Accurate sulfur injection system and method for propane dehydrogenation

Abstract

The invention discloses a precise sulfur injection system and method for propane dehydrogenation, and belongs to the technical field of propane dehydrogenation. The system comprises a sulfur injection tank, a plurality of small buffer tanks, a sulfur injection pump, a flow detection element, a remote liquid level meter and a control unit, dMDS is stored in the sulfur injection tank and supplemented into the small buffer tanks through regulating valves, each small buffer tank is provided with a remote liquid level meter, the bottom of each small buffer tank is connected with the sulfur injection pump, the discharge end of each sulfur injection pump is connected with the reaction unit through a flow detection element, and the control unit regulates and controls according to liquid level and flow data. The method comprises the steps that DMDS is supplemented into the small buffer tank from the sulfur injection tank, the sulfur injection pump pumps DMDS to the reaction unit, the sulfur injection amount is accurately controlled through the combination of the liquid level descending rate of the small buffer tank and flow detection, and meanwhile the pump state is monitored. The problems that metering is not stable and faults are difficult to find in time in a traditional sulfur injection process are solved, accurate sulfur injection control is achieved, long-period operation of a propane dehydrogenation device is guaranteed, and remarkable practicability and economical efficiency are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of propane dehydrogenation, in particular to a precise sulfur injection system and method for propane dehydrogenation. BACKGROUND

[0002] In a propane dehydrogenation device, sulfur injection operation is crucial for long-term operation of the device: sulfur is not only a poison for the catalyst, but also can effectively inhibit the coking of the inner wall and internal parts of the reaction vessel, thereby improving product yield, reducing the risk of plugging, and prolonging the operation cycle of the device.

[0003] However, the traditional sulfur injection process (such as the "sulfur injection original process") has obvious defects: the sulfur injection tank directly feeds the reaction unit through a sulfur injection pump, and the sulfur injection amount depends on the outlet flow meter, but the outlet flow meter of the sulfur injection pump has large instantaneous value fluctuations and poor measurement stability; and the process lacks a buffer and monitoring link, so pump failures are difficult to detect in time, which can lead to uncontrolled sulfur injection amount and affect the performance of the catalyst, thereby shortening the operation cycle of the device. SUMMARY

[0004] The purpose of the present application is to provide a precise sulfur injection system and method for propane dehydrogenation, which solves the problems of "unstable measurement and difficult fault monitoring" in the traditional sulfur injection process, realizes precise control of the sulfur injection amount, and ensures long-term operation of the propane dehydrogenation device.

[0005] To achieve the above purpose, the present application realizes the following technical solutions:

[0006] A precise sulfur injection system for propane dehydrogenation, comprising a sulfur injection tank, a plurality of buffer small tanks, a sulfur injection pump, a flow detection element, a remote liquid level meter, and a control unit;

[0007] The sulfur injection tank is used to store DMDS, and the sulfur injection tank is connected with a feed pipe, which comprises a pipe for supplementing DMDS and a pipe for introducing nitrogen;

[0008] The discharge end of the sulfur injection tank is connected to each of the buffer small tanks through a pipe provided with an adjusting valve, so as to supplement the DMDS in the sulfur injection tank to each buffer small tank;

[0009] Each of the buffer small tanks is provided with the remote liquid level meter, which is used to detect the liquid level in the corresponding buffer small tank;

[0010] The bottom of each of the buffer small tanks is connected to the corresponding sulfur injection pump through a pipe, and the discharge end of the sulfur injection pump is connected to the reaction unit of the propane dehydrogenation device through a pipe provided with the flow detection element;

[0011] The remote liquid level meter and the flow detection element are in signal connection with the control unit, and the control unit is used for regulating the sulfur injection process according to the liquid level change and the flow detection data.

[0012] Further, the sulfur injection pump is a volumetric pump.

[0013] Further, the number of the buffer tanks is four, and four sulfur injection pumps are connected correspondingly, and the discharge ends of the four sulfur injection pumps are connected to four propane dehydrogenation reaction units.

