Background technology
Adopting hydrocarbon gas is the feedstock production ammonia-synthesizing material gas, industrialized the earliest technological process is the normal pressure partial oxidation, development along with the metallurgical technology technology, the processing and fabricating of high temperature alloy conversion tube (as HK-40, HP-Nb) has obtained solution, and hydrocarbon gas steam under pressure conversion process has just replaced the normal pressure partial oxidation technology.Up to now, transfer pressure is brought up to 3.0~4.3MPa from normal pressure, and industrial scale also maximizes day by day, and single series synthetic ammonia maximum-norm is 1700MTPD in the world today, and single series methyl alcohol maximum-norm is more than the 2540MTPD.Tradition synthesis gas preparation technology, no matter be the normal pressure partial oxidation process, the continuous conversion process that perhaps pressurizes all be high-temperature technology gas directly to be imported waste heat boiler produce high-parameters steam, and the required heat of hydrocarbon gas steam reforming has to solve by a part of hydrocarbons that burns.
The core of energy-saving technique is exactly to reduce the consumption of burning with hydrocarbons as far as possible, thereby realizes the autothermal balance or the half autothermal balance of conversion process process.
For autothermal balance or the half autothermal balance that realizes conversion process, just set about developing heat exchange type abroad since the eighties in last century and transform gas-making process.Realizing industrialized the earliest is the LCA technology of Britain I.C.I company, and its industrial scale is 300~450MTPD.This process using heat-exchanged reformer replaces traditional external-heat one-stage converter, and with the portion C H of one-stage converter
4The steam reforming load is shifted to secondary reformer, in secondary reformer, add excess air, to keep the autothermal balance of system, be used to simultaneously carry out heat exchange outside the heat exchange type primary reformer tubes and between the inner reaction tube thing, so that the required heat of hydrocarbons steam reforming reaction in the pipe to be provided from the high-temperature technology gas of secondary reformer.In order to satisfy ammonia synthesis reaction to H in the unstripped gas
2/ N
2Requirement, be provided with the PSA device, removing the excess nitrogen of the system that brings into excess air, also remove CO simultaneously
2Gas.LCA technology is removing excessive N
2Process in, caused certain amount of H
2Loss, in order to overcome this shortcoming, lattice sieve De-Nol nitrogen synthesis of Byelorussia adopts two sections conversion process of string oxygen-rich air behind the heat exchange type one-stage converter, thereby has both reached system's autothermal equilibrated purpose, does not have H again
2The loss problem just need be provided with cover PSA air separation (or empty branch) device in addition.
In last century end, I.C.I has succeeded in developing the LCM technology that is used to produce methyl methanol syngas on LCA technology basis, promptly uses to add pure oxygen to replace excess air in secondary reformer.Meanwhile, also succeed in developing the heat exchange type oxygen-rich air at home in succession and transformed the system ammonia-synthesizing material gas, the heat-exchanging type parallel conversion is connected with heat exchange type to transform and is prepared ammonia-synthesizing material gas technology, and the heat exchange type pure oxygen transforms system methyl alcohol synthetic raw gas and two sections conversion systems of heat-exchanging type parallel conversion string pure oxygen methyl alcohol synthetic raw gas for two sections.
But all exist natural gas source not to be fully used in the above technology, methanol production and carbonylation of methanol acetic acid production can not be united and carry out, need a large amount of combustion fuel gas and can not fundamentally solve hydrogen and the unbalanced problem of carbon.
Summary of the invention
Main purpose of the present invention is to make full use of natural gas source, methanol production and carbonylation of methanol acetic acid production can be united and carry out, use, reduce fuel gas consumption to realize resources circulation, energy-saving and cost-reducing, minimizing is invested and the reduction of erection time, and is fundamentally solved hydrogen and the unbalanced problem of carbon.
