding external absorbent cooling systems and high-temperature modes of absorbent desorption, the implementation of auto-adjustability of these processes directly during their implementation in a closed cycle while simplifying the hardware design of the process, reducing energy consumption, size and mass characteristics of installations for its implementation, the cost of their manufacture and operation, i.e. improving the efficiency, safety and auto-regulation of the process, autonomy and efficiency.

This problem is solved due to the fact that in the method of trapping vapors of low boiling substances (LP) from vapor-gas mixtures (ASG), for example, low-boiling hydrocarbons from vapor-air mixtures (PVA), which includes supplying a vapor-gas mixture to an absorber, followed by absorption of vapor of low-boiling substances from it with a liquid absorbent , the removal of purified gas from the absorber and the supply of saturated drug absorbent to the stripper, according to the invention, a horizontal disk heat and mass transfer apparatus is used as an absorber, a high boil is used as an absorbent other substances that are fed into the absorber towards the vapor-gas mixture, pass them sequentially and countercurrently to the ASG movement along the slit gaps between the contact disks, thereby interacting the gas-vapor mixture with the surface of the liquid absorbent film continuously forming on the surface of the rotating contact disks, the amount of absorbent being proportional to the flow rate ASG based on the achievement of a concentration close to the equilibrium of at least one of the low-boiling substances in the absorbent, while sorption of the absorbent is carried out at a pressure significantly lower than atmospheric - in the range from 0.005 to 0.05 MPa, at an average temperature of the absorbent above the boiling point of the main desorbed boiling substances at a given pressure in the countercurrent mode of the absorbent and vapor phase by evaporation of low boiling substances, simultaneously performing the function of refrigerants from a film of high-boiling absorbent formed on rotating disks saturated with low-boiling substances while cooling it due to the removal of its own the thermal energy of the absorbent for the evaporation of low-boiling substances, while the vapor phase removed from the stripper is cooled by a counter unheated absorbent stream to the condensation temperature of the high-boiling absorbent vapor, the pairs of fractions of low-boiling substances removed from the stripper are compressed and condensed at a pressure above atmospheric while cooling them in heat exchange the liquid absorbent flowing from the absorber, the condensate of low boiling fractions formed remove their process, and the purified cooled absorbent directs They are fed back into the absorber to carry out the absorption process.

In order to ensure a high degree of capture of low-boiling gasoline vapors forming a wide fraction of low-boiling hydrocarbons (BFLH), increase the efficiency of the process cycle and process efficiency, universality, availability and ease of implementation of the process, including the “cost-effectiveness” criterion, the absorbent is used for example, diesel fuel, which is supplied to the absorber at a temperature of from +5 to -5 ° C based on 5 to 20 liters of absorbent per m ^{3 of} PVA, the flow rate of the vapor-air mixture and the absorbent of the relative the surface of the contact disks is not more than 3 m / s, the residence time of the vapor-air mixture in the contact zone is not less than 1.2-1.7 seconds and the rotation speed of the contact disks is from 10 rpm to 100 rpm, while the ratio of the flow of vapor-air mixture (V, ^m3 / h) to the surface of the contact disc (S, m ²⁾ less than or equal to 2.5.

In order to increase the degree of cooling of the absorbent with an increase in the efficiency of the operating cycle of the process, it is advisable to throttle the condensate of low-boiling substances formed upon cooling to a pressure lower than critical for one or part of low-boiling substances with boiling at constant pressure and lowering its temperature, while the heat required for boiling of low-boiling substances , divert from the purified absorbent, thereby providing its additional cooling, the resulting vapor portion of boiling substances, for example when entering stationary mode, they enter the PVA in the absorber, and in stationary mode they are throttled into a stripper equipped with a vacuum pump-compressor, and the remaining condensate of low-boiling substances is removed from the process.

In order to minimize energy costs for the implementation of the process while increasing the efficiency of the working cycle, it is advisable to reduce the pressure in the stripper to 0.005-0.05 MPa during the operation of the liquid ring vacuum pump.

In order to minimize energy costs for the implementation of the process while increasing the efficiency of the working cycle, it is advisable to use the absorbent involved in the process as the working fluid for the liquid ring vacuum pump.

In order to minimize energy costs for the implementation of the process while increasing the efficiency of the duty cycle, it is advisable to partially heat the absorbent during its flow through the liquid ring vacuum pump during its operation.

In order to minimize energy costs for the implementation of the process while increasing the efficiency of the working cycle, it is advisable to set the temperature of the absorbent heating on the basis that the average temperature of the cold and heated absorbent streams entering the stripper should not be lower than the boiling point of the main, highest boiling point desorbed substances at a given pressure while the temperature of the cold part of the absorbent supplied to the stripper should be lower than the boiling point of the highest boiling point of the desorbed substances fraction taking into account the heating of the absorbent from condensation on the contact disks of the desorber vapors with a high boiling point that are part of the absorbent.

As an example, No. 1. Since the proposed process for trapping vapors of low-boiling substances, such as vapors of a wide fraction of low-boiling hydrocarbons (BFLH) from PVA, is based on the principle of absorption by high-boiling (compared to absorbable substances) absorbents, it is possible to use petroleum oil, kerosene or diesel fuel, the boiling point of which is more than + 170- + 180 ° С. The use of summer diesel fuel as an absorbent is advisable for the following reasons: its wide availability at oil transshipment bases and gas stations; its stability, high boiling point (≥180 ° С, which is more than 140 ° С higher than the boiling temperature of the main trapped components), low viscosity at this absorption temperature, and the initial absence of low-boiling gasoline fractions in it.

(At petrol stations and petrol stations where there is no diesel fuel, it is advisable to use petroleum oil as an absorbent).

The use of DT (as well as petroleum oil and kerosene) as an absorbent during the process in GDTMOA provides high heat and mass transfer coefficients (at a given temperature) due to the greater specific density, thickness, uniformity and sufficient mobility of the absorbent film on rotating disks (due to acceptable viscosity) and, therefore, the organization of an effective absorption process. The main advantage of diesel fuel, petroleum oil and kerosene is their high solubility (up to equilibrium concentration) of BFLH at a temperature of -5- + 5 ° С, which is:

- for the amount of propane-butane - up to 3.5%; - for the sum ΣС ₅ ... and ΣС ₆ ... - up to 40-65%.

