RU2167905C1 - Lining of chambers of ovens from heat treatment of carbon-containing raw materials - Google Patents

Abstract

FIELD: by-products, shale-processing, electrode and other industries, and in repairs of ovens. SUBSTANCE: inventions deals with designs of coke, pitch coke, shale-processing and other ovens for heat treatment of carbon, hydrocarbon and carbon-containing raw materials. Lining of chambers of ovens for heat treatment of carbon-containing materials includes interconnected refractory articles. Surfaces of refractory articles, facing furnace chamber, have recesses inclined to horizontal axis. Recesses on surface of refractory articles are made vertical. Refractory articles with recesses are laid in head part and part adjacent to charging holes. Recesses on surface of refractory articles are inclined to side opposite to oven doors, and number of recesses on surface of refractory articles is determined by formula

, where is number of recesses in lining; E is modulus of elasticity of lining material, kgf/sq.cm; β - is specific contraction of lining material for 1/ C; Δt - is temperature change value of wall surface, C;

Description

 The invention relates to the construction of coke ovens, pitch coke ovens, slate processing and other furnaces that heat treat carbon, hydrocarbon, carbon-containing raw materials, and can be used in coke, shale processing, electrode and other industries, as well as in repairs of furnaces. Given the identity of the processes in the thermal processing of carbon-containing materials of organic origin in batch furnaces, further in the description, our proposal is considered on the example of the lining of furnace chambers for coking coal (coal charges).

 The closest analogue of the invention is the lining of furnace chambers for heat treatment of carbon-containing raw materials, including interconnected refractory products, while on the surface of the refractory products facing the furnace chamber, grooves are inclined to the horizontal axis (RU 2028364 C1, C 10 B 29/02, 02/09/95).

Coke ovens are batch ovens. A coal charge (coal tar pitch) is loaded into the furnace chamber, heated to a temperature of 1000 - 1100 ^o C for 14 - 18 hours. The resulting coke is discharged from the furnace chambers and then the coal charge is reloaded, respectively.

 The lining of the coke oven chamber in the zone of the "head" parts on both sides undergoes sharp temperature fluctuations: these zones during the operation of the furnaces for 20 - 40 years or more, every 14 to 18 hours are sharply cooled during coke delivery and furnace loading and heated for coking period. As a result of such abrupt heat exchange, the lining in the zone of the “heads” and loading hatches begins to collapse, the area of the damaged surface gradually increases, damage to the refractory products increases, in some cases deep shells and burnouts are formed, resulting in a reduction in the service life of the furnaces.

 Temperature fluctuations lead to an even more unpleasant feature of the operation of coke oven batteries: in the "head" part of the walls of coke oven chambers, due to internal stresses in the coked mass, its monolithicity is violated, which leads to the separation of the extreme part of the coke cake from its bulk. When the doors are removed, this part falls out of the furnace chamber to the work platform (the so-called "ends"), thereby creating enormous difficulties for maintenance personnel, who are forced to manually or mechanically cast this coke back into the coke oven. With a total mass of 15 to 30 tons of coke produced from modern coke ovens, the number of “ends” sometimes reaches 700 kg. Therefore, in addition to difficulties in operation, the "ends" of coke that are thrown back into the furnace chamber reduce the useful capacity of the furnace chamber by an appropriate amount, thereby reducing the overall performance of the coke oven battery.

 The analysis of the process of destruction of the refractory masonry and coke landslides from the head of the furnace chambers has one and the same reason initially - with sharp fluctuations in temperature, thermal stresses arise in the masonry and the coked mass. It is practically not possible to eliminate the indicated causes by means of the furnace heating mode or operating conditions due to the peculiarities of the design of coke and pecocoke batteries.

 The technical essence of the invention is to increase productivity and increase the life of the furnaces by eliminating coke falls from the head of the furnace chambers and increasing the strength of refractory products.

 To do this, on the surface of the refractory products from which the walls of the coking chambers are laid, vertical or inclined grooves are made on the side facing the furnace coking chamber.

 In FIG. 1 shows a refractory product with inclined grooves; figure 2 is a view aa in figure 1.

 Refractory products with grooves can be laid out either the entire furnace chamber, or only that part of it, which is subjected to the most abrupt temperature fluctuations. So, in horizontal coke and pitch coke ovens, it is most expedient for refractory products with grooves to lay out only the “head” part and the part adjacent to the loading hatches. Moreover, the implementation of the grooves in the head parts of the lining almost completely eliminates coke crashes when removing the oven doors before issuing the coke cake. This is due to the retention of the coke column in the grooves of the lining. Upon delivery, the head part of the coke cake is crushed by the head of the coke pusher booster press to a depth of 0.5 m and pushed along with the entire mass of the coke cake. This effect was established as a result of studies on experimental piers, the head part of which was first made of refractory products with grooves on a coke oven battery N 4 of the Altai Coke and Chemical Plant, and then confirmed on new coke oven batteries of the Nizhny Tagil and Cherepovets steel plants.

