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新奥门葡京娱乐场  

澳门新葡京娱乐

   
 

FIELDS

  Coke Oven Gas Processing
   
 

Traditional utilization method of coke oven gas is mainly used as industrial fuel and domestic fuel gas after removal of tar, naphthalene, benzene and H2S. In this way, not only valuable chemical raw material is directly burned, but also CO2, SO2 and NOx are produced to pollute the environment.

Coke oven gas is rich in H2, CH4 and CO, and is a valuable raw material for the synthesis of chemicals. According to literature records, in the 20th century of 1970s, a coke oven gas to methanol production plant was constructed in former Soviet Union, but it already shut down. In 2006, the first coke oven gas to methanol plant was put into production in Qujing City, Yunnan Province, China, the capacity of the plant was 80kt/a pure methanol. According to incomplete statistics, to December 2014, total production capacity of coke oven gas to methanol plants that have been completed and put into production in China is nearly 8,000kt/a. There are about more than 50 production enterprises and the largest production capacity of single set reaches 300kta.

Usually, coke oven gas to methanol plants are associated plants of coking industry. They belong to energy-saving technology and measures must be taken for coking projects according to "Admittance Condition of Coking Industry" issued by the Chinese government (Document No.76, 2004 of China National Development and Reform Commission )(coke oven gas of newly built or expansion coke ovens must be completely recycled for utilization, not be discharged directly or lighted the torch). This type of project can convert coke oven gas into basic chemical raw materials with high added value, which conforms to the requirements of circular economy, so CDM project policy support (i.e. CLEAN DEVELOPMENT MECHANISM) can be applied.

In addition, coke oven gas to ammonia and urea, and coke oven gas to LNG are also major development direction of coke oven gas comprehensive utilization in recent 10 years in China.

澳门葡京娱乐场官网

Position of ECEC in the industry

200kt/a coke oven gas to methanol project of Linhuan Coking & Chemical Co. of Huaibei Coal Mining Group is the first coke oven gas comprehensive utilization project undertaken by ECEC. The project was a built in EPC mode by ECEC. The project was completed and realized successfully commissioned in one stroke in September, 2010. Since 2006, ECEC in China has completed three comprehensive utilization projects of coke oven gas, which have been put into operation. Both production capacity and quality of product of them can reach design index.
 

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200kt/a coke oven gas to methanol project of Linhuan Coking & Chemical Co. of Huaibei Coal Mining Group, its design capacity is 200kt/a pure methanol. Coke oven gas is pressurized by motor driven reciprocating compressor, adopting advance process flow of PDS wet process crude desulphurization, organic sulfur two-stage hydrogenation in series with zinc oxide protection dry process fine desulphurization, partial oxidation by pure oxygen catalysis, 5.0MPa low pressure methanol synthesis, three-tower rectification (high performance regular packing, double-action rectification).The project is built in EPC mode by ECEC.

Coke oven gas comprehensive utilization project of Xinjiang Dahuangshan Hongji Coking and Chemical Co., Ltd., its design capacity is 120kt/a liquid ammonia (intermediate product),220kt/a urea (final product). Coke oven gas is pressurized by motor driven reciprocating compressor, adopting advance process flow of ADA + PDS wet process crude desulphurization, organic sulfur two-stage hydrogenation in series with zinc oxide protection dry process fine desulphurization, partial oxidation by pure oxygen catalysis, two stage CO conversion, polyamine process (improved MDEA) CO2 removal technology, domestic low pressure ammonia synthesis, carbon dioxide steam stripping process urea production technology. The project is built in EPC mode by ECEC.

200kt/a coke oven gas to methanol project of Cangzhou China Railway Equipment Manufacturing Materials Co., Ltd, its design capacity is 200kt/a pure methanol. Coke oven gas is pressurized by motor driven reciprocating compressor, adopting advance process flow of PDS wet process crude desulphurization, organic sulfur two-stage hydrogenation in series with zinc oxide protection dry process fine desulphurization, partial oxidation by pure oxygen catalysis, 5.0MPa low pressure methanol synthesis, three-tower rectification (high performance regular packing, double-action rectification)The project is built in EPC mode by ECEC.

