JP6144520B2 - Method of cooling manufacturing equipment during non-stationary conditions - Google Patents

Description

  The present invention relates to a cooling method for manufacturing equipment during non-stationary conditions. In particular, the present invention relates to a method for cooling production equipment (reaction product gas) at a non-stationary time in a gas phase oxidation reaction process.

  In the gas phase oxidation reaction process, especially ethylene oxide (ethylene oxide) production process, it was assumed in advance that an explosive combustible material would be generated when the control of temperature and pressure became difficult due to abnormal reaction, for example, due to abnormal reaction. A coping structure is required. As a countermeasure structure that presupposes an unsteady time, the structure of the device that can manually open and close the solenoid valve and the power valve, or depending on the reactor, it can be ventilated cooling or natural cooling with a blower using pressurized gas or emergency power supply Such a device structure has been devised (for example, see Patent Document 1).

  Further, in the gas phase oxidation reaction process, the reactor inlet gas is usually heat-exchanged with the reactor outlet gas in order to save the process energy (see, for example, Non-Patent Document 1).

JP 2002-226427 A

Chemical Process From Basics to Technology Development 1st Edition, 1st edition, published on March 25, 1998, edited by Chemical Engineering Society, pages 121-128

  In Patent Document 1 and Non-Patent Document 1, when an abnormal reaction occurs in the reactor, the reactor outlet gas is supplied to the heat exchanger at a higher temperature than usual. In that case, in the heat exchanger, the reactor inlet gas is heat-exchanged to a temperature higher than usual. As a result, the temperature of the reactor inlet gas rises, causing a problem that abnormal heat generation occurs inside the reactor.

  Moreover, in the reactor with a quench of the said nonpatent literature 1, when the heat-transfer area of a quench part is small, the expected cooling effect cannot be acquired, and when cooling water is put into a quench part, the process side and The temperature difference from the cooling water side becomes large, which may cause damage to the equipment.

  Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide means for preventing abnormal heat generation of the reactor inlet gas.

  As a result of intensive studies to solve the above problems, the present inventors have found that when the temperature of the reaction product gas containing ethylene oxide led out from the reactor outlet during non-steady state rises, It has been found that abnormal heating of the gas at the inlet of the reactor can be prevented by directly introducing the cooling medium to any place up to the inlet of the exchanger. Based on the above findings, the present invention has been completed.

  That is, the above-described object is that the ethylene oxidation reaction vessel outlet or the ethylene oxidation reaction that generates a reaction product gas containing ethylene oxide by catalytic vapor phase oxidation of ethylene and a molecular oxygen-containing gas on a silver catalyst in an unsteady state. This can be achieved by a method of cooling the production equipment during the unsteady state, which comprises introducing a cooling medium into a connecting line connecting the outlet of the heat exchanger and the inlet of the heat exchanger.

  According to the present invention, abnormal heat generation of the ethylene oxidation reactor inlet gas can be suppressed / prevented.

It is a block diagram which mainly shows the structural example of an ethylene oxidation reaction process and an absorption process among the manufacturing processes of ethylene oxide which implement the method which concerns on one Embodiment of this invention. It is a block diagram which shows the structural example of the manufacturing process of ethylene glycol using the ethylene oxide obtained through the manufacturing process of ethylene oxide which implements the heat | fever recovery method which concerns on one Embodiment of this invention as a raw material.

