EP3498805A1

EP3498805A1 - Process for producing modified tar

Info

Publication number: EP3498805A1
Application number: EP16912782.6A
Authority: EP
Inventors: Kyung Tae Park; Byung Il Kim; Seung Jae Lee
Original assignee: Posco Co Ltd
Current assignee: Posco Holdings Inc
Priority date: 2016-08-08
Filing date: 2016-10-27
Publication date: 2019-06-19
Also published as: WO2018030584A1; KR101797134B1; CN109790469A; EP3498805A4

Abstract

The present invention relates to a process for producing modified tar, and can provide a process for producing modified tar, comprising: a first distillation step of removing water and/or a first light oil, of which the boiling point is from (180°C to the boiling point of naphthalene), or lower, by distilling tar, which is a by-product of a cokes process, at a temperature from 100°C to a temperature from (180°C to the boiling point of naphthalene), or lower, in a first distillation tower; a second distillation step of respectively separating modified tar; a second light oil of which the boiling point is lower than that of naphthalene; and a mixed oil comprising naphthalene, wash oil, and modified tar by distilling the product, from which water and/or the first light oil was removed in the first distillation step, at 300°C to 350°C in a second distillation tower; and a third distillation step of respectively separating naphthalene, the wash oil, and the modified tar by distilling, at 220°C to 260°C in a third distillation tower, the mixed oil of the product of the second distillation step.

Description

[Technical Field]

The present invention relates to a process for producing modified tar.

[Background of Invention]

At the steelworks, a large amount of molten metal is produced in the blast furnace. The raw materials, coal and iron ore are required for the production of molten metal, and the coal and iron ore are processed rather than directly pour into the blast furnace, which may cause problems such as air permeability. Specifically, coal is converted into cokes, and iron ore is converted into sintered ore or pellets, and then introduced into a blast furnace. In particular, cokes plays a role in improving the air permeability and supplying heat source in the blast furnace, and cokes are produced by carbonization of coking coal in a coke oven at high temperature.
The coking coal is introduced into a boat or a train and goes through the crusher to reduce the grain size and blends in the blending bin to adjust the components. Blended coal is charged into a coke oven and converted into cokes by a carbonization. The coke oven consists of a number of independent combustion chambers and carbonization chambers. The Coke Oven Gas (COG) combustion in the combustion chambers supplies energy to the carbonization chamber, which leads to a carbonization of coal.
When carbonization is carried out in the carbonization chambers, volatile components comprised in coal would escape from the coke oven through the riser tube in a gas form. It is referred to as Coke Oven Gas (COG) and it is an important energy source for the steelworks. Further, the unrefined coke oven gas is referred to as Crude COG. Crude COG is refined through a desulfurization apparatus for removing sulfur and various scrubbers to produce COG, which are used in the steelworks. Tar and heavy tar are deposited when Crude COG goes through a tar decanter. Tar, which is a by-product of the cokes process, is stored in storage tanks for sale.
The strength of the cokes introduced into the blast furnace is an important indicator for a quality of cokes. It is important to maintain the strength of cokes high because if the strength is low, the cokes will be broken and cause problems in the blast furnace and transference. If the strength of cokes is high, the cost could be saved by mixing a pulverized coal, which has poor quality but is relatively cheaper than coking coal, and meet a certain level of strength at the same time. Many steelworks endeavor to improve the strength of cokes.
Further, conventionally, there has been an attempt to increase the strength by mixing tar with coal for cokes. However, when tar is used in a crude form, severe odor and clogging of the after-treatment pipe due to naphthalene could be caused. In order to prevent the problems above, a method of manufacturing a coking additive for coal was devised by removing only the odorous part. However, the above method has a disadvantage that a naphthalene removal apparatus is required in the COG refining process.

[Description]

[Problems to be solved]

The present invention is to provide a process for producing modified tar capable of improving adverse effects of conventional tar coking additives by removing odorous light oil and naphthalene that causes a pipe clogging after the cokes process, from tar, which is a by-product of the cokes process.
Further, the light oil separated through the modified tar production process can be used or sold as fuel, naphthalene can be sold separately, and the wash oil can be used in the conversion process, thereby improving the economic efficiency.

