A coal tar hydrogenation system that saves energy and efficiently utilizes acidic dry gas

Abstract

The invention discloses a coal tar hydrogenation system for energy-saving and efficient utilization of acidic dry gas, comprising a dehydration tower, a coal tar fractionation tower, a coal tar pitch tank, an intermediate light oil tank, an intermediate medium oil tank, a new hydrogen pipeline, a first reactor, a second reactor, a third reactor, a fourth reactor, a fifth reactor, a high-pressure separator, a low-pressure separator, a pre-fractionation tower, a fractionation tower, a naphtha stabilization tower, a side-line tower, a 1# light coal tar tank, a 2# light coal tar tank, a heating furnace and a desulfurization device. The scheme desulfurizes and dries the acidic dry gas obtained in the low-pressure separator, the pre-fractionation tower and the naphtha stabilization tower, and then sends it to the heating furnace for combustion. The heating furnace provides heat for the coal tar fractionation tower, thereby avoiding the waste of resources and environmental pollution caused by the emptying and combustion of the acidic dry gas in the traditional coal tar hydrogenation system.

Description

Technical field:

[0002] The invention relates to a coal tar hydrogenation system, in particular to a coal tar hydrogenation system which can save energy and efficiently utilize acidic dry gas. Background technology:

[0004] my country has abundant coal reserves, and the diversified energy development strategy based on coal has become an important means for my country to adjust and optimize its energy structure. Among them, the technology of producing gasoline, diesel and its additives by hydrogenating and reforming coal tar produced as a by-product of coal pyrolysis, coking or gasification can fully improve the comprehensive utilization value of coal tar and solve the problems of environmental pollution caused by the low-value utilization of coal tar.

[0005] The raw coal tar contains a large amount of impurities such as moisture, sulfur, nitrogen, and metal salts. The coal tar hydrogenation technology first removes moisture and heavy coal tar through pretreatment, and then removes sulfur, nitrogen and other environmentally polluting components in the coal tar through hydrogenation reaction, while removing metals. While removing impurities in the coal tar, some heavy components are converted into light components to produce environmentally friendly C1-C4 light hydrocarbons, naphtha, kerosene, diesel and tail oil.

[0006] However, the acidic dry gas produced by the traditional coal tar hydrogenation system is sent to the flare for combustion and discharge through the vent main. On the one hand, the acidic dry gas contains a small amount of combustible gases such as methane, ethane, hydrogen, carbon monoxide, etc., which have a certain calorific value and are directly discharged and burned, resulting in a waste of resources; on the other hand, the acidic dry gas contains a small amount of hydrogen sulfide, which is easy to pollute the environment if it is directly discharged.

[0007] In addition, after coal tar and hydrogen react with the catalyst, qualified product oil can be obtained after multi-stage separation. In the separator, not only are methane, ethane, hydrogen, carbon monoxide and other gases discharged from the top of the separator to achieve gas-liquid separation, but also the liquid is stratified, and acidic wastewater is discharged from the bottom. The remaining products enter the subsequent system for further separation to obtain the final qualified product oil. Acidic wastewater is generally discharged through a pipeline and sent to the wastewater treatment system for treatment. However, combustible gases are still dissolved in the acidic wastewater, and the low-pressure separator mainly achieves gas-liquid separation, and the separation effect of water and oil is poor. Therefore, the discharged acidic wastewater still contains a large amount of oil, which not only wastes resources, but also makes subsequent treatment difficult. Summary of the invention:

[0009] In order to solve the above technical problems, the object of the present invention is to provide a coal tar hydrogenation system which is energy-saving and highly efficient in utilizing acidic dry gas.

