JP5506255B2 - Gas processing equipment - Google Patents

Description

  The present invention relates to a gas processing apparatus used in a wet hydrogen sulfide environment for processing gas containing hydrogen sulfide, such as natural gas, petroleum-associated gas, and petroleum refined gas.

  There are many treatment processes for natural gas containing hydrogen sulfide, gas associated with petroleum, and refined petroleum gas. In these apparatuses, the gas to be handled is often high pressure. In many cases, these devices have a large weight such as a slag catcher, a gas oil separator, an amine absorption tower, and a regeneration tower.

  Many of the equipment used in the sulfur recovery process or the like as the treatment process is usually made of a steel plate for pressure vessels (carbon steel) in consideration of the corrosion allowance. This is because the iron sulfide film formed by the reaction between iron and hydrogen sulfide covers the surface of the iron on the fluid side of the container (inside the container), which prevents the corrosion from progressing to some extent. Carbon steel can be used for a long time.

However, since atomic hydrogen generated when iron sulfide is formed is extremely small, it enters the carbon steel and permeates the carbon steel. The atomic hydrogen that has entered the carbon steel cannot permeate the manganese sulfide layer formed in the carbon steel, as will be described later. Become. Cracks occur due to the hydrogen gas accumulated in the carbon steel.
That is, an ordinary steel plate for a (pressure) container (coal bed steel) is used for a container such as a pressure vessel used in a process for treating a gas containing hydrogen sulfide as described above, that is, a vessel used in a wet hydrogen sulfide environment. If used, hydrogen-induced cracking will occur. That is, HIC (Hydrogen Induced Cracking) occurs. It is known that non-metallic inclusions in carbon steel basically accumulate atomic hydrogen that permeates through the carbon steel and cause HIC.

Therefore, in the above-mentioned wet hydrogen sulfide environment, it has become common knowledge to use HIC-resistant steel that has been specially treated during production to reduce the content of non-metallic inclusions (for example, patent documents). 1).
The manganese sulfide layer described above is used when manganese sulfide, which has been reacted with manganese and sulfur added to remove impurity sulfur in a converter or the like for making a carbon steel ingot, stretches the carbon steel ingot to a steel plate with a roller. It is layered and remains in the carbon steel.

  On the other hand, the above-mentioned HIC-resistant steel is, for example, carbon steel without a layer of manganese sulfide, and calcium is added to make sulfur a compound of calcium sulfide CaS when making a carbon steel ingot. CaS is produced in a spherical shape, and even when the carbon steel ingot is stretched to form a carbon steel plate, it remains in the carbon premises in a spherical state. As described above, when atomic hydrogen permeates through the carbon steel, atomic hydrogen is absorbed. Without blocking, it is possible to prevent atomic hydrogen from being molecularized (gasified) in carbon steel. CaS is also a non-metallic inclusion, and it is preferable that the content in the HIC steel is low.

JP-A-10-237533

  By the way, since it is difficult to manufacture high strength HIC-resistant steel, when the strength required for the pressure vessel is obtained, the thickness of the pressure vessel increases and the weight increases. In recent plants equipped with the above-mentioned hydrogen sulfide-containing gas treatment equipment that requires such HIC-resistant steel, the equipment tends to increase in size, the weight of these pressure vessels increases, production, transportation, The difficulty is increasing in construction.

  That is, since it is difficult to increase the strength of HIC-resistant steel, for example, a container used in a wet hydrogen sulfide environment requires a sufficient plate thickness to obtain the required strength, and such a container is enlarged. When it does, it will have a big weight. For example, in the amine absorption tower which is a pressure vessel of the above-described gas processing apparatus, the use of HIC-resistant steel that has not been increased in strength and the size of the amine absorption tower that exceeds 1000 tons have been made due to the increase in size.

Here, the following problem arises when the weight of the large pressure vessel exceeds 1000 tons.
First, there are few production factories equipped with facilities for producing large-sized pressure vessels having a weight exceeding 1000 tons, and the production factories are limited. In this case, it becomes difficult to efficiently manufacture the pressure vessel, and it becomes difficult to secure a transportation route to the construction site of the gas processing apparatus, which may increase the cost of transportation.

Second, the bridge or road in the route for transporting the pressure vessel from the manufacturing plant to the installation site of the construction site cannot withstand a weight of 1000 tons or more, and it may be difficult to transport the pressure vessel. At this time, if transport is possible by passing the detour route, there is a possibility that the transport period becomes longer or the transport cost becomes higher.
Third, when the pressure vessel (processing tower) is installed upright at the construction site, a special crane capable of handling a weight of 1000 tons or more is required. The number of such special cranes is limited, and there is a possibility that the usable period of the crane is limited, and it is expensive to transport the crane.

