JPS58104993A - Pyrolysis plant for hydrocarbon - Google Patents

Abstract

PURPOSE:To attempt marked improvement of the energy efficiency by the high-temperature exhaust gas, by connecting, to the burning air feed system of pyrolysis furnace(s), the discharge opening(s) of a variable air flow blower and the exhaust vent(s) of a gas turbine. CONSTITUTION:The discharge opening(s) of a variable air flow blower 51 and the exhaust vent(s) of a gas turbine 61 are connected to the burning air feed system of a pyrolysis furnace 10 for olefin production, an air flow from the blower 51 and/or a divergence of the input guide valve 62 (or the driving source) of the gas turbine 61 being controlled through an air flow controller 30 so that the air flow in the air duct 40 for the pyrolysis furnace 10 is equalized with that which is calculated from a fuel consumption in said furnace and also corrected with an excess oxygen content in the furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrocarbon pyrolysis apparatus for producing ethylene, propylene, and other useful melefins by pyrolysis of hydrocarbons, and particularly relates to a pyrolysis apparatus for producing combustion air to the pyrolysis furnace. Concerning improvements in means.

Generally, for olefin production, a pyrolysis furnace containing a large number of pyrolysis tubes is used, and a device configured to immediately introduce the pyrolyzed gas into a quencher is used. ing. In this pyrolysis furnace, naphtha and kerosene from Okinawa are heated to over 800C.
Fuel consumption is extremely high, so from the standpoint of energy conservation,
It is requested that this fuel consumption be reduced by 10%.

By the way, in order to improve the efficiency of gas turbines from the perspective of comprehensive energy utilization in chemical plants, attempts have been made to use high-purity exhaust gas, which accounts for most of the heat loss in gas turbines, as auxiliary gas for the sintering equipment. There is. However, it is difficult to apply it to combustion equipment with large load fluctuations, such as the production of pillars for gas turbines for power generation, and therefore the field of application is restricted. In other words, when only a pyrolysis furnace and a gas turbine are combined, the amount of exhaust gas from the gas turbine must be controlled to match the load of the pyrolysis furnace, otherwise the thermal freezing effect of the pyrolysis furnace will decrease. Either install a variable guide vane on the inlet side of the turbine to control the amount of air intake, or
Or it is necessary to increase or decrease the load on the gas turbine. However, when controlling in this way, the change in power generation output is large compared to the change in exhaust gas amount, and the power generation efficiency decreases significantly.
Also, as the temperature and oxygen content of the exhaust gas changes,
It is not easy to operate a pyrolysis furnace to meet the above requirements.For this reason, conventionally, pyrolysis furnaces used for producing olefins, which have large load fluctuations, use exhaust gas from a gas turbine as an auxiliary gas. It had not been used.

The purpose of the present invention is to incorporate a gas turbine, which has conventionally been difficult to incorporate into a pyrolysis furnace for producing olefins, which has a large energy load, to achieve carbonization that can significantly improve the energy production of high-temperature exhaust gas. To provide hydrogen pyrolysis equipment.

The present invention connects a combustion air supply system of a pyrolysis furnace to a discharge port for variable air flow and an exhaust port of a gas turbine, and controls the air flow of these blowers and the opening of the input guide vane of the gas turbine. The air flow rate in the air duct for supplying melting air to the pyrolysis furnace is controlled by an air flow control device to control the flow rate from the fuel consumption of the pyrolysis furnace. The purpose is to achieve the above objective by eliminating the drawbacks due to the connection of only a gas turbine by controlling the air flow rate to match the flow rate of air that is discharged and corrected by the excess oxygen flow in the pyrolysis furnace. .

An embodiment of the present invention will be described below with reference to the drawings.

