RU2327504C1 - Station of oil products dehydration - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: watered oil products from collector 1 are supplied sequentially through recuperative heat-exchanger 3 and superheater 4 in autoclave-settling tank 5. Carbohydrates that are released from large water particles are supplied from autoclave-settling tank 5 to receiving bin of stripping film device 6, where boil-off of residual moisture takes place. Evaporated moisture is supplied in condenser 7, which is cooled by register 8, from where condensate flows by gravity to settling tank 9. In settling tank 9 condensate is separated in top carbohydrate layer and bottom water layer.

EFFECT: acceleration of water vapors stripping and reduction of power inputs.

4 cl, 1 dwg

Description

The invention is intended for dehydration of highly viscous petroleum products, fats and other media and can be used in petrochemistry, oil refining, transport, oil transportation, energy, food and other industries.

Waterlogged oil and grease products are formed during accidental spills, during the preparation of railway tanks and ship tanks for cargo change, during washing and separation processes, as well as during the preparation of capacitive equipment for repair and internal inspection. At the same time, water in hydrocarbons is present both in the form of large droplets capable of exfoliating, and in the form of submicron particles forming stable colloidal systems, and also in molecular form, in molecular form, in dissolved form.

The separation of coarse water-oil mixtures is traditionally carried out in gravity sumps, both non-nozzle and coalescing. Stable colloidal systems are separated in washing or extraction units using surface-active substances (surfactants) or solvents that affect the equilibrium conditions between the aqueous and hydrocarbon phases. To remove dissolved water, distillation plants are used, consisting of a heated tank, a helmet pipe, a condenser of distilled vapors and collections of feedstock and separation products (Kasatkin. Processes and apparatuses of chemical technology, - M: Chemistry, - 1957).

Attempts to use all of the above means for dehydration of highly viscous organic products do not give the desired effect due to the extremely low speeds of mass transfer processes in such viscous media. So, after 48 hours of settling of waterlogged fuel oil M 100 at a temperature of 90-100 ° C, the water content in it remains ~ 20%. The addition of surfactants and extractants followed by settling of the mixtures at the same temperature conditions can slightly reduce the water cut of fuel oil, but the processing time and energy consumption increase significantly. It is not possible to drive water from the mass of fuel oil in 5-6 hours even at a temperature> 150 ° C in vacuum apparatuses. At temperatures above 200 ° C, dehydration processes could be faster (due to a significant decrease in the viscosity of the medium being treated), however, this increases the likelihood of tar wax paraffins.

The well-known "installation for the vacuum distillation of petroleum feedstocks" (RF patent No. 36256, class B01D 3/10, publ. 03/10/04), containing a distillation apparatus connected to a source of reduced pressure with pipelines for supplying petroleum feed, discharge of the separated liquid fraction and removal of residues from the apparatus. The installation differs in that the distillation apparatus is made in the form of a horizontal container, the upper part of which is formed by a cylindrical surface, and the lower one - by two curved sections with the edges bent inward, the ends of which are connected to a vertical channel connected to the accumulated liquid fraction accumulator. The cooling system is located in the upper part of the tank, and the heating system in the lower part. But the evaporation in the described installation is carried out from the mass of processed raw materials, therefore its use for highly viscous media is ineffective for the above reasons.

Also known is the installation of dewatering bitumen with a dynamic tray system (RF patent No. 2236495, publ. 20.09.04, IPC E01C 19/08, C01C 3/12). It contains a container, heated inside and out and equipped with a mixer, the blades of which rotate and slide on the inner surface of the casing. The heating of the mass of bitumen in this way can be intensified, however, the evaporation of moisture from the mixed highly viscous mass proceeds extremely slowly.

The well-known "installation for the drying of paste-like heat-sensitive material" (US Pat. No. 599783, class F26B 17/00, published September 15, 03), including a container, a vacuum drum filter, a horizontal perforated belt conveyor between the filter drum and the second drum, a gas duct for coolant, distribution manifold, vacuum pumps, housing, hopper and conveyor of the dried product with an intermediate shutter.

The limited layer thickness of the processed product contributes to a more complete distillation of water, however, this installation is not without significant drawbacks:

1) the drum vacuum filter has a very high resistance to a viscous product and unnecessarily complicates the distillation complex;

2) the perforated belt conveyor is bulky and unsuitable for moving products such as fuel oil and bitumen with the simultaneous use of perforations;

3) warming the viscous mass with hot gas is ineffective;

4) there are no devices that equalize the thickness of the layer of the processed product on the conveyor, which significantly reduces the completeness of the distillation.

