Disclosure of Invention
The invention aims to solve the defects that the energy consumption of a desorber is high due to the fact that the flow of gasoline is circularly stabilized by supplementing an absorbent of an absorption stabilizing system of the existing delayed coking device is high, and the flow is complex and the processing amount of a main fractionating tower is large due to the fact that rich diesel oil returns to the main fractionating tower for recycling. The method directly flash-vaporizes the coking rich gasoline and diesel oil and then directly sends the coking rich gasoline and diesel oil to a downstream gasoline and diesel oil hydrofining device.
The invention is realized by the following technical scheme:
the delayed coking process with low power consumption for absorbing stable system includes the following steps: the original product gasoline is sent to a downstream gasoline and diesel oil hydrofining device, the product gasoline is changed into product gasoline which is sent to the lower part of a reabsorption tower 19, rich gasoline and diesel oil at the tower bottom of the reabsorption tower 19 are flashed by a rich gasoline and diesel oil flash evaporation tank 11 and then directly sent to the downstream gasoline and diesel oil hydrofining device, the flashed gas is sent to an inlet of a rich gas compressor, an original lean diesel oil-rich diesel oil heat exchanger 8 is cancelled, and the flow of other pipelines is unchanged.
A delayed coking method for realizing energy consumption reduction of an absorption stabilization system comprises the following steps:
after the high-temperature oil gas from the coke tower and the vacuum residue oil from the atmospheric and vacuum distillation device after heat exchange are fully contacted in a de-superheating section of a main fractionating tower 1, the oil gas enters a rectifying section, the liquid phase enters a stripping section, is fed into a heating furnace and pumped into the heating furnace, is rapidly heated in the furnace tube to the temperature of 550 ℃ below zero, which can cause coking reaction in the coke tower, and then enters the coke tower, and the coking oil flows into the coke tower to cause deep thermal cracking reaction and is converted into coke and oil gas; obtaining rich gas, crude gasoline, diesel oil and wax oil in sequence through fractionation, and taking away the excessive heat through a tower top cooling system, top circulation reflux, diesel oil reflux, middle section reflux and wax oil reflux;
the gas at the top of the main fractionating tower 1 is cooled to 40-45 ℃ by a first circulating water cooler 2 and enters a gas-liquid separation tank 3, non-condensable gas and condensed crude gasoline are separated, the non-condensable gas and flash gas of rich gasoline and diesel oil are compressed to 1.3MPag by a first rich gas compressor 4-1 and a second rich gas compressor 4-2 together and cooled to 40-45 ℃, then the non-condensable gas and the flash gas of the rich gasoline and diesel oil are mixed with tower top gas of a desorption tower 22 and tower bottom oil of an absorption tower 16 pumped by a bottom oil suction pump 18 and enter a condensed oil tank, a circulating water cooler 15 is cooled to 43-44 ℃, the circulating water cooler is mixed with the tank bottom oil of a gas-liquid separation tank 13 at the first-level outlet of the compressor and enters a condensed oil tank 17, and the condensed crude gasoline is pressurized by a crude gasoline pump 5 and then is sent to the top of an absorption and stabilization part of the absorption tower 16;
diesel oil is extracted from the 14 th layer of the main fractionating tower 1 and is divided into two parts after heat exchange: one strand of the waste liquid is used as hot reflux to return to the main fractionating tower; the other strand is taken out by a diesel pump 6 after heat exchange as a product diesel, and is sent to the top of a reabsorption tower 19 as an absorbent through a lean diesel-rich diesel heat exchanger 7, a lean diesel-hot water heat exchanger 8, a lean absorption diesel air cooler 9 and a lean absorption diesel circulating water cooler 10 to 40-45 ℃;
