CN113441091A - Method for treating lost catalyst of HCl oxidation fluidized bed - Google Patents

Method for treating lost catalyst of HCl oxidation fluidized bed Download PDF

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Publication number
CN113441091A
CN113441091A CN202110853739.7A CN202110853739A CN113441091A CN 113441091 A CN113441091 A CN 113441091A CN 202110853739 A CN202110853739 A CN 202110853739A CN 113441091 A CN113441091 A CN 113441091A
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catalyst
fluidized bed
hcl
fine powder
liquid
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衡华
周波
刘一
魏立彬
李源
张宏科
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Wanhua Chemical Group Co Ltd
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Wanhua Chemical Group Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/005—Separating solid material from the gas/liquid stream
    • B01J8/0055—Separating solid material from the gas/liquid stream using cyclones
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D47/00—Separating dispersed particles from gases, air or vapours by liquid as separating agent
    • B01D47/06—Spray cleaning
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1418—Recovery of products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1456—Removing acid components
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/18—Absorbing units; Liquid distributors therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/005—Separating solid material from the gas/liquid stream
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
    • B01J8/24—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique

Abstract

The invention discloses a method for treating a lost catalyst of an HCl oxidation fluidized bed, which comprises the following steps: 1) contacting hydrogen chloride, oxygen and a catalyst to produce a process gas stream; 2) the process gas flow enters a cyclone separator, and catalyst fine powder with smaller particle size enters a quenching spraying system along with the process gas flow to carry out secondary gas-solid separation; 3) spraying and washing the process gas flow in a quenching and spraying system, and collecting washing liquid; 4) and (3) circularly concentrating the washing liquid through a cross-flow filter, returning the filtered clear liquid to a quenching spraying system to be used as spraying liquid for recycling, and sending the concentrated liquid to a sludge treatment plant after post-treatment. The invention can separate the catalyst with small particle size from the process air flow, and avoid the blockage of the heat exchanger and the device pipeline by the tiny fine powder with strong adhesion, thereby influencing the stable operation of the device. In addition, the separation mode of the catalyst fine powder is stable, and the long-period stable operation of the filter can be ensured.

Description

Method for treating lost catalyst of HCl oxidation fluidized bed
Technical Field
The invention relates to a method for treating a run-out catalyst, in particular to a method for treating a run-out catalyst of an HCl oxidation fluidized bed.
Background
In the process for producing isocyanate by a phosgene method, most of chlorine atoms are discharged in a hydrogen chloride form after carbonyl substitution, and a large amount of byproduct hydrogen chloride brings great pressure to enterprises and directly restricts the development of the isocyanate industry. The current common method for treating byproduct hydrogen chloride mainly comprises the following steps: hydrochloric acid is prepared by an absorption method, acid-base neutralization is carried out, products such as chloroethylene are prepared, chlorine is produced by HCl oxidation by a Deacon method, and the like. The Deacon method HCl oxidation process can realize the cyclic utilization of chlorine resources, the method accords with the economic development mode of resource circulation, and is vital to the promotion of the sustainable development of chlorine-related industries and the environmental protection; meanwhile, the Deacon method HCl oxidation process has the advantages of no other side reactions, simple process flow, high efficiency and the like. In the conventional catalytic oxidation of HCl using oxygen, a wide variety of different catalysts are used, for example catalysts based on ruthenium, chromium, copper, etc. Such catalyst descriptions are described, for example, in patents CN103987455A, GB676667A, CN101125297A, and CN104549360A, among which copper-based catalysts are the most potential green chemical processes for resource recycling by catalyzing the oxidation of HCl to chlorine gas because of their relatively low manufacturing cost.
The attrition strength of the HCl oxidation catalyst is one of the key indicators for its commercial application. The existing fluidized bed catalyst is fluidized in a reactor, and very severe friction exists among catalyst particles, between the catalyst particles and a wall of the reactor and between the catalyst and process gas, so that the catalyst can be broken into small particles with the particle size of 5-50 mu m and smaller fine powder along with the long-time operation of the catalyst, and the small particles and the smaller fine powder can enter a downstream shell-and-tube heat exchanger along with reaction gas to cause the blockage of the downstream shell-and-tube heat exchanger, so that the device cannot operate stably. The existing process adopts a ceramic filter to filter catalyst fine powder, and the following technical problems exist in the using process:
(1) the ceramic filter cylinder has large diameter, the processing flatness and roundness of processing equipment are difficult to ensure, and leakage is easy to occur;
(2) high requirement for heat preservation of process gas flow, and HCl and Cl2And H2Corrosive atmosphere such as O, etc., has strong corrosion to the filter, and is easy to generate low-temperature dew point corrosion;
(3) the catalyst fine powder with smaller particle size has strong adhesion, and the ceramic filter stick is easy to block;
(4) the service life of the ceramic filter element is only 2-3 years, and the operation cost is high;
(5) the ceramic filter element blowback valve is easy to leak, and the use and maintenance cost is high.
