Waste heat boiler in refineries and petrochemical plants may be watertube boiler or shell boiler. The latter are of particular design and mostly process gas coolers, with process gas within the tubes and boiler water around the tubes. The operational pressure is up to 140 bars, but their steam production regularly do not exceed 200 t/h.water cycle in a boiler plant. Depending on the steam generator operating pressure, we have either low pressure ( LP), medium pressure ( MP) or high pressure ( HP) boilers.Table 15 provides the usual lines separating each egory.
where fuel is burned and flue gas is transported. the basic structure of a fire tube boiler consists of tubes. Fire tube boilers are used for supplying steam or warm water in small scale appliions. Usually boilers of this type are customized for liquid or gaseous fuels. natural gas and biogases. like oil. .High Pressure Boiler Inspection Procedures (with Checklist)A highpressure boiler is defined as a boiler in which steam or vapor is generated at a pressure equal to or greater than 15 psig, or a boiler in which water is heated at a temperature of 250°F and a pressure greater than 160 psig, when water is heated for use external to the boiler
A low pressure firetube boiler can usually tolerate high feedwater hardness with proper treatment while virtually all impurities must be removed from water used in some modern, high pressureHighPressure Boiler Water Treatment. Highpressure boilers usually have areas of high heat flux and feedwater, composed of demineralized makeup water and a high percentage of condensate returns. Phosphate is a pH buffer in this program and limits the localized concentration of caustic. Deposition reduces heat transfer from boiler tube
Salt in Marine Boilers. From: Henry Evers, LL.D., Steam and the Steam Engine, London, William Collins, Sons, and Company, 1873.The author was Professor of Mathematics and Applied Science at the Charles Science School, Plymouth. Notes: Page numbering and line breaks have been retained images are found at the bottom of the page on which they may appear higher in the original text layout.Feed Water Treatment to Avoid Corrosion Makeup water to steam boilers should be treated with oxygen scavengers to avoid serious corrosion problems Maximum Flow Velocities in Water Systems Water velocities in pipes and tubes should not exceed certain limits Steam Boiler Rating and Feed Water Temperature Boiler output and feed water
Boilers 2.3 Boiler Types and Classifiions There are virtually infinite numbers of boiler designs but generally they fit into one of two egories: Fire tube or "fire in tube" boilers contain long steel tubes through which the hot gasses from a furnace pass and around which the waterCorrosive Effects of Chlorides on Metals 143 2.3.2 Pitting growth In presence of chloride ions pits are growin g by autoalytic mechanism. Pitting corrosion of a stainless steel is illustrated in the Figure 1. The actual pitting corrosion phenomenon is shown on propeller shaft of high speed craft, and the pit depth was measured with dial
Both the Water Tube and the Fire Tube Boiler have the following components: HEAT SOURCE A gas, oil, or coal burner heats the water in the oiler. WATER SOURCE The makeup water entering the boiler from the local water supply is the water source. It may be preheated (in large systems it is nearly always preheated) to drive off dissolved oxygentubes – another high wastage area of this boiler waterwalls, flue gas temperature range 1000 – 1100 F, tube metal temperature uniform at ~550 F, uneven gas flow through Pass 2 with lower velocities along the roof. Predominant corrosion in both areas is suspected to be a combination of mechanisms 1, 2, and 3 as described in Introduction.
6. CARE OF HIGH PRESSURE DRUM TYPE BOILER DURING CONDENSER TUBE LEAKAGE 6.1. Boiler water regime requires careful monitoring control and adjustment whenever condenser tube leakage is suspected or confirmed. The condenser tube leakage brings large amount of chlorides into the condensate and consequently into the feed water.Corrosive Effects of Chlorides on Metals 143 2.3.2 Pitting growth In presence of chloride ions pits are growin g by autoalytic mechanism. Pitting corrosion of a stainless steel is illustrated in the Figure 1. The actual pitting corrosion phenomenon is shown on propeller shaft of high speed craft, and the pit depth was measured with dial
The following are specified limit for high pressure boiler from different organization: ASME Guidelines for Water Quality in Modern Industrial Water Tube Boilers for Reliable Continuous Operation:Boiler Feed Water Boiler Water Drum Pressure (psi) Iron (ppm Fe) Copper (ppm Cu) Total Hardness (ppm CaCO3) Silica (ppm SiO 2) Total Alkalinity**In boiler systems, nearly all problems related to premature water and firetube failure, unexpected performance loss, and system failure can be traced to water chemistry and treatment. Taking the steps to develop and maintain an efficient and reliable watertreatment program will ensure a
Water chemistry sensors for both feed water and boiler need monitoring as any impurities in this gets concentrated and gets carried over in the steam. Conductivity controls for water blowdown in the drum type boiler are a method to remove such concentrate. Conductivity is just one of many factors to monitor. Changes in conductivity readings in various area gives a good clue to operators toBypass high pressure cut off of the boiler. Arrange the boiler fire rate to a maximum. Safety valve will be lift during the test. The test is carried out as long as the water permits in the boiler. Accumulation pressure should not exceed 10% of working pressure in the specified time. Specified time is 15 mins for a smoke tube boiler and 7 mins
HP and LP Differences • High pressure – Makeup water is very pure and corrosive • Low level of dissolved solids – Based on coordination of phosphate and pH so that no free caustic exists – Lower chemical treatment levels – Lower tolerances for variations in chemical levels and TDS – Production of high purity steam • Low pressure – Based on phosphate precipitationEXCERPTS FROM: ASME BOILER AND PRESSURE VESSEL CODE SECTION I − POWER BOILERS 2010 EDITION INTRODUCTION This Code covers rules for construction of power boilers1, electric boilers2, miniature boilers3, high−temperature water boilers4, heat recovery steam generators5, and certain fired pres
Chlorides Limits In High Pressure Fire Tube Boiler Water,The pressure generated in a different way in steam boiler and hot water boiler. In a steam boiler, the water turn from liquid into gas after absorbing heat and its volume increases. The boiler is a closed container, so the boiler pressure will rise. The pressure of hot water boiler comes from the upper tank or the pump worked for circulating• Bouncing water line in the boiler can be both system and water composition induced. • Most often it is system related involving sudden pressure drops. • A three element feedwater system can help solve sink/swell problems in the boiler. • Sink/swell, foaming and priming can lead to carryover which can lead to water hammer.
I'm trying to look for limits and guidelines about chloride content in the water for high pressure coal fired boiler (meassured in makeup water and boiler drum). I have foung some information but it's so dispersive, I've seen limits from 12 PPB to 50 PPM (more than 4000 times difference).Fire tube or "fire in tube" boilers contain long steel tubes through which the hot gasses from a furnace pass and around which the water to be converted to steam circulates. (Refer Figure 2.2). Fire tube boilers, typically have a lower initial cost, are more fuel efficient and easier to operate, but they are limited generally to capacities of 25 tons/hr and pressures of 17.5 kg/cm 2.