RU2717028C1 - Method for wave purification of rectification columns from heavy oil residues containing fine mechanical particles - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil processing, oil and gas industry, in particular, to cleaning reservoirs from heavy oil residues. Method involves flushing water from top to bottom of the column with draining of dirty water into industrial sewer. Column is filled with hot water up to the level of the upper manhole and steam is supplied to the bottom part of the column. Quality of the column cleaning is controlled by visual determination of the drainage water transparency.

EFFECT: increased efficiency of cleaning, reduced time expenditures.

1 cl

Description

The present alleged invention relates to the refining, oil and gas industry. It is aimed at a modern solution to the problem of cleaning large-sized mass transfer apparatus. The proposal mainly relates to the purification of distillation columns of technological processes for the processing of crude oil and columns for stabilizing the products of the catalytic processing of oil and gas raw materials contaminated with catalytic dust and alkali, in case of their alkaline treatment. Currently, before carrying out repairs on the columns in question, they are subjected to prolonged water washing followed by manual cleaning of their contact plates and pockets of the latter. Such work is carried out in the following order:

1. After the technological installation is stopped for appropriate repairs (current or major), the column is freed from liquid hydrocarbons, then the air vent located in its upper end is opened and, by supplying water vapor to the bottom of the column, they begin to blow it, with the discharge of steam residual liquid and gaseous hydrocarbons (to a safe content of hydrocarbons in the samples of air from the column).

2. Then, open the upper hatchway of the column and, by supplying technical water to the upper contact plate, wash the column with drainage of dirty water through a fitting in its bottom, into the industrial sewer. Rinsing water from the upper contact plate flows into its pocket, from which it flows onto the downstream plate and so on, to the bottom plate. The washing operation of the column, depending on its size and degree of contamination, lasts at least 2-3 days and requires the consumption of large quantities of water.

3. Then, if there are no harmful impurities in the sample from the column, the rest of its hatches are opened and, removing part of the contact devices in the center of the contact plates, the mine is pierced in the column. After that, they begin to manually clean the plates and their pockets. The dirt remaining in pockets and plates may be in large quantities. This stage of work, carried out manually and in cramped conditions, is characterized by extremely low manufacturability, low working culture and harmful working conditions (in connection with which, often the work is carried out in anti-wear suits).

According to the present alleged invention, water purification of distillation columns from dirt is carried out in one stage, in the following order:

1. After purging the distillation column with water vapor and opening its upper hatch, the column is filled with hot technical water to the level of the hatch, while applying gradientless heating of its flow by supplying sharp water vapor into it.

2. Then, opening the valve of the drainage fitting located on the bottom of the column, establish the same balance between the water entering the column and drained from it. Thus, the stability of the water level in the column is achieved, which is necessary for the full coverage of all its contact plates and their pockets with water.

3. After performing the operations according to p. 1 and 2, water vapor is supplied to the bottom of the column, smoothly, avoiding large hydraulic shocks in it. The optimal supply to the column is such that a uniform sound (hum) is achieved over the entire height of the column, without water hammer.

4. Quality control of the column cleaning is carried out by visually determining the transparency of the drainage water, periodically taken into a transparent glass container.

5. When the color of the drainage water is identical to the fresh water supplied to the column, its purification is considered completed. After which, it is freed from water and proceed to further routine maintenance.

Depending on the dimensions of the columns and the quality of the processed raw materials, the duration of their cleaning lasts about 5-15 hours.

The essence of this method of cleaning contact plates and their pockets of distillation columns is that when water vapor enters the mass of water in the column, its bubbles condense quickly, losing their volume (collapse). Due to the fact that this happens in an incompressible fluid, at the beginning, when steam enters the column, direct micro-shock waves appear in the volume of water. When steam bubbles collapse, microwaves arise in the opposite direction (similar to the occurrence of a direct and reverse wave in the explosion of any explosives). During the movement of a direct shock wave, a vacuum occurs behind the front of its movement, as a result, the mass of dirt deposited on the contact plates and their pockets comes off their surface. During the movement of the reverse microwave, a highly effective contact of water with dirt occurs, with deep penetration into the mass of dirt. Such a mass transfer mechanism is repeated many times along the height of the column, leading it to mass transfer in an oscillatory hydrodynamic wave mode.

The proposed method of single-stage wave cleaning of distillation columns has passed successful pilot tests when cleaning contact plates and their pockets deposited during rectification of a heterogeneous catalytic hydrogenation product at 300 atm. middle oil fractions, then subjected to alkaline treatment. Cleaning lasted about 5.5 hours.

This method was successfully tested on a distillation column of straight-run oil refining, the pockets of the contact plates of which were clogged with dense mud by 85-90%. The column has not been cleaned for more than 8 years. After washing it for 15 hours according to the proposed method, she was completely ready for subsequent routine maintenance.

The proposed method can be successfully used in the purification of dirt from gas-liquid separators, electric dehydrators for the desalination and dehydration of oils and gas condensate and the cleaning of reactors of thermal processes of oil refining.

Claims (1)

The method of wave purification of distillation columns from heavy oil residues containing fine mechanical particles, including washing the columns with water from top to bottom with draining dirty water into an industrial sewer, characterized in that the column is filled with hot water to the level of the upper manhole and the water column is fed into the bottom steam, while monitoring the quality of column cleaning by visually determining the transparency of the drainage water.