[Means to Solve Problems]

In one embodiment of the present invention is a process for producing modified tar, comprising: a first distillation step of removing water and/or a first light oil, of which the boiling point is from (180°C to the boiling point of naphthalene), or lower, by distilling tar, which is a by-product of a cokes process, at a temperature from 100°C to a temperature from (180°C to the boiling point of naphthalene), or lower, in a first distillation tower; a second distillation step of respectively separating modified tar, a second light oil of which the boiling point is lower than that of naphthalene, and a mixed oil comprising naphthalene, wash oil, and modified tar by distilling the product, from which water and/or the first light oil was removed in the first distillation step, at 300°C to 350°C in a second distillation tower; and a third distillation step of respectively separating naphthalene, the wash oil, and the modified tar by distilling, at 220°C to 260°C in a third distillation tower, the mixed oil of the product of the second distillation step.
In the second distillation step, the product, from which water and/or the first light oil was removed in the first distillation step, may be heated to 300°C to 350°C and then transferred to the second distillation tower.
In the third distillation step, the mixed oil of the product from the second distillation step may be transferred to the third distillation tower without additional heating.
The modified tar separated from the second distillation tower and/or the third distillation tower is recycled to the second distillation tower.
In the second distillation step, steam is supplied to the second distillation tower.
After the third distillation step, the step of re-boiling the modified tar separated in the third distillation step through a heater and then re-introducing into the third distillation tower may be further comprised.
In the second distillation step, the product, from which water and/or the first light oil was removed in the first distillation step, and the modified tar separated from the second distillation tower and/or the third distillation tower, which is recycled, may be heated to 300°C to 350°C and then transferred to the second distillation tower.
Prior to the first distillation step, the step of heating tar, which is a by-product of the cokes process, through a heat exchanger or a heater, and introducing tar into the first distillation tower, may be further comprised.
The modified tar may be used for a coking additive to be added to the producing process for cokes.

[The Effects of Invention]

The present invention provides a process for producing a modified tar capable of improving adverse effects of tar coking additives by removing odorous light oil and naphthalene that causes a pipe clogging after the cokes process, from tar, which is a by-product of the cokes process.
Further, the light oil separated through the modified tar production process can be used or sold as fuel, naphthalene can be sold separately, and the wash oil can be used in the conversion process, thereby improving the economic efficiency.

[Brief Description of the Drawings]

Figure 1 is an exemplary schematic diagram of an apparatus that may be used in modified tar production process as an embodiment of the present invention.

[Detailed Descriptions of Invention]