In order to avoid the above problems, effective measures are required to separate the small particles and fine powder of the lost catalyst from the process gas, so as to realize the long-period stable operation of the device.
Disclosure of Invention
The invention aims to solve the technical problem of how to solve the problem of unstable device operation caused by the blockage of a pipeline by catalyst fine powder.
In order to solve the technical problems, the invention provides a method for treating a catalyst damaged by an HCl oxidation fluidized bed. The method can separate 5-100 mu m of small catalyst particles for recycling, and can separate catalyst fine powder with smaller particle size from process gas flow, so that the tiny fine powder with stronger adhesion is prevented from blocking a heat exchanger and a device pipeline, and further the stable operation of the device is influenced. In addition, the separation mode of the catalyst fine powder is stable, and the long-period stable operation of the filter can be ensured.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a method for treating a run-out catalyst of an HCl oxidation fluidized bed comprises the following steps:
1) contacting hydrogen chloride, oxygen, and an HCl oxidation catalyst loaded in a fluidized bed to produce a process gas stream comprising chlorine, unreacted hydrogen chloride, and lost catalyst;
2) the obtained process airflow enters a cyclone separator for primary gas-solid separation, wherein catalyst small particles with the particle size of 5-100 mu m are separated, and smaller fine powder with the particle size of less than 5 mu m enters a quenching spraying system along with the process airflow for secondary gas-solid separation;
3) in a quenching spraying system, spraying and washing the entering process gas flow, washing smaller fine powder from the process gas, and collecting washing liquid;
the process gas enters a subsequent hydrochloric acid absorption system and a product refining system to recover hydrochloric acid and purify a product chlorine gas, and the partial process route is a mature process known in the field and is not further discussed and illustrated in the invention.
4) And (3) circularly concentrating the washing liquid through a cross-flow filter, returning the filtered clear liquid to a quenching spraying system to be used as spraying liquid for recycling, and feeding the concentrated liquid to a sludge treatment plant after neutralization, flocculation and filter pressing forming.
The invention sets two-stage gas-solid separation process to separate catalyst particles and catalyst fine powder with smaller particle size. The first stage gas-solid separation adopts a cyclone separator to collect and recycle small catalyst particles, but the prior art knows that the first stage gas-solid separation can only capture particles with the particle size of more than 5-10 μm, because the friction of the catalyst in a reactor is severe, part of catalyst fine powder with smaller particle size (usually less than 5 μm, and much smaller catalyst fine powder can reach nm level) exists, and the fine powder can not be separated in the cyclone separator and enters a second stage gas-solid separation process, namely, the fine powder is removed by combining quenching spray with cross flow filtration.
The catalyst fine powder separated by the cyclone separator has small average particle size and strong adhesion, if a conventional spraying and filtering mode is adopted, the pressure difference between the front and the back of the filtering rises quickly, the membrane filter is blocked quickly, and tiny particles enter the pore channels of the membrane to cause difficult regeneration, so the traditional method has no industrial applicability. The invention adopts a mode of quenching spray and cross flow filtration to effectively solve the problems, and the cleaning solution flows parallel to the membrane surface of the filter, and the shearing force generated when the cleaning solution flows through the membrane surface can take away the particles retained on the membrane surface, so that the pollution layer is always kept at a thinner level, the shutdown and production halt caused by the continuous increase of the pressure difference are avoided, and the whole operation period of the process is obviously prolonged.
In a preferred embodiment, the fluidized bed reactor has an internal diameter of 1.0 to 6.0 m.
In a preferred embodiment, the oxidation reaction conditions in step 1) are: the reaction temperature is 300 ℃ and 500 ℃, and the reaction pressure is 0.1-1.0 Mpag.
