Summary of Q&A on chemical technology

Vacuum desuperheater overhead steam ejector, the pressure of the power steam increases, exceeding the normal operating pressure, is it beneficial to vacuum the top of the tower? why?

1. It is advantageous to increase the pressure by 0.5~1 kg. If the increase is too much, the vacuum will not be greatly improved , but it will have a negative effect.
2. After the pressure increases too much, the amount of steam entering the subsequent heat exchanger increases, and the heat load of the heat exchanger increases, especially when the temperature of the cooling water is high in summer, which causes the vacuum to drop.

In order to increase the inlet pressure of the air compressor, can the catalytic cracking fractionation tower use a packed tower?

The valve tower tray has the advantages of simple structure, convenient disassembly and assembly, high efficiency of the tray (compared with the bubble cap tower), large elasticity, wide adaptability and large production capacity, but it is easy to cause leakage when the treatment volume is low. liquid. The structure of the packed tower is simple, and it is convenient to manufacture and install and repair. However, the gas-liquid two-phase contact is not good, and the channel flow is easy to occur, so the large fractionation tower is rarely used. Used for absorption and extraction equipment.

The lower part of the fractionation column is not available because the superheated feed has a catalyst and can be used above the middle part.

The actual operation of the catalytic fractionation tower has 5 layers of solid tongue trays + 3 sections of packing, which has almost all the tower packing. It has been operating normally since 2012.

What is the high ethanol content in the finished methanol?

1. The synthesis reaction is poor, the ethanol content in the crude alcohol is high, and the rectification system is not adjusted in time;
2. The reflux ratio of the rectification system is small;
3. The rectification product is removed from the heavy component of the production tower;
4. The fusel oil and alkane oil are less produced;
5. The amount of extraction water added is small, and the complex is increased;
6. The intermediate tank or the finished tank is mixed with methanol;

What types of pump flushing are there?

Flushing can be divided into three forms of flushing, ie, self-flushing, external flushing, and cyclic flushing . (1) Due to the viscosity and gravity of the medium delivered by the pump itself, a cleaner medium is introduced into the sealed chamber from the outside, which is called external flushing. (2) The medium conveyed by the pump itself is driven into the sealed cavity through a small hole in the end seal gland. Mix with the medium inside the pump. Called self-flushing. (3) Circulating flushing means that the flushing oil drawn from the outside enters the sealed cavity and is taken out by a special pipe. After cooling and filtering, it is re-entered into the sealed cavity.

The amount of steam in the reboiler of our company is increased, but the temperature of the tower is basically unchanged. Why? The tower feed is a vapor phase feed.

In fact, the reason is very simple.
From the common sense analysis, the reboiling steam increases and the kettle temperature should rise. However, the amount of steam in the reboiler reboiler is increased, but the temperature of the column is basically unchanged. Why? The maximum efficiency of the reboiler is achieved by the phase change of the reboiled steam . When the reboiler fills the process medium and reboils the vapor to complete the phase change, the efficiency of the reboiler is maximized. Your company's rectification tower reboiler steam usage increases, but the reboiler is the vapor in the gas phase, the energy actually loaded to the process side is not large, so the temperature of the tower kettle is basically unchanged. Another reason is that too much light components at the bottom of the tower can also cause this phenomenon, but this time is accompanied by other phenomena.
Of course there are other reasons such as reboiler coking, etc. You have to consider all possible factors in all directions.