RU44066U1 - METHANOL SYNTHESIS REACTOR - Google Patents

Abstract

The proposed device relates to contact shelf devices used to produce methyl alcohol from synthesis gas. The reactor is a cylindrical apparatus with a length of 23900 mm and a diameter of 2800 mm with catalyst baskets located inside the housing, separated by heat exchangers or boilers, containing a remote control unit for the synthesis gas flow through the baskets, consisting of valves and temperature sensors functionally connected to each other, and their number less than the number of catalyst baskets at least one. The application of the proposed utility model allows to prevent premature failure of the catalyst, align the temperature profile along the entire length of the apparatus, and increase the productivity of the installation.

Description

The proposed device relates to contact devices used for large-scale production of methanol from synthesis gas.

Known [Nitrogen. 1994. No. 207. p.24-32] super-column (converter), representing a simple double tubular heat exchanger, in which the catalyst is loaded into the space between the inner and outer pipes (Figure 1).

The length of the pipes with the catalyst varies from 10 to 20 m, based on the design conditions for the synthesis loop and the size of the unit.

The heated synthesis gas enters the apparatus and, passing through the internal tubes connected to the bottom space, is additionally heated to the temperature of the reaction. After that, he goes to the annular region filled with a catalyst, and leaves the lower part of the apparatus. The catalyst is cooled by water to power the boilers, which circulates in the housing to produce medium-pressure steam, as well as gas in the apparatus.

This design has several advantages in terms of capital investment and energy efficiency. According to its creators, it can significantly increase the conversion of synthesis gas in one pass and achieve a productivity of 2500 tons of methanol per day.

Due to its large size (outer diameter 85 mm), the outer pipes in the supercolumn have greater mechanical strength compared to smaller pipes in isothermal reactors, which reduces the material consumption of the apparatus.

The disadvantages of this design include the complexity of loading the catalyst into the annulus and the high pressure drop during the passage of synthesis gas through the apparatus.

The prototype of the proposed utility model is a horizontal methanol synthesis column described in [G. Sioli, L. Bianchi, E. Filippi, F. Zardi. Chemical industry. 1997. No5. S.63-75].

It represents a horizontal cylindrical casing in which four catalyst baskets and intermediate heat exchangers or boilers are installed (Figure 2).

Each catalyst basket consists of the following elements:

- lattice coated with a wire mesh to hold the catalyst; it is fixed by the walls of the apparatus and the central support.

- two walls providing lateral retention of the catalyst at the ends of the shelves;

- a shield in the form of sectors stacked on top of the catalyst;

- a vertical cylindrical container in which a heat exchanger is enclosed, inserted directly into the wall separating two consecutive shelves.

The boilers have a TEMA "E" type housing layout and bundles of U-shaped pipes in which the vapor pressure can reach 25 bar.

Gas / gas heat exchangers - straight pipe and floating head designs. Both heat exchangers and boilers are enclosed vertically in their housings and are attached directly to the housing under pressure using flanges.

Access to the baskets is possible through two manholes and heat exchanger chambers after removing the tube bundles. At the top of the casing, fittings are also provided for loading the methanol synthesis catalyst.

The device operates as follows.

Fresh synthesis gas enters the converter through an inlet fitting with an inner diameter of 750 mm, reaches the top of the first shelf / layer and crosses it in the downward direction (according to the usual "cross-flow" pattern). At the outlet of the shelf, the converted gas is collected and sent to the annulus of the heat exchanger; passing up, it heats the feedstock gas in the pipes.

After the heat exchanger, gas enters the subsequent shelves, repeating the above scheme, and leaves the apparatus through a fitting located at the opposite end of the reactor.

Features of the known utility model are:

- a simple design from a mechanical point of view: the catalyst baskets are empty containers, without complex internal parts, such as piping, coils, etc .;

- Independent access to each catalyst shelf directly from ground level.

The disadvantages of this utility model include the possibility of sintering of the catalyst layer, mainly in the first basket along the synthesis gas due to the lack of heat removal. In this case, the flow of synthesis gas to other sections of the reactor is reduced and it must be stopped accidentally to overload the catalyst, which leads to a decrease in the productivity of the entire methanol plant.

The objective of the utility model is to improve its design with a simultaneous increase in efficiency during operation.

The task is achieved in that the cylindrical methanol synthesis reactor with catalyst baskets located inside the housing separated by built-in heat exchangers or boilers is supplemented by a synthesis gas flow separation unit that remotely controls its supply through baskets consisting of valves functionally connected to each other and temperature sensors , and their number is less than the number of catalyst baskets by at least one.

Figure 3 shows a General view of the proposed utility model.

The reactor is a horizontal welder made of carbon steel SA-387.11.C12 with a length of 23900 mm and a diameter of 2800 mm, designed for an operating pressure of 10.28 MPa.

For remote control of the converted gas flow through the catalyst baskets, a unit is installed consisting of temperature sensors and valves installed in the first three sections of the apparatus with fittings. Opening the valves to the required throughput occurs when the maximum permissible temperature of the converted gas is reached, leaving the bottom of the catalyst baskets.

The utility model works as follows.

Fresh synthesis gas enters the converter through the inlet fitting, reaches the first upper shelf of the catalyst and goes down.

The temperature sensor installed at the bottom of the reactor is functionally connected with the operation of the valve and upon reaching its critical value, determined by the properties of the catalyst, gives the valve a command for the required degree of opening. In this case, part of the synthesis gas is discharged via the bypass line to the lower part of the apparatus and, together with the converted gas, is sent to the heat exchanger and then to the shelf of the second basket. In turn, a decrease in the volume of synthesis gas passing through the first catalyst basket equalizes the temperature profile in it and, accordingly, reduces the rate of adverse reactions.

The operation of control valves in other sections of the apparatus is similar to the considered example.

The implementation of the claimed utility model will significantly extend the life of the catalyst for the synthesis of methanol due to alignment

temperature profile along the entire length of the apparatus and thereby increase the productivity of the installation.

Claims (1)

A cylindrical methanol synthesis reactor with catalyst baskets inside the housing separated by heat exchangers or boilers, characterized in that it further comprises a remote control unit for the synthesis gas flow through baskets consisting of valves and temperature sensors functionally connected to each other, and their number is less than the number catalyst baskets at least one.