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  Nitrogenous Fertilizers

The production of nitrogen fertilizers in China started in 1930s when the highest total output was only 226kt/a. After new China was founded, the Chinese government attached great importance to the development of nitrogenous fertilizer industry. By the end of 1965, 15 medium-sized nitrogenous fertilizer plants had been put into operation in the country, with the total output of synthetic ammonia reaching 1,300kt/a and above. In 1964~1966, preparation was made for the construction of Sichuan Luzhou Natural Gas Chemical Plant and Shanxi Xingping Fertilizer Plant using imported technology, which were successively put into production in 1970. In the following one decade and more, on the basis of continuously summarizing the construction and production experience with medium-sized nitrogenous fertilizer plants, a number of other medium-sized nitrogenous fertilizer production plants were built. After 1978, China carried out an all-round rectification of medium-sized nitrogenous fertilizer plants in terms of organization, management and technology, and conducted gap filling and potential tapping of the existing enterprises targeting energy saving and consumption reduction, which increased the productivity of the existing plants. As of 1983, the number of medium-sized nitrogenous fertilizer plants in the country amounted to 56, and the raw materials used by the plants reflected the policy of making use of coal, oil and gas simultaneously with coal as the main raw material. As a result, the nitrogenous fertilizer production series in the country came into being.

To meet the increasing demand of agriculture for nitrogenous fertilizer and with the large-scale development of petroleum and natural gas in the country, China introduced 13 sets of complete production plants from the United States, Holland, Japan and France in 1973, each having a capacity of 1000t/d of synthetic ammonia and 1620~1740 t/d of urea, of which 10 sets used natural gas as raw material and 3 sets use light oil as raw material. With the joint efforts made by the provinces and cities concerned, these large-scale nitrogen fertilizer plants were completed with high speed, high quality and high level and were put into operation one after another between May 1976 and Sep. 1979. Although the output of these large-scale nitrogenous fertilizer plants accounts for 20% only of the total output of nitrogenous fertilizer in the country, they have played a significant role in enhancing the technical level and management level of the country's nitrogenous fertilizer industry. Since 1983, the nitrogenous fertilizer output of the country ranked the second in the world, only next to that of the former Soviet Union.

Position of ECEC in this industry

After ECEC was established, the first project it undertook was the design of the phase I project (including basic engineering design and detail engineering design) of Huainan Chemical Fertilizer Plant (the present Huainan Chemical Group). This project was one of the medium-sized nitrogenous fertilizer enterprises built up during the "Second Five-Year Plan" period of the country, the design capacity of which was 50kt/a of synthetic ammonia and 110kt/a of ammonium nitrate. The first system of the project was completed and successfully commissioned in one stroke on Sept. 23, 1965, and the second system was completed and put into operation on Dec. 30, 1965.

In 1966, ECEC implemented a new process flow for synthetic ammonia-methanol combined production (known as medium-pressure co-production of methanol) in the design of phase II expansion project of Huainan Chemical Fertilizer Plant. To explore the production conditions and process flow for the industrialization of the co-production of methanol, ECEC carried out the design and industrial test of a pilot plant in Danyang Chemical Fertilizer Plant, Jiangsu Province during 1967~1968 and finally made a success of the new process flow test of co-production of methanol. On such a basis, ECEC accomplished the design of the co-production of methanol project of Huainan Chemical Fertilizer Plant for 20,000t/a of fine methanol in 1969, which was successfully commissioned in one stroke in July 1973. This engineering design won the excellent design prize of the former Ministry of Chemical Industry in 1981. In 1973, ECEC organized and participated in the negotiations with foreign companies for the import into China of 3 out of the 13 sets of large chemical fertilizer plants and specifically implemented the chemical fertilizer plant of Anqing Petrochemical Complex, which uses naphtha or refinery gas as raw material to produce 300,000t/a of synthetic ammonia and 520,000t/a of urea.