the operating pressure of the absorption tower 16 is 1.1 MPag-1.23 MPag, the gas from the condensation oil tank 17 enters the lower part, the crude gasoline from the main fractionating tower and the circulating stable gasoline from the stabilizing tower as a supplementary absorbent enter the top part of the absorption tower, and the crude gasoline and the circulating stable gasoline are in countercurrent contact to finish mass transfer and heat transfer, and the intermediate circulating water cooler is used for realizing heat balance; the lean gas from the top of the absorption tower 16 is sent to the bottom of a reabsorption tower 19 and is in countercurrent contact with the product gasoline and the product diesel oil from a main fractionating tower to absorb components which are carried by the lean gas and are not less than C3, the product dry gas is discharged from the top of the tower, and the gasoline-rich diesel oil at the bottom of the tower directly enters a raw material buffer tank of a downstream gasoline-diesel oil hydrofining device after passing through a flash tank 11;
condensed oil is pressurized from a condensed oil tank 17 through a feeding pump 20 of a desorption tower, then passes through the heat exchange 21 of the condensed oil and stable gasoline, the condensed oil and the stable gasoline exchange heat to 50-55 ℃, and enter the top of the desorption tower 22, a reboiler 23 at the bottom of the desorption tower exchanges heat with the diesel oil of a main fractionating tower through reflux heat supply, deethanized gasoline at the bottom of the desorption tower exchanges heat with the stable gasoline through a deethanized gasoline-stable gasoline heat exchanger 24 to 160-164.2 ℃ and enters a stabilizing tower 25, a reboiler 26 at the bottom of the stabilizing tower exchanges heat through reflux of the middle section of the main fractionating tower, LPG light components are distilled from the top of the tower, are condensed and cooled to 41-43.1 ℃ through an air cooler 31 at the top of the stabilizing tower and enter a gas-liquid separation tank 32 at the top of the stabilizing tower, one part of liquefied gas is pressurized through a reflux pump 33 at the top of the stabilizing tower to serve as cold reflux, and the other part of the liquefied gas is pressurized through a liquefied gas product pump 34 to serve as a product to be sent out of the device; the stable gasoline at the bottom of the tower sequentially passes through a de-ethanized gasoline-stable gasoline heat exchanger 24, a condensed oil-stable gasoline heat exchanger 21, a deoxidized water-stable gasoline heat exchanger 27 and an air cooler 28, and a second circulating water cooler 29 is cooled to 40 ℃, and is pressurized by a stable gasoline pump 30 and then divided into two paths, wherein one path is used as a supplementary absorbent and sent to the top of the absorption tower, and the other path is used as a product gasoline and sent to the lower part of the reabsorption tower.
Compared with the prior art, the invention has the following advantages and effects:
(1) the product gasoline is sent to the lower part of the reabsorption tower and the product diesel oil is sent to the top of the reabsorption tower to be used as absorbent, so that the flow rate of the gasoline which is circularly stabilized by the supplementary absorbent is reduced, the circular processing amount of an absorption stabilizing system is greatly reduced, and the quality indexes of dry gas and liquefied gas products of a coking device are not influenced.
(2) The process of recycling the delayed coking rich diesel is stopped, the rich diesel which is not subjected to the recycling treatment does not influence the material balance of a downstream hydrofining device even if the rich diesel contains a certain amount of gasoline and LPG components, and the rich diesel which is discharged from the bottom of the coking reabsorption tower is directly sent to the gasoline and diesel hydrofining device after being flashed, so that the process of coking rich diesel is omitted, the processing load of a main fractionating tower is reduced, the material balance of the downstream gasoline and diesel hydrofining device is basically not influenced, and the process has remarkable innovative significance.
(3) The process flow reduces the treatment capacity of the main fractionating tower of the delayed coking device, reduces the cooling load of the tower top gas, and absorbs the energy consumption of the desorption tower in the stabilizing system.
