SU44237A1 - The method of using the heat of reaction for the formation of ammonia or methanol - Google Patents

Description

The formation of ammonia from elements under high pressure in the presence of a catalyst is a highly exothermic reaction. The amount of heat released reaches 750-800 calories per kg of ammonia formed. With the formation of 1 kg of methanol, the amount of reaction heat exceeds 850-900 calories.

In modern synthesis columns, during one passage of gas through the catalyst, on average, about 20% of the total gas weight is converted into ammonia or methanol, which makes it possible to raise the temperature of 1 kg of the gas mixture due to the heat of formation by 120-150 °. If a heat exchanger for heat recovery is created in the synthesis column, providing a heat differential of 10–20 and putting it on a loss of 1-2, which is quite enough, then it is obvious that it can be used near reaction heat for outsiders for the process.

An example is the Nitrogen column with a heat exchanger size of 120 m, always operating with a bypass of 20-30 / c. The temperature of the gas inlet in the catalyst box is about 400. The capacity of the column is 1.4 from ammonia per hour. The heat of reaction is 780 calories per kg of formed

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ammonia. The amount of 8,000 KiJ4ac gas passing through the column. The bypass gas inside the column is heated from 15 to 400 ° C, therefore, the heat exchange unnecessarily recovers heat:

8000 0.9. 0.2 (400 - 15) 554400.

Here, 0.9 is the heat capacity of 1 kg of the gas mixture.

It should be borne in mind that the temperature of the gas leaving the column is still very high, -160-170.

Thus, even with a heat exchanger of 120 liters, as in the Nitrogen column, it is possible without detriment to the process to remove 554400 calories of heat per hour from the column. Creating a more intensive heat exchanger working at a lower temperature difference when the gas exits from it, for example: 40-15 25, where 15 ° is the temperature of the gas entering the heat exchanger, it will be possible to use up to 90% of the reaction heat, which in our example would be 1400 780. 0.9 980000 or 1140 kilowatt of power.

If we take the efficiency factor of machines for transforming energy into 30%, then the useful power will be 342 kilowatts.

The heat of reaction can be used to heat fresh gases,

arriving at pre-catalysis in such a way that it is preheated by heat exchange in the heat exchanger TI of the precontact A recuperator (see drawing), the fresh gas mixture enters the catalyst box of the synthetic column B, where it is heated to the required temperature of 400-450 ° and then returned to column A for formalization, where it passes through the catalyst mass, then to the heat exchanger TI where it is cooled. Circulating gases pass through the heat exchanger Gz.

The subject matter of the invention.

A method of using the heat of reaction for the formation of ammonia or methanol using two separate stages of catalysis: forcatalysis and final catalysis, characterized in that the fresh gas to be contacted is heated first before forcatalysis by the heat of the gases coming from the forcatalysis and then the heat of the final catalysis reaction.

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