WO2016119224A1

WO2016119224A1 - Isothermal and low temperature shift converter and shift conversion process thereof

Info

Publication number: WO2016119224A1
Application number: PCT/CN2015/071962
Authority: WO
Inventors: 谢定中
Original assignee: 湖南安淳高新技术有限公司
Priority date: 2015-01-30
Filing date: 2015-01-30
Publication date: 2016-08-04

Abstract

Disclosed are an isothermal and low temperature shift converter and a shift conversion process. The shift conversion process is optimized to design a reaction operating line by way of a T-X graph: i.e. first a CO isothermal conversion of 90% to 93% in the range of 260ºC to 310ºC, and then a isothermal conversion of 97% to 99% in the range of 190ºC to 220ºC. The shift converter comprises two isothermal reaction rings with different temperatures, corresponding to two water vapour cycle systems; the water pipe in the inner ring is a suspended "U"-shaped tube welded to the tube plate or a new-type double pipe; the outer ring is a suspended "U"-shaped tube welded to the ring tube. The catalyst beds in the inner and outer rings are continuous radial beds; the inner ring is a main reaction bed and the outer ring is a terminal reaction bed. In the operation of the present invention, the bed temperatures of the catalyst bed at the beginning and at the end are controlled only by controlling the drum pressure, which is simple and easy; a low temperature is advantageous for the chemical balance, and requires less catalyst than a high temperature with a high conversion.

Description

Isothermal low temperature conversion furnace and conversion process

Technical field

The invention relates to a process and a reactor for converting CO and steam into CO ₂ and H ₂ at a constant constant temperature, and is applied to deep conversion of gas with high CO content into H ₂ , and further as synthetic ammonia, methanol, acetic acid, Ethylene glycol and other products that require hydrogen as a raw material.

Background technique

Gas, natural gas conversion gas, coke oven gas conversion gas, calcium carbide furnace tail gas, blast furnace gas, converter gas, etc. These gases all contain a large amount of CO, for example, the CO content in the calcium carbide tail gas is about 80%, and the powder gas flow gasifier gas The CO content is ～68% (different depending on the coal gasification method), the CO content of the converter gas is 50%～58; the CO can be converted into a useful H ₂ , and the converted reaction formula is:

The shift reaction is an exothermic reversible reaction, and there must be a catalyst and an excess of H ₂ O (water vapor) in a reactive excess to allow the reaction to proceed in the H ₂ direction.

The shift catalyst is mainly composed of iron, and has several components such as cobalt and molybdenum. The shift catalyst containing cobalt and molybdenum has an active component of MoS ₂ . The shift catalyst is used at a temperature ranging from 200 ° C to 470 ° C. When the catalyst water-to-gas ratio (the ratio of the added steam to the reaction gas) is high, a reverse sulfidation reaction occurs:

The reverse sulfidation reaction deactivates the catalyst. When the water vapor ratio is low and the temperature is high (>400 ° C), a strong exothermic reaction of methanation occurs:

3H ₂ +CO=CH ₄ +H ₂ O

The methanation reaction does not convert to hydrogen, but also consumes hydrogen, which produces useless CH ₄ , which increases the trouble of subsequent processing, and causes the original temperature of the catalyst to rise and burn out the catalyst.

The water-gas ratio is high, that is, more water vapor is added, the material consumption is increased, and at the same time, the unreacted excess water vapor is increased, and the recovery steam device is increased. At the same time, different gas production methods, the CO content is different, for example: air-steam coal gasification gas CO content is about 30%, oxygen-steam coal slurry gasification gas CO content is about 45%, oxygen-steam The CO content in dry coal gasification gas is about 60% to 68%. The CO in the gas should be converted to H ₂ by the above-mentioned shift reaction. If the product after the gas conversion is methanol, the CO in the shift gas is retained by 18% to 20%; if the product is synthetic ammonia or H ₂ , the CO in the shift gas can only be changed. Retain 0.3% to 0.4%. If the product after the gas conversion is synthetic ammonia, it is purified and purified by methanolylization, and the shift gas CO is retained by 1% to 3%.

The product is two varieties of synthetic ammonia and methanol (diol), and the CO in the shift gas is retained at 3% to 10%.

It is known from the reaction formula that the CO conversion is an exothermic reaction, and the released heat causes the reaction gas to heat up, and the catalyst is simultaneously reacted at this temperature. 1% CO (dry basis) per reaction, temperature rise 5 ° C ~ 6 ° C; the higher the CO content in the gas, and the lower the CO content of the shift gas after the reaction, that is, the more CO changes, the higher the temperature rise.

For example: CO 65% (mol, dry basis) in gas, water-to-gas ratio R = 1.1, converted CO is 13% (mol, dry basis), according to:

CO+H ₂ O=CO ₂ +H ₂ +Q

65 115 4.3 23.7

13 63 56.3 75.7

Reaction heat after reaction: 9590 cal/mol;

Release heat: 52 × 9590 = 498680 Kcal / h;

Specific heat capacity Cp: 9.01kcal / kmol. ° C;

After the reaction material: 208kmol / h;

498680=208×9.01×△t △t=266.1°C

If the temperature before the reaction is 245 ° C, the temperature after the reaction is: 266.1 + 245 = 511.1 ° C.

This temperature is higher than the maximum temperature at which the catalyst is used, which seriously affects the activity of the catalyst. How to control the temperature of the reaction process so as not to exceed the maximum allowable temperature of the catalyst, and at the same time control the water-gas ratio to reduce the addition of water vapor, and not to produce a methanation reaction after the steam is reduced.

If the product is synthetic ammonia or H2, the CO in the shift gas can only be retained by 0.3% to 0.4%. The conversion is a reversible exothermic reaction with the help of a catalyst. Temperature is the most sensitive process index for such reactions: in terms of chemical equilibrium, the temperature is high, the reaction driving force is small, and the reaction is unfavorable, and the reaction should be carried out at a low temperature; In terms of temperature, the higher the temperature, the greater the energy given to the reaction, which is beneficial to speed up the reaction.

In the active temperature range of the catalyst, there is theoretically a temperature-to-change ratio (X-T) curve, see Figure 1. Figure 1 contains:

Balanced temperature curve: The curve with the highest conversion rate and the reaction speed equal to zero, that is, the actual operation cannot fall on the equilibrium temperature curve.

The most suitable temperature curve: the curve with the highest reaction speed, the change trend is similar to and close to the equilibrium temperature curve.

The operation curve is the actual operation line of the design. The operation line indicates that the gas with a certain steam-to-gas ratio is preheated to the initial reaction temperature of the catalyst, and the first transformation reaction is carried out. Part of the CO conversion, the CO in the gas is reduced to a certain extent, and the temperature rises. High (does not exceed the maximum temperature allowed by the catalyst), the reaction gas is cooled, the temperature is lowered (slightly higher than the lowest temperature allowed by the catalyst, the steam is not condensed, the catalyst activity is high); the second reaction is carried out, the CO is lowered again, and the temperature is increased. High (same as before, no more than the maximum temperature allowed by the catalyst), and then cooled (cooling temperature as before); then the third transformation reaction To the final required CO content.

