CN102092713B - Method for continuously preparing phosgene - Google Patents
Method for continuously preparing phosgene Download PDFInfo
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- CN102092713B CN102092713B CN201010584341XA CN201010584341A CN102092713B CN 102092713 B CN102092713 B CN 102092713B CN 201010584341X A CN201010584341X A CN 201010584341XA CN 201010584341 A CN201010584341 A CN 201010584341A CN 102092713 B CN102092713 B CN 102092713B
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Abstract
The invention relates to a method for producing phosgene through the reaction of chlorine and carbon monoxide, and in particular to a method that chlorine and carbon monoxide are used to perform an exothermic reaction in a tube reactor in the presence of an activated carbon catalyst and generate phosgene. In the method provided by the invention, after chlorine is mixed with excess carbon monoxide in a mixer M1, then the mixture enters a tubular reactor C1 to react under the action of the activated carbon catalyst and generate phosgene and then passes through a protection reactor C2 to ensure that chlorine reacts completely; and the heat generated by the reaction is led out by a 60 DEG C cooling water system in closed cycle, the generated gaseous phosgene is cooled through W1 condensation and W2 condensation and enters a phosgene gas-liquid separation tank B2, the un-condensed gas enters an exhaust gas absorber K1, and -5 DEG C toluene is used to absorb and recycle phosgene in tail gas.
Description
Technical field
The present invention relates to a kind of method of being produced phosgene by chlorine and reaction of carbon monoxide, be specifically related to make chlorine and carbon monoxide to produce the method for phosgene by thermopositive reaction under the existence of activated carbon catalyst in the shell reactor.After wherein chlorine mixes in mixing tank M1 with excessive carbon monoxide, enter shell and tube reactor C1, under the activated carbon catalyst effect, reaction generates phosgene, then, through guard reactor C2, guarantees that chlorine reaction is complete; The heat that reaction generates is derived by 60 ℃ of cooling water systems of closed cycle, the gaseous phosgene generated through W1, W2 condensed in two stages, cooling after, enter phosgene gas-liquid separation groove B2, uncooled gas enters tail gas absorber K1, with the toluene of-5 ℃, absorbs phosgene contained in tail gas and reclaims and use.
Background technology
Tolylene diisocyanate (TDI) is one of isocyanic ester series products of consumption maximum in the world, is one of main raw material of urethane.The TDI production technique is mainly that the chlorine reaction that the carbon monoxide that provided by gas sweetening and chlor-alkali device provide generates phosgene (COCL
2), then by tolylene diamine (TDA) and COCL
2reaction generates TDI, the unit such as master operation has that phosgene is synthetic, TDA is synthetic, the synthetic TDI of phosgenation and rectifying, phosgene recovery, solvent recuperation, waste gas destruction.Several major companies that at present produce in the world TDI, all used the proprietary technology of oneself, and all use without exception traditional phosgenation.These companies are that press in Bayer (BAYER), BASF (BASF), Dow Chemical (DOWS CHEM), rhone-poulenc (RHONE POULENE), ENI chemistry (ENI CHEM), Olympic (OLIN) and Mitsui east.Traditional phosgenation, even react with the tolylene diamine in inert solvent with phosgene, generate TDI and emit HCL gas.Phosgenation reaction carries out in tower or in reactor mostly.In traditional phosgene recovery system, material enters the toluene absorption tower, and phosgene is absorbed by toluene, and the non-condensable gases such as HCL are discharged from tower top.