In order to achieve the above object, the invention provides a kind of hydrocarbon vapours heat-exchanging type parallel and transform the method for preparing CO and synthetic gas.The unstripped gas that contains hydrocarbons that present method adopts is Sweet natural gas, liquefied petroleum gas (LPG) or coal mine gas, and its technological process is as follows:
A, the unstripped gas that will contain hydrocarbons mixes the back shunting with water vapour, enter an external-heat one-stage converter respectively, one first heat exchange type one-stage converter and one second heat exchange type one-stage converter, one section steam reforming reaction of hydrocarbons is carried out in described external-heat one-stage converter and the described first and second heat exchange type one-stage converter parallel operations, the heat energy of two sections reforming gas of high temperature that hydrocarbon steam conversion reaction institute heat requirement generates from one first secondary reformer and one second secondary reformer respectively in the described first heat exchange type one-stage converter and the second heat exchange type one-stage converter, this heat obtains by the indirect heat exchange between two sections reforming gas of high temperature and the heat exchange type one-stage converter inner reaction tube thing; Described external-heat one-stage converter is chewed combustion fuel gas by burning, for the hydrocarbon steam conversion reaction provides heat; Described first secondary reformer and second secondary reformer that enter two parallel operations after one section reforming gas that described external-heat one-stage converter, the first heat exchange type one-stage converter and the second heat exchange type one-stage converter generate mixes respectively carry out CH
4Degree of depth conversion reaction adds CO simultaneously in described first secondary reformer and second secondary reformer
2Gas is in order to regulate the H of the two sections reforming gas of high temperature that generate
2/ C ratio, or in described first secondary reformer and second secondary reformer, add pure oxygen, in order to keep minimum N in two sections reforming gas of system's thermal equilibrium and high temperature
2Content, or add the unstripped gas contain hydrocarbons in described first secondary reformer and second secondary reformer is in order to the content that increases CO in two sections reforming gas of high temperature and can be energy-conservation;
B, from two sections reforming gas of high temperature of described first secondary reformer heat is offered the described first heat exchange type one-stage converter after, after heat recovery equipment reduces temperature, enter the CO tripping device again, cutting out partial CO; After from two sections reforming gas of high temperature of described second secondary reformer heat being offered the described second heat exchange type one-stage converter, after heat recovery equipment reduces temperature, and mixes, be used as synthetic gas from the tail gas behind the separation of C O of described first secondary reformer.
The pressure that enters the gas mixture of interior unstripped gas of described external-heat one-stage converter, the first heat exchange type one-stage converter and the second heat exchange type primary reformer tubes and water vapor in above-mentioned preparation method's steps A is 0.2~4MPa, and temperature is 400~600 ℃; One section reforming gas temperature of the outlet of the described first heat exchange type one-stage converter and the second heat exchange type one-stage converter is 500~750 ℃, CH
4Butt mol ratio therein is 12~35%; One section reforming gas temperature of the outlet of described external-heat primary reformer tubes is 600~900 ℃, CH
4Butt mol ratio 2~16% therein; Two sections reforming gas temperature of the high temperature of the outlet of described first secondary reformer and the second secondary reformer converter are 800~1050 ℃.
CO described in above-mentioned preparation method's steps A
2Be from the combustion product gases of described external-heat one-stage converter, to reclaim acquisition.Described combustion product gases is reclaiming CO
2Before, the CO that is provided with the convection zone of described external-heat one-stage converter
2Preheat coil, hydro carbons gas/steam preheating coil pipe, hydro carbons gas preheat coil, oxygen preheat coil pipe and the heat exchange of combustion air preheat coil after self temperature reduces, just enter stack gas recovery CO
2Device.
H in the synthetic gas that above-mentioned preparation method receives
2, CO and CO
2Gas composition meets the following conditions, and can be used for the low pressure methanol synthesis technique:
In the formula: f-ratio, no unit,
H
2The molar flow of-hydrogen, kmol/h,
CO
2The molar flow of-carbonic acid gas, kmol/h,
The molar flow of CO-carbon monoxide, kmol/h.
The CO that above-mentioned preparation method prepares can be used as the methanol carbonyl synthesized acetic acid unstripped gas, and the synthetic gas of acquisition can be used as the methyl alcohol synthetic raw gas.