As a method to solve the above-mentioned problems, the entire pressure vessel is not assembled at the production factory, and each part is transported to the construction site while being divided into parts. There is a method of assembling by welding, performing a treatment such as annealing of the welded portion, and standing up by the ginpole method.
However, there are problems in terms of schedule, quality control, and cost in actually assembling locally, and implementation is difficult.
Furthermore, when the pressure vessel that requires high strength is further increased in size, the plate thickness necessary for the pressure vessel may exceed the production limit of the steel plate made of HIC steel.

  The present invention has been made in view of the above circumstances, and provides a gas processing apparatus capable of reducing the weight by reducing the thickness of a steel plate used in a container of a gas processing apparatus used in a wet hydrogen sulfide environment. The purpose is to provide.

In order to achieve the above object, the gas processing apparatus according to claim 1 is a container used in a wet hydrogen sulfide environment for processing a gas containing hydrogen sulfide, such as natural gas, petroleum-associated gas, and petroleum refined gas. a gas treatment apparatus provided with a steel sheet for the container, yield point 300N / mm ² or more, 900 N / mm ² or less and a tensile strength of 490 N / mm ² or more, 1200 N / mm ² or less high It is characterized by being formed of clad steel lined with austenitic stainless steel on the entire inner surface of tensile steel.

In the invention described in claim 1, the steel sheet used in the wet hydrogen sulfide environment is not a HIC-resistant steel, but a clad steel in which an austenitic stainless steel is lined on a high-tensile steel having a yield point of 300 N / mm ² or more. Therefore, in the wet hydrogen sulfide environment, the stainless steel on the inner surface of the container comes into contact with hydrogen sulfide, but corrosion by hydrogen sulfide is prevented by the stainless steel. That is, generation of iron sulfide due to hydrogen sulfide is prevented on the inner surface of the container made of stainless steel. By preventing the generation of iron sulfide, generation of atomic hydrogen on the inner surface of the container is also prevented.
Therefore, generation of HIC is prevented by using austenitic stainless steel as the cladding material.
And since the said high-tensile steel is used as a base material of the clad steel used for the steel plate for containers, it is possible to reduce the plate thickness of the plate material of the container even with the same strength as compared with the case of using HIC steel. This makes it possible to reduce the weight of the container while ensuring strength.
That is, by making the yield point of high-tensile steel 300 N / mm ² or higher and the tensile strength 490 N / mm ² or higher, the plate thickness of the container can be made thinner than when using HIC steel. Can do. In other words, when the yield point and tensile strength are lower than the above values, there is little difference in plate thickness with HIC steel when the high-strength steel is lined or overlay welded with austenitic stainless steel. It becomes difficult to reduce the weight.
Also, the yield point of the high-tensile steel and 900 N / mm ² or more, the tensile strength and larger than 1200 N / mm ^2, there is a possibility that processing becomes difficult.

The gas processing device according to claim 2 is a gas processing device including a container used in a wet hydrogen sulfide environment for processing a gas containing hydrogen sulfide, such as natural gas, petroleum-associated gas, and petroleum refined gas. Te, steel sheet for the container, yield point 300N / mm ² or more, 900 N / mm ² or less and a tensile strength of 490 N / mm ² or more, the entire inside of 1200 N / mm ² or less of high-tensile steel, austenite Stainless steel is formed by overlay welding.

In the invention described in claim 2, the steel plate used in the wet hydrogen sulfide environment is not a HIC-resistant steel, but a steel plate obtained by overlay welding austenitic stainless steel to high-tensile steel having a yield point of 300 N / mm ² or more. Therefore, as in the case of claim 1, it is possible to reduce the weight by reducing the plate thickness of the steel plate of the container while preventing HIC.
In order to reduce the weight, it is advantageous to line the stainless steel than overlay welding because it can greatly reduce the plate thickness. However, the plate thickness of the clad steel is limited in terms of production, depending on the size, required strength, etc. When the plate thickness of the high-tensile steel becomes thick, it can be dealt with by using overlay welding.
The invention according to claim 3 is the invention according to claim 2, wherein the high-tensile steel is thicker than 150 mm.

  The gas treatment apparatus according to claim 4 is the invention according to any one of claims 1 to 3, wherein the type of the austenitic stainless steel is SUS301, SUS302, SUS303, SUS304, SUS304L in JIS standards. It is any one of SUS305, SUS316, SUS316L, SUS317, SUS321, and SUS347.