(4) The process flow of the invention increases the top cycle heat output of the main fractionating tower of the delayed coking device.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Comparative example
The comparative example is the existing delayed coking main fractionating tower and absorption stabilizing system;
the process flow is shown in figure 1. The specific process is as follows:
after the high-temperature oil gas from the coke tower and the vacuum residue oil from the atmospheric and vacuum distillation device after heat exchange are fully contacted in the de-superheating section of the main fractionating tower 1, the oil gas enters the rectifying section, the liquid phase enters the stripping section, is fed into the heating furnace and pumped into the heating furnace, is rapidly heated in the furnace tube to the temperature of 550 ℃ which can generate coking reaction in the coke tower, and then enters the coke tower, and the coking oil flows into the coke tower to generate deep thermal cracking reaction and is converted into coke and oil gas. Obtaining rich gas, crude gasoline, diesel oil and wax oil in sequence through fractionation, and taking away the excessive heat through a tower top cooling system, top circulation reflux, diesel oil reflux, middle section reflux and wax oil reflux;
the gas at the top of the main fractionating tower 1 is cooled to 40 ℃ by a first circulating water cooler 2 and enters a gas-liquid separation tank 3, non-condensable gas and condensed crude gasoline are separated, the non-condensable gas enters a first rich gas compressor 4-1 and a second rich gas compressor 4-2 and is compressed to 1.3MPag and is cooled to 40 ℃, the non-condensable gas and the condensed crude gasoline are mixed with the top gas of a desorption tower 22 and the bottom oil of an absorption tower 16 pumped by a bottom oil suction pump 18 and enter a circulating water cooler 15 to be cooled to 44 ℃, the condensed crude gasoline and the bottom oil of a gas-liquid separation tank 13 at the primary outlet of the compressor are mixed into a condensed oil tank 17, and the condensed crude gasoline at 40 ℃ is pressurized by a crude gasoline pump 5 and then is sent to the top of the absorption tower 16 of an absorption stabilizing part;
diesel oil is extracted from the 14 th layer of the main fractionating tower 1 and is divided into two parts after heat exchange: one strand of the waste liquid is used as hot reflux to return to the main fractionating tower; another strand of diesel oil is pumped out by a diesel oil pump 6 after heat exchange and divided into two strands, and one strand of diesel oil serving as lean diesel oil is sent to the top of a reabsorption tower 19 as an absorbent through a lean diesel oil-rich diesel oil heat exchanger 7, a lean diesel oil-hot water heat exchanger 8, a lean absorption diesel oil air cooler 9 and a lean absorption diesel oil circulating water cooler 10 to 45 ℃; the other strand is taken as product diesel oil and is sent to a raw material buffer tank of a gasoline and diesel oil hydrofining device after heat exchange;
the operation pressure of the absorption tower 16 is 1.23MPag, gas from the condensation oil tank 17 enters the lower part, crude gasoline from the main fractionating tower and circulating stable gasoline from the stabilizing tower as a supplementary absorbent enter the top part of the absorption tower, and the crude gasoline and the circulating stable gasoline are in countercurrent contact to finish mass transfer and heat transfer, and an intermediate circulating water cooler helps to realize heat balance; the lean gas coming out from the top of the absorption tower 16 is sent to the bottom of a reabsorption tower 19 and is in countercurrent contact with the lean diesel oil from the main fractionating tower to absorb the carried C and C3The components, the dry gas of the product is discharged from the top of the tower, and the rich diesel oil at the bottom of the tower returns to the main fractionating tower through a lean diesel oil-rich diesel oil heat exchanger 7;
condensed oil is pressurized from a condensed oil tank 17 through a feeding pump 20 of a desorption tower, then passes through a condensed oil-stable gasoline heat exchanger 21, exchanges heat with stable gasoline to 55 ℃, enters the top of a desorption tower 22, exchanges heat with the stable gasoline to 170 ℃ through a reboiler 23 at the bottom of the desorption tower, enters a stabilization tower 25 through a heat exchanger 24 for removing ethane gasoline-stable gasoline, exchanges heat with the stable gasoline to 170 ℃, and returns to the stabilization tower through the middle section of a main fractionating tower to supply heat through a reboiler 26 at the bottom of the stabilization tower, LPG light components are distilled from the top of the tower, are condensed and cooled to 40.1 ℃ through an air cooler 31, enter a gas-liquid separation tank 32 at the top of the stabilization tower, one part of liquefied gas is pressurized through a reflux pump 33 at the top of the stabilization tower to serve as cold reflux, and one part of liquefied gas is pressurized through a liquefied gas product pump 34 to serve as a product discharge device; the stable gasoline at the bottom of the tower sequentially passes through a deethanized gasoline-stable gasoline heat exchanger 24, a condensed oil-stable gasoline heat exchanger 21, a hot water heat exchanger 27 and an air cooler 28, and a second circulating water cooler 29 is cooled to 40 ℃, and is pressurized by a stable gasoline pump 30 and then divided into two paths, wherein one path is used as a supplementary absorbent and sent to the top of the absorption tower, and the other path is used as a product to be sent to a raw material buffer tank of a gasoline and diesel oil hydrofining device.