 


Source of technology

ECEC has accumulated more than 10 years of rich experience in coke oven gas comprehensive utilization projects. ECEC has maintained long-term relations of cooperation with a number of companies engaged in coke oven gas comprehensive utilization technology study in China, at the same time, maintained good communication and cooperation with the internationally famous licensors. Main copartners in methanol synthesis technology and coke oven gas methanation technology are TOPSøE and Johnson Matthey Catalysts. In addition, ECEC is strategic cooperative partners of advanced ATR self heating pure oxygen catalysis partial oxidation process of Johnson Matthey Catalysts in China. The application of the process makes ECEC in an absolutely leading position in coke oven gas to methanol industry in China.

Sample projects

With an annual output of 140 million tons of coke in the whole country, surplus byproduct coke oven gas reaches 280 ×108Nm3 except for fuel gas used by coke oven. About 14 million tons of methanol can be produced every year if we can make effective use of byproduct coke oven gas. 200kt/a coke oven gas to methanol plant of Cangzhou China Railway Equipment Manufacturing Materials Co., Ltd. is a typical production plant by using coke oven gas as raw material.

The project was built in EPC mode by ECEC. Basic design of the project began on September 4, 2009, site construction began in March,2010, mechanical completion was realized at the end of June, 2011 and successfully commissioned in one stroke was achieved on September 25, 2011.

During the period from September,2011 to September,2014, the plant has been in a long period of stable operation state, the annual average production of methanol is 220,000 tons. The methanol product quality, raw materials and utilities consumption indicators reach the design requirements and are in an absolutely leading position in China.

Feed stock pure oxygen and utilities (IA, PA, N2, electricity, demineralized water, mobilization steam) for the plant are all supplied by the whole plant. Steam condensate is sent to demineralized water station of the whole plant for reclamation, production and domestic wastewater are sent to waste water treatment unit of the whole plant.

The project is composed of the following main units:
 

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Gas-holder: thin oil seal dry-seal gasholder with capacity of 50,000m3

Coke oven gas compression: coke oven gas is compressed from 3KPa(G) to 2.6Mpa(G) by motor driven reciprocating compressor for downstream process. The compressors adopt six-line four-stage reciprocating compressors, coke oven gas enters crude desulfurization process through two-stage compression by coke oven gas compressor, after crude desulphurization, coke oven gas is sent into compressor again for three-stage and four-stage compression. Two equipments are operated while one equipment is standby.

Crude desulphurization and purification of coke oven gas:
using PDS as catalyst and dilute alkali solution as absorption medium, for removal of inorganic sulfur from coke oven gas, at the same time, absorption and removal of HCN. The rich solution absorbing hydrogen sulfide is changed into elemental sulfur through air oxidation for regeneration cycle use. By dilute alkali absorption, hydrogen sulfide in coke oven gas can be reduced to ≤ 20mg/Nm3, then hydrogen sulfide in coke oven gas can be removed to ≤ 1mg/Nm3 by dry process iron oxide protection desulfurizing agent.
PDS wet process crude desulfurization in series with dry process iron oxide protection process has advantages of high desulfurization efficiency, removal of HCN, easy solution regeneration and low service cost.

