What are the disadvantages of the 4.0MPa Texaco gasifier and the 8.00MPa Texaco gasifier?

The furnace types and their respective advantages and disadvantages are compared and introduced in detail upstairs! Thank you very much! Could someone please introduce the operation and energy consumption of the post-process due to the different pressures of the two furnace types?

Haha, the pressure is different, much different

Please give a detailed comparison upstairs, thank you! !

The pressure levels of the more common coal-water slurry entrained bed coal-water slurry pressurized gasifier should be 4.0MPa, 6.5MPa and 8.5MPa. The main consideration is the pressure required in the post-process.

(1) Different gas compositions: As the gasification pressure increases, the volume reduction reaction is facilitated. The CH4 and CO2 content in the gas increases, and the heat of the gas increases. Increasing the gasification pressure can increase the calorific value of the gas, which is beneficial to the production of city gas, but detrimental to the production of synthetic raw material gas. Therefore, the selection of gasification pressure must be comprehensively considered. (2) The gas production rate is different. As the pressure increases, the gas production rate decreases. The decrease in gas production rate as the pressure increases is due to the increase in the amount of methane in the generated gas, thereby reducing the total gas volume. (3) The consumption of oxygen and water vapor is different. As the pressure increases, the reaction rate to generate methane accelerates, and the heat released by the reaction increases, thereby reducing the oxygen consumption of the carbon combustion reaction. As the pressure increases, water vapor consumption increases. As the pressure increases, the amount of hydrogen consumed to generate methane increases, and the absolute amount of water vapor decomposition required by the gasification system increases. However, the increase in pressure increases the speed of the water vapor decomposition reaction to the left, that is, the water vapor decomposition rate decreases. For example, the decomposition rate of water vapor is about 65% under normal pressure, while the decomposition rate of water vapor drops to about 36% under 2.0MPa. Due to the above reasons, the water vapor consumption of pressurized gasification is higher than that of normal pressure gasification. * * Increase (4) Gasifier production capacity. The production capacity of different gasifiers depends on the chemical reaction speed of the gasification reaction and the diffusion speed of the gas-solid phase. Under pressure, under the same temperature conditions, a larger reaction rate for generating methane can be obtained. Therefore, the chemical reaction speed of pressurized gasification at the same temperature is faster than that under normal pressure, which is beneficial to improving the production capacity of the gasifier. In short, increasing 4.0MPa to 8.00MPa brings various advantages, but due to the decrease in water vapor decomposition rate, the thermal efficiency decreases as the pressure increases. If you think I am very dedicated, please rate me for encouragement!

It should be 8.75MPa.

In fact, for now, the gasification pressure of 4.0MPa seems a bit low. The initial choice was due to many problems. With the improvement of gasification technology, the pressure has also developed from low to high. Now 6.5MPa is more common and can be used with low-pressure synthetic methanol, reducing compression power consumption. The 8.7MPa gasification currently operating in Nanhua has a background of replacing oil with coal, and is generally not used as a key recommendation gasification process. After the pressure level of the device is increased, many problems are brought about. The requirements for material grade are increased, which involves the level of mechanical manufacturing and air separation capacity. It is believed that with the continuous development of science and technology and the trend of large-scale equipment, the scale of gasification will become larger and larger, and the pressure level should be increased, but it should not be unlimited and should be at a reasonable supporting level.

At present, domestic gasifiers are mainly operated at three pressure levels of 4.0MPa, 6.5MPa and 8.5MPa. The current design pressure of 6.5MPa is more reasonable. If the pressure is too high, the material level and equipment manufacturing requirements of the equipment for conversion, methanol washing and liquid nitrogen washing will be high. Originally, some materials for low-temperature methanol washing need to be purchased abroad, so the project investment will be greater. Currently, low-temperature methanol washing is more demanding The reasonable pressure is about 5.6MPA. If the pressure is increased to above 7.3MPA, the absorption effect will not be very obvious, and the equipment investment will also increase. In addition, if you choose 8.5MPa, the corresponding pressure level of the air separation liquid oxygen pump and the main heat exchanger equipment in the cold box will be increased, and the equipment investment will obviously increase. So I think the gasification pressure of 6.5MPA is more appropriate. If I am right, give me extra points.

There is another benefit that no one has mentioned. During low-pressure operation, Texaco gasification systems have experienced varying degrees of ash and water problems. There is no such problem in 6.5MPa and 8MPa factories. After increasing the pressure, the gas flow rate will decrease, which is helpful to solve the problem of dust and water in the quench system and gray water system.

I think what you said is not accurate enough! Take methanol production as an example. Currently, the methanol synthesis pressure is 5.5~6.0MPa, while some manufacturers use 4.0MPa gasification pressure, and some use 6.5MPa gasification pressure. Can you say that the gasification pressure is determined based on the pressure required in the post-process? ? I personally think: Using 4.0MPa gasification pressure mainly requires a large amount of purified lean liquid circulation, a large compression ratio of the synthetic compressor, and a large total energy consumption. ； The gasification pressure of 6.5MPa has relatively low energy consumption requirements for post-processing!

In fact, the maximum pressure of Texaco is 8.7MPa, but the only set introduced in China is designed and produced according to 8.5MPa. The choice of pressure is mainly to consider the subsequent use of the syngas. Of course, within the allowable range of the material, the higher the pressure, the better, the higher the efficiency, and the corresponding corporate profits will be higher, but there are practical problems! Just like buying a car, the displacement is closely linked to the user's actual hardware and software facilities!

As the pressure increases, the gasification burner will also be affected and its service life may be reduced accordingly.

If it is not due to the post-process pressure requirements, it is recommended not to use the 8.5Mpa Texaco gasifier. Because the system pressure is high, the burners and valves (especially the hand valves are large)... ultimately require a lot of manpower to start and stop, and the process of starting and stopping is very long, and it is also very laborious to hand over for maintenance.

This post was last edited by xuqinger on 2010-3-31 20:34 In fact, the 8.7MPa device of Nanhua is running quite well.

It seems that you are a friend of Nanhua and are so familiar with Nanhua's process, so please introduce the operation of high-pressure and low-temperature methanol washing, especially the stability and energy consumption of the pump.

Let me say a few words. As we all know, the gasification burner is the key equipment of gasification. As far as I know, the operating life of the burner of the 4.0MPa gasifier should have reached about 150 days. The operating life of the burner of the 6.5MPa gasifier (inner diameter 2800) is within 45 days. The operating life of the burner of the 6.5MPa gasifier is within 45 days. The operating life of the burner of the MPa gasifier (inner diameter 3200) is more than 60 days, and the operating life of the burner of the four-nozzle 6.5MPa gasifier (inner diameter 2800) is about 30 days. In addition, can friends from Nanhua tell us about the operating life of the burner of the 8.5MPa gasifier? Can friends from Yankuang Cathay talk about the operating life of the four-nozzle 4.0MPa gasifier burners? It should be said that for high-pressure gasifiers, the life of the burner is reduced, which indirectly results in an increase in the number of shutdowns and maintenance, and increases shutdown losses and maintenance costs.

If methanol is produced, the 8.0MPa process and the low-temperature methanol washing process do not require a compressor.

For the synthesis of methanol, I strongly recommend that Texaco gasifiers use a working pressure of above 8.0MPa, because the lower the pressure, the single-pass conversion rate of methanol decreases significantly, and it is more economical to use higher pressure to produce methanol. The operating life of the burner of the gasifier is a technical difficulty, but for the synthesis of methanol, a pressure above 8.0MPa is economical.