A storage tank VOCs gas collection system

Abstract

The utility model discloses a kind of VOCs gas collection systems of storage tank, including storage tank, air inlet buffer tank, frequency conversion fan;Storage tank top is connected nitrogen gas source by nitrogen gas inlet pipeline;Storage tank top is installed breather valve by tee, tee is connected air inlet buffer tank by VOCs gas collection pipeline;The top outlet of air inlet buffer tank is connected gas output pipeline, and frequency conversion fan is installed on gas output pipeline;PT01 pressure transmitter is installed on the top of storage tank, PV01 regulating valve is installed on nitrogen gas inlet pipeline, PV02 regulating valve is installed on VOCs gas collection pipeline, and PT01 pressure transmitter and PV01 regulating valve, PV02 regulating valve constitute PICA01 control loop;One or more pressure transmitters are installed on the top of air inlet buffer tank, and frequency converter of frequency conversion fan constitutes PICA02 control loop with pressure transmitter.The utility model can be applied to various VOCs gas storage tank, and has good practical application value.

Description

Technical Field

[0001] This utility model belongs to the field of chemical technology and relates to VOCs gas, specifically a VOCs gas collection system for storage tanks. Background Technology

[0002] The development of VOCs (volatile organic compounds) collection technology for storage tanks is an important issue in the environmental protection field of the petrochemical industry. VOCs in storage tanks mainly originate from the volatilization of crude oil, gasoline, naphtha, and other petroleum products within the storage tanks of production units. These waste gases not only contain flammable and explosive hydrocarbon gases but may also contain toxic and harmful substances, posing a threat to the environment and human health.

[0003] With the increasing severity of air pollution, volatile organic compounds (VOCs), as important precursors to ozone (O3) formation, have received high attention from the Ministry of Ecology and Environment. To implement the national decisions and plans on air pollution prevention and control, the Ministry of Environmental Protection has introduced a series of measures and requirements to strengthen VOCs control.

[0004] Due to factors such as tank operation and temperature and pressure changes, VOC emissions may exhibit intermittent characteristics, posing a considerable challenge to VOC gas collection. Utility Model Content

[0005] Currently, the process of extracting VOCs gas alters the gas pressure and temperature within the tank, causing more VOCs to evaporate from the liquid. Over time, this inevitably leads to increased material consumption within the storage tank, resulting in higher production costs. To overcome the problem of continuous VOCs gas extraction from the storage tank by the blower, which promotes VOCs volatilization, this invention provides a VOCs gas collection system for storage tanks.

[0006] This utility model is achieved using the following technical solution:

[0007] A VOCs gas collection system for a storage tank includes a storage tank, an inlet buffer tank, and a variable frequency fan. The top of the storage tank is connected to a nitrogen source via a nitrogen inlet pipeline. A breather valve is installed on the top of the storage tank via a T-junction, which is connected to the inlet buffer tank via a gas collection pipeline. The top outlet of the inlet buffer tank is connected to a gas outlet pipeline, and the variable frequency fan is installed on the gas outlet pipeline. A PT01 pressure transmitter is installed on the top of the storage tank. A PV01 regulating valve is installed on the nitrogen inlet pipeline, and a PV02 regulating valve is installed on the VOCs gas collection pipeline. The PT01 pressure transmitter, the PV01 regulating valve, and the PV02 regulating valve constitute a PICA01 control loop. One or more pressure transmitters are installed on the top of the inlet buffer tank, and these pressure transmitters, together with the frequency converter of the variable frequency fan, constitute a PICA02 control loop.

[0008] In operation, based on the actual conditions of various tank types in the tank farm, such as fixed tanks and floating roof tanks, a connecting tee is installed at the lower end of the breather valve. The VOCs gas recovery pipeline is directly led out from the tee and connected to the main oil and gas collection pipeline of the tank farm. The PV01 and PV02 pressure regulating valves, located at the top of the tank, are controlled by a PT01 pressure transmitter, thereby controlling the amount of nitrogen replenishment and VOCs gas exhaled from the tank. The VOCs gas enters the intake buffer tank, and a variable frequency fan is installed at the outlet of the intake buffer tank. The variable frequency fan is interlocked and controlled according to the pressure at the top of the intake buffer tank, enabling automatic start and stop. With this VOCs collection method, the fan does not directly extract VOCs gas from the tank, thus avoiding pressure and temperature changes within the tank and preventing an increase in the amount of volatilization, reducing material volatilization and saving production costs.

[0009] Preferably, pressure transmitters PT02, PT03, and PT04 are installed at the same pressure measuring point on the top of the air intake buffer tank. These pressure transmitters, along with the variable frequency fan, form a PICA02 control loop. In application, the pressure at the top of the air intake buffer tank (collected from pressure transmitters PT02, PT03, and PT04) is selected from two of the three, enabling the variable frequency fan to automatically start and stop.

