CN2226664Y - Steam choking shaft gland for gas compressor - Google Patents

Abstract

The utility model relates to a novel steam choking shaft gland for gas compressors. The steam choking shaft gland is composed of the seal of seal cavities and comb teeth. One seal cavity is positioned at the position adjacent to medium end and is capable of being poured with water vapor; two seal cavities which are mutually communicate and are simultaneously connected with the same air extractor are arranged at atmospheric air end. Only one air extractor is used. The utility model has simple structure, low manufacturing cost and reduced consumptive steam quantity and no technical medium atmospheric dilution. The utility model is suitable for compressors with lower pressure such as the catalytic cracking air compressors of oil refineries.

Description

A kind of vapor lock axle envelope of gas compressor

The utility model relates to centrifugal gas compressor field of components in the mechanical engineering, is the vapor lock axle envelope of a kind of new structure of using of centrifugal compressor.

In chemical industry or the oil refining process units, the centrifugal compressor that process gas is used does not allow dielectric leakage, strict to the axle envelope, different according to process gas kind and pressure, adopt different axle envelopes, current used both at home and abroad axle envelope has floating ring shaftseal, mechanical shaft seal, the axle of bleeding seals, gas spiral fluted shaft envelope and vapor lock axle envelope, more than several sealing means all be found in the related standards of API (API), vapor lock axle envelope is an external the eighties technology newly developed, its seal element is a labyrinth seal, this sealing configuration and variation in pressure are as shown in Figure 1, [2] feed the water vapor of certain pressure to Seal cage b chamber from the steam inlet, labyrinth seal through two surveys of b chamber, steam and the machine interior processing medium moving toward compressor [4] one flow measurements mix, the place is extracted out from outlet [3] by an air ejector in the C chamber, delivers to the suction port of compressor again; Toward bearing housing [5] one flow measurements moving steam and air mixing, the place takes away with another air ejector in a chamber, enters atmosphere, among the figure, M is a processing medium, and S is a steam, A is an air, and arrow is represented flow direction, and the essence of this sealing is the combination seal that labyrinth seal and vapor lock constitute, its great advantage is simple in structure, because it is a kind of noncontact seal, no abrasion, good reliability, life-span is long

Actual conditions at China, requirement to centrifugal compressor axle envelope is a good seal performance, life-span is long, and is simple in structure, and operation and maintenance is convenient, cheap, operating cost is low, and meets the ability to bear and the resource situation of factory, and the complex structure that the said several envelopes in front have, the cost height is difficult to bear on the general factory economy; The needs that have are set up the sealing oil station; What have needs the supply of nitrogen as barrier gas, but the enterprise that has does not have the nitrogen resource, petrochemical plant all has abundant water vapor resource, use water vapor to do sealing gas, have a small amount of water vapor and enter compressor, this is to the manufacturing process did not influence, though the vapor lock sealability of current external application is better, the reliability height, simple in structure, use maintenance also more convenient, but through analysing in depth, discovery still has deficiency, and the one, processing medium and steam return the suction port of compressor together in the machine that air ejector is extracted out, have increased the quantity of circuit gas in the machine and the load of compressor; The 2nd, vapor pressure cuts down control with regulating, and air ejector has two, and the pipeline complexity causes some troubles of installing and using; The 3rd, use two air ejectors simultaneously, all extract a part of steam out, steam consumption is bigger,

The purpose of this utility model provides a kind of vapor lock axle envelope of improved gas compressor, the structure of this vapor lock axle envelope and variation in pressure are as shown in Figure 2, it still adopts labyrinth seal as seal element, it does not feed steam in the b chamber, but survey at media end one, inlet [3] is located to feed steam as barrier gas toward Seal cage C chamber, and the outlet [1] of a chamber and b chamber is connected same air ejector [6] simultaneously with [2], among Fig. 2, [4] be compressor, [5] are bearing housings, and S and A represent steam and air respectively, arrow is represented gas flow direction

Its body structure of the present utility model as shown in Figure 3, it is made up of Seal cage and labyrinth seal, at close media end, one Seal cage [13] that can feed the water vapor of blocking action is arranged, in atmosphere end Seal cage [11] is arranged, there is Seal cage [12] centre, Seal cage [11] and [12] are connected the air ejector of the little air of only extracting the part leaked steam out and being entered by air end simultaneously and take over [6], between Seal cage [11] and [12] and between sealing [11] and the atmosphere labyrinth seal [1] is arranged, labyrinth seal [9] is arranged between Seal cage [12] and [13], labyrinth seal [8] is arranged, between Seal cage [13] and the medium in accompanying drawing 3, [2] be axle sleeve, [3] be lock washer, [4] are the axle sleeve set screw nuts, and [5] are glands, [7] be the inlet that feeds steam, [10] are sealing gaskets.

