RU2466174C1 - Method to clean furnace coil with vertical pipes against coke deposits - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: method includes preheating of pipes to 450-500°C with blowdown by water vapour along with movement of produced products and subsequent additional heating of pipes with sections to 700-850°C with subsequent displacement of the heating area. According to the invention, the heating zone is moved in direction from the outlet section to the inlet section of the furnace coil.

EFFECT: invention makes it possible to reduce duration of furnace coil cleaning by 5-7 hours.

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Description

The invention relates to oil refining, in particular to methods for cleaning coke oven furnaces with vertical pipes.

A known method of cleaning pipes of furnaces from coke deposits, including pre-heating pipes to 300-650 ° C (mainly 450-500 ° C), followed by blowing water vapor in the direction of the formed products. Heating is continued to 650 ° C, after which every half hour the direction of flow is reversed (reverse) / Wolfson S.I. Steam-air method for the removal of coke from the furnaces of oil refineries. M., Gostoptekhizdat, 1963, p. 26-53).

The disadvantage of this method is the significant investment of time (18-38 hours) for cleaning the tube furnace from coke deposition.

The closest in technical essence and the achieved effect to the proposed method is a method for cleaning cracking furnaces, including pre-heating the pipes to 450-500 ° C with steam blowing along the course of the formed particles of coke products with subsequent additional heating of the pipes in successive sections from beginning to end up to 700-850 ° C (the section means a section of several pipes covered by the flame of one or more burners, the so-called heating zone) / A.s. SU No. 1726493 A1. BI No. 14, 04/15/92 /.

Heating of pipes in successive sections contributes to the uniform entry of coke particles into the transporting stream and their removal from the furnace.

However, when vertical furnace tubes are cleaned in this way, particles of coke deposits of the first section are intensively removed and spontaneous blockage of the pipe cross-section of the next furnace sections that have not yet been cleaned, which leads to an increase in the duration of the coke removal operation due to the time required to eliminate blockages in the pipes furnace coil.

The objective of the invention is to reduce the cleaning time of the coil of the furnace with vertical pipes from coke deposits.

This is achieved by the fact that in the method of cleaning the coil of a furnace with vertical pipes from coke deposits, which includes pre-heating the pipes to 450-500 ° C with steam blowing along the formed products and subsequent additional heating of the pipes in sections to 700-850 ° C with moving heating zones, according to the invention, the heating zone is sequentially moved in the direction from the outlet to the inlet sections of the furnace coil.

When pipes are heated to 700-850 ° C in a water vapor environment, coke deposition is calcined with the loss of volatiles, while coke shrinks, becomes brittle and due to a significant difference in the thermal expansion coefficients of the pipe metal and coke, reaching 10-20 times, the contact surface collapses, coke cracks, breaks off the pipe walls and is carried out by a stream of water vapor from the furnace coil in the form of a dispersed (granular) substance.

The primary cleaning of the outlet (end) section of the furnace coil allows you to increase the flow area of this section and thereby ensure free passage of dispersed coke from previous untreated sections of the furnace coil, and to stabilize the process of its removal.

The parallel arrangement of the vertical pipes and the flame of the furnace burner makes it possible to more clearly establish the boundary and the size of the heating surface of the section, to maintain the given sequence of their movement in the direction from the output to the input sections of the furnace coil.

The stabilization of the dispersed coke removal process described above allows the pipes to be cleaned without stopping the furnace to remove the reaction coil from the process system and thereby reduce the time taken to clean the pipes from coke deposits.

The proposed method is as follows.

Replace the hydrocarbon feed entering the furnace coil from vertical pipes with water vapor. In this case, the furnace coil is not removed from the technological system and the temperature of 450-500 ° C is maintained in the furnace. Water vapor is supplied in the direction of flow from the inlet to the outlet sections of the furnace coil. Then, additional heating of only one outlet (end) section of the furnace coil to a temperature of 700-850 ° C is carried out by the corresponding group of burners, increasing fuel consumption in them, and the supply of water vapor to the furnace coil is also increased, controlling the magnitude of the technological parameters for the removal of granular coke from the coil the furnace visually by “peeping” or by the sound (noise, shock) of coke particles in the pipes of the remote system.

After cleaning the pipes of the outlet section of the furnace coil, the cleaning process is transferred to the previous neighboring section by identical control of the technological parameters, and the parameters of the cleaned outlet section are returned to the previous, milder mode with a temperature of 450-500 ° C. Similarly and sequentially, the remaining vertical pipes of the furnace coil are cleaned in the direction from the outlet to the inlet sections of the furnace coil. Dispersed coke from the chimneys, together with a stream of water vapor, is sent to the collection unit for cleaning products.

The table shows data on the duration of cleaning the coil of the furnace from coke deposits according to the proposed method and prototype, depending on the temperature of the additional heating sections of the coil of the furnace.

The performance of the method of cleaning pipes of the coil of the furnace No. of furnace coil cleaning operations The heating temperature of the sections (sections) of the furnace coil of the proposed method and prototype, ° C The duration of the cleaning operation of the furnace coil, hours * Arithmetic average duration of operations, hours The proposed method Prototype The proposed method Prototype one 700 fifteen 8 - - 2 800 12 32 13.5 twenty 3 850 12 7 13 15.6 four 700 fifteen 36 13.5 20.7 5 800 13 7 13,4 eighteen 6 850 12 2.5 13.1 19.1 7 700 fifteen 8 13,4 17.5 8 800 13 25 13.3 18.5 9 850 12 7 13,2 17,2 10 700 fifteen 36 13,4 19.1 eleven 800 12 7 13.3 eighteen 12 850 12 32 13.1 19.1 * the flow of water vapor is regulated by the removal of coke from the coil of the furnace.

As can be seen from the table, cleaning the furnace coil by additionally heating the sections with successive movement of the heating zone in the direction from the outlet to the inlet sections of the furnace coil allows reducing the cleaning time by 5-7 hours or by 46% (rel.).

Claims (1)

The method of cleaning the coil of a furnace with vertical pipes from coke deposits, including pre-heating the pipes to 450-500 ° C with steam blowing along the formed products and subsequent additional heating of the pipes in sections to 700-850 ° C with the movement of the heating zone, characterized in that the heating zone is successively moved in the direction from the outlet to the inlet sections of the furnace coil.