WO2017005110A1

WO2017005110A1 - Method for preparing ethyl alcohol by extracting hydrogen using coke gas

Info

Publication number: WO2017005110A1
Application number: PCT/CN2016/087434
Authority: WO
Inventors: 代淑梅; 王天双
Original assignee: 唐山中溶科技有限公司
Priority date: 2015-07-06
Filing date: 2016-06-28
Publication date: 2017-01-12
Also published as: CN106316786A; CN106316786B

Abstract

Provided is a method for preparing ethyl alcohol by extracting hydrogen using coke gas, comprising the production steps: a coke gas resulting from coking is subjected to a series of purification measures, i.e. pre-purification, CO transformation, wet desulphurization and wet CO₂ removal, fine desulphurization and methanation, so that the coke gas becomes a purified gas only containing H₂, CH₄, CnHm and N₂, the purified gas is sent to a pressure swing adsorption device for hydrogen extraction to extract hydrogen, and the hydrogen is reacted with acetic acid to produce an absolute ethyl alcohol product. The method makes full use of the characteristics of different components in the coke gas to establish a new production process for producing ethyl alcohol by extracting hydrogen from coke gas while simultaneously producing a by-product methane gas, and the process is scientific, rational, simple and convenient. Not only are heat requirements for coke oven and chemical production satisfied, but also the problem of sulphur pollution from discharged smoke in coking enterprises is solved completely, while obtaining a good economic benefit.

Description

Method for extracting hydrogen from coke oven gas to produce ethanol

Technical field

The invention relates to the production field of coal chemical products and the field of environmental protection, in particular to a coke oven gas as a raw material, the coke oven gas is purified, the different components are separated and rationally utilized, and significant economic benefits are obtained, Completely solved the problem of sulfur pollution in coking enterprises.

Background technique

After the initial purification of the coke oven gas, the general total sulfur content (the sum of H ₂ S and organic sulfur) is as high as 300-600 mg/Nm ³ . The traditional coking process uses nearly 50% of the total coke oven gas directly back to the coke oven and chemical production as fuel. A coke oven with an annual output of 1 million tons of coke burns 220 million Nm ³ of coke oven gas every year and discharges 66-132 tons of sulfide per year to the atmosphere. In 2014, the country's 480 million tons of coke production discharged 30,000 to 60,000 tons of sulfide into the atmosphere. If the coke oven gas desulfurization device is separately used to solve the sulfur pollution of coking enterprises, the investment is huge and the cost is high, which is an unbearable burden for coking enterprises. At present, the excess coke oven gas after coke oven use, in addition to being used as fuel to burn (the same sulfur pollution), the most mature methanol production technology, the largest installed. However, in the conventional coke oven gas-making methanol process, there are great defects in the process, and the conversion and the methanol-depleted gas-fired device all burn a large amount of hydrogen, and the energy waste is huge.

Summary of the invention

The object of the present invention is to provide a new method for extracting hydrogen from coke oven gas to produce ethanol in view of the problems existing in the prior art and the problem of sulfur pollution. The method purifies all the coke oven gas, and separates different components, and the high-value hydrogen gas is used for reacting with acetic acid to produce ethanol, and achieves high economic benefits. The highly purified hydrogen extraction tail gas is returned to the coke oven for fuel, so that the sulfur content of the coking plant exhaust gas is close to zero (0.1 ppm). Completely solved the problem of sulfur pollution in coke oven exhaust. In addition to coke oven fuel, methane has some surplus and can be purified and sold as natural gas.

To achieve the above objectives, the following technical solutions are adopted: a method for extracting hydrogen from coke oven gas to produce ethanol, including coke oven gas prepurification device, CO converter device, wet desulfurization device, wet CO ₂ removal device, fine desulfurization and methane Chemical plant, pressure swing adsorption methane removal device, pressure swing adsorption hydrogen extraction device, coke oven gas compression device, hydrogen compression device, methane gas compression device, acetic acid hydrogenation to ethanol plant, the specific steps are as follows:

a. The coke oven gas produced by the coking chemical production is sent to the coke oven gas prepurification device to remove impurities;

b. The pre-purified coke oven gas is pressurized by the coke oven gas compressor and then enters the CO converter to generate a shift gas;

c. changing gas into the wet desulfurization device for wet desulfurization;

d. The gas after the wet desulfurization is pressurized by the compressor and then enters the wet decarburization device;

e. The decarburized gas enters the fine desulfurization device, and the desulfurized gas is a high-purification purification gas;

f. Purifying gas enters the pressure swing adsorption methane extraction device, extracts part of methane gas, and is sold as natural gas after being pressurized;

g. The tail gas after the methane is introduced into the pressure swing adsorption hydrogen extraction device, and most of the hydrogen is extracted for use in the hydrogenation device;

h. acetic acid and hydrogen enter the acetic acid hydrogenation unit, acetic acid and hydrogen react to form ethanol, which is rectified and sold as anhydrous ethanol product;

i. Exhaust gas after hydrogen extraction, coke oven and chemical production as fuel.

