Carbon monoxide sulfur-free isothermal transformation process and equipment

Abstract

The invention discloses a carbon monoxide sulfur-free isothermal conversion technology and equipment, and the technology comprises the following steps: S1, adjusting the water-gas ratio of a raw material gas containing carbon monoxide to 0.1-0.4, and carrying out first-stage sulfur-free isothermal conversion to obtain a first-stage converted gas; and S2, adjusting the water-gas ratio of the first-stage shift gas to 0.2-0.8, and then carrying out second-stage sulfur-free isothermal shift to obtain second-stage shift gas. The two-stage sulfur-free isothermal conversion process is adopted to control the temperature in stages, the reaction rate is reduced in the first-stage sulfur-free isothermal conversion process in a mode of combining the high carbon monoxide content with the low water-gas ratio, the water-gas ratio is increased in the second-stage sulfur-free isothermal conversion process, and the reaction rate is increased in the mode of combining the low carbon monoxide content with the high water-gas ratio. The hot-spot temperature and the outlet temperature are successfully controlled below 240 DEG C, the problem of overtemperature in the sulfur-free shift process is finally solved, and the service life of the catalyst is greatly prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of carbon monoxide conversion, and in particular to a sulfur-free isothermal conversion process and equipment for carbon monoxide. Background Art

[0002] The carbon monoxide shift process uses the effect of catalysts to make carbon monoxide react with water vapor under certain conditions to generate hydrogen and carbon dioxide. At the same time, a heat exchange unit is set inside the catalyst bed to maintain the shift reaction at the catalyst tolerance temperature, prevent the catalyst bed from overheating, and make the shift reaction as close to the optimal temperature curve as possible. Among them, hydrogen is a clean energy.

[0003] The carbon monoxide conversion process releases a lot of heat and is a thermodynamically controlled process. In industry, high conversion rates and selectivity can only be achieved under the action of catalysts. Among them, when there is a large amount of sulfur-containing gas in the conversion gas, a sulfur-resistant catalyst will be used for the conversion reaction. When there is no sulfur or the sulfur content in the conversion gas is extremely low, a low-temperature copper-based catalyst that is insensitive to sulfur or has weak sulfur resistance will be used. This type of catalyst can maintain good activity and stability in a sulfur-free environment. The catalyst is used at a low temperature, usually between 160°C and 260°C. The initial use requires a temperature below 240°C, and the final use temperature is around 260°C. If it exceeds 260°C, the catalyst will quickly deactivate. At present, researchers are committed to improving the structure of the conversion reactor, hoping to improve the heat transfer efficiency of the conversion reactor itself. The sulfur-free conversion process usually uses a one-stage sulfur-free isothermal conversion, which has the problem of a short catalyst life cycle. Summary of the invention

[0004] Based on this, it is necessary to provide a carbon monoxide sulfur-free isothermal conversion process and equipment that can reduce the hot spot temperature and thus extend the service life of the catalyst.

[0005] In one aspect of the present application, a carbon monoxide sulfur-free isothermal shift process is provided, comprising the following steps:

[0006] S1, adjusting the water-gas ratio of the raw gas containing carbon monoxide to 0.1-0.4, and then performing a first-stage sulfur-free isothermal shift to obtain a first-stage shifted gas;

[0007] S2, after adjusting the water-gas ratio of the primary conversion gas to 0.2-0.8, performing a secondary sulfur-free isothermal conversion to obtain a secondary conversion gas.

[0008] The process of the present application adopts a two-stage sulfur-free isothermal transformation process to control the temperature in stages. In the first-stage sulfur-free isothermal transformation process, a high carbon monoxide content combined with a low water-gas ratio is used to reduce the reaction rate and control the transformation depth. The heat load is reduced by reducing the transformation depth to ensure that the reaction heat can be removed in time during the first-stage sulfur-free isothermal transformation process, so that the hotspot temperature and the outlet temperature of the first-stage sulfur-free isothermal transformation reaction can be controlled below 240°C; then, the water-gas ratio is increased during the second-stage sulfur-free isothermal transformation process. Since the carbon monoxide concentration has been reduced after the first-stage sulfur-free isothermal transformation, the hotspot temperature and the outlet temperature of the second-stage sulfur-free isothermal transformation reaction are controlled below 240°C by using a low carbon monoxide content combined with a high water-gas ratio. Finally, the whole process temperature is successfully controlled within the catalyst use temperature range, the overheating problem of the sulfur-free transformation process is solved, and the service life of the catalyst is extended, and the carbon monoxide content (V% dry basis) at the outlet of the second-stage sulfur-free isothermal transformation is controlled within 0.5%~20%. The present application connects two stages of sulfur-free isothermal conversion processes in series, and controls the conversion depth by adjusting the water-gas ratio at each stage, thereby reducing the heat load step by step and extending the catalyst service life. The carbon monoxide conversion rate of the catalyst during the same period is much higher than that of the existing process.

