Water seal control system for pressure of methanol vault storage tank

Abstract

A water seal control system for pressure of a methanol vault storage tank is connected with the methanol vault storage tank and comprises a water seal tank and a supporting frame, and the water seal tank is installed beside the methanol vault storage tank through the supporting frame. A methanol discharge pipe communicated with a nitrogen pipeline is introduced into one side of the top of the water seal tank, and a discharge pressure regulating valve is arranged in parallel and then is connected with a spray guide pipeline; a vertical flash gas discharge pipe is led out from the other side of the flash gas discharge pipe, and a desalted water pipe is led in the flash gas discharge pipe; an overflow pipe and a discharge pipe are led out of the upper part of the side surface of the water seal tank and then combined, and the absorption liquid is recycled to the underground tank and connected with a U-shaped pipe; a swinging head connecting transparent hose with a communicating valve is led out of the bottom of the water seal tank, and the hose head is arranged at the position flush with the highest liquid level of the water seal tank; and the split-range controller is respectively in telecommunication connection with the methanol vault storage tank, the low-pressure nitrogen valve and the discharge pressure regulating valve. The system can greatly reduce methanol volatilization loss, and has practical value and economic value for storage tank pressure control and safe and stable operation.

Description

Technical Field

[0001] The utility model belongs to the technical field of methanol storage, and in particular relates to a water seal control system for the pressure of a methanol dome storage tank. Background Art

[0002] Methanol vault storage tank is a nitrogen-sealed normal temperature and pressure storage tank. The tank pressure control is mainly achieved through nitrogen sealing and tank top breathing valve, and the pressure is generally controlled at 1.0-2.0KPa. Under normal circumstances, the methanol vault storage tank forms a nitrogen seal above the methanol liquid level in the tank by adding low-pressure nitrogen to prevent air from entering the tank and forming an explosive mixture with methanol volatile gas, ensuring the safety of the tank. At the same time, the tank controls the pressure through nitrogen sealing and tank top breathing valve to avoid negative pressure in the tank. Methanol storage tanks are affected by ambient temperature, methanol temperature, tank level rise and fall, and nitrogen sealing pressure. There is a situation of methanol volatilization loss in the tank, and the stability of tank pressure control is not high enough. When methanol is introduced into the tank, the temperature of methanol is generally 30-40℃. Even if the spray water system on the outer surface of the tank is put into use, the tank pressure is still high, even exceeding the high value of 2.3KPa. Methanol volatilization intensifies and is discharged into the atmosphere through the breathing valve, which not only pollutes the environment but also causes high methanol loss. Utility Model Content

[0003] In order to reduce the volatilization loss of methanol in the dome storage tank and realize the pressure control of the storage tank and safe and stable operation, the utility model proposes a water seal control system for the pressure of the methanol dome storage tank.

[0004] A water seal control system for the pressure of a methanol vault storage tank is connected to the methanol vault storage tank, characterized in that the system comprises a water seal tank and a support frame, the edge of the vault of the methanol vault storage tank is connected to a nitrogen pipeline with a low-pressure nitrogen valve, and a breathing valve is arranged at the highest point of the vault; the water seal tank is installed on the ground beside the methanol vault storage tank through the support frame; a methanol discharge pipe connected to the nitrogen pipeline is introduced into one side of the top of the water seal tank, and a discharge pressure regulating valve is arranged on the pipe line, a drainage pipe is connected to the pipe after the discharge pressure regulating valve, and a condensate discharge drainage valve is arranged; the methanol discharge pipe mouth enters 5 cm below the liquid level of the water seal tank; a vertical flash gas discharge pipe is led out from the other side of the top of the water seal tank, and the pipe mouth height is the same as the water seal tank top. The discharge heights of the breathing valves at the top of the methanol dome storage tank are consistent, and a desalted water pipe with a water replenishment valve is introduced at the upper position of the flash gas discharge pipe; an overflow pipe is led out from the upper side of the water seal tank, and a discharge pipe with a discharge valve is led out directly below the overflow pipe. The overflow pipe and the discharge pipe are connected in parallel to recover the absorbed liquid to the underground tank, and a parallel pipe discharge valve is set on the parallel pipe, and a U-shaped pipe is set behind the parallel pipe discharge valve; a swing head with a connecting valve is led out from the bottom of the water seal tank, and then a transparent hose is connected. The transparent hose is fixed on the outside of the water seal tank, and the pipe head is set at a position flush with the highest liquid level of the water seal tank; the split-range controller is respectively connected to the methanol dome storage tank, the low-pressure nitrogen valve and the discharge pressure regulating valve by telecommunications.

