KR100937373B1 - Temperature control method for fluidized bed reactor - Google Patents

Abstract

[PROBLEMS] To provide a temperature control method capable of more precisely controlling the temperature in the reactor when the gas phase exothermic reaction is carried out in a fluidized bed reactor.

[Measures] As a temperature control method when performing a gas phase exothermic reaction using a fluidized bed reactor having a normal heat exchanger tube, a control heat exchanger tube, and a temperature detector,

(i) removing heat by the normal heat removing tube and detecting a temperature in the fluidized bed reactor by the temperature detector,

(ii) When the detected temperature is out of the set temperature, the heat removal capacity of the adjusting heat exchanger tube is changed from 10% or less to 90% or more, or 90% or more to 10% or less of the adjustable range FS. And controlling the temperature in the fluidized bed reactor to a set temperature by changing at a rate of 0.1 FS / min or more.

Fluidized Bed Reactor, Vapor Exothermic Reaction, Temperature Control Method, Steady Heater, Regulated Heater, Temperature Detector

Description

TEMPERATURE CONTROL METHOD FOR FLUIDIZED BED REACTOR}

The present invention relates to a temperature control method for a fluidized bed reactor, and more particularly, to a temperature control method capable of more precisely controlling the temperature in the reactor when performing a gas phase exothermic reaction using a fluidized bed reactor. It is about.

Fluidized bed reactors are widely used for industrially producing monomers useful for producing various synthetic resins and synthetic fibers by vapor phase exothermic reactions. Representative examples of the gas phase exothermic reaction carried out industrially include sequential oxidation reactions such as partial oxidation reactions and ammonia oxidation in the presence of ammonia. In the sequential oxidation reaction, since the oxidative stability of the partial oxidation product which is the target product is generally not so large, the sequential reaction of the target product proceeds as the reaction proceeds, that is, the reaction conversion rate increases. As a result, complete oxidation products are increased and the selectivity of the desired product tends to be lowered. Therefore, the yield of the target product obtained as a product of a conversion rate and a selectivity will have the maximum value in any conversion rate. For example, Non-Patent Document 1 discloses that the yield is usually the highest when the conversion ratio is 85 to 95% with respect to the production of acrylonitrile by the ammonia oxidation reaction of propylene. Therefore, in order to produce the desired product economically and more advantageously, it is extremely important to control the conversion ratio of the reaction to the desired range. Of course, this is not limited to the oxidation reaction, but it can be considered that it holds for the general gas phase exothermic reaction.

On the other hand, one of the advantages of the fluidized bed reactor is that the heat transfer in the reactor is faster and the reaction temperature is relatively easier to control than other reactor types, for example, a fixed bed reactor. In performing a gas phase exothermic reaction using a fluidized bed reactor, a method of controlling the temperature in the reactor based on the temperature detected by a temperature detector installed in the reactor is generally used. For example, Patent Document 1 discloses a fluidized bed reactor and a fluidized bed reactor temperature control method capable of controlling the temperature by flowing a cooling medium at a variable speed in at least one heat removing tube and adjusting the flow rate thereof. In addition, Patent Document 2 discloses a method of controlling the temperature by adjusting the flow rate of a liquid to be mixed in steam at a substantially constant flow rate when supplying a mixture of a liquid and its vapor as a cooling medium.

[Nonpatent Literature 1] Tetsuo Tanaka, "Advanced Acrylonitrile Manufacturing Technology," Japan Chemical Industry Association, Japan Chemical Industry Association, October, 1983, p. 551-561

[Patent Document 1] WO 95/21692 Brochure

[Patent Document 2] US Patent No. 2,697,334

Here, the conversion rate of the raw material of the gas phase exothermic reaction depends on the activity of the catalyst, and the conversion rate increases with the increase of the catalyst activity. In addition, the catalytic activity depends on the reaction temperature, and with the exception of exceptions such as enzymatic reactions, the catalytic activity generally increases with the increase of the reaction temperature. In addition, for example, in the case of the oxidation reaction, it is clear that the total oxidation product (eg, CO ₂ ) is more stable when comparing the production energy of the partial oxidation product with the complete oxidation product. If it rises, it is obvious that the calorific value of the whole reaction system increases. This can also be thought of as a general vapor phase exothermic reaction.

Therefore, in the gas phase exothermic reaction, if the reaction temperature rises due to any cause, 1) the catalyst activity increases with the increase of the temperature, and 2) the sequential reaction proceeds as the conversion rate of the reaction increases with the increase of the catalyst activity. 3) the amount of actually reacted in the supplied raw materials increases, and as the contribution of more stable products increases with the progress of the sequential reaction, the calorific value per unit time of the entire reaction system increases, and 4) the reaction temperature as a result. Tends to indicate a cyclical behavior that increases. Of course, the case where the reaction temperature is lowered also shows the reverse circulating behavior, so in all cases, the temperature emanates at the local part of the reactor, causing a temperature distribution in the reactor, and in extreme cases, the temperature of the entire reactor is It may diverge and lead to thermal runaway of the reactor or reaction stop. Therefore, in the gas phase exothermic reaction, it is very important to finely control the reaction temperature in order not only to produce the target product more economically and more advantageously, but also to stably continue the reaction.

In this way, in consideration of the importance of temperature control in the gas phase exothermic reaction, conventional temperature control is not sufficient depending on the reaction, and further static temperature control is required. In view of the above circumstances, an object of the present invention is to provide a temperature control method capable of controlling the temperature in the fluidized reactor more stably when the gas phase exothermic reaction is performed in the fluidized bed reactor.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly examined about the said subject, and, as a result of the temperature control method at the time of performing gas-phase exothermic reaction using the fluidized bed reactor which has a normal heat exchanger tube, a control heat exchanger tube, and a temperature detector, (i) the said normal agent The step of removing heat by the heat pipe and detecting the temperature in the fluidized bed reactor by the temperature detector; (ii) When the detected temperature is out of a set temperature, the heat removal capacity of the regulated heat pipe is adjustable. By a process comprising adjusting the temperature in the fluidized bed reactor to a set temperature by varying from 10% or less to 90% or more, or from 90% or more to 10% or less, at an average rate of change of 0.1 FS / min or more. When the gas phase exothermic reaction was carried out in a fluidized bed reactor, it was found that the temperature in the reactor can be controlled more statically, thereby completing the present invention. .