There are three ways to cool down: 1 using cold gas directly into the high temperature reaction gas; 2 indirect cooling, that is, placing a heat exchanger outside the reactor (such as a tube-and-tube heat exchanger), and reacting the hot gas to one side (such as inside the tube) The unreacted cold gas goes to the other side (such as outside the tube); 3 is directly sprayed into the hot reaction gas with condensed water to achieve the purpose of cooling. There are water pipes in the 4 beds, and the water indirectly absorbs the heat and steam. There is an unreacted cold gas indirect heat exchange cold pipe in the 5 bed layer, and the unreacted cold gas is heated to the reaction temperature by the reaction heat.

The following two typical two types of conversion devices are described below.

The first is a typical multi-furnace adiabatic transformation process, as shown in Figure 2. The process of synthesizing ammonia conversion system is carried out from high concentration CO. The gas containing 65% of CO is separated by water by steam-water separator E-1, and then preheated to 245 °C by preheater E-2; the gas is connected in parallel to the detoxification tank E-3. And pre-change furnace E-4, after pre-change reaction, CO decreased to 59.1% (conversion rate 3.59%), the temperature rose to 275 ° C; after heating the crude gas by E-2, the superheated steam was added, and the gas-vapor ratio reached 1.1. , entering the first converter E-5 reaction, CO decreased to 21% (conversion rate 55.94%), the temperature rose to 470 ° C, divided into three streams into the methanation gas preheater E-6, steam superheater E- 7, #1 waste pot E-8, and then enter the quenching humidifier E-9, humidified by the process condensate, the reaction gas temperature dropped to 232 ° C, into the second converter E-10, CO reduced to 3% (conversion rate 92.61%), the temperature rises to 324 ° C, enter #2 waste pot E-11; the reaction gas temperature drops to 215 ° C, enters the third converter E-12, the temperature rises to 228.3 ° C, CO drops to 0.4% (Conversion rate 98.00%), enter #3 waste pot E-13, the reaction gas temperature drops to 160 ° C, low pressure steam is produced, the shift gas is cooled by the water cooler E-14 and separated by the separator E-15 to go downstream.

The second process is shown in the adiabatic internal (water) cold flow chart 3.

After preheating to about 220 ° C ~ 230 ° C gas enters the inner and outer annulus of the primary conversion furnace 50, radially through the catalyst layer, adiabatic reaction, the temperature rises to 400 ° C ~ 450 ° C, and then traverses the double loop single tube bundle 51 The inner cooling coil of the water-cooled tube reacts, and the reaction is vaporized by the circulating water buried in the water pipe in the catalyst, and the temperature of the catalyst bed is gradually lowered until about 270 ° C, and the CO is reduced to 3% to 5%. The humidifier 52 is cooled, the temperature is lowered to 232 ° C, and then the unvaporized water mist is separated by the separator 53 and enters the adiabatic terminal furnace 54 to be adiabatic, the hot spot temperature is 256 ° C, and then the inner cooling reaction is cooled, and the outlet temperature is 200 ° C. The CO drops to a temperature of 0.4% to 0.6%.

The first typical conversion process mentioned above has four conversion furnaces, and each of the conversion furnaces is connected with a cooling heat exchanger; the number of equipments is large, the flow is long, and the floor space is large; the first conversion furnace is particularly easy to overheat.

The second transformation process has the following disadvantages:

1 The first-order transformation adopts the traditional adiabatic internal cooling reactor. The hot spot temperature reaches 440 °C, the reaction point is far away from the equilibrium line, the reaction driving force is large and the reaction temperature is high. When the CO content of the gas to be reacted is high and the water-gas ratio is large, the reaction is special. Advantageously, this point is easy to over-temperature and fly, which easily leads to catalyst aging failure.

2 The process includes at least five equipments: water phase change steam, internal transfer furnace with tube bundle heat exchanger, corresponding water vapor circulation system, and a terminal shift furnace; there is a spray water temperature increase between the two furnaces. The humidifier is used to lower the gas temperature and ensure that the terminal furnace reacts at a lower temperature. An additional steam separator is added to prevent the vaporized moisture from being brought into the terminal furnace to damage the catalyst.

Since the conversion rate of a section of furnace is limited, the conversion rate is <90%, and the system exit CO ≤ 0.4% to 0.6%, the spray water is required to cool down, and the terminal furnace is set to a thermally adiabatic internal cooling complex mode.

The first and second stage converters are all set in adiabatic internal cooling mode. The multi-ring single tube form is used. The whole casing beam is buried in the catalyst. The two ends of the tube are bent and welded to the ring tube. The bending point is close to the welding point, and the bending stress is welded. Residual application of the addition, where the temperature is high, it is easy to break here.

4 The humidifier is exposed to water.

5 two insulated internal cooling converters, plus the humidifier spraying water in the middle to cool and humidify, there must be at least three temperature control points in the operation, and the first and second-order transformation hot spots are over-temperature and temperature hazard, and regulation High difficulty.

6 because the secondary transformation process has hot spots. The first-order converter furnace catalyst reaches the middle and late stages faster, the outlet CO content increases, the secondary transformation load increases, the hot spot rises, the system outlet temperature rises, the equilibrium temperature distance decreases, the conversion rate decreases, and the shift gas CO increases. The secondary transformation does not play a role in the system's CO output.

Summary of the invention

The invention aims to provide an isothermal low-temperature reforming furnace and a conversion process, and the conversion furnace and the conversion process are balanced on the TX map (see FIG. 4) according to the working condition of the gas to be changed and the required conversion rate. The curve design optimizes the low temperature isothermal depth CO conversion operation curve, thereby deriving the process: the gas is preheated to a certain temperature, enters the catalyst bed, CO immediately undergoes micro-adiabatic reaction, and the temperature rises slightly; CO shift reaction releases heat = water pipe water absorption heat Vaporization, isothermal reaction process, reaching a higher conversion rate (for example, about 94%); water pipe water absorption heat>CO reaction release heat process, the conversion rate continues to increase, and the temperature drops until the conversion rate reaches the required end point (in the embodiment) The spot temperature was 212 ° C and the conversion rate was 98%).

In order to achieve the above object, the technical solution adopted by the present invention is:

An isothermal low temperature shifting furnace comprising an outer casing, a steam drum, a catalytic bed radial cylinder for placing a catalyst disposed in the outer casing, a centrally located central intake pipe disposed at the center of the outer casing, and a water chamber disposed at the top of the outer casing and a steam chamber; the water chamber and the steam chamber are separated by an upper tube sheet, and the steam chamber and the inner chamber of the outer shell are separated by a lower tube sheet; and the structural feature is that the upper portion of the catalytic bed is in a radial tube a gas collecting ring and a water collecting ring, wherein the water collecting ring communicates with the water outlet of the steam drum through a pipe, and the gas collecting ring communicates with the air inlet of the steam drum through a steam pipe; A plurality of U-shaped water-cooling pipes are disposed between the central air intake pipe, one end of each U-shaped water-cooling pipe is connected to the gas collecting ring, and the other end is connected with the water collecting ring; and between the U-shaped water-cooling pipe and the central air intake pipe Provided with a plurality of U-shaped tubes or double sleeves; one end of the U-shaped tube The steam chamber is in communication, and the other end is in communication with the water chamber; or the inner tube of the double sleeve is in communication with the water chamber, and the outer tube is in communication with the steam chamber; the U-shaped water-cooled tube forms a water vapor circulation outer ring The U-shaped tube or the double sleeve forms a water vapor circulation inner ring.

