CN1290736A

CN1290736A - Delay coking process

Info

Publication number: CN1290736A
Application number: CN 00125627
Authority: CN
Inventors: 雷泽永
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-10-07
Filing date: 2000-10-07
Publication date: 2001-04-11

Abstract

Delay coking process as one improved technological process includes three aspects. Firstly, heavy paraffin base oil from the bottom of the fractionating tower is stored in a material cylinder as independent material directly to realize zero circulation of coking process. Secondly, fresh residual oil material is made to heat exchanged with coking products fully to raise the temperature after heat exchange. Finally, residual oil from tap hole is made to flow into the radiation section of heating furnace, rather than the fractionating tower, to reduce greatly the heat load and fuel consumption of the furnace. The process of the present invention with optimized heat exchange procedure can raise power consumption, increase processing capacity and raise yield of light oil greatly.

Description

A kind of delay coking process

The present invention relates to a kind of delay coking process, belong to petrochemical industry.

Delay coking process is one of important secondary processing technology of large-scale refinery, China from the sixties since petrochemical industry is built up, its main process process and equipment almost do not have big change, its flow process is referring to Fig. 2: fresh residual oil through feedstock pump 15 pump and after residual oil-diesel oil interchanger heat exchange (residual oil in the device that has also will with the stage casing heat exchange that refluxes) temperature reach about 180 ℃, the convection zone that enters process furnace 3 tops further is heated to about 340 ℃, it goes out convection zone residual oil and enters directly contact heat-exchanging of oily vapour (about 420 ℃) that coking fractional distillation column 6 bottoms and coke tower 1 come, its temperature rises to 370-380 ℃, coke tower 1 oily vapour is condensed to 350～380 ℃ simultaneously, wax slop wherein (is the general designation that coke drum exports component heavier than wax oil in the oil gas, the factory that has is called turning oil) be condensed into liquid phase by vapour phase, and with fresh residual oil mutually mixed flow at the bottom of the tower, enter radiation pump 4, residual oil after radiation pump 4 boosts and wax slop mixture enter the radiation section of process furnace 3 bottoms, about reheat to 500 ℃, go out process furnace 3 and enter coke tower 1 bottom through four-way valve 2; In coke tower 1 through condensation and scission reaction, the part oil product generates refinery coke, big portion oil product generates wax slop, wax oil, diesel oil, gasoline and rich gas, about 420 ℃, flow out from coke tower 1 top with gas phase state, enter separation column 6 bottoms and carry out contact heat-exchanging, as mentioned above from the residual oil of process furnace 3 convection zones; In separation column 6, wax oil except that wax slop, diesel oil, gasoline and rich gas enter the separation column middle and upper part with gas phase and carry out product separation, wherein: light wax oil is pumped and branch two tunnel after steam generator 17 heat exchange through wax oil pump 9, one the tunnel returns separation column 6, and device is cooled off through water cooler 16 in another road; Backflow wax oil in stage casing divides two the tunnel, the one tunnel directly to remove stabilizer tower B after stage casing reflux pump 8 is pumped, and separation column 6 is returned in another road after vapour generator 17 heat exchange; Diesel oil divides two the tunnel, the one tunnel directly to remove desorption tower A after diesel oil pump 7 is pumped, and another road goes out device again through residual oil-diesel oil interchanger 11 heat exchange after water cooler 16 coolings; Gasoline and rich gas flow out from separation column 6 tops and go out device after water cooler 16 coolings.

