Hydrate Control

Thermodynamic inhibitors Antinucleants Growth modifiers Slurry additives Anti-agglomerates Methanol or glycol modify stability range of hydrates. Prevent nucleation of hydrate crystals. Control the growth of hydrate crystals. Limit the droplet size available for hydrate formation. Dispersants that remove hydrates. 

The usual practice for avoiding the plugging of production facilities by hydrates is to add thermodynamic inhibitors, such as methanol or glycol. A newer concept is the injection of low-dosage additives either kinetic inhibitors, which delay nucleation or prevent the growth of hydrate crystals, or hydrate dispersants, which prevent the agglomeration of hydrate particles and allow them to be transported within the flow [880,1387]. Hydrate control is discussed extensively in Chapter 13. Classes of hydrate control agents are shown in Table 11-9, and additives are shown in Table 11-10. 

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From a hydrate melting standpoint it is possible in the winter time to have too cold a liquid temperature and thus plug the liquid outlet of the low temperature separator. It is easier for field personnel to understand and operate a line heater for hydrate control and a multistage flash or condensate stabilizer system to maximize liquids recovery. 

Hydrate control is not included in this chapter, but is discussed in Chapter 13 because of the relative importance and difference in chemical mechanism. Many chemicals added to water will result in a depression of the freezing point. The practical application is restricted, however, because of some other unwanted effects, such as corrosion, destruction of rubber sealings in engine parts, or economic aspects. 

Gas hydrates were first reported at the beginning of the 19th century, and until the 1930s they remained a scientific curiosity. At that time it was realized that hydrates were more likely to be the causative agent in blocking pipelines than ice. Today, gas hydrate control continues to be a problem in the oil and gas industry. In the 1960 s it was realized that natural gas hydrates are present in the geo-sphere with worldwide reserves estimated at 10,000 to 40,000 trillion cubic meters (TCM). Considerable efforts are underway to refine global estimates and to develop technology and exploit this resource. On the other hand these hydrates may... 

Bucklin, R.W., Toy, K.G, Won, K.W., Hydrate Control of Natural Gas Under Arctic Conditions Using TEG in Proc. Gas Conditioning Conference, Norman, OK, (1985). 

Figure 6 The Snriivit development project featuring sub sea templates down to 320 m water depth, well stream to shore, and hydrate control by MEG. The system is closed so that there will be no emissions offshore. The project comprises CO2 re-injection and remote power system and control facilitated from the shore at a distance of 160 km [17].

Both catalyst activity and tar formation are directly affected by the state of hydration of the phosphoric acid-kieselguhr type of catalyst. At the higher temperature it is more difficult to maintain proper hydration. Hydration control is required because the catalyst has an optimum water content which determines the activity and selectivity of the catalyst. The water-vapor pressure varies at different catalyst temperatures and it is important to keep the water content of the hydrocarbon in equilibrium with that of the catalyst. In those units where water of saturation in the feed is insufficient, additional water must be injected into the feed as catalyst requirements dictate. The solid phosphoric acid type of catalyst contains the proper amount of water when manufactured and the art of catalyst hydration has reached such a point that catalyst in properly operated polymerization units no longer fails from coke formation or loss of activity. 

FCS water management is the key factor for an efficient and reliable operation of a PEMFC stack. Membrane hydration control and water balance for a durable operation of FCS are the main objectives of this sub-system, whose design and control issues, strictly connected to thermal management but also to reactant subsystem components, are discussed in Sect. 4.5. The possibility of interactions between the wet and warm cathode outlet stream and the components of thermal and water management sub-systems is also discussed. 

Hydration Control of Ion Distribution in Polystyrene Sulfonate Gels and Resins... 

A GAS HYDRATE, also known as a gas clathrate, is a gas-bearing, icelike material. It occurs in abundance in marine sediments and stores immense amounts of methane, with major implications for future energy resources and global climate change. Furthermore, gas hydrate controls some of the physical properties of sedimentary deposits and thereby influences seafloor stability. 

Competition for Hydration Controls the Amount of Pentagonally Arranged Water... 

Investigations of crude oils with respect to hydrate control have thus been conducted for numerous years [9]. Most of them show results on plugging or non-plugging occurrence in laboratory facilities or pilot loops and do not allow us to preset flow conditions... 

In 1934, Hammerschmidt showed that gas hydrates are implicated in a natural gas pipeline blockage and since then hydrate control has been a major activity in the gas and oil industry with a substantial associated cost factor. The recent (2010) Deep Star Horizon oil well problems in the Gulf of Mexico again brought to the fore that gas hydrates often show up where they are not wanted. Gas hydrate control comes under the discipline of flow assurance in petroleum and chemical engineering. A comprehensive text in this area is the book by Sloan and Koh. ... 

The ion exchange capacity and the strong hydration control many properties of nanosized silica. For example, very high concentrations (up to 40% by wt) of stable... 

Kitmey, F. D., Re-Use of Returned Concrete by Hydration Control Characterization of a New Concept, 3rd CANMET/ACI Int Conf. of Superplasticizers and Other Admixtures in Conor., SP-119 19—40, Am. Concr. Res. Inst Special Publ. (1989)... 

Townsend. F. M., 1953, Vapor Liquid Equilibrium Data for Diethylene Glycol Water and Triethylene Glycol Water in Natural Gas Systems. Proc. Gas Hydrate Control Conf., University of Oklahoma. Norman, OK, May 5-6. 

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