Given the relatively low percentage of propane content (C ₃ H ₈ ) in the PVA of gasoline - not more than 1.5% and the relatively high value of the equilibrium constant, makes the complete extraction of this component from PVA economically impractical. For propane, the ratio of the mass flow rates of the absorbent and PVA is 20 ... 50 at the temperature of the diesel fuel in the temperature range - 20 ÷ 0 ° С, i.e. it is logical to limit the degree of hydrocarbon recovery from PVA to 97 ... 98% (at T≈0 ° C), refusing to completely capture propane, but at the same time drastically reduce the consumption of absorbent material, significantly reduce the dimensions of the absorber, and reduce the energy consumption of the unit and its cost.

For butane, the ratio of the mass flow rates of absorbent and PVA is 10 ... 20, for pentanes - 3 ÷ 5. With this ratio of the mass flow rates of the absorbent and PVA, with the appropriate selection of temperature and the proper organization of the absorption process itself, the degree of absorption of hydrocarbons, starting with butane, can be arbitrarily high.

Thus, although the “critical” component of NGL in PVA gasoline is propane, the degree of absorption of which determines mainly the degree of absorption of NGL and which is the most difficult to absorb from gasoline vapors (excluding, respectively, methane and ethane, which are not present in PVA gasoline ), but given its low concentration of ≤1.5%, butane should be taken as a critical component, the concentration of which in PVA can reach 55% of the total hydrocarbon vapor.

The ability of an absorbent to absorb (absorb) NGL substantially depends on the temperature of the absorbent (on the equilibrium concentration at a given temperature). So, at T _DT = + 20 ° С and an absorbent flow rate of 10 l / m ³ _PVA, the capture of BFLH is less than 65% (the concentration of BFLH in purified PVA is up to 7 ÷ 12%, which is unacceptable), then at T _DT = 0 ÷ -3 ° С - completeness of capture of BFLH is ≥93% (up to 98%), and the concentration of BFLH in purified PVA is already ~ 1.5 ÷ 0.5%. The need for cooling the absorbent is obvious.

Since in this process low-boiling substances, for example vapors of low-boiling hydrocarbons, can also be considered as refrigerants (refrigerants), in this process (absorption - desorption of low-boiling substances), in order to increase its efficiency, it is rational to use the principle of constructing the process underlying the work of refrigeration absorption plants based on the use of the properties of mixtures consisting of components that differ sharply at boiling points at the same pressure (including hydrocarbons).

The low-boiling hydrocarbons that make up the PVA gasolines (at P = 0.1 MPa) are:

C ₃ H ₈ T _bales = -40 ° C;

C ₄ H ₁₀ T _bales = -1 ° C;

ΣC ₅ H ₁₂ T _bales ≤ + 36 ° C;

ΣС ₆ Н ₁₄ Т _bales ≤ + 69 ° С;

which have a significantly lower boiling point than an absorbent, for example diesel fuel (T _bale ≥ + 180 ° C). The concentration of hydrocarbon vapor C ₇ H _{16 ...} and C ₈ H _{18 ...} included in the composition of PVA gasolines is insignificant (less than 1%). The boiling point of C ₇ H _{16 ...} and C ₈ H _{18 ... is} lower or equal to + 98 ° С and + 126 ° С, respectively, they are well absorbed, but because of their high boiling point, they can be used as refrigerants do not take into account.

When absorption of BFLH (refrigerants) to an equilibrium concentration, the temperature of the absorbent rises.

During the subsequent evacuation of the absorbent (at 0.01 MPa), the vapor pressure of NGL in the absorbent significantly exceeds the equilibrium pressure, they evaporate at a significantly lower temperature with the selection of the (intrinsic) heat of the absorbent and its cooling. The vapor phase of the low-boiling hydrocarbon fraction from the vacuum pump under an overpressure of more than 0.16-0.3 MPa is directed to a heat exchanger (condenser), where it is cooled by a cold absorbent flowing from the absorption block and condenses, releasing heat Q _K , The condensate formed of the refrigerant is then It passes through the choke (adjustable gate) where boiling is throttled to the pressure (p ₂ <p ₁₎ and a further heat exchanger THEN _x, where partly boils and reduces its temperature to T _h. The resulting vapor-liquid mixture is sent to the refrigeration tank E1, built into the tank with a clean absorbent. In the TO _x heat exchanger and E1 tank (evaporators), the refrigerant, taking the heat from the cooled absorbent, partially boils off at a constant pressure p ₂ , in a temperature range that depends on the composition and ratio of low-boiling hydrocarbons (LU). The remaining condensate of low-boiling hydrocarbons is discharged to the accumulator, and the vapor phase of the LU is returned to the absorber (at the moment of the first start-up of the installation) or to the stripper with expansion to P = 0.01 MPa and additional cooling of the absorbent.

The high equilibrium concentration of low-boiling hydrocarbons in diesel fuel (taking into account the distribution of LN in PVA) allows us to bring their actual content in the absorbent - diesel fuel to 5% -10% or more, i.e. Σ (C _{3 ...} -C _{6 ...} ) up to 80-200 g or more in 1 liter of diesel fuel, thereby ensuring, on the one hand, the minimum consumption of absorbent per 1 m ^{3 of} PVA, on the other hand, a sufficient concentration of NGL in the absorbent for their effective use as refrigerants, providing cooling of the absorbent in the process of vacuum distillation of BFLH.