  In the invention according to claim 4, an austenitic stainless steel having a nickel: Ni content of 6% or more, preferably 8% or more and a chromium: Cr content of 16% or more, preferably 18% or more. By using it, corrosion by hydrogen sulfide in a wet hydrogen sulfide environment can be prevented, thereby preventing generation of HIC.

By setting the yield point of high-tensile steel to 300 N / mm ² or more and the tensile strength to 490 N / mm ² or more, the plate thickness of the container can be made thinner than when HIC steel is used. . In other words, when the yield point and tensile strength are lower than the above values, there is little difference in plate thickness with HIC steel when the high-strength steel is lined or overlay welded with austenitic stainless steel. It becomes difficult to reduce the weight.
Also, the yield point of the high-tensile steel and 900 N / mm ² or more, the tensile strength and larger than 1200 N / mm ^2, there is a possibility that processing becomes difficult.

  ADVANTAGE OF THE INVENTION According to this invention, the plate | board thickness of the container of the gas processing apparatus used in wet hydrogen sulfide environment can be made thin, and the weight reduction of a container can be achieved. Further, by reducing the weight of the container, it is possible to cope with a further increase in the size of a gas processing apparatus that processes a gas containing hydrogen sulfide.

It is a side view which shows the amine absorption tower which concerns on embodiment of this invention. It is principal part sectional drawing of an amine absorption tower.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a side view showing an amine absorption tower according to an embodiment of the present invention, and FIG. 2 is a sectional view of a main part (nozzle part) of the amine absorption tower.
The gas processing apparatus of this example is, for example, an amine absorption tower 1 as a container provided in a gas processing facility when removing hydrogen sulfide contained in natural gas.

  The amine absorption tower 1 is used in a process for removing hydrogen sulfide contained in natural gas. If natural gas containing hydrogen sulfide is used as fuel as it is, sulfurous acid gas is generated as a combustion product, which causes pollution, so it is necessary to remove hydrogen sulfide from natural gas. It is common to remove by chemical absorption (acid-alkali reaction) acid gas removal process using potassium carbonate.

  In this process, for example, the above-described amine absorption tower 1 is used, a raw material gas is put into the lower part of the amine absorption tower 1, and a lean amine solution (solution before absorbing hydrogen sulfide) is introduced from the tower top 10 of the amine absorption tower 1. The hydrogen sulfide is reacted and absorbed by countercurrent contact (gas-liquid contact) between the raw material gas (natural gas containing hydrogen sulfide) and the amine solution using a tray or packing in the amine absorption tower 1 and the like. Remove hydrogen sulfide.

  The source gas from which hydrogen sulfide has been removed is sent to an apparatus that performs the next treatment process. Also, the amine solution that has reacted and absorbed hydrogen sulfide becomes a rich amine solution (solution after absorbing hydrogen sulfide), which is extracted from the amine absorption tower 1 and warmed in a heat exchanger, and is reduced in pressure to the amine regeneration tower. Sent. A reboiler is installed at the bottom of the amine regeneration tower, and the rich amine solution is heated to generate steam to strip hydrogen sulfide from the amine solution. A condenser is installed at the top of the tower, and water is condensed in this condenser, and is refluxed to the amine regeneration tower.

The hydrogen sulfide stripped in the amine regeneration tower is discharged and recovered as sulfur by a sulfur recovery device or the like.
The amine solution from which hydrogen sulfide has been removed in the amine regeneration tower is returned to the amine absorption tower 1 from the amine regeneration tower as a lean amine solution.
In such an amine absorption tower 1, the inside becomes a wet hydrogen sulfide environment, which may cause problems such as the generation of HIC described above.

In the amine absorption tower 1 of this example, as a steel plate for containers constituting the amine absorption tower 1, an austenitic stainless steel 3 (hereinafter abbreviated as stainless steel) is lined over the high-tensile steel 2. That is, clad steel 4 made of high-tensile steel 2 and stainless steel 3 is used for amine absorption tower 1. In addition, the internal attachment metal fitting 5 etc. for attaching internal members, such as a tray in the amine absorption tower 1, packing, etc. are formed, for example with austenitic stainless steel. The tubular portion to which the pipe of the amine absorption tower 1 is attached is also lined or overlay welded with austenitic stainless steel.
The clad steel 4 in this example uses the high-tensile steel 2 as a base material and the stainless steel 3 as a clad material. In the clad steel 4, the base material and the clad material are metallurgically joined at the boundary portion between them.

