Method and device for fractional condensation of coal tar
阅读说明：本技术 煤焦油分级冷凝的方法及装置 (Method and device for fractional condensation of coal tar ) 是由 许建良 刘海峰 *** 于广锁 代正华 王亦飞 陈雪莉 龚欣 赵辉 梁钦锋 郭晓 于 2019-04-23 设计创作，主要内容包括：本发明公开一种煤焦油分级冷凝的方法及装置。该方法包括如下步骤：(1)含油热解煤气与水蒸气间壁式换热后,得高馏程焦油和一级热解气；(2)所述一级热解气与熔盐间壁式换热后,得中馏程焦油和二级热解气；(3)所述二级热解气与导热油间壁式换热后,得低馏程焦油和三级热解气；(4)所述三级热解气与冷却水间壁式换热后,得轻质油和不含焦油的热解气；其中,步骤(1)中,所述水蒸气的入口温度为150-250℃；步骤(2)中,所述熔盐的入口温度为200-250℃；步骤(3)中,所述导热油的入口温度为100-150℃。该方法及装置,能够实现煤焦油分级冷凝、热解气净化,同时能够回收高温显热。(The invention discloses a method and a device for fractional condensation of coal tar. The method comprises the following steps: (1) after the oily pyrolysis gas and the steam are subjected to wall-dividing heat exchange, high-distillation-range tar and first-stage pyrolysis gas are obtained; (2) after the first-stage pyrolysis gas and the molten salt are subjected to wall-dividing heat exchange, middle-distillation range tar and second-stage pyrolysis gas are obtained; (3) after the secondary pyrolysis gas and the heat conduction oil perform wall-type heat exchange, low-distillation-range tar and tertiary pyrolysis gas are obtained; (4) after the three-stage pyrolysis gas and cooling water are subjected to wall-type heat exchange, light oil and pyrolysis gas without tar are obtained; wherein, in the step (1), the inlet temperature of the water vapor is 150-250 ℃; in the step (2), the inlet temperature of the molten salt is 200-250 ℃; in the step (3), the inlet temperature of the heat transfer oil is 100-150 ℃. The method and the device can realize the fractional condensation of the coal tar and the purification of pyrolysis gas, and can recover high-temperature sensible heat.)
1. A method for fractional condensation of coal tar, characterized in that the method comprises the following steps:
(1) after the oily pyrolysis gas and the steam are subjected to wall-dividing heat exchange, high-distillation-range tar and first-stage pyrolysis gas are obtained;
(2) after the first-stage pyrolysis gas and the molten salt are subjected to wall-dividing heat exchange, middle-distillation range tar and second-stage pyrolysis gas are obtained;
(3) after the secondary pyrolysis gas and the heat conduction oil perform wall-type heat exchange, low-distillation-range tar and tertiary pyrolysis gas are obtained;
(4) after the three-stage pyrolysis gas and cooling water are subjected to wall-type heat exchange, light oil and pyrolysis gas without tar are obtained;
wherein, in the step (1), the inlet temperature of the water vapor is 150-250 ℃; in the step (2), the inlet temperature of the molten salt is 200-250 ℃; in the step (3), the inlet temperature of the heat transfer oil is 100-150 ℃.
2. The method for fractional condensation of coal tar according to claim 1, wherein the cooling water after heat exchange and the water vapor obtained after recuperative countercurrent heat exchange of the heat transfer oil are subjected to recuperative countercurrent heat exchange with the oil-containing pyrolysis gas;
and/or the cooling water after heat exchange and the water vapor obtained after heat exchange of the molten salt dividing wall type countercurrent flow are subjected to the heat exchange and then subjected to the oil-containing pyrolysis coal gas dividing wall type countercurrent flow heat exchange.
3. The method for fractional condensation of coal tar as claimed in claim 1, wherein in step (1), the heat exchange is counter-current heat exchange, and the outlet temperature of the water vapor is 350-470 ℃.
4. The method for fractional condensation of coal tar according to claim 1, wherein in step (2), the molten salt is a mixed salt of potassium nitrate and sodium nitrate; wherein the molar ratio of potassium nitrate to sodium nitrate is preferably 1:4-1: 1;
and/or, in the step (2), the heat exchange is countercurrent heat exchange, and the outlet temperature of the molten salt is 250-400 ℃, preferably 300-400 ℃.