So, with an average content of low-boiling hydrocarbons in gasoline vapors (in 1 m ³ PVA) from ~ 500 to 1000 g / m ³ _PVA (in which, depending on the type and composition of gasoline, it contains: - С ₃ Н ₈ ≤1.5 %; ΣC ₄ H ₁₀ ≤55%; ΣC ₅ H ₁₂ ≤45%; ΣС ₆ Н ₁₄ ... ≤3%) at a flow rate of ~ 7 liters of diesel fuel (absorbent) per 1 m ^{3 of} PVA at a temperature of + 5--5 ° С the equilibrium concentration of Σ (С ₃ Н ₈ + С ₄ Н ₁₀ ) in the absorbent can be up to 3.5%, and the concentration of ΣC ₅ H ₁₂ + ΣC ₆ H _{14 is} more than 13% (theoretically, the equilibrium concentration Σ (С ₆ Н ₁₂ + С ₆ Н ₁₄ and higher) at an absorption temperature of + 3 ÷ -5 ° С it is 40 ÷ 65%). At the desorption temperature T _des = + 18- + 25 ° С and Р = 0.01 MPa) the equilibrium concentration Σ (С ₃ Н ₈ + С ₄ Н ₁₀ ) will be close to zero, and a ΣC ₅ H ₁₂ + ΣС ₆ Н ₁₄ less than 1 ÷ 5%, i.e. distillation (evaporation) of almost the entire amount of trapped low-boiling hydrocarbons will occur.

Thus, based on the fact that propane, butane and pentanes (in the case under consideration for this process) are effective refrigerants, the advantages of the proposed closed working cycle (with vacuum desorption of the absorbent), which makes it possible to organize the cooling of the absorbent directly during the implementation of the "absorption" cycle, are obvious. desorption "and thereby eliminate the need for an external refrigeration unit). At the same time, it is not necessary to carry out high-temperature complete distillation of gasoline fractions ΣC ₆ H ₁₄ ... and higher from the absorbent, since some accumulation of ΣС ₆ Н ₁₄ ... and higher in the absorbent can be allowed to reach an equilibrium concentration (up to 5 ÷ 10%) at process parameters corresponding to desorption modes without reducing the completeness of capture of BFLH from PVA.

In the part of the device, as an object of the invention, the problem is solved due to the fact that in the device for trapping vapors of low boiling substances (LP) from gas-vapor mixtures, for example, hydrocarbon vapors from vapor-air mixtures containing an absorber and a stripper, as well as a container of a purified absorbent, a heat exchanger, pump, connecting pipes, inlet and outlet pipelines of absorbent, gas-vapor mixture and purified gas, filters, automation equipment according to the invention, the absorber and stripper are installed with an inclination towards the outlet and of them are absorbent and made in the form of countercurrent horizontal heat and mass transfer apparatus, the cavities of which are divided into sections in which contact disks are mounted on the shaft, the stripper is also equipped with a vacuum pump-compressor and gas equalizing pipe and communicated with the capacity of the cleaned absorbent through the absorbent drain pipe, while the inlet pipe of the vacuum pump is communicated by the compressor from the first section of the stripper from the inlet side of the absorbent, the outlet device of the vacuum pump by means of a pipe yes, it is connected in series with a heat exchanger-condenser installed on the absorber drain pipe from the absorber, an adjustable throttle valve and installed in the tank of the cleaned absorbent by the evaporator of the refrigerating chamber and the condensate unit, while a filter is placed in series on the absorber drain pipe into the stripper, the heat exchanger condenser, collector, float-condensate valve, after which the absorber discharge line is divided into two pipelines, the first of which equipped with a heater and connected to the 3-5 section of the stripper, and the second pipeline is designed to supply cold absorbent to the first section of the stripper, while the collector is communicated by means of an additional pipeline with a float valve for bypassing excess absorbent installed on it, with a cleaned absorbent tank, which is connected by a pipeline with the cavity of the first section of the absorber, moreover, a filter, a pump, a non-return valve are installed in series on the pipeline main, and the condensate tank is equipped with pipes a wire for discharging condensate and communicates with the stripper and, by means of the pipeline - with a vapor mixture inlet pipe into the absorber, the stripper and the condensate tank equipped with pressure gauges, temperature sensors, sensors of the upper and lower level; moreover, the automation means include an automatic control unit for the operation of the device in communication with the indicated pressure gauges and sensors, and adjustable valves and electrovalves are installed on pipelines and highways.

In order to minimize energy costs for the implementation of the process while increasing the efficiency of the operating cycle and increasing the absorption properties of the absorbent, it is advisable to use a liquid-ring vacuum pump as a vacuum pump-compressor, while the liquid supply pipe is connected to the first pipe from the absorber discharge line behind an adjustable valve, the outlet pipe of the liquid-ring vacuum pump is equipped with a gas separator, the gas cavity of which is connected by a pipeline to the heat exchange nick-condenser, a liquid chamber via a conduit through the float valve is connected to a heater and a bypass-line - with a nozzle for supplying liquid to the vacuum pump.

The introduction of a bypass line between the gas separator and the vacuum pump allows you to create a circuit with controlled circulation of the liquid (absorbent) in order to control the temperature and flow rate of the liquid supplied to the stripper.

In order to minimize energy costs for the implementation of the process while increasing the efficiency of the duty cycle, it is advisable to heat the absorbent in a liquid ring vacuum pump during its operation with 10 ÷ 70% of the liquid circulation through the bypass line with a temperature in the range from + 10 ° С to + 120 ° C). Such a technical solution allows the use of a liquid ring vacuum pump simultaneously as a vacuum pump, heater, and liquid pump for supplying an absorbent saturated with low boiling fractions to a stripper, a cavitation stripper and a cavitation absorbent activator.

Schematic diagrams of devices for capturing and recovering vapors of hydrocarbons and other low-boiling substances from gas-vapor mixtures for this process with an integrated refrigeration cycle are shown in Figs. 1 and 2. Fig. 2 shows a schematic diagram of a device for this process in the embodiment with a liquid ring vacuum pump.

A device for collecting and recovering boiling substances, for example, hydrocarbons from steam-air mixtures (see Figs. 1-3), contains an absorber 1 and a stripper 2, made in the form of countercurrent horizontal disk heat and mass transfer apparatus, the cavities of which are divided by partitions 3 into sections 4, in which shafts 5, 6 mounted contact disks 7. The absorber 1 and stripper 2 are installed with a slope of 10 ° in the direction of exit of the absorbent.