That is, this invention is as follows.

[One]

A temperature control method when performing a gas phase exothermic reaction using a fluidized bed reactor having a normal heat exchanger tube, a control heat exchanger tube, and a temperature detector,

(i) removing heat by the normal heat removing tube and detecting a temperature in the fluidized bed reactor by the temperature detector,

(ii) When the detected temperature is out of the set temperature, the heat removal capacity of the adjusting heat exchanger tube is changed from 10% or less to 90% or more, or 90% or more to 10% or less of the adjustable range FS. Adjusting the temperature in the fluidized bed reactor to a set temperature by changing at a rate of 0.1 FS / min or more,

Temperature control method comprising a.

[2]

In the temperature range in which the gas phase exothermic reaction is carried out, the total heat of reaction is 50 to 2500 kJ / mol (raw material), and the partial differential coefficient relating to the temperature of the total heat of reaction is 0.2 to 40 kJ / mol (raw material) · K, The method as described in said [1].

[3]

 The said gas phase exothermic reaction is a gaseous-phase ammoxidation reaction which uses propane and / or propylene as a raw material, and the method as described in said [1] or [2] whose product of reaction is acrylonitrile.

[4]

The gas phase exothermic reaction is a gas phase oxidation reaction using at least one member selected from the group consisting of n-butane, 1-butene, 2-butene, butadiene, and benzene, wherein the product of the reaction is maleic anhydride. 1] or [2].

[5]

The said gas phase exothermic reaction is a gaseous ammonia oxidation reaction which uses i-butene and / or i-butane as a raw material, and the method as described in said [1] or [2] whose product of reaction is methacrylonitrile.

[6]

 The said gas phase exothermic reaction is gas phase oxidation reaction which uses o-xylene and / or naphthalene as a raw material, and the method as described in said [1] or [2] whose product of reaction is phthalic anhydride.

[7]

The said gas phase exothermic reaction is gas phase alkylation reaction which uses phenol and methanol as a raw material, and the method as described in said [1] or [2] whose product of reaction is 2, 6- xylenol and / or o-cresol.

[8]

The said gas phase exothermic reaction is gaseous ammonia oxidation reaction which uses methane and / or methanol as a raw material, and the method as described in said [1] or [2] whose product of reaction is hydrocyanic acid (HCN).

[9]

The said gas phase exothermic reaction is a gaseous-phase ammoxidation reaction which uses 1 or more types chosen from the group which consists of ethane, ethene, and ethanol as a raw material, and the method of said [1] or [2] whose product of reaction is acetonitrile.

[10]

A process for preparing the desired compound using a fluidized bed reactor having a normal heat exchanger tube, a control heat exchanger tube and a temperature detector,

(a) supplying a raw material to the fluidized bed reactor filled with a catalyst to perform a gas phase exothermic reaction,

(b) removing heat by the normal heat removing tube and detecting a temperature in the fluidized bed reactor by the temperature detector;

(c) When the detected temperature is out of the set temperature, the heat removal capacity of the adjustment heat exchanger tube is changed from 10% or less to 90% or more, or 90% or more to 10% or less of the adjustable range FS. Adjusting the temperature in the fluidized bed reactor to a set temperature by varying the speed at 0.1 FS / min or more

Manufacturing method comprising a.

According to the temperature control method of the present invention, when the gas phase exothermic reaction is performed in the fluidized bed reactor, the temperature in the fluidized bed reactor can be controlled more stably.

EMBODIMENT OF THE INVENTION Hereinafter, the best form (following this Example) for implementing this invention is demonstrated in detail. In addition, this invention is not limited to a following example, It can variously deform and implement within the range of the summary.

The temperature control method of the present embodiment is a temperature control method when performing a gas phase exothermic reaction using a fluidized bed reactor having a normal heat exchanger tube, a control heat exchanger tube and a temperature detector, and (i) heat removal by the normal heat transfer tube; In addition, the process of detecting the temperature in the said fluidized bed reactor by the said temperature detector, (ii) When the detected temperature is out of setting temperature, the heat removal ability of the said adjustment heat exchanger tube is made into 10% or less of the adjustable range FS. At least 90%, or at least 90% and at most 10%, changing at an average rate of change of 0.1 FS / min or more to adjust the temperature in the fluidized bed reactor to a set temperature.

The fluidized bed reactor in this embodiment has a normal heat exchanger tube, a control heat exchanger tube, and a temperature detector. As long as one or more temperature detectors, they may have two or more. The position at which the temperature detector is provided is not particularly limited as long as it is a place where the temperature of the reactor can be stably measured, and can be provided in a catalyst rich layer, a lean layer, a gas outlet, or the like depending on the purpose. There is no restriction | limiting in particular in the model of the temperature detector provided, The detector of the format normally used, for example, a thermocouple or a resistance thermometer, can be used.

The fluidized bed reactor has a normal heat exchanger tube and a regulated heat exchanger tube together with the temperature detector. The "normal heat removal tube" in a present Example is a heat removal tube normally used for the purpose of removing reaction heat and controlling the temperature in a reactor. The "regulated heat removal tube" is a heat removal tube for adjusting the temperature in a reactor to a preset temperature, when the temperature detected by heat removal with a normal heat exchanger tube is out of setting temperature.

The shape of the heat removal tube to be installed is not particularly limited as long as it can be appropriately installed in the reactor. However, from the availability of materials and the ease of processing, a combination of materials used for piping, that is, steel pipe and steel pipe coupling, is used. It is common to be constructed in a U-shape connected. There is no restriction | limiting in particular also in the material of a heat exchanger tube, According to the conditions used, namely, the temperature, pressure, presence or absence of corrosiveness of the contacting fluid, such as a cooling medium or a reaction gas, for example, JIS G-3454, G-3458 , A pipe material specified in G-3459, and a steel pipe coupling specified in JIS B-2311 or the like can be freely selected and used.

As the fluidized bed reactor, an upflow type in which the catalyst particles maintain a fluidized state is generally adopted by an upflow of gas introduced from the bottom of the reactor, but in the present embodiment, the downflow type is not limited to the above type. Or any other way.