The following is a further improved technical solution of the present invention:

Further, the gas collection ring is located above the water collecting ring.

As a specific structural form, both ends of the U-shaped tube are fixed on the lower tube sheet, and one end thereof communicates with the water chamber through a short tube.

In order to keep the connection between the inner tube and the outer tube stable, a spiral coil is disposed between the inner tube and the outer tube of the double sleeve, and the inner tube communicates with the water chamber through a short threaded tube.

An annular gap is formed between the outer casing and the radial bed of the catalytic bed, the annulus being in communication with a reaction gas outlet disposed at the bottom of the outer casing; the bottom of the central intake pipe is in communication with the inlet of the unreacted gas.

The lengths of the two branch pipes of the U-shaped water-cooled pipe and the U-shaped pipe are not equal, and the shorter branch pipe is disposed on one side of the central intake pipe.

The outer casing, the water chamber and the steam chamber are in the form of a wine bottle, and the water chamber and the steam chamber are located at the bottle neck position of the wine bottle.

The upper tube sheet is thinner than the lower tube sheet; the lower surface of the upper tube sheet is provided with a support ring, and a flexible graphite sealing ring is disposed between the lower surface of the upper tube sheet and the support ring, and a surface of the upper tube plate is fixedly mounted The pressure ring is provided with a flexible graphite sealing ring between the pressure ring and the upper surface of the upper tube.

An isothermal low-temperature transformation process is characterized in that two sets of water vapor circulation systems are arranged in an isothermal low-temperature reforming furnace, and one set of water vapor circulation systems is located inside another group, and the specific transformation process comprises the following steps:

1) preheating stage, preheating unreacted gas to a certain temperature, maintaining the CO isothermal conversion rate of 0;

2) In the constant temperature stage, the CO isothermal conversion rate is maintained in the range of 260 ° C to 310 ° C of 90% to 93%. At this time, the water in the water pipe absorbs heat and reacts to release heat, and the temperature in the catalyst bed is kept constant;

3) In the cooling stage, the isothermal conversion rate is maintained in the range of 190 ° C to 220 ° C by 97% to 99% until the operation line intersects with the optimum temperature curve, and the unreacted gas is discharged.

The invention is further described below.

The shape of the conversion furnace of the present invention is a wine bottle shape, and comprises two isothermal reaction rings of different temperatures, corresponding to two water vapor circulation systems. The inner ring water pipe is welded to the tube plate to suspend the "U" tube or the new double sleeve. The outer ring is a U-shaped tube that is welded to the ring pipe. The inner and outer ring catalytic beds are continuous radial beds. The inner ring is the main reaction bed, and the outer ring is the terminal reaction bed. Advantages of the Invention A shifting furnace can convert a crude gas having a CO content of up to 80% to 90% to 0.3% to 0.4%, with less equipment and a short process. The heat of the shift reaction is all used for by-product medium pressure and low pressure steam. The temperature difference between the reaction bed and the plane is ≤3°C and the temperature difference between the same cylinder surface is ≤10°C. There is no hot spot and no over-temperature. The furnace tube is not expanded and contracted, and the tube sheet does not warp and deform, and the tube sheet is not welded. Cracks, catalysts and shifters have long service life and are safe and reliable to use. The operation only controls the drum pressure to control the initial and final bed temperatures of the catalyst bed, which is simple and easy. Low temperature is beneficial to chemical equilibrium, less than the amount of high temperature catalyst, and high conversion rate.

The reaction temperature curve of the present invention is shown in the operating curve "A" as the operating condition of the reactor, the gas is preheated to a certain temperature (for example, 260 ° C), the conversion rate is zero, and a small amount of reaction (for example, reaction) is immediately performed in the catalyst bed CO. 3%), a slight temperature rise (eg 272 ° C). Starting from the beginning of the working condition "B", the CO shift reaction releases heat, which is immediately absorbed by the water pipe, and the water in the water pipe absorbs heat> the heat is released from the reaction, and the heat of the reaction is dynamically balanced to keep the temperature of the catalyst bed constant. The line of operation rises linearly to intersect the optimum temperature curve at the "C" point (at this point in the example, the temperature is 272 ° C, the conversion rate is 94%).

From the "C" point, the water in the water pipe absorbs heat> the reaction releases heat, that is, the conversion rate continues to increase, and the temperature drops. On the graph, the operation line is the diagonal line rising to the left until the required end point conversion rate and the optimum temperature. The curves intersect at the "D" point (in this example the temperature is 212 ° C, the conversion rate is 97.95%).

The end point of the isothermal low-temperature process of the invention is ≤94%, which fully utilizes the advantages of large equilibrium temperature range and large driving force, so that all the catalysts work in a mild and efficient working condition, and are not easy to aging. Moreover, the reaction is the most difficult, the minimum speed is at the end, the remaining conversion rate is <6%, the amount of conversion is small, and the reactor structure is correspondingly simple.

The inner cavity of the "bottle" shaped cylindrical shell of the invention is divided into a main reaction ring (inner ring) and a terminal working condition reaction ring (outer ring, temperature ratio) according to the reaction temperature working condition in the radial cylinder catalyst bed of the catalytic bed. low). The upper part of the inner ring is the bottleneck "A". The upper tube plate 2 and the lower tube plate 4 are installed in the bottle neck, and the cavity between the upper tube plate and the upper end cap of the cylindrical casing is a water chamber 18, and the cavity between the upper tube plate and the lower tube plate is a steam chamber 16 .

Below the lower tube sheet 4 is the reaction gas, and above is the water vapor, the pressure difference between the two sides is large, and the lower tube sheet is thick. Both sides of the upper tube sheet 2 are water vapor systems, and the pressure difference is small. Therefore, the upper tube sheet is thin, a flexible graphite sealing ring 27-1 is disposed between the lower side of the upper tube sheet and the support ring 28, and a pressure ring 26 is disposed on the tube plate, and a flexible graphite sealing ring 27-2 is sandwiched therebetween, and the metal screw 25 is used. Pressing, the water chamber cylinder is made of a circular ring of graphite with a round metal ring and a screw to prevent water from leaking directly into the steam chamber. However, during maintenance, it can be disassembled without moving fire, as shown in Figure 7. Shown.

The inner ring is provided with a plurality of U-shaped tubes 8-2, and the two ports of the U-shaped tubes are welded to the lower tube sheets, and one of the ports has a socket-type short tube 17, which is closely matched with the U-shaped tube, and the short tube The upper end passes through the upper tube sheet and the two are sealed with a packing, as shown in FIG.

If the CO% to be changed is large (for example, into the reactor CO > 45%), the double casing of the structure of the present invention is used. As shown in FIG. 6, the casing has an inner tube 23 and an outer tube 24, which are on the inner tube 23. The 1-4-section spiral coil 24 is welded as a support between the inner and outer tubes to prevent the inner tube from vibrating during operation, and the inner tube is loaded into the outer tube by rotation to facilitate labor saving. The outer tube port is welded to the lower tube sheet, and the inner tube of the outer tube is extended from the lower tube sheet, and a short threaded tube 25 is disposed. The upper end of the short tube passes through the upper tube sheet, and the two are sealed with the packing 20. In order to check whether the welded seam 21 of the outer tube port of the upper tube sheet is leaking, it can be easily disassembled without moving.