Producing phosgene by chlorine and reaction of carbon monoxide under C catalyst exists is a kind of well-known technique.Catalyzer is aging and require to improve all the time operating temperature in time course along with the carrying out of reaction, this point has counter productive to the composition of product gas conversely: phosgene decomposes the backward reaction that produces chlorine and carbon monoxide significantly to be increased, and this requires again elapsed time for gas scrubbing; Activated-carbon catalyst itself also can cause side reaction, at high temperature, chlorine for a long time contact relative to activated carbon surface caused the formation of tetracol phenixin, tetracol phenixin is a kind of harmful byproduct that has a strong impact on polycarbonate output, in addition, tetracol phenixin is considered to relevant with ozone layer depletion and Global warming always.By this explained hereafter, phosgene out can contain the tetracol phenixin of 400～500ppm weight usually, and by the approximately 4,500,000 tons of calculating of whole world phosgene production total amount, this content is equivalent to produce the approximately tetracol phenixin of 1800～2300 tons together with phosgene simultaneously.Therefore, developing the amount that can make tetracol phenixin impurity, to be down to minimum Phosgene mfg. process be very important.A target that is prepared phosgene by chlorine and carbon monoxide is to design a kind of method that allows single step reaction, can in a wide region, change the pressure and temperature parameter of reaction, can realize thus the maximum flexibility in control process and reduce the interference by product, as tetracol phenixin.
This strong reaction heat release under activated carbon catalyst exists of carbon monoxide and chlorine, its Enthalpies of Formation is-107.6kJ.Reaction is generally carried out in shell and tube-type reactor.In this course, the pelleted catalyst of granularity between 3～5mm packed in the reaction tubes that internal diameter is 50～70mm.Reaction starts at 40～50 ℃ of temperature, and in pipe, temperature rises to about 400 ℃ of then declines rapidly.Carbon monoxide is excessive a little to react and obtains not chloride phosgene to guarantee that all chlorine is participated in.Reaction can or be generally under the high pressure of 2～3 bar at normal pressure to be carried out, so that phosgene can be by means of water quench.In order to improve the heat of reaction of carrying out by means of the heat-transfer medium circulated between catalyst tube, shift out, mounting guiding board between catalyst tube, to produce the transverse flow of heat-transfer medium between catalyst tube.Be covered with pipe in the known shell and tube-type reactor for the preparation of phosgene to reach the maximum utilization of reactor inner space, and there is flow deflector between catalyst tube.These plates are relatively short, and in the water conservancy diversion zone, heat-transfer medium becomes longitudinal flow around catalyst tube from transverse flow.Catalyst tube is not cooling, causes on the catalyst tube in water conservancy diversion zone and etching problem occurs.With the heat that in direct cooling safe dissipation shell and tube-type reactor, many tube reactions of activated-carbon catalyst produce, but also mentioned transpiration cooling in document.But the gas temperature that proposes reactor exit must be lower than 100 ℃ simultaneously, just can make cl content in phosgene lower than 50ppm.Therefore, the method for this invention also divides two stages to carry out.In the first stage of the method, at high temperature manufacture phosgene, carry out transpiration cooling with a kind of high boiling point refrigerant, the subordinate phase of the method is carried out under the direct cooling conditions of 70～100 ℃.This reactor is special tubular structure, in order to prevent corrosion, manufactures reactor tube with stainless steel especially.If water by reaction tubes because the hole that forms of corrosion enters reaction compartment, water can with phosgene vigorous reaction on activated-carbon catalyst of formation.Reaction between this water photoreactive gas can form hydrochloric acid, thereby causes further corrosion.Realize the dissipation to phosgene producing method reaction heat by the decompression evaporative cooling, the pressure now preferably adopted is lower than barometric point, and its absolute value is 1 bar.From this viewpoint, coolant circulating is a closed cycle system preferably, and wherein water is evaporated, and shifts, and in another place's condensation, then is recirculated to the refrigerant space and again evaporates.In this sense, the liquid water in boiling state is preferably contained in the refrigerant space in shell and tube-type reactor.Therefore, the pressure in reaction compartment keeps being greater than the pressure in the refrigerant space, if reaction tubes damages, phosgene can enter the refrigerant space from reaction tubes, and water can not enter from the refrigerant space reaction tubes of reactor.Monitoring device monitoring refrigerant space by suitable, determine whether that phosgene enters the sign in refrigerant space, because exist phosgene to mean that the reaction tubes of shell and tube-type reactor is damaged in the refrigerant space.Therefore, this continuous detecting can prevent any consequent damage.The phosgene that the relative quantity of CO and chlorine can make the method produce has low cl content.Preferably use with respect to cl content be excessive 2～20 (mole) %, more preferably excessive 5～12 (mole) CO of %.Can be with any gas mixer mixing chlorine and CO of being purchased, such as the orifice mixing tank, static mixer or vortex patern mixing tank, can use the shell-type exchangers of the conventional tube with water coolant well known by persons skilled in the art or atmospheric condenser or other condensers as heat exchanger.Can use various monitoring devices to guarantee the security of system when being damaged situation, particularly when the reaction tubes corrosion.These monitoring devices should be able to stopped reaction when surpassing the predetermined trigger value, preferably, by cutting off reaction-ure feeding, equipment is converted to safe condition.