In a preferred embodiment, the process is characterized in that, in step 1), HCl is reacted with O2In a molar ratio of (1-8) to 1, preferably (2-4) to 1; the HCl mass space velocity is 100-.
In a preferred embodiment, the HCl oxidation catalyst is a supported catalyst, preferably the active component is one or more of Ru, Au, Ce, Cu, V, Be, Mg, Bi, Sb, Cr, Ce, K, and the support is TiO2Catalyst of one or more of molecular sieve, alumina and active carbon.
In a preferred embodiment, the cyclones are in one or more, preferably two or three, series;
preferably, the small catalyst particles separated by the cyclone separator are returned to the HCl oxidation fluidized bed for reuse.
In a preferred embodiment, the quenching spray adopts equipment which is one or more connected cylindrical spray towers, and spray liquid is sprayed by a spray head to cool the process gas, so that the separation and cooling of smaller fine powder in the process gas are realized.
In a preferred embodiment, the quench spray system is operated at a pressure of 0.1 to 0.5Mpag and at a temperature of 100 ℃ to 150 ℃.
In a preferred embodiment, when the clear liquid after cross-flow filtration returns to the quenching spraying system as spraying liquid to return, the temperature of the spraying liquid is adjusted to control the concentration of hydrogen chloride in the washing liquid obtained after spraying to be unchanged; for example, when the concentration of hydrogen chloride in the washing liquid tends to increase, the temperature of the spraying liquid is properly reduced to reduce the acid washed, so that the content of HCl in the discharged waste acid is maintained, the consumption of alkali liquor required by waste acid neutralization is not increased, and the energy consumption is reduced.
In a preferred embodiment, the membrane material in the cross-flow filter is one or more of silicon carbide, ceramic, silicon nitride and alumina.
In a preferred embodiment, the cross-flow filter adopts a multi-channel asymmetric structure, and the filter pore size of each channel is gradually increased from small to large along the flow direction of the clear liquid.
In a preferred embodiment, the cross-flow filter has a filtration precision of 10nm to 100 μm.
The invention preferably adopts the asymmetric structure to carry out cross flow filtration, not only can intercept catalyst fine powder through a first contacted small-aperture membrane layer, but also can reduce the contribution to filtration resistance through a membrane layer with gradually-increased filtration aperture, and meanwhile, the membrane layer with larger filtration aperture can also be used as a supporting layer to improve the supporting strength of the filter so as to ensure the stable operation of equipment and simultaneously improve the filtration precision and the separation efficiency of the catalyst fine powder, thereby realizing the aim of the invention.
In a preferred embodiment, the specific treatment method of the concentrate after cross-flow filtration is as follows:
adjusting pH to 6-9, preferably 7-8, by using 2-32 wt% NaOH solution, and then adding PAM (polyacrylamide) and PAC (polyaluminium chloride) for coagulation and flocculation, wherein the adding amount of PAM and PAC is preferably 2-5mg/L and 7-13mg/L respectively; and (3) performing filter pressing on the wastewater after the flocculation sedimentation through a plate-and-frame filter press, wherein the filter pressing pressure is 1.0-2.5Mpag, and preferably 1.5-1.8 Mpag.
The method for treating the lost catalyst of the HCl oxidation fluidized bed can separate out small catalyst particles with the particle size of 5-50 mu m and smaller fine powder in process gas flow with high separation efficiency, and can ensure the long-time stability of the pressure difference of a filter when separating the smaller fine powder, and ensure the long-period stable operation of a reaction device and a treatment system of the invention; in addition, the separated small catalyst particles can be recycled to an oxidation reaction system, clear liquid obtained after spraying treatment and cross-flow filtration of smaller fine powder can flow back to a spray tower to be used as spray liquid, the concentration of acid in the spray liquid obtained after spraying is controlled and regulated through temperature to be unchanged, and the consumption of alkali liquor in the process of neutralizing discharged waste acid is reduced.
Drawings
FIG. 1 is an overall process flow diagram of the present invention.
Detailed Description
The invention is further illustrated by the accompanying drawings and specific examples, which are given by way of illustration only and do not limit the scope of the invention.
The fluidized bed reactor adopted by the embodiment of the invention is made of Ni201, has the diameter of 4m and the height of 20m, is internally provided with a secondary cyclone separator, and is manufactured by Jiangsu Zhongsheng pressure vessel Co. The HCl material flow comes from a Wanhua chemical MDI and TDI device, wherein the HCl content is 95-99mol percent, and the CO content is 1-5mol percent. The copper catalyst is prepared by the method in example 1 of the reference patent publication CN 104785271B.
