Regenerated gas drying system

Abstract

The utility model discloses a regenerated gas drying system which is characterized by comprising a cooling water heat exchanger, a high-pressure steam heat exchanger, a drying unit, a regenerated gas outlet header pipe and a heat back-blowing line, the drying unit comprises a hot branch pipeline, a cold branch pipeline, a regeneration dryer, an inlet line of the drying unit and an outlet line of the drying unit; an outlet pipeline of the cooling water heat exchanger is connected to a cold branch pipeline; an outlet pipeline of the high-pressure steam heat exchanger is connected to a heat branch pipeline; and the hot branch pipeline and the cold branch pipeline are respectively connected to an inlet line of the drying unit. The condensate at the regeneration outlet of the dryer is obviously reduced or does not exist, so that the effect of reducing the accumulated liquid is achieved, the phenomenon that the accumulated liquid at the regeneration gas outlet flows back to the dryer is avoided, the condition that a subsequent system is frozen and blocked is solved, and the stable operation of the device is ensured.

Description

Technical Field

[0001] The utility model relates to a method for treating liquid accumulation in the outlet pipeline of regeneration gas, in particular to a regeneration gas drying system. Background Art

[0002] In the prior art, a molecular sieve in an ethylene plant dryer adsorbs moisture under low temperature and high pressure to remove moisture from cracked gas, and desorbs and releases moisture under high temperature and low pressure to remove moisture from the molecular sieve. After the normal dryer operates for a certain period, the molecular sieve becomes saturated with water absorption and needs to be regenerated. The steps for regenerating the molecular sieve to desorb and release moisture are as follows: put into parallel operation, cut out, relieve pressure, cold blow, drain liquid, raise temperature, keep constant temperature, lower temperature, and pressurize for standby.

[0003] Because there is a connection at the lowest point at the intersection of the regeneration gas outlet branch pipe and the regeneration gas outlet main pipe in the ethylene plant dryer, there is a design defect. Therefore, when the dryer is dehydrated and regenerated, liquid accumulation is likely to form at other regeneration gas outlet pipelines. When the regeneration gas outlet valve is opened, the accumulated liquid will flow back into the dryer, causing subsequent system freeze plugging and affecting the normal operation of the device. Summary of the Utility Model

[0004] In order to overcome the above defects, the utility model provides a regeneration gas drying system, which uses high-temperature methane hydrogen to backflush the condensate falling into the low point to reduce the liquid accumulation phenomenon and ensure the stable operation of the device.

[0005] To achieve the above utility model purpose, the utility model adopts the following technical scheme: a regeneration gas drying system includes a cooling water heat exchanger, a high-pressure steam heat exchanger, a drying unit, a regeneration gas outlet main pipe, and a hot backflush line; the drying unit includes a hot branch pipeline, a cold branch pipeline, a regeneration dryer, an inlet line of the drying unit, and an outlet line of the drying unit; the outlet pipeline of the cooling water heat exchanger is connected to the cold branch pipeline; the outlet pipeline of the high-pressure steam heat exchanger is connected to the hot branch pipeline; the hot branch pipeline and the cold branch pipeline are respectively connected to the inlet line of the drying unit; the outlet line of the drying unit is connected to the regeneration gas outlet main pipe; the inlet end of the hot backflush line is connected to the hot branch pipeline; the outlet end of the hot backflush line is connected to the outlet line of the drying unit.

[0006] Further, the drying unit further includes two diaphragm valve groups, a power valve group, an exhaust valve, and an outlet valve; the two diaphragm valve groups are respectively arranged on the hot branch pipeline and the cold branch pipeline; the power valve group is arranged on the inlet line of the drying unit; the exhaust valve and the outlet valve are sequentially arranged on the outlet line of the drying unit; each diaphragm valve group includes a front valve, a diaphragm valve, and a rear valve; the diaphragm valve is arranged between the front valve and the rear valve.

[0007] Further, a hot blow inlet valve is arranged at the inlet of the hot backflush line; a condensate drain valve and a hot blow outlet valve are sequentially arranged at the outlet of the hot backflush line.

[0008] Further, the inlet end of the hot backflush line is connected between the front valve and the diaphragm valve; the outlet end of the hot backflush line is connected between the exhaust valve and the outlet valve.