Put down-6[1994 of Japanese Patent Publication NO.] a kind of amount (for example reducing 50%) that can reduce the tetracol phenixin produced in Phosgene mfg. process with pickling and carbon that contain the activation that total amount is 1.5% (weight) or the metal component consisted of transition metal, boron, aluminium and silicon still less of-29129 disclosure employing.
Chinese invention patent application 03804716.0 " for the production of reactor and the method for phosgene " discloses gas-phase reaction under fixed bed catalyst exists of a kind of carbon monoxide and chlorine and has produced the reactor of phosgene.Reactor comprises that and bottom extending longitudinally along reactor is fixed on a branch of parallel contact pipe on base, and there is cover at the two ends of reactor.Reactor also comprises flow deflector, in the space of flow deflector between the contact pipe, perpendicular to the longitudinal direction extension of reactor, and does not stop up the access portal on reactor wall, and described access portal is disposed opposite to each other in the mode replaced.Be filled with fixed bed catalyst in the contact pipe, the gas-phase reaction mixture is introduced by reactor one end, by covering and contacting pipe, by second cover, by the reactor the other end, is left.Liquid heat transfer medium is conducted through the space between the contact pipe, and reactor is not managed in the zone of access portal.The cross section of reactor center is symmetrical to be built, and has a plurality of districts, between each district, by dividing plate, in liquid-tight mode, separate, thereby heat-transfer medium can not flow into another district in inside reactor Cong Yige district.A sheath for the Multi-stage heat galvanic couple that holds to have two or more temperature measuring points is provided at least one catalyst tube, and this sheath is at the outside opening of reactor bottom.A kind of device for preparing phosgene, wherein two or more reactors in series connect, and measurement of concetration point for residual chlorine content and/or temperature measuring point are preferably mounted at the connection place of upper reactor lower cover and lower reactor upper cover, and second reactor has than the catalyst tube of the larger diameter of inner pipe of first reactor, particularly diameter of inner pipe is 20～110mm, is preferably 60～90mm.
Chinese invention patent application 200510093948.7 " phosgene producing method and equipment " discloses a kind of method of manufacturing phosgene, wherein chlorine and carbon monoxide react under the activated-carbon catalyst existence condition in shell and tube-type reactor, this reactor comprises many reaction tubess and around the refrigerant space of reaction tubes, wherein, a) from outside, the refrigerant space by evaporative cooling makes reaction tubes cooling, and while b) operating, the pressure of reaction tubes is greater than the pressure in the refrigerant space.It is characterized in that the add-on based on chlorine, the add-on of carbon monoxide reaches excessive 2～20 % by mole, and the absolute pressure in the refrigerant space is 0.1 to 0.8 bar.The steam that condensing steps evaporates in the refrigerant space in a) again in heat exchanger, and water of condensation is recycled to the refrigerant space in heat exchanger before condensed steam, is isolated the steam that step is evaporated in the refrigerant space in a) from liquid water.Heat exchanger is positioned at the shell and tube-type reactor top, and water of condensation is returned in the refrigerant space that flows into shell and tube-type reactor under action of gravity.Coolant circulating system seals.Manufacture the equipment of phosgene by making the reaction under the activated-carbon catalyst existence condition of chlorine and carbon monoxide, comprise: a) at least one shell and tube-type reactor, it has the reaction tubes that (i) many foundation originally are arranged in parallel with each other, (ii) around the water-cooled space of each root reaction tubes, (iii) at least one allows water enter the entrance in refrigerant space, (iv) at least one makes water and/or steam leave the outlet in refrigerant space, b) at least one water circulation system, it has (i) steam/water separator, by (ii), the pipeline from outlet to steam/water separator delivering vapor/water is connected with the outlet of shell and tube-type reactor for it, carry and measure CO and chlorine by pipeline 1 and 2, then mixed.This step can be at a special gas mixer, and such as occurring in orifice mixing tank or nozzle mixer, then gaseous mixture enters shell and tube-type reactor by pipeline from below.In shell and tube-type reactor, be filled with gac in pipe.The reaction of product phosgene occurs to form in pipe.Phosgene leaves shell and tube-type reactor by the product pipeline.For the reaction heat of phosgene producing method in the shell and tube-type reactor that dissipates, water enters the refrigerant space of shell and tube-type reactor by water-in from below.Water in the refrigerant space seethes with excitement in shell and tube-type reactor, then by water outlet, with the steam/water mixture form, leaves shell and tube-type reactor, by pipeline, arrives the steam/water separator.
