RU2034010C1 - Technique and equipment for dry quenching of coke - Google Patents

Abstract

FIELD: coke and chemical industry. SUBSTANCE: coke in the quenching chamber is cooled at least by two flows, one of them being fed above the gas outlet zone through the upper tier of central distributor in the quantity of 20-40 percent of the whole of the volume of gas circulating in the cooling system. The distributor is located one eighth-one twelfth higher of the beveled gas ducts of the quenching chamber. EFFECT: higher efficiency and reduced burning loss. 2 cl, 1 dwg

Description

 The invention relates to techniques for dry quenching of coke and may find application in the coke industry.

 The closest analogue of the proposed invention is a technical solution described in USSR patent N 1025330.

 The essence of it is that according to the method, the cooling of coke, including passing coke under the action of gravity through the refrigerating chamber, the supply of cooling gas occurring countercurrent by at least two streams along the height of the chamber, and the removal of gas from the upper part of the chamber, its cooling and supply into the chamber, the gas is cooled to at least two different temperatures, and the higher temperature stream is supplied to the chamber above the supply point of the lower temperature gas stream.

 In a coke cooling installation, including a cooling chamber installed in series with cooling gas supply means located one above the other in the chamber height and a gas outlet manifold, a dust collecting bin connected to it, a waste heat boiler with heat exchange elements, a gas blower pipe connected to means for supplying cooling gas, each means for supplying cooling gas is connected directly by a gas-blowing pipeline to the recovery boiler, gas supply means higher temperature is connected to the recovery boiler after the first section along the gas heat exchange elements and disposed below the means for supplying gas at a lower temperature are connected to a recovery boiler, respectively, after the next downstream gas heat exchanger elements, the latter are arranged in parallel.

The disadvantages of this technical solution of the method and installation for quenching of coke are the uneven heat transfer due to the fact that it provides a one-sided lateral discharge of cooling gas. In this case, the movement of the flow of cooling gas will always be shifted towards the outlet, which leads to undercooling of coke on the back side from the outlet. Furthermore, the flow of circulating gas at a higher temperature (300 ° ^C) supplied to the chamber is provided above the feed point of stream at a lower temperature.

 With such a supply of circulating gas, effective quenching of coke will not be achieved due to the small temperature difference between coke and cooling gas.

A negative point is the passage of the entire flow of circulating gas through the entire layer of hot coke, having a temperature of 900 ^about C, which is located above the upper level of the input.

Contact of the gas with the entire volume of coke at this temperature accelerates the reaction rate of CO ₂ + C = 2CO, which is associated with an increase in the coke fumes.

 Since modern installations provide a single supply for extinguishing a large volume of hot coke (20-30 tons), when such an amount of coke gets directly into the gas circulation zone, the temperature in front of the boiler rises sharply after loading and vice versa decreases before subsequent loading, which leads to fluctuations steam generation parameters.

 All this ultimately leads to an increase in coke fumes, and therefore, to a deterioration in its quality.

 The aim of the invention is to increase the efficiency of the coke quenching process by increasing heat transfer between coke and gas.

 This goal is achieved by the fact that in a method comprising supplying coke to a quenching chamber, cooling it with gas supplied at different levels by at least two streams, and removing gas with its subsequent dust removal and heat recovery, one of the gas streams is fed above the gas removal zone in an amount of 20-40% of the total gas volume, moreover, quenching of coke in the zone located above the gas outlet is carried out in a direct flow, and lower in countercurrent to the gas.

 This goal is also achieved in a device including a vertical housing equipped with a prefabricated manifold for gas removal, as well as means for loading and unloading coke and a central circulating gas distributor with several tiers, a prefabricated manifold for gas extraction is made annular with oblique gas outlets, and the central distributor is installed in the extinguishing chamber in such a way that its upper tier is located above the oblique gas ducts by 1 / 8-1 / 12 of the diameter of the extinguishing chamber.

 These differences allow, due to the uniform heat transfer, to reduce coke waste and thereby reduce the destruction of the structure of coke pieces, i.e. increase its strength.

 In addition, in the proposed design of a device for quenching hot coke, a decrease in resistance to gas passage is achieved, which allows to increase the productivity of the quenched coke process by 10-15%. Organization of a quenching coke quenching process in two stages with cooling in the first stage as part of the total circulating gas flow leads to improving the uniformity of heat removal from red-hot coke by circulating gas along the height and cross-section of the quenching chamber, which also reduces the coke fumes. At the same time, the dustiness of the circulating gas also decreases.