[0010] In a further preferred embodiment, a return pipe is provided between the inlet and outlet of the variable frequency fan, and a cooler is installed in the return pipe. The return pipe at the inlet and outlet of the fan facilitates stable inlet flow and ensures that the fan does not frequently start and stop.

[0011] More preferably, a flame arrester is installed on the VOCs gas collection pipeline, and valves are installed on both sides of the flame arrester on the VOCs gas collection pipeline. Adding a flame arrester to the collection pipeline entering the inlet buffer tank prevents the recovery device from affecting the safety of the storage tank, ensuring the safe and stable operation of the storage tank.

[0012] Preferably, a filter is installed on the gas output pipeline in front of the variable frequency fan. Flexible connections are provided on both sides of the gas output pipeline near the variable frequency fan to facilitate stable fan output.

[0013] Preferably, valves are installed on both sides of the PV01 regulating valve on the nitrogen inlet pipeline. A bypass backup / maintenance pipeline is also provided on the nitrogen inlet pipeline. This facilitates inspection and maintenance of the nitrogen inlet pipeline without shutting down the system.

[0014] This utility model is reasonably designed and can be applied to various VOCs gas storage tanks, and has great practical application value. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the present invention.

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram showing the structure of the present invention.

[0018] In the diagram: 1-Storage tank, 2-Inlet buffer tank, 3-Variable frequency fan, 4-Cooler, 5-Flame arrester, 6-Filter, 7-Nitrogen source, 8-Nitrogen inlet pipeline, 9-Bypass spare / maintenance pipeline, 10-VOCs gas collection pipeline, 11-Gas output pipeline, 12-Return pipeline, 13-Breathe valve, 14-PV01 regulating valve, 15-PV02 regulating valve, 16-PT01 pressure transmitter, 17-PT02 pressure transmitter, 18-PT03 pressure transmitter, 19-PT04 pressure transmitter, 20-Flexible connection, 21-Tee, 22-Valve. Detailed Implementation

[0019] To better understand the above-mentioned objectives, features, and advantages of this utility model, the solution of this utility model will be further described below. It should be noted that, unless otherwise specified, the embodiments of this utility model and the features thereof can be combined with each other.

[0020] In this description, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. It should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0021] Many specific details are set forth in the following description in order to provide a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the present invention, and not all embodiments.

[0022] The specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0023] A VOCs gas collection system for a storage tank includes a storage tank 1, an inlet buffer tank 2, a variable frequency fan 3, etc.

[0024] like Figure 1 As shown, the top of the storage tank 1 is connected to the nitrogen source 7 via a nitrogen inlet pipe 8; a breather valve 13 is installed on the top of the storage tank 1 via a three-way valve 21, and the three-way valve 21 is connected to the intake buffer tank 2 via a VOCs gas collection pipe 10; the top outlet of the intake buffer tank 2 is connected to the gas output pipe 11, and a variable frequency fan 3 is installed on the gas output pipe 11; a return pipe 12 is provided between the inlet and outlet of the variable frequency fan 3, and a cooler 4 is installed in the return pipe 12.

[0025] like Figure 1 As shown, a PT01 pressure transmitter 16 is installed on the top of the storage tank 1, a PV01 regulating valve 14 is installed on the nitrogen inlet pipeline 8, and a PV02 regulating valve 15 is installed on the VOCs gas collection pipeline 10. The PT01 pressure transmitter 16, the PV01 regulating valve 14, and the PV02 regulating valve 15 constitute the PICA01 control loop.

[0026] like Figure 1 As shown, one or more pressure transmitters are installed on the top of the air intake buffer tank 2. In specific implementation, PT02 pressure transmitter 17, PT03 pressure transmitter 18, and PT04 pressure transmitter 19 are installed at the same pressure measuring point on the top of the air intake buffer tank 2. The PT02 pressure transmitter 17, PT03 pressure transmitter 18, and PT04 pressure transmitter 19 together with the frequency converter of the variable frequency fan 3 form a PICA02 control loop.

[0027] like Figure 1 As shown, valves 22 are installed on both sides of the PV01 regulating valve 14 on the nitrogen inlet pipeline 8. A bypass spare / maintenance pipeline 9 is also provided on the nitrogen inlet pipeline 8.

[0028] like Figure 1 As shown, a flame arrester 5 is installed on the VOCs gas collection pipeline 10, and valves 22 are installed on both sides of the flame arrester 5.

[0029] like Figure 1 As shown, a filter 6 is installed on the gas output pipeline 11 in front of the variable frequency fan 3. Flexible connections 20 are provided on both sides of the gas output pipeline 11 and the variable frequency fan 3.