Chinese invention patent 00806122.X " a kind of method that is prepared phosgene by chlorine and carbon monoxide " discloses the commercial run of producing phosgene, comprises that reactor is linked in sequence, a fine adjustment reaction parameter and two consistent step method of reaction conditions height.The method is in the situation that the efficiency that periodical operation and dissemination reaction are carried out is on the low side.Therefore and the change catalyzer requires higher temperature of reaction and to the mass formation disadvantageous effect of product.Chlorine can cause the formation tetracol phenixin with contacting of gac.Other catalyzer should be able to be with the synthetic phosgene of the mode scalable, that technology simply and farthest reduces by product.The present invention relates to by chlorine and carbon monoxide by be selected from reaction on the catalyzer of metal halide scalable produce the method for phosgene, wherein, the generation of by product can be selected and prevent or reduced to the reaction parameter that comprises temperature and pressure in a wider scope.Method of the present invention makes from the chlorine of the different orders of magnitude and the synthetic high-quality phosgene of reaction of carbon monoxide when using variable reaction parameter becomes possibility.
The above several aspects of contrast patent, the object of the present invention is to provide a kind of by product few, containing the method for few free chlorine, tetracol phenixin, more low-cost, safer production phosgene.Wherein by sufficient heat, dissipate, guarantee that the gas temperature of reactor exit is lower than 100 ℃, the cl concn in phosgene, lower than 50ppm, guarantees operational safety simultaneously.
Summary of the invention
The chlorine that the CO come from gas-cleaning installation and chlor-alkali device come, after (CO gas is excessive) enters the M1 mixing tank by a certain percentage, enter shell and tube phosgene reactor C1 from top to bottom, under the activated-carbon catalyst effect, generate phosgene, low temperature, high pressure are conducive to the chemical equilibrium that phosgene generates.Catalyzed reaction is carried out at activated carbon surface, and speed of reaction depends on the uptake rate of reagent and the desorption rate of product.In general the specific absorption carbon monoxide of chlorine is easy.A newly-increased chlorine preheater B1, solve chlorine in course of conveying because temperature reduces, the poor chlorine gas liquefaction that occurs of companion's thermal effect, cause phosgene free chlorine content overproof, cause in photochmeical reaction generating Cl-TDI, thereby have a strong impact on the problem of separation circuit operating mode.For guaranteeing to react completely, after C1, be connected in series a phosgene guard reactor C2, make chlorine free in reaction product few.Reaction is thermopositive reaction, and the heat that reaction generates is derived by 60 ℃ of cooling water systems of closed cycle.The gaseous phosgene generated through phosgene condenser W1, phosgene water cooler W2 condensed in two stages, cooling after, be chilled to-10 ℃, most of phosgene is liquefied, and enters phosgene gas-liquid separation groove B2.Liquid phosgene force feed is to producing TDI use, uncooled phosgene and excessive CO, N
2reach the HCl gas that side reaction produces, enter tail gas absorber K1, with the toluene of-5 ℃, absorb contained phosgene in tail gas, reclaim the phosgene absorbed, K1 tail gas send alkali lye destruction tower to decompose to destroy wherein and arranges atmosphere after objectionable constituent.