[Step (i)]

Step (i) is a step of removing the temperature in the fluidized bed reactor by the temperature detector while removing the heat from the normal heat removal tube.

A normal heat removal tube is a heat removal tube normally used, and is used for the purpose of roughly adjusting a heat removal ability according to supply rate of a raw material, or according to the fall of the capability of a heat removal tube by contamination etc., The use / non-use can be switched. Therefore, in order to adjust the total amount of heat removal ability, it is preferable to install the heat removal tube of the capability which has a certain margin with respect to the required amount of heat removal, divided into several series. Here, a series means the group of the heat removal tube or heat removal tube which has the valve which can open and close the flow of a cooling medium in each, and can set use / nonuse separately. The heat removal capacity of the heat removal tube includes various areas such as the area in contact with the rich layer portion of the fluidized bed, the area in contact with the lean layer of the fluidized bed, the temperature of the catalyst bed, the type of the cooling medium passed through, the physical form, the temperature supplied, and the speed of supply. Dominated by factors The total amount of the heat removal capacity of the normal heat removal tube is not particularly limited as long as it is equal to or higher than the heat amount (necessary capacity) to be determined based on the amount of reaction heat generated, etc., but preferably 130% or more, more preferably 150% of the required capacity. As mentioned above, More preferably, it is 180% or more. From the standpoint of preventing excessive equipment, the total heat removal capacity of the normal heat removal tube is preferably 300% or less, more preferably 270% or less, even more preferably 240% or less of the required capacity. As the number of series of the normal heat pipe increases, the adjustment of the heat removal capacity tends to be easier, and therefore preferably 5 or more lines, more preferably 8 or more lines, even more preferably 10 or more lines, particularly preferably 16 Install the series or above. By appropriately switching the use / nonuse of these plural systems, the total amount of the heat removal capacity can be roughly adjusted and used.

The cooling medium passed through the normal heat exchanger tube is not particularly limited as long as it can achieve the required heat removal capability, but is preferably a liquid that evaporates at the operating temperature of the reactor, more preferably water, even more preferably 0.5 to Water pressurized to 5 MPa (gauge pressure). By using the liquid evaporated at the operating temperature of the reactor as a cooling medium, heat removal by latent heat of evaporation is used, so that the overall heat transfer coefficient of the heat removal tube can be relatively high. Therefore, the amount of heat removal per unit surface area of the heat removal tube is increased, and the required number of heat removal tubes can be reduced. In addition, the vapor of the obtained cooling medium can be used again as a cooling medium.

In addition, it is preferable not only to use a liquid as a cooling medium, but also to provide a heat removal tube using a gas as a cooling medium, and furthermore, to use a liquid as a cooling medium, a part of the evaporated cooling medium may be It is more preferable to provide the heat removal tube which collect | recovers as gas-liquid mixture flow and collect | recovers it as superheated steam using the generated steam further as a cooling medium.

In step (i), the above-mentioned normal heat exchanger tube is defrosted and the temperature detector detects the temperature in the fluidized bed reactor. In the case where a plurality of temperature detectors are provided in the reactor, one of them may be used, or two or more detectors may be selected to perform calculations such as averaging a plurality of detection temperatures.

[Step (ii)]

In the step (ii), when the detected temperature is out of the set temperature, the heat removal capacity of the adjusting heat exchanger tube is set from 10% or less to 90% or more, or from 90% or more to 10% or less of the adjustable range FS, It is a process of adjusting the temperature in a fluidized bed reactor to a preset temperature by changing at an average change rate of 0.1 FS / min or more.

Here, the "set temperature" is a temperature in the fluidized bed reactor in which the desired conversion rate and the yield of the desired product can be obtained in the gas phase exothermic reaction, and can be arbitrarily set according to the reaction to be carried out.

The adjustment heat removal tube in this process is for adjusting the amount of heat removal according to the difference between the temperature detected by the temperature detector and the set temperature. Among the plurality of heat removing tubes, which one is normally used (as a normal heat removing tube) and which one is used for adjustment (as an adjusting heat removing tube) may be determined in advance or may be appropriately set according to the type of gas phase exothermic reaction. have. In any case, from the viewpoint of uniformly removing the temperature in the reactor, it is preferable that the plurality of regulating heat removal tubes are in a position spaced apart from each other.

The heat removal capacity of the heat exchanger can vary depending on the area in contact with the rich layer portion of the fluidized bed, the area in contact with the lean layer portion of the fluidized bed, the temperature of the catalyst bed, the type, physical form, temperature supplied, and speed of supply of the cooling medium. Dominated by factors Therefore, in the adjustment of the heat removal capacity of the adjustment heat removal tube, among these various control factors, the capacity can be adjusted by changing one or more of the physical quantities which can be arbitrarily set, for example, the supply temperature and supply speed of a cooling medium. Moreover, the heat transfer area can be changed by increasing or decreasing the number of adjustment heat removal tubes used, and as a result, the heat removal ability as a whole can also be adjusted.

The cooling medium passed through the regulating heat pipe is not particularly limited as long as it can achieve the required heat removal capacity and can adjust the heat removal capacity of the heat pipe, but preferably a fluid which does not cause a phase change in the operating temperature of the reactor, more preferably. Preferably gas, more preferably gas pressurized to 0.2-5 MPa (gauge pressure), particularly preferably water pressurized to 0.2-5 MPa (gauge pressure). Since only sensible heat is used for the defrosting of the fluid which does not cause a phase change in the operating temperature of the reactor, the defrosting capacity of the regulating heat pipe is changed in proportion to the change in the supply speed of the cooling medium. Therefore, the heat removal ability of a heat removal tube can be adjusted more easily.

The distribution of heat removal amount of heat normally removed by the normal heat removal pipe and the heat removal by the control heat removal pipe is not particularly limited and may be arbitrarily designed and set so that the temperature in the reactor is stabilized, but it does not adversely affect the temperature control in the reactor. In the non-limiting range, it is desirable to remove as much heat as possible with a normal heat pipe. The amount of heat to be removed by the normal heat removal tube is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more of the amount of heat to be removed (total heat removal amount).