As an absorbent, in solving the problem of trapping and recovering low-boiling substances, for example, hydrocarbon vapors from steam-air mixtures, fractions of high-boiling hydrocarbons, for example, summer diesel fuel, are used.

The desorber 2 is in communication with the cleaned absorbent capacity 8 by the absorbent drain line 9 and the gas equalizing port 10. The upper part of the first section 11 of the desorber 2 (from the inlet side of the absorbent) is connected by a pipe 14 to the inlet 12 of the vacuum pump-compressor 13. The output device of the vacuum pump-compressor 13 the pipeline 15 is connected in series with a heat exchanger-condenser 16 mounted on the absorber discharge duct 17, an adjustable choke valve 18, an evaporator of the refrigerating chamber 19 and a tank A condensate 20 mounted in the container 8 the purified absorbent.

On the line 17 of the removal of absorbent from the absorber 1 to the stripper 2, a filter 21, a heat exchanger-condenser 16, a collector 22, a float valve (condensate-separator) 23, an adjustable valve 24, a heater 25, which is connected by a pipe 26 with 3 ÷ 5, are installed in series. section of stripper 2 and pipe 27 with an adjustable valve 28 for supplying cold absorbent to the first section of stripper 2, which is cut into the pipe 17 for removal of absorbent from the absorber in the area between the float valve 23 and the adjustable valve 24 for supplying absorbent to the heater 25.

The manifold 22 is communicated by means of an additional pipeline 29 with a float valve 30 (bypass of excess absorbent) installed on it with a clean absorbent container 8, which is connected by a pipeline 31 to the first section of the absorber 1 from the side of the cleaned air outlet pipe 32 and on which the filter 33 is installed in series. pump 34, non-return valve 35, adjustable valve 36.

The condensate tank 20 is communicated by a gas pipeline 37 through an electrovalve 38 with a vapor-air mixture supply pipeline to the absorber 39, and with a stripper through PB 40 and EC 41 and is equipped with a pipeline with EC 42 for condensate drainage. The capacity of the clean absorbent 8 and the condensate tank 20 are equipped with pressure gauges 43 and 44, temperature sensors 45 and 46, and sensors of the upper 47, 48, and lower 49 and 50 levels. The rotation of the shaft is carried out by gear motors 51.

In order to minimize energy costs for the implementation of the process while increasing the efficiency of the working cycle and increasing the absorption properties of the absorbent, it is advisable to use a liquid ring vacuum pump 52 (see figure 2, 3). In this case, the pipe 53 for supplying liquid to the liquid ring vacuum pump 52 is connected to the absorber discharge line 17 behind the adjustable valve 24, a gas separator 54 is installed on the output pipe of the liquid ring vacuum pump, the liquid cavity of which is connected to the heater through a pipe 55 through the float valve 56 25, and the gas cavity by a pipe 15 is connected to a heat exchanger-condenser 16.

In order to control the temperature and flow rate of the liquid supplied to the stripper, it is advisable to introduce a pipe 57 with an adjustable valve 58 connecting the gas separator to the pipe 53 for supplying liquid to the vacuum pump 52 (bypass line) to create a circuit with controlled fluid circulation (absorbent). This technical solution allows the use of a liquid-ring vacuum pump at the same time as a vacuum pump, a liquid pump for supplying an absorbent saturated with low boiling substances (hydrocarbons) to a stripper, a heater (in the temperature range from + 10 ° С to + 120 ° С), and during operation in regimes close to cavitation, the desorption process is intensified with the simultaneous activation of the absorbent.

Consider example number 1. The implementation of the method of trapping and recovery, in relation to the task of trapping gasoline vapors (hydrocarbons) from steam-air mixtures displaced from filling tanks of fuel trucks on a loading platform for loading light petroleum products, and a device for implementing the method.

Initial data:

PVA - gasoline vapor + air.

The content of LFU in 1 m ³ PVA is 500 g.

The consumption of PVA is 36 m ³ / hour.

Absorbent - (summer) diesel fuel.

The amount of absorbent in the installation is 100 kg.

The initial temperature of the absorbent T _ab = 10 ° C.

The consumption of diesel fuel per 1 m ^{3 of} PVA is accepted - 7.5 kg / m ³ .

The flow rate of the absorbent through the absorber is 7.5 kg / m ³ × 36 m ³ / hour. = 270 kg / hour.

The pressure in the stripper P _des = 0.01 MPa.

Steam-air mixture containing low-boiling hydrocarbons under an overpressure of 150-250 mm of water. (by gravity) is fed through line 39 to the absorber 1 (horizontal disk heat and mass transfer apparatus - GDTMAA) in the counter-current mode of the vapor-air mixture and the absorbent, which is fed into the absorber along line 31 (the absorber is installed at an angle to the drain of the absorbent). Simultaneously with the supply of the PVA, the pump 34 for supplying the absorbent to the absorber is turned on.

During the sequential flow of PVA along the gap gaps between the contact disks 7 during the interaction of the vapor-air mixture with the surface of the film of liquid cooled absorbent continuously formed on the surface of the rotating contact disks 7 in sections 4 of the absorber, the fractions of low-boiling vapors are absorbed by (summer) diesel fuel and then removed from the absorber purified air and liquid absorbent. A saturated BFLH absorbent along line 17 of the absorption of absorbent from absorber 1 to stripper 2 passes sequentially through filter 21, heat exchanger-condenser 16, manifold 22, float valve (condensate separator) 23, adjustable valve 24, heater 25 (off) and goes to 3 ÷ 5 sections of stripper 2.

During the absorption of 0.5 kg LU (exothermic reaction), heat equal to:

Q = g · m · k _ex ;

where: m is the mass of condensate LU;

g is the specific heat of vaporization (g _{С3 ... С6} ≈400 kJ / kg);

k _ex ≈0.5-0.95 - coefficient experimentally established by the authors for this absorber (depends on the ambient temperature).

Q = 400 kJ / kg × 0.5 kg × 0.5 = 100 kJ;

As a result, the heating of 7.5 kg of absorbent +0.5 kg of NGL will be:

ΔT _AB = Q / C · m = 100 kJ / (2 kJ / kg · K × 8 kg) = 6.25 ° C;

where: m is the mass of the absorbent; C is the specific heat of the diesel fuel;

The temperature of the absorbent at the outlet of the absorber will be

T _{input des} = 10 + 6.25 = + 16.25 ° C.

