The method of preparation of the reactor for the preparation of formaldehyde

 

(57) Abstract:

The invention relates to the field of chemical technology and can be used in the manufacture of formaldehyde in the chemical, petrochemical and other industries.

The method of preparation of the reactor for the preparation of formaldehyde, which consists in the fact that in the reactor in multiple threads serves a coolant temperature of at least 200oC. the Main stream is passed through the first and sequentially through the remaining layers of the catalyst. The rest flows through all layers except the first catalyst and then through all succeeding layers.

The invention relates to the field of chemical technology and can be used in the manufacture of formaldehyde in the chemical, petrochemical, woodworking and other industries.

In industry formaldehyde receive two different ways: through the oxidation of methanol with oxygen by passing the source of the reaction gas successively through the several layers of the respective mainly zhelezorudnogo catalyst, and by oxidative dehydrin the both cases, the formaldehyde receive reactors, contains multiple layers of catalyst. And in both cases there is a need before you begin these reactors to warm up the catalyst layers to the temperature of the beginning of the reaction for the preparation of formaldehyde.

Thus, the known method of producing formaldehyde by oxidation of methanol in the presence of a catalyst containing the oxides of metals in two stages. In the first stage of the reaction gas, which consists of methanol and oxygen is passed through the catalyst located in the tube, outside the cooled coolant. Partially reacted in the first stage, the reaction gas is fed to the second stage, which consists in passing it through the catalyst bed operating under adiabatic conditions. Before operating the reactor in which the process is carried out, pre-heated to the temperature of the beginning of the reaction, the catalyst was located in the tubes, hot coolant circulating in the annular space of the catalytic reactor. When the pipes leak air which is in them is heated and then enters and heats the catalyst bed operating in the adiabatic regime. After preheating, in operating mode, the process podgotovki reactor is very energy-intensive [1]

There is also known a method of producing formaldehyde, which consists in the successive transmission of the methanol-oxygen mixture through four layers of catalyst based on metal oxides. All the catalyst layers work in adiabatic conditions. After passing through each layer of the gas mixture is cooled to 200 280oC [2]

The preparation of the reactor for the work in which this method is carried out, is carried out by the original sequential heating of the catalyst by an external power source (e.g. hot air) until the temperature of the beginning of the reaction in the first layer (200 280oC) with subsequent supply source of a reactive gas. Energy supply from the outside is as long as the temperature of the reacted mixture at the output of the last layer will not reach the values required for the implementation of autothermal mode (heating the initial mixture to a temperature of the beginning of the reaction, the reacted reaction mixture). This way by the greatest number of similar features with the proposed technical solution adopted for the prototype.

For consistent initial heating of the catalyst, as in the prototype, characterized by a slow warming of the subsequent word is but the beginning of the reaction) the last layer is heated only up to 150 170oC. If at this time to begin feeding source of the reaction gas in the reactor, low temperature last layer will not provide flow therein reactions and consequently the final product - formaldehyde received during this period will have a residual methanol content in excess of regulatory requirements.

If we continue the process of heating the layers to achieve the desired temperature (not lower than 200oC), including the last layer, you will need a large amount of energy and a significant period of time. The described method is the traditional [3, page 196] and is widely known for various chemical industries.

A task that does not solve the present invention is the reduction of energy consumption and the duration of the period of preparation of the reactor for operation, providing the receipt of the certified formaldehyde.

The task is achieved by the fact that the initial heating of the catalyst in the reactor preparation of formaldehyde until the temperature of the beginning of the reaction is carried out by passing through them inert to the catalyst gas temperature not lower than 200oC, not less than two concurrent threads: the main of them served in the first and follow the IU first, catalyst layer, and then sequentially through all other layers, the subsequent layer. The method is as follows. Through the reactor miss hot air or any inert towards the catalyst a gaseous coolant. The heated coolant out of the reactor from any suitable source of heat to a temperature not lower than 200oC. it is Then fed into the reactor in multiple threads. The main of them is sure to pass along the same path, which then undergoes reaction gas, i.e., through the first and then through the remaining layers of the catalyst. Parallel streams of fluid fed into the reactor in any places before catalyst, or directly in them. Threads can be, for example, only two primary and secondary, which can apply to any area of the reactor, but preferably before the last layer of the catalyst. In this case, simultaneously with the first, with the same speed greater than the speed of warming up the other layers will warm up and the last layer. In this case, when the temperature of the first and the last layer of 200 - 280oC reactor was transferred to the operating mode and begin to pass through it vhodnye the catalyst layers, located between the first and the last, are heated to the operating temperature at high speed. In the last layer, oxidation of the remaining methanol with oxygen, therefore, obtained at the outlet of the reactor formaldehyde in the initial period of operation of the reactor does not contain methanol, i.e., is suitable.

