CN1036931C - Safety preparation-unloading method for hydrogenization device - Google Patents

Abstract

The present invention relates to a method for safely removing a catalyst in a hydrogenation unit in oil refining industry, which comprises the following operation steps: catalyst washing with light oil, stripping of hot hydrogen, nitrogen displacement, supply of air in a controlled quantity under the condition of nitrogen circulation, slow low-temperature oxidation of a catalyst surface adherent substance easily and impetuously combusted, etc. The catalyst treated with method can be directly removed from a reactor, and the removed catalyst can not be combusted again when the removed catalyst is in contact with the air. The method has the advantage of operation cost saving. The catalyst does not need to be protected by a large quantity of inert gases or chemical reagents. The time for unit running stop caused by catalyst removal is shortened. The activity of the removed catalyst is not lost when the removed catalyst is reused.

Description

Safety preparation-unloading method for hydrogenization device

The present invention be a kind of in petroleum refining industry's hydrogenation unit the used catalyst unloading method, belong to the hydrocarbon ils machining technology.

The catalyzer of hydrogenation unit (hydrocracking, hydrofining, hydrotreatment etc.) can make catalyst carbon deposit, aging even poisoning through after certain runtime, therefore causes catalyst activity reduction.Though this process is gradually, carries out lentamente, finally all can make catalyst deactivation.Catalyzer behind the inactivation need draw off to regenerate or to reclaim from device.In addition, for various reasons, hydrogenation unit is on-stream the catalyst bed stressor layer also can be occurred and falls abnormalities such as increase, reactor radial direction temperature difference be excessive.When some operation index surpasses allowed band, just must shut down, open the reactor observation analysis or the extraction catalyst sample is searched reason, catalyzer is carried out " casting aside head ", regeneration or renewal.Various metals (as W, Mo, Ni, Co etc.) as the activity of hydrocatalyst constituent element in use are to be sulphided state, on-stream also can be former thereby on the surface of catalyzer, adsorbed a large amount of iron sulphide owing to pollution of the impurity in the stock oil, inclusion etc., these metallic sulfides when ingress of air, oxidation rapidly, heat release and cause dieseling.In addition, also can in air, burn at the hydrocarbon ils that adheres on the catalyst surface, dust etc.Pass through the catalyzer of high-temp combustion like this, even after the regeneration, activity of such catalysts also can suffer damage.Therefore, when on the full scale plant of hydrogenation, drawing off catalyzer, must take appropriate measures, avoid taking place security incident, prevent the high-temp combustion of catalyzer, with the active unlikely decline of protection regeneration rear catalyst.

According to reported in literature, unload the safety problem of agent and can take three kinds of solutions, i.e. protection of inert gas method, chemical agent or light oil dampening and in-situ regeneration method.

The protection of inert gas method is got up catalyst protection with a large amount of rare gas elementes exactly; make the catalyzer air contact (" drawing off, preserve and loading of the high sulfur catalyst of hydrocracking high reactivity " of in unloading the process of agent, getting along well; Cheng Mei, Yang Yong are firm; " refining of petroleum "; 1991; the 2nd phase; 22～26 pages); bear nitrogen protection that the several national hydrogenation units of North America unload the Catalyst Recovery Inc. of catalyst recovery company of agent, circulation preparation-unloading method (Catalyst Recovery Inc. come to China exchange of technology material, nineteen eighty-three) in addition and also belong to these class methods.This method not only needs to consume a large amount of rare gas elementes, and in the operation of sieving, store, recharging after unloading agent, yet has many troubles.

Adding chemical agent or light oil dampening is after device is stopped work cooling, injects chemical agent or light oil and makes catalyzer wetting, forms fluid film in agent.Because of film has played secluding air, oxidizing reaction can not take place in the material of easy oxidation on the catalyzer when unloading agent, and it is elegant also not have the dirt sound of sighing.KEC as refinery, sika island unloads agent method (" Japanese hydrogenation unit unloads agent and catalyst device outer regeneration technology investigation report ", " hydrogen addition technology ", 1989 the 1st phases, 81～90 pages) promptly belong to these class methods, what it was used is that a kind of code name is the chemical reagent of KS-767.This method also needs to consume chemical reagent or oil plant, and uneconomical.