[0010] The present invention is implemented by the following technical scheme: a coal tar hydrogenation system for energy-saving and efficient utilization of acidic dry gas, comprising a dehydration tower, a coal tar fractionation tower, a coal tar pitch tank, an intermediate light oil tank, an intermediate medium oil tank, a new hydrogen pipeline, a first reactor, a second reactor, a third reactor, a fourth reactor, a fifth reactor, a high-pressure separator, a low-pressure separator, a pre-fractionation tower, a fractionation tower, a naphtha stabilization tower, a side-line tower and a 1# light coal tar tank and a 2# light coal tar tank, the lower outlet of the dehydration tower is connected to the inlet of the coal tar fractionation tower, the bottom outlet of the coal tar fractionation tower is connected to the coal tar pitch tank, the top outlet of the coal tar fractionation tower is connected to the intermediate light oil tank, the upper outlet of the coal tar fractionation tower is connected to the inlet of the intermediate medium oil tank, the outlet of the intermediate light oil tank and the new hydrogen pipeline are connected to the inlet of the first reactor, and the outlet of the first reactor is connected to the inlet of the first reactor. The outlet of the intermediate oil tank and the outlet of the intermediate oil tank are connected to the inlet of the second reactor, the second reactor, the third reactor, the fourth reactor and the fifth reactor are connected in sequence, the outlet of the fifth reactor is connected to the inlet of the high-pressure separator, the liquid outlet of the high-pressure separator is connected to the inlet of the low-pressure separator, the side liquid outlet of the low-pressure separator is connected to the inlet of the pre-fractionation tower, the bottom outlet of the pre-fractionation tower is connected to the inlet of the fractionation tower, the top outlet of the pre-fractionation tower is connected to the inlet of the naphtha stabilization tower, the top outlet of the fractionation tower is connected to the naphtha stabilization tower, the side outlet of the fractionation tower is connected to the inlet of the side-line tower, the outlet of the naphtha stabilization tower is connected to the 1# light coal tar tank, and the bottom outlet of the fractionation tower and the outlet of the side-line tower are both connected to the 2# light coal tar tank;

[0011] It also includes a liquid separator, a heating furnace and a desulfurization device. The liquid separator is provided with an inlet, a top gas outlet, a side outlet and a bottom outlet. The inlet of the liquid separator is connected to the bottom outlet of the low-pressure separator, the top outlet of the liquid separator is connected to the inlet of the desulfurization device, the side outlet of the liquid separator is connected to the inlet of the high-pressure separator, and the bottom outlet of the liquid separator is connected to the wastewater treatment system.

[0012] The gas outlet of the low-pressure separator, the top outlet of the pre-fractionation tower, and the top outlet of the fractionation tower are all connected to the inlet of the desulfurization device, the outlet of the desulfurization device is connected to the furnace chamber of the heating furnace through a pipeline, and the bottom of the coal tar fractionation tower is connected to the heating furnace through a pipeline.

[0013] Furthermore, the desulfurization device includes a supercharger, a desulfurization tower and a drying tower; the gas outlet of the low-pressure separator, the top outlet of the pre-fractionation tower, the top outlet of the fractionation tower and the top outlet of the liquid separator are all connected to the inlet of the supercharger, the outlet of the supercharger is connected to the air inlet of the desulfurization tower, the gas outlet of the desulfurization tower is connected to the inlet of the drying tower, and the outlet of the drying tower is connected to the furnace chamber of the heating furnace.

[0014] Furthermore, the gas outlet of the high-pressure separator is connected to the inlet of the circulating hydrogen compressor, and the outlet of the circulating hydrogen compressor is connected to the new hydrogen pipeline.

[0015] Furthermore, a coil is provided in the inner cavity of the liquid separation tank, and an inlet and an outlet of the coil are both connected to the heating furnace.

[0016] Advantages of the present invention:

[0017] 1. This scheme desulfurizes and dries the acidic dry gas obtained from the low-pressure separator, pre-fractionator and naphtha stabilization tower, and then sends it to the heating furnace for combustion. The heating furnace provides heat for the coal tar fractionation tower, thus avoiding the waste of resources and environmental pollution caused by the venting and combustion of acidic dry gas in the traditional coal tar hydrogenation system.

[0018] 2. This scheme reduces the pressure and heats the wastewater separated in the low-pressure separator. The acidic gas enters the desulfurization system for desulfurization and drying and is then sent to the heating furnace for combustion. The oil after static separation is returned to the high-pressure separator for treatment, and the remaining wastewater is sent to the subsequent wastewater treatment system for treatment. This avoids the waste of resources caused by the traditional method of discharging acidic wastewater through pipelines and sending it to the wastewater treatment system for treatment, thereby saving production costs. Description of the drawings:

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 The present invention is a schematic diagram of a coal tar hydrogenation system for energy-saving and efficient utilization of acidic dry gas.