According to the utility model, the steam that feeds Seal cage [13] (the C chamber among Fig. 2) enters in the machine respectively and Seal cage [12] through labyrinth seal [8] and [9], (the b chamber among Fig. 2) is because the interior pressure reduction of Seal cage [13] and machine is less, the steam flow that enters in the machine significantly reduces, part steam enters Seal cage [12], also have sub-fraction might enter Seal cage [11] (a chamber among Fig. 2) through labyrinth seal [1], but this partial amt is very little, can omit and disregard, the pressure that feeds steam cuts down without pressure regulation, and regulate with restriction orifice, as long as pressure ratio is greater than 2 (this point realizes easily) before and after guaranteeing restriction orifice, the pressure that feeds steam can automatic tracking axis seal pressure.

The utility model is simplified the general structure of sealing greatly, and is easy to operate, and its sealing effect can be with following example explanation.

Example, certain oil refinery Catalytic Cracking Plant Compressor.

Medium: oil gas

Media density: 1.2262Kg/m ³(under the standard condition)

Flow: 7800NM ³/ hour

Axle envelope place pressure: 0.15MPa

Rotating speed: 8000--9000rpm

Inlet temperature: 40--50 ℃

Shaft diameter: 130mm (sealing part)

Calculate through labyrinth seal and enter the interior steam flow of machine and the gas flow of extraction.The steam that injects enters in the machine respectively and the b chamber through two labyrinth seals of surveying, and pressure descends.Air leakage is calculated as follows: $G=\mathrm{\α\ΠDS}\sqrt{\frac{g(p_1^2-p_2^2)}{Z{P}_1{V}_1}}$

Wherein, α is an air leakage factor, and D is the sealing part diameter of axle, and S is a seal clearance, and g is gravity accleration (9.81M/S ²) P ₁For sealing preceding pressure, P ₂For sealing back pressure, V ₁For sealing preceding gas specific volume, Z is the labyrinth seal number of teeth, and in this example, the C chamber is 13 teeth in machine, and the C chamber is 6 teeth to the b chamber, is 5 teeth between a chamber and the atmosphere.Result of calculation: the steam flow that each end of compressor shaft drains in the machine is 29 kilograms/hour, steam flow to external leakage is 91.1 kilograms/hour, 20.8 kilograms/hour of the air quantities of extracting out, the vapor volume that injects is to enter in the machine and to the steam flow sum of external leakage, it is 120.1 kilograms/hour, all there is the axle envelope at these machine two ends, the steam total amount of injecting is 240.2 kilograms/hour, the steam flow that enters in the machine is 58 kilograms/hour, two ends can be with an air ejector, the gas gross of extracting out is (20.8+91.1) * 2=223.8Kg/ hour, and wherein to account for this compressor flowrate of 81.4%. be 7800NM to steam ³/ hour, standard condition lower density is 1.2262Kg/m ³, its mass flow rate is 9564.36Kg/ hour, the steam that enters in the machine is 58Kg/ hour, only accounts for 0.6% of compressor flowrate, can not produce any influence to mechanical property and manufacturing process.

If this compressor adopts original air extracting seal, every group of air ejector consumes steam 500Kg/ hour, extracts processing medium (cracking gas) out 200-300Kg/ hour, and annual pressing calculated in 8000 hours, and steam is by 40 yuan of/ton calculating of inside price, then

40 yuan/ton * 0.5 ton/hour * 8000 hours=160,000 yuan of vapour lossess

470 yuan/ton * 0.25 ton/hour * 8000 hours=940,000 yuan of cracking gas losses

Like this, with regard to economic aspect, just lose 1,100,000 yuan every year, the environmental pollution that causes is imponderable especially.

Have only loss of the steam of injection after using vapor lock sealing of the present utility model, amount to value every year and be 240.2Kg/ hour * 40 yuan/ton * 8000 hours=76864 yuan.Can save ten thousand yuan of 110-7.6864=102 like this every year.

Aspect the acquisition expenses of axle envelope equipment, floating-ring seal and mechanical seal are equipped with sealing oil system because of need, and its purchase commodity accounts for the 20--40% of compressor bank overall cost.Be generally ten thousand yuan of 110--150.From the sealing of the gas spiral scouring machine tool of external introduction, 150,000 dollars in the every cover of price, and the actual cost of every of the utility model is less than 100,000 yuan.Be that new compressor bank is equipped with the vapor lock sealing in the utility model, purchase commodity can be saved more than 100 ten thousand yuans.

Vapor lock axle in the utility model envelope requires Seal cage pressure greater than working medium pressure, so the utility model is applicable to the compressor that pressure is lower, and the catalytic cracking air compressor of oil refinery for example.

Claims (1)

1. A kind of vapor lock axle envelope of gas compressor, form by Seal cage and labyrinth seal, it is characterized in that, near media end a Seal cage [13] that can feed the water vapor of blocking action is being arranged, in atmosphere end Seal cage [11] is arranged, there is Seal cage [12] centre, Seal cage [11] interconnects and is connected simultaneously the air ejector [6] of the little air of only extracting the part leaked steam out and being entered by air end with [12], between Seal cage [11] and [12] and between Seal cage [12] and atmosphere by labyrinth seal [1], labyrinth seal [9] is arranged between Seal cage [12] and [13], labyrinth seal [8] is arranged between Seal cage [13] and the medium.