CN109678819B

CN109678819B - Optimized energy production method of diketene

Info

Publication number: CN109678819B
Application number: CN201811506123.7A
Authority: CN
Inventors: 徐成刚; 田家民; 葛恒杰
Original assignee: Anhui Jinhe Industrial Co Ltd
Current assignee: Anhui Jinhe Industrial Co Ltd
Priority date: 2018-12-10
Filing date: 2018-12-10
Publication date: 2022-04-01
Anticipated expiration: 2038-12-10
Also published as: CN109678819A

Abstract

The invention relates to a diketene optimized energy production method, which utilizes a 2# standby quencher to always control the high negative pressure production of a device system, if the pressure difference of the emergency cooling reaches more than 3KPA, the standby quencher is immediately switched online to ensure the high negative pressure long-period production of the system, simultaneously 96 percent acetic acid entering an acetic acid evaporator is subjected to secondary preheating, the running period of the evaporator is prolonged, and a dilute anhydride pump is used for carrying out discontinuous dilute anhydride circulation on a 4# to 6# condenser, so that the problem of blockage of the condenser is solved, the cracking running period is prolonged, the diketene yield in unit time is increased, the overhaul time is shortened, the effective production time is prolonged, the overhaul cost and the production cost are reduced, and the generation of pollutants and wastewater is reduced. Improves the optimized cycle of diketene productivity and prolongs the production process and the device.

Description

Optimized energy production method of diketene

Technical Field

The invention belongs to the technical field of chemical production, and relates to a method for producing diketene by an acetic acid cracking method.

Background

The acetic acid cracking method is the main method for preparing the diketene at present, but belongs to negative pressure production in the diketene production process, particularly in the high-temperature cracking process, the coil pipe of a cracking furnace is carbonized and can be continuously brought to the inlet of a quencher, the diketene production process is to prepare 99.0 percent of raw material glacial acetic acid and 85 percent of recovered acid of a recovery system into cracked acid with the content of 96 percent +/-0.2 percent, the cracked acid is pumped into an acetic acid evaporator through an acetic acid knockout pump, the acetic acid is completely gasified through an acetic acid superheater and enters the cracking furnace. The diammonium hydrogen phosphate with the content of 30 percent of the cracking reaction catalyst enters a cracking furnace radiation section together to catalyze the cracking of the acetic acid. The raw material glacial acetic acid and the system recovered acid contain a certain amount of impurities, byproducts acetone and impurities in diammonium hydrogen phosphate (when the temperature of the cracking furnace is too high, the over-cracking phenomenon is aggravated, namely, the coking phenomenon is also aggravated), the outlet of the cracking furnace is the inlet of a quencher, partial tubulation of the quencher is blocked, negative pressure difference between the inlet and the outlet of the quencher is increased if the temperature is too high, power equipment energy consumption is increased, the feeding amount is not increased, the yield is reduced, if the load is maintained forcibly, raw material consumption is increased, the amount of side reaction dilute acetic acid is increased, safety production is endangered, when the dilute acid is recovered, the cost is increased, a certain amount of sewage is also generated, the environment is polluted, the sewage treatment cost is increased, and energy is wasted. The operation cycle of manufacturers of the same device is about 1 month, and the devices are frequently cleaned, and the carbon of the incomplete cracking furnace knot of the acetic acid cracking is brought into an inlet tube of a quencher from the cracking furnace, so that the system resistance is increased, waste gas and sewage are generated, and the problem of great extension of the cracking cycle and capacity optimization becomes a problem to be solved urgently in the ketene dimer industry.

Disclosure of Invention

The invention mainly aims to improve the yield, reduce the consumption of glacial acetic acid and raw materials, reduce the cleaning frequency and waste gas and sewage generated in the cleaning process and finally achieve the purposes of energy conservation and emission reduction.