[0009] Further, there are three drying units; the three drying units are a liquid-phase drying unit, a second drying unit, and a gas-phase drying unit respectively; the liquid-phase drying unit, the second drying unit, and the gas-phase drying unit are connected in parallel.

[0010] Further, the regeneration dryer of the second drying unit is a second dryer.

[0011] Further, the regeneration dryers of the liquid-phase drying unit are two liquid-phase dryers; the inlet lines of the two liquid-phase dryers are respectively connected to the inlet line of the liquid-phase drying unit; the outlet lines of the two liquid-phase dryers are respectively connected to the outlet line of the liquid-phase drying unit; power valve groups are respectively arranged on the inlet lines of the two liquid-phase dryers; exhaust valves and outlet valves are respectively arranged in sequence on the outlet lines of the two liquid-phase dryers.

[0012] Further, the regeneration dryers of the gas-phase drying unit are two pairs of gas-phase dryers; the inlet lines of the two gas-phase dryers are respectively connected to the inlet line of the gas-phase drying unit; the outlet lines of the two gas-phase dryers are respectively connected to the outlet line of the gas-phase drying unit; power valve groups are respectively arranged on the inlet lines of the two gas-phase dryers; exhaust valves and outlet valves are respectively arranged in sequence on the outlet lines of the two gas-phase dryers; the two gas-phase dryers of a pair of gas-phase dryers are connected in parallel.

[0013] Further, the hot branch pipelines of the liquid-phase drying unit, the second drying unit, and the gas-phase drying unit are respectively connected to the outlet pipeline of the high-pressure steam heat exchanger; the cold branch pipelines of the liquid-phase drying unit, the second drying unit, and the gas-phase drying unit are respectively connected to the outlet pipeline of the cooling water heat exchanger; the outlet lines of the liquid-phase drying unit, the second drying unit, and the gas-phase drying unit are respectively connected to the regeneration gas outlet main pipe.

[0014] Further, the branch pipelines of the hot backflush line are respectively connected to the outlet lines of the two liquid-phase dryers, the outlet line of the second drying unit, and the outlet lines of the two pairs of gas-phase dryers; the inlet end of the hot backflush line is connected between the front valve and the diaphragm valve; a hot blow inlet valve is arranged at the inlet of the hot backflush line; a condensate drain valve and a hot blow outlet valve are respectively arranged in sequence at the outlet of each branch pipeline of the hot backflush line; the outlet end of each branch pipeline of the hot backflush line is connected between the exhaust valve and the outlet valve.

[0015] Due to the adoption of the above technical solution, the utility model has the following beneficial effects: The condensate at the regenerated outlet of the dryer in the regeneration gas drying system is significantly reduced or there is no condensate, achieving the effect of reducing liquid accumulation. There is no longer the phenomenon that the liquid accumulation at the regeneration gas outlet flows back into the dryer, solving the problem of freezing and blocking in the subsequent system and ensuring the stable operation of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic structural diagram of a regeneration gas drying system of the utility model;

[0017] In the figure: 1, cooling water heat exchanger; 2, high-pressure steam heat exchanger; 3, main pipe of regeneration gas outlet; 4, hot back-blowing line; 5, hot branch pipeline of liquid-phase drying unit; 6, hot branch pipeline of second drying unit; 7, hot branch pipeline of gas-phase drying unit; 8, cold branch pipeline of liquid-phase drying unit; 9, cold branch pipeline of second drying unit; 10, cold branch pipeline of gas-phase drying unit; 11, outlet pipeline of cooling water heat exchanger; 12, outlet pipeline of high-pressure steam heat exchanger; 13, inlet line of second drying unit; 14, outlet line of second drying unit; 15, second dryer; 16, inlet line of liquid-phase drying unit; 17, inlet line of liquid-phase dryer; 18, outlet line of liquid-phase dryer; 19, outlet line of liquid-phase drying unit; 20, liquid-phase dryer; 21, inlet line of gas-phase drying unit; 22, inlet line of gas-phase dryer; 23, outlet line of gas-phase dryer; 24, outlet line of gas-phase drying unit; 25, gas-phase dryer; 26, diaphragm valve group; 27, front valve; 28, diaphragm valve; 29, rear valve; 30, power valve group; 31, exhaust valve; 32, outlet valve; 33, hot blow-out valve; 34, condensate drain valve; 35, hot blow-in valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The utility model provides many applicable creative concepts, which can be embodied in a large number in specific contexts. The specific embodiments described in the following embodiments of the utility model are only illustrative descriptions of the specific embodiments of the utility model and do not constitute a limitation on the scope of the utility model.