  The present invention relates to an outlet portion of an ethylene oxidation reactor for generating a reaction product gas containing ethylene oxide by catalytic vapor phase oxidation of ethylene and a molecular oxygen-containing gas on a silver catalyst during an unsteady state. The present invention relates to a cooling method for manufacturing equipment in a non-steady state, which includes supplying a cooling medium to a connecting line that connects an outlet and an inlet of a heat exchanger. In the present invention, when the temperature of the reaction product gas containing ethylene oxide at the outlet of the ethylene oxidation reactor (also simply referred to as “reactor” in this specification) rises during an unsteady state, It is characterized in that the cooling medium is directly put into any place up to the exchanger inlet (the outlet of the ethylene oxidation reactor or the connecting line). According to this method, since the reaction product gas derived from the reactor outlet that generates heat during non-stationary conditions is directly cooled, the temperature of the subsequent gas, that is, the gas until reaching the reactor inlet via the heat exchanger is increased. Effectively suppressed and prevented. Thereby, abnormal heat generation of the reactor inlet gas at the time of unsteady state can be prevented. Therefore, according to the method of the present invention, the raw material gas or reaction product gas forms an explosive combustible in the ethylene oxidation reactor or line (piping), the container internal pressure rises, or the temperature rises. It is possible to control and prevent production equipment from being damaged and causing major damage to the production equipment, and the production equipment can be operated safely and reliably. Further, as will be described in detail below, since the cooling medium charging means is a simple facility, it is not necessary to provide an excessive amount of equipment for an unsteady time when the usage frequency is low, and an ethylene oxidation reactor or line ( It is possible to effectively prevent polymerization of raw materials and reaction products, formation of explosive combustibles, abnormal increase in the internal pressure of the ethylene oxidation reactor, damage to the ethylene oxidation reactor and line (piping) due to the abnormal increase in the piping). Therefore, the manufacturing apparatus can be operated very easily from a safe place without causing a large damage to the manufacturing apparatus. In particular, since ethylene oxide burns even in the absence of a catalyst and a rapid temperature rise tends to occur, the method of the present invention is particularly effective from the viewpoint of safe operation of the manufacturing apparatus.

  In the present specification, the term “non-stationary time” has the same definition as commonly used in the art. Specifically, it means a process leading to continuous production at the start-up in the process of manufacturing ethylene oxide; until a stop such as a normal stop or an emergency stop; and an abnormal situation. For example, the process leading to continuous production at the time of start-up in the process of manufacturing the product includes preheating the ethylene oxidation reactor; There are times when the reactor is inspected and the catalyst is replaced after the stoppage; until the emergency stop (including when an abnormal situation occurs), it may be due to equipment failure or content error (abnormal reaction) due to equipment failure or operation error. , When temperature and pressure control and reaction control become difficult; during a power failure (an aspect during an abnormal situation); due to a power failure, transfer means (pumps, etc.), stirring / mixing means (especially motors, etc.), heat exchange Examples include cases where a means (such as a heater) or an automatic control system stops functioning, but should not be limited to these. When the method of the present invention requires urgency particularly in an unsteady state, for example, when an unsteady state is detected or after the apparatus is urgently stopped in an unsteady state, the raw material gas from the heating medium in the heat exchanger ( The abnormal reaction proceeds due to the residual heat of ethylene and molecular oxygen-containing gas) and reaction product gas (especially ethylene oxide) and the residual heat of these gases themselves, and the abnormal reaction product is discharged from the container through a normal discharge route. There are serious problems such as the equipment becoming unusable and the equipment becoming unusable, and the internal temperature rising due to the progress of abnormal reactions may cause an explosion or damage to the equipment. This is a particularly effective and effective method when it may occur.

