Methanol purge gas recycling system

Abstract

The utility model discloses a methanol purge gas recycling system which comprises a methanol synthesis device, a purge gas washing tower, a hydrogen extraction device and a coke oven, a purge gas outlet of the methanol synthesis device is communicated with a gas inlet of the purge gas washing tower through a pipeline, a gas outlet of the purge gas washing tower is communicated with a gas inlet of the hydrogen extraction device through a pipeline, and the gas outlet of the purge gas washing tower and a desorbed gas outlet of the hydrogen extraction device are both communicated with a coke oven return gas pipeline through pipelines. The device has the advantages that the desorbed gas and the coke oven gas are blended to serve as fuel gas to be fed into the combustion chamber of the coke oven through the coke oven return gas pipeline, so that the coke oven gas yield is increased, and the coking economic benefit is further improved. Meanwhile, the opening degree of the flow adjusting valve can be adjusted according to the flame temperature, detected by the flame temperature sensor, in the combustion chamber of the coke oven, so that the temperature requirement of the first-stage metallurgical coke is met. The utility model can greatly save the consumption of coke oven gas and improve the economic benefit of enterprises.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of reuse systems of vent gas, in particular to a kind of methanol vent gas reuse system. BACKGROUND

[0002] In the process of preparing methanol, most of the gas discharged from methanol synthesis column forms circulating gas in the process of cooling and separating methanol, and the rest is regarded as methanol vent gas. Methanol vent gas contains abundant hydrogen, carbon monoxide, carbon dioxide, methane and nitrogen, and also valuable components such as methanol and methyl formate. In order to realize the reuse of effective gas therein, hydrogen contained in the vent gas is usually purified by pressure swing adsorption, but in the process of purification, desorption gas is produced as a byproduct, which also contains hydrogen, nitrogen, methane, carbon monoxide, carbon dioxide and a small amount of methanol. Currently, this part of desorption gas is usually directly discharged to the flare for combustion and venting; at the same time, when the hydrogen extraction process is overhauled or stopped, the methanol vent gas also needs to be discharged to the flare for combustion and venting, causing great waste of resources. SUMMARY

[0003] In order to solve the above problems, the purpose of the utility model is to provide a kind of methanol vent gas reuse system.

[0004] The utility model is implemented by the following technical solutions:

[0005] A kind of methanol vent gas reuse system, comprising a methanol synthesis device, a vent gas scrubbing tower, a hydrogen extraction device and a coke oven;

[0006] The vent gas outlet of the methanol synthesis device is communicated with the gas inlet of the vent gas scrubbing tower through a pipeline, the gas outlet of the vent gas scrubbing tower is communicated with the gas inlet of the hydrogen extraction device through a pipeline, and the gas outlet of the vent gas scrubbing tower and the desorption gas outlet of the hydrogen extraction device are both communicated with the coke oven gas recycling pipeline through a pipeline;

[0007] A first shut-off valve is provided on the pipeline communicating the gas outlet of the vent gas scrubbing tower and the coke oven gas recycling pipeline;A second shut-off valve is provided on the pipeline communicating the gas outlet of the vent gas scrubbing tower and the gas inlet of the hydrogen extraction device.

[0008] Further, the desorption gas outlet of the hydrogen extraction device is also communicated with the flare through a pipeline;

[0009] A flame temperature sensor is provided in the combustion chamber of the coke oven, a third shut-off valve is provided on the pipeline communicating the desorption gas outlet of the hydrogen extraction device and the flare;A flow regulating valve is provided on the pipeline communicating the desorption gas outlet of the hydrogen extraction device and the coke oven gas recycling pipeline;

[0010] The signal output end of the flame temperature sensor is signal connected with the signal input end of the controller, and the signal output end of the controller is signal connected with the signal input end of the first cut-off valve, the second cut-off valve, the third cut-off valve and the flow regulating valve respectively.

[0011] The utility model discloses the advantages of:

[0012] The utility model discloses the desorption gas is mixed and is used as fuel gas by coke oven gas pipeline and is sent into the combustion chamber of coke oven, increases coke oven gas production, and further improves the economic benefit of coking. Meanwhile, can adjust the opening size of flow regulating valve according to the flame temperature in the coke oven combustion chamber detected by flame temperature sensor, and further adjust the proportion of mixed desorption gas, to guarantee to satisfy the temperature requirement of primary metallurgical coke.

[0013] The utility model discloses simple system, the transformation cost is low, can also save the dosage of coke oven gas greatly, improves the economic benefit of enterprise. DRAWINGS:

[0014] In order to more clearly illustrate the technical scheme in the embodiment of the utility model or prior art, the following will briefly introduce the drawing needed to be used in the embodiment or prior art description, and obviously, the drawing in the following description is only some embodiments of the utility model, and for the ordinary skilled person in the art, other drawings can also be obtained according to these drawings without paying creative labor.

[0015] Figure 1 It is the system connection schematic diagram of this embodiment;

[0016] Figure 2 It is the signal control schematic diagram of this embodiment.

[0017] In the drawing: methanol synthesis device 1, purge gas washing tower 2, hydrogen extraction device 3, coke oven back gas pipeline 4, torch 5, flame temperature sensor 6, controller 7, first cut-off valve 8, second cut-off valve 9, third cut-off valve 10, flow regulating valve 11. CONCRETE IMPLEMENTATION:

[0018] The technical scheme in the embodiment of the utility model will be clearly and completely described in the following combined with the drawings in the embodiment of the utility model, and obviously, the described embodiment is only a part of the embodiment of the utility model, not all the embodiment. Based on the embodiment in the utility model, all other embodiments obtained by the ordinary skilled person in the art without creative labor belong to the protection scope of the utility model.