Hereinafter, embodiments of the present invention will be described in details. However, these are presented as an exemplary purpose and the present invention is not limited thereto, and the present invention is only defined by the claim scope described in the below.
The terms first, second, third, and the like are used to describe various portions, components, regions, layers and/or sections, but are not limited thereto. These terms are only used to distinguish one portion, component, region, layer or section from another portion, component, region, layer or section. Thus, a first portion, component, region, layer or section described below may be referred to as a second portion, component, region, layer or section without departing from the scope of the present invention.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not specifically state the opposite meaning thereof. The "comprises" means that a particular characteristic, region, integer, step, motion, element and/or component is specified and that does not exclude the presence or addition of other characteristics, regions, integers, steps, motions, elements, and/or components.
Unless defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms defined in the commonly used dictionary are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.
One embodiment of the present invention is to provide a process for producing modified tar by modifying tar added as a coking additive to improve a quality of cokes in a cokes production process. Specifically, odorous substance of light oil, and naphthalene that causes clogging in the process after the coke process are removed from tar, which is a by-product of the conventional cokes process, to provide a modified tar production process capable of improving the adverse effects of coking additives.
More specifically, one embodiment of the present invention is a process for producing modified tar, comprising: a first distillation step of removing water and/or a first light oil, of which the boiling point is from (180°C to the boiling point of naphthalene), or lower, by distilling tar, which is a by-product of a cokes process, at a temperature from 100°C to a temperature from (180°C to the boiling point of naphthalene), or lower, in a first distillation tower; a second distillation step of respectively separating modified tar, a second light oil of which the boiling point is lower than that of naphthalene, and a mixed oil comprising naphthalene, wash oil, and modified tar by distilling the product, from which water and/or the first light oil was removed in the first distillation step, at 300°C to 350°C in a second distillation tower; and a third distillation step of respectively separating naphthalene, the wash oil, and the modified tar by distilling, at 220°C to 260°C in a third distillation tower, the mixed oil of the product of the second distillation step.
(180°C to naphthalene boiling point) used herein means a particular point of temperature between 180°C and a boiling point of naphthalene, and A to B means A or more and B or less, unless defined otherwise.
Figure 1 is an exemplary schematic diagram of an apparatus that can be used in the modified tar production process as one embodiment of the present invention. Thus, such apparatus can be modified into various forms. Hereinafter, the modified tar production process of one embodiment of the present invention will be described with reference to FIG. 1
Tar, which is a by-product of the cokes process, is maintained at a temperature of 70°C to 100°C to prevent a hardening in a storage tank (not shown). Thereafter, the storage tank is connected to the first distillation tower 101 through a pipe, and tar is heated to a temperature of at least 110°C and (180°C to a boiling point of naphthalene), or lower, through a heat exchanger or a heater (not shown). The heated tar is distilled in the first distillation tower. Specifically, water escapes to the top in the form of water vapor, and the remaining tar without water is lowered to the bottom. Thus, the temperature of tar can be easily increased in the first heater 104 as a subsequent step. At this time, a first light oil having a boiling point of (180°C to the boiling point of naphthalene), or lower, is also evaporated and can escape to the top of the first distillation tower in a gas state. Thus, water escaped to the top and the first light oil having a boiling point of (180°C to boiling point of naphthalene), or lower, are separated into a mixed state in the separately equipped water separator 106. Thereafter, water and the first light oil are separated through the water separator 106, so that only the first light oil can be separated into the separate first light oil storage tank 107. The first light oil thus separated can be used as a fuel in the cokes production process or a modified tar production process, or can be sold separately.
Tar, from which water and the first light oil is removed and which is lowered to the bottom of the first distillation tower, are heated to a temperature of 300°C to 350°C through the first heater 104 equipped separately, and then transferred to the second distillation tower 102. The distillation temperature of the second distillation step is limited as described above because it is easy to separate the wash oil within the above range, and when the temperature exceeds 350°C, unnecessary energy is supplied and the disadvantageous energy loss occurs. In a second distillation tower, a second light oil composed of components having lower boiling point than naphthalene (about 218°C); naphthalene, wash oil, mixed oil with modified tar, and modified tar. The wash oil is a substance composed of components having higher boiling point than naphthalene, and is generally a liquid in the form of a mixture having a boiling point in the range of about 230°C to 330°C. At this time, the second distillation tower 102 can be operated at normal pressure, and steam is introduced through the steam pipe 111 to increase the efficiency of the separation. By introducing steam, the flow rate inside the second distillation tower 102 increases, so that the separation efficiency can be improved.
The second light oil from the second distillation tower 102 can be transferred to the water separator 106 and mixed with the first light oil, water vapor from the first distillation tower. Thereafter, water and light oils can be separated through the water separator 106 as described above, and the separated light oil can be used as a fuel in a cokes production process, a modified tar production process, or sold separately. It is also possible to further include water vapor with the remaining second light oil separated from the second distillation tower 102.
The mixed oil separated in the second distillation tower 102 is transferred to the third distillation tower 103 without further heating and is distilled in the third distillation tower 103 at a temperature of 220°C to 260°C
Thus, naphthalene is separated from the top of the third distillation tower 103 and stored in the naphthalene storage tank 108 in a liquid state. In the middle portion of the third distillation tower 103, the wash oil is separated and stored in the wash oil storage tank 109, so that it can be used in a conversion plant or the like. At the bottom of the third distillation tower 103, the modified tar is separated and transferred to the modified tar storage tank 110 and stored. By performing the third distillation step in the temperature range above, the distillation of naphthalene is possible and the wash oil can be separated to about 4% level.
After the third distillation step in the third distillation tower 103, the modified tar separated in the third distillation step is re-boiled through the second heater 105, and then re-introduced into the third distillation tower (103). Thus, by further distilling the separated modified tar in the third distillation tower 103, the purity of the modified tar can be further improved.
The modified tar discharged from the bottom of the second distillation tower 102 and/or the bottom of the third distillation tower 103 can be recycled to the second distillation tower 102 through the circulation pipe 112, equipped separately. Specifically, water separated from the bottom of the first distillation tower 101 and/or the product, from which the first light oil is removed, are mixed before being heated by the first heater 104 described above, and then can be heated at the first heater 104 and transferred to the second distillation tower 102. Thus, the recycled modified tar is subject to the repeating distillations in the second distillation tower 102 and the third distillation tower 103, so that the purity can be improved.
The modified tar finally obtained through the above-described process can be mixed, as a coking additive, with the coking coal to increase the strength of the coking coal in the cokes production process. In addition, it is possible to remove odor generated from the conventional unmodified tar and to prevent the pipe clogging caused by naphthalene, thereby improving the strength of the coking coal while improving the adverse effects of the conventional additives. In addition, light oil, naphthalene, and wash oil, which are by-products of the modified tar production process, can be sold separately, and additional income can be incurred.