  Therefore, the method of the present invention is preferably performed as soon as possible in the event of an unsteady state, particularly an emergency or abnormal situation. Therefore, it is desirable that a detection means for detecting the unsteady state is provided. Such detection means include means for detecting that an internal abnormality of the reactor (abrupt temperature rise or pressure increase due to abnormal reaction or the like) has occurred, an abnormality in the reactor (malfunction or operation error, etc.) Means for detecting the occurrence of breakage, temperature fluctuation, pressure fluctuation, flow fluctuation, etc., means for detecting the occurrence of a power failure, abnormalities in equipment or equipment using heat exchanger (abnormal reaction) Means for detecting the occurrence of sudden temperature rises or pressure rises due to etc., abnormalities in equipment or devices that use heat exchangers (damage of devices due to malfunctions or operational mistakes, temperature fluctuations, pressure fluctuations) And a means for detecting the occurrence of flow rate fluctuations). As a means for detecting the occurrence of a power failure, for example, a voltage detector can be cited, and a backup system that automatically switches to an emergency power supply by detecting the occurrence of a power failure is obtained. It is preferable. Examples of means for detecting that an abnormality has occurred in the reactor or in the equipment or apparatus using the heat exchanger include, for example, a temperature detector (temperature sensor), a pressure detector (pressure sensor), pH Examples include a detector (pH sensor), a gas leak detector, a liquid leak detector, a liquid level detector (liquid level sensor), and a flow rate detector (flow rate sensor). By detecting that an abnormal reaction or the like has occurred by these, the apparatus can be urgently stopped or the raw material gas or the reaction product gas can be extracted with a pump, and at the same time, the method of the present invention can be carried out. It is preferable to construct a system that can operate with either a normal power supply or an emergency power supply as a drive power supply. Examples of means for detecting that an abnormality has occurred in the reactor itself include a temperature detector (temperature sensor), a pressure detector (pressure sensor), a pH detector (pH sensor), and a gas leak detector. , Liquid leak detectors, liquid level detectors (liquid level sensors), flow rate detectors (flow rate sensors), and the like. A system that can operate with either a normal power supply or an emergency power supply as a drive power supply is constructed so that an emergency stop of the equipment can be automatically performed and the method of the present invention can be automatically executed by detecting a device abnormality. It is preferable to keep it. In addition, the temperature detector (temperature sensor) is used in the same way as described above in the process leading to continuous manufacturing at the start-up in the process of manufacturing the product and in the process leading from the continuous manufacturing process to the normal stop. ), Detection means (pressure sensor (pressure sensor), pH detector (pH sensor), gas leak detector, liquid leak detector, liquid level detector (liquid level sensor), flow rate detector (flow rate sensor), etc. Furthermore, it is preferable that a control means) is provided. This is because it is possible to automatically control a series of operations from start-up to normal stop. Among these, it is more preferable that a means for measuring the temperature of the reaction product gas derived from the reactor is provided. That is, it is preferable that the method of the present invention further includes measuring the temperature of the reaction product gas derived from the ethylene oxidation reactor to detect an unsteady time. In general, in unsteady states, especially in emergency situations and abnormal situations, it is recognized that the reaction proceeds abnormally and the temperature at the ethylene oxidation reactor outlet (the temperature of the reaction product gas derived from the reactor) rises. It is done. For this reason, measuring the temperature of the reaction product gas derived from the ethylene oxidation reactor is effective in that an unsteady state can be detected at an early stage.

  Embodiments of the present invention will be described below. In addition, this invention is not limited only to the following embodiment. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

  In the present specification, “X to Y” indicating a range means “X or more and Y or less”, and “weight” and “mass”, “wt%” and “mass%”, “part by weight” and “ “Part by mass” is treated as a synonym. Unless otherwise specified, measurement of operation and physical properties is performed under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50%.

  FIG. 1 is a block diagram mainly showing a configuration example of an ethylene oxidation reaction step and an absorption step in an ethylene oxide production process for carrying out a method according to an embodiment of the present invention.

  In this specification, the term “reaction product gas containing ethylene oxide” means a process in which ethylene is subjected to catalytic gas phase oxidation with a molecular oxygen-containing gas in the presence of a silver catalyst in an ethylene oxidation reactor (ethylene oxidation reaction step). It is sufficient if it is generated by. The technology of this catalytic gas phase oxidation reaction itself is widely known, and conventionally known knowledge can be appropriately referred to in the practice of the present invention. In addition, there is no restriction | limiting in particular in specific forms, such as a composition of reaction product gas. As an example, the reaction product gas is usually 0.5 to 5% by volume of ethylene oxide, in addition to gases such as unreacted oxygen, unreacted ethylene, product water, carbon dioxide, nitrogen, argon, methane, and ethane. It contains trace amounts of organic acids such as acetaldehyde aldehydes and acetic acid.