[0019] The following further describes the utility model in conjunction with the drawings and specific embodiments.

[0020] As Figure 1As shown in the figure, a regeneration gas drying system of the present utility model includes a cooling water heat exchanger 1, a high-pressure steam heat exchanger 2, a drying unit, a regeneration gas outlet main pipe 3, and a hot backflush line 4; the drying unit includes a hot branch pipeline, a cold branch pipeline, a regeneration dryer, an inlet line of the drying unit, and an outlet line of the drying unit; an outlet pipeline 11 of the cooling water heat exchanger is connected to the cold branch pipeline; an outlet pipeline 12 of the high-pressure steam heat exchanger is connected to the hot branch pipeline; the hot branch pipeline and the cold branch pipeline are respectively connected to the inlet line of the drying unit; the outlet line of the drying unit is connected to the regeneration gas outlet main pipe 3; an inlet end of the hot backflush line 4 is connected to the hot branch pipeline; an outlet end of the hot backflush line 4 is connected to the outlet line of the drying unit.

[0021] Further, the drying unit further includes two diaphragm valve groups 26, a power valve group 30, an exhaust valve, and an outlet valve; the two diaphragm valve groups 26 are respectively arranged on the hot branch pipeline and the cold branch pipeline; the power valve group 30 is arranged on the inlet line of the drying unit; the exhaust valve 31 and the outlet valve 32 are sequentially arranged on the outlet line of the drying unit; the diaphragm valve group 26 includes a front valve 27, a diaphragm valve 28, and a rear valve 29; the diaphragm valve 28 is arranged between the front valve 27 and the rear valve 29.

[0022] Further, a hot blow inlet valve 35 is arranged at the inlet of the hot backflush line 4; a condensate drain valve 34 and a hot blow outlet valve 33 are sequentially arranged at the outlet of the hot backflush line 4.

[0023] Further, the inlet end of the hot backflush line 4 is connected between the front valve 27 and the diaphragm valve 28; the outlet end of the hot backflush line 4 is connected between the exhaust valve 31 and the outlet valve 32.

[0024] Further, there are three drying units; the three drying units are a liquid-phase drying unit, a second drying unit, and a gas-phase drying unit; the liquid-phase drying unit, the second drying unit, and the gas-phase drying unit are connected in parallel.

[0025] Further, the regeneration dryer of the second drying unit is a second dryer 15; the second drying unit includes a hot branch pipeline 6 of the second drying unit, a cold branch pipeline 9 of the second drying unit, the second dryer, an inlet line 13 of the second drying unit, and an outlet line 14 of the second drying unit; the outlet pipeline 11 of the cooling water heat exchanger is connected to the cold branch pipeline 9 of the second drying unit; the outlet pipeline 12 of the high-pressure steam heat exchanger is connected to the hot branch pipeline 6 of the second drying unit; the hot branch pipeline 6 of the second drying unit and the cold branch pipeline 9 of the second drying unit are respectively connected to the inlet line 13 of the second drying unit; the outlet line 14 of the second drying unit is connected to the regeneration gas outlet main pipe 3.