In the step (ii) of the present embodiment, when the detected temperature by the temperature detector is out of the set temperature, the heat removal capacity of the adjusting heat removal tube is adjusted from 10% or less to 90% or more, or 90% of the adjustable range FS. From above, it is important to change the average change rate at 0.1 FS / min or more. In other words, when the difference between the detected temperature and the set temperature is large, the average change speed of the heat removal capacity is increased, and when the difference with the set temperature is small, the control is not performed to decrease the average change speed. If there is a difference in temperature, it is always changed from 10% or less of the adjustable range FS to 90% or more, or 90% or more to 10% or less, at an average change rate of 0.1 FS / minute or more.

Temperature rise (fall) by changing the heat removal capacity of the adjustment heat exchanger tube from 10% or less of the adjustable range FS to 90% or more, or from 90% or more to 10% or less at an average change rate of 0.1 FS / min or more. Since it is estimated that further temperature rise (fall) by this and the divergence of temperature can be prevented, it becomes possible to control the temperature in a reactor more statically. Taking the case of temperature rise as an example, by changing the heat removal capacity in this way, the reaction proceeds as the temperature rises, and the heat removal capacity is increased before the chain phenomenon in which the temperature rises further by the generated reaction heat occurs. It is easy to keep the internal temperature close to the set temperature. Therefore, in the case of a reaction having a large partial differential coefficient relating to the total heat of reaction and the temperature of the total heat of reaction, it is particularly preferable to perform temperature control according to the method of the present embodiment.

Moreover, you may set so that the heat removal ability may be changed, when the difference between the temperature detected by the temperature detector and the set temperature is more than a predetermined value. Also in this case, of course, if the difference is more than a predetermined value, it is always changed from 10% or less of the adjustable range FS to 90% or more, or 90% or more to 10% or less at an average change rate of 0.1 FS / minute or more. The predetermined value may be a detection limit value of the temperature detector or may be set according to the characteristics of the gas phase exothermic reaction.

When the difference between the detected temperature and the set temperature is equal to or larger than a predetermined value, a control method by ON-OFF control of the heat removal capacity of the adjusting heat removal tube will be described. What is necessary is just to set a predetermined value suitably according to the magnitude | size of the partial differential coefficient regarding the temperature of reaction heat mentioned later, For example, in the case of the ammoxidation reaction of propane, it is preferable to set it as 0.30-2.0 degreeC, and in the case of the ammonia oxidation reaction of propylene It is preferable to set it as 0.50-3.0 degreeC. If the detected temperature is higher than or equal to the predetermined temperature, the average change rate is changed from 0.1% or less to 90% or more from 10% or less of the adjustable range FS. Change at an average change rate of 0.1 FS / min or more from 90% or more to 10% or less.

The adjustable range FS may be all of the adjustment ranges determined from the facility specifications of the adjustment heat removing tube, but the limited range therein may also be the adjustable range FS. That is, the adjustable range FS cannot be said to represent the state from not using the adjustment heat removal tube at all, or to the state of using it all. If a part of a plurality of adjustment heat exchanger tubes is normally used, the part which is using the part normally is 0 FS. On the other hand, unless a part of the adjustment heat removal tube is used for normal temperature control, for example, for emergency use, the state except the capability of the adjustment heat removal tube which is not used is 1.0 FS. There is no restriction | limiting in particular about the method of restricting the adjustment range of a heat removal capability, For example, when adjusting a heat removal capability according to a change of a flow volume, the maximum flow volume is limited by inserting the restriction orifice which adjusts the valve installed in a flow path. By setting an appropriate bypass path in the control valve, the adjustment range of the heat removal capacity can be restricted to a narrower range by a method of restricting the minimum flow rate or limiting the operating range of the control valve that is automatically adjusted.

The adjustment speed (change rate) of the heat removal capability of the adjustment heat removal tube is not necessarily constant, and may be changed by the result of the calculation used for adjustment or the response characteristics of the system. In this embodiment, the heat removal capacity is changed from 10% or less to 90% or more of the adjustable range FS, or from 90% or more to 10% or less, at an average change rate of 0.1 FS / min or more. The average change rate of heat removal ability is 0.1 FS / min or more, More preferably, it is 0.2 FS / min or more, More preferably, it is 0.25 FS / min or more. Although it does not restrict | limit especially as an upper limit of an average change rate, Preferably it is 6.0 FS / min or less, More preferably, it is 5.0 minutes or less from the point of limitation of stability of an automatic adjustment calculation, the operation speed of a control valve, etc. Preferably it is 4.0 FS / min or less. The average change rate of the heat removal capability can be adjusted by the calculation method used when adjusting a capability, the value of the control variable used by the calculation method employ | adopted, the operation speed of the control valve used, etc.

In addition, control of the heat removal capability of an adjustment heat removal tube can be set to be performed automatically. The calculation method used for automatically adjusting the capacity of the adjusting heat removal tube is not particularly limited as long as the average change rate of the heat removal capacity can be controlled to a predetermined range by selecting an appropriate control variable, for example, ON-OFF control, PID operation control, fuzzy operation control, and neural network operation control can be used, but it is common in the industry to use ON-OFF control or PID operation. For example, when using ON-OFF control, the predetermined average change rate can be obtained by adjusting the speed which drives a control valve. In the case of using PID arithmetic control, a predetermined average change rate is selected by appropriately selecting proportional band (P), integral time (I), and derivative time (D) according to the response characteristics of the system. You can get it.

Moreover, in order to perform the temperature control of the fluidized-bed reactor which performs a gaseous-phase exothermic reaction more stably, it is preferable that the amount of heat which is generated is kept as stable as possible, and heat transfer in a fluidized bed is made quick. In order to stably maintain the calorific value generated, it is preferable to keep the reaction conditions such as the feed rate of the raw material and the reaction pressure as constant as possible, so that the reaction can be made stable. In addition, in order to quickly perform heat transfer in the fluidized bed, it is necessary to maintain a good fluidized state of the fluidized bed. In general, the fluidized state of the fluidized bed is known to be governed by the gas flow rate (air column velocity), the particle diameter of the catalyst and the like. The gas flow rate is not particularly limited as long as the flow rate of the fluidized bed can be maintained satisfactorily. The catalyst can be used as it is as long as it is a catalyst used in a fluidized bed reactor, but the weight average particle diameter is preferably 20 to 100 µm, more preferably 30 to 80 µm, and still more preferably 40 to 60 µm. The content of fine powder (so-called good fraction) having a particle diameter of 44 µm or less is preferably 10 to 70% by weight, and furthermore, it is preferable to be classified as A particles in the Geldart powder classification map.