As shown in the upper right corner of the figure, a plurality of pyrolysis furnaces 10 are installed all over the place, and each of these pyrolysis furnaces 10 carries out multi-tube pyrolysis I#11 internally. formula pyrolysis g
A quench cooler (not shown) is directly connected to the outlet Kg of ll. f
In addition, each pyrolysis tube 1-. Saturated hydrocarbons such as naphtha, kerosene, light oil, and natural gas are supplied as pyrolysis raw materials into the chamber 1, and a wooden lid is used as a diluent at a rate of 0.6% of the amount of hydrocarbons supplied.
Supplied mixed with a scale of ~1.0. Each pyrolysis g1
1 is 750-900C within a very short time in the furnace 10.
The temperature is raised to 350 to 650C, and then immediately quenched to about 350 to 650C in a pre-P quencher. .

Each of the pyrolysis furnaces 10 includes an oxygen concentration controller 12 that detects the oxygen concentration in the furnace (i, p), and a pressure that detects and adjusts the furnace pressure and is cascade-controlled 1 by a signal from the oxygen concentration controller 12. Each pyrolysis furnace 10 is provided with a manual damper 15 in its inlet duct 14 and an induction fan 18 driven by a motor 17 in its outlet duct 16. An induced fan inlet damper 19 with a valley is provided. In addition, the set value of the oxygen concentration controller 12 is controlled by the amount of L suitable candy according to the load in the furnace.

#IC@Pyrolysis furnace IO is provided with a gas burner and an oil burner (not shown), and these burners are supplied with fuel gas and fuel oil from a gas main pipe 21 and an oil main pipe 22, respectively. Further, the gas amount 921 is provided with a detector 23 for detecting the flow rate, density, pressure, and temperature of the fuel gas, and the oil main pipe 22 is provided with a detector 24 for detecting the flow rate of fuel oil. There is. The output signals of these detectors 23 and 24 and the output signal of the oxygen concentration regulator 12 are respectively output from the air amount correction controller 2.
0 as the excess air source signal [30
has been entered.

The inlet duct 14 of each pyrolysis furnace 10 is for supplying combustion air to each furnace lO. (tadak) 40. A branch duct 41 branched from the middle of this air duct 40 has a discharge port for an air volume variable blower 51 and an auxiliary air blower @52! The drive sources 53 and 54 of these blowers 51 and 52 are composed of a turbine or a lid holder turbine, and the drive source 53 of the blower 51 is configured to be able to control the rotational speed. At this time, when the drive source 53 is constituted by an electric motor, it is advantageous to control the rotation speed using a frequency converter. That is, a rotation speed control v#55 consisting of a drive source 53KFi, a frequency converter, etc. for the processing air blower 51 is connected, and a signal from the air flow rate control device 30 is inputted to this open side device 55, and the signal from the air flow rate control device 30 is inputted to ff1-.・Source 5
3 rotation [control is being performed. In addition, the auxiliary blower 5
A discharge port 56 with a drive lever is provided at the discharge port 2, so that air blowing from the auxiliary blower 52 to the branch duct 41 can be controlled.

The branch duct 41 of the front 1i empty duct 40 is also upstream 11
1jK, gas turbine exhaust: via gas duct 42
7 is connected to an exhaust port of a gas turbine 61 for power generation. Between this exhaust gas duct '42 and the branch duct 41, the air duct 40 has an air duct 40 for introducing the exhaust gas of the gas turbine 61 into the air duct 40 and l! A switching damper 43 with a drive damper is provided to switch the power on and off. Further, a chimney 44 for releasing into the atmosphere is connected to the exhaust gas duct 42, and a gas turbine 61 is located inside the chimney 44.
A discharge damper 45 with a drive and source is provided to control whether or not the exhaust gas is released to the atmosphere. This damper 4
5 has its opening degree controlled via a pressure control device 47 based on a detection signal from a pressure regulator 46 provided at the confluence of the exhaust gas duct 42 and the air duct 40. .