[ example 1 ]
As shown in fig. 1, the following steps are performed:
(1) charging a copper catalyst (100t) having an average particle diameter of 60 μm into a fluidized bed reactor; according to HCl 400kmol/h, O2100kmol/h, reaction temperature 400 deg.C, reaction pressure 0.5Mpag2The reaction of (1). The composition of the obtained process gas is as follows: h2O content 38 mol%, Cl238 mol% for HCl, 19 mol% for O2Content 5 mol%, HCl conversion 80%.
(2) The process gas enters the cyclone at a gas velocity of 21m/s and about 500kg/h of catalyst fines are entrained into the secondary cyclone. The separation efficiency of the catalyst fine powder in the cyclone separator was 99%, and the remaining catalyst fine powder having a particle size of 5kg/h or less was introduced into the quenching spray tower along with the process gas.
(3) Spraying and washing the process gas at the temperature of 120 ℃ under the condition of 0.2Mpag, and collecting the washing liquid.
(4) Cross-flow filter parameters: the filtration precision of the membrane layers along the flowing direction of the clear liquid is 10nm, 5 μm and 20 μm in sequence, the material of the membrane layers is SiC, and the filtration area of each membrane layer is 10m2. The washing liquid is circulated and concentrated through the cross-flow filter, and the circulation flow is 100m3H, clear liquid output 9m3H, the outflow flow of the concentrated solution is 1m3H; wherein, the content of fine powder in the washing liquid before filtration is 499mg/L, the content of catalyst fine powder in the circulating concentrated solution after filtration is 5000mg/L, and the content of catalyst fine powder in the clear liquid is 1 mg/L.
(5) And returning the filtered clear liquid to a quenching spraying system for recycling as spraying liquid, adjusting the pH of the concentrated liquid to 8 by adopting a 16 wt% NaOH solution, and then adding PAM and PAC for coagulation and flocculation, wherein the adding amount of PAM and PAC in the wastewater is 3mg/L and 10mg/L respectively. And (4) performing filter pressing forming on the wastewater after the flocculation sedimentation through a plate-and-frame filter press, and conveying the wastewater to a sludge treatment plant, wherein the filter pressing pressure is 1.8 Mpag.
The initial transmembrane pressure difference was 0.04Mpa, when the cross-flow filter pressure increased to 0.4Mpa, the run period was 20 days.
[ example 2 ]
The method comprises the following steps:
(1) charging a copper catalyst (100t) having an average particle diameter of 60 μm into a fluidized bed reactor; according to HCl 200kmol/h, O2Feeding 200kmol/h, reacting at 400 deg.C and 0.5Mpag to prepare Cl by oxidation of HCl2The reaction of (1). The composition of the obtained process gas is as follows: h2O content 24 mol%, Cl224 mol% HCl content 8 mol% O2Content 44 mol%, HCl conversion 85%.
(2) The process gas enters the cyclone at a gas velocity of 17.9m/s and about 300kg/h of catalyst fines are entrained into the secondary cyclone. The separation efficiency of the catalyst fine powder in the cyclone separator was 97%, and the remaining 9kg/h of catalyst fine powder having a smaller particle size was introduced into the quenching spray tower along with the process gas.
(3) Spraying and washing the process gas at the temperature of 130 ℃ under the condition of 0.3Mpag, and collecting the washing liquid.
(4) Cross-flow filter parameters: the filtration precision of the membrane layers along the flowing direction of the clear liquid is 60nm, 15 μm and 30 μm in sequence, the material of the membrane layers is silicon nitride, and the filtration area of each membrane layer is 16m2. The washing liquid is circularly concentrated by passing through the cross-flow filterThe circulation flow is 120m3H, clear liquid yield 15m3H, the outflow flow of the concentrated solution is 2m3H; wherein the content of the fine powder in the washing liquid before filtration is 511mg/L, the content of the catalyst fine powder in the circulating concentrated solution after filtration is 4500mg/L, and the content of the catalyst fine powder in the clear liquid is 20 mg/L.
