System and method for operating a system

Abstract

The invention relates to a method for supplying steam to a system (1) having a steam-assisted flare (2), the flare (2) having a gas feed (3) for a gas to be flared off and a steam feed (7) for the steam, the flare (2) being designed in such a way that, during operation, a gas flowing in via the gas feed (3) is flared off essentially without smoke by virtue of the addition of steam flowing in via the steam feed (7), and the system having a rapid steam generator (11) in which steam is generated by the stoichiometric combustion of hydrogen and oxygen, the steam generated in the rapid steam generator (11) flowing into the steam feed (7).

Description

[0001] Description

[0002] Plant and method for operating a plant

[0003] The invention relates to a plant comprising a steam-assisted flare, wherein the flare has a gas supply for a gas to be flared and a steam supply for a steam, wherein the flare is designed in such a way that, during operation, a gas flowing in via the gas supply with the admixture of a steam coming via the steam supply can be flared off essentially smokelessly.

[0004] The invention further relates to a method for supplying a plant with a steam-assisted flare with steam, wherein the flare has a gas supply for a gas to be flared and a steam supply for the steam, wherein the flare is designed such that, during operation, a gas flowing in via the gas supply with the admixture of a steam coming via the steam supply is flared off essentially smokelessly.

[0005] Many industrial processes produce gases, so-called process gases, which are not further utilized and are flared. Venting process gases and reducing emissions through flaring is very common in many industrial processes, e.g., in chemical plants, gas pipelines and distribution systems, LNG plants, offshore / onshore oil and gas production, petrochemical plants, and refineries.

[0006] The flaring of some process gases, such as heavy hydrocarbons, produces smoke. Typical environmental regulations require companies to limit their flaring emissions so that emissions do not exceed certain limits for specific periods.

[0007] Flaring solutions include steam-assisted flares, air-assisted flares, or high-pressure flares. When the vent gas is not under high pressure, steam- and air-assisted flares are typically used.

[0008] Steam-assisted flares are designed for the disposal of heavier hydrocarbon gases. To prevent smoke development, steam is injected into the flare gas effluent stream, creating the ideal mixture for complete combustion.

[0009] Large quantities of high-pressure steam are used to entrain atmospheric air and force the air to mix with the exhaust gases. The greater the amount of air mixed per steam injected with the exhaust gases, the higher the achievable smoke-free capacity.

[0010] Steam-assisted flares have the advantage of fewer maintenance problems, lower annual energy costs, lower maintenance costs, and a longer flare tip life. Especially when steam is available from the industrial process, steam-assisted flares are more cost-effective than air-assisted flares because the air flow is much higher than that of steam.

[0011] The higher the carbon content of the flare gas, the higher the steam rate required for flaring.

[0012] Secondly, the reliability and availability of the support medium must be guaranteed at all operating points, as the system must ensure that the emission specifications can be met under all load cases. In some plants, steam is generated by (chemical) processes. This steam can be used for flaring. However, during abnormal operation, no steam is available and at the same time additional vent gases have to be flared, i.e. the amount of steam required for flaring is the reciprocal of the amount of steam available. Air-assisted flaring, which is more expensive to operate, is often used because conventional technologies cannot generate additional steam quickly enough.

[0013] Against this background, the invention has set itself the task of specifying a plant and a method in which flaring is easier.

[0014] This object is achieved by a system comprising a steam-assisted flare, the flare having a gas supply for a gas to be flared and a steam supply for a steam, the flare being designed in such a way that, during operation, a gas flowing in via the gas supply with the admixture of steam coming via the steam supply can be flared off essentially smokelessly, with a flash steam generator in which steam can be generated by the combustion of hydrogen and oxygen, the steam generated in the flash steam generator being able to flow into the steam supply.

[0015] The object is also achieved by a method for supplying a plant with a steam-supported flare with steam, wherein the flare has a gas supply for a gas to be flared and a steam supply for the steam, wherein the flare is designed such that, during operation, a gas flowing in via the gas supply with the admixture of steam coming via the steam supply is flared off essentially smokelessly, with a flash steam generator in which steam is generated by the combustion of hydrogen and oxygen, wherein the steam generated in the flash steam generator flows into the steam supply.