 The drawing schematically shows a device for dry quenching of coke.

 The device consists of a vertical housing 1 with loading 2 and unloading 3 means connected by oblique gas vents 4 with a prefabricated annular collector 5 for exhaust gases, divided in height into two ducts. In the lower part of the vertical casing 1, a central circulating gas distributor 6 is installed with several tiers 7, 11 of circulating gas outlets to provide differentiated supply and regulation of the amount of gas in tiers. Moreover, it is installed in such a way that its upper tier 7 is located above the oblique gas vents 4 by 1 / 8-1 / 12 of the diameter of the quenching chamber 10.

 The supply of 20-40% of the circulating gas to the central distributor is carried out through the pipe 12, and 80-60% through the pipe 13. The interconnection of the structural elements ensures the presence of a pre-chamber 8 and zones of the first and second stages of the process 9 and 10, respectively.

 The essence of the method and the operation of the device is as follows.

Hot coke having a temperature of 980-1050 ^{° C} was charged to a dry quenching through the loading device 2, after which it enters the precombustion chamber 8 and then into a zone located above the discharge gases, i.e. to the first cooling stage 9, where it contacts in direct flow with 20-40% of the total volume of gas circulating in the cooling system, supplied through the pipe 12 and the upper tier 7 of the central circulating gas distributor 6, located above the oblique gas outlets 4. Then the coke is cooled in countercurrent in the area below the gas outlet, i.e. at the second stage of the process 10, the remaining amount of circulating gas: 60-80% of the volume supplied through the pipe 13 and the lower tiers 11 of the central distributor 6, located below the oblique gas vents 4.

Cooled to 150-200 ^{° C} coke is discharged through the discharge device 3.

Heated to 750-800 ^C circulating gases from the first and second stage cooling gas outlet 4 via the skew fed into annular channels (collector) 5, and then the waste heat boiler and dedusting (not shown).

Cooled to 130-140 ^C gases circulating in the closed system after recycling the captured heat when extinguishing coke is recycled through a central valve 6 for quenching the coke.

Thus, in the proposed object, in contrast to the known prototype, a zone-wise supply of cooling gas is carried out in height in the center of the chamber, which, in the presence of oblique gas outlets located around the perimeter of the chamber, leads to a more uniform distribution of circulating gas, i.e. to more uniform cooling of coke. The design of the device allows to provide a cooled to 130-140 ^{° C} circulating gas across the height of the chamber, which leads to an intensification of the process quenching of coke especially in the upper part thereof.

 In the well-known solution (prototype), coke quenching is carried out only in the once-through, in the proposed in the combined system: in the once-through (first stage) and counter-current (second stage).

In the proposed embodiment, only 60-80% of the total circulating gas volume is supplied to the zone below the oblique gas flues through the entire coke layer, and the rest (20-40%) enters the zone above the oblique gas vents. This provides a reduction in system resistance, which is a prerequisite for increasing plant productivity. Furthermore, since in the zone located below the oblique flues coke temperature is already lower ^(about 800 C) burn the coke decrease significantly.

 PRI me R. Dry quenching of coke was carried out in a model simulating the design of the proposed device.

 The operating mode was as follows.

(1) где S и ν_св удельная поверхность засыпи (м²/м³) и свободный объем межкускового пространства (м³/м³);
ν_сл- кинематическая вязкость газа;
ρ_сл- плотность циркулирующего газа;
ω- средняя скорость циркулирующего газа в камере, м/с, определяемая по следующей формуле:
ω =

(2) где V_г количество циркулирующих газов, м³/г;
t_cp средняя температура циркулирующих газов, ^оС;
F площадь сечения камеры тушения, м².The temperature of hot coke supplied to the quenching of ¹⁰⁰⁰ ° C; specific consumption of gas circulating in the system 1.3 thousand m ³ / t; the temperature of the circulating gas in the system, supplied to the coke quenching, 135 ^{° C;} circulating gas temperature after quenching coke ^of 800 C; extinguished coke temperature 180 ° ^C. The resistance of the layer of coke was determined from the formula
ΔP

(1) where S ν and _{communication} grist specific surface (m ² / m ³⁾ and space mezhkuskovogo free volume (m ³ / m ^3);
ν _SL - kinematic viscosity of the gas;
ρ _SL - the density of the circulating gas;
ω is the average velocity of the circulating gas in the chamber, m / s, determined by the following formula:
ω =

(2) where V _{g is the} amount of circulating gases, m ³ / g;
t _{cp is the} average temperature of the circulating gases, ^о С;
F cross-sectional area of the quenching chamber, m ² .

