CN1142248C - Process for utilizing low-pressure tail gas of ethylene plant - Google Patents
Process for utilizing low-pressure tail gas of ethylene plant Download PDFInfo
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- CN1142248C CN1142248C CNB011075805A CN01107580A CN1142248C CN 1142248 C CN1142248 C CN 1142248C CN B011075805 A CNB011075805 A CN B011075805A CN 01107580 A CN01107580 A CN 01107580A CN 1142248 C CN1142248 C CN 1142248C
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- tail gas
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Abstract
The present invention relates to a process for utilizing the low-pressure tail gas of an ethylene device. The present invention is characterized in that low-pressure tail gas with regulated pressure enters a low-pressure fuel system to directly supply heat to a cracking furnace through regulating the pressure of the low-pressure tail gas produced by the ethylene device; in addition, high-pressure tail gas enters the high-pressure fuel system of the cracking furnace after being dried, regenerated and activated by catalysts, controls the outlet temperature of the cracking furnace at the same time and supplies pressure to the low-pressure fuel system. The present invention recycles the low-pressure tail gas in a simple technological process, cancels a tail gas compressor in a traditional technology, and has the advantages of low investment, little land occupation, low energy consumption, simple operation, low maintenance cost and stable operation.
Description
The low-pressure tail gas that the present invention relates to ethylene unit utilizes method.
At present, ethylene unit is with tube furnace Pintsch process technology, and petroleum hydrocarbon is decomposed into H from small molecular weight
2, CH
4One until the very big cracking heavy oil of viscosity, the split product of all size carbochain through a series of fractionation, compress, remove chemical processes such as sour gas, drying, refrigeration, low temperature separation process, reaction be refining, isolate product and other byproducts such as ethene, propylene.In the pyrolysis in tubular furnace technology, petroleum hydrocarbon raw material is many to carry out heat scission reaction under high temperature more than 800 ℃, because the requirement of fuel balance is considered to install the fuel of self-produced tail gas byproduct as pyrolyzer in the technological design of ethylene unit usually.The tail gas byproduct is from two positions of low temperature separation process process; The one, the gas phase high pressure exhaust gas of demethanizing tower return tank extraction and liquid phase tail gas; Another part originates from the low-pressure methane hydrogen of separation drum, the low-pressure tail gas that low-pressure methane hydrogen also is commonly called as for everybody, tail gas byproduct from the demethanizing tower is sent with 0.6MPa, the tail gas byproduct that originates from separation drum is decompressed to the laggard tail-gas compressor of 0.02MPa and boosts to more than the 0.35MPa, behind the regeneration of high pressure exhaust gas drying device, catalyst activation, enter the pyrolyzer high-pressure fuel system, and the pyrolyzer temperature out of control high pressure exhaust gas is more than 800 ℃ as the pyrolyzer fuel of heat supply.
From the tail gas byproduct of ethylene unit output, after high and low pressure tail gas separated, low-pressure tail gas accounted for 1/3rd of tail gas byproduct, if do not utilize, can only put to burning in the air from torch.In order to utilize this part energy; must add electronic or the decompressor compressor driven; also has corresponding supporting monitoring around unit; protection etc.; these equipment and huge compressor have increased many floor spaces and one-time investment; the energy consumption height of these equipment; maintenance cost is big; and compressor assembly relates to suction pressure; outlet pressure, minimum reflux, water coolant; fresh water; lubricating oil, sealing oil, the fuel feed when shutting down situation and the vibration of unit; a whole set of operation such as axle temperature; control; interlocking; projects such as daily monitoring; increase the complicated operation degree, increased dried the scratching of device simultaneously; fluctuation; stop and wait the probability that takes place.
The purpose of this invention is to provide a kind of low-pressure tail gas of ethylene plant and utilize method, this method has been cancelled the tail-gas compressor in the traditional technology, low-pressure tail gas after the pressure regulation is entered low-pressure fuel system directly to the pyrolyzer heat supply, finish the recycling of low-pressure tail gas with simple processing method, use equipment is few, and one-time investment and floor space are little, energy consumption is low, simple to operate, maintenance cost is low, and the device running is stable.
Technical solution of the present invention is such:
The pressure of the low-pressure tail gas of A, adjusting ethylene unit output,
B, the low-pressure tail gas that will adjust pressure enter low-pressure fuel system directly to the pyrolyzer heat supply,
C, high pressure exhaust gas enter the high-pressure fuel system of pyrolyzer on the basis of finishing moisture eliminator regeneration, catalyst activation, and finish the control of pyrolyzer temperature out simultaneously and to the ftercompction of low-pressure fuel system.
The above adjusts the pressure of low-pressure tail gas, and the pressure of the low-pressure tail gas that produces in the conventional production methods by 0.12MPa, is increased to about 0.17MPa, to adapt to low-pressure fuel system.