[0009] In some embodiments, in S1, the water-gas ratio of the raw gas is adjusted to 0.1-0.3.

[0010] In some embodiments, in S2, the water-gas ratio of the primary conversion gas is adjusted to 0.2-0.6.

[0011] In some embodiments, in S1, before adjusting the water-gas ratio, the following step is further included: adjusting the temperature of the raw gas to 160°C-190°C.

[0012] In some of the embodiments, in S1, the hot spot temperature in the primary sulfur-free isothermal shift reaction is ≤240°C.

[0013] In some of the embodiments, in S2, the hot spot temperature in the secondary sulfur-free isothermal shift reaction is ≤240°C.

[0014] In some embodiments, the raw gas satisfies at least one of the following conditions:

[0015] (1) The carbon monoxide content of the raw gas on a dry basis is greater than 60% by volume;

[0016] (2) The sulfur content of the raw gas is less than 0.1 pppmv;

[0017] (3) The pressure of the raw gas is 0.5 MpaG ~3.5 MpaG.

[0018] In some of the embodiments, a copper-based shift catalyst is used in the primary sulfur-free isothermal shift reaction and / or the secondary sulfur-free isothermal shift reaction.

[0019] In some embodiments, the feed gas is a desulfurized tail gas with a high carbon monoxide content.

[0020] In some of the embodiments, in S1, the dry volume content of carbon monoxide in the primary conversion gas is 25% to 45%.

[0021] In some embodiments, in S1, the temperature of the primary shifted gas is ≤240°C.

[0022] In some of the embodiments, in S2, the dry volume content of carbon monoxide in the secondary conversion gas is 0.5% to 15%.

[0023] In some embodiments, in S2, the temperature of the secondary shifted gas is ≤240°C.

[0024] In some of the embodiments, in S1, the primary sulfur-free isothermal shift reaction also produces a low-pressure saturated steam by-product of 0.6 MPaG to 2.0 MPaG.

[0025] In some of the embodiments, in S2, the secondary sulfur-free isothermal shift reaction also produces a low-pressure saturated steam by-product of 0.6 MPaG to 2.0 MPaG.

[0026] The second aspect of the present application provides a carbon monoxide sulfur-free isothermal conversion device, including a primary water-gas ratio adjustment device, a primary sulfur-free isothermal conversion device, a secondary water-gas ratio adjustment device, and a secondary sulfur-free isothermal conversion device, wherein the gas outlet of the primary water-gas ratio adjustment device is connected to the gas inlet of the primary sulfur-free isothermal conversion device, the gas outlet of the primary sulfur-free isothermal conversion device is connected to the gas inlet of the secondary water-gas ratio adjustment device, and the gas outlet of the secondary water-gas ratio adjustment device is connected to the gas inlet of the secondary sulfur-free isothermal conversion device.

[0027] The above-mentioned equipment adopts a two-stage series connection of a primary sulfur-free isothermal conversion device and a secondary sulfur-free isothermal conversion device, and at the same time adjusts the water-gas ratio of the inlet of the primary sulfur-free isothermal conversion device through a primary water-gas ratio adjustment device to reduce the reaction rate, so as to ensure that the reaction heat can be removed in time during the primary sulfur-free isothermal conversion process, so that the hotspot temperature and the outlet temperature of the primary sulfur-free isothermal conversion reaction can be controlled below 240°C; the water-gas ratio of the inlet of the secondary sulfur-free isothermal conversion device is adjusted through a secondary water-gas ratio adjustment device, and the hotspot temperature and the outlet temperature of the secondary sulfur-free isothermal conversion reaction can be controlled below 240°C by using a low load and a high water-gas ratio; finally, the whole process temperature is successfully controlled within the catalyst use temperature range, the overheating problem of the sulfur-free conversion process is solved, and the service life of the catalyst is greatly extended.

[0028] In some of the embodiments, the apparatus further comprises a feed heat exchange device, and a gas outlet of the feed heat exchange device is connected to a gas inlet of the first-stage water-gas ratio adjustment device.

[0029] In some of the embodiments, a purification device is provided between the first-stage water-gas ratio adjustment device and the first-stage sulfur-free isothermal conversion device.