5. The method for fractional condensation of coal tar according to claim 1, wherein in the step (3), the inlet temperature of the heat transfer oil is 100-120 ℃;
and/or in the step (3), the heat conduction oil is silicone oil;
and/or, in the step (3), the heat exchange is countercurrent heat exchange, and the outlet temperature of the heat transfer oil is 200-.
6. The method for fractional condensation of coal tar according to claim 1, wherein in step (4), the inlet temperature of the cooling water is 10-40 ℃, preferably below 30 ℃, more preferably 10-30 ℃;
and/or in the step (4), the heat exchange is countercurrent heat exchange, and the outlet temperature of the cooling water is 100-140 ℃.
7. The method for fractional condensation of coal tar according to claim 1 or 2, characterized in that in step (1), the flow rate of the oil-containing pyrolysis gas is 3000-3/h；
And/or in the step (1), the temperature of the oil-containing pyrolysis gas is 550-700 ℃;
and/or, in the step (1), the water vapor is saturated water vapor;
and/or, in the step (1), the flow rate of the water vapor is 1.50-17t/h, preferably 2.1-17 t/h;
and/or, in the step (2), the flow rate of the molten salt is 13.1-75 t/h;
and/or in the step (3), the flow rate of the heat conduction oil is 6.1-60 t/h;
and/or, in the step (4), the flow rate of the cooling water is 1.6-15.1 t/h.
8. A coal tar fractional condensation device is characterized by comprising an oil-containing pyrolysis gas conveying pipeline, a first-stage condenser, a first-stage separator, a second-stage condenser, a second-stage separator, a third-stage condenser, a third-stage separator, a fourth-stage condenser and a fourth-stage separator; the first-stage condenser, the second-stage condenser, the third-stage condenser and the fourth-stage condenser are all dividing wall type heat exchangers; the oil-containing pyrolysis gas conveying pipeline is sequentially communicated with a hot fluid channel of the first-stage condenser, the first-stage separator, a hot fluid channel of the second-stage condenser, the second-stage separator, a hot fluid channel of the third-stage condenser, the third-stage separator, a hot fluid channel of the fourth-stage condenser and the fourth-stage separator; the device also comprises a water vapor conveying pipeline, a molten salt conveying pipeline, a heat-conducting oil conveying pipeline and a cooling water conveying pipeline which are respectively communicated with the cold fluid channel of the first-stage condenser, the cold fluid channel of the second-stage condenser, the cold fluid channel of the third-stage condenser and the cold fluid channel of the fourth-stage condenser.
9. The apparatus for the fractional condensation of coal tar according to claim 8, wherein the first stage separator, the second stage separator, the third stage separator and the fourth stage separator are in the form of cyclones, heavy settling separators or contact separators, preferably cyclones;
and/or the device also comprises a first heat exchanger, and a cold fluid channel of the four-stage condenser is sequentially communicated with a cold fluid channel of the first heat exchanger and a cold fluid channel of the first-stage condenser; a cold fluid channel of the third-stage condenser is communicated with a hot fluid channel of the first heat exchanger to form a heat-conducting oil circulation channel; the first heat exchanger is preferably a waste boiler;
and/or the device also comprises a second heat exchanger, and a cold fluid channel of the four-stage condenser is sequentially communicated with a cold fluid channel of the second heat exchanger and a cold fluid channel of the first-stage condenser; a cold fluid channel of the secondary condenser is communicated with a hot fluid channel of the second heat exchanger to form a molten salt circulation channel; the second heat exchanger is preferably a waste boiler.
10. The apparatus for fractional condensation of coal tar according to claim 8 or 9, wherein the steam delivery conduit is connected to the primary condenser in such a manner that the cold and hot fluids are subjected to countercurrent heat exchange in the primary condenser;
and/or the molten salt conveying pipeline and the secondary condenser are connected in a manner that cold and hot fluids perform countercurrent heat exchange in the secondary condenser;
and/or the connection relationship between the heat conduction oil conveying pipeline and the three-stage condenser enables cold and hot fluid to perform countercurrent heat exchange in the three-stage condenser;
and/or the cooling water conveying pipeline is connected with the four-stage condenser in a connecting relationship, so that cold and hot fluids can perform countercurrent heat exchange in the four-stage condenser.
Technical Field
The invention relates to a method and a device for fractional condensation of coal tar.