The in-situ regeneration method is not actually catalyzer is drawn off, and in reactor decaying catalyst is regenerated, and the material of easy oxidation on the catalyzer cannot fully be contacted with airborne oxygen.This method is the way of having continued to use for many years, as people such as single pines in the 4th phase of " refining of petroleum " nineteen ninety, the method described in " IN-SITU REGENERATION OF UNICRACKING CATALYSTS " literary composition of 8～14 pages, this method complicated operation, also need the special-purpose reclaim equiment of a cover, investment cost is big.And the operating time is long, and the days out of service of device are increased.

Weak point at above method, the objective of the invention is to propose a kind of a large amount of rare gas elementes that neither consume, do not use the safety preparation-unloading method of the industrial hydrogenation unit of chemical reagent or lightweight oil plant again, this method can not take long device stoppage time as the in-situ regeneration method.

Method of the present invention is to stop work when hydrogenation unit, after temperature of reactor descends, embathe catalyzer with light oil, the process hot hydrogen is carried and is removed light oil, again with nitrogen replacement hydrogen, then under nitrogen circulation, feed little air, the control air amount makes the reaction bed temperature vertex be no more than 100 ℃, and the incendive material slow oxidation of catalyst surface is burnt, and gets final product safety preparation-unloading then.

Below the inventive method is described in detail:

When hydrogenation unit is stopped work, under operational condition, lower the temperature, when temperature of reactor is reduced to 300 ℃, stop into stock oil, introduce virgin oil (straight-run spirit, virgin kerosene etc.) the washing catalyst bed that final boiling point is lower than the stock oil final boiling point, lower the temperature gradually while washing, will remain in the diesel oil of catalyst surface or heavier component flush away.Time with the oil wash beds is no less than 6 hours.After bed temperature is reduced to 200 ℃, stop to add virgin oil, continue logical hydrogen purge, blow off hydro carbons residue on the catalyzer with big as far as possible amounts of hydrogen.The hydrogen purge time is no less than 10 hours.After purging, the recycle unit that starts system is cooled to 80 ℃ with hydrogen recycle, and pressure is reduced to 0.5MPa, with the hydrogen nitrogen replacement in the system, hydrogen in system gas and hydrocarbon content less than 0.5% (volume) till, so far nitrogen replacement finishes.

Through behind the nitrogen replacement, just can hang down the oxidation operation under the temperature control.Keep under the 0.5MPa nitrogen pressure in system, start compressor and set up nitrogen circulation.After the instrument for analyzing the content of oxygen calibration with reactor inlet, in system, slowly mend pressurized air, the temperature variation of simultaneously close monitoring catalyst bed.According to the oxygen level in the timely conditioned reaction device of the bed temperature height changing conditions inlet gas.In the oxidising process under whole low temperature control, reaction bed temperature is the highest to be no more than 100 ℃, and the bed temperature rise is below 40 ℃.When the oxygen level that increases or reduce in the reactor inlet gas, to pay special attention to, especially when increasing oxygen level, more will regulate to prevent overtemperature slowly, modestly.After regulating oxygen level, also to stablize and observe for some time.If the bed temperature rise is too little, can suitably increase the oxygen level in the reactor inlet place gas.Be lower than 100 ℃, bed temperature rise at strictness control bed temperature vertex and be lower than under 40 ℃ of situations, the oxygen level in the reactor inlet gas is increased to 0.5% (volume) gradually and stablized 2 hours.When oxygen level in the reactor inlet gas has surpassed 10% (volume) and bed when not having temperature rise, can continue to increase air capacity rallentando, to the last all bubbling airs enter reactor, and bed is not when still having temperature rise, low temperature control oxidation operation end down.

Compare with the prior art of hydrogenation unit preparation-unloading method, the advantage of the inventive method is:

1, the inventive method does not consume a large amount of rare gas elementes or chemical reagent, does not need loaded down with trivial details in-situ regeneration operation yet, has saved process cost and investment.

2, the agent time of unloading that present method is used is short, thereby has also shortened device owing to unloading the time that agent shuts down.

3, on the catalyzer easily the material of oxidizing fire through the oxidation operation under the low temperature control of present method after, in reactor, finished oxidizing reaction.No matter the catalyzer that draws off is through any one operations such as exposing in air, deposit, sieve, store, recharge, does not have safety problem and exists.

4, the catalyzer that uses present method to draw off can not be subjected to because of unloading the loss of activity that agent causes, and this point can be by the data declaration among the embodiment.

Embodiment 1

The industry hydro-refining unit, stock oil is coking vapour, diesel oil, uses the Hydrobon catalyst that contains fluorine, nickel, tungsten.Because of the beds radial temperature difference is bigger, when inside the plan break-down maintenance, catalyzer is drawn off in the running according to the inventive method.