[0030] In some of the embodiments, the first-stage sulfur-free isothermal conversion device is provided with a first-stage heat transfer device.

[0031] In some of the embodiments, the secondary sulfur-free isothermal conversion device is provided with a secondary heat transfer device.

[0032] In some of the embodiments, the first-stage sulfur-free isothermal conversion device and / or the second-stage sulfur-free isothermal conversion device has a built-in copper-based conversion catalyst bed.

[0033] In some of the embodiments, the gas outlet of the purification device is respectively connected to the gas inlet of the first-level sulfur-free isothermal conversion device and the gas inlet of the second-level water-gas ratio adjustment device, and a valve is provided on the pipeline between the purification device and the second-level water-gas ratio adjustment device. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic structural diagram of a carbon monoxide sulfur-free isothermal conversion device according to one embodiment.

[0035] Description of reference numerals:

[0036] 1. Feed heat exchange device; 2. Primary water-gas ratio adjustment device; 3. Purification device; 4. Primary sulfur-free isothermal conversion device; 4.1. Primary heat transfer device; 5. Secondary water-gas ratio adjustment device; 6. Secondary sulfur-free isothermal conversion device; 6.1. Secondary heat transfer device; Valve 7. DETAILED DESCRIPTION

[0037] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0039] Water-gas ratio: The water-gas ratio refers to the volume ratio of water vapor to dry process gas in the raw gas.

[0040] Hot spot temperature: Hot spot temperature refers to the temperature of the highest point in the catalyst bed.

[0041] Sulfur-free isothermal shift: isothermal shift process with total sulfur content in the feed gas less than 0.1ppmv.

[0042] Traditional sulfur-free isothermal shift reactors with high CO have an over-temperature problem. The hot spot temperature usually exceeds 280°C, while the catalyst operating temperature of sulfur-free isothermal shift is usually between 160°C and 260°C. Over-temperature shortens the catalyst life cycle, and a water-gas ratio greater than 0.5 is required to achieve a satisfactory carbon monoxide conversion rate. Currently, most researchers are committed to improving the reactor, hoping to solve the over-temperature problem by improving the heat transfer efficiency of the reactor itself; others are reducing the inlet carbon monoxide concentration by circulating to control the reaction exothermic rate, but this process requires cyclic power consumption. The present application takes all-round and full-process considerations from both the process and the entire shift equipment.

[0043] Based on this, the embodiment of the present application provides a carbon monoxide sulfur-free isothermal shift process, comprising the following steps:

[0044] S1, adjusting the water-gas ratio of the raw gas containing carbon monoxide to 0.1-0.4, and then performing a first-stage sulfur-free isothermal shift to obtain a first-stage shifted gas;

[0045] S2, after adjusting the water-gas ratio of the primary conversion gas to 0.2-0.8, performing a secondary sulfur-free isothermal conversion to obtain a secondary conversion gas.

[0046] The process of the present application adopts a two-stage sulfur-free isothermal transformation process to control the temperature in stages. In the first-stage sulfur-free isothermal transformation process, a high carbon monoxide content combined with a low water-gas ratio is used to reduce the reaction rate and control the transformation depth. The heat load is reduced by reducing the transformation depth to ensure that the reaction heat can be removed in time during the first-stage sulfur-free isothermal transformation process, so that the hotspot temperature and the outlet temperature of the first-stage sulfur-free isothermal transformation reaction can be controlled below 240°C; then the water-gas ratio is increased during the second-stage sulfur-free isothermal transformation process. Since the carbon monoxide concentration has been reduced after the first-stage sulfur-free isothermal transformation, the hotspot temperature and the outlet temperature of the second-stage sulfur-free isothermal transformation reaction are controlled below 240°C by using a low carbon monoxide content combined with a high water-gas ratio. Finally, the temperature of the entire process is successfully controlled within the catalyst use temperature range, the overheating problem of the sulfur-free transformation process is solved, the service life of the catalyst is extended by more than 50%, and the carbon monoxide content (V% dry basis) at the outlet of the second-stage sulfur-free isothermal transformation is controlled within 0.5%~20%. The present application connects two stages of sulfur-free isothermal conversion processes in series, and controls the conversion depth by adjusting the water-gas ratio at each stage, thereby reducing the heat load step by step and extending the catalyst service life. The carbon monoxide conversion rate of the catalyst during the same period is much higher than that of the existing process.

[0047] As an example, the water-gas ratio of the raw gas can be adjusted to 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 and 0.4, or within a range consisting of any two of the above point values ​​as end values.