Low-pressure fuel system of the present invention has high-pressure discharge, low pressure replenishment control valve, the control loop of the pressure of low pressure drop pipeline and stable system, the measuring instrument of pressure flow, interlock circuit and control valve that the low pressure interlocking cuts off and is connected with the pyrolyzer interlock control system.
More than the low-pressure tail gas that is adjusted into about 0.17Mpa pressure of the present invention enter low-pressure fuel system, go into the low pressure nozzles to the pyrolyzer heat supply through the low pressure drop pipeline is laggard.
Interlocked valve of the present invention and interlock control system are to be provided with at safety and shutdown system, and purpose is a protection ethylene unit safety, and its interlocked valve and interlock control system are modern chemical industry, the general known technology of oil refining industry.
Moisture eliminator regeneration and catalyst activation, the tail gas quantity of this process demand accounts for 60% (wt) of device exhaust ultimate production, in the deep cooling process for separating, accounts for 70% (wt) of tail gas total amount from the quantity of the isolated high pressure exhaust gas of demethanizing tower (pressure 0.6Mpa).From quantitative analysis, only high pressure exhaust gas just can satisfy the needs of regeneration and reactivation process and have a surplus, so only high pressure exhaust gas is carried out moisture eliminator regeneration, catalyst activation program in the high and low pressure two-way heat supply flow system of the present invention.
One of principal contradiction that low-pressure methane heat supply of the present invention will solve is exactly that used tail gas pressure is low, in this case, designed pipeline should adopt the low pressure drop design, the measure that for this reason mainly solves low pressure drop on low pressure line promptly is to reduce control valve as far as possible, elbow and orifice plate, flow velocity is to reduce pressure drop.
The present invention uses the low pressure nozzles, is because low-pressure fuel accounts for 1/3rd of total amount of fuel, so the performance of low pressure nozzles is very important.The configuration of low-pressure tail gas heating system should be paid the utmost attention to the sidewall heat supply, when the heat supply of whole bottoms, can solve the heat supply problem by the two nozzles configurations of high and low pressure, burner hearth middle part flux was big when such design also can be alleviated the nozzles heat supply of full bottom, and bottom problem less than normal.
The pressure of low-pressure tail gas of the present invention is mainly determined by the temperature of hydrogen in the hydrogen gas tank.When the flash distillation back pressure of tail gas byproduct was 0.2Mpa, hydrogen temperature was controlled at-163 ℃ in the hydrogen gas tank.Because of low-pressure tail gas process ice chest system in the cold recovery process, the pressure drop of 0.03MPa is generally arranged, in fact the about 0.17MPa of pressure that sends of low-pressure tail gas, the selection of this pressure parameter, the low-pressure tail gas 0.12MPa that produces than the past traditional technology has improved 0.05MPa hydrogen product purity and has guaranteed 95% (mol).
The present invention has reduced one-time investment and occupation of land.Employed electronic or decompressor compressor driven in traditional technology, its investment accounts for 1% of device gross investment, and takes up an area of bigger; Owing to not adopting compressor, the present invention do not reduce investment and saving land used.The present invention has reduced energy consumption.Traditional technology mesolow tail gas boosts with compressor and current consumption is big, the present invention thereby do not have this energy consumption.
The present invention has reduced maintenance cost.Tail-gas compressor in the traditional technology is one of main equipment in the ethylene process process, and is very important equipment, accidentally not only can cause a large amount of tail gas emptying to torch, and can cause the fluctuation of pyrolyzer system slightly, even stops.Thereby the tail-gas compressor maintenance repair is changed oil, and maintenance services such as monitoring are more, and will prepare a large amount of spare parts, and there is not this problem in the present invention.
The present invention has simplified operation, has increased reliability of operation.A whole set of project such as operation, control, interlocking, daily monitoring such as the fuel feed the when compressor assembly of traditional technology relates to suction pressure, outlet pressure, minimum reflux, water coolant, fresh water, lubricating oil, sealing oil, shutdown situation and the vibration of unit, axle temperature; not only increase operational ton, and increased the probability that device disturbs, fluctuates even stop.The present invention is because of without compressor assembly, thereby reduced operation, avoided that unnecessary device disturbs, fluctuation.
Advantage of the present invention is to have cancelled the tail-gas compressor in the traditional technology, low-pressure tail gas after the pressure regulation is entered low-pressure fuel system directly to the pyrolyzer heat supply, finish the recycling of low-pressure tail gas with simple processing method, use equipment is few, one-time investment and floor space are little, energy consumption is low, and is simple to operate, and the device running is stable.
Below in conjunction with accompanying drawing embodiments of the invention are described:
Fig. 1 low-pressure tail gas of the present invention utilizes schema.