  Referring to FIG. 1, first, a raw material gas containing ethylene or molecular oxygen is pressurized by a blower 104, heated by a heat exchanger 105, and supplied to an ethylene oxidation reactor 107. The ethylene oxidation reactor 107 is usually performed in a multitubular reactor 106 having a number of reaction tubes filled with a silver catalyst. The reaction product gas generated in the ethylene oxidation reaction step is discharged from the outlet 120 of the ethylene oxidation reactor 107 and introduced into the heat exchanger 105 through a connection line 122 that connects the outlet 120 and the inlet 121 of the heat exchanger. Is done. Here, the reaction product gas is cooled by passing through the heat exchanger 105 and then supplied to an ethylene oxide absorption tower (hereinafter also simply referred to as “absorption tower”) 108. Specifically, the reaction product gas is supplied from the bottom of the absorption tower 108. On the other hand, an absorption liquid mainly composed of water is supplied from the top of the absorption tower 108. As a result, gas-liquid countercurrent contact is performed inside the absorption tower 108, and ethylene oxide (usually 99% by mass or more) contained in the reaction product gas is absorbed by the absorption liquid. In addition to ethylene oxide, ethylene, oxygen, carbon dioxide, inert gases (nitrogen, argon, methane, ethane, etc.), low-boiling impurities such as formaldehyde generated in the ethylene oxidation reaction process, high concentrations of acetaldehyde, acetic acid, etc. A substantial amount of boiling-point impurities are absorbed simultaneously. The temperature of the reaction product gas supplied to the absorption tower 108 is preferably about 20 to 80 ° C. Moreover, there is no restriction | limiting in particular about the composition of an absorption liquid, In addition to what has water as a main component, propylene carbonate as disclosed by Unexamined-Japanese-Patent No. 8-127573 may be used as an absorption liquid. Moreover, an additive may be added to the absorbent as necessary. Examples of the additive that can be added to the absorbing liquid include an antifoaming agent and a pH adjusting agent. As the antifoaming agent, any antifoaming agent can be used as long as it is inactive with respect to ethylene oxide and by-product ethylene glycol and has an antifoaming effect of the absorbing solution. A water-soluble silicone emulsion is effective because it is excellent in dispersibility in an absorbing solution, dilution stability, and thermal stability. Moreover, as a pH adjuster, the compound which can melt | dissolve in absorption liquids, such as hydroxide and carbonate of alkali metals, such as potassium and sodium, is mentioned, for example, Potassium hydroxide or sodium hydroxide is preferable. In addition, pH of an absorption liquid becomes like this. Preferably it is 5-12, More preferably, it is 6-11.

As the absorption tower 108, a plate tower type or packed tower type absorption tower can be used. The operating condition of the absorption tower 108 is that the ethylene oxide concentration in the reaction product gas is 0.5-5% by volume, preferably 1.0-4% by volume, and the operating pressure of the absorption tower 108 is 0.2-4. The pressure is 0 MPa gauge, preferably 1.0 to 3.0 MPa gauge. The absorption operation is more advantageous at higher pressures, but the possible values can be determined according to the operating pressure of the oxidation reactor. Further, the molar flow rate ratio (L / V) of the absorbing liquid to the reaction product gas is usually 0.30 to 2.00. The space linear velocity (GHSV [NTP]) in the standard state of the reaction product gas is usually 400 to 6000 h ⁻¹ .

  Gases containing ethylene, oxygen, carbon dioxide, inert gases (nitrogen, argon, methane, ethane, etc.), aldehydes, acidic substances, etc. that have not been absorbed by the absorption tower 108 are absorbed through the conduit from the top of the absorption tower 108. It is discharged as tower exhaust gas. A certain amount of the absorption tower exhaust gas is increased in pressure by the blower 104 and then recycled to the ethylene oxidation reactor 107. Here, the ethylene oxidation reaction step is usually performed under pressure (a pressure of about 1.0 to 3.0 MPa gauge). For this reason, before the exhaust gas (absorption tower exhaust gas) from the tower top of the absorption tower 108 is circulated to the ethylene oxidation reaction step, it is necessary to raise the pressure using a pressure raising means such as the blower 104.