Phosgene building-up reactions equation is:
Cl
2+CO→COCl
2+-116.7KJ/mol
The summary technical solution of the present invention is as follows:
1, a kind of method of continuous production phosgene is characterized in that:
A) the first step is the phosgene synthesis procedure, excessive CO and CL
2after entering by a certain percentage the M1 mixing tank; enter shell and tube phosgene reactor C1 from top to bottom, under the activated-carbon catalyst effect, generate phosgene, be connected in series a phosgene guard reactor C2 after C1; the heat that reaction generates is derived by 60 ℃ of cooling water systems of closed cycle, comprising:
(i) start the CO compressor and carry CO, guarantee CO pressure 0.3～0.5MPa, CO pressure reduction>=0.02MPa, CO temperature>=20 ℃, CO/CL
2ratio 1.0, CO advances the M1 valve and opens, and CO enters M1 flow>=130kg/h;
(ii) start CL
2compressor is carried CL
2, guarantee CL
2pressure 0.3～0.5MPa, CL
2pressure reduction>=0.02MPa, start CL
2preheater B1, guarantee CL
2temperature>=40 ℃, CL
2advance the M1 valve and open, CL
2enter M1 flow>=300kg/h;
(iii) CL
2after excessive CO enters M1 and mixes, enter shell and tube phosgene reactor C1 from top to bottom, generate phosgene under the activated-carbon catalyst effect, temperature raises gradually;
(iv) heat that reaction generates is derived by 60 ℃ of cooling water systems of closed cycle;
(v) react completely in the phosgene guard reactor C2 be connected in series after C1, under the activated-carbon catalyst effect, generate phosgene, make in the reaction product phosgene without free chlorine;
B) second step is that phosgene condensation and tail gas absorb operation, the gaseous phosgene generated through phosgene condenser W1, phosgene water cooler W2 condensed in two stages, cooling after, be chilled to-10 ℃, most of phosgene is liquefied, enter phosgene gas-liquid separation groove B2, liquid phosgene force feed is used to producing TDI.Uncooled phosgene and excessive CO, N
2reach the HCl gas that side reaction produces, enter tail gas absorber K1, with the toluene of-5 ℃, absorb contained phosgene in tail gas, reclaim the phosgene absorbed, K1 tail gas send alkali lye destruction tower to decompose to destroy wherein and arranges atmosphere after objectionable constituent.Comprise:
(i) gaseous phosgene generated is through phosgene condenser W1 condensation;
(ii) after the gaseous phosgene water cooler W2 generated is cooling;
(iii) be chilled to-10 ℃, most of phosgene is liquefied, and enters phosgene gas-liquid separation groove B2;
(iv) liquid phosgene force feed is used to producing TDI.
(v) uncooled phosgene and excessive CO, N
2and the HCl gas of side reaction generation, enter tail gas absorber K1, absorb contained phosgene in tail gas with the toluene of-5 ℃.
2, method according to claim 1, is characterized in that CL
2must be introduced into after chlorine preheater B1 preheating to enter again into M1 and mix with excessive CO.
3, method according to claim 1, is characterized in that controlling processing parameter and comprise: CL
2enter M1 flow 2357～4704kg/h, 45～55 ℃ of temperature, pressure 0.3～0.5MPa, pressure reduction 0.02～0.04MPa, CO enters M1 flow 1023～2046kg/h, 20～30 ℃ of temperature, pressure 0.3～0.5MPa, pressure reduction 0.02～0.04MPa, CO/CL
2ratio 1.0, 40～50 ℃ of M200 temperature outs, 40～50 ℃ of C1 head temperature, enter warm water flow>=185T/h, 65～70 ℃ of C1 warm water return water temperatures, 60～70 ℃ of C1 outlet material temperature, the C2 temperature difference≤2 ℃, 60～70 ℃ of C2 temperature outs, C2 exit phosgene free chlorine≤10ppm, W1 water coolant backwater pH value 8.5, with interior, there is the tubulation of freezing toluene to lower the temperature around B2, guarantee that in B2, phosgene is liquid phase, go out freezing toluene flux>=2500kg/h from B2, B2 liquid level 30～40%, B2 temperature-5～-10 ℃, enter K1 technique toluene 500～600kg/h, K1 tower top exhaust gas flow 124～180kg/h, at the bottom of the K1 tower, liquid level 30～58%, K1 top pressure 0.3～0.4MPa, K1 tower top exhaust gas pressure 0.01～0.03MPa, 5～10 ℃ of K1 column bottom temperatures.
