US 4,626,552 A · Process for the start-up of a Fischer-Tropsch reactor

Abstract

A process for the start-up of a reactor which utilizes a feed comprising hydrogen and carbon monoxide for the synthesis of hydrocarbons. The feed is contacted with a bed of hydrocarbon synthesis catalyst in which perturbations of the temperature profile across the bed can develop, and which, at start-up is particularly acute. In practicing the process the feed is introduced into the reactor at a rate ranging up to about 100 percent of the total flow rate at which the feed is introduced to the reactor at line-out. Hydrogen is introduced into the reactor as a portion of said feed at a molar feed rate generally well below the feed rate in which the hydrogen is employed in the reactor at line-out, the molar ratio of hydrogen:carbon monoxide of the feed generally not exceeding about 90 percent, preferably 75 percent, of the molar ratio of hydrogen:carbon monoxide at line-out. While maintaining the low molar ratio of hydrogen:carbon monoxide in the feed, the pressure and temperature of the reactor is raised to levels of pressure and temperature, respectively, employed at line-out. Thereafter the molar ratio of hydrogen:carbon monoxide is raised until the molar ratio of hydrogen:carbon monoxide is essentially that employed at line-out. The thermal stability of the operation is greatly improved, and by conducting start-up in this manner the conventional time period required for start-up can be drastically reduced, e.g., from an 8 to 18 day start-up period for a small reactor to as little as about 20 hours, or less.

Claims14

Dependent claims

In a process for the start-up of a reactor wherein a feed comprised of hydrogen and carbon monoxide is contacted with a bed of hydrocarbon synthesis catalyst in which perturbations of the temperature profile across the bed can develop, and which, at line-out conditions defined by feed flow rate, pressure, temperature, and the molar ratio of hydrogen:carbon monoxide of the feed is sufficient to synthesize hydrocarbons from the hydrogen and carbon monoxide, the improvement which comprises:

elevating, while maintaining the molar feed ratio of hydroge:carbon monoxide at below about 90 percent of its line-out value, the feed flow rate, pressure, and temperature to values approaching line-out feed flow rate, line-out pressure, and line-out temperature, and then gradually increasing the molar feed ratio of hydrogen:carbon monoxide to essentially that employed at line-out.

(i) introducing the feed into the reactor at a rate ranging between about 30 percent and 100 percent of the total flow rate at which the feed is introduced to the reactor at line-out, hydrogen being introduced into the reactor as a portion of said feed in molar feed rate ranging from about 15 percent to about 90 percent of the feed rate of hydrogen employed in the reactor at line-out, the molar ratio of hydrogen:carbon monoxide of the feed not exceeding about 90 percent of the molar ratio of hydrogen:carbon monoxide at line-out,
(ii) raising the pressure and temperature of the reactor to levels of pressure and temperature, respectively, employed at line-out;
and while maintaining these levels of pressure and temperature,
(iii) increasing gradually the molar ratio of hydrogen:carbon monoxide until the molar ratio of hydrogen:carbon monoxide is essentially that employed at line-out.

1 more element

(i) introducing the feed into the reactor at a rate ranging between about 30 percent and 100 percent of the total flow rate at which the feed is introduced to the reactor at line-out, hydrogen being introduced into the reactor as a portion of said feed in molar feed rate ranging from about 15 percent to about 90 percent of the feed rate of hydrogen employed in the reactor at line-out, the molar ratio of hydrogen:carbon monoxide of the feed not exceeding about 90 percent of its line-out value, the temperature ranging from about 0 Fahrenheit degrees to about 200 Fahrenheit degrees below the temperature employed at line-out, pressure ranging from about 60 psig to about 550 psig below the pressure employed at line-out,
(ii) increasing gradually the pressure of the reactor to that employed after line-out of the reactor while maintaining substantially the temperature and gas flow rate described in step (i);
increasing gradually the temperature of the reactor until the space-time-yield obtained with the feed gas characterized in step (i) corresponds to that obtained during line-out;
and while maintaining these levels of pressure and temperature,
(iii) increasing gradually the molar ratio of hydrogen:carbon monoxide until the molar ratio of hydrogen:carbon monoxide is essentially that employed at line-out.

2 more elements

Dependencies are inferred from the claim text.

Process for the start-up of a Fischer-Tropsch reactor

Life of this patent

Process for the start-up of a Fischer-Tropsch reactor

Life of this patent

Abstract

Claims14