[0022] In the figure: dehydration tower 1, coal tar fractionation tower 2, coal tar pitch tank 3, intermediate light oil tank 4, intermediate medium oil tank 5, new hydrogen pipeline 6, first reactor 7, second reactor 8, third reactor 9, fourth reactor 10, fifth reactor 11, high pressure separator 12, low pressure separator 13, pre-fractionation tower 14, fractionation tower 15, naphtha stabilization tower 16, side line tower 17, 1# light coal tar tank 18, 2# light coal tar tank 19, heating furnace 20, booster 21, desulfurization tower 22, drying tower 23, circulating hydrogen compressor 24, liquid separator 25. Specific implementation method:

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] A coal tar hydrogenation system for energy-saving and efficient use of acidic dry gas, comprising a dehydration tower 1, a coal tar fractionation tower 2, a coal tar pitch tank 3, an intermediate light oil tank 4, an intermediate medium oil tank 5, a new hydrogen pipeline 6, a first reactor 7, a second reactor 8, a third reactor 9, a fourth reactor 10, a fifth reactor 11, a high-pressure separator 12, a low-pressure separator 13, a pre-fractionation tower 14, a fractionation tower 15, a naphtha stabilization tower 16, a side tower 17 and a 1# light coal tar tank 18 and 2# light coal tar tank 19, the lower outlet of the dehydration tower 1 is connected to the inlet of the coal tar fractionation tower 2, the bottom outlet of the coal tar fractionation tower 2 is connected to the coal tar pitch tank 3, the top outlet of the coal tar fractionation tower 2 is connected to the intermediate light oil tank 4, the upper outlet of the coal tar fractionation tower 2 is connected to the inlet of the intermediate medium oil tank 5, the outlet of the intermediate light oil tank 4 and the new hydrogen pipeline 6 are connected to the inlet of the first reactor 7, the outlet of the first reactor 7 and the outlet of the intermediate medium oil tank 5 are connected to the second The inlet of the reactor 8 is connected, the second reactor 8, the third reactor 9, the fourth reactor 10 and the fifth reactor 11 are connected in sequence, the outlet of the fifth reactor 11 is connected to the inlet of the high-pressure separator 12, the gas outlet of the high-pressure separator 12 is connected to the inlet of the circulating hydrogen compressor 24, and the outlet of the circulating hydrogen compressor 24 is connected to the new hydrogen pipeline 6; the liquid outlet of the high-pressure separator 12 is connected to the inlet of the low-pressure separator 13, the side liquid outlet of the low-pressure separator 13 is connected to the inlet of the pre-fractionation tower 14, the bottom outlet of the pre-fractionation tower 14 is connected to the inlet of the fractionation tower 15, the top outlet of the pre-fractionation tower 14 and the top outlet of the fractionation tower 15 are both connected to the inlet of the naphtha stabilization tower 16, the side outlet of the fractionation tower 15 is connected to the inlet of the side-line tower 17, the outlet of the naphtha stabilization tower 16 is connected to the 1# light coal tar tank 18, and the bottom outlet of the fractionation tower 15 and the outlet of the side-line tower 17 are both connected to the 2# light coal tar tank 19;

[0026] It also includes a heating furnace 20 and a desulfurization device, the desulfurization device includes a booster 21, a desulfurization tower 22 and a drying tower 23, the gas outlet of the low-pressure separator 13, the top outlet of the pre-fractionation tower 14, and the top outlet of the fractionation tower 15 are all connected to the inlet of the booster 21, the outlet of the booster 21 is connected to the air inlet of the desulfurization tower 22, the gas outlet of the desulfurization tower 22 is connected to the inlet of the drying tower 23, the outlet of the drying tower 23 is connected to the furnace chamber of the heating furnace 20, the bottom of the coal tar fractionation tower 2 is connected to the heating furnace 20 through a pipeline, the material at the bottom of the coal tar fractionation tower 2 is sent to the heating furnace 20 for heating and then returned to the coal tar fractionation tower 2 to realize a heating cycle.

[0027] This embodiment also includes a separator tank 25, the inlet of the separator tank 25 is connected to the bottom outlet of the low-pressure separator, the top outlet of the separator tank 25 is connected to the inlet of the booster 21, the side outlet of the separator tank 25 is connected to the inlet of the high-pressure separator 12, and the bottom outlet of the separator tank 25 is connected to the wastewater treatment system; a coil is provided in the inner cavity of the separator tank 25, and the inlet and outlet of the coil are both connected to the heating furnace 20, so that the liquid in the separator tank 25 is heated by the heating furnace 20.