[0019] Embodiment 1:

[0020] As Figure 1 ,2 The methanol purge gas recycling system shown comprises a methanol synthesis device 1, a purge gas washing tower 2, a hydrogen extraction device 3, and a coke oven;

[0021] The outlet of the methanol synthesis device 1 is connected to the gas inlet of the purge gas washing tower 2 through a pipeline, the gas outlet of the purge gas washing tower 2 is connected to the gas inlet of the hydrogen extraction device 3 through a pipeline, and the gas outlet of the purge gas washing tower 2 and the desorption gas outlet of the hydrogen extraction device 3 are both connected to the coke oven gas recycling pipeline 4 through pipelines;

[0022] A first shut-off valve 8 is arranged on the pipeline connecting the gas outlet of the purge gas washing tower 2 and the coke oven gas recycling pipeline 4, and a second shut-off valve 9 is arranged on the pipeline connecting the gas outlet of the purge gas washing tower 2 and the gas inlet of the hydrogen extraction device 3.

[0023] The desorption gas outlet of the hydrogen extraction device 3 is also connected to the flare 5 through a pipeline, a flame temperature sensor 6 is arranged in the combustion chamber of the coke oven, a third shut-off valve 10 is arranged on the pipeline connecting the desorption gas outlet of the hydrogen extraction device 3 and the flare 5, and a flow regulating valve 11 is arranged on the pipeline connecting the desorption gas outlet of the hydrogen extraction device 3 and the coke oven gas recycling pipeline 4; the signal output end of the flame temperature sensor 6 is signal connected to the signal input end of the controller 7, and the signal output end of the controller 7 is signal connected to the signal input ends of the first shut-off valve 8, the second shut-off valve 9, the third shut-off valve 10, and the flow regulating valve 11.

[0024] Working explanation:

[0025] Under normal circumstances, the methanol purge gas is sent to the hydrogen extraction device 3 to recover the hydrogen contained therein, and the by-product desorption gas is mixed with the coke oven gas to be used as fuel gas and sent to the combustion chamber of the coke oven through the coke oven gas recycling pipeline 4, thereby increasing the coke oven gas production and improving the economic benefit of coking.

[0026] When the hydrogen extraction device 3 is under maintenance or fails to operate, the methanol purge gas is directly mixed with the coke oven gas to be used as fuel gas and sent to the combustion chamber of the coke oven through the coke oven gas recycling pipeline 4.

[0027] Since the heat value of the desorption gas is low, it may not reach the required temperature of the first-grade metallurgical coke under different working conditions. Therefore, the opening size of the flow regulating valve 11 can be adjusted according to the flame temperature in the combustion chamber of the coke oven detected by the flame temperature sensor 6, so as to adjust the proportion of the mixed desorption gas, thereby ensuring that the temperature requirement of the first-grade metallurgical coke is met. The desorption gas that cannot be recycled by mixing is burned and vented through the flare 5.

[0028] In this embodiment, the components and contents of the methanol purge gas and the desorption gas are shown in Table 1.

[0029] Table 1 composition and content of methanol purge gas and desorption gas

[0030]

[0031] In this embodiment, the process parameters of methanol purge gas and desorption gas are shown in Table 2.

[0032] Table 2 process parameters of methanol purge gas and desorption gas

[0033]

[0034] The enterprise present methanol production load is 80%, before the implementation of this embodiment, the desorption gas and the purge gas to the flare vent flow is about 11000Nm3 / h, calculated according to the heat value of desorption gas 6874.75kJ / Nm3, can replace about 4007.89Nm3 / h coke oven gas (calculated according to the heat value of coke oven gas 16552.40kJ / Nm3 in May, two series heat value average value). According to the operation of 8000 hours per year, the unit price of coal gas is 0.5 yuan / Nm 3 The calculation, the annual incremental income is about: 4007.89Nm 3 / h×8000h×0.5 yuan / Nm 3 ÷10000=1603 million yuan.

[0035] The above only for the preferred embodiment of the utility model has, and does not limit the utility model, any modification, equivalent replacement, improvement etc. made within the spirit and principles of the utility model, should be included in the protection scope of the utility model.

Claims

1. A methanol purge gas recycling system, characterized in that: It includes methanol synthesis unit, off-gas scrubber, hydrogen extraction unit and coke oven; The purge gas outlet of the methanol synthesis unit is connected to the air inlet of the purge gas washing tower through a pipeline, the air outlet of the purge gas washing tower is connected to the air inlet of the hydrogen extraction device through a pipeline, and the air outlet of the purge gas washing tower and the desorbed gas outlet of the hydrogen extraction device are both connected to the coke oven return gas pipeline through a pipeline; A first shut-off valve is provided on the pipeline connecting the gas outlet of the purge gas washing tower and the coke oven return gas pipeline; a second shut-off valve is provided on the pipeline connecting the gas outlet of the purge gas washing tower and the gas inlet of the hydrogen extraction device.

2. A methanol purge gas recycling system according to claim 1, characterized in that: The desorbed gas outlet of the hydrogen extraction device is also connected to the flare through a pipeline; A flame temperature sensor is provided in the combustion chamber of the coke oven, a third shut-off valve is provided on the pipeline connecting the desorbed gas outlet of the hydrogen extraction device and the flare; a flow regulating valve is provided on the pipeline connecting the desorbed gas outlet of the hydrogen extraction device and the coke oven return gas pipeline; The signal output end of the flame temperature sensor is signal-connected to the signal input end of the controller, and the signal output end of the controller is signal-connected to the signal input ends of the first shut-off valve, the second shut-off valve, the third shut-off valve and the flow regulating valve respectively.

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