The technical scheme adopted by the invention is as follows:

a diketene optimized energy production method comprises the prior process steps of cracking, condensing, polymerizing, absorbing, rectifying, recycling and treating residue DK, hydrolyzing, recycling and concentrating dilute acid, wherein a 1# quencher, a 2# to 6# condenser and a separator are sequentially connected at an outlet of a cracking furnace, and is characterized by comprising the following steps:

1) the two ends of the 1# quencher are connected with a 2# quencher and a 1# quencher in parallel to form a standby quencher, when the pressure difference of an inlet and an outlet of the 1# quencher in production is more than 3KPa, the 2# quencher is started to be continuously used, the 1# quencher is closed, and the 1# quencher is cleaned for standby after the temperature of the 1# quencher is reduced to normal temperature;

2) when the No. 4-6 condenser is blocked, starting a dilute anhydride pump to flush the No. 4-6 condenser and the separator for 3-5 minutes;

the further technical scheme is as follows:

in a diketene system, two No. 1 heat exchangers and No. 2 heat exchangers are arranged before acetic acid enters an acetic acid evaporator, so that 96 percent acetic acid at normal temperature is adjusted to 80-90 ℃;

a set of rectification system and a hydrolysis kettle are added between the separator and the concentration dilute acid tank, so that the material blockage phenomenon can not occur in the processing of the crude diketene;

the concentration dilute acid tank is lifted to 1.5 meters from a feeding acid liquid inlet of the concentration system, and a feeding acid pipeline of the concentration system is changed to be used for hydrolysis dropwise adding, so that the operation period of concentration is prolonged, the quality of cracked acid is improved, the over-cracking phenomenon is relieved, and the operation period of cracking is prolonged.

The method has the advantages that the cycle of the diketene production device is prolonged to more than 12 months by optimizing the flow, the production cost is reduced, the pollution is reduced, the yield of the diketene is improved, the consumption of glacial acetic acid is reduced, and the generation of waste gas and sewage in the overhaul period of each month is greatly reduced.

The invention connects the outlet of the cracking furnace with a quencher in series, and realizes the long-period operation of the cracking system under the condition of ensuring that the system does not stop by switching (pre-pumping negative pressure), thereby improving the production yield and reducing the consumption of various materials, saving steam by preheating 96 percent acetic acid in advance and improving the running time of an evaporator. 4# to 6# condenser and separator upper head inside dispose the shower nozzle, solved the pressure differential problem that the weak anhydride of condenser blocks gradually. The improvement of the feed inlet of the concentration system and the optimization of the acid at the bottom of the concentration tank improve the quality of the cracking acid, relieve the over-cracking phenomenon and improve the cracking operation period. Greatly improves the yield, saves energy, reduces emission and is environment-friendly.

Drawings

FIG. 1 is a flow chart of the optimized diketene productivity production process of the present invention.

Detailed description of the invention

As shown in fig. 1, the method for producing diketene by optimizing capacity provided by the invention comprises the following steps:

1. connect gradually 1# quencher, 2# -6# condenser and separator in the pyrolysis furnace exit, near 1# quencher parallelly connected dispose a 2# quencher as reserve quencher, when 1# quencher inlet-outlet pressure difference is greater than 3KPa in the production, open 2# quencher cooling water valve and material outlet valve earlier, after system's pressure is steady, slowly open 2# quencher import, after 2# quencher pressure balance, close 1# quencher inlet-outlet, wait until 1# quencher temperature drop to circulating water temperature about, just possessed the maintenance cleaning condition. Namely, the 2# standby quencher is turned upside down, and the 1# quencher is cleaned for standby after the temperature of the 1# quencher used originally is reduced to the normal temperature.

When the pressure difference of the inlet and the outlet of the 2# quencher is more than 3KPa, the 1# quencher is turned over in time to continue production.