(5) And returning the filtered clear liquid to a quenching spraying system for recycling as spraying liquid, adjusting the pH of the concentrated liquid to 9 by adopting 10 wt% NaOH solution, and then adding PAM and PAC for coagulation and flocculation, wherein the adding amount of PAM and PAC in the wastewater is 3mg/L and 10mg/L respectively. And (4) performing filter pressing forming on the wastewater after the flocculation sedimentation through a plate-and-frame filter press, and conveying the wastewater to a sludge treatment plant, wherein the filter pressing pressure is 1.6 Mpag.
The initial transmembrane pressure difference was 0.04Mpa, when the cross-flow filter pressure increased to 0.4Mpa, the run period was 12 days.
[ example 3 ]
The method comprises the following steps:
(1) charging a copper catalyst (100t) having an average particle diameter of 60 μm into a fluidized bed reactor; according to HCl 100kmol/h, O233kmol/h, reaction temperature 400 ℃, reaction pressure 0.5Mpag, and HCl oxidation to Cl2The reaction of (1). The composition of the obtained process gas is as follows: h2O content 37 mol%, Cl237 mol% for HCl, 15 mol% for O2Content 11 mol%, HCl conversion 83%.
(2) The process gas enters the cyclone separator at a gas velocity of 5.6m/s, and about 100kg/h of catalyst fines are entrained into the secondary cyclone separator. The separation efficiency of the catalyst fine powder in the cyclone separator was 96%, and the remaining 4kg/h of the catalyst fine powder having a smaller particle size was introduced into the quenching spray tower along with the process gas.
(3) Spraying and washing the process gas at the temperature of 138 ℃ under the condition of 0.4Mpag, and collecting the washing liquid.
(4) Cross-flow filter parameters: the filtration precision of the membrane layers along the flowing direction of the clear liquid is 20nm, 0.8 μm and 30 μm in sequence, the material of the membrane layers is silicon nitride, and the filtration area of each membrane layer is 20m2. The washing liquid is circularly concentrated by passing through the cross-flow filter, and the circulating flow rate is 80m3H, clear liquid output 18m3The discharge flow of the concentrated solution is 1.5m3H; wherein the content of the fine powder in the washing liquid before filtration is 191mg/L, the content of the catalyst fine powder in the circulating concentrated liquid after filtration is 2667mg/L, and the content of the catalyst fine powder in the clear liquid is 15 mg/L.
(5) And returning the filtered clear liquid to a quenching spraying system for recycling as spraying liquid, adjusting the pH of the concentrated liquid to 8 by adopting 6 wt% NaOH solution, and then adding PAM and PAC for coagulation and flocculation, wherein the adding amount of PAM and PAC in the wastewater is 3mg/L and 10mg/L respectively. And (4) performing filter pressing forming on the wastewater after the flocculation sedimentation through a plate-and-frame filter press, and conveying the wastewater to a sludge treatment plant, wherein the filter pressing pressure is 1.6 Mpag.
The initial transmembrane pressure difference was 0.04Mpa, when the cross-flow filter pressure increased to 0.4Mpa, the run period was 15 days.
[ example 4 ]
The method comprises the following steps:
(1) charging a copper catalyst (100t) having an average particle diameter of 60 μm into a fluidized bed reactor; according to HCl 500kmol/h, O2100kmol/h, reaction temperature 400 deg.C, reaction pressure 0.5Mpag2The reaction of (1). The composition of the obtained process gas is as follows: h2O content 23 mol%, Cl223 mol% HCl content 47 mol% O2Content 7 mol%, HCl conversion 50%.
(2) The process gas enters the cyclone at a gas velocity of 26.9m/s and about 600kg/h of catalyst fines are entrained into the secondary cyclone. The separation efficiency of the catalyst fine powder in the cyclone separator is 99.5%, and the rest catalyst fine powder with the particle size of less than 3kg/h enters the quenching spray tower along with the process gas.
(3) Spraying and washing the process gas at the temperature of 150 ℃ under the condition of 0.5Mpag, and collecting the washing liquid.
(4) Cross-flow filter parameters: the filtration precision of the membrane layers along the flowing direction of the clear liquid is 100nm, 10 μm and 30 μm in sequence, the material of the membrane layers is alumina, and the filtration area of each membrane layer is 12m2. The washing liquid is circulated and concentrated through the cross-flow filter, and the circulation flow is 150m3H, clear liquid yield 15m3H, the outflow flow of the concentrated solution is 2m3H; it is composed ofIn the method, the content of fine powder in the washing liquid before filtration is 132mg/L, the content of catalyst fine powder in the circulating concentrated solution after filtration is 1500mg/L, and the content of catalyst fine powder in the clear liquid is 50 mg/L.