 The number of grooves and their depth depend on the characteristics of the refractory material used (tensile strength, elastic modulus, specific reduction), the dynamics of the temperature in the furnace chamber, the thermophysical properties of the refractory masonry or the temperature of the lining surface facing the chamber, its speed. The number of grooves and their depth are determined by calculation and from operating experience of furnaces.

,
где П - количество пазов в футеровке;
σ - расчетное термическое напряжение, кгс/см²;

предел прочности материала футеровки на разрыв, кгс/см²;
E - модуль упругости материала футеровки, кгс/см²;
β - удельное сокращение материала футеровки, приходящееся на 1^oC, 1/град;
Δt - изменение температуры поверхности стенки, ^oC.The number of grooves is taken equal to the number (multiplicity) of the calculated level of internal stresses σ ultimate tensile strength

,
where P is the number of grooves in the lining;
σ is the calculated thermal stress, kgf / cm ² ;

tensile strength of the lining material, kgf / cm ² ;
E is the elastic modulus of the lining material, kgf / cm ² ;
β is the specific reduction of the lining material per 1 ^o C, 1 / deg;
Δt is the change in wall surface temperature, ^o C.

 Example.

 Calculation of the number of slots P for dinas lining of a horizontal coke oven.

β = 3,5 кгс/см²;
Δt = 860^°C.
П = 27,6 • 10³ • 12,8 • 10^-6 • 860 / 3,5 = 87
При длине камеры коксования L = 14080 мм расстояние между пазами должно быть равным l = L/П = 14080/87 = 162 мм
Исходя из теоретического расчета, при длине огнеупорного изделия 325 мм в нем необходимо выполнять не менее одного паза. При аналогичном расчете пазов для вертикальной прокалочной печи вместо показателя длины печи L используется высота печи H.E = 27.6 • 10 ³ kgf / cm ² ;

β = 3.5 kgf / cm ² ;
Δt = 860 ^° C.
P = 27.6 • 10 ³ • 12.8 • 10 ^-6 • 860 / 3.5 = 87
With the length of the coking chamber L = 14080 mm, the distance between the grooves should be equal to l = L / P = 14080/87 = 162 mm
Based on the theoretical calculation, with a length of the refractory product 325 mm, it is necessary to perform at least one groove in it. In a similar calculation of the grooves for a vertical calcining furnace, the height of the furnace H is used instead of the length indicator L of the furnace.

 To enhance the protection of masonry walls from cracking, the grooves are best done slanted. In this case, even with the formation of a crack, it will be localized by the grooves and will not get spread to a greater depth. In addition, it is advisable, based on the conditions of service of refractories - to eliminate unnecessary thermal and mechanical stresses in the grooves, to perform them not rectangular, but radial with a rounded edge at the surface of the refractory product. And, finally, the slope of the grooves should be directed in the direction opposite from the doors of the coke oven, or in the direction of the main coking array. In this case, when the coking load shrinks, the grooves will serve as original guides and its head part along these guides will rush towards the main coking array - to press against it, preventing its separation and subsequent collapse when removing the coke oven doors.

 The depth of the grooves in the Dinas refractory products used for the laying of coking chambers and calcining furnaces is taken to be 12 mm based on the following considerations. The most dangerous fluctuations in the temperature of the masonry from dinas reach 12 mm. At a depth of 15 mm from the surface of the refractory product, temperature fluctuations no longer reach the dangerous limit, since at this level the volume changes of the dinas do not exceed 0.15%. The temperature fluctuations on the surface of the dinas refractory from the side of the heating channel are insignificant, since they are constantly in the conditions of heating.

Thus, the use of this invention allows:
- to increase the service life of coke, pitchox and other heating furnaces by reducing stresses in the refractory masonry and preventing its premature destruction;
- reduce the volume of current repairs and increase the production of the final product both by reducing downtime during the period of repairs, and especially this applies primarily to coke ovens - a sharp decrease in coke collapses and its return to the furnace chamber.

Claims (2)

1. The lining of the chambers of furnaces for heat treatment of carbon-containing raw materials, including interconnected refractory products, while on the surface of the refractory products facing the furnace chamber, grooves are inclined to the horizontal axis, characterized in that the grooves on the surface of the refractory products are made vertical, while refractory products with grooves are laid in the head part and the part adjacent to the loading hatches, the grooves on the surface of the refractory products have an inclination in the direction opposite to the oven doors, and if ETS grooves on the surface of the refractories is determined by the formula

where P is the number of grooves in the lining;
E is the elastic modulus of the lining material, kg • s / cm ² ;
β is the specific reduction in the lining material per 1 / ^o C;
Δt is the change in wall surface temperature, ^o C;

tensile strength of the lining material, kg • s / cm ² .  2. The lining of the furnace chamber according to claim 1, characterized in that the grooves are oval in shape with curves at the surface of the refractory product.

Images