4, method according to claim 1, is characterized in that: CL
2pressure reduction<0.02Mpa, CL
2advance the M1 valve closes; CL
2flow<300kg/h, CO advances the M1 valve closes; CO pressure reduction<0.02Mpa, CO advances the M1 valve closes; CO flow<130kg/h, the W2 outlet valve is closed; CO/CL
2ratio<0.95, the B2 outlet valve is closed.
5, method according to claim 1, the step that it is characterized in that driving comprises:
A) CO purges;
B) Water heating system is driven;
C) K1 drives;
D) W1, W2, B2 drive;
E) CO feeds intake;
F) CL
2feed intake.
6, method according to claim 1 is characterized in that shut-down operation comprises:
A) stop CL
2feed intake;
B) CO purges;
C)N
2purge;
D) B2 batch turning;
E) Water heating system stops;
F) K1, W1, W2 stop;
G) system and other unit are disconnected.
7, method according to claim 4 is characterized in that key points for operation comprise:
A) should strictly control CL in the production process
2feeding temperature, pressure, prevent liquefaction;
B) strictly control CO, CL
2feed ratio, guarantee CL
2react completely.
8, method according to claim 5 is characterized in that key points for operation comprise:
A) before Water heating system and the parking of W1 water coolant, C1, C2, must keep >=0.3MPa of W1 system pressure;
B) to the equipment of need maintenance, before overhauling, essential isolation thoroughly purges, and confirms without overhauling after phosgene.
9, method according to claim 1 is characterized in that C1 catalyst loading key points for operation comprise:
A) every tubulation catalyst loading is wanted evenly;
B) every tubulation bottom should keep the inertia district that 145mm is high, and the space of 30cm should be stopped in top;
C) prevent that catalyzer from falling in the C1 lower tube.
10, method according to claim 1, is characterized in that C2 catalyst loading key points for operation are that catalyzer top should be pushed down by silk screen, prevent that catalyzer from blowing out.
The accompanying drawing explanation
Accompanying drawing means that phosgenation prepares the process flow diagram of tolylene diisocyanate.
Code name explanation: B1-Cl in figure
2preheater, M1-CO, Cl
2mixing tank, C1-phosgene synthesis reactor, C2-phosgene guard reactor, W1-phosgene condenser, W2-phosgene water cooler, B2-phosgene gas-liquid separation groove, K1-tail gas absorber.
Embodiment
The following example is for further describing the inventive method.Above disclosed the spirit and scope of the present invention be not subject to the restriction of these embodiment.
Embodiment mono-
Reactor, tower process condition are controlled as following table:
Embodiment bis-
Reactor, tower process condition are controlled as following table:
Although in above illustrating, describe the present invention in detail, should be understood that, described details is only for illustrating, and those skilled in the art can make change to it within not deviating from the spirit and scope that claim of the present invention limits.