If there are more threads in the hot coolant speed heating of the reactor will increase with a significantly reduced energy consumption. Using the proposed method, it is possible to reduce the time of preparation of the reactor to work 5 times.

Example 1 (the prototype). In the reactor with four successive layers of catalyst for the initial heating of the layers is carried out by passing air quantity 30000 nm3/h, heated at start-up heat exchanger overheated up to 2500oC (20 ATM) vapor with a flow rate of 16 t/h Heating of the first layer of catalyst to the reaction start temperature 220 - 240oC continues for 12 h, the temperature of the fourth layer 120 130oC. In the case of the introduction of the reactor in operation at this point in the next 8 to 10 h there is incomplete conversion of methanol due to the low temperature on the last layer and, consequently, receive some of the topics the initial heating of the catalyst is carried out for 38 hours, until all the layers do not reach the temperature of the beginning of the reaction 220 240oC. This leads to increased consumption of superheated steam up to 576 tons

Example 3. The initial heating of the catalyst is accomplished by passing before the start of the air heated in the start-up heat exchanger superheated steam with a temperature of 250oC and a flow rate of 16 t/h Hot air enters the reactor by two parallel streams, the first of which, with the consumption of 20000 nm3/h passes through the first and sequentially through the remaining layers of the catalyst, and the second with a flow rate of 10000 nm3/h through the last layer of the catalyst. Heating the first and fourth layers of catalyst to 200oC 8 h After reaching this temperature is up for the production of standard formalin. Saving superheated steam during the initial warm-up is 480 so

Example 4. Similar to example 3, characterized in that the reactor has 5 consecutive layers. The initial heating of the catalyst is carried out analogously to example 3 except that the hot air postoi, the other three with the cost of 5000 nm3/h between 2, 3, 4 and 5 layers, respectively. The time needed to run the reactor with the production of standard formalin is 12 o'clock Savings superheated steam 450 so

The method of preparation of the reactor for the preparation of formaldehyde, comprising heating the catalyst to a temperature of the beginning of the oxidation reaction of methanol with oxygen by passing through them inert in respect to the catalyst carrier with a temperature not lower than 200oC, characterized in that the coolant fed into the reactor at least two concurrent threads: the main one is passed through the first and sequentially through successive layers of catalyst, and more served in any or in front of anyone, except the first, the catalyst layers, and then sequentially passed through this, and all subsequent layers of the catalyst.

 

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FIELD: industrial organic synthesis.

SUBSTANCE: formaldehyde is produced via oxidative dehydrogenation of methanol with air oxygen at high temperature on silver-containing in fixed-bed reactor enclosing gas stream distributor followed by absorption of resultant reaction gases to form methanolic formalin, which is further rectified. Gas stream distributor utilized is inert filling composed of geometrically shaped members 3-10 mm in diameter placed on grid mounted upstream of catalyst in the form of a bed 50 to 500 mm thick.

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6 cl, 1 dwg, 1 tbl

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2 cl, 4 ex, 1 tbl, 1 dwg

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SUBSTANCE: invention relates to a method of producing formaldehyde through dehydrogenation of methanol in the presence of an oxide Zn-Na containing catalyst at high temperature. Dehydrogenation of methanol is carried out through chemical conjugation in the presence of hydrogen peroxide taken in an amount which ensures its concentration in methanol of 0.8-1.5%, and in the presence of a catalyst which also contains silicon dioxide with the following initial composition of components, wt %: Na2O - 1.2-1.4; ZnO - 0.8-1.2; SiO2 - the rest, at 790-900C, mainly at 820-850C.

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2 cl, 6 ex

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SUBSTANCE: present invention relates to a method of producing methanol, involving feeding a first stream of hot hydrocarbon-containing gas into a reactor, feeding an oxygen-containing gas into the reactor, oxidation of the hot stream of hydrocarbon-containing gas in the reactor with oxygen from the oxygen-containing gas to form a stream of products containing methanol and formaldehyde; and transferring heat from the stream of products to the first stream of hydrocarbon-containing gas, extracting methanol from the stream of products and extracting CO2 and formaldehyde from the stream of products to form a reduced stream of products containing hydrocarbons through physical absorption thereof with an absorbent, wherein the first stream contains at least a portion of the reduced stream of products, as well as apparatus (versions) for realising said method.

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EFFECT: increased stability of the catalyst layer.

15 cl, 2 tbl, 5 ex

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