The output from this pressure control device M47 is the previous I! ? #It is now input to the furnace pressure control system 1 of the cracking furnace 1O, that is, the drive source of the induction fan-incorporated rodannoda 19 of each cracking furnace 10, through a selector (not shown) that selects one of the 6 furnaces 10. ing. At this time, the output signal of the pressure regulator 13 of the famous furnace 10 is also input to the drive source of each mensku 19 through the low selector shown in the figure, and the low selector causes the pressure controller t47 and the pressure regulator 13 to be inputted. The lower one of the output signals is transmitted to the driving source of the maintenance valve 19, and the opening/opening degree is controlled thereby.

On the air intake side of the front r gas turbine 61, an inlet guide vane 62 with a driving source for controlling the intake air raid is provided, and the gas turbine 61 drives the air intake W 63. .

At this time, due to the performance of the gas turbine 61Fi, the load is 100.
Since the operation at 96 is the most thermally efficient, the inlet guide vane 62 is always fully open, and in order to accommodate the 94WT fluctuation of the pyrolysis furnace 10, basically the air volume variable blower is $51.
This is done by increasing or decreasing the amount of air supplied due to air flow, and the opening degree of the air flow guide vane 62 is adjusted only when it is unavoidable. If a two-shaft type gas turbine is used, the amount of wax supplied can be increased or decreased by increasing the load (output) of the gas turbine itself.

In consideration of the case where the gas turbine 61 trips, that is, the gas turbine 61 stops due to some unknown reason, a trip detection control device 57 is provided which is activated by a trip signal of the gas turbine 61. There is. - The output signal of this detection control device 57 is transmitted to the drive source 54 of the auxiliary blower 52.
input, the blower 52 is activated, and the delay 1 is activated.
It is input to the drive source of the discharge rod 456 through the path 58, and causes the discharge port damper 56 to start up the blower 520. In addition, the output signal of the detection control device 57 is input to the drive source of the # air distribution, switching damper/#43 of the air duct 40 and the discharge damper 45 of the chimney 44, and changes the switching damper 43 from open to closed. It is a trap to drive I#45 from closed to open. Furthermore, the same output signal is also sent to the fuel open side system 1 of the pyrolysis furnace 10, and the flow rate in the pyrolysis tube 11 of the pyrolysis furnace 10 is kept to a minimum for a predetermined period of time to reduce the furnace and load. By reducing the flow rate, it is possible to compensate for the lack of oxygen in the furnace until the auxiliary air blower @52 is fully activated. It is like that. In addition, the auxiliary blower 52
After activation, the system returns to operation at a steady flow rate. In addition, in the unlikely event that the auxiliary air blower does not work, the fuel will be cut and the cracking furnace will be shut down.

The branch duct 41 of the front air raid duct 40 is also downstream, that is, on the cracking furnace 10 side, from the left in the figure, the air duct 10
A temperature sensor (T/C) 71 that detects the temperature inside the furnace, a pressure sensor (FT) 72 that detects the pressure, a flow rate sensor (FT) 73 that detects the combustion air flow rate, and oxygen in the firing air. An oxygen concentration detector (02) 74 for detecting concentration is provided, and output signals from each of these detectors 71 to 74 are input to the air flow rate control device 30. This air flow rate control device 30 includes oxygen concentration controllers 12 for the six furnaces 10, as described above, for the output signals of these detectors 71 to 74.
output signals from and gas and oil header 21.2
The output signals from the detectors 23 and 24 of 2 are input, and based on these signals, the rotation speed limiting device g55 and the gas turbine inlet guide vane 62 are adjusted so that the air flow rate in the air duct 10 becomes an escape pressure. 1: □
) It starts to output a control signal in the J range. That is, the air flow rate control device 30 calculates the required amount of oxygen from the amount of fuel in the cracking furnace in the gas main pipe 21 and the oil converter 1221c, and adds the excess air rate from the air amount correction meter 20 to this required amount of oxygen. The number of revolutions of the blower 51 and the gas turbine inlet guide vane are adjusted so that the value calculated by multiplying by 6
K is set to control the opening degree of 2. In addition, the blower 5
1 and the gas turbine inlet guide vane 62 by the air flow rate control device 30, the optimum air amount (oxygen amount) required by the pyrolysis furnace 10 can be controlled by the air flow rate signal of the air duct 40 and the fuel flow rate signal alone. However, considering the case where it is not possible to maintain the appropriate air amount due to errors in each of the detectors 71 to 74, 23, and 24 II#, an excess air rate signal of the pyrolysis furnace 10 is introduced, and the supplied air is Calculation results are corrected based on flow rate, etc.

