Issue 11/2013 - Advances in new ethoxylatation reactor technology

Technological progress of new ethoxylatation reactors

□ Jiangsu Tianyin Chemical Co.
, Ltd.
Qin Yisheng Chen Yongfu Zhang Xuejun

Ethoxylatation of alcohols or phenols with ethylene oxide (EO) produces alcohol ethers or phenol ethers, which are a series of mixtures
with varying degrees of polymerization.
At present, the ethoxylatation reactor used in industry has the traditional tank stirring reactor, the new Press reactor, the tubular reactor and the Buss reactor, because the new ethoxylation reactor has many advantages, is constantly replacing the traditional ethoxylation reaction device
.

1.
Tubular reactor

Tubular reactors are mostly used for the continuous production of polyether, because it is close to the ideal piston flow, the residence time is short, the material contact time is the same, the molecular weight distribution of the ethoxy matrix obtained is narrow, the color is good, and the by-product content is low
.
In addition, because the tube is slender and has good heat dissipation, it will not cause local overheating
of the reactor.
Figure 1 shows the tubular ethoxylation process
.

The early ethoxylated tubular reactor process has the following disadvantages: (1) the EO addition of each stage of the reactor is not large, it is difficult to generate high molecular weight products, and multiple stages of feeding are required to obtain high molecular weight products, thus complicating the reactor feeding system; (2) The reactor section is small and the production capacity is not large, if you want to increase the production capacity, you need to lengthen the reactor, which increases the cost investment and consumption; (3) Only suitable for mass production, not suitable
for multi-variety production.

Second, Press reactor

In 1962, the Italian company Press Industries launched a new ethoxylatation reactor, which completely changed the mass transfer process of the tank reactor, that is, instead of using the principle of distribution in the gas phase initiator and catalyst liquid phase of EO, but using the starting agent and the catalyst liquid phase as the dispersion phase, diffusing to the EO gas phase as a continuous phase in a fine spray state
.
Installing a nozzle tube with different openings inside the reactor to spray liquid materials has greatly promoted the industrial production
of polyether.
In order to continuously improve and perfect the ethoxylatation reactor process, Press has launched three generations of industrial reactors
.

1.
The first generation of
the reactor The first generation ethoxylation reactor has only one gas-liquid contact reactor, and the weight ratio of starting agent and EO is 1:7, which is suitable for the production of EO
products with small molecular weight.
The reactor is suitable for the production of products with low molecular weight, and the volume growth ratio of EO to ethoxylatation products is 1:7, which is relatively small
.

2.
Second Generation Reactor Second Generation Reactor
makes a further contribution
to improving molecular weight distribution.
It is composed of two parts, a gas-liquid reactor and a receiver, in which each batch of reaction is carried out under the same geometric conditions, and the liquid in the receiver is always at rest, which helps to recirculate a more homogeneous liquid through EO.

The volume growth of this generation of reactor EO and ethoxylatation products has increased compared with the first generation, and the growth ratio is generally 1:12, which is only suitable for large-scale production
of medium and low viscosity products.

3.
The third generation reactor The third generation reactor is a horizontal and a vertical series connection, realizing the two-stage reactor
, in which there is a long neck under the vertical mixing reactor to store a small amount of starting agent
.
There are two large and small cycles, and when the small cycle is over, the large cycle is opened to increase
the molecular weight of the product.
The reactor is suitable for the production of high molecular weight products, the volume growth ratio of EO to ethoxylatation products is 1:40~70, and its reactor is shown in
Figure 2.

Press reactor has the following advantages:
(1) high reaction rate, good
product quality Due to the large area of liquid phase spray contact EO, the gas-liquid contact surface is significantly increased, thereby greatly improving the reaction speed and reducing the amount of catalyst, generally 0.
1% of the finished product amount, and the reaction pressure is low
.
Since the droplet descent path is the same during the reaction process and the reaction molecule growth rate is the same, the molecular weight distribution of the final product is narrow
.
Due to the short production cycle and fast response, the color of the product is better
.

(2) The system safety is high, the process control is completely automated
Because the liquid phase is dispersed into the gas phase, the gas-liquid contact is sufficient, the reaction speed is fast, EO rarely remains in the liquid phase, and the gas phase part is not in contact with any rotating or moving parts, which reduces the possibility of explosion, prevents the generation of static electricity, and reduces the possibility
of EO leakage.
The whole process can be controlled
by DCS automation.

(3) Strong adaptability, less
by-products There are more than 200 ethoxylatation product formulation technologies in the Press software library, such as raw alkyl phenols, synthetic fatty alcohols, natural fatty alcohols, fatty acids, esters, amines, etc.
as starting agents and EO additions have very good adaptability, and can also be used to prepare polyethylene glycol and other polyethers
.
Since the catalyst-containing starting agent is in full contact with EO, the reaction speed is fast, and the amount of catalyst is small, which avoids long-term contact between EO and catalyst, and reduces the content of self-polymerization by-products of EO
.

(4) Low production energy consumption, the device occupies a small
ground Pressreactor no matter from the consumption of electricity, water, steam, or nitrogen, the consumption per ton of product is far lower than that consumed by traditional
reactors.
Due to the reasonable arrangement and exquisite design of this type of reactor, the plant occupies a small
area.

Nevertheless, the Press reactor has the following disadvantages: the device is not suitable for ethoxylatation with EO as a starting agent for solids with higher melting points; Compared with the Buss reactor process, the reaction rate is
relatively slow.

Third, Buss reactor

The Swiss company Buss has developed the ethoxylatation circuit reactor, the core of which is a high-efficiency gas-liquid reaction mixer, the whole process is carried out
in the state of continuous cyclic movement of the gas phase and the liquid phase.
The structure diagram of its core part is shown in
Figure 3.

Although the Buss reactor has the advantages of good gas-liquid mass transfer, high reaction rate, good product quality, high safety, small environmental pollution, and high volume utilization rate, at present, its industrial devices are few, and the product formula is less mastered, and the application is not as extensive
as the Press reactor.

4.
Loop reactor

Dana International Jiangsu Tianyin Chemical Co.
, Ltd.
(hereinafter referred to as Dana Chemical) ethoxylation reactor technology from the use of tank reaction to the development and application of multiple sets of loop (external circulation) reactors, and the successful development of continuous pipeline reaction ethyl (prop) oxygenation reaction device; The products produced by ethyl (propyl) oxylatation technology have developed from a single variety to the production of ethylene glycol methyl ether, ethylene glycol ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol ether and polycarboxylic acid polyether
.

Dana Chemical initially used the stirring kettle ethyl (propyl) oxylating reactor to produce surfactants for the preparation of chemical fiber oil agent, but the ethoxylatation reaction production of the stirred kettle has the shortcomings of ethylene oxide raw material loss, high energy consumption, easy to produce safety accidents, etc.
, after understanding the superiority of foreign press reactors for ethyl (propyl) oxylatation reaction, through digestion and absorption of foreign technology, began to develop and apply loop (external circulation) reactors
.
The core technology of the loop reactor is the design
of nozzles that fully disperse the circulating material.
After research, it has been independently designed and successfully applied to loop reactor manufacturing
.
At present, Dana Chemical has built 7 sets of loop reactors, including 1 set of 60-liter loop reactor for pilot test, 1 set of 2 cubic meter and 8 cubic meter reactor, and 2 sets
of 15 cubic meter and 20 cubic meter reactors.