The outer ring is provided with a plurality of U-shaped tubes 8-1, one port of which is welded to the outer (upper) collecting annular tube 5 located on the radial tube of the catalytic bed, and the other port is welded inside (the lower port is welded) The water collecting annular pipe 6 is on the water collecting pipe.

There is a long-shaped steam drum at a height of several meters above the cylinder of the "bottle". The steam drum is separated by a partition into two large and small space drums, medium pressure section 19 and steam drum low pressure. Segment 1.

When the amount of gas to be converted is large and the steam production capacity is large, the design is to set two steam drums for one big and one small.

The "bottle" shaped cylinder "B" is sleeved with the casing as a catalytic bed radial cylinder 9, and is provided with a plurality of venting orifices. The radial bed top of the catalytic bed is connected to the bottle neck A; the outer wall of the catalytic bed radial cylinder An annular gap is left between the inner wall of the cylindrical casing 11 and a central intake pipe 7 having a top end closed and a plurality of venting holes distributed in the pipe wall, and the lower end of the central intake pipe is located in the cylindrical casing. Unreacted gas inlet below the bottom.

There is a tee pipe 14 in the middle of the bottom of the cylinder body, and an intake center intake pipe 7 is inserted therein. The tee pipe has a sealing packing 13-1 to block the inlet unreacted gas and the outlet reaction gas phase string, and the bottom has a small head 13-2. There are two unloading catalyst discharge ports 12 at the bottom of the cylinder body, and two catalyst loading ports 15 are arranged at the shoulder of the cylinder body. The center of the bottle neck has a catalyst loading tube 3 which is connected to the upper and lower tubes.

The bottom of the steam drum 19 is connected to a plurality of pipes connected to the water chamber, through which the water enters the water chamber 18, and then descends to the bottom through the U-shaped 8-2, and is folded to the heat outside the absorption pipe, and the gas phase is continuously converted into steam. Next, it rises to the steam chamber 16 and rises upward through the furnace steam to the steam drum 19. In the steam drum, the steam and water are separated and the steam is taken out from the top.

The water falling from the steam drum 1 enters the water collecting ring 6, and then descends through the U-shaped tube 8-1, and the U-shaped tube descends through the bottom to the outside of the absorption tube, and the phase changes into steam, and the vapor-water mixture rises from the bottom to the set. The steam ring 5 rises through the steam tube outside the furnace until the drum 1 is reached. In the steam drum, the steam and water are separated, the steam is taken out from the top, and the water enters the water pipe from the bottom of the steam drum.

If it is a double casing, the water descending from the steam drum 1 passes through the water indoor pipe 23, from the top to the bottom, and is folded from the bottom to the top, absorbing the heat outside the pipe, continuously transforming into steam, and the steam-water mixture is discharged to the water chamber. rise.

The steam drum 19 and its water vapor circulation system and the steam drum 1 and its water vapor circulation system are two independent systems. The steam pressure of the steam drum 19 system is higher than the steam pressure of the steam drum 1 system.

A catalyst 10 is placed in the "bottle" cavity of the "bottle" shaped cylinder to assist in speeding up the reaction.

When the CO-containing gas enters the central intake pipe 7 from the bottom tee 14 of the "bottle"-shaped cylindrical casing, it passes through the catalytic bed 10 through the pores, and the reaction heat is released, and the reaction heat is absorbed by the water vapor mixture in the pipe, and the water is changed. For steam, keep the temperature inside the bed and tube constant. After the reaction, the CO is reduced to the target value, passing through the small hole of the radial tube 9 of the catalytic bed, and accumulating in the radial cylinder annulus of the catalytic wall of the cylindrical wall, from the top to the bottom of the three-way outlet of the reactor, the U-shaped tube on both sides The length of the U-shaped tube faces the center of the catalyst bed, and the water vapor flows from the top to the bottom from the top to the bottom. The short side is discharged from the bottom to the top. The short side is more vaporized than the long side, and the reaction gas is short. While flowing radially to the long side, the airflow enters the front side of the worker to flush the short side. It has a stronger heat capacity and can make the short side vaporize more.

The inner ring U-shaped tube 8-2 corresponding to the steam drum 19 and the "belly" peripheral U-shaped tube 8-1 corresponding to the steam drum 1 are two different water vapor circulation systems of water vapor pressure level, and the central system has high pressure and peripheral system. Low pressure.

Because 85%~95% CO reaction process state is far away from the equilibrium point line, the reaction driving force is large, and it can be carried out at a higher temperature. At this time, the amount of CO is much, the amount of heat is much, and the amount of catalyst is not much, but it needs to be changed. The thermal area is large. When the reaction approaches the terminal, the reaction CO needs to be small, the heat release is small, and the demand heat exchange area is small. The reaction process state is close to the equilibrium point; but the temperature is low, which is favorable for the reaction to continue, and the reaction at low temperature. A lot of catalyst is needed. As shown in Figure 8.

In the gas to be converted of the present invention, the CO can be up to 80% to 90%, and the CO after the conversion can be reduced to 0.3% to 0.4%.

The shift reaction catalyst bed of the invention is a radial bed, which is divided into two inner and outer rings, the inner ring transforms a large amount (>90%), the catalyst amount accounts for a total amount of ～50%, the unit catalyst reacts a large amount of CO, and the cooling water pipe has many ( >70%), the amount of outer ring change is small (<10%), the amount of CO per unit catalyst is small, and the number of cooling water pipes is small (<30%).

A steam drum is divided into two pressure steam drums, which respectively form two pressure water vapor cycles with the corresponding two-line water pipes.

The two ports of the inner ring cooling water pipe U-shaped water pipe 8-1 are welded to the lower tube sheet, and a short tube 18 is inserted into one port of the U-shaped tube, which is closely matched with the U-shaped tube, and the upper end of the short tube passes through the upper tube sheet. Both are sealed with a packing, as shown in Figure 5. If you want to inspect the nozzle weld on the lower tubesheet, you can remove the upper tubesheet, remove the short tube packing, and pull out the short tube. After the inspection, it can be completely reassembled without the need to apply heat.

If the CO% to be changed is very large (for example, into the reactor CO> 45%), the center distance between the left and right pipes of the U-shaped tube is large, and the density of the tube is not too large, the new structure double casing is used, and the casing has an inner tube. The outer tube is welded with one to four spiral coils on the inner tube as a support between the inner and outer tubes, and the inner tube is loaded into the outer tube by rotation, which is convenient for labor saving. The outer tube port is welded to the lower tube plate, and is inserted into the inner tube of the outer tube. After the lower tube sheet is extended, a short threaded tube is disposed, and the upper end of the short tube passes through the upper tube sheet, and the two are sealed with a packing.

If you want to inspect the nozzle weld on the lower tubesheet, you can remove the upper tubesheet, remove the short tube packing, and pull out the short tube. After the inspection, it can be completely reassembled without the need to apply heat.

The outer ring U-shaped water cooling water pipe 8-2 is welded to the water collecting ring 6, and the other pipe is welded to the collecting ring 5.