 From equation (1) it is seen that the resistance of the coke mound layer is proportional to the average gas velocity to the degree of 1.55. The speed of the circulating gas itself is determined by the quantity and its temperature, and the total resistance of the quenching zone also depends on the length of the path of passage of the circulating gas from the blast head to oblique flues.

= 4,8 мм вод.ст. где 0,4 скорость циркулирующего газа на первой ступени;
1,33 скорость циркулирующего газа в объекте-прототипе в зоне тушения м/с.So, for example, when 30% of the volume of circulating gas is supplied to the first stage of the process, the resistance of 1 m of the bed layer at the first stage of the process will be
thirty·

= 4.8 mm water column where 0.4 is the velocity of the circulating gas in the first stage;
1.33 the speed of the circulating gas in the prototype object in the quenching zone m / s.

= 17,1 мм вод.ст. где 0,93 скорость циркулирующего газа в зоне тушения по предлагаемому решению, м/с.The resistance of 1 m of the mound layer in the extinguishing zone in the second stage will be
thirty·

= 17.1 mm water column where 0.93 is the velocity of the circulating gas in the quenching zone according to the proposed solution, m / s.

 Thus, the total resistance of 1 m of the coke charge during its quenching will be 4.8 + 17.1 = 21.9 mm water column.

 If we also take into account that at the first stage of the process the path length of the circulating gas to oblique flues is reduced from 7 (in a known facility, as well as at the second stage of the process of the proposed facility) to 3 m, then the total resistance of the coke quenching system to the gas passage will be 4.8x3 + 17x7 = 133.4 mm water column

The basic object is the existing dry coke quenching unit (CTC), operating at design capacity with a specific blast rate of 1,500 nm ³ / t quenched coke with a sieve composition of coke with a grade of +80 and -25 mm, respectively 11 and 7% Content in the circulating gas СО 8% and Н ₂ 4% The actual and estimated resistance of 1 m of the coke charge layer to the quenching zone of this facility is 30, and the total resistance of the entire system is 200-210 mm water column.

 Thus, in the proposed facility, the hydraulic resistance of the entire coke quenching system is reduced by approximately 33%, which allows to increase the capacity of the extinguished coke plant by 10-15%. The same situation occurs when compared with the prototype object.

 In the table. 1 shows experiments confirming the achievement of the goal within the selected process parameters.

 From the data in table. 1 it can be seen that the supply of 20-40% of the circulating gas to the first extinguishing stage when the upper tier of the central distributor is located above the level of oblique passages at a distance of 1 / 8-1 / 12 of the diameter of the extinguishing chamber ensures the optimal operation of the installation.

 The supply of 20-40% of circulating gas to the first extinguishing stage when the upper tier of the central distributor is located above the level of oblique passages at a distance of less than 1/8 or more than 1/13 worsens the performance of the installation: in the first case, the total resistance and dustiness of the circulating gas increase, in the second the fumes and abrasion of coke increase (see table. 2).

 In the table. 3 shows comparative data on the parameters of the coke quenching process carried out in the prototype object and in the proposed technical solution for different loading of the device used.

 From the above comparison of the indicators of the known and proposed objects, it can be seen that at the same load, i.e. at the same performance, in the proposed facility higher performance is achieved, which allows you to work on the installation with a greater load, i.e. increase productivity by about 10-15%

Claims (2)

 1. The method of dry quenching of coke, including the supply of coke to the quenching chamber, cooling it with gas supplied at different levels by at least two streams, and gas removal with its subsequent dust removal and heat recovery, characterized in that, in order to increase the efficiency of the quenching process Coke due to the uniformity of its heat transfer, one of the gas flows is supplied above the gas removal zone in an amount of 20 to 40% of the total volume of direct flow to the coke, and the gas flow supplied below the gas removal zone is supplied in counterflow to the coke.  2. A device for dry quenching of coke, including a vertical casing equipped with means for loading and unloading, a circulating gas distributor with several tiers, and a collecting manifold for gas removal, characterized in that, in order to increase the efficiency of the coke quenching process by achieving uniform heat transfer , the collection manifold for gas removal is circular with oblique gas ducts, and the central circulating gas distributor is installed in the extinguishing chamber so that its upper tier is located above the oblique gas odov 1/8 to 1/12 of the diameter of the quenching chamber.

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