[0026] Further, the regeneration dryer of the liquid-phase drying unit is two liquid-phase dryers 20; the liquid-phase drying unit includes the hot branch pipeline 5 of the liquid-phase drying unit, the cold branch pipeline 8 of the liquid-phase drying unit, two liquid-phase dryers 20, the inlet line 16 of the liquid-phase drying unit, and the outlet line 19 of the liquid-phase drying unit; the outlet pipeline 11 of the cooling water heat exchanger is connected to the cold branch pipeline 8 of the liquid-phase drying unit; the outlet pipeline 12 of the high-pressure steam heat exchanger is connected to the hot branch pipeline 5 of the liquid-phase drying unit; the hot branch pipeline 5 of the liquid-phase drying unit and the cold branch pipeline 8 of the liquid-phase drying unit are respectively connected to the inlet line 16 of the liquid-phase drying unit; the outlet line 19 of the liquid-phase drying unit is connected to the regeneration gas outlet main pipe 3; the inlet lines 17 of the two liquid-phase dryers are respectively connected to the inlet line 16 of the liquid-phase drying unit; the outlet lines 18 of the two liquid-phase dryers are respectively connected to the outlet line 19 of the liquid-phase drying unit; the inlet lines 17 of the two liquid-phase dryers are respectively provided with power valve groups 30; the outlet lines 18 of the two liquid-phase dryers are respectively provided with exhaust valves 31 and outlet valves 32 in sequence.

[0027] Further, the regeneration dryers of the gas-phase drying unit are two pairs of gas-phase dryers 25; the gas-phase drying unit includes the hot branch pipeline 7 of the gas-phase drying unit, the cold branch pipeline 10 of the gas-phase drying unit, two pairs of gas-phase dryers 25, the inlet line 21 of the gas-phase drying unit, and the outlet line 24 of the gas-phase drying unit; the outlet pipeline 11 of the cooling water heat exchanger is connected to the cold branch pipeline 10 of the gas-phase drying unit; the outlet pipeline 12 of the high-pressure steam heat exchanger is connected to the hot branch pipeline 7 of the gas-phase drying unit; the hot branch pipeline 7 of the gas-phase drying unit and the cold branch pipeline 10 of the gas-phase drying unit are respectively connected to the inlet line 21 of the gas-phase drying unit; the inlet lines 22 of the two gas-phase dryers are respectively connected to the inlet line 21 of the gas-phase drying unit; the outlet lines 23 of the two gas-phase dryers are respectively connected to the outlet line 24 of the gas-phase drying unit; the inlet lines 22 of the two gas-phase dryers are respectively provided with power valve groups 30; the outlet lines 23 of the two gas-phase dryers are respectively provided with exhaust valves 31 and outlet valves 32 in sequence; the two gas-phase dryers 25 of a pair of gas-phase dryers 25 are connected in parallel.

[0028] Further, the hot branch pipeline 5 of the liquid-phase drying unit, the hot branch pipeline 6 of the second drying unit, and the hot branch pipeline 7 of the gas-phase drying unit are respectively connected to the outlet pipeline 12 of the high-pressure steam heat exchanger; the cold branch pipeline 8 of the liquid-phase drying unit, the cold branch pipeline 9 of the second drying unit, and the cold branch pipeline 10 of the gas-phase drying unit are respectively connected to the outlet pipeline 11 of the cooling water heat exchanger; the outlet line 19 of the liquid-phase drying unit, the outlet line 14 of the second drying unit, and the outlet line 24 of the gas-phase drying unit are respectively connected to the regeneration gas outlet main pipe 3.

[0029] Furthermore, the branch pipelines of the hot back-blowing line 4 are respectively connected to the outlet lines 18 of two liquid-phase dryers, the outlet line 14 of the second drying unit, and the outlet lines 23 of two pairs of gas-phase dryers; the inlet end of the hot back-blowing line 4 is connected between the front valve 27 and the diaphragm valve 28; a hot blow inlet valve 35 is arranged at the inlet of the hot back-blowing line 4; a condensate drain valve 34 and a hot blow outlet valve 33 are successively arranged at the outlet of each branch pipeline of the hot back-blowing line 4; the outlet end of each branch pipeline of the hot back-blowing line 4 is connected between the exhaust valve 31 and the outlet valve 32.

[0030] It should be noted that when the gas-phase dryer, the liquid-phase dryer, and the second dryer 15 need to be regenerated, the regeneration tail gas is introduced into the dryer through the cooling water heat exchanger 1 and the high-pressure steam heat exchanger 22. The regeneration gas flows upward through the dryer bed, and the process medium flows downward in the dryer. Only in the liquid-phase dryer, the regeneration gas flows downward through the dryer bed, and the process medium flows upward in the dryer. The regeneration gas temperature is controlled by adjusting the flow rates of the cold regeneration gas and the hot regeneration gas. The hot regeneration gas provides the necessary heat for the desorption of the moisture adsorbed by the desiccant in the dryer bed. After desorption, the cold regeneration gas cools down the dryer bed. The regeneration gas containing the desorbed water leaves the dryer and is sent to the regeneration gas separation tank through the regeneration gas outlet main pipe 3.