[0048] As an example, the water-gas ratio of the first-stage conversion gas can be adjusted to 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75 and 0.8, or it can be within the range consisting of any two of the above point values ​​as end values.

[0049] In some embodiments, in S1, the water-gas ratio of the feed gas is adjusted to 0.1-0.3. At this water-gas ratio, the catalyst has a longer service life.

[0050] In some embodiments, in S2, the water-gas ratio of the primary shift gas is adjusted to 0.2-0.6. At this water-gas ratio, the catalyst has a longer service life.

[0051] In some implementations, the water-gas ratio of the raw gas is adjusted to 0.1-0.3, and the water-gas ratio of the primary conversion gas is adjusted to 0.2-0.6. Under this water-gas ratio, the heat load can be gradually reduced, the carbon monoxide conversion rate is high, the catalyst service life is long, and the service life of the catalyst is greatly extended.

[0052] In some embodiments, in S1, before adjusting the water-gas ratio, the following step is further included: adjusting the temperature of the raw gas to 160° C. to 190° C. This temperature is the catalyst activation temperature, so that the gas entering the catalyst bed reacts mildly, avoiding entering the catalyst bed at the optimal temperature, resulting in intense reaction and excessively high hot spot temperature.

[0053] In some embodiments, the inlet temperature of the primary sulfur-free isothermal shift is 160° C. to 190° C. At this temperature, the reaction in the catalyst bed of the primary shift reactor is relatively mild, and the hot spot temperature is prevented from being too high.

[0054] In some embodiments, the inlet temperature of the secondary sulfur-free isothermal shift is 160° C. to 190° C. At this temperature, the reaction in the catalyst bed of the secondary shift reactor is relatively mild, and the hot spot temperature is prevented from being too high.

[0055] In some of the embodiments, in S1, the hot spot temperature in the primary sulfur-free isothermal shift reaction is ≤240°C.

[0056] It is understood that a large number of thermocouples are arranged inside the isothermal shift reactor, and the highest temperature is identified as the hot spot temperature.

[0057] Furthermore, the hot spot temperature in the primary sulfur-free isothermal shift reaction is 200°C to 240°C.

[0058] The hot spot temperature is controlled below 240°C, so that the temperature is maintained within the operating temperature range of the first-level sulfur-free isothermal shift catalyst, avoiding overheating and temperature runaway that lead to catalyst sintering and affect the catalyst service life.

[0059] In some of the embodiments, in S2, the hot spot temperature in the secondary sulfur-free isothermal shift reaction is ≤240°C.

[0060] Furthermore, the hot spot temperature in the secondary sulfur-free isothermal shift reaction is 200°C to 240°C.

[0061] The hot spot temperature is controlled below 240°C and maintained within the operating temperature range of the secondary sulfur-free isothermal shift catalyst, avoiding overheating and temperature runaway that may lead to catalyst sintering and affect the catalyst service life.

[0062] In some embodiments, the carbon monoxide dry volume content of the feed gas is greater than 60%, preferably 60% to 80%.

[0063] In some embodiments, the sulfur content of the feed gas is less than 0.1 pppmv. pppmv is parts per million by volume.

[0064] In some embodiments, the pressure of the raw gas is 0.5-3.5 MPaG. MpaG refers to the gauge pressure unit megapascals. The pressure of the raw gas is preferably 0.8-2.0 MPaG.

[0065] In some of the embodiments, the feed gas is sulfur-free high carbon monoxide tail gas.

[0066] Furthermore, the raw gas is desulfurized tail gas with a high carbon monoxide content.

[0067] Furthermore, the raw gas is the tail gas of calcium carbide furnace, tail gas of ore-fired furnace or tail gas of silicon manganese furnace from the fine desulfurization section.

[0068] In some of the embodiments, a catalyst that is not tolerant to sulfur is used in both the primary sulfur-free isothermal shift and the secondary sulfur-free isothermal shift.

[0069] In some of the embodiments, a copper-based shift catalyst is used in the primary sulfur-free isothermal shift reaction.

[0070] In some of the embodiments, a copper-based shift catalyst is used in the secondary sulfur-free isothermal shift reaction.

[0071] In some of the embodiments, copper-based shift catalysts are used in both the primary sulfur-free isothermal shift reaction and the secondary sulfur-free isothermal shift reaction.

[0072] Furthermore, copper-zinc-based shift catalysts are used in both the primary sulfur-free isothermal shift reaction and the secondary sulfur-free isothermal shift reaction.

[0073] Furthermore, the copper-zinc conversion catalyst is Three-way catalyst.