The present invention also provides a kind of method of utilizing synthesis gas preparation methyl alcohol, the H that the off-gas that produces in the described synthesis gas preparation methanol process obtains through separation
2, rich CO
2Gas and tail gas turn back to again in the synthesis gas preparation process, realize resource circulation utilization.The technological process of this method is as follows:
A, will contain hydrocarbons unstripped gas and described methyl alcohol building-up process in the off-gas that produces through separating the H that obtains
2Mix the back shunting with water vapour, enter an external-heat one-stage converter respectively, one first heat exchange type one-stage converter and one second heat exchange type one-stage converter, one section steam reforming reaction of hydrocarbons is carried out in described external-heat one-stage converter and described first one-stage converter and the second heat exchange type one-stage converter parallel operation, the heat energy of two sections reforming gas of high temperature that hydrocarbon steam conversion reaction institute heat requirement generates from one first secondary reformer and one second secondary reformer respectively in the described first heat exchange type one-stage converter and the second heat exchange type one-stage converter, it obtains by the indirect heat exchange between two sections reforming gas of high temperature and the heat exchange type one-stage converter inner reaction tube thing; Described external-heat one-stage converter is chewed combustion fuel gas by burning, for hydrocarbon steam conversion reaction provides heat, wherein part of fuel gas from the off-gas that produces in the described methyl alcohol building-up process through separating H
2With rich CO
2The tail gas that obtains behind the gas; Described first secondary reformer and second secondary reformer that enter two parallel operations after one section reforming gas that described external-heat one-stage converter, the first heat exchange type one-stage converter and the second heat exchange type one-stage converter generate mixes respectively carry out CH
4Degree of depth conversion reaction adds simultaneously the off-gas that produces in the described methyl alcohol building-up process through separating the rich CO that obtains in described first secondary reformer and second secondary reformer
2Gas is in order to regulate the H of the two sections reforming gas of high temperature that generate
2/ C ratio, or in described first secondary reformer and second secondary reformer, add pure oxygen, in order to keep minimum N in two sections reforming gas of system's thermal equilibrium and high temperature
2Content, or add the unstripped gas contain hydrocarbons in described first secondary reformer and second secondary reformer is in order to the content that increases CO in two sections reforming gas of high temperature and can be energy-conservation;
B, from two sections reforming gas of high temperature of described first secondary reformer heat is offered the described first heat exchange type one-stage converter after, after heat recovery equipment reduces temperature, enter the CO tripping device again, cutting out partial CO; After from two sections reforming gas of high temperature of described second secondary reformer heat being offered the described second heat exchange type one-stage converter, after heat recovery equipment reduces temperature, with mix from the tail gas behind the separation of C O of described first secondary reformer, as synthetic gas.
Enter unstripped gas, H in described external-heat one-stage converter, the first heat exchange type one-stage converter and the second heat exchange type primary reformer tubes among the above-mentioned processing step A
2With the pressure of the gas mixture of water vapour be 0.2~4MPa, temperature is 400~600 ℃; One section reforming gas temperature of the outlet of the described first heat exchange type one-stage converter and the second heat exchange type one-stage converter is 500~750 ℃, CH
4Butt mol ratio therein is 12~35%; One section reforming gas temperature of the outlet of described external-heat primary reformer tubes is 600~900 ℃, CH
4Butt mol ratio therein is 2~16%; Two sections reforming gas temperature of the high temperature of the outlet of described first secondary reformer and the second secondary reformer converter are 800~1050 ℃.
The adoptable device (or method) of separation of C O that is used for from cooled second stage exit gas comprises that PSA separates adsorption unit among the above-mentioned preparation method, and Deep Cooling Method separation of C O, or complexed absorption separation of C O recommend to use PSA to separate adsorption unit.
