CN201568738U - Expander seal gas recycle device - Google Patents

Abstract

The expander sealing gas recycling device is applied to the recycling of waste gas in the natural gas cryogenic process. A sealing gas emptying pipeline connected with the turbine oil storage tank is connected with an inlet of the liquid phase separator; the upper part of the liquid phase separator is provided with a natural gas outlet, a constant pressure air release valve is connected on a natural gas outlet pipeline of the liquid phase separator, and an emptying pipeline is connected on the constant pressure air release valve; an external gas supply pipeline is connected to the pipeline between the natural gas outlet of the liquid phase separator and the constant pressure air release valve, and the external gas supply pipeline is connected with the original gas supply pipeline. The effect is as follows: the method can recycle the sealing natural gas of the turboexpander. Under the condition of ensuring the normal operation of the expansion machine, the natural gas for sealing is recovered, the energy-saving and emission-reducing effects are obvious, and the economic benefit is obvious. The defect that natural gas for sealing only by operating the expansion machine needs to enter a working cavity under pressure and then is released to the air in the prior art is overcome.

Description

An expander sealing gas recovery and utilization device

technical field

The utility model relates to the technical field of natural gas processing, in particular to the reuse of waste gas in the cryogenic process of natural gas, and is a recycling device for seal gas of an expander.

Background technique

The expander is one of the main equipment for natural gas cryogenics. Due to its special mechanical structure, it is required that all the gas entering the expander can be expanded through the deflector and the working wheel to generate cooling capacity. However, since the working wheel is a high-speed rotating part and the casing is a stationary part, low-temperature gas may leak through the gap of the casing. This will reduce the total cooling capacity of the expander and increase the cooling loss. In addition, the leakage of cooling capacity may also freeze the bearing lubricating oil and cause mechanical failure. Therefore a reliable seal must be used.

When the gas flows through the sealing gap, the pressure gradually decreases. The amount of leakage depends on the size of the sealing gap and the pressure difference between the two sealing spaces. If the sealing space is more, or the pressure on the outside is higher, the pressure difference on both sides of each sealing gap will be smaller, and the leakage will also be reduced. Therefore, the sealing device is divided into two sections, and a sealing gas with a pressure slightly higher than the surrounding pressure is introduced in the middle, and the pressure can be 0.05-0.10MPa (gauge pressure). In this way, on the one hand, the leakage of low-temperature gas can be reduced and the cold loss can be reduced, and at the same time, the lubricating oil of the bearing can be prevented from penetrating into the seal and entering the expander. At present, the turboexpander used in the air separation unit generally needs to pass through the sealing gas with pressure. In order to prevent the lubricating oil from entering the expander, the pressure sealing gas should be supplied before starting the expander oil pump. When shutting down, it is necessary to stop the pressure sealing gas after the oil pump stops running. As long as the expander is running, the natural gas used for sealing will enter the working chamber under pressure, and then be released into the air. Taking an expander with a daily processing capacity of 100,000 cubic meters as an example: the leaked sealed natural gas is as high as 1,000 cubic meters per day.

Utility model content

The purpose of the utility model is to provide a device for recovering and utilizing the sealing gas of an expander, which can recover and utilize the natural gas used for sealing under the condition of ensuring the normal operation of the expander.

The technical solution adopted in the utility model is: the expander sealing gas recovery and utilization device is mainly composed of an expander, a turbine oil storage tank, a liquid phase separator, and a constant pressure release valve. The expander is connected with a sealed gas source pipeline, sealed The gas source pipeline provides the gas source for the expander. The expander has a pipeline connected to the turbine oil storage tank, and the exhaust port of the turbine oil storage tank is connected to a sealing gas venting pipeline. It is characterized in that: the sealing gas discharge pipeline connected to the turbine oil storage tank is connected to the inlet of the liquid phase separator. There is a natural gas outlet on the upper part of the liquid phase separator, a constant pressure release valve is connected to the natural gas outlet pipeline of the liquid phase separator, and a venting pipeline is connected to the constant pressure release valve. An external gas supply pipeline is connected to the pipeline between the natural gas outlet of the liquid phase separator and the constant pressure release valve, and the external gas supply pipeline is connected to the original gas supply pipeline.