The U-shaped tube has different lengths on both sides, and the short side of the U-shaped tube faces the center of the catalyst bed. The water vapor flows from the top to the bottom of the long tube at the bottom, and the short side flows from the bottom to the top. The reaction gas from the short side to the long side Radial flow, the airflow first flushes the short side.

The shift reactor housing of the present invention is shaped like a wine bottle, and the bottle neck is a part of the water vapor circulation cooling system, that is, a water chamber and a steam chamber, and upper and lower tube sheets.

The shift reactor of the present invention has three to several charging ports, that is, two to three shoulders of the bottle-shaped casing, one center in the neck of the bottle-shaped casing, and a plurality of charging ports at different diameters thereof. . There are two to three unloading ports at the bottom of the bottle-shaped housing.

The present invention accomplishes the task of converting the raw material gas CO from 30% to 90% to 0.3% to 0.4%.

In summary, the isothermal low-temperature conversion process of the present invention optimizes the design of the reaction operation line in the TX map: first, the CO isothermal conversion rate is in the range of 260 ° C to 310 ° C, 90% to 93%, and then at 190 ° C to 220 ° C. The range of CO isothermal conversion in the range is 97% to 99%. The shape of the converter is a bottle shape, containing two isothermal reaction rings of different temperatures, corresponding to two water vapor circulation systems, wherein the inner ring water pipe is welded to the tube plate to suspend the "U" tube or the new double casing, and the outer ring is The "U" shaped tube is suspended on the ring pipe, and the inner and outer ring catalytic beds are continuous radial beds. In action, the inner ring is the main reaction bed and the outer ring is the terminal reaction bed. The invention can convert the crude gas with the CO content up to 80%-90% to 0.3%-0.4%, the equipment is small, the process is short, and the conversion reaction heat is all used for the by-product medium pressure and low pressure steam, and the reaction bed has the same plane temperature difference ≤ 3 ° C and the same cylinder surface temperature difference ≤ 10 ° C, no high temperature hot spots, not over temperature flying temperature. The furnace tube is not expanded and contracted by thermal expansion and contraction. The tube sheet will not be warped and deformed. The tube sheet will not be cracked. The catalyst and converter have a long service life and are safe and reliable. The operation only controls the initial and final bed temperature of the drum pressure control bed, which is simple and easy, and the low temperature is beneficial to the chemical balance, and the amount of the catalyst is lower than that of the high temperature catalyst, and the conversion rate is high.

Compared with the prior art, the beneficial effects of the present invention are:

(1) According to the traditional high-concentration CO depth conversion gas is first adiabatic reaction (slanting line rising to the right on the TX map) until the temperature rises to 400 ° C ~ 480 ° C, and then cooled (internal or intercooled or direct water spray cooling) Re-reaction, the activity of the catalyst is dependent on a large number of small crystal grains adsorbing the molecules to be reacted, and the smaller the crystal grains, the more favorable the reaction. However, when the temperature is high, the crystal grains will grow, the number of particles will decrease, and the activity of the catalyst will rapidly decrease. Moreover, the catalyst temperature difference is 150 ° C, and the temperature difference stress is large, and the catalyst is easily broken and powdered. The invention relates to an isothermal low-temperature conversion process and a conversion furnace, wherein the bed temperature is far <400 ° C, the catalyst reacts under mild working conditions, there is no risk of over-temperature flying temperature, the temperature difference between the catalyst bed and the plane is <3 ° C, and the temperature difference between the same cylinder surface temperature difference <10 ° C, the temperature difference stress is small, the catalyst is not easy to crack and powder. If the first year reaction temperature is 270 ° C, 5 ° C ~ 8 ° C per year, reach 400 ° C, at least 16 years can be used, if it reaches 350 ° C, at least can be used 10 years. The catalyst has high efficiency, long life and low reactor resistance.

(2) An isothermal low-temperature shifting process and a shifting furnace of the present invention, the inner ring main reaction bed, the temperature of the catalyst before and after the use of the catalyst is below 310 ° C, and the temperature is increased later, the water vapor pressure of the outer ring water and gas system is adjusted, and the reaction bed is still constant. About 200 °C, to ensure that the terminal outlet CO is 0.3% to 0.4%.

(3) According to the traditional high CO gas, it is necessary to set a terminal furnace to reduce the CO after conversion by 0.4% to 1%, and spray water to cool down before entering the terminal furnace. The present invention does not set the terminal furnace, and the furnace completes the depth conversion, and the CO is the lowest after the conversion. Can be reduced to 0.3% to 0.4%, no water spray in the middle, reducing equipment investment and floor space, eliminating the accident of catalyst damage caused by water spray.

(4) The invention relates to an isothermal low-temperature conversion process and a conversion furnace, which are carried out under constant temperature and low temperature, and have a reversible exothermic reaction and low Temperature is beneficial to the chemical equilibrium movement, achieving the same amount of catalyst, the same water-to-gas ratio, a higher conversion rate, or the same water-to-gas ratio, achieving the same conversion rate and the least amount of catalyst.

(5) A continuous reaction furnace of the present invention comprises two water vapor circulation systems having different water vapor pressure levels and reaction rings corresponding to two different temperatures (for example, 260 ° C to 310 ° C and 180 ° C to 200 ° C), the former is an isothermal reaction cycle. The latter is a lower temperature isothermal reaction ring of the terminal, and there is no separation device between the two rings, and the structure of the reaction furnace is simple.

(6) The water pipe adopts a hanging U-shaped pipe, which is simpler than the single-tube double-ring structure, has good thermal expansion and contraction performance and low investment.

(7) If the CO% to be changed is very large (for example, into the reactor CO>45%), the new structure double casing is used to weld one to four spiral coils on the inner tube, which serves as a support between the inner and outer tubes, and simultaneously rotates. The inner tube is loaded into the outer tube to facilitate labor saving.

(8) The CO reaction in the inner ring is large (96% CO is reacted in this circle), the water pipes are mostly (78% of the total), the relative volume is not much (the catalyst amount only accounts for 52% of the total), and the pressure difference between the inside and outside of the pipe is small. The tube plate structure is adopted, and the pipe is regular and compact (the number is large), the tube plate is reduced, the thickness is reduced, and the cost is reduced. The tube plate structure can be controlled by CNC automatic welding to improve the manufacturing quality.

(9) Regardless of the U-shaped pipe or the new double casing, the upper pipe plate is sealed with packing; between the upper and lower pipe plates, there are detachable short pipes that do not leak water. When it is necessary to check whether the pipe welding of the lower pipe plate is leaking, It is easy to disassemble the upper tube sheet and the short tube without the need for hot fire cutting, which is convenient for leak detection.

(10) The amount of CO in the outer ring is very small (only 4% is reacted in this circle), the water pipe is small (accounting for 23% of the total), and the relative volume of the catalyst is relatively large (only 48% of the total), but the pressure difference between the inside and outside of the pipe is large. The utility model adopts a loop structure, has large pressure bearing capacity, and has low light weight and low investment. Due to the small number of water pipes, the arrangement is relatively loose, which is convenient for manual welding and can guarantee quality.

(11) The gas flows from the central radial direction to the surrounding, the central radial ring has a small cylindrical area, the cloth is dense, and the airflow speed is fast, which is beneficial to heat transfer. The gas that enters first has high CO content, many reactions, and large heat release. Hot. The heat does not accumulate and maintains an isothermal constant temperature condition.