The high strength steel, the yield point of the its mechanical properties 300N / mm ² or more, at 900 N / mm ² or less, a tensile strength of 490 N / mm ² or more, and has a 1200 N / mm ² or less.
In the high-tensile steel 2, if the yield point is 300 N / mm ² or more and the tensile strength is 490 N / mm ² or more, for example, with respect to the thickness of the container when the container is formed of HIC steel, It is possible to significantly reduce the thickness of the container made of the above clad steel.

On the contrary, in the high strength steel 2, when the yield point is smaller than 300 N / mm ² and the tensile strength is smaller than 490 N / mm ² , the difference in plate thickness from the container made of HIC steel cannot be increased. In particular, since stainless steel is lined, it is not possible to sufficiently reduce the weight by reducing the plate thickness.
Also, the yield point of the high-tensile steel and 900 N / mm ² or more, the tensile strength when the larger than 1200 N / mm ^2, the processing cost becomes difficult to increase.

The thickness of the high-strength steel 2 as the base material in the grad steel is determined by the pressure required in the pressure vessel, the size of the pressure vessel, and the like. When a thickness of about 200 mm is required, for example, when a high tensile steel having a yield point of 450 N / mm ² and a tensile strength of 590 N / mm ² is used, the thickness is about 110 mm to about 140 mm, for example. It becomes.

As the austenitic stainless steel as the clad material in the clad steel, those of the following JIS standards can be suitably used.
SUS301: Ni (6-8%), Cr (16-18%)
SUS302: Ni (8-10%), Cr (17-19%)
SUS303: Ni (8-10%), Cr (17-19%), Mo (0.60% or less can be added)
SUS304, SUS304L: Ni (8 to 10.5%), Cr (18 to 20%)
SUS305: Ni (10.5-13%), Cr (17-19%)
SUS316, SUS316L: Ni (10-14%), Cr (16-18%), Mo (2-3%)
SUS317: Ni (11-15%), Cr (18-20%), Mo (3-4%)
SUS321: Ni (8 to 10.5%), Cr (18 to 20%), Ti (1 to 2%)
SUS347: Ni (8 to 10.5%), Cr (18 to 20%), Nb (1 to 2%)

Moreover, if the thickness of the stainless steel as a clad material is about 2-4 mm, for example, corrosion can fully be prevented and generation of HIC can be prevented.
Further, in the gas treatment apparatus, all of the parts that become the wet hydrogen sulfide environment, other than the container part, use the above-described clad steel 4 or those obtained by overlaying stainless steel, or HIC such as HIC-resistant steel. It is preferable to use a member whose generation is suppressed, and it is necessary to use a clad steel 4 or an overlay welded part for a portion where the weight is increased in a large container.

Below, the design values, such as plate | board thickness and weight in the amine absorption tower 1 constructed | assembled with the HIC steel and the amine absorption tower 1 constructed | assembled with the clad steel 4 of this example, were calculated | required.
As a design standard at this time, ASME (American Society of Mechanical Engineers) Section viii Division ² (2007) was applied.
Table 1 shows the gas composition of natural gas from which hydrogen sulfide is to be removed as a design condition.

The natural gas flow rate as a design condition was 1500 MMSCFD (million standard cubic feet per day).
As the HIC-resistant steel, those having mechanical properties shown in Table 2 were used, and similarly, as the high-tensile steel, those having mechanical properties shown in Table 2 were used. Moreover, SUS304 was used as stainless steel.

  With respect to the amine absorption tower 1, the plate thicknesses of the substantially hemispherical tower top 10, the substantially hemispherical tower bottom 11, and the cylindrical part 12 between the tower top 10 and the tower bottom 11 are the same. Calculation was based on the above design criteria. In addition, in the amine absorption tower 1 of HIC-resistant steel, the portion obtained by removing the corrosion allowance from the total plate thickness is shown in Table 2 as the calculated plate thickness. Further, in the amine absorption tower 1 made of the clad steel 4, the total plate thickness is obtained by adding the lining thickness of stainless steel to the calculated plate thickness of high-tensile steel.

Moreover, the size of the amine absorption tower 1 was such that the inner diameter of the tower was 6500 mm and the height of the cylindrical portion 12 of the tower was 35 m, corresponding to the natural gas flow rate described above. In addition, TL in Table 2 is a tangent line, indicates the boundary between the hemispherical portion and the cylindrical portion, and TL-TL is the length of the cylindrical portion 12 excluding the tower top 10 and the tower bottom 11.
The design temperature in the amine absorption tower 1 was 100 ° C., and the design pressure was 80 bar.
As shown in the calculation results of Table 2, the total plate thickness including the corrosion allowance of the HIC steel in the cylindrical portion is 168 mm, whereas the total plate thickness of the clad steel is 108 mm. Similarly, the total plate thickness including the corrosion allowance of the HIC steel is 87 mm at the tower top and the tower bottom, whereas the total plate thickness is 56 mm in the clad steel.