[0074] In some of the embodiments, in S1, the dry volume content of carbon monoxide in the primary conversion gas is 25% to 45%.

[0075] In some embodiments, in S1, the temperature of the primary shift gas is ≤ 240°C, preferably 200°C to 240°C.

[0076] In some of the embodiments, in S2, the dry volume content of carbon monoxide in the secondary conversion gas is 0.5% to 15%.

[0077] In some embodiments, in S2, the temperature of the secondary shifted gas is ≤ 240°C, preferably 200°C to 240°C.

[0078] In some of the embodiments, in S1, the primary sulfur-free isothermal shift reaction also produces a low-pressure saturated steam by-product of 0.6 MPaG to 2.0 MPaG.

[0079] In some of the embodiments, in S2, the secondary sulfur-free isothermal shift reaction also produces a low-pressure saturated steam by-product of 0.6 MPaG to 2.0 MPaG.

[0080] See also Figure 1 According to the second aspect of the present application, a carbon monoxide sulfur-free isothermal conversion device is provided, comprising a primary water-gas ratio adjustment device 2, a primary sulfur-free isothermal conversion device 4, a secondary water-gas ratio adjustment device 5, and a secondary sulfur-free isothermal conversion device 6, wherein the gas outlet of the primary water-gas ratio adjustment device 2 is connected to the gas inlet of the primary sulfur-free isothermal conversion device 4, the gas outlet of the primary sulfur-free isothermal conversion device 4 is connected to the gas inlet of the secondary water-gas ratio adjustment device 5, and the gas outlet of the secondary water-gas ratio adjustment device 5 is connected to the gas inlet of the secondary sulfur-free isothermal conversion device 6.

[0081] The above-mentioned equipment adopts a two-stage series connection of a primary sulfur-free isothermal conversion device and a secondary sulfur-free isothermal conversion device, and at the same time adjusts the water-gas ratio of the inlet of the primary sulfur-free isothermal conversion device through a primary water-gas ratio adjustment device to reduce the reaction rate, so as to ensure that the reaction heat can be removed in time during the primary sulfur-free isothermal conversion process, so that the hotspot temperature and the outlet temperature of the primary sulfur-free isothermal conversion reaction can be controlled below 240°C; the water-gas ratio of the inlet of the secondary sulfur-free isothermal conversion device is adjusted through a secondary water-gas ratio adjustment device, and the hotspot temperature and the outlet temperature of the secondary sulfur-free isothermal conversion reaction can be controlled below 240°C by using a low load and high water-gas ratio; finally, the whole process temperature is successfully controlled within the catalyst use temperature range, the over-temperature problem of the sulfur-free conversion process is solved, and the service life of the catalyst is extended by more than 50%.

[0082] In some of the embodiments, the primary sulfur-free isothermal conversion device is an isothermal conversion furnace.

[0083] In some of the embodiments, the secondary sulfur-free isothermal conversion device is an isothermal conversion furnace.

[0084] In some of the embodiments, the primary water-gas ratio adjustment device is a humidifier.

[0085] In some of the embodiments, the secondary water-gas ratio adjustment device is a humidifier.

[0086] See also Figure 1 In some embodiments, the apparatus further comprises a feed heat exchange device 1 , and a gas outlet of the feed heat exchange device 1 is connected to a gas inlet of the first-level water-gas ratio adjustment device 2 .

[0087] In some embodiments, the feed heat exchange device is a heat exchanger.

[0088] In some of the embodiments, a purification device 3 is provided between the first-stage water-gas ratio adjustment device and the first-stage sulfur-free isothermal conversion device.

[0089] In some embodiments, the purification device 3 is a purification tank.

[0090] See also Figure 1 In some of the embodiments, the primary sulfur-free isothermal conversion device 4 is provided with a primary heat transfer device 4.1.

[0091] In some embodiments, the primary heat transfer device is a primary steam drum.

[0092] It is understood that the basis for achieving natural circulation of water and water vapor between the isothermal conversion device and the steam drum is the thermal siphon principle, that is, the use of the gravity difference of the fluid between the downcomer and the riser. After the saturated water enters the reactor heat exchange tube through the downcomer to absorb the heat released by the reaction, a part of the water becomes saturated steam. After the liquid phase boils and becomes a vapor-liquid mixture, its density is greatly reduced. The saturated steam moves upward and breaks through the liquid surface to enter the steam drum. The saturated steam entrained with liquid droplets undergoes vapor-liquid separation in the steam drum, and the generated saturated steam is discharged from the top of the steam drum as saturated steam. The gravity difference of the fluid between the downcomer and the riser is used as the driving force for natural circulation to overcome the pressure drop of the entire circulation loop, thereby realizing the natural circulation of steam drum heat exchange.