[0005] Furthermore, the position difference of the U-shaped tube is ≧250 mm.

[0006] Furthermore, the distance between the position where the discharge pipe is led out and the ground is not less than 200 cm.

[0007] The utility model has the beneficial effect that the desalted water in the water seal tank is used to spray and absorb the methanol gas volatilized from the methanol vault storage tank, and the liquid level in the water seal tank is used to control the pressure of the methanol vault storage tank. The pressure of the methanol vault storage tank is controlled by adjusting the low-pressure nitrogen flow and the methanol gas discharge through the split-range controller. It has the characteristics of stable control, can greatly reduce the loss of methanol volatilization, and has practical and economic value for the pressure control of the storage tank and safe and stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 The figure is a connection diagram of a water seal control system for the pressure of a methanol dome storage tank.

[0009] Among them: 1- methanol vault storage tank, 2- water seal tank, 3- water supply valve, 4- flash steam discharge pipe, 5- transparent hose, 6- discharge pressure regulating valve, 7- low-pressure nitrogen valve, 8- breathing valve, 9- parallel pipe discharge valve, 10- connecting valve, 11- support frame, 12- discharge valve, 13- overflow pipe, 14- split-range controller, 15- condensate discharge guide valve. DETAILED DESCRIPTION

[0010] Example 1: A water seal control system for methanol vault storage tank pressure, connected to a methanol vault storage tank 1, comprising a water seal tank 2 and a support frame 11. The edge of the vault of the methanol vault storage tank 1 is connected to a nitrogen pipeline with a low-pressure nitrogen valve 7, the specification of the nitrogen pipeline is DN100; a breathing valve 8 is set at the highest point of the vault. A cylindrical water seal tank 2 is manufactured, with a height of 300mm and a diameter of 450mm.

[0011] The water seal tank 2 is installed on the ground beside the methanol dome storage tank 1 through a support frame 11; a methanol discharge pipe connected to the nitrogen pipeline is introduced on one side of the top of the water seal tank 2, and a discharge pressure regulating valve 6 is set on the pipe, and a drainage pipe is connected to the pipe after the discharge pressure regulating valve 6 and a condensate discharge drainage valve 15 is set; the methanol discharge pipe mouth enters 5cm below the liquid level of the water seal tank 2. A vertical flash gas discharge pipe 4 is led out from the other side of the top of the water seal tank 2. The pipe specification is DN100, and the pipe mouth height is consistent with the discharge height of the breathing valve 8 at the top of the methanol dome storage tank; a desalted water pipe with a water replenishment valve 3 is introduced at the upper position of the flash gas discharge pipe 4, and the desalted water pipe specification is DN10. An overflow pipe 13 is led out from the upper side of the water seal tank 2. The mouth of the overflow pipe 13 is 20 cm away from the bottom of the water seal tank 2. A discharge pipe with a discharge valve 12 is led out 3 cm below the overflow pipe 13. The distance between the discharge pipe and the ground is 200 cm. The specifications of the discharge pipe and the overflow pipe 13 are both DN20. The overflow pipe 13 and the discharge pipe are connected in parallel to recover the absorption liquid to the underground tank, and a parallel pipe discharge valve 9 is set on the parallel pipe. A U-shaped pipe with a potential difference of 250 mm is set behind the parallel pipe discharge valve 9 to prevent the flash gas in the underground tank from flowing back to the water seal tank 2. A swing head with a DN20 connecting valve 10 is led out from the bottom of the water seal tank 2, and then a transparent hose 5 is connected. The transparent hose is fixed on the outside of the water seal tank 2, and the pipe head is set at a position flush with the highest liquid level of the water seal tank 2 to observe the liquid level in the water seal tank 2.