(5) And returning the filtered clear liquid to a quenching spraying system for recycling as spraying liquid, adjusting the pH of the concentrated liquid to 7 by adopting 2 wt% NaOH solution, and then adding PAM and PAC for coagulation and flocculation, wherein the adding amount of PAM and PAC in the wastewater is 3mg/L and 10mg/L respectively. And (4) performing filter pressing forming on the wastewater after the flocculation sedimentation through a plate-and-frame filter press, and conveying the wastewater to a sludge treatment plant, wherein the filter pressing pressure is 1.4 Mpag.
The initial transmembrane pressure difference was 0.04Mpa, when the cross-flow filter pressure increased to 0.4Mpa, the run period was 10 days.
[ example 5 ]
The method comprises the following steps:
(1) charging a copper catalyst (100t) having an average particle diameter of 60 μm into a fluidized bed reactor; according to HCl 500kmol/h, O2100kmol/h, reaction temperature 400 deg.C, reaction pressure 0.5Mpag2The reaction of (1). The composition of the obtained process gas is as follows: h2O content 32 mol%, Cl2Content 32 mol%, HCl content 14 mol%, O2Content 22 mol%, HCl conversion 82%.
(2) The process gas enters the cyclone at a gas velocity of 25.9m/s and about 550kg/h of catalyst fines are entrained into the secondary cyclone. The separation efficiency of the catalyst fine powder in the cyclone separator was 99%, and the remaining catalyst fine powder having a particle size of 5kg/h or less was introduced into the quenching spray tower along with the process gas.
(3) Spraying and washing the process gas at the temperature of 130 ℃ under the condition of 0.3Mpag, and collecting the washing liquid.
(4) Cross-flow filter parameters: the filtration precision of the membrane layers along the flowing direction of the clear liquid is 50nm, 1 μm and 50 μm in sequence, the material of the membrane layers is ceramic, and the filtration area of each membrane layer is 20m2. The washing liquid is circularly concentrated by passing through the cross-flow filter, and the circulating flow rate is 120m3H, clear liquid output 20m3H, the outflow flow of the concentrated solution is 5m3H; wherein the content of fine powder in the washing solution before filtration is 205mg/L, and the washing solution is circulated after filtrationThe content of the fine catalyst powder in the concentrated solution is 1100mg/L, and the content of the fine catalyst powder in the clear solution is 18 mg/L.
(5) And returning the filtered clear liquid to a quenching spraying system for recycling as spraying liquid, adjusting the pH of the concentrated liquid to 6 by adopting a 4 wt% NaOH solution, and then adding PAM and PAC for coagulation and flocculation, wherein the adding amount of PAM and PAC in the wastewater is 3mg/L and 10mg/L respectively. And (4) performing filter pressing forming on the wastewater after the flocculation sedimentation through a plate-and-frame filter press, and conveying the wastewater to a sludge treatment plant, wherein the filter pressing pressure is 1.5 Mpag.
The initial transmembrane pressure difference was 0.04Mpa, when the cross-flow filter pressure increased to 0.4Mpa, the run period was 10 days.
Comparative example 1
Carrying out oxidation reaction according to the method and the feeding amount in the step (1), the step (2) and the step (3) of the embodiment 5, separating out 99% of catalyst fine powder in the process gas by a secondary cyclone separator, and then spraying and washing; the difference lies in that: the filter adopting the polytetrafluoroethylene membrane filter element is used for carrying out dead-end filtration on the washing liquid, and the filtration area is 10m2The filtration precision is 10 mu m, and the liquid inlet flow is 5m3H, the content of the fine catalyst powder in the concentrated solution after filtration is 1000mg/L, and the content of the fine catalyst powder in the clear solution is 10 mg/L. The initial transmembrane pressure difference is 0.04MPa, and when the filtration pressure difference rises to 0.4MPa, the operation period is 2.4 h.
Comparative example 2
Carrying out oxidation reaction according to the method and the feeding amount in the step (1), the step (2) and the step (3) of the embodiment 5, separating out 99% of catalyst fine powder in the process gas by a secondary cyclone separator, and then spraying and washing; the difference lies in that: the cross-flow filtration adopts a filter membrane with a single aperture of 10 μm, the membrane layer is made of ceramic, and the filtration area of each membrane layer is 20m2. The washing liquid is circularly concentrated by passing through the cross-flow filter, and the circulating flow rate is 120m3H, clear liquid output 20m3H, the outflow flow of the concentrated solution is 5m3H; wherein the content of fine powder in the washing liquid before filtration is 150mg/L, the content of catalyst fine powder in the circulating concentrated solution after filtration is 180mg/L, and the content of catalyst fine powder in the clear liquid is 120 mg/L.