Next, the operation of this embodiment will be explained by case.

　　・:1′.

When starting the pyrolysis furnace 10 and the gas turbine 61 at the same time when starting the operation of the device, the release amount 45 of the chimney 44 for atmospheric release is opened, and the air duct) 40 is opened.
The cut-off motherboard 43 inside is completely closed, and each pyrolysis furnace 1
The manual engine speed control 15 in the 00-in Rodak)-14 is left fully open.In this state, the gas turbine 61 is started, but since the gas turbine 61 is an automatic start-up, it reaches the no-load rated rotation speed from start-up. Manual control is not possible until then, so the exhaust gas is unplugged from the chimney 44 until then.

Next, each pyrolysis furnace 10'o induction fan 18 is started, and the □ switching dan/main 43 in the air □ duct 40 is activated.
is slightly opened, and a small amount of waste gas from the gas turbine 61 is allowed to flow into each pyrolysis furnace 10. When the exhaust gas starts to flow a little, the heating burner (not shown) of the 6th furnace 10 is ignited to maintain the temperature inside the furnace. We will continue to improve our skills. At this time, the oxygen concentration was not controlled by the air flow rate control device 30, and the pressure inside the pyrolysis furnace 10 was controlled by the induction fan 1-8, and the pressure in the air duct 40 was controlled by the pressure in the vicinity of the exhaust gas duct 42. The so-called pressure control iii is performed by adjusting the opening degree of the discharge lever 445 using the pressure regulator 46.

When the internal demand of the furnace reaches a specified value, steam is allowed to flow into the pyrolysis tube 11 to preserve it. When the temperature of the steam flowing through the pyrolysis tube 11 reaches the pyrolysis temperature, raw material hydrocarbons such as naphtha are introduced into the tube, but the blower 51 with variable air volume is started at the latest before the introduction of the original hydrocarbons. . Pyrolysis tube 11
When hydrocarbons are introduced into the furnace 10, the load on the furnace 10 increases rapidly, so the load is increased while paying close attention to the internal pressure of the air duct 40.

After charging hydrocarbons to each pyrolysis furnace 10, pressure control is switched to oxygen concentration control. On the other hand, as the furnace load increases, it is necessary to increase the amount of air supplied, so
The fan 45 is completely closed and the load on the blower 51 is increased.

The feeding of hydrocarbons to the pyrolysis furnace 10 is completed, and the pyrolysis furnace 1
0 enters stable operation, the gas turbine 610 power generation load is applied. At this time, the temperature of the exhaust gas of the gas turbine 61 increases as the power generation load increases, and the oxygen concentration in the exhaust gas decreases, so the power generation load is gradually increased while paying close attention to changes in the furnace 10. To go.

In addition, when starting up the device, when starting up the pyrolysis furnace 10, in the past, when starting up the gas turbine 61, when starting up each pyrolysis furnace 10, the variable air volume blower 51 and the auxiliary blower 52 were driven to provide only fresh air. K to supply combustion air.

Next, the gas turbine 61 is started after confirming that the switching door 443 in the air dumper 40 is closed and the discharge door 45 of the chimney 44 is open.