[0012] The split-range controller 14 is respectively connected to the methanol dome storage tank 1, the low-pressure nitrogen valve 7 and the discharge pressure regulating valve 6 by telecommunication. After the device is started normally, the connecting valve 10 and the water supply valve 3 are opened on site to spray desalted water into the water seal tank 2. It is observed on site that the liquid level of the transparent hose 5 has reached the pipe mouth and the water seal tank 2 is filled with the normal liquid level. The split-range controller 14 is set to "CAS", the SP value is set to 1.5KPa, and the pressure PI02 of the methanol dome storage tank 1 is adjusted in series with the low-pressure nitrogen valve 7 and the discharge pressure regulating valve 6 double valve. When the opening OP value of the discharge pressure regulating valve 6 is getting larger and larger, it means that methanol condensate is accumulated at the low point of the methanol discharge pipe from the methanol dome storage tank 1 to the water seal tank 2 on site. The condensate discharge guide valve 15 needs to be opened on site to drain the condensate and reduce the resistance. In order to prevent the abnormal pressure of the methanol dome storage tank 1, when the pressure PI02 value of the methanol dome storage tank 1 reaches the designed high and low limits, the alarm reminds the operator to check and deal with it.

Claims

1. A water seal control system for the pressure of a methanol vault storage tank, connected to the methanol vault storage tank, characterized in that The system includes a water seal tank and a support frame. The edge of the arch of the methanol arch storage tank is connected to a nitrogen pipeline with a low-pressure nitrogen valve, and a breathing valve is set at the highest point of the arch; the water seal tank is installed on the ground next to the methanol arch storage tank through the support frame; a methanol discharge pipe connected to the nitrogen pipeline is introduced on one side of the top of the water seal tank, and a discharge pressure regulating valve is set on the pipe, a drainage pipe is connected to the pipe after the discharge pressure regulating valve, and a condensate discharge drainage valve is set; the methanol discharge pipe mouth enters 5cm below the liquid level of the water seal tank; a vertical flash gas discharge pipe is led out from the other side of the top of the water seal tank, and its pipe mouth height is the same as the discharge port height of the breathing valve on the top of the methanol arch storage tank The degree of water is consistent, and a desalted water pipe with a water replenishment valve is introduced into the upper position of the flash gas discharge pipe; an overflow pipe is led out from the upper part of the side of the water seal tank, and a discharge pipe with a discharge valve is led out from just below the overflow pipe. The overflow pipe and the discharge pipe are connected to the ground tank after being connected, and a parallel pipe discharge valve is set on the parallel pipe, and a U-shaped pipe is set behind the parallel pipe discharge valve; a swing head with a connecting valve is led out from the bottom of the water seal tank, and then a transparent hose is connected, the transparent hose is fixed on the outside of the water seal tank, and the pipe head is set at a position flush with the highest liquid level of the water seal tank; the split-range controller is respectively connected to the methanol vault storage tank, the low-pressure nitrogen valve and the discharge pressure regulating valve by telecommunications.

2. A water seal control system for methanol dome storage tank pressure as claimed in claim 1, characterized in that The position difference of the U-shaped tube is ≧250 mm.

3. A water seal control system for methanol dome storage tank pressure as claimed in claim 1, characterized in that The distance between the discharge pipe and the ground is not less than 200 cm.

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