[0031] When the second dryer 15 is in operation and the gas-phase dryer is being regenerated, a large amount of liquid phase will accumulate at the regeneration outlet of the second dryer 15. When the regeneration gas outlet valve of the second dryer 15 is opened, the accumulated liquid will flow back into the dryer, causing freezing and blockage of the subsequent system and affecting the normal operation of the device. By adding a new hot back-blowing line 4 to the regeneration gas, the condensate falling into the low point is back-blown with high-temperature methane hydrogen, so as to reduce the phenomenon of liquid accumulation and ensure the stable operation of the device.

[0032] Under low temperature and high pressure, the molecular sieve in the dryer adsorbs moisture to remove moisture from the cracked gas. Under high temperature and low pressure, the molecular sieve desorbs and releases moisture to remove moisture from the molecular sieve. After the normal dryer has operated for a certain period, the molecular sieve becomes saturated with water absorption and needs to be regenerated to desorb and release moisture. The regeneration steps of the dryer are: put into parallel operation, cut out, relieve pressure, cold blow, drain liquid, heat up, keep constant temperature, cool down, and pressurize for standby. This is the prior art.

[0033] When cold blowing is carried out, there is a large amount of accumulated liquid in the pipeline behind the regeneration gas outlet valve, which affects the normal regeneration of the dryer, the dryer cannot be dried qualified, resulting in freezing and blockage of the subsequent system, and finally leading to the shutdown of the entire device.

[0034] To solve this liquid accumulation problem, the regeneration gas drying system is redesigned to keep the medium flowing in the pipeline all the time. The condensate falling into the low points is backflushed with high-temperature methane hydrogen to reduce the liquid accumulation phenomenon and ensure the stable operation of the device. When the dryer is in operation, the hot backflush line 4 is opened. When the dryer is cold blown, the hot backflush line 4 is closed. The regeneration steps of the dryer become: put into parallel operation, cut out, relieve pressure, close the methane backflush line, cold blow, drain liquid, heat up, keep constant temperature, cool down, open the methane backflush line, and pressurize for standby.

[0035] Furthermore, it should be noted that in the prior art: when cold blowing is carried out, there is a large amount of liquid accumulation in the pipeline behind the outlet valve of the regeneration gas of the liquid-phase dryer, and liquid drainage is required. The liquid drainage time is about 20 - 30 minutes. After the hot methane backflush line is put into use, when cold blowing is carried out, there is no liquid at the regeneration outlet of the dryer, and no liquid drainage is needed anymore; there is a large amount of liquid accumulation in the pipeline behind the outlet valve of the regeneration gas of the second dryer 15, and liquid drainage is required. The liquid drainage time is about 40 - 60 minutes; there is a large amount of liquid accumulation in the pipeline behind the outlet valve of the regeneration gas of the gas-phase dryer, and liquid drainage is required. The liquid drainage time is about 30 minutes.

[0036] For the present utility model: there is no liquid at the regeneration outlet of the liquid-phase dryer, and no liquid drainage is needed anymore; the condensate at the regeneration outlet of the second dryer 15 is significantly reduced or there is no liquid, and the liquid drainage time is about 1 - 3 minutes; the condensate at the regeneration outlet of the gas-phase dryer is significantly reduced or there is no liquid, and the liquid drainage time is about 1 - 3 minutes, solving the problem of freeze plugging in the subsequent system and ensuring the stable operation of the device.