The embodiment of the invention comprises the following steps:
the original product gasoline is sent to a downstream gasoline and diesel oil hydrofining device, the product gasoline is changed into product gasoline which is sent to the lower part of a reabsorber, rich gasoline and diesel oil at the bottom of the reabsorber is directly sent to the downstream gasoline and diesel oil hydrofining device after being flashed, the flashed gas is sent to an inlet of a rich gas compressor, an original lean diesel oil-rich diesel oil heat exchanger is omitted, and the flow of other pipelines is unchanged.
The process flow diagram is shown in fig. 2, and the specific process flow is as follows:
after the high-temperature oil gas from the coke tower and the vacuum residue oil from the atmospheric and vacuum distillation device after heat exchange are fully contacted in the de-superheating section of the main fractionating tower 1, the oil gas enters the rectifying section, the liquid phase enters the stripping section, is fed into the heating furnace and pumped into the heating furnace, is rapidly heated in the furnace tube to the temperature of 550 ℃ which can generate coking reaction in the coke tower, and then enters the coke tower, and the coking oil flows into the coke tower to generate deep thermal cracking reaction and is converted into coke and oil gas. Obtaining rich gas, crude gasoline, diesel oil and wax oil in sequence through fractionation, and taking away the excessive heat through a tower top cooling system, top circulation reflux, diesel oil reflux, middle section reflux and wax oil reflux;
the gas at the top of the main fractionating tower 1 is cooled to 40 ℃ by a first circulating water cooler 2 and enters a gas-liquid separation tank 3, non-condensable gas and condensed crude gasoline are separated, the non-condensable gas and flash gas of rich gasoline and diesel oil are fed into a first rich gas compressor 4-1 and a second rich gas compressor 4-2 together and compressed to 1.3MPag and cooled to 40 ℃, then the non-condensable gas and the flash gas of the rich gasoline and the oil at the bottom of an absorption tower 16 pumped by a bottom oil suction pump 18 are mixed with a circulating water cooler 15 and cooled to 44 ℃, the non-condensable gas and the oil at the bottom of a gas-liquid separation tank 13 at the primary outlet of the compressor are mixed into a condensed oil tank 17, and the condensed crude gasoline is pressurized by a crude gasoline pump 5 at 40 ℃ and then is fed to the top of an absorption tower 16 of an absorption stabilizing part;
diesel oil is extracted from the 14 th layer of the main fractionating tower 1 and is divided into two parts after heat exchange: one strand of the waste liquid is used as hot reflux to return to the main fractionating tower; the other strand is taken out by a diesel pump 6 after being used as the product diesel oil for heat exchange, and is sent to the top of a reabsorption tower 19 to be used as an absorbent through a lean diesel oil-rich diesel oil heat exchanger 7, a lean diesel oil-hot water heat exchanger 8, a lean absorption diesel oil air cooler 9 and a lean absorption diesel oil circulating water cooler 10 to 45 ℃;
the operation pressure of the absorption tower 16 is 1.23MPag, gas from the condensation oil tank 17 enters the lower part, crude gasoline from the main fractionating tower and circulating stable gasoline from the stabilizing tower as a supplementary absorbent enter the top part of the absorption tower, and the crude gasoline and the circulating stable gasoline are in countercurrent contact to finish mass transfer and heat transfer, and an intermediate circulating water cooler helps to realize heat balance; the lean gas coming out from the top of the absorption tower 16 is sent to the bottom of a reabsorption tower 19 and is in countercurrent contact with the product gasoline and the product diesel oil from a main fractionating tower to absorb the carried C and C3The components are that the dry gas of the product is discharged from the top of the tower, and the rich gasoline and diesel oil at the bottom of the tower directly enters a raw material buffer tank of a downstream gasoline and diesel oil hydrofining device after passing through a rich gasoline and diesel oil flash tank 11;
