JPS6059164B2 - How to use low-pressure steam discharged from a sulfur recovery plant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for effectively utilizing low pressure steam discharged from a sulfur recovery plant.

When recovering elemental sulfur by direct ring reduction of sulfur oxides coming from flue gas desulfurization equipment or alternatively by Claus reaction with hydrogen sulfide, sulfur is added to the downstream side of the reduction reactor or Claus reactor. A method is used in which a condenser is installed to indirectly exchange heat with water to condense the sulfur vapor flowing out of the reactor into liquid sulfur.

According to this method, the cooling water supplied to the sulfur condenser is generally discharged from the sulfur condenser in a gas-liquid mixed phase, which is then sent to a steam drum where the vapor and liquid phases are separated. The liquid phase is circulated to the sulfur condenser together with cooling water that is replenished from time to time. By the way, in the above sulfur recovery method, the pipes, pumps, storage tanks, etc. that handle liquid sulfur, including the area below the sulfur condenser, must be maintained at a temperature of about 135 to 150 °C to prevent the liquid sulfur from solidifying. However, in order to perform this heat retention or heating with steam, a substantially constant amount of steam is required at all times.

On the other hand, as mentioned above, the amount of steam discharged from the F steam drum not only varies depending on the operating conditions of the equipment, but also the pressure ranges from 2.5 to 3.7 (9/clt), and the a ratio (127 to 3.7).
(140°C), it is difficult to use it as heat-insulating or heating steam for conduits, pumps, storage tanks, etc. that handle liquid sulfur. Therefore, conventionally, high-pressure steam from an external source has been used to insulate or heat parts that handle liquid sulfur.
The present invention proposes a method in which low-pressure steam, which is discharged from the steam drum of a sulfur recovery plant and which cannot be used effectively as it is, is mixed with high-pressure steam and used as a heat source to prevent liquid sulfur from solidifying. It is something to do.

Therefore, the method of the present invention introduces high-pressure steam from a high-pressure steam generation source into the first fluid inlet of the ejector through the first pressure regulating valve, and introduces low-pressure steam discharged from the steam drum of the sulfur recovery plant into the ejector. The medium pressure steam is introduced into the second fluid inlet to generate medium pressure steam, and the high pressure steam bypasses the ejector and connects the first
A second pressure regulating valve is provided that operates at a pressure 0.1 to 0.5k9/Ai lower than that of the pressure regulating valve, and while the amount of intermediate pressure steam generated from the ejector is controlled by the first and second pressure regulating valves, the intermediate pressure is It consists of circulating the steam to the sulfur recovery plant as insulation and/or heating steam.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS To explain the method of the invention with reference to the accompanying drawings, sulfur vapor exiting a reactor 1, such as a sulfur oxide reduction reactor or a Claus reactor, is fed to a sulfur condenser 2.

The sulfur vapor indirectly exchanges heat with the cooling water returned from the steam drum 3 in the condenser 2, is cooled to the condensation temperature, and is condensed into liquid sulfur. This liquid sulfur is led from the lower part of the condenser 2 to a sulfur tank 4, and is supplied to a sulfur storage tank 6 via a sulfur pump 5. On the other hand, the cooling water supplied to the sulfur condenser 2 is partially evaporated by heat exchange with sulfur vapor, and is supplied from the upper part of the condenser 2 to the steam drum 3 in a gas/liquid mixed phase state.