[0093] See also Figure 1 In some of the embodiments, the secondary sulfur-free isothermal conversion device 6 is provided with a secondary heat transfer device 6.1.

[0094] In some embodiments, the secondary heat transfer device is a secondary steam drum.

[0095] In some of the embodiments, the first-stage sulfur-free isothermal conversion device and / or the second-stage sulfur-free isothermal conversion device has a built-in copper-based conversion catalyst bed.

[0096] Furthermore, the copper-based shift catalyst is Three-way catalyst.

[0097] See also Figure 1In some embodiments, the gas outlet of the purification device 3 is respectively connected to the gas inlet of the first-level sulfur-free isothermal conversion device 4 and the gas inlet of the second-level water-gas ratio adjustment device 6, and a valve 7 is provided on the pipeline between the purification device 3 and the second-level water-gas ratio adjustment device 5. The first-level sulfur-free isothermal conversion device 4 and the second-level sulfur-free isothermal conversion device 6 are connected in parallel. When the equipment works normally, the valve 7 is opened, and the raw gas from the purification device 3 can only enter the first-level sulfur-free isothermal conversion device 4; when the first-level sulfur-free isothermal conversion device 4 needs to be repaired, the valve 7 is closed, and the raw gas from the purification device 3 can directly enter the second-level sulfur-free isothermal conversion device 6 for conversion. At this time, it is necessary to reduce the load to leave room for maintenance of the equipment.

[0098] It can be understood that the above-mentioned carbon monoxide sulfur-free isothermal shift process of the present application can be carried out by means of this equipment.

[0099] The following are specific examples (the sulfur-free isothermal conversion furnace of each example and comparative example is built with a catalyst of the same service life).

[0100] Example 1

[0101] Use as Figure 1 The carbon monoxide sulfur-free isothermal conversion equipment shown in the figure uses the tail gas of the calcium carbide furnace from the fine desulfurization section as the raw gas. The raw gas pressure is 2.0MPaG and the carbon monoxide content is 70% (V% dry basis). After being heated to 180°C by the feed heat exchanger, it enters the first humidifier to add steam and boiler water to adjust the water-gas ratio to 0.2, and then enters the purification tank or desulfurization and dechlorination tower to remove sulfur and chlorine in the tail gas, and then enters the first sulfur-free isothermal conversion furnace for the first sulfur-free isothermal conversion. The first sulfur-free isothermal conversion furnace is built-in The catalyst bed has a hot spot temperature of 230°C, an outlet temperature of 200°C, an outlet carbon monoxide content of 40% (V% dry basis), and the first-stage steam drum of the first-stage sulfur-free isothermal conversion furnace produces 0.8MPG low-pressure saturated steam as a by-product.

[0102] The first-stage conversion gas from the first-stage sulfur-free isothermal conversion furnace enters the second humidifier to add steam and boiler water to adjust the water-gas ratio to 0.3, and then enters the second-stage sulfur-free isothermal conversion furnace for the second-stage sulfur-free isothermal conversion. The second-stage sulfur-free isothermal conversion furnace is built-in The catalyst bed has a hot spot temperature of 215°C, an outlet temperature of 190°C, an outlet carbon monoxide content of 10% (V% dry basis), and the steam drum of the secondary isothermal conversion furnace produces 0.8MPaG low-pressure saturated steam as a by-product.

[0103] The hot gas after the reaction in the secondary sulfur-free isothermal conversion furnace preheats the raw gas, and then passes through the boiler feed water preheater, desalted water preheater, and conversion water cooler to cool down to 40°C, and then enters the water separator to go to the next process.

[0104] Example 2

[0105] Example 2 is basically the same as Example 1, except that the tail gas from the calcium carbide furnace enters the first humidifier 2 to add steam and boiler water to adjust the water-gas ratio to 0.3.

[0106] Example 3

[0107] Example 3 is basically the same as Example 1, except that the tail gas from the calcium carbide furnace enters the first humidifier 2 to add steam and boiler water to adjust the water-gas ratio to 0.1.

[0108] Example 4

[0109] Example 3 is basically the same as Example 1, except that the tail gas from the calcium carbide furnace enters the first humidifier 2 to add steam and boiler water to adjust the water-gas ratio to 0.4.

[0110] Example 5

[0111] Embodiment 5 is basically the same as Embodiment 1, except that the first-stage conversion gas enters the second humidifier 5 to add steam and boiler water to adjust the water-gas ratio to 0.6.