After device is stopped work, according to the operation steps of the inventive method through kerosene clean, hot hydrogen purges, nitrogen replacement.In the system hydrogen and hydrocarbon content analyze qualified after, system pressure is transferred to 0.5MPa nitrogen press, start recycle compressor and set up intrasystem nitrogen circulation, advance industrial pressurized air, be not more than under 100 ℃ the condition strict control pressurized air inlet at the control catalyst bed temperature.Oxidation operation is shared 34 hours under the low temperature control.When oxidation finished, bed did not have temperature rise, and bed each point temperature is all below 30 ℃.

After the oxidation operation under the low temperature control, catalyzer to be unloaded by general preparation-unloading method, the not blanketing with inert gas of catalyzer that draws off is directly put into metal bucket and is preserved.Though be exposed in the air catalyzer phenomenon of not generating heat.Through after the maintenance of device, the catalyzer of depositing is sieved by taking out in the metal bucket, reload in the reactor.The normal procedure that goes into operation according to device turns round.Analyze the equal and live catalyst suitable (seeing Table 1) of the performance of the catalyzer that draws off after the low temperature controlled oxidation such as desulfurization degree, denitrification percent and dealkalize nitrogen rate through demarcating.As with unload agent before performance compare, desulfurization degree is constant, denitrification percent and dealkalize nitrogen rate also have raising by a relatively large margin.After also explanation was unloaded agent through low-temperature oxidation thus, catalyzer had not only kept the activity before the oxidation, and also has certain catalyst regeneration effect.

Table 1

Catalyst performance	Live catalyst	Before the low-temperature oxidation	After the low-temperature oxidation
				Desulfurization degree, % denitrification percent, % dealkalize nitrogen rate, %	99.8 76.7 80.5	99.1 53.8 64.6	99.8 73.3 80.6

Embodiment 2

Reformed pre-hydrogenated highly industry device, stock oil are the straight run reforming raw oil, use Ni-W/ γ-Al ₂O ₃Catalyzer.Because increase falls in the on-stream pressure that beds occurs, decide that the back of stopping work carries out " casting aside head " to catalyzer and handle, make the low temperature controlled oxidation according to the inventive method and unload the agent operation.

When device is stopped work beginning,, reduce inlet amount simultaneously, when temperature of reactor is reduced to 200 ℃, stop incoming stock oil with per hour 20～30 ℃ cooling rate cooling.System is kept constant temperature down at 200 ℃, purge 10 hours to purge clean hydro carbons residue on catalyst surface as far as possible with hydrogen recycle.Stop the hydrogen recycle compressor after still under hydrogen recycle, being cooled to 80 ℃ then.The pressure of system is reduced to 0.3MPa.Draw oxygen level less than the hydrogen in the nitrogen replacement system of 0.3% (volume), the total amount of hydro carbons and hydrogen is lower than 0.4% (volume) in the nitrogen of system.Again pressure is increased to 0.5MPa with nitrogen then, set up nitrogen circulation.After the calibration of the gas oxygen content analyzer at reactor inlet place, oxygen level is 0.3% (volume) in the system, slowly mends pressurized air and hang down under the temperature control catalyst oxidation and operate in system.

Through after the above-mentioned operation, open reactor, beds is carried out " casting aside head ", catalyzer is drawn off, sieves, loads again, after the step that goes into operation according to device running goes into operation once more, under the identical operations condition, catalyzer has still kept fresh dose desulfurization, denitrification activity, and the sulphur of the reforming raw oil after the hydrofining, nitrogen impurity content are all below 0.5ppm.

Claims (1)

1. safety draws off the used catalyst method in petroleum refining industry's hydrogenation unit, is included in operation such as to propose with light oil washing catalyst and hot hydrogen before drawing off, and the inventive method is characterised in that:

(1) after catalyzer is carried through the light oil more than 6 hours washing and the hot hydrogen more than 10 hours, the hydrogen in the apparatus system is replaced with nitrogen, the hydrogen in system in the nitrogen and the content of hydro carbons less than 0.5% volume till;

(2) apparatus system is set up nitrogen circulation;

(3) will make the easily material slow oxidation of oxidation burning on the catalyst surface in the little air of control is sent into apparatus system under the nitrogen circulation, in the whole process of oxidizing fire, beds each point temperature all remains on below 100 ℃;

(4) the air manipulated variable of access to plant system increases gradually, and oxygen level has reached airborne oxygen concn in the gas at reactor inlet place, and bed when not had temperature rise till.