  As shown in FIG. 1, in a preferred embodiment of the ethylene oxide production process according to the present invention, when the absorption tower exhaust gas discharged from the top of the absorption tower 108 is circulated to the ethylene oxidation reactor 107, By passing through the heat exchanger 105, heat exchange is performed with the reaction product gas before being supplied to the absorption tower 108. Thus, the temperature of the absorption tower exhaust gas circulated to the ethylene oxidation reactor 107 is raised, and the reaction product gas supplied to the absorption tower 108 is cooled.

  Further, another fixed amount of the absorption gas from the absorption tower is introduced into the carbon dioxide absorption tower 109 via the blower 104, and after carbon dioxide is absorbed and separated, it is recycled to the ethylene oxidation reactor 107. In this way, the reaction product gas circulated from the absorption tower 108 and the carbon dioxide absorption tower 109 is replenished with ethylene, methane, etc. to adjust the gas composition, and then introduced into the ethylene oxidation reactor 107 as a raw material gas and continuously. Perform oxidation reaction.

  On the other hand, the absorption liquid that has absorbed ethylene oxide in the absorption tower 108 is withdrawn as the bottom liquid of the absorption tower 108 and is supplied to the subsequent ethylene oxide purification step (not shown). Specifically, the absorption liquid that has absorbed ethylene oxide in the absorption tower 108 is sent to an ethylene oxide diffusion tower (not shown), and the bottom of the ethylene oxide diffusion tower is heated to dissipate ethylene oxide from the aqueous solution (a diffusion step). An aqueous solution substantially free of ethylene oxide obtained from the bottom of the ethylene oxide diffusion tower is circulated and used as an absorbing solution. On the other hand, in addition to ethylene oxide, water, carbon dioxide, inert gas (nitrogen, argon, methane, ethane, etc.) obtained from the top of the ethylene oxide stripping tower, low boiling impurities such as formaldehyde and high boiling impurities such as acetaldehyde, acetic acid, etc. The contained diffused matter is purified through each of the dehydration step, light fraction separation step and heavy fraction separation step (rectification step). Thereby, a high purity ethylene oxide is obtained.

  The high-purity ethylene oxide thus obtained may be shipped as a final product as it is, or may be used as a raw material for producing ethylene glycols. FIG. 2 is a block diagram showing a configuration example of an ethylene glycol production process using ethylene oxide obtained as a raw material through an ethylene oxide production process in which a heat recovery method according to an embodiment of the present invention is performed. The case where ethylene glycols are produced from the high-purity ethylene oxide obtained as described above will be briefly described with reference to FIG. As shown in FIG. 2, the recovered ethylene oxide is sent together with water to a hydrolysis reactor 291 to be reacted. Then, the ethylene glycol aqueous solution obtained by this hydrolysis reaction is sent to the concentration step 292 and then to the dehydration step 293 to evaporate the water. Then, it sends to the monoethylene glycol distillation tower 294, and isolate | separates monoethylene glycol from the tower top. Further, the bottom liquid of the monoethylene glycol distillation column 294 is sent to the diethylene glycol distillation column 295, and diethylene glycol is separated from the column top. Further, the bottom liquid of the diethylene glycol distillation column 295 is sent to the triethylene glycol distillation column 296, and the triethylene glycol is separated from the column top. (For example, refer to JP 2001-316308 A). Thus, when ethylene glycols are produced from ethylene via ethylene oxide, operations such as rectification operation of ethylene oxide, concentration dehydration operation of by-produced ethylene oxide, and rectification operation of various ethylene glycols are required. And a large amount of heat source is consumed. In the ethylene oxide production process, in the absorption tower 108, ethylene oxide reacts with water to produce ethylene glycol. Therefore, a part of the absorption liquid in the absorption tower 108 may be extracted and concentrated using a multi-effect evaporator or a dehydrating distillation tower to obtain various ethylene glycol products (ethylene glycol purification step).