Coke oven gas hydrogenation for fine desulphurization:
after crude desulphurization purification, organic sulfur and the remaining H2S content in coke oven gas still cannot meet the requirement of the catalyst of downstream process for sulfur content, hydrogenation fine desulfurization process must be adopted for further desulfurization of coke oven gas. Metallic oxide works well in inorganic sulfur removal, but it cannot remove organic sulphur, therefore the organic sulphur shall be converted to inorganic sulfur by hydrogenation, and then be removed by using metallic oxide (dry process fine desulfurizing) in order to satisfy the requirements of following sections for total sulfur in raw gas.
Iron molybdenum prehydrogenation, iron molybdenum hydrogenation, 1-stage medium temperature zinc oxide, cobalt molybdenum hydrogenation, medium temperature zinc oxide hydrogenation fine desulphurising process are used one by one in order to ensure that S content of coke oven gas at the outlet is lower than required 0.1PPM and effectively protect pure oxygen conversion catalyst and methanol synthesis catalyst.

Pure oxygen conversion and conversion gas heat reclaim:
self-heating pure oxygen catalysis partial oxidation technology is used for preparation of methanol synthetic gas, which makes hydrogen-carbon ratio of methanol synthesis raw gas is more reasonable and is favorable to methanol synthesis and saving consumption of coke oven gas. At the same time, pure oxygen conversion outlet temperature is 1000~1030℃ and methane content at the outlet is controlled at 0.3% (dry basis),which is conducive to improve the one-way methanol synthesis conversion rate, reduce the amount of purge gas and circulating gas so as to save energy consumption.
Conversion gas waste heat recovery is by-product medium pressure steam of 3.8MPa (G), preheating boiler feed water, byproduct low-pressure steam, preheating demineralized water and by-product medium pressure steam of 3.8MPa (G) in sequence, they are overheated through convection section of heating furnace and supplied to synthetic gas compressor turbine, thus high energy is utilized fully.
This unit is equipped with a saturation tower to heat conversion process condensate for humidifying coke oven gas to achieve cyclic utilization, this action firstly can reduce consumption of medium pressure steam for coke oven gas humidification, secondly can reduce the discharge of waste water, and thirdly can reduce consumption of fresh water.

Methanol synthesis:
advanced and reliable isothermal synthesis tower technology developed by East China University of Science and Technology is used, bed temperature of methanol synthesis tower is distributed evenly which is close to the best synthesis temperature, byproduct medium pressure steam is supplied to the units of methanol distillation, etc. Crude methanol is obtained from synthetic gas out of the tower through heat exchange, cooling and condensation and gas-liquid separation, then the gas is pressurized and returned to inlet of synthesis tower.

Methanol rectification:
4-tower rectification process is used in this section (pre column, pressurized tower, atmospheric tower, recovery tower).The main purpose of pre column is removing the dissolved gas in crude methanol (such as CO2, CO, H2 ,etc.) and low boiling point components (such as dimethyl ether, methyl formate). Pressurized tower and atmospheric tower are designed to remove water and impurities with high boiling points (such as ethanol, higher alcohols) and obtain first quality methanol product with high purity. Methanol recovery tower is designed to further recover methanol, reduce methanol content in the wastewater, ensure that the wastewater reach relevant standards and be discharged directly. High efficient regular packing is used for rectification tower to ensure the products of high quality and low consumption of steam.

Synthetic gas compression:
Centrifugal compressor driven by medium pressure condensing steam turbine is used as synthesis gas compressor. Double cylinder and multistage compression is used, the fresh synthesis gas pressurized by low-pressure cylinder goes through heat exchange and liquid separation outside cylinder and continues to enter the high pressure cylinder for compression, circulation gas enters circulation section of high pressure cylinder and mixes with fresh gas in the cylinder, then the synthetic gas is compressed to 5 - 6.5Mpa (G) and supplied to synthesis section.

Flare stack:
for safety vent

Liquid storage and transport facility:
Two sets of 10000 m3 methanol product storage tank with inner floating roof and necessary auto loading trestle are provided.

Control system of the plant: automatic control system of DCS is used for this plant to ensure stable, convenient and quick operation control of the whole plant. At the same time, a set of safety instrument system (SIS) is used to provide safety guarantee for all critical equipment and systems of the whole plant.


 

   
 

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