[0014] A precise sulfur injection method for propane dehydrogenation, which adopts the precise sulfur injection system in any one of claims 1-3, comprises the following steps:

[0015] Step 1: DMDS is stored in the sulfur injection tank, and the DMDS is supplemented to each buffer tank through the regulating valve, so that each buffer tank maintains a preset liquid level;

[0016] Step 2: the sulfur injection pump is started to extract DMDS from the corresponding buffer tank and deliver it to the reaction unit, and the flow detection element is used to detect the delivery flow;

[0017] Step 3: the liquid level of the buffer tank is detected in real time by the remote liquid level meter, and based on the fixed cross-sectional area of the buffer tank, the consumption of DMDS in unit time is calculated from the liquid level drop rate;

[0018] Step 4: the control unit regulates the opening degree of the regulating valve to supplement DMDS to the buffer tank according to the liquid level change rate and the flow detection data, and monitors the running state of the sulfur injection pump, and if the liquid level drops abnormally, a fault warning and processing are performed.

[0019] Compared with the prior art, the beneficial effects of the present application are as follows:

[0020] 1. Precise control of sulfur injection amount: through the remote liquid level meter of the buffer tank, combined with the fixed cross-sectional area of the tank, the sulfur injection amount is accurately calculated from the liquid level drop rate, which makes up for the instability of the volumetric pump outlet flow meter.

[0021] 2. Enhanced fault monitoring capability: the buffer tank can timely find the fault of the sulfur injection pump or pipeline through the liquid level drop amplitude, and reduce the influence of misoperation on sulfur injection.

[0022] 3. Ensure long-period operation of the device: precise sulfur injection can stabilize the catalyst performance, inhibit coking in the non-catalyst area, and prolong the operation period of the propane dehydrogenation device. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a flow diagram of the propane dehydrogenation sulfur injection system of the present application. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] In the description of the embodiments of the present invention, it should be noted that if terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first," "second," and "third" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0026] Furthermore, the use of terms such as "horizontal," "vertical," and "sag" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0027] In the description of the embodiments of the present invention, "multiple" means at least two.

[0028] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0029] Example:

[0030] like Figure 1 As shown, a precision sulfur injection system for propane dehydrogenation according to the present invention includes a sulfur injection tank, multiple buffer tanks, a sulfur injection pump, a flow detection element, a remote level gauge and a control unit.

[0031] The sulfur injection tank is used for storing dimethyl disulfide (DMDS), and a feed pipeline is connected to the sulfur injection tank, the feed pipeline including a pipeline for supplementing DMDS and a pipeline for passing nitrogen gas (ensuring the stability of the pressure and medium in the tank);

[0032] The discharge end of the sulfur injection tank is connected to each buffer tank through a pipeline provided with an adjusting valve, so as to supplement DMDS in the sulfur injection tank to each buffer tank;

[0033] Each buffer tank is provided with the remote liquid level meter for detecting the liquid level in the corresponding buffer tank in real time;

[0034] The tank bottom of each buffer tank is connected to the corresponding sulfur injection pump through a pipeline, and the discharge end of the sulfur injection pump is connected to a reaction unit for propane dehydrogenation through a pipeline provided with the flow detection element;

[0035] The remote liquid level meter and the flow detection element are signal-connected to the control unit, and the control unit is used for regulating the opening degree of the adjusting valve to supplement DMDS and monitoring the running state of the sulfur injection pump according to the liquid level change and flow detection data.

[0036] A precise sulfur injection method for propane dehydrogenation, using the above-mentioned precise sulfur injection system, includes the following steps:

[0037] DMDS supplementing and buffering: DMDS is stored in the sulfur injection tank, and DMDS is supplemented to each buffer tank through the adjusting valve, so that each buffer tank maintains a preset liquid level;

[0038] Sulfur injection and flow detection: the sulfur injection pump is started to extract DMDS from the corresponding buffer tank and deliver it to the reaction unit, and the flow detection element is used to detect the delivery flow in real time;

[0039] Liquid level monitoring and sulfur injection amount calculation: the liquid level of the buffer tank is detected in real time by the remote liquid level meter, and since the cross-sectional area of the buffer tank is fixed, the consumption of DMDS in unit time (i.e. the amount of sulfur injection into the reaction unit) is calculated from the liquid level drop rate;

[0040] Regulation and fault warning: the control unit regulates the opening degree of the adjusting valve to supplement DMDS to the buffer tank according to the liquid level change rate and flow detection data; at the same time, if the liquid level drop rate is abnormal (such as stagnation, too fast / slow), it is judged that there is a fault in the sulfur injection pump or pipeline, and timely warning and treatment are performed.