For guaranteed desorption of 95% C ₃ H ₈ , C ₄ H ₁₀ , and ΣC ₅ H ... from the absorbent (at a given pressure) and its recovery, the temperature of the absorbent at the time of the start of desorption should be equal to or greater than 13 ° C (experimental data) therefore, to prevent overcooling of the absorbent in the stripper, a heater 25 is introduced.

Simultaneously with the inclusion of the pump 34 for supplying the absorbent to the absorber, the vacuum pump 13 is turned on and a pressure of ~ 0.01 MPa is set in the cavity of the stripper.

From a high-boiling absorbent film formed on rotating contact disks, saturated with low-boiling hydrocarbons, heated to a temperature of ≥ + 16.25 ° C (which is higher than the boiling point of C ₃ H ₁₀ , C ₄ H ₁₀ , and ΣC ₅ ... at a given pressure), low-boiling hydrocarbons are vaporized, which are pumped (by a vacuum) pump or compressor (at a pressure greater than 0.16 MPa) into the pipe 15 and then enter the heat exchanger-condenser 16.

The first stage of cooling of the absorbent occurs directly in the stripper 2 due to the removal of its own thermal energy of the absorbent for evaporation of BFLH.

During desorption (evaporation of the same amount), BFLH absorbent is cooled to a temperature:

ΔT _DB = Q _isp / s · m = 400 kJ / kg × 0.5 kg / (2 kJ / kg · K × 7.5 kg) = 13.3 ° С;

where: Q _isp - the amount of heat spent on the evaporation of 0.5 kg of LF;

m is the mass of absorbent supplied to the absorber per 1 m ^{3 of} PVA;

C is the specific heat of the diesel fuel;

those. the temperature of the purified absorbent at the outlet of the stripper will be:

T _{output des} = + 16.25 ° -13.3 ° = + 3.95 ° C.

Purified from low-boiling hydrocarbons and cooled absorbent flows into the storage tank 8 through the absorbent drain line 26.

The BFLH vapors removed from the stripper are compressed by VN 13 to a pressure above atmospheric (0.16 ÷ 0.3 MPa) and piped through 15 to the heat exchanger-condenser 16, where they are cooled to + 4 ° С - (to + 17 ° С in the initial transition period) by absorbent flowing through line 17 from the absorption column and condense.

The resulting condensate of low-boiling fractions could be immediately returned through a pipeline with an electrovalve 42 to the line of the shipped product, which is the source of these vapors, or to the storage tank. However, when the condensate contains from 10 to 55% ΣС ₃ H ₈ and С ₄ H ₁₀ (which are the main refrigerants), it is advisable to organize an additional “external” refrigeration cycle, for which the formed condensate of BFLH is passed through an adjustable valve 18, throttled to atmospheric pressure and supplied into the refrigeration chamber-heat exchanger 19, installed in the storage tank 8, where it partially boils at a constant pressure and reduces its temperature, taking away heat from the cooled purified absorbent, thereby providing its additional body cooling by Δt _pac ≈2-3.5 ° С (up to -2 ° С ÷ -4 ° С per cycle), the steam formed in this case (low-boiling С ₃ Н ₈ and С ₄ Н ₁₀ and residual air from the stripper) sent to the entrance to the absorber through the gas pipeline 37 and the electrovalve 38 (in the initial period of the transition process), and the liquid mixture BFLH (the remaining part C ₃ H ₈ , C ₄ H ₁₀ , and the whole amount ΣC ₅ H ... and ΣC ₆ N. .. and above) is sent via EC 42 to the trunk of the shipped oil product or to the storage tank for subsequent sale as a commercial product. The presence of sensors of the upper 48 and lower 50 levels in the condensate tank allows the latter to be used as a measured tank to account for the return (recovery) of condensate captured by BFLH.

In the case of a high initial concentration of BFLH in PVA and the need to maintain a high degree of capture of BFLH during transient processes when entering the stationary mode (during the return of some low-boiling С ₃ Н ₈ and С ₄ Н ₁₀ and air residues from the stripper to the absorber through the gas pipeline 37 ) You can proportionally increase the consumption of absorbent.

A further decrease in the temperature of the absorbent and increase of the cycle efficiency is possible due to the subsequent throttling of the vapor phase С ₃ Н ₈ and С ₄ Н ₁₀ from the tank 20 directly to the outlet of the desorption column through РВ 40 and ЭК 41 (pressure drop ΔР≥0.19 MPa), which will provide additional cooling of the absorbent by 2-6 degrees directly in stripper 1 with high efficiency, and the vapor phase C ₃ H ₈ and C ₄ H _{10 itself} , accumulating in a closed desorption circuit (in the condensate tank), will perform the functions:

- refrigerant (with T _bales = -5--25 ° С);

- contribute to an increase in the concentration of refrigerants C ₃ H ₈ and C ₄ H ₁₀ in the condensate tank to a level of ~ 35-85%), which will increase the efficiency of the compression refrigeration cycle and increase the completeness of capture of BFLH);

- to increase the intensity of ash and mass transfer processes in the desorption unit through the use of C ₃ H ₈ and C ₄ H ₁₀ vapors as a carrier of the vapor phase of other gasoline fractions (ΣC5 ... C ₆ ... and higher)).