(12) The gas flows from the central radial direction to the surrounding, surrounded by a low temperature thermostat ring, and immediately flows into the reactor tube wall and the radial ring annulus of the catalytic bed, and the low temperature working condition is beneficial to the protection of the pressurized cylinder body, thereby improving safety. Can reduce the wall and reduce investment.

(13) The structure of the converter of the present invention is reasonable. Such as suspended water-cooled pipe, the operating conditions are mild, although the pipe plate is thick, but the same temperature at the whole plate, the plate will not be deformed, the pipe plate welding will not cause cracks due to the plate fin. The shift furnace overhaul cycle is longer than the catalyst life cycle.

(14) The process controls the bed temperature only by controlling the steam drum pressure, thereby controlling the outlet CO content and achieving safe and easy operation.

(15) The shifting furnace is provided with a plurality of feeding ports and discharging ports at different positions, and it is easier to install and discharge the catalyst.

The invention is further illustrated below in conjunction with the drawings and embodiments.

DRAWINGS

Figure 1 is a three-curve diagram of the shift reaction of the present invention;

Figure 2 is a flow chart of multi-furnace adiabatic conversion;

Figure 3 is an adiabatic internal (water) cold flow chart;

Figure 4 is a diagram showing the isothermal low temperature conversion T-X of the present invention;

Figure 5 is a schematic view showing the structure of the U-shaped water pipe of the present invention;

Figure 6 is a schematic view showing the structure of the double casing of the present invention;

Figure 7 is a schematic view showing the assembly structure of the upper tube sheet according to the present invention;

Figure 8 is a distribution diagram of the catalyst and water-cooled pipe of the present invention;

Figure 9 is a two-reaction conversion furnace (U-shaped tube) of the wine bottle shape of the present invention;

Figure 10 is a two-reaction conversion furnace (double casing + U-tube) of the wine bottle shape of the present invention.

detailed description

The conversion furnace used in the CO conversion process of the present embodiment has two CO reaction rings and two different temperature water vapor circulation cooling systems, which can continuously react to exotherm during the reaction process, continuously remove the reaction heat by water vaporization, and maintain the reaction at a low temperature. At a constant temperature. Equipment inspection is convenient.

According to the T-X diagram equilibrium temperature curve and the optimum temperature curve, the optimized operation curve shown in Fig. 4 was designed, and finally a high efficiency reactor was designed.

As shown in FIG. 4, the former coordinate value of the figure indicates the reaction temperature of the point, and the latter indicates the CO conversion rate, wherein the operation curve "A" is the reactor operating condition, and the gas is preheated to a certain temperature (for example, 260 ° C). The conversion rate is zero, and a very small amount of reaction (e.g., 3% of the reaction) is carried out immediately after entering the catalyst bed, with a slight temperature rise (e.g., 272 ° C). Starting from the beginning of the working condition "B", the CO shift reaction releases heat, which is immediately absorbed by the water pipe, and the water in the water pipe absorbs heat> the heat is released from the reaction, and the heat of the reaction is dynamically balanced to keep the temperature of the catalyst bed constant. The line of operation rises linearly to intersect the optimum temperature curve at point "C" (in this example the temperature is 272 ° C, the conversion rate is 94%).

From the "C" point, the water in the water pipe absorbs heat> the reaction releases heat, that is, the conversion rate continues to increase, and the temperature drops. On the graph, the operation line is the diagonal line rising to the left until the required end point conversion rate and the optimum temperature. The curve intersects at the "D" point. (In this example, the temperature is 212 ° C and the conversion rate is 98.50%.)

In this embodiment, an isothermal low-temperature shifting process and an operating line of a shifting furnace have the highest reaction rate, or achieve a high conversion rate, which requires a minimum amount of catalyst. Because the distance from the "A" point to the "C" point, the reaction condition balance The temperature line is very far, the reaction driving force is very large, and the recent "C" point balance temperature distance is also large (74 °C in the embodiment, in the conventional case, when the conversion rate reaches 94%, the equilibrium temperature distance is generally about 30 °C.) . And it falls on the most suitable temperature line, which is the fastest. Finally, from the "C" point to the terminal "D" point, its operating line is basically fitted to the most suitable temperature line. Therefore, the reaction speed of the reactor operating line designed in this embodiment is always the highest. According to this operation curve, the maximum amount of CO entering the reaction gas can be 80% to 90%, and the conversion end point (D) CO can be reduced to 0.3% to 0.4%.

According to the operation line design described above, the structure of the isothermal low-temperature deep CO-changing reactor is that it has an upright "bottle"-shaped cylindrical shell with upper and lower ends at both ends, and its structural feature is that The inner cavity of the "bottle" shaped cylindrical housing is divided into two inner and outer rings. The upper part of the inner ring is the bottleneck. The upper part of the bottle neck is provided with an upper tube plate and a lower tube plate, and a cavity between the upper tube plate and the upper end cap of the cylindrical casing is a water chamber, and a cavity between the upper tube plate and the lower tube plate is a steam chamber.

The inner tube lower tube plate is suspended with a plurality of U-shaped tubes, two ports are welded on the lower tube sheet, and a short tube is inserted into one port of the U-shaped tube, which is closely matched with the U-shaped tube, and the upper end of the short tube passes through the upper tube sheet. Both are sealed with a packing. The lower end of the short tube is inserted into the outer tube (tight fit), and the schematic view is shown in Fig. 5.

If the CO% content to be converted is large (for example, into the reactor CO > 45%), the double casing of the structure of this embodiment is used.

In the embodiment, the double sleeve has an inner tube and an outer tube, and one to four spiral coils are welded on the inner tube to serve as a support between the inner and outer tubes, and the inner tube is loaded into the outer tube by rotation, which is convenient for labor saving.

The outer tube port is welded to the lower tube sheet and is loaded into the inner tube of the outer tube. After the lower tube sheet is extended, a threaded short tube is connected to the inner tube. The upper end of the short tube passes through the upper tube sheet and the two are sealed with a packing. In order to check whether the weld of the outer tube port of the upper tube sheet is leaking, it is easy to disassemble without the need of fire. The schematic is shown in Figure 6.

Below the lower tube sheet is the reaction gas, the top is the water vapor, the pressure difference between the two sides is large, and the lower tube sheet is thick. Both sides of the upper tube sheet are water vapor systems, and the pressure difference is small. Therefore, the board book. The upper tube plate is designed to be sealed with a circular ring of metal and a screw on the graphite circular ring to prevent water from leaking directly into the steam chamber, but it can be disassembled during the maintenance. The schematic is shown in Figure 7.

The outer cylinder of the "bottle" shaped cylinder "stomach" is provided with a catalytic bed radial cylinder with a bottom portion and a plurality of ventilation holes at the side wall, and the radial end of the catalytic bed is the same as the bottle neck Connecting; an annular gap is left between the outer wall of the radial bed of the catalytic bed and the inner wall of the cylindrical casing; the center of the "bottle-shaped" cylindrical casing is provided with a central intake pipe with a top end closed and a plurality of ventilation holes distributed in the pipe wall, The lower end of the central intake pipe is an unreacted gas inlet located below the bottom of the cylindrical casing.