It is more possible to drive away water from thin layers of a highly viscous product, so it is more promising to use distillation plants in film machines.

As such, it is proposed to use, for example, the well-known "rotary film apparatus" (US Pat. No. 69779, class B01D 3/30, publ. 15.09.04) with a cross-flow diagram of the gas-liquid system. It contains a housing with liquid and gas inlet and outlet nozzles, a shaft with a rotor fixed to it and two end caps, between which there is a contact device in the form of a tape spiral with Z-shaped bends along its entire perimeter. In the middle of each bend there is at least one hole for the passage of gas. When liquid enters the apparatus, it is distributed in the form of a film on a spiral under the action of centrifugal force, and in the places of bending it disperses into droplets. When a gas stream passes through a contact device, interphase turbulization occurs, intensifying the mass transfer process.

Considering only the main part of the installation: the rotary film apparatus, serious shortcomings should be noted. The movement of a highly viscous liquid by gravity along a ribbon spiral and dispersing it into droplets is possible only at a very high temperature, which is unacceptable for thermolabile liquids. Highly viscous liquid cannot be distributed by centrifugal forces on the tape in an even layer, and after dehydration, unload it immediately from the apparatus.

Another "rotary film evaporator" (US Pat. RF No. 2186605, class B01D 1/22, publ. 10.08.02), which contains a cylindrical body with a heated jacket, a source of supply of the source fluid and a fitting for the removal of secondary steam and concentrate, rotor with blades fixed along its entire length and connected to the drive, it has the same drawbacks as the previous one.

The closest to the claimed station according to formal signs is the "installation for drying fuel and oils" (RF patent No. 2042372, BI No. 24, 1995). This installation includes a collection of watered oil products, a large distant apparatus (cube), a condenser-reflux condenser, a vacuum condenser, a vacuum pump, a condenser of vapors pumped by a vacuum pump, a condensate sump, a small distillation cube, collectors of dehydrated oil products and condensed light fractions, a collection of distilled water and lines connecting these devices, including the collector of gas etching lines from all devices operating under vacuum.

The following features are essential for solving the task: a collection of watered oil products, a stripper, a condenser of distilled vapors, a condensate sump, a collector of the upper layer (light oil products that form inevitably boiling mixtures with water - azeotropes), a water collector, a collection of dehydrated oil products and piping (pipelines connecting these devices), including the gas line collector.

When dehydrating viscous petroleum products (M-100, bitumen, paraffins) in this installation, a number of disadvantages are found:

1) the design of the stripper — the cube (container with heating elements) —is ineffective for processing products with high viscosity;

2) all water contained in oil products is removed by distillation, therefore, with an initial water cut of more than 40% of the product, the energy consumption is so great that their cost exceeds the effect achieved by its dehydration;

3) there is no heat exchanger-superheater, which does not allow to intensify the distillation process by reducing the time to supply the required amount of heat;

4) distant and heat exchangers of a batch installation, the processed product in them is stationary and viscous, therefore, the processes of heat and mass transfer cannot be intensified.

The task of the invention is to develop an effective dehydration station for viscous petroleum products, devoid of the above disadvantages.

The technical result is achieved due to the fact that the well-known set of apparatuses “drying units”, including a collection of water-saturated oil products, a stripper, a condenser of distilled vapors, a condensate sump, a collector of a (upper) hydrocarbon layer, a water collector, a collection of dehydrated oil products and piping, including collector gas lines, some changes and additions have been made, namely:

1) instead of the stripping cube, a stripping film apparatus with moving disks is used;

2) there is at least one heat exchanger-superheater of the processed product;

3) there is an autoclave-settler, where part of the water is separated from the overheated flooded product without evaporation;

4) all heat and mass transfer apparatus of the continuous station.

An example of a concept of a station for dehydration of petroleum products is shown in the drawing.

