Abstract

Japan Oil, Gas and Metals National Corporation (JOGMEC), JGC Corporation and Osaka Gas Co., Ltd have been developed a new syngas production process, Advanced Auto-Thermal Gasification (A-ATG) process, consisting of a new auto-thermal reforming catalyst with ultra-deep desulfurization of natural gas. We verified A-ATG process through 2,000 hours syngas production operation at pilot plant of which capacity was 65 BPD-GTL equivalent. This paper shows result of pilot plant operation and discussion including economics, environmental parameters and a future application of this system.

Introduction

GTL technology is an effective technology to produce clean fuel from natural gas and coal seam gas. Especially, a country such as JAPAN which has not natural resources in domestically and imports oil from foreign countries needs GTL technology for securing national security because GTL technology contributes diversity in liquid hydrocarbon resources. Australia also can supply oil with Australian people stably from domestic abundant natural resources such as natural gas and coal seam gas by using GTL technology (1).

The Advanced Auto-thermal Gasification (A-ATG) Process is a new, high-efficiency process to produce synthesis gas from natural gas and coal seam gas. We believe that the successful development of this process will lead to a substantial reduction in the construction costs for synthesis gas production systems, which account for a large percentage of the total construction costs of GTL plants, and will, thereby, contribute to the wider use of GTL products. The development of the A-ATG process has been carried out jointly by Japan, Oil, Gas and Metals National Corporation (JOGMEC), JGC Corporation and Osaka Gas Co., Ltd.

We constructed the pilot plant of 65BPD-GTL equivalent as shown in Figure 1, and have been conducted pilot plant test project in order to acquire engineering data for scale-up technology and to verify A-ATG technology.

Characteristic of A-ATG process

A synthesis gas production process based on the combination of a pre-reformer and a secondary reformer is the state of the art for commercial plants at the present time. Figure 2 compares the main flows of the conventional process with the A-ATG process.

In the conventional process, desulfurized natural gas is reformed with steam at a low temperature in the pre-reformer and, then, further reformed at a high temperature in the secondary reformer, using burners. However, the pre-reformer must be relatively large because of the low reaction rate (around GHSV 5,000 hr-1), and there is a limit to how much the secondary reformer can be scaled up due to burner design issues.

The A-ATG Process combines ultra-deep desulfurization of the feed gas with a new, high performance reforming catalyst which allows simultaneous oxidation (exothermic reaction) and reforming (endothermic reaction), with an entry temperature below 300°C and without using burners. That means that the A-ATG system intrinsically can realize auto-thermal reaction on the catalyst. Moreover, the maximum reactor temperature is lower than that in the secondary reformer used in the conventional process.

Results and discussions
(1) Pilot Plant Test

The process flow of the pilot plant is shown as Figure 3. Feed gas is compressed and heated in the desulfurizer feed heater, then fed to the ultra deep desulfurizer. The sulfur content of the feed gas is reduced to less than 1 ppb in this reactor. The desulfurized feed gas is mixed with steam and oxygen, then fed to the AATG reactor. In this pilot plant, the AATG reactor feed heater is installed to obtain operation data under various inlet temperatures of the reactor. The effluent of the reactor is fed to the quench drum to cool it down, then fed to the flare stack to burn it. A small amount of product gas is fed to the shift reactor to produce hydrogen-rich gas, which is recycled to the compressor for the desulfurization reaction.

Before testing at this pilot plant, we confirmed the catalyst performance and the stable operation at the bench-scale plant (2)(3).

We conducted the long operation test during 2,000hours at this pilot plant. Operation conditions of this test are shown as in Figure 4 and the gas composition of it in the pilot plant is shown as in Figure 5. The stable operation was achieved under high-temperature (950–1050°C) and high-pressure (2.8–3.0MPaG) conditions without trouble.

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