Background
The energy reserves of China are rich in coal, less in gas and lean in oil. In 2017, coal accounts for 60.4% of the whole energy consumption structure, while in other energy consumption, the dependence of petroleum and natural gas on import is higher. The main form of coal utilization in China is direct combustion, which accounts for about 80% of the total coal consumption. The coal gas and tar with low cost are obtained by pyrolyzing the large amount of coal for power, and the residual semicoke is sent to a boiler for combustion and power generation, so that the resource utilization level and the utilization value of the coal can be greatly improved, and the shortage of oil gas supply in China is relieved.
The existing process for preparing tar by Coal pyrolysis adopts a mild method to extract liquid fuel and chemicals from Coal, and representative main Coal pyrolysis processing technologies at abroad comprise a Lurgi three-section furnace (L-S) low-temperature upgrading process in Germany, a Lurgi-Ruhrgas (L-R) upgrading process, a brown Coal solid upgrading heat carrier (ETCH-175) process in the former Soviet Union, a mild gasification (Encoal) process in the United states, a Toscoa1 process, a Western upgrading (Garrett) process, a Coal Oil Energy Development (COED) process, CCTI, a fluidized bed fast pyrolysis process (CSIRO) in Australia and a Japanese Coal fast upgrading technology. The preparation process of the pyrolysis tar is also proposed in turn by the Zhejiang university, the Qinghua university, the Chinese academy of sciences process engineering research institute, the engineering thermophysical research institute and the like in China.
The oil-gas separation of the high-temperature oil-containing pyrolysis gas is one of key technologies for preparing pyrolysis tar and fuel gas, currently, the coal pyrolysis technology generally adopts a direct spraying process to condense and recover tar, so that the pyrolysis gas and the tar are separated, and then the tar is recovered.
However, due to the complex tar components and wide molecular weight distribution, the prior art is difficult to realize the separation of oil products according to grades and recover high-temperature sensible heat.
Disclosure of Invention
The invention aims to solve the technical problem of providing a novel coal tar fractional condensation method and a novel coal tar fractional condensation device for overcoming the defects that the prior art is difficult to realize oil product separation according to grade and recover high-temperature sensible heat. The method and the device for fractional condensation of the coal tar can realize fractional condensation of the coal tar and purification of pyrolysis gas, and can recover high-temperature sensible heat.
The invention solves the technical problems through the following technical scheme:
the invention provides a method for fractional condensation of coal tar, which comprises the following steps:
(1) after the oily pyrolysis gas and the steam are subjected to wall-dividing heat exchange, high-distillation-range tar and first-stage pyrolysis gas are obtained;
(2) after the first-stage pyrolysis gas and the molten salt are subjected to wall-dividing heat exchange, middle-distillation range tar and second-stage pyrolysis gas are obtained;
(3) after the secondary pyrolysis gas and the heat conduction oil perform wall-type heat exchange, low-distillation-range tar and tertiary pyrolysis gas are obtained;
(4) after the three-stage pyrolysis gas and cooling water are subjected to wall-type heat exchange, light oil and pyrolysis gas without tar are obtained;
wherein, in the step (1), the inlet temperature of the water vapor is 150-250 ℃; in the step (2), the inlet temperature of the molten salt is 200-250 ℃; in the step (3), the inlet temperature of the heat transfer oil is 100-150 ℃.
In the method, the temperature of the water vapor, the temperature of the molten salt and the temperature of the heat conducting oil are controlled within the ranges, so that the good fluidity of the coal tar attached to the wall can be ensured, and further the fractional condensation of the coal tar is realized.
In the above method, preferably, the cooling water after heat exchange and the water vapor obtained after the heat transfer oil dividing wall type countercurrent heat exchange are subjected to dividing wall type countercurrent heat exchange with the oil-containing pyrolysis gas. The scheme can produce high-grade water vapor as a byproduct.
In the method, preferably, the cooling water after heat exchange and the water vapor obtained after the heat exchange of the molten salt dividing wall type countercurrent heat exchange are subjected to the dividing wall type countercurrent heat exchange with the oil-containing pyrolysis gas. The scheme can produce high-grade water vapor as a byproduct.
In the step (1), the flow rate of the oil-containing pyrolysis gas is preferably 3000-3H is used as the reference value. The temperature of the oil-containing pyrolysis gas is preferably 550-700 ℃.