The diagram shows:

1 - a heated collection of flooded hydrocarbons; 2 - pump; 3 - heat exchanger-recuperator; 4 - superheater; 5 - autoclave settler; 6 - stripping film apparatus with moving disks; 7 - condenser distilled vapor; 8 - cooling register; 9 - condensate sump; 10 - a collection of light hydrocarbons; 11 - a collection of the water layer; 12 - shutoff and control valves; 13 - a collection of dehydrated oil products; 14 - heating registers; 15 - air; 16 - collector gas lines.

The station operates as follows.

Watered petroleum products from the heated collector 1 are pumped 2 sequentially through a heat exchanger-recuperator 3, where they are heated by separated superheated water, and then through a superheater 4 to an autoclave-settler 5, where pressure is maintained above 0.5 MPa (0.6-1.6) and temperatures above 140 ° C, but below the boiling point of water. At such a high temperature, the viscosity of hydrocarbons is much lower, so large particles of water have time to settle in the lower part of the autoclave and form an aqueous layer. This water layer, as it accumulates, is discharged from the autoclave-settler 5 for purification or reuse, after cooling it to a temperature below 100 ° C in the heat exchanger-recuperator 3. This avoids boiling of water when the pressure drops to atmospheric. Hydrocarbons freed from large particles of water are squeezed out under pressure drop into the receiving hopper of the stripping film apparatus 6, where due to a sharp decrease in pressure to atmospheric pressure during the continuous formation and movement of the film of the processed product, the moisture remaining in it rapidly boils away. A lot of heat is used to evaporate moisture, and this can lead to cooling and solidification of the product in the bins. Therefore, compensatory heating of the mass of the product is carried out using the heating registers 14, which are equipped with all the hoppers of the stripping film apparatus. Evaporated moisture enters the condenser 7, cooled by register 8, where it condenses, and the condensate flows by gravity into the sump 9. Together with vapors of water to be distilled, light hydrocarbons in the form of azeotropes can be distilled off. Therefore, the condensate in the sump 9 will be stratified into two layers: the upper - hydrocarbon - and the lower - water. The upper layer — light hydrocarbons — is drained by gravity into the collector 10 and, as it accumulates, is shipped for sale, for example, as a valuable light fuel. The water layer through the hydraulic lock is discharged by gravity into the collector 11, from where, as it accumulates, it is recycled or reused. Dehydrated viscous hydrocarbons from the stripping film apparatus 6 are drained by gravity into a heated collector 13 and, as they accumulate, they are sold, for example, as boiler fuel. The pressure in the system for distillation and processing of separation products, including collectors, is maintained by atmospheric air through air 15. To avoid the loss of volatile hydrocarbons into the atmosphere, gas recovery lines from apparatuses 9, 10 and 11 are assembled into a collector 16 connected to a condenser 7.

Thus, the proposed technical solution has several advantages compared to the technical solutions used for the same purposes, namely:

1) water vapor is distilled off two to three orders of magnitude faster than in similar installations, since the watered product is preheated and formed in the form of a film;

2) due to significant overheating and a decrease in the viscosity of the processed raw materials in the autoclave-settler, a significant part of the undissolved water manages to separate without evaporation, which reduces the energy consumption for dehydration by 2–3 times;

3) the heat of the superheated water separated in the autoclave is used to preheat the waterlogged hydrocarbons in the heat exchanger - recuperator, which reduces the total energy consumption for dehydration;

4) in continuous operation, the viscous product does not stop moving, which allows to intensify its processing.

The pilot version of the oil dehydration station is currently being installed at the faculty in the city of Kirishi. Based on the results of its tests, the leadership of the Oktyabrskaya Railway will decide on the creation of an industrial station for the dehydration of oil products with high throughput.

Claims (4)

1. A station for dehydration of oil products, including a collection of watered oil products, a distillation apparatus, a condenser of distilled vapors, a condensate sump, a collector of a (upper) hydrocarbon layer, a water collector, a collection of dehydrated oil products and piping, including a collector for gas recovery lines, characterized in that it is equipped with an autoclave - sedimentation tank, and for stripping, a stripping film apparatus with moving disks is used. 2. The station for dehydration of petroleum products according to claim 1, characterized in that it is equipped with at least one heat exchanger-superheater of flooded hydrocarbons. 3. The station for dehydration of petroleum products according to claim 1, characterized in that it is equipped with a heat exchanger-recuperator of heat of separated superheated water. 4. The station for dehydration of petroleum products according to claim 1, characterized in that all of its heat and mass transfer apparatuses are made for continuous operation.