An important (constructive) feature of the desorption process is that part of the absorbent introduced into the stripper can be heated and introduced into the 3rd, 4th, or 5th sections from the side of the vapor phase of the NGL from the stripper, and the other part of the unheated (cold) saturated NGL absorbent is introduced into 1 (first) section of stripper 1 from the outlet (12) side of the vapor phase of BFLH via pipe 27 with adjustable valve 28, bypassing heater 25. Moreover, vaporous fractions with a higher boiling point (ΣC ₇ H ... and higher), evaporated in 3 ÷ 5 sections of stripper from side The vapor phase inlet together with BFLH are condensed on the disks of 4 ÷ 1 sections from the side of the BFLU vapor phase (forming a kind of reflux condenser with heat and mass transfer efficiency ≥98%), since the temperature of the absorbent introduced into 1-4 sections of stripper 1 via the pipeline 27 (in stationary conditions), by about 10-15 ° С, it is always lower than the temperature of the absorbent after heater 25, but (in this case) does not exceed the boiling point ΣC ₅ H ... (at this pressure) by more than 10 ÷ 30 ° C. Moreover, the flow rate and temperature of the absorbent streams through pipelines 27 and 17 are selected in such a way that the average temperature of the absorbent should be from 13 to 28 ° C.

Purified from the majority of NGL, the cooled absorbent from the storage tank 8 passes through a pipe 31 through a filter 33 and pump 34 through a check valve 35 and an adjustable valve 36 are sent back to the absorber 1 for the absorption process.

In the case of a mismatch of the absorbent costs along the line 31 to the absorber and along the line 17 of the absorption of the absorbent from the absorber, the excess of absorbent by the float valve 30 is transferred directly to the container of the cleaned absorbent 8, which greatly simplifies the installation control system.

An introduction to the circuit of a liquid-ring vacuum pump 52 (see FIGS. 2, 3), connected by a fluid supply pipe 53 to a line 17 through an adjustable valve 24 and a gas separator 54, connected through the float valve 56 to the heater 25, and through the gas path to the pipeline 15, connected to the heat exchanger-condenser 16, allows the use of a liquid ring vacuum pump (BBH) simultaneously as a vacuum pump and heater.

So, the drive power of the vacuum pump 52 (VVN-0.8 for this installation) is 2.2 kW, efficiency = 35%, then the amount of heat ~ 1 will be consumed for heating 240 l / h of the absorbent pumped by the pump for an hour. 2 kWh = 4320 kJ,

In this case, the absorbent pumped through the BBH, heats up on

Δt _BBH ≤Q / (s · m _DT .)

where: m is the mass of absorbent pumped through the BBH;

C is the specific heat of the diesel fuel;

_BBH Δt = 4320 kJ / (2 kJ / kg × 240 kg) = 9 ° C.

However, given that the absorbent enters the stripper both from BBH 52 with a maximum flow rate of up to 240 l / h via line 55 and through line 27 (“cold”) with a flow rate of 48 l / h, the average temperature rise of the entire absorbent with NGL entering the stripper will be ΔT≤Q / (s · m _{DT + cond.} );

where m _{DT + cond} = 270 + 0.5 × 36 = 288 kg;

ΔТ _VN = 4320 kJ / (2 kJ / kg × 288 kg) = 7.5 ° С.

Thus, the absorbent will heat up another 7.5 degrees and the first vacuum desorption cycle in the case with BBH (for the case under consideration) will begin at an average temperature T _des.nach = + 22.7 ° C (at P = 0.01 MPa), which above the boiling point of propane, butanes and pentanes. In this case, the temperature of the heated absorbent entering through the pipeline 55 through the float valve 56 will be + 25.7 ° С, and not of the heated part of the absorbent — introduced into the stripper 2 through the pipeline 27--16 ° С (at steady-state stationary conditions, respectively - from + 14 ° С (max. Up to 120 ° С) through the pipeline 55, and from ~ + 4 to ~ 14 ° С - coming through the pipeline 27.

The redistribution of the costs (and temperature) of the absorbent entering through the pipeline 55 and through the pipe 27 to the stripper is carried out by adjustable valves 58, 24 and 28. Pipeline 57 with an adjustable valve 58 connecting the gas separator 54 to the pipe 53 for supplying liquid to the vacuum pump 52 (bypass line), introduced to create a fluid circulation circuit (absorbent) in order to control the temperature and flow rate of the fluid supplied to the stripper (in the temperature range from + 10 ° C to + 120 ° C).

Since the standard filling of the installation with absorbent material, in the considered example, is ~ 100 l of diesel fuel, the temperature of the absorbent after the first pumping cycle along the working circuit of 100 l of diesel fuel will be:

T _cycle = T _ab + Δt _AB + Δt _BH + Δt _DB + Δt _throttle + Δt _{throttle des} =

≈10 ° + 6.7 ° + 6 ° + (- 13.3 °) + (- 2) + (- 1) ≈ + 6.5 ° C,

those. during the first cycle, the temperature of the absorbent will decrease from + 10 ° C to + 6.5 ° C, etc.

Considering that the absorbent consumption for this installation is ~ 270 ÷ 300 l / h, then the time of one cycle will be 100 l / 300 l / h≈0.3 hours≈20 min.

In 1 hour (at the first start-up), the temperature of the absorbent in the installation will decrease by approximately ΔТ _ВН = 3.5 ° С × 3 cycles = 10.5 ° С, i.e. from 10 ° C to ~ -0.5 ° C.

During repeated starts (in the presence of condensate in the tank 20), the cooling rate of the absorbent can be increased by 3-5 times due to the greater contribution of the compression refrigeration cycle.

The implementation of this process eliminates the need for external compression refrigeration units (the cost of which is up to 30-40% of the installation cost).

At the same time, autoregulation of the cycle is achieved, which means that when the temperature of the absorbent decreases, the completeness of capture of BFLH and their concentration in the absorbent rapidly increase, and, as a result, a further decrease in the temperature of the absorbent. However, upon reaching a T _{absorp of} ≈ -3 ÷ -7 ° С, the viscosity of DT sharply increases, which leads to a decrease in heat and mass transfer coefficients and, as a result, a decrease in the completeness of capture and a decrease in the degree of cooling of the absorbent. As a result, the system itself finds the optimum mode (depending on the scheme, type of absorbent and installation parameters).

The introduction of a liquid-ring vacuum pump ensures that it functions as a vacuum pump, a pump for supplying absorbent saturated with low-boiling fractions to the stripper and heater, which makes it possible to halve the energy costs of the process at a lower cost.

This process organization scheme allows to reduce the absorbent consumption to 6.5 ÷ 10 kg per 1 m ^{3 of} PVA practically without reducing the completeness of capture of volatile hydrocarbons (for PVA of light petroleum products).