After this start-up, after the gas turbine 61 reaches the rated rotational speed, the switching stopper 43 in the cylinder 40 is gradually opened, and the discharge member 45 is gradually closed. At this time, duct 4
If the pressure inside 0 rises, gradually close the discharge valve #56 of the auxiliary blower 52. Discharge Dan / 5
6 is fully closed and the auxiliary blower 52 is stopped, and at 4,
The amount of air supplied by this auxiliary blower 52 is
After switching to the exhaust gas of No. 1, the power generation and load of the Gastersen 61 are gradually increased by monitoring the condition of the furnace 10.

In this way, when the furnace 1o and the gas turbine 61 appear to be in a stable operating state regardless of the % IK before starting and enter a steady operating state, the air flow rate control device 30 controls the oxygen flow rate. The combustion air flow rate required in the pyrolysis furnace 10 is calculated by adding the theoretical air flow rate to the total amount of fuel gas and fuel oil to the burners provided in the furnace 10, and the excess air rate in the exhaust gas of the pyrolysis furnace 10. The required air flow rate is controlled to match the air flow rate in the air duct 40. At this time, the air flow rate in the air chamber 40 is corrected based on the oxygen concentration, temperature, pressure, etc. in the air.

By the way, coke is deposited in the pyrolysis tube 11 as a result of the pyrolysis reaction of hydrocarbons in the pyrolysis furnace 10, and the efficiency of the pyrolysis furnace 10 decreases over time. Therefore,
A plurality of pyrolysis furnaces 10 are installed in parallel, and the operation is switched at regular intervals, so that the entire olefin production plant is continuously operated.

When the coke is deposited in the coke-pyrolysis tube 11, the supply of the raw material hydrogen carbonate is stopped, and steam and air are supplied to the pyrolysis tube 11 to remove the coke precipitated in the tube. Typically, the heating burner is extinguished and the inside of the furnace is inspected, so the required air flow rate of the pyrolysis furnace will vary significantly in such a process.

When the required air flow rate decreases due to partial stoppage of a plurality of pyrolysis furnaces 1O, first, the drive source 53 of the variable air volume blower 51 is
is achieved through the rotational speed control device 55, and the required air flow rate is compared with the indicated value of the flow rate detector 73 installed in the air duct 40 and adjusted. When adjustment by the blower 51 alone is not sufficient, the amount of exhaust gas is reduced by throttling the inlet guide vane 62 of the gas turbine 761 or by reducing the power generation load of the two-shaft gas turbine, thereby reducing the air flow rate in the air duct 40. let If adjusting the inlet guide vane 62 or reducing the power generation load is not enough, the discharge damper 45 in the chimney 44 is opened while the amount is controlled by the pressure regulator 46 to cope with the problem.

On the other hand, when starting the pyrolysis furnace 10 from which coke removal has been completed, the air flow rate is increased by the operation opposite to that described above, and if the air flow rate is still insufficient, the auxiliary blower 52 is operated to cover it.

Next, when the gas turbine 61 or the generator 63 comes to an emergency stop (trip) due to a failure or the like, the stop of the gas turbine 61 is immediately detected by the trip detection control device 57, and the switching dunner in the air duct 40 is immediately detected. While the pipe 43 is closed, the discharge dunner 45 in the chimney 44 is opened and the auxiliary blower 52 is started to compensate for the decrease in the supply air flow rate. At this time, even if the auxiliary blower 52 is started, it takes more than 10 seconds to complete the start of the drive source 54, so if the pyrolysis furnace 10 is operated at a constant load, there will be a temporary air shortage. . Therefore, the problem is dealt with by reducing the load on the pyrolysis furnace 10 until the auxiliary blower 52 is fully activated.