Hydrocarbons steam reforming reaction such as methane is in the heat exchange type primary reformer tubes of the present invention and in the external-heat primary reformer tubes:
In secondary reformer owing to added pure oxygen, CO to secondary reformer
2Reach hydrocarbons such as methane, so its steam reforming reaction is:
The synthetic gas that this preparation method obtained can be used for the unstripped gas of methyl alcohol and acetic acid process for combination producing process, also can produce methyl alcohol separately, and to provide purity to other user simultaneously be 99.8% high-purity CO product gas.The present invention has following characteristics:
1. be better than traditional external-heat steam reforming technology, it can utilize two sections reforming gas of high temperature of secondary reformer outlet to add the interior reactant of heat exchange type primary reformer tubes, for its steam reforming reaction provides essential heat, the fuel gas consumption and the combustion product gases quantity discharged of external-heat converter have been significantly reduced, reduced the thermosteresis that fume emission caused, improve envrionment conditions, realized half autothermal balance of hydrocarbon steam conversion reaction process substantially.
2. unstripped gas is divided into three bursts of tributaries, in the heat exchange type one-stage converter of two parallel connections and an external-heat one-stage converter, carry out one section conversion reaction respectively, the transforming degree of each tributary hydrocarbon gas can have nothing in common with each other, thus some operational condition in each tributary such as gas flow, temperature out, CH
4Content etc. can be different, is convenient to the operational load of each converter of flexible.Every interior CO that is added of secondary reformer
2Gas and unstripped gas also can according to the synthetic gas moiety difference require to regulate, thereby solved hydrogen and the unbalanced problem of carbon in the synthetic gas fully.
3. can realize methyl alcohol and acetic acid combination producing, realize the resources circulation use, thereby reduce every consumption indicators greatly.
4. this preparation method's external-heat one-stage converter and secondary reformer combination, be traditional hydrocarbon steam conversion technical process, therefore, even if the heat exchange type one-stage converter is out of order, unstripped gas can not remove the heat exchange type one-stage converter, directly enter the external-heat one-stage converter, and make this technological process keep normal operation.
Embodiment
Referring to Fig. 1, the unstripped gas that contains hydrocarbons through manage 1 (or with from pipeline 3 by the methanol synthetic discharged gas delayed H that obtains that separates
2After the mixing) the unstripped gas preheat coil that enters in the convection zone of external-heat one-stage converter 9 is preheated to 250~430 ℃, enters hydrodesulphurisatioreactors reactors 6 to remove the deleterious sulphur of follow-up operation through pipeline 5 then, and catalyzer is housed in the reactor.The qualified gas of desulfurization is flowed out by pipeline 7 and with (pressure is 0.3~4.5MPa) to mix from the technological process steam of pipeline 33, be process feed gas, enter external-heat one-stage converter convection zone Sweet natural gas/steam preheating coil pipe, make temperature rise to 400~600 ℃, pressure is 0.2~4MPa, through pipeline 8 enter respectively heat exchange type one-stage converter 10,10 ' and the conversion tube of external-heat one-stage converter 9 in, catalyzer all is housed in these conversion tubes.In heat exchange type one-stage converter 10 and 10 ',, make unstripped gas and water vapor generation chemical reaction and generate CO and H by means of two sections heats that reforming gas provided of the high temperature that comes from secondary reformer 14 and 14 ' between the pipe of conversion tube respectively
2In external-heat one-stage converter 9, still going up the burning that is provided with by means of furnace roof (or furnace wall) chews, a certain amount of combustion heat of being emitted by the fuel gas of pipeline 37 that burns is kept itself and the required heat of steam reforming reaction, in addition, carry combustion air to chew by pipeline 27, promote the fuel gas burning to burning.After two heat exchange type one-stage converters 10 and 10 ' proceeded to a certain degree with external-heat one-stage converter 9 conversion reaction separately, one section reforming gas temperature of heat exchange type one-stage converter outlet was 500~750 ℃, CH
4Butt mol ratio therein is 12~35%, and one section reforming gas temperature of the outlet of external-heat primary reformer tubes is 600~900 ℃, CH