The gas phase exothermic reaction in the present embodiment is not particularly limited, and for example, a gas phase ammonia oxidation reaction for producing acrylonitrile using propane and / or propylene as a raw material, n-butane, 1-butene, 2-butene Gas phase oxidation reaction for producing maleic anhydride using at least one member selected from the group consisting of butadiene and benzene, and vapor phase ammoxidation for producing methacrylonitrile using i-butene and / or i-butane as raw materials. Reaction, gas phase oxidation reaction to produce phthalic anhydride with o-xylene and / or naphthalene as raw materials, gas phase alkylation reaction to produce 2,6-xyleneol and / or o-cresol from phenol and methanol as raw materials, methane And / or gaseous ammonia oxidation reaction for producing hydrocyanic acid (HCN) using methanol as a raw material.

The heat of reaction of the gas phase exothermic reaction varies depending on the reaction, for example, the reaction heat of the reaction of producing acrylonitrile from propylene and ammonia is 520 kJ / mol (propylene), the reaction of producing acrylonitrile from propane and ammonia. The heat of reaction of is 637 kJ / mol (propane). However, the actual reaction is a parallel reaction and a sequential reaction, and CO ₂ , CO, or other by-products are generated. The total heat of reaction including up to side reactions can be determined in consideration of the contribution rate (yield of each product) of the reactions in parallel.

For example, the heat of reaction of the reaction of propane burning to produce CO ₂ and water, or CO and water is 2,043 kJ / mol (propane) and 1,194 kJ / mol (propane) per mol of propane, respectively. When 100 mol of propane was reacted with ammonia and oxygen, 80 mol of propane reacted (reaction rate 80%), 50 mol acrylonitrile (yield 50%), 60 mol CO ₂ (20% yield), 30 mol Assuming that CO (yield 10%) is produced, the total heat of reaction under these conditions can be obtained as 637 x 0.5 + 2,043 x 0.2 + 1,194 x 0.1 = 846.5 (kJ / mol). As apparent from the calculation process, the total heat of reaction varies depending on the reaction rate of the raw material, the contribution rate (product distribution) of each parallel reaction, and the like, and thus depends on the reaction conditions. Although there is no restriction | limiting in particular in the total heat of reaction, when too much, it becomes difficult to control as the amount of heat to be defrosted increases, and since it leads to the temperature distribution in a reactor, and also in extreme cases, thermal runaway of a reactor, it selects reaction conditions. In doing so, it is desirable to make the total heat of reaction as small as possible. Specifically, per 1 mol of raw material to be supplied, preferably 50 to 2,500 kJ / mol (raw material), more preferably 70 to 2,000 kJ / mol (raw material), still more preferably 100 to 1,500 kJ / mol (raw material) It is better to select the reaction conditions so that

On the other hand, in the gas phase exothermic reaction, the stability of the target product is not very large, so that the sequential reaction of the target product proceeds as the reaction proceeds, that is, the reaction conversion rate increases, and the selectivity of the target product tends to decrease. have. Here, the reaction conversion rate depends on the activity of the catalyst, and the conversion rate increases with the increase of the activity. In addition, the activity of the catalyst depends on the reaction temperature, and in general, the activity rises with the increase of the reaction temperature. Therefore, if the reaction temperature rises for some reason, the reaction amount increases and the sequential reaction proceeds. This increases.

For example, when only the temperature rises by 5 degreeC, without changing other conditions from the conditions of the preceding paragraph, 82.5 mol of propane reacts in 100 mol of propane supplied (reaction rate 82.5%), and 50.3 mol of acrylonitrile (Yield 50.3%), 64.5 mol of CO ₂ (yield 21.5%), and 32.1 mol of CO (yield 10.7%) were produced so that the total heat of reaction under these conditions was 637 x 0.503 + 2,043 x 0.215 + 1 , 194 x 0.107 = 887.4 (kJ / mol). Since the rate of change of the total heat of reaction can be expressed as a partial differential coefficient with respect to the temperature of the total heat of reaction, in this case, it is determined as (887.4-846.5) ÷ 5 = 8.2 (kJ / mol · K) by linear approximation around this temperature. As can be seen from the calculation process, the partial differential coefficient with respect to the temperature of the total heat of reaction varies depending on the reaction temperature, the reaction rate of the raw materials, the contribution rate of each parallel reaction (the yield of each product), and the like, and thus depends on the reaction conditions. When the rate of change of the total reaction heat becomes too large, in terms of heat balance, the control of the reaction temperature becomes unstable, which leads to the cause of the temperature distribution in the reactor, and even to the extreme case of the thermal runaway of the reactor. In selecting the reaction conditions, it is preferable that the rate of change in the total heat of reaction be as small as possible. Specifically, the partial differential coefficient with respect to the temperature of the total heat of reaction is 0.2 to 40 kJ / mol (raw material) · K, preferably 0.5 to 30 kJ / mol (raw material) · K, more preferably 1 to 10 kJ / It is good to select reaction conditions so that it may become mol (raw material) * K.

[Method for Producing Target Compound]

In addition, the method for producing the target compound of the present embodiment is a method for producing the target compound using a fluidized bed reactor having a normal heat exchanger tube, a control heat exchanger tube and a temperature detector, (a) by supplying a raw material to the fluidized bed reactor filled with a catalyst Performing a gas phase exothermic reaction, (b) defrosting by the normal heat exchanger tube, and detecting the temperature in the fluidized bed reactor by the temperature detector, (c) the detected temperature is out of the set temperature. In this case, the fluidized bed reactor is changed by changing the heat removal capacity of the regulating heat pipe from 10% or less to 90% or more of the adjustable range FS or from 90% or more to 10% or less at an average change rate of 0.1 FS / min or more. And adjusting the internal temperature to the set temperature.

Step (a) is a step of supplying a raw material to a fluidized bed reactor filled with a catalyst to perform gas phase exothermic reaction. Here, as a gas phase exothermic reaction, the reaction similar to the above-mentioned gas phase exothermic reaction is mentioned, As the raw material, the thing similar to what was illustrated as a raw material of the said gas phase exothermic reaction is mentioned. Moreover, it does not specifically limit as a catalyst, What is normally used for gas phase exothermic reactions, such as a composite oxide catalyst, is mentioned.