The main components (molar percentage) of coke oven gas are: H ₂ 55-60%, CO 5-8%, CO ₂ 1.5-3.5%, CH ₄ 23-27%, CnHm 2-4%, N ₂ 3- 7%, H ₂ S 100-200 mg/Nm ³ ; organic sulfur 200-400 mg/Nm ³ ; calorific value 3500-4500 kcal/Nm ³ .

The coke oven and the fuel required for chemical production are provided by the hydrogen extraction tail gas of the later process; the water vapor required for the production of each device in the whole process is provided by the coke dry quenching device.

According to the above technical solution, compared with the existing coke oven gas methanol technology, the invention eliminates the high energy-consuming air separation device and the methane conversion device in the existing coke oven gas methanol production technology, and the investment is reduced, and the production cost is reduced; While greatly reducing the production cost, there are two products of ethanol and natural gas, and the output value and economic benefit are increased several times. In the present invention, the coke oven gas is no longer directly returned to the coke oven and chemically produced as a fuel, and the post-process high purification degree is used. Exhaust gas is used as fuel; while achieving significant economic benefits, the problem of sulfur pollution from coking enterprises is completely solved. In the conventional coke oven gas methanol plant, the coke oven gas can only produce one kind of methanol. In the device of the invention, not only the produced ethanol is several times higher than the original methanol production value and economic benefit, but also By-product natural gas sales, the economic benefits are very significant.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a process flow diagram of the present invention.

Detailed ways

The invention will be further described below in conjunction with the accompanying drawings.

The invention discloses a production method for extracting hydrogen from coke oven gas to produce ethanol. The design idea of the method is: compared with the coke oven gas to produce methanol, the production device cancels the air separation device and the methane conversion device, and provides scientific and reasonable coke Furnace gas hydrogen extraction to ethanol process route.

Referring to Figure 1, the apparatus used in the production process of the present invention comprises a coke oven gas prepurification device, a CO converter, a wet desulfurization and CO ₂ removal device, a fine desulfurization and methanation device, a pressure swing adsorption methane device, and a pressure transformation. The adsorption hydrogen extraction device, the coke oven gas compression device, the hydrogen compression device, the methane gas compression device, and the acetic acid hydrogenation ethanol production device are all mature chemical devices commonly used in the coal chemical industry. The specific steps for the production of ethanol after reconstitution of these devices are as follows:

(1) The coke oven gas produced by coking and chemical production is sent to the pre-purification device for preliminary purification, and most of the impurities such as coal tar, naphthalene and benzene are removed; and then the coke oven gas compressors 1 and 2 are passed. After pressurization, it enters the CO converter. Under the action of the catalyst, CO reacts with water vapor to form CO2 and H2, and at the same time converts most of the organic sulfur into H2S. The shift gas enters the wet desulfurization unit for wet desulfurization and removes 80. More than % H2S, which can reduce the subsequent fine desulfurization load to reduce production cost; the wet desulfurization gas is pressurized into the wet decarburization device after being pressurized in stages 3 and 4; the decarburized gas enters the fine desulfurization The device removes the total sulfur content in the gas to below 0.1 ppm, and simultaneously converts a trace amount of CO and CO2 in the gas into methane, and the gas becomes a purifying gas with high purification degree;

(2) The refined coke oven gas obtained in the step (1) enters the pressure swing adsorption methane extraction device to extract methane, and the extracted methane is compressed and sold as natural gas or vehicle CNG;

(3) The tail gas of step (2) is dehydrogenated by a pressure swing adsorption hydrogen extraction device, and the extracted hydrogen gas is compressed to 4 Mpa (g), and then deacidified to a acetic acid hydrogenation unit to react with acetic acid to form crude ethanol;

(4) The tail gas obtained in step (3) has a sulfide content of less than 0.1 ppm. As a coke oven and a fuel for chemical production, there is almost no sulfur pollutant in the combustion exhaust gas, which completely solves the problem of sulfur pollution of the flue gas in the coking plant.