[0016] The invention enables rapid generation of steam for the flare. The combustion of hydrogen and oxygen in the flash steam generator produces steam at high temperatures. In combination with water injection, a large amount of steam can be generated comparatively quickly because the slow phase change from water to steam that occurs in the technical standard of a heat exchanger is avoided. Therefore, in an emergency load situation in which no steam supply from the system is available, the flash steam generator can provide the steam supply for the steam-assisted flare. This enables the use of a steam-assisted flare even during unfavorable process operation and saves expenditure on air compression during a large part of the operating time.

[0017] The invention is based on the idea that the required amount of steam depends on both the gas to be flared and the operating point of the plant. Typically, the amount of flare gas and its composition increase during emergency operation for heavier hydrocarbon gases. This means that the amount of medium required for flaring is much higher in emergency operation. Since emergency operation usually only takes place for short periods of time, the costs for hydrogen and oxygen during these periods are low compared to the reduced operating costs in normal operation.

[0018] The invention provides the advantage that a hydrogen and oxygen based rapid steam generator as an emergency steam generator enables the use of steam assisted flares.

[0019] An advantage of the invention is to use the flash steam generator as a superheater to prevent water droplets in the steam of the steam supply.

[0020] An additional advantage is the use of wet steam instead of water as the cooling steam medium of the flash steam generator.

[0021] Advantageous further developments are specified in the subclaims. Combustion need not be stoichiometric. It may be advantageous to burn with an excess of oxygen or hydrogen.

[0022] It is therefore advantageous if the rapid steam generator has a hydrogen supply line for supplying hydrogen and an oxygen line for supplying oxygen and a combustion chamber, wherein the stoichiometric combustion of hydrogen and oxygen takes place in the combustion chamber to produce steam, wherein the steam can flow into a rapid steam generator outlet line, wherein the rapid steam generator outlet line is fluidically connected to the steam supply.

[0023] In a further advantageous development, the rapid steam generator is designed in such a way that the combustion of hydrogen and oxygen takes place in several successive stages.

[0024] This measure allows the quality and quantity of steam to be better regulated.

[0025] In a further advantageous development, the system has a steam supply line, wherein the steam supply line is connected to the steam inlet and, in a first operating state, supplies the flare with steam from a system process. Thus, the system is designed for two operating states, which can be utilized according to the invention. For this purpose, the system advantageously has a switching valve device with which switching between the two operating states can be achieved.

[0026] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings. Identical components or components with the same function are designated by the same reference numerals.

[0027] Exemplary embodiments of the invention are described below with reference to the drawings. These are not intended to represent the exemplary embodiments to scale; rather, where useful for explanation, the drawings are presented in a schematic and / or slightly distorted form. For supplements to the teachings immediately apparent in the drawings, reference is made to the relevant prior art.

[0028] It shows :

[0029] Figure 1 is a schematic representation of an embodiment of a system according to the invention

[0030] Figure 1 shows a plant 1. The plant 1 comprises a flare 2, the mode of operation of which is explained below. In an industrial process, such as in chemical plants, in gas pipelines and distribution systems, in LNG plants, in offshore / onshore oil and gas production, in petrochemical plants and in refineries, process gases are produced which must be flared. The process gas flows via the gas supply 3 to the flare 2. The flare 2 has an outer jacket 4. The process gas flows along within the jacket 4. Also within the jacket 4 is a steam injection device 5 which is designed to mix steam into the process gas. For this purpose, the tubular steam injection device 5 has outlet lines 6 for the steam at its end.The flare 2 is referred to as a steam-assisted flare 2 and is designed in such a way that, during operation, the gas flowing in via the gas supply 3 with the admixture of a steam coming via the steam injection device 5 can be flared off essentially smokelessly.

[0031] The steam flows via steam inlet 7 into the steam injection device 5. The steam inlet 7 is fluidly connected to a steam supply line 8 in which a first valve 9 is arranged. The steam flowing in the steam supply line 8 comes from an industrial process or a plant process which is not explained in more detail. In any case, the origin of the steam from this industrial process or plant process is symbolized by the reference numeral 10. This steam can be wet steam which is superheated using the flash steam generator 11. In a first operating state, the first valve 9 is open and the flare 2 is supplied with steam from the industrial process or the plant process.