  Referring to Non-Patent Document 1, since a large amount of reaction heat is generated during the oxidation reaction between ethylene and oxygen in the ethylene oxidation reactor, the oxidation reaction heat generated in the ethylene oxidation reactor is transferred to the boiling transfer by hot water circulation. Remove by heat. In order to effectively use this heat of reaction, hot water is led to a gas-liquid separation tank, and saturated vapor is obtained in the gas-liquid separation tank. The generated saturated steam is used in the process, but the hot water remaining in the gas-liquid separation tank is supplied again to the reactor. At this time, the hot water used in the process as saturated steam is not supplied to the hot water circulation. The same amount of hot water used for the process as saturated steam is replenished from the cooling layer as boiler feed water.

  The method of the present invention is characterized in that the cooling medium is fed into an ethylene oxidation reactor outlet or a connection line connecting the ethylene oxidation reactor outlet and the heat exchanger inlet. Here, the “ethylene oxidation reactor outlet portion” means a portion (exit portion side) below the multitubular reaction tube provided in the ethylene oxidation reactor. Specifically, in FIG. The portion of the ethylene oxidation reactor 107 below (outlet side) of the multitubular reaction tube 106 indicated by the hatched portion A is indicated. In addition, in the present invention, when the cooling medium is introduced into the ethylene oxidation reactor outlet or the connection line at the unsteady time, the supply of the raw material gas (ethylene, molecular oxygen-containing gas) is performed before the introduction of the cooling medium. It is preferable to block.

  Here, the method for introducing the cooling medium into the outlet portion of the ethylene oxidation reactor is not particularly limited. For example, in FIG. 1, in a non-steady state, the valve 125 is opened, the cooling water feed pump 111 is operated, and the cooling medium is attached to the outer periphery of the ethylene oxidation reactor 107 outlet via the cooling water charging line 124. Liquid can be fed to the jacket 123. In addition to or in place of the above, cooling water may be directly applied to the outlet of the reactor 107. Similarly, the method for supplying the cooling medium to the connection line 122 is not particularly limited. For example, in a non-steady state in FIG. 1, the valve 127 can be opened and the coolant feed pump 110 can be operated to feed the coolant to the connection line 122 via the coolant input line 126. In addition to or instead of the above, cooling water may be directly applied to the connecting line 122. In addition, in the said form, although performed electrically (electrically) using a pump, it is not limited to the said form, For example, you may carry out by a manual type (manual). In addition, an electric solenoid valve or the like is in an open / closed state with pressurized air or the like during a power failure (not energized). Of course, the power supply may be secured with an emergency power supply in consideration of a power failure. Furthermore, for example, an emergency power supply is used in the event of a power failure or equipment failure, and the cooling medium is attached to the outer periphery of the outlet of the ethylene oxidation reactor 107 using a normal power supply when a normal power supply is ensured, such as a normal stop or emergency stop. The liquid may be fed to the jacket 123 or the connecting line 122 formed.

  In the present invention, the detection means in the non-steady state is not particularly limited, and the above-described means can be used, but a means for measuring the temperature of the reaction product gas derived from the ethylene oxidation reactor is provided. It is preferable that That is, it is preferable that the method of the present invention further includes measuring the temperature of the reaction product gas derived from the ethylene oxidation reactor to detect an unsteady time. In general, in a non-steady state, particularly in an emergency or abnormal situation, for example, the flow of gas decreases, the reaction proceeds abnormally, and the temperature at the ethylene oxidation reactor outlet rises. . For this reason, from the viewpoint of early detection, it is effective to detect the unsteady state by measuring the temperature of the reaction product gas derived from the ethylene oxidation reactor. For this reason, as shown in FIG. 1, it is preferable that the temperature detector (temperature sensor) Tx is installed in an ethylene oxidation reactor outlet or a connection line connecting the ethylene oxidation reactor outlet and the heat exchanger inlet. .