In addition, the step (b) is a step of removing heat by the normal heat removing tube and detecting a temperature in the fluidized bed reactor by a temperature detector, and in the step (c), when the detected temperature is out of the set temperature, The heat removal capacity of the regulating heat pipe is changed from 10% or less to 90% or more of the adjustable range FS or from 90% or more to 10% or less at an average change rate of 0.1 FS / min or more to bring the temperature in the fluidized bed reactor to the set temperature. It is a process to adjust. Here, the step (b) and the step (c) correspond to the above-described steps (i) and (ii), respectively, and the target compounds can be produced by the same means. As a target compound, the thing similar to what was illustrated as a product of the above-mentioned vapor phase exothermic reaction can be mentioned.

1 shows an example of a fluidized bed reactor in this embodiment. In the reactor 1, the fluidized bed 2 by a catalyst is formed. When the raw material is oxidized using the fluidized bed reactor, a gas containing oxygen (usually air) is supplied from the oxygen introduction pipe 3 provided at the lower part of the reactor, and a gas containing the raw material is supplied from the raw material supply pipe 4. . The gas containing the reaction product is discharged out of the reactor 1 via the discharge pipe 5.

The heat removal tube located in the fluidized bed 2 is supplied with a liquid cooling medium or a gas cooling medium. The heat removal tube to which the liquid cooling medium is supplied is normally used, while the heat removal tube to which the gas cooling medium is supplied is normally used, and there are some used for adjustment. Hereinafter, the heat removal tube 6 which is normally used using liquid as a cooling medium is a normal heat removal tube 6, and the heat removal tube which is normally used using a gas as a cooling medium is a normal heat removal tube 7, and the remaining heat removal tube is adjusted It is called (8). In addition, although each heat removal pipe | line is shown only one series in FIG. 1, normally, each of several series is provided.

The normal medium heat pipe 6 using the liquid is supplied with the cooling medium from the gas-liquid separation vessel 9 by the pump 10. Part of the cooling medium is evaporated by the heat exchange between the fluidized bed 2 and the normal heat removal tube 6, and the gas liquid is returned to the gas-liquid separation vessel 9 as a gas-liquid two-phase flow. The portion where the cooling medium of the liquid is reduced by evaporation is further supplied through the cooling medium additional pipe 11.

Part of the cooling medium vapor generated in the normal heat removal tube 6 is supplied to the normal heat removal tube 7. By the heat exchange of the fluidized bed 2 and the normal heat exchanger tube 7, the cooling medium vapor becomes superheated steam and is supplied out of the system through the superheated steam discharge pipe 12.

The other part of the cooling medium vapor which generate | occur | produced in the normal heat exchanger tube 6 is supplied to the adjustment heat exchanger tube 8. As shown in FIG. The flow rate supplied can be finely controlled by the flow control valve 13. By heat exchange between the fluidized bed 2 and the control heat exchanger tube 8, the cooling medium vapor becomes superheated steam and is supplied out of the system through the superheated steam discharge pipe 14.

Moreover, the temperature detector 15 is provided in the fluidized bed 2. Although only one detector is shown in FIG. 1, normally, a plurality of detection units are provided by changing positions in the horizontal direction and the vertical direction. The temperature information detected by the temperature detector 15 is transferred to the temperature controller 16 and detected as the temperature of the fluidized bed. In the case where a plurality of detectors are provided, appropriate calculations, such as selecting and averaging the appropriate detectors, are used as the temperature of the fluidized bed.

In the regulator 16, a predetermined calculation is performed in accordance with the difference between the detected fluidized bed temperature and the set temperature, and the flow control valve 13 of the cooling medium is operated in accordance with the result of the calculation to adjust the heat exchanger tube 8. The ability of the adjustment heat removal tube 8 is adjusted by adjusting the flow volume of the cooling medium which passes through.

Of the cooling medium vapor generated in the normal heat removal tube (6), the surplus which is not used in the normal heat removal tube (7) and the control heat removal tube (8) is supplied out of the system through the saturated steam discharge pipe (17).

EXAMPLE

Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to a following example.

Example 1

In a fluidized bed reactor 1 having a diameter of 6.82 m having a form as shown in FIG. 80 tons were charged. 45,000 Nm 3 / Hr of air from the oxygen supply pipe 3 and a gas in which propane 3,000 Nm 3 / Hr and 2,700 Nm 3 / Hr were mixed from the raw material supply pipe 4 were supplied to produce acrylonitrile as the main product. .

In the fluidized bed 2, the normal heat removal tube 6 manufactured using the steel pipe of the outer diameter 114.3 mm prescribed | regulated to JIS G-3458, and the butt weld type 180 degree long elbow tube of the corresponding diameter prescribed | regulated to JIS B-2311. A series (total of 1,250m in total) was installed. 800 ton / Hr of 235 degreeC water is supplied to these normal heat exchanger tubes 6 from the gas-liquid separation vessel 9, and a part of it is evaporated, as a gas-liquid two phase flow of temperature 236 degreeC and pressure 3MPa (gauge pressure). Recovered. The evaporation rate at normal conditions was 5.8%.

In addition, 8 series of normal heat removal tubes 7 produced using the same material as that of the normal heat removal tubes 6 (total of the straight pipe portions were 225 m) were installed. 17 ton / Hr of saturated water vapor | steam of the temperature of 236 degreeC separated by the gas-liquid separation container 9 from the gas-liquid two-phase flow generated in the normal heat-heating tube 6 by the gas-liquid separation container 9, and a pressure of 3 MPa (gauge pressure) It supplied and collect | recovered as superheated steam of temperature 370-372 degreeC.

Moreover, 12 series of adjustment heat removal tubes 8 produced using the same material as the normal heat removal tube 6 (total of a straight pipe part are 370 m) were provided. In these adjustment heat exchanger tube 8, the flow volume of saturated steam of temperature 236 degreeC separated by the gas-liquid separation vessel 9 from the gas-liquid two-phase flow generated in the normal heat exchanger tube 6, and pressure 3MPa (gauge pressure) is adjusted. It supplied through the flow regulating valve 13, and it collect | recovered as superheated steam of 370-438 degreeC.