"bottle" shaped cylinder "belly" (outer ring), provided with a plurality of U-shaped tubes, one port of which is welded to the outer (upper) annular tube located on the radial tube of the catalytic bed The other port is welded to the inner (lower) annular tube.

The outer ring is required to change CO% very little, and the outer core U-shaped tube has a larger core distance than the inner ring U-shaped tube.

There is a long tubular steam drum at a height of several meters above the "bottle" shaped cylindrical casing, and the steam drum is divided into two large and small spaces by a partition.

A plurality of pipes are taken from the lower end of one end of the steam drum A to connect with the water chamber in the bottle neck of the "bottle", and a plurality of pipes are taken from the steam chamber in the bottle neck of the "bottle" to be connected to the upper middle portion of one end of the steam drum A.

From the lower end of one end of the steam drum B, several pipes are connected with the upper annular pipe around the "bottle" and "belly", and several pipes are connected from the lower tube of the "bottle" and "stomach" to the steam. The upper end of the end of the package B.

The "bottle" shaped cylinder "cavity" cavity contains a catalyst to help speed up the reaction.

When the CO-containing gas enters the central intake pipe from the bottom of the central intake pipe in the center of the "bottle" cylindrical casing, the gas is radially passed through the catalytic bed through the pores, and the reaction heat is released and absorbed by the water vapor mixture in the pipe. For steam, keep the temperature inside the bed and tube constant. After the reaction, the CO is lowered to the target value, passes through the radial tube pores of the catalyst bed, and is collected in the radial cylinder annulus of the cylindrical wall catalytic bed, and exits from the bottom of the reactor from top to bottom.

The water descending from the steam drum enters the U-shaped pipe or the double casing, absorbs the reaction heat outside the pipe, and continuously changes into steam. The steam-water mixture is first turned from the top down to the bottom through the down pipe, and then rises from the bottom to the steam drum. In the steam drum, the steam and water are separated, the steam is taken out from the top, and the water enters the water pipe from the bottom.

The central U-shaped pipe system or double casing system corresponding to the A end of the steam drum and the U-shaped pipe system corresponding to the "belly" corresponding to the B end are two different water vapor circulation systems of water vapor pressure level, and the central system has high pressure and surrounding. System pressure is low. Because 85%~95% CO reaction process state is far away from the equilibrium point line, the reaction driving force is large, and it can be carried out at a higher temperature. At this time, the amount of CO is much, the amount of heat is much, and the amount of catalyst is not much, but it needs to be changed. The thermal area is large. When the reaction approaches the terminal, the reaction CO is small, the heat release is small, and the heat exchange area is small. The reaction process state is close to the equilibrium point, but the temperature is low, which is favorable for the reaction to continue, and the reaction at low temperature. A lot of catalyst is needed. The schematic is shown in Figure 8.

An isothermal shifting furnace of two reaction rings is shown in Figs. The inner cavity of the "bottle" shaped cylindrical shell, the catalytic bed in the radial tube catalyst bed, is divided into the main reaction ring (inner ring) and the terminal working condition reaction ring according to the reaction temperature condition (outer ring, lower temperature) . The upper part of the inner ring is the bottleneck "A". The upper tube plate 2 and the lower tube plate 4 are installed in the bottle neck, and the cavity between the upper tube plate and the upper end cap of the cylindrical casing is a water chamber 18, and the cavity between the upper tube plate and the lower tube plate is a steam chamber 16 .

Below the lower tube sheet 2 is the reaction gas, and above is the water vapor, the pressure difference between the two sides is large, and the lower tube sheet is thick. Both sides of the upper tube sheet 4 are water vapor systems, and the pressure difference is small. Therefore, the upper tube board, a flexible graphite sealing ring 27-1 is disposed between the lower side of the upper tube sheet and the support ring 28, and a pressure ring 26 is disposed on the tube plate, and a flexible graphite sealing ring 27-2 is sandwiched therebetween, with metal screws 25 Pressing, the water chamber cylinder is made of a circular ring of graphite with a round metal ring and a screw to prevent water from leaking directly into the steam chamber, but it can be disassembled during the maintenance. As shown in Figure 7.

As shown in FIG. 5, the inner ring is provided with a plurality of U-shaped tubes 8-2, and the two ports of the U-shaped tubes are welded to the lower tube sheets 4, and one of the ports has a socket-type short tube 17, which is short. 17 is tightly fitted with the U-shaped tube 8-2, and in the short tube 17 and the lower tube Welds 21 are provided between the plates 4 for welding connection, and the upper ends of the short tubes 17 pass through the upper tube sheets 2, both of which are sealed with a packing 20.

If the CO% to be changed is large (for example, into the reactor CO > 45%), the double casing of the structure of this embodiment is used, as shown in FIG. The sleeve has an inner tube 23 and an outer tube 22, and the inner tube is welded with one to four spiral coils 24 as a support between the inner and outer tubes to prevent the inner tube from vibrating during operation, and the inner tube is loaded into the outer tube by rotation. Easy to save labor. The outer tube port is welded to the lower tube sheet and is loaded into the inner tube of the outer tube. After the lower tube sheet is extended, a threaded short tube 25 is disposed, and the upper end of the short tube passes through the upper tube sheet, and the two are sealed with the packing 20. In order to check whether the welded seam 21 of the outer tube port of the upper tube sheet is leaking, it can be easily disassembled without moving.

The outer ring is provided with a plurality of U-shaped tubes 8-1, one port of which is welded to the outer (upper) collecting annular tube 5 located on the radial tube of the catalytic bed, and the other port is welded inside (the lower port is welded) ) Collecting water on the ring 6.

There is a long tubular steam drum at a height of several meters above the "bottle" shaped cylindrical casing, and the steam drum is divided into two large and small space steam drums 19 and a steam drum 1 by a partition.

The "wine bottle" shaped cylinder B is sleeved with the casing and is a catalytic bed radial cylinder 9, which is provided with a plurality of venting holes. The top end of the radial bed of the catalytic bed is connected with the bottle neck A; an annular gap is left between the outer wall of the radial bed of the catalyst bed and the inner wall of the cylindrical casing 11; the top of the radial tube of the catalytic bed is closed at the top and the wall is distributed with a plurality of The central intake pipe 7 of the venting orifice, the lower end of the central intake pipe 7 is an unreacted gas inlet located below the bottom of the cylindrical casing.

There is a tee pipe 14 in the middle of the bottom of the cylinder body, and the intake center intake pipe 7 is inserted therein. The tee pipe has a sealing packing 13-1 to block the inlet unreacted gas and the outlet reaction gas phase string, and the bottom has a small head 13-2. There are two unloading catalyst discharge ports 12 at the bottom of the cylinder. The shoulder of the cylinder has two catalyst loading ports 15, and the center of the bottle neck has a catalyst charging tube 3 which is connected to the upper and lower tubes.

The bottom of the steam drum 19 leads several tubes to be connected with the water chamber 18, through which the water enters the water chamber 18, and then descends to the bottom through the U-shaped 8-2, absorbs the heat outside the tube, continuously transforms into steam, and the steam-water mixture is lowered. Instead, it rises to the steam chamber 16 and rises up the steam outside the furnace to the steam drum 19. In the steam drum, the steam and water are separated, and the steam is taken out from the top.