As explained in the above, it will be understood by those skilled in the art that various changes and modifications may be made without departing from idea and scope of the claims described in the below.

[Reference Signs]

101 : The first distillation tower	102 : The second distillation tower
103 : The third distillation tower	104 : The first heater
105 : The second heater	106 : Water separator
107 : Light oil storage tank	108 : Naphthalene storage tank
109 : Wash oil storage tank	110 : Modified tar storage tank
111 : Steam pipe	112 : Circulation pipe

Claims

A process for producing modified tar, comprising:
a first distillation step of removing water and/or a first light oil, of which the boiling point is (180°C to the boiling point of naphthalene), or lower, by distilling tar, which is a by-product of a cokes process, at a temperature from 100°C to (180°C to the boiling point of naphthalene), or lower, in a first distillation tower;

a second distillation step of respectively separating modified tar; a second light oil, of which the boiling point is lower than that of naphthalene; and a mixed oil comprising naphthalene, wash oil, and modified tar by distilling the product, from which water and/or the first light oil was removed in the first distillation step, at 300°C to 350°C in a second distillation tower; and

a third distillation step of respectively separating naphthalene, wash oil, and modified tar by distilling, at 220°C to 260°C in a third distillation tower, the mixed oil of the product of the second distillation step.
The process of Claim 1,
in the second distillation step,
wherein the product, from which water and/or the first light oil was removed in the first distillation step, is heated to 300°C to 350°C and transferred to the second distillation tower.
The process of Claim 2,
in the third distillation step,
wherein the mixed oil of the product from the second distillation step is transferred to the third distillation tower without additional heating.
The process of Claim 3,
wherein the modified tar separated from the second distillation tower and/or the third distillation tower is recycled to the second distillation tower.
The process of Claim 1,
in the second distillation step, steam is supplied to the second distillation tower.
The process of Claim 1,
after the third distillation step,
further comprising the step of re-boiling the modified tar separated in the third distillation step through a heater and then re-introducing the modified tar into the third distillation tower.
The process of Claim 4,
in the second distillation step,
wherein the product, from which water and/or the first light oil was removed in the first distillation step, and the modified tar separated from the second distillation tower and/or the third distillation tower, which is recycled, are heated to 300°C to 350°C and then introduced to the second distillation tower.
The process of Claim 1,
prior to the first distillation step,
further comprising the step of heating tar, which is a by-product of the cokes process, through a heat exchanger or a heater, and introducing tar into the first distillation tower.
The process of Claim 1,
wherein the modified tar is:
used for a coking additive to be added to the producing process for cokes.