According to shown in Figure 1, the operational path of pressure that the present invention adjusts the low-pressure tail gas of ethylene unit output be by the overhead stream of rectifying tower return tank D1 through in the plate-fin heat exchanger E by partial condensation after, liquid phase material tail gas flash distillation under the back pressure low less than 0.1MPa of sending into hydrogen gas tank D2 produces cold, heat exchange in plate-fin heat exchanger E, to satisfy the needs of reparation technology process to hydrogen product, when the flash distillation back pressure of tail gas byproduct is 0.2MPa, hydrogen temperature is controlled at-163 ℃ in the hydrogen gas tank, because of low-pressure tail gas will pass through ice chest in the cold recovery process, the pressure drop of 0.03MPa is generally arranged, in fact the about 0.17MPa of pressure of low-pressure tail gas outlet is to adapt to low-pressure fuel system.Low-pressure fuel system is the fuel system of being set up based on from the low-pressure tail gas of low temperature separation process, its technical process is the low-pressure tail gas from hydrogen gas tank and methane tower, pressure with 0.17MPa enters low-pressure fuel system, enters the low pressure nozzles to the pyrolyzer heat supply through low pressure line.Pressure for stable system, be to guarantee to enter the pyrolyzer heat supply to stablize, this system is provided with high-pressure discharge, the additional control valve of low pressure, control loop, simultaneously, the instrument that has disposed pressure, flow routinely detects, interlock circuit and control valve that the low pressure interlocking cuts off and is connected with the pyrolyzer interlock control system.Described low pressure drop pipeline is to reduce elbow, the control valve of current limiting element, orifice plate etc. in design as far as possible.
The high pressure exhaust gas that from the isolated pressure of demethanizing tower is 0.6MPa enters the high-pressure fuel system of pyrolyzer by traditional moisture eliminator regeneration, the basis of catalyst activation, by being located at the high pressure nozzles of furnace bottom, with 800 ℃ of pyrolyzer heat supplies of pyrolyzer temperature out to ethylene unit.The required thermal load of pyrolyzer is mainly controlled by the high pressure exhaust gas amount, so high pressure exhaust gas accounts for 70% of tail gas total amount of fuel, the low-pressure tail gas system is guaranteeing that hydrogen purity is under the situation of 95% (mol), satisfies the distribution of pyrolyzer heating demand.Low-pressure fuel system is correspondingly provided with ftercompction control voltage-stabilizing system for this reason, and fireproof tempering device.Voltage-stabilizing system is a pipeline inner pressure in the control low-pressure fuel system, comes ftercompction with high pressure exhaust gas immediately when pressure descends.Fireproof tempering device is an interlocked valve, and signal such as raw material when taking place, interlocking cut off when cutting off the water, have a power failure, stopping, valve-off.
Claims (3)
1, a kind of low-pressure tail gas of ethylene plant utilizes method,
A, discharge the balance that the throttling refrigeration degree of depth of material and temperature, material are formed, adjust the pressure of the low-pressure tail gas of ethylene unit output, the pressure of conventional production methods mesolow tail gas by 0.12MPa, is increased to about 0.17MPa by the control hydrogen gas tank,
B, the low-pressure tail gas that will adjust pressure enter low-pressure fuel system directly to the pyrolyzer heat supply,
C, high pressure exhaust gas enter the high-pressure fuel system of pyrolyzer on the basis of finishing moisture eliminator regeneration, catalyst activation, and finish the control of pyrolyzer temperature out simultaneously and to the ftercompction of low-pressure fuel system.
2, a kind of low-pressure tail gas of ethylene plant according to claim 1 utilizes method, it is characterized in that low-pressure fuel system has the low pressure drop pipeline, and the pressure high-pressure discharge of stable system, low pressure replenishment control valve, control loop, the measuring instrument of pressure flow, interlock circuit and control valve that the low pressure interlocking cuts off and is connected with the pyrolyzer interlock control system.
3, a kind of low-pressure tail gas of ethylene plant according to claim 2 utilizes method, it is characterized in that being adjusted into about 0.17MPa, and the low-pressure tail gas of pressure enters low-pressure fuel system, goes into the low pressure nozzles to the pyrolyzer heat supply through the low pressure drop pipeline is laggard.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011075805A CN1142248C (en) | 2001-02-27 | 2001-02-27 | Process for utilizing low-pressure tail gas of ethylene plant |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011075805A CN1142248C (en) | 2001-02-27 | 2001-02-27 | Process for utilizing low-pressure tail gas of ethylene plant |
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| Publication Number | Publication Date |
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| CN1320676A CN1320676A (en) | 2001-11-07 |
| CN1142248C true CN1142248C (en) | 2004-03-17 |
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| CNB011075805A Expired - Lifetime CN1142248C (en) | 2001-02-27 | 2001-02-27 | Process for utilizing low-pressure tail gas of ethylene plant |
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| CN104099130A (en) * | 2013-04-02 | 2014-10-15 | 敬东科技股份有限公司 | Recycling method for cracking furnace tail gas |
| CN110425768A (en) * | 2019-07-30 | 2019-11-08 | 中国电子科技集团公司第十一研究所 | Taper throttling refrigerator |
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