[0041] In specific implementation:

[0042] In combination Figure 1 , the sulfur injection tank receives DMDS from the tank unloading device, and the nitrogen gas pipeline controlled by PCV-1 and PCV-2 ensures the stability of the pressure and DMDS in the tank;

[0043] The sulfur injection tank distributes DMDS to multiple buffer tanks (four buffer tanks in this embodiment, each equipped with a remote liquid level meter) through a regulating valve; each buffer tank corresponds to a sulfur injection pump (P-1 to P-4), which delivers DMDS to different reaction units, and FI-1 to FI-4 on the delivery pipeline detect the flow rate in real time.

[0044] Since the cross-sectional area of the buffer tank is fixed, the ratio of the volume change to the time of the liquid level drop is the sulfur injection amount per unit time, which can be accurately calculated through real-time data of the remote liquid level meter, making up for the defects of the volume pump outlet flow meter, such as "large instantaneous value fluctuation and unstable metering"; at the same time, the buffer tank plays a "buffering and monitoring" role: if the sulfur injection pump fails, the liquid level drop rate of the corresponding buffer tank will be abnormal (such as stagnation or sudden change in rate), which facilitates timely detection of pump failure, reduces the impact of misoperation on sulfur injection accuracy, ultimately ensures the accuracy of sulfur injection, maintains catalyst performance, and prolongs the operation cycle of the device.

[0045] The above describes the present application and its embodiments, which are not limited, and the drawings only show one of the embodiments of the present application, and the actual structure is not limited thereto. In summary, if a person of ordinary skill in the art is inspired thereby, without departing from the spirit of the present application, similar structural modes and embodiments can be designed without creativity, which should all belong to the protection scope of the present application.

Claims

1. A precise sulfur injection system for propane dehydrogenation, characterized in that: comprising a sulfur injection tank, a plurality of buffer tanks, a sulfur injection pump, a flow detection element, a remote liquid level meter and a control unit; the sulfur injection tank is used to store DMDS, and the sulfur injection tank is connected with a feed pipe, the feed pipe comprises a pipe for supplementing DMDS and a pipe for passing nitrogen; the discharge end of the sulfur injection tank is connected to each of the buffer tanks through a pipe provided with an adjusting valve, so as to supplement the DMDS in the sulfur injection tank to each buffer tank; each of the buffer tanks is provided with the remote liquid level meter, which is used to detect the liquid level in the corresponding buffer tank; the bottom of each of the buffer tanks is connected to the corresponding sulfur injection pump through a pipe, and the discharge end of the sulfur injection pump is connected to a reaction unit for propane dehydrogenation through a pipe provided with the flow detection element; the remote liquid level meter and the flow detection element are signal connected with the control unit, and the control unit is used to control the sulfur injection process according to the liquid level change and the flow detection data. The sulfur injection pump is a volumetric pump. The number of buffer tanks is four, corresponding to four sulfur injection pumps, and the discharge ends of the four sulfur injection pumps are respectively connected to four reaction units for propane dehydrogenation. The precise sulfur injection system according to any one of claims 1-3 comprises the following steps: Step 1: store DMDS in the sulfur injection tank, and supplement DMDS to each buffer tank through the adjusting valve to keep each buffer tank at a preset liquid level; Step 2: start the sulfur injection pump, extract DMDS from the corresponding buffer tank and deliver it to the reaction unit, and detect the delivery flow rate using the flow detection element; Step 3: detect the liquid level of the buffer tank in real time through the remote liquid level meter, and based on the cross-sectional area of the buffer tank, calculate the consumption of DMDS per unit time from the liquid level drop rate; 2. A precision sulfur injection system for dehydrogenation of propane as claimed in claim 1, wherein: Step 4: the control unit adjusts the opening of the adjusting valve to supplement DMDS to the buffer tank according to the liquid level change rate and the flow detection data, and monitors the operating state of the sulfur injection pump, and if the liquid level drops abnormally, it will give a fault warning and treatment.

3. The precise sulfur injection system for dehydrogenation of propane according to claim 1, wherein: ​ 4. A precision sulfur injection method for propane dehydrogenation, characterized by, ​ ​ ​ ​ ​

Images