In the step (1), the water vapor is preferably saturated water vapor. The flow rate of the water vapor is preferably 1.50 to 17t/h, more preferably 2.1 to 17 t/h. When the heat exchange is a countercurrent heat exchange, the outlet temperature of the water vapor is preferably 350-470 ℃.
In step (1), the high boiling range tar is referred to as tar with a boiling point of >450 ℃ in the conventional sense of the art.
In the step (2), the molten salt is preferably a mixed salt of potassium nitrate and sodium nitrate. Wherein the molar ratio of potassium nitrate to sodium nitrate is preferably 1:4 to 1: 1. The flow rate of the molten salt is preferably 13.1 to 75 t/h. When the heat exchange is a countercurrent heat exchange, the outlet temperature of the molten salt is preferably 250-400 ℃, more preferably 300-400 ℃.
In the step (2), the medium distillation range tar refers to tar with a boiling point of more than 250 ℃ and less than or equal to 450 ℃ according to the conventional meaning in the field.
In the step (3), the inlet temperature of the heat transfer oil is preferably 100-120 ℃.
In the step (3), the heat conducting oil is preferably silicone oil. The flow rate of the heat conducting oil is preferably 6.1-60 t/h. When the heat exchange is a countercurrent heat exchange, the outlet temperature of the heat transfer oil is preferably 200-.
In the step (3), the low-distillation-range tar refers to tar with a boiling point of more than 150 ℃ and less than or equal to 250 ℃ according to the conventional meaning in the field.
In the step (4), the inlet temperature of the cooling water may be the temperature of the cooling water conventionally used in the art, and may be, for example, 10 to 40 ℃, preferably 30 ℃ or lower, and may be, for example, 10 to 30 ℃. The flow rate of the cooling water is preferably 1.6-15.1 t/h. When the heat exchange is a countercurrent heat exchange, the outlet temperature of the cooling water is preferably 100-140 ℃.
In the step (4), the light oil refers to tar with a boiling point of more than 50 ℃ and less than or equal to 150 ℃ according to the conventional meaning in the field.
The invention also provides a device for coal tar fractional condensation, which comprises an oil-containing pyrolysis gas conveying pipeline, a first-stage condenser, a first-stage separator, a second-stage condenser, a second-stage separator, a third-stage condenser, a third-stage separator, a fourth-stage condenser and a fourth-stage separator; the first-stage condenser, the second-stage condenser, the third-stage condenser and the fourth-stage condenser are all dividing wall type heat exchangers; the oil-containing pyrolysis gas conveying pipeline is sequentially communicated with a hot fluid channel of the first-stage condenser, the first-stage separator, a hot fluid channel of the second-stage condenser, the second-stage separator, a hot fluid channel of the third-stage condenser, the third-stage separator, a hot fluid channel of the fourth-stage condenser and the fourth-stage separator; the device also comprises a water vapor conveying pipeline, a molten salt conveying pipeline, a heat-conducting oil conveying pipeline and a cooling water conveying pipeline which are respectively communicated with the cold fluid channel of the first-stage condenser, the cold fluid channel of the second-stage condenser, the cold fluid channel of the third-stage condenser and the cold fluid channel of the fourth-stage condenser.
After heat exchange is carried out between the oil-containing pyrolysis gas and water vapor in a primary condenser, the oil-containing pyrolysis gas enters a primary separator for oil-gas separation, and high-distillation-range tar and primary pyrolysis gas are obtained; the first-stage pyrolysis gas and the molten salt exchange heat in a second-stage condenser, and then enter a second-stage separator for oil-gas separation to obtain middle-distillation range tar and second-stage pyrolysis gas; after the heat exchange between the second-level pyrolysis gas and the heat conduction oil is carried out in the third-level condenser, the second-level pyrolysis gas and the heat conduction oil enter a third-level separator for oil-gas separation, and low-distillation-range tar and third-level pyrolysis gas are obtained; and after the heat exchange between the third-stage pyrolysis gas and cooling water is carried out in a four-stage condenser, the third-stage pyrolysis gas and the cooling water enter a four-stage separator for oil-gas separation, and light oil and pyrolysis gas without tar are obtained.
In the above apparatus, the first stage separator, the second stage separator, the third stage separator and the fourth stage separator may be in the form of a cyclone separator, a heavy settling separator or a contact separator, preferably a cyclone separator.