4Butt mol ratio therein is 2~16%.One section reforming gas of above-mentioned each one-stage converter flows out to merge through separately outlet pipe respectively and enters secondary reformer 14 and 14 ' through house steward 12 through pipeline 13, and catalyzer is housed in the secondary reformer.Technology with oxygen through pipeline 2 with mix from the small amount of steam of pipeline 33, enter external-heat converter convection zone, be preheated to 250~350 ℃.Enter secondary reformer 14 and 14 ' respectively through pipeline 15, with from one section reforming gas of pipeline 13 after fierce turbulence mixes, at first in the combustion reactions of furnace roof generation hydrogen and oxygen, for continue after the conversion reaction of the methane degree of depth essential heat is provided.From the next CO of combustion product gases retrieving arrangement
2By pipeline 4 with mix from the small amount of steam of pipeline 33 after enter external-heat converter 9 convection zones and be preheated to 300~450 ℃ after, through pipeline 35 with enter secondary reformer after one section reforming gas through pipeline 13 mixes.Enter the burner of secondary reformer without a part of unstripped gas of one-stage converter through pipeline 36, carry out turbulence with one section reforming gas and technology with oxygen simultaneously and mix, and carry out partial oxidation reaction in on-catalytic conversion reaction space.When two sections conversion reactions proceed to a certain degree, be that temperature out is when reaching 800~1050 ℃, secondary reformer 14 is worked off one's feeling vent one's spleen and is entered between the pipe of heat exchange type one-stage converter 10 through pipeline 16, high-order reformed gas waste heat is passed to the interior reactant of pipe, self temperature is reduced to 500~750 ℃, enter the A end of reforming gas boiler 26 through pipeline 17, further reclaim heat in the reformed gas with the byproduct steam form, then through feedwater preheater 28 and water cooler 29, enter PSA transformation adsorption separation device 32 through pipeline 19 again, part CO in the reformed gas is separated, send to the unstripped gas of making methanol carbonyl synthesized acetic acid, the tail gas behind the separation of C O is because of containing a large amount of H
2, CO
2And effective ingredient such as CO, send to work off one's feeling vent one's spleen from secondary reformer 14 ' and mix without two sections reforming gas of PSA after, be used as the methyl alcohol synthetic raw gas.Two sections reforming gas that come out from secondary reformer 14 ' enter between the pipe of heat exchange type one-stage converter 10 ' through pipeline 22, the reforming gas waste heat is passed to the inner reaction tube thing, after self temperature is reduced to 500~750 ℃, enter the B end of reforming gas waste-heat boiler 26 through pipeline 23, reclaim heat in the reforming gas in the byproduct steam mode, the reforming gas temperature that the pot 26B that goes out to give up holds is reduced to 180~350 ℃, enter feedwater preheater 30 through pipeline 24 and further reclaim heat, finally draw and be chilled to about 40 ℃ through water cooler 31, through pipeline 25 with mix from the tail gas of PSA tripping device through pipeline 20, send and make methyl methanol syngas.
Convection zone at external-heat one-stage converter 9 is provided with CO
2Gas, Sweet natural gas/steam, Sweet natural gas, technology reclaim heat after pipeline 34 send flue gas to reclaim CO with preheat coils such as oxygen and combustion air, stack gas through these preheat coils
2Device.The steam that reforming gas boiler 26 is produced divides through drum to enter native system by pipeline 33 after dried up.
Mix the synthetic gas that obtains with reforming gas in the process of synthesizing methanol from the tail gas behind the PSA tripping device cutting out partial CO, from the off-gas that produces, separate the H that obtains by pipeline 25
2, rich CO
2Gas and tail gas are got back to pipeline 3 again respectively, and pipeline 35 and pipeline 37 (tail gas act as a fuel gas) position realizes that resources circulation uses.
But since material quantity and other production control parameter independent regulation in each converter in this technological process, separation of C O
2Amount also can control, therefore can guarantee that the synthetic gas that obtains can be used in the low pressure methanol synthesis technique.
It should be noted last that: above embodiment is the unrestricted technical scheme of the present invention in order to explanation only, although the present invention is had been described in detail with reference to the foregoing description, those of ordinary skill in the art is to be understood that, still can to the present invention make amendment and or be equal to replacement, and do not break away from the spirit and scope of the present invention.