condensed oil is pressurized from a condensed oil tank 17 through a feeding pump 20 of a desorption tower, then passes through a condensed oil-stable gasoline heat exchanger 21, exchanges heat with stable gasoline to 55 ℃, enters the top of a desorption tower 22, exchanges heat with the stable gasoline to 164.2 ℃ through a heat exchanger 24 for removing the ethane-gasoline-stable gasoline, enters a stabilization tower 25, exchanges heat with the stable gasoline through the middle section of the main distillation tower for refluxing and supplying heat through a reboiler 23 at the bottom of the desorption tower, and condenses and cools to 43.1 ℃ through an air cooler 31, and then enters a gas-liquid separation tank 32 at the top of the stabilization tower, wherein one part of liquefied gas is pressurized as cold reflux through a reflux pump 33 at the top of the stabilization tower, and the other part of liquefied gas is pressurized as a product to be sent out of the device through a liquefied gas product pump 34; the stable gasoline at the bottom of the tower passes through a deethanized gasoline-stable gasoline heat exchanger 24, a condensed oil-stable gasoline heat exchanger 21, a hot water heat exchanger 27 and an air cooler 28 in sequence, and a second circulating water cooler 29 is cooled to 40 ℃, and is pressurized by a stable gasoline pump 30 and then divided into two paths, wherein one path is used as a supplementary absorbent and sent to the top of the absorption tower, and the other path is used as a product gasoline and sent to the lower part of the absorption tower.
The main operation of the comparative examples and examples will be described below by taking a 180 ten thousand ton/year delayed coking plant as an example.
Table 1 comparative and example main fractionator reflux heat removal
Table 2 comparative and example rich gas compressor operation
Based on isentropic compression efficiency 75%;
TABLE 3 comparative and example rich gas cooling duty
TABLE 4 intermediate cooling duty of absorption towers of comparative and example
Table 5 comparative and example make-up absorbent flow rates
Table 6 comparative and example stripper reboiler runs
Table 7 comparative and example stabilizer energy consumption behavior
As can be seen from tables 1 to 7, the invention:
1. the condensing load on the top of the main fractionating tower is reduced by 4 x 104kcal/h, amplitude reduction 0.4%;
2. the power consumption of the rich gas compressor is increased by 20kw by 1.1%, and the steam consumption of the driving turbine at 3.5MPa is reduced by 0.35 t/h;
3. main fractionating tower top circulation multi-heat extraction 265X 104kcal/h, which saves steam of 1.0MPa by 5.3 t/h;
4. the desorption tower reduces reboiling load 371X 104kcal/h (1.0 MPa steam 7.4t/h), reduced amplitude 42.8%;
5. increasing reboiling load of stabilizing tower by 7X 104kcal/h (equivalent 3.5MPa steam 0.14t/h), amplification 2.0%;
the steam is saved by 12.2t/h in the total embodiment, and the energy consumption cost is reduced by 1844.6 ten thousand yuan/year in the embodiment compared with the comparative embodiment based on the steam unit price of 180 yuan/t and the calculation of 8400 hours of annual operation of the device.
The process flow of the invention sends the product gasoline to the lower part of the reabsorption tower and the product diesel oil to the top of the reabsorption tower as the absorbent, thus reducing the flow rate of the gasoline which is circularly stabilized by the supplementary absorbent, greatly reducing the circular processing amount of the absorption stabilizing system, and not influencing the quality indexes of the dry gas and liquefied gas products of the coking device. The process of recycling the delayed coking rich diesel oil is stopped, the rich diesel oil which is not subjected to the recycling treatment does not influence the material balance of a downstream hydrofining device even if the rich diesel oil contains a certain amount of gasoline and LPG components, and the rich diesel oil which is discharged from the bottom of the coking reabsorption tower is directly sent to the gasoline and diesel oil hydrofining device after being flashed, so that the process of coking rich diesel oil is omitted, the processing load of a main fractionating tower is reduced, and the material balance of the downstream gasoline and diesel oil hydrofining device is basically not influenced.
As described above, the present invention can be preferably realized.
The embodiments of the present invention are not limited to the above-described embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and they are included in the scope of the present invention.