High efficiency, auto-adjustability and efficiency of the process are achieved due to the integrated absorption-compression refrigeration cycle integrated in the process.

Example No. 2. Capture and recovery of alcohol vapor during the technological processes of drying gunpowder, gypsum, etc.

In the technological processes of drying gunpowder, gypsum and other substances after their dehydration with alcohol, a significant amount of alcohol vapor is released into the atmosphere. This process can be effectively used to trap alcohol vapor and return it to the process cycle.

In this case, the vapor-air mixture, as in the previous example, is sent to the absorber and further through the process. A distinctive feature is that water is used as an absorbent, cooled to + 5- + 3 ° С. The consumption of absorbent (water) per 1 m ³ PVA is not more than 0.5-5 l / m ³ _PVA . Vacuum desorption of alcohol is carried out at a pressure of 0.015-0.04 MPa, at a temperature of + 20- + 35 ° C. (The resulting condensate is a water-alcohol solution, then sent for distillation to obtain rectified alcohol, and then returns to the process).

Example No. 3. Capture of mercaptan and hydrogen sulfide vapors during the shipment of highly viscous fuel oils (with their circulation heating).

During the circulation heating of fuel oil in railway tanks (in order to reduce their viscosity) and the subsequent operation of their pumping from the railroad neck, vapor of mercaptans and hydrogen sulfide, sulfur dioxide, toluene, benzene, saturated hydrocarbons, etc. are released.

Hydrogen sulfide and mercaptans are toxic, have an unpleasant odor and high volatility (the boiling point of methyl mercaptan is -6 ° C, ethyl mercaptan -35 ° C, which is close to the propane-butane mixture). Their presence in oils and condensates creates environmental problems in the transportation and storage of this raw material, especially in their transshipment operations.

It is known that hydrogen sulfide and mercaptans are equally well absorbed by diesel fuel, kerosene, petroleum oil and water (solubility in water is up to 3% vol.).

Using the above process allows you to capture and allocate in the form of condensate or vapor phase hydrogen sulfide and mercaptans. In this case, the process is carried out as well as in the capture of hydrocarbon vapors. In the northern regions, it is advisable to use kerosene and diesel fuel as an absorbent; in the southern regions, it is advisable to use chilled water. Absorbent (up to 90%) that has exhausted its life can be introduced into the condensate obtained and sent to a recovery boiler for combustion and production of process steam, or sent to neutralization using one of the well-known demercaptanization methods.

Example No. 4. Capture of ammonia vapor in the premises of poultry farms with simultaneous cooling and air purification.

Ammonia is a toxic substance. The increased ammonia content in the atmosphere of the premises of poultry farms leads to a decrease in the egg-bearing ability of chickens, an increase in their incidence, etc.

Using this method and device allows you to remove ammonia from the atmosphere of the premises. For this purpose, the air, saturated with ammonia vapors and fed into the absorber, wherein ammonia _(bp = -33,35 ° C) is absorbed by the chilled water at a temperature of about 5-10 ° C, after which the purified, dehumidified and cooled air back into the room. The completeness of ammonia capture is more than 99%. The absorbent (water) is supplied to the absorber at the rate of 0.5-3 liters per 1 m ^{3 of} PVA. Ammonia desorption is carried out in accordance with the process of paragraph 1. The condensate discharged from the stripper is ammonia water, which can be used as fertilizer.

In addition, this method and device can be used to capture (and remove from the processes) vapors of ethers, CO ₂ , benzene, various vapors of low boiling substances from associated petroleum gas, etc.

Compared with the best domestic and foreign installations of a similar purpose, the proposed method and installation for its implementation in the aggregate allows:

- to ensure the degree of trapping and recovery of gasoline vapors from the steam-air mixture up to 98% (if necessary - more than 99.9%), including from depleted steam-air mixtures with a hydrocarbon content of 5% or more, with very low energy costs;

- the smallest, in comparison with the best known installations, specific gas-dynamic resistance along the working path, which in most cases allows for the flow of ASG by gravity (at an overpressure of only 20-50 mm water column) without the use of explosive discharge equipment;

- reduce by 2.5-12 times (compared with known devices of a similar purpose), the dimensions and weight of the absorption units with the same completeness of capture and performance;

- to implement a wide range of regulation of the flow characteristics of the vapor-gas (vapor-air) mixture, which allows for the constant intake of vapors of low-boiling hydrocarbons both during storage of oil and light oil products (small breaths), and during filling tanks (large breaths)

- reduce installation and work sites by 2-10 times;

- ensure a reduction in capital expenditures on environmental protection by 2-12 times;

- reduce the amount of electricity consumed to 0.15-0.2 kW per 1 kg of condensate obtained (almost 40-60% compared with the closest analogues);

- The most complete solution of environmental and fire safety issues at refineries, low pressure tanks and gas stations;

- significantly expand the scope of use of installations for this process.

This process will find wide application for capturing and recovering both harmful and useful substances from steam-blowing mixtures in the chemical, food, woodworking, perfumery, pharmaceutical and other industries.

Figure 1 shows a schematic diagram of an installation for capturing and recovering boiling substances from vapor-gas mixtures for this process.

Figure 2 shows a schematic diagram of an installation for collecting and recovering boiling substances from vapor-gas mixtures according to this process in the embodiment with a liquid ring vacuum pump.

Figure 3 shows the working unit of the absorption-regenerative system with vacuum desorption (BARS-60 VD unit) for trapping and recovering gasoline vapors at a capacity of up to 60 m ³ / h (shown without heat-insulated panels).