In the center of the fluidized bed, a K type thermocouple was provided as the temperature detector 15, and the thermostat 16 was converted into a temperature signal and detected. In the temperature controller 16, a sequence operation is performed using the DCS apparatus CS3000 manufactured by Yokogawa Denshi Co., Ltd. according to the difference between the detected reactor temperature and the set temperature, and the flow regulating valve 13 is operated according to the result. Opening and closing operation was performed, and the ability of the adjustment heat removal tube 8 was adjusted.

First, the set temperature given to the temperature controller 16 is set to 445.0 ° C and a predetermined value ± 0.3 ° C (temperature 444.7 ° C, 445.3 ° C for controlling), and is installed in the drive air (instrumental air) pipe provided to the driving device of the control valve. By adjusting one speed controller, the regulating valve changes the heat removal capacity of the adjusting heat exchanger tube from 100% to 0% of the adjustable range FS, or from 0% to 100%, at an average change rate of 3.0 FS / min. Was set to perform the automatic control operation. At this time, the fluctuation range of the reactor temperature was 444.5 to 445.5 ° C, and automatic control was possible in the range of ± 0.5 ° C with respect to the set temperature.

Example 2

In Example 1, the average change rate is 0.2 FS from 100% to 0% of the adjustable range FS, or from 0% to 100%, without changing the set temperature and the predetermined value. Automatic control operation was performed by setting the control valve to change to / min. At this time, the fluctuation range of reactor temperature was 444-446 degreeC, and automatic control was possible in the range of +/- 1 degreeC with respect to set temperature.

In this embodiment, a K-type thermocouple is provided as the temperature detector 15 in the center of the fluidized bed, and the thermostat 16 converts the thermoelectric power into a temperature signal and detects it. In the temperature controller 16, PID operation is performed using the DCS apparatus CS3000 manufactured by Yokogawa Denshi Co., Ltd. according to the difference between the detected reactor temperature and the set temperature, and according to the result, the flow regulating valve 13 The opening degree was adjusted and the ability of the adjustment heat exchanger tube 8 was adjusted.

Example 3

PID operation is performed by the DCS apparatus so that the heat removal capacity of the adjusting heat exchanger tube 8 is changed from 100% to 0% of the adjustable range FS, or from 0% to 100%, at an average change rate of 3.0 FS / min. The ammoxidation reaction of propane was carried out in the same manner as in Example 1 except that control variables (P: proportional band, I: integration time, D: derivative time) were set and automatic control operation was performed. At this time, the fluctuation range of the reactor temperature was 444.5 to 445.5 ° C, and automatic control was possible in the range of ± 0.5 ° C with respect to the set temperature.

Example 4

The embodiment except that the control variable was set to change the heat removal capability of the adjustment heat removal tube 8 from 100% to 0% of the adjustable range FS, or from 0% to 100%, with an average change rate of 0.2 FS / min. In the same manner as in 3, automatic control operation was performed to carry out ammonia oxidation of propane. At this time, the fluctuation range of reactor temperature was 444-446 degreeC, and control was possible in the range of +/- 1 degreeC with respect to set temperature.

Example 5

In the same fluidized bed reactor as in Example 1, 105 tons of a composite oxide catalyst containing 40% of a fine particle having an average particle diameter of 60 μm and a particle diameter of 44 μm or less composed of vanadium and phosphorus was charged. 70,000 Nm 3 / Hr of air was supplied from the oxygen supply pipe 3 and 2,950 Nm 3 / Hr of n-butane was supplied from the raw material supply pipe 4, and maleic anhydride was produced as the main product.

The set temperature given to the temperature controller 16 is set to 452.5 ° C. and a predetermined value is ± 0.2 ° C. (controlled temperature 452.3 ° C., 452.7 ° C.), and is provided in the drive air (instrument air) pipe provided to the drive device of the control valve. By adjusting the speed controller, the control valve is automatically set to change the heat removal capacity of the adjusting heat exchanger tube from 100% to 0% of the adjustable range FS, or from 0% to 100%, with an average change rate of 3.0 FS / min. Control operation was performed. At this time, the fluctuation range of the reactor temperature was 452.1 to 452.9 ° C, and automatic control was possible in the range of ± 0.4 ° C with respect to the set temperature.

Example 6

In the same fluidized bed reactor as in Example 1, 300 tons of the composite oxide catalyst containing 40% of a fine particle having an average particle diameter of 50 µm and a particle diameter of 44 µm or less composed of iron and vanadium were charged. 50,000 Nm <3> / Hr of mixed gas of methanol and phenol was supplied from the raw material supply pipe 4, and o-cresol and 2, 6- xylenol were manufactured as main products.

Drive air (instrument air) given to the drive device of a control valve by making the set temperature given to the thermostat 16 into 333.0 degreeC and predetermined value ± 0.2 degreeC (temperature 332.8 degreeC to control, 333.2 degreeC). By adjusting the speed controller installed in the piping, the regulating valve is configured to change the heat removal capacity of the adjusting heat exchanger tube from 100% to 0% of the adjustable range FS, or from 0% to 100%, at an average change rate of 3.0 FS / min. Was set to perform the automatic control operation. At this time, the fluctuation range of the reactor temperature was 332.6 to 333.4 ° C, and automatic control was possible in the range of ± 0.4 ° C with respect to the set temperature.

Comparative Example 1

(1) Reaction Example 1

 In Example 1, the heat removal capability of the adjustment heat exchanger tube 8 is changed from 100% to 0% of the adjustable range FS, or from 0% to 100% without changing the set temperature at an average change rate of 0.05 FS / min. The control valve was set to change, and automatic control operation was performed. At this time, the reactor temperature continued to diverge and automatic temperature control was impossible.

(2) Reaction Example 2

When the gas phase exothermic reaction was carried out under the same conditions as in reaction example 1, the reactor temperature continued to diverge, and automatic temperature control was not possible.

As shown in Reaction Examples 1 and 2, the ammonia oxidation reaction of propane was performed a plurality of times under the same conditions, but the temperature in the fluidized bed was diverted in either the direction of rising or falling, so that temperature control was impossible in each of the implementations. .