In the steam drum 3, a vapor phase and a liquid phase are separated from each other, and the liquid phase is circulated to the condenser 2 as cooling water. As mentioned above, the vapor phase recovered from the steam drum is between 2.5 and 3.7
k9/CFll. It is a low-pressure steam on the order of abS, and its temperature is 127 to 147°C even as saturated steam.In addition, the amount of steam varies considerably depending on the operating conditions of the equipment, so it is difficult to use conduits, pumps, and storage tanks that handle liquid sulfur. The reality is that it is difficult to use it for heat insulation or heating. In the present invention, low pressure steam discharged from the steam drum 3 is introduced into the second fluid inlet of the ejector 10 through a line 9 provided with a drum internal pressure control valve 7 and a check valve 8. High-pressure steam from a high-pressure steam generation source 11 is introduced into the first fluid (also referred to as driving fluid) inlet of the ejector 10 via the first pressure regulating valve 12, whereby medium-pressure steam is supplied from the ejector 10. Occur. Of course, the ejector 10 is designed to maximize the recovery rate of low pressure steam. Medium-pressure steam generated from the ejector 10 flows into a line 15 for insulating and/or heating the cooling water heater 16, the sulfur storage tank 6, the sulfur pump 5, the lower region of the sulfur condenser 2, etc., as shown in the figure. Used as a vapor, this vapor is usually
．． 3-4.9k9/Clt. abs(135-150℃
) must be held at a pressure of In many cases, this pressure can be maintained by adjusting the amount of high-pressure steam introduced into the ejector 10 as the first fluid using the first pressure regulating valve 12. However, when the consumption of intermediate pressure steam within the system increases, it is difficult to maintain the intermediate pressure steam at the above set pressure. Therefore, in the present invention, a line 13 is provided to bypass the high-pressure steam from the high-pressure steam generation source 11 to the line 15, and the bypass line 1 is 0.1 to 0.5 kg/a lower than the first pressure regulating valve 12.
l A second pressure regulating valve 14 that operates at a lower pressure is provided, and the line 1
While detecting the pressure of the medium-pressure steam flowing through 5 with a pressure transmitter, the pressure of the medium-pressure steam is regulated as follows.

That is, 3.3 to 4.9k9 depending on the first pressure regulating valve 12
/C7ll. The consumption of medium-pressure steam in the system increases, and the pressure is 0.1 to 0.5 k higher than the set pressure.
9/Crl becomes low, the second pressure regulating valve 14 operates in response to an electric signal from the pressure transmitter circle, and maintains the pressure of medium pressure steam by introducing high pressure steam directly into line 15. There is something to do. Although this method detects the pressure of intermediate pressure steam to open and close the first and second pressure regulating valves, it is also possible to perform similar control by detecting temperature instead of pressure. However, in this case, the response speed is somewhat slower than when using pressure. Alternatively, the first and second pressure regulating valves may each be self-bladed pressure control valves, and the line 15 may be connected to the first and second pressure regulating valves through a pressure conduit instead of a pressure transmitter. It is also possible to regulate the pressure of steam.
Note that when the consumption of medium-pressure steam is small and low-pressure steam is not sucked by the ejector 10, the check valve 8 prevents the medium-pressure steam from flowing backward, and the low-pressure steam from the steam drum 3 is It is released from the system through the relief valve 17.

As is clear from what has been described above, according to the present invention, low-pressure steam discharged from the steam drum of a sulfur recovery plant, which could hardly be utilized in the past, can be used as medium-pressure steam for heat retention or heating. It can be used as
Therefore, the amount of high-pressure steam consumed can be significantly reduced compared to the case where the system is kept warm or heated using high-pressure steam alone.

Furthermore, according to the present invention, even if the amount of low-pressure steam discharged from the steam drum fluctuates, the amount of medium-pressure steam necessary for keeping warm or heating can be always secured, and the amount of medium-pressure steam depends on the consumption amount. Since the pressure can be adjusted, it has the advantage of being able to provide just the right amount of medium-pressure steam.

[Brief explanation of the drawing]

The drawing is a flow sheet showing one embodiment of the present invention. 1; Reactor, 2; Sulfur condenser, 3; Steam drum, 4
; sulfur tank; 5; sulfur pump; 6; sulfur storage tank;
7; Steam drum internal pressure control valve, 8; Check valve, 10; Ejector, 11; High pressure steam generation source, 12; First pressure regulating valve, 14
; Second pressure regulating valve, 16; Cooling water heater, 17; Relief valve, circle; Pressure transmitter.

Claims (1)

[Claims] 1. High pressure steam brought from a high pressure steam generation source is introduced into a first fluid inlet of the ejector through a first pressure regulating valve, and low pressure steam discharged from a steam drum of a sulfur recovery plant is introduced into a second fluid inlet of the ejector. medium-pressure steam is generated, and the high-pressure steam bypasses the ejector and is connected to the line leading to the outlet side of the ejector through a first pressure regulating valve.
．． A second pressure regulating valve that operates at a lower pressure of 5 kg/cm^2 is provided, and while the amount of intermediate pressure steam generated from the ejector is controlled by the first and second pressure regulating valves, the intermediate pressure steam is kept warm and/or
or a method of utilizing said low-pressure steam comprising circulating it to a sulfur recovery plant as heating steam.