The startup of low-temperature methanol washing is spray methanol treatment. . .
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The methanol used in the low-temperature methanol washing spray is introduced 30 minutes before startup. . . But isn’t it unreasonable to send this amount of methanol to the methanol-water separation tower? Our company sends this methanol to the methanol regeneration tower. We wonder if there are other companies that use a similar design to ours, and whether anyone agrees with it.
It makes sense! Because at this time, the methanol-water separation tower has already been put into operation!
This portion of methanol should be sent to the methanol-water separation tower; it represents the main source of water introduced into the methanol washing system, and separation of water is necessary.
Methanol spraying is started half an hour before gas introduction, and the methanol-water separation tower should be put into operation at the same time as methanol spraying. What the poster is concerned about is that at this time the water separation tower is not in use, and the low temperature may cause damage to the E16 unit as well as the pipes downstream, as well as to the materials of the water separation tower; this could lead to frost cracking, given that these are all steel materials designed for normal temperature conditions.
It makes sense – the purpose of spraying methanol is to mix the methanol with the condensate formed from the processed gas, thereby lowering the temperature of the water below its freezing point and preventing ice formation that could block the pipes. Thus, this mixed liquid is discharged to the water separation tower after passing through V101, in order to recover this portion of the sprayed methanol
This methanol enters the water separation tower to recover it, thereby maintaining the methanol concentration within that tower
This method is reasonable. You are using Linde cryogenic methanol wash, right? The function of this methanol is to lower the freezing point of the feed gas and prevent ice formation that could block the pipes ； Secondly, it is to prevent it from reacting with water. It then enters V101 for gas-liquid separation, and exits from the bottom to the lower part of T105 (the methanol-water separation tower). The stream coming from the top of T105 enters T104 (the thermal regeneration tower), while the stream coming from the bottom passes through a heat exchanger before entering V105. After passing through a pump and a heat exchanger, it splits into two streams: 1) which goes to the top of T101 as the absorbent liquid; 2) which is mixed with the raw gas. This allows methanol to be recycled. :handshake
By the time methanol spraying was resumed, the thermal regeneration tower was already in operation, and E116 already had hot fluid flowing through it, so there was no need to worry about the pipes freezing! Also, for the material design of ordinary heat towers, the minimum temperature they can withstand is generally around -25 degrees!