That is, by using the clad steel 4 made of the high-tensile steel 2 and the stainless steel 3, the thickness of the container of the gas processing apparatus used in the wet hydrogen sulfide environment can be reduced.
And with the Erection weight (weight when built), the absorption tower of HIC-resistant steel is 1230 tons, whereas in the case of clad steel made of high-tensile steel and stainless steel, it becomes 801 tons, about 35% It is possible to reduce the weight.

  That is, the weight of the amine absorption tower 1 can be reduced, and problems caused by handling heavy objects from manufacture to transportation and installation can be reduced, and cost can be reduced. it can. In particular, the problem which becomes serious when the weight of the container exceeds 1000 tons can be solved by reducing the weight to 1000 tons or less.

  In the above embodiment, as a steel plate for a container of a gas treatment facility used in a wet hydrogen sulfide environment, a steel plate of clad steel 4 lined with austenitic stainless steel is used as a high strength steel. A steel plate obtained by overlay welding (overlay welding) of stainless steel may be used. The overlay welding is performed by automatic welding. For example, the stainless steel layer is formed by overlay welding with an automatic welding machine on the inner peripheral surface of a steel plate made of high-strength steel formed in a cylindrical shape.

In overlay welding, a stainless steel layer is formed with a thickness of about 5 to 15 mm, usually about 10 mm. The thickness of the stainless steel part is thicker than in the case of the lining described above.
In addition, overlay welding can be used to overlay stainless steel on high-strength steel without any problem even if the thickness of high-strength steel increases, but in the case of clad steel 4 described above, the plate thickness of high-strength steel is large. Then, it becomes difficult to join the grad material to the base material.

  Therefore, for example, when the thickness of the high-strength steel becomes thick based on the container size, the pressure difference between the inside and outside of the container, etc. This is suitable when the plate thickness of the high-tensile steel exceeds, for example, 150 mm and becomes thicker under the condition that the thickness is increased. If the clad steel 4 can be produced even if the plate thickness of the high-tensile steel exceeds 150 mm, the clad steel 4 may be used.

Also, when a stainless steel layer is formed by overlay welding on the inside of high-strength steel, the basic container structure is the same as that shown in FIGS. 1 and 2, for example, on the inside of high-strength steel. The difference is whether the austenitic stainless steel is lined or overlay welded.
Further, in the case of overlay welding, substantially the same operational effects as in the case of lining can be obtained.

  Further, the present invention is not limited to the amine absorption tower 1 of the above example, and the inside thereof is used to treat the gas containing hydrogen sulfide such as the above-mentioned natural gas, petroleum-associated gas, and petroleum refined gas. It can be applied to various containers of gas treatment equipment that has a wet hydrogen sulfide environment, and can be applied to containers such as amine regeneration towers, slag catchers, and gas oil separators. It can be suitably used for a container that becomes thick.

1 Amine absorber 2 High-strength steel 3 Austenitic stainless steel

Claims (4)

A gas processing apparatus comprising a container used in a wet hydrogen sulfide environment for processing gas containing hydrogen sulfide, such as natural gas, gas associated with oil, and refined petroleum gas,
Steel for the container, yield point 300N / mm ² or more, 900 N / mm ² or less and a tensile strength of 490 N / mm ² or more, the entire inside of 1200 N / mm ² or less of high-tensile steel, austenitic stainless A gas processing apparatus characterized by being formed of clad steel lined with steel. A gas processing apparatus comprising a container used in a wet hydrogen sulfide environment for processing gas containing hydrogen sulfide, such as natural gas, gas associated with oil, and refined petroleum gas,
Steel for the container, yield point 300N / mm ² or more, 900 N / mm ² or less and a tensile strength of 490 N / mm ² or more, the entire inside of 1200 N / mm ² or less of high-tensile steel, austenitic stainless A gas processing apparatus, wherein steel is formed by overlay welding.   The gas processing apparatus according to claim 2, wherein a plate thickness of the high-tensile steel is greater than 150 mm.   The type of the austenitic stainless steel is any one of SUS301, SUS302, SUS303, SUS304, SUS304L, SUS305, SUS316, SUS316L, SUS317, SUS321, and SUS347 according to JIS standards. The gas treatment device according to any one of the above.

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