Take the coke oven gas produced by an annual output of 1 million tons of coke oven as an example:

Coke oven gas produced by coke oven, after initial purification, coke oven gas, 50,000 Nm ³ per hour, composition: H ₂ 58%, CO 7.4%, CO ₂ 3.5%, CH ₄ 24.2%, CnHm2.3% , N ₂ 4.6%, H ₂ S 100-200mg/Nm ³ ; organic sulfur 200-400mg/Nm ³ ; calorific value 4000 kcal / Nm ³ , send pre-purification device to remove most of the coal tar, naphthalene and Impurities such as benzene; pre-purified gas, the compressor is boosted to 0.8 MPa (g) into the CO converter, CO reacts with steam to form CO ₂ and H ₂ O, and most of the organic sulfur in the coke oven gas Conversion to H ₂ S; shifting gas into the wet desulfurization unit, removing more than 80% of H ₂ S, which can reduce the subsequent fine desulfurization load to reduce production costs; the initial desulfurization gas is boosted to 2.6MPa by the compressor (g) Entering the wet decarburization device to remove most of the CO ₂ ; the decarburized gas enters the fine desulfurization device, and removes the total sulfur content in the gas to below 0.1 ppm, while at the same time small amounts of CO and CO ₂ conversion to methane, the gas becomes _2, CH _4, CmHn, N high purification degree of purification of gas containing only H _2; purge air enters A pressure swing adsorption device mentioned methane, extracted (surplus portion of the fuel as coke) methane 4900Nm ³ / h, pressurized to 4.0MPa (g) sold as pipeline natural gas SNG; tail gas put into the methane to hydrogen pressure swing adsorption The device can extract 99.99% pure hydrogen 25000Nm ³ /h according to the hydrogen extraction rate of 85% for use in the hydrogenation unit; the exhaust gas after hydrogen extraction is 15700Nm ³ /h, and its composition is: H ₂ 28.28%, CH ₄ 52.45%, CnHm4.77%, N ₂ 14.5%, calorific value 5900 kcal / Nm ³ , coke oven and chemical production as fuel. The tail gas is used as a fuel for a coke oven, and the total sulfur content is less than 0.1 ppm, which completely solves the problem of sulfur pollution of the coke oven gas.

The raw material acetic acid is 33.5 tons/h, and the hydrogen produced is 25000 Nm ³ /h. The reaction is carried out in a hydrogenation acetic acid to ethanol plant to produce 25 tons/h of anhydrous ethanol product with a purity of 99.98%.

The above-described embodiments are merely illustrative of one embodiment of the invention, and are not intended to limit the scope of the invention. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention.

Claims

A method for extracting hydrogen from coke oven gas to produce ethanol, comprising coke oven gas prepurification device, CO converter device, wet desulfurization device, wet CO 2 removal device, fine desulfurization and methanation device, and pressure swing adsorption methane The device, the pressure swing adsorption hydrogen extraction device, the coke oven gas compression device, the hydrogen compression device, the methane gas compression device, and the acetic acid hydrogenation ethanol production device are characterized in that the specific steps are as follows:

a. The coke oven gas produced by the coking chemical production is sent to the coke oven gas prepurification device to remove impurities;

b. The pre-purified coke oven gas is pressurized by the coke oven gas compressor and then enters the CO converter to generate a shift gas;

c. changing gas into the wet desulfurization device for wet desulfurization;

d. The gas after the wet desulfurization is pressurized by the compressor and then enters the wet decarburization device;

e. The decarburized gas enters the fine desulfurization device, and the desulfurized gas is a high-purification purification gas;

f. Purifying gas enters the pressure swing adsorption methane extraction device, extracts part of methane gas, and is sold as natural gas after being pressurized;

g. The tail gas after the methane is introduced into the pressure swing adsorption hydrogen extraction device, and most of the hydrogen is extracted for use in the hydrogenation device;

h. acetic acid and hydrogen enter the acetic acid hydrogenation unit, acetic acid and hydrogen react to form ethanol, which is rectified and sold as anhydrous ethanol product;

i. Exhaust gas after hydrogen extraction, coke oven and chemical production as fuel.
The method for producing hydrogen by using coke oven gas to produce ethanol according to claim 1, wherein the main component (molar percentage) of the coke oven gas is: H2 55-60%, CO 5-8% , CO2 1.5-3.5%, CH4 23-27%, CnHm 2-4%, N2 3-7%, H2S 100-200mg/Nm3; organic sulfur 200-400mg/Nm3; calorific value 3500-4500 kcal/Nm3.
The method for producing hydrogen from a coke oven gas by using a coke oven gas according to claim 1, wherein the coke oven and the fuel required for chemical production are provided by a hydrogen extraction tail gas in a later process; The required water vapor is provided by a coke dry quenching unit.