In the past 40 years, ECEC has accomplished 36 new construction and technical revamping projects of small, medium and large-sized nitrogenous fertilizer projects in China, all of which have been completed and put into production and the productive capacities and product quality of which have all met the design figures. The productive capacities (as synthetic ammonia) of these projects are 2~600kt/a. The raw materials for their production include coke, anthracite, bituminous, naphtha, refinery gas and coke oven gas, etc. The product variety includes synthetic ammonia, ammonium bicarbonate, ammonium nitrate, urea as well as nitric acid, methanol, formaldehyde etc. Typical projects completed by ECEC include:










The phase I project of Huainan Chemical Fertilizer Plant, whose design capacity is 50kt/a of synthetic ammonia and 110kt/a of ammonium nitrate. The synthetic ammonia system uses a process with lump coal or coke as raw material, which consists of fixed-bed, atmospheric-pressure, intermittent gasification, atmospheric pressure conversion, 1.8Mpa water wash decarbonization, 13MPa copper and alkali wash purification and 32Mpa ammonia synthesis.

The phase II project of Huainan Chemical Fertilizer Plant, which mainly includes: two sets of side-fed, tamped coking furnace and associated coking recovery system, which use Huainan coal as raw material and have a total capacity for 560kt/a of coke; an ammonia synthetic gas production unit with a design capacity for 45kt/a of synthetic ammonia, which uses coke oven gas as raw material and pressurized catalytic partial oxidation process; a 25kt/a crude methanol production unit using the process of co-production of methanol and associated methanol rectifying unit; a 110kt/a urea plant using an aqueous solution total circulating process; a 40kt/a concentrated nitric acid plant; a 50kt/a crude tar and 15kt/a crude benzol purification plant as well as utility and auxiliary facilities corresponding to the second-phase expansion project.

The nitrogenous fertilizer plant of Anqing Petrochemical Complex, which uses naphtha or refinery gas as raw material to produce 300,000t/a of synthetic ammonia and 520,000t/a of urea. The ammonia unit consists of naphtha desulfurization, steam reforming, high-temperature conversion, hot potash decarbonization, centrifugal steam turbine-driven compression and TOPSØE S-200 ammonia converter, while the urea unit uses CO2 stripping process for urea production. In 1996, ECEC completed the revamping of raw material route of Anqing Petrochemical Complex, substituting refinery gas instead of 50% of naphtha to produce synthetic ammonia. The engineering design of the revamping project of the said unit was completed by the end of 1996, and the unit was successfully commissioned in 1997.

The technical revamping project of the nitrogenous fertilizer plant of Guangzhou Petrochemical Complex, the 300,000t/a synthetic ammonia and 520,000t/a urea unit of Guangzhou Petrochemical Complex used naphtha as raw material. In 1999, ECEC completed the revamping of raw material route of the plant for synthetic ammonia in order to replace naphtha with partial refinery gas in the production of synthetic ammonia, and later, by cooperating with TOPSØE, completed the expansion and energy saving retrofitting for 10% increase of production capacity.

The revamping and expansion project of Huainan Chemical General Works, using Texaco (now GE of U.S.)coal water slurry gasification process, sulfur-resistant conversion, NHD desulphurization decarbonization ,home-make centrifugal compressor and TOPSOE S-200 ammonia synthesis process

600kt/a synthetic ammonia and 800kt/a urea project of Hebei Cangzhou Zhengyuan Chemical Fertilizer Co., Ltd., for detail, please refer to Sample Project.

Source of technology

ECEC has accumulated more than 50 years' engineering experience in the aspect of nitrogenous fertilizer field. In order to maintain the technical superiority in this field, ECEC maintains long-term cooperative relations with a number of Chinese companies engaged in the technical research of nitrogenous fertilizer and, at the same time, keeps good cooperative relationships with world-known licensors, such as TOPSØE, Casale, GE, STAMICARBON, SNAMPROGETTI, LINDE, etc.

Sample project:

China is a country with coal as its main energy resources. The synthetic ammonia industry of China has been constructed and developed with coal as the main raw material. The productive capacity of synthetic ammonia plants with coal as raw material accounts for 80% and above of the total domestic synthetic ammonia production capacity. 600kt/a synthetic ammonia and 800kt/a urea project of Hebei Cangzhou Zhengyuan Chemical Fertilizer Co., Ltd. is a typical synthetic ammonia plant with coal as raw material.