There are two defectives in this technology:

The firstth, the process furnace thermal load is overweight, its reason is that the load of coking heater is made up of convection zone and radiation section, we can say between the two without any contact, and fractionator bottom temperature does not allow to surpass 380 ℃ (otherwise separation column bottom coke), thereby strictness has limited convection zone temperature out and radiation section temperature in.Because the convection zone temperature out is limited between 320～340 ℃ by strictness, so the convection zone temperature in also is limited between 180-200 ℃ or is lower, therefore, residual oil can not be with the abundant heat exchange of product, have only few heat exchange, coking raw material residual oil can only heat exchange arrive 180-200 ℃, causes coking heater convection zone overload.And radiation section has two reason fabricate-heat overloads simultaneously: 1. the radiation section temperature in also can not improve because of the separation column temperature limitation, generally about 370 ℃, so the radiation section thermal load can not reduce; 2. its recycle ratio promptly is equivalent to the 20-40% of residual oil amount generally 1.2～1.4, and turning oil circulates repeatedly at radiation section, has occupied 20-40% radiation section thermal load in vain.Therefore the thermal load (being the working ability of coker) of process furnace can only be limited in design level, and causes the process furnace unit consumption of fuel higher, is generally 26-31Kg/t residual oil.On the other hand, owing to be subjected to the restriction of whole temperature＜180-200 ℃ of heat exchange, the main waste heat of device product can not be used for and the heat exchange of raw material residual oil, can only be by the lower low-pressure saturated steam of vapour generator production grade, thus cause the unreasonable use of the energy.

The secondth, wax slop carries out pyrogenic reaction with residual oil at same reaction conditions, and its technology is unreasonable.Reason is that wax slop is that residual oil raw material is carrying out a kind of intermediates that the cracking condensation reaction is produced, its proportion and raw material are close, because this product is the second product behind the slag oil crack, its aromaticity content is than its parent residual oil content height, molecular weight ratio residual oil is little, its thermostability is better than parent residual oil, is difficult for cracking; Therefore, under same temperature, pressure and time, participate in thermal response through process furnace and coke drum with residual oil, so transformation efficiency is lower, generally once can not finish reaction, have only through two, three times or repeatedly reaction just can finish cracking or condensation reaction becomes coke chemicals.This process mixes and formation turning oil with new wax slop together in second, third time.

Purpose of the present invention provides a kind of delay coking process that can reduce process furnace and plant energy consumption, increase device working ability significantly and improve light oil yield with regard to being at above-mentioned prior art present situation.

The object of the present invention is achieved like this: improve existing delay coking process, and the one, the direct carrying device of the wax slop that goes out at the bottom of separation column is stored in separately the head tank independently processes raw material, thereby make coking process realize zero recycle ratio as a kind of; The 2nd, with fresh feed residual oil and fully heat exchange of various coke chemicals (comprising wax slop), improve its heat exchange temperature eventually; The 3rd, no longer will advance separation column again, but directly enter radiation section, thereby process furnace thermal load and unit consumption of fuel are reduced greatly spout residual oil;

Delay coking process process after the improvement is as follows: fresh residual oil is after feedstock pump is successively by residual oil-diesel oil interchanger, residual oil-stage casing recuperator, residual oil-wax oil interchanger, residual oil-wax slop interchanger and the heat exchange of each section of separation column product, enter surge tank, entering the process furnace convection zone through the radiation pump more further heats, go out convection current and directly enter radiation section and remake further heating, then go out process furnace and enter the coke tower bottom through four-way valve; Through condensation and scission reaction, the part oil product generates refinery coke in coke tower, and big portion oil product generates wax slop, wax oil, diesel oil, gasoline and rich gas, flows out from the coke cat head with gas phase state, enters the separation column bottom; Wax slop is extracted out through the wax slop pump from the separation column bottom, and after above-mentioned residual oil-wax slop interchanger heat exchange, divide two the tunnel, one the tunnel returns separation column, and another road is direct carrying device after the water cooler cooling, is stored in separately in the head tank independently to process raw material as a kind of; Other wax oil, diesel oil, gasoline and rich gas enter the separation column middle and upper part with gas phase and carry out product separation, wherein: light wax oil is pumped and branch two tunnel after above-mentioned residual oil-wax oil interchanger heat exchange through the wax oil pump, one the tunnel returns separation column, and another road goes out device after the water cooler cooling; Backflow wax oil in stage casing divides two the tunnel, the one tunnel directly to remove stabilizer tower after the stage casing reflux pump is pumped, and separation column is returned in another road after above-mentioned residual oil-stage casing recuperator heat exchange; Diesel oil divides two the tunnel, the one tunnel directly to remove desorption tower after diesel oil pump is pumped, and another road divides two the tunnel, the one tunnel to return separation column after above-mentioned residual oil-diesel oil interchanger heat exchange again, and another road goes out device after the water cooler cooling; Gasoline and rich gas go out device from the cat head outflow and after the water cooler cooling.