2. A spray header is arranged in the upper end sockets of the 4# to 6# condenser and the separator, when the condensers are slightly blocked (a negative pressure gauge is arranged between every two condensers, the negative pressure of the front-stage condenser is lower than the negative pressure of the rear-stage condenser, and the condition that the negative pressure is higher than 3KPa is generally the slight blockage), a weak anhydride pump is required to be started to flush the 4# to 6# condenser and the separator for 3-5 minutes (the corresponding condenser tube nest and the corresponding liquid discharge tube are flushed by weak anhydride with the content of 60 percent), and the flushed weak anhydride flows back to a weak anhydride tank, so that the problem of pressure difference caused by gradual blockage of the condensers is solved.

The dilute anhydride from the dilute anhydride pump adjusts the material spraying direction through a self-made spray header (5 stainless steel pressure guide pipes with the diameter of 10 mm and the length of 120 mm) of a No. 4-6 condenser and an upper end socket of a separator, so that ammonia salt in a condenser tube array, the separator and a liquid outlet pipe can be conveniently cleaned, the smoothness of the condenser tube array and the liquid outlet pipe is ensured, the high-negative-pressure production of a system is ensured, and the effect of prolonging the period is achieved.

3. In a diketene system, two 316L 1# -2 # heat exchangers are arranged before acetic acid enters an acetic acid evaporator, so that the original 96% acetic acid at normal temperature is adjusted to 80 ℃ -90 ℃, the steam consumption is reduced, and the service cycle of the evaporator is prolonged.

4. The concentration dilute acid tank is lifted to 1.5 meters from a feeding acid liquid inlet of the concentration system, and a feeding acid pipeline of the concentration system is changed to be used for hydrolysis dropwise adding, so that the operation period of concentration is prolonged, the quality of cracked acid is improved, the over-cracking phenomenon is relieved, and the operation period of cracking is prolonged.

The liquid inlet of the pump of the concentrated dilute acid tank is 20 cm away from the ground before being modified, the sediment and the byproduct acetone at the tank bottom can be recovered to a storage area through the concentrating device to be acid-blended, so that the acid is brought to a cracking furnace to generate a coking phenomenon, the cracking operation period is influenced, the liquid inlet is increased to 1.5 m after being modified, the sediment at the tank bottom does not enter the concentrating device any more, the operation period of a concentrating system is prolonged, the quality of the cracked acid is also improved, the over-cracking phenomenon is relieved, and the cracking operation period is prolonged.

The original feeding acid pipeline of the concentration system is changed into hydrolysis dropwise adding for use, and the sediment and acetone in the dilute acid are separated out through hydrolysis, so that the occurrence of side reaction is reduced.

5. A set of rectification system and a hydrolysis kettle are added between the separator and the concentrated and diluted acid tank, so that the problem of material blockage during processing of the crude diketene is avoided.

Claims

1. A diketene optimized energy production method comprises the prior process steps of cracking, condensing, polymerizing, absorbing, rectifying, recycling and treating residue DK, hydrolyzing, recycling and concentrating dilute acid, wherein a 1# quencher, a 2# to 6# condenser and a separator are sequentially connected at an outlet of a cracking furnace, and is characterized by comprising the following steps:

2) and when the No. 4-6 condenser is found to be blocked, the No. 4-6 condenser and the separator are flushed for 3-5 minutes by starting the dilute anhydride pump.

2. The method for producing diketene with optimized energy production according to claim 1, wherein in the diketene system, a heat exchanger 1 and a heat exchanger 2 are arranged before acetic acid enters an acetic acid evaporator, so that the normal temperature of 96% acetic acid is increased to 80-90 ℃.

3. The method for producing diketene with optimized capacity according to claim 1 or 2, wherein a set of rectification system and a hydrolysis kettle are added between the separator and the dilute acid concentration tank, so that the situation of material blockage during processing of the crude diketene is avoided.

4. The optimized diketene productivity production method according to claim 3, wherein the concentration dilute acid tank is lifted to 1.5 m from the feeding acid liquid inlet of the concentration system, and the feeding acid pipeline to the concentration system is changed to be used for hydrolysis dropwise, so that the operation period of concentration is prolonged, the quality of cracked acid is also prolonged, the over-cracking phenomenon is relieved, and the operation period of cracking is prolonged.