[0028] Working principle:

[0029] Density: 963.6Kg / m 3 The density of 1# coal tar is 1041.4Kg / m 3The 2# coal tar is heated to 160-168°C and sent to the dehydration tower 1. The temperature at the bottom of the dehydration tower 1 is controlled to be 130-140°C. The oily wastewater is discharged from the top of the dehydration tower 1 and sent to the outside for treatment. The dehydrated coal tar at the bottom of the dehydration tower 1 is sent to the coal tar fractionation tower 2, heated to 305-310°C by the heating furnace 20, and enters the coal tar fractionation tower 2. The top of the coal tar fractionation tower 2 obtains intermediate light oil, the middle obtains intermediate medium oil, and the bottom obtains heavy fuel oil-coal tar (1# and 2# coal tar contain heavy oil, which cannot be hydrogenated and needs to be removed in the early stage). The intermediate light oil, 0# coal tar and hydrogen from the new hydrogen pipeline 6 are sent to the first reactor 7 together. The light oil is heated to 305-310°C by the heating furnace 20 and enters the coal tar fractionation tower 2. The hydrogenation reaction is carried out under the catalytic action of the oil treatment agent, and the hydrogenation product obtained in the first reactor 7 and the intermediate intermediate oil obtained in the intermediate intermediate oil tank 5 enter the second reactor 8 for hydrogenation reaction, and then are sent to the third reactor 9, the fourth reactor 10 and the fifth reactor 11 in sequence, wherein the main model of the hydrorefining catalyst in the first reactor 7 is HPRL-Φ1.4; the main model of the hydrorefining catalyst in the second reactor 8 is HPM-Φ1.3; the main model of the hydrorefining catalyst in the third reactor 9 is HPRH-Φ1.4 / Φ1.6; the main model of the hydrorefining catalyst in the fourth reactor 10 is HP-1.2 / Φ1.4; the main model of the catalyst in the fifth reactor 11 is The number is HPT-Φ1.2, and the catalyst manufacturers are all Pingxiang Petrochemical Filler Co., Ltd. Coal tar fraction oil is hydrogenated under the catalytic action of different hydrorefining catalysts. The main components of the hydrogenated product are alkanes, and also include cycloalkanes, monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, etc. The hydrogenated product is sent to the high-pressure separator 12, and the pressure in the high-pressure separator 12 is controlled to be 16.5MPa. The gas (mainly including hydrogen and a small amount of methane) is pressurized to 18.0MPa by the circulating hydrogen compressor 24 and then sent to the first reactor 7 for reuse; the liquid separated by the high-pressure separator 12 (mainly including alkanes above C5, cycloalkanes and monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, etc.) is sent to the low-pressure separator 13, and the pressure is controlled to be 16.5MPa. The pressure is 1.30MPa, the side discharge liquid enters the pre-fractionation tower 14, the bottom temperature of the pre-fractionation tower 14 is controlled to be 303°C, the material with the top output temperature of 176°C enters the naphtha stabilization tower 16, the bottom liquid enters the fractionation tower 15, the bottom temperature of the fractionation tower 15 is controlled to be 306°C, the material with the top output temperature of 176°C enters the naphtha stabilization tower 16, the gas with the side output temperature of 197°C enters the side line tower 17, and the bottom of the fractionation tower 15 and the bottom of the side line tower 17 obtain 2# light coal tar whose main components are C10 or higher alkanes, cycloalkanes and monocyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons; the naphtha stabilization tower 16 obtains 1# light coal tar whose main components are stabilized naphtha and heavy naphtha;

[0030] Acidic wastewater is discharged discontinuously from the bottom of the low-pressure separator 13, and the acidic wastewater enters the separator tank 25. The pressure continues to drop to normal pressure, and is heated to about 70°C by the heating furnace 20. The gas is discharged from the top of the separator tank 25, and the oil and water are separated by static separation. The oil is discharged from the side outlet and sent to the high-pressure separator 12 for further separation, and the wastewater is discharged from the bottom outlet and sent to the subsequent water treatment system for treatment; the gas discharged from the separator tank 25 and the top gas of the low-pressure separator 13, the pre-fractionation tower 14 and the naphtha stabilization tower 16 are pressurized by the supercharger 21 and sent to the desulfurization tower 22. The desulfurization tower 22 adopts wet desulfurization, and the desulfurizer is alkali solution. The gas after wet desulfurization is sent to the drying tower 23 for dehydration and drying, and then sent to the heating furnace 20 for combustion, so as to make full use of its calorific value.