In the above apparatus, preferably, the apparatus further includes a first heat exchanger, and the cold fluid channel of the quaternary condenser is sequentially communicated with the cold fluid channel of the first heat exchanger and the cold fluid channel of the primary condenser; and a cold fluid channel of the third-stage condenser is communicated with a hot fluid channel of the first heat exchanger to form a heat-conducting oil circulation channel. More preferably, the first heat exchanger is a waste boiler. The two technical schemes can produce high-grade steam as a byproduct.
In the above apparatus, preferably, the apparatus further includes a second heat exchanger, and the cold fluid channel of the quaternary condenser is sequentially communicated with the cold fluid channel of the second heat exchanger and the cold fluid channel of the primary condenser; and a cold fluid channel of the secondary condenser is communicated with a hot fluid channel of the second heat exchanger to form a molten salt circulation channel. More preferably, the second heat exchanger is a waste boiler. The two technical schemes can produce high-grade steam as a byproduct.
In the above device, preferably, the connection relationship between the steam delivery pipe and the primary condenser is such that cold and hot fluids perform countercurrent heat exchange in the primary condenser.
In the above apparatus, preferably, the molten salt delivery pipe is connected to the secondary condenser in such a manner that the cold and hot fluids perform countercurrent heat exchange in the secondary condenser.
In the above device, preferably, the connection relationship between the heat transfer oil delivery pipe and the tertiary condenser enables counter-current heat exchange between cold and hot fluids in the tertiary condenser.
In the above device, preferably, the cooling water delivery pipe is connected to the four-stage condenser in such a manner that the cold and hot fluids perform countercurrent heat exchange in the four-stage condenser.
In the above apparatus, preferably, the apparatus further includes a high distillation range tar storage tank, and the high distillation range tar storage tank is used for collecting the high distillation range tar discharged from the first-stage condenser.
In the above apparatus, preferably, the apparatus further includes a middle distillation range tar storage tank, and the middle distillation range tar storage tank is used for collecting the middle distillation range tar discharged by the secondary condenser.
In the above apparatus, preferably, the apparatus further includes a low distillation range tar storage tank, and the low distillation range tar storage tank is used for collecting the low distillation range tar discharged from the three-stage condenser.
In the above apparatus, preferably, the apparatus further includes a light oil storage tank for collecting light oil discharged from the four-stage condenser.
The above preferred conditions can be arbitrarily combined to obtain preferred embodiments of the present invention without departing from the common general knowledge in the art.
The reagents and starting materials used in the present invention are commercially available.
The positive progress effects of the invention are as follows: the method and the device for fractional condensation of the coal tar can realize fractional condensation of the coal tar and purification of pyrolysis gas, and can recover high-temperature sensible heat.
Drawings
FIG. 1 is a schematic diagram of an apparatus used in an embodiment of the present invention.
Description of reference numerals:
oil-containing pyrolysis
First-
Two-
Two-
Three-
Three
Four-
Four-
Molten
Heat transfer
Cooling
High distillation range
Middle distillation
Low distillation range
Light
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.
In the following examples and comparative examples, the coal quality data used are shown in table 1.
TABLE 1 Properties of the feed coal
TABLE 2
Generally, the oil-containing pyrolysis gas contains tar 10% (coal-based), and this value means that the tar in the oil-containing pyrolysis gas accounts for 10% by mass of the coal from which the oil-containing pyrolysis gas is produced; in the following examples and comparative examples, the yield of tar (coal-based) with a high distillation range (boiling point >450 ℃) means that the obtained tar with a high distillation range accounts for the mass percentage of the coal which generates the oil-containing pyrolysis gas; the yield of tar (coal base) in the middle distillation range (the boiling point is more than 250 ℃ and less than or equal to 450 ℃) refers to the mass percentage of the obtained middle distillation range tar in the coal generating the oil-containing pyrolysis gas; the yield of tar (coal base) with low distillation range (the boiling point is more than 150 ℃ and less than or equal to 250 ℃) means that the obtained tar with the low distillation range accounts for the mass percent of the coal generating the oil-containing pyrolysis gas; the yield of tar (coal base) of the light oil (the boiling point is more than 50 ℃ and less than or equal to 150 ℃) means that the obtained light oil accounts for the mass percent of the coal generating the oil-containing pyrolysis gas.
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