The basic engineering design of 600kt/a synthetic ammonia and 800kt/a urea project of Hebei Cangzhou Zhengyuan Chemical Fertilizer Co., Ltd. was started in May 2011 and approved in September 2011. On-site construction of the project was started in December 2012 and the project is planned to be put into production by the end of December 2014. The project is composed of the following main units:







Gasifier: including raw coal storage and transportation, pulverized coal preparation, home-made HTL gasification, crude synthetic gas washing, slag/water treatment
Operating pressure of gasifier is 4.0MPa, 2 sets of home-made HTL gasifiers (daily coal handling capacity of a gasifier is 2000 tons) are provided, and two gasifiers are in operation. China Aerospace Science and Technology Corporation is responsible for supply of process package and key equipment, basic engineering design and detailed engineering design of the gasifiers.

Purifier: including crude synthetic gas conversion, desulphurization / decarbonization, methanation and sulfur recovery
Domestic sulfur-resistant conversion catalysts is used for synthetic gas conversion, and detailed engineering design is completed independently by ECEC with our own technology. Conversion section is provided with 3 shift-converters to make full use the steam in crude synthetic gas from HTL gasification section and ensure that CO content in synthetic gas leaving conversion section meets the requirement of synthetic ammonia unit (≤ 0.35 % mol), and the heat produced during course of reaction is recovered by means of byproduct medium and low pressure steam, heating boiler feed water and demineralized water.
Cryogenic methanol wash process developed by Dalian University of Technology is used for desulphurization / decarbonization to selectively remove CO2 and H2S from synthetic gas. Desulphurization / decarbonization section is equipped with packed absorption tower and detailed engineering design is completed by ECEC.
The technology developed by Hangzhou Zhongtai is applied to liquid nitrogen wash section to remove residual CO and CH4 from synthetic gas and obtain ammonia synthesis raw gas with appropriate ratio of H2/N2. Liquid nitrogen section is designed independently by ECEC.
Three-reactor Claus sulfur recovery technology developed by Shangdong Sanwei Technology Corporation is applied to sulfur recovery section, exhaust gases is sent to boiler for incineration, after desulphurization together with boiler flue gas, it's discharged after reaching the standard. Process package is supplied by Shangdong Sanwei Technology Corporation. Detailed engineering design is completed by ECEC.

Synthesis unit: including synthetic gas compression (circulating section included), ammonia synthesis
Domestic designed and manufactured steam-driven centrifugal compressor is selected for synthetic gas compression. Detailed engineering design is completed independently by ECEC. Qualified synthetic gas and circulation gas are pressurized to 14.0MPa in compression section to satisfy the requirement for ammonia synthesis.
Ammonia synthesis technology owned by Cangzhou Zhengyuan Chemical Fertilizer Co., Ltd. is applied to ammonia synthesis section , process design of high pressure synthesis loop for ammonia synthesis is supplied by Cangzhou Zhengyuan Chemical Fertilizer Co., Ltd. while detailed engineering design is completed by ECEC.

Urea unit: it is used to produce urea by using ammonia produced by synthetic ammonia unit and high purity CO2 produced by purifier.
CO2 air stripping technology owned by ECEC is used for urea unit, basic engineering design and detailed engineering design are completed independently by ECEC.

Air separation unit: it's used to provide high purity oxygen gas for gasifier and high purity N2 for ammonia synthesizer.
Proprietary technology and key equipment of air separation owned by Air Product are used for air separation unit, high pressure oxygen gas is produced directly by liquid oxygen in-plane compression flow and nitrogen gas is re-pressurized by compressor. Production capacity of air separation unit is 60000Nm3/h oxygen gas. ECEC is responsible for associated civil engineering design of air separation unit.

Control system of the plant: Domestic DCS and SIS are used for whole synthetic ammonia and urea production system to realize automation of production control and detection.



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