Comparative Example 2

(1) Reaction Example 1

Without changing the set temperature, the speed of the regulating valve is changed so that the heat removal capacity of the adjustment heat exchanger tube 8 changes from 100% to 0% of the adjustable range FS, or from 0% to 100%, at an average change rate of 0.05 FS / min. Maleic anhydride was produced in the same manner as in Example 5 except that the controller was set. At this time, the reactor temperature continued to diverge and automatic temperature control was impossible.

(2) Reaction Example 2

When the gas phase exothermic reaction was carried out under the same conditions as in reaction example 1, the reactor temperature continued to diverge, and automatic temperature control was not possible.

 As shown in Reaction Examples 1 and 2, the oxidation reaction of n-butane was carried out a plurality of times under the same conditions, but the temperature in the fluidized bed diverged in either the direction of rising or falling, so that temperature control was impossible in each of the implementations. did.

Comparative Example 3

(1) Reaction Example 1

In Example 6, the heat removal capacity of the adjustment heat exchanger tube 8 is changed from 100% to 0% of the adjustable range FS, or from 0% to 100% without changing the set temperature at an average change rate of 0.05 FS / min. The speed controller of the regulating valve was set to change, and automatic control operation was performed. At this time, the reactor temperature continued to diverge and automatic temperature control was impossible.

(2) Reaction Example 2

When the gas phase exothermic reaction was carried out under the same conditions as in reaction example 1, the reactor temperature continued to diverge, and automatic temperature control was not possible.

As shown in Reaction Examples 1 and 2, the alkylation reaction of phenol was carried out a plurality of times under the same conditions, but the temperature in the fluidized bed was diverted in either the direction of rising or falling, so that temperature control was impossible in all of the implementations.

As is apparent from the above results, the gas phase exothermic reactions of Examples 1 to 6 using the temperature control method of the present embodiment were controlled to remain in a certain range without the divergence of the temperature in the reactor either rising or falling.

 On the other hand, in the gas phase exothermic reaction of Comparative Examples 1 to 3, since the average change rate of the heat removal capacity of the regenerative heat exchanger tube is not 0.1 FS / min or more, the temperature in the reactor rises or falls as the reaction proceeds. Divergence, temperature control in the reactor was difficult.

According to the present invention, it is possible to statically control the temperature of a fluidized bed reactor widely used when industrially producing monomers useful for producing various synthetic resins and synthetic fibers, and in the temperature range where the catalyst is at the highest yield, Can operate stably for a long time.

1 shows an example of a fluidized bed reactor in the present embodiment.

[Explanation of symbols on the main parts of the drawings]

1 fluid bed reactor, 2 catalyst fluidized beds, 3 oxygen introduction tubes,

4 raw material introduction pipe, 5 reaction generating gas discharge pipe,

6 Top heat tube, using cooling medium of liquid

7 Top heat pipe, using cooling medium of gas

8 fixed heat pipe, 9 gas-liquid separation vessel, 10 cooling medium transport pump,

11 cooling medium additional pipe, 12 superheated steam discharge pipe (for normal heat pipe),

13 cooling medium flow control valve (regulated heat pipe capability control valve),

14 superheated steam discharge pipe (for regulated heat pipe), 15 reactor temperature detector,

16 thermostats, 17 saturated steam discharge lines

Claims (10)

As a temperature control method when performing a gas-phase exothermic reaction using a fluidized bed reactor having a steady heat pipe, a controlled heat pipe and a temperature detector,  (i) removing heat by the normal heat removing tube and detecting a temperature in the fluidized bed reactor by the temperature detector,  (ii) When the detected temperature is out of the set temperature, the heat removal capacity of the adjusting heat exchanger tube is changed from 10% or less to 90% or more, or 90% or more to 10% or less of the adjustable range FS. Adjusting the temperature in the fluidized bed reactor to a set temperature by varying the speed at 0.1 FS / min or more Temperature control method comprising a. The method of claim 1, In the temperature range in which the gas phase exothermic reaction is carried out, the total heat of reaction is 50 to 2500 kJ / mol (raw material), and the partial differential coefficient relating to the temperature of the total heat of reaction is 0.2 to 40 kJ / mol (raw material) · K. Characterized in temperature control method. The method according to claim 1 or 2, The gas phase exothermic reaction is a gas phase ammonia oxidation reaction using at least one of propane and propylene as a raw material, and the product of the reaction is acrylonitrile. The method according to claim 1 or 2, The gas phase exothermic reaction is a gas phase oxidation reaction using at least one member selected from the group consisting of n-butane, 1-butene, 2-butene, butadiene, and benzene, wherein the product of the reaction is maleic anhydride. Temperature control method. The method according to claim 1 or 2, The gas phase exothermic reaction is a gas phase ammoxidation reaction using at least one of i-butene and i-butane as a raw material, and the product of the reaction is methacrylonitrile. The method according to claim 1 or 2, The gas phase exothermic reaction is a gas phase oxidation reaction using at least one of o-xylene and naphthalene as a raw material, and the product of the reaction is phthalic anhydride. The method according to claim 1 or 2, The gas phase exothermic reaction is a gas phase alkylation reaction based on phenol and methanol, and the product of the reaction is 2,6-xylenol, o-cresol, or 2,6-xylenol and o-cresol. Temperature control method. The method according to claim 1 or 2, The gas phase exothermic reaction is a gas phase ammonia oxidation reaction using at least one of methane and methanol, and the product of the reaction is hydrocyanic acid (HCN). The method according to claim 1 or 2, The gas phase exothermic reaction is a gas phase ammonia oxidation reaction using at least one member selected from the group consisting of ethane, ethene, and ethanol, and the product of the reaction is acetonitrile. A process for preparing the desired compound using a fluidized bed reactor having a normal heat exchanger tube, a control heat exchanger tube and a temperature detector, (a) supplying a raw material to the fluidized bed reactor filled with a catalyst to perform a gas phase exothermic reaction, (b) removing heat by the normal heat removing tube and detecting a temperature in the fluidized bed reactor by the temperature detector; (c) When the detected temperature is out of the set temperature, the heat removal capacity of the adjusting heat exchanger tube is averaged from 10% or less to 90% or more, or 90% or more to 10% or less of the adjustable range FS. Changing the temperature in the fluidized bed reactor to a set temperature by changing at a change rate of 0.1 FS / min or more Manufacturing method comprising a.

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