[0112] Example 6

[0113] Example 6 is basically the same as Example 1, except that the first-stage conversion gas enters the second humidifier 5 to add steam and boiler water to adjust the water-gas ratio to 0.2.

[0114] Example 7

[0115] Example 7 is basically the same as Example 1, except that the first-stage conversion gas enters the second humidifier 5 to add steam and boiler water to adjust the water-gas ratio to 0.8.

[0116] Example 8

[0117] Example 8 is basically the same as Example 1, except that the tail gas from the calcium carbide furnace is heated to 160°C via the feed heat exchanger 1.

[0118] Example 9

[0119] Example 9 is basically the same as Example 1, except that the tail gas from the calcium carbide furnace is heated to 190°C via the feed heat exchanger 1.

[0120] Comparative Example 1

[0121] Comparative Example 1 is substantially the same as Example 1, except that the secondary sulfur-free isothermal transformation is omitted.

[0122] Comparative Example 2

[0123] Comparative Example 2 is basically the same as Example 1, except that the tail gas from the calcium carbide furnace enters the first humidifier 2 to add steam and boiler water to adjust the water-gas ratio to 0.6.

[0124] Comparative Example 3

[0125] Comparative Example 3 is basically the same as Example 1, except that the tail gas from the calcium carbide furnace enters the second humidifier 2 to add steam and boiler water to adjust the water-gas ratio to 0.1.

[0126] Examples 1 to 10 and comparative examples 1 to 3 were tested for hot spot temperature, outlet temperature and CO dry volume fraction at the outlet of the secondary sulfur-free isothermal conversion furnace (the CO volume fraction was measured based on the dry composition after deducting moisture). The test results are shown in Table 1 below.

[0127] Table 1

[0128]

[0129] As can be seen from Table 1 above, Examples 1 to 10 adopt the process of the present application, and reduce the heat load in stages through a two-stage sulfur-free isothermal conversion process, and control the hot spot temperature and the outlet temperature below 240°C step by step, thereby avoiding overheating and extending the service life of the catalyst. In addition, the outlet CO content is 0.5% to 20%, achieving a higher CO conversion rate.

[0130] While the one-stage sulfur-free isothermal conversion process of Comparative Example 1 controls the hotspot temperature at 230°C, the CO content at the outlet of the second-stage sulfur-free isothermal conversion is as high as 42.7%, and the CO conversion rate is extremely low, which has no industrial application value.

[0131] Although Comparative Example 2 adopts a two-stage sulfur-free isothermal conversion process, the water-gas ratio of the first-stage sulfur-free isothermal conversion is too high, the hot spot temperature is as high as 285°C, and overheating occurs, which in turn affects the catalyst life.

[0132] Although Comparative Example 3 adopts a two-stage sulfur-free isothermal conversion process and the hot spot temperature is controlled within 230°C, the outlet CO content is as high as 27.3%, the total CO conversion rate is low, and it has no industrial application value.

[0133] In addition, by comparing the various embodiments, it can be seen that a water-gas ratio of 0.1 to 0.3 is used in the first-stage sulfur-free isothermal transformation process, and a water-gas ratio of 0.2 to 0.6 is used in the second-stage sulfur-free isothermal transformation process, the hot spot temperature is lower, and thus the catalyst service life is longer.

[0134] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0135] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A carbon monoxide sulfur-free isothermal shift process, characterized in that: The following steps are involved: S1, adjusting the water-gas ratio of the raw gas containing carbon monoxide to 0.1-0.4, and then performing a first-stage sulfur-free isothermal shift to obtain a first-stage shifted gas; S2, after adjusting the water-gas ratio of the primary conversion gas to 0.2-0.8, performing a secondary sulfur-free isothermal conversion to obtain a secondary conversion gas.

2. The carbon monoxide sulfur-free isothermal shift process according to claim 1, characterized in that: In S1, the water-gas ratio of the raw gas is adjusted to 0.1-0.

3.

3. The sulfur-free isothermal shift process of carbon monoxide according to claim 1, characterized in that: In S2, the water-gas ratio of the primary conversion gas is adjusted to 0.2-0.

6.

4. The carbon monoxide sulfur-free isothermal shift process according to claim 1, characterized in that: In the S1, before adjusting the water-gas ratio, the following step is also included: adjusting the temperature of the raw gas to 160°C-190°C.

5. The carbon monoxide sulfur-free isothermal shift process according to any one of claims 1 to 4, characterized in that: In S1, the hot spot temperature in the first-stage sulfur-free isothermal shift reaction is ≤240°C.