As described above, according to the power tree embodiment, the high temperature exhaust gas discharged from the gas turbine 61 can be used, and the energy efficiency of the pyrolysis apparatus can be greatly improved. At this time, in addition to the exhaust gas, a variable air volume blower 51 was installed, and the air flow rate was always controlled using the air volume of the air blower 51. Therefore, unless there is a large change in the furnace load, 100% load operation is possible. This does not cause a decrease in the efficiency of the preferable gas turbine 61. Furthermore, when the device is started, the air flow rate control device 30 does not perform any control, and the air flow rate control device 30 does not perform any control.
Since the control is performed by the furnace internal pressure control system consisting of 19, etc. and the pressure control device 47, the system can be controlled more appropriately when the air volume is insufficient at startup.

In addition, in implementation, as a countermeasure against air shortage when starting up the auxiliary blower 52 when the gas turbine 61 trips, there is a method in which the auxiliary blower 52 is always operated with no load, and when the gas turbine 61 trips, the load is rapidly applied. Alternatively, a method of configuring the auxiliary blower 52 with a large number of small units that can be started quickly can be considered, but this poses problems such as operation costs, equipment costs, etc. □,'1. Load limiting methods are advantageous. In addition, if each pyrolysis furnace IO is equipped with an induction fan 18 as in the above embodiment, an emergency suction duct 48 is provided in the air duct 40, as shown by the chain line in the figure. The dan/#49 may be opened to suck air when the gas turbine 61 trips. moreover,
The number of pyrolysis furnaces 10 is not limited to four as shown in the figure, but may be four or less or four or more.

As described above, the present invention has the effect of providing a hydrocarbon pyrolysis apparatus that can significantly improve the energy efficiency of the apparatus.

[Brief explanation of drawings]

The figure is a schematic configuration diagram showing one embodiment of the present invention. 10...Pyrolysis furnace, 12...Oxygen concentration etc. needle, 1
8... Induction fan, 20... Air amount correction controller, 2
1... Gas main pipe, 22... Oil main pipe, 23.24
...Detector, 30...Air flow rate control device, 40...
・Air duct, 43...Switching end, N/#, 45...
Discharge Dan/etc., 46... Pressure controller, 4'7... Pressure control device, 51... Variable air volume: Blower, 52-... Auxiliary blower, 55... Rotation speed control device, 57 . . . trip detection control device, 61 . . . is a turbine, 62 .
Flow l detector, 74...Oxygen concentration detector. Procedural Amendment (Voluntary) March 8, 1981, Showa S6 Year Permit Application No. SOS*ST No. 2, Issued TSO
Name Hydrocarbon. Heat distribution device 3, relationship with the case of the person making the amendment Patent applicant 4, agent 6, number of inventions increased by amendment 7
, Target of correction 1. Modify "quantity ratio" to "weight ratio of 0.3 to 1.0". (2) "About 350 to 650°C" on page 5, line 9 of the specification is changed to "about 350 to 700°C." Above 11゜

Claims (1)

[Claims] (1) In addition to installing pyrolysis furnaces with built-in hydrocarbon pyrolysis tubes in a row of multiple V groups, ``in these pyrolysis furnaces?'' A variable air volume blower and a gas turbine are installed in series to supply a blowing space, and the discharge port of the blower and the exhaust port of the gas turbine are respectively connected to the air ducts leading to each pyrolysis furnace.
Between the exhaust port of the gas turbine and the air duct, there is provided a switch for switching between introducing and blocking the exhaust gas of the gas turbine into the air duct, and the air flow rate in the air duct is controlled by the heat # to match the air flow rate calculated from the fuel consumption of the cracking furnace and corrected by the excess oxygen plan of the pyrolysis furnace.
1. A hydrocarbon pyrolysis apparatus characterized in that an air flow rate control device is provided to control at least one of a drive source for a blower and an inlet guide vane or a drive source for a gas turbine. (2. In the first claim, it is provided that among the control of the body II of the variable air volume blower and the control of the inlet guide vane or drive of the gas turbine, one ill of the drive tube of the kite-operated air blower is provided. A hydrocarbon thermal decomposition device characterized by being equipped with an air flow rate control device that preferentially performs ill.