[0030] In specific implementation, based on the actual situation of the storage tanks 1, including fixed tanks and floating roof tanks in the tank farm, a connecting tee 21 is installed at the lower end of the breather valve 13. The VOCs gas collection pipeline 10 is directly led out from the tee 21 and connected to the tank farm's oil and gas collection main pipeline. The PT01 pressure transmitter 16 installed at the top of the storage tank controls the PV01 pressure regulating valve 14 and the PV02 pressure regulating valve 15, thereby controlling the amount of nitrogen replenishment and the amount of VOCs gas exhaled from the storage tank. The VOCs gas enters the intake buffer tank 2, and the intake buffer... A variable frequency fan 3 is installed at the outlet of the buffer tank 2. The variable frequency fan 3 is interlocked and controlled based on the top pressure of the intake buffer tank 2. The top pressure (collected from PT02 pressure transmitter 17, PT03 pressure transmitter 18, and PT04 pressure transmitter 19) uses a three-to-two selection method, enabling automatic start and stop of the variable frequency fan 3. A return pipeline 12 (with a cooler 4 connected in series in the return pipeline 12) is installed at the inlet and outlet of the variable frequency fan 3 to stabilize the inlet flow and ensure that the variable frequency fan does not frequently start and stop. Additionally, flexible connections 20 are provided on both sides of the variable frequency fan 3 to stabilize gas output. Simultaneously, a flame arrester 5 is added to the VOCs gas collection pipeline 10 entering the intake buffer tank 2 to prevent the recovery device from affecting the safety of the storage tank 1, ensuring the safe and stable operation of the storage tank 1. Through this VOCs collection method, the fan does not directly extract VOCs gas from the storage tank 1, thus avoiding pressure and temperature changes within the storage tank 1 and preventing an increase in the amount of volatilization within the storage tank 1. This also reduces material volatilization and saves production costs.

[0031] The above description is merely a specific embodiment of this utility model, enabling those skilled in the art to understand or implement it. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and all should be covered by the protection scope of the claims.

Claims

1. A VOCs gas collection system for storage tanks, characterized in that: Includes storage tank (1), air intake buffer tank (2), and variable frequency fan (3); The top of the storage tank (1) is connected to a nitrogen source (7) via a nitrogen inlet pipe (8); a breather valve (13) is installed on the top of the storage tank (1) via a tee (21), and the tee (21) is connected to the intake buffer tank (2) via a VOCs gas collection pipe (10); the top outlet of the intake buffer tank (2) is connected to a gas output pipe (11), and a variable frequency fan (3) is installed on the gas output pipe (11); A PT01 pressure transmitter (16) is installed on the top of the storage tank (1), a PV01 regulating valve (14) is installed on the nitrogen inlet pipeline (8), and a PV02 regulating valve (15) is installed on the VOCs gas collection pipeline (10). The PT01 pressure transmitter (16), the PV01 regulating valve (14), and the PV02 regulating valve (15) constitute a PICA01 control loop. One or more pressure transmitters are installed on the top of the air intake buffer tank (2), and the pressure transmitters and the frequency converter of the variable frequency fan (3) form a PICA02 control loop.

2. The VOCs gas collection system for a storage tank according to claim 1, characterized in that: A PT02 pressure transmitter (17), a PT03 pressure transmitter (18), and a PT04 pressure transmitter (19) are installed at the same pressure measuring point on the top of the air intake buffer tank (2). The PT02 pressure transmitter (17), the PT03 pressure transmitter (18), and the PT04 pressure transmitter (19) together with the variable frequency fan (3) form a PICA02 control loop.

3. A VOCs gas collection system for a storage tank according to claim 1 or 2, characterized in that: A return pipe (12) is provided between the inlet and outlet of the variable frequency fan (3), and a cooler (4) is installed in the return pipe (12).

4. The VOCs gas collection system for a storage tank according to claim 3, characterized in that: A flame arrester (5) is installed on the VOCs gas collection pipeline (10).

5. A VOCs gas collection system for a storage tank according to claim 4, characterized in that: Valves (22) are installed on both sides of the flame arrester (5) on the VOCs gas collection pipeline (10).

6. A VOCs gas collection system for a storage tank according to claim 5, characterized in that: A filter (6) is installed on the gas output pipeline (11) in front of the variable frequency fan (3).

7. A VOCs gas collection system for a storage tank according to claim 6, characterized in that: The gas output pipeline (11) is provided with flexible connections (20) on both sides of the variable frequency fan (3).

8. A VOCs gas collection system for a storage tank according to claim 7, characterized in that: Valves (22) are installed on both sides of the PV01 regulating valve (14) on the nitrogen inlet pipeline (8).

9. A VOCs gas collection system for a storage tank according to claim 8, characterized in that: A bypass spare / maintenance pipeline (9) is also provided on the nitrogen inlet pipeline (8).

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