Syngas conversion in space furnaces and Texaco furnaces!

It depends on by how many points CO is higher; if the increase is within 5%, no additional steam should be required. Of course, it also depends on the process design for the transformation; if the water passes through a 2.5 MPa waste boiler before entering the transformation furnace, the steam pressure upon entry into the furnace will be around 0.7, which is generally sufficient.

This also depends on what the subsequent system is designed to produce, as well as whether partial or complete conversion is used in that system. In our coal-fired furnaces used for methanol production, medium-pressure steam was added at the methanol production stage to adjust the water vapor ratio; this approach allowed us to control the extent of the reaction and facilitate the adjustment of the H/C ratio in the converted gas. The post-process system of the current water-coal slurry process is used for producing liquid ammonia, and the water vapor from the fully shifted process gas is basically sufficient; however, the water vapor ratio can have an impact on CO.

The space furnace has a water-cooled wall structure, whereas the conventional Texaco furnace, namely the GE furnace, has a hot wall; the combustion chamber temperature of the space furnace can be higher.

This post was last edited by wlq1970 on 2015-7-1 at 18:16. Based on the reaction equation, steam and CO react in a 1:1 ratio; therefore, the actual amount of CO should be calculated using material balance, and then it should be determined whether there is sufficient steam by analyzing the water-to-gas ratio. In principle, a 1:1 ratio should be maintained, but some excess steam should be present. If sulfur-resistant shift reaction is used and the sulfur content in the feed gas is low, the excess amount of steam should not be too large, as this can easily lead to desulfurization of the sulfur-resistant catalyst. Repeated sulfidation and desulfurization can easily result in catalyst deactivation.

This post was last edited by wang06120325 on 2015-7-1 at 18:59. The designed value for the water vapor ratio is around 1.2 to 1.4, but it’s difficult to achieve this in practice. The calorific value of the coal varies, which in turn affects the thermal load on the furnace. Additionally, the operating temperature and pressure of the gasification furnace also influence the water vapor ratio. Here, the water vapor ratio generally does not exceed 1.2; once it exceeds this value, it indicates that the gasification furnace is approaching a state where water is carried over in the output. In practical operations, it has been found that when the water quality in the furnace is good, the water vapor ratio can be increased without the liquid level in the furnace dropping too rapidly. However, if the water quality is poor, increasing the water vapor ratio will only exacerbate the problem of water being carried over. From a transformation perspective, an increased water vapor ratio raises the concentration of reactants, which facilitates the forward reaction. However, it also carries away a large amount of reaction heat, potentially causing a drop in temperature within the bed. The desulfurization phenomenon mentioned earlier occurs for this same reason. Additionally, an excessively high water vapor ratio reduces the strength of the catalyst, leading to widespread caking. Most manufacturers currently use cobalt-molybdenum-based catalysts; if reverse sulfidation occurs, the catalyst becomes inactive and needs to be sulfided again.

Previously, the company used Shell boilers; since a waste-heat recovery system was employed, medium-pressure steam was added to the downstream system to adjust the water-vapor ratio. Although the space furnace uses water-cooled walls, due to the quenching process, the water-vapor ratio should be similar to that of the water-coal slurry, or even slightly higher, as the operating temperature of the space furnace is slightly higher than that of the water-coal slurry.

We use Texaco pressure gasification here; there are two furnaces in operation with one as a backup, and the output of transformed gas is around 220,000 cubic meters.:)

Now, some conversion manufacturers have developed models suitable for low water vapor ratios; even furnaces with such low water vapor ratios as those used by Shell can carry out reactions properly without the need for steam.

Well, the low water vapor ratio catalyst mentioned above is also based on the principle of controlling the extent of the shift reaction. The syngas from coal-fired boilers is directed to the shift reactor in three different streams, one of which is used as quench gas to control the temperature of the bed. The process is relatively complex; otherwise, the bed temperature can rise sharply due to the high concentration of carbon monoxide in the syngas. This phenomenon is more pronounced when starting up the system and bringing it online. Additionally, before entering the burner, the oxygen in the coal-fired furnace passes through a steam mixer where it mixes with medium-pressure steam; by controlling the ratio of oxygen to steam, the effective gas content of the syngas can be altered, thereby increasing the hydrogen content in the syngas.