Claims

1. A regeneration gas drying system, characterized in that: It includes a cooling water heat exchanger, a high-pressure steam heat exchanger, a drying unit, a main line for the outlet of the regeneration gas, and a hot backflush line; the drying unit includes a hot branch line, a cold branch line, a regeneration dryer, an inlet line of the drying unit, and an outlet line of the drying unit; the outlet line of the cooling water heat exchanger is connected to the cold branch line; the outlet line of the high-pressure steam heat exchanger is connected to the hot branch line; the hot branch line and the cold branch line are respectively connected to the inlet line of the drying unit; the outlet line of the drying unit is connected to the main line for the outlet of the regeneration gas; the inlet end of the hot backflush line is connected to the hot branch line; The outlet end of the hot backflush line is connected to the outlet line of the drying unit.

2. The regenerated gas drying system according to claim 1, characterized in that: The drying unit further includes two diaphragm valve groups, a power valve group, an exhaust valve, and an outlet valve; the two diaphragm valve groups are respectively arranged on the hot branch line and the cold branch line; the power valve group is arranged on the inlet line of the drying unit; the exhaust valve and the outlet valve are sequentially arranged on the outlet line of the drying unit; the diaphragm valve group includes a front valve, a diaphragm valve, and a rear valve; the diaphragm valve is arranged between the front valve and the rear valve.

3. The regenerated gas drying system according to claim 2, wherein: A hot blow inlet valve is arranged at the inlet of the hot backflush line; a condensate drain valve and a hot blow outlet valve are sequentially arranged at the outlet of the hot backflush line.

4. The regenerated gas drying system according to claim 3, characterized in that: The inlet end of the hot backflush line is connected between the front valve and the diaphragm valve; the outlet end of the hot backflush line is connected between the exhaust valve and the outlet valve.

5. The regenerated gas drying system according to claim 2, characterized in that: There are three drying units; the three drying units are respectively a liquid-phase drying unit, a second drying unit, and a gas-phase drying unit; the liquid-phase drying unit, the second drying unit, and the gas-phase drying unit are connected in parallel.

6. The regenerated gas drying system according to claim 5, wherein: The regeneration dryer of the second drying unit is the second dryer.

7. The regenerated gas drying system according to claim 5 or 6, wherein: The regeneration dryer of the liquid-phase drying unit is two liquid-phase dryers; the inlet lines of the two liquid-phase dryers are respectively connected to the inlet line of the liquid-phase drying unit; the outlet lines of the two liquid-phase dryers are respectively connected to the outlet line of the liquid-phase drying unit; power valve groups are respectively arranged on the inlet lines of the two liquid-phase dryers; exhaust valves and outlet valves are respectively and sequentially arranged on the outlet lines of the two liquid-phase dryers.

8. The regenerated gas drying system according to claim 7, characterized in that: The regeneration dryer of the gas-phase drying unit is two pairs of gas-phase dryers; the inlet lines of the two gas-phase dryers are respectively connected to the inlet line of the gas-phase drying unit; the outlet lines of the two gas-phase dryers are respectively connected to the outlet line of the gas-phase drying unit; power valve groups are respectively arranged on the inlet lines of the two gas-phase dryers; exhaust valves and outlet valves are respectively and sequentially arranged on the outlet lines of the two gas-phase dryers; the two gas-phase dryers in a pair of gas-phase dryers are connected in parallel.

9. The regenerated gas drying system according to claim 5 or 8, characterized in that: The hot branch lines of the liquid-phase drying unit, the second drying unit, and the gas-phase drying unit are respectively connected to the outlet line of the high-pressure steam heat exchanger; the cold branch lines of the liquid-phase drying unit, the second drying unit, and the gas-phase drying unit are respectively connected to the outlet line of the cooling water heat exchanger; the outlet lines of the liquid-phase drying unit, the second drying unit, and the gas-phase drying unit are respectively connected to the main line for the outlet of the regeneration gas.

10. The regenerated gas drying system according to claim 9, wherein: The branch pipelines of the hot backflush line are respectively connected to the outlet lines of two liquid-phase dryers, the outlet line of the second drying unit, and the outlet lines of two pairs of gas-phase dryers; the inlet end of the hot backflush line is connected between the front valve and the diaphragm valve; a hot blow inlet valve is arranged at the inlet of the hot backflush line; a condensate drain valve and a hot blow outlet valve are sequentially arranged at the outlet of the branch pipeline of each hot backflush line; the outlet end of the branch pipeline of each hot backflush line is connected between the exhaust valve and the outlet valve.

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