[0032] If a situation arises in which the steam from the industrial process or the plant process is no longer available in sufficient quantity, the steam is generated and made available in a different way according to the invention, which will now be explained in more detail. A main component is the flash steam generator 11. The flash steam generator 11 has a hydrogen supply line 12 and an oxygen supply line 13. Hydrogen flows into a combustion chamber (not shown in more detail) via the hydrogen supply line 12. Oxygen also flows into the combustion chamber via the oxygen supply line 13. The oxygen and the hydrogen react in the combustion chamber, subsequently producing steam at very high temperatures. Water is added via a water line 14 at the operating point required for the flare. This can influence the physical values ​​of the steam.The pressure in the water line 14 can be generated, for example, by a pump 15 arranged in the line.

[0033] The steam flows into the steam supply 7 via a rapid steam generator outlet line 16. In an alternative embodiment, the rapid steam generator 11 can be designed such that the combustion of hydrogen and oxygen occurs in several successive stages. For this purpose, hydrogen, oxygen, and water are added at a further point 17, which also react with each other and generate additional steam.

[0034] In an alternative embodiment, air can be used instead of oxygen. In another alternative embodiment, the steam is generated by water injection.

[0035] The flash steam generator 11 is connected to a steam line 18, which is fluidly connected to the steam supply line 8. A second valve 19 is arranged in the steam line 18. The first valve 9 and the second valve 19 form a changeover valve device. In the first operating state, in which the steam for the flare 2 comes from the industrial process or the plant process, the first valve 9 is open and the second valve 19 is closed. In the second operating state, in which the steam for the flare 2 comes from the flash steam generator 11, the first valve 9 is closed and the second valve 19 is open.

[0036] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited to the disclosed examples and other variants can be derived by the person skilled in the art without departing from the scope of the invention.

Claims

Patent claims 1. Plant (1) comprising a steam-assisted flare (2), the flare (2) having a gas supply (3) for a gas to be flared and a steam supply (7) for a steam, the flare (2) being designed such that, during operation, a gas flowing in via the gas supply (3) with the admixture of steam coming via the steam supply (7) can be flared off essentially smokelessly, characterized by a rapid steam generator (11) in which steam can be generated by the combustion of hydrogen and oxygen, the steam generated in the rapid steam generator (11) being able to flow into the steam supply (7).

2. Plant (1) according to claim 1, wherein the rapid steam generator (11) has a hydrogen supply line (12) for supplying hydrogen, an oxygen line (13) for supplying oxygen and a combustion chamber, wherein the combustion of hydrogen and oxygen takes place in the combustion chamber to produce steam, wherein the steam can flow into a rapid steam generator outlet line (16), wherein the rapid steam generator outlet line (16) is fluidically connected to the steam supply (7).

3. Plant (1) according to claim 1 or 2, wherein the rapid steam generator (11) is designed such that the combustion of hydrogen and oxygen takes place in several stages one after the other.

4. Plant (1) according to one of the preceding claims, wherein the rapid steam generator (11) is fluidly connected to a water line (14).

5. Plant (1) according to one of the preceding claims, comprising a steam supply line (8), wherein the steam supply line (8) is connected to the steam feed (7) and, in a first operating state, supplies the flare (2) with steam from a plant process.

6. Plant (1) according to claim 5, with a changeover valve device (9, 19) which is designed such that in a second operating state the flare (2) is only supplied with steam from the flash steam generator (11).

7. Method for supplying a plant (1) having a steam-assisted flare (2) with steam, the flare (2) having a gas supply (3) for a gas to be flared and a steam supply (7) for the steam, the flare (2) being designed such that, during operation, a gas flowing in via the gas supply (3) with the admixture of steam coming via the steam supply (7) is flared off essentially smokelessly, characterized by a rapid steam generator (11) in which steam is generated by the combustion of hydrogen and oxygen, the steam generated in the rapid steam generator (11) flowing into the steam supply (7).

8. The method according to claim 7, wherein in a first operating state the plant (1) is supplied with steam from a normal operation of a plant process (10) and in a second operating state in which no steam from the normal operation is available, the plant (1) is supplied with steam from the flash steam generator (11).

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