Being stored in wax slop in the head tank in above-mentioned separately waits to run up to and can directly advance coker again as independent coking raw material after a certain amount of, and under the temperature of reaction harsher, carry out coking processing separately than parent residual oil, also can do other raw material (as the oily blend component that acts as a fuel).

Compared with prior art, the present invention extracts wax slop at the bottom of the separation column out and makes the process furnace radiation section no longer include turning oil, so the thermal load of process furnace radiation section descends 20～40%, thereby makes its working ability improve 20～40%.The wax slop of extracting out then can be stored in earlier in the oil tank, treats to carry out coking processing after quantity enough separately under the temperature of reaction harsher than parent residual oil, and its transformation efficiency is reached more than 90%, makes coking process realize zero recycle ratio like this.Consider the independent processing of wax slop, reduce to 1.1 by 1.4 so be equivalent to the recycle ratio of coker.On the other hand, therefore coking raw material residual oil can directly forward radiation to from convection current, just be not subjected to the restriction of separation column bottom coke, also just needn't limit the heat exchange of residual oil and product, thereby make whole heat exchange process obtain global optimization, about 300 ℃ of the whole Wen Keda of heat exchange, this is equivalent to the convection chamber thermal load and has reduced 70%.And the decline of convection chamber load, i.e. the raising greatly of convection current temperature in must cause the raising of radiation entrance temperature, can be increased to by original 370 ℃ about 400～440 ℃, thereby the load of whole radiation section is descended; And the improvement of above-mentioned twice technology can make the inlet amount of process furnace improve more than 50%, and then pyrogenic amount of finish promptly improves more than 50%.Be increased to 290-300 ℃ because the residual oil raw material heat exchange is warm eventually by 180-200 ℃ simultaneously, turning oil is cancelled, and therefore under same amount of finish, the thermal load of process furnace can descend more than 50%, the 2-3Kg/t-residual oil so the unit consumption of fuel 8-10Kg/t-residual oil that can descend, the energy consumption of device also descend.In addition,, the process furnace fuel of calorific value such as just can save, make the utilization of the energy more reasonable because heat exchange process obtains global optimization.

Description of drawings:

Fig. 1 is the process flow diagram of the embodiment of the invention.

Fig. 2 is the process flow diagram of prior art.

Embodiment describes in further detail the present invention below in conjunction with accompanying drawing.

As shown in Figure 1, fresh residual oil is after feedstock pump is successively by residual oil-diesel oil interchanger 11, residual oil-stage casing recuperator 12, residual oil-wax oil interchanger 13, residual oil-wax slop interchanger 14 and separation column 6 each section product heat exchange (temperature can reach about 300 ℃), enter surge tank 5, again after radiation pump 4 enters process furnace 3 convection zones and further is heated to about 400 ℃～440 ℃, go out convection zone and directly enter radiation section and further be heated to about 500 ℃, go out process furnace 3 then and enter coke tower 1 bottom through four-way valve 2;

Through condensation and scission reaction, the part oil product generates refinery coke in coke tower 1, and big portion oil product generates wax slop, wax oil, diesel oil, gasoline and rich gas, flows out from coke tower 1 top with gas phase state about 420 ℃, enters separation column 6 bottoms and distills;

In separation column 6, wax slop becomes liquid phase, pump and branch two tunnel after above-mentioned residual oil-wax slop interchanger 14 heat exchange from separation column 6 bottoms through wax slop pump 10, one the tunnel returns separation column 6, another road temperature after water cooler 16 coolings is reduced to 130 ℃ and is directly gone out device, is stored in separately in the head tank independently to process raw material as a kind of;