In addition, the initial transmembrane pressure difference was 0.02MPa, when the filtration pressure difference rose to 0.4MPa, the operation period was 2 days.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and additions can be made without departing from the method of the present invention, and these modifications and additions should also be regarded as the protection scope of the present invention.

Claims (10)

1. A method for treating a lost catalyst of an HCl oxidation fluidized bed is characterized by comprising the following steps:
1) contacting hydrogen chloride, oxygen, and an HCl oxidation catalyst loaded in a fluidized bed to produce a process gas stream comprising chlorine, unreacted hydrogen chloride, and lost catalyst;
2) the obtained process airflow enters a cyclone separator for primary gas-solid separation, wherein catalyst small particles with the particle size of 5-100 mu m are separated, and smaller fine powder with the particle size of less than 5 mu m enters a quenching spraying system along with the process airflow for secondary gas-solid separation;
3) in a quenching spraying system, spraying and washing the entering process gas flow, washing smaller fine powder from the process gas, and collecting washing liquid;
4) and (3) circularly concentrating the washing liquid through a cross-flow filter, returning the filtered clear liquid to a quenching spraying system to be used as spraying liquid for recycling, and feeding the concentrated liquid to a sludge treatment plant after neutralization, flocculation and filter pressing forming.
2. The method for treating the run-out catalyst of the HCl oxidation fluidized bed according to claim 1, wherein the oxidation reaction conditions in step 1) are as follows: the reaction temperature is 300 ℃ and 500 ℃, and the reaction pressure is 0.1-1.0 Mpag.
3. The method for treating a catalyst lost from an HCl oxidation fluidized bed according to claim 2, wherein in step 1), HCl and O are mixed2In a molar ratio of (1-8) to 1, preferably (2-4) to 1; the HCl mass space velocity is 100-.
4. The method for treating the escaping catalyst of the HCl oxidation fluidized bed according to claim 3, characterized in that the HCl oxidation catalyst is a supported catalyst, preferably the active component is one or more of Ru, Au, Ce, Cu, V, Be, Mg, Bi, Sb, Cr, Ce and K, and the carrier is TiO2Catalyst of one or more of molecular sieve, alumina and active carbon.
5. The method of claim 1, wherein the cyclone is one or more in series;
preferably, the small catalyst particles separated by the cyclone separator are returned to the HCl oxidation fluidized bed for reuse.
6. The method as claimed in claim 1, wherein the operating pressure in the quenching spray system is 0.1-0.5Mpag, and the operating temperature is 100-150 ℃.
7. The method for treating the catalyst loss of the HCl oxidation fluidized bed according to any one of claims 1 to 6, wherein when the clear solution after cross-flow filtration returns to the quenching spray system as spray solution, the temperature of the spray solution is adjusted to control the concentration of hydrogen chloride in the wash solution obtained after spraying to be constant.
8. The method for treating the HCl oxidation fluidized bed run-away catalyst, according to any one of claims 1 to 7, wherein the cross-flow filter adopts a multi-channel asymmetric structure, and the filter pore size of each channel is gradually increased from small to large along the flow direction of the clear liquid.
9. The method for treating the HCl oxidation fluidized bed run-away catalyst according to any one of claims 1 to 8, wherein the cross-flow filter has a filtration precision of 10nm to 100 μm.
10. The method for treating the HCl oxidation fluidized bed run-away catalyst according to any one of claims 1 to 9, wherein the specific treatment method of the concentrated solution after cross-flow filtration is as follows:
adjusting pH to 6-9, preferably 7-8, with 2-32 wt% NaOH solution, and adding PAM and PAC for coagulation and flocculation; and (3) performing filter pressing on the wastewater after the flocculation sedimentation through a plate-and-frame filter press, wherein the filter pressing pressure is 1.0-2.5Mpag, and preferably 1.5-1.8 Mpag.
CN202110853739.7A 2021-07-28 2021-07-28 Method for treating lost catalyst of HCl oxidation fluidized bed Pending CN113441091A (en)

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