Science articles

URALCHEM OKHK OJSC is one of the largest companies in the market of nitrogen and phosphorus fertilizers in the Russian Federation and the CIS, with facilities for the production of more than 2.5 million tons of ammonium nitrate, 2.8 million tons of ammonia, 0.8 million tons of mono- and diammonium phosphate, 0.8 million tons of complex fertilizers, 1.2 million tons of urea per year. URALCHEM OKHK OJSC takes the second place in the world and the first in Russia in the production of ammonium nitrate.

Among the main production assets of OJSC “URALCHEM OKHK” should be called the Azot branch, Berezniki, Perm Territory; Mineral Fertilizers OJSC, Perm; OJSC "Mineral Fertilizer Plant of the Kirov-Chepetsk Chemical Combine", Kirov-Chepetsk, Kirov Region; Voskresensk Mineral Fertilizers OJSC, Voskresensk, Moscow Region.

In the fall of 2011, specialists of Mineral Fertilizers OJSC applied to CJSC LOTOS with a request to develop and manufacture an intensified LOTUS ® refrigerator for a technological position (114 - C1) in the production of ammonia, in limited placement dimensions.

Earlier, at this position (114 - C1), a plate heat exchanger of the Alfa Laval compoblock type (Alfa Laval), type CPK75-V-350, was installed , which, during operation, used for cooling synthesis gas with demineralized water for no more than 3-4 months, after which he had to be stopped for repair. The heat exchanger did not produce calculated heat engineering parameters for the depth of cooling of the synthesis gas, in addition, there was cracking along the welded butt joint of the plates with a length of 70 mm.

The engineers of CJSC “LOTOS” got down to work.

Yuri Vladimirovich notes the attentive attitude of the specialists of LOTOS CJSC to the tasks and the prompt development of technical solutions using the LOTUS ® heat exchanger for cooling synthesis gas. The solution developed by them that is optimal for this production using the intensified heat exchange refrigerator  L OTUS ® BEM GW - 3.15 - 08173/1 in accordance with TU 3612-001-60793544-2009 took into account the comments and wishes of the technical specialists of Mineral Fertilizers OJSC.  

A word to the author of the letter:

1. The LOTUS ® heat exchanger is made completely according to the counter-current temperature scheme, which provides cooling of the synthesis gas to 112 0 C at a flow rate of demineralized water of 490 t / h.
2. Maximum compactness of the LOTUS ® heat exchanger is ensured due to the use of tubes of the minimum allowable diameter, taking into account the low viscosity of the synthesis gas.
3. In this LOTUS ® heat exchanger, flows are balanced over both spaces and the necessary flow rates of moving media (synthesis gas - 21 m / s, demineralized water - 0.89 m / s) are ensured, ensuring a uniform distribution of the heat load over the entire heat transfer surface.
4. A high heat transfer coefficient of up to 1386.0 W / (m2 * K) was achieved for these environments.
5. The high-speed movement of demineralized water in the annulus has been organized, which minimizes the volume of stagnant zones, which allows the most efficient use of the entire heat transfer surface.
6. The conditions have been created for the stable operation of the apparatus with a decrease / increase in the cost of working media by + 15 - 30%.
7. During the development, a full range of strength calculations was carried out, which made it possible to ensure reliable operation of the LOTUS ® heat exchanger at a pressure and temperature corresponding to the initial design data.

The refrigerator L OTUS ® BEM GW - 3.15 - 08173/1 in accordance with TU 3612-001-60793544-2009 at the position 114-C1 was put into operation in May 2012. In October 2012, after five months of operation, a scheduled inspection of the L OTUS ® BEM GW - 3.15 - 08173/1 refrigerator was carried out. On the fact of inspection of comments from the specialists of OJSC Mineral Fertilizers regarding the operability of the LOTUS ® heat exchange equipment, there was no. Expired period of operation of this LOTUS ® refrigerator      showed that all the thermotechnical operating parameters were implemented, and the heat exchanger cools the synthesis gas to a temperature of 112 0 С at a water temperature at the inlet of the apparatus of 111 0 С due to the presence of a surface reserve of 63% even with a 5% increase in the consumption of synthesis gas. To transfer heat from the temperature difference between the inlet and outlet 1 0 C can only truly intensive heat transfer equipment, and how are intensified exchanger coils L OTUS ® .

Over the past period of operation, this LOTUS ® refrigerator showed the following parameters:

No. p / p	Parameter	Units measuring	Value
			estimated	actual
one.	Synthesis gas consumption Demineralized water consumption	t / h	81 490	85 490
2.	Synthesis gas temperature: - at the entrance - at the exit	0 C	158.0 116.0	160,0 112.0
3.	The temperature of demineralized water: - at the entrance - at the exit	0 C	111.0 116.5	111.0 116.0

The intensification of heat transfer through the use of various design solutions in L OTUS ® heat exchangers has significantly increased the efficiency of heat transfer processes at OJSC Mineral Fertilizers. As a result of the introduction of the heat exchanger L OTUS ® BEM GW - 3.15 - 08173/1 pos. 114-C1 natural gas consumption per tonne of ammonia decreased by 3–3.5 cubic meters, which is especially important in connection with the increase in gas tariffs from July 1, 2012. In addition, the heat exchanger L OTUS ® BEM GW - 3.15 - 08173/1     pos. 114-C1 makes it possible at a certain stage of production to hold a higher load in hot weather, and in winter to stop part of the fans on the subsequent AVZ heat exchanger to save energy.

Positive results due to the introduction of the refrigerator of L OTUS ® , were commented upon by the technical specialists of JSC "Mineral fertilizers" in the corporate magazine of the UCC "URALCHEM" for the 3rd quarter 2012.

The decrease in metal consumption, coupled with significant energy savings and the unconditional reliability of the heat exchanger (even compared to foreign counterparts), led to a high assessment of Mineral Fertilizers OJSC specialists and their willingness to recommend L OTUS ® heat exchange equipment for use in similar plants.