  In the present invention, the timing for starting the introduction (liquid feeding) of the cooling medium to the outlet of the ethylene oxidation reactor or the connection line is not particularly limited as long as it is unsteady. For example, as described above, when the temperature of the reaction product gas derived from the ethylene oxidation reactor is measured to detect an unsteady time, the temperature of the reaction product gas derived from the ethylene oxidation reactor is It is preferable to start charging the cooling medium when the temperature rises by more than + 40 ° C. from the specified value, and more preferable to start charging the cooling medium when the temperature rises by more than + 20 ° C. from the specified value. Here, the “specified value” is determined by the user for each production apparatus according to the reaction temperature, pressure, etc., and is not particularly limited. The “specified value” is usually a value set during steady operation. From the viewpoint of safety, it is preferable to perform an operation of shutting off the supply of the source gas and supplying the cooling medium immediately after detecting the unsteady time (abnormal heat generation has occurred) (for example, within several seconds). .

  Further, the timing for terminating the introduction (liquid feeding) of the cooling medium to the outlet portion of the ethylene oxidation reactor or the connection line is not particularly limited as long as it is determined that the abnormal heat generation can be sufficiently prevented. For example, as described above, when the temperature of the reaction product gas derived from the ethylene oxidation reactor is measured to detect an unsteady time, the temperature of the reaction product gas derived from the ethylene oxidation reactor is It is preferable to end the charging of the cooling medium when it is cooled to a specified value or less. If the temperature of the reaction product gas is lowered to the above-described temperature, the possibility of abnormal heat generation again is very low or not.

  In the present invention, when the supply of the raw material gas is interrupted before the cooling medium is supplied, the timing for interrupting the supply of the raw material gas is not particularly limited as long as it is before the supply of the cooling medium. For example, in the above embodiment, when the temperature of the reaction product gas derived from the ethylene oxidation reactor is increased by 15 ° C. or more from a specified value, it is preferable to shut off the supply of the raw material gas, and 10 ° C. or more from the specified value. It is more preferable to shut off the supply of the raw material gas at the time of rising. Thereby, abnormal heat generation can be prevented more effectively and earlier. In the method of the present invention, it is preferable that the inert gas is circulated in the reactor instead, even when the supply of the raw material gas is shut off. Generally, when the raw material gas is stagnant, the risk of explosiveness increases. For this reason, the raw material gas is also maintained in a fluid state by the flow of the inert gas. Moreover, local temperature rise in the reactor can be suppressed / prevented by the flow of the inert gas.

  The cooling medium that can be used in the present invention is not particularly limited as long as the reaction product gas can be quickly lowered to a temperature at which the above problem does not occur in a non-steady state. Specific examples include clean water, industrial water, boiler feed water, pure water, rain water, well water (ground water), and cooling water such as sea water. Of these, boiler feed water and pure water are desirable from the viewpoints of handling, safety, economy, environmental impact, and post-cooling treatment. Further, the temperature of the cooling medium is not particularly limited as long as the temperature of the reaction product gas derived from the ethylene oxidation reactor can be lowered to a predetermined temperature (preferably, a temperature equal to or lower than the above-described temperature).

  Further, such a cooling medium (preferably, cooling water) may be directly supplied from the water or industrial water through a pipeline, or a water storage tank or the like is installed and supplied from the water storage tank or the like. It may be. In particular, when supplying water from industrial water or water storage tanks, it may be supplied by a liquid pump. However, in order to provide a stable supply even during a power outage, an external power supply (emergency power supply) is required only when the emergency engine is started. It is preferable to use a liquid feed pump that can be started (driven) and then operated by the emergency engine. In addition, in the case of a water tank, when the equipment scale is large and a large amount of cooling medium is required, in order to secure the required amount of cooling medium, the water tank will be enlarged and the equipment will be used less frequently. Therefore, the cooling medium may be stored in an underground tank or the like. By doing so, the above-ground part can be effectively utilized. Therefore, an apparatus such as a liquid supply pump for a cooling medium used in an unsteady state may be similarly installed in the underground space.