[0031] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A coal tar hydrogenation system for energy-saving and efficient utilization of acidic dry gas, characterized in that: The invention comprises a dehydration tower, a coal tar fractionation tower, a coal tar pitch tank, an intermediate light oil tank, an intermediate medium oil tank, a new hydrogen pipeline, a first reactor, a second reactor, a third reactor, a fourth reactor, a fifth reactor, a high-pressure separator, a low-pressure separator, a pre-fractionation tower, a fractionation tower, a naphtha stabilization tower, a side-line tower, a 1# light coal tar tank and a 2# light coal tar tank, the lower outlet of the dehydration tower is connected to the inlet of the coal tar fractionation tower, the bottom outlet of the coal tar fractionation tower is connected to the coal tar pitch tank, the top outlet of the coal tar fractionation tower is connected to the intermediate light oil tank, the upper outlet of the coal tar fractionation tower is connected to the inlet of the intermediate medium oil tank, the outlet of the intermediate light oil tank and the new hydrogen pipeline are connected to the inlet of the first reactor, the outlet of the first reactor and the outlet of the intermediate medium oil tank are connected to the The inlet of the second reactor is connected, the second reactor, the third reactor, the fourth reactor and the fifth reactor are connected in sequence, the outlet of the fifth reactor is connected to the inlet of the high-pressure separator, the liquid outlet of the high-pressure separator is connected to the inlet of the low-pressure separator, the side liquid outlet of the low-pressure separator is connected to the inlet of the pre-fractionation tower, the bottom outlet of the pre-fractionation tower is connected to the inlet of the fractionation tower, the top outlet of the pre-fractionation tower is connected to the inlet of the naphtha stabilization tower, the top outlet of the fractionation tower is connected to the naphtha stabilization tower, the side outlet of the fractionation tower is connected to the inlet of the side-line tower, the outlets of the naphtha stabilization tower are both connected to the 1# light coal tar tank, and the bottom outlet of the fractionation tower and the outlet of the side-line tower are both connected to the 2# light coal tar tank; It also includes a liquid separator, a heating furnace and a desulfurization device. The liquid separator is provided with an inlet, a top gas outlet, a side outlet and a bottom outlet. The inlet of the liquid separator is connected to the bottom outlet of the low-pressure separator, the top outlet of the liquid separator is connected to the inlet of the desulfurization device, the side outlet of the liquid separator is connected to the inlet of the high-pressure separator, and the bottom outlet of the liquid separator is connected to the wastewater treatment system. The gas outlet of the low-pressure separator, the top outlet of the pre-fractionation tower, and the top outlet of the fractionation tower are all connected to the inlet of the desulfurization device, the outlet of the desulfurization device is connected to the furnace chamber of the heating furnace through a pipeline, and the bottom of the coal tar fractionation tower is connected to the heating furnace through a pipeline; The desulfurization device includes a supercharger, a desulfurization tower and a drying tower. The gas outlet of the low-pressure separator, the top outlet of the pre-fractionation tower, the top outlet of the fractionation tower and the top outlet of the liquid separator are all connected to the inlet of the supercharger, the outlet of the supercharger is connected to the air inlet of the desulfurization tower, the gas outlet of the desulfurization tower is connected to the inlet of the drying tower, and the outlet of the drying tower is connected to the furnace chamber of the heating furnace; The gas outlet of the high-pressure separator is communicated with the inlet of a circulating hydrogen compressor, and the outlet of the circulating hydrogen compressor is communicated with the new hydrogen pipeline.

2. The energy-saving and efficient coal tar hydrogenation system utilizing acidic dry gas according to claim 1, characterized in that: A coil is provided in the inner cavity of the liquid separation tank, and the inlet and outlet of the coil are both connected to the heating furnace.

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