The water descending from the steam drum 1 enters the water collecting ring 6, and then descends through the U-shaped tube 8-1. After the U-shaped tube is lowered, the heat is turned to the outside of the absorption tube through the bottom portion, and the gas phase is continuously converted into steam, and the vapor-water mixture rises from below to The collecting ring 5 is raised through the steam tube outside the furnace until the drum 1 is reached. In the steam drum, the steam and water are separated, the steam is taken out from the top, and the water enters the water pipe from the bottom of the steam drum.

The steam drum 19 and its water vapor circulation system and steam drum 1 and its water vapor circulation system are two independent systems. The steam pressure of the steam drum 19 system is higher than the steam pressure of the steam drum 1 system.

When the CO-containing gas enters the central intake pipe 7 from the bottom tee 14 of the "bottle"-shaped cylindrical casing, it passes through the catalytic bed 10 through the pores, and the reaction heat is released, and the reaction heat is absorbed by the water vapor mixture in the pipe, and the water is changed. For steam, keep the temperature inside the bed and tube constant. After the reaction, the CO is lowered to the target value, passing through the small hole of the radial tube 9 of the catalytic bed, and is collected in the radial cylinder annulus of the cylindrical wall of the catalytic wall, and the outlet is three-way from the bottom of the reactor from top to bottom.

The U-shaped tube has different lengths on both sides, and the short side of the U-shaped tube faces the center of the catalyst bed. The water vapor flows from the top to the bottom from the top to the bottom, and the short side flows from the bottom to the top. The short side has a larger degree of vaporization than the long side. The external reaction gas flows radially from the short side to the long side, and the air flow first flushes the short side, and the heat transfer capability is stronger, so that the short side can be vaporized more.

The inner ring U-shaped tube 8-2 corresponding to the steam drum 19 and the U-shaped tube 8-1 surrounding the "belly" corresponding to the steam drum 1 are two different water vapor circulation systems of water vapor pressure level, and the central system has high pressure and peripheral system. Low pressure.

Because 85%~95% CO reaction process state is far away from the equilibrium point line, the reaction driving force is large, and it can be carried out at a higher temperature. At this time, the amount of CO is much, the amount of heat is much, and the amount of catalyst is not much, but it needs to be changed. The thermal area is large. When the reaction approaches the terminal, the reaction CO needs to be small, the heat release is small, and the demand heat exchange area is small. The reaction process state is close to the equilibrium point; but the temperature is low, which is favorable for the reaction to continue, and the reaction at low temperature. A lot of catalyst is needed. As shown in Figure 9.

In this embodiment, the CO in the gas to be converted can be up to 80% to 90%, and the CO can be reduced to 0.3% to 0.4% after the conversion.

The above-described embodiments are to be understood as being illustrative only and are not intended to limit the scope of the present invention. Modifications are within the scope defined by the claims appended hereto.

Claims

An isothermal low temperature shifting furnace comprising a casing (11), a steam drum (1), a catalytic bed radial cylinder (9) disposed in the outer casing (11) for placing the catalyst (10), located at the center of the outer casing (11) And a vertically arranged central intake pipe (7), and a water chamber (18) and a steam chamber (16) disposed at the top of the outer casing (11); the water chamber (18) and the steam chamber (16) are passed between The tube sheets (2) are spaced apart, and the vapor chamber (16) is separated from the inner chamber of the outer casing (11) by a lower tube sheet (4); characterized in that the upper portion of the catalytic bed radial tube (9) a gas collecting ring (5) and a water collecting ring (6) are provided, the water collecting ring (6) is connected to the water outlet of the steam drum (1) through a pipe, and the gas collecting ring (5) passes through the steam pipe and the steam The inlet of the package (1) is connected; a plurality of U-shaped water-cooled tubes (8-1) are disposed between the radial bed (9) of the catalytic bed and the central intake pipe (7), and each U-shaped water-cooled tube One end of (8-1) is connected to the gas collecting ring (5), and the other end is connected to the water collecting ring (6); and the U-shaped water-cooling pipe (8-1) and the central intake pipe (7) are further provided with a plurality of U-shaped tubes (8-2) or double sleeves (8-3); one end of the U-shaped tube (8-2) is in communication with the steam chamber (16), and the other end is connected to the water chamber ( 18) connected; or the double The inner tube (23) of the tube (8-3) is in communication with the water chamber (18), and the outer tube (22) is in communication with the steam chamber (16); the U-shaped water-cooling tube (8-1) forms water vapor The outer ring is looped, and the U-shaped tube (8-2) or the double sleeve (8-3) forms a water vapor circulation inner ring.
The isothermal low temperature shifting furnace according to claim 1, characterized in that the gas collecting ring (5) is located above the water collecting ring (6).
The isothermal low temperature shifting furnace according to claim 1, wherein both ends of the U-shaped tube (8-2) are fixed to the lower tube sheet (4), one end of which passes through the short tube (17) and the The water chamber (18) is connected.
The isothermal low temperature shifting furnace according to claim 1, wherein a spiral coil (24) is disposed between the inner tube (23) and the outer tube (22) of the double sleeve (8-3), The inner tube (23) communicates with the water chamber (18) through a threaded short tube (25).
The isothermal low temperature shifting furnace according to claim 1, wherein an annular gap is formed between the outer casing (11) and the catalytic bed radial cylinder (9), and the annular gap is connected to a reaction gas outlet disposed at the bottom of the outer casing. The bottom of the central intake pipe (7) is in communication with the inlet of the unreacted gas.
The isothermal low temperature shifting furnace according to claim 1, wherein said U-shaped water-cooling pipe (8-1) The lengths of the two branches of the U-shaped tube (8-2) are not equal, and the shorter branch tube is disposed on the side of the central intake pipe (7).
The isothermal low temperature shifting furnace according to claim 1, wherein said outer casing (11), water chamber (18) and steam chamber (16) are in the form of a bottle, said water chamber (18) and a steam chamber. (16) Located at the bottleneck of the bottle.
The isothermal low temperature shifting furnace according to claim 1, wherein the upper tube sheet (2) is thinner than the lower tube sheet (4); and the lower surface of the upper tube sheet (2) is provided with a support ring ( 28), a flexible graphite sealing ring (27-1) is disposed between the lower surface of the upper tube sheet (2) and the support ring (28), and a pressing ring (26) is fixedly mounted on the upper surface of the upper tube sheet (2). A flexible graphite seal (27-2) is provided between the ring (26) and the upper surface of the upper tube sheet (2).
An isothermal low-temperature transformation process is characterized in that two sets of water vapor circulation systems are arranged in an isothermal low-temperature reforming furnace, and one set of water vapor circulation systems is located inside another group, and the specific transformation process comprises the following steps:

1) preheating stage, preheating unreacted gas to a certain temperature, maintaining the CO isothermal conversion rate of 0;

2) In the constant temperature stage, the CO isothermal conversion rate is maintained in the range of 260 ° C to 310 ° C of 90% to 93%. At this time, the water in the water pipe absorbs heat and reacts to release heat, and the temperature in the catalyst bed is kept constant;

3) In the cooling stage, the isothermal conversion rate is maintained in the range of 190 ° C to 220 ° C by 97% to 99% until the operation line intersects with the optimum temperature curve, and the unreacted gas is discharged.