Claims (9)
1. the method for a continuous production phosgene is characterized in that:
A) the first step is the phosgene synthesis procedure, excessive CO and CL
2after entering by a certain percentage the M1 mixing tank; enter shell and tube phosgene reactor C1 from top to bottom, under the activated-carbon catalyst effect, generate phosgene, be connected in series a phosgene guard reactor C2 after C1; the heat that reaction generates is derived by 60 ℃ of cooling water systems of closed cycle, comprising:
(i) start the CO compressor and carry CO, guarantee CO pressure 0.3～0.5MPa, CO pressure reduction>=0.02MPa, CO temperature>=20 ℃, keeping the charging capacity of CO is 1023kg/h, corresponding CL
2charging capacity be 2357kg/h; The charging capacity that perhaps keeps CO is 2046kg/h, corresponding CL
2charging capacity be 4704kg/h; CO advances the M1 valve and opens, and CO enters M1 flow>=130kg/h;
(ii) start CL
2compressor is carried CL
2, guarantee CL
2pressure 0.3～0.5MPa, CL
2pressure reduction>=0.02MPa, start CL
2preheater B1, guarantee CL
2temperature>=40 ℃, CL
2advance the M1 valve and open, CL
2enter M1 flow>=300kg/h;
(iii) CL
2after excessive CO enters M1 and mixes, enter shell and tube phosgene reactor C1 from top to bottom, generate phosgene under the activated-carbon catalyst effect, temperature raises gradually;
(iv) heat that reaction generates is derived by 60 ℃ of cooling water systems of closed cycle;
(v) react completely in the phosgene guard reactor C2 be connected in series after C1, under the activated-carbon catalyst effect, generate phosgene, make in the reaction product phosgene rarely free chlorine;
B) second step is that phosgene condensation and tail gas absorb operation, the gaseous phosgene generated through phosgene condenser W1, phosgene water cooler W2 condensed in two stages, cooling after, be chilled to-10 ℃, most of phosgene is liquefied, enter phosgene gas-liquid separation groove B2, liquid phosgene force feed is to producing TDI use, uncooled phosgene and excessive CO, N
2reach the HCl gas that side reaction produces, enter tail gas absorber K1, with the toluene of-5 ℃, absorb contained phosgene in tail gas, reclaim the phosgene absorbed, K1 tail gas send alkali lye destruction tower to decompose to destroy wherein and arranges atmosphere after objectionable constituent, comprising:
(i) gaseous phosgene generated is through phosgene condenser W1 condensation;
(ii) after the gaseous phosgene phosgene water cooler W2 generated is cooling;
(iii) be chilled to-10 ℃, most of phosgene is liquefied, and enters phosgene gas-liquid separation groove B2;
(iv) liquid phosgene force feed is used to producing TDI;
(v) uncooled phosgene and excessive CO, N
2and the HCl gas of side reaction generation, enter tail gas absorber K1, absorb contained phosgene in tail gas with the toluene of-5 ℃.
2. method according to claim 1, is characterized in that controlling processing parameter and comprise: CL
2enter M1 flow 2357～4704kg/h, 45～55 ℃ of temperature, pressure 0.3～0.5MPa, pressure reduction 0.02～0.04MPa, CO enters M1 flow 1023～2046kg/h, 20～30 ℃ of temperature, pressure 0.3～0.5MPa, pressure reduction 0.02～0.04MPa, keeping the charging capacity of CO is 1023kg/h, corresponding CL
2charging capacity be 2357kg/h, the charging capacity that perhaps keeps CO is 2046kg/h, corresponding CL
2charging capacity be 4704kg/h, 40～50 ℃ of M1 temperature outs, 40～50 ℃ of C1 head temperature, enter warm water flow>=185T/h, 65～70 ℃ of C1 warm water return water temperatures, 60～70 ℃ of C1 outlet material temperature, the C2 temperature difference≤2 ℃, 60～70 ℃ of C2 temperature outs, C2 exit phosgene free chlorine≤10ppm, W1 water coolant backwater pH value 8.5, with interior, there is the tubulation of freezing toluene to lower the temperature around B2, guarantee that in B2, phosgene is liquid phase, go out freezing toluene flux>=2500kg/h from B2, B2 liquid level 30～40%, B2 temperature-5～-10 ℃, enter K1 technique toluene 500～600kg/h, K1 tower top exhaust gas flow 124～180kg/h, at the bottom of the K1 tower, liquid level 30～58%, K1 top pressure 0.3～0.4MPa, K1 tower top exhaust gas pressure 0.01～0.03MPa, 5～10 ℃ of K1 column bottom temperatures.