6. The sulfur-free isothermal conversion process for carbon monoxide according to any one of claims 1 to 4, characterized in that: In S2, the hot spot temperature in the secondary sulfur-free isothermal shift reaction is ≤240°C.

7. The carbon monoxide sulfur-free isothermal shift process according to any one of claims 1 to 4, characterized in that: The raw gas meets at least one of the following conditions: (1) The carbon monoxide content of the raw gas on a dry basis is greater than 60% by volume; (2) The sulfur content of the raw gas is less than 0.1 pppmv; (3) The pressure of the raw gas is 0.5MpaG ~3.5MpaG.

8. The carbon monoxide sulfur-free isothermal shift process according to any one of claims 1 to 4, characterized in that: A copper-based shift catalyst is used in the primary sulfur-free isothermal shift reaction and / or the secondary sulfur-free isothermal shift reaction.

9. The carbon monoxide sulfur-free isothermal shift process according to any one of claims 1 to 4, characterized in that: The raw gas is desulfurized tail gas with high carbon monoxide content.

10. The carbon monoxide sulfur-free isothermal shift process according to any one of claims 1 to 4, characterized in that: In S1, the dry volume content of carbon monoxide in the primary conversion gas is 25% to 45%.

11. The carbon monoxide sulfur-free isothermal shift process according to any one of claims 1 to 4, characterized in that: In S1, the temperature of the primary conversion gas is ≤ 240°C.

12. The carbon monoxide sulfur-free isothermal shift process according to any one of claims 1 to 4, characterized in that: In S2, the dry volume content of carbon monoxide in the secondary conversion gas is 0.5% to 15%.

13. The carbon monoxide sulfur-free isothermal shift process according to any one of claims 1 to 4, characterized in that: In S2, the temperature of the secondary conversion gas is ≤240°C.

14. The carbon monoxide sulfur-free isothermal shift process according to any one of claims 1 to 4, characterized in that: In S1, the primary sulfur-free isothermal shift reaction also produces a low-pressure saturated steam by-product of 0.6 MPaG to 2.0 MPaG.

15. The sulfur-free isothermal shift process for carbon monoxide according to any one of claims 1 to 4, characterized in that: In S2, the secondary sulfur-free isothermal shift reaction also produces a low-pressure saturated steam by-product of 0.6 MPaG to 2.0 MPaG.

16. A sulfur-free isothermal conversion device for carbon monoxide, characterized in that: It comprises a primary water-gas ratio adjusting device, a primary sulfur-free isothermal conversion device, a secondary water-gas ratio adjusting device and a secondary sulfur-free isothermal conversion device, wherein the gas outlet of the primary water-gas ratio adjusting device is connected to the gas inlet of the primary sulfur-free isothermal conversion device, the gas outlet of the primary sulfur-free isothermal conversion device is connected to the gas inlet of the secondary water-gas ratio adjusting device, and the gas outlet of the secondary water-gas ratio adjusting device is connected to the gas inlet of the secondary sulfur-free isothermal conversion device.

17. The sulfur-free isothermal conversion device for carbon monoxide according to claim 16, characterized in that: The equipment also includes a feed heat exchange device, and the gas outlet of the feed heat exchange device is connected to the gas inlet of the first-level water-gas ratio adjustment device.

18. The sulfur-free isothermal conversion device for carbon monoxide according to claim 16 or 17, characterized in that: A purification device is provided between the first-stage water-gas ratio adjustment device and the first-stage sulfur-free isothermal conversion device.

19. The sulfur-free isothermal conversion device for carbon monoxide according to claim 16 or 17, characterized in that: The first-stage sulfur-free isothermal conversion device is provided with a first-stage heat transfer device.

20. The sulfur-free isothermal conversion device for carbon monoxide according to claim 16 or 17, characterized in that: The secondary sulfur-free isothermal conversion device is provided with a secondary heat transfer device.

21. The sulfur-free isothermal conversion device for carbon monoxide according to claim 16 or 17, characterized in that: The first-stage sulfur-free isothermal conversion device and / or the second-stage sulfur-free isothermal conversion device has a built-in copper-based conversion catalyst bed.

22. The carbon monoxide sulfur-free isothermal conversion device according to claim 18, characterized in that: The gas outlet of the purification device is respectively connected to the gas inlet of the first-level sulfur-free isothermal conversion device and the gas inlet of the second-level water-gas ratio adjustment device, and a valve is provided on the pipeline between the purification device and the second-level water-gas ratio adjustment device.

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