Other wax oil, diesel oil, gasoline and rich gas enter separation column 6 middle and upper parts with gas phase and carry out product separation, wherein:

Light wax oil is pumped and is divided two the tunnel, the one tunnel to return separation column 6 after above-mentioned residual oil-wax oil interchanger 13 heat exchange through wax oil pump 9, and another road goes out device after water cooler 16 coolings;

Backflow wax oil in stage casing divides two the tunnel, the one tunnel directly to remove stabilizer tower B after stage casing reflux pump 8 is pumped, and separation column is returned in another road after above-mentioned residual oil-stage casing recuperator 12 heat exchange;

Diesel oil divides two the tunnel, the one tunnel directly to remove desorption tower A after diesel oil pump 7 is pumped, and another road divides two the tunnel, the one tunnel to return separation column 6 after above-mentioned residual oil-diesel oil interchanger 11 heat exchange again, and another road goes out device after water cooler 16 coolings;

Gasoline and rich gas flow out from separation column 6 tops and go out device after water cooler 16 coolings.

According to new technical process, required equipment compared with prior art, a newly-increased wax slop extractor pump 10 and corresponding metering, control and heat-exchange system, newly-increased 3

raw produce interchanger

12,13,14, newly-increased radiation pump intake surge tank 5, process furnace 3 systems need transform corresponding air preheater.

Claims

1. delay coking process is characterized in that:

A. fresh residual oil is after feedstock pump is successively by residual oil-diesel oil interchanger (11), residual oil-stage casing recuperator (12), residual oil-wax oil interchanger (13), residual oil-wax slop interchanger (14) and the heat exchange of separation column (6) each section product, enter surge tank (5), again after radiation pump (4) enters the further heating of process furnace (3) convection zone, go out convection zone and directly enter radiation section and remake further heating, then go out process furnace (3) and enter coke tower (1) bottom through four-way valve (2);

B. in coke tower (1) through condensation and scission reaction, the part oil product generates refinery coke, big portion oil product generates wax slop, wax oil, diesel oil, gasoline and rich gas, flows out from coke tower (1) top with gas phase state, enters separation column (6) bottom;

C. wax slop is extracted out through wax slop pump (10) from the separation column bottom, and after above-mentioned residual oil-wax slop interchanger (14) heat exchange, divide two the tunnel, one the tunnel returns separation column (6), another road directly goes out device after water cooler (16) cooling, be stored in separately in the head tank independently to process raw material as a kind of;

Other wax oil, diesel oil, gasoline and rich gas enter separation column (6) middle and upper part with gas phase and carry out product separation, wherein:

Light wax oil is pumped and is divided two the tunnel, the one tunnel to return separation column (6) after above-mentioned residual oil-wax oil interchanger (13) heat exchange through the wax oil pump, and another road goes out device after water cooler (16) cooling;

Backflow wax oil in stage casing divides two the tunnel, the one tunnel directly to remove stabilizer tower (B) after stage casing reflux pump (8) is pumped, and separation column (6) is returned in another road after above-mentioned residual oil-stage casing recuperator (12) heat exchange;

Diesel oil divides two the tunnel, the one tunnel directly to remove desorption tower (A) after diesel oil pump (7) is pumped, and another road divides two the tunnel, the one tunnel to return separation column (6) after above-mentioned residual oil-diesel oil interchanger (11) heat exchange again, and another road goes out device after water cooler (16) cooling;

Gasoline and rich gas flow out from separation column (6) top and go out device after water cooler (16) coolings.

2, delay coking process as claimed in claim 1, it is characterized in that the described wax slop that is stored in separately in the head tank is waited to run up to directly advances coker separately as coking raw material after a certain amount of again, and carries out coking processing under the temperature of reaction harsher than parent residual oil separately.