  In addition, regarding the conditions for charging the cooling medium to the reactor outlet or the connection line during non-stationary conditions, there are restrictions on the power supply (whether normal power supply can be used during normal stop or abnormal reaction, power failure or equipment It cannot be defined uniquely because it depends on whether or not a normal power supply can be used such as when there is an abnormality), the intended use, the scale of the equipment, and whether or not the handling fluid is withdrawn to an underground tank or the like during non-stationary conditions. If it is possible to avoid or stop an abnormality in the apparatus and the cooling medium can be stably fed by a liquid supply pump equipped with a normal power source or a portable engine, a gas (raw material gas or Reaction product gas) can be extracted from the apparatus. The input amount (flow rate) of the cooling medium may be determined in consideration of the temperature of the reaction product gas derived from the reactor, the heat transfer area, the amount of exchange heat, and the like.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

Example 1
An ethylene oxide production process including the ethylene oxidation reaction step and the absorption step shown in FIG. 1 was performed. The temperature of the gas at the inlet of the reactor during the above operation was measured over time, and the results are shown in Table 1. In Table 1, time indicates the time from the start of abnormal reaction.

That is, using the system shown in FIG. 1, a reaction product gas containing ethylene oxide was obtained by catalytic vapor phase oxidation of ethylene and a molecular oxygen-containing gas on a silver catalyst. At this time, the flow rate of the circulating gas in the reactor was 2000 Nm ³ / min, the reactor outlet temperature during operation was 203 ° C., and the reactor inlet temperature was 181 ° C. Five seconds after the start of the abnormal reaction, the reactor outlet temperature rose by 9 ° C., so the supply of the raw material gas was shut off. Since the reactor outlet temperature rose 20 ° C. 8 seconds after the start of the abnormal reaction, boiler feed water (130 ° C.) was supplied at 200 L / min from the cooling water charging line 126 in FIG. Due to the cooling effect, the temperature at the inlet of the reactor 107 changed over time as shown in Table 1. At this time, the exothermic temperature of the reactor inlet gas was as shown in Table 1, and it did not become higher than the exothermic temperature by cooling. From this result, it is considered that the abnormal heat generation of the ethylene oxidation reactor inlet gas can be effectively suppressed / prevented by using the method of the present invention.

Comparative Example 1
In Example 1, the operation of Example 1 was repeated except that the connection line was not cooled. The temperature of the gas at the inlet of the reactor during the above operation was measured over time, and the results are shown in Table 1. In this case, 90 seconds after the start of the abnormal reaction, the reactor inlet temperature exceeds the exothermic temperature, and the reactor inlet gas generates abnormal heat.

104 ... Blower,
105 ... heat exchanger,
106 ... multi-tube reactor,
107 ... ethylene oxidation reactor,
108 ... absorption tower,
109 ... carbon dioxide absorption tower,
110, 111 ... cooling water feed pump,
122 ... connecting line,
125, 127 ... valves,
124, 126 ... Cooling water input lines.

Claims (3)

During unsteady coupling for connecting the inlet of the ethylene oxidation reactor exit to ethylene and molecular oxygen-containing gas to catalytic gas phase oxidation over a silver catalyst to produce a reaction product gas containing ethylene oxide and heat exchanger A method for cooling an ethylene oxide production apparatus during non-stationary operation, comprising introducing a cooling medium into a line.   The method according to claim 1, further comprising measuring a temperature of a reaction product gas derived from the ethylene oxidation reactor to detect an unsteady time. The method according to claim 1 or 2, wherein the charging of the cooling medium is performed by operating a cooling water feeding pump and feeding the cooling medium to the connecting line via a cooling water charging line.

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