Claims (12)

1. The method of trapping vapors of low boiling substances (LP) from vapor-gas mixtures (ASG), comprising supplying a vapor-gas mixture to an absorber, subsequent absorption of vapors of low boiling substances from it with a liquid absorbent, withdrawing purified gas from the absorber and supplying a saturated LP absorbent to the desorber, characterized in that as an absorber use a horizontal disk heat and mass transfer apparatus, as absorbent - high-boiling fractions that are fed into the absorber towards the vapor-gas mixture, pass them sequentially and counterflow along the gap gaps between the contact disks, thus interacting the vapor-gas mixture with the surface of the liquid absorbent film continuously forming on the surface of the rotating contact disks, the amount of absorbent being proportional to the consumption of ASGs based on the achievement of a concentration close to equilibrium of at least one of the drugs in the absorbent, the process of desorption of the absorbent is carried out at a pressure significantly lower than atmospheric - in the range from 0.005 to 0.05 MPa, with an average temperature of the absorbent higher The boiling point of the main desorbed low-boiling substances at a given pressure in the countercurrent mode of the absorbent and vapor phase by evaporation of low-boiling substances, which simultaneously serve as refrigerants, from the film of high-boiling absorbent saturated on the low-boiling substances formed on the rotating disks, while its cooling due to the removal of its own thermal energy absorbent for evaporation of boiling substances, while the vapor phase removed from the stripper is cooled by an unheated sweat lump of absorbent to the condensation temperature of high-boiling absorbent vapors, the vapors of fractions of low-boiling substances removed from the stripper are compressed and condensed at a pressure above atmospheric pressure while cooling them in a heat exchanger with a liquid absorbent flowing from the absorber, the condensate of low-boiling fractions formed is removed from the process, and the purified cooled absorbent is sent back in the absorber for the absorption process. 2. The method according to claim 1, characterized in that low-boiling hydrocarbons are used as the drug. 3. The method according to claim 1, characterized in that diesel fuel is used as the absorbent. 4. The method according to claim 3, characterized in that diesel fuel is supplied to the absorber at a temperature of from +5 to -5 ° C based on 5 to 20 l of absorbent per 1 m ^{3 of} ASG, the flow rate of the gas-vapor mixture and absorbent relative to the surface contact disks no more than 3 m / s, the residence time of the gas-vapor mixture in the contact zone is not less than 1.2 ÷ 1.7 s and the rotation speed of the contact disks is from 10 to 100 rpm, while the ratio of the gas-vapor mixture consumption (V, m ³ / h) to the surface of the contact disks (S, m ² ) less than or equal to 2-5. 5. The method according to claim 1, characterized in that the condensate of boiling substances formed during cooling is throttled to a pressure below critical for one or part of boiling substances with its boiling at constant pressure and lowering its temperature, while the heat required for boiling of boiling substances divert from the cleaned absorbent, thereby providing additional cooling, the steam of low boiling substances formed in this case is sent to stationary inlet at the inlet of ASG to the absorber, and to the station In a linear mode, they are throttled into the stripper, and the remaining condensate of low-boiling substances is removed from the process. 6. The method according to claim 1, characterized in that the pressure drop in the stripper to 0.005 ÷ 0.05 MPa is carried out during operation of the liquid ring vacuum pump. 7. The method according to claim 6, characterized in that the absorbent involved in the process is used as the working fluid for the liquid ring vacuum pump. 8. The method according to claim 6, characterized in that the heating of the absorbent is carried out during its flow through the liquid ring vacuum pump in the process of its operation. 9. The method according to claim 1, characterized in that the heating temperature of the absorbent is set based on the fact that the average temperature of the cold and heated absorbent streams entering the stripper should not be lower than the boiling point of the main, highest boiling point desorbed substances at a given pressure, the temperature of the cold part of the absorbent supplied to the stripper should be lower than the boiling point of the highest boiling point of the desorbed fraction materials, taking into account the heating of the absorbent from condensation on the contact disks of the stripper EPA vapor from high boiling point, a part of the absorbent. 10. A device for trapping vapors of low boiling substances (LP) from vapor-gas mixtures (ASG), containing an absorber and stripper, as well as a container of cleaned absorbent, a heat exchanger, a pump, connecting pipes, supply and exhaust pipelines of absorbent, gas-vapor mixture and purified gas, filters, automation equipment, characterized in that the absorber and stripper are installed with a slope towards the exit of the absorbent and are made in the form of countercurrent horizontal heat and mass transfer apparatus, the cavities of which are divided into sections, in contact disks are installed on the shaft, the stripper is also equipped with a vacuum pump and gas equalizing pipe and connected to the container of the cleaned absorbent via the absorbent drain line, while the inlet pipe of the vacuum pump is in communication with the first section of the stripper from the side of the absorbent input, the outlet of the vacuum pump is connected in series through the pipeline with a heat exchanger-condenser installed on the absorber removal line from the absorber, an adjustable throttle valve and a filter, a heat exchanger-condenser, a collector, a float-condensate separator valve, after which the absorber discharge manifold is divided into two pipelines, the first of which is located in the tank of the cleaned absorbent by the evaporator of the refrigerating chamber and the condensate block; which is equipped with a heater and connected to 3-5 sections of the stripper, and the second pipeline is designed to supply cold absorbent to the first section of the stripper, while the collector The OR is communicated through an additional pipeline with a float valve for bypassing excess absorbent with a clean absorbent tank installed on it, which is connected by a pipeline to the cavity of the first section of the absorber, with a filter, a pump, a non-return valve installed in series on the pipeline, and a condensate tank equipped with a drain pipe condensate and in communication with the stripper and through the gas pipeline - with the pipeline for supplying the gas mixture to the absorber, while the stripper and the tank for condensate provided with pressure gauges, temperature sensors, sensors of the upper and lower level; moreover, the means of automation include an automatic control unit for the operation of the device in communication with the indicated pressure gauges and sensors, and adjustable valves and electrovalves are installed on pipelines and highways. 11. The device according to claim 10, characterized in that the absorber is designed to trap boiling hydrocarbons as a drug. 12. The device according to claim 10, characterized in that it contains a liquid-ring vacuum pump as a vacuum pump, while the liquid supply pipe is connected to the first pipe from the absorber exhaust pipe behind an adjustable valve, and an output pipe of the liquid-ring vacuum pump is installed a gas separator, the gas cavity of which is connected by a pipeline to a heat exchanger-condenser, and the liquid cavity is connected through a pipe through a float valve to the heater and the bypass line to bkom fluid supply to the vacuum pump.

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