3. method according to claim 1, is characterized in that: CL
2pressure reduction<0.02Mpa, CL
2advance the M1 valve closes; CL
2flow<300kg/h, CO advances the M1 valve closes; CO pressure reduction<0.02Mpa, CO advances the M1 valve closes; CO flow<130kg/h, the W2 outlet valve is closed.
4. method according to claim 1, the step that it is characterized in that driving comprises:
A) CO purges;
B) Water heating system is driven;
C) K1 drives;
D) W1, W2, B2 drive;
E) CO feeds intake;
F) CL
2feed intake.
5. method according to claim 1 is characterized in that shut-down operation comprises:
A) stop CL
2feed intake;
B) CO purges;
C)N
2purge;
D) B2 batch turning;
E) Water heating system stops;
F) K1, W1, W2 stop;
G) system and other unit are disconnected.
6. method according to claim 4 is characterized in that key points for operation comprise:
A) should strictly control CL in the production process
2feeding temperature, pressure, prevent liquefaction;
B) strictly control CO, CL
2feed ratio, guarantee CL
2react completely.
7. method according to claim 5 is characterized in that key points for operation comprise:
A) before Water heating system and the parking of W1 water coolant, C1, C2, must keep >=0.3Mpa of W1 system pressure;
B) to the equipment of need maintenance, before overhauling, essential isolation thoroughly purges, and confirms without overhauling after phosgene.
8. method according to claim 1 is characterized in that C1 catalyst loading key points for operation comprise:
A) every tubulation catalyst loading is wanted evenly;
B) every tubulation bottom should keep the inertia district that 145mm is high, and the space of 30cm should be stopped in top;
C) prevent that catalyzer from falling in the C1 lower tube.
9. method according to claim 1, is characterized in that C2 catalyst loading key points for operation are that catalyzer top should be pushed down by silk screen, prevent that catalyzer from blowing out.
Priority Applications (1)
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|---|---|---|---|
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| CN103570018A (en) * | 2013-10-29 | 2014-02-12 | 嘉兴学院 | Safe phosgene preparation method and device |
| CN105197931A (en) * | 2014-11-10 | 2015-12-30 | 青岛科技大学 | Low-consumption environment-friendly efficient phosgene synthesis technology |
| CN104492237A (en) * | 2014-12-28 | 2015-04-08 | 甘肃银光聚银化工有限公司 | Recovery method of phosgene synthesis tail gas |
| CN105817183B (en) * | 2015-01-07 | 2018-04-13 | 万华化学集团股份有限公司 | A kind of method of optical self-encoding tower catalyst change |
| CN105384640B (en) * | 2015-10-26 | 2017-07-04 | 安徽广信农化股份有限公司 | A kind of tail gas treatment process of paranitrobenzoyl chloride |
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| EP3453700A1 (en) * | 2017-09-06 | 2019-03-13 | Covestro Deutschland AG | Method for cleaning equipment conveying phosgene |
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| CN109289714A (en) * | 2018-10-30 | 2019-02-01 | 甘肃银光聚银化工有限公司 | A kind of packing method of optical self-encoding catalysts |
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| CN110655079B (en) * | 2019-09-24 | 2023-03-03 | 万华化学（宁波）有限公司 | Method for preparing phosgene |
| CN113402383A (en) * | 2020-03-17 | 2021-09-17 | 上海祖玥新材料科技有限公司 | Method for synthesizing 2-ethylcaproic acid chloride by reacting 2-ethylhexanoic acid with phosgene |
| CN111995549B (en) * | 2020-09-03 | 2023-01-13 | 万华化学集团股份有限公司 | Method for producing MDI and phosgene |
| CN114146652A (en) * | 2021-12-06 | 2022-03-08 | 甘肃银光聚银化工有限公司 | Phosgene synthesis reaction waste gas recycling method |
| CN114920668B (en) * | 2022-05-13 | 2023-10-13 | 万华化学集团股份有限公司 | Method for preparing low-chlorine impurity isocyanate |
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