The annual consumption of sealing gas is more than 400,000 cubic meters, while the annual gas consumption of water jacket furnace and regeneration furnace is about 500,000 cubic meters. Under the condition of ensuring the normal operation of the expansion agent, use the deactivated vertical separator to connect the discharged natural gas containing turbine oil to the separator. A constant pressure release valve is installed on the separator, and the set pressure is 0.18MPa. After separation and deoiling, the water jacket furnace and the regenerative heating furnace are used as fuel gas. The working pressure of the fuel gas is 0.1-0.16MPa. The separated sealed natural gas is connected to the outlet port of the fuel gas pressure regulating valve (the pressure regulating valve outlet pressure is 0.14MPa), when the fuel gas consumption is higher than the sealing gas, the pressure regulating valve will automatically supplement the gas supply; otherwise, when the sealing gas pressure exceeds 1.8MPa, the constant pressure valve will open and vent to the outside, ensuring the stable operation of the expander and eliminating air pollution .

Beneficial effects of the utility model: the utility model expander seal gas recycling device can recycle the turbo expander seal gas. Under the condition of ensuring the normal operation of the expander, the natural gas used for sealing is recovered, the effect of energy saving and emission reduction is obvious, and the economic benefit is remarkable. It overcomes the original problem that as long as the expander is running, the natural gas used for sealing must enter the working chamber with pressure and then release it to the air.

Description of drawings

Figure 1 is a schematic diagram of the connection structure of the expansion machine sealing gas recovery and utilization device of the utility model.

In the figure, 1. Expander, 2. Turbine oil storage tank, 3. Sealed gas source, 4. Sealed gas vent, 5. Liquid phase separator, 6. Separator inlet, 7. Constant pressure release valve, 8 . Vent pipeline, 9. Pressure gauge, 10. Gas pressure regulating valve, 11. Gas liquid gas bag, 12. Water jacket furnace, 13. Regeneration furnace.

Detailed ways

Embodiment 1: Taking a set of expander sealing gas recovery and utilization device as an example, the utility model is further described in detail.

See Figure 1. The utility model expander sealing gas recycling device is composed of an expander 1, a turbine oil storage tank 2, a liquid phase separator 5, a constant pressure release valve 7, a pressure gauge 9, a gas pressure regulating valve 10, and a gas liquid gas bag 11. It is composed of water jacket furnace 12 and regeneration furnace 13.

The expander 1 is connected with a sealed gas source pipeline 3, and the sealed gas source pipeline 3 provides a gas source for the expander. The expander 1 has a pipeline connected to the turbine oil storage tank 2, and the exhaust port of the turbine oil storage tank 2 is connected to a sealing gas venting pipeline 4.

The seal gas discharge line 4 connected to the turbine oil storage tank 2 is connected to the inlet of the liquid phase separator 5 . There is a natural gas outlet on the upper part of the liquid phase separator 5, and a constant pressure release valve 7 is connected to the natural gas outlet pipeline of the liquid phase separator 5, and a venting pipeline 8 is connected to the constant pressure release valve 7.

An external gas supply pipeline is connected to the pipeline between the natural gas outlet of the liquid phase separator 5 and the constant pressure purge valve 7, and the external gas supply pipeline is connected to the original gas supply pipeline.

The original gas supply pipeline is connected with the water jacket furnace 12 and the regeneration furnace 13 of the useful gas equipment. The original gas supply pipeline is connected with gas supply equipment, the gas supply equipment is gas liquid gas bag 11, the gas supply pipe is connected with gas pressure regulating valve 10, the other end of gas pressure regulating valve 10 is connected to the gas supply pipeline A pressure gauge 9 is fixed on it.

Claims (1)

1. An expander sealing gas recycling device, mainly composed of an expander (1), a turbine oil storage tank (2), a liquid phase separator (5), a constant pressure release valve (7), the expander ( 1) Connected to the sealing gas source pipeline (3), the expander (1) has a pipeline connected to the turbine oil storage tank (2), and the exhaust port of the turbine oil storage tank (2) is connected to the sealing gas venting pipeline (4) ; It is characterized in that: the sealing gas venting pipeline (4) connected to the turbine oil storage tank (2) is connected with the inlet of the liquid phase separator (5); there is a natural gas outlet at the top of the liquid phase separator (5), A constant pressure release valve (7) is connected to the natural gas outlet pipeline of the phase separator (5), and a venting pipeline (8) is connected to the constant pressure release valve (7); The pipeline between the pressure and release valves (7) is connected with